DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

N 388

THE COLLOID MATTER OF CLAY 

AND ITS MEASUREMENT

BY

HAERISON EVERETT ASHLEY

WASHINGTON

GOVERNMENT PRINTING OFFICE

1909

CONTENTS.

Preface, by A. V. Bleininger................................:..............

Introduction.............................................................. 7

Colloids in clays.......................................................... 9

Sources of the colloids................................................. 9

Hydrated silicates................................................ 9

Gelatinous silica................................................... 9

Ferric and aluminum hydroxides.................................. 10

Organic colloids................................................... 10

Artificially added colloids......................................... 12

Summary ......................-----.-------.----- --------- --- 12

Aging and drying of clays ............................................. 12

Air drying....................................................... 12

Drying under pressure............................................. 13

Weathering of fire clays........................................:.. 13

Aging of feldspathic bodies........................................ 14

Forms of colloids....................................................... 14

Sols and gels...................................................... 14

Coagulation and setting............................................ 15

Examples of set gels............................................... 15

Formation of sols.................................................. 17

Electrostatic charges in sols.................................... 17

Ionic reactions............................................... 18

Nature of gel formation............................................ 18

Stability of clay sols and gels...................................... 19

Protection colloids................................................ 20

Properties of colloids..................:.............................,......, 20

Viscosity............................................................. 20

Viscosity of clay slips.............................................. 20

Plasticity. ....................................................... 21

Action of electrolytes.............................................. 22

Exchange of bases............................................ 22

Organic colloids................................................ 24

Mellor, Green, and Baugh's experiments. ...................... 24

Laws of coagulation................................................ 27

Absorption............................................................ 27

Lack of definite relation of absorption to temperature............... 27

* Relation of absorption to plasticity.................................. 28

Distribution of absorbed water among constituents.................. 28

Volumes of clay gel in various salt solutions ........................ 29

Distribution of salts in gels......................................... 30

Adsorption........................................................... 31

Statement of theory................................................ 31

Cellular structure of gels............................................ 31

Partition between immiscible liquids................................ 32

Partition between a liquid and a gel................................ 32
4 CONTENTS.

Properties of colloids Continued. 

Adsorption Continued.

Partition between a liquid and a gel Continued. Page

Silk and picric acid........................................... 32

Gelatine and tannin............................................ 33

Hagerstown loam and gentian violet. ............................ 34

Quartz flour and gentian violet................................. 35

Klingenberg clay and barium chloride........................... 37

Silver iodide and silver nitrate.................................. 38

Silver iodide and potassium iodide............................. 39

.Tennessee ball clay and malachite green......................... 41

Summary...................................................... 41

Determination of plasticity................................................. 42

Dependence on colloids................................................ 42

 Adsorption tests of clays............................................... 43

Adsorption tests with brilliant green................................ 43

Comparison of brilliant green with malachite green.................. 45

Quality of water used.............................................. . 45

Malachite-green adsorption and physical properties of clays........... 46

Methods of testing..............................;............. 46

Results of tests............................................... 47

Malachite-green adsorption..................................... 50

Physical properties of clays ................................... 50

Plasticity............................................................ 54

As determined by malachite-green adsorption tests. ................ 54

As found in practice.............................................. 55

Miscellaneous applications of malachite-green test. .......................... 56

Efficiency of grinding................................................. 56

Fuller's earth......................................................... 57

Paris whites.......................................................... 57

Future work.............................................................. 58

Summary................................................................ 59

References................................................................' 59

Index.................................................................... 63

ILLUSTRATIONS.

Page. 

PLATE I. Apparatus for colorimetric test of adsorption..................... 46

FIGURE 1. Adsorption of tannin by gelatine................................. 34

2. Adsorption of gentian violet by Hagerstown loam. ............... 35

3. -Adsorption of gentian violet by quartz flour...................... ° 37

4/Adsorption of barium chloride by Klingenberg clay............... 39

5. Adsorption of potassium iodide by silver iodide................... 41

6. Adsorption of malachite green by Tennessee Ball and Sagger Clay

Company's Tennessee ball clay No. 3........................... 42

7. Structural formulae of malachite green and brilliant green. ........ 46

8. Adsorption of malachite green by Potters' Supply Company's

Tennessee ball clay No. 3.................................... 50

9. Surface concentration and specific air shrinkage of clay colloids as

related to deformability....................................... 52
PREFACE.

By A. V. BLEININGER.

The United States Geological Survey, in carrying out the provisions 

of the act of Congress approved May 27, 1908, which authorized "the 

continuation of the investigation of the structural materials belonging 

to and for the use of the United States, such as stone, clays; cement, 

and so forth," has established at Pittsburg, Pa., as part of its testing 

station there, a plant for the investigation of various problems bearing 

on the selection, preparation, and testing of clays and clay products

for use in the building and engineering construction work of the 

Government.

The work now being carried on at this plant falls into three groups:

(1) The testing of such clay products as common and pressed 

brick, paving brick, hollow tiles and conduits, enameled brick, fireproofing, terra cotta, fire brick, glazed tile, floor and roofing tile, porcelain electric insulators and other building ware submitted by the 

structural bureaus of the Government. This work includes the working out of technical specifications of the various materials for use in 

government construction.

(2) The development of specifications and methods of making 

tests of clays and clay products to determine the purposes for which 

they are best suited, and the application of these tests to the valuation of deposits of clay or glass-making and other structural material 

on public lands.

(3) The study incidentally of problems of manufacture, the solution of which would mean the elimination of much loss or would tend 

to the making of a more efficient product, better suited to the needs 

of the Government, such as the proper physical structure of fire brick, 

partition tile, floor tile, and terra cotta in different forms, of other 

heat-resisting materials, the drying of those difficultly drying clays 

that are found in many localities where there are no workable beds 

of better clay, and the proper heat treatment for various clay products.

The topic discussed in the following bulletin comes within the 

second of these three groups.

The most characteristic property of clays is their plasticity, on 

which depends their use in the arts. Yet this peculiar function of 

clay has been the most difficult to explain and to measure. Heretofore no criterion has been found which would enable the clay worker

5
O PREFACE.

to compare with any degree of accuracy the varying degrees of plasticity found in the clays employed in industry. In this bulletin 

Mr. Ashley has made an attempt to explain the character of the 

plastic constituents of clay in the light of recent researches in the 

field of colloids, and also to offer a method for the comparison of the 

different clays with respect to this property. He is dealing, therefore, 

with "a subject which is of fundamental importance not only to the 

scientific investigator but also to the manufacturer, for the success 

of the practical operations of shaping and drying hinges largely on 

the character and amount of the plastic matter present in clays.

These studies by Mr. Ashley were for the most part incidental to 

his investigation of clay products, but the defects in clay products 

purchased for the use of the Government should be much improved 

by the placing of such information as this paper contains in the hands 

of the manufacturers.
THE COLLOID MATTER OF CLAY AND ITS MEASUREMENT.

By HARRISON EVERETT ASHLEY.

INTRODUCTION.

Scope of paper. In this paper a definition of clay is given which is 

in accordance with the colloid theory and is sufficiently broad to 

include all substances worked as clays. The colloid theory is then 

applied to a description of the properties of clays. The result represents several months' searching of scientific literature, in the course 

of which the endeavor has been made to use so far as possible only 

studies on clays, avoiding studies on other colloids, such as gelatine, 

albumens, metallic sulphide suspensions, and metal suspensions.

 Special attention is given to adsorption, that property, so well 

developed in colloids, of taking other substances out of solution or 

suspension. It is finally shown that the adsorption of certain dyes 

by clays furnishes a means of estimating the colloidal matter present, 

and that when classified according to colloidal content the clays are 

also classified approximately according to plasticity. Some of the 

results of this latter investigation, undertaken while the writer was 

in the employ of the Homer Laughlin China Company, Newell, 

W. Va., are included herein by permission of the company, with 

further studies along similar lines now being continued in the clayproducts laboratories of the United States Geological Survey. The 

present is a preliminary report.

Definitions. Solids were formerly defined as crystalline and amorphous. The term " colloid" now comprises everything formerly 

known as amorphous. In this classification organic structures are 

considered as representing the highest type of crystallization. Clays 

usually present the amorphous or colloidal appearance, any crystalline, 

matter present being largely masked by a coating of colloid matter.

Clays may be defined as mixtures of minerals of which the representative members are silicates of aluminum, iron, the alkalies, and the 

alkaline earths. The hydrated aluminum silicate, kaolin (Al2 03 .2Si02 . 

2H2 0), is the most characteristic of these. Some feldspar is usually present. The grains of .these minerals may show crystal faces 

(especially in the case of kaolins), but more commonly they are of

7
8 COLLOID MATTER OF CLAY.

irregular shapes.- Upon most of these grains is an enveloping colloid 

coating. This is mainly of silicate constitution, but may consist 

partly of organic colloids, of iron, manganese, and aluminum hydroxides, and of hydrated silicic acid. Quartz grains, which are generally 

present, and mica, which is frequently present, do not have the colloid 

coating or have it in much less degree. Almost any mineral may be 

present in clays and modify the properties somewhat. The combination of granular materials and colloids is in such proportion that, 

when reduced to sufficiently fine size (by crushing, sifting, washing, 

or other means) and properly moistened with an appropriate amount 

of water, plasticity is developed. If the colloid matter is in excess 

the clay is considered very plastic, fat, or sticky, but if the granular matter is in excess it is called sandy, weak, or nonplastic..

Isolation of colloid matter ~by ScJiloesing. In 1874 Th. Schloesing 

(1 a) made a careful examination of a number of clays, removing carbonates by weak hydrochloric acid, washing, and then examining the 

separated portions which settled with different velocities in slightly 

ammoniacal distilled water. Kaolin was allowed to stand 24 hours 

before decanting. The settled matters were fractioned, also the 24- 

hour suspension (second levigation).

The following table shows the results with 40 grams of kaolin from 

M. Demondesir (Manche):

Fractionation of kaolin.

Water (H2O). ........

Alumina (AhOs) .....

Magnesia (MgO) .....

First levigation.

Sand-free 

portions: A, 

31 grams.

13.73 

46.28 

39.92

.09 

.28

Second levigation.

(a) 

1 day 

4.35 

grams.

13.93 

46.55 

40.05

.04 

.04

(6) 

Iday 

2.49 

grams.

13.92 

46.20 

39.85

.22 

.06

(c) 

5 days 

0.72 

grams.

14.28 

Lost.

(A) 

27 days 

0.30 

grams.

12.70 

48.57 

30.46

1.36 

1.03

T (e) In suspension 

0.59 

grams.

10.30 

49.57 

32.32 

1.98

1.29 

. 4.25

AlsO3.2SiO2.2H2O

13.91 

40.63 

39.46

Most of the fracl ons thus approximated the composition now 

ascribed to kaolin, Al2 03 .2Si02 .2H2 0. Owing to the unsatisfactory 

state of analytical chemistry 35 years ago, too implicit reliance can 

not be put on" the figures of column e. On precipitating the 0.59 

grams of material therein it occupied, after standing 24 hours, a volume of 146 cubic centimeters; this is five times as bulky as the precipitates of iron and alumina obtained in chemical analysis. This 

matter (e) was filtered, washed, put into a porcelain dish, and dried 

over calcium chloride. It became a broken film, horny, slightly transo Numbers refer to "References," pp. 59-62.
SOUECES OF THE COLLOIDS.. 9

lucent, adhering strongly to the porcelain. There was no cohesion 

in A, very little in a, I, c, or d; a great amount in e. There was no 

gradual change, but an abrupt difference in properties between d 

and e. Schloesing concluded, "From these characteristics I consider 

that the clay e is colloidal."

COLLOIDS IN CLAYS.

SOURCES OF THE COLLOIDS.

HYDRATED SILICATES.

Many investigators, observing the adsorptive power of soils, have 

sought to find out to which of its constituents this quality is due. 

According to Wiley (12), Way 

passed a solution of ammonia through tubes containing pure sand, and found that 

it came through apparently unaltered from the first, while a soil treated in the same 

way removed the ammonia for a considerable time. He concluded from this that 

the adsorptive power does not exist in the sand. He next oxidized the organic matter in a soil with nitric acid and then treated it with ammonia in the same way. 

The first portions of the filtrate showed no ammonia in any form; hence he concluded 

that organic matter is not essential to the act of absorption [adsorption]. He further 

showed that clay alone is capable of causing absorption [adsorption] phenomena. 

* * * He next tried to trace out the particular compound which caused the 

absorption [adsorption]. Having tried various natural silicates, he at last succeeded in producing a hydrated silicate of aluminum and soda which exhibited 

displacement and absorptive [adsorptive] properties very similar to those shown by 

the soil (46.1 Si02 , 26.1 A1203 ,15.8 Na^O, 12.0 H2 0). * * * Eichhorn [13] thought 

of trying natural hydrated silicates or zeolites, and found that they exhibited the 

same power as Way's artificial preparation.

Cushman (11) says in regard to Way (14):

The more clayey the soil, the more water it seemed capable of absorbing. But 

this was not all; besides water, this clay substance exhibited a greater facility for 

absorbing [adsorbing] the bases contained in certain salts which were dissolved in 

the water. Also this action was shown to be selective, certain bases and substances 

being held so that they could not be washed out again. Let us hear what Way himself 

had to say on the subject: "Coloring matters are actually precipitated unchanged 

or in the state of insoluble pigments [technically known as lakes] by mere mixture 

with white clay. Neither to the action of capillarity or to that of oxidation are we 

i;o attribute the property of soils to retain the mineral bases and animal and vegetable 

ingredients of manure." Way found, moreover, that exposure to a high heat destroyed 

this peculiar absorptive [adsorptive] power of the clay substance.

GELATINOUS SILICA.

Later investigators failed to confirm Way in thinking that silica, 

organic matter, etc., take no part in adsorbing salts, dyes, etc. He 

himself (15) found gelatinous silica in very considerable proportion 

(40 per cent) in a "chalk" used for agricultural purposes. Van 

Bemmelen (2) found that a silica gel of the formula Si02 . 4H2O retains 

aluminum chloride (A1C13 ) so tenaciously that repeated washings
10 COLLOID MATTER OF CLAY.

with water fail to show even traces in the wash water, yet that a solution of potassium chloride (KC1) promptly displaces considerable 

amounts, being itself adsorbed. Van Bemmelen considered the adsorptive powers of silicates in soils as for the most part to be regarded 

as such substitutions. He says (16):

Soils contain colloids colloidal silicates, ferric oxide, silicic acid, humus substances all of which can show the above effects. The absorption [adsorption] effects 

obtained on treating soils with solutions are principally to be attributed to the colloidal silicates. . .

Cameron and Bell (19) say:

Evidence is wanting for the existence of * * * silica coatings on the minerals 

of the soil. It is possible that such a coating of silica may take place to some extent.

* * * Microscopic examinations fail to disclose it, such coatings as exist being 

mainly of ferruginous materials, generally removable quite easily by mechanical 

means and permeable to water. * * * The main argument against the formation 

of siliceous coatings on the minerals is, however, the fact that they are continuously 

soluble when treated with fresh amounts of water, or when the hydrolized products 

are removed from the solution.

From a study of the evidence collected in Clarke's data of geochemistry (44) it appears that gelatinous silica is most likely to appear in 

the products of recent rock decay, and least likely in old soils.

FERRIC AND ALUMINUM HYDROXIDES!

Colloidal ferric oxide is more likely to be found in the red-burning 

clays than in the lighter-burning ones. In 1868 Warington (17) 

found that hydrated ferric oxide, which is commonly present in soils 

and clays poor in color, and hydrated aluminum oxide, which is less 

frequently present,0 are capable of absorbing (adsorbing) potash and 

ammonia, and that the absorptive (adsorptive) power of the ferric 

hydrate is two or three times that of aluminum hydrate. He further 

says that humus, and especially hydrated silicates, have also been 

shown to possess absorptive (adsorptive) powers.

ORGANIC COLLOIDS.

Peats are soils which consist almost entirely of organic matter, and 

thus exhibit separately the characteristics that are to be attributed 

to the organic matter in common clays and soils. Schreiner and Reed 

(6) state that "the amounts of organic matter in ordinary soils is

* * * 2.06 per cent for the soil and 0.83 per cent for the subsoil." 

Such matters are called "humus" or "humic acid" when they may 

be extracted by 5 per cent ammonia after previous treatment with 

1 per cent hydrochloric acid (7). Any humus in the kaolin examined 

by Schloesing would accordingly have been found in his colloidal 

residue e.

a Cameron and Bell (18) outof several thousand examinations have but once observed aluminum hydrate 

A1(OH)3 in a'soil. The sample was from southern California.
SOTJKCES OF THE COLLOIDS. 11

A. A. Julien (84) describes humic acid and many similar substances, 

in part, as follows: "Humic acid possesses a strictly colloid nature/' 

It reddens litmus paper. . It dissolves in 8,337 parts of water at 6°, 

though insoluble in water free of nitrogen or air. After drying at 120° 

it dissolves in 13,784 parts of water at 15°. After perfect drying at 

high temperatures it becomes insoluble. "It has also the colloidal 

property of glueing together vegetable earths, such as the siliceous 

sands of the Landes near Bordeaux, into a layer impervious to water." 

Ammonium humate, C60H48 (NH4 ) 6027 , dissolves in 22 parts of water. 

