428 



Dr. A, W. Hofmann on the [June 20, 



A second platinum-salt exists which only differs from that just mentioned 

 by containing two molecules of hydrochloric acid. This salt was accidentally 

 obtained in an attempt to decompose the ethylene sulpho-urea by sulphuric 

 acid. The urea was heated with the concentrated acid until sulphurous 

 acid began to be evolved ; on adding platinum chloride to the solution 

 after it had been diluted with water, a difficultly soluble platinum-salt was 

 formed, crystallizing in beautiful long needles. At the first glance this 

 appeared to be the platinum-salt of a new base, but on examination it was 

 found to contain the original sulphur compound. It is represented by 

 the formula 



2(C 3 H 6 N 2 S,HCl),PtCl 4 . 



On decomposing this platinum-salt by sulphuretted hydrogen a chlorhydric 

 solution was formed, from which platinum chloride precipitated the original 

 amorphous salt, and which on evaporation left the original ethylene 

 sulpho-urea ; this was identified by its bitter taste and by a determination 

 of its melting-point. It is not easy to form an idea of the manner in which 

 sulphuric acid acts in this case, as the needle-shaped platinum-salt is not 

 produced in the presence of chlorhydric acid alone, even when very concen- 

 trated and in large excess. 



On comparing the composition of ethylene sulphocarbamide with that 

 of ethylenediamine on the one side and that of ethylene mustard-oil on the 

 other, it will at once be seen that the new body occupies a position inter- 

 mediate between the two : 



C 2 HJ C 2 H 4 ] C 2 H 4 ] 



ir c n!r §h 



The idea naturally suggested itself of procuring the mustard-oil by the 

 further action of carbon bisulphide on ethylene sulphocarbamide ; but al- 

 though numerous experiments have been made in this direction under varied 

 conditions, hitherto all these attempts have been without success. Digestion 

 with carbon bisulphide alone or with carbon bisulphide and lead oxide 

 produces no result ; nor is the sulphur compound changed by treatment 

 with potassium xanthate under pressure. In every respect the body ex- 

 hibits remarkable stability ; indeed all endeavours to remove the sulphur by 

 the action of metallic oxides or of ammonia, even under pressure at a very 

 high temperature, have hitherto failed. 



An experiment may here still briefly be mentioned by which the formation 

 of the body sought for was aimed at in another way. As is well known, 

 ethylic mustard-oil may also be procured from diethylsulpho-urea when 

 ethylamine is eliminated from this compound, and thus a further reaction 

 appeared to present itself which might be made available for the production 

 of ethylene mustard-oil. An ethylene sulpho-urea corresponding to four 

 molecules of ammonia and having the formula 



(C 3 H 4 )"fN 4 



