SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1916. 

EVAPORATION OF BRINE FROM SEARLES LAKE, CALIFORNIA. 

By w. B. HICKS. 

INTRODUCTION. 

The bed of crystalline salts known as Searles 

Lake, 

1 in southeastern California, contains the 

most valuable potash-bearing brine known in 

the United States. This salt body has an exposed surface area estimated at 11 or 12 

square miles and an average depth of about 70 

feet. For the most part it is firm and compact 

enough to support a wagon and team even 

during u~usually wet seasons, when it is' sometimes flooded with a thin sheet of water that 

dissolves the surface salts to a slight extent. 

The deposit contains in the interstices between 

the salt crystals a saturated brine the volume 

of which is estimated to be more than 25 per 

cent of that of the entire saline 1nass.2 · 

The brine contained in this so-called lake carries. about 2.1 per cent of potassium, or the 

equivalent of about 4 per cent of potassium 

chloride. It is composed chiefly of the · chlorides, sulphates, carbonates, and borates of 

sodium and potassium. It is essentially different from the brines used in the manufacture of 

potash in Germany, and qn that account a diferent process is required for the extraction of 

the potassium from it. Economical methods 

for extracting the commercial salts, including 

potash, from this brine are now eagerly sought 

b.ut none yet tried have been proved commer~ Cially successful. Fractional evaporation and 

crystallization form an essential part of the 

methods which appear to give the most prmnise 

an~ detailed knowl~dge ?f the effect of evapo~ ~atwn on th~se ?rines Is therefore of special 

Interest. It Is difficult to predict from theoretical considerations what will be the effect of 

evaporation on the various constituents of so 

1 !lor _a detailed description of this so-called lake, see Gale, H. s., Sal~es m the Owens, Searles, and Panamint basins, southeastern Califo:ma: U. S. Geol. Survey Bull. 580, pp. 265-317, 1914 (Bull. 580-L). 

Gale, H. S., op. cit., p . 274. 

complicated a system as that represented by 

the brine of Searles Lake. All the necessary 

data for an adequate discussion of the subject 

have not been worked out, and direct experimental data on the evaporation of brines of 

shnilar composition are meager. 

In a recent Survey report by the writer 3 

some results have been presented which were 

intended to throw further light on conditions 

governing the deposition of salts from solution 

and thus to aid in solving the problem of extracting potash from American natural brines. 

Solutions prepared in the laboratorv were 

en:ployed in the experiments. Simple salt 

~:rnxtu~es were used at first, and by gradually 

n1cluding other salts more complex brines were 

obtained and subjected to evaporation, although none were strictly comparable with 

those found in nature. It was not possible to 

do more than a small part of the experimental 

work contemplated at the time, and the results 

were presented as a first chapter in the studv of 

the general subject of potash brines. Som~ of 

the ~ata obtained are significant and suggest 

the Importance of a more thorough investigation of the subject. 

. As a continuation of the experiments just mentiOned, the natural brine from Searles Lake, Cal., 

has been subjected to fractional evaporation 

and crystallization, and the effect determined 

by analyzing the crystals that separated from 

the solution. The results are presented in the 

present paper as a second contribution in the 

study of potash brines. It is hoped that they 

may be of value in developing an economical 

process for the extraction of the commercial 

salts from America.n brines and also in studying 

those general geologic problems with which the 

deposition of salts from solution is connected. 

1 Hicks, W. B., Evaporation of potash brines: U. S. Geol. Survey 

Prof. Paper 95, pp. 64-72, 1915 (Prof. Paper 95-E). . 

1 
2 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1916. 

Because of the acute condition in the potash 

situation and the eagerness with which economical methods for the extraction of potash from 

brines are sought, it seems desirable to give to 

the public as rapidly as possible all information bearing on the subject. This has led to 

the publication of this paper at the present 

time, although only a small part of the experimental work planned has been done. The results here set forth may be supplemented later. 

THE BRINE. 

Six samples of brine from Searles Lake were 

collected May 14, 1912, by R. B. Dole, and 

were preserved in sealed glass bottles. Each 

sample represented about equal quantities of 

brine from several wells as indicated below: 

No. 

1 

2 

3 

4 

5 

6 

Samples of brine from Searles Lake, Cal. 

Source. Location.a Depth. 

