( oU ) 



In order to deteriiiiiie in wiiat |ir(i)M)rtioii nrtlm- and /////vdininio- 

 tolueiie are present, it was necessary to i-enio\e the ben/vl bromide 

 from the mixture. Tiiis was done by l)rin,ij:iiiji' it into conlaet with 

 (limethvlanilino. Thei'c is iheii tnrnied t|iiaiililati\ eiy an amnioninm 

 bi'Oniide, the bulk ul' which is ile|i(>siled as a civslalline mass. By 

 washing- tlie residual li(|uid with \cr\ diiiilc nitric acid the excess 

 of dimethyl aniline ami tlic still diN>(il\('d ammonium l)romide 

 ai*e remoNcd so liial we olilain linally a li(|uid consisting merely of 

 tlie .bromotoluenes. When dried ami distilled in vacuo it is i-eady 

 for the determination of I lie isomers. This was done by determining 

 the solidifying point of this puritied liquid. By means of the solidi- 

 tying point curve previously constructed l)y Dr. v.\n ukk Laan, the 

 composition of the mixture could be at once ascertained from the 

 said point. By the analysis of a series of made up mixtures he was 

 satisfied that this method of analysis gives results accurate within 

 about 1 percent and is tlierefore sufüciently accurate for the purpose 

 intended. 



With the aid of the method described Dr. van oioh Laan obtained 

 the following results. 



1. Influence of ienijieriitnre. The llask containing the nnxture of 

 bromine and toluene was kept carefully in tiie dark. Observations 

 were made a( 25°, 50°, 75° and 100°. At 25° the reaction took 

 place very slowly and even after a week the bromine had not alto- 

 gether disappeared. A I 50° this was already I lie case in 3 days. 

 The subjoined table contains the anal^'ses of liie reaction mixtures. 

 The ligures given are each the mean of 8 or 4 concordant deternnnations. 



From this it appears that in tiic dark a regular iiicrease of the 

 benzyl bromide content lakes place with a rising temperature. From 

 a graphical extrapolation ii appeal's liiat itenzyl bromide is no longer 

 formed below 17°, bul, on the olliei' hand, aliove H3° it is Ihe sole 

 i-eaction product. These conclusions. ht)wevcr. must still be coniirmed 

 experimentally. The pi-oporlion in w liich c////»- and /^'^/vdiromololuene 

 are formed also alters somew lial in lavdur of Ihe tirst-nained isomer. 

 A determinalion of the s|». gr. of Ihc mixture showed that this does 

 not contain any of the higher brnniinaleil sul)slances. The mixture 

 obtained at 25° iiad a s|i. lir. of 1.35it.s at (i4°.(J whilst a mixture of 

 the two isomers in the same projporlion shows a sp.gr. of 1.3598 

 at 64°. 



2. Iii/hience of /ii//il. As already ob.scrxcd, ScnKAMM claims to 

 have obtained excbisi\ely brn/ylbromide when brominaling al low 

 tempei'ature in full sunlight, although his experimental dala create 



