Page:Popular Science Monthly Volume 9.djvu/163

Rh Cahours, and Schorlemmer. The first and second were found by Fouqué in gaseous exhalations from petroleum-wells at Petrolia (and Fredonia, New York); the third in similar exhalations from wells at Pioneer Run.

Pelouze and Cahours carry the marsh-gas series to C16H32, but Warren concluded that it terminates with C9H20, and that the oils of higher density and atomic numbers belong to the ethylene series.

On inspecting the above table it will be seen that numbers 4, 7, 9, 11, 13, and 14, have a common difference of about 30° C. between each in succession, in regard to their boiling-points; and that numbers 6, 8, 10, and 12, have a similar common difference, and are each about 8° higher in their boiling-points than the ones next below them. On this account, Warren divided them into two groups; but he included here another C4H10, with a boiling-point of 8 to 9°, which is, according to Sadtler, a mixture of the two given in the table.

Besides the members of the marsh-gas series given above, American petroleum yields liquids boiling above 300° C., which on cooling yield a solid mass called paraffine, white and transparent when pure. It probably is a mixture of the higher members of the series CnH2n+2, and on heating in a sealed tube is converted into a mixture of several paraffines and olefines of lower molecular weight, liquid at ordinary temperatures (Fownes).

Of the ethylene series, Warren has found in Pennsylvania petroleum, decylene, C10H20, boiling-point 174.9°; undecylene, C11H11, boiling-point 195.8°; and bidecylene, C12H24, boiling-point 216.2°; these have a difference of about 20° C. in their successive boiling-points.

No higher series of hydrocarbons is yet known from Pennsylvania petroleum, but members of the benzol series, CnH2n—6, have been found in other petroleums. Thus De la Rue and Müller, in 1850, found benzol, toluol, and xylol, in Rangoon tar; Bussenius and Eisenstuck discovered xylol in petroleum from Sehnde, Hanover; Pebal and Freund detected benzol, C6H6, toluol, C7H8, xylol, C8H10, cumol, C9H1, and cymol, C10H14, in naphtha from Boroslaw, Galicia; De la