208 E. DIVEES AjSTD M. OGAWA : PRODUCTS OF HEATING 



dioxide. Some repetitions of the experiment gave almost the same 

 results. Calculation and the results of one experiment gave the 

 following numbers : — 



If, in the formation of this complex, no longer losing 

 material quantities of ammonia and water, only these products 

 had been given off, the residue should have been 8472 per cent, 

 of the hydrated normal sulphite, whereas it proved to be little 

 more than 79 per cent., in consequence of volatitisation of some 

 of the (dissociated) salt, made manifest by the production of a 

 little sublimate. 



After renewing the heating in a fresh subliming-tube, allow- 

 ing the temperature to rise slowdy from 120° to 150°, the residue 

 had almost all disappeared in two hours, while an abundant dry 

 sublimate had deposited. For some time during this heating, 

 sulphur dioxide steadily escaped, but practically ceased to do so 

 long before sublimation was finished. The residue left when 

 sulphur dioxide was no longer coming oft', proved on analysis to be 

 normal sulphite again, but only half hydrated, 2(NH4)2S03, OH2. 

 The sublimate, also, now and at the finish, consisted of 

 normal sulphite, apparently anhydrous though found to be a 

 little hydrated because it is very hygroscopic and had unavoid- 

 ably some exposure to the air while it was being scarped out of 

 the tube into the weighing bottle. 



Hydrated ammonium sulphite, therefore, becomes by gra- 

 dual heating to 120° converted one-third into the anhydrous 

 salt, and one-third into pyrosulphite, by loss of w^ater and am- 

 monia ; and then the nearl}^ stable complex of these salts with 



