Bulletin No. 312 (

A, Economic Geology, 92 

D, Petrography and Mineralogy, 

E, Chemistry and Physics, 50

DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

CHAKLKS D. WALCOTT, DiHECTOR

SPECIAL REFERENCE TO GEOLOGIC

EUGENE C. SULLIVAN

WASHINGTON

G O V E R N M E N T F K 1 N T ING O Y Y I C E 

190T

CONTENTS.

Page.

Introduction.............................................................. 5

Outline of earlier work.....:................................................ 7

Filtration and diffusion................................................ 7

Chemical reaction...................................................... 10

' Alkaline solution................................................... 28

Precipitation of acid ion........................................... 30

Influence of calcium carbonate..................................... 31

Application of mass law....................................^........ 33

Influence of concentration.......................................... 34

Experimental work........................................................ 37

Method of procedure.................................................... 37

Experimental results................................................... 38

Kaolin and cupric sulphate........................................; 38

Influence of surface................................................ 39

Orthoclase and salt solutions........................................ 40

Orthoclase and cupric sulphate.:.................................... 41

Influence of concentration.. ........................i ........... 42

Influence of temperature........................................ 42

Orthoclase with cupric sulphate and sulphuric acid.................. 43

Orthoclase and cupric nitrate....................................... 43

Orthoclase and cupric chloride..................................... 44

Orthoclase and silver sulphate....................^.................. 44

Orthoclase and lead nitrate......................................... 44

Orthoclase and gold chloride....................................... 44

Orthoclase and zinc sulphate........................................ 45

Kaolin and zinc sulphate........................................... 45

Orthoclase and ferrous sulphate..................................... 4.6

Kaolin and ferrous sulphate........................................ 46

Orthoclase and ferric sulphate....................................... 46

f Orthoclase and manganous sulphate................................. 47

Qrthoclase and nickel sulphate..................................... 47

Orthoclase and magnesium sulphate................................. 47

t. Orthoclase and calcium chloride.................................... 48

Orthoclase and strontium chloride................................... 48

Orthoclase and barium chloride.................................... 49

1 Orthoclase and potassium chloride................................... 49

Orthoclase and sodium chloride.................................... 50

Orthoclase and sulphuric acid....................................... 50

Orthoclase and carbonic acid........................................ 51

Microcline and cupric sulphate...................................... 51

Albite and cupric sulphate......................................... 51

Enstatite and cupric sulphate....................................... 52

Augite and cupric sulphate........................................ 52

3
4 CONTENTS.

Experimental worlt Continued.

Experimental results Continued. Page.

Anthophyllite and cnpric sulphate................................... 53

Amphibole and cupric sulphate..................................... 53

Garnet and cupric sulphate......................................... 54

Olivine and cupric sulphate......................................... 54

Vesuvianite and cupric sulphate....... I............................ 55

Epidote and cupric sulphate ........................................ . 55

Prehnite and cupric sulphate....................................... 56

Tourmaline and cupric sulphate..................................... 56

Muscovite and cupric sulphate..................................... 56

Biotite and cupric sulphate........................................ 57

Talc and cupric sulphate........................................... 57

Shale and cupric sulphate............................. 5............ 58

Clay gouge and cupric sulphate..................................... 58

Clay gouge and silver sulphate............ '. ......................... 59

Calcite (Iceland spar) and cupric sulphate.......................... 59

Fluorite and cupric sulphate........................................ 60

Pyrite and cupric sulphate.......................................... 60

Glass and cupric sulphate........................................... 60

Possible application to geologic phenomena............... v ............ 60

Forrn of precipitation................................................... 61

Summary.............................................................. 64

Index.................................................................... 65
THE INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS, 

WITH SPECIAL REFERENCE TO GEOLOGIC PHENOMENA.

By EUGENE C. SULLIVAN.

INTRODUCTION.

The work.described in the following pages was undertaken in the 

chemical laboratory of the United States Geological Survey, in an 

attempt to apply chemical methods to the investigation of geologic 

processes and especially of the secondary deposition of ores.

The concentration of metals by water solutions in deposits of 

sufficient magnitude to constitute ore bodies involves two processes 

the taking up of the metal from its original seat, and its redeposition 

at a point favorable for accumulation. As to the first process, water, 

and especially water solutions, must be assumed to attack and dissolve to a greater or less extent all minerals with which they come 

into contact. Various causes will lessen or increase the extent of this 

action in the case of any particular mineral; but in every instance, no 

matter how infinitesimal the quantity dissolved as measured by ordinary laboratory' standards, 'the solubility is capable, through long 

periods of time, of producing important geologic effects. Tho process 

of solution therefore involves no special difficulties.

Chief interest will center on the deposition, in one spot, of a mass of 

metal gathered by the solvent waters from over a wide range of country. It is important both from a scientific and from an economic 

point of view to know what agent determines that the metal from 

an immense volume of solution, which has passed undisturbed 

through a section of rock very large in comparison with that in 

which it is finally concentrated, shall be deposited in a certain limited 

area, to constitute a valuable body of ore. Physical conditions, such 

as comminution of the rock, stagnation.of the carrying waters, local 

variations in temperature, or mingling of solutions, may have been 

important factors. They become important, however, chiefly in so 

far as they accelerate or otherwise modify chemical reactions, and a 

thorough knowledge of the reactions possible under natural conditions seems to be a necessary foundation for study along this line.

5
6 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

With, this in view some of the changes that take place at ordinary 

temperature when water solutions are brought into contact with 

rock-forming minerals have been examined.

The result has been, in a word, to make it apparent that chemical 

reaction between silicates and salt solutions is a very general phenomenon, taking place to a decided extent immediately upon contact, and that the outcome is mainly an exchange of bases in chemically 

equivalent quantities between solid and solution; the metal of the 

dissolved salt is precipitated and an equivalent quantity of silicate 

is decomposed and its bases enter the solution. Salt solutions as 

decomposing agents are much more active than pure water and are 

comparable with acids in this respect.

A review, as brief as possible, has been made of our present knowledge of the reactions between salt solutions and silicates in so far as 

it seems likely to have bearing on geologic work. The fact that no 

connected survey of this field exists and that the literature is scattered, most of the early papers having appeared in agricultural journals not readily accessible as a rule to the geologist and mineralogist, 

perhaps justifies the expectation that such an outline will prove useful. By no means all of the published papers bearing on the subject are mentioned in the text; the treatment has been confined to 

the briefest statement consistent with the development of the facts. a

The work described in the present paper is but an incomplete outline of a part of the field. Important work to be done suggests itself 

at once.

The investigation should be extended both as to salt solutions and 

as to minerals.

The character of the precipitates obtained by interaction between 

salt solutions and minerals should be investigated by grinding the 

minerals in the solutions, which should give the end products in a 

comparatively short time by abrading the surfaces already acted upon 

and continually exposing fresh material to the solution.

The action of minerals on mixtures of salts in solution, and thus 

possible natural processes of separation, should be studied.

Where separation of metals has taken place, caused apparently by 

difference in character of wall rock, the opportunity and desirability 

of laboratory investigation are obvious.

Equilibrium conditions are still to be worked out. These are of 

great interest, both scientifically and practically, as showing the possibility of decomposition or the direction of decomposition of a mineral 

as dependent on the make-up of the solution with which it is in contact.

o References to the literature on this and related subjects are assembled in Cameron, F. K., and Bell, 

J. M., The mineral constituents of the soil solution: U. S. Dept. Agr., Bull. Bur. Soils No. 30, 1905.
EARLIER WORK: FILTRATION AND DIFFUSION. 7

It can not be doubted that the collection of definite comparative 

data along these lines will also throw light on questions of mineral 

constitution.

The possible practical effects of diffusion through wall rock, etc., 

should be ascertained experimentally.

OUTMNE OF EARLIER WORK.

FILTRATION AND DIFFUSION.

That water is improved for drinking purposes by filtration through 

sand was known as early as the time of Aristotle."

Francis Bacon b writes of a method of obtaining fresh water practiced on the coast of Barbary: "Digge a hole on the seashore somewhat above high-water mark and. as deep as low-water mark, which 

when the tide cometh will be filled with water fresh and potable." 

He also remembers "to have read that trialhath been made of salt 

water passed through earth through ten vessels, one witnin another, 

and yet it hath not lost its saltness as to become potable/' but when 

"drayned through twenty vessels hath become fresh."

Dr. Stephen Hales c mentions, on the authority of Boyle Godfrey, 

that "sea water being filtered through stone cisterns, the first pint 

that runs through will be like pure water, having no taste of the 

salt, but the next pint will be as salt as usual."

Berzelius filtered solutions of common salt through .sand and 

found the first portions of the filtrate fresh. Matteucci d obtained 

similar results with other salts.

Although such phenomena are attributable to adsorption an accumulation of dissolved substance on the contact surface liquid-solid, 

the filtering medium with its large surface affording favorable conditions for such an effect the possibility is to be considered that we 

are dealing with the result of the different diffusivity of the constituents of a solution. Each substance has its own velocity of diffusion, and where free passage is interfered with, as in the filtration 

of a water solution; the water, traveling more rapidly than the salts, 

may come through first.

Krawkow, 6 on comparing pure water and solutions side by side, 

found that the water moved more rapidly through a soil. Briggs 

obtained similar results, which he attributed to the greater viscosity 

of the solutions/

a Sachsze, Agriculturchemie, p. 14C.

t> In Sylva Sylvarum, quoted by Way, Jour. Roy. Agr. Soc., vol. 11,1850, p. 310. 

c In a paper read before the Royal Society in 1730 on "Some Attempts to make Sea-Water Wholesome," cited by Way.

<* Sur les phenomeiies physiques des corps vivants, Paris, 1847, p. 29, cited by Way. 

«.Tour. fiir Landwirtschaft, vol. 48, 1900, p. 209. 

/ U. S. Dept. Agr., Bull. Bur. Soils No. 19, 1902. ' .
8 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

King,® on filtering very dilute soil solutions (containing carbonates, sulphates, nitrates, and phosphates) through a porcelain filter, 

observed an increase in the concentration of the unfiltered portion. 

The matter was followed up by Briggs, who found in the case of 

N/1000 solutions of potassium, sulphate, sodium, bicarbonate, and 

potassium nitrate a decrease in the concentration of the filtrate and 

an increase, amounting to 2 or 3 per cent, in the concentration of 

that part of the unfiltered liquid nearest the filter. Sodium carbonate solution (N/1000) suffered the greatest loss (15 per cent) on 

filtering. "This would follow from the tube behaving as an imperfect semipermeable membrane, allowing the water to pass through 

the filter walls more readily than the dissolved salt."

When the material is somewhat readily penetrable but slight separation will be effected in this way. With relatively impervious 

material, however, important separation of the constituents of a 

solution is possible, as in dialysis of a salt solution through an animal membrane, leaving behind colloid matter, the velocity of diffusion of which is practically nil as compared with that of electrolytes. 

Still less pervious are the so-called semipermeable membranes, such 

as a film of precipitated cupric ferrocyanide, which permit the solvent to pass, but not the dissolved salt.

G. F. Becker 6 suggested the possibility of natural concentration 

of metals by dialysis, the confining rock of an underground water 

channel acting as a septum.

Kohler c describes experiments on the filtration of salt solutions 

through kaolin. Cupric sulphate and lead nitrate solutions, after 

passing through a layer of washed kaolin (some 20 cm3 of dilute 

solution with 25 grams kaolin in an ordinary glass funnel), contained but very little of the metals. Sodium chloride, sodium sulphate, and magnesium sulphate solutions under similar treatment 

took on acid reaction. Kohler attributes these results to adsorption a selective concentration of dissolved substance, here the bases 

of the salts, on the surface of a solid and discusses the possibility 

that concentration of metals by this means has led to the formation 

of ore bodies.

The writer, on filtering magnesium chloride and sodium chloride 

solutions through kaolin, as described by Kohler, found the filtrate 

faintly but distinctly acid to litmus. With sodium chloride the first 

4 or 5 cubic centimeters of filtrate had about the same degree of 

acidity, as a solution 0.001 normal. Such acidity seems sufficiently accounted for by the exchange of the magnesium and sodium 

of these salts in part for the iron and aluminum of the kaolin, the 

salts of the latter metals undergoing extensive hydrolysis in dilute

« Briggs, U. S. Dept. Agr., Bull. Bur. Soils No. 30, .1002, p. 30. 

6 Mineral Resources U. S. for 1802, U. S. Geol. Survey, p. 156. 

eZeitschr. prakt. Geol., vol. 11, 1903, p. 49.
EARLIER WORK: FILTRATION AND DIFFUSION. 9

solution. The acidity observed is of the same order of magnitude 

as the quantity of trivalent bases found in dilute copper sulphate 

solution after contact with kaolin.

The acidity of a salt solution after filtration through a substance, 

such as kaolin, through which the liquid diffuses but slowly, may be 

due to some extent to the greater velocity of diffusion of the acid con- 

.stituent of the salt, which is present owing to hydrolysis the splitting up of a salt into its acid and base by the action of water:

CuS04 .+ 2H2 0 = Cu(OH) 2 + H2S04 . 

Fe,(S04 ) 8 + 6H20 = 2Fe(OH)3 + 3H2S04 .

In water solutions of salts of heavy metals the base is present, to a 

greater or less extent, in the colloidal condition, and colloids are 

marked by their very slow rate of diffusion.

P. Rohland 0 states that a certain clay was permeable to crystalloid 

solutes, such as sodium chloride, barium chloride, cupric sulphate, 

potassium clichromate, etc., while it was impermeable to colloids, such 

as ferric hydroxide, silicic acid, and dissolved starch.

Spring & observed the separation of acid and base by diffusion and 

the consequent deposition of the metal hydroxide in media similar in 

character to a suspension of clay in water. The suspended material 

in one case, gum mastic (an emulsion of the resin in water, a milky 

liquid obtained by pouring an alcoholic solution of mastic into water); 

in another, silica was superposed in a column 15 cm. in height on a 

concentrated solution of the salt and diffusion allowed to take place. 

Coagulation or sedimentation of the solid was caused immediately 

and the particles descended to the point at which their density and 

that of the solution were the same. The height to which fiocculation. 

extended was not the same for different salts. Above the cupric sulphate solution the layer in which ffocculation took place reached a 

height of 11.5 cm. The copper had diffused upward not more than 7 

cm., as shown by the absence of color and by the ferrocyanide test in 

a portion removed by means of a pipette. Sulphuric acid was, however, present in the higher 4.5 cm. Other salts aluminum chloride, 

ferric chloride, alum, magnesium chloride, zinc chloride gave similar 

results. Above the layer of salts in each case free acid was found.

The nocculent deposit above the cupric sulphate solution, removed 

with a pipette and washed on a filter, was of yellow-green color and 

contained cupric hydroxide. Aluminum, iron, zinc, and magnesium 

were shown to be present in mastic precipitated by means of their 

salts in the same manner.

If, however, the turbid mastic was shaken with cupric sulphate or 

aluminum chloride solution, the flocks of mastic which formed did not

oZeitschr. Elektrochein., vol. 11, 1005, pp. 455-450. 

6 Bull. Acacl. roy. Belgique, vol. 70, 1900, p. 490.
10 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

retain copper or aluminum. Washed on a filter and tested, they gave 

no reactions ior those metals.

"The decomposition of the salts depends then only on the condition 

that diffusion intervenes and that, in any case, agitation does not 

bring base and acid into contact." "The mastic suspension apparently performs the same office as a permeable wall in the sense that it 

retains the molecules of hydroxide in order to precipitate with them, 

while it allows the molecules of acid, to pass more freely."

The same results were obtained when silica was used as thp suspended material instead of mastic.

Bruni and Vanzetti a have shown that in the diffusion of cupric 

sulphate solution through gelatine the sulphuric acid separated by 

hydrolysis travels appreciably faster than the base. The blue solution is preceded by a colorless layer containing acid. With ferric 

chloride similar results were observed.

A further cause to which may be attributed acidity of a solution 

after contact with a hydrated silicate is double decomposition between 

the salt and silicic acid, or alumino-silicic acid, the hydrogen of the latter replacing in solution the metal of the salt. Such action takes place 

readily enough in alkaline solution: H2Si03 + 2KOH = K2Si03 + 2H20. 

It is slight if at all measurable with neutral salts.

CHEMICAL REACTION.

That solutions ma}^ be deprived in-part of their dissolved substances 

by sandy material has therefore long been well known. The fact 

that clays, soils, etc., enter into chemical exchange with solutions, 

giving off some things and taking up others, appears to have first been 

specifically recognized by H. S. Thompson, an Englishman, who published his observations in 1850.& Thompson found that ammonium 

sulphate solution filtered through soil or clay exchanged its ammonium for calcium. The filtrate contained chiefly calcium sulphate. 

Similar experiments with ammonium carbonate also showed a reaction between the dissolved substance and the solid.

The matter was taken up and studied in detail by J. Thomas Wa,y, 

chemist to the Royal Agricultural Society, whose work is described in 

the journal of the society for 1850 and following years. c Way found 

that when an ammonia solution passed through soil or clay the percolating liquid contained neither ammonia nor ammonium salts. His 

first experiment was carried out in a tube 20 inches long and of threefourths inch internal diameter, which when about two-thirds filled 

contained 2,800 grains (180 grams') of soil. The soil used had been 

dried in air. A 1.5 per cent solution of ammonia was used, and the

aAtti Reale Acad. Lincei [5] 15 II, December, 190G, pp. 705-715. 

& Jour. Koyal Agr. Soc., vol. 11,1850, pp. 68-74. 

.c Jour. Royal Agr. Soc., vol. 11, 1850, pp. 313-379; vol. 13, 1852, pp. 123-143; vol. 15, 1854, p. 491.
J&ARLJER WORK: CBLEMIOAL ENACTION. 11

first portions took from one and a half to two hours to percolate 

through the column. When one ounce (30 cm. 3 ) had passed, it was 

tested and found to contain no trace-of ammonia or ammonium salts. 

Quantitative experiments showed that the soil had taken up ammonia 

equal in amount to about three-tenths of 1 per cent of its own weight. 

The result was the same on forcing the solution through by pressure, 

so that contact lasted but a few seconds.

Solutions of salts, such as the nitrates, chlorides, and sulphates of 

ammonium, potassium, sodium, and magnesium, filtered through soil 

gave up the respective bases entirely and received in exchange calcium from the soil. In the case of ammonium chloride it was shown 

that the chlorine content of the solution was not affected by contact 

with the soil. Filtration through a white pottery clay led to similar 

results, sodium being in this instance the substituting base; again 

the concentration of the chlorine was unchanged.

Way had no difficulty in proving that the active ingredient of the 

soil in absorption of bases was its clay. Owing to the relatively 

small proportion of base taken up by clay (a few tenths of' 1 per cent of 

its weight), he concluded that the action was due, not to the clay as a 

whole, but to some constituent present in small quantity. Evidence 

tending to show that this constituent was a hydrated alumino-silicate 

of alkali or alkaline earth he obtained by demonstrating that artificial 

alumino-silicates of' sodium, potassium, calcium, magnesium, and 

ammonium were capable of exchanging bases with salt solutions 

exactly as the soils had done. It does not, however, follow that the 

soil contains zeolitic silicates which are responsible for such- action, as 

has been sometimes assumed.a Apparently any silicate, including the 

feldspars, is capable of entering into these reactions.

Sodium alumino-silicate was prepared by mixing sodium silicate and 

sodium aluminate solutions. The precipitate washed with water and 

dried was a white powder practically insoluble in. water and containing 

some 18 per cent of soda. The other compounds were similarly prepared or were obtained from this one by substitution the amm.onium 

compound, for instance, by digesting with ammonium chloride solution, which removed sodium and. formed an ammonium aluminosilicate.

Way clearly recognizes the nature of the phenomena with which he 

is dealing as the chemical replacement of one base by another. He 

says, for instance: 6 ' 'It will be abundantly evident as we proceed that 

the absorptive power of soils is something entirely different from a 

surface attraction." Again, "the quantity of lime acquired by the 

solution corresponded exactly to that of the ammonia removed from 

it the action was therefore a true chemical decomposition." 0

a This point has been emphasized by Merrill, G. P., Rocks, Rock-W.eathering, and Soils, New 

York, 1906, pp. 362-365. ' 

bLoc. cit. ; 1850. 

cLoc. cit., 1852.
12 INTERACTION BETWEEN MINERALS AND WATEK SOLUTIONS.

«

Way investigated also the influence of concentration and of temperature. The amount of exchange between solution and solid was found 

to increase with increasing concentration of the solution used, and to 

increase also, although but slightly, with rising temperature.

He observed that absorption was greater from alkaline than from 

neutral solution, and that absorption of free alkali (potassium hydroxide) was increased by previous boiling of the clay with hydrochloric 

acid. . The cause of the latter phenomenon, the decomposition of 

silicates with resulting formation of colloid silica or silicic acids, he did 

not recognize.

/ The relative ease with which the bases enter into these substitution reactions appears to depend somewhat upon the conditions of 

experimentation. Way makes the statement that sodium, potassium, 

calcium, magnesium, and ammonium will each be dislodged from 

its alumino-silicate by a salt of any of those following it in the order 

given. a Potassium should be with ammonium as one of the bases 

least readily replaced from silicates by substitution, not, as Way has 

it, at the other end of the series. He erroneously states that these 

changes are not reversible.

The capacity of the feldspars to enter into these reactions was not 

recognized by Way. He says :& "It is only in the state of hydrates that 

the double silicates possess the property in question; this is the reason 

why feldspar and albite substances, of the same composition in all 

other respects as the artificial silicates, are devoid of the power of 

absorbing ammonia."

