550 AGRICULTURAL ANALYSIS 



tate to the filter, wash with alcohol, dry the filter and the precipi- 

 tate at a gentle heat till all alcohol has evaporated, carefully 

 transfer the contents of the filter to a watch glass placed on white 

 glazed paper; dissolve the potassium platinochlorid still remain- 

 ing on the filter in small quantities of boiling water, evaporate 

 the filtrate on a water bath in an accurately weighed platinum 

 dish to dryness and transfer to the same the main portion of the 

 chlorid from the watch-glass. In order to obtain the salt free of 

 the corresponding combinations of sodium, barium, calcium, and 

 magnesium, which salts, although soluble in alcohol, may make 

 the salt impure, before weighing treat the precipitate twice with 

 small quantities of cold water, which will dissolve these im- 

 purities ; evaporate the solution after addition of one cubic cen- 

 timeter of platinic chlorid nearly to dryness on a water bath, 

 treat the residue in the same way as given before, add the small 

 quantity of potassium platinochlorid which is hereby obtained 

 together with the main portion to the platinum dish, dry at 130, 

 and weigh. Only after having been treated in this way may the 

 precipitated potassium platinochlorid be considered absolutely 

 pure. The Stassfurt salts contain magnesia, often in large quan- 

 tities, and as a consequence the potassium platinochlorid precipi- 

 tated directly is likely to be contaminated therewith. 



470. Methods for the Analysis of Carnallit, Kainit, Sylvinit, 

 and Bergkieserit. The chemists of the German Potash Syndi- 

 cate use the following methods in the analysis of the raw products 

 mentioned above. 39 



1 I ) Preparation of the Sample. It is advisable to take from a 

 large, well mixed mass at least half a kilogram for the analytical 

 sample, and this should be ground to a fine powder in a mill or 

 mortar. 



(2) Estimation of the Potash by the Precipitation Method. In 

 a half liter flask are placed 35.71 grams of kainit, hartsalz or 

 sylvinit, or 30.56 grams of carnallit or bergkieserit, which are 

 boiled with 350 cubic centimeters of water after the addition of 

 10 cubic centimeters of hydrochloric acid. After cooling, the 



39 Division of Chemistry, Bulletin 35, 1892 : 63. 



Methods of Analyses of Potash Salts, Published by the Kalisyndikat, 

 Leopoldshall-Stassfurt, 1906. 