Feet. 

rrine at surface .... SW. t sec. 15 ... 2 

WellS. E. V ....... ..... do ......... 20 

WellS. E. IV ...... NE. i sec. 23 ... 20 

~ell B •........... SE. i sec. 15 ... 30 

ell A ............ NE. i sec. 22 ... 25 

WellS. E. VI. ..... Center sec. 22 .. 30 

~ell E. 6 ........... SW. l sec. 22 ... (?) 

;vell s. E. 6 ........ Center sec. 23 .. (?) 

;vell E. 8 ........... SW. i sec. 23 ... Deep. 

Well F ............. NE. t sec. 26 ... Shallow. 

~ellS. E. 3 ........ NW. -1 sec. 25 .. Deep. 

ellS. E. 4 ........ NE. t sec. 25 .. Very deep. 

ellS. E. 8 ........ SE. i sec. 25 ... Very deep. 

ell E. 9 ........... NW. f sec. 30b. Deep. 

Well E. 10 .......... NE. f sec. 31 b. 10 

Well E. 11 .......... SE. i sec. 36 ... ·Very deep. 

Well E. 13 .......... SW. t sec. 36 ... Deepest. 

WellS. E. 2 ........ SE. t sec. 26 ... Deep. 

WellS. E. I. ....... SW. i sec. 27 .. . Very deep. 

Well N ............. NW. ±sec. 31 b. 6 

Well T ............. SW. i sec. 28 ... Deep. 

Well U ............. NW. t sec. 28 .. Very deep. 

WellS. E. I. ....... SW. t sec. 27 .. Deep. 

a All in T. 25 S., R. 43 E., except as otherwise indicated. bIn T. 25 S., R. 44 E. 

In October, 1914, the writer prepared a 

composite sample of brine consisting of 1 liter 

.from each of the six bottles described above. 

The brine was filtered from the suspended 

matter, thoroughly mixed, and preserved in a 

large bottle closed with a rubber stopper. 

When this solution was allowed to stand 

crystals were slowly deposited from it. These 

crystals would not redissolve readily on warming and shaking. In April, 1915, the brine was 

filtered at 22.5° C., and both the crystals and 

the solution were analyzed. The crystals, 

collected on a Monroe crucible and dried by 

suction, weighed 18 grams. Microscopic examination by W. T. Schaller showed that the 

crystals were composed largely of a mixture of 

sodium chloride and borax. This was confirmed 

by analysis, which gave the following results: 

Analysis of crystals deposited by composite sample of brine 

from Searles Lake, Cal. 

Na ......................... ·.................... 21. 26 

K............................................. .29 

Cl.... .... ......... ............. .... .. . . . . . . . . . . . . . 22.25 

so4. ......................................... .. . 49 

B40 7........................................... 22.51 

C03 •••• ••••••.••••••••••••••••••••••••••••••••••• • 40 

H20 (by difference).... . . . . . . . . . . . . . . . . . . . . . . . . . . 32. 80 

100.00 

Accordingly the 18 grams of crystals deposited from 61iters (7.763 grams) of brine contained only 4 grams of borate and like quantities of both sodium and chlorine. Therefore 

the quantity of each of these three constituents 

deposited represents only 0.05 per cent of the 

original solution, which is probably about the 

limit of error in the analysis and does not appreciably affect the accuracy of the analysis 

of the original brine. 

The filtered brine which was used in the 

present investigation had a straw-yellow color 

and a cloudy appearance. The composition is 

given below along with that of other brines 

from Searles Lake for comparison. 

Composition of brines from Searles Lake, Cal. 

A B I c 

K ............................ 6. 17 6.34 6.07 

Na .......................... 33.66 33.80 33. 61 

CL ........................... 36.36 37.04 37. 10 

so4 .. ····················· .. 12.86 13. 00 12.99 

COaa· .. ···················· 7.72 7. 24· 6.71 

B407 .. ······················ 3.23 2.50 3.01 

Other constituents (Li, Mg, 

Al20 3, Fe20 3, Si02, Br, I, 

P0 (?) . 08 . 51 4, As20 3, etc.) ........... 

100.00 100.00 100.00 

Total salts by summation .... . 34.04 33.91 b 32.90 

Specific gravity ............. . {1.2938 1.2974 ... .. ..... 

at23°C at(?) 

a This represents the combined carbonates and bicarbonates. The amount of HC03 in the original brine found by Ross was 0.55 per cent. b Approximate. The specific gravity of this sample was not reported, and the original analysis was stated in grams per llter. 