Important to our present purpose, as illustrating the practical effect 

of silicates on organic matter, is the same author's description of the 

action of clay on barnyard liquors. These filtered through clay lost 

their color, odor, and taste. Sand was comparatively inefficient in 

this respect, although, as shown by Angus Smith/ it had some oxidizing action, changing the nitrogen of organic compounds into nitrate.

Eichhornd studied the reactions between salt solutions and individual natural minerals, such as chabasite, (Ca,Na2 )Al2 (Si03 ) 4 ,6H2 0, 

and natrolite, Na2Al2Si3O10 ,2H3O. The following table shows the 

extent of . substitution obtained with dilute solutions of the salts 

named. Four grams chabasite, finely powdered, 4 grams salt, 400 

cm3 water were taken; contact was for ten days, presumably at room 

temperature:

Composition of chabasite as affected by sail, solutions.

CaO ..........................................................

NsisO ........................................................

Before 

action 

of salts.

Per cent. 

10.37

0.42

After 

action 

of NaCl.

Per cent. 

 6.65

5.40

After action of 

NfhCI.

Per cent. 

4.15

o Loc. cit., p. 132. b Loc. cit., p. 135. "Cited by Way, loc. cit. <* Pogg. Ann., vol. 105, 1858, p. 126.
EARLIER WOKK: CHEMICAL REACTION. 13

Exchange lias taken place in approximately equivalent quantities. 

Sodium carbonate and ammonium carbonate with chabasite gave 

similar results. The ammonium substitution product gave off no 

ammonia on heating to 100°, yet in contact at ordinary temperature 

with a solution containing chloride of calcium, sodium, potassium, or 

magnesium the ammonium was removed and the other base substituted. Eichhorn showed that these substitutions are reversible. 

After treatment with sodium chloride the altered chabasite, for instance, gave up sodium to calcium chloride solution. "The bases," 

he says, "appear to be mutually replaceable." He recognized the 

fact that some substitutions took place more readily than others, and 

as a measure of such ease of substitution he ascertained the time in 

which the salts of various bases drew calcium into solution from 

chabasite. The order found was as follows, those first in the list 

extracting a detectable amount of calcium most rapidly: Potassium, 

sodium, lithium, barium chlorides; cadmium nitrate; zinc, strontium, 

magnesium chlorides. This order, he remarks, may be modified by 

varying concentration of the salts.

Henneberg and Stohinann" in 1858 described experiments confirming Way's results. They found that ammonium or potassium 

hydroxide, carbonate, nitrate, chloride, or sulphate in contact with 

soils of the widest variation in character gave up ammonium or potassium to form insoluble compounds. In the case of the nitrate, 

chloride, and sulphate salts almost neutral in water the acid content of the solution remained unchanged, the acid which had been 

combined with the absorbed ammonium or potassium" reappearing in 

combination with calcium or magnesium. From solutions of phosphates, silicates, etc. salts alkaline in water the acid radical also 

was in part precipitated. Sodium and magnesium salts were found 

to behave like salts of ammonium and potassium. The following 

data are typical of those obtained in these experiments. The figures 

show the number of grams of ammonia (NH3) absorbed by 100 grams 

of soil from 200 cm3 of solutions of the concentrations indicated. 

Ammonia absorbed by soil from salts oj ammonium.

NHiOH. ..............................

N1-UC1. ................................

NH,N08 ... ........................... .

(NHOaSO,.. ...........................

(NH«) 2HPO«. .........................

0.05 gram 

equivalent 

per liter 

(0.17g. NH3 

in 200 cm3).

0.058

0.0545

 0.054

0.057

0.1 gram 

equivalent 

per liter 

(0.34 g. NH 3 

in 200 cm3).

0.095

0.071

0.080

0.086

0. 141

0.2 gram 

equivalent 

per liter 

(0.68 g. NH 3 

in 200 cm3).

0.149

0.107

0.106

0.118

0.206

0.5 gram 

equivalent 

per liter 

(1.7 g. NE, 

in 200 cm3).

0. 118

[0.170V]

The amount of ammonium taken from solution is about the same 

whether it is present as chloride, nitrate, or sulphate salts which in 

water solution are almost neutral to indicators. With ammonium

a Ann. Chem., vol. 107, 1858, p. 152; more fully, Jour. Landw., vol. 3, 1859, p. 25.
14 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

hydroxide and ammonium phosphate alkaline in water solution 

the quantity absorbed is somewhat greater.

Henneberg and Stohmami found also that the greater the quantity 

of solution taken with a fixed quantity of soil the greater was the 

absorption. In certain cases, for instance, doubling the amount of 

solution increased the amount of absorption one-fifth. The time of 

contact, as Way had already shown, was of little influence. Absorption was not greater in one hundred and sixty-eight hours than in four.

The authors compare the quantities of ammonium precipitated and 

calcium dissolved, but remain in doubt as to whether substitution in 

chemically equivalent amounts has taken place, possibly because they 

fail to determine the bases other than calcium taken from the soil by 

the solutions.

Peters a investigated the action of soils on solutions of potassium 

salts, making complete analyses of the solutions after contact with the 

soils. The tables following indicate the general nature of the results. 

The data in the first table, obtained in four experiments carried out 

under conditions supposed to be identical, with 250 cm3 potassium 

chloride solution (N/20, equivalent to 2.36 grams K2O per liter) and 

100 grams soil, allow some estimate of the accuracy attained. The 

lack of agreement is undoubtedly due in part to actual nonuniformity 

in the experimental results and in part to the errors of analysis. 

Action of soils on potassium chloride solution.

K absorbed equivalent to grams KzO.

0.2130...

0.2015...

0.1976...

0.1841...

Found in 250 cm3 solution 

CaO.

0. 1176 

0. 1176 

0.1120 

0.1064

MgO.

0.0032 

0.0048 

0.004S 

0.0050

K2O.

0.375S 

0. 3873 

0.3912 

0.4047

Na2O.

0.0463 

. 0.0439 

0.0370 

0.0450

As showing the influence of the anion and of concentration the following data derived from the contact of 100 grams soil with 250 cm3 

solution may be quoted from Peters:

Influence of anion and of concentration in action of soils on -solutions of potassium salts.

Salt.

KCl.............. ......................... ............................ KCI ..............................................:...................

KCl..................................................................

KCI..................................................................

KCl ..................................................................

K^SO^.. ..............................................................

K2SO<...... ..........................................................

KNO3 .. ..............................................................

KsCOa-..-.... ....-..-..-..-..-.-....-....-.-.-,...-....-............

KsCOs........ .......................................................

KOH...... ..........................................................

KOH...... ..........................................................

Concentration.

N/80 

N/40 

N/20 

N/10 

N/5 

N/20 

N/10 

N/20 

N/20 

N/10 

N/20 

N/10

"K, expressed as grams 

KsO.

Originally 

in 250 cm3.

0. 1472 

0.2944 

0.5888 

1.1776 

2.3552 

0.5888 

1.1776 

0.5888 

0.5888 

1.1776 

0.5888 

1. 1776

Absorbed 

from 

250 cm3.

0.0988 

0.1381 

0. 1990 

0.3124 

0.4503 

0.2089 

0.3362 

0.2516 

0.2792 

0.4705 

0.4018 

0. 7347

aLandw. Vers.-Stat., vol. 2, 1860, p. 113.
EAELIEE WORK: CHEMICAL REACTION. 15

Here again absorption from the salts in neutral solution is roughly 

the same whatever the form of combination, while from alkaline solution the absorption is greater. The slow increase in absorption as 

concentration rises is also exemplified. Peters found that the chloride 

and sulphate ions were not absorbed, while the phosphate ion was. 

The following order of absorption is given for the bases-, that absorbed 

in greatest quantity being placed first: Potassium, ammonium, 

sodium, magnesium, calcium.

The bases dissolved from the soil were replaced in very nearly 

equivalent quantity by the absorbed base. From "bases dissolved" 

has been subtracted that quantity which is dissolved from the soil by 

water alone.

Comparison of bases dissolved with potassium absorbed from chloride solution.

Original concentration

N/80..........'.... ..............................................................

N/40 ............................................................................

N/20 .............................................................................

N/10 ............................................................................

N/5... .................................................................:........

Bases dissolved,

equivalent

to grams

KjO.

0. 0891

0. 1241

0. 2061

0.3138

0. 4545

K absorbed,

equivalent

to grams

KiO.

' 0. 1012

0. 1381

0. 1990

0. 3124

0. 4503

The results of experiments by Peters on the absorption of potassium 

chloride from solution by wood charcoal are also of importance. The 

charcoal was washed with alcohol and ether and dilute nitric acid and 

carefully dried. The quantities are stated in grams.

Reaction betiueen wood charcoal and potassium chloride solution.

KCl.

N/20 ................................................

N/10. ................................................

Found in solution.

CaO.

0.0128 

0.0280

KjO.

0. 5410

Cl.

0. 4254

Absorbed.

K2 0.

0.0478 

. 0.0795

Cl.

0.0179 

0.0329

A certain amount of the entire salt has apparently been absorbed. 

The potassium absorbed in excess of that equivalent to the chlorine 

absorbed has been replaced in solution by an equivalent quantity of 

calcium.

Although recognizing that "for the absorption of bases from salts a 

chemical exchange with the constituents of the soil is necessary," 

Peters clings to the idea of physical retention; "this [chemical 

exchange] is made possible by the help of the great ' predisposing' 

affinity exerted by the soil on the bases." "The absorption is conditioned by surface attraction which the molecules of the soil exert."

The generally accepted view thus expressed by Peters was that 

taught by Justus Liebig, the dominant figure in agricultural chemistry
16 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

in the middle of the nineteenth century, and, indeed, the creator of 

that branch of science. Soil was known, even before Way's time, to 

have the power of taking up and holding gaseous ammonia, and this 

was ascribed by Liebig to mechanical attraction exerted by the soil 

particles and manifested on their surface.

Rautenberg a in 1862 carried on a series of careful experiments to 

determine what constituent of the soil was responsible for its absorptive properties, and in the end adopted Way's view that the capacity 

for absorption depended on certain hydrous silicates. Efts work was 

confined to solutions of ammonium compounds. He concludes that 

in general the bases dissolved are equivalent to tne ammonium 

absorbed, but still recognizes mechanical influences in the absorption.

Kiillenberg 6 three years later published an exhaustive comparison 

of the effects of various salt solutions through a range of concentrations on a single soil. It will be worth while to reproduce his results 

here, as they constitute the most systematic investigation of the matter that has been undertaken. An attempt to plot the results as 

curves reveals occasional inaccuracies of considerable magnitude, but 

on the whole the data furnish a probably correct outline of existing 

relationships.

It may be observed again that the base enters into reaction to 

approximately the same extent whether it is combined as sulphate, 

chloride, or nitrate. So far as there is a. difference, more of the base 

is removed from sulphate solution than from the others. Dn comparing chemically equivalent quantities it is seen that ammonium is 

taken from solution in greatest degree, followed in order by potassium, magnesium, sodium, and calcium. As to the bases dissolved 

from the soil, Kullenberg's conclusion is that "for the absorbed base 

nearly equivalent quantities of other bases, already present in the 

soil, have been carried over into the solution."

Eighteen experiments with sulphates showed no absorption of SO*. 

Twenty with chlorides showed no absorption of CL The significance 

of this is of course somewhat lessened by the fact that the soil contains 

both sulphate and chloride.

The composition of the soil is shown on the next page.

<i Jour, fur Landw., vol. 7, 1862, pp. 405-554; also vol. 7, 1862, pp. 49-60.

b Mitteil. cl. landw. Ccntralvcreins fur Schlesien, Heft 15, p. 83; also Jahrb. Fortschr. Agr. Chem., vol. 

8, 1865, p. 15.
EARLIER WORK: CHEMICAL REACTION. 17

Composition of soil used in Kullenbery's experiments.

Constituent.

CaO.................................... ............................

MgO........ .......................................................

Fc,0»...... ........................................................

A1 2 03 . ............................................................

K2O. :..............................................................

SO.i. .............................................. r. ...............

!J20o....... ........-..........:-....-....................--.......

Cl............................................ ......................

SiOt................................................ ................

:H SO, ISO0 ..................................................:.......

MnO...............................................................

Total ....... .'. ........... i ...................................

Soluble in 

2£ parts 

cold water.

0.0110

0.0065

 0. 0022

0.0045

0.0022

0. 0012

0.0027

0.0035

0. 0000

0.0055

0.0122

a 0. 0082

O.OG09

Soluble in 

3 parts 

boiling 

HCI, specific gravity, .1.17.

2. 1380

0. 243G

0. 2846

1.5912

1.8480

0. 19,%

0.0612

0.0413

0.0863

0. 0059

0.0930

87. 9C50

5.2840

0.2412

100.08

Insoluble 

in boiling 

HCI.

0. 3959

0. 2023

0. 4398

5. 3483

2. 1024

0. 9588

78.5175

87.97

<* Insoluble' on evaporating solution and heating residue. Soil contained also 0.0059 per cent NH8, 

0.0105 per cent NsOs, and 0.0073 per cent total nitrogen. No C02 present.

In these experiments 100 grams of soil were taken in 250 cm3 solution, which was filtered after three days. Grams absorbed = loss 

in 250 cm3 plus .quantity dissolved from soil by 250 cm3 water alone.

Absorption shown by Kullenbcnfs experiments. 

CAO.

Salt.

CaSO<. .............................................................

CaSO<. .............................................................

CaSO.i. ............................... ......................;......

Ca(N03)s- .........................................................

Ca(NO3)n. .........................................................

Cft(NOa) ». ...........................................................

Ca(N03)2......... ......... ........................................

Ca(N03) 2 ..........................................................

CaCh. ..............................................................

CaCI 2 .. . ............................................................

CuCla................................. ...... . ...................

CaCls. ................................. ....... ..................

CaCl 2 . ................................ ............................

Equivalents per 

liter in 

original 

solution.

0.01 

0.02 

0.04 

0.01 

0.02 

0.04 

0.1 

0.2 

0.01 

0. 02 

0.04 

0.1 

0.2

Amount of base 

absorbed.

Gram.

0. 0173 

0. 0243 

0. 0312 

0. 0060 

0. 0180 

0. 0224 

0. 0257 

0. 0328 

0.0118 

0. 0208 

0. 0270 

0. 0308 

0. 0374

Per cent of 

original.

20.0 

17.3 

11.1 

0.8(7) 

13.5 

8.4 

3.8 

2.4 

17.7 

35.0 

10.2 

4.6 . 

2.8

MoO.«

MgSO< ....... \: ....................................................

MgSO...... ........................................................

MgSO......... .....................................................

MgSO< .............................................................

MgSO< .............................................................

Mg(N03)2.... ......................................................

Mg(N0^2...... ...................................................

Mg(N03) 2 .................... ......................................

Mg(NOs)s. .........................................................

Mg(NOs)!.... ......................................................

MgCIs ..............................................................

MgClj. .............................................................

MgCI 2 ...... ........................................................

MgClj...... ........................................................

MgClj. .............................................................

0.01

0.02

0.04

0.1

0.2

0.02

0.04

0.1

0.2

0. 01

0.02

0.04

0.1

0.2

0. 0220

0. 0362

0. 0479

0. 0734

0. 1312

0. 0238

0. 0371

0. 0470

0. 0731

0.0815

0.0184

0. 0346

0.0450

0. 0569

0.0985

40.4

38.2

25.2

15.5

13.8

CA O

39 1

15.4

8.0

38.8

36.5

10.2

10.4

' Anion of less influence here than with Ca,

Bull. 312 07 2
18 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

Absorption shown by Riillenberg's experiments Continued. 

NA ;O.

Salt.

Na2SO<........ ....................................................

NazSO* ............................................................

Na2SO<........ ....................................................

Na2SO< ............................................................

Na2S04 ............................................................

NaNO3 . ............................................................

NaNOs. ............................................................

NaNOs. ............................................................

NaN03 . ............................................................

NaNOs. ............................................................

NaCl ...............................................................

NaCl.................. .............................................

NaCl ...............................................................

NaCl ...............................................................

NaCl...............................................................

NasHPOi ..........................................................

Na2HPO< ..........................................................

Na2HPO< ........................................:.................

Na2HP04 ..........................................................

Na2HP04 ..........................................................

Na2C03 . ...........................................................

Na2C03 . ............................................................

Na2C03 . .........................:....-.--.........................

Equivalents per 

liter in 

original 

solution.

0.01 

0.02 

0.04 

0.1 

0.2 

0.01 

0.02 

0.04 

0.1 

0.2 

0.01 

0.02 

0.04 

0.1 

0.2 

0. 005 

0.01 

0.02 

0.05 

0.1 

0.01 

0.02 

0.04 

0.1 

0.2

Amount of base 

absorbed.

Gram.

0. 0140 

0.0216 

0. 0372 

0. 0849 

0. 1211 

0. 0140 

0. 0228 

.0.0352 

0.0889 

0. 1460 

0.0112 

0.0229 

0.0463 

0. 1020 

0.1638 

0. 0220 

0.0414 

0.0718 

0. 1567 

0. 2819 

0.0172 

0. 0348 

0. 0734 

0. 1610 

0. 2055

Per cent of 

original.

18.9 

14.6 

12.6 

11.5 

8.2(?) 

18.9 

15.4 

11. 9(?) 

.12.6 

9.9 

15.2 

15.4 

15.7 

13.8 

11.1 

29.9 

28.1 

24.3 

21.2 

19.1 

23.3 

23.6 

24.9 

.21.8 

13.9

K2 0.

K^04 . .............................................................

K2S04. .............................................................

K2SO<. .............................................................

K2SO«. ..............................................................

K2SO4. ............................................................

KNOs..... .........................................................

KNOs.. .............................................................

KNOs

KNOs. .............:............................................-..

KNOs. .............................................................

KC1....................................................... .........

KC1 ................................................................

KC1 ................................................................

KC1.... ............................................................

KC1... ...........:..................................... '...-.........

K2HPO< ...........................................................

K2 IIPO< ...........................................................

K2HP04...................... ........................... ..........

K2HPO, ...........................................................

K2HPO<....... ...................................................

KsCOs........................... ..................................

K2C03 . ............................................................

K2COs......... ....................................................

KsCOs...... :.....................................-.........-......

KjCOa......... ....................................................

0.01

0.02

0.04

0.1

0.2

0.01

0.02

0.04

0.1

0.2

0.01

0.02

' 0.04

0.1

0.2

0.005

0.01

0.02

0.05

0.1

' 0.01

0.02

0.04

0.1

0.2

0. 0609

0.0977

0..1496

0. 2300

0. 3503

0. 0566

0. 0840

0.1097

0.1658

0. 3072

0.0630

0. 0970

0. 1084

0. 1652

0. 2833

0. 0713

0. 1271

0.2113

0. 3295

0.5005

0. 0719

0. 1989

0. 2231

0.3094

0. 3747

14 z,

43.8

33. 5

21.1

15.7

50 7

37. 6

24.6

14.9

13.8

56.5

43.4

24.3

14.6

12.8

03.9

56.9

47.4

 29.5

. 22.4

64.5

53.3

50.0

20.6

' 16.8
EARLIER WORK: CHEMICAL REACTION. 19

Absorption shown by Kullenbenf s experiments Continued. 

NHs.

Salt.

(NHV>»SO< .........................................................

(NHOsSO*... ......................................................

(NHOsSO<.. .......................................................

(Nai 2SO< ..........................................................

(NIW 2SQ4..... ....................................................

NHYNOs..... ......................................................

NH<N03 ..... ......................................................

NKtWO*..... ......................................................

NH,N03 ..... ......................................................

N I3YN03 . ..........................................................

NII<C1....... ......................................................

NIliCl....... ......................................................

N H <C1 .............................................................

N HiCl .............................................................

NH£\. ..................................... I...................... Nirj^POi......................................:..................

NKhMjPOi.. . ......................................................

N HYFfjPO* .........................................................

NII < II2 PO< . ........................................................ NI -rawo... . .......................................................

(NH< )4lI2 (CO3) 3 . ...................................................

(N1I<)<HVC03) 3 .. ..................................................

(NH04l-TXC03 ) 3 .... ................................................

(NH<)4H2 (C03 )3... .................................................

(NH<KHXC08 )3..... ...............................................

Equivalents per 

liter in 

original 

solution.

O.Qi 

0.02 

0.04 

0.1 

0.2 

0.01 

0.02 

0.04 

0.1 

0.2 

0.01 

0.02 

0.04 

0.1 

0.2 

0.01. 

0.02 

0.04 

0.1 

0.2 

0.01 

0.02 

0.04 

0. 1 

0.2

Amount of base 

absorbed.

Gram.

0.0290 

0.0409 

0.0688 

0. 1173 

0. 1400 

0.0229 

0. 0371 

0. 0016 

0. 0871 

0. 1280 

0. 0229 

0. 0375 

0. 0612 

0. 0811 

0. 1174 

0.0307 

0. 0535 

0.0919 

0. 2000 

0.3294 

0. 0260 

0.0410 

0. 0744 

0. 1233 

0. 1755

Percent of 

original.

60.3 

48.0 

40. 3 

27. 3 

16.4 

53.4 

43.4 

36.1 

20.4 

15.0 

53.4 

44.1 

35. 9 

19.0 

13.8 

72.0 

62.8 

54.0 

47.0 

38.7 

01.1 

48.1 

43.7 

28.9 

20. C

Warington in 1868 a studied "The part taken by oxides of iron and 

aluminum in the absorptive action of soils." He observed a slight 

decrease oh measuring the concentration of potassium nitrate solution 

before and after contact with ferric hydroxide prepared by.precipitation from ferric chloride solution with ammonia.

