closed tubes, the result, by determining the loss being 8.9 per cent. gases. After washing with water and purifying with acid to remove the non-saturated and aromatic hydrocarbons and other admixtures, the distillate obtained from the menhaden oil was subjected to several distillations and in the separate fractions pentane, hexane, normal and secondary heptane, normal octane and normal nonane were established according to their characteristic properties.

The loss in distillate by treatment with ordinary and fuming sulphuric acid amounted to about 37 per cent., and from this it could be inferred that it contained olefines and aromatic hydrocarbons.

If from a mixture containing paraffin hydrocarbons, olefines and naphthenes the olefines are removed by ordinary sulphuric acid, the specific gravity, refractive power and refractive exponent of the remaining oil will decrease; but if the naphthenes present are then taken out with fuming sulphuric acid, the first two quantities decrease, but the specific refractive power increases. In the absence of naphthalene the latter remains unchanged or decreases. This being presupposed, Engler and Seidner obtained results from which the presence of naphthenes, thoughonly in small quantities, in the distillate of menhaden oil appeared probable.

To prepare an illuminating oil from the distillate, the latter was first subjected to distillation, and the fractions between 284° and 572° F. caught. After refining this fraction in the ordinary manner a product was obtained which could not be distinguished from ordinary commercial petroleum, and possessed all the properties of a good illuminating oil. Its specific gravity was 0.8025, its flashing point 80° F., and its medium intensity of light 13.2.

Since it is known that fish oil consists chiefly of triolein, the latter, for controlling purposes, was synthetically prepared and subjected to a similar distillation, the results obtained corresponding with those of menhaden oil.

To obtain an idea of the behavior of not only the fat, but of

the entire animal substance, when distilled under super-pressure, Engler had formerly subjected in Oehlrich's refinery marine animals, dried fishes and mollusks to distillation at a pressure of 16 atmospheres.

The distillates obtained, however, differ in their entire composition so much from petroleum that there can be no doubt that petroleum could be formed only by accumulated masses of animal bodies having passed first through a process of putrefaction, whereby the nitrogenous substances were destroyed and removed, the fat alone remaining behind, which was in later epochs converted into petroleum by pressure and heat, and perhaps by the first alone. That petroleum is not of vegetable origin is proved by the absence of carbonaceous residue in the localities where petroleum occurs, which would absolutely be the case if its origin were due to vegetable remains. Because if we take cellulose (CHO) as the representative of the crude materials of petroleum, then with its composition of 44.4 per cent. carbon, 6.2 per cent. hydrogen, and 49.4 per cent. oxygen, a residue would remain after parting only with a small portion of the elementary substances under the formation of water, which would be so poor in hydrogen and so rich in carbon that without a separation of carbon a formation of saturated hydrocarbons, or even of hydrocarbons of the series CH could no longer be considered possible. It is, however, entirely different with animal fats or fatty acids formed by the splitting off of glycerin. By eliminating from the latter the total oxygen with the hydrogen belonging to it as water, carbon and hydrogen still remain behind in a proportion (87 per cent. carbon and 13 per cent. hydrogen), which comes remarkably close to the total composition of our crude petroleum.

Proceeding from his classical experiments, Engler shows that the formation of petroleum may be due to the fact that after the putrefaction of the bodies of marine animals all the nitrogenous organic substances, etc., were destroyed, whereby the nitrogen was carried away as ammonia or ammoniacal salts, and the fatty substances consisting chiefly of trioleate, tristearate,

and tripalmitate of glycerin remained behind. By the pressure of deposits of sedimentary strata and perhaps also by the gases formed during putrefaction and by heat, this fat suffered an initial splitting into the acids (oleic, stearic and palmitic acids), and into glycerin, the latter being washed away as such or converted into acreolin. The fatty acids, under the same pressure and heat, were finally decomposed, hydrocarbons and water being formed. The appearance of carbonic acid and carbonic oxide in his experiments, Engler considers only an incidental phenomenon (because only slight traces of these gases occur in petroleum and the gases accompanying it), but the appearance of water as the principal phenomenon. The less carbonic acid and carbonic oxide are formed, the more regularly, according to Engler, the process of the conversion of fatty acids into petroleum progresses.

