Popular Science Monthly/Volume 9/June 1876/Petroleum

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PETROLEUM.[1]
By Prof. H. B. CORNWALL.

ALTHOUGH it has only lately acquired its present important place among articles of commerce, this valuable product of Nature's laboratory has been known for ages, and was used for medicinal and illuminating purposes in ancient times. The petroleum-spring of Zante, one of the Ionian Islands, was mentioned by Herodotus more than 2,000 years ago; and Pliny says that the oil of a spring at Agrigentum, Sicily, was used in lamps. The city of Genoa was formerly lighted from the wells of Amiano, in Parma, Italy.

Prof. A. E. Foote (American Chemist, November, 1872) states that Peter Kalm, in his "Travels in North America," published in 1772, gives a map of the Pennsylvania oil-springs in 1771; but, according to H. E. Wrigley, the earliest mention of petroleum in that State occurred in the report of the commander of Fort Duquesne, 1750, when he witnessed the ceremonies of the Seneca Indians on Oil Creek. A prominent feature of the ceremonies was the burning of the oil as it oozed from the ground.

The oil-spring of Cuba, Alleghany County, New York, called the Seneca Oil-Spring, was described by Prof. Silliman, in 1833, as a dirty pool, about eighteen feet in diameter, covered with a film of oil, which was skimmed off from time to time for medicinal purposes. The so-called Seneca-oil was not from this spring, but from Oil Creek. Hildreth, in 1833, gave an account of the salt-wells of the Little Kanawha Valley, West Virginia, which he says yielded a little oil. In 1840 a well at Burkesville, Kentucky, was described as spouting oil at the estimated rate of seventy-five gallons a minute for a few days, but it then failed entirely (Dana, "Mineralogy," fifth edition, 1869). In 1844 Mr. Murray mentioned the petroleum of Enniskillen, Canada.

About twenty years ago the manufacture of oil from coal and bituminous shales, having been widely extended through the labors of Abraham Gesner and James Young, of Glasgow, began to excite interest in this country, and, according to S. D. Hayes, the first coal-oil offered for sale in this country was made by Philbrick & Atwood, in 1852, at the works of the United States Chemical Manufacturing Company, Waltham, Massachusetts. It was called coup-oil, after the recent coup d'état of Louis Napoleon, and was used as a lubricator.

In 1856 the first illuminating oil was made by Mr. Joshua Merrill, from Trinidad bitumen, according to the same authority. According to H. E. Wrigley, however, a refinery was started as early as 1850 by Mr. Samuel Kier, of Pittsburg, Pennsylvania, for the treatment of crude petroleum ("Report on Petroleum of Pennsylvania" for the "Second Geological Survey of Pennsylvania, 1874"). Success being limited only by the small amount available, search for the oil was naturally directed to Oil Creek, and in 1858 Messrs. J. G. Eveleth and George H. Bissell, of New York City, leased one hundred acres of land near Titusville, on the northern border of Venango County, Pennsylvania, and engaged Colonel E. L. Drake, of New Haven, Connecticut, to bore a well. On the 28th of August, 1859, he struck oil at a depth of seventy-one feet (according to some authorities sixty-nine and a half feet), and a pump was adjusted which produced twenty-five barrels a day.

In 1861 the first flowing well was struck by Mr. Funk, on the M'Elhenny Farm, Oil Creek, at a depth of 400 feet. Soon after two more wells were sunk (the Phillips and Empire), flowing 3,000 barrels each daily. Since 1858, in round numbers, 10,500 wells have been bored in Pennsylvania, and oil-wells also exist in West Virginia, Ohio, Kentucky, and elsewhere, with results that will be stated hereafter.

It would not be proper to leave the history of petroleum without mentioning Prof. B. Silliman's report on Pennsylvania petroleum to Messrs. Eveleth, Bissell & Reed, 1855.

He examined the rock-oil or petroleum of Venango County, and, long before the present processes of refining had been introduced, suggested several very important processes, which have been since followed in its treatment; such as distillation by steam, "cracking," or breaking up of the heavier oils into lighter compounds, its use for making gas, for illuminating purposes, for lubricating, etc.

Composition.—Petroleum is a mixture of several hydrocarbons, and contains also bituminous materials, sulphur, carbonaceous matter, sand, and clay. Its odor is generally offensive. The color and specific gravity vary greatly. The crude petroleum of Pennsylvania is generally dark-green with a brownish tinge by reflected light; the color of thin layers by transmitted light varies from dark-yellowish to reddish-brown. The oil of Enniskillen is blackish-brown; of Mecca, Ohio, yellow; in the neighborhood of Shamburg, Venango County, Pennsylvania, "black" and "green" oils occur side by side in the same districts; the lubricating oil of White Oak, West Virginia, is yellow; that from Amiano, Italy, is red to straw-color; at Baku the light oil is clear and faint yellow. Pennsylvania petroleum is somewhat thick, like thin sirup, but, although stiffened somewhat by cold, is always fluid. The oil of Pagan, Burmah, is very light, resembling naphtha, as is some of that from Baku.

The specific gravities of different petroleums are as follows: White Oak, West Virginia, 28° to 40° Baumé; Mecca, Ohio, 26° to 27°; Franklin, Pennsylvania, 30° to 32°; Cuba, New York, 32°; Tidioute, 43°; Pit-Hole, 51°; Pomeroy, Ohio, 51°; Russia, 28° to 40°. The heavy oils command, as a rule, a higher price. Although there is no certainty about their occurrence, the heavy oils have been frequently found at a higher level than the light oils in Pennsylvania, so that this was at one time supposed to be the rule.

