186 S. D. Hayes on the Distillation of Petroleum Naphthas. 
heavy oil had accumulated it was drawn off at the bottom, the 
largest quantity being found in the first cylinder. It was 
found that the longer the vapors were held together in the 
apparatus, heated and under pressure, the more perfect were 
compositions; and Mr. Willard obtained at different 
times from two to ten per cent. of the naphtha as heavy oil. 
The heavy hydrocarbon oil obtained in this way has a dark 
yellowish-brown color, and smells of the adhering naphtha when 
fresh ; but after standing exposed to the air for a few days, it 
loses this odor and becomes nearly neutral, or comparatively 
free from offensive odor. Its specific gravity varies from 0850 
to 0°860, and its boiling point, after it is freed from the adher- 
ing naphtha, is above 400° F. 
It does not evaporate at common temperatures, leaves 4 
permanent greas i ood lubricator for 
» 
pears are decomposed or “cracked,” first into burning oil an¢ — 
eavy products, and ultimately into burning oil entirely. Bub — 
Mr. Willard’s 
sources, may “cracked” at a temperature below 300° B 
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It is a memoir that has never been published in any scientifi¢ : 
journal, containing the results of an extended investigation made 
troleum are not simply bodies previously existing in the pet” 
* Report on the Rock Oil or Petroleum from Venango county. Penneylvania ri 
_ With special reference to its use for illuminating and other purposes. By Prof. # 
_ Silliman, Jr. New Haven, 1855. 
- 