Calcium humate dissolves in 3,125 parts of water; magnesium humate, 

pretty easily; ferric, humate, in 5,000 parts of water at 19°. Humic 

acids are unstable, and therefore tend to disappear from old deposits, 

though traces are found in some minerals. The humic acids are solvents for silica. The humic acids have decomposed the upper layers 

of the "Champlain" clays of New York and the New Jersey Cretaceous clays, white fire clays, and pipe clays of the "Coal Measures." The action consisted mainly in the removal of calcium and 

iron, which were redeposited to form a hardpan at the lower limit of 

the action. This hardpan may consist of a layer of limonite. Hardpan may often be found as a thin impervious layer in sands where 

clays are practically absent. Gibbsite, the aluminum hydrate, is 

occasionally associated as attached crusts with limonite, and is 

therefore of the same origin. Amorphous silica may occur as (a) 

animal skeletons, (Z>) deposits from thermal waters, (c) a gelatinous 

deposit formed directly by the decomposition of rocks by organic 

acids, '(d) a deposit from solution in organic acids.

Flint, hornstone, and amorphous chert, therefore, seem to me to present the colloid 

form of silica necessarily deposited from a solvent of a colloid nature, such as humic 

acid and probably the azohumic acids have been found to possess. Granular ch'ert, 

jasper, etc., * * * appear to be the crystalline forms of silica, probably in part 

deposited from solution in thermal waters.

H. Borntrager (85) finds in peat:

Analyses of peat.

' 

Water. .........................................................................

Ash .............................................................................

Humus acids. ..................................................................

1.

29.50

3.05

54.95

12.50

100.0

2.

20.0

3.0

47.0

30.0

100.0

Charles A. Davis (5) states that:

Some types of peat, notably the brown ones, are said to become nearly impervious 

to water after they are once thoroughly dried out, because the organic acids which they 

contain are colloidal or gluelike in form, and when they dry they become insoluble. 

* * * With fineness of texture goes greater plasticity. * * * The plastic black 

peats are higher in ash, are more difficult to burn, and are harder when dry, reaching 

nearly the consistency of soft coal.
12 COLLOID MATTER OF CLAY.

ARTIFICIALLY ADDED COLLOIDS.

Considering alluvial clays, E. Q. Acheson (8) made a few experiments with those substances he thought likely to be found m the 

washings of vegetation. Addition of gallotannic acid or catechu was 

found by him to give kaolin many of the properties of the best highly 

colloidal ball clays. An excessive amount of water was not required 

to temper it; plasticity, tensile strength, and hardness were increased. 

In the discussion of his paper it was brought out that W. D. Gates had 

obtained similar results by the use of silicate of soda, and (according 

to Charles Weelans) that gums, glues, and gelatine have long been 

used in the pottery industry for obtaining such results. All of these 

materials are typical colloids.

SUMMARY.

The colloid matters in clay are therefore noncrystalline, hydrated, 

gelatinous, aluminum silicates, organic colloids, gelatinous silicic acid, 

and hydrated ferric oxide. Rarely there may also be present aluminum hydrate.

AGING AND DRYING OF CLAYS. 

AIR DRYING.

Grout (9) found 0.08 per cent agar-agar (a colloid obtained from 

seaweed and resembling gelatine closely) to increase plasticity from 

36 to 57 per cent with two different clays; that 0.2 per cent agar-agar 

causes a further but not proportionate increase; that gelatine has 

only one-tenth the effect of agar-agar; that 3 per cent of freshly precipitated alumina is required to give the same effect as 0.08 per cent 

agar-agar. But on air drying and then reworking in each case the 

plasticity was found to have dropped to its original figure. He 

found that air-dried silicic acid cuts down plasticity as much as 

angular quartz sand. He prepared an artificial hydrated silicate of 

alumina by mixing sodium silicate and alum solutions, and found that 

after drying it failed to soften in water. Therefore, to him, it seemed 

that none of these or other colloids could be responsible for the behavior of natural clays; for he apparently thought that clay can be 

dried and wetted repeatedly without affecting its plasticity injuriously, without affecting the activity of the colloids.

In this supposition he was not in accord with practical experience. 

The clay used by potters has in most cases never been deprived 

of its natural moisture. After once being dried out at as low a temperature as 60°, it is found to have lost noticeably in plasticity. In 

consequence many potteries make a practice of using their dry scrap 

for the preparation of casting slip, which requires a less plastic mixture than their other processes.

In soaking or blunging their clays potters know that the tougher 

the clay the more difficult it is to blunge it to make it take
AGING AND DRYING OF CLAYS. 13

up water and become uniformly suspended in the water. Paul Robland (40) compared caoutchouc to the completely impervious, 

imdried, highly plastic clays; which do not take up or allow to diffuse 

the slightest amounts of water, which are "completely impenetrable 

to water." One of these, the black Striegau clay, when moderately 

dried, would allow solutions of crystalloids, such as potassium 

dichromate, copper sulphate, sodium chlorides, barium chlorides, etc., 

to diffuse through it. It thus acted when it had been dried as a semipermeable colloid membrane.

Another reason for Mr. Grout's failure to duplicate the action of 

natural colloids is probably to be found in the fact that colloid and 

ultimate fine-granular matters are much more intimately mixed in 

natural clays than they could be in the mere superficial coating of 

large lumpy flocules in Mr. Grout's experiments. With experiments 

of longer duration Mr. Grout would probably have observed the

return of plasticity to his treated clay, unless other circumstances 

intervened. He would have accelerated that return had he ground 

Ins material in water in a ball mill for a sufficient period.

DRYING UNDER PRESSURE.

According to W. B. Hardy (10) the gel, or solid form, of either 

agar-agar or gelatine, when subjected to pressure, loses water and 

becomes more concentrated. The resulting solid still retains the 

old structure, which is not destroyed by drying, and the system tends 

to reform itself on the old lines by refilling the original capillary 

spaces. In this resumption it shows considerable hysteresis, or lag. 

The structure of colloids .has been shown by the microscopic work of 

Butschli and of Nagelli to be cellular or spongelike. Hardy's experiment is much like squeezing water out of a sponge. After the sponge 

has been dried, it will not immediately take up the water again, but 

requires time to soak it up through its capillary passages, like oil in a 

wick. Cushman (38) has recorded that:

Silicic acid which has been air-dried can have water pressed out of it by subjecting 

it to very high pressures; the same phenomenon is known in the case of clays in the 

manufacture of hydraulic pressed brick.

WEATHERING OF FIRE CLAYS.

Fire clays in their natural beds have been consolidated under great 

pressure and their water content reduced to but little over that 

chemically combined. Most emphatically the colloids of fire clay do 

not take up water promptly. On standing months or years with 

water they will soak it up. On grinding in a wet pan, an operation 

that may be compared with kneading and squeezing a dry sponge, 

they will take up water into their coarser pores. In its natural bed, 

fire clay exists at a very uniform temperature, but when it comes to 

the surface, either in a natural outcrop or in the clayworker's "pile"
14 COLLOID MATTER OF CLAY.

.of weathering clay, it is subjected to alternations of heat and cold, 

consequently its minute pores expand and contract. If the pile is 

kept moistened the water will penetrate as the pores expand, and as 

the pores contract a portion will be forced farther in. In some plants 

it is considered necessary to steam the clay, as diffusion of water is 

more rapid at high temperatures. In glass-pot factories it is considered necessary to age or store the damp body for a year, in order 

to let the water have time to penetrate the clay uniformly. The 

finished pots are then allowed months or years to get thoroughly dry. 

Evidently plasticity is not the creature of a few hours' laboratory 

work.

AGING. OF FELDSPATHIC BODIES.

Cushman (37) considers Grout's reasoning invalid, "as both 

plasticity and binding power can be shown to be due to a softening 

or decomposing action of water on the surface of the fine particles, 

which is invariably increased by the action of wet grinding, pugging, 

and puddling." He points out that " colloids are formed much more 

slowly in nature under temperature and pressure conditions we can 

not imitate."

The "decomposing action of water on the surface of fine particles," 

mentioned by Cushrnan, is not of importance in the case of highly 

compressed clays low in feldspathic materials, such as fire clays. 

But with a body containing ground, feldspar the aging must continue 

until, first, the decomposition of feldspar by water into colloidal 

silicates, colloidal silicic acid (?), and free alkali (37) has ceased or 

become greatly retarded; and until, second, this free alkali has been 

neutralized either by acids originally present in the clay or more likely 

by the products of bacterial activity (41) in the aging clay. Rohland (43) has advanced what is practically this idea, but he applies

it to a too wide range of clays. He refers the matter wholly to the 

quantity of OH ions present,, plasticity varying somewhat inversely 

with the quantity of these, and says that as rise of temperature 

increases the quantity of OH ions it decreases plasticity. In opposition to this view it may be noted that the old pottery slip kiln gave 

much more plastic bodies than does the modern cold-working filter 

press, and that the steaming of fire clays decidedly increases their 

plasticity.

FORMS OF COLLOIDS. 

SOLS AND GELS.

Colloids exist in two characteristic forms: (1) as a homogeneous 

suspension in a liquid, called a "sol;" and (2) as a continuous jelly 

with pore walls (and pores) filled with a liquid, called a "gel." Solids 

are included under (2) as a limiting case. The sol or gel is named by 

a prefix according to the liquid with which it is associated, as hydrosol,
FORMS OF COLLOIDS. ' 15

alcosol, hydrogel, etc. This nomenclature was proposed by Graham 

(86) in 1861, and, as it has been adopted by practically all writers on 

colloids, should be used in preference to Cushman's terms "pectoid" 

(for gel) and "colloid" (for sol).

COAGULATION AND SETTING.

Colloids are commonly spoken of as reversible and irreversible, 

according to whether they will pass from sol to gel and back to sol, 

or whether, having passed into the gel form, they can not be reconverted to the sol.

The process of passing from sol to gel is best called " coagulation," 

though sometimes "pectinization" is used; that of passing from gel 

to sol is called peptinization. When granular matter also is present, the terms flocculation and deflocculation are preferable.

Weber (20) speaks of "pectisation" as an irreversible process that

may perpetuate "any physical state (sol or gel) of a colloid." As 

this word so closely resembles "pectinize," he has not been followed 

in its use. A more serviceable phrase for the same idea is "setting," 

proposed by Hardy (10). Some colloidal solutions (sols) set spontaneously on standing, some by boiling, a large number of the inorganic colloids by freezing, the majority of inorganic colloids on adding to their solutions minute quantities of electrolytes. If resoluble, 

sols do not "set" but merely "coagulate" without setting.

Sols when set form amorphous precipitates which are exactly alike, whatever the concentration of the sol acted upon. In setting, a 

chemical change is usually produced in the molecule. Therefore, 

more than a physical change of conditions is required to reverse it.

EXAMPLES OF SET GELS.

As examples of set gels, may be mentioned fired clay, wares; gelatine treated with alum or formaldehyde, as in the Leuchter process 

of reducing or enlarging'models (22).

India rubber. According to Weber, india rubber (polyprene, of 

empirical formula C10H16) is a gel practically freed of solvent 

(therefore a solid); while ebonite (polyprene disulphide, C10H16S2 ) 

is the set modification of the same gel produced by the action of 

sulphur in vulcanization. In ebonite, polyprene disulphide and the 

excess of sulphur (15 to 70 per cent) form a new system, probably a 

solid solution. (This discussion does not include the case of solid 

solutions.) As a chemical process, time, temperature, and mass 

alone affect the composition of the vulcanization product (set gel); 

but the physical properties largely depend on the physical state of 

the india-rubber colloid (gel) employed. Ordinary rubber goods 

consist of a mixture of ebonite and india-rubber. Therefore they are 

entirely coagulated and partly set.
16 COLLOID MATTER OF CLAY.

Charcoal. Charcoal is another example of set gels. It results 

from a very complete decomposition of organic gels by heat, and its 

structure depends on theirs. Liquids are probably not absorbed into 

the substance of its pore walls, but dissolved substances (solutes) or 

suspended substances (sols) are readily attached to the surfaces of its 

pore walls (adsorption). All of the external and internal surfaces 

are wetted by the liquid.

Silica. Van Bemmelen (21) showed that the silica hydrogel when 

concentrated by evaporation undergoes an irreversible inversion 

when the water content is from 3 to 1.5 molecules H2 0 to 1 molecule 

Si02 and the vapor pressure between 10 and 4.5 millimeters. The 

position of this point depends on the mode of preparation, the age 

of the gel, the velocity of the dehydration, etc. The gel at this point 

becomes dull, opalescent, and fluorescent, then white like porcelain, 

and finally opaque white, like chalk without any gloss. After the 

inversion, dehydration takes place more rapidly than before, and the 

dimness disappears just as it has appeared, remaining bright until 

the final dehydration. As this modified gel can not resume the condition of the original gel, it might seem to be set. But as it fails to 

perpetuate the physical state of the original gel, and has all the ordinary properties of a gel, we must consider it a gel. Therefore, the 

original silica gel might be called the a gel, and the modified or intermediate gel, the ft gel.

In chemical analysis silica is separated from solution by forming 

the set gel by dehydration at 100° + . The failure of the ft gel to go 

over completely to the set gel is a frequent cause of inaccuracy. 

Hillebrand (23) has shown that while the bulk of the silica is removed 

from solution by evaporating the hydrochloric acid solution to 

approximate dryness, taking up in hydrochloric acid, and filtering, 

yet about 1 per cent more is recovered on repeating the operation. 

''Blasting for 20 to 30 minutes is necessary to expel all moisture 

from the silica, and it is then not hygroscopic."

A few analysts, in rapid processes, separate silica from solution in 

a form which is probably the ft gel. The process is as follows: One 

gram of blast-furnace slag is put into a Royal Meissen dish, 25 cubic 

centimeters of 1:1 hydrochloric acid is added, and the whole is covered 

with a watch glass and boiled violently till all the free liquid appears 

to be gone, but nothing is dry. Next 10 cubic centimeters of 1:1 

acid is added, the mixture boiled for 1 minute, and 25 cubic centimeters of hot water added. It is again boiled and can then be 

filtered very rapidly. The process is far from accurate, and it is 

questionable if its employment is ever justifiable. A peculiarity of 

the process is that Royal Berlin ware can not be used, as the silica 

sticks badly to it, a difficulty not found with Royal Meissen ware.
FORMS OF COLLOIDS. 17

The practicability of this process is related possibly to the fact noted 

by Hillebrand, that "The presence of much calcium chloride seems 

to facilitate dehydration of the silica."

FORMATION OF SOLS.

According to Whitney (27), "Whenever any substance which is by 

nature insoluble in a liquid is produced in a fine state of division in 

that liquid, it will remain in colloidal state (sol) until coagulated or 

precipitated by external means." Thus "Bredig [28] has shown that 

a great many metals may be produced in the hydrosol state by simply 

forming an electric arc under water between terminals of the metal 

desired. The heat of the arc volatilizes the metal, and the vapors 

condense in the water, yielding deeply colored suspensions or colloidal solutions." Many aniline dyes do not truly dissolve in water, 

but enter into colloidal suspension. In the cases of some dyes it is 

difficult to determine whether the properties are those of a large 

molecule of a crystalloid or of a small colloid particle. It is sometimes 

one or the other according to the concentration of the liquid. There is 

probably no dividing line (32, 34). Sols may also be produced by 

chemical reaction within the liquid; for example, by the action of 

hydrogen sulphide on arsenious oxide.

ELECTROSTATIC CHARGES IN SOLS.

From a review by Whitney. and Ober (24), the following paragraphs are taken:

A clearer idea of the value of what follows will be gained if one recognizes at this 

point the probable necessity of attributing electrostatic charges to particles of any 

kind when suspended in a liquid, and of assuming that these charges, while they may 

be positive or negative for different kinds of suspended matter, must still be of the same 

sign for all particles of the same substance. It is known that two different substances 

in contact assume equal and opposite electrostatic charges at their contact surfaces, 

and the work of Quincke, Coehn, and others have brought to light the regularities of 

this phenomenon.

Suspended particles of finely divided sulphur, silica [probably also nongelatinous 

clay], etc., in water exhibit negative charges exactly as larger masses of the same 

substance in contact with water do, and when the suspension is placed between two 

electrodes connected with a source of electromotive force, the particles all migrate in 

the direction of the negative current. Conversely, too, water in capillary tubes made 

of such materials as charge themselves negatively in contact with it moves with the 

positive electricity through the capillary under the influence of the electric current. 

Similarly, particles suspended in turpentine assume in most cases the opposite charge 

as compared with the water, and under influence of the electric current move in the 

opposite direction.

Coehn [25] was led to conclude that a substance having a Jiigher dielectric constant 

than the liquid in which it is suspended assumes the positive charge, while if of lower 

dielectric constant its charge is negative. It is probable that this does not alone determine the nature of the charge, which, at least in many cases, must depend also on ' 

83865 Bull. 388 09 2
18 COLLOID MATTER OF CLAY.

electrolytic solution-pressure and the partition coefficient for the ions of dissolved 

electrolyte between the suspended material and the liquid [26].

We seemed forced then to recognize electrostatic charges on suspended particles, and 

it seems just as necessary to accept the conclusion that, as a result of these charges, suspended particles whose masses are small enough are equally distributed throughout 

the liquid and prevented from ever coalescing or settling because of the mutual repulsion of these charges. This mutual repulsion might also cause measurable osmose and 

corresponding osmotic pressure, properties which colloids have to a small degree.

IONIC REACTIONS.

According to Mayer, Schaeffer, and Terroine (29) ; in all of a series 

of tests the addition of traces of alkali to an ultramicroscopic suspension had the effect of increasing the size of the colloidal granules 

if the suspension was positive and of diminishing them if the suspension was negative; and the addition of acids produced the inverse 

effect.

