pearing greenish in tint. The black oils in the United States are obtained from the Trenton limestone of Ohio and from California; the Pennsylvania oils are of amber tint. In addition to the hydrocarbons, which are the chief constituents of petroleum, the following substances may be present: Sulphur, nitrogen, hydrogen sulphide, carbon disulphide, arsenic, and phosphorus. The carbon percentage may vary from 79.5 to 88.7 per cent.; the hydrogen from 9.6 to 14.8 per cent.; the sulphur from 0.7 to 2 per cent., and in rare cases even 3 per cent.; nitrogen from 0.008 to 1.1 per cent. The hydrocarbons of all crude petrofeums fall either into the paraffin or olefin group, those of America belonging chiefly to the first and those of Russia to the second group. The number of different members of the paraffin series present may be very large; some Pennsylvania oils, for example, have yielded 18 different paraffin compounds, as well as a number of substances belonging to the ethylene group. The hydrocarbons of the olefin series predominate in the Russian oils and many others. The composition of crude petroleum from a number of different localities is given below:

boniferous, the latter being especially important in West Virginia. Four fields are recognized in Pennsylvania, the oil varying from amber to dark green. Ohio contains two districts. One of these, the Mecca-Belden field, is of minor importance; a second in eastern Ohio is a westward extension of the West Virginia area. The Lima-Indiana field extends from Lima southwestwardly into Indiana, lying without the Appalachian region as usually defined. The oil here is carried by the Trenton limestone of the Lower Silurian, the depth being about 1300 feet; it was first discovered near Findlay, Ohio. The oil is dark and heavy and resembles the Tennessee and Canada oils in its sulphur contents. Farther south oil is obtained from the Carboniferous in eastern Kentucky and in Tennessee. While new pools are discovered occasionally in the Eastern fields, the most important developments in recent years have been in the Southwestern and Western States.

Oil has been found at a number of localities in the Tertiary rocks of eastern Texas, and several fields, including the Corsicana, Nacogdoches, Beaumont, Elgin, San Antonio, and Sugar

The gravity of an oil is most commonly expressed in the degrees of the Baumé (B.) scale, on which water has a specific gravity of 10 degrees. The oils from Allegany County, N. Y., run from 38° to 41° B.; from Venango County, Pa., 46° to 48° B.; Warren County, Pa., 43° B.; Lima County, Ohio, 36° to 38° B.; Florence, Colo., 30° B. Russian oils average about 32° B. The lighter oils yield a better quantity of illuminants, while the heavier ones often serve well for lubricating purposes, etc. On exposure to the air many petroleums lose their more volatile constituents and change to a viscous or even solid condition resembling asphalt. The lighter colored varieties are often quite liquid, while the black or dark oils may be slightly viscous. The temperature at which crude petroleum solidifies ranges from 82° F. in some Burma oits to several degrees below zero in certain Italian oils. The flashing point may be equally low in the latter, but in others found on the Gold Coast it rises as high as 370° F. The boiling point likewise shows_considerable variation, from 180° F. in some Pennsylvania oils to 338° F. in certain oils found at Hanover, Germany.

DISTRIBUTION OF PETROLEUM. The most noted and most productive field in the United States is the Appalachian, which extends along the western slope of the Appalachian Mountains, from southwestern New York (and eastern Ohio), through western Pennsylvania into West Virginia, Kentucky, and Tennessee. The oil-bearing sandstones are partly Devonian and partly Car

C

H

Per cent.

Per cent.

Per cent.

83.5

13.3

3.2

84.3

14.1

1.6

84.9

13.7

1.04

82.0

14.8

3.2

84.0

13.4

Lake, are now being exploited. The first mentioned supplies both light and heavy oils, which are obtained from depths of 950 and 1175 feet respectively. The first well put down in the Beaumont field yielded 75,000 barrels of oil a day, spouting the liquid in a six-inch column to a height of 160 feet; nine days elapsed before the flow was brought under control. The Beaumont oil is a dark asphaltic oil with much sulphur, and is obtained at a depth of 1000 feet. Petroleum has also been discovered in western Louisiana, especially near Jennings, where it is found at a depth of 1800 feet. Southeastern Kansas and northeastern Indian Territory produce some oil from the Cherokee shales and sandstones of the Carboniferous. In Wyoming petroleum occurs in 18 scattered fields, and in formations ranging from the Upper Carboniferous to the Upper Tertiary, but mostly in those of Mesozoic age. The Cretaceous sandstone at Florence, Colo., yields a heavy oil which resembles that of Wyoming in being valuable as a lubricant. Oil has also been obtained in moderate quantities at Boulder, Colo. It is obtained at depths of as much as 2850 feet, and has a gravity of 42.5° B. California contains several oil fields in the southern part of the State. The rocks are of Cretaceous to Neocene age. The oil has an asphaltic base, and is chiefly valuable as a fuel. Petroleum is also known to occur in Washington, Arizona, New Mexico, Montana, and Utah. A moderate amount of oil is obtained from Lambton County, Ontario, at a depth of 400 to 500 feet. Cuba is known to have at

