99 
fixed by carbon both at 550° and at 885°. The influence of time 
and temperature will be decided by further experiments. 
5. The experiments described may be interpreted in different 
ways. The sulphur may have been: absorbed by the carbon or 
fixed by chemical forces. Let us first consider the former case more 
closely. Amorphous carbon is an exceedingly efficient absorbent for 
various gases’), why should not sulphur vapour be absorbed? 
By absorption is understood a reversible phenomenon; the absorbed 
gas is condensed on the absorbent, and has remained unchanged in 
its chemical properties. 
The fact that the carbon does not lose its sulphur-content at 
1000° and 1 mm. pressure is not conclusive against the assumption 
of absorption. For if the absorption-isotherm has an asymptote in 
the axis of coordinates, it is possible that the last rests of 
absorbed substance (in this case 2°/, sulphur) are practically not to 
be removed. The influence of the temperature and the time during 
which the sulphur vapour is in contact with the carbon, on the 
quantity of sulphur which is fixed, will have to be studied more 
closely to render it possible to draw a definitive conclusion in this 
respect. The behaviour of the fixed sulphur towards hydrogen, 
however, seems to me an argument in favour of the sulphur being 
fixed to the carbon by chemical forces. By the action of hydrogen 
on the sulphur-carbon complex sulphuretted hydrogen is formed. In 
this reaction it must be assumed that the hydrogen reacts with the solid’ 
phase. For the sulphur vapour tension of the sulphur. carbon complex 
is still very small at 900°, otherwise finally all the sulphur would 
be expelled in gaseous form by heating in a nitrogen current 
at that temperature. For the same reason the sulphur cannot be 
assumed to be in the carbon in a solid solufion having a ceriain 
vaponr-tension. In this case, too, it would be incomprehensible why 
the sulphur could be expelled by hydrogen, and not by nitrogen. 
Also the fact that by treatment of the product P, with 
bromine water only a. small part of the sulphur is oxidized, is 
difficult to reconcile with the idea of absorption. 
I assume for the present that the sulphur is bound to the carbon 
by chemical forces, and propose to designate the carbon-sulphur 
compound formed in this way for the present by the name of carbon 
sulphide. Nothing can be concluded with regard to the composition 
1) This holds: at least for charcoal, animal charcoal and such substances, 
Whether also pure amorphous carbon is a. good absorbent, does not seem to 
have been decided as yet. . 
7* 
