MABERY AND HUDSON. — AMERICAN PETROLEUM. 115 



The monochloroctiine obtained by Pelouze and Cahours,* and by 

 Scliorlemmer,t from petroleum octane, boiling point 1G8°-172°, was evi- 

 dently a mixture of the two chloroctanes from the hydrocarbons 119°. 5 

 and 1*24°. It could not be otherwise, on account of the imperfect sepa- 

 ration of the hydrocarbons. In our experience, nothing less than thirty 

 distillations is sufficient for the separation of these bodies with any 

 degree of purity. 



In comparing the results in this paper with those of others, it should 

 be borne in mind that our products were separated from Trenton lime- 

 stone petroleum, which was unknown at the time of the earlier study of 

 Pennsylvania oil. But there can be little doubt that these portions of 

 Pennsylvania and Ohio oils are identical so far as the principal constitu- 

 ents are concerned. That this is true of constituents with boiling points 

 above 150^ will be shown in another paper. 



In many instances, even after the most careful purification, the specific 

 gravity of the petroleum hydrocarbons is somewhat higher than that of 

 the same hydrocarbons synthetically prepared. Schorlemmer | thought 

 this was due to fine differences of isomerism. But this was before the 

 discovery of uaphtenes in petroleum. It now seems very probable that 

 the higlier specific gravity is due to the difficulty in removing the last 

 trace of these bodies, especially since a small excess of carbon and a 

 slight deficiency in hydrogen for the formula C„H2„ + 2 accompanies the 

 higher specific gravity. A notable quality of the naphtenes is their 

 inertness toward reagents, which is doubtless greatly increased by large 

 dilution in the principal petroleum hydrocarbons. 



In Russian petroleum, Markownikoif and Putochin § discovered isocto- 

 naphtene, boiling point 122°. 5. In looking for this hydrocarbon in Ohio 

 petroleum the fractions 120°-124° were carefully distilled many times, 

 until so little remained within these limits no individual constituent 

 could be present in any appreciable quantity, or in such quantity that it 

 could be collected by fractional distillation and identified. The octane 

 found by Lemoine at 121° is, therefore, also excluded. 



The octane, boiling point 125°. 46, separated by Schorlemmer, was 

 assumed to be identical with normal octane formed from normal butyl 

 iodide by the action of sodium. "Warren found a somewhat hisfher 

 boiling point in the octane from Pennsylvania petroleum. This body 



* Jahr. 1863, p. 528. 



t Ann. Chem. Pliarm., CXXV. 112. 



J Pliil. Trans., CLXXI. 451 (1880). 



§ Ber. der deutsch. chem. Gesellsch., 1885, p. 1860. 