least small supplies of oil, and a limited quantity has been exported from Porto Rico. In Mexico active exploration has been carried on at several points in the Gulf Coast region with the result of finding supplies of good oil around Tampico. It has an asphalt base. Of the South American countries, Peru is the most important petroleum producer, most of the output coming from the Zorritos field. Petroleum is also said to occur in Venezuela, Argentina, and Ecuador, but it is not taken out of the ground to any extent. Russia is not only the most important foreign producer of petroleum, but the largest producer in the world, the fields in the Baku region of Southeastern Russia supplying enormous quantities annually. The greater part of the output comes from the Baku field proper, although important quantities are obtained from the Grosni field, 500 miles north of Baku. Rumania contains several promising oil fields, which occur in the same formations as the Russian fields. In Germany oil is obtained near Hanover, and also in Alsace, while some is supplied by the Carboniferous rocks of Great Britain, but does not begin to supply the local demand. In Japan petroleum is obtained on the northwestern coast, and some of it is refined. The crude material sometimes yields 60 per cent. of illuminating and lubricating oils. A high paraffin oil is found in Java, and Sumatra, Borneo, and the Burma field of India are important producers. While petroleum is known to occur in the Philippines, little is obtained, and that by primitive methods; the islands of Panay, Leyte, Guimaras, Negros, Bohol, Mindanao, and Cebú all carry some petroleum.

MINING AND TRANSPORTATION OF PETROLEUM. The modern method of drilling for petroleum is similar to that used in sinking gas and artesian wells. The most prominent feature of the oildrilling outfit is the derrick, which is a tall, pyramid-like wooden frame about 75 feet high, 12 feet square at the base and about 3 feet at the top. The cost of a rig, as it is called, ranges from $200 to $275. The diameter of the well hole is 10 or 12 inches at the surface, decreasing with depth to 5 or 6 inches. In Russia wells are drilled of much greater diameter, and 26 inches is not an unusual size for the beginning of the bore-hole. In many cases the oil does not flow when the oil-bearing rock is struck, and it is customary in this instance to explode a torpedo at the bottom of the drill-hole, whereupon the oil almost immediately begins to pour out of the well, sometimes with tremendous velocity. For details of petroleum mining, see WELL-SINKING. The question of cheap and rapid transportation of crude petroleum from the wells to the refineries is one of great importance. At first the oil was transported on carts, later it was carried in barges or by railway in tank cars, but these methods gave place to the system of pipe lines. At the present day the total length of pipe lines transporting Pennsylvania crude oil is probably over 25,000 miles. The pipes, which have a diameter of from 4 to 8 inches, are usually laid underground and have bends at regular intervals to allow for contraction and expansion. Stations with pumps and storage tanks are placed from 28 to 30 miles apart, the oil being received into the tank at one pumping station and then forced through the pipe to the next one. Since all petroleum contains more or less paraffin or wax, much trouble is often experienced in the clogging

of the pipes, especially in cold weather, and to clear them out an instrument known as the 'godevil' is sent through the pipe. This is so constructed that it is forced along by the moving current of oil and scrapes the paraffin off from the inside of the tube. Pipe lines have been built from the Appalachian oil region to Jersey City, Philadelphia, Baltimore, Chicago, and Cleveland.

REFINING. The refining of petroleum is based upon the separation of the component hydrocarbons by a process of fractional distillation. This is usually carried out in horizontal cylindrical iron stills, which are surmounted by a dome that connects with a vapor pipe. A common size of still is 30 feet long by 121⁄2 feet in diameter, with a capactiy of from 650 to 700 barrels of crude oil. When the latter is placed in the still and subjected to increasing temperature, the oils pass off in the order of their volatility; the separation is not absolutely perfect, however, as oils of lower boiling point may carry over some higher ones. As the vapor rises it passes to the condenser, a series of iron pipes surrounded by cold water. The distillates are led off into their respective tanks. This process of distillation, which is known as the intermittent system, is the one commonly followed in the United States, and the still requires periodic refilling. In Russia a continuous system is employed, involving a series of stills, which are heated to successively higher temperatures. The crude oil then flows slowly from one to the other, and from each one there passes off the product volatilizing at the temperature to which the still is heated.

