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V. " On the Action of Dibromide of Ethylene on Pyridine." By 

 JOHN DAVIDSON, Esq. Communicated by Dr. HOFMANN. 

 Received May 24, 1861. 



Pyridine, as is well known, has been obtained in the destructive 

 distillation of coal, of certain varieties of shale, and of animal sub- 

 stances. The specimen with which I worked was obtained from 

 coal-tar, and separated by distillation from the picoline : it boiled 

 constantly at 118'5C. 



A mixture of pyridine and dibromide of ethylene gradually 

 darkens, and at last becomes brown ; no crystals, however, are de- 

 posited ; on the other hand, the reaction proceeds with rapidity at 

 100 C. After the lapse of three hours the mixture is converted 

 into an almost black crystalline mass, from which, by successive 

 treatment with cold, and crystallization from hot, alcohol, a beautiful 

 bromide, crystallizing in silky plates, is obtained. In preparing this 

 bromide, it is advisable to add to the mixture of the anhydrous sub- 

 stances about one-fifth or one- sixth of its volume of alcohol, and to 

 digest in sealed tubes. The whole liquid solidifies in this manner 

 into a silky crystalline mass, which is only very slightly coloured. 



The crystalline bromide is extremely soluble in water ; I did not 

 succeed in getting crystals from the aqueous solution. It is very 

 soluble in boiling, but dissolves only slightly in cold alcohol ; the 

 boiling alcoholic solution solidifies on cooling into a pearly crystal- 

 line mass. Larger and transparent crystals may be obtained from 

 dilute solutions, but in no case were their forms sufficiently perfect 

 for determination. The simplest expression arrived at in analysing 

 the bromide is the formula 



C 6 H 7 NBr* ; 



but the mode of formation of the new compound unmistakeably shows 

 that this expression must be doubled, and that the composition and 

 weight of its molecule is represented by the formula 

 C 12 H 14 N 2 Br 2 . 



Pyridine, then, imitates triethylamine and triethylphosphine in 

 their deportment with dibromide of ethylene, the new bromide being 

 * H = l ; = 16; C = 12, &c. 



