VARIATION OF STOKI.ASA 



439 



operation, and if too weak, the contents of the flask have to be 

 heated overmuch, the result in both cases being the formation of 

 a fine spray of caustic solution, which is very difficult to stop, even 

 with complicated washing attachments to the distilling flask. The 

 test analyses on pure nitrates are satisfactory. This method has 

 been used with satisfaction in the laboratory of the Bureau of 

 Chemistry, but does not appear to have any special advantage 

 over the process of Ulsch, to be described further on. 



379. Variation of Stoklasa. Stoklasa has subjected the 

 method of Devarda to a comparative test with the following 

 methods : 61 



Fig- 33- Stoklasa's Nitric Acid Apparatus. 



1. Wagner's schloesing-grandeau method. 



2. Lunge's nitrometer method. 



3. Stutzer's method. 



The reduction takes place in a copper erlenmeyer A, Fig. 33, in 

 which, in addition to the solution containing the nitrate, are placed 

 200 cubic centimeters of water, 40 cubic centimeters of potassium 

 hydroxid solution of 33 B., five cubic centimeters of alcohol, and 

 finally two and one-half grams of the finely powdered devarda 

 alloy. The distillate passes through a tube B filled with glass 

 pearls and into the condenser D through the bulbs CC'. 

 61 Zeitschrift fur angewandte Chemie, 1893, 6 : 161. 