According to Whitney and Ober, "Spring [30] believes the statical 

charge, which it is assumed the ions of electrolytes carry, neutralizes 

the statical charges of opposite sign on colloidal particles. * * * 

For example, he states that certain colloids are negative and therefore 

require for their immediate precipitation or coagulation a certain 

concentration of a positive ion." Picton and Linder (42) see in such 

precipitations " a remarkable mimicry of ionic dissociation." Others 

consider it true ionic dissociation.

A. Lottermoser (31) considers that 

' The hydrosol condition is only possible if one of the reacting ions (I/+Ag/, Fex//+ 

30H', Si03//+2H/) remains up to a certain minimum amount in excess; that on exceeding this limit the gel formation begins; and that with the completed reaction, therefore 

(if equivalent amounts of the reacting ions are brought together), the gel formation 

becomes complete. * * * The hydrosol condition is bound up with the presence 

of certain ions in the colloid, which are added naturally to the colloid as electrolyte 

or remain in the same.

Dialysis decreases stability and leads to precipitation. Increase of 

the same electrolyte increases stability up to a maximum, then lets 

it fall to zero.

NATURE OF GEL FORMATION.

Some of the simpler colloids, such as those of the nobler metals, 

probably do not form gels at all; their decomposition is always the 

irreversible one to set gels. Substances that form gels have a tendency 

to form crystals, and especially complex forms, under favorable conditions. With the reaction of gel formation, sufficient freedom or 

directive force is apparently not given the particles to orient themselves into crystal ranks. The precipitation seems to take place when 

the particles get within a certain maximum range of'each other. 

This probably gives a certain regularity of structure winch microscopic workers describe as cellular and an. immense area of surface.
FOEMS OF COLLOIDS. 19

The precipitating ion, when the cause is the action of an electrolyte, 

a,lso tends by its presence to break up the symmetry of arrangement 

required for crystals. In the precipitate, positive and negative 

valencies 'satisfy each other where near enough, but possibly' many 

unsatisfied valencies are present. Some who are not ready to accept 

the conception of wholly unsatisfied valencies are yet ready to accept 

the idea of residual valencies. The more complex the chemical ions 

.and the more viscous the medium the more unlikely it is that when 

concentrated by itself or precipitated with a substance of opposite 

electrical sign the ions of a substance will ever be able to arrange 

themselves on crystal lines. Heat, giving greater mobility, tends to 

assist these complex sols to arrange themselves in such manner as to 

precipitate or coagulate; while the simpler ones, having at all times 

sufficient mobility, require merely the oppositely charged electrolyte. 

Heat may also assist by decompositions to simpler molecules and by 

the increase of static charges. This leads to the conception of permanent colloids, which, in short, are substances that never find conditions favorable for coagulation. Such probably have only small 

electrostatic charges in proportion to their mass; so that but little 

effect upon their properties results from the neutralization of that 

charge by an oppositely charged ion. The formation of gels is not 

noticeable in such cases. - -

STABILITY OF CLAY SOLS AND GELS.

J. M. Van Bemmelen (2) went into the question of the settling of 

a clay suspension. As soon as the loosely bound salts are washed 

out of a cla}^ it becomes difficult to cause it to settle, and it can not 

be filtered, but runs through the filter paper. On adding a small 

amount of acid or a salt or an alkali (in short, any electrolyte), the 

milk-white liquid coagulates and settles in a short time. It also 

can now be filtered. Washing again with water, another point is 

reached when the particles become infinitely fine and pass through 

the filter.

Aclolph Mayer (3) has determined the limiting amounts of electrolytes which will permit a fine clay (free from soluble salts by treatment with hydrochloric acid) still to be kept in suspension in water 

(100 grams clay, 500 cubic centimeters water). The limits are: Ammonia, 2.5 per cent; sulphuric, hydrochloric, and nitric acids and 

the alkali salts of these acids, 0.025 per cent.

Van Bemmelen assumes that the finely divided substance forms 

larger molecular aggregates in which the added substance takes part. 

The solution to do this must have a definite concentration, otherwise 

too many molecular aggregates are decomposed by the water and 

return to the finer molecular condition.

Although 2.5 per cent of ammonia caused precipitation in Mayer's 

experiments, a less amount favors the deflocculation, or breaking
20 COLLOID MATTER OF CLAY.

up of the lumps. Thus it is the practice in the laboratory of the 

Bureau of Soils of the Agricultural Department (4) to add 10 drops of 

strong ammonia to a 5-gram sample of clay in 75 cubic centimeters 

of distilled water in order to assist in separating the clay into its finest 

particles preliminary to mechanical analysis. With alkaline soils 

ammonia hinders the defiocculation, and should therefore be omitted 

in dealing with such.

Inorganic sols (34) are frequently coagulated by freezing or evaporating; this is often really due to the traces of electrolytes always 

present in the liquid, which become concentrated until they reach 

the minimum necessary for flocculation.

PROTECTION COLLOIDS.

When a very stable sol in the presence of a less stable sol of the 

same sign is acted upon by an electrolyte that will not precipitate 

the former, but would precipitate the latter if alone, the influence of 

the more stable sol is often sufficient to " protect" the less stable sol 

from coagulation. Noncolloidal substances can exercise protection; 

for example, ether protects noble metal hydrosols. Gelatine is a 

common "protection colloid" for many substances of small-sized 

ions. The colloids of clay may carry into suspension solid particles 

that are wholly noncolloidal by ordinary ideas.

PROPERTIES OF COLLOIDS.

VISCOSITY. 

VISCOSITY OF CLAY SLIPS.

Bleininger (49) has made an investigation of the viscosity of clay 

slips with different percentages of clay and water. The first additions of clay (up to about 3 per cent) decreased the viscosity of the 

water. This is to be attributed, as just shown, to complete deflocculation of the clay by dilution, and also to the solution of the 

electrolytes found with the clay; since, as expressed by Charles 

Henry (50), the kinetic theory of gases apprises us that the viscosity 

decreases when the diameter of the particles inceases, and the inverse. 

Bleininger therefore introduced particles larger than the water molecules into solution, and thereby decreased the viscosity. When, however, the additions had become so great that no further matter went 

into solution and the effect of the clay gel showed itself, then the 

viscosity increased with each addition of clay.

Previous to Bleininger's work a negative viscosity for clay slips had 

but rarely been observed, and, indeed, Dr. Max Simonis (51) had proposed this definition: "Clays are rocks which, pulverized and brought 

into suspension with equal or greater amounts of water, measurably
PROPEETIES OP COLLOIDS. 21

increase.the cohesion of the water. Nonplastics lack this property." 

As Simonis (52, 53) had previously noted that alkalies can cut down 

the viscosity of clay slips, it is evident that he overlooked the possibility of salts naturally occurring in clay having the same effect at 

sufficient dilution.

PLASTICITY.

Many plastic bodies consist of a more or less granular material, 

coated and held by a viscous substance. Instances are: Putty, 

which is a mixture of any white granular material (typically whiting) 

with linseed or a similar oil, the latter hardening on exposure to air; 

cake frosting, a mixture of granular sugar with the white of eggs, 

becoming hard on exposure to air; plaster of Paris, a mixture of 

gypsum crystals and an amorphous paste of uncrystallized plaster, 

hardening upon completion of the crystallization; wiping solder, a 

mixture of lead crystals in a fused eutectic mixture of lead and tin, 

hardening on cooling; mortars, mixtures of sand with lime or other 

cementing pastes, hardening on reaction with the air, or by internal 

reactions; waxes, mixtures of oils of high melting points with oils of 

lower melting points, hardening on cooling; and, finally, clays, mixtures of granular, nonplastic materials with moist organic and inorganic gels, hardening on evaporation of the water. The term 

"nonplastics" for granular materials requires qualification, since 

plastic bodies would lose plasticity if the granular constituent were 

removed and would become sticky. Plasticity depends on a proper 

ratio of granular material and viscous suspension medium.

P. Rohland (43) considers that the plasticity of clays depends on the 

amount of hydroxyl ions present in the water. When this is large, 

the negatively charged clay particles will go into colloidal suspension. 

When the hydroxyl concentration is depressed, as by additions of 

acid or depression of temperature, the clay will assume the gel condition and become plastic. For decreasing plasticity may be used 

all bases, organic and inorganic, all salts of strong bases with weak 

acids, which hydrolytically split off OH ions in large amounts. To 

this classification belong potash, soda, salts of phosphoric acid, 

salts of silicic'acid. "Neutral salts with very few exceptions appear 

to behave indifferently." As indifferent salts he mentions sodium 

chloride, sodium sulphate, potassium nitrate, magnesium chloride, 

and others. "The causes of the abnormal behavior of several are 

not yet exactly known."

This conception is attractive by virtue of its simplicity and comprehensiveness. It seeks, however, to refer the plasticity of clays to 

their vehicle, a water solution of soluble salts, rather than to their 

own composition. It seems more logical, though perhaps more
22 COLLOID MATTER OF CLAY.

difficult in details, to refer plasticity to the gel structure of the clays 

themselves. It must be allowed that the condition of the water will 

have effects of the nature assigned by Rohland; but as clay is plastic 

when wetted with, for example, aniline (paint remover), linseed oil 

(kaolin putty)', alcohol, glycerin (plastic medical dressing), etc., 

hydroxyl can by no means play the principal part. This is substantiated by the views of Coehn (25). (See p. 17.)

ACTION OF ELECTROLYTES.

Plastic clays have very little, if any, of their colloid matter in the 

hydrosol condition. They hold in their natural deposits sufficient 

bases, especially lime, to keep them as coagulated gels. Anyone 

has but to look at the clear water coming from a pottery filter press 

to realize how completely absent is the sol form of the clay colloids. 

It is not until a sol has been coagulated and thus become a gel that 

it has .any plasticity or marked adhesive and cohesive properties. 

Thus Hans Kuzel (45) has observed that the pure gels of colloid 

metals form exceptionally homogeneous plastic masses when the 

mechanically combined water is removed by appropriate expression 

or other suitable means. (He adds nonplastics.) The sols of such 

metals are fluid, therefore wholly unplastic.

It is possible that much of the colloid matter in clays has never 

been in the sol form, but is a gelatinous residue left from rock decomposition, together with crystal rock fragments (46).

According to Hardy (lOa), a sol is coagulated when its static charge 

of electricity is neutralized. This is usually done by electrolytes. 

With a negative sol, such as a clay that has been brought into colloidal 

suspension, the positive ion of the electrolyte is of most influence in 

effecting precipitation, the acid ion taking little part. The power 

seems to vary but little in different positive ions of the same valence; 

but with certain sols divalent ions have about 60 times the precipitating effect of monovalent ions, and trivalent ions 600 times that of 

monovalent ions (27, 24, 33). The effects are not so great on clays.

EXCHANGE OF BASES.

Eugene C. Sullivan (39) has carefully studied the interaction 

between minerals and water solutions. Pie concludes that "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." He does not consider pure water, acids, or 

alkalies in this generalization.

If sodium carbonate be added to a clay which has just enough 

calcium (the most common "soluble salt" in clay is calcium sulphate)
PROPERTIES OP COLLOIDS. . 23

to keep the colloid matter in gel form, it will (the calcium being but 

loosely combined) react according to the following equation:

Ca + Na2C03 -> CaC03 + Naz 

with gel the addition insoluble with the sol.

F. F.orster (87) is to be credited with first perceiving the nature of 

tliis action of sodium carbonate on the clay gel. The calcium carbonate formed being insoluble no longer has influence on the colloid. 

The sodium, in amount equal to the calcium, has metal ions of lower 

valence than the calcium which originally stabilized the gel. As 

many times more sodium atoms than calcium atoms are required to 

precipitate the same amount of gel, it is evident that the clay gel will 

be broken up, or the clay will be deflocculated by the soda, and its 

plastichYy will fall off in proportion to the completeness of the reaction. 

When, however, enough sodium ions have been added, they may be 

expected to precipitate the gel anew.

Such is the caste, as studied by Mellor, Green, and Baugh (47). 

These investigators took measurements of the time required for 200 

cubic centimeters of an earthenware body slip to run from a modification of Mariotte's bottle. Reduced to a basis a of time for water 

equals 10 seconds, their results were:

Addition of sodium carbonate (grams) ............... 0 0.1 0.2 0.3 0.4 0.5 1.0 1.5 2.5 3.5 4.5

Time required (seconds) ..... 10 .8.7 7.4 6.5 6.1 6.1 6.1 6.1 7.8 13.9 (&)

Similar results were obtained by them for potassium carbonate, 

sodium bicarbonate, sodium potassium carbonate, sodium sulphide, 

potassium hydroxide, gallic acid, ammonium gallate, and tannin. It 

can not be asserted that with each of these compounds the action is 

the same as with sodium carbonate, for the earthenware body is of 

too complex a nature, and the action must be studied on simpler 

substances for full conformation, but probably the explanation holds 

for most of these cases. The insolubility of the compound formed 

may^not be so complete as that of calcium carbonate in-every case; 

it is less so, for instance, with calcium hydroxide formed by action of 

potassium hydroxide.' According to Simonis's results, sodium hydroxide and rubidium hydroxide behave similarly to potassium hydroxide.

When the added salt does not form an insoluble product with the 

salt in the clay, there is probably part replacement in accordance 

with the mass-action law. Thus on addition of sodium sulphate 

there was a falling off in viscosity, and sufficient sodium ion concentrations were not reached to reprecipitate the gel. Such was also the 

case with sodium sulphite and sodium chloride. It is therefore classified here with hydrochloric acid. Certain salts, however, were added

a Mellor, Green, and Baugh used water at various temperatures, which took in some cases 10 seconds and 

ia others more, to flow from the viscosimeter. These results have been reduced to a common basis of 10 

seconds.

& Too stiff to flow through apparatus.
24 COLLOID MATTEE OP CLAY.

in sufficient amounts to reprecipitate the gels, viz, potassium acid 

sulphate, potassium sulphate, potassium nitrate.

It is difficult to classify the action of hydrochloric acid and mercuric sulphate. The latter decomposes to insoluble sulphate and free 

acid.

Divalent ions in some cases reinforced the salt in the cl&y, in others 

the reverse, according to slight variations in precipitating power, 

such as have been shown by Schulze (33). Magnesium sulphate 

decreased viscosity. Substances increasing viscosity were calcium 

sulphate, copper sulphate, calcium chloride, and, according to Simonis, 

calcium hydroxide.

Trivalent ions reinforced the fiocculation, even though associated 

with monovalent ions. The case studied was potassium aluminum 

sulphate (K2S04 .A12 (S04) 3 .24 H20).

ORGANIC COLLOIDS.

In some cases the action is probably not on' the inorganic gel 

of the clay, but on the organic matter. Strong ammonia increased 

the viscosity in these experiments. Ammonia is known to be a 

solvent for humic acids. It is very likely that it acted on the somewhat insoluble or set humic acids and humates, forming ammonium 

humates, which, not having sufficient water for solution, assumed 

the gelatinous form and increased the viscosity. Similar action may 

be attributed to ammonium chloride, aniline, methylamine, and ethylamine. This possible explanation needs verification, and can not be 

considered as of weight until such studies have been made. All of 

the other basic ions studied were of simple nature. The effect of the 

complexity of the NH4 group may be of influence. Smaller additions 

than those tabulated may produce deflocculation.

Alcohol additions did not affect the viscosity. As water additions 

would have decreased the viscosity, so alcohol substitutions for water 

would have increased the viscosity. The action of alcohol is therefore similar to that of ammonia, a complex group, with solvent effect 

on organic matter.

Humic acid and grape sugar, being themselves colloids, increased 

the colloid content and the viscosity. Sodium biborate is possibly 

also to be classed as increasing viscosity, or on Binn's assumption of 

the basic nature of boron (48). might be considered as having a 

trivalent basic ion.0

MELLOR, GREEN, AND BAUGH'S EXPERIMENTS.

In the table of Mellor, Green, and Baugh's results below the times 

required for equal Volumes of slips with various additions to flow 

through the same orifice are given (reduced to a common basis b of 

time for water equals 10 seconds):

« Work by the writer in 1909 shows that borax belongs in the first or second of the groups of the table. 

6 See footnote, p. 23.
Effect of various additions on the viscosity of an earthenware body slip, measured by the time in 

a Mariotte bottle viscosimeter.

1. Deflocculation resulting from, precipitation of stabilizing ion:

Gallic acid (C7H6O6 . H2O) . ...................

2. Deflocculation resulting from, mass action effect of 

ions of small flocculating power:

3. Hydrochloric acid (28 per cent) (sp. gr. 1.14)/ ....

Mercuric sulphate (decomposes to insoluble

4. Deflocculation by divalent ions of lesser flocculating

5. Reinforced flocculation by divalent ions of equal or 

greater flocculating power:

6. Reinforced flocculation by trivalent ions: Potassium aluminum sulphate (K2SO4.Ah(SO4)3. 

24H2O )........................................

0

in

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

10

0.1

8.7

9.7

8.8

8.5

6.4

' 8.3

8.0

«5.6

7.5

6.7

10.0

10.0

8.9

8:6

10.0

9.1

11.2

8.4

f (Ic.c.) 

\ 11.7

9.1

11.2

14.2

11.2

15.0

0.2

7.4

7.1

7.5

6.9

5.9

8.7-

8.3

6.0

6.0

10.0

9.7

7.8

7.6

9.7

S.5

9.6

7.8

(2 c.c.) 

10.6

S.O

9.1

10. 8

21.3

11.2

1S.S

0.3

6.5

6.3

6.3

6.9

6.7

8.9

5.7

9.4

7.7

6.9

9.5

9.1

9.6

8.1

(3 c.c.) 

9.2

10 8

35.5

11.6

20.0

0.4

 6.1

5.5

6.3

6.9

8.2

9.2

6.0

5.5

9.1

-7.6

6.9

9.2

10.0

11.6

8.4

(4 c.c.) 

