AMMONIUM AMIDOSULPIIITE. 195 



interact, in which he found that always equal volumes combiue, 

 whichever gas may be taken in excess. The results somewhat 

 approached this when no steps were taken to restrain the rise in 

 temperature due to the union of the gases ; but when the gas- 

 tube was immersed in a cooling-mixture and the ammonia was 

 in excess, the volume of this gas consumed was much greater 

 than that of the sulphur dioxide. This method of investigating 

 the matter is, however, inapplicable, because the ammonium 

 amidosulphite, which is formed, partly decomposes with free 

 evolution of ammonia. By letting the dried gases come together 

 in a vessel agitated in a freezing-mixture and keeping the am- 

 monia in excess, a solid mass is obtained which consists largely 

 of the amidosulphite, behaving as such in water, though mixed 

 with other substances, and quantitative analysis of which shows 

 that much more thiin three mois, ammonia to two mois, sulphur 

 dioxide have gone to its formation. If, instead of examining it 

 at once, it is kept for a long time in a gentle current of dry 

 nitrogen or hydrogen, at a temperature of 30° to 35°, it no longer 

 contains amidosulphite or gives any sulphite to water, and contains 

 not much more than one atom of nitrogen to one of sulphur. 

 Thus, Rose's results are explained and, at the same time, shown 

 to be of no direct significance. 



Products of the decomjjosition. — Both Hose and Forchham- 

 mer found ammonium sulphate to be a principal constituent of 

 the product of the interaction of the gases. A sufficiently high 

 temperature having been reached, this will have been the case ; 

 furthermore, the solution of the even less heated product slowly 

 becomes acid and full of sulphate. But when the temperature 

 has not been allowed to exceed 30°, or even 40°, the quantity of 

 sulpliate in the product is so small that it may almost be dis- 



