(9907) 
For this investigation a solution of p.p, dimethylstilbene in benzene 
was saturated with hydrogen sulphide, introduced into tubes the air 
of which was totally displaced by hydrogen sulphide and after sealing 
the tubes, the contents were heated for 40 hours at 200°. From these 
tubes there indeed was obtained, besides unaltered p.p. dimethyl 
stilbene, a product which proved to be identical with p.p. dimethyl- 
dibenzyl. This showed that under the given circumstances the expected 
reaction might have taken place. 
On the other hand, dimethyldibenzyl was heated with a solution ot 
sulphur in benzene for 40 hours at 200° and, although it was not 
yielded in a quantity sufficient to admit of a thorough purification, p.p. 
dimethylstilbene was obtained; at all events a hydrocarbon melting 
between 140° and 150° which absorbed bromine and yielded a product 
melting between 185° and 192°, whereas the melting point of p.p. 
dimethylstilbene dibromide is situated at 208°. From these experi- 
ments it is, therefore, probable that the formation of stilbene is here 
the primary and that of dibenzyl the secondary reaction, but we here 
got no certainty about this. 
On repeating the experiments on the action of sulphur on p-xylene 
in sealed tubes some of which were opened from time to time unequal 
proportions of stilbene and dibenzyl were still obtained, but the result 
of the first experiment (nearly exclusive formation of dibenzyl) was 
never again obtained. 
It should be mentioned here that p.p. dimethylstilbene was often 
obtained in two different forms. Generally, it was a coarse crystalline 
powder, but occasionally it consisted of very thin leaflets with a silky 
lustre and showing a violet-coloured fluorescence. The original form of 
both was retained after reerystallisation from alcohol. Once we succeeded 
after a good deal of trouble to convert the coarse granular form by 
grafting, into the silky condition. The melting point of both forms 
was identical. On treating them with an ethereal solution of bromine 
they both gave the same bromine addition product. To see whether 
this was a case of stereo-isomery, solubility determinations were made 
of both modifications in absolute alcohol at 25°. In both instances 
the same solubility value. was found, namely 0.21 part per 100 parts 
of alcohol 5. Notwithstanding the difference in appearance which was 
also retained in these solubility experiments, a stereo-isomery has 
thereby been rendered very improbable. 
1) Exps (Journal f. Pract. Chemie. Neue Folge Band 39. P. 299 and Band 47. 
P. 46) gives the solubility of p.p. dimethylstilbene in alcohol at the ordinary 
temperature as 0.76 per 100. 