The constituents of the mixture known as petroleum are separated from each other by fractional distillation; with care they can be isolated in quite a pure state, but in practice they undergo various decompositions, and are frequently to be regarded rather as products than as educts of the operations. Some are gaseous at ordinary temperatures, others are liquid, and others solid. They are divided into two classes: one having the formula CnH2n+2, and belonging to the marsh-gas. or paraffine series; the other, with the formula CnH2n, belonging to the ethylene series (olefines). They have been carefully investigated by Pelouze and Cahours, Warren, Schorlemmer, and Ronalds, and the results obtained by them are given in the following table, partly compiled from the review of the subject by Prof. S. P. Sadtler, in Prof. Genth's "Report on the Mineralogy of Pennsylvania" ("Second Geological Survey, 1874"). The letters F, R, W, P and C, and S, indicate the observers, Fouqué, Ronalds, Warren, Pelouze and 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.

MARSH-GAS SERIES.—FORMULA CnH2n+2·
No. NAME Formula. Carbon Hydrogen. Boiling-
Point (C.).
Specific
Grav. (0° C.).
Observer.
1 Methyl hydrid (methan) CH4 75 25 A gas. .559 F.
2 Ethyl hydrid (æthan) C2H6 80 20 " F.
3 Propyl hydrid (propan) C3H8 81.81 18.19 −17° F., R.
4 Butyl h. (normal butan) C4H12 82.8 17.2 0 .600 W.
5[2]  Pseudo-butan " " " 17
6 Amyl h. (normal peutan) C5H12 83.33 16.67 87−39 .645 W.
7 Dimethyl-propan " " " 30.2 .626 (17°) P.& C., W., S
8 Hexyl h. (normal hexan) C6H14 83.72 16.28 68.5 .689 P.& C., W., S.
9 Æthyl-isobutyl " " " 61.3 .676 W.
10 Heptyl h. (normal septan) C7H16 84 16 98.1 .780 W., S.
11 Æthyl-amyl " " " 90.4 .718 W., S.
12 Octyl h. (normal octan) C8H18 84.21 15.79 127.6 .752 W.
13 An isomer of No. 12 " " " 119.5 .787 W., P & C.
14 Nonyl hydrid (nonan) C9H20 84.38 15.62 150.8 .756 W.

Pelouze and Cahours carry the marsh-gas series to C16H32, hut 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 Rue and Müller found naphthaline, C10H8, in Rangoon tar; and, finally, a member of the anthracene series, CnH2n—18, has been found in the last products of the distillation of petroleum for paraffine-oil. It is probably formed by destructive distillation of the petroleum, and has been called thallene or viridine by Prof. H. Morton, who investigated especially its fluorescent character.

Petroleum undergoes alteration by evaporation of its lighter constituents, leaving viscid or solid bitumen, containing more or less paraffine; by oxidation of some hydrogen, giving rise to ethylenes, benzols, or naphthalenes; and, by the additional absorption of oxygen, forming true asphaltum. Of this latter class are the grahamite of West Virginia and the albertite of Nova Scotia. The grahamite I believe to have been altered before reaching its present level, for reasons which cannot be given here. Mr. W. P. Jenney has made some interesting experiments on the oxygenation of petroleum and the formation of artificial oxygenated hydrocarbons resembling natural products (American Chemist, April, 1875).

Occurrence of Petroleum.—It occurs in rocks of nearly all ages, from the Lower Silurian up; most abundantly in shales and sandstones; also to some extent in limestones. Sometimes it impregnates the whole stratum; sometimes it collects in subterranean cavities and fissures. In the Rangoon and Caspian regions the oil occurs near the surface in clayey soil, and collects in shallow pits. A noted foreign locality is Ye-nan-gyoung, in Burmah, where the wells are narrow shafts, 180 to 300 feet deep, and large enough for a man to work in. The oil is drawn up with a bucket and windlass, and as many as 1,000,000 barrels are annually obtained. In Persia oil is largely found at Baku, on the west shore of the Caspian; China yields a small amount of oil; Japan has small and undeveloped districts; New Zealand, also, shows indications. In the Caucasus, Russia, surface-wells have long been worked, and lately wells have been sunk with great success. In Galicia, Austria, are wells yielding largely; and Alsace and Hanover have produced some oil. Petroleum has likewise been found in Peru, Ecuador, Southern Mexico, San Domingo, Trinidad, and Nova Scotia, in small quantities.

The petroleum district of Canada West is in Lambton, Bothwell, and Kent Counties (H. E. Wrigley), and in Ontario. The average production is not over 2,500 barrels daily. It occurs mainly in the Corniferous limestone of the Lower Devonian, but is also found in greater or less quantity in the Bird's-eye limestone of the Lower Silurian, and the Lower Helderberg limestone of the Upper Silurian. The cavities of Orthocerata in the Trenton limestone (Lower Silurian) at Pakenham, Canada, frequently hold small quantities of petroleum. In Canada East there is a petroleum district on the St. John's River, not far from Gaspé Bay.

In the United States oil is very abundant in Western Pennsylvania, and has been found in considerable quantity in West Virginia, Ohio, Kentucky, and Tennessee. It has also been found, but in small quantities, in New York State, near Chicago, in Michigan, Indiana, Colorado, and California. The oil of Southern California comes from Tertiary shales, and is said to contain no paraffine.

