554 AGRICULTURAL ANALYSIS 



will be obtained in separating the minerals with bromoform ac- 

 cording to their varying specific gravities. 



Calculations of the salts present in carnallit and bergkieserit 

 are obtained in the following manner: The lime found is reck- 

 oned as sulfate, and the excess of sulfuric acid, after satisfying 

 the lime, is then credited to magnesia. The remaining magnesium 

 is stated as magnesium chlorid. 



(c) In calculating the contents of potash, of potassium chlorid, 

 and of potassium sulfate from the weighed potassium platino- 

 chlorid, the factors 0.1928, 0.3056, and 0.3566 are used, assuming 

 that the atomic weight of platinum is 197.18. 



(d) The two methods which have been described under a and 

 b, and which are in common use in the Stassfurt potash indus- 

 try, i. e., the so-called precipitation method, and the oxalic acid 

 method, give almost identical results. The first method, how- 

 ever, deserves preference on account of greater simplicity in 

 cases where potash alone is to be determined. Finkener's method 

 likewise gives results which agree well with the results obtained 

 by the customary methods. It consists in evaporating the salt 

 solution with a sufficient quantity of platinic chlorid without pre- 

 viously removing the sulfuric acid, reducing the potassium platino- 

 chlorid, and weighing the metallic platinum. 



The following are the results of comparative analyses : 



1. After the precipitation method 22.02 per cent. KC1 



2. After the oxalic acid method 22.03 per cent. KC1 



3. After Finkner's method 22.01 per cent. KC1 



In another sample of carnallit the following results were ob- 

 tained : 



1. After the precipitation method 17.88 per cent. KC1 



2. After the oxalic acid method 17.88 per cent. KC1 



In a third sample of carnallit the content of potassium chlorid 

 was as follows : 



1. After the precipitation method 18.44 per cent. 



2. After the oxalic acid method 18.38 per cent. 



The German chemists object to precipitating the sulfuric acid 

 and alkaline earths with barium oxid and ammonium carbonate, 

 and afterwards the potash with platinic chlorid. The results ob- 



