97 
in the remaining product was 1,75 °/,. It follows from this last 
experiment that the formation of sulphuretted hydrogen does not take 
place in this manner, that primarily sulphur vapour is split off, which 
reacts with the hydrogen. For if the sulphur combined with the carbon 
had an appreciable vapour tension at 900°, the generated sulphur 
vapour would be carried along by the nitrogen current, and then 
it would be possible to remove nearly all the sulphur from the 
carbon by heating in a nitrogen current, which is not the case. In 
the action of hydrogen on P, we have, therefore, to do with a 
specific action of the hydrogen, hence with a chemical reaction. 
§ 4. I then examined more closely the conditions under which, 
and the temperatures at which this fixation of sulphur by amorphous 
carbon takes place. These experiments have not yet led to a satis- 
factory insight into the proposed problem, and should, therefore, 
be considered as provisional. A series of experiments was arranged 
as follows: 
1.5— 2 grammes of a mixture of 75°/, amorphous carbon K, and 
25°/, sulphur was put in a porcelain boat, this boat was placed in 
a porcelain tube, which was in an oven heated beforehand at a 
definite temperature. The oven was then kept at this temperature 
for an hour, pure nitrogen flowing through the tube during this 
time; then the tube was cooled in a nitrogen current. This experi- 
ment was made at different temperatures (all above the boiling-point 
of sulphur), viz. at 500—-510°, at 610—590°, 670—710°, 900—940°. 
Most sulphur distilled from the boat for the greater part already 
at the beginning of the experiment. In the experiment at 500—510° 
no H,S-formation was observed; it was, however, observed in the 
experiments at 610—590° and at the higher temperatures. 
In all these cases the carbon recovered after the experiment had 
fixed no sulpbur or very little. Compare with this the preparation 
of P, ($ 2), in which a larger quantity of mixture of carbon + 
sulphur was placed in an oven heated at 510°, which temperature 
was slowly raised to 975°; in this latter case the contents of the 
porcelain tube will have assumed the temperature of 510° less 
rapidly, and the sulphur could, therefore, be fixed by the carbon, 
before all the sulphur had been distilled out from the mixture. 
The temperature at which the fixation took place in this expe- 
riment, cannot be ascertained. In the series of experiments mentioned 
‘in § 4 the small quantity of substance quickly assumed the tem- 
perature of the heated tube, the sulphur evaporated almost imme- 
diately after the boat had been pushed into the oven, the time during 
7 
Proceedings Royal Acad. Amsterdam. Vol. XXIV. 