The Upper Oil-Region of Pennsylvania begins in the vicinity of Tidioute, on the Alleghany, in Warren County, and runs southwest to Titusville, thence nearly south, along Oil Creek, into Venango County to Oil City, and thence southwest to Franklin. East Sandy, on East Sandy Creek, is at the extreme southeast edge of this field, and forms the only connecting link between the upper and lower oil-fields of the State. The principal points in this upper region are Tidioute, Triumph, and Economy, in the Tidioute District; West Hickory, New London; the Titusville District, including the Drake well; Church Run, Pit-Hole, Shamburg, Petroleum Centre, Rouseville (between these two places were the Blood well, of 1,000 barrels daily, and the Phillips well, which once flowed 3,940 barrels in twenty-four hours, and has produced over 500,000 barrels), Oil City, Sage Run, and Franklin. The Valley of Oil Creek, within a length of twenty miles, produced over $110,000,000 worth of oil, from an actual area of less than three square miles.

The Lower Oil Belt begins at Triangle City, Beaver Creek, Clarion County, and runs southwest twenty-one miles to St. Joe, in Butler County, and is the greatest producing area so far found (H. E. Wrigley, op. cit.). In 1866 rock with some oil was struck at Brady's Bend at a depth of 1,100 feet, giving rise to further investigation of the river above, which resulted in the discovery of a sand-rock of 57 feet thickness, at a depth of 960 feet, on the Alleghany River at Parker's Landing. A number of wells that had been supposed failures were afterward drilled to the proper depth, with great results.

The oil-bearing rock of Pennsylvania is a sand-rock, of which different strata are struck at different depths.

The operators speak of these as the first sand, second sand, and so on. After going through loose soil and a shale or slate-rock, the first sand is struck generally near the surface in the upper oil-regions (at a depth of 71 feet in the case of the first well sunk, the Drake well); 100 to 200 feet below this is the second sand; at 300 to 400 feet more the third sand, and then a fourth and fifth sand at intervals of about 150 feet. These sand-rocks are generally light-colored, and are separated by slate and other dark sand-rocks.

The heavy oil of Franklin comes from a sand-rock 260 feet deep, and from 50 to 80 feet in thickness. The rower sand-rocks are said to produce very bright, pure oils. Only 39.5 square miles of the 3,115 miles of the oil-region of Pennsylvania are actually productive.

The West Virginia oil-wells occur along an anticlinal extending from the borders of Southern Ohio through Wood, Wirt, and Ritchie Counties, between thirty-five and forty miles. No oil is found in the horizontal rocks, but it occurs along the disturbed and broken, tilted strata on the edges of the line of uplift. This same belt runs north into Ohio, through Washington and Morgan Counties into Noble County. Volcano, White Oak, and Burning Springs are the principal points in West Virginia. The oil is found in subcarboniferous rocks, ascending to them from the underlying Devonian.

In Ohio there is another oil-belt, west of the above, beginning in Perry and Morgan Counties on the north, and running south through Athens into Meigs County; and in Cuyahoga and Trumbull Counties are oil-regions closely related to those of Western Pennsylvania. The "Mecca" oil, a valuable lubricating oil, occurs in the Mecca Oil Rocks (Berea grit and Bedford shales) of Trumbull County, Ohio. The total production of Ohio and West Virginia is not over 500 barrels daily (Wrigley).

The Kentucky oil-district is mainly in Barren and Cumberland Counties, with a small adjoining tract south of it in Overton County, Tennessee. A well in Cumberland County, 191 feet deep, produced 300 barrels daily. The abundant supply from Pennsylvania and the difficulty of transportation have prevented these regions from becoming well known.

Origin and Source of Petroleum.—At first it was held by many that petroleum was a result of distillation from the bituminous coals, which were found in its vicinity, and this belief was strengthened by the fact that some of the very bituminous coals, such as Cannel and Boghead coal, afforded large quantities of similar oils on being distilled; but, although this is very probably the source of a small amount of oil, yet the larger part of it is now believed to derive its origin from rocks lying below the coal-measures, since the oil-bearing rocks are mostly older than the carboniferous formations.

Some investigators have ascribed a vegetable origin to petroleum, but most authorities agree in attributing it to animal as well as vegetable agencies. Shales are the most common oil-bearing rocks, and in their formation the organic materials would be finely divided and protected from oxidation. The oil-bearing shales commonly show few vegetable remains, and Dana observes that the absence of distinct fossil animal and vegetable remains points to an abundance of delicate water-plants or infusorial or microscopic vegetable life as the source of the organic material contained in them. Limestones, on the other hand, are frequently full of animal fossil remains, showing an animal origin for the oil in them, although it is by no means agreed that the petroleum in certain limestones was derived from organic remains in the limestones and not from other strata below them. In whatever shape the finely-divided material was originally present, it would be finely diffused through the mud, and protected from atmospheric agencies, and subsequently the hydrocarbons would be formed from them, probably at but a slight elevation of temperature, produced by the same agencies which have caused elevations in the temperature of the interior of the earth's crust at various points.

Dana has further pointed out how petroleum might be formed by the reactions of the organic vegetable remains alone, the abstraction of some carbon and oxygen, as carbonic acid, accounting for the formation of the lighter oils; while the escape of some marsh-gas from less confined material would account for the heavier oils.

Newberry attributes the disagreeable smell of some limestone-oil to its animal origin, and Dufrenoy alludes to the abundance of fish fossils as a proof that the oil of various European districts was derived from animal remains.

