101 
sulphur; this sulphur-content could be reduced to 2,7 °/, by heating 
in vacuum, but remained then constant. Its behaviour towards oxidizers 
was perfectly analogous to that of the carbon sulphide described in 
§ 2. These experiments, which are still to be confirmed by a new 
series will be described later. 
§ 6. These carbon sulphides obtained synthetically present a close 
resemblance with coal-coke, for so far as the sulphur-content is 
considered. The sulphur fixed to carbon in coal-coke is very resistent 
to oxidizers and cannot be expelled by heating. 
In a recent research Powe1l.’*) has shown that the sulphur content 
of coke can be considerably reduced by leading hydrogen over the 
coke at 500—1000°, which caused the sulphur fixed to carbon to 
be transformed into sulphuretted hydrogen for a large part. His state- 
ment?) that sulphur-free coke can combine with sulphur when 
heated in a mixture of hydrogen and sulphuretted hydrogen, and that 
there is equilibrium between the carbon-sulphide and the sulphur 
vapour, cannot be judged until the experiments have been further 
described. 
In conclusion | will mention the product that Stock and Praetorius *) 
obtained in their research on the carbonsubsulphide (C,S,). This 
carbonsubsulphide polymerizes to a black mass of unknown molecular 
weight. On heating this carbon-like substance to dark redness CS, 
and C,S, escaped ; but there remained a carbon-like mass that contained 
39°/, sulphur. A closer examination of such a product and its 
behaviour at prolonged heating will be of interest. 
1) Journ. of Ind. and Engin. Chem. 12, 1077 (1920). 
2) Ibid 13, 34 (1921). 
3) Ber. 45, 3569 (19) 2). 
