been deposited, perhaps upon some ocean beach in the ages long rolled past, a vast amount of organic remains either vegetable or animal. If these had remained uncovered or unprotected, a slow disappearance of their or ganic constituents would have occurred, in which case there could not possibly have been any oil formed. Thus it became necessary to cover these remains with deposits of sand. Now in order to subject them to the necessary heat for destructive distillation, it supposes this stratum should be deeply covered with successive depositions, by which covering the internal heat of the earth is prevented from being dissipated in its revolutions through space. Having thus our materials gathered for the process, and having placed our rocky retort in position, Nature liberally, yet in her own time (for her working days are centuries), supplies the heat necessary. But if there is to be a product of this distillation, there must be provided a receiver commensurate in size into which it may be stored. We have this already formed in the overlying porous sandstones, which are so many immense reservoirs covering hundreds of square miles of territory. These formations must in turn be protected by a rocky impervious covering to prevent the escape of the oil in an upward direction and to complete these grand subterranean "oil works," and to prevent the escape of the product in a lateral direction, and its wasteful dissemination generally. This impervious covering should so conform to the adjacent strata, that the oil formed and stored in the sand should be effectually sealed up.. From a number of observations made in the drilling of wells in

the oil regions, it appears that the absence of either of the above-mentioned conditions renders what appears to be the most" satisfactory showing" illusory and disappointing.

The oil thus stored in the "sand formation may be equally disseminated through its porous structure, or it may find a lodgement in a fissure or cavity of enormous dimensions. The fact has been frequently noticed that upon reaching the oil sand, the tools have suddenly dropped, and volumes of oil have been immediately thrown out of the well.

"The escape of the oil at the surface of a well is caused sometimes by mere hydrostatic pressure as water rises in common artesian wells. More frequently perhaps the oil is forced up by the elastic reaction of confined gases. An open cavity or a porous portion of rock bounded on all sides by impervious walls which constitutes a virtual cavity may be partly filled with oil, while gases occupy the higher portions of the cavity. Such a cavity whether actual or virtual may possess any form or extent, or may consist of a number of cavities connected by narrow passages or mere fissures. In nearly all cases more or less gas accompanies the oil and subsists under a very high degree of pressure. The pressure in such cases is not the hydrostatic pressure of water, but a consequence of the continued generation of gas and oil, long after the cavity has been filled. If a boring happens to penetrate the higher portion of such a cavity the gas at once rushes forth with greater or less violence and persistence. As soon, however, as the tension is relieved the

escape ceases. No oil will be obtained without applying suction, since there is no hydrostatic pressure exerted from behind, and the secretion of the gas tends rather to confine the oil in the lowest ramifications of the cavity.

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Suppose, however, on boring a hole for oil we happen to penetrate some of the lower portions of the cavity occupied by the oil. The elastic pressure of the confined gas will at once force the oil up and produce a spouting or blowing well. The flow must necessarily subside by degrees as the confined gas, by the escape of the oil, acquires more space for its accommodation. It may continue, however, until the cavity is exhausted of its oil, after which pumping will be of no avail. If the confined gas attains its equilibrium before the oil has been completely forced from the cavity, it is evident that the remainder must be obtained by pumping. There is no cavity so large, however, as not to be destined to ultimate exhaustion. Every oil-well of whatever class is destined to abandonment. It is true that nature is constantly at work replenishing the exhausted reservoirs, but her accumulations are slow.

“Intermittent wells appear to act in some cases precisely after the manner of intermittent springs. More frequently, however, it is manifest that the combined action of gas and oil produces the phenomenon. In boring a well suppose a stream of gas is struck one hundred feet from the surface of the rock and a small stream of oil twenty feet below the gas, the entrance of oil fills twenty feet of the hole and begins to submerge the fissure at which

the gas is escaping; the gas forces its way through the oil with a sputtering sound, bubble after bubble rising to the surface. As the oil ascends the gas makes louder and louder complaints till finally summoning all its accumulated energies it hoists the superincumbent column of oil to the surface and pours it out in a stream of a few seconds' duration. The flow then ceases and the same operation begins to be repeated. After a minute or more of renewed grumbling and sputtering the pent-up gas again relieves itself, and thus the work continues. The same results would ensue if oil and gas found entrance at the same fissure, or even if the gas were admitted at any distance beneath the entrance of a small supply of oil."

The pressure exerted either upon bodies of oil or water by the expansive force of gas thus confined is enormous; when we add to this the additional pressure of a column of water of a thousand or more feet in height, we may form a very slight, but a wholly inadequate idea of the force with which a stream of gas is thrown from an opening into such a cavity. In many instances the roaring as of a tornado may be heard for many miles. We shall have occasion elsewhere to speak of some of the phenomena associated with wells of this character.

1 Winchell. 'Sketches of Creation,' p. 284.

CHAPTER III.

GEOGRAPHICAL DISTRIBUTION OF PETROLEUM.

PETROLEUM, under the various synonyms of rock-oil, mineral oil, naphtha, bitumen, pitch, asphaltum, mineral wax, has been known and employed for thousands of years. The earliest mention we have of it, is the Biblical record of its use by the patriarch Noah, who rendered the Ark impervious to the "floods of waters" by giving his vessel two coats of "pitch," "within and without." Combining, as we shall discover further on, with its water-proof qualities, the property of preserving timber from decay to a remarkable degree, it may be safely said that no better substitute for similar purposes has yet been discovered. That it was in general use, and for a variety of purposes, very early in the history of man, there can be little doubt. We learn a little further on in the sacred volume, that the generation immediately following commenced on the plains of Shinar "to build a tower whose top may reach unto heaven." In the construction of this edifice they "used brick for stone and slime had they for mortar." The mortar employed in this building was one of the many forms of this bituminous substance, which, on account of its peculiar viscid, adhesive, and indestructible qualities, was admirably adapted for a building of such