544 AGRICULTURAL ANALYSIS 



composed of the following named chemists: Tisserand, Vas- 

 saliere, Schloesing, Prillieux, Risler, Aime Girard, Cornu, Gran- 

 deau, Liebaut, Joulie, Mamelle, Miintz and Marsais. 



Perchloric Acid Method. The preference is given by the 

 French Commission to this method which is conducted accord- 

 ing to the procedure given by Schloesing, which is substantially 

 the one found on page 579. The method varies slightly when 

 used with the different salts of potash, as, for instance, the sul- 

 fates and the chlorids. There is also a very slight difference in the 

 manipulation where the potash is contained in a complex or mixed 

 fertilizer. The above differences refer, however, solely to the pre- 

 liminary treatment and to the elimination of the potash from its 

 principal compounds. 



Platinum Chlorid Method. The French commission has also 

 recommended the platinum method for the determination of pot- 

 ash in the form of double chlorids of potash and platinum. The 

 method described does not differ in any essential points from that 

 already given. Where it is advisable to estimate the soda also, 

 the total chlorin is determined in the mixed chlorids, the potash 1 

 estimated by the platinum method, the chlorin necessary to com- 

 bine with it deducted from the total chlorin and the residual 

 chlorin calculated to chlorid of soda. 



Method of Corenwindcr and Contamine. The French commis- 

 sion has recommended also as one of the alternative methods the 

 determination of potassium in salts and in refined potash com- 

 pounds according to the variations of Corenwinder and Con- 

 tamine, in which there is introduced into the process as a reagent, 

 sodium formate. This method is regarded by the Commission 

 as exact as that in which the perchlorate is used. In this process 

 25 grams of the salt to be examined is ignited in case it con- 

 tains any organic matter or salts of ammonia, which must pre- 

 viously be destroyed or eliminated. After cooling, the melt is 

 dissolved and the volume brought to one liter and the solution 

 filtered. An aliquot part of the filtrate, conveniently 20 cubic 

 centimeters, corresponding to five decigrams of the original mate- 

 rial, is acidulated with hydrochloric acid, evaporated to dryness, 

 and the saline residue weighed for the purpose of determining; 