A. Composite sample of b~ine prepared by_ the ":rite.r as described above and used m the present mvest1gat10n. 

W. B. Hicks, analyst. 

B. Average of six analyses of brines from wells in 

Searles Lake. Walton Van Winkle, analyst. Gale, H. S., 

op. cit., p. 277. . C. Analysis of brine from Searles Lake. W. H. Ross, 

analyst. Gale, H. S., op. cit., p. 277. 

NOTE. B and C have been rec.alculated to 100 per cent. 
EVAPORATION OF BRINE FROM SEARLES LAKE, CAL. 3 

METHODS. 

METHOD OF EXPERIMENTATION. 

In conducting the experiments 1,000 grams 

of brine continuously stirred in a beaker was 

evaporated on the steam bath at about 78° C. 

to approximately two-thirds of its original volume, and the hot solution was then separated 

from the depositedcrystals by filtration through 

a paper filter supported by a platinum cone and 

contained in a funnel surrounded by a steam coil 

of brass to maintain the temperature of the 

steam bath during filtration. As much as possible of the adhering mother liquor was removed 

by strong suction, and the main bulk of the 

crystals were transferred to a small tared flask 

and weighed. The remainder of the crystals, 

which adhered to the beaker, filter paper, etc., 

were washed into a tared platinum dish, evaporated to dryness, and weighed. The combined 

weights so obtained represent the amount of 

salts deposited during the first stage of the 

evaporation. The two portions of the crystals were then combined and thoroughly mixed. 

The sample so prepared was designated 1 A 

and was preserved in a paraffin-sealed flask for 

analysis. 

The filtrate, well covered to prevent evaporation, was placed in a bath having a constant 

temperature of 30° C. (±0.05°) and was stirred 

vigorously until the temperature of the solution 

adjusted itself to that of the thermostat and for 

an hour or so thereafter. The deposited crystals were allowed to settle and were then separated from the solution by filtration through 

paper at room temperature (approximately 

30° C.) and dried as much as possible by strong 

suction. The main bulk of the crystals were 

then transferred to a small tared flask and 

weighed. Those adhering to the beaker, filter 

paper, etc., were washed into a weighed platinum 

dish, evaporated to dryness, and weighed. The 

combined weights so obtained represent the 

amount of salts deposited during cooling from 

78° C. to 30° C. in the first stage of the evaporation. The two portions of the crystals were 

then combined and thoroughly mixed. The 

sample so prepared was designated 1 B and 

was preserved in a paraffin-sealed flask for 

analysis. 

The filtrate obtained in the last operation 

from sample 1 B was weighed: and its specific 

gravity was determined by means of the 

Westphal balance. The solution adhering to 

the funnel, specific-gravity cylinder, etc., was 

washed into a platinum dish, evaporated to 

dryness, and weighed. This weight multiplied 

by 3 and added to that of the main portion of 

the solution gave the corrected weight of the 

filtrate. The residue was dissolved in as little 

water as possible and added to the main portion of the solution. The combined solution 

was returned to the steam bath for further concentration. 

The process just described-fractional evaporation with consequent removal of the crystals 

deposited during evaporation and also those 

separated during cooling-was repeated at 

intervals until only a small portion of the solution remained. This produced fourteen fractions of crystals, representing seven stages in 

the evaporation. Each fraction was analyzed, 

as was also the final mother liquor, according 

to the methods described below. 

METHODS OF ANALYSIS. 

Weighed samples of the crystals were dissolved in water and diluted to definite volume 

(weighed samples of the brines were simply 

diluted to definite volume), and aliquots each 

containing roughly 0.5 gram of solids were 

taken for analvsis. The determinations were 

made in duplicate, and practically . all the 

figures given in the tables (pp. 6-7) are averages of two closely agreeing results. Common 

methods of analysis were usually employed, 

· but short cuts were taken wherever possible, 

and a brief description of the procedure therefore seems advisable. The sulphate radicle 

was precipitated and weighed as barium sulphate, and potassium was estimated by the 

modified chlorplatinate method. 1 After the 

sample had been acidified with hydrochloric 

acid and the borates removed by repeated 

evaporation with methyl alcohol and hydrochloric acid, sodium was determined by weighing the combined bases as sulphates (after 

igniting to constant weight with ammonium 

carbonate) and subtracting the potassium sulphate. Chlorine was determined by titration 

with N /10 silver nitrate after neutralizing the 

solution with nitric acid, and the borate radicle 

was estimated by titration with N/10 sodium 

hydroxide in the presence of mannite. and 

1 Hicks, W. B., A rapid modified chlorplatinate method for the estimation of potassium: Jour. Ind. Eng. Chern., vol. 5, pp. 650-653, 1913. 
4 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1916. 

phenolphthalein. The carbonate radicle was 

determined by titrating with N /10 hydrochloric acid in the presence of methyl orange and 

subtracting the borate equivalent, and therefore the results include both carbonates and 

·bicarbonates. The latter were not evaluated. 

