November 15,1934
I N D U S T R I A L A N D E N G I N E E R I N G C H E M I STR Y
439
from greenish black to light yellow depending upon the iodide concentration. In the absence of interfering elements less than 0.003 mg. of iodine produces a faint coloration on 0.1 gram of mercurous chloride. The shades of color produced provide a method for approximately estimating minute quantities of iodine in dilute solution.
dilute with water, keeping the hydrochloric acid concentration below 4 per cent. Add CuS04.5H20to make a 5 per cent cold solution, followed by mercurous chloride which precipitates palladium. The palladium may be estimated by the color on the mercurous chloride, or preferably the precipitate ma be filtered, dissolved, and diluted for estimation by mercurous chcride. The filtrate from the removal of palladium now contains platinum. SEPARATION OF GOLD, PLATINUM, PALLADIUM, SELENIUM, Add a little mercurous chloride to the filtrate and boil gently for about 5 minutes to precipitate platinum. The precipitate TELLURIUM, AND ARSENIC may be filtered, dissolved, and reprecipitated for estimation. The methods of separation are based entirely on reductions 2. SEPARATION OF SELENIUM,TELLURIUM, AND ARSENIC. from solution to the elemental form. It is best to use very Gold, platinum, and palladium are removed from this fresh solution by mercurous chloride, after which the filtrate is made dilute solutions and to work with a few cubic centimeters of a up to a hydrochloric acid concentration of about 20 per cent. solution containing no more than a few milligrams of each Add about 5 per cent of sodium bisulfite and allow to stand for element. Such a solution should first be made acid to the 15 minutes, followed by gentle boiling for a few minutes to preextent of about 1 or 2 per cent with hydrochloric and divided cipitate selenium. The selenium may be filtered, redissolved with hydrochloric acid, and estimated with mercurous into two parts, one part being treated for the segregation of chlorinated chloride. The filtrate from the removal of selenium contains gold, platinum, and palladium and the other for arsenic, tellurium and arsenic. selenium, and tellurium. Tellurium is removed by adding mercurous chloride, warming the solution if necessary t o hasten reaction. The filtrate now 1. SEPARATION OF GOLD,PLATINUM, AND PALLADIUM. Add contains only arsenic. crystals of oxalic acid to make about a 5 per cent solution and In order to remove arsenic the hydrochloric acid concentration boil to precipitate gold. Filter on a fine paper, wash, then dis- must be raised to 30 per cent or higher, after which arsenic can solve precipitate, some of which adheres to the beaker, %it:, dilute be precipitated by mercurous chloride in the usual manner. chlorinated hydrochloric, boil off chlorirlo, and test with mercuroue chioride to detect and estimate gold. The filtrate from the LITERATURE CITED go:d reduction contains the other elements from which platinum cad palladium can be separated. (1) Pierson, G. G., Master's Thesis, University of Wisconsin, 1923. Evaporate filtrate to near dryness with a little sulfuric acid to (2) Smith, H. R., and Cameron, E. J., IND. ENG.CHEM., Anal. Ed., 6, decompose oxalic acid. Any element precipitated during the 400 (1934). evaporation is dissolved with a little hydrochloric acid and potassium chlorate. Drive off free chlorine and excess acid, and R ~ C B I V BMay I D 23, 1934.
Determination of the Common and Rare Alkalies in Mineral Analysis ROGERC. WELLSAND ROLLINE. STEVENS, U. S. Geological Survey, Washington, D. C.
I
N MOST rock and mineral On record no mention is made Of rubidium and cesium. Lithium is reported as a trace in many-but this m e a n s l i t tIe quantitativelythough it has of course been de-
Methods are described which afford a determination of each member of the alkali group and are successful in dealing with the quantities of the rare alkalies found in rocks and minerals. The procedures are relatively rapid and based chiefly on the use of chloroplatinic acid, absolute alcohol and ether, and ammonium sulfate, The percentages Of all the alkalies found in a number Of are given*
t e r m i n e d occasionally by the method' The few reported results for rubidium and c e s i u m a r e questionable. A m e t h o d for afi the alkalies is needed, one that will not be too complicated and that will be adapted to the particular purpose of handling the percentages of lithium, rubidium, and cesium met with in rocks and minerals.