As regards the circumstances favoring the accumulation of petroleum, it appears that there should be a shale or other fine-grained rock forming to protect the organic matter during its deposition, a porous stratum above to be penetrated by the hydrocarbons resulting from the decomposition of the organic matter, and finally another shale or slate above, to prevent the further escape of the volatile products. If the sand-rock which usually forms the porous stratum is filled with fissures, large quantities of oil may collect in these.

The petroleum of Enniskillen, Canada, is ascribed by Hunt to the Coniferous limestone of the Lower Devonian. Many geologists ascribe the oil of Pennsylvania, West Virginia, Ohio, and the rest of this grand oil area, to the black shale or Genesee slate of the Middle Devonian. Dr. J. S. Newberry, in his "Report of the Geological Survey of Ohio," says of the Huron (black) shale of the Middle Devonian in Ohio, that it is bituminous, and contains sheets of asphalt or asphaltic coal. Oil and gas springs are associated with its outcrop, and there is reason to believe that it supplies the wells of Oil Creek, Pennsylvania. Hydrocarbons are the product of spontaneous distillation in the outcrops of the Huron shale in Ohio. It shows traces of marine vegetation, and represents the Gardeau shale of New York, with whatever there is in Ohio of the underlying Genesee slate. Its materials appear to have accumulated in a quiet water-basin, being marine and not terrestrial vegetation. It forms a vast repository of hydrocarbonaceous matter, yielding ten to twenty gallons of oil per ton by distillation.

A line of oil and gas springs marks its outcrop, from Central New York to Tennessee. Emanations of oil and gas occurring from Lower Silurian rocks at Collingwood, Canada, and on the Upper Cumberland River, Kentucky, are associated with similar deposits of black shale representing the Utica shale (Lower Silurian) of New York. The wells of Oil Creek penetrate strata immediately overlying the Huron shale, and the oil is obtained from fissured and porous sheets of sand stone of the Portage and Chemung groups, which lie just over the Huron and offer convenient reservoirs for the oil it furnishes. It is a well-known fact that wells sunk into the black shale yield no considerable quantity of oil, unless from strata resting upon it.

The foregoing statements, it will be seen, go to substantiate the theory upheld by Newberry, in common with other geologists, that the strata yielding much oil have only served to store the oil which comes from other strata below. T. S. Hunt holds that the petroleum of the limestone of Ontario, Canada, and other localities is largely the result of decomposition of the organic matters in these same rocks, and not of distillation from below. This view Newberry opposes on the following grounds: The Corniferous limestone, from his very extended observations, contains little hydrocarbons; oil and gas springs are rare where it underlies the surface; no considerable quantity of petroleum has been derived from wells in the Corniferous, Niagara, or any other limestone; even at Chicago there are no paying wells. Borings have been unsuccessful in Ohio wherever the Corniferous is the surface rock; and, further, there is no Corniferous limestone where Hunt cites it in Kentucky. There is positive proof that part of the oil comes from a lower horizon, and probably the Canada oil comes from underlying Silurian Collingwood shale. On Oil Creek are the argillaceous shales of the Waverley and Chemung strata, forming the sides and bottom of the valley, and below are several beds of sandstone, with the black shales of the Portage and Genesee still lower. In Ohio these favorable conditions are wanting; the sand-rocks of Oil Creek thin out and give place to fine, impervious, argillaceous shales; the strata become more homogeneous and free from crevices, and hence the oil cannot penetrate them so well. In Cuyahoga County, Ohio, the wells reach down through carboniferous rocks to the Huron shale, but there are no good wells, because the sandstone reservoirs are lacking, and only close-grained shales are present.

Hunt, on the other hand, holds that the petroleum of Southwest Ontario, and probably in other localities, is to be sought in the oliferous limestones of the Corniferous and Niagara formations, both of which abound in indigenous petroleum (American Journal of Science, III., ii., 369), which, in the case of the Ontario limestone, he shows cannot have come from overlying strata. He also mentions a well sunk at Terre Haute, Indiana, 1,900 feet deep, which yields two barrels of oil daily; and a second one, very near, which yields 25 barrels. This one is 1,625 feet deep, and passes through 700 feet of coal-measures, 700 feet of carboniferous limestone, with underlying sandstone and shales, 50 feet of Genesee slate (or its equivalent), and at a depth of 25 feet below this the oil-vein was met with in Corniferous limestone. A third well, a mile east, at a depth of 2,000 feet showed no oil.

The truth seems to be, that these limestones may contain a little petroleum indigenous to them, but they have not furnished the grand supplies of very productive regions. Before leaving this part of the subject, mention should be made of the gas which so generally accompanies the oil. It is often met with in the oil-regions when no oil is struck, producing "gas-wells;" and is also met with where no oil, or very little, is found, on the borders of the oil-districts. Many private residences and manufacturing establishments are heated and lighted by this gas; Fredonia, New York, has been lighted with it for years. The Newton gas-well, five miles south of Titusville, Pennsylvania, is 786 feet deep, and yielded 4,000,000 cubic feet per day, supplying light and fuel to a great number of dwellings and manufactories in Titusville. A rolling-mill near Pittsburg is run by gas brought from Butler County, a distance of about nineteen miles, and when it is not needed the gas is lighted, furnishing a jet of flame seventy feet high, which, with another jet from a neighboring mill, furnishes a grand spectacle at night.

