44 Ë. DIVERS AXlJ T. HAGÀ. 



100" without iDeing changed. The alkaline salts, though they contain 

 water, may be heated also without change to 100" ov a little above. 



About 105° for the two-thirds normal salts and 110° tor the 

 alkaline salts, (jximidosulphonates slowly take moisture from the air, 

 increase cc^nsequently in weight, and become hydrolysed and acid. 

 In this behaviour they are like imidosulphonates (This Jouni..^ 6, (M). 

 Claus observed that the dipotassium salt gained thus in weight, but 

 set this down t(3 absorption of oxygen, lîut :iny oxidation would be 

 attended with a loss of nitrogen or oxides of nitn^gen much more in 

 weight than the oxygen absorbed. P)esides, we tind that, heated for 

 hours at 120° in a current of well-dried air, oximidosulphonates, even 

 the two-thirds normal potassium salt, gain nothing in weight. 



The effect of higher temperatures was investigated by Claus, who 

 found that the anhydrous dipotassium salt gives olf some acid-reacting 

 vapoiu' not sulphur dioxide, that (3n further heating a little am- 

 monium sulphate sublimes ( ! ), and that the residue then consists 

 a])parently of potassium pyrosulphate. Mis experience on heating 

 the tive-sixths normnl [lotassium salt was. that abo\e '20(f the 

 crystals swell up and s])ring asunder, gi^e first nitric oxide and then 

 ammonium sulphate, and leave a residue which does not fuse and is 

 normal potassium sulphate. Freniy, Claus, and Raschig all state that 

 this salt decom])Oses suddenly at al)out :^00° (150° Raschig) with 

 develojmient of red vapours. 



We have experimented more particularly with the sodium 

 oximidosulphonates, the disodium salt being better fitted than the 

 dipotassium salt for testing the eifects of dry heat upon oximidosul- 

 phonates because it is anhydrous. With the object of c(jllecting the 

 resulting' cruses the heatino^ has been conducted in a vaciunn as well as 

 in open vessels. 



Tlie dried normal sodium salt remains unchanged until the tem- 



