CONSTITUENTS OP PLANTS, ETC. 



325 



on page 324 gives the names, formulae, and boiling points of 

 the chief hydrocarbons occurring in American petroleum. 



444. Refining Petroleum. Petroleum as it issues from the 

 earth is dark colored and ill-smelling ; some of its constitu- 

 ent hydrocarbons are too volatile for burning in lamps, 

 others are too heavy, consequently the petroleum is sub- 

 jected to a process of refining. The chief point in the re- 

 fining process is called fractional distillation, whereby the 

 bodies having different boiling points are separated; the 

 lighter portions boiling the lowest distill over first, and the 

 successive portions are denser and less volatile. This proc- 

 ess furnishes various products, which are still mixtures of 

 hydrocarbons, and which have no definite composition, but 

 they have received names for commercial uses ; the follow- 

 ing table shows these bodies and their uses : 



PRODUCTS OF THE DISTILLATION OF CRUDE PETROLEUM.* 



Rearranged from Dr. C. F. Chandler's Report on Petroleum, presented to the 

 Board of Health of the City of New York, 18TO. 



