136 PROCEEDINGS OP THE AMERICAN ACADEMY. 



attention to be diverted from the maiu object iu view. It should not be 

 understood that the diminution in weight mentioned above on treating 

 with acids was due entirely to the removal of aromatic hydrocarbons. 

 In all the petroleum hydrocarbons we have separated, on treating with 

 nitric and sulphuric acids, a large proportion of the products has remained 

 in solution, and it has been possible to reduce them only very slowly 

 by heating with sodium. From the distillates above 150°, heavy dark 

 brown precipitates have been formed at first, followed by light flocculent 

 deposits resembling aluminic hydrate. On distilling after treating with 

 sodium, usually a considerable residue is left. If heating with sodium be 

 continued until there is no further action, the metal will remain bright in 

 the oil, and we have looked on this as an indication of purity. 



The oil separated from the acid mixture was boiled with sodium until 

 it produced no further decomposition, shaken with sulphuric acid, and 

 allowed to stand a long time in contact with sodium. Since the metal 

 remained unaffected, the oil was assumed to be completely purified ; 

 nevertheless, analysis showed still remaining a trace of the less hydro- 

 genized body : — 



0.1547 gram of the oil gave 0.4816 gram COo, and 0.2104 gram HoO. 



A determination of the specific gravity of the purified oil gave 0.7585. 



To prove with greater certainty the composition of this hydrocarbon, 

 the crude distillate obtained as described above was heated on the steam 

 bath with fuming sulphuric acid, which gave some decomposition, and the 

 oil remaining washed thoroughly with caustic soda and water. 20 grams 

 of the crude distillate gave 16.5 grams of the purified oil, with a loss of 

 17.5 per cent, which is probably an approximate measure of the propor- 

 tion of aromatic hydrocarbons in this distillate. It is probable that the 

 loss in weight with the mixture of nitric and sulphuric acids included 

 some decomposition of the principal hydrocarbon. The oil treated with 

 fuming sulphuric acid was carried through ten distillations, after which it 

 collected for the most part within one degree, and 100 grams distilled 

 at 196°-] 97°, under 760 mm., and with the mercury column all in the 

 vapor. This product was again warmed with fuming sulphuric acid, 

 washed, and dried over sodium. 



In the latter ex23eriment the acid was only slightly discolored. The 



