( 294 ) 
The melting point was constant at 55—56°. 
That the obtained hydrocarbon was really m.m. dimethylstilbene 
was proved by adding bromine to its ethereal solution which imme- 
diately yielded erystals of the dibromide with the previously found 
constant melting point of 167—168°. 
The ethereal liquid from which the dimethylstilbene bromide was 
precipitated, contained, of course, free bromine from which it was 
freed by treatment with aqueous potash. After distilling off the ether, 
the liquid was submitted to fractional distillation when hydrogen 
bromide was evolved owing to the presence of brominated products. 
The hydrogen bromide present in the distillate was removed by 
treatment with aqueous potash and the liquid distilled once more. 
When it appeared that this distillate, passing over between 298° and 
302° was not yet free from bromine it was dissolved in toluene and 
boiled for three hours with sodium wire which completely removed 
the bromine. The liquid then showed a constant boiling point ot 298°. 
On analysis was found: 
CA 30 SBE 
Caleulated! for Catan 20 LG OUA ELST: 
Two determinations of the molecular weight by means of the lowe- 
ring of the freezing point in benzene gave 201 and 199; calculated 
210°. All data agree with those of VorrrarH and those of Morirz 
and Wotrrenstein for m.m. dimethyldibenzyl. Only the boiling point 
was found to be two degrees higher. 
From this it, therefore, appears that m-xylene on treatment with 
sulphur yields stilbene as well as dibenzyl as discomposition products. 
To ascertain whether stilbene was here also the first product, 
m.m. dimethyldibenzyl was submitted to the action of sulphur by 
boiling it with this in a reflex apparatus. The product of the reaction 
dissolved in ether and treated with bromine did not yield a trace 
of the characteristic m.m. dimethylstilbene dibromide. This sub- 
stance could not even be recognised by means of the microscope. 
From this we think we may come to the conclusion that during 
the action of sulphur on m-xylene the first product is most proba- 
bly stilbene and that dibenzyl is a secondary product formed by the 
reducing action of hydrogen sulphide. 
The results of this research are, as we believe, a confirmation of 
the opinion expressed by ARONsTEIN and Merinuizen in their treatise 
on the molecular weight of sulphur. A trifling action of the sulphur 
on toluene and xylene must cause a derivation of the molecular 
weight in the direction previously found. One mol. of sulphur causes 
the formation of 8 mols. of hydrogen sulphide and 4 mols of stilbene. 
