288 Journal of the Asiatic Society of Bengal. [August, 1914. 



lead compound was not allowed to react with the gas, and after 

 displacing the nitric oxide by means of a current hydrogen 

 the contents of the flask were vigorously shaken to facilitate 

 the oxidation of the dissolved nitric oxide by the lead peroxide 

 left over. The cork closing the mouth of the flask was then 

 removed and the liquid filtered, when a pale yellow solution 

 was obtained. This answered to the metaphenylene diamine 

 test for nitrites and gave a white precipitate of lead sulphate 

 with dilute sulphuric acid. The nitrous acid was removed 

 completely by heating with an excess of ammonium sulphate 

 as long as the liquid gave a colour reaction with Griess's re- 

 agent, the precipitated lead sulphate was filtered off and on 

 now applying the brucine test for nitric acid a distinct red 

 colouration was obtained. It, therefore, appeared that both 

 lead nitrite and lead nitrate had been formed. Ray Dhar and 

 De(T. Chem. Soc, 1912, 101. 1185), however, are of opinion 

 that when ammonium nitrite is heated for the preparation of 

 nitrogen, a small portion breaks up according to the 



equation 



3NH 4 N0 2 = NILNO, + 2NO + 2NH, + ILO. 



They were led to this conclusion by the result arrived at 

 by Lord Rayleigh and Prof. Ramsay while endeavouring to 

 prepare "chemical nitrogen" from a mixture of ammonium 

 chloride and potassium nitrite. It was pointed out that the 

 crude gas from this source always has an ammoniacal smell. 

 If, however, potassium nitrite be dissolved in water contain- 

 ing ammonium chloride the solution should, according to the 

 laws of chemical equilibrium, contain the four substances— po- 

 tassium chloride, ammonium nitrite, ammonium chloride and 

 potassium nitrite— so that we are not justified in assuming 

 without experimental proof, that the ammonia in the above 

 instance is a product of the decomposition of ammonium 

 nitrite. If, on the other hand, ammonium nitrite, actually de- 

 composes on heating into ammonium nitrate, nitric oxide and 

 ammonia, the colour reaction obtained with brucine, as indi- 

 cated above, is inconclusive. We, accordingly, proceeded to 

 study the action of heat on a solution of ammonium nitrite. 



3. A strong solution of the salt was prepared by dissolv- 

 ing freshly prepared silver nitrite in boiling water and adding 

 barium chloride as long as a precipitate separated out. The 

 silver chloride was filtered off and to the solution of barium 

 nitrite thus obtained ammonium sulphate was added slightly 

 in excess. The precipitated barium sulphate was removed by 

 filtration and the clear solution of ammonium nitrite boiled 

 as long as it gave a yellow colouration with a solution of meta- 

 phenylene diamine hydro-chloride in dilute hydrochloric acid. 

 On now applying the brucine test for nitric acid no red coloura- 

 tion was obtained. It, therefore, follows that by the action 