8.1

9.0

11.2

24.5

11.6

21.9

0.5

6.1

5.5

11.3

9.5

6.0

5.5

7.5

9.1

7.0

6.6

9.2

12.4

12.4

9.4

(5 c.c.) 

7.5

9.1

11.2

11.6

(a)

0.6

( r r\

9.1

14.0

9.0

a Too thick to run through. 

& Addition, 0. 9 gram. 

c Addition, 0.7 gram, 

d Addition, 1.7 grains.

« Addition 0.02 gram, time 7.2 seconds; 0.04 gram, 6.1 seconds; 0.06 

gram, 5.8 seconds; 0.OS gram 5.6 seconds; 0.12 gram, 5.0 seconds.
Effect of various additions on the viscosity of an earthenware body slip, measured by the time 

a Mariotte bottle viscosimeter Contin

7. Reinforced flocculation by a complex group: a.

Methylamine (CH3Nir2 ) <=. ....................

Ethylamine (CaHjNT^) <=. ....................

Aniline (CslIsNH^X .........................

8. Reinforced flocculatiorfby colloids or by additions 

of greater viscosity:

Sodium biborate (Na2B<O7. lOHjO) . ..........

Absolute alcohol (CsHaOIT) c. ................

0

10 

10

10 

10 

10 

10

10 

10 

10

10

0.1

10.7 

10.0 

(1 c.c.) 

13.0

(1 C.C.I

(") 

(1 c.c.) 

12.6 

(0.1 c.c.) 

11.6

10.6 

10.0 

10.3 

f (1 C.c.) 

\ 10.0

0.2

( 6 ) 

11.8 

(2 c.c.) 

14.5

(2 c.c.) 

13.7 

(0.2 c.c.) 

CO

11.4 

10.3 

10.7 

(2 c.c.) 

10.0

. 0.3

16.2 

(3 c.c.) 

10.0

(3 C.c.) 

( 6 )

12.3 

10.3 

10.7 

(3 c.c.) 

10.0

0.4

16.2 

(4 c.c.) 

( 6 )

12. 6 

10.3 

10.7 

(1 c.c.) 

10.0

0.5

(»)

13.4 

10.3 

11.0 

(5 c.c.) 

10.0

0.6 

a Work performed since January 1, 1909, shows that these reagents may possibly belong 

in the second group and are used here in too great concentrations to cause deflocculation.
PROPERTIES OF COLLOIDS. 27 

LAWS OF COAGULATION.

A promising theoretical treatment of coagulation is that of Hardy 

(lOa), who says: "The concentration of acids necessary to coagulate 

electronegative colloid particles, and of alkalis necessary to coagulate 

electropositive particles, is determined by the laws which govern ordinary chemical equilibrium," that is, equicoagulate solutions of acids 

agree in their electric conductivity within the limits of experimental 

6>rror.

Specific conductivity = C = vd (u + v).

a is the fraction of the total number of molecules, v, which ?,re 

dissociated at any one moment, and u + v is the sum of the velocity 

of the two ions.

In the case of the action of salts on these hydrosols, the relation is 

riot so simple. K does not vary directly with a (u + v), but contains 

a, factor which is approximately squared or cubed by a change from 

a, monovalent to a divalent or trivalent ion. The relation can therefore be best expressed as J$L = va(u + v) A.x, where x is positive and 

increases rapidly with an increase in the valency of the ion whose 

electric charge is of the opposite sign to that on the particles.

Action is on the liquid or on the particles or on both at various 

times.

Unfortunately little experimental work has been done along the 

line indicated by Hardy.

ABSORPTION. 

LACK OF DEFINITE RELATION OF ABSORPTION TO TEMPERATURE.

It has been pointed out in the case of silica that a portion of the 

liquid medium is most tenaciously held by the gel. (See p. 16.) 

This is a universal and well-known property of colloids. In the case 

of hydrogels it may be said to correspond in a rough way to water of 

crystallization; but just as colloids have no definite form, neither do 

they retain a definite amount of water nor give it up at a definite 

temperature on heating. Cushman (38) has shown in the case of 

several hydrogels the proportion of water that they will absorb after 

being heated to increasingly high temperatures. Similar curves were 

obtained for silicic acid gel, ferric oxide gel, and two clays. The temperatures at which they lost the absorptive power completely are 840° 

and 950° for the two clays, 1,020° for the ferric oxide gel, and 1,200° 

for the silica gel. As the water regained was from over a sulphuric 

acid solution of 18 millimeters vapor pressure, it is, according to 

Cushman, not to be considered hygroscopic, but as due to absorption.

According to Van Bemmelen (54), hydrogels are not definite hydrates, as the vapor tension and hence the water content change continuously with temperature, while a true hydrate gives off a definite
28 COLLOID MATTER OF CLAY.

number of molecules of water at definite temperatures. The water 

of hydrogels may be replaced by other liquids, such as alcohol, glycerine, etc. The aqueous tension of colloids also undergoes irreversible 

Changes on drying out, heating, etc.

RELATION OF ABSOEPTION TO PLASTICITY.

The amount of water required by clays to give them a plastic consistency (which may be considered, as closely related to amount absorbed) is sometimes taken as a measure of plasticity, but Grimsley 

(9) notes that Ries in his work on the Michigan clays found examples 

where 19 per cent of water.was required for a clay of low plasticity, 

and 17 or 18 per cent for another of high plasticity.

Grout (9) found that a shale which had increased largely in plasticity on weathering checked within 0.02 per cent of the combined 

water originally present. Therefore, plasticity can not be measured 

directly either by the combined or the absorbed water.

DISTRIBUTION OF ABSORBED WATER AMONG CONSTITUENTS.

The amount of water absorbed from the atmosphere by the various 

constituents of clay is remarkable.

For quartz, Patten 'and Gallagher (55) report at 25° C. 

Absorption by quartz at 25° C.

Vapor pressure.

Millimeters.

0.09

8.00

14.00

18.30

23. 50 (water)

Moisture absorbed.

Per cent.

0.07

.10

.11 .12'

.01

For feldspars, Day and Alien (56) find that the water of constitution (about 0.60 per cent) frequently reported for feldspars is in 

most cases really hygroscopic, and is the larger in amount the finer 

the samples are ground.

Von Dobeneck (57) reports the water absorbed by humus at 20° 

C. as follows:

Absorption by humus at 20° C.

Humidity.

Per cent.

30

SO

70.

90

100

Moisture absorbed.

Per cent.

4.05

.7.76

10.58

15.67

18.02
PROPERTIES OF COLLOIDS. 29

Briggs and McLane (58) subjected soils in a centrifugal machine to 

forces 3,000 times that of the earth's gravitation. The water retained varied from 3.6 per cent with coarse sandy soils to 46.5 per 

cent in the case of a heavy clay subsoil. Each per cent of clay or 

organic matter corresponded to 0.62 per cent of moisture; each per 

cent of silt to 0.13 per cent of moisture.

Referring to the work of Schloesing (see p. 8), it will be noted 

that he found the finest constituent of a very pure clay to have a 

gelatinous nature, with a decided reluctance to giving up water.

It will be seen from these figures that the large moisture content 

of air-dried clays is not to any noticeable degree due to the granular 

kaolin feldspar and quartz, but to the organic matter and to the mineral colloidal constituent of the clay.

VOLUMES OF CLAY GEL IN VARIOUS SALT SOLUTIONS.

Schloesing has noted the great bulk assumed by the clay gel in 

water. Patten and Gallagher (55) have studied the effect of various 

salt solutions on the bulk of 50 grams of Susquehanna clay shaken up 

with 150 cubic centimeters of solution and allowed to settle for 7 

days, as given in the following table:

Effect ofl5Q cubic centimeters of various solutions on SO grams of clay.

Solute.

Flocculation:

Deflocculation:

Volume of solution in 

soil.

Y solution.

Cubic centimeters. 

60.5 

73.0

SO. 4 

91.4 

97.7 

104. 6 

108.7 

110.4 

111. 3 

118. 1 

120.9 

126.1 

126.7 

128.1

N , t. JQ solution.

Cubic centimeters. 

69.4 

89.4

o70.1 

126. 4 

a 69. 8 

105.6 

123.2 

117.7 

117.6 

125. 8 

101. 2 

113. 8 

128.7 

131.9

a- Flocculation.

The deflocculation has not proceeded far enough to result in sol 

formation in most of these cases. It is probable that sol formation 

would not be reached at any concentration with potassium nitrate, 

sodium nitrate, potassium sulphate, ammonium sulphate, sulphuric 

acid, and sodium sulphate.
30 COLLOID MATTEB OF CLAY.

The result is closely parallel to that of Mellorj Green, and Baugh 

on the viscosity of clay slips. Divalent lime, and complex ammonium ions caused a decrease in bulk and an increase of viscosit}^ 

Ammonium seems to present anomalies, for which it is possible, but 

not profitable, to frame explanations. F. Hofmeister (59) has 

shown that with the same positive ion, different negative ions givedifferent amounts of swelling with plates of glue.

It has been pointed out by Weber (20) that the water associated 

with a gel is dissolved in the gel a distinction from ordinary solutions 

with a considerable difference. Van Bernmelen (60) states that 

it is homogeneously distributed throughout the substance of the gel, 

not concentrated on the surfaces like hygroscopic water on glass.

DISTRIBUTION OF SALTS IN GELS.

The physical distribution of the salts associated with a gel is a 

subject of much interest. A small portion of one of the ions is intimately associated, probably by a sort of chemical combination, and 

is necessary for the stability of the gel state. This has already been 

discussed (p. 18). The amount required for this stability varies with 

different elements, and is greatest for the monovalent ions, least for 

those of highest valence.

A colloid of opposite sign'may perform the same function as a salt 

ion of opposite sign in coagulating a sol or stabilizing a gel. According to Teague and Buxton (36, 62), whose work does not seem to be 

published in the language of. their own country, some dyes are true 

crystalloids, soluble in water; others are true colloids, suspensions in 

water; and there are all intermediate gradations. In other words, 

there is no dividing line between crystalloids and colloids; but it is 

convenient to classify separately as colloids those substances whose 

ions are so large as to give preeminence to those phenomena that we 

call colloidal. But all dyes can be treated as in one group. Teague 

and Buxton (62), with especial reference to dyes, lay clown this rule: 

"Slightly colloidal substances (sols of opposite sign) precipitate each 

other over a wide range of concentrations, but incompletely; highly 

colloidal substances, over a narrow range of concentrations, but completely." In their earlier article (36), they say that in the case of a 

highly colloidal color and one slightly colloidal for example, congo 

red and methylene blue the slightest excess of congo red dissolves the 

precipitate, but the weakly colloidal methylene blue dissolves nothing 

unless in considerable excess. In their later article (62), they say 

that highly colloidal substances can probably take the more colloidal 

member of. a mutual colloid gel away from the weaker member. It 

thus appears that in the matter of replacements, colloid complexity 

has an effect similar to increase of valency with simple crystalloid 

ions.
PROPERTIES OF COLLOIDS. 31

Des Bancels (64) states that (1) mixtures of two colloids of opposite 

signs cause a precipitation which is complete at a definite proportion; 

but addition of an electrolyte capable of precipitating one of the 

two colloids prevents their mutual precipitation; (2-) if to mixtures 

containing a constant quantity of negative colloid A and increasing 

proportions of an electrolyte which does not precipitate this colloid 

one adds a constant quantity of colloid B, it is noticed that for weak 

quantities of electrolyte the precipitate is a mixture of A and B, for 

increasing amounts of electrolyte the precipitate consists of B alone, 

while for the strongest amounts of electrolyte the precipitate contains a mixture of A and B; (3) the precipitate resulting from the 

mixture of'two colloids of opposed signs can generally be dissociated 

by the addition of an electrolyte capable of precipitating one of the 

couple.

ADSORPTION.' 

STATEMENT OF THEORY.

After a sol has been coagulated by a certain amount of an opposite 

ion, the question is proper, What becomes of the excess of the coagulating ion or of other ions of the same sign that may subsequently 

be brought into the liquid? The replacements possible in the latter 

case have already been discussed (p. 22). As to the former case, there 

are two views: One, that the excess ions are collected on the surfaces 

of the gel, adsorbed, as is considered the case with gases held by 

charcoal; the other, that the excess ions are distributed between.the 

outside liquid and the gel, as if the gel were the second of two immiscible liquids; that is, that the ions were held in solid solution in 

the gel.

Walker and Appleyard (61) have disproved the latter theory as 

applied to dyeing, and their proof is equally applicable in other 

cases. The adsorption theory not having been disproved, probably 

is correct.

The excess of the opposite ion that has not taken part in coagulating the gel and that is not adsorbed is probably in simple solution in 

the liquid medium, whether that medium be absorbed by the gel or 

free.

CELLULAR STRUCTURE OF GELS.

For the adsorption theory it is necessary to consider that the gel 

has a surface proportional to its mass. On page 18 the circumstances that may lead to a cellular structure have been mentioned. 

W. B. Hardy (10) discusses such a state in the case of gelatine; Van 

Bemmelen (63) notes the similarity of such structures and emulsions; 

Lottermoser (65) describes a cell-like structure, which he calls an 

"emulsion colloid" but which Weber (20) has described as a gel
32 COLLOID MATTER OF CLAY.

swelled up to, near, or above the maximum solubility of water in the 

gel. Butschli and also Nagelli have described the microscopic 

appearance of the cellular structure of colloids.

The theory of a cellular structure having been accepted, its mathematical expression may be considered. Bodeker (66) in 1859 considered adsorption as proportional to the square root of the initial 

concentration. Wolff (67) in the same year pointed out that the 

final, not the initial, concentration should be considered.

PARTITION BETWEEN IMMISCIBLE LIQUIDS.

Nernst, in 1891, formulated a "partition law" for the distribution 

of a solute between two immiscible liquids. Distribution is considered dependent on the relative solution pressure in two solvents.

where Ca is the concentration in solvent a, Cb is the concentration in 

solvent &, and /? is a constant, amounting practically to the ratio of 

the solubilities in the two liquids.

If, however, the molecular weight in the solvent 6 is n times as 

great as in a, the equation takes the form

PARTITION BETWEEN A LIQUID AND A GEL.

In applying this to adsorption the most common form is

where X = the weight of the adsorbed substance, m = the weight of 

the adsorbent, Cb = the concentration of the solution, and /? and p are 

constants.

SILK AND PICRIC ACID.

For picric acid" and silk, Walker and Appleyard (61) obtained

 P=. = 35.5,

2.7 / '

AT

which is of the above form; s = concentration of dye on silk, and 

w = concentration of dye in water. 

Taking logarithms 

log s = log 35.5 + log w.

Differentiating,

ds _ 1 dw ~o~"~9 7 ~w

o ^.l 6C/
PROPERTIES OP COLLOIDS. 33

that is, if the concentration in water increases by 1 per cent of its

value, the concentration in the silk will increase by per cent of its ' . J 2.7

own value. It appears that the molecule is 2.7 times greater in 

water than in the fiber (if solid solution were to be assumed), which 

is most improbable, especially as picric acid (C0H2 (N02) 3 .OH) has 

high electrolytic dissociation in water. Therefore, according to 

Walker and Appleyard, the phenomenon can not be explained by 

solid solution; although the mathematical expression has a similar 

form, which is to be ascribed to adsorption.

GELATINE AND TANNIN.

The colloid nature and homogeneity of silk being possibly somewhat questionable, the equation to represent the results of Wood 

(68) on the adsorption of tannin by gelatine has been worked out. 

The calculations are as follows:

Adsorption of tannin by 1 gram of air-dry gelatine (=0.74 gram anhydrous}.

Volume

of solution 

(cubic, centimeters).

100

200

300

400

500

600

700

800

Tannin 

(grams).

1

2

3

4

5

6

7

8

Tannin 

adsorbed 

(grams).

0.91

1.50

1.90

2.17

2.28

2.36

2.36

2.36

A.

Tannin

adsorbed 

per gram anhydrous 

gelatine

(grams).

1.226

2.028

2.567

2.932

3.080

3.189

3.189

3.189

iLogA.

0.090

.307.

1 .410

.467

.489

.504

.504

.504

Tannin 

left in 

solution

0.09

.50

1.10

1.83

2.72

3.64

4.64

5.64

.

Tannin 

per gram 

water 

(grams).

0.0009

.0025

. 003667

.004575

.00544

. 006067

. 00663

. 00705

LogB.

4.955

3.398

3.565

3.661

3.736

3.783

3.822

3.849

The foregoing calculations were made with a slide rule.

In figure 1, logs A are plotted as ordinates and logs B as abscissas.

As the first five points lie closely on the same straight line, they 

represent data that may be expressed by an exponential equation.

Assume A B71 = K. Taking logarithms, log A + n log B = log K = K1 . 

Selecting two convenient points on the straight line of figure 1,

0.5000 +3.749 w = E>

or

0.0611 + 4.900 n = Kl

0.5000-2.251 n = K> 

0.0611 -3.100 n = Kl

_____ ' «%,.

These may be solved simultaneously for n and K1 . From K1 , K is 

obtained.

83865 Bull, 388 09 3
34 COLLOID MATTER OF CLAY.

Employing a slide rule, five-place logarithms, and seven-place 

logarithms, there are obtained, respectively:

^m =46.3, , and = 46.09810.

The five-place logarithms secure the equation with sufficient 

accuracy only to three significant figures in the constant.

§

-4-6.098

A

3.0 3.2 3.4 3.6 3.8

LOG.B

Tannin in solution

FIGURE 1. Adsorption of tannin by gelatine.