According to Van Bemmelen 5 the compounds resulting from such 

precipitation, commonly called hydroxides, are oxides containing 

variable amounts of water dependent on the condition as regards 

moisture of the atmosphere in which they are placed. There is some 

uncertainty as to what amount of the Water of such substances should 

be counted as. hydrate water and not as water diluting the solution. 

(See p. 24.) Warington assumes as combined water that quantity 

which is not given off over concentrated sulphuric acid, amounting to 

15 per cent. His experiments are not described in sufficient detail to 

show to what extent this affects the results. With potassium chloride the case was similar, while potassium sulphate underwent 

greater absorption. As calculated by Warington the ferric oxide 

took up potassium equivalent to 0.2 per cent of its own weight of 

K2 0 from potassium nitrate solution; 0.3 per cent from chloride, and 

1.2 per cent from sulphate.

Ammonium sulphate or chloride solution became distinctly alkaline

, in contact with ferric oxide, a reaction which appears to be analogous

to that between mercuric oxide and potassium chloride, etc., .where,

«Jour. Chem. Soc., London, vol. 21, 1868, p. 1. 

. &Zeitschr. anorg. Chemic, vol. 20,1899, p. 185, and other papers in the same journal.
20 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

owing to the very slight electrolytic dissociation of mercuric chloride, 

that compound forms in . quantity, producing at the same time 

strongly alkaline potassium hydroxide.

Warington found that aluminum oxide was similar in behavior to 

ferric oxide, although its action was less marked. Rautenberg 0 had 

not been able to detect absorption on treating aluminum oxide with 

ammonium chloride solution.

According to Skey 6 quartz powder takes iron from ferric acetate 

solution. This requires verification.

In 1870 Lemberg began the publication of his work on the transformation of silicates by salt solutions. His experiments, whose 

number runs into the hundreds, constitute a mine of important 

observations in the chemistry of minerals and of geologic processes. 

The silicates used were in the main those related to the zeolites, but 

others were included. The solutions were chiefly of salts of the alkalies and alkaline earths, but embraced also such bases as iron, aluminum, silver, and thallium. The outcome of the experiments was 

usually either (1) exchange of bases in equivalent quantity between 

silicate and solution; (2) addition of base to the silicate, especially 

from alkaline solution; (3) addition of entire salt, or (4) addition or 

subtraction of water. Frequently, if not usually, transformation to 

a different mineral species, often crystalline in form, ensued. Most 

of the work was done at temperatures ranging between 100° and 200° 

C., although some of it was performed at ordinary room temperature. 

The first papers c contain studies of the action of magnesium salt 

solutions on such silicates as apophyllite, gehlenite, vesuvianite, 

datolite, and wollastonite; practically equivalent substitution of 

magnesium for calcium and potassium took place. The work with 

wollastonite was conducted at room temperature and also at 100° C.,

with the following results:

Action of magnesium sulphale on wollaslonite.

Wollastonite after contact with MgSO* solution:

CiiO.

44.1

27.4

1.0

MgO.

11.5

32.0

The action is the same in the cold as at 100° an approximately 

equivalent exchange of calcium for magnesium.

Leucite at high temperatures was converted by sodium chloride 

solution into analcite,d while potassium chloride effected the reverse

a Jour, fiir Landvv., vol. 7, 1862, p. 422.

&Trans. New Zealand Inst., vol. 2. 1869, p. 151.

cZeitschr. deutsch. geol. Gesell., vol. 22,1870, pp. 335 and 803; vol. 24,1872, p. 187.

1 Ibid., vol. 28,1876, p. 537.
EAELIEE WORK: CHEMICAL REACTION. 21

transformation. At low temperatures the reaction was likewise an 

equivalent exchange of bases. The reaction in the cold, although 

taking place to a less extent, is identical with that which results at 

higher temperature.

Leucite contains little water, while analcite has 8 or 9 per cent, and 

all the experiments, hot and cold, show an increase in water content 

as sodium takes the place of potassium.. There seems to be no doubt 

that the one mineral was changed more or less completely into the 

other at 200° C., and the experimental results presented by Lemberg 

are evidence that the same transformation took place, less rapidly, 

at 100°, at 40°, and at room temperature. To bring out this point, 

'and also to illustrate the nature of Lemberg's work, the results of his 

analyses in these experiments will be given in full.

The leucite and analcite were treated with concentrated solutions

of the salts designated, and the portions which had undergone transformation were separated by levigation from the .unchanged mineral, 

air-dried, and analyzed. The leucite was from Vesuvius, the analcite 

from the valley of Fassa.

Action of salt solutions on leucite.

.

Temperature (dog. C.) .........

HaO............................

SiO»............................ 

AlsOa.... .......................

CaO............................

K?0.. ..........................

Na8O.................. .........

.Leucite.

0.32

56. 04 

23. 38

0.20

18. 90

1.41

- 100. 25

NaCl.

180-195. 

(")

7. 80

55. 30 

22.91

0.29

0.08

12.90

100.00

NaCl.

100. 

4.

7.84

54. G2 

23. 40

0.20

0.66

13.22

100. 00

NaCl.

100. 

U8.04

55.38 

22.71

0.25

0.89

12.73

100.00

Na2CO3 .

100. 

. 4.

7.54

54. 72 

23. 01

0.20

1.40

12.54

100.01

NaCl.

40. 

11.

3.40

55. &J 

. 23. 50

0.10

11.61

5. 56

100.00

NaCl.

Room. 

11.

1.79

55. 68 

23. 48

0. If)

15. 88

3.02

100.00

a 18 hours. 

Action of salt solutions on analcite.

HjO ......................................

Si 0».. ....................................

AlaOs.....................................

CaO......................................

K2 O ......................................

Na2 0 .....................................

Analcite.

8.80

50 32

22.00

0.51

13. 10

100. 82

K2CO:t .

100.

7.

0.98

56. 03

22.20

0.60

19.00

0.57

' 99.98

K2C03 .

100.

4*.

0.89

55. 87

22.29

0.00

20.31

99.96

KC1.

100.

3.

0.98

.56. 38

22.39

0.45

19.80

100.00

KsCOa.

40.

7.

1.23

56. 59

21.97

0.52

20.' 23

100.54

KsCO3 .

11-t

1.69

50. 43

22.62

0.40

17. 82

1.04

100.00

Clarke and Steiger," by heating together dry salts and silicates, 

obtained, in crystalline form, substitution compounds of ammonium 

and other bases similar in composition to those here under discussion.

o Am. Jour. Sci., 4th ser., vol. 8, 1899, p. 245; vol. 9, 1900, p. 117.
22 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.,

To throw light on the question of so-called soil absorption, Lemberg subjected an artificial potassium alumino-silicate to digestion 

with various salts and salt mixtures in solution and analyzed the 

resulting solid after thorough washing. Sodium replaced potassium 

in increasing quantity as the concentration of the sodium chloride 

solution in contact with the solid was increased. The presence of 

potassium chloride in the solution at the outset lessened the extent 

to which substitution of sodium for potassium in the solid took 

place. Treated with ammonium chloride solution at room temperature, the artificial silicate gave up its potassium almost completely in exchange for ammonium, as did analcite its sodium at 

40° and chabasite and desmin their calcium and sodium at 100°. 

Similar results followed experiments with other salts. The conclusion drawn by Lemberg from his own work and that of others is 

that "these are purely chemical processes, in which the mass plays 

a rdle in the sense of Berthollet's theory, hence the incomplete 

exhaustion of the solution and hence the mutual replacement of the 

bases/'

Lemberg's work brings out over and over again the fact that 

sodium silicates and alumino-silicates are less stable in contact with 

water solutions than are the corresponding potassium compounds. 

Evidence of this is found not only in the laboratory, but also under 

natural conditions. The replacement of sodium in silicates by the 

potassium of a dissolved salt takes place far more readily than the 

reverse reaction. A similar relation, although perhaps not quite so 

marked, exists between magnesium and calcium silicates. The transformation of a magnesium silicate by calcium chloride into a calcium 

silicate is more difficult than the reverse changed Wollastonite, 

apophyllite, gehlenite, okenite, and a number of artificial magnesium silicates were used to illustrate this experimentally. These 

phenomena are probably closely related to the relative solubility of 

the various minerals in water.

Lemberg,6 following Bischof,c suggests the possibility that the 

need of plant life for potassium rather than sodium may be due to 

the fact that the potassium of silicates is held more tenaciously than 

the sodium, and accordingly the plant finds more of the potassium 

at its disposal in the soil; the environment has then developed the 

habit.

In this same connection we have a suggestion of one reason why 

the ocean is a solution of sodium rather than potassium chloride. 

Other metals and other bases have been eliminated owing to their 

greater capacity than the alkalies for forming compounds insoluble

a Zeitschr. deutsch. geol. Gesell., vol. 20, 1877, p. 483. 

oIbid., vol. 28, 1870, p. 599. 

cChein. Ge'ol., 1st ed., vol. 1, p. 860.
EARLIER WORK: CHEMICAL REACTION. 23

in water, or, as in the case of nitrates, to the fact that they are 

readily decomposed in contact with other substances. The final 

persistence of s the sodium salt rather than that of potassium may 

be due in large measure to this selective action of silicates in rocks, 

sediments such as mud, etc.

Lemberg was unable to detect transformation of the feldspars 

experimentally. "In addition to these (the zeolites) I have experimented with the various feldspars, hornblende, cordierite) serpentine, and scapolite, but up to the present only in the case of hornblende could an exchange of substance be proved with certainty/ ' a

Work along the same line as that of Lemberg was continued by 

Thugutt.&

J. M. Van Bemmelen/of Leiden, in 1877 made an important contribution c to our subject, the first of an extended series by the same 

author. After a very comprehensive review of the work accomplished up to that date, he describes his own experiments.

One hundred grams of soil were brought into contact with 200 

cm'3 portions of solution containing respectively 8 and 40 milligram-equivalents of potassium chloride. After filtration the solutions were carefully analyzed, with the following results, expressed 

in milligram-equivalents. The author estimates the experimental 

error of a determination as at most ±0.2:

Results of Van Bemmelen's experiments with potassium chloride.

Found in solution: 

Na... ..............................................................

Ca................... ..............................................

Mg.... .............................................................

Discrepancy (excess dissolved over absorbed) .........................

Sing, equivalents 

in 200 cm 3.

Experiment I.

0.07 

r,.58

1.10 

1.21

7.89 

i z,(\

0.39

0.32

Experiment 11.

5.90

5.50 

1.05 

1.32

7.87 

1.50

0.37

0.41

40 ing. 

equivalents in 

200 cm3.

Experiment HI.

15.50

7.34 

3.70 

0.48

.17.52 

1.50

10.02

0.52

An exchange of potassium for sodium, calcium, and. magnesium 

had taken place. The chlorine also was determined in the first 

experiment; it had not changed (8.19 equivalents found, instead of 

8.0). The author remarks that the result does not show absorption 

of the salt as a whole; "it can be but very slight, if it takes place at 

all."

a Zeitschr. dent sen. geol. Oesell., vol. 28, 1870, p. 591.

6 Dissertation, Dorpat, 1891, and Zeitschr fiir anorg. Chemie, vol. 2,1892, pp. 64-150.

c Landwirtschaftliche Vers. Stat., vol. 21, 1877, pp. 135-191.
24 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

Van Bemmelen later" investigated the behavior of hydrous silica 

toward various solutions. The silica used, although containing water 

in an amount represented by the formula Si02 ,4H2 0, of which 3.8 

H2 0 was given off on drying at 100° C. or over concentrated sulphuric acid, was a dusty powder. The result of putting this substance into salt solutions was practically the same as if the loosely 

bound water of the silica had been added as liquid. The solute 

distributed itself almost uniformly between the water of the solution 

and the water of the colloid.

The quantities taken for experiment were 100 cm3 of solution and 

10 grams of silica. The 3.8 molecules of water loosely held by the 

silica amount to 5.18 cm3 in 10 grams of the powder, and in case this 

acts as solvent water the concentration would be that corresponding 

to dilution to 105.18 cm3 . The solutions, analyzed after contact 

with the solid, were actually of concentrations corresponding to dilution to the following volumes:

'Results of Van .Bemmelen's experiments with hydrous silica, shniving volumes corresponding to observed concentration.

Solution used: 

KsSO,.. ...............................................................

KN03 . ...............................................................

KC1..................................................................

H2SO4. ...............................................................

HN03 . . ..............................................................

HC1................................................... ...............

1.

20

C?/?,3 .

104.7

10,5.8

104,4

2.

r>0

Cm3 .

104.4

104.5

104.5

101.7

3.

100

Cm3 . 

104.8

104.2

a As used by Van Bemmelen, equivalent, atom, and molecule signify the respective weights taken in 

milligrams.

How much of the water of the solid is to be counted as taking up 

the solute and how much of it is in a condition in which it will not 

act as solution water can not, according to Van Bemmelen,6 be 

determined; the assumption that 3.8 molecules perform that function 

may therefore be subject to modification. In the experiments just 

cited somewhat less salt was, as a rule, absorbed by the silica than 

this assumption would require. Van Bemmelen is inclined to regard 

the action as an exchange between colloid and solution; the colloid 

taking up salt and giving off an equivalent quantity of water.

In a later paper,0 speaking of absorption by the soil, Van Bemmelen says: "If absorption of the entire salt takes place it is slight, 

and in any case not greater than with silica." A certain soil after 

removal of all matter soluble in hydrochloric acid, and drying at 110°

« Jour, ftir prakt. Ohemie, vol. 23, 1881, p. 327; also Land. Vers. Stat., vol. 23, 1870, p. 264. 

b Zeitschr. fur .anorg. Chemic, vol. 23, 1900, p. 330, and other volumes of the same journal, 

c Landw. Vers. Stat., vol. 35, 1888, p. 121, 
WOKK: CHEMICAL REACTION. 25

took up 12.8 per cent moisture from moist air. "The water thus 

absorbed plays the same part, so far as the salt is concerned, as the 

water of the solution." Contact with this soil dried at 110° did not 

alter the concentration of chlorine in a potassium chloride solution; 

the concentration before contact was 20.13 milligram-equivalents in 

100 cm3 ; after contact it was 20.18. Therefore the dried powdered, 

material did not.extract water as such from the solution; had it done 

so the concentration of the solution would have increased about 5 

per cent. The salt is, as in the case of the silica, uniformly distributed 

between the water of the solution and any water taken, up by the 

solid. There is no absorption of the salt alone, although there may 

be absorption of the unchanged solution. The same soil, containing 

12.8 per cent moisture, decreased the chlorine concentration i.o the 

same extent as would the water it contained if added as liquid to 

the solution. In his summing up at the conclusion of this paper Van 

Bemmelen says: "The absorption phenomena of the soil are to be 

ascribed chiefly to colloid silicates, whose power of absorption, for 

entire salts is slight (ein geringes)."

As late as 1900 Van Bemmelen writes: a "As to a specific absorption, 

these complexes (colloid silicates) exert none or almost none; if salts 

are absorbed, the absorbed water is the chief cause therefor."

The important practical fact here is that colloid silica and colloid, 

silicates as they occur in nature do not possess in any large measure 

the power of abstracting from solution and concentrating neutral 

salts. Water percolating through such material will share its dissolved, salts with the water of the colloid; but there can be no notable 

accumulation of salt except as it is present in corresponding quantity 

in the solution both before and after contact with the siliceous matter.

A paper published by Lagergren in 1S99 6 on the "Theory of the 

so-called adsorption of dissolved substances," describes experiments 

on the action of animal charcoal, kaolin, and powdered, glass on the 

dissolved salts of the alkalies, barium, and magnesium. The author 

found that charcoal and kaolin dried at 160° C. increased the concentration of chlorides and bromides, in some cases as much as 1 per 

cent; the concentration was determined by specific gravity and by 

titration with silver nitrate. The data given do hot show how well 

these methods agreed. The charcoal and kaolin had. been boiled-with 

hydrochloric acid in order to purify them. In the case of the sulphates specific gravity alone was relied upon for the determination of 

concentration. The charcoal contained considerable mineral matter. 

In view of the importance of the matter, confirmation of Lagergren's 

results seems desirable.

"-7. oilschr. anorg. Cheniiu, vol. 2:i, p. 321.

b Bihang till k. Svenska Vet.-Akad. Handlingar, Bel. 24, Afd. IT, No. 4, 1809.
.26 INTERACTION BETWEEN MINEEALS AND WATEE SOLUTIONS.

Joly" showed that sea water attacks basalt, orthoclase, obsidian, 

and hornblende to a much greater extent than does fresh water.

Dittrich 6 found that the action of salt solutions on a decomposed 

hornblende granite consisted hi an exchange of bases. Neutral 

potassium chloride solution dissolved from the rock almost twice as 

much calcium as dilute acetic acid, and about one-fourth as much 

as warm 10 per cent hydrochloric acid. Neither carbonic nor 

acetic acid dissolved more than a small part of the potassium taken 

from solution by the rock powder. Potassium, ammonium, and 

magnesium chlorides had approximately equal effect on the powdered granite, while the action of sodium chloride was much weaker, 

and calcium chloride scarcely produced any change whatever. The 

action was the same whatever the acid with which the base was combined.

Powdered feldspar or kaolin with potassium chloride solution gave 

but little action. "Beide Versuche hatten also ein negatives Resultat 

gegeben." The experiments did show, however, that simple absorption of the potassium had not taken place.

Laterite and bauxite with potassium chloride solution retained but 

small quantities of potassium, which, in contrast to that taken up 

by silicates, was almost completely redissolved by water. A slight 

exchange also took place between the calcium of the solid and the 

potassium of the salt. In one experiment with laterite 0.0048 gram CaO 

and a trace of magnesium oxide went into solution, while potassium 

equivalent to 0.0298 gram potassium oxide, out of a total of 0.4680 

gram, was taken up by the 25 grams of the solid. "These experiments 

prove most clearly that the phenomena under investigation are not 

 absorption phenomena, but are purely chemical processes." Hydrous 

aluminates of calcium and magnesium the author considers responsible 

for the absorption of potassium in the earth's crust.

As affording definite data regarding the substances dissolved from 

a rock of the character mentioned, a part of Dittrich's results will be 

reproduced in detail. The decomposed rock contained 0.90 per cent 

calcium oxide, 1.50 per cent magnesium oxide, 7.73 per cent potassium 

oxide, 1.72 per cent sodium oxide; 25 grams rock powder were taken 

in each instance with 100 cm3 salt solution.

QiLantilies, in grams, dissolved from rock, by N/lO NaCl (0.5806 gram in 100 cm3 ).

CaO........................................................................ 0.0356

MgO....................................................................... 0. 0050

K20........................................................................ Trace.

About one-eighth of the total sodium was removed from solution 

by the rock. The total bases in the solution are equivalent to 0.5981

"Joly, J., Proc. Roy. Irish Acacl., vol 24, 1902, pp. 21-33. 

6 Mitt, grossh. bad. geol. Landesanstalt, vol. 4, 1903, p. 341.
EARLIER WORK: CHEMICAL REACTION. 27

gram. NaCI, an excess of 0.0175 gram over that originally present. 

This excess is for the most part accounted for by the solubility of the 

rock constituents in water alone. a Chlorine, 0.34.93; originally 0.3518 

gram.

Quantities, in grams, dissolved from rock by N/J.O KCl (0.7404 gram in 100 c??i3 ).

CaO...................................................................... 0.0640

MgO.....................................................:............... 0.0056

Na.20. -.................................................................. 0.01.69

About two-sevenths of the potassium was precipitated. The total 

bases in solution were equivalent to 0.7600 gram KCl, greater by 

0.0196 gram than the original amount. Chlorine 0.3468; originally 

 0.3518.

N/10 MgCl2 (0.4750 gram in 100 cm3 ) gave 0.0630 CaO-and small 

quantities of K2 0 and Na2 0. About one-fifth of the magnesium was 

precipitated. Lime and magnesia in solution were equivalent to 

0.4888 gram magnesium chloride, an excess of 0.0138 gram over .that 

originally present.

Alkali nitrates, sulphates, and carbonates gave similar results. 

Calcium chloride had little effect. Dittrich continued, this work and 

published its results. 6

Briggs6' investigated the action of dilute solutions on powdered 

quartz whose particles were for the most part 0.005 to 0.05 millimeter in diameter, corresponding to a total area of about 1,000 cm2 

per gram.-

No change in the concentration of neutral salts could be detected 

after contact of their solutions with quartz, and the author's conclusion is that "so far as quartz is concerned adsorption is of minorimportance in the retention of soluble substances in the soil/'

Cushman, in the microscopic appearance of the particles and in the 

formation of a considerable quantity of soluble alkali silicate on wet 

grinding, found experimental evidence that water produces a colloidal siliceous film on the surface of powdered orthoclase and other 

silicates/

So far as the evidence goes, then, the action of silicates, clay, and 

other constituents of the earth's crust on solutions of such salts as 

do not dissolve in water with alkaline reaction consists in an equivalent exchange of bases. The salt is uniformly distributed between 

the water of colloid silica and silicates and the water of the solution. 

Any absorption of the salt as a whole by the solids mentioned is so 

slight as to have escaped positive detection. As bearing on the latter 

point it should be said that certain colloid substances,'-analogues to 

which are present in the earth's crust, do take from solution both the

« Lcc. cit., p. 2C6. cJoar! Phys. Chein., vol. 9, 1905, p. 017.