Other constituents that have been reported in 

traces or in very small amount in the brine 

were disregarded. 

RESULTS. 

SUMMARY OF STAGES IN THE EVAPORATION. 

By conducting the experiments according to 

the methods above described, fourteen fractions 

grams additional were deposited, which were marked 1 B. 

The filtrate that was separated from the crystals had a 

specific gravity of 1.278 at 30° C. and weighed 750 grams. 

Second stage.-The 750 grams of solution remaining from 

the first operation was concentrated on the steam bath to 

about two-thirds of the original volume, and 28.93 grams 

of solids were deposited. The crystals so obtained were 

designated 2 A. When the filtrate was cooled from 78° 

to 30° C., 14.30 grams of solids, marked 2 B, were deposited. The filtrate remaining after the separation of 

the crystals had a specific gravity of 1.282 at 30° C. and 

weighed 617 grams. 

Third stage.-The 617 grams of solution obtained in the 

second stage was concentrated on the steam bath at 78° C. 

to about 500 cubic centimeters. During this treatment 

21.52 grams of salts, designated 3 A, separated from the 

hot solution. The solution was then cooled from 78° to 

IOOr----r---r---r---r---.----,r------r........,--r---r----. 

30° C., when an additional deposition 

of 13.56 grams occurred. This lot was ~ 

~~/ 

:::=:=:=:=::/~=:/::;/=:}: 70t-!-~--+-T-/-+-____-;--+-__;---+------:~/--+ · /--1++/1..--.-1 

designated 3 B. The filtrate that was 

separated from the crystals had a 

specific gravity of 1.295 at 30° C. and 

weighed 502 grams. 

Fourth stage.-The filtrate from the 

third stage, amounting to 502 grams, 

was evaporated to about two-thirds 

its volume on the steam bath at 78° 

@ 01/ 4 /;j ~oor---i---+~-~t-~--+----~~--~~~q/~---+---~~~~7L~-~ 

C., resulting in the separation from 

the hot solution of 41.01 grams of 

salt, designated 4 A. When the solution was cooled from 78° to 30° C., 

8.88 grams of crystals separated. 

These were marked 4 B. The filtrate 

remaining had a specific gravity of 

1.318 at 30° C. and weighed 351 grams. 

§ 1/ )~// /[/ / ~sor--_,---+---~--4V--~~~~~~~~~~~~-H~~~~--~ 

~ I y _J'YY 1 ~1. -

~:::;::.o/':/:/::=:7:7:: 1/ 7 ;/ I II 

I ~ 1 

Fifth stage.-The 351 grams of solution obtained as indicated above was 

evaporated to about 200 cubic centimeterson the steam bath at 78° c.,and 

during this process 28.81 grams of crystals were deposited from the hot solution. These were designated 5 A. Cooling from 78° to 30° C. resulted in the 

20 1((/ ;__; 10 // / --~ "ji0/ ~~~ 

rooo ~----~ 900 800 700 600 500 400 

GRAMS OF SOLUTlON 

300 200 100 

deposition of 14.31 grams of crystals, 

designated 5 B. The solution that was 

~ separatedfrom the crystals had a specific 

gravity of 1.351 and weighed 230 grams. 

FIGURE 1.-Diagram Sixth stage.-The filtrate remaining showing the percentages of the various constituents deposited during evaporation of brine from Searles Lake, Cal. from the fifth operation, which amounted to230grams, was concentrated on the steam bathat78° C. 

to about 100 cubic centimeters. The salts deposited during 

the evaporation from the hot solution weighed 24 .68 grams 

and were designated 6 A. Those deposited during cooling from 78° to 30° C. weighed 29.37 grams and were designated 6 B. The filtrate had a specific gravity of 1.386 at 

30° C. and weighed 114 grams. 

of crystals, representing seven stages in the 

evaporation, were obtained. A summary of 

the procedure followed is given below, together 

with the quantity of salts making up the 

several fractions and the weight and specific 

gravity of the solution remaining after each 

stage in the evaporation. 

