MABERY AND HUDSON. — AMERICAN PETROLEUM. 107 



The quantity of this product was insufficient for a determination 

 of its specific gravity. The following value was obtained as its vapor 

 density : — 



0.1 Goo gram of the oil gave 87.2 c.c. of vapor at 182°, under a tension 

 of 4-47 mm. 



Calculated for C^IIsCIj. Found. 



4.39 4.16 



Our first attempts towards separating the butanes were made before 

 the necessity of long continued diatillution was fully appreciated. Not 

 until after several trials was it observed to what an extent a small pro- 

 portion of isobutaue depressed the boiling point of pentane. In the 

 earlier work, after six or eight distillations the product was assumed to 

 he sufficiently pure for chlorination. A study of the chlorine deriva- 

 tives show^ed beyond question that the hydrocarbon was pentane. We 

 were still further misled by the boiling point of the pentyl chloride, 96°, 

 which did not correspond to that of any hitherto published. Referring 

 to our former notes on the vapor density of the distillate 8°-9°, we found 

 the following determinations : — 



I, 0.0717 gram of the oil gave 45.5 c.c. of vapor at 16°, under a ten- 

 sion of 48.1 cm. of mercury. 

 II. 0.0849 gram of the oil gave 46.8 c.c. of vapor at 18°.5, under 

 a tension of 47.75 cm. of mercury. 



III. 0.0999 gram of the oil gave 51.5 c.c. of vapor at 18°. 5, under a 



tension of 51.75 cm. of mercury. 



IV. 0.0751 gram of the oil gave 43.5 c.c. of vapor at 18°. 5, under a 



tension of 45.76 cm. of mercury. 



It will be seen that determination I. corresponds closely to the compo- 

 sition of butane, and determinations 11., III., and IV. to that of pentane. 

 When these determinations were made, we expected results that would 

 substantiate what had previously been done on the butanes, and there- 

 fore accepted only the first result, which was the last one obtained, as 

 supporting this view. But in the light of further knowledge of these 

 bodies, the determinations thousht to be erroneous correspond more 

 nearly to pentane, although showing the influence of the small quantity 

 of isobutane. The first result was published in a former paper,* when 



* These Proceedings, XXXI. 24. 



