POTASSIUM N1TROSOSULPHATE. ()} 



separated with care, by evaporating the mother-liquors of potassium 

 nitrososulphate almost to dryness, with sometimes the addition of 

 alcohol ; while without precautions to keep the nitric oxide colourless 

 and all air absent, this salt forms quickly in notable quantity. Now, 

 did Raschig take these precautions ? Presumably he did, but there is 

 nota word in his memoir to show that he was conscious of this liability 

 to err, or that he took any such precautions as, for instance, were 

 taken by Hantzsch, to have his nitric oxide pure. Until something 

 more definite cun be stated of the way to form such an isomer of 

 Pelouze's potassium nitrososulphate as Raschig has described, its 

 existence remains unproved ; for his preparation, for aught he has 

 shown, could have been Pelouze's salt mixed with some such salt as 

 his own potassium dihydroxylamine-sulphonate. 



In a short paper, published some years ago (J. Chem. Soc., 

 47, 364) we made known the fact that, although the alkali 

 nitrososulphates had appeared, hitherto, to be incapable of bearing 

 ordinary double decomposition with other salts, we had yet found 

 them capable of a few such changes, resulting in the precipitation 

 from concentrated solutions of a barium and of a lead salt. No 

 quantitative analysis of these salts was given. It was also there 

 mentioned by us that silver nitrate, unlike copper sulphate, does not 

 at once cause decomposition of alkali nitrososulphates. The title of 

 our note is The Existence of Barium and Lead Nitrososulphates. 



Now, in introducing the account of his preparation of barium- 

 potassium and silver-potassium nitrososulphates, Hantzsch does indeed 

 refer to that note, but only to say that, according to us, salts of the 

 heavy metals cannot be prepared ; thus, actually reversing our state- 

 ment, and leaving unmentioned the above results of our work. 



A new point about nitrososulphates which, small in itself, may 

 yet prove of significance in settling their constitution, is that their 



