288 



separation, during the principal phase of this process, of disulphide 

 of carbon, and therefore, in consequence of a secondary reaction, of 

 sulphuretted hydrogen which, more especially during the latter 

 stages of the operation, is apt to accumulate to a very considerable 

 extent in the liquid. Three molecules of the red disulphide-of- 

 carbon-compound, and one molecule of sulphuretted hydrogen con- 

 tain the elements of one molecule of disulphide of carbon, two mole- 

 cules of sulphide of triethylphosphine and one molecule of the yellow 



3C 7 H 15 PS a -j-H 2 S=CS 2 +2C 6 H 15 PS + C 8 



Red crystals. Sulphide. Yellow crystals. 



That the formation of the yellow crystals is actually due to the 

 action of sulphuretted hydrogen is unequivocally proved by a syn- 

 thetical experiment. The red disulphide-of-carbon-compound, when 

 digested at 100 in sealed tubes with a saturated solution of sul- 

 phuretted hydrogen, is rapidly converted into the yellow crystals. I 

 have thus succeeded in preparing considerable quantities of this 

 substance, of which, as long as it was only obtained as a secondary, 

 I might almost say accidental, product of the reaction, I had great 

 difficulty in procuring a sufficient quantity for analysis. 



The constitution of the yellow crystals, like that of the red com- 

 pound from which they originate, is rather obscure. I have already 

 pointed out on a former occasion that the red compound may be 

 viewed as the primary triethylphosphonium-salt of sulphocarbonic 

 acid minus one molecule of sulphuretted hydrogen, 



P] J CSs _H J S=(C2 H 5 ) 3 P, CS, 



If we imagine a sulphocarbonic acid in which one equivalent of 

 hydrogen is replaced by the monatomic radical CH 3 S (methylene- 

 mercaptam minus the molecular residue of sulphuretted hydrogen), 



TT \ 



Sulphocarbonic acid . . TT i C S 3 , 



Sulphomethylsulphocar- (C H, S) 1 ^ 

 bonicacid.... ..... H J CS " 



the yellow crystals may be viewed as the triethylphosphonium-salt 

 of sulphomethylated sulphocarbonic acid minus one molecule of sul- 

 phuretted hydrogen, 