6 Zeits. filr anorg. Chem., vol. 47, 1905, pp. 151-102. d U. S. Dept. Agr., Bureau of Clieiu., Bull. 92, 1905.
. 28 INTERACTION BETWEEN MINEEAL9 AND WATER SOLUTIONS.

acid and the base of the salts mentioned. Ferric and aluminum 

oxides and metastannic and stannic acids, for instance, take potassium sulphate from solution, while hydrated manganese dioxide takes 

up sulphate, chloride, or nitrate of potassium. a This of course does 

not necessarily imply adsorption. It is not at all impossible, as Van 

Bemmelen suggests, that chemical reaction takes place. Manganese 

dioxide takes up more base than acid from a neutral salt solution, and 

thus imparts to the solution acid reaction. Cupric oxide takes more 

of the acid and alkalinity of solution results.6 These and other 

similar reactions suggest the reaction between mercuric oxide and 

potassium chloride, where potassium hydroxide forms owing to the 

slight electrolytic dissociation of mercuric chloride, and they may be 

due to similar causes. The solids capable of absorbing both acid and 

base from a neutral salt solution are in the main those which themselves exercise both basic and acidic functions.

It is interesting that Van Bemmelen, about six years before the 

propounding of Arrhenius's theory, uses the old electrolytic dissociation theory of Clausius to interpret these reactions: "If we assume 

with the physicists (as in the explanation of electrolysis) that hi a 

dilute acid or salt solution a few individual molecules are in a state 

of dissociation, it is conceivable that the potash of these molecules is 

bound by the manganese dioxide, whereupon fresh dissociation and 

binding of potash can take place until equilibrium sets in." c

ALKALINE SOLUTION.

Where the solution is alkaline in reaction, containing a soluble 

hydroxide dissolved as such or a salt made up of a strong base and a 

weak acid (as the carbonates, silicates, and phosphates of sodium and 

potassium) which is hydrolyzed by water with resulting formation of 

free alkali, its behavior with clay, soils, etc., is due largely to the 

presence of colloid silica or aluminum silicate, and consists primarily 

in the direct addition of alkali to these solids, without substitution, 

insoluble silicates or alumino-silicates being formed.

Way d was the first to observe that the absorption of free alkali 

(potassium hydroxide) by clay was greater after the clay had been 

extracted by hot hydrochloric acid. He, however, attached little 

importance to the observation. The same fact was noted by Van 

Bemmelen 6 and attributed to the-union of the alkali with silicic acid 

remaining after decomposition of silicates by the hydrochloric acid! 

That free alkali was taken from solution by soils without substitution 

by other bases was observed by Henneberg and Stohmami/ in the

a Van Bemmelen, Jour, fur prakt. Chemie, vol. Ml, 1881, p. 330.

b Tominasl, Cornptes rendus, vol. 92, p. 453.

cLoc. cit., p. 394.

<Mour. Roy. Agr. Soc., vol. 11, 1850, p. 359.

eLandw. Vers.-Stat., vol. 21, 1877.

/Ann. Cliein., vol. 107, 1S58, p. 152; Jour, fur Landw., vol. 3, 1859, p. 25.
EARLIER WORK: ALKALINE SOLUTION. 29

case of ammonia, and later by others in the case of other bases. 

That the extraction with acid by decomposing soluble silicates or 

coating them with an impervious layer of silicic acid in large measure 

destroys the power of absorption with substitution was shown by 

Peters," Eichhorn,6 and others.

The fact that silicates after extraction with acid are capable of 

taking up free alkali led Heideii c to an astonishing observation. In 

order to remove silica after extraction with acid he digested with 

sodium carbonate solution and was surprised to find that the residue 

took up 3^ times as much potassium from potassium chloride solution 

as before the sodium carbonate treatment. Sodium had been taken 

up by the silica, and this was then in a position to enter into exchange 

with potassium in neutral solution.

The decrease in concentration observed by Briggs d on treating 

potassium, sodium, and ammonium hydroxide solutions with quartz 

(100 grams quartz powder, 150 cm3 solution) in glass flasks was 

approximately the same in the three cases.

Absorption of alkali ly quarlz.

Final concentration. L°Sm'3 150

0.105 mill'miol in ISOcnr1 . 

13 millimols in 150cm3 ...

Millimol. 

0.0-12 

0.8

Carbonates suffered a slighter loss in concentration under similar 

conditions. That this action was due chiefly to the glass of the flask 

rather than to the quartz was shown by the fact that the results with 

potassium hydroxide in a platinum container were only about onesixth those in glass.

The author recognizes that "the carbonate and hydroxide can not 

be considered free from chemical action on the quartz."

Rumpler c discusses these reactions in connection with the fact that 

sugar-makers purify beet juices by filtration through a silicate (an 

artificial cement) which takes out practically all of the potassium and 

about 25 per cent of the nitrogenous bases (betain), thus leaving the 

molasses less viscous and capable of further crystallization. Pie 

points out that when free alkali (potassium hydroxide) acts on a 

silicate the calcium and magnesium^ which are removed are at once 

precipitated as hydroxides and therefore do not tend to put a stop to 

further substitution of potassium by promoting the reverse reaction,' 

as their, soluble salts would do. This is suggested as a reason why 

free alkali has greater, action on silicates than a neutral salt has.

« Landw. Vers.-Stat., vol. 2, I860, p. 146. 

6 Jahrb. Fortschr. Agr. Chem., vol. 2, 1859, p. JO. 

c Diingerlehre, vol. 1, p. 257; cited by Lemberg. 

dJour. Phys. Chcm., vol. 9, 1905, p. 617.

« Bcr. int. Cong. angcw. Cherhie, 1903, vol. 3, p. 59; also Die dcutsche. Zuckcr-Industrie, vol. 20, 

1901, pp. 585 and 625.
.30 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS. 

PRECIPITATION OF ACID ION.

The loss of the acid radical of a dissolved salt to clay,.soil, etc., 

appears, like the loss of the base, to be due usually to the formation of 

an ordinary insoluble salt, such as the phosphate, carbonate, or silicate 

of calcium, iron, etc. Such.precipitation takes place primarily from 

alkaline solution because the acids that have the greatest tendency to 

form insoluble compounds are weak acids, whose salts are hydrolyzed 

by water. It is observed also in such solutions as those obtained by 

dissolving calcium carbonate or calcium phosphate in carbonic acid 

solution.

Way 0 notes the fact that the acids of ammonium carbonate, potassium carbonate, calcium bicarbonate, sodium phosphate, calcium acid 

phosphate, etc., are removed from solution by soils, together with the 

bases. 1 Now the. base of the dissolved salt in contact with these soils 

is substituted chiefly by calcium. When the calcium salt is soluble, 

therefore, as in the case of the chloride, nitrate, and sulphate, the 

acid radical remains in the solution; when the calcium salt is insoluble, as in the. case of the carbonate or phosphate, the acid radical is 

precipitated.

Liebig b showed that the acid radical of sodium and potassium silicates was removed in part by soils. According to Kiillenberg c the 

phosphate radical is taken up by soil from solution in greater quantity 

the higher the atomic weight of the metal with which it is combined 

(potassium, sodium, ammonium). The difference is probably due to 

the varying readiness with which the salts of the different metals 

decompose the silicates of the soil.

Warington d attributes the removal of the phosphate radical from 

solution by soils chiefly to interaction, with ferric and aluminum 

oxides with formation of insoluble phosphates. He shows that the 

oxides mentioned when artificially prepared are changed to phosphates 

by a solution of calcium phosphate in water containing carbonic acid. 

Ferric oxide (moist, prepared by precipitation from ferric chloride 

solution with ammonia) takes up about 6 per cent of its weight of potash (K20) from a 1 per cent solution of potassium carbonate. From 

0.4 to 0.8 equivalent of the carbonate radical is absorbed for one of 

potassium. By the same oxide 2.3 per cent of potassium sulphate is 

taken up, 6 per cent of ammonium carbonate (equivalent quantities 

of base and acid), 2.5 per cent of ammonium sulphate, and 0.24 per 

cent of ammonium chloride, a 1 per cent solution of the salt being used 

in each case. The ammonium salt solutions are distinctly alkaline 

after contact with ferric oxide. Aluminum oxide gives results similar 

to those with ferric oxide, but less strongly marked.

aJour. Roy. Agr. Soc. vol. 11, 1850, loc. cit. c Jahrb. Fortschr. Agr. Chem., vol. 8, 1865, p. 15. 

i> Ann. Chemie, vol. 105, 1858, p. 109. djour. Chem. Soc. London, vol. 21,1868, p. 1.
EARLIER WORK: INFLUENCE OF CALCIUM CARBONATE. 31

Van Bemmelen" showed that extraction with hydrochloric acid, 

which dissolved oxides of iron and aluminum and decomposed sili- 

'cates to such an "extent that absorption with substitution would not 

take place, also did away with precipitation of the carbonate, phosphate, and borate radicals by the soil. A soil thus extracted took up 

half the alkali from sodium carbonate solution, leaving the acid radical 

in its entirety as bicarbonate. From a solution of sodium phosphate 

(Na2HP04 ) such a soil took up 7.6 equivalents sodium out of a total of 

38.8 present, leaving the acid radical practically unchanged. From a 

borax solution it took 5 equivalents sodium out of a total of 9, and no 

boron. The same soil before extraction with hydrochloric acid took 

12 equivalents of sodium and 4.6 milligram-atoms of phosphorus from 

a sodium-phosphate solution containing 38.8 equivalents of sodium 

and 10.4 mill.gram-atoms of phosphorus.

These facts are in harmony with the conclusion above stated that 

the abstraction of acid radical from solution by silicates is due to the 

formation of insoluble salts, the basic constituents capable of forming 

these insoluble salts being removed or rendered inaccessible to the 

solution by the action of hydrochloric acid.

INFLUENCE OF CALCIUM CAKBONATE.

The action of such silicic acids as result from extraction of "a silicate 

or a soil with acid, as in the experiments of Van Bemmeleii just cited, 

is of some practical importance where calcium carbonate is present, 

giving to the mixture an alkaline reaction. In such a case, as haabeen 

shown, the free alkali unites with the silicic acid and is thus precipitated. The consequence of this is that more calcium carbonate dissolves to replace the calcium hydroxide removed, and these processes 

repeat themselves until equilibrium is reached. The extent to which 

the solubility of'calcium carbonate is increased by the presence of a 

soil which has been extracted with hydrochloric acid is shown by the 

.following data from Van Bemmelen. 6 "Soil B" designates the soil 

extracted with hydrochloric acid.

250 cm3 water dissolve 0.30 milligram-equivalent calcium carbonate.

250 cm3 water in the presence of 100 grams soil B dissolved'2.4 

milligram-equivalents.

"Soil B" in contact with calcium carbonate not only thus increases 

the amount of the latter which may be held in solution by a water, 

but it becomes itself capable, through the medium of the calcium carbonate, of reaction with neutral salts. Again citing Van Bemmelen, 0 

250 cm3 potassium chloride solution (50 equivalents) dissolve 0.73 

equivalent calcium carbonate. But in the presence of 100 grams of 

soil B, 250 cm" of the same solution dissolve from calcium carbonate

«Landw. Vcrs.-Stat., vol. 23, 1879, p. 267. b Landw. Vcrs.-Stat., vol. 23, 1879, p. 273. cLoc. cit.
32 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

6.2 equivalents of calcium and 4.2 of the carbonate radical, while 4 

equivalents of potassium are taken up by the soil owing to partial 

double decomposition between calcium hydroxicle and potassium 

chloride with resultant formation of potassium, hydroxide, which combines with the silicic acid.

In similar experiments with amorphous silica containing water corresponding approximately to the formula SiO2 ,4H2O, calcium carbonate alone was but little affected by the silica, and potassiun 

chloride solution not at all, but when 20 grams silica, 2 grams calcium 

carbonate, and 200 cm3 (40 equivalents) potassium chloride solution 

were mixed it was found that 3.8 milli-equivalents of calcium and 2.7 

of the carbonate radical were dissolved and 2 of potassium were 

 taken up by the silica.

Lemberg had somewhat earlier a brought out experimentally the 

same point with regard to the influence of calcium carbonate. He 

used carbonic acid solution, for extracting the alkali from an artificial 

zeolite-like potassium alumino-silicate, 6 and the behavior of the resultant silicic acids toward calcium carbonate and neutral salt solutions 

was similar to that of Van Bemmelen's soil B, which had been extracted 

with hydrochloric acid. Lemberg's discussion of this reaction is well 

worth reproducing: c

These experiments show what essentially different courses chemical-geological transformations may-take, according to the electro-negative constituent of the salt solution 

which causes the metamorphism. Consider a carnallite bed underlain by layers of 

clay, and suppose the clay to be transformed in places into some product rich in potash, 

such as a mica. It is natural to attribute the potash content of the metamorphic product to the overlying carnallite; the fact remains unaccounted for, however, that the 

entire body of clay has not undergone the same change. The matter is thrown into a 

very different light when it is found that the altered portions of the clay carry calcium 

carbonate, while the surrounding portions are free from it. If the clay possesses a composition similar to that of the silicate extracted with carbonic acid in the experiments 

described, the percolating potassium chloride solution will be without action on it; 

contact of the solution with calcium carbonate, however, will cause partial change into 

calcium chloride and potassium carbonate, and the latter salt, being alkaline, is capable 

of changing the clay into a potash silicate. As the altered clay has taken up no calcium 

one would scarcely be likely to connect the mechanically admixed calcium carbonate 

with the metamorphism, and yet it has been the conditio sine qua non; still more difficult to clear up would the process be if the calcium carbonate had been completely dissolved out and the last clue thus destroyed.

As the transformation of this clay is conditioned by the calcium carbonate, so, on 

the other hand, the solubility or alterability of the calcium carbonate is affected by the 

presence of the clay. Of two marls, one a clay capable of taking up alkali and the other 

a chloritic clay, the former, other things being equal, will in a fixed time give up more 

lime in the form of calcium chloride to waters containing sodium and potassium 

chlorides than the latter.

oZeitschr. deutsch. geol. Gesell., vol. 28, 1876, p. 593.

b Original KjO content, 22.8 per cent; after extraction with CO2, 5.3 per cent.

c Loc. cit., p. 594.
EARLIER WORK: APPLICATION OF MASS LAW. 38

Such modifications of one chemical process by another may be of frequent occurrence, and the striking fact that rock masses apparently perfectly homogeneous suffer 

at points but little apart very different transformations, loses in a measure its puzzling 

character in view of the above considerations.

APPLICATION OF MASS LAW.

A paper by H. P. Armsby, written in 1877,° contributed toward a 

clear understanding of the nature of the absorption of bases by silicates. Way and other workers on the subject had been embarrassed 

in attempting to classify the observed phenomena as chemical reactions by the fact that no relation of chemical equivalence existed 

between the quantity of base taken up and the quantity of any single 

constituent or of any group of constituents of a soil present under the 

conditions of the experiment. N6r could such a relation be found 

among the quantities of different bases taken up by a fixed amount of 

one soil.. Even among, compounds of the same base the absorption

from a solution of the hydroxide or salt alkaline in reaction was not 

as a rule the same as from solutions of the neutral salts. Further, the 

absorption, of base by a given soil from the same salt was by no means 

invariably the same, but fluctuated "with temperature, concentration 

of the solution, and relative quantities of soil and solution. These 

facts were used as arguments in favor of the theory that absorption 

was a physical surface phenomenon.

All these things, Armsby points out, are in accordance. with the 

law of mass action. The absorption had been shown to be an 

exchange of bases between the silicates of the soil and the dissolved 

salts. In the specific case which he takes up experimentally the 

reaction between calcium chloride and an artificial sodium alurninosilicate there is opportunity for the formation of two slightly soluble 

substances, one the sodium alumino-silicate, the other the corresponding calcium compound. In such a case reaction in general does 

not proceed to the formation of one of the two substances exclusively 

to the absolute wiping out of the other, but an equilibrium condition 

is reached in which both slightly soluble compounds are present. 

When such equilibrium sets in a definite relation prevails among the 

concentrations of the reacting substances in the solution. When 

calcium chloride solution, for example, is brought into contact with 

solid sodium alumino-silicate equilibrium may require sodium in 

solution in excess of calcium. In such case solid calcium aluminosilicate will form, withdrawing calcium from and supplying sodium to 

the solution until the necessary ratio is reached. The amount of 

solid transformed will therefore vary with the amount and concentration of the solution used as Avell as with the nature of the solute. 

Sodium chloride in this case accumulates in the solution until its

oLandw. Vers.-Stat. 2J, 397. 

Bull. 312 07 3
34 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

tendency to react with the newly formed calcium alumino-silicate, 

producing again the original substances, holds in check the tendency 

of the first reaction to take place.

In illustration of this Armsby shows that the absorption of calcium 

falls off when sodium chloride is present in the solution from the 

beginning with calcium chloride:

Absorption of calcium by silicate, in grams.

Amount of 

silicate 

taken.

2.5 

1.25 ' 

0.625 

0. 3125

Absorption, NaCl 

present.

0. 1151 

0. 0663 

0. 0359 

0. 0187

Absorption, NaCl 

absent.

0.1039 

0. 0585 

0. 0303 

0. 0143

The sodium chloride was added in quantity about equivalent to the 

calcium chloride. I

The amounts of different bases absorbed will vary with the solubility of their respective alumino-silicates and change in temperature, by shifting the relative solubility, may lead to readjustments in 

the equilibrium.

In the transformation of analcite into leucite by potassium chloride a 

change of one solid into the other may be expected to take place 

until the composition of the solution is such that it acts upon neither 

analcite nor leucite. The simplest case of such a solution is that which 

results when a mixture of analcite and leucite is treated with water, 

forming a solution saturated with respect to both solids. The ratio 

of potassium to sodium in this solution gives at least a qualitative 

indication of what may be expected for the equilibrium ratio where 

potassium and sodium salts are in contact with the two minerals.

Leucite, the potassium compound, appears to be less soluble than

analcite. It may then be expected that any solution in equilibrium 

with the two will contain less potassium than sodium and that in 

solutions not fulfilling this condition transformation of the one 

solid into the other will take place until this equilibrium condition is 

satisfied. A potassium salt will therefore transform more of analcite 

than a sodium salt will of leucite under similar conditions.

INFLUENCE OF CONCENTRATION.

Bodeker in 1859 b sought a numerical expression for the relation 

between concentration of solution and amount of absorption.. It 

was known that increased reaction followed rise in concentration, 

although not in the same proportion. Bodeker concluded that the 

absorption was proportional to the square root of the concentration,

? See p. 20. b Jour, fur Laiidwirtschaft, vol. 3, 1859, p. 48.
EAELIEE WOEK: INFLUENCE OF CONCENTBATION. 35

a statement which expresses the facts approximately in some cases, 

but which has been found not to hold in general. Within certain 

limits of concentration 50 to 500 mini-equivalents salt per liter it 

is true that to double the amount of absorption the concentration 

must be approximately quadrupled, but in weaker solutions absorption is more nearly directly proportional to concentration, while in 

more concentrated solution the quantity of any 'given base taken up 

.by a fixed amount of soil is but little affected by varying the concentration of the solution.

Wolff a in the same year called attention to the fact that the final, 

not the initial, concentration of the solute is to be considered in discussing, the relation between strength of solution and amount of 

absorption. According to him, two equal quantities of soil treated 

with different solutions of a salt will have absorbed identical quantities of base, if after absorption the percentage compositions of the

solutions are alike.

This phase of the subject, was worked out experimentally for colloids by Van Bemmelen, who showed that the quantity of solute 

taken up by a given quantity of a colloid was the same, no matter 

what the original conditions, if only the final concentration of the 

solution was the same. Among the data illustrating this are the 

following, 100 millimols inetastannic acid (Sn02 with about 2H20) 

being used in each case: 6

Experiments .with sulphuric acid and colloid metastannic acid.

Initial state.

Mols a 

H2SO.,.

20

. 50

10

20

10

50

10

20

Cm3 

H2 0.

10

50

10

80

20

400

40

200

1 moJ 

H2S04 in 

cm3 .

J

1

1

4

2

8

4

10

Final state .

Mols H2SO4 

taken up 

by solid.

11.45

11.2

8. 55

8.52

8.07

8.21

7.4

7/5

Mols HjSO* 

in solution.

8. 55

38.8

1.45

11.48

1.93

41.79

2.C

12.5

1 mol 

H2S04 in 

cm3 .

1.17

1.29

7.0

7.1

10. 4

9.50

15.4

10.0

"As used by Van Bemmelen, the mol is the molecular weight taken in milligrams. .

Therefore the quantity of salt absorbed by the colloid will be 

determined by the final concentration of the solution. Water percolating through colloid material will give up its solute to the colloid until equilibrium is reached. After that it will pass through 

unchanged. A more dilute solution will extract the salt from the 

colloid until an equilibrium which corresponds to the greater dilution is established.

oLandw. Zeitung fur Nord- und Mitteldeutschland, 1859, Nos. 32 and 33. Cited by Peters. 

6 Jour, prakt. Chem., vol. 131, 1881, p. 333.
1 

36 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

The absorption is accordingly, in general, an exponential function 

of the concentration of the solution. This is the form found by 

Ostwald a for the solubility of the alkaline earth sulphates in acids of 

. various concentrations and by Meyerhoffer b for the action of potassium 

carbonate on barium sulphate. This form of the curve is therefore 

not necessarily an indication that we are dealing with solid solution 

or adsorption.0 The chief reaction where silicates and salt solutions 

are concerned appears' from the stoichiometrical relations to be 

undoubtedly double decomposition. Where the reaction consists 

chiefly in the precipitation of metal hydroxide, as with orthoclase or 

kaolin and cupric sulphate, the silicate, owing to the weakness of its 

acid and the consequent tendency of the anion to unite with the 

hydrogen of water to form the nondissociated acid, acts in a sense 

as a generator of hydroxyl ions, and here the exponential form of 

the concentration curve is to be expected. It is to be borne in 

mind that the conditions examined experimentally are not those of 

equilibrium, inasmuch as precipitation may be increased by further 

grinding of the silicate powders. The greater penetrative power of 

the concentrated solutions, due to their higher osmotic pressure, 

will undoubtedly determine in some degree the extent of the reaction 

and therefore the form of the concentration curve.