Previous attempts to deal with all the alkalies are noted by Hillebrand and Lundell (2) and by Noyes and Bray (4). The method of extracting rubidium and cesium chlorides from potassium chloride by means of hydrochloric acid and alcohol has been used by several analysts. Strecker and Diaz, however, in referring to this step (8) give no details of procedure, and the extraction of rubidium was found to be incomplete by Moser and Ritschel (3); they, however, used relatively large quantities of the two salts in their tests. Experience shows that e ~ o r t should s be directed to dealing with small quantities of lithium, rubidium, and cesium. Attempts to devise a quantitative procedure on the scheme of Noyes and Bray gave unsatisfactory results for small quantities of rubidium and cesium, as the precipitates formed were not sufficient,lv insoluble. Results were correct only to a milligram or more." A com lex organic compound, sodium 6-chloTo-6nitrotoluene-m-sulgnate, is suggested by Davies (1) as a precipi-
F ~ t ~ ~ quite soluble. The writers found, however, that the rubidium comp o u n d w a s not sufficiently insolublefortheseparation of rubid-
i U $ ~ ~ O,Leary ~ ~ and ~ ~ Papish (6) have reviewed the analytical reactions of rubidium and cesium and proposed some new methods. They precipitate rubidium and cesium with phosphomolybdic acid and obtain excellent separations from potassium although the procedure appears to be rather time-consuming. deparation of most of the potassium, the element generally in excess, however, seems preferable to precipitation of the minor elements first. The methods here described afford a determination of each member of the alkali group and are successful in dealing with the quantities of the rare alkalies found in rocks and minerals. They presuppose that the alkali chlorides have first been obtained free from all other compounds. Should magnesium and calcium be present they will be found mainly with lithium, and sulfate will be found with sodium. The behavior of traces of borate and fluoride has not been determined, but these may easily be removed if known to be present. Spectroscopic confirmation of the presence of mere traces of any of the alkalies should of course be obtained. At the present time the J. Lawrence Smithmethod seems to be preferred for extracting the alkalies from silicate rocks and minerals. It has long been used almost exclusively in the U. S. Geological Survey
s
~
~
~
~
~
l
440
ANALYTICAL EDITION
and is also recommended by Washington (9), and if carefully followed will provide alkali chlorides of sufficient purity.
REAGENTB AND APPARATUS The salts used for reference were of analytical purity. Some sodium chloride of exceptional purity was available. Potassium chloride was Baker’s analytical reagent. Cesium chloride from Eimer and Amend was found to be pure by the spectroscope and on analysis gave an atomic weight of 132.29 for cesium. The rubidium chloride from Eimer and Amend analyzed as follows: HzO, 0.44; LiCl, 0.18; NaC1, 0.36; KC1,4.10; CsCl, 1.26; RbC1,93.66; apparent atomic weight of Rb, 82.1. This salt was purified by fractional precipitation with chloroplatinic acid to free it from potassium, lithium, and sodium, the rubidium chloroplatinate was converted into chloride by removal of platinum by redistilled formic acid, and reprecipitated with hydrochloric acid gas and alcohol to remove any remaining cesium. After two such treatments the atomic weight found for the rubidium was 85.34. Most of the experiments involving rubidium were made with the salt having the analysis first given and corrections were applied for the impurities if necessary. These results were checked in essential particulars, however, with the purest rubidium chloride. Most of the reagents for the methods described are available in every laboratory or can easily be procured. For the separation of cesium certain reagents are needed in particular concentrations : AMMONIUM SULFATESOLUTION.Five grams of ammonium sulfate in 100 ml. of water. ALCOHOLICAMMONIUMSULFATE.Dissolve about 1 gram of ammonium sulfate in 20 ml. of water and add slowly with stirring 100 ml. of 95 per cent alcohol. Remove by filtering the excess ammonium sulfate that precipitates and to the clear liquid add a few crystals of ammonium sulfate to keep it saturated. This solution contains about 0.54 gram in 100 ml. WASHSOLUTION.Prepare in the same way as the alcoholic ammonium sulfate, except that 0.16 gram of ammonium chloride is also added to the water solution of ammonium sulfate before addition of the alcohol. Filtering was usually done with suction applied to a small bell jar containing a test tube or small graduate to receive the filtrate, and a filter containing a small plug of glass wool covered with asbestos or through a small sintered-glass filtering crucible. A milliliter-graduated pipet and a 10-ml. buret are needed. For the separation of cesium the suction filter apparatus consisted of a bottle with bottom removed and rubber stopper carrying funnel and suction outlet tube. The bottom was ground smooth to make a n air-tight connection with a greased ground-glass plate. A small wad of glass wool was placed in the bottom of the funnel and asbestos soup poured in to make a small dense filter. The filter was washed thoroughly with water and dried with alcohol before use. The same filter may be used repeatedly. The funnel stem dipped through a perforated watch glass into the platinum dish or crucible which received the filtrate. The “radiator” used for evaporating off ammonium sulfate consisted of a 100-ml. porcelain crucible in which was placed a small porcelain support to hold the crucible being ignited. Heat was applied to the bottom with a Bunsen flame.
