IMIDES OF BENZENEDISULPHOiVIC ACIDS. 21 



for the imide, showing that the crystals were nothing but the 

 pure imide. 



p-Benzenedisulphoxime also gave a similar result. This 

 substance is almost insoluble in fuming nitric acid ; yet, on 

 allowing the mixture to stand from five to ten days a small 

 quantity of the compound was changed into the corresponding 

 imide. Although the quantity produced was so small that it 

 was difficult to isolate it, its presence could be proved by the 

 formation of the almost insoluble potassium salt on neutralising 

 the diluted solution with caustic potash. 



A notable quantity of sulphuric acid was found in the nitric 

 solution in both cases. This is perhaps due to the complete 

 decomposition of the oximes. 



The unexpected reducing action of fuming nitric acid upon 

 the disulphoximes here observed may be due to the lower oxides 

 of nitrogen which exist in the acid. But further investigation is 

 necessary to settle the question. 



In concluding this counnunication, the author desires to 

 express his great obligation to Prof. Haga, who has taken a 

 great interest in the work and aided him with valuable advice. 