Van Bemmelen regards the holding of electrolytes by colloids as 

due to loose chemical combination, and designates the resulting 

products as "absorption compounds." In many of the cases examined by him ordinary chemical union undoubtedly is responsible for 

a part, at least, of the phenomena observed, as where stannic oxide 

is treated with acid or alkali. In some other cases there seems reason to classify the facts as distribution of solute between two solvents one water, the other a colloid.

No undoubted case of solid solution is known among amorphous 

substances. d

As to the possibility of adsorption, Freundlich e finds that even by 

charcoal "inorganic salts in water solution are very weakly adsorbed." 

Indubitable evidence that adsorption of inorganic salts by mineral 

matter takes place to a measurable extent seems to be lacking.

a Jour, prakt. Chem., vol. 137,1884, p. 55.

& Zeitschr. phys. Chem., vol: 53,1905, p. 530.

c For a discussion of adsorption, solid solution, and chemical combination see Ostwald, Lehrbuch 

vol. 2, pt. 3, 1906, pp. 252 and ff.

d Ostwald, Lehrbuch, vol. 2, pt. 3, 1906, p. 253.

e Freundlich, Herbert, Adsorption in solutions: Zeitschr. phys. Chem., vol. 57, December, 1906, pp. 

385-470.
INTEKACTION BETWEEN MINEEALS AND WATEE SOLUTIONS. 37

EXPERIMENTAL WORK.

METHOD OF PROCEDURE.

In the work carried out in the Geological Survey laboratory 0 the 

experimental procedure, except where otherwise specified, was as 

follows: The mineral, finely ground in an agate mortar, was left 

several days at room temperature, with occasional shaking, in a wellstoppered flask with twice its weight of the solution. Whether contact was for a few hours or a few months made little difference. 

The liquid was filtered through a double layer of filter paper in a 

Gooch crucible, which, except in the case of pure-water extracts, 

retained the finest powders and gave perfectly clear filtrates. A. 

measured quantity of the filtrate was subjected to analysis. After 

addition of acid, silica was removed by evaporation, iron and aluminum were precipitated with ammonia, and calcium was separated 

with ammonium oxalate. Ammonium salts were then driven off by 

heating, and magnesium was precipitated and washed with barium 

hydroxide solution and weighed as the sulphate. The barium 

hydroxide contained a trace (less than 0.1 per cent) of impurity, 

chiefly potassium and sodium, for which a correction was applied in 

the one or two cases in which it was of significance. In the nitrate 

from magnesium hydroxide barium was precipitated with ammonium carbonate, reprecipitated, and the alkalies in the filtrate were 

weighed as chlorides and separated in the usual way. Repeated 

tests of the alkali chlorides for magnesium gave, as a rule, an 

unweighable trace at most rarely a few tenths of a milligram.

Some idea of the degree of uniformity which can be obtained on 

repeating these experiments as nearly as possible under the same conditions may be had from the duplicate results with copper sulphate 

and kaolin. The errors may, however, in less favorable cases, 

amount to several hundredths of a millimol.

The results are only roughly comparable among different minerals, 

owing to the impossibility of getting the powders of uniform fineness.

The orthoclase was, except where otherwise specified, from a lot 

of very fresh cleavage fragments obtained from Delaware County, 

Pa., through Foote & Co. Orthoclase A and orthoclase B were from 

San Diego County, Cal.

a A preliminary paper giving some of the results of this .work was published in Jour. Am. Chem. 

Soc., vol. 27, 1905, pp 976-979, and in Economic Geology, vol. 1, 1905, pp. 07-73.
38 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

EXPERIMENTAL RESULTS. 

KAOLIN AND CUPRIC SULPHATE.

Kaolin- with twice its weight of cupric sulphate solution. The 

kaolin used was an impalpable powder, most of its particles having 

a diameter of about 0.002 to 0.003 mm. Examination under the 

microscope, kindly made by Mr. Lindgren, showed the presence of 

some undecomposed feldspar. The kaolin was free from carbonate 

and gave no trace of hydrogen sulphide on heating with acid. The 

results are stated both in grams and in milligram molecules.

Experiments, with kaolin and cupric sulphate solutions.

COPPER FOUND IN 50 CUpIC CENTIMETERS.

1

Grams.

0. 0051

0. 0013

0. 0038

Millimols.

O.OS

0.02

0.06

2

Grams.

0. 0254

0. 0143

0.0111

Millimols.

0.40

0.22

0.18

3

Grams.

0. 0259

0. 0156

0. 0103

Millimols.

0.41

0. 25

0.16

4

Grams .

0. 1269

0. 1104

0. 0165

Millimols.

2.00

.1.74

0.26

5

Grams.

0.1268

0. 1099

0. 0169

Millimols.

1.99

1.73

0.26

BASES FOUND IN VARIOUS VOLUMES OF FILTRATES.

Constituent.

Si02 . ....................

Fe2 0g, AlaOs.............

CaO......................

MgO.. ................... K 2 o .................:...

Na2O ....................

Total ................

Total gain in 50 cm3 .

110 cm3 .

Grams.

0. 0026 

0.0008 

0.0042 

0. 0032 

0. 0016 

0. 0020

0. 0144 

0.0065

Millimols.

aQ.Q2 

0.08 

0.08 

0.02 

0.03

0.23 

0.10

50 cm3 .

Grams.

0.0026 

0,0020 

0.0048 

0. 0031 

0. 0010 

0. 0015

0.0150 

0.0150

Millimols.

"6." 6e"

0.09 

0.08 

0.0 1 

0.02

0.26 

0.26

55 cm3.

Grams .

0.0006 

0.0004 

0. 0051 

0. 0037 

0. 0011 

0. 0027

0.0136 

0.0126

Millimols.

"o.'oi"

0.09 

0.09 

0.01 

0.04

0.24 

0. 22

60 cm3 .

Grams.

0.0020 

0.0018 

0. 0066 

0. 0042 

0. 0018 

0. 0016

0.0180 

0. 0150

Millimols.

"6'05" 

0.12 

0.11 

0.02 

0.03

0.33 

0. 28

60 cm 3.

Grams.

0. 0013 

0.0025 

0. 0066 

0. 0040 

0. 0013 

0. 0020

0.0177 

0.0148

Millimols.

""6." 07 

0.12 

0.10 

0.01 

0.03

0.33 

0.28

a In this table and in those following the figures given for millimols ferric and aluminum oxides 

express the, number of divalent millimols to which the quantities of these bases found are equivalent, 

the millimol being the molecular weight taken in milligrams.

Fifty grams washed kaolin taken with 100 cm3 distilled water. 

Solution neutral to litmus. Found in 50 cm3 (as sulphates): a

 Experiment with kaolin and 'water.

SiOj... .........................................................................

CaO .............................................................................

MgO.......................................... ..... .............

KiO... ............................. .... ....

NasO ...........................................................................

Grams.

0. 0006

0. 0010

0.0005

O non9

0. 0003

0. 0026

Millimols.

0.018

0. 013

O AAO

0.006

0.039

» Corrections have been applied to these figures for impurities in the barium hydroxide solution used 

as follows: MgO 0.0001, K20 0.0004, NajO 0.0006 gram.
EXPERIMENTAL RESULTS. 39

Subtracting from the bases dissolved by copper sulphate solution 

that quantity which water alone takes up from the .kaolin, 0.04 millimol, we have the following comparison of the copper precipitated and 

the bases replacing it:

Comparison of copper, precipitated with bases dissolved.

~RfiQpQ HioQnlvoci prn*l*

Millimols in SO cm3.

0.08

0.06 

0.06

0.40

0.18 

0.22

0.41

0.16 

0.18

2.00

0.26 

0.24

1.99

0.26 

0.24

The agreement is sufficient to show that the main reaction which 

takes place is an exchange of bases in equivalent quantities between 

the kaolin and the solution. Any adsorption that occurs is probably 

not over 0.02 millimol or 0.0013 gram copper, which in 25 grams kaolin is one in 20,000. In the case in which the bases are 0.04 millimol 

in excess the solution had unusual opportunity to dissolve material 

from glass, in which it stood for about five months.

Copper sulphate solution containing 2 millimols in 50 cm3 when 

filtered through 25 grams of kaolin in a column 1 cm. in diameter 

came through at first colorless and contained chiefly calcium sulphate.

The investigation of the action of kaolin was suggested by Kohler's 

paper on adsorption, to which reference has already been made." 

The instances cited by Kohler of association of ore with kaolin while 

neighboring sandstone free from kaolin contains no metal seem attributable to chemical precipitation by residual silicate or aluminosilicate in the kaolin rather than to adsorption.

INFLUENCE OF SURFACE.

The surface exposed by a finely powdered mineral to the action of 

the salt solutions is of course very large, and it is only by multiplication of the reaction velocity in some such way that these changes 

become at all accessible to laboratory investigation. It may be 

remarked that fine grinding appears to be a less exceptionable means 

to this end than the use of high temperatures, which may give a very 

different result from that which would be obtained in a longer time at 

lower temperatures. The final equilibrium is riot affected by fineness 

of division of the reacting solid. It is in general affected by a variation in temperature.

The surface actually exposed to a salt solution even in the case of a 

fresh rock in place is perhaps greater than is apparent. The permeability of such rocks was illustrated in the course of work with

aZeitschr. prakt. Geol., vol. 11, 1903, p. 53.
40 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

selected cleavage fragments of very fresh orthoclase, which had lain 

for some months in a copper sulphate solution. . In order to examine 

the surface of the feldspar the solution was poured off and the mineral 

very carefully and thoroughly washed with water and set aside to dry. 

Some days later minute crystals of copper sulphate were found on the 

surface of the mineral at points where no crack was visible to the eye. 

These were dissolved by soaking the fragments in water, and the surface was again thoroughly washed, with the same result at the end of 

a few days. Copper sulphate solution which had penetrated numberless interstices in the apparently unaltered mineral again came to the 

surface and deposited crystals. The washing was repeated many 

times with the same result.

That the extent to which silicate and solution exchange bases is 

dependent upon the surface exposed is evident from the following 

experiments, in which the amount of copper precipitated increases as 

the grinding is carried further.

Washed kaolin with cupric sulphate solution .containing originally 

0.1263 gram copper in 50 cm3 precipitates 0.0165 gram copper. 

Agitating the mixture continuously for about two weeks increases the 

amount of copper precipitated to 0.0183 gram, and kaolin previously 

ground in the agate mortar precipitates under similar conditions as 

much as 0.0584 gram.

Orthoclase from San Diego County, Cal., ground for four hours, 

precipitated 0.0268 gram copper, while another portion of the same 

feldspar ground for about fifteen hours removed 0.0798 gram copper, 

other conditions being the same.

Orthoclase from Delaware County, Pa., precipitated 0.0469 gram 

copper; ground a few hours longer, 0.0656 gram; two portions of 

another sample, still more finely powdered, precipitated respectively 

0.0728 gram after two days' contact and 0.0730 gram after twelve 

days.

ORTHOCLASE AND SALT SOLUTIONS.

The orthoclase used was in two lots of different fineness. Twentyfive grams of one lot precipitated from 50 cm3 1 .per cent cupric 

sulphate solution 0.0730 gram copper; of the other, 0.0469 gram. 

These numbers are in the ratio 1.554 :1. The quantities of the various 

metals precipitated and bases dissolved are assembled in the following table. Twenty-five grams orthoclase and 50 cm3 solution were 

used in each case. The results obtained with the coarser feldspar, 

indicated by *, have been multiplied by 1.554 and are what might be 

expected if feldspar of uniform fineness were used.
EXPERIMENTAL RESULTS. 41

Summary of results with orthoclase and salt solutions.

Solution.

* Magnesium sulphate. . ...............................

* Manganous sulphate. ...............................

* Nickelous sulphate. .................................

Metal precipitated.

Grams. 

0.0099 

0. 0207 

0.0355 

0.0365 

0.0648 

0.0549 

0.0716 

0.0625 

0.0729 

0.0611 

0.0427 

0. 1027 

0.0982 

0.0563 

0. 2970

Milligramatoms. 

0.40 

0.51 

0.62 

0.65 

1.16 

0.93 

1.13 

0.98 1.03' 

0.93 

0.48 

0.94 

0.71 

0.27 

1.43

Original 

content.

Milligramatoms. 

1.98 

2.44 

2.54 

2.10 

1.21 

2.06 

1.98 

1.99 

1.98 

3.05 

2.32 

0.98 

2.04 

1.36 

2.00

Bases 

dissolved.

Millimols. 

0.47 

0.54 

0.53

1.41 

0.92

1.01 

0.85 

0.99 

0.51 

a 1.01 

0.78 

1.21 

1.14

« Milli-equivalents.

Owing to the fact that orthoclase gives up a perceptible quantity of 

alkali to water, the bases dissolved will be a few hundredths of a 

.imllimol in excess of the metal precipitated in those cases in which no 

basic salt is formed. Where the precipitate contains basic salt, the 

bases going into solution throw out more than their equivalent of 

metal. The auric chloride solution has, owing to acidity resulting 

from, hydrolysis, dissolved bases in excess of the metal precipitated.

OETHOCLASE AND CUPRIC SULPHATE.

Experiments. Orthoclase A (from San Diego County, Cal.), containing 11.98 per cent K20, 3.32 per cent Na20; free from carbonates. 

In the first experiment the sample had been ground for four hours, 

in the .second for fifteen hours. Contact was for one hour and overnight, respectively. - '

Experiments with orthoclase and cupric sulphate.

Constituent.

Copper in 50cm3 :

Finally.......;..........,.................................

Content of 39.89 cm3 : 

CaO..... .................................................. Mgo...............................;......................:

KjO..... ..................................................

NaaO

]

Grains.

0. 1262

0.0994

0.0268

.

Millimols.

1.98

1.56

0.42

'

e

Grams.

0. 1266

0.0468

0.0798

0.0015

0.0018

0.0348

0.0212

0.0593

0.0743

>_

Millimols.

1.99

0.74

1.25

0.03

0.05

0.37

0.34

0.79

1.18
42 INTEKACTION BETWEEN MINEBALS AND WATEK SOLUTIONS.

Orthoclase B (San Diego County, Cal.), containing 8.26 per cent 

K2 0, 4.38 per cent Na2 0, 0.03 .per cent C02 ( =0.0075 gram or 0.17 

millimol C02 in 25 grams feldspar). In contact overnight with 

cupric sulphate solution.

Experiment with orthoclase and cupric sulphate.

Constituent.

Copper in 50 cm3 : 

Finally .....................................................................

Content of 53.66 cm3 solution: 

KtO...... ..................................................................

NaaO.... ...................................................................

Total.............................'......'..................................

Grams.

0.1266

0.0685

0.0581

0.0356

 0.0284

0.0630

Millimols.

1.99

1.08

0.91

0.37

0.46

0.83

0.77

Influence of concentration. The influence of concentration of the 

cupric sulphate solution is foreshadowed by earlier work with other 

substances. The more concentrated the solution the greater the 

quantity of copper precipitated under similar conditions. Precipitation is not, however, proportional to concentration, but increases 

more slowly than the latter. In concentrated solutions a change in 

the concentration has comparatively little effect on the amount precipitated. A few determinations of the quantity of sulphate radical 

precipitated with the copper are appended. No definite relation 

appears between the two. In very, dilute solution, where the copper 

is almost completely precipitated, the proportion of acid radical 

carried down decreases.

Experiments with orthoclase and cupric sulphate, showing influence of concentration.

Content in 50 cm3 .

Constituent.

Copper:

Finally............

Sulphate radical:

Grams.

0.0316

0.0316

0.0481

0.0453

0.0028

Millimols.

0.497

0

0.497

0.501

0.472

0 029

Grams.

0.0632

0.0215

0.0417

0.0961

0.0870

0 0091

Millimols.

0.994

0.338

0.656

1.001

0.906

0.095

Grams.

"0.1263

0.0794

0.0469

Millimols.

1.99

1.24

0.75

Grams.

1.487

1.403

& 0.084

Millimols.

-23.39

22.06

cl.33

Grams.

2.978

2.873

d 0. 105

Millimols.

46.82

45.17

«1.65

a A solution of this original concentration treated with the same orthoclase, more finely ground, 

lost 1.03 mols copper and 0.176 mol SO*; and with the orthoclase still more finely pulverized 1.15 mols 

copper and 0.182 mol S0<.

6 ±0.002. c-j-o.02. d± 0.003. <±0.05. . '

Influence of temperature. The change in amount of precipitation 

caused by raising the temperature was found to be slight. Ortho-
EXPERIMENTAL "RESULTS. 43

clase with cupric sulphate heated for a few minutes on the water 

bath precipitated 0.082 gram copper as compared with 0.073 gram 

cold.

ORTHOCLASE WITH CUPRIC SULPHATE AND SULPHURIC ACID.

Twenty-five grams powdered orthoclase with 50 cm3 cupric sulphate 

solution and 0.7 cm3 5.8 normal sulphuric acid (=2.03 millimols). 

Filtered after two days.

Experiment ivith orthoclase and cupric sulphate and sulphuric acid.

Constituent.

Copper in 50.7 cm3 :

Finally.....................................................................

Loss ................................................. ; ....................

Content of 40 cm3 

SiOs. .......................................................................

AlaOs.......................................................................

MgO..................................................... ...................

KS 0..... ...................................................................

Na2O .......................................................................

Total .....................................................................

Grams.

0. 1263

0. 1214

0.0040

0.0122

0.0248

0.0019

0..0635

0.0125

0. 1165

0. 1477

Millimols.

1 99

1.91

' 0. 08

' «0.73

0.03

0.05

0.08

0.20

I 69

2.14

a The alumina found is equivalent to 0.73 divalent inillimol.

The bases dissolved are equivalent to the sulphuric acid present 

plus the copper precipitated. The orthoclase has therefore neutralized the dilute sulphuric acid solution (0.2 gram sulphuric acid in 50 

cm3). The copper precipitated is but a small fraction of that precipitated from unacidified solution.

ORTHOCLASE AND CUPRIC NITRATE.

Filtered after two days.

Experiment with orthoclase and cupric nitrate.

Constituent.

Copper in 50 cm3 :

Finally .....................................................................

Content of 40 cm3 :

MgO........................................................................

~K.tQ...............i........... .............................................

Na2O .......................................................................

Total.....................................................................

Grams.

0. 1267

0.0865

0.0402

0.0027

0.0000

0. 0006

0.0008

0.0323

0 OOSO

0.0450

0.0563

Millimols.

1.99

1.36

0. fi.3

0.02

0.01

0.02

0.34

0.13

O co

0.65
44 INTERACTION BETWEEN MINEEALS AND WATER SOLUTIONS.

ORTHOCLASE AND CUPRIC CHLORIDE.

Filtered after three days.

Experiment with orthoclase and cupric chloride.

Constituent.

Copper in 50cm3 :

Finally .....................................................................

Grams.

0.1258

 0.0542

0.0716

Milltmols.

1.98

0.85

1.13

For comparison of the precipitation from sulphate, chloride, and 

nitrate of copper, see page 41.

ORTHOCLASE AND SILVER SULPHATE.

Twenty-five grams powdered orthoclase in contact for two days 

with 50 cm3 silver sulphate solution: The silver was almost completely precipitated.

Experiment with orthoclase and silver sulphate.

.Constituent.

Silver in 50 cm3 :

Content of 30.27 cm-:

CaO..... ................................. .....I. ....... ....f.. ..............

MgO......................................................... ...............

KaO..... ...................................................................

NasO.... ...................................................................

Total. ....................................................................

Total in 50 cm3 . ................................................................

Grams.

0.1066

0.0039

0.1027

0.0007

0.0001

0.0004

0.0170

0.0073

0.0255

0.0421

Milliequivalents.

0.98

0.04

0.94

0.02

0.36

0.23

0.61

1.01

ORTHOCLASE AND LEAD NITRATE.

Twenty-five'grams powdered orthoclase with 50 cm3 lead nitrate 

solution. Filtered after five days.

Experiment with orthoclase and lead nitrate.

Constituent.

Lead in 50 cm3 :

Finally .....................................................................

Content of 40 cm3 : 

Si02..... ...................................................................

MgO........................................................................

K^O..... ...................................................................

NasO.... ...................................................................

Total .....................................................................

Grams.

0. 4140

0. 1170

0. 2970

0. 0024

0. 0008

0. 0017

0. 0030?

0. 0528

0. 0143

0.0750

0.0938

Millimols.

2.00

0.57

1.43

0.02

0.03

0.07?

0.56

0.23

0.91

1.14
EXPERIMENTAL RESULTS. 45

ORTHOCLASE AND GOLD CHLORIDE.

Twenty-five grams powdered orthoclase with 50 cm3 auric chloride 

solution (AuCl3 ), which contained a slight excess of hydrochloric acid 

(0.03 millimol, determined by precipitation as silver chloride). The 

bases dissolved are in no apparent relation to the gold precipitated, 

being in very decided excess. >

Experiment with orthoclase and gold chloride.

Constituent.

Gold in 50 cm3 :

JjOSS

Content of 40 cm3 : 

on

MgO......................... ................ ................................

KsO..... ...................................................................

Na 2O .......................................................................

Total.......................................................;..-..........

Content of 50 cm3 . ..............................................................

Grams.

0. 2687

0. 2325

0. 0362

Trace.

Trace.

0. 0009

0. 0412

0. 0103

0. 0524

0. 0055

Millimols.

0

1.36

1.18

0.18

0.02

0.43

0.17

0.62

0.78

Gold was not precipitated from hydroaurichloric acid (HAuCl4 ) 

solution by orthoclase.

ORTHOCLASE AND ZINC SULPHATE.