SEPARATION OF SODIUM AND POTASSIUM GROUPS I n the Smith method the total alkalies are generally weighed as chlorides, but the separations outlined in the present paper permit each alkali to be weighed separately, so that an initial weighing of the chlorides is merely a check. Ammonium chloride must of course be removed. The alkali chlorides are first separated into two groups by the use of chloroplatinic acid; lithium goes with the sodium, and rubidium and cesium go with the potassium. This separation
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should be conducted with care to remove sodium and lithium as completely as possible from the potassium group. The potassium chloroplatinate grou is then weighed. The chloroplatinates are changed back to c\lorides by precipitating the platinum with hot dilute formic acid. If the potassium chloroplatinate group is collected and weighed in a small Jena glass filtering crucible (fineness 4), the hot formic acid may be run through the filter several times, leaving the platinum on the filter. A further trace of platinum generally separates on evaporating the alkali chloride solution to dryness, so that it is better to remove the chloroplatinates to a dish and make two evaporations with formic acid before filtering off the platinum. The sodium chloroplatinate solution is also evaporated twice to dryness with a little formic acid, and the salts are dissolved in water and filtered from the platinum. LITHIUM Having obtained the chlorides by removal of the platinum, the sodium solution is ready for the determination of lithium. This is now done in the U. S. Geological Survey by a slight modification of the excellent Palkin method (6)rather than by the Gooch method requiring the use of obnoxious amyl alcohol. PROCEDURE. Evaporate the solution of chlorides t o dryness, preferably in a small glass-stoppered Erlenmeyer flask of about 30-ml. capacity. Dissolve in 0.4 ml. of water, warming slightly if necessary, cool, add 0.01 ml. of concentrated hydrochloric acid and 5 ml. of absolute alcohol, rotate the flask add 15 ml. of ether, allow to stand about 15 minutes, filter through asbestos on glass wool in a small funnel with suction (or through a Jena sintered-glass filter or a weighed Gooch crucible for direct weighing of sodium chloride), wash well with a mixture of 1 part of alcohol to 4 or 5 parts of ether, finally eva orate the filtrate with a slight excess of sulfuric acid in a weighefdish, and heat to constant weight as lithium sulfate. Palkin recommends a second treatment of the first lithiumbearing filtrate, but more sodium chloride is seldom obtained in a second treatment. With a zinnwaldite mica from Virginia 1.92 per cent of lithium oxide was found by this method as compared with 1.85 found by J. J. Fahey, of the Geological Survey, with the older Gooch amyl alcohol method. SODIUM Sodium is weighed as chloride, after separation of the lithium chloride, or as sulfate.