The same form of equation applies to tannin and gelatine as to 

picric acid and silk, but reaches a limit after which it fails to apply. 

That there is a superior limit to adsorption may have an important 

significance.

HAGERSTOWN LOAM AND GENTIAN VIOLET.

Cameron and Patten (69) have determined the adsorption of gentian 

violet ((CH3) 2N.C6H3 :SC1N:C6H3NH2) by Hagerstown loam. The 

dye has a solubility of 6.8 per cent at 25°.
PROPERTIES OF COLLOIDS. 35

Their results, as recalculated by the writer, are given in the following table:

Adsorption of gentian violet by Hagerstown loam.

< 

cij oo

Dye 

added per 

liter 

(grams).

1.33

2.66

3.33

6.67

10.00

13.33

20.00

26.67

A.

Dye adsorbed 

per 

gram of soil 

(grams).

0. 001 999 6

. 003 999 8

. 004 999 6

. 009 982 5

. 014 95

. 019 817

. 020 45 

. 020 25

Log. A.

3". 301

3.602

3.699

3.999

2.175

2.297

2.310

2.306

B.

Dye remaining 

in solution per 

gram of water 

(grams).

0.00000023

. 000 001 40

. 000 002 50

. 000 012 0

. 000 032 5

. 000 125 0

. 006 525

. 013 500

Log. B.

7.362

6.146

6.398

5.080

5.512

1.097

3.815

2.130

=.8375

4.0 LOG.B 3.0 T.O

FIGURE 2. Adsorption of gentian violet by Hagerstown loam.

Studying these data in the manner just described (fig. 2), it is 

found that the first six of these points are accurately represented by 

the equation

A A

TJ0.39495 = 0.83723 Or -DO-3849965 = 0.8375014,
36 COLLOID MATTEE OP CLAY.

Seven-place logarithms appear necessary to obtain a constant accurate in the fourth significant figure.

In similar manner to the preceding case, there is a superior limit 

to adsorption, beyond which the last two points lie.

QUAETZ FLOUR AND GENTIAN VIOLET.

Cameron and Patten have also studied adsorption of gentian violet 

by quartz flour. The writer has recast their results, as given in the 

following table:

Adsorption of gentian violet by quartz flour.

0.04 .............................................

Equation applies: 

.10.............................................

.5..............................................

.67........:....................................

1.33. ............................................

2.00. ............................................

2.C6. .............................................

3.33. ............................................

Equation fails: 

4.66. ............................................

6.67. ............................................

16.67. ............................................

A.

Dye adsorbed per

gram of

(grams).

0. 000 06

. 000 14

. 000 743

. 001 984

. 001 901

. 002 66

. 002 89

. 002 95

. 002 97

. 002 93

. 002 90

A'. 

A

1- A

.0035.

0. 000 061

. 000 1457

. 000 945

. 000 4572

. 004 16

.011 06

.016 6

. 018 77

. 019 54

. 018 03

. 016 86

3.786

1.164

3.975

3.660

3.619

2.045

2.220

2.274

5.291

2.256

2.227

B.

Dye unadsorbed

per liter

(grams).

Trace.

0. 0001

.0040

.0108

.066

.224

.740

1.370

2.668

4.710

147*;

Log. B.

3 nnn

3.602

"5.034

2.820

T ^f;n

T SfiQ

0.137

0 497

0.673

1.169

a Evidently erroneous.

The form of equation used in the three preceding cases failed to 

represent the data. In casting about for a more accurate numerical

A expression, the expedient was evolved of dividing A by 1 

U.UUoo*

It will be noted that 0.0035 is of the same order of magnitude as the 

maximum observed adsorption per gram, 0.00295. The latter figure, 

however, failed to work, and the value employed was the result of 

repeated trials to get a value that would give a straight line on

'___A 

the logarithmic diagram. Then if A' = A , the equation

0.0035 A'

 o 0 . 531404 = 0.01948113 represents the data accurately from the most

dilute solution up to practically the maximum of adsorption.
PROPEKTIES OF COLLOIDS. 37

In figure 3 the logarithmic curves for the equations are given for 

comparison. Thus A Bn = K (the theoretical curve, which should bo 

a straight.line if the equation is correct); A' Bn = K, where

A'= A A~ 

0.00297 

0.00297 being the maximum observed adsorption; and A' Bn =K,

A

where A' =

1- A , 0.0035 being a value found by trial.

0.0035 

The superiority of the third curve is easily seen.

FIGURE 3. Adsorption of gentian violet by quartz flour. 

KLINGEN3ERG CLAY AND BARIUM CHLORIDE.

H. Hirsch has studied the adsorption of barium chloride by various 

clays. For Klingenberg clay his results, as recalculated, are given in 

the table following.
38 COLLOID MATTER OF CLAY.

Adsorption of barium chloride by 100 grams of Klingeriberg clay in 1 liter water.

Barium 

chloride 

added 

(grams).

0.1

.2

.3

.4

. 5

.0

.7

.8

.9

1.0

1.5

2.0

2.5

3.0

4.0

5.0

10.0

15. 0 '

20.0

25.0

A. 

Barium 

chloride per 

per gram of 

clay 

(grams).

0. 000 90

.001 92

. 002 92

. 003 52

. 004 24

. 004 89

. 005 51

. 006 03

. 006 54

. 007 01

. 008 08

. 009 30

.010 09

. 010 87

.011 64

. 012 31

. 014 12

. 015 27

. 015 35

.015 51

A'.

A

A

1 0.0178

0.001 013

. 002 15

.003 492

. 004 38

. 005 573

. 006 75

. 007 98

. 009 13

. 010 33

. Oil 55

. 014 84

. 019 48

.023 3

.028 0

. 033 77

.040 0

. 068 2

. 107 4

.111 5

.121 1

Log. A'.

3.000

3. 333

3.543

3.642

3.746

3.829

3.902

3.961

2.015

2.063

2. 171

2.290

2.368

2". 447

2.529

2.602

2.833

1.031

1.048

1.084

B. 

Barium chloride remaining in solution per gram 

of water 

(grams).

0. 000 004

. 000 008

. 000 008

. 000 048

. 000 076

. 000 111

. 000 149

.000 197

. 000 246

. 000 299

. 000 692

. 001 070

.001 491

. 001 913

. 002 836

. 003 769

. 008 588

. 013 473

. 018 465

. 023 449

Log. B.

6.602

6.903

a. 6903

5. 681

5.881

4.045

4. 173

4.295

4.391

4.476

4.840

3.030

3.174

3. 282

3. 453

3.577

3.935

2.130

2. 267

2.370

"Erroneous.

These are plotted in figure 4. The equation representing the 

A' A

data is , = 0.7646805, where A' =

1- 0.0178

SILVER IODIDE AND SILVER NITRATE.

A. Lottermoser and A. Rothe (71) have determined the adsorption 

of silver nitrate by fresh precipitated silver iodide. The concentrations of the solutions employed were determined by means of electrical conductivities. The following is their table:

Adsorption of silver nitrate by silver iodide.

Co

Silver

nitrate per 

cubic centimeter of 

original solution 

(millimoles).

0. 00045

. 00075

.00107

.00163

. 00232

. 00502

. 00988

. 01519

B.

Silver 

nitrate per 

cubic centimeter of final 

solution

(millimoles).

0. 00019

. 00045

. 00073

. 00123

.00188

. 00450

. 00928

. 01456

LogB.

-3. 7212

-3. 3468

-3. 1367

-2. 9101

-2. 7258

-2. 3468

-2. 0324

-1.8308

A.

Silver 

nitrate adsorbed per 

gram of silver 

iodide

(millimoles).

0. 0023

.0026

.0029

.0034

.0038

.0045

.0051

.0054

Log A.

.-2.6383

-2. 5850

-2. 5376

-2. 4685

-2. 4202

-2. 3468

-2. 2924

-2. 2676

A as

computed 

from 

the 

equation.

0. 0024

.0028

.0031

.0035

.0038

.0046

.0051

.0057
PROPERTIES OP COLLOIDS. 39

A millimole is one one-thousandth part of the molecular weight of 

a substance expressed in grams. In the case of silver nitrate a millimole is 0.170 gram.

A

The equation is -p 0. 19a6 =

A'

gO.5173 .7647-

0.0/78

4.0 3.0 2.0 1,0

LOG.B

FIGURE 4. Adsorption of barium chloride by Klingenberg clay.

SILVER IODIDE AND POTASSIUM IODIDE.

Peptization. These investigators further show that the freshly 

precipitated amorphous silver iodide may be peptized by treatment 

with the soluble iodides of either potassium, cadmium, or barium, as
40 COLLOID MATTER OF CLAY.

shown by the following table for potassium iodide, acting on 0.25 

gram silver iodide in 25 cubic centimeters of water.

Effect of potassium iodide solution on silver iodide.

Concentration of

potassium iodide

in the solution

(normality).

0.0005

.001

.002

.004

.01

.02

.03

.05

.075

.1

.15

.25

Effect on silver iodide.

Very weak hydrosol formation.

Beginning of intense hydrosol formation.

Strong increase of the same.

Further increase. A visible alteration of the silver iodide structure

Strong hydrosol formation.

Do.

Maximum hydrosol formation. 

Decreased hydrosol formation.

Do.

Complete alteration of structure of silver iodide. 

Almost no hydrosol formation. 

No hydrosol formation.

The authors say that dried precipitates or dry preparations of silver 

iodide can not be peptized; That if the hydrosol is once completely 

precipitated it can not be peptized; that is, the hydrosol phase must 

never be completely eliminated, for then an "alteration of structure" 

will occur.

Adsorption. As might be expected from this, on attempting to 

measure the adsorption of potassium iodide by silver iodide, they 

fail to obtain data that may be represented by the adsorption equations. The results follow:

KO = specific conductivity of the solution before adsorption. 

K = specific conductivity of the solution at equilibrium.

Adsorption of potassium iodide by silver iodide.

Ko .10".

45.1

72.2

176.0

280.8

448.2

694.8

873.2 i.osas

1,275.0

1,381.4

0

Potassium 

iodide at start 

(moles per 

liter).

0. 000 299

. 000 481

;001 181

. 001 900

. 003 032

. 004 772

. 005 997

. 007 231

. 008 894

. 009 637

K .10«.

19.7

61.5

164.3

268.8

399.3

646.2

827.4

- 992. 8

1,245.6

1,359.4

B.

Potassium 

iodide at equilibrium 

(moles per 

liter).

0. 000 130

.000 410

. 001 102

. 001 819

. 002 701

. 004 438

. 005 683

. 006 926

. 008 689

. 009 483

LogB.

-3. 886

-3. 387

-2. 959

-2. 740

-2. 569

-2. 353

-2.246

-2. 160

-2. 061

-2.023

A.

Potassium 

iodide adsorbed 

per gram 

silver iodide 

(millimoles).

0.0046

.0078

.0084

. .0087

;0090

.0090

.0085

.0077

.0055

.0040

Log A.

-2.337

-2. 108

-2.076

-2. 061

-2. 046

-2. 046

-2. 071

-2. 114

-2.260

-2. 398

In the logarithmic diagram (fig. 5) the second, third, fourth, and 

fifth points are exactly on a line, and, therefore, may be represented 

by an exponential equation, but the fifth point is at a maximum, 

higher initial concentrations resulting in decreased adsorption.

The authors suggest that this phenomenon may be due to structure alteration or to complex salt formation, but find no connection
PROPERTIES OF COLLOIDS. 41

between it and hydrosol formation. The present writer has made 

calculations to ascertain if decreased dissociation due to increased 

concentration might account for the decreased adsorption. No such 

relationship was indicated.

TENNESSEE BALL CLAY AND MALACHITE GREEN.

In investigation of the adsorption of malachite green by Tennessee 

ball clay No. 3, of the Tennessee Ball and Sagger Clay Company, 

Whitlock, Tenn., and the Potters' Supply Company, East Liverpool, 

Ohio, the logarithmic diagram (fig. 6) shows a similar maximum, but 

none of the points lie on the same straight line, even when a correcFIGURE 5. Adsorption of pota°sium iodide by silver iodide.

tion factor is introduced similar to that used in the discussion of 

Hirsch's results on the adsorption of barium chloride by Klingenberg 

clay.

SUMMARY.

In this discussion of equations are included only those cases which 

have been studied from very small concentrations up to the highest 

possible adsorption. We have then the exact equation A B~n = K, 

applying to 

Silk and picric acid, 

Gelatine and tannin, 

Hagerstown loam and gentian violet, 

Silver iodide and silver nitrate;
42 COLLOID MATTER OF CLAY.

the corrected equation A'B~n = K, where A' =

1- A

-, applying

toconstant

Quartz flour and gentian violet, 

Klingenberg clay and barium chloride;

4.5 

LOG. B

3.0 3.5

FIGURE 6. Adsorption of malachite green by Tennessee Ball and Sagger Clay Company's Tennessee Wall

clay No. 3.

and the cases showing maxima and not permitting the use of such 

equations, as follows:

Silver iodide and potassium iodide, 

Tennessee ball clay No. 3 and malachite green.

It does not yet seem possible to formulate an equation that shall 

apply to all cases of adsorption.

DETERMINATION OF PLASTICITY.

DEPENDENCE ON COLLOIDS.

If the plasticity of clays is mainly due to a proper ratio of granular 

materials and active (that is, not "set") colloid gels, any means of 

establishing the relative or absolute amount of colloids in a clay 

should supply a measure of its plasticity.
DETERMINATION OF PLASTICITY. 43

Of course, the shape and size of the granular materials (whether 

of crystal nature or "set" gels) will be of some effect, as will also 

the special nature of the active colloids present. Any methods 

applied to testing other colloids should be of value in testing clays. 

For instance, glues and clays are tested by the tensile-strength test 

for tensile strength or binding power. While this test is of value, 

it does not tell how workable a clay is. Sugars and oils are tested 

by measurements of viscosity. Simonis (51, 52, 53, 72, 73), Mellor 

(47), and Bleininger (49) have applied this test to clay slips. The 

two former have shown by this means how plasticity may be altered 

by additions to clay slips, especially in regard to their suitability 

for the casting process. Bleininger has shown in the case of three 

well-known clays that the more plastic has the greater viscosity.

ADSORPTION TESTS OF CLAYS.

Hirsch (70) in his paper on the behavior of clay in salt solutions 

saw the possibilities of adsorption. He. said: "We hoped at first to 

be able to classify the clays according to their plasticities with the 

help of this process [adsorption of barium chloride]. The lean, very 

sandy brick clays fall completely out of the series, and partially 

show a greater adsorption than the fat, highly plastic clays." The 

present writer, having the information that colloids adsorb dyes, but 

without any details, also sought to apply this principle to the measurement of plasticity.

ADSORPTION TESTS WITH BRILLIANT GREEN.

On May 21, 1908, at a meeting of the Pittsburg section of the 

American Chemical Society, an informal discussion was held regarding the results then attained. The following table was shown. The 

comparisons were made colorimetrically with improvised apparatus 

of the crudest sort:

Dye remaining unadsorbed on treating various clays (50 grams each) with brilliant green 

(in 1,000 cubic centimeters water}. a

Harris, North Carolina china clay ....

0.10

0.002

0.20

0.002 

.002 

.007

0.30

0.004

.031

0.50

0.001

.0073

0.60

O.OCG 

.021

.111

1.00

0.001 

.017

.073

.111 

.172

,292

2.00

0. 0133 

.004

.110

3.00

0.045

« All experiments submitted herewith were made with tap water from Ohio River, filtered through 

gravel and led in by a long iron pipe.

In the column for 1.00 gram dye-these clays fall approximately 

in the order of their plasticities. There are, however, various anoma-
44 COLLOID MATTER OF CLAY.

lies, the most striking of which, is the apparent difference of WH2 and 

B B china clays, which are practically almost duplicates in plasticity.

In the discussion, Dr. Joseph H. James suggested .that malachite 

green would be found a more stable dye, less likely to be affected by 

adventitious circumstances, and subsequently the use of that dye 

was adopted with decided advantage.

A further series of tests was, however, made with brilliant green. 

In each case the water, the crushed air-dry clay, and the dry dye 

were put in a small test blunger, blunged for 30 minutes, and then 

allowed to settle until apparently clear. The dye remaining in 

solution was determined colorimetrically.

Dye remaining unadsorbed on treating various clays (50 grams each, in 1,000 cubic 

centimeters water) with brilliant green dye.

"Lone Star," Texas "kaolin".. . ...................................

No. 10 run-of-mine Tennessee ball clay, Johnson-Porter Clay Co. ...

No. 12 English ball clay, G. Knowles & Sons. . .....................

No. 1 sagger clay, P. L. Ryan. . ....................................

No. 8 sagger clay, Edgar Bros. Co. .................................

Al English china clay, Hammill & Gillespic. .......................

1.00

0. 0006

. 000338

.006

 . 00814

.0095

.011

.017

.018

.020

.022

.028

.0287

.0424

.056

.0562

.0588

.073

.084

..094

.098

.111

.126

.172

.1886

.292

.314

.314

.375

.500

2.00

0.013

.0878

.0253

.111

.064

.061

.1456

.063

.102

.110

3.00

0. 000097

.045

.0901

4.00

0. 0878

.1818

a With 7.00 grams, the result was 0.000827; with 10.00 grams, 0.00267; with 13.00 grams, 0.01054; with 

18.00 grams, 0.1205.

These clays fall neither in the order of plasticity nor of merit in 

the column with 1.00 gram dye; 2.00 grams dye give a somewhat 

better arrangement, Texas, Pike's No. 20, Ryan No. 1, M. & M. ball, 

Knowles's, No. 12 ball, Tennessee No. 3, special sagger, Florida, No. 10 

run-of-mine, and Tennessee No. 9, falling in ascending sequence.

