190 Messrs. Thorpe and Young* on the Combined Action 



The following are the data obtained in the determination of its 

 specific gravity : — , 



from which 1*5967 is obtained as the specific gravity of hexylene dibro- 

 mide at 20° compared with water at the same temperature. 



A second determination with a smaller quantity gave 1*5975 at 18°. 

 Pelouze and Cahours found the boiling-point of this body to be 192-198°, 

 and its specific gravity 1*582 at 19°. These numbers are certainly too 

 low ; the bromide had probably been slightly decomposed by distillation. 



"We have attempted to determine the relative amounts of hydride and 

 olefine in the fraction boiling at 65-68° by means of the reaction with 

 bromine. 



The hydrocarbon was weighed out in a small distillation-flask, and 

 well cooled by a mixture of ice and salt ; bromine was then slowly added, 

 and in minute drops, by means of the little apparatus seen in the figure 

 — a small caoutchouc ball about 5 cub. centims. in diameter, which can be 

 compressed by the plate movable along the rods by means of the 

 milled head-screw. The mode of working the instrument is obvious ; by 

 means of it the bromine can be easily transferred from the bottle in 

 which it is preserved to the hydrocarbon, and the amount added can be 

 regulated with great nicety. The bromine was added until the liquid 

 was permanently reddened, when the flask was again weighed to deter- 

 mine the amount of bromine employed. 13*30 grms. of the mixed hydro- 

 carbons boiling at 65-70° required 13*16 grms. bromine before the red 

 colour was persistent. This amount of bromine is equivalent to 6*9 grms. 

 of hexylene, and 13*3—6*9=6*4 as the amount of hexane present. The 

 mixture was now distilled, and all passing over below 110° (at which 

 point the liquid in the flask commenced to blacken) collected in a weighed 

 test-tube. The weight of the distillate was 6*18 grms. Prom these 

 numbers it would appear that the product boiling at 65-68° is a mixture 

 of hexane and hexylene in about equal proportions. 



6. The fraction boiling at 94-97° was next treated with bromine in 

 the cold until the liquid was reddened. The termination of the reaction 

 was not so easily seen in this case ; the mixture blackened slightly, and 

 more hydrobromic acid was evolved, although the hydrocarbon was care- 

 fully cooled by ice and salt. The brominated mixture on distillation 

 commenced to boil about 95°, and it was heated to 130°, when the liquid 

 in the flask commenced to decompose ; at this point, therefore, the distil- 

 lation was interrupted. The following are the details of a quantitative 

 determination :— - 



"Weight of bottle 



Bottle + water at 20° . 

 Bottle + bromide at 20° 



1*6807 grm. 

 7*2942 grms. 

 10*6440 „ 