EXTRACTION OF RUBIDIUMAND CESIUMFROM POTASSIUM As already stated, Strecker and Diaz (8) give few details regarding the extraction of rubidium and cesium chloride from potassium chloride with hydrochloric acid-alcohol mixtures. A number of experiments were therefore made on this point, with the object of reducing the solubility of the potassium chloride as completely as possible. It was found that reduction of the percentage of water was advantageous-for example, dissolving the chlorides (0.1000 gram) in only 0.4 ml. of water, saturating with hydrochloric acid gas, and adding 10 ml. of anhydrous alcohol previously saturated with hydrochloric acid gas gave the following results: OF ALKALI CHLORIDES AT 25“ C. TABLE I. SOLUBILITY
SOLV~NT
-SOLUBILITY---KC1 RbCl Gram8
10 ml. of water 3.08 10 ml. of 1 volume of concentrated HC1 and 2 0.0031 volumes of alcohol 0.4 ml. of water and 10 ml. of alcohol, both 0.0008 maturated with HC1
Grams
7.28
CsCl Grams
12.7
0.021
0.31
0.0027
0.024
The separation of cesium from potassium is easier than separation of rubidium from potassium. The solubility indicated that about 2.7 mg. of rubidium chloride might be extracted from potassium chloride without carrying more than 0.6 mg. of potassium chloride, but tests show that the extraction of rubidium proceeds slowly. The quantities extracted (Table 11) were all actually determined as chloroplatinates,
I N D US T R IA L A N D E N G I N E ER I N G CHE M I STR Y
November 15,1934
441
may be present. Very nearly all the cesium is found in the first extract, but if this is appreciable a second extract should be made t o remove any further cesium. Considerable rubidium may still remain with the potassium. The next step is to remove rubidium (and potassium) as sulfate from the extracts containing the cesium, The method here described was worked out by the junior author (R. E. S.). TABLE11. EXTRACTION OF A LITTLERUBIDIUM AND CESIUM Potassium and rubidium are precipitated by ammonium FROM A LARGE PROPORTION OF POTASSIUM in alcoholic solution. The quantity of ammonium sulfate (Using HCI gas and 10 ml. of alcohol saturated with HCl) sulfate, determined by many trials, is such that 5 to 10 mg. N T -A F .-x------, No. OF ExFOUND CsCl EXPT. KC1 RbCl CsCl TRACTIONS RbCl of rubidium sulfate are precipitated essentially free from Gram Gram Gram Gram Gram cesium. A larger quantity of ammonium sulfate causes the 1 0.1000 0.0010 .... 1 0.0005 .... 2 0.0002 .... precipitation of some cesium. Ammonium chloride is in3 0.0001 .... cluded in the alcoholic wash solution, together with ammoTotal 0.0008 nium sulfate to prevent precipitation of cesium sulfate during 2 0.1000 0,0024 .... 1 0.0014 .... washing. 2 0.0007 ....
and the total chlorides first weighed were greater by about 0.6 mg. in each test, because of the presence of potassium chloride. This figure may be used as a correction on the weight of the extracted chlorides for each extraction. For these tests the flasks stood overnight and were then brought to 25’ C., but similar results were obtained after 30 minutes.
3
0.1000
0.0068
....
3
0.0003
....
Total
0.0024 0.0026 0.0012 0.0011 0.0003 0.0003 0.0002
.... .... .... .... .... ....
1 2 3 4
5 6
4
5
6
0.1000
0.1000
0.1000
....
0.0010
....
0.0030
....