This gas is the cause of spouting-wells. If a well is sunk into the top of a fissure containing oil and gas, the gas will first escape, and then the oil must be pumped out; but, if the well strikes in the oil, the pressure of the gas would first drive out the oil. If water also was present and the well struck the bottom of the fissure the heavier water would first escape, then the oil, and then the gas. Such a well, after standing a while would again yield oil on pumping, then perhaps water only, or water and oil, until it had had another rest. If the supply of gas is kept up by an open crevice, the well may continue to flow for some time. The pressure of neighboring water may also cause the oil to flow from a well. Generally the pumping-wells are pretty constant, although when a number of wells are bored near together they interfere with each other, and sometimes water poured down one well will appear in another, and this method has been pursued to bring rival well-owners to terms.

A few words may here be said about drilling wells and transporting the oil. The wells are drilled by means of drilling-tools like those used in sinking artesian wells, which are suspended by a cable, and operated by small steam-engines. The well is lined with wrought-iron tubing, screwed together in sections, and, to prevent water from flowing down the outside of the lining into the well, a water-packer is used, which is essentially a circular piece of leather with the edges cut and turned upward, so that the whole forms a cup about the tube, which is pressed tightly against the sides of the well by the weight of the column of water. It is much better than the old flaxseed bag. The oil is conveyed from the oil-district to the refineries and shipping-stations by means of wrought-iron pipes, two to four inches in diameter, which form a network throughout the entire country, and have an aggregate length of nearly 2,000 miles. One company carries the oil thirty-seven miles, in this way, from Butler County to the vicinity of Pittsburg.

Refining and Uses of Petroleum.—Crude petroleum contains gases and volatile liquids giving off at ordinary temperatures gases, which form explosive mixtures with air; heavy oils, which injure its burning properties, but are useful as furnishing lubricators and paraffine; tarry and carbonaceous matters; sulphur and other compounds, which give an offensive odor when burned. It is therefore refined by distillation, to separate the useful products in a pure state. The general features of the process will be best illustrated by a practical example, and for this purpose we have selected the well-known refinery of Charles Pratt & Co., at Greenpoint, Long Island, manufacturers of Pratt's Astral Oil. This establishment has a capacity of 15,000 barrels weekly.

The crude oil, coming mostly from Pennsylvania, with a specific gravity of 46 to 48° Beaumé, is run into horizontal cylindrical stills of wrought-iron, heated by anthracite fires. Eight of these stills have a capacity of 600 barrels each, and there are eight smaller ones. From these stills pipes lead to large worms, cooled by running water, and connected with a series of small tanks, so that the products from each still can be separately collected, and the successive portions that come from the still can be kept apart, according to their specific gravity.

At about 160° Fahr. (70° C.) the gases begin to come off abundantly, and these are conducted from the lower end of the worms to heat the steam-boilers. At about 225° Fahr. (107° C.) gasoline, having a specific gravity of 85° B., begins to run from the worm; after an hour and a half, at a temperature of 325° Fahr. (163° C.) naphtha begins to run, with a density of 74 B., and continues for about three hours; at 350−400° Fahr. (177−200° C.) benzine, with a density of 62° B., begins and runs about one hour. For the remainder of the heat, about thirty hours, illuminating oil is collected, with a density of 48−50° B., and ending with a temperature of 750° Fahr. (398° C.). The residuum, having a density of 20° B., is drawn off and shipped in barrels to the paraffine and lubricating oil-works. Steam is then run into the still for nearly two hours to remove the gas, the man-hole is opened, and the coke scraped off to be used for fuel.

The results of this operation are about as follows:

Gasoline 3 per cent.
Naphtha 10 " "
Benzine 3 " "
Illuminating oil 75 " "
Residuum 4 " "
Coke and loss 5 " "
 Total 100

The residuum yields by subsequent treatment paraffine to the amount of about one per cent, of the crude petroleum.

The illuminating oil comes from the worm at a temperature of about 80° Fahr. (49° C.) and is pumped from the receiving-tank into the agitator, an immense cylindrical tank of boiler-iron, holding 1,800 barrels (a smaller one holds 500), where it is cooled (if necessary) to 60° Fahr. by water run in at the top by sprinkling from a hose, and drawn off below. Forty-four gallons of strong commercial sulphuric acid being added for every 100 barrels of oil, the mixture is agitated by air pumped in through a pipe leading down through the oil to the bottom. This is done by an engine, and produces a very thorough mixture, during which the temperature rises, and when it reaches 70° Fahr. (21° C.) the operation is ended. Water is then played upon the top for about three hours, when caustic-soda lye of 20° B. is added, in the proportion of 500 gallons to 1,800 barrels of oil, thoroughly agitated with the oil, and then drawn off at the bottom after settling. The sulphuric acid purifies the oil partly by combining with, partly by breaking up, the injurious compounds, and the soda is added to neutralize the acid. Finally, the oil is again washed with water and drawn off into bleaching-pans, of which one has a capacity of 2,000 barrels, and two others of 750 each. Here the oil is left under a roof and exposed to diffused daylight four or five hours, to improve its color, and is then removed to the storage-tanks. It is possible to expose the oil too long in the bleachers, injuring its color. It is a curious fact, noticed in several refineries, that the oil, after removal to the agitator and before treatment with the acid, sometimes gives off spontaneously inflammable gas, which has been known to take fire during the cooling with water.

The gasolene is used for making gas. The naphtha and benzine destined for the market are kept separate, but sometimes they are further treated at the refinery, and are then run together, and sent to the naphtha-works with a density of 68° to 70° B. Here they are treated in iron stills of 200 to 600 barrels capacity, heated by coal. The vapors are condensed in a series of three worms, and the operation is so managed that the various products are obtained of the required density. These products are gasolene, of 90° (sometimes 97°), 88°, and 86° B.; naphtha, of 76° and 71°; benzine, of 65° and 62°. Most of the benzine shipped is of the latter density. The barrels used for shipping all of these products are coated inside with glue.