First stage.-1,000 grams of brine from Searles Lake 

was evaporated on the steam bath at 78° C. to about twothirds of the origina1 volume, and during this ·process 75 .00 

grams of salts, which were designated 1 A, separated from 

the hot solution. On cooling from 78° to 30° C., 19.11 

Seventh stage.-The 114 grams of solution obtained as 

described above was evaporated on the steam bath at 

78° C. to about 50 cubic centimeters, and the salts deposited during this operation from the hot solution 

weighed 19.22 grams and were designated 7 A. The 

crystals that separated on the cooling of the solution from 

78° to 30° C. weighed 10.41 grams and were marked 7 B. 
EVAPORATION OF BRINE FROM SEARLES LAKE, CAL. 5 

The solution that was separated from the crystals had a 

specific gravity of 1.399 at 30° C. and weighed 55 grams. 

This solution represents the final filtrate, indicated in 

Tables 1, 2, and 3 by the number 8. 

TABULATION OF RESULTS. 

Each of the fractions of crystals obtained in 

the experiments just detailed was analyzed, as 

was also the final filtrate. 14 

The results are given in Table 

1 and have been used in Gomputing the hypothetical combinations given in Table 2. 

The figures in Table 2 were 

obtained by calculating all the 

potassium to potassium chloride and the borate, carbonate, 

·and sulphate radicles to the 

corresponding sodium salts and 

supplying enough sodium chlo3 

z 

0 

~I ...J 

0 

"' 

~ ride to make the results add If) 

1-

up to 100. Although this meth- ~ 

2 

I 

0 

9 

od of computation conceals ~ s 

the small error of closure, it t;; 

z was used because of its sim- 8 7 

plicity. The percentages of ~ 

~ the several constituents depos- o:: 

;;; 6 ited from solution as evapo- w 

ration progressed have been i= 

calculated and are set forth in ~ 

Table 3 and shown graphically ~ 

5 

<( in figure 1. The composition ~ 4 

of the solution remaining after ~ 0:: 

each stage in the evaporation g: -

3 

has been computed from the 

quantity and composition of 

the various fractions of crystals, the composition of the 

final filtrate being used as a 

basis. The data so obtained, 

v 

1----

""' ~ 

r--

l----

/ 

t----

"" ""-- -

--

ration, have been plotted and are shown graphically in figure 2. 

Nos. 1 to 8 in the tables represent the 

successive stages in the evaporation. The 

letter A refers to the crystals deposited from 

the hot solution during the process of · evaporation; B has reference to the crystals deposv -----.._, ~ r--.... 

~ 

~ 

\ / ~ 

~ Na r\ -..........._ 

1'-- l/ 

\~ .... 

rv 

7 

/ 

j 

~ 7 ---.._ 

/ / / / v ~ ~ ___....,.- v v ~ v ~ v ~ so.,. - y :::::--- t--- ~ 

~ 

~- t---~ 

together with the composition 

of the original brine and that 

0 

LOOO 900 800 700 600 500 400 300 200 100 0 

GRAMS OF SOLUTION 

Of the final mother liquor, are FIGURE 2.-Diagram showing the changes in the composition of the solution resulting through 

presented in Table 4. These evaporation of brine from Searles Lake, Ca). 

values, which give the changes in the composi- ited as the solution was cooled from 78° to 

tion of the solution resulting through evapo- 30° C. 
TABLE !.-Percentage composition, in radicles, of the crystals deposited during fractional evaporation. 

1 2 3 4 5 6 

A B A B A B A B A B A B 

---

K .... : . ... ....... . ..... . .......... 0. 96 0. 72 1. 14 0. 87 1.54 1. 37 1. 72 1. 78 1.95 40.35 3.21 30.03 

Na ...... ....... ........... .. ..... 35. 45 38. 61 36. 51 38. 71 37.28 37. 94 37.00 37.58 37.27 8. 87 36.04 12.87 

01 ................................ 14. 73 59. 92 30.22 59. 43 50. 99 58. 99 45.20 58. 98 46. 76 47. 92 44.03 31.10 

804·· · ·--- .... ·······. ··· · ···· .. . 36. 98 . 22 23. 51 . 28 6. 60 . 47 10.49 . 31 9. 16 . 39 8. 55 1. 03 