Total 1 2
Total 1 2
Total 0.0090
1 2
PROCEDURE. To the dry alkali chlorides in a small dish or beaker add 0.1 ml. of 5 per cent ammonium sulfate and stir the solution until all alkali chlorides dissolve. To the solution add 5 ml. of the alcoholic ammonium sulfate from the buret, dropwise with stirring. After a few drops of the solution have been added the sulfates of potassium and rubidium begin to form as a bulky precipitate. It is well to add the first milliliter very slowly, about one drop a second, as a coarser recipitate is thus formed. Now allow the solution to stand a hal?hour with occasional stirring and then filter with mild suction through the asbestos pad. Rinse the precipitate, beaker, and filter thoroughly with three portions of the wash solution, about 0.5 ml. eaoh. A wash bottle giving a &e jet is useful for the purpose. Catch the filtrate and washings, containing the cesium, in a small tared platinum crucible or dish, and add a small quantity of powdered ammonium sulfate. to convert cesium chloride to sulfate during the ignition to follow. Evaporate the filtrate on the steam bath until the salts begin to crystallize, and then add a few drops of alcohol. This precipitates the salts in a finely divided condition, making them easier to dry and ignite. After taking to apparent dryness, dry the residue further by addition of a few more drops of absoa lute alcohol and again evaporate. Cover the crucible with a watch glass and place in the radiator for the final drying of the residue and the removal of ammonium salts. A low flame is used; any salt which may spatter is reflected back into the crucible by the watch glass. When ammonium chloride is seen on the watch glass it may be removed and the heat increased. After the ammonium chloride is all removed the mass begins to melt and ammonium sulfate to volatilize. Care should be taken to avoid loss of cesium through spattering. After most of the ammonium sulfate is removed, apply the full flame of the burner to the radiator for a short time, then move the crucible about in the direct flame of a burner, keeping the entire crucible at moderate redness. Place in a desiccator, covered with a watch glass, cool, and weigh. Repeat until a constant weight is obtained. Cesium may be confirmed with the spectroscope, using 2 or 3 drops of water to dissolve the sulfate in the crucible. Dip a tight coil of platinum wire, consisting of six to a dozen loops, into the solution and hoId in the Bunsen flame to make the observation. A quantity of cesium even less than 0.1 mg. can thus be detected. Dissolve the precipitate formed in the treatment with alcoholic ammonium sulfate in water, take to dryness in a second tared
0.0057
....
....
0.0010 0.0000
....
0.0010 0.0028 0.0001
.... ....
....
Total
-
0.0029 0,0088
0.0002 0.0090
It may be safely concluded that if the first extract under the conditions specified is not greater than 0.6 mg., significant proportions of rubidium and cesium are absent, and accordingly no further time need be spent in looking for them, unless spectrographic tests are of interest. Evaporate the “potassium chloride” to dryness PROCEDURE. in a 30-ml. Erlenmeyer flask, preferably one with a glass stopper, a t about 106’ C. in an oven through which the neck of the flask emerges, or on the steam bath. Cool, add 0.4 ml. of water, warm, cool again, and saturate with hydrochloric acid gas from a small generating flask, by dropping concentrated hydrochloric acid into concentrated sulfuric acid. Then add 10 ml. of absolute alcohol, also previously saturated with hydrochloric acid gas. Filter with suction through asbestos in a small funnel or through a sintered-glass filtering crucible. Wash with a displacement wash of 2 ml. of a mixture of absolute alcohol and ether. Evaporate the filtrate to dryness, ignite very slightly, but not to redness, and weigh. If the weight is not more than 0.6 mg., rubidium and cesium are absent, except for spectrographic traces.
CESIUM If the weight of chlorides extracted from the potassium chloride is more than 0.6 mg., rubidium or cesium or both
EXPT.
-TAKEN RbCl Gram
7 8 9 10 11 12 13 14 15 16 17 .. 18
19 20 21 22 23 24 25
.... ....
....
0.0100 0.0047 0.0030 0.0010 0.0027 0.0100
----
TABLE 111. SEPARATION OF CESIUMAND RUBIDIUM
CsCl
RbaSOk
RbCl
Gram 0.0104 0.0202 0.0312
Gram
Gram
....
....
.. .. .. ..
0.0301 0.0320
.... .... .... ..... ...
.... ....
0.0043 0.0107 0.0103 0.010s 0.0054 0.0051 0.0048 0.0052 0.0025 0,0022 0.0019 0.0004
FOUND cs2so4
.... ....
....
0.0095 0.0043 0.0028 0.0008
0.0039 0.0097 0.0093 0.0098
0.0049 0.0046 0.0044 0.0047 0.0023 0.0020 0.0017 0.0004
Gram 0.0113 0.0214 0.0323
.... .. ..
....
0.0306 0.0349 0.0251 0.0027 0.0326 0.0220 0.0120 0.0026 0.0217 0.0113 0.0034 0.000s
csci
-----ERRORRbCl
Gram 0.0105 0.0199 0.0301
Gram
.... .... .... ....