If, however, these clays are grouped so that only clays of a common 

origin are in the same column, the arrangement is more logical in 

each group.
DETERMINATION OF PLASTICITY. 45 

Dye unadsorbed (1 gram added), arranged by origin of days treated.

English ball clays.

Eimor & 

Am en d 

ful ler's 

earth. 

Pike'5! No. 

20. 

Knowles's 

No. 12. 

M o o i." e & 

Hunger.

0.0006

.0095 

.017 

.022

Tennessee ball and 

sagger clays.

Tenness e e 

No. 3.

No. 10,-run 

of mine. 

Tennessee 

No. 9. 

Special 

sagger. 

P. S. Co. 

wad. 

J-P. C. Co. 

wad. 

M-S. C. Co. 

wad.

0.008

.011 

.020 

.028 

.098 

.126 

.314

Atlantic coast 

sagger clays.

Ryan No. 1

Edgar No. 

8. 

Edgar No. 

10. 

SuchBB..

0.018

.029 

.042 

.059

Atlantic coast 

china clays.

Bryson..... 

Penland.... 

Bluemont. .

0.006

.056 

.172 

.189

English china 

clays.

HN. ......

Poole No. 

1. 

WH2 .......

BE.......

Al.. .......

M GR..... 

No. 15......

0.084

.094 

.111 

.292 

.314 

.375 

.500

It would appear from.this that the colloidal matter in any one of 

these groups, for example, Atlantic coast china clays, has an effect 

on brilliant green different from that of the colloidal matter in 

some of the other groups, for example, English china clays. Brilliant 

green may then be of use only to compare clays of a common origin, 

or to check the uniformity of a particular clay from time to time.

COMPARISON OF BRILLIANT GREEN WITH MALACHITE GREEN.

Schultz and Julius (74) give the following formulae:

Malachite green (oxalate), (C23H24N2 ) 2 (C2H204 ) 3 , of which the molecular weight is 890.6, or per one color base ion, 445.3.

Brilliant green crystals, C27H34N2 04S; molecular weight, 482.4.

The structural formulae may be represented as shown in figure 7.

The brilliant green has the more complex color base, having four 

C2H5 groups against an equal number of CH3 groups in malachite 

green. According to Pelet-Jolivet and Wild (75), malachite green is 

wholly noncolloidal, while from the paper of Hober and Chassin (76), 

brilliant green seems also to be noncolloidal. The former authors 

find that dye solutions, under the influence of electrolytes, go over 

to the colloid condition, and think that contact with ; an adsorbent 

favors such a transformation.

QUALITY OF WATER USED.

The tap water used in this work contained considerable amounts 

of calcium sulphate and calcium carbonate, and lesser amounts of 

magnesium sulphate, magnesium carbonate, and sodium chloride. 

It would consequently have a considerable precipitating effect on the 

oxalic acid ions of the malachite green. This was found to be the 

case, but if the water were of constant composition, it should not 

affect the order of the clays in the classification, as equal volumes were
46 COLLOID MATTER OF CLAY.

used in all comparisons. However, it was found that acetic acid 

would prevent precipitation, and it was employed in a considerable 

number of tests with malachite green. It was then found, although 

a preliminary test had given the opposite result, that the weak con^ 

centration of acetic acid present acting on the iron stirrer of the 

blunger was effecting some decolorization of the dye. These results 

were accordingly discarded and the use of the blunger was abandoned 

entirely.

The results with acetic acid failed to give a more accurate classification than did the simple aqueous solution. Consequently the 

use of acetic acid was abandoned.

(CH3) 2 

Gj.Hj.04.

CiHj.04-

FIGURE 7. Structural formulas of malachite green and brilliant green.

MALACHITE-GREEN ADSORPTION AND PHYSICAL PROPERTIES OF CLAYS.

METHODS OF TESTING.

The following procedure was eventually adopted. Into a 500 

cubic centimeter bottle with ground-glass stopper greased with 

vaseline, 20 grams clay and the dye were placed, then 400 cubic 

centimeters water was added. The closed bottle was then fastened 

in the frame of a small ball mill (60 revolutions per minute) so that 

at every revolution it was upended. This gave a. vigorous and complete agitation, which lasted for an hour. Although the clay 

appeared to settle clear in half an hour, the results were too large and 

erratic unless the settling continued over night.0 On the following

a Poole's No. 1 china clay (50 grams clay, 1,000 cubic centimeters water, 3 grams dye) gave:

Grams dye

in excess.

July 30, after standing some time.............................................................. 1. 840

July 31, after standing over night.............................................................. 1.797

July 31, after rotating again (seemed clear)..................................................... 2.012

August 1, after standing over another night.................................................... 1.750
U. S. GEOLOGICAL SURVEY

APPARATUS FOR MAKING COLOR COMPARISONS TO DETERMINE ADSORPTION OF DYESTUFF.
DETERMINATION OP PLASTICITY. 47

day a convenient amount of the clear liquid was taken out by a 

pipette and put into one of a pair of "carbon" comparison tubes 

such as used in steel analysis, and compared by dilution with a 

standard solution of 3 grams per liter, using a camera while 

matching. (See PI. I.)

RESULTS OF TESTS.

The powers of various clays to adsorb malachite green, together 

with other physical properties, are given in the following table, in 

which the clays, as elsewhere in this bulletin, are designated by their 

trade names:
Adsorption of malachite green and the other physical prop

Designation of clay.-

A. H. Williams, Texas " kaolin" ......................

Potters' Supply Co., Tennessee No. 3 ball. ............

Jas. P. Prall, No. 1 light sagger (N. J.) ................

J. Poole, Pike's No. 20 English ball 6 ..................

Mandle-Sant Clay Co., Tennessee No. 3 ball ............

Hammill & Gillespie, Whiteway's English ball .......

Kentucky Construction and Improvement Co., No. 1

Johnson-Porter Clay Co., No. 9 Tennessee ball ........

William H. Prall, No. 1 retort (N. J.) ................

Wilhelm Priem, Zettlitz ( Germany) kaolin ...........

Mandle-Sant Clay Co. , Tennessee No. 9 ball ............

Portion unabsorbed.

1.00 gram 

dye used.

O.OO081 

( Perfectly! 

\ clear? j

.00371

.0086 

.00333

.00258

.00445

.01635 

.00477

.00731

.00268 

.0206

. 02235

. 00872 

. 02325

.0343

. 01895 

.023

3.00 grams 

dye used.

0. 00351 

. 01075 

. 01904

.03608 

.0470 

.0699 

.0680

.0764 

. 0848 

.109

.1221

.186 

.1591

.1955 

.2083 

.219 

.235

.2288 

.255 

.263 

.2792 

.286

.2828 

.295

.316 

.372

.494 

.578 

.683

.775 

.925

.938 

.967

1.058 

1.137

A. 

JacksonPurdy surface factor.

121 

123

184 

168 

185

170 

184

199

173 

( Dyed. \ 

\ 113?J 

170 

150 

152

172 

179

178+ 

183

117

168 

/ Dyed. I 

1 129 /

137 

78

187 

f Dyed. \ 

X 85 / 

191

59 

192

B.

Cast air 

shrinkage.

25 

12.0

18.6 

8.5 

12.2 

11.9 

8.5 

11.5 

11.5 

9.8 

10.7

11.3 

12.0

12.3 

9.2 

9.4 

7.5 

9.7 

11.3 

. 9 

10.0 

9.4 

8.6 

12.0 

9.7

Total

8 

5.0

9.6 

14.8 

7.9

0 

9.7

Fire 

(co

, 15.0
'(-W

i

Johnson-Porter Clay Co., No. 1 ball (Tenn.) ..........

.0299

.0759

.0405

nqi

.0408

ncoo

.0892

.0935

.0758

.1042

299

*°

1.000

1.146

1.152

1.187

1.230

1.348

1.440

1.456

1.459

1.500

1 CCJ.

1.616

1.808

1.860

1.886

1.929

2.060

2. 410 '

2.760

3.000

199

163 

188

178

143

133

198

175

175

186

f Dyed.\

I 134 | 

/ Dyed.1

i 101 /

144

156

170

178

163

126

7.6

6.2

9.2

8.6

6.2

9.2

7.0

6.2

8.1

5.4

9.2

9.0

6.6

7.6

9.0

5.1

6.4

6.3

7.0

M

05.00 grams, 0.0456; 7.00 gram, 1.291. t> 2.00 grams, 0.0276; 4.00 gram, 0.2855. 
50 COLLOID MATTER OF CLAY.

MALACHITE-GREEN ADSORPTION.

The results with 3.0-gram dye per 50.0 grams clay in 1,000 cubic 

centimeters water are used as a basis for comparison. From these, 

column C has been prepared by means of figure 8. a The principle is 

this: If there is a certain amount of colloids in, say, 10 grams of No. 

3 ball clay, there is twice as much in 20 grams, three times as much 

in 30 grams, etc. Let us call the amount of colloids.in 50 grams 100, 

in 20 grams 40, etc. Treating each of these amounts of No. 3 ball 

clay with 3 grams of malachite green, we obtain the curve shown in 

figure 8. Now suppose we take 50 grams of any other clay, say, 

Moore & Hunger's ball clay, and treat it with the same .amount of

20 30 

Grams P. 5.Co. No.3,Tennesse? ball clay

50

80 100

Relative colloid value 

FIGURE 8. Adsorption of malachite green by Potters' Supply Company's Tennessee ball clay No. 3.

dye, the amount of dye adsorbed proves to be 2.8779 grams; 2.8779 

grams comes on the curve at 43.35 grams Tennessee ball No. 3, or at 

90.7 relative colloids; that is, it is assumed that clays adsorbing 

equal amounts of dye contain equal amounts of colloids, and these 

are expressed in terms of the amount present in Tennessee ball No. 3.

PHYSICAL PROPERTIES OF CLAYS.

Column A, Jackson-Purdy surface factor, contains numbers which 

it is convenient to assume are proportional to the total area of all the

a Work performed in 1909 with pure water and longer periods of shaking show that the two branches 

of the curve shown in figure 8 approximate straight lines, meeting at an angle.
DETERMINATION OF PLASTICITY. 51

particles in a unit weight of clay, and are thus- a measure of the 

fineness of the material. The method was originally proposed by 

W. Jackson (77) and made more general by Ross C. Purdy (78). The 

assumption is far from correct, as the colloids and soluble salts are 

not granular and the average size assumed for the smallest grains is 

incorrect, but it is a convenient approximation.

Column B, cast air shrinkage, contains values obtained by casting 

a clay slip into a plaster of Paris mold 10 centimeters in diameter, 

using approximately 50 grams of clay, and giving a test piece about 

.0.5 centimeter thick. A number of precautions are necessary for 

accurately comparable work, and it is regretted that some of these 

figures, three years old, do not have the precision of later work 

(79, 82).

The column of fire shrinkage at cone 8 is put in merely because of 

its general interest.

The surface factor, air shrinkage, and relative colloids were in 

some cases determined on one and the same sample; in others, on 

separate lots; and in still others they are averages of material examined over considerable periods. ' However, such error as is introduced in this manner is properly to be charged against the clay.

The maximum errors possible are probably 20 per cent in the case 

of the surface factor, 1 per cent for air shrinkage, and 5.0 per cent for 

relative colloids. The average errors, however, will not exceed 5 per 

cent for surface factor, 0.3 per cent for air shrinkage, and 2.5 per cent 

for relative colloids.

In column D has been put the surface concentration of colloids, 

obtained by dividing the relative colloids by the surface factor. It 

is an attempt to express numerically the density of the layer of 

colloid material that is considered as enveloping the granular material. Theoretically, not the surface factor but only that portion 

corresponding to the granular material should be used; but a method 

for obtaining this information has not yet been worked out. The 

values in this column should closely parallel the bonding power of 

these clays.

It is assumed that the various clay colloids will differ in their 

ability to absorb water, and, consequently, in their shrinkage. In 

column E it is attempted to measure this effect by calculating the 

specific air shrinkage, for which purpose the linear air shrinkage is 

divided by the relative colloids.

The lubricating layer,- permitting motion to the granular particles, 

is made up of colloids holding water; and in column F this is estimated as deformability, directly proportional to the surface concentration of colloids and to their specific air shrinkage, hence to their 

product.
52 COLLOID MATTER OF CLAY.

, Texas "kaolin."

Mandle-Sant special sagger.

Prall No. 1 sagger.

Prall No. 1 retort.

Knowles No. 12 ball.

Potters' Supply Tennessee ball No. 3.

Pike's No. 20 ball.

Eyan No. 1 sagger. 

, Paul ground fire clay. 

. Mandle-Sant Tennessee No. 3. 

. Atlanta M. & C. Co. 

. Kentucky C. & I. Co. No. 1 sagger. 

. Diamond Fireclay Co. 

. Johnson-Porter No. 9 Tennessee. 

. Moore &'Munger ball. 

. Excelsior B. C. Co. sagger. 

. Potters' Supply Co. Tennessee No. 4. 

. Edgar No. 8 sagger. 

. Edgar Florida. 

. Such BB sagger. 

. Edgar No. 1 10 sagger. 

. Mandle-Sant No. 11 Tennessee. 

. Johnson-Porter wad. 

, Potters' Supply Co. wad. 

, Johnson-Porter UX sagger. 

, Harris Penland kaolin. 

, Harris Bryspn kaolin.

Priem Zettlitz kaolin. 

. Mandle-Sant wad.

Hall Georgia kaolin.

Mandle-Sant Tennessee No. 9.

Johnson-Porter No. 1 ball.

Adolph WE2 kaolin.

Hammill & Gillespie kaolin. 

. Duncan White Mountain clay.

Poole No. 1 kaolin.

PooleBB kaolin.

Moore & Munger HN kaolin.

Sant Bluemont kaolin.

Peach kaolin.

Moore & Munger MGR kaolin.

Knowles No. 15 kaolin.

.I74O 

Deformability

.20 .40 

E. Specific air shrinkage of colloids

FIGURE 9. Surface concentration and specific air shrinkage of clay colloids as related to deformability.
DETERMINATION OF PLASTICITY. 53

The relations of columns D, E, and F are shown graphically in 

figure 9. It will be seen that ball and sagger clays fall in one group, 

having colloids of low specific air shrinkage. The china clays fall in 

another distinct group, having low surface concentration of colloids. 

The wad clays apparently form a distinct group with somewhat 

greater surface concentration of colloids than the china clays. The 

Texas and Florida " kaolins " a are distinct from all other clays and 

from each other. The two fire clays tested are closely associated 

with the ball and sagger clays. With finer grinding the resemblance 

would appear stronger.

Finally in column G an expression is given for plasticity. Both 

Zschokke (80) and Grout (9) have experimentally determined plasticity as the product of a deformation by the force producing it. Similarly it is here taken as the product of the deformability by the force 

resisting deformation, assuming that this resistance is exerted by the

colloids, which are the cementing materials supplying the cohesion 

of the clay. This is the product of columns C and F, but F is the

C B product of columns D and E, and these represent -r and p respec-

... , , n CxB tit very; whence G = -r .

Since ordinarily the shrinkage (B) and the surface factor (A) are

TO

both highest with high colloidal matter (C), it is evident that -r- will 

approximate a constant, and that plasticity is mainly due to the relaTD

tive colloids (C). The fraction -r seems to take care very satisfactorily of the variations in the nature of the colloid matter and of the 

size of grain.

It will be noted that increased fineness of grain is considered as 

cutting down the plasticity. It has been the writer's repeated observation that increased fineness of grain of the granular material in a 

clay or body is a source of weakness and trouble; that, having greater 

surface, more colloid matter is required to cement the fine granular 

matter together and so shrinkage and liability to crack are increased.

a Work performed in 1909 shows that the surface factor of Florida clay is really 185, so that the data 

based on this determination are in error, and the clay really falls nearer the other china clays on the 

deformability diagram.
54 COLLOID MATTER OF CLAY.

PLASTICITY. 

AS DETERMINED BY MALACHITE-GREEN ADSORPTION TESTS.

In the following table the clays are arranged as classified by 

column G:

Plasticity of various clays.

Texas " kaolin "........................................................... 10. 34

Ball and sagger clays:

Maudle-Sant special sagger.............................................? 9. 09

Prall No. 1 light sagger................................... r ............ 7. 27

Ball clays 

Knowles No. 12 ball.............................................. 6. 53

Pike's No. 20 ball................................................ 6. 28

Mandle-Sant No. 3 Tennessee...................................... 5. 96

Johnson-Porter No. 9 Tennessee................................... 5. 76

Kentucky Construction and Improvement Co., No. 1 sagger........ 5. 69

Edgar Plastic Kaolin Co., Florida..................................? 5. 66

Prall, No. 1 retort................................................ 4. 90

Moore & Hunger, ball.............................................. 4. 88

Ryan, No. 1 sagger................................................... 4. 79

Atlanta Mining and Clay Co., Georgia................................. 4. 73

Potters' Supply Co., No. 3 Tennessee................................... 4.62

Potters' Supply Co., No. 4 Tennessee................................... 4. 52

Excelsior Ball Clay Co., sagger........................................ 4. 20

Such, B B mixture .................................................. 3. 66

Edgar Bros. Co., No. 8 sagger......................................... 3. 51

Johnson-Porter, No. 10 Tennessee...................................... 3. 45

Edgar Bros. Co., No. 10 sagger......................................... 2. 63

Paul Clay Co., ground fire clay........................................ 2. 595

Wad clays:

Johnson-Porter, X wad..................................:............? 1. 867

Johnson-Porter, TJX sagger............................................ 1. 824

Potters' Supply Co., wad............................................. 1. 775

Mandle-Sant Clay Co., wad...........................................? 1.530

Mandle-Sant Clay Co., No. 9 Tennessee...................................... 1. 473

Johnson-Porter, No. 1 ball................................................. 1.378

China clays:

Hall Clay Co., Georgia sagger (kaolin) .................................. 1. 335

Priem, Zettlitz, kaolin................................................ 1. 335

Harris, Penland china clay........................................... 1.117

Adolph, WH2 china clay............................................... 1.104

Harris, Bryson china clay.............................................. 1. 097

Poole, No. 1 china clay. ............... i............................... 1. 097

Sant, Bluemont china clay............................................ . 916

Duncan, White Mountain clay........................................ . 903

Poole, B B china clay................................................ .873

Hammill & Gillespie, Al china clay.................................... . 868

Moore & Munger, H N china clay...................................... . 675

Moore & Munger, M G R china clay................................... . 647

Knowles, No. 15 china clay........................................... . 618

Peach Kaolin Co., china clay.......................................... . 556

Diamond Clay Co., ground fire clay........................................ . 000
DETERMINATION OF PLASTICITY. 55 

PLASTICITY AS FOUND IN PRACTICE.