The residuum is either "cracked" in special stills (a process of which we shall have more to say hereafter) or it is sold to be worked up for lubricating oils and paraffine.

Mr. Joshua Merrill, manufacturing chemist of the Downer Kerosene Oil Company, has made several very important discoveries in the treatment of petroleum, and a short account of them has been given in a "Memoir on Petroleum Products," communicated to the Society of Arts, Massachusetts Institute of Technology, by S. D. Hayes, March 14, 1872, from which some facts are here selected:

Neutral lubricating oil, free from offensive odors and tastes, was partly the result of an accident. The condenser of a still heated by direct fire and charged with 900 gallons of mixed heavy and light oils, became partially closed, and the pressure caused leakage at the bottom of the still. The fire was very gradually drawn, after 250 gallons of light oil had passed off. The next day the oil in the still was found to be light-yellow, nearly odorless, neutral, and dense; the light, odorous hydrocarbons having been removed, at this low temperature, without decomposing either the distillate or the oil in the still. Further experiments perfected the process, which is greatly aided by the admission of steam from an open pipe into the body of the still during distillation.

Mineral sperm-oil was the result of experiments by Messrs. J. and R. S. Merrill on burning heavy lubricating oil and paraffine in lamps, especially constructed for the purpose. The light was very good, but the liquid was too thick to ascend into the wick. To obviate this the oil was subjected to a partially destructive distillation, "cracking" it enough to render it mobile, but not volatile.

The manner in which the crude petroleum is treated to obtain these various products is briefly outlined here from Prof. Hayes's sketch: The crude oil is heated by steam in upright, wrought-iron cylinders, incased in wood, of 12,000 gallons capacity. About 15 per cent. of distillate passes off and is condensed in pipes surrounded by water, yielding gasolene and A, B, and C naphthas, which are separately collected. From the gasolene rhigolene can be obtained by a second distillation with steam-heat, condensing the first portions of the distillate by ice and salt; ten per cent, is obtained from the gasolene. The steamed oil is pumped from the naphtha-stills into small stills, holding 1,000 gallons each, and heated by direct fires. Only carbon remains in these stills, some uncondensable gas escapes, and the other products are: No. 1, crude illuminating oil; No. 2, intermediate oils; No. 3, crude lubricating oil. Each of these is redistilled in the same sort of still. No. 1 is agitated with sulphuric acid, then with caustic soda, and distilled, yielding 80 per cent, of its volume of finished kerosene (refined illuminating oil) and mineral sperm-oil, and nearly 20 per cent, of denser oil. No. 2 is at once redistilled, yielding chiefly crude lubricating oil. No. 3 is agitated with sulphuric acid and then distilled with caustic soda in the still, yielding mainly dense paraffine-oil. This is kept in wooden barrels in ice-houses from seven to ten days, and deposits crystalline paraffine, which is pressed in strong cloth bags, one above another, with sheet-iron between, and yields crude paraffine-wax and heavy oil. The paraffine is repeatedly recrystallized from solution in naphtha and pressed, until it is white and pure enough for sale. The heavy oil is heated in stills by direct fires, slowly increased, but kept as low as possible, and generally with the admission of steam, until 20 to 30 per cent, has passed over. The residue is ready for sale, haying only a slight odor like that of fat-oils, while the hydrocarbons that are condensed after passing over have a very offensive odor. The very last distillates from all of the destructive distillations are called "cokings," and are distilled by themselves, yielding mainly crude lubricating oil. The carbon separated in the stills contains some caustic soda, which can be obtained as carbonate by burning the carbon and lixiviating the ashes. The sulphuric acid used in agitating the oils is known as "sludge," and is sometimes sold to the makers of superphosphate of lime, although it has been occasionally successfully reconverted into oil of vitriol. The following list includes the commercial products which have been made from petroleum, being those already mentioned, with the exception of cymogene, which is distilled from gasolene, and condensed by a pump:

1. Cymogene, specific gravity 110° Beaumé; boils at 32° F. (0° C.); used in ice-machines. 2. Rhigolene, sp. gr. 100° B.; boils at 65° F. (18.3° C.); extremely volatile, producing by its rapid evaporation a temperature of —19° F.; used as a local anæsthetic. 3. Gasolene, sp. gr. 97°, 90°, 88°, and 86° B., as required by the market. The very light gasolene is ordered in small quantities, probably for ice-machines. The others are used in gas-machines, for which they are admirably adapted, and for various exceedingly dangerous lamps and stoves designed for their combustion. 4. Naphtha, sp. g. 70° to 76° B.; boils at 180° F. (27° C.), when of 70° gravity; used in manufacture of oil-cloths, cleansing, as a solvent for paraffine, etc.; sometimes fraudulently mixed with the higher-priced illuminating oils, or with crude petroleum, to be again sold to the refiner; also sold, under various names, as a burning-fluid, notwithstanding the certain danger attending its use. 5. Benzine, sp. gr. 65° to 62° B.; the boiling-point for 65° B. is 300° F. (149 C.); used in making paints and varnishes. 9. Illuminating oil (kerosene), sp. gr. 45° to 50° B.; boiling-point for 45° B. is 350° F. (177° C.). "Astral" oil and "mineral sperm" are particularly safe varieties, freed with care from explosive compounds. 7. Lubricating oil. "Neutral" lubricating oil has a specific gravity of 29° B., and boils at 575° F. (301.5° C.). 8. Paraffine, sp. gr. 0.87°; fusing-point for commercial paraffine about 110° to 150° F. (43.3° to 65° C.), according to its purity; boiling-point about 698° F. (370° C.); used for making water-proof fabrics, candles, lubricators, matches, chewing-gum, etc.