Twenty-five grams powdered orthoclase with 50 cm3 zinc sulphate 

solution. Filtered after two days.

Experiment with orthoclase and zinc sulphate.

Constituent.

Zinc in 50 cm3 :

Finally ......................................... . .........................

Content of 41.1 cm3 : 

SiOa. ........................................................................

FesO3 . ......................................................................

CaO .............................:..........................................

MgO:.......................................................................

K20..... ...................................................................

NajO.... ...................................................................

Total.....................................................................

Grams.

0. 1995

0.1384

0. 0611

0. 0019

0. 0010

0. 0014

0. 0013

0.0363

0. 0127

0. 0546

0. 0665

Millimols.

3.05

2.12

0.03

0.02

0.03

0.03

a 0.32

«0. 41

' aO.81

a 0.00

a The result for K2O is low, that for NajO is high, and the totals are high. 

KAOLIN AND ZINC SULPHATE.

Twenty-five grams kaolin in contact two days with 50 cm3 of the 

same zinc sulphate solution precipitated 0.0169 gram (0.26 millimol) 

zinc.
46 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

ORTHOCLASE AND FERROUS SULPHATE.

Twenty-five grams orthoclase with 50 cm3 ferrous sulphate solution 

in stoppered flask of some 200 cm3 capacity. The air was not removed 

from the flask before stoppering. After two days the orthoclase, 

originally pure white, had taken on a light chocolate color, due to pre-. 

cipitated iron. Fifty cm3 ferrous sulphate solution, similarly inclosed 

in a flask without orthoclase, showed no perceptible precipitate at the 

end of two days. The orthoclase, by rendering the solution alkaline, 

had accelerated oxidation and thus precipitation.

Experiment with orthoclase and ferrous sulphate: Iron in 50 cm3 .

Grains.

0. 1178 

0. 0813

0. 0365

Millimols.

2.10 

1.45

0.65

In a similar experiment in which some pains were taken to exclude 

air only 0.016 gram iron was precipitated.

KAOLIN AND FERROUS SULPHATE.

Twenty-five grams kaolin in presence of air with 50 cm3 ferrous sulphate solution of about the same concentration as in the experiment 

with orthoclase removed approximately 0.015 gram (0.27 millimol) 

iron.

ORTHOCLASE AND FERRIC SULPHATE.

Twenty-five grams powdered orthoclase with 50 cm3 ferric sulphate 

solution. Filtered after three weeks. But a trace of iron remained 

in the filtrate.

Experiment vrith orthoclase and ferric sulphate.

Constituent.

Iron in 50cm3 :

Content of 40cm3 : 

SiOs. .......................................................................

A1S 03 ..... ..................................................................

CaO...... ..................................................................

MgO .......................................................................

KaO...... ..................................................................

NftsO ........................................................................

Total ......................................'...............................

Grams.

0. 0675

0. 0027

0.0648

0. 0067

0. 0114

0. 0023

0. 0012

0. 0519

0. 0103

0.0838

0. 1058

Millimols.

1.21

0.05

a 1.16

0.34

0.04

0.03

0.55

0.17

1.13

61.41

"3.48 milli-equivalents. s'2.82 milli-equivalents.
EXPERIMENTAL RESULTS. 47

Barium sulphate obtained from 50 cm3 ferric sulphate solution after 

contact with orthoclase was 0.3528 gram, or 1.514 millimols; before 

contact (assumed equivalent to iron), 1.810 millimols. The loss of 

sulphate radical, 0.296 millimdl, or 0.592 milli-equivalent, plus the 

gain in bases, 2.82 milli-equivalents, equals 3.412 milli-equivalents, 

practically identical with the loss of iron.

ORTHOCLASE AND MANGANOUS SULPHATE.

Twenty-five grams powdered orthoclase with 50 cm3 manganous 

sulphate solution. Filtered after two weeks.

Experiment with orthoclase and manganous sulphate.

Constituent.

Manganese in 50 cm3 : Originally. .................................................................

Content of 40cm3 : > SiO2 ........................................................................

CaO .........................................................................

MgO................ .........................................................

K2 0...... ..................................................................

NaaO..... ...................................................................

Total .....................................................................

Content of 50 cm3 ..............................................................

Grams.

0. 1307

0. 0222

0. 0020

0. 0004

0. 0012

0. 0013

0.0183

0. 0013

0. 0251

0.0314

Millimols.

2.54

0.40

0.01

0.02

0.03

0.19

0.02

0.27

O.;M

ORTHOCLASE AND NICKEL SULPHATE.

Twenty-five grains powdered orthoclase with 50 cm3 nickel sulphate 

solution. Filtered after two weeks' contact.

Experimeni with orthoclase and niclccl sulphate.

Constituent.

Nickel in 50cm3 :

Content of 38.8 cm3 : 

SiOs...... ..................................................................

MgO ........................................................................

KlO...... ..................................................................

Na2O ........................................................-.............:

Grains.

0. 1209

0. 0850

0.0353

0. 0031

0. 0001

0. 0008

0. 0032

0. 0245

0. 0009

0. 0386

0. 0490

Millimols.

2.00

1. 40

0.00

0.01

0.08

0.20

0.11

0.40

0.5!)

ORTHOCLASE AND MAGNESIUM SULPHATE.

Twenty-five grams powdered orthoclase with 50 cm3 magnesium 

sulphate solution.
48 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

Experiment with orthoclase and magnesium sulphate.

Constituent.

Magnesium in 50 cm3 : Originally. .................................................................

Finally. .....................................................................

Content of 40 cm': 

SiO2 . .......................................................................

CaO......................:.................................................

K2O..... ...................................................................

Total.....................................................................

Grams.

0.0481'

. 0. 0417

0. 0064

0.0012

0. 0006

0. 0016

0.0118

0. 0045

0. 0197

0. 0246

Millimols.

1.98

1.71

^ 0.26

. 0.02

0.03

0.12

0.07

0.24

0.30

ORTHOCLASE AND CALCIUM CHLORIDE.

Twenty-five grams powdered orthoclase with 50 cm3 calcium chloride solution. Filtered after five days.

Experiment with orthbclase and calcium chloride.

Constituent.

Calcium in 50 cm8 :

Finally. ....................................................................

Content of 40 cm8 : 

SiO2 , Ah03, etc .............................................................

MgO.............. ..........................................................

K2 0..... ...................................................................

Na2O ......................:................................................

Total .....................................................................

Grams.

0.0977

0. 0844

0.0133

0. 0012

0. 0004

0. 0179

0. 0048

0. 0243

0. 0304

Millimols.

2.44

2.11

0.33

0.01

0.08

0.28

0.35

ORTHOCLASE AND STRONTIUM CHLORIDE.

Twenty-five grams powdered orthoclase with 50 cm3 strontium 

chloride solution. Filtered after seven days.

Experiment with orthoclase and strontium chloride.

Constituent.

Strontium in 50 cm8 :

Content of 40 cm8 : 

SiO2 ..... ................................. ...................... .............

A12O3, etc. ..................................................................

CaO........................................................................

MgO........................-...:.........................-....-.......-....

K2O..... ...................................................................

Na2 0 .........................;.............................................

Total .....................................................................

Grams.

0. 2032

0. 1757

0. 0275

0. 0007

0. 0004

0.0008

0. 0005

0. 0157

0. 0056

0. 0237

0. 0296

0. 0017

0. 0279

Millimols.

2.32

2.01

0.31

0.01

 0.01

0.01

0.17

0.09

0.29

0. 36

0.03

0.33
EXPEKIMENTAL EESULTS. 49

ORTHOCLASE AND BARIUM CHLORIDE.

Twenty-five grams powdered orthoclase with 50 cm3 barium chloride solution. Filtered after four days.

Experiment with orthoclase and barium chloride.

Constituent.

Barium in 50cm8 :

Content of 40 cm8 : Si02 .......... .........................................................I....

CaO ........................................................................ Mgo.. :.....................................................................

KzO..... ...................................................................

NasO ...........................:.............. n. ...........................

Total.....................................................................

Grams.

0. 2801

0. 2J69

0. OG32

. 0.0005

0. 0003

0.0010

0.0004

0.0258

0. 0054

0. 0334

0.0418

Millimols.

2.04

1.58

0.46

0.01

0.02

0.01

0.27

0.09

0.40

0.50

A. S. Cushman has shown a that barium and aluminum are removed 

to some extent from solutions of their salts by a white china clay.

ORTHOCLASE AND POTASSIUM CHLORIDE.

Twenty-five grams powdered orthoclase with 50 cm3 potassium 

chloride solution. Filtered after fourteen days. This orthoclase was 

of a different grinding from that used with other salts, and the precipitation of potassium given below is therefore not directly comparable with that of the other metals.

Experiment with orthoclase and potassium chloride.

Constituent.

Potassium in- 50 cm8 :

Loss ......................................................................

Content of 20 cm8 :

MgO .........................................................................

NaaO.... ...................................................................

Total ..................................:..................................

Grams.

0.1558

0. 1443

0. 0115

0. 0004

0. 0002

0. 0002

0. 0086

0. 0094

0. 0235

Milliequivalents.

3.98

3.69

0.29

0.01

0.14

0.15

0.37

. S. Dept: Agr., Bureau of Chein., Bull. 92,1905,-p. 18.

Bull, 312 07-
50 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

ORTHOCLASE AND SODIUM CHLORIDE.

Fifty cm3 dilute (0.08N) sodium chloride solution after contact 

with 25 grams orthoclase contained about 35 milligrams K20 as 

chloride.a

ORTHOCLASE AND SULPHURIC ACID.

Twenty-five grams powdered orthoclase with 50 cm3 0.1 normal sulphuric acid (2.50 millimols).

Ov-thodase and sulphuric acid: content of 40 cm3 .

Constituent.

Aho3 .... ...........................................':........-........,.........

CaO ............................................................................

MgO ............................................................................

KjO ............................................................................

Na2 0 ...........................................................................

Total.....................................................................

Total in 50 crna. ................................................................

Grams.

0. 0242

0. 0313

Undet.

0. 0010

0. 0556

0. 0108

0. 1229

0. 1536

Millimols.

a 0.92

0.03

0.59

0.17

1.71

2.14

a This is the number of divalent millimols to which 0.0313 gram alumina is equivalent.

The acid has dissolved somewhat less than its own equivalent of 

bases from the orthoclase. No change in the concentration of the 

sulphate radical could be detected. Barium sulphate obtained from 

40 cm3 before contact with orthoclase 0.4696 gram; after contact, 

0.4698 gram. Precautions were taken to prevent the precipitation of 

alkali sulphate with the barium sulphate; 6 the chlorine carried down 

was determined and a correction made for it calculated to barium 

chloride. 0

The relatively large amount of aluminum dissolved by an acid solution is noticeable as compared with the more nearly neutral salt solutions, which take chiefly the alkali metals from orthoclase. See the 

results with cupric sulphate in the presence of sulphuric acid and with 

ferric-sulphate solution, which is quite acid owing to hydrolysis. ' The 

salt solutions are similar in this respect to carbonic acid, which, according to Lemberg/ dissolves only the strong bases from silicates, while 

mineral acids dissolve all bases, including the sesquioxides.

a A. S. Cushman has very recently (U. S. Dept. Agr., Office of Public Roads Circular No. 38, 1906) 

described experiments showing that the amount of substance dissolved from orthoclase by ammonium chloride solution is decidedly greater than that dissolved by water.

& Hintz and Weber, Zeitsch. anal. Chem., vol. 45,1906, p. 40; Lunge, G., Zeitsch. fur angew. Chem., 

Heft. 12, 1905.

c Hulett, G. A., and Duschak, L. H., Zeits. fur anorg. Chem., vol. 40, 1904, p. 196.

d Zeitsch. deutsch. geol. Gesell., vol. 28,1876, p. 595.
EXPEKIMENTAL KESULT§, 51

ORTHOCLASE AND CARBONIC ACID.

Twenty grams orthoclase A taken with 50 cm3 water, carbon dioxide passed through the mixture for twenty hours. The solution contained 0.040 gram of solid. Dilute cupric-sulphate solution dissolved 

about 0.065 gram from the same quantity of this orthoclase, and water 

less than 0.010 gram.0

MICROCLINE AND CUPRIC SULPHATE.

Twenty-five grams powdered microcline, KAlSi3 08 , from Way's 

quarry, near Wilmington, Del., containing 0.03 per cent C02 ( = 

0.0075 gram or 0.17 millimol carbon dioxide in 25 grams feldspar) 

with 50 cm3 cupric sulphate solution containing 0.126 gram (2 millimols) copper. Filtered after twenty-four hours. The filtrate had 

lost approximately 0.100 gram (1.6 millimols) copper from 50 cm3 .

ALBITE AND CUPRIC SULPHATE.

Albite, NaAlSi3 08; containing 0.02 per cent C02 ( = 0.005 gram or 

0.11 millimol C02 in 25 .grams feldspar) in contact over night with 

cupric sulphate solution.

Experiment with albite and cupric sulphate.

Constituent.

Copper in 50 ran3 :

Finally .....................................................................

Content of 38.34cm3 :

CaO...... ..................................................................

Na2O .......................................................................

Total .....................................................................

Grams.

0. 1266

0. 0343

0.0923

0. 0046

0.0020

0. 0107

0. 0689

0. 0898

Millimols.

1.99

0.54

1.45

6.06

0.19

O CQ

1.08

1.41

a Including a little MgO and K2 0.

The albite after this treatment was washed and dried (it had a 

bluish-green tinge) and again subjected to the action of cupric sulphate solution.

Copper found in 50 cm3 'of cupric sulphate solution with albite.

Finally. ........................................................................

Grams.

0.1263

0. 0865

0. 0398

Millimols.

1.99

1.36

0.63

a For the action of carbonic acid solution on various minerals sec W. B. and R. E. Rogers, Am. Jour. 

Sci., 2d ser., vol. 5,1848, p. 401, and R. Miiller, Tschermaks Min. Pet. Mitt, 1877, p. 25.
52 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

ENSTATITE AND CTJPRIC SULPHATE.

Twenty grams powdered enstatite (bronzite) (MgFe) 2 (SiO3 ) 2 , from 

Webster, Jackson County, N. C., removed the color at once from 50 

cm.3 dilute cupric sulphate solution: 9 cm3 concentrated solution were 

then added, so that cupric sulphate was finally in excess.

Experiment with enstatite and cupnc sulphate.

Constituent.

Copper in 59 cm3 :

Content of 40 cm3 : 

Si02 . ...............................................

CaO ...............................................

MgO. ...............................................

KsO..... ............................................

NasO.... ..........................................

Grams.

0.6620

O O94K

n A.VIA.

Millimols.

10.41

3.53

6.88

Grams.

0. 0620

0. 2274

0. 4346

0. 0035

. 0.0003

0.0183

0.1150

 0.0007

0. 0010

0. 13S8

0. 2052

Millimols.

10. 41

3.58

6.83

0.01

0.33

2.85

0.01

0.02

3.22

4.76

In each of the experiments with enstatite the inner surface of the 

flask became coated with very fine grains which under the mircoscope 

appeared rounded. They were insoluble in water, soluble in dilute 

acid, and contained copper and sulphate, hence basic sulphate of 

copper.

AUGITE AND CUPRIC SULPHATE.

Augite, Ca(Mg,Fe)Si2O6 , from Herschell Township, Hastings 

County, Ontario. Extracted with dilute hydrochloric acid before 

powdering. As used contained 0.28 per cent CO2 , = 0.07 gram or 

1.59 millimols C02 in 25 grams augite.. Twenty-five grams of the 

finely ground mineral removed the color completely from 50 cm3 

dilute cupric sulphate solution: 4 cm 3 of concentrated solution were 

added, and cupric sulphate was then in excess.

Experiment with augite and cupric sulphate.

Constituent.

Copper in 54 cm3 :

Finally .....................................................................

Content of 32cm3 : 

SiO2 - .......................................................................

AlsOa- ...........-................ .........:................................

CaO ........................................................................

MgO........................................................................

KsO...............................................................'.........

NasO ........................................................................

Grams.

0. 4346

0. 0882

0. 3464

0. 0066

0. 0005

0. 0329

0. 0595

'

0. 1703

Millimols.

R 83

1 ^9

5.45

0.59

1.47

9 flS

3.51

oK2SO< +Na2SO4=0.0031 gram.
EXPERIMENTAL RESULTS. 53

Here more S04 has left tne solution than corresponds to the formula 

Cu4 (OH) 3S04 . This was confirmed by "a direct determination of S04 

in an 8 cm3 portion of the filtrate after removal of the copper. Barium 

sulphate obtained was 0.1688 gram, as against 0.2379 gram from the 

same volume originally, a loss of 0.0691 gram in 8 cm3 , equivalent to a 

loss of 2 millimols S04 from 54 cm3 .

Of the total copper precipitated, 5.45 millimols, about 2.12 millimols are accounted for by the carbonate present.

ANTHOPHYLLITE AND CUPRIC SULPHATE.

Twenty-five grams powdered anthophyllite (Mg,Fe)Si03 , from 

Upper Providence, Delaware County, Pa. ; removed the copper completely from 50 cm3 dilute cupric sulphate solution. Fifteen cm3 

concentrated solution was then added, so that cupric sulphate was 

finally in excess. Filtered after eleven days:

Experiment with anthophyllite and cupric sulphate.

Constituent.

Copper in 65 cm3 :

Content of 50 cm3 : 

SiOj..... ...................................................................

MnO,CaO ..................................................................

MgO.. ......................................................................

K2 0....................................:.i. ................................

Na20.... ...................................................................

Total .....................................................................

Grams.

1. 0194

0. 3019

0. 7175

0. 0104

0. 0012

0. 2771

0. 0016

0. 0041

0. 2944

0. 3827

Millimols.

16. 02

4.74

11.28

0.02

6.87

0.02

0.07

0.98

9.07

AMPHIBOLE AND CUPRIC SULPHATE.

Twenty grams powdered amphibole, Ca(Mg,Fe) 3 (Si03 ) 4 , from St. 

Lawrence County, N. Y., removed the color completely from 40 cm3 

dilute cupric sulphate solution. In the first experiment impurities 

had been separated as far as possible from the amphibole, before fine 

grinding, by means of Thoulet solution; in the second such purification was not attempted. Filtered after twenty-four hours' contact.
54 INTERACTION BETWEEN MINEEALS AND WATEE SOLUTIONS.

Experiment with amphibole and cupric sulphate.

Constituent.

Copper in 40crn:i : Originally. ........................................

Finally .............................. ; .............

Content of filtrate: 

SiO2 . .............................................. Fe2 o3 ........ ........:............................:

CaO.. ................................:............

MgO........................ .......................

KS 0. .........................:....................

Total ............................................

Grams.

0. 1015 

0

0. 1015

Millimols.

1.60 

0

1.60

24. 4 cm3

0.0009

0. 0003 

0. 0042 

. 0.0369 

0. 0049 

0. 0089

0. 0561

0. 0920

o.oi

0.08 

0.92 

0.05 

0.14

1.20

1.97

Grams.

0. 1015 

0

0. 1015

Millimols.

1.60 

0

1.60

30 cm3

0. 0001

0. 0006 

0. 0089 

0. 0471 

0. 0183 

0. 0063

0. 0813

0.1084

0.02 

0.16 

1.17 

0.19 

0.10

1.64

2.19

GARNET AND CUPRIC SULPHATE.

Twenty grams powdered garnet, Ca3Al2Si3 012 ,- from Burke County, 

N. C., with 40 cm3 dilute cupric sulphate solution. The garnet had 

been ground to about 100-mesh and separated from other minerals by 

means of Thoulet solution before it was finely pulverized. Filtered 

after three days.

Experiment with garnet and cupric sulphate.

Constituent.

Copper in 40 cm8 :

Content of 35 cm3 : 

SiOz ...................................................................... .

Fe20s......................................... . MnO. ......................................................................

MgO..--.-...:.........................-.....-..............................

K20................ ........................................................

NajO.... .............................................................:.....

Total .....................................................................

Grams.

0. 1010

0.0569

0.0441

0.0037

O AfllO

0.0060

0. 0016

0.0076

0. 0039

0.0011

. 0.0251

0. 0287

Millimols.

1.59

0.89

0.70

0.02

0.09

0.03

0 19

0.04

0.02

0.39

0.45

OLIVINE AND CUPRIC SULPHATE.

Chrysolite (olivine) (Mg,Fe) 2Si04 , from Webster, Jackson County, 

N. C., extracted with dilute hydrochloric acid before powdering. As 

used contains 0.32 per cent C02 , equal to 0.08 gram or 1.'82 millimols 

C02 in 25 grams. This amount of carbonate would precipitate about 

2.43 millimols copper. Twenty-five grams olivine removed the color 

at once from 50 cm3 dilute cupric sulphate solution; 4 cm3 concentrated solution were added, so that cupric sulphate was finally in 

excess in the solution.
EXPERIMENTAL RESULTS.

Experiment with olivine and cupric sulphate. ,

55

Constituent.

Copper in 54 cm 3 :

Finally .....................................................................

Loss ......................................................................

Content of 30 cm3 : 

Si02 . .......................................................................

AlsOs-...- ..................................................................

MgO........................................................................

K2 0 ........................................................................

Total ......................................................................

Grams.

0. 4346

0.0842

0. 3504

0.0036

0.0004

0.0038

0.0954

Trace.

0. 1032

0. 1858

Millimols.

6.83

1.32

5.51

0.01

0.07

2.36

2.44

4.40

VESUVIANITE AND CUPRIC SULPHATE.

Twenty grams powdered vesuvianite, Ca0 (Al;Fe)3 (OH,F)(SiO4 ) 5 , 

from Sanford; Me. ; removed the color completely from 40 cm3 dilute 

cupric sulphate solution. Filtered after two days' contact. Filtrate 

neutral or faintly alkaline to litmus.

