IWIDOSULPHONATES. 59 



He \vc\à found that paras ulphatammon, as it cooled after ])eing' prepar- 

 ed by heat, took uj) ammonia if in contact with it, and tliat the 

 flocculent matter, named sulphatammon by Rose, would lose from six 

 to nine percent, of its weight, in a vacuum over sulphuric acid, leaving 

 a residue giving up more ammonia Avhen heated to 100,° and then 

 consisting of parasiilphatammon, as already mentioned. But he treat- 

 ed these phenomena as a case of the physical abs()r])tion of gases by 

 porous solids, and likened the ammonia lost or taken up to hygroscopic 

 moisture. Yet a compound of two molecules of sulphur trioxide with 

 four of ammonia has to lose as ammonia only .seven and a half per 

 cent, of its weight in order to become a compound of two molecules 

 of sulphur trioxide with three of ammonia. As for the high loss of 

 nine per cent, recorded, that if correctly observed may have been due 

 to loss of moisture, for, as Rose found, sulphatammon is markedly 

 hygroscopic and loses the moisture again at 100.° 



Sixteen years later, Woronin first established the accuracy of 

 Eose's analysis of tlie flocculent matter, sulphatammon, and then 

 showed that this and parasulphatamnK^i were different salts of the 

 same acid. Another sixteen years later, Berglund claimed for sul- 

 phatammon that it nuist be triammonium imidosulphonate, since 

 pnrasulphatanimon had pnn'ed to be diammonium imidosulphonate. 

 But then, opposed to this conception of its nature tliere were the facts, 

 first, that Hose had made no admission of its evolving ammonia when 

 dissolved in water and evaporated so as to yield parasulphatammon; 

 secondly, that llaschig much more recently had dissolved an old s])eci- 

 men of parasulphatammon in anuiionia -water and on evapoi-ation oN-er 

 sulphuric acid got only ])arasulpliatanunon again ; and, lastly, known 

 \n ourselves at least, that trisodiinu, or tripotassium, or triargentum 

 imidosulphonate when decom])osed by ammonium-chloride solution 

 sets free much ammonia. It seemed to us. therefore, at first to be as 



