HISTORY OF PETROLEUM OR ROCK OIL. 329 



of the oxydation of naphtlia or petroleum by a process similar to that 

 by which resins are derived from vegetable hydrocarbons. These 

 formulas must be taken as representing not the true equivalents, but 

 only the proportions of the elements in the bodies in question, which 

 are in most cases mixtures of various substances. This is especially 

 true of naphtha, which may be taken as the representative of pure 

 unoxydized petroleum, and which is separated b}' distillation into oils 

 of very different boiling points. The late analyses by Uelsmann of 

 the rectified rock oil from Sehnde near Hanover, gave the formula 

 C18H205 and according to De la Rue and Miiller, the greater part of 

 the Rangoon petroleum consists of hydrocarbons in which the number 

 of equivalents of hydrogen is a little greater than the carbon; one 

 gave C2 6H2 8* Associated with these are, however, portions of bodies 

 containing a less proportion of hj^drogen, so that we may conceive 

 the mean composition of petroleum to be represented, as in the pre- 

 ceding table, by equal equivalents of hydrogen and carbon; many 

 forms of solid bitumen also, as ozokerite and hatchetine, have the 

 same general composition. 



By referring to what has been said above it will be seen that the 

 final result of the third process of decomposition of woody fibre, in 

 which the air being excluded, the oxygen is shared between the car- 

 bon and hydrogen, w^ould be CaoHg. A similar result would be ob- 

 tained with the simultaneous evolution of marsh gas, if we suppose 

 6 CO2 + 8 HO -\- 3 CH2 to be removed from an equivalent of woody 

 fibre, leaving CjsHe = CaoHg = C24H9.5, which approaches the 

 composition of most bituminous coals and of idrialine. A further 

 elimination of marsh gas would leave a residue of pure carbon, and 

 thus, as Bischof has suggested, vegetable matters may be converted 

 into anthracite without the intervention of a high temperature. 



The elimination of the w^hole of the oxygen in the form of carbonic 

 acid would leave a compound with a large excess of hydrogen, of 

 which it would be necessary to remove a portion in the form of water 

 or marsh gas in order to reduce the residue to the composition of pe- 

 troleum. We know of no combination of carbon and hydrogen in 

 which the number of atoms of hydrogen surpasses by more than two 

 those of hydrogen, the general formula being C„H^+2? «o that oils 

 like C18H20 and C26H28 contain nearly the maximum quantity of 

 hydrogen, and a body like C14H20J w'hose formation we have sup- 

 posed above, could not exist, but must break up into marsh gas and 

 some less hydrogenous oil like petroleum. 



We do not know the precise conditions which in certain strata favor 

 the production of petroleum rather than of lignite or coal, but in the 

 fermentation of sugar, to which we may compare the transformations 

 of woody fibre, we find that under different conditions it may yield 

 either alcohol and carbonic acid, or butyric and carbonic acids with 

 hydrogen, and even in certain modified fermentations the acetic, 

 lactic, and propionic acids, and the higher alcohols, like C10H12O2. 

 These analogies furnish suggestions which may lead to a satisfactory 

 explanation of the peculiar transformation by which, in certain sedi- 

 mentary strata, organic matters have been converted into bitumen. 