The refined illuminating oil should be free from more volatile compounds, which cause it to give off vapors that explode when mixed with air and ignited. Dr. White, President of the New Orleans Board of Health, found that, on adding to oil which "flashed" at 113° F. one per cent. of naphtha, the mixture flashed at 103°; with two per cent. at 92°; with five per cent. at 83°; with 20 per cent. the oil itself burned at 50° ("Report on Petroleum to New York Board of Health," Dr. C. F. Chandler, 1871). Dr. Chandler has found that the temperature of the oil in an ordinary glass oil-lamp ranges from 76° to 98° F., and in a metal lamp from 76° to 129° F., the lower limits being for rooms heated between 73° and 74° F., and the higher for a temperature of 90° to 92°. It is, therefore, evident that an oil giving off explosive gases at less than 100° F. must be dangerous, and even at 110° F. an accident might occur, but only in exceptional circumstances.

The oils must, therefore, stand a certain test, called the "flashing test," which consists in heating them, preferably, in a thin metal or glass cup which holds the oil, and is itself placed in another vessel full of cold water, which is gradually heated by a small spirit-lamp. The bulb of a thermometer is kept well immersed beneath the surface of the oil, draughts are to be avoided, and the heat very slowly raised. From time to time, as the flashing-point is approached, the temperature is noted, and a very small flame, as a gas-jet issuing from a glass tube drawn to a fine point, is quickly passed across its surface, taking care not to touch the oil. A faint blue flame will flash across the oil when it reaches a temperature at which explosive gases are given off. Although it is generally agreed that the temperature should be very gradually raised, fifteen minutes being allowed for a test, yet Calvert (Chemical News, May, 1870) states that an oil which flashed at 90° F., after fifteen minutes, showed a flashing-point of 101°, when thirty minutes were consumed in making the test. Oil of 100° is not safe absolutely. There is another test called the burning-test, the point at which an oil will take fire and burn; it is from 10° to 50° F. above the flashing-test (Chandler), and is of little value in determining the safety of an oil, because, as already shown, the addition of one per cent, of naphtha will lower the flashing-test 10° in a good oil, while it would not materially affect the burning-point. From the directions already given for testing oil any one can readily make the test, and in view of the large number of unsafe oils sold it is very important that such tests should be made before using an oil not known to be safe.

The subject of refining petroleum may be dismissed with a few words more about "cracking" oils. It is the object of the refiner to make as much illuminating oil as possible, and to do this advantage is taken of the fact that, when the vapors of heavy oils are heated above their boiling-points, carbon is deposited, and the condensed hydrocarbons resulting have a less specific gravity. This decomposition is technically called "cracking," and it was observed long ago that in distilling the heavier oils lighter hydrocarbons were obtained during the first stages of the operation, even when not wanted. Cracking can be accomplished by distilling the oils under pressure, or, as is the case in the very large stills now employed, by allowing the vapors of the heavier hydrocarbons, on condensing, to flow down again upon the now hotter oil in the still, whereby they are cracked, depositing carbon. By carefully adapting the heat to the changing character of the oil, the yield of illuminating oil can be increased, but a residuum is always left in the large stills to be afterward treated in smaller ones.

S. D. Hayes states that this operation can be reversed, and from two to ten per cent. of a heavy oil obtained from the lightest and cheapest gasolene or petroleum naphtha. This change he observed in an apparatus constructed by Mr. Z. A. Willard, for generating gases and hydrocarbon vapors for metallurgical purposes. It consisted essentially of upright wrought-iron cylinders, half-full of the naphtha, through which steam at the ordinary working temperature and pressure passed, vaporizing the naphtha, and maintaining a pressure of about fifty pounds to the inch. The steam and naphtha vapors were thus kept above the liquid at a temperature much above the boiling-point of naphtha, but never as high as 300° Fahr., and the decompositions appeared to occur rather in the vapors than in the liquid. The heavy oil drawn off below had a dark yellowish-brown color, was nearly odorless after a few days' exposure to the air, had a specific gravity of about 34° Beaumé, and boiled above 400° Fahr. By redistilling, it was broken up into lighter and heavier liquid hydrocarbons, paraffine, and separated carbon (American Journal of Science, III., ii., 184).

Petroleum as a Fuel and Gas-Producer.—The use of gasolene in gas-machines is well known, and sometimes naphtha has been used to enrich coal-gas, by decomposing its vapor at a cherry-red heat, so as to produce a gas rich in heavy hydrocarbons, which is mixed with the coal-gas. Crude petroleum has also been conducted continuously into red-hot cast-iron retorts, whereby it is decomposed and rich gas formed. The Lowe process, now making daily 120,000 cubic feet of gas, of 19.5 candle-power, for a five-foot burner, at Utica, New York, is very successful. It consists essentially in forcing steam through a generator partly full of anthracite coal, brought to intense ignition; the steam is decomposed, and the resulting hydrogen meets crude petroleum that trickles down through the top of the generator; the petroleum is carried in vapor with the hydrogen into a "superheater" filled with loose fire-bricks, previously intensely heated by the gases from the generator. Here the hydrogen and hydrocarbons react upon each other, producing a permanent gas, which is purified as usual. The resulting gas is of uniform quality, very pure, and the saving in labor and materials is about 35 per cent. over coal-gas (Scientific American, January 8, 1876).