Various anomalies have to be explained. Experimental errors in 

elutriation, clue to incomplete deflocculation of the clays, have probably made too high the values marked with a ?. In these cases 

the dyed clay was elutriated. It was found out later that dyeing 

increases the size of the floccules and hence decreases the surface 

factor. The two No. 3 Tennessee ball clays occur on adjacent properties. It is believed that the shrinkage measurements or the surface factors of one or both are in error, the former having been made 

three years ago for one of the clays and the latter presenting difficulties in deflocculation. The Mandle-Sant No. 9 Tennessee ball is 

much more plastic than its position in the table indicates. Neither 

UX nor Johnson-Porter No. 1 ball is a strong clay, and they are 

correctly placed. Among the china clays there is the possibility of

the addition of some whitening agent, or of wetting by salt water 

in transit across the ocean, that would interfere with the colloid test. 

The lowest English clay on the list, Knowles No. 15, has a very good 

reputation as a " safe" clay. The Diamond Clay Company's fire clay 

with finer grinding will have a measureable shrinkage, and is capable 

of being classed with the sagger clays if so ground. But as supplied, 

i.ts shrinkage-is less than the possible error of measurement, and it is 

correctly placed as to the plasticity in the coarse ground condition.

Very few people will agree exactly in their conception of plasticity. 

Each considers a body most plastic when it best suits his work. A 

jiggerman and a presser in the same clay shop will not agree as to 

the amount of moisture required in the body used. When a brickmaker calls a clay plastic he means that it will work well in his 

machine; but a potter means by the same phrase that it is fat enough 

to mix with considerable inactive material ("flint," spar, etc.) to 

make a workable body. An electric porcelain plant will have a 

tube, wet-press, or plastic body and a dry-press or insulator body. 

The writer hopes to show by later investigations that a certain 

"degree" or measure of plasticity is best suited to each class of 

manufacture.

The errors of measurement are in most cases small, and on the 

whole the table accurately represents those properties of clays that 

may be collectively described as plasticity. -

o In valuing clays, plasticity is but one of the factors to be considered; refractory properties, color, cleanness, etc., all go together in 

the selection of the clays to be used for the manufacture of wall and 

floor tiles, sanitary ware, terra cotta, pottery, etc. The measurement of the relative colloids, surface factor, and cast air shrinkage 

of various clays will give, however, an accurate and complete idea 

of their working properties or plasticity.
56 COLLOID MATTER OF CLAY.

MISCELLANEOUS APPLICATIONS OF MALACHITE-GREEN

TEST.

EFFICIENCY OF GRINDING.

The Texas "kaolin" and the fire clays .mentioned in the preceding 

pages were tested as supplied to the trade. They were also tested 

as to the effect of fine grinding.

Test of 50.0 grams Texas "kaolin," 5.00 grams malachite green, and 1,000 cubic centimeter's of water.

Grams dye unaclsorbed. 

As supplied.................................................... 0. 0456

Ground 1 hour in ball mill with dye............................ . 0314

Ground 2 hours in ball mill with dye........................... . 0315

Test of 50.0 grams Paul Clay Company's ground sagger (fire clay) ivith malachite green 

and 1,000 cubic centimeters of water.

1.00 gram 3.00 grams 

dye. dye.

As supplied............................................ grams dye unadsorbed.. 0.023 25 0.578

Ground 1 hour ...........................................................do.... .001 515 ............

Ground 2 hours ..........................................................do................ . 2513

Test of 50.0 grams Diamond Clay Company's ground fire-clay with malachite green and 

1,000 cubic centimeters of water.

1.00 gram 3.00 grams 

dye. dye.

As supplied ............................................grams dye unadsorbed.. 0.018 95 1.058

Ground 1 hour............................................................do.... .000 309 ............

Ground 2 hours...........................................................do................ .065

In each of these cases finer grinding caused increased adsorption 

of dye, but the extent of the effect is markedly different in the three 

cases and seems to correspond to the development of the so-called 

"latent" plasticity of fire clay. This has already been ascribed 

(p. 13) to a reabsorption of water and a swelling to the original bulk 

of the clay, possessed ages ago before the clay had been subjected to 

pressure in its place of deposit.

The dye test then supplies a measure of the efficiency of grinding 

in increasing the plasticity of a fire clay.

It was noticed that brilliant green, instead of retaining its usual 

bluish-green tint, became a much purer green with Pike's No. 20 ball, 

Eimer & Amend's fuller's earth, and Sant's Tennessee ball No. 3; 

no explanation is offered. Malachite green developed a purer blue 

with Eimer & Amend's fuller's earth.
APPLICATIONS OF MALACHITE GREEN TEST. 57

FULLER'S EARTH.

Fuller's earth has been shown by W. L. Dubois (35) to be utterly 

unreliable as a means of estimating colorirnetrically the amount of 

caramel in vinegar, when equal amounts of fuller's earth are used 

with equal amounts of vinegar. With pure vinegars any given lot 

of fuller's earth would have no effect on some vinegar, and would 

remove up to 60 or 70 per cent of the color from other vinegars. The 

results appeared extremely erratic. While this problem is separate 

from the present investigation, it is closely parallel; in both cases a 

colloidal earth is used to remove a coloring matter from solution. In 

the light of this experience it is thought that the following arrangements would lead to comparable results: As, in this work, the 

addition of acetic acid increased the apparent intensity of the dye 

up to 33 per cent over that in aqueous solution, it would appear that 

vinegars should be brought to a uniform acidity before applying the

fuller's-earth test; that is, either water or pure acetic acid should be 

added to bring the acetic acid to a standard concentration. Dubois 

"used various fuller's earths of unknown colloidal strength to precipitate caramel of unknown strength. The proper procedure would 

seem to be to determine what proportion of a particular fuller's earth 

will remove caramel most completely from a particular vinegar when 

brought to the standard acetic-acid concentration. Then standardize 

this fuller's earth against a pure dye solution, such as the malachite 

green oxalate used in this work. In using other lots of fuller's earth 

such quantities should be taken as will have equal decolorizing 

action on the standard dye.

By this procedure the writer feels confident that the fuller's-earth 

test for caramel would be much improved.

PARIS WHITES.

The malachite green test has been applied to a number of " English 

cliffstone Paris whites" with the following results:

Test of English cliffstone Paris whites with 3 grams of malachite green dye.

Dye 

unadsorbed.

0. 0218

.0224

.0251

.0280

Relative 

market

150

120

115

100

Surface 

factor.

182

168

168

165

Remarks.

Claimed to be finest sold.

It appears that there is a close relationship between market price 

and fineness and dye precipitated. It is also to be remarked that 

carbonate of lime in this form removes the dye very completely from 

solution, and to a much greater extent than corresponds to the very 

slight plasticity it possesses. Way (15) observed the presence of
58 COLLOID MATTER OF CLAY. 4

gelatinous silica in the chalk formations; so that it will be necessary 

to find out whether pure dalcium carbonate has the same action as 

this English cliffstone Paris white.

FUTURE WORK.

There is still considerable work to be done in connection with this 

test for colloids.

While malachite green seems excellent for the purpose, other dyes 

may be equal or better. Messrs. H. A. Metz & Co. have kindly supplied a very comprehensive set of dyes for studying this point. The 

dye selected should be tested to see whether supplied in uniform 

quality from various sources.

'The possible disturbing effect of various soluble salts and minerals 

should be determined.

The rate of deterioration of standard solutions should be studied.

These studies have been confined to high-grade clays, and a wider 

range of materials should be studied. Samples of the various bodies 

used in the ceramic industries have been collected, and it is intended 

to ascertain whether definite numerical limits can be given for the 

plasticity required by each.

It is also intended to study the process of aging clays, as this 

method will permit measurement of the progressive increases in 

plasticity.

It is intended to formulate a field test for plasticity that will determine whether the clay is worth more accurate investigation.

Seger (81) has noted in several places that there seems to be a close 

relationship between the amount of soluble salts in a clay and its 

plasticity. Purdy and Moore consider it "an exceedingly probable 

assumption that it is the influence of the adsorbed salts that gives to 

a day its plasticity" (83). It is probable that in the malachite green 

test the color base is exchanged with the bases that stabilize the gel 

and with the bases of the soluble salts present, and that the oxalates 

of lime, etc., are precipitated. It is possible that a dye having its 

color base united with hydrochloric acid may supply an excellent 

means of studying the soluble salts in clay. Hirsch's work with aluminum chloride indicates the feasibility of such a procedure (70).

As an accurate surface factor is essential to a careful study of a clay, 

the best means of defiocculation of the clay particles before elutriation 

should be studied. It is not believed that ammonia, or long boiling, 

or violent shaking is the proper means; but that the formation of the 

clay hydrosol can be better effected by the addition of a more suitable 

chemical reagent or solvent. This is being studied.
KEFERENCES. 59

SUMMARY. t

. Clay is defined as a mixture of granular matter and a colloid gel.

The sources of the colloid matter are organic, resembling peat, and 

inorganic, principally colloidal silicates and silica and less commonly 

alumina and ferric oxide.

Adsorption, the property colloids have of taking other substances 

out of solution or suspension, may in most cases be represented by 

exact equations.

The adsorption of a dye by clays supplies an approximate measure 

of plasticity.

The plasticity, taken as the product of the deformability by the

CxB force resisting deformation, reduces to the expression - , where

A.

C is the measure of colloids present, B is the cast air shrinkage, and A 

is the Jackson-Purdy surface factor.

The dye test supplies a measure of the efficiency of grinding in 

increasing the plasticity of a fire clay. Questions that call for further 

study are the possible finding of a better dye than malachite green, 

the* disturbing influence of minerals and salts in clays, and the formulation of a field test for plasticity.

REFERENCES.

1. Schloesing, Th., The constitution of the clays: Compt. Rend., vol. 79, 1874, 

pp. 376-380, 473-477.

2. Van Bemmelen, J. M., Compounds of several solid dioxide hydrates with acids, 

salta, and alkalies: Jour, prakt, Chemie, 2d ser., vol. 23, 1881, pp. 324-349, 379-395.

3. Mayer, Adolph, Forschungen auf dem Gebiete de'r Agricultur Physik, vol. 3, pt. 2.

4. U. S. Dept. Agr., Bur. Soils, Bull. 24, 1904, p. 9.

5. Davis, Charles A., Peat: Eighth Ann. Kept. Geol. Survey Michigan, 1906, pp. 

320, 325.

6. Schreiner and Reed, Certain organic constituents of soils in relation to soil fertility: U. S. Dept. Agr., Bur. Soils, Bull. 47, 1907, p. 10.

7. Methods of analysis; humus in soil: XL S. Dept. Agr., Bur. Chem.,Bull. 

107, 1907, p. 19.

8. Acheson, E. G., Egyptianized clay: Trans. Am. Ceram. Soc., vol. 6, 1904, p. 31.

9. Grout, F. F., West Virginia Geol. Survey, vol. 3, 1906, p. 47-.

10. Hardy, W. B., On the mechanism of gelation in reversible colloidal systems: 

Proc. Roy. Soc., vol. 66, 1899, pp. 95-109. 

lOa. Idem, p. 112.

11. Cushman, Allerton S., The colloid theory of plasticity: Trans. Am. Ceram. Soc., 

vol. 6, pp. 65-78.

12. Wiley, Harvey W., Principles and practice of agricultural analysis, vol. 1, p. 120.

13.. Eichorn, , Landw. Centralbl., vol. 11, p. 169.

14. Way, J. T., Jour. Royal Agr. Soc., vol. 11, 1850.

15. Way, J. T., On deposits of soluble or gelatinous silica in the lower beds of the 

chalk formation: Jour. Chem. Soc., vol. 6, 1854, pp. 102-106.

16. Van Bemmelen, J. M., The absorptive power of soils: Jahresber., 1888, pt. 2, 

p. 2737.
60 o COLLOID MATTER OF CLAY.

17. Warington, Robert, jr., On the part taken by oxide of iron and alumina in the 

absorptive action of soils: Jour. Chem. Soc., 2d ser., vol. 6, 1868, pp. 1-19.

18. Cameron, F. K., and Bell, James M., The mineral constituents of the soil solution: U. S. Dept. Agr., Bur. Soils, Bull. 30, 1905, p. 22.

19. Idem, p. 23.

20. Weber, Carl Otto, The chemistry of india rubber, London, Charles Griffin & Co. 

(Limited), 1902, p. 79.

21. Van Bemmelen, J: M., The absorption of water in the colloids, especially in the 

gel of silicic acid: Zeitschr. anorg. Chemie, vol. 13, 1896, pp. 232-357.

22. The Leuchter process of reducing or enlarging models: The Brass World, 

vol. 3, 1907, p. 371.

23. Hillebrand, William Francis, Some principles and methods of rock analysis: 

Bull. U. S. Geol. Survey No. 176, 1900, pp. 52-53.

24. Whitney, W. R., and Ober, J. E., The precipitation of colloids by electrolytes: 

Jour. Am. Chem. Soc., vol. 23, 1901, p. 844.

25. Coehn, , [Electric charges]: Wied. Ann., vol. 64, 1898, p. 217.

26. Bredig, , [Similarity of action of colloidal platinum and organic ferments]: 

Chem. Zeitung, vol. 24, 1900, p. 895.

27. Whitney, W. R., Colloids: Trans. Am. Electrochem. Soc., vol. 7, 1905, pp. 225- 

233.

28. Bredig, G., Zeitschr. angew. Ghemie, 1898, p. 951.

29. Mayer, Schaeffer, and Terroine, Influence de la reaction du milieu sur la grandeur des granules colloidaux: Compt. Rend., vol. 145, 1907, pp. 918-920.

30. Spring, -^ , Recueil trav. chim. Pays-Bas, vol. 19, 1900, p. 204.

31. Lottermoser, A., The formation process of hydrosols and hydrogels: Zeitschr. 

phys. Chemie, vol. 60, 1907, p. 451. l!

32. Picton and Linder, Solution and pseudosolution: Jour. Chem. Soc., vol. 61, 

1892, p. 171.

33. Schulze, , Jour, prakt. Chemie, vol. 25, 1882, pp. 431-452.

34. Proctor, H. R., Colloidal chemistry: Chem. News, vol. 98, 1908, pp. 152, 167, 

175.

35. Dubois, W. L., The fuller's earth test for caramel in vinegar: Jour. Am. Chem. 

Soc., vol. 29, 1907, p. 75. Also, U. S. Dept. Agr., Bur. Chem., Bull. 105,1907, p. 23. 

, 36. Teague, Oscar, and Buxton, B. H., The precipitation of aniline dyes: Zeitschr. 

phys. Chemie, vol. 60,1907, p. 469.

37. Cushman, Allerton S., Rock decomposition and clay formation in the laboratory: 

Trans. Am. Ceram. Soc., vol. 8, 1906, p. 180.

38. Cushman, Allerton S., On the cause of the cementing value of rock powders 

and the plasticity of clays: Jour. Am. Chem. Soc., vol. 25, 1903, pp. 451-468.

39. Sullivan, Eugene C., The interaction between minerals and water solutions: 

Bull. TJ. S. Geol. Survey No. 312, 1907.

40. Rohland, Paul, The semipermeability of clays: Sprechsaal, vol. 39,1906, p. 129.

41. Stover, Edward C., Bacteria in clay mixtures: Trans. Am. Ceram. Soc., vol. 5, 

1903, pp. 358-361.

42. Picton and Linder, Solution and pseudosolution: Jour. Chem. Soc., vol. 71, 

1897, pp. 568-573.

43. Rohland, P., The means for altering the amount of plasticity of clays: Sprechsaal, vol. 39, 1906, pp. 1371-1372.

44. Clarke, F. W., Data of geochemistry: Bull. U. S. Geol. Survey No. 330, 1908.

45. Kuzel, Hans, Process of manufacturing incandescent metal filaments: German 

patent 194348, July 25, 1905.

46. Clarke, F. W., Data of geochemistry: Bull. U. S. Geol. Survey No. 330, 1908, 

p. 423.
EEFEEENOES. 61

47. Mellor, J. W., Green, S. A., and Baugh, T., Studies on clay slip, I: Trans. 

English Ceram. Soc., vol. 6, pp. 161-170.

48. Binns, Charles F., The function of boron in the glaze formula: Trans. Am. 

Ceram. Soc., vol. 10, pp. 158-174.