Experiment with vesuvianite and cupric sulphate.

Constituent.

Copper in 40 cm 3 :

Content of 30 cm3 :

CaO ........................................................................

MgO........................................................................

KjO ........................................................................

NasO..... ..................................................................

Total .....................................................................

Grams.

.0.1012

0

0.1012.

n fiftni

0.0010

0. 0505

0. 0076

0. 0003

0.0009

0. 0604

0. 0805

Millimols.

1.59

0

1.59

0.02

0.90

0.19

0.003

0.02

1.13

1.51

EPIDOTE AND CUPRIC SULPHATE.

Twenty-five grams powdered epidote, HCa2 (Al,Fe) 3Si3013; "from 

Germany/' removed the color completely from 50 cm3 dilute cupric 

sulphate solution; 5 cm3 concentrated solution were afterwards added, 

so that copper sulphate was finally in excess in the solution. Filtered after nine days. Basic copper sulphate was deposited on the 

flask wall.
56 INTERACTION BETWEEN MINERALS AND WATEE SOLUTIONS. 

Experiment with epidote and cupric sulphate.

Constituent.

Copper in 55 cm3 : 

Originally. ....................... .... . ... . . .. ...........

Finally.. ............................. . . . . ... ... ... ... .............

Loss.. .............................. ... . . ... .. ... .................

Content of 40 cm3 : 

SiO2 . .......................................................................

Fe2 03 , etc ..................................................................

MnO............................. ..... .. . .. ................

CaO ........................................................................

MgO.........................................................................

K2 0..... ...................................................................

Na2O .......................................................................

Total. ............................... ....................................

Grams.

0:4238

0. 0705

0. 3533

0. 0039

0. 0012

0. 0046

0.'0317

0. 0177

0. 0017

0. 0036

0. 0644

0.0886

Millimols.

6.67

1.11

5.5(5

0.02

0.06

0.57

0.44

0.02

0.06

1.17

1.01(1)

PEEHNITE AND CUPRIG SULPHATE.

Twenty-five grams prehnite, H2Ca2Al2Si3 012 , from Upper Montclair, N. J., removed the color from 50 cm3 cupric sulphate solution 

containing 0.126 gram copper.

TOURMALINE AND CUPRIC SULPHATE.

Black tourmaline, Pierrepont, St. Lawrence County, N. Y.; 20 grams 

removed the color completely from 40 cm3 cupric sulphate solution 

containing 0.1 gram copper. Filtered after twenty-four hours. The 

filtrate was neutral to litmus and contained boron.

MUSCOVITE AND CUPRIC SULPHATE.

Twenty-five grams muscovite, H2KAl3Si3Oi 2 , from Jackson County, 

N. C. ; containing 0.026 per cent C02; equal to 0.0065 gram or 0.15

millimol C02 in the 25 grams, removed the color completely at once 

from 50 cm3 dilute cupric sulphate solution; 4 cm3 concentrated 

solution were added, furnishing an excess of cupric sulphate to the 

solution.

Experiment with muscovite and cupric sulphate.

Constituent.

Copper in 54 cm3 :

Content of 30 cm3 : 

Si02 , A1 2 03 , etc .............................................................

CaO ........................................................................

MgO ........................................................................

K2 0 ........................................................................

Na2 0 .......................................................................

Total .....................................................................

Grams.

0. 4346

0. 1632

0. 2714

0. 0019

0. 0013

0. 0084

0. 1203

0. 0209

0. 1528

0. 2750

Millimols.

6.83

2.56

4.27

0.02

0.21

1.28

0.34

1.85

3.33
EXPERIMENTAL RESULTS. 57

BIOTITE AND CUPRIC SULPHATE.

Biotite, (HK) 2 (Mg,Fe) 2 (Al,Fe) 2Si3 012 , from Rossie County, N. Y., 

containing 0.15 per cent CO2 , =0.038 gram or 0.86 millimol CO2 in 

25 grains biotite. Twenty-five grams removed the color at once 

from 50 cm3 dilute cupric sulphate solution; 4 cm3 concentrated 

solution were then added, making cupric sulphate in excess.

Experiment with biotite and cupric sulphate.

Constituent.

Copper in 54 cm3 :

Finally ................... ............................................

Content of 30cm3 : 

Si02 . .................... .. ....................... ............ ...

CaO ........................................................................

MgO. .......................................................................

K,'0..... ..............................:........ ............................

Nn,20 .......................................................................

Total ...................................:.................................

Content of 54 cm3 . ..............................................................

Grams.

0.4346

0. 224G

0. 2100

0.0027

0.0032

Tr.

0.0635

0.0443

0.0046

0.1183

0.2129

Millimols.

6.83

3.53

3.30

0.09

1.57

0.47

0.07

2.20

3. 96

The bases removed are here in excess of the copper precipitated, 

and it was found that water alone extracted a considerable quantity 

of material from the powdered mineral.

TALC AND CUPRIC SULPHATE.

Twenty grams powdered talc (H2Mg3Si4012 ), from Harford County, 

Md., removed the copper almost completely from 40 cm3 dilute cupric 

sulphate solution. Filtered after three days. .

Experiment with talc and cupric sulphate.

Constituent.

Copper in 40 cm3 :

Finally .....................................................................

Content of 30cm3 : 

Si02 ........................................................................

AlsOa, etc ...................................................................

CaO........................................................................

MgO...................... ..................................................

K2O..... ...................................................................

NasO..... ..................................................................

Total .....................................................................

Grams.

0.1010

iTr.

0.1

0.0040

0.0003

0.0018

0.0387

0.0005

0.0464

0.0619

Millimols.

1.59

Tr.

1.5

0.01

0.03

0.96

0.01

1.02

1.36

a Ammonia gave slight blue color.
58 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

SHALE AND CUPRIC SULPHATE.

A shale from Newtown, Ariz. ("Morenci shale")? finely pulverized in 

an agate mortar and mixed with twice its weight of solution. The 

shale was made up chiefly of kaolin, glauconite, and epidote, and 

contained 6.74 per cent K2 0 and 0.44 per cent Na2O.

Experiments with shale and cupric sulphate. 

COPPER IN 50 CUBIC CENTIMETERS.

]

Grams.

0. 1277

0.0063

0.1214

Millimols.

2.01

0.10

1.91

Grams.

1 0.1277

0

0. 1277

Millimols.

2.01

0

2.01

Grams.

3.747

3.584

0.163

.

Millimols.

58.91

56.35

2.56

CONTENTS OF FILTRATES.

Constituent.

CaO ..........................

MgO. .........................

K20 ..........................

NasO. .......................

Total...................

80 cm3.

0.0010 

0.0247 

0.0518 

0.0840 

0.0035

0. 1703 

0. 1565

0.03 

0.44 

1.28 

0.89 

0.06

2.70 

1.69

82.6 cm3 .

0.0011

' 0.0036 

0.0185 

0.0754 

0.0625 

0.0046

0. 1657 

0. 1003

0.12 

0.33 

1.88 

0.66 

0.07

? 06

1.85

Contact in the first experiment was for a few days, in the second 

for four months, and in the third for a few hours. The dilute solutions were neutral to litmus after contact with the shale.

The microscopic examination was made by Mr. W. Lindgren of 

the Geological Survey,- at whose suggestion the action of the shale 

toward cupric sulphate solution was examined. The chemical analysis was by Dr. W. F. Hillebrand, of the Geological Survey. The 

occurrence of cuprite in this shale is common at Morenci.a

CLAY GOUGE WITH CUPRIC SULPHATE.

Clay gouge vein-filling from Silver Plume, Colo. Contains 3.92 

per cent C02 ( = 0.784 gram or 17.84 millimols in 20 grams), largely 

as ferrous carbonate; 3.52 per cent K2 0, 0.18 per cent Na20. Ground 

in agate mortar. Twenty grams taken with 40 cm3 concentrated 

cupric sulphate solution. Filtered after three days.

Experiment with clay gouge and cupric sulphate.

Constituent.

Copper in 40 cm3 :

Loss ......................................................................

Grams.

2.382

2.091

0.291

Millimols.

3.75

3.29

0.46

.oSee Lindgren, Prof. Paper U. S. Geol. Survey, No. 43, p. 191.
EXPERIMENTAL RESULTS. 59

The bases dissolved from the gouge were chiefly alumina and potash. 

The ferrous carbonate appears to have taken little if any part in the 

precipitation of the copper, in contrast with the action of the more 

soluble calcium carbonate, which is completely dissolved by cupric 

sulphate solution (see p. 84).

CLAY GOUGE WITH SILVER SULPHATE.

Twenty grams of the finely ground material taken with 40 cm3 

silver sulphate solution. Filtered after four days.

Experiment with clay gouge and silver sulphate.

Constituent.

Silver in 40 cm3 :

Finally.... .................................................................

Content of 25cm3 :

A1203 . ......................................................................

CaO..... ................................................................... Mgo.. .............................................:........................

K2 0..... ..............:...-................................................

Na2 0.......................................................................

Total......................................................./.............

Content of 40 cm'. ..............................................................

Grams.

0.0844

Tr.

0.084'

0. 0012

0. 0002

0. 0013

0. 0020

0. 0222

0. 0010

0. 0291

0. 0466

Millimols.

0 7fl

Tr.

0.78

0.02

0.06

0.24

0.03

0.35

0. 5(1

The filtrate gave no reaction for ferric salt with potassium' sulphocyanate nor for ferrous with ferricyanide. Again the ferrous carbonate apparently had not been affected.

Work with this material was made possible through the kindness 

of Mr. G. H. Garrey, who placed samples at the writer's disposal.

CALCITE (ICELAND SPAR) AND CUPRIC SULPHATE.

0.0502 gram ( = 0.502 millimol) calcite in contact with 50 cm3 dilute 

cupric sulphate solution. Filtered after two days.

Calcite and cupric sulphate: content of 50 cm 3 .

Constituent.

Copper:

Finally .....................................................................

BaSO<:

Finally. ....................................................................

Grams.

0. 1263

0. 0820

0. 0443

0. 4674

0.4284

0.0390

Millimols.

1.986

1.289

0.697

2.002

1 QOC

0. 167

The loss of copper is to the loss of sulphate as 4:0.96, indicating the 

precipitation of a basic sulphate similar in composition to brochantite
60 INTEKACTION BETWEEN MINEKALS AND WATEE SOLUTIONS.

and langite. This is in accordance with the work of Becquerel." The 

precipitate contained no calcium. Brochantite varies in composition 

from' CuS04 ,5/2CuO,3H2O to CuS04 ,7/2CuO,aq. Moissan, Traite, 5,83.

FLUORITE AND CUPRIC SULPHATE.

Fluorite removed practically no copper at all from dilute cupric 

sulphate solution.

PYRITE AND CUPRIC SULPHATE.

Ground pyrite (25 grams) washed with sulphuric acid, alcohol, and 

ether removed 0.0286 gram copper from 50 .cm3 cupric sulphate solution containing originally.0.1263 gram copper.

GLASS AND CUPRIC SULPHATE.

One hundred cm3 1 per cent cupric sulphate solution in contact ten 

days with 71 grams coarsely powdered window glass.

Glass and cupric sulphate: content of 50 cm?..

Constituent.

Copper in 50 cm3 :

CaO .:.........................................................................

MgO............. ..............................................................

K2 0 ...........................................................................

Na2 0 ..........................................................................

Total ....................................................................

Grams.

0. 1271

0. 1200

0. 0071

0. 0070

0. 0029

0.0001

0. 0006

0. 0026

0. 0132

Millimols.

2.00

1 89

0.11

0.000

0.052

0.002

0.007

0.042

0. 103

The glass, after washing with water until the washings no longer contained copper, retained a green color, unmistakable on comparison 

with the original glass. Extraction with hydrochloric acid gave a 

solution from which 0.0056 gram copper and 0.0057 gram barium sulphate were obtained, i. e., 4Cu: 1.1S04 .

An accumulation of sediment in the stock bottle of 1 per cent cupric 

sulphate solution gave 0.0083 gram copper and 0.0084 gram barium 

sulphate, again 4Cu:l.lS04 . Contact with a silicate precipitates in 

these cases, therefore, the same basic sulphate which results on treating cupric sulphate solution with insufficient alkali for complete precipitation.

POSSIBLE APPLICATION TO GEOLOGIC PHENOMENA.

What part these reactions have actually played in ore deposition 

and other geologic changes is for the geologist to decide. Lindgren b

oComptes rendus, vol. 34, 1852, p. 573.

b Copper deposits of the Clifton-Morenci district, Arizona: Prof. Paper U. S. Geol. Survey No. 43, 

1905, p. 119.
EXPERIMENTAL RESULTS. 61

has recently noted the fact that the basic copper sulphate, brochantite, 

whose composition is that of one of the substances formed by the 

action of silicates on copper-salt solutions, is an ore of more frequent 

occurrence than is usually supposed, it having been confounded in 

many cases with chrysocolla or malachite. The sulphide ores could 

readily result from such basic compounds through reduction of the 

sulphate by organic matter or by other oxidizable substances. The 

change from the cupric to the more commonly found cuprous compounds, such as cuprite and chalcocite, could be due to the same reducing agents or even to hydrogen sulphide. Cuprous sulphide appears 

to be more stable than cupric sulphide at high temperatures, and it 

may well be more stable at lower temperatures also. A cupric salt 

precipitated by hydrogen sulphide under ordinary conditions forms 

some cuprous sulphide for example, 2CuS04 + 2H2S = Cu2S +S + 

 2H2S04 , in addition to the cupric sulphide which makes up the main 

mass oi' the precipitate, that is, CuS04 +H,S -=CuS +H2S04 .

As/ illustrating further the reducibility of cupric compounds by 

hydrogen sulphide, cupric sulphide when dissolved in hydrochloric 

acid forms cuprous chloride 2CuS+2HC1 =2CuCl+H2S+S. This 

reaction is mentioned by Gmelin-Kraut a and has been confirmed by 

the writer,

FORM OF PRECIPITATION.

The immediate condition in which the metal is thrown down from 

the solution by a silicate is perhaps of secondary importance, subject 

as the newly formed substance is to spontaneous change into a more 

stable form, as from amorphous or colloidal to crystalline in structure, 

and also to the modifying and transforming influence of continually 

renewed portions of active solutions. The fact of prime significance 

geologically seems to be that by a process of simple chemical exchange 

the metal may be removed from solution and fixed in the solid state 

and thus concentrated, by contact with even the most stable of the 

silicates.

The changes under consideration involve the action of the alkali or 

alkaline-earth salt of a weak acid (silicic or alumino-silicic) and are 

thus analogous to the more familiar behavior of sodium carbonate 

with solutions of salts of the metals. Owing to hydrolysis the precipitates caused by sodium carbonate tend to split up into the acid and 

base (carbonic acid and metal oxide or hydroxide) and the weaker 

the base the more marked is this action. The precipitate from 

solutions of salts of strong bases, such as calcium chloride, is the normal carbonate; a weaker base, such as nickel, is precipitated as basic 

carbonate or a mixture of the normal carbonate with hydroxide or 

oxide; while the very weak bases, as iron in ferric salts, are precipia Handbuch, 6th eel., vol. 3, p. 620.
62 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

tated as hydroxide or oxide containing little or no carbonate, and the 

corresponding quantity of carbon dioxide is set free:

CaCl2 +Na2C03 =CaC03 +2NaCl;

2NiCl2 +2Na2C03 +H2 0 =NiC03 ,Ni(OH) 2 +C02 +4NaCl; 

2FeCl3 + 3Na2CO3 + 3H2O = 2Fe(OH)3 + 3CO2 + GNaCl.

The action of a silicate may be expected to be similar to that of 

the carbonate, with the difference that the silicate, as the salt of a 

weaker acid than carbonic, will tend to produce a more basic precipitate that is, one containing more hydroxide.

The hydroxide of the metal, with more or less silicate and an amount 

of silica corresponding to the quantity of precipitated hydroxide, 

will therefore make up the precipitate in case the solution and the precipitant come together under such conditions that the metal is completely precipitated. When insufficient alkali for complete precipitation 

is added to a metal salt solution the resulting precipitate is in some 

cases a basic salt where with excess of alkali it would be a hydroxide. 

Cupric sulphate, for instance, with alkali in excess gives CuSO4 + 

2KOH = Cu(OH) 2 + K2S04 ; but where the copper salt is in excess the 

result is 4CuSO4 + 6KOH = Cu4 (OH) 0SO4 + 3K2SO4 . The same basic 

salt is formed by calcium carbonate or by such silicates as glass, 

acting on excess of cupric sulphate solution. There seems,to be, 

therefore, reason to expect that in the precipitations with which 

we are here concerned the same basic salt will play an important 

part. As a matter of fact, in the cases of enstatite and epidote contact with cupric sulphate caused the formation of a coating on the 

flask wall which contained copper and sulphate and was insoluble 

in water, and was therefore basic copper sulphate. After filtration 

of shale from cupric sulphate solution a similar precipitate formed.

That the silicate of the metal is actually formed to some extent when 

orthoclase, for instance, is brought into contact with metal salt solutions is evident in the case of the sodium salt, where precipitation as 

hydroxide is out of the question. The experiment shows also that 

although barium is precipitated (50 cm3 solution lose 0.0802 gram 

= 0.58 millimol barium) the resulting solution remains neutral to litmus and hence contains practically no barium hydroxide whatever. 

Barium has therefore not been precipitated from this solution in the 

form of hydroxide, for this would necessitate the formation of a 

saturated solution of that compound. The conclusion seems inevitable that the barium which has left the solution is in combination as 

a silicate.

Further evidence that the silicate of the precipitated metal is 

formed is found in the fact that the reverse reactions can be made to 

take place, while the precipitation of hydroxide or basic sulphate of 

copper is under these conditions practically an irreversible reaction. 

Orthoclase treated with cupric sulphate solution gives up potassium
EXPERIMENTAL RESULTS. 63

for copper, which is precipitated. The resulting slightly green 

powder, washed until water extracts at most a minute trace of copper, 

if treated with potassium sulphate solution gives up copper in considerable quantity, thus reversing the first reaction. Precipitated 

cupric hydroxide or basic sulphate similarly treated with potassium 

sulphate solution gives up no copper. The following are the experimental data on this point:

The copper is not extracted from the orthoclase by water: 50 cm3 

water stirred up with 25 grams of washed and air-dried orthoclase 

which had taken 0.073 gram copper from solution dissolved a scarcely 

weighable trace (about 0.05 milligram) of the metal.

The copper is extracted by potassium sulphate solution: After 

washing, as just described, and freeing from water by suction 50 cm3 

potassium sulphate solution of normal concentration were stirred up 

with the orthoclase and the solution was then filtered. Fifty cm3 

filtrate now contained 0.008 gram copper.

Copper is not extracted from cupric hydroxide' or basic cupric 

sulphate by potassium sulphate solution: Fifty cm3 cupric sulphate 

solution (0.127 gram copper) was precipitated with sodium hydroxide, and after thorough washing neither water nor potassium, sulphate solution dissolved copper from the precipitate. About one 

gram basic cupric sulphate was prepared by treating cupric sulphate 

with insufficient sodium hydroxide for complete precipitation. After 

thorough washing water still dissolved a trace of copper from the 

product. The solubility in potassium sulphate solution was not 

appreciably greater.

Ano-ther sample of orthoclase treated as above described gave a 

similar result. Several successive extractions with potassium sulphate solution yielded decreasing quantities of copper. Anthophyllite after contact with cupric sulphate and washing gave only a 

trace of copper when extracted with water. Fifty cm3 potassium sulphate solution, however, removed about 0.006 gram copper. Vesuvianite which had been treated with-cupric sulphate solution of such 

dilution that the copper was completely precipitated gave up no 

copper on extraction with potassium sulphate solution, owing probably to the precipitation of the copper entirely as hydroxide where 

the precipitant is in excess, as it was in this case.

Van Bemmelen a shows that salts which are not removed from a 

colloid by water may be dissolved by means of another salt solution. 

Calcium chloride, for instance, in a well-washed preparation of chromic 

hydroxide, was taken out by a concentrated solution of potassium sulphate. There is no reason to believe that the copper extracted from 

orthoclase and other silicates, as just described, was in a condition 

similar to that of the calcium chloride in Van Bemmelen's experiment.

a Jour, prakt. Chem., vol. 23, 1881, p. 387.
64 INTERACTION BETWEEN MINERALS AND WATER SOLUTIONS.

SUMMARY.

The natural silicates precipitate the metals from solutions of salts, 

while at the same time the bases of the silicates are dissolved in quantities nearly equivalent to the precipitated metals. The bases most 

commonly replacing the metals. in these processes are potassium, 

sodium, magnesium, and calcium. Where exact equivalence is wanting, it is attributable either to solubility of the mineral in pure water 

or to the precipitation of basic salts.

The metals are precipitated as hydroxides or basic salts (in the case 

of cupric sulphate, for instance, as a basic cupric sulphate similar to 

brochantite or langite) with .more or less metal silicate.

The specific materials on which work was done are albite, amphibole, augite, biotite, enstatite, garnet, clay gouge, kaolin, microcline, 

muscovite, olivine, orthoclase (3), prehnite, shale, talc, tourmaline, and 

vesuvianite, with cupric sulphate solution; and orthoclase with salts 

of sodium, potassium, magnesium, calcium, strontium, barium, manganese, iron, nickel, copper, zinc, silver, gold, and lead. Experiments were also made on the action of kaolin on solutions of salts 

of zinc and iron, and of glass, fluorite, and pyrite on cupric sulphate 

and of carbonic and sulphuric acids on orthoclase.

