80 HOM' CROr.3 FEED. 



ler's test,* which is of cxtveino delicacy, and -wliich he con« 

 stantly employed in his invostigntions. 



Zabelia operated in closed vessels. The apparatus he 

 used consisted of two glass flasks, a larger and a smaller 

 one, which were closed by corks and fitted with glass 

 tubes, so that a stream of air entering the larger vessel 

 should bubble through water covering its bottom, and 

 thence passing into the smaller flask should stream through 

 Nessler's test. Next, he found that no ammonia and 

 (by Price's test) but doubtful traces of nitrous acid could 

 be detected in the purest water when distilled alone in 

 this apparatus. 



Zabelin likewise showed that cellulose (clippings of filter, 

 paper or shreds of linen) yielded no ammonia to Nessler's 

 test when heated in a current of air at temperatures of 

 120° to 160° F. 



Lastly, he found that when cellulose and pure water to- 

 gether were exposed to a current of air at the tempera- 

 tures just named, ammonia was at once indicated by 

 Nessler's test. Nitrous acid, however, could be detected, 

 if at :dl, in the minutest traces only. 



Views of SchOnbeiv. — Tiie reader should observe that 

 Boettger and Schonbein, finding in the first instance by 

 the exceedingly sensitive test with iodide of potassium 

 and starch-paste, that nitrous acid was formed, when hy- 

 drogen burned in the air, while the water thus generated 

 was neutral in its reaction with the vastly less st iisitive 

 litmus test-paper, concluded that the nitrous acid was 

 united with some base in the form of a neutral salt. Af- 

 terward, the detection of ammonia appeared to denion- 

 Btrate the formation of nitrite of ammonia. 



We have already seen that nitrite of ammonia, by ex- 

 posure to a moderate heat, is resolved into nitrogen and 

 water. Schonbein assumed that under the conditions of 



* See p. &4 



