(>XlMll)(<SL'[-lMloXA'rKS (»1! S L'LPH AZOTATES. -^ß 



its equivalent of either hydroxide or carbonate. l^>iit in his memoir in 

 the Aininh'ii, [xiblished later, he makes no mention of this, and con- 

 demns Fremy's and Claus's similar processes as iDeing frequently un- 

 productive, althouoh Claus had also used equivalent quantities of 

 nitrite and hydroxide. Evidently he thought little of this method 

 because of its uncertainty ; yet, as we shall show, it is. when pro[)erly 

 modified, regularly very productive in the case of both sodium and 

 potassium salts, and indeed is the only one by wliich sodium oximido- 

 sulphonate can be isolated. 



Fremy prepared his ha sic salt nearly in the same way as his 

 neutral salt, varyino- this onlv to the extent of workino- with more 

 concentrated solutions, and so regulating the passage of sulphur 

 dioxide (assisted, it would seem, by addition of more potassium hydrox- 

 ide), that separation of crystals should take place with the solution 

 still strongly alkaline. Some care was required as to the degree of 

 concentration, which he adiusted bv beo-innino- witli solutions strono- 

 enough to deposit sulphaztite, and then adding just sufficient water 

 to redissolve this before passing in more sulphur dioxide. The 

 yield of salt was large. A secondary method of his was to make 

 sulphazate and salts allied to it and then treat these with water, 

 when the alkaline oximidosulphonate slowly crystallised from their 

 solution. 



Clans in following Fremy's main process could get the alkaline 

 salt only in admixture with the neutral salt and other compounds. 

 By fractional crystallisation it could indeed be separated from these, 

 but he preferred a modification of Fremy's secondary process, in which 

 salts nearly the same as Fremy's sulphazate, with their adhering alka- 

 line mother-li([uor, are boiled witli two or three times their volume of 

 water, the sc^lution filtered hot. and when barely cold decanted from 

 the crystals tliat have formed of the basic salt, Tliis Fremv-Claus 



