260 



Dibromide of Tribrominated Ethylene. 



To obtain this compound, tribrominated ethylene was introduced 

 into a retort, and cautiously distilled into a receiver containing bro- 

 mine. Combination took place with considerable evolution of heat. 

 The orange-red liquid thus produced was washed with weak potash, 

 and ultimately with water. Thus purified, this bromine-compound is 

 a yellowish red oil, soluble in alcohol and in ether, and solidifying 

 when exposed to a frigorific mixture. I have not succeeded in 

 preparing this substance in a state of sufficient purity for analysis. 

 But the nature of this body is clearly established by the facility with 

 which it is transformed into 



Tetrabrominated Ethylene or Bromide of Carbon, 

 by the action of an alcoholic solution of potash. 



Addition of water to the alcoholic solution precipitates this 

 compound as an oily liquid, which, when slowly deposited by 

 spontaneous evaporation from its solution in alcohol or ether, separates 

 in beautiful crystalline plates of an agreeable aromatic odour and 

 burning taste. One or two recrystallizations render this substance 

 perfectly pure. It is heavier than water, fuses at 50 C., sublimes at a 

 higher temperature, and is not attacked by the mineral acids. 



These properties identify this compound with the bromide of 

 carbon obtained by Lowig in the action of bromine upon alcohol and 

 upon ether. 



For analysis, the substance was dried over sulphuric acid in vacuo ; 

 the formula 



C 2 Br 4 



was established by the determination both of carbon and of bromine. 

 The tetrabrominated ethylene is generated by the action of an 

 alcoholic solution of potash upon the dibromide of tribrominated 

 ethylene, according to the following equation : 



C 2 HBr 5 + KHO = C 2 Br 4 +KBr+H 2 O. 



The experiments which form the subject of this note were per- 

 formed in the laboratory of Dr. Hofmann. 



