196 E. DIVERS AND M. OGAWA : 



regarded. Along with sulphate, trithionate was considered by- 

 Rose to make up most of the product, for the aqueous solution 

 of the mass always gives a strong reaction with silver nitrate 

 which might be that of trithionate and, in the case of his pro- 

 duct, gave other reactions of a trithionate. But when the pro- 

 duct has been carefully prepared and is free from amidosulphite, 

 its solution gives the silver reaction without the others belonging 

 to a trithionate. Thus, the solution may be acidified and left 

 for hours without yielding more than mere traces of sulphur 

 dioxide and sulphur ; to get these in quantity, the solution had to 

 be strongly heated under pressure. Besides this, the absence of 

 sulphate in the solution is of itself almost enough to disprove 

 the production of trithionate, since, as Hose himself represented, 

 sulphate and trithionate are complementary products of the de- 

 composition. 



Heating pure ammonium amidosulphite gives the same re- 

 sults as heating the coloured product of the union of sulphur 

 dioxide and ammonia as gases. Rose's assertion that the product 

 is a single substance, even in appearance, is certainly incorrect, 

 according to our experience. By the union of the gases in a 

 receiver kept well cooled, the product is deposited as a soft, 

 waxy, yellow coating on the walls of the vessel and on the gas 

 tubes. Its colour varies in different parts from nearly white to 

 orange-red somewhat irregularly but generally so as to be whiter 

 near where the ammonia enters, the whiteness not being due to 

 moisture in the gases, as Rose assumed. When the product gets 

 to 30-35°, whether by its own heating or by external heat, it is 

 decomposed at first into an obscurely crystalline white solid and 

 a much smaller quantity of a coloured, effervescing liquid, partly 

 draining to the bottom of the vessel ; after a time all becomes 



