ACCURACY OF THE PROCESS 593 



dered alkaline by soda-lye and boiled. With the precautions 

 above mentioned, the method promises to prove of great value 

 in agricultural analysis, effecting both a saving of time and ex- 

 pense in potash determinations. 



497. Accuracy of the Process. The perchlorate method was 

 tried in conjunction with the platinum method on the two samples 

 of potash fertilizer prepared and distributed by the official reporter 

 on potash for 1893. 71 One of the samples was of a fertilizer 

 which had been compounded for the Florida trade and contained 

 bone, dried blood, and potash, mostly in the form of sulfate. 

 The other sample consisted of mixed potash salts, sulfate, chlo- 

 rid, double salt, kainit, and about five per cent, of the sulfates of 

 calcium, potassium, and magnesium. 



The results obtained by Wagner and Caspari on the two sam- 

 ples follow : 



Sample No. i. Sample No. 2. 



Per cent, potash Per cent, potash 



By the platinum method 13-25 37-98 



By the perchlorate method i3-9 37 -82 



In transmitting their results these chemists say : "In the course 

 of our work the fact was again clearly and distinctly brought out 

 that the improved perchlorate method is decidedly superior to the 

 old platinum chlorid method as regards rapid execution and sim- 

 plicity of manipulation. This superiority is especially perceptible 

 in the analysis of mixed fertilizers containing phosphoric acid. 

 For this reason the laborious and time-taking separation of the 

 alkalies, which is necessary in the .platinum method, is entirely 

 avoided." 72 In the presence of organic matter containing nitro- 

 gen it is advisable to previously destroy the nitrogenous materials 

 in order to avoid the danger of their transformation into am- 

 monia during the progress of the analysis. 



The perchlorate method, on the whole, appears to be almost 

 as accurate as the platinum process, requires less manipulation 

 and can be completed in a shorter time and at less expense for 

 reagents. In spite of these advantages, however, the use of the 

 method has not obtained to any extent in this country, and in so 

 far as the author knows, is not employed in any official or com- 

 mercial laboratory in the United States. 

 71 Division of Chemistry, Bulletin 38, 1893 : 57. 

 " Division of Chemistry, Bulletin 38, 1893 : 56. 



