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toluene. On opening the tubes much hydrogen sulphide escaped and 
from the liquid obtained the xylene was distilled off. The residue 
became quite solid and apparently consisted of sulphur and a ery- 
stallised hydrocarbon. To remove the greater part of the sulphur, 
the hydrocarbon was dissolved in ether which was then distilled off. 
By recrystallising the residue from alcohol a mass was soon obtained 
which melted at 81—82°. Two determinations of the molecular 
weight by the freezing point method with benzene gave, respectively 
the values 200 and 205. No change took place on heating with 
hydrogen iodide in sealed tubes and no addition product was obtained 
on adding an ethereal solution of bromine. The product in fact 
appeared to be identical with p.p. dimethyldibenzyl p—CH, ©, H,CH,. 
CH, C, H, CH, — p. which Moritz and Wotrrenstuin ') had obtained 
by the oxidation of p-xylene with potassiumpersulphate. 
The result which was not analogous to that obtained with toluene 
caused us to repeat the experiment which now yielded a crystallised 
product which unlike the first substance was found to consist of a 
mixture of hydrocarbons. In order to completely eliminate the sulphur 
the mixture was boiled with solution of sodium sulphite, then dissolved 
in ether and after distilling off the same, the residue was treated 
with cold alcohol. The alcoholic solution again contained p.p. dimethyl- 
dibenzyl (m. p. 81— 82°) as was proved by repeated recrystallisations. 
The portion insoluble in cold alcohol was solved in boiling alcohol 
and by repeated recrystallisation a product was obtained which melted 
at 176—177°, yielded, on adding an ethereal solution of bromine, a 
bromine product melting at 208° and proved to be identical *) with 
p-p. dimethylstilbene p — CH, C, H, CH CH C, H, CH, — p. 
In order to find out the cause of the difference in these results a 
further investigation took place. As far as we were aware, the only 
difference between the two experiments was that this time the tubes 
had been repeatedly opened thus causing the removal of the greater 
part of the hydrogen sulphide. The temperature during the experiment 
was in both eases the same and constant between 200 and 210° ; 
the heating was also continued for about the same length of time. 
It was now possibie that originally in both cases p.p. dimethyl- 
stilbene had been formed. Whilst in the first experiment this sub- 
stance might have been almost completely reduced to p.p. dimethyl- 
dibenzyl by the action of the hydrogen sulphide, this reaction could 
only have occurred in a limited degree in the second experiment. 
1) Ber. D. Chem. Ges. Band 32. P. 2531. 
2) Gotpscumipt & Hepp. Ber, D, Chem. Ges, Band 5. P. 1504, 
