284 E. DIVEES AND T. HAGA : 



Claus's statement that some potassium sulphite neutral to litmus 

 was as active upon nitrite, after lie had added potasli in * excess ' 

 to it, as it was before only requires us to assume that the excess 

 spoken of was large enough to give the solution a markedly 

 alkaline action upon litmus and yet small enough to leave much 

 pyrosulphite unchanged. 



I. — h. Poiassluni Hydroxide not a Factor in the Formation of 

 the Sidphazotued Salts. 



That a normal sulphite, potassium or sodium, remains still 

 inactive upon nitrite, when alkali hydroxide is added, was ascer- 

 tained by leaving the three substances together in solution in a 

 closed flask for some time, as in the experiments where no 

 hydroxide was present, and then precipitating with barium chlo- 

 ride after addition of ammonium chloride, and finding no sulphur 

 compound left in the filtrate. (Ammonium chloride prevents 

 precification of hydroximidosulphate, this Journal 7, 48, 69). 



On the many occasions we have had to prepare sulphazo- 

 tised potassium salts by submitting solutions of nitrite and hydrox- 

 ide to the action of sulphur dioxide, taking care to keep the 

 solution briskly agitated, we found that, even in ice-cold solu- 

 tions, precipitation of these very sparingly soluble salts only 

 began from the point at which there was no more hydroxide 

 left, and then went on freely until the solution had become 

 neutral to lacmoid paper. In proportion as the hydroxide dis- 

 appeared, sulphite became abundant, whilst from the time that 

 the replacement of hydroxide by sulphite was complete, the 

 quantity of sulphite steadily decreased as the sulphazotised salts 

 formed, sul})hazotised sodium salts being very soluble no preci- 