0.0285 0.0325 0.0234 0.0025 0.0303 0.0205 0.0112 0.0024 0,0202 0.0105 0.0032 O.OOO7
...... ...... ......
-0.0005 -0.0004 -0.0002 -0.0002 +O.OOlZ -0.0003 -0.0004 -0.0002 0.0000 -0.0003 -0.0002 -0.0003 + O . 0003 -0.0001 -0.0001 -0.0001
CsCl Gram +0.0001
-0.0003 -0.001 1
......
.. .. .. .. . .
......
-0.0016 +0.0005 +0.0006 +0.0001 -0.0003 +0.0004 +0.0003 +O ,0003 +O.OOOl -0.0004 0.0000 -0.0001
ANALYTICAL E D I T I O N
442
crucible, ignite, and weigh to give the weight of rubidium and potassium sulfates in the first extracts.
SEPARATION OF CESIUM AND RUBIDIUM Experiments were made on a range of mixtures, containing quantities of cesium chloride up to 30 mg. and of rubidium chloride up to 10 mg., to illustrate the use of the method and the errors involved. Complete precipitation of the small quantity of potassium, left after treatment with hydrochloric acid and alcohol, was shown by an experiment with 2 mg. of potassium chloride. The crucible used to weigh the alkalies in the cesium fraction gave no change in weight, showing that potassium is quantitatively precipitated as sulfate. It was thought that sodium might also be removed completely, as its solubility as sulfate in water is less than that of potassium, but experiments showed that about 0.7 mg. of sodium sulfate remained in the filtrate, enough to affect the results and make spectroscopic identification of cesium difficult. To a still larger extent lithium remains in solution; an experiment with 0.0025 gram of lithium chloride yielded 0.0030 gram of lithium sulfate in the cesium fraction. Care must therefore be taken in the chloroplatinate procedure in order. to avoid the presence of lithium and sodium with the cesium. The method works best for mixtures containing up to 10 mg. of rubidium chloride and not more than 20 mg. of cesium chloride. With more rubidium its removal becomes somewhat incomplete, and with more cesium chloride it also begins to precipitate as sulfate. If larger percentages of these elements are present, an aliquot portion of the potassium group should be taken for analysis or preliminary fractional separations made. The results given in Table I11 were obtained a t a room temperature of about 22’ C., but during hot weather slightly different results were obtained and it was found necessary to cool the solutions. On account of the difficulty of manipulating very small weights of material, temperature fluctuations, etc., the errors shown in Table I11 have a relative rather than an absolute significance. Nevertheless they offer the possibility of making some corrections. When the quantities of the two chlorides involved are small, as in experiments 23 to 25, no corrections are indicated. The removal of larger quantities of rubidium is less complete and a correction of about 0.3 mg. is shown. With 30 mg. of cesium chloride the results are dependent on the quantity of rubidium chloride that accompanies it; if little or no rubidium is present the results are low by about 1.3 mg., but when 10 mg. of rubidium chloride are also present the results are high by about 0.4 mg. This behavior is due to the removal of the sulfate ion as rubidium sulfate. A trace of cesium was sometimes observed by means of the spectroscope in the rubidium separated in this way, but that the separations were not due to a compensation of errors is clearly shown by the results with the single salts. Even less than 0.1 mg, of cesium sulfate can be shown by the spectroscope and a spectroscopic quantity would have little significance in the separations.
RUBIDIUM If the cesium calculated to cesium chloride, plus 0.6 mg. of potassium chloride for each extraction with alcohol and hydrochloric acid, accounts for all the salts extracted, rubidium is absent; otherwise some rubidium is present, but that separated from the cesium may be only part of the total rubidium. If rubidium is found here the extraction of the potassium chloride with alcohol and hydrochloric acid is repeated as long as any more rubidium chloride is extracted, allowing 0.6 mg. of potassium chloride for each extract. The small quantities of rubidium ordinarily found in succeeding extracts may be freed from the little potassium present by
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separation as chloroplatinate in 5 ml. of 15 per cent alcohol, as shown below. The calculated weight of rubidium chloride can then be checked by the weight of rubidium chloroplatinate.
