undoubtedly prepared to perform in the water the same function as the coal plants performed in the atmosphere. As the result of terrestrial vegetation has been first woody tissue, and then, by its decomposition, coal; so the result of marine vegetation has been first cellular tissue filled with a kind of liquid carbon; and, as the carbon is unalterable, the decomposition of the plant has left it free as fluid bitumen or petroleum. The geographical distribution of petroleum and that of the remains of marine algæ present the same remarkable coincidence. At Oil Creek, Slippery Rock Creek, in the Chemung of Virginia, Ohio, Kentucky, everywhere indeed where oil has been seen, either in cavities or saturating the rocks, and where the strata are open to view, a remarkable amount of fucoidal remains has been seen. This cannot be a mere casual coincidence."

The author appends to this paper the following note: "Professor Liebig, to whom I wrote a résumé of my opinion on this subject with the request that he would point out to me the result of chemical analyses of marine plants, if there were any either in support or discredit of my idea, kindly answered that there were unhappily no analyses of species of fucus or other hydrophytes which could be used as affording a support to my views, but that my arguments, based on exact researches, were so conclusive that, for himself at least, they had removed any doubts of the truth of the theory."

1 Lesquereaux, Transactions American Philosophical Society, vol. xiii. 1869, pp. 313-328.

The theory of the origin of petroleum held by Prof. J. S. Newberry is briefly as follows: It is well known that in the growth of plants, the mysterious principle called life produces the dissociation of the elements composing carbonic acid and water breaking the strongest bonds of inorganic chemistry. Under this influence, structures of hundreds of feet in height, and many tons in weight, are piled up in antagonism to the force of gravitation and the affinities of inorganic chemistry. When the life spark leaves this structure, and its creative and conservative power is no longer exerted, the mass stands as an unstable compound, and the oxygen which has been divorced from its carbon by the intrusive life force now hastens to reclaim its own. This reunion may take place slowly and quietly, and is then named "decay," but under favoring circumstances, with heat and fury, which is called combustion. The result in each case is the same; the organic tissue is oxidized; the affinities of inorganic chemistry reassert themselves; the stable compounds carbonic acid and water are formed and pass away; hydrocarbons are evolved and oxidized, and, in place of the great mass of organic tissue, a handful of ashes is left, which represents the mineral matter, woven by life into its ephemeral fabric. This process of the decomposition of organic matter may be hastened or retarded, but it can hardly be permanently arrested. By excluding oxygen and applying heat, the constituents of the mass react upon themselves, forming new compounds, solids, liquids, and gases, several of which possess properties which make them useful to man during

their existence, or in the development of usable force in the act of passing to their inevitable destiny, oxidation.

The chemical composition of wood tissue varies somewhat in different kinds of wood, but a typical example chosen by Bischof, gave :—

When this is placed in a retort and subjected to destructive distillation, there are evolved from it watery vapor, acetic acid, condensable vapors of naphtha, and, as the heat is increased, uncondensable gases, such as carburetted hydrogen, water from the combination of hydrogen and oxygen, and carbonic acid-the latter from a combination of the carbon and oxygen. The ultimate residual is charcoal (consisting of carbon) and the ash of the plant, in all perhaps one-quarter of the original mass. A similar round of changes may take place spontaneously, and at a low temperature. When buried under water or under wet earth, vegetable tissue is still slowly oxidized, since water absorbs some air; but apart from this, the original tissue is greatly modified by the reaction of its constituents upon themselves. The carbon, hydrogen, and oxygen combine in part to form carbonic acid gas, water, carbu retted hydrogen, naphtha (petroleum), which escape in part, remaining temporarily as a solid residuum, which becomes at first brown, and ultimately black from its free carbon, and is known first as lignite, and subsequently, as

it progressively changes, as coal, anthracite, etc. The escape of gases from vegetable matter decaying in shallow water has been seen by almost every one. The solution of liquid hydrocarbons has also been observed, and would be more frequently noticed if carefully looked for. The process of subterranean or subaqueous distillation of vegetable tissue is called bituminization, because one of its temporary products is bitumen, which saturates or invests the residual carbon, giving it a pitchy appearance. This process goes on as long as there is any organic compound left. in the mass; the final residuum is graphite, the intermediate stages being represented by peat, lignite, bituminous coal, anthracite, etc. Some of its phenomena may be observed in the evolution of carburetted hydrogen, and carbonic acid (under the names of "fire-damp" and "chokedamp"), from beds of lignite and coal, and by a constant flow of inflammable gas and petroleum from strata of bituminous shale. The spontaneous distillation and oxida tion of the organic constituents of beds of lignite, coal, and carbonaceous shale may be seen along their lines of outcrop, even when the carbon of the most exposed portions is altogether burnt off, leaving an ash or clay behind. As the strata are penetrated, the percentage of carbon and hydrogen constantly increases, until, having passed beyond the seat of atmospheric influences, the mass is found presenting its natural physical and chemical characters.

It would not be proper to take leave of this branch of the subject without bringing to the notice of our readers the only remaining theory regarding the origin of petro

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leum, which is deserving of attention at our hands. We do this in justice to the distinguished chemist, whose views on all questions relating to his profession are entitled. to eminent respect and careful consideration. We have discussed as briefly as its importance would permit, the vegetable and animal origin of petroleum, and will here call attention to

Berthelot's Theory of its Mineral Origin.

6

This is best stated in Mr. Berthelot's own words as set forth in a paper published in the Ann. de Chim. et de Phys.,' vol. ix. page 482, 1866.

"The hypothesis recently put forth by M. Daubrée, that the terrestrial mass contains free alkali metals in its interior, joined to the experiments which I have lately made, leads almost necessarily to a mode of explaining the formation of hydrocarbons. In fact, according to my experiments, the carbonic acid everywhere infiltrated into the crust of the earth coming in contact with alkali metals forms acetylides. These same acetylides would result also from the contact of earthy carbonates with alkali metals even below a dull-red heat. Now these alkaline acetylides once formed may be subjected to the action of steam, and free acetylene would be the result, if the product were immediately withdrawn from the influence of heat, hydrogen, and other matters present. But on account of the conditions being different, the acetylene would not exist, as my recent experiments prove. In its place we obtain either products of condensation, which approach the