68 



Dr. Hofmaxm on Homologues and Analogues [Recess, 



however, this precipitate blackens, even at the common temperature, more 

 rapidly on heating, with formation of sulphide of silver. Simultaneously 

 the odour of ethylic mustard-oil becomes perceptible ; and if the liquid 

 be heated to ebullition, this oil distils in large quantity with the vapour of 

 water. The disengagement of sulphuretted hydrogen, which, is observed at 

 the same time, belongs to a secondary reaction, the unstable hydrosulphide 

 of silver (which is formed in the first instance) splitting up into sulphide of 

 silver and sulphuretted hydrogen. 



In this experiment no excess of silver should be used. Ethyl mustard- 

 oil, more especially upon protracted ebullition, exchanges its sulphur for 

 oxygen, thus giving rise to the formation of cyanate of ethyl, easily re- 

 cognizable by its fearful odour. Ultimately this ether is entirely decom- 

 posed into carbonic acid and ethylamine ; after some time the solution 

 contains nothing but nitrate of ethylamine. 



Most of the metallic ethyl-sulphocarbamates,more especially the copper and 

 mercury salts, behave exactly like the silver compound. I have almost inva- 

 riably employed mercuric chloride for preparing ethyl-mustard-oil. In this 

 case the hydrochlorate of ethylamine which is produced unites with the 

 excess of corrosive sublimate to form an insoluble compound. Accordingly 

 the ethylamine, which in this reaction is separated as salt, exists partly in 

 solution, partly in the precipitate ; it is easily recovered by treating with 

 caustic soda the residue which is left after the mustard- oil has been ob- 

 tained by distillation. When working with pure ethylamine, one half of 

 the base may thus be regenerated for a new operation. 



But it would be useless to employ pure ethylamine for this purpose. 

 The crude mixture of bases, which is obtained by allowing alcoholic am- 

 monia to stand for some time with iodide of ethyl and distilling the iodides 

 thus formed with an alkali, is very well adapted for this operation. This 

 mixture, as is well known, contains, together with ammonia, the primary, 

 secondary, and tertiary monamines of the ethyl-series. 



I have satisfied myself, in the first place, that diethylamine is just as 

 easily converted into ethylic mustard-oil as ethylamine. The experiment 

 was made with absolutely pure diethylamine prepared by means of diethyl- 

 oxamic ether. Bisulphide of carbon, more especially in alcoholic solution, 

 acts with great energy upon diethylamine, diethyl-sulphocarbamate of di- 

 ethylamine being formed, which, when treated by a metallic salt, furnishes 

 a metallic diethyl-sulphocarbamate together with a salt of diethylamine. 

 On ebullition, the former is converted into ethylic mustard-oil ; but instead 

 of the metallic hydrosulphide generated in the analogous metamorphosis 

 of ethylamine, in this case a mercaptide is formed. 



(C S)"(C a H ) N, (C H 5 ) 1 g_ C 2 H, 1 N C 2 H 5 V g 



I should not leave unmentioned, however, that the formation of mercap- 

 tide is still to be further proved by direct experiment. On working with 