SEPARATION OF
A
LITTLEPOTASSIUM FROM RUBIDIUM AND CESIUM
As both rubidium and cesium chloroplatinates are considerably less soluble than potassium chloroplatinate a t ordinary temperature (7), rubidium and cesium may be separated from 1 or 2 mg. of potassium chloride, as obtained in the extractions with alcohol and hydrochloric acid. The chlorides are evaporated nearly to dryness with a slight excess of chloroplatinic acid, the salts well stirred with 5 ml. of 15 per cent alcohol, and the less soluble chloroplatinates filtered off, washed with 95 per cent alcohol, and weighed. Tests of this procedure are shown in Table IV. The analyses in Table I1 also confirm the reliability of such separations. TABLEIV. SEPARATION OF RUBIDIUM AND CESIUMFROM LITTLEPOTASSIUM AS CHLOROPLATINATES
-
(Using 5 ml. of 15 per cent alcohol) EXPT. 26 27 28 29 30 31 32 33 34 36
-TAK3N-
KCl
0.0040 0.0020 0.0016 0.0016 0.0015 0.0002 0.0015 0.0015 0.0015
RbCl
.... .. . . 0.0006 0.0010 0.0019
0.0038
.. .. .. .. .... ,, ..
-FOUND-
KC1
CaCl
.. .. .. .. .... .... ....
0.00200 0.0001~
..., .... .... . . .. .. . . ....
.... 0.0005
0.0010 0.0020 0.0000 0.0040 0 OOOOb a K2PtCla precipitated, the rest being soluble. b By spectroscope.
:
A
RbCl
CsCl
....
.. .. .... 0.0008
.... ....
0.0007 0.0021 0.0037
....
.... ..... ... ., ..
0.0006 0.0009 0.0020 0.0038
The total quantity of rubidium is the sum of that separated from the cesium in the first two extractions and that obtained in further extractions of the potassium chloride with alcohol and hydrochloric acid.
POTASSIUM Potassium is generally calculated from the weight of chloroplatinates corrected for rubidium and cesium, but if its percentage is small it is preferable to weigh it as chloride or sulfate obtained after separation of rubidium and cesium.
RESULTS WITH MINERALS I n Table V are given results on the alkalies for several minerals analyzed by the writers. MINERALS TABLE V. ALKALIESIN CERTAIN Lit0
NazO
%
%
%
%
%
0.74 0.45 1.70
9.58 8.60 0.23
1.04 1.46 0.09
0.10 1.14 1.38
0.20 0.96 1.58 1.02
2.66 0.14 0.06 0.08
None None
0.02 0.44 0.76
ZinnwalditefromAmeliaCounty,Va. 1.92 Biotite from Custer County, S. Dak. 0.65 Beryl from Custer County, S. Dak. 0.95
Vermiculite from Yellow Mt., Macon County N C. 0.04 Beryl Bubkfield Maine 0.66 Beryl’ Warren depot Maine 0.82 Beryl: near Standiah,’Maine 0.70
KaO RbrO
0.06
Car0
None Trace
LITERATURE CITED (1) Davies and Davies, J. Chem. Soc., 123, 2976 (1923). (2) Hillebrand and Lundell, “Applied Inorganic Analysis,” John Wiley & Sons, N. Y., 1929. (3) Moser and Ritschel, Z . anal. Chem., 70, 184 (1927). (4) Noyes and Bray, “Qualitative Analysis for the Rare Elements,” Macmillan Co., N. Y., 1927. (5) O’Leary and Papish, IND.ENG.CHEM.,Anal. Ed., 6, 107 (1934). (6) Palkin, J . A m . Chem. SOC.,38, 2326 (1916). (7) Seidell, “Solubilities of Inorganic and Organic Compounds, Supplement,” D. Van Nostrand Co., N. Y., 1928. (8) Strecker and Diaz, Z . ana2. Chem., 67, 321 (1925). (9) Washington, “The Chemical Analysis of Rocks,” John Wiley & Sons, N. Y., 1930. RECEIVEDJune 2, 1934. Published by permission of the Director, U. 8. Ueological Survey.