003 •••••••. ••• •••• •••••• ••••••.. • . 11. 34 . 21 8.03 . 31 2.90 . 53 4. 68 . 52 3. 99 1. 36 6. 54 5.57 

B407. ··········. ····· ·· ·········. . 54 . 32 . 59 . 40 . 69 . 70 . 91 . 83 . 87 1. 11 1. 63 19.40 ·~--

100.00 100.00 100.00 100.00 100.00 100. 00 100.00 100.00 100.00 100.00 100. 00 100.00 

H20 by difference ................. 7. 60 3. 89 6. 74 3. 18 8.64 6.36 11. 72 2.34 8. 21 9.60 8. 67 35.21 

Anhydrous salts: 

By summation ... ___ ._. ____ ___ 92.40 96. 11 93. 26 96. 82 91. 36 93. 64 88.28 97. 66 91. 79 90.40 91.331 64. 79 

Ignited residue ....... ___ ..... 92. 20 95. 70 93. 05 96.40 91.50 93. 30 88. 40 97. 60 92.20 90.35 91.00 64. 15 

Weight of crystals._._ .... _ .grams .. 75.00 19.11 28. 93 14. 30 21. 52 13. 56 41.01 8. 88 28. 81 14.31 24.68 29. 37 

a The solution also contained 0.22 per cent arsenic=0.55 per cent of the anhydrous salts. 

TABLE 2.-Percentage composition, in hypothetical combinations, of the crystals deposited during fractional evap'oration. 

1 2 3 4 5 6 

A B A B A B A B A B A B 

KCl ...................... .. ..... . . 1. 83 1.37 2. 17 1. 66 2. 93 2. 61 3.28 3. 39 3. 72 76. 90 6. 12 57. 25 

NaCL ............................ 22. 72 97.52 48.09 96. 86 81. 29 94. 84 71. 67 94.56 74. 56 18. 68 67. 57 6.28 

Na2S04 ................. _ ........ _. 54. 75 . 33 34. 81 . 41 9. 77 . 70 15. 51 . 46 13. 56 . 58 12. 65 1. 53 N~C03 ••••• --- •••••• ----.---.-- •• 20.00 . 37 14. 17 . 55 5. 12 . 94 8.26 . 52 7.04 2.40 11. 55 9.84 

N ~B -- ... . _. _ .... ____ ......... . 70 . 41 . 76 . 52 . 89 . 91 1. 18 1. 07 1. 12 1.44 2. 11 25. 10 

100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 

-----

7 

A B 

5.29 31. 68 

35. 60 12. 14 

21. 64 32. 51 

6. 71 . 77 

26. 83 4. 96 

3. 93 17. 94 

100.00 100.00 

23. 59 28. 99 

76. 41 71.01 

76. 10 71. 20 

19.22 10.41 

7 

A B 

10.08 60. 37 

27.49 6.54 

9.94 1. 14 

47.40 8. 75 

5.09 23. 20 

100.00 100.00 

8 

11. 97 

29. 36 

22. 33 

3.07 

21. 23 

12.04 

a 100. 00 

59. 91 

40.09 

40. 80 .............. 

8 

22. 80 

19. 58 

4.54 

37. 50 

15. 58 

100.00 

--

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p 
EVAPORATIO.N OF BRINE FROM SEARLES LAKE, CAL. 7 

TABLE 3._:_Percentages of the constituents deposited during fractional evaporation. 

[The first column for each constituent gives the percentage deposited at each stage; the second column gives the total percentage.] 

Stage. K. Na. Cl. 

