( 290 ) 
means of an ethereal solution of bromine. The result justified the 
belief that the formation of stilbene had taken place in a more simple 
manner than was formerly supposed, and according to the equation : 
2C,H, CH, +2S=C,H, CH:CHC, H‚ + 2H,S 
The thionessal found in the preliminary experiments might then 
have originated from the action of sulphur on the stilbene which 
according to Baumann and Krerr readily takes place at 250°. Fresh 
experiments in which toluene was heated with sulphur for hundreds 
of hours in sealed tubes at 200° yielded as sole crystallisable product 
a large quantity of stilbene which was obtained in a perfectly pure 
condition and of which the bromine addition product with the 
correct melting point was prepared. In connection with the results of 
the action of sulphur on xylene to be mentioned presently, we took 
into consideration the possibility that as a first product not stilbene 
but dibenzyl might have been formed according to the equation: 
2C, H, CH, + S= C, H, CH, CH, C,H, 4 H,S 
and efforts were made to isolate this if possible. As, however, 
according to the researches of Rapiszewsk1'), sulphur converts dibenzyl 
very readily into stilbene and as we had found by special experi- 
ments that this already takes place at 200° when a solution of 
dibenzyl in benzene is heated with sulphur and as we had also 
proved that this action does not take place at a temperature of 
140—145° we have heated sulphur with toluene in a sealed tube 
for eight days at 140°. As sole product we obtained stilbene besides 
hydrogen sulphide from which fact we are justified in concluding 
that by the action on the toluene two atoms of hydrogen are directly 
withdrawn and the two remaining groups are condensed to stilbene. 
Action of sulphur on p-xylene. When a solution of sulphur in 
p-xylene is boiled there is a much more perceptible evolution of 
hydrogen sulphide than on boiling a solution of sulphur in toluene. 
If, as in the previous experiment with toluene, the gas evolved was 
removed by means of a current of carbon dioxide and passed through 
an aleoholie solution of lead acetate 16 milligrams of lead sulphide 
(equal to 2.1 milligrams of sulphur) were obtained after boiling for 
an hour and a half. Here again there was no sign of any lead 
mercaptide; neither did the xylene solution ‘contain a mercaptane 
as was plainly shown by the fact that no reaction was obtained 
with mercuric oxide. We next proceeded to heat one gram of sulphur 
with 30 ce of p-xylene in sealed tubes for 120 to 160 hours at 
200 to 210° similarly to what was done in the experiment with 
1) Ber. D. Chem. Ges. Band 8. P. 758. 