Based upon the results of Engler's experiments, the hydrocarburetting process from the fatty acids may also be explained in a different form. The transformation of the glycerides of the fatty acids into the hydrocarbons of petroleum might also have taken place by the fats suffering decomposition under pressure into glycerin and fatty acids. The glycerin was next decomposed into acreolin and water. The acreolin condensed to benzol, water being simultaneously split off, a reaction characteristic of the aldehydes and ketones. The fatty acids, on the other hand, underwent far-reaching splitting into hydrocarbons and carbonic acid, the former being dissociated under the prevailing pressure and heat, whereby the hydrocarbons characteristic of petroleum were formed. The second product of the splitting of the fatty acids-the carbonic acid-was reduced by the hydrogen molecules, which were in a nascent state during the dissociation of the hydrocarbons, and by the most volatile hydrocarbons, carbonic oxide being formed, so that the appearance of carbonic acid and of carbonic oxide in nature, as well as in Engler's experiments, may be considered an absolute factor in the formation of petroleum from fats. The partial or entire absence of these gases in natural gas may be due to their absorb

tion and convertion into carbonates by masses of earths, earthy alkalies, etc., surrounding the petroleum.

c. From plants and animals.

Several geologists and chemists consider petroleum of both animal and vegetable origin. A few of them may here be mentioned. Prof. Lesley connects the formation of Pennsylvania petroleum with the "vastly abundant accumulations of Paleozoic sea weeds, the marks of which are so infinitely numerous in the rocks, and with the infinitude of coralloid sea animals, the skeletons of which make up a large part of the limestone formations which lie several thousand feet beneath the Venango oil-sand group." Ashburner also ascribes a vegetable and animal origin to petroleum. Newberry (1859) asserts that the oil has been separated from vegetable and animal remains at the transitory stage of the organisms which is called bitumization. Prof. E. B. Andrews, however, calls attention to the fact "that if the oil were formed with the bitumen of the coal, we should expect that wherever there is bituminous coal there would be corresponding quantities of oil, which is not the case."

N. S. Shaler' supposes animal as well as vegetable origin, and regarding the first refers to certain Devonian limestones, and the latter to the Devonian black shale of Eastern America.

E. Orton is also of the opinion that petroleum occurring in shale and sandstone is of vegetable origin and that occurring in limestone of animal origin.

Peckham endeavors to prove that the quality of petroleum varies according to its origin; thus bitumen which forms asphalt but contains no paraffin is of animal origin, while that which does not form asphalt, but contains paraffin, is of vegetable origin.

Harper ascribes the formation of the Hanover petroleum to the decomposition of large masses of organic bodies of the animal and vegetable kingdoms, especially to those of the Devonian and carboniferous formations. Strippelmann holds a

1Stowell. Petr. Rep., 1877. No. 7, p. 6.

similiar opinion. He considers "that the formation of petroJeum is without doubt connected with the Surian, Devonian and carboniferous formations and the decomposition of masses of vegetable and animal substances accumulated in unknown depths is still in progress under the cooperation of greater heat. From this seat of production and its collecting spaces, the latter of which belong chiefly to the more recent formations, the productive oil regions have been filled and are still filled partially by condensations of gas and partially by capillary attraction.”

According to Dr. Kraemer petroleum is the product of dry distillation of organisms of pre-carboniferous epochs. The process of transformation has taken place (and perhaps takes place to day), where folds and piling up of the earth's crust gave rise to mountains,

2. Process of Formation.

As will be seen from the explanation given in the preceding sections, there can be no doubt of the organic origin of petroleum. It has been frequently suggested that the process of transformation has been effected by distillation, but in this respect also, opinions are diametrically opposed to one another. Some suppose for this distillation temperatures similar to those employed in the destructive distillation of coal; others consider the presupposition of a high temperature either unnecessary or as being in conflict with the chemical composition; while others again combine high and lower degrees of heat.

Daubree's experiments with fragments of wood exposed to the action of superheated steam showed the possibility of the formation of volatile and liquid products resembling natural bitumen at a relatively low temperature, though above 202° F.

Those who presuppose a high temperature for the formation of petroleum, refer either to the neighborhood of volcances, which, however, can be but very seldom established, or to the terrestrial heat at great depth. In e'ther case it becomes DECcessay to si ppose, besides the scat of formation exposed to a high temperature, a considerably cooler condensing scheme