As regards the use of petroleum for fuel, it has always been found difficult to secure the complete combustion of the oil, so as to avoid smoke; the complicated nature of the contrivances devised for its use has also worked against its introduction as a fuel; but a furnace for reheating and rolling scrap-iron into boiler-plate has been invented by C. J. Eames, and is worked in Jersey City, which deserves mention. Prof. H. Wurtz (American Chemist, September, 1875) has described it at length. A current of steam heated to incandescence, meeting crude petroleum as it drips slowly over cast-iron shelves, takes up all the oil and carries it to a chamber where it meets an air-blast .and passes on to the combustion-chamber. This is a cellular tier of fire-bricks occupying the space over the bridge-wall of an ordinary furnace. Here the combustion begins, and thence the flames pass into the furnace, heating the six piles of iron, of 500 pounds each, which form a charge. Eight tons of boiler-plate can be worked off in ten hours with 300 gallons of crude petroleum, to which should be added 500 pounds of coal for generating and heating the steam. Petroleum is also used as a source of power in hydrocarbon engines (G. B. Brayton's), its vapor being mixed with air and ignited.

Production and Value of Petroleum and its Products.—When the first abundant supplies of petroleum were obtained, the demand for it as an illuminator was small, and it could be bought at the wells for ten cents a barrel, or was even allowed to run to waste (Wrigley), but as the consumption increased the price rose steadily, reaching, in 1864, $13.75 per barrel. The average prices per barrel at Titusville are given below, taken from Stowell's Petroleum Reporter, Pittsburg:

1864 $7 62 1870 $3 74
1865 6 18 1871 4 50
1866 3 78 1872 3 84
1867 2 78 1873 1 84
1868 3 95 1874 1 29
1869 5 48 1875 1 48

The production of the Pennsylvania oil-region, from 1859 to 1874, according to Wrigley, has been as follows:

1859 3,900 barrels 1867 3,347,306 barrels
1860 650,000 " 1868 3,715,741 "
1861 2,113,600 " 1869 4,215,000 "
1862 3,056,606 " 1870 5,659,000 "
1863 2,611,359 " 1871 5,795,000 "
1864 2,116,182 " 1872 6,539,103 "
1865 3,497,712 " 1873 9,879,303 "
1866 3,597,527 " 1874 10,910,303 "

The yield for 1859 is put at about 2,000 barrels by Mr. S. H. Stowell, who has also kindly furnished the following statistics:

Total Yield of the United States in 1875.

Pennsylvania 8,787,506  bbls., of 42 galls.
Western Virginia (approximated) 182,000  " " "
All other sources, " 17,150  " " "
————
 Total 8,986,656  " " "

The total value of the crude oils at the wells, up to the end of 1874, is given by Wrigley as $235,475,120, with an additional value for the refining of 75 per cent, of the whole, at $2 per barrel, of over $100,000,000. The stock of crude oil on hand at the wells, in December, 1875, was 3,550,207 barrels. The total export from the United States during 1875 was: Crude petroleum, 378,532 barrels (of 40 gallons each); refined, 5,086,785; naphtha, 344,978. The average price of these in New York has been, per gallon:

Crude, in Bulk. Refined, in Barrels. Naphtha, in Barrels.
1875 6.59 cents. 12.99 cents. 9.67 cents.
1874 5.86 " 13.09  " 8.85  "
1873 7.62 " 18.21  " 11.07  "
1872 12.80 " 23.75  " 14.81  "

Estimating the freight at $2.50 per barrel to the sea-board, and including the cost of refining and handling, Wrigley puts the total value of petroleum exported to foreign parts from Pennsylvania, since the beginning of the industry, at a minimum of $260,000,000.

In 1874 nearly 600 wells were drilled, producing an average of 50 barrels each; in 1875, about the same number, with an average of less than 25 barrels; and there were 3,125 producing-wells in Pennsylvania, January 1, 1876 (Stowell).

According to the rules of the New York Produce Exchange, crude petroleum shall be understood to be pure, natural oil, neither steamed nor treated, and free from water, sediment, or any adulteration, and of the gravity of 40° to 47° Beaumé. An allowance of one-half of one per cent, for every quarter of a degree above 47° gravity shall be made to the buyer. Refined petroleum shall be standard white or better, with a fire-test of 110° Fahr. or upward. Settlements of contracts shall be as follows: Barreled oil or naphtha, on a basis of forty-six gallons per barrel; refined oil, in bulk, forty-five gallons; crude oil, in bulk, forty gallons.

Dr. Chandler states that the average cost per hour of light equal to eight candles is as follows—the gas being sixteen-candle power, with a five-foot burner, the standard kerosene flashing at 115° Fahr., and the sperm-candles burning each 120 grains per hour:

From sperm-candles, at 42 cents per pound 5.76 cents.
Gas, at $3 per 1,000 feet 0.75 "
Mineral sperm-oil, in German student-lamp, at 75 cents per gallon 0.57 "
 " " in Merrill's lamp 0.48 "
Astral oil, in flat-wick lamp, at 50 cents per gallon 0.46 "
 " " in German student-lamp 0.44 "
 " " in Merrill's lamp 0.34 "
Standard kerosene, in flat-wick lamp, at 40 cents per gallon 0.33 "
 " " in German student-lamp 0.31 "
 " " in Merrill's lamp 0.28 "
  1. Petroleum, literally rock-oil, from petra, rock, and oleum, oil.
  2. Not yet obtained in a pure state.