49. Bleininger, A. V., The viscosity of clay slips: Trans. Am. Ceram.. Soc., vol. 10, 

pp. 389-395.

50. Henry, Charles, Spectophotome'trie, viscosime'trie, et signes electriques des 

solutions: Compt. Rend., vol. 145, 1907, p. 1415.

51. Simonis, Max, Physical definition of clay and nonplastics: Sprechsaal, vol. 38, 

1905, pp. 1625-1626.

52. Simonis, Max, The tenacity of clay slips: Sprechsaal, vol. 38, 1905, p. 597.

53. Simonis, Max, Zettlitz clay and alkali: Sprechsaal, vol. 38, 1905, p. 881.

54. Van Bemmelen, J. M., The nature of colloids and their water content: Chem. 

Centralbl., 1888, p. 1255.

55. Patten and Gallagher, Absorption of vapors and gases by soils: U. S. Dept. 

Agr., Bur. Soils, Bull. 51, 1908. ~

56. Day and Alien, Isomorphism and thermal properties of the feldspars: Am. 

Jour. Sci., 4th ser., vol. 19,1905, p. 127.

57. Von Dobeneck, , Porsch. Geb. Agr.-Phys., vol. 15, 1892, p. 201.

58. Briggs and McLane, The moisture equivalent of soils: U. S. Dept. Agr., Bur. 

Soils, Bull. 45, 1907.

59. Hofmeister, F., The function of dissolved substances in processes of swelling: 

Zeitschr. phys. Chemie, vol. 7, 1891, p. 432. Arch. exp. Path. u. Pharm., vol. 28, 

1891, pp. 210-238.

60. Van Bemmelen, J. M., Zeitschr. anorg. Chemie, vol. 23, 1900, pp. 321-372.

61. Walker, James, and Appleyard, James R., Absorption of dilute acids by silk: 

Jour. Chem. Soc,, vol. 69, 1896, p. 1334.

62. Teague, Oscar, and Buxton, B. H., The Mutual coagulation of colloids: Zeitschr. 

phys. Chemie, vol. 62, 1908, pp. 287-307.

63. Van Bemmelen, J. M., The formation of gels and their structure: Zeitschr. 

anorg. Chemie, vol. 18, 1898, pp. 14-36.

64. Des Bancels, J. Larguier, Colloid reactions and the mechanism of mordenting: 

Rev. g6n. mat. color., vol.'12, pp. 193-201.

65. Lottermoser, A., The preparation of colloidal elements: Zeitschr. angew. Chemie, 

vol. 21, 1908, pp. 632-639.

66. Bodeker, , Jour. Landwirtschaft, vol. 3, 1859, p. 48.

67. Wolff, , Landw. Zeitung Nord und Mitteldeutschland, Nos. 32 and 33,1859.

68. Wood, J. T., The compounds of gelatin and tannin: Jour. Soc. Chem. Ind., 

vol. 27, 1908, pp. 384-387.

69. Cameron, F. K., and Patten, H. E., The distribution of solute between water 

and soil.

70. Hirsch, H., Behavior of clay in salt solutions: Tonindustrie-Zeitung, vol. 28, 

1904, p. 491.

71. Lottermoser, A., and Rothe, A., Adsorption of silver nitrate and potassium 

iodide by amorphous silver iodide: Zeitschr. phys. Chemie, vol. 62,1908, pp. 359-383.

72. Simonis, Max, The settling 'of casting bodies and its prevention: Sprechsaal, 

vol. 39, No. 5, 1906, p. 169.

73. Simonis, Max, Further contributions on the relations of clays and nonplastics 

toward electrolytes: Sprechsaal, vol. 39, 1906, pp. 1167, 1184.

74. Schultz and Julius: Organic colouring matters. 3d ed.

75. Pelet-Jolivet, L., and Wild, A., Dyestuffs in solution: Zeitschr. Chemie u. Ind. 

der Kolloide, vol. 3, 1908, pp. 174-177.

76. Hober, R., and Chassin, S., Dyes as colloids: Zeitschr. Chemie u. Ind. der 

Kolloide, vol. 3, 1908, pp. 76-80,
62 COLLOID MATTER OF CLAY.

77. Jackson, W., Trans. English Ceram. Soc., vol. 3, p. 16. Also Ceramic calculations.

78. Purdy, Ross C., The calculation of the comparative fineness of ground materials 

by means of a surface factor: Trans. Am. Ceram. Soc., vol. 7, 1905, p. 441.

79. Ashley, Harrison Everett, The testing of the raw materials of a whiteware pottery: Trans. Am. Ceram. Soc., vol. 9, 1907.

80. Zschokke, B., Investigations on the plasticity of clays: Bull. Soc. d'Encouragement, vol. 103, 1902, pp. 619-658. Baumaterialienkunde, 1902, Nos. 24, 25-26; 

1903, Nos. 1-2, 3-4, 5-6. Tonindustrie-Zeitung, vol. 29, 1905, p. 1657.

81. Seger, Hermann August, Collected writings, translated by members of the 

American Ceramic Society, p. 357.

82. Ashley, Harrison Everett, Pottery plaster: Trans. Am. Ceram. Soc., vol. 10, 

1908, pp. 76-90.

83. Purdy, Ross C., and Moore, J. K., Pyrophysical and chemical behavior of clay: 

Trans. Am. Ceram. Soc., vol. 9, 1907, p. 222.

84. Julien, A. A., On the geological action of the humus acids: Proc. Am. Assoc. 

Adv. Sci., 1879, pp. 311-410.

85. Borntrager, H., Zeitschr. anal. Chemie, vol. 39,1900, p. 694, vol. 40,1901, p. 639.

86. Graham, Thomas, Liquid diffusion applied to analysis: Philos. Trans. Royal 

Soc., 1861, pp. 183-224.

87. Forster, F., Die chernische Industrie, vol. 28, No. 24.
INDEX.

A. Page.

Absorption, discussion of.................... 27-31

relation of, to plasticity.................. 28

to temperature...................... 27-28

Acheson, E. G.,011 added colloids............ 12

Adsorption, destruction of, by heat.......... 9

discussion of............................. 31-42

estimation of colloids by................. 43-54

investigation of.......................... 7

apparatus for, plate showing......... .40

theory of................................ 31

Ageing, eflect of............................ 14

Alcohol, effect of, on clay.................... 24

Alien and Day, on absorption by feldspar... 28 

Aluminum hydroxide, adsorption by........ 10

Appleyard, J. K., and Walker, J., on adsorption......................... 31

on partition of solutes.................... 32-33

Ashley, II. E., work of....................... G

B.

Barium chloride, adsorption of, by Klingenberg clay........................ 37-38

chart showing........................... 39

Baugh, T., Mellor, J. W., and Green, S. A.,

on clay slips..................... 23-26

Bell, J. M., and Cameron, F. K., on silica

coatings......................... 10

Bibliography................................ 59-62

Binns, C. F., on action of boron............. 24

Bleininger, A. V., on viscosity of clays....... 20,43

preface by............................... 5-6

Blunging, difficulties in...................... 12-13

Borntrilger, H., on peats .................... 11

Bredig, G., on formation of soils............. 17

Briggs and McLanc, on absorption by soils.. 29 

Brilliant green, adsorption tests of........... 43-45

comparison of, with malachite green..... 45

Butschli, on structure of gels................ 32

Buxton, B. H., and Teague, 0., on dyes..... 30

C.

Cameron, F. K., and Bell, J. M., on silica

coatings......................... 10

Cameron, F. K., and Patten, H. E., on adsorption ................................... 34-37

Charcoal, absorption and adsorption in...... 16

nature of................................. 16

Chassin, S., and Hober, R., on brilliant green. 45 

Olarke, F. W.,on origin ofsilica gel.......... 10

Clays, absorption by. See Absorption. Page, 

adsorption tests of....................... 43-53

aging and drying of........'.............. 12-14

constituents of,"absorptive powers of.... 28-29

definition of............................ 7-8,59

effect of sodium carbonate on............ 22-23

further study of......................... 58,59

plasticity of. See Plasticity.

properties of.. '. .......................... 48-53

chart showing....................... 52

viscosity of.............................. 20-21

Clay gels, stability of......................... 19-20

volume of............................... 29-30

Clay sols, stability of........................ 19-20

Coagulation, laws of......................... 27

nature of................................ 15

Coehn, , on electrostatic charges....... 17-18

Colloids, addition of, to clay, eflect of........ 12

coating by................................ 7-8

definition of............................. 7,12

forms of.................;............... 14-20

mixtures of........................'...... 31

properties of............................. 20-42

sources of.............................. 9-12,59

Colloids, organic, nature of.................. 10-11

' viscosity of................ '.............. 24

Color comparisons, apparatus for, plate showing .............................. 46

Cushman, A. S., on plasticity............... 14

on temperature effects................... 27

on water in clay......................... 13

on Way's experiments................... 9

D. 

Davis, C. A., on peats....................... 11

Day and Alien, on absorption by feldspar... 28 

Definitions, statement of.................... 7-8

Deflocculation, extent of, in salt solutions.... 29-30

nature of................................ 15

Des Bancels, J. L., on colloid mixtures...... 31

Drying, effects of............................ 12-14

Dubois, W. L., on fuller's earth and vinegar. 57

E. 

Ebonite, nature of........................*... . 15

Eichhorn, , on adsorption of zeolites... 9 

Electrolytes, action of....................... 22-27

F.

Feldspar, absorption powers of.............. 28

aging of................................. 14

Ferric hydroxide, adsorption by............. 10

63
64 INDEX.

Page. 

Fire clays, grinding of, effect of.............. 56

weathering of............................. 13

Forster, F., on nature of adsorption......... 23

Fuller's earth, effect of, on vinegar........... 57

G.

Gallagher, -, and Patten, H. E., on absorption by quartz.............. 28

Gates, W. D., on added colloids............. 12

Gelatine, adsorption of tannin by............ 33-34

adsorption of tannin by, chart showing.. 34 

Gels, cellular structure of.................... 31-32

formation of............................. 18-19

nature of................................. 14

partition of solute between liquids and.. 32-42 

salts in, distribution of.................. 30

solution of water by.. ................... 30

Gentian violet, adsorption of, by Hagerstown

loam............................ 34-36

adsorption of, by Hagerstown loam, chart

showing......................... 35

by quartz flour...................... 36-37

chart showing................... 37

Geological Survey, investigations by......... 5-6

Graham, Thomas, nomenclature by......... 15

Green, S. A., Baugh, T., and Mellor, J. W., on

clay slips........................ 23-26

Green. See Malachite green; Brilliant green. 

Grimsley, G. P., on absorption and plasticity.............................. 28

Grinding, effect of, on plasticity............. 56,59

Grout, F. F., on drying clays................ 12,28

on plasticity............................. 53

H.

Hagerstown loam, adsorption of gentian violet by........................... 34-36

adsorption of gentian violet by, chart

showing......................... '35

Hardy, W. B., on action of electrolytes...... 22

on coagulation........................... 2.7

on drying under pressure................ 13

on setting............................... 15

on structure of gelatine.................. 31

Henry, Charles, on viscosity................. 20

Hillebrand, W. F., on dehydration of silica.. 17 

Hirsch, H., on adsorption................ 37-38,43

Hober, E.., and Chassin, S., on brilliant green. 45

Hofmeister, F., on swelling of glue........... 30

Hurnic acid, nature of....................... 9-10

Humus, absorption by...................... 28

adsorption by........................... 10

I.

India rubber, nature of. 15

J.

Jackson, W., on clay particles............... 50-51

James, J. H., on adsorption tests............ 44

Julien, A. A., onhumic acid................. 11

Julius and Schultz, onformulseofgreens..... 45

K.

Kaolin, fractionation of. 

nature of...........

Page. 

Klingenberg clay, adsorption of barium chloride by .......................... 37-38

adsorption of barium chloride by, chart

showing ......................... 39

Kuzel, Hans, on plasticity. .................. 22

L.

Linder and Picton, on ionic reactions. ......: 18

Liquids, partition of solute between gels and. 32-42

Liquids, immiscible, partition between. ..... 32

Lottermoser, A., on ionic reactions. ......... 18

on structure of gels ...................... 31

Lottermoser, A., and Rothe, A., on adsorption ............................. 38-41

M.

McLane and Briggs, on absorption by soils. . 29 

Malachite green, adsorption of, by Tennessee

ball clay. ..................... 41-42, 50

adsorption of, by Tennessee ball clay,

charts showing .................. 42, 50

tests of .............................. 40-50

applications of. ............... 54, 56-58

Mayer, Adolph, on settling of clay. .......... 19

Mayer, Schaeffer, and Terroine, on ionic reactions. ......................... 18

Mellor, J. W., Green, S. A., and Baugh, T.,

on clay slips. . ................... 23-26

Moore, J. K., and Purely, R. C., on plasticity. '58

N.

Nagelli, 

Nernst,

, on structure of gels. . ......... 32

, on partition between immiscible liquids ..;.................. 32

O.

Ober, J. E., and Whitney, W. R., on electrostatic charges. ................... 17-18

on ionic reactions. ....................... 18

P.

Paris whites, malachite green, tests of....... 57-58

Patten, H. E., and Cameron, F. K., on adsorption ......................... 34-37

Patten, H. E., and Gallaghcr, , on absorption by quartz............... 28

Peats, adsorption by........................ 10-11

analyses of............................... 11

Pectinization, use of term.................... 15

Pectisation, use of term...................... 15

Pcctoid, use of term......................... 15

Pelet-Jolivet, L., and Wild, A., on malachite

green............................ 45

Peptinization, use of term................... 15

Picric acid, partition of dye between silk and. 32-33 

Picton and Linder, on ionic reactions........ 18

Plasticity, causes of.......................... 21-22

determination of...................... 42-55,59

by malachite green.................. 54

loss of, by drying........................ 12-14

nature of................................ 8

relation of, to absorption................. 28

to colloids........................... 42-43
INDEX. 65

Page.

Potassium iodide, adsorption of, by silver

iodide........................... 39-41

adsorption of, by silver iodide", chart

showing......................... 41

Pressure, drying under, effect of............. 13

Proctor, R. H., on inorganic sols............. 20

Protection colloids, nature of................ 20

Purdy, R. C., on clay particles............... 50-51

Purdy, R. C., and Moore, J. K., on plasticity. 58

Quartz, absorption by....................... 28

Quartz flour, adsorption of gentian violet by.. 36-37 

adsorption of gentian violet by, chart

showing......................... 37

R. 

References, list of............................ 59-62

Ries, H., on plasticity and absorption....... 28

Rohland, Paul, on OH ions.................. 14,21

on permeability of clays................. 13

on plasticity of clays..................... 21-22

Rotho, A., and Lottermoser, A., on adsorption............................. 38-41

Salt solutions, volume of clay gels in......... 29-30

Salts, distribution of, in gels................. 30-31

Schaffer, Mayor, and Terroine, on ionic reactions .......................... 18

Schioesing, Th., isolation of colloids by...... 8-9

on absorption by clay.................... 29

Schultz and Julius, on formula? of greens..... 45

Seger, H. A., on plasticity.........'.......... 58

Set gels, examples of......................... 15-17

Setting, nature of............................ 15

Silica, dehydration of........................ 16-17

Silica, gelatinous, adsorption by............. 9-10

Silicates, hydrated, adsorption by........... 9

Silk, partition of dye between picric acid and. 32-33 

Silver iodide, adsorption of potassium iodide

by............................... 39-41

adsorption of potassium iodide by, chart

showing......................... 41

adsorption of silver nitrate by........... 38-39

Simonis, Max, on viscosity of clays........ 20-21,43

Sodium carbonate, action of, on clay......... 22-24

Sols, formation of............................ 17-18

nature of................................ 14

Stover, E. C., on aging of clay............... 14

Structural materials, investigation of........ 5

Sullivan, E. C., on interaction of minerals and 

solutions..................

T.

Page.

22.

Tannin, adsorption of, by gelatine........... 33-34'

, adsorption of, by gelatine, chart showing. 34 

Teague, 0., and Buxton, B. H., on dyes..... 30

Temperature, effect of, on absorption........ 27-28

Tennessee ball clay, adsorption of malachite

green by......................... 41-42

adsorption of malachite green by, charts

showing......................... 42,50

Terrome, Mayor, and Schaffer, on ionic re- .

actions.......................... 18'.

Van Bemmelen, J. M., on settling of clay.... 19

on silica gel.............................. 9-10'

on solution in gels....................... 30

on structure of gels...................... 31

on temperature effects................... 27-28-

Vinegar, effect of fuller's earth on............ 57

Viscosity, discussion of...................... 20-27

Von Dobeneck,, on absorption by humus. 28

Walker, J., and Appleyard, J. R., on adsorption............................. 31

on partition of solutes................... 32-33

Warington, Robert, jr., on ferric, and aluminum hydroxide.................. 10

Water, quality of, in tests................ 43,45-40.

Way, J. T., experiments of, on seat of adsorp-'

tive powers..................... 9

Weathering, effect of, on fire clays........... 13-14

Weber, C. 0., on pectisation................. 15

on solution in gels....................... 30

on structure of gels................. T.... 31-32

Weelans, Charles, on addition of colloids..... 12

Whitney, W. R., on formation of sols....... 17

Whitney, W. R., and Ober, J. E., on electrostatic charges................... 17-18-

on ionic reactions........................ 18

Wild, A., and Pelet-Jolivet, L., on malachite

green............................ 45

 Wiley, H. W., on Way's experiments....... 9

Wood, J. T., on adsorption of tannin........ 33

Zschokke, B., on plasticity. 53.

o

83865 Bull. 388 09-