POTASSIUM NITRITO-HYDROXIMIDOSULPHATES. 213 



explosively when heated — more so than does the hydroxiraido- 

 siilphate by itself — giving off almost colourless gases and white 

 fumes, just as might be expected and just as does a dry mixture 

 of its constituent salts in corresponding proportions or a mixture 

 of nitrite with a little sulphite. 



The compound salt can be purified from other salts or from 

 alkali when these are present by recrystal Using from strong 

 enough potassium nitrite solution. But from its own mother- 

 liquor it can bo separated only by draining on the tile and not 

 by washing. Such draining however is very effective because of 

 the felted fibrous form of the salt, its non-deliquescent natuie, 

 and the hygroscopic character of a solution of potassium nitrite. 

 The analysis of the salt was made in the usual way described 

 in our previous papers on hydroximidosulphates and other 

 sulphonated-nitrite derivatives. By boiling its solution with an 

 acid most of its sulphur appears as ordinary sulphate, but not 

 quite all ; so that in estimating the sulphur the solution must be 

 hydrolysed for some hours at 150"' under }>ressure. The results 

 of analysis were :— 



There are other ways in which the potassium iiitrito- 

 2/3 normal hydroximidosulphate may be formed all cousistino- 

 essentially in producing the hydroximidosulphate by sulphonatins; 

 a small portion of the potassium nitrite in a concentrated solution. 

 Thus the following mode of working will give good results with 

 certainty but it may be wideh^ deviated from with due conside- 

 ration and precaution provided only that a concentrated solution 