I 

so4. C03 . B40 7 • 

1A ...... .. ........... 3. 19 3.19 21.44 21.44 8.23 I 

8. 23,58. 50 58.50 29.88 29.88 3.36 3.36 

1 B ................... . 62 3.81 6.19 27.63 8.90 17. 13 . 09 58. 59 .15 30. 03 . 55 3.91 

2A ............... . ... 1. 48 5.29 8.59 36. 22 6.60 23.73 14.47 73.06 8.25 38.28 1.45 5.36 

2 B .............. ... .. . 57 5.86 4.68 40.90 6.65 30.38 . 09 73.15 .15 38.43 . 55 5.91 

3A ................... 1.43 7.29 6.40 47.30 8.10 38.48 2.97 76.12 2.17 40.60 1.27 7.18 

3 B ................... . 81 8.10 4.20 51. 50 6.05 44: 53 .14 76.26 . 27 40.87 . 82 8.00 

4A .......... .. ....... 2.95 11.05 11. 68 63.18 13.22 57.75 8.68 84.94 6.43 47.30 3.00 11.00 

4 B .................. . .71 11.76 2.84 66. 02 4. 13 61.88 . 07 85.01 .19 47.49 . 64 11.64 

5A ................... 2.48 14.24 8.61 74.63 10.00 71.88 5.52 90.53 3.99 51.48 2.09 13.73 

5 B ........... . ....... 24. 85 39.09 1.00 75.63 5.01 76.89 .11 90. 64 . 68 52. 16 1. 27 15.00 

6A ............ ....... 3.43 42. 52 7.08 82. 71 8.02 84.91 4.38 95.02 5.63 57.79 3.36 18.36 

6 B ........... . ....... 27.22 69. 74 2.14 84.85 4.79 89. 70 .46 95.48 4.03 61.82 33.51 51.87 

7 A ............ .. ..... 3. 71 73.45 4.56 89.41 2.57 92.27 2.26 97.74 14.97 76.79 5.28 57. 15 

7 B ................... 11.14 84.59 . 79 90.20 1. 94 94.21 I .14 97.88 1.41 78.20 12.09 69.24 

8 .............. .. ..... 12.57 97.16 5.66 95.86 3.98 98.19 1. 55 99.43 17.80 96.00 24.20 93.44 

TABLE 4.-Changes in the composition of the solution during fractional evaporation. 

Solution Spe- Percentage composition of the solution (calculated). Potascific sium in after gravity total K/Na Stage. evapora- at salts ratio. tion 30° C. K. Na. Cl. so4. C03 • B40 7. Total. (per (grams). 20° c. cent). 

--------------------

Original solution a .•..•... ... 1,000 1. 292 2. 10 11.46 12.37 4.38 2.63 1.10 34.04 6.16 0.18 

1 ................... . ........ 750 1.278 2.69 10.88 13.60 2.39 2.41 1.40 33.37 8.06 . 25 

2 ............................ 617 1.282 3. 19 10.66 13.85 1.87 2.55 1.67 33.79 9.44 . 30 

3 ............................ 502 1. 295 3.84 10.57 13.46 2.03 3. 10 2.00 35.00 10 97 . 36 

4 ............................ 351 1.318 5.26 10.17 13.04 1. 81 3. 79 2.74 36.81 14.30 . 52 

5 .......................... .. 230 1. 351 5.45 10.50 11.66 1.68 5.22 4.01 38.52 14.15 . 52 

6 ................... . ........ 114 1. 386 5.20 11.54 9.39 1. 53 8.21 4.29 40.16 12.95 .45 

7 a ........................ . 55 1. 399 4.80 11.77 8.95 1.23 8.51 4.83 40.09 11.97 .41 

a Values determined by actual analysis. 

DISCUSSION. 

Before discussing the results presented in the 

tables, it will be well to recall the fact that 

before the fractional crystallization began sodium chlorid_e and borax had been deposited 

from the brine on standing at 22.f) ° C. Although undetermined factors make deductions 

inconclusive, the facts indicate that when 

the temperature is lowered these constituents 

must separate from the solution in order that 

equilibrium may be attained for the new conditions. It n1ight be inferred that by lowering 

the temperature still further larger amounts of 

sodium chloride and borax would leave the solution. However, as the solubility of sodium 

sulphate decreases rapidly when the temperature is lowered below the transition point, this 

constituent might separate out in large amounts 

at low temperature. In principle the same 

argument may be applied to the potassium 

chloride and sodium carbonate contained in the 

brine. The fi11nJ equilibrium at any temperature is dependent on the solid phases which 

separate and must therefore be determined 

experimentally. 

By reference to the tables it will be seen that 

more than 58 per cent of all the sulphate originally present in the brine was deposited from 

the hot solution in the first fraction of crystals, 

which is composed of nearly 55 per cent of 

sodium sulphate, large amounts of cm·bonate 

and chloride, and only small amounts of borate 

and salts of potassium. In the other fractions 

of crystals that were deposited from the hot 

solution as evaporation progressed the sulphate 

radicle is a chief component. When the brine 

had been reduced to half its original volume, 

more than 76 per cent of all the sulphate had 

been deposited, and in the final filtrate less than 

2 per cent of it remained. It is signifieant that 

only small quantities of sulphate were found in 

the several fractions of crystals deposited as 
8 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1916. 

the solution was cooled from 78 ° to 30° C. 

