3g E. DIVERS AND T. HAGA. 



half the total loss of weight, in 2^ hours, at 95°, and the whole, or 

 20 °/o5 n °t before the salt had been heated twelve hours. Thus, the loss 

 in weight is slow, and a heat, mistaken for 110° (107°), maintained for 

 only a few minutes, would have had so small an effect as perhaps, to 

 have deceived Pelouze. When the salt does suddenly decompose, a 

 marked rise of temperature accompanies the change, and this may 

 have caused him to name 130° as the decomposition point. If these 

 suggestions are rejected, as to how Pelouze's statements may be 

 explained away, we have still in this difference in behaviour to heat, 

 the only one unaccounted for between Hantzsch's and Pelouze's 

 preparations. 



From Pelouze's account it is to be inferred that, while in presence 

 of moisture and acids, potassium nitrososulphate decomposes into 

 potassium sulphate and nitrous oxide, it is converted by dry heat 

 wholly into sulphite and nitric oxide. Hantzsch has found, however, 

 that by dry heat not more than 20-26 % of the salt is changed into 

 sulphite and nitric oxide, the rest becoming sulphate and nitrous oxide. 

 But there is nothing to show that Pelouze worked quantitatively 

 in the matter. Besides, Hantzsch himself has found that silver- 

 potassium nitrososulphate does wholly decompose into sulphite * and 

 nitric oxide by heat, thus greatly lessening the weight that might be 

 attached to this supposed difference. 



Heating the salt in dried hydrogen until it exploded at 108° we 

 got results showing that 28.2 in one case, and 29 parts per 100 in 

 another case, had been changed into sulphite. Our mode of working, 



* Impressed by the stability of silver-potassium sulphite, Hantzsch is led to recognise 

 in it that constitution which one of us and Shimidzu, unknown no doubt to him, had long 

 since given it (J. Chem. Soc. 49. 581). Further, that it is like the mercury sulphites, which 

 according to Barth, he says are sulphonates. We not only agree with this view of the constitu- 

 tion of these salts, but would point out that Barth in the paper quoted by Hantzsch, fully 

 credits Divers and Shimidzu with that view, and then adopts it and confirms it. 



