OXIMIDOÖULPHONATES OK «ULPHAZOTATES. 55 



founded in fact, the dipotassiiim salt always preceding it and then 

 only yielding it by alkaline treatment. 



The five-sixths potassium salt forms rhombic plates, crystallising 

 in masses on the walls of the vessel. It is only sparingly soluble in 

 water. It was analysed by Fremy and l)y Claus with results identi- 

 cal ns to the sulphur and not greatly differing from each other as 

 to the potassium. Raschig got results for potassium exactly 

 intermediate to theirs, but for sulphur one per cent, less than they got; 

 and he rightly gave to the composition of the salt a molecule of water, 

 although Claus had emphatically stated it to be anhydrous, having 

 found that it can be heated to 120" without any change or loss of 

 Aveight. Raschig, however, so far from establishing the presence of 

 this molecule of crystallisation-water, wrote of the salt that it ' remains 

 w^holly unchanged at 120°,' a statement almost the same as that 

 which Claus had made in proof that it contained no water. The 

 facts, we firid, are that it does lose in weight when heated, in fine 

 powder, to 120°, and therefore contains water, but, as is usual in our 

 experience with sulphazotised salts, it gives up this water very slowly. 

 We further find that at 120° it slowly increases in weight again by 

 re -taking water from the atmosphere and in doing so becomes hydro- 

 lysed and acid. When the hydrated salt is rapidly raised to, and 

 maintained at 120°, such hydrolysis also occurs and thus fixes the 

 water, causing the salt to suffer scarcely any change in weight. 



The results of our determinations of sulphur and potassium agree 

 with tliose got by Raschig, but with the potassium a little lower than 

 the calculated number. As our methods of getting our preparations 

 were somewhat exceptional, we submit the results of our analyses 

 along vvith those got by the other investigators, also interesting from 

 the peculiarities noticed of their agreements and variations : — 