These facts point to the conclusion that sodium 

sulphate is less soluble in the hot solution than 

it is at 30° C., a conclusion which is in accord 

with experimental data on the solubility of 

sodium sulphate in pure water. 

The behavior of the carbonate radicle was 

somewhat like that of the sulphate. A large 

portion came down in the first crop of crystals 

and in all the succeeding fractions that were 

d~posited from the hot solution during evaporation (marked A in the tables). However, a 

considerable amount separated out during cooling from 78° to 30° C. in fractions 6 B and 

7 B, and nearly 18 per cent of the total amount 

in the original brine remained in the final 

filtrate. The results are somewhat difficult to 

interpret but point out clearly that the carbonate is at least as soluble in the cold solution 

as in the hot until about the fifth stage in the 

evaporation. Then, in the presence of a greater 

concentration of potassium, the carbonate is 

much more soluble in the hot solution. 

At this point it seems pertinent to call attention to an experiment conducted by the writer 

with the view of showing the possibility of removing the carbonate from the brine by the 

action of carbon dioxide. This gas was passed 

at the rate of several bubbles a second through 

100 grams of the brine at room temperature. 

No visible action was apparent for some time. 

Finally a precipitate began to form and to 

adhere to the bottom and sides of the container. After about six hours no further action 

was perceptible and the reaction appeared to 

be completed. The residue, which was filtered 

from the solution through a tared Monroe 

crucible, weighed 5.85 grams. It was analyzed 

with the following results: 

Analysis of precipitate produced through action of carbon 

dioxide on brine. 

Na.. ........................................... 26.27 

K............................................. .68 

01............................................. 4. 28 

804······················ ······················ 003 ••••••••••••••••••••••••••••••••••••••••••• 

HC03 ••••••••••••••••••••••••••••••••••••••••• 

B407········································ .. . H 20 (by difference) .......................... .. 

. 65 

4. 13 

53.36 

1. 06 

9.57 

100.00 

The solids which separated through the action 

of carbon dioxide on the brine contained · 73.6 

per cent of sodium bicarbonate and 9.57 per 

cent of water. The original brine contained 

2.63 per cent of C03 , and so the deposition 

represents 67.5 per cent of all the carbonate 

originally present in the brine. 

Small amounts of borate separated from the 

hot solution and also during cooling in all the 

fractions of crystals, but at the beginning of 

the sixth stage in the evaporation, when only 

114 grams of the solution remained, the total 

quantity of borate that had been deposited was 

only about 18 per cent of the amount originally 

present. More than 45 per cent of the borate 

separated in the two fractions 6 B and 7 B as the 

solution was cooled from 78 ° to 30° C., and more 

than 24 per cent remained in the final filtrate. 

The results show that the borate became more 

soluble in the solution .as the concentration of 

the potassium and carbonate radicles increased 

and that of chloride and sulphate decreased. 

Although potassium separated in increasing 

amounts in all the succeeding fractions of 

crystals up to the fifth stage, only about 8 per 

cent of that originally present was lost from 

solution by reducing it to half the original 

volume and increasing the concentration of the 

potassium to nearly 4 per cent. This loss is 

somewhat higher than that recorded in the 

experiments with artificial potash brines.1 

More than 60 per cent of all the potassium 

was deposited on cooling the solution from 

78° to 30° C. in fractions 5 B, 6 B, and 7 B, and 

12.57 p~r cent remained in the final filtrate. 

Residue 5 B, representing 24.85 per cent of all 

the potassium in the original brine, contained 

the equivalent of 76.9 per cent of potassium 

chloride, with sodium chloride as the principal 

impurity. Residues 6 B and 7 B, representing 

more than 48 per cent of all the potassium in the 

brine, contained 57 and 60 percent, respectively, 

of potassium chloride, but in these residues 

carbonates and borates are the chief impurities. 

The data here recorded indicate that carefully controlled fractional evaporation and 

crystallization, possibly combined with other 

treatment, promise much as a means of obtaining potassium from brines similar to that- of 

Searles Lake. A wider range of temperature 

suggests itself at once, and other possibilities 

are apparent. · However, many points in regard 

to the behavior of the constituents of the brine 

under varying conditions remain to be studied 

before the problem can be adequately discussed. 

1 Hicks, W. B., Evaporation of potash brines: U. S. Geol. Survey 

Prof. Paper 95, pp. 65-72, 1915 (Prof. Paper 95-E).