Adsorption, a mechanical surface attraction, plays a comparatively 

insignificant part, if any, in the retention of copper by kaolin. If 

adsorption is lacking in the case of kaolin, it seems reasonable to 

assume that it is lacking in the case of other silicates also.

Under the conditions of the experiments described the precipitation 

of copper caused by orthoclase does not differ materially in quantity 

from that caused by pyrites.

A dilute salt solution decomposes orthoclase and dissolves its constituents to about the same extent as does a saturated solution of carbonic acid. Both are much more efficient in this respect than water.

Orthoclase (and presumably other alkali silicates also) accelerates 

the oxidation of ferrous sulphate by the oxygen of the air. A similar 

influence may be expected in other oxidation reactions that take place 

more readily in the presence of alkali than in the presence of acid.

It is worthy of note that the iron of ferrous silicates is not found in 

solution replacing copper after the" precipitation of the latter. This 

was also true of the iron in a clay gouge containing considerable ferrous carbonate.

The writer wishes to acknowledge gratefully suggestions and assistance from various geologists of the Survey, especially from Mr. W. H. 

Weed and Mr. Waldemar Lindgren. He is also under obligation to 

Prof. G. P. Merrill and Mr. Wirt Tassin, of the National Museum, and 

others for minerals furnished.
INDEX.

A.

Absorption, nature of ..................... 11,15

influence of concentration on........... 34-36

of bases, dependence of, on quantity of

solution......................... 14

Acetic acid, action of, on decomposed granite.............................. 26

Acid ion, precipitation of................... 30-31

Acidity of salt solutions after filtration,

cause of......................... 8-9

Acids, nature of action of, on aluniino-silicates............................ 50

' v separation of bases from, in salt solutions, by diffusion.............. 9

Adsorption, extent of...................... 36

negative results concerning.......... 36,39,64

Ostwald's discussion of, reference to... 36

"* (footnote)

phenomena of......................... 7,8,25

Albite, experiments with................... 51

Alkali, free, absorption of, by quartz, experiment showing.............. 29

absorption of, by soils.................. 28-29

action of, on silicates, nature of........ 29

Alkali salts, action of, on granite........... 27

Alkaline solutions, absorption from, as compared with absorption from 

neutral solutions ............ 12,13,15

action of clay, etc., on.................. 28-31

Alumino-silicates, absorption by, from salt

solutions....................... 11

relative stability of..................... 22

Aluminum, amount of, dissolved by acid

solution......................... 50

Aluminum oxide, action of, on .salt solutions. ........................ 20,28,30

Ammonia, absorption of, by soil, from salts

of ammonium............ 11,13-14,19

absorption of, from ammonium hydroxide solutions............... 29

Ammonium, substitution of, for other bases

in silicates................... 12,21,22

Ammonium alumino-silicate, preparation

of............................... 11

Ammonium carbonate, absorption of, by

ferric oxide..................... 30

absorption of, by chabasite............ 13

Ammonium chloride, absorption of, by ferric oxide........................ 30

action of, on chabasite................. 12

action of, on granite........,/*:........ 26

reaction of, with ferric oxide........... 19

Ammonium hydroxide, reaction of, with

soil.... .'........................ 13-14

Bull. 312 07 5

Ammonium phosphate, reaction of, with

soil.............................'13-14

Ammonium salts, absorption of acid radical from, by ferric oxide........ 30

ammonium absorbed by soil from...... 13

reaction of, with soil and minerals... 11,13-14 

Ammonium substitution compounds, action of.......................... 13,21

Ammonium sulphate, reaction of, with

ferric oxide..................... 19,30

Amphibole, experiments with.............. 53-54

Analcite, absorption of sodium from, by ammonium chloride solution...... 22

transformation of, to leucite........ 20-21,34

Anion, influence of, in action of soils on solutions of potassium salts, table 

showing......................... 14

AnttiophyJlite, experiment with............ 53

Aristotle, on filtration...................... 7

Armsby, H. P., on law of mass action as 

applied to absorption of bases by 

silicates......................... 33-34

Augite, experiments with.................. 52-53

Auric chloride, experiments with........... 41

B.

Bacon, Francis, on filtration of sea water.. 7 

Barium, precipitation of, form of.......... 62

Barium chloride, experiments with......... 41,49

Bases, absorption of, by alumino-silicates,

order of...................... 12,13,22

absorption of, dependence of, on quantity of solution................. 14

exchange of, acidity caused by......... 8

replacement of, by potassium, in experiments with soil .................. 15

separation of, from acids, by diffusion in

solutions....................... 9

Bauxite, experiments with................. 26

Becker, O. F., on concentration of metals by

dialysis......................... 8

Becquerel, experiments by.................. 60

Bemmelen, J. M. van, experiments by... 23-25,63 

on absorption of salts by soil.......... 24,25

on electrolytic dissociation as explaining

reactions of salts and minerals.. 28 

on holding of electrolytes by colloids.... 36

on hydrous oxides...................... 19

on influence of calcium carbonate....... 31

on precipitation of acid radical as affected by extraction with acid... 31 

on reaction between alkali and silicates.. 28 

Berzelius, J. J., on filtration................ 7

65
66 INDEX.

57

22

Biotite, experiment with. ................s .

Bischof, G., on assimilation of potassium 

rather than sodium by plants... 

Bodeker, C., on relation between concentration of solution and amount of 

absorption...................... 34-35

Borate radical, precipitation of, by acidextracted soil................... 31

Borax solution, experiments with.......... 31

Briggs, L. J., on action of alkali on quartz... 29 

on adsorption of salts by quartz........ 27

on changes in concentration of solutions

caused by filtration............. 7

Brochantite, possible mode of formation of. 60-61 

Bronzite, experiment with.................. 52

Bruni, G., on separation of acid and base by

diffusion........................ 10

C.

Calcite, experiments with................... 59-60

Calcium, absorption of, by silicate, experiment showing................... 34

replacement of, by magnesium, in silicates ............................ 22

Calcium carbonate, influence of............. 31-33

Calcium chloride, action of, on granite...... 27

action of, on sodium alumino-silicates... 33-34 

experiments with............... 26,41,48,61,63

Calcium oxide, absorption of, by soils, experiments showing.............. 17

Calcium phosphate, action of, on ferric and

aluminum oxides............... 30

Calcium salts, precipitation of acid ions as.. 30

Calcium silicates, stability of, as.compared

with magnesium silicates....... 22

Cameron, F. K., and Bell, J. M., on literature 

of research concerning reactions 

between salt solutions and silicates. ........................... 6

Carbonate radical, precipitation of, by acidextracted soil................... 31

Carbonates, absorption of, by quartz...... 29

precipitative action of, compared with that of silicates..... 62

Carbonic acid, action of, on substituted

potassium...................... 26

removal of bases from silicates by... 32,50,51-

Carnallite, metamorphism of clay by....... 32

Chabasite, experiments with............ 12-13,22

Charcoal, absorption of potassium chloride

by.............................. 15

Chloride io~n, nonabsorption of, by soil..... 15,16

Clarke, F. W., and Steiger, George, experiments by, showing substitution 

of bases......................... 12

Clausius, R., electrolytic dissociation theory 

of, cited to explain reactions of 

salts and minerals.-. .........'... 28

Clay, absorption of bases from salt solutions

by.............................. 11

filtration of salt solutions through, results of......................... 11

metamorphism of, by overlying carnallite bed......................... 32

permeability of, to solutes.............. 9

Clay gouge, experiments with.............. 58-59

Page. 

Colloids, action of, on salt solutions...... 25,27-28

equilibrium between solutions and...... 35

impermeability of clay to............... 9

Concentration of metals by dialysis, possibility of......................... 8

Concentration of solutions, influence of..... 12,

14,34-36,42

Contact, time of, extent of absorption as related to......................... 11,14

Copper, nonreplacement of, by iron of ferrous silicates.................... 64

Crystalloid solutes, permeability of clay to.. 9 

Cupric chloride, experiments with.......... 41,44

Cupric nitrate, experiments with........... 41,43

Cupric oxide, action of, on salt solutions.... 28

Cupric sulphate, experiments with........ 8,9-10,

38-39,40,41-43,51-60,62-63 

nitration of solution of, effect of........ 8,9

hydrolysis of........................... 9

precipitates from....................... 62

experiment with........................ 9

Cushman, A. S., experiments by, showing

action of water on silicates..... 27

on dissolution of orthoclase by ammo-' = 

nium chloride solution.......... 50

on removal of barium and aluminum

from solution by China clay.... 49

D.

Decomposition, double, acidity caused by... 10 

Deposition of metallic ores, factors in....... 5-6

De.smin, experiment with................... 22

Dialysis, concentration of metals by....... 8

Diffusion, acidity caused by, after filtration. 9 

Dittrich, M., on reaction between granite

and salt solutions.............. 26

Duschak, L. H., and Hulett, G. A., on correction for chlorine............. 50

E.

Eichhorn, H., experiments by ............. 12-13

on destruction of absorptive power of

silicates by acid................. 29

on reactions between salt solutions and

natural minerals................ 13

Electrolytic dissociation theory, citation of, 

by van Bemmelen to explain reactions of salts and minerals ... 28 

Enstatite, experiment with................ 52

Epidote, experiments with ................ 55-56

Experimental work, methods followed in... 37 

results of................................ 38-60

F.

Feldspars, reaction of with salt solutions. 11-12,26 

Ferric oxide, absorption of potash by....... 30

absorption of salts by.................. 19

action of, on salt solutions............. 28

Ferric salts, precipitates from.............. 61-62

Ferric sulphate, experiments with....... 41,46-47

hydrolysis*6f............................ 9

Ferrous sulphate, experiments with........ 41,46

Filtration, effect of, on salt solutions....... 7,8,9

Fluorile, experiments with................. 60

Freundlich,Herbert, on adsorption ........ 36
INDEX. 67

Garnet, experiment with................... 54

Garrey, G. H., aid by....................... 59

Geologic phenomena, application of experiments to....................... 60-61

Glass, experiments with.................... 60

Godfrey, Boyle, on filtration of sea water... 7 

Gold chloride,experiments with............ 45

Granite, action of salt solutions on......... 26-27'

Grinding of the minerals, influence of extent

or fineness of................... 40

H.

Hales, Stephen, on filtration of sea water... 7

Henneberg and Stohmann, experiments of.. 13-14 

on absorption of free alkali............. 28-29

Hillobrand, W. F., aid by................... 58

Hintz, E., and Weber, H., on means of preventing precipitation of alkali 

sulphite with barium sulphate. 50

Hornblende granite, action of salt solutions

on.............................. 26-27

Hulett, G. A., and Duschak, L. H., on correction for chlorine............. 50

Hydrochloric acid, action of, on decomposed

granite......................... 26

destruction of absorptive power for acid

radical by...................... 31

effect of extraction of clay by, on absorption of free alkali............... 28

extraction of soils with, effects of....... 28,31

Hydrolysis, influence of, in causing acidity

after filtration.-................. 9

Hydrous oxides, water of.................. 19

Hydrous silica, behavior of, toward solutions.. ........................... 24-25

I.

Iceland spar, experiment with.............. 59-60

Iron of ferrous silicates, non-replacement of

copper by....................... 64

J.

Joly, J., experiments by, showing action of 

sea water on rocks and minerals.

K.

26

Kaolin, experiments with............... 38-39,45

filtration of salt solutions through..... 8

King, F. H., on changes in concentration of

solutions caused by filtration... 7 

Kohler, Ernst, on adsorption............... 39

on filtration of salt solutions through

kaolin........................... 8

Krawkow, S., on motion of solutions in

soils............................. 7

Kullenberg, 0., experiments by, showing 

absorption by soil from salt solutions. ........................... 16-19

on removal of phosphate radical from

salts by soils.................... 30

L.

Lagergren, S., experiments by, on adsorption of salts by kaolin and other 

substances...................... 25

Laterite, action of potassium chloride solution on.......................... 26

Lead nitrate, experiments with........... 8,41,44

solution of, filtration of, effect of....... 8

Lemberg, J., experiments of............. 20-23,32

. on absorption of potassium rather than

sodium by plants............... '22

on action of carbonic acid on silicates... 50 

on assimilation of potassium by plants,

chemical cause of............... 22

on nature of processes involved in his

experiments..................... 22

on transformation of clay by calcium

carbonate....................... 32-33

on transformation of the feldspars..... 23

Leucite, transformation of analcite to...... 34

transformation of, to analcite.......... 20-21

Liebig, Justus, on mechanical or physical 

action of soils in absorbing bases 

from salts...................... 15-16

on precipitation of silicate radical...... 30

Lime, absorption of, by soils, experiments

showing......................... 17

Lindgren, Waklemar, acknowledgments to. 64 

aid by................................... 38,58

on occurrence of brochantite............ 60-61

Lunge, G., on means of preventing precipitation of alkali sulphate with 

barium sulphate................ 50

M.

Magnesia, absorption of, by soils, experiments showing.................. 17

Magnesium, replacement of, by calcium in

silicates......................... 22

Magnesium chloride, action of, on granite.. 27 

experiments with '..................... 8,26,27

filtration of, effect of.................... 8

Magnesium oxide, absorption of, by soils,

experiments showing........... 17

Magnesium salts, experiments with........ 13

Magnesium silicates, stability of, as compared with calcium silicates.... 22

Magnesium sulphate, action of, on wollastonite........................... 20

experiments with.................... 41,47-48

Manganese dioxide, action of, on salt solutions.. .......................... 28

Manganous sulphate, experiments with.... 41,47

M!ass law, application of.................... 33-34

Matteucci, Carlo, on filtration.............. 7

Mercuric oxide, action of, on salt solutions. 28 

Merrill, G. P. acknowledgments to......... 64

on zeolitic silicates in soils ............. 11

Metastannic acid, action of, on salt solutions ............................ 28

colloidal, experiments with............. 35

Metathesis, acidity caused by.............. 10

Meyerhoffer, W., experiments by, showing 

reaction between potassium carbonate and bairum sulphate.... 36

Microcline, experiment with................ 51

Millimol, definition of....................... 38

Mineral surface exposed to action of salt solutions, influence of amount of.. 39-40
68 INDEX.

Page.

Minerals used in experiments, pulverization

of, influence of fineness of....... 40

Miiller, R., on action of carbonic acid solutions on minerals............... 51

Muscovite, experiment with................ 56

N.

Natrolite, experiments with.............. 12

Neutral solutions, absorption from, as compared with absorption from alkaline solutions.............. 12,13,15

Nickel salts, precipitates from.............. 61

Nickel sulphate, experiments with.......... 41, 47

0.

Ocean,- salthess of, chemical causes of....... 22-23

Olivine, experiment with................... 54-55

Ore deposition, factors in................... 5-6

Orthoclase, acceleration of oxidation of ferrous sulphate by................ 64

o actionof wateron........................ 27

experiments with.............. 40,51,62-63,64

replacement of potassium by copper in, 

when treated with cupric sulphate .......................... 63

specimen of, used in experiments, source

of........._.................... 37

Ostwald, W., experiments by, showing solubility of alkaline-earth sulphates 

in acids......................... 36

Oxides, hydrous, water of.................. 19

P.

Peters, E., experiments by................. 14-15

on destruction of absorptive power of

silicates by acid................ 29

on mechanical or physical action of soils

in absorbing bases from salts... 15 

Phosphate ion, absorption of, by soil....... 15,30

Phosphate radical, precipitation of, by acidextracted soil................... 31

Plants, assimilation of potassium by, rather

than sodium.................... 22

Potassium, absorption of, experiments

showing........................ 15

assimilation of, by plants, chemical

cause of......................... 22

Potassium alumino-silicates, experiments

with............................ 22,32

Potassium carbonate, interaction of, with

ferric oxide..................... 30

Potassium chloride, absorption of, by charcoal ............................. 15

absorption of, by ferric oxide........... 19

action of colloid oxides on.............. 28

action of, on granite.................... 26

reaction of, with oxides of metals....... 28

action of soils on solution of............ 14

experiments with........ 15,23,25,26,27,29,49

Potassium hydroxide, absorption of, by

clay............................. 28

action of, on silicates, nature of........ 29

reaction between silica and............. 10

Potassium nitrate, absorption of, by ferric

oxide........................... 19

Page. 

Potassium nitrate, action of colloid oxides

on.............................. 28

changes in concentration of solutions of,

caused by filtration............. 8

Potassium oxide, absorption of, by ferric

oxide........................... 30

absorption of, by soils.................. 18

Potassium salts, reaction of, with soil...... 13-14

Potassium silicates, relative stability of, as

compared with sodium silicates. 22 

Potassium sulphate, absorption of, by ferric oxide........................ 19,30

action of colloid oxides on.............. 28

changes in concentration of solutions of,

caused by filtration............. 8

experiments with....................... 63

Potash, absorptio'n of, by ferric oxide...... 30

absorption of, by soils, experiments

showing........................ 18

See also Potassium oxide. 

Precipitates, nature of..................... 61-64

Prehnite, experiment with................. 56

Pulverization of minerals, fineness of, influence of....................... 40

Pyrite, experiments with................... 60

precipitation caused by, compared with

that caused by orthoclase....... 64

Q. 

Quartz, absorption of alkali by............ 29

absorption of carbonates by............ 29

R.

Rautenberg, F., experiments by, showing 

absorption by soil from salt solutions. ........................... 16

on action of aluminum oxide on ammonium chloride.................... 20

Reversible reactions, occurrence of, between

salt solutions and silicates...... 12,13

Rohland, P., on permeability of clays to

solutes.......................... 9

Rogers, \V. B., and Rogers, R. E., on action 

of carbonic acid solution on minerals............................ 51

Riimpler, A., on reactions between silicates

and alkalies..................... 29

S. 

Salt solutions, acidity of, after filtration,

cause of......................... 8-9

action of silicates on, nature of......... 27

efficiency of, in decomposition of silicates ............................ 6

Sea, saltness of, chemical causes of......... 22-23

Sea water, experiments with............... 26

Shale, experiments with.................... 58

Silica, amorphous, experiments with....... 32

hydrous, behavior of, toward solutions.. .......................... 24-25

water of................................ 24

Silicates, action of, on solutions of salts, nature of............ : ............. 27

colloid, absorption of salts by.......... 25

precipitative action of, compared with

that of carbonates.............. 62
INDEX. 69

Page. 

Silicates, reactions between salt solutions

and, character and extent of.... 6,11

Silver sulphate, experiments with.'...... 41,44,59

Skey, W., on absorption of iron from ferric 

acetate solution by quartz 

powder ......................... 20

Smith, Angus, on effect of sand as a filter for

organic compounds............. 12

Soda, absorption of, by soils, experiments

showing........................ 18

Sodium alumino-silicates, action of calcium

chloride on.................... 33-34

preparation of.......................... 11

Sodium bicarbonate, changes in concentration of solutions of, caused by 

nitration........................ 8

Sodium carbonate, changes in concentrations of solutions of, caused by 

nitration........................ 8

experiments with....................... 13

increase of absorptive power by digestion with....................... 29

precipitates caused by.................. 61

Sodium chloride, action of, on granite...... 26

experiments with............... 8,12,13,22,50

filtration of, effect of................... 8

presence of, in sea water, chemical causes

of............................... 22-23

Sodium"phosphate, absorption of sodium

from solution of, by soil........ 31

Sodium salts, reactions of, with soils and

minerals........................ 13-14

Sodium silicates, stability of, as compared

with potassium silicates........ 22

Soil, composition of, used in Kullenberg's

experiments .................... 17

Solid solution reference to discussion of... 36

(footnote) 

Spring, W., on separation of acid and base

by diffusion..................... 9

Stannic acid, action of, on salt.solutions ... 28 

Steiger, George, and Clarke, F. W., experiments by, showing substitution 

of bases......................... 21

Stohmann and Henneberg, experiments of.. 13-14 

' on absorption of free alkali............. 28-29

Strontium .chloride, experiments with...... 41,48

Sugar making, extraction of potassium by a

silicate in process of............ 29

Sulphate, determination of, in cupric sulphate solution.................. 52

in ferric sulphate solution.............. 47

in sulphuric acid solution............... 50

Page 

Sulphate ion, nonabsorption of, by soil..... 15,16

Sulphuric acid, experiments with........ 35,43,50

Surface of mineral exposed to action of salt 

solutions, influence of amount 

of.................'.............. 39-40

T. 

Talc, experiment with....................;. 57

Tassin, Wirt, acknowledgments to......... 64

Temperature of solutions, effect of...... 21,42-43

Thugutt, S., experiments by............... 23

Time of contact, relation of extent of absorption to..................... 11,14

Thompson, H. S., experiment made by..... 10

Tourmaline, experiment with.............. 56

V.

Van Bemmelen, J. M. See Bemmelen, J. M.

van. 

Vanzetti, B. L., on separation of acid and

base by diffusion............... 10

Vesuvianite, experiments with.............. 55,63

W.

Warington, Robert, experiments by, showing absorption by oxides of iron 

and aluminum.................. 19,20

on precipitation of acid radical by ferric

and aluminum oxides........... 30

Way, J. T-., experiments made by.......... 10

on effect of sand and clay as a filter for

organic compounds............. 12

on precipitation of acid ion............. 30

on reaction between alkali and silicates. 28 

on reactions between salt solutions and

silicates........................ 11,12

on removal of acids of salt solutions by

soils............................ 30

Weber, H., and Hintz, E., on means of preventing precipitation of alkali 

with barium sulphate .......... 50

Weed, W. H., acknowledgments to......... 64

Wolfl, on relation between concentration of 

solution and amount of absorption. ....................'...-..... 35

Wollastonite, action of magnesium sulphate

on.............................. 20

Wood charcoal, absorption of potassium

chloride by..................... 15

Zeolitic silicates in soil, observation on..... 11 

Zinc'sulphate, experiments with............ 41,45