AMIDOSULPHONIC ACID. 237 



of them are exceedingly soluble, and form supersaturated solutions 

 (Berglund). They are stable, even in solution, so far as we have observed, 

 except the ammonium salt, which is liable to hydrolyse, if not quite dry. 

 Their solutions maybe kept for hours at 100°, or even be boiled, with- 

 out showing decomposition. The behaviour of some of them, when 

 heated in absence of water, will be described after that of the acid 

 itself. 



A double salt of sodium sulphate and amidosulphonic acid has been 

 obtained by us at times in the course of preparing amidosulphonic 

 acid and separating it from its sodium salt by sulphuric acid ; but 

 experiments, made to determine the conditions for its production at 

 will, have been unsuccessful. When obtained by us, it had crystallised 

 from a strongly acid solution, and formed short, thick prisms, some- 

 what deliquescent. Its analysis showed it to have the composition of 

 6 mol. amidosulphonic acid with 5 mol. disodium sulphate, and 15 

 mol. water. 



This complex may have been only a crystal compound, but it 

 could not have been a mere mixture, because of its form, its apparent 

 homogeneity, and its content of water. It may be written as — 

 H 2 NSO B H + 5(NaO.S0 2 .NH 2 .HO.SO,.ONa, 30H 2 ), which, if the 

 one mol. of amidosulphonic acid be neglected, is a salt analogous to the 

 well-defined and stable ammonium sodium sulphate, formed under 

 similar circumstances, the sodium :unidosulphonate representing am- 



