of Heat and Pressure upon the Paraffins. 



191 



"Weight of mixed hydrocarbons 14-21 grms. 



"Weight of bromine added 12-9 „ 



Equivalent to heptylene 7*9 „ 



Equivalent to heptane 6*3 



Amount of heptane actually obtained . . 6-15 „ 



From this experiment it would appear that the amount of olefine is 

 slightly greater than that of the hydride in the fraction boiling at 94-97° ; 

 but, from the circumstances of the experiment, we have reason to believe 

 that the amount of heptylene thus indicated is slightly above the truth. 

 It was difficult to determine the final point of the reaction ; the hydride 

 was not altogether unacted on by the bromine, and small quantities of 

 hydrobromic acid were continuously disengaged during the process ; 

 these circumstances would tend to increase the weight of bromine used, 

 and consequently the apparent weight of the olefine present. In extend- 

 ing our research to the determination of the constitution of these hydro- 

 carbons, we have had occasion to repeat this experiment on a far larger 

 scale and under more favourable conditions. 



900 grms. of the mixed heptane and heptylene required 716 grms. of 

 bromine; this would be equivalent to 439 grms. of heptylene. 900 grms. 

 of a mixture of heptane and heptylene in equivalent proportions would 

 contain 444 grms. of heptylene. 



The heptylene bromide could not be redistilled under the ordinary 

 atmospheric pressure without decomposition ; it commenced to blacken at 

 about 150°, and dense fumes of hydrobromic acid were evolved. When 

 distilled in a current of steam, it was obtained nearly colourless. 



It cannot be preserved, however, without slight decomposition ; when 

 exposed to light, it slowly darkens in colour and evolves hydrobromic 

 acid gas. 



It was analyzed with the following results : — 



0-7470 grm. gave 1-0210 grm. AgBr and 0-035 grm. reduced silver. 



Calculated for -r, ■= 



C 7 H u Br 8 . FouncU 



Br 62-01 61-66 



The specific gravity of this compound was found to be 1*5146 at 18°*5, 

 water at the same temperature being taken as unity. 



The heptane, after washing with dilute potash solution, drying, and 

 rectification over sodium., boiled constantly at 97-99°. Its specific 

 gravity was found from two experiments to be (1) 0-6910 at 19°, and 

 (2) 0-6915 at 18°. "Warren and Storer found for the same hydrocarbon 

 from Menhadden oil the specific gravity of 0-6942 at 17°- 5. 



Burnt with copper oxide in a stream of oxygen, it yielded the following 

 numbers : — 



I. 0-1695 grm. hydride gave 0*5240 grm. carbon dioxide and 

 0*2460 grm. water. 