The process of fractional distillation can be divided into two parts. In the first part of the process the more volatile products, such as gasoline and other naphthas, are evolved. The residue is then transferred to another still in which the second part of the operation is carried on, the oil being heated to a still higher temperature for the purpose of separating the illuminating and lubricating oils. The condensing apparatus ends in the tail house, where the distillates are conducted to their proper tanks. When the various fractions of the distillation are to be kept separate, and of constant composition, a special form of condenser may be used, by means of which the oil is brought into contact with the surface of iron turnings, thereby increasing the evaporation. If the oil contains sulphur it is necessary to redistil it in stills containing copper oxide, which removes the sulphur. Cracking is a term used to denote the process of condensing the heavier vapors in the still, causing them to become superheated and decomposed, and thus obtaining a more complete separation of the fractions, as well as increasing the percentage of illuminating oil. In the distillation of the oil the lightest constituents pass off first and the heaviest last. The fractions obtained in the order of their lightness are the following: Cymogene. This is the lightest of all, and since its boiling point is 32° F., it is a gas at ordinary temperatures. Rhigolene. Boiling point, 65° F. Petroleum ether. A highly volatile product having a specific gravity of 0.635. It has sometimes been called Sherwood oil. Gasoline. This, properly speaking, is the fraction following petroleum ether, although the name is often applied to a mixture of this and the three previous ones, its gravity thus ranging from 0.635 to 0.690.

In

gasoline proper the boiling point ranges from 90° to 200° F. Naphtha is a name broadly applied to all light distillates, but more especially to those boiling at 80° to 120° F., and whose gravity varies from as low as 62° B. up to 76° B. Benzine (q.v.) represents the least volatile product of the naphthas and has a specific gravity of about 0.73 (57° to 62° B.), and a boiling point of 120° to 150° F. Ligroine forms a special grade of solvent naphtha of a specific gravity of 0.715, and a boiling point of 194° to 248° F. Following the lighter naphthas come the illuminating oils, divided into heavy and extra heavy naphthas; in the process of distillation these may either be carried off separately or together. In the former case, the heavy naphthas may be redistilled and separated into benzine and light distillate. The latter may then be mixed with the extra heavy naphthas in varying proportions to form white oil or export oil. There are many grades of domestic illuminating oil or kerosene, which differ chiefly in fire test.

After the naphthas have passed off, the residuum is forced through steam-jacketed filters filled with bone black or fuller's earth; the first portions of the filtrate represent light oils, and are followed by successively heavier ones. When the petroleum belongs to the paraffin group, the residuum is sometimes placed in the tar still for further distillation, and there the heavy vapors are carried over by the aid of superheated steam, the presence of the latter also preventing dissociation of the oil, which if it occurred would be followed by a lowering of viscosity of the lubricating oil and a decrease in the amount of paraffin obtained. The distillates containing the paraffin are freed from the latter by chilling, the effect of this being to cause a separation of the waxy paraffin scales. The oils thus freed from the paraffin are important lubricants, and under this class a number of grades are known as spindle oil, engine oil, summer dark oil, winter dark oil, cylinder oil, valve oil, etc. The residue now left in the tar still is a porous mass of separated carbon, solid decomposition products termed coke. The tar is sometimes used without further distillation for the manufacture of vaseline.

Many of the distillates obtained in the treatment of crude petroleum contain acid constituents as well as compounds which in time impart a dark color and unpleasant odor to the distillate. Raw distillates, when used for illuminating purposes, also rapidly char the wick and lose their power of being drawn upward by capillarity. It is therefore customary to purify the various fractions obtained by treatment with sulphuric acid and caustic soda, before they are marketable. The distillate, which has been first cooled to 60° F., is agitated with sulphuric acid in tall cylindrical tanks of wrought iron lined with sheet lead, and known as agitators; about 11⁄2 to 2 per cent. of acid is required. The acid is then washed out with water, and a 1 per cent. solution of caustic soda added, after which a second agitation takes place, followed by washing.

The percentage of the various fractions yielded by different oils varies. Many Pennsylvania oils yield 8 to 10 per cent. naphtha, 70 to 80 per cent. refined oils, 5 to 9 per cent. residuum and 5 per cent. loss. In the distillation of 100 gallons of crude petroleum there are obtained on the average about 76 gallons of illuminating oil, 11 gallons of gasoline, benzine, and naphtha, and 3

gallons of lubricating oil, while the residuum and loss amount to 10 gallons.

TESTING OF REFINED OILS. Refined oils are usually tested for their color, gravity, flashing and burning points, and sometimes for their behavior when cooled (cold test). The color is determinable by inspection. The gravity is a measure of the purity of the distillate. Too large a proportion of the lighter oils renders the product unsafe for illuminating purposes, while too great a percentage of the heavier oils interferes with its free burning qualities. The gravity test is commonly made by placing the oil in a tall jar and inserting a hydrometer marked preferably with the Baumé scale (water has a value of 10 on this scale). The temperature of oil when this test is made should be 60° F. The fire test inincludes the determination of the flashing point, i.e. the temperature to which the oil must be heated in order to produce a momentary explosion of the mixture of inflammable vapor, and of the burning point, i.e. the temperature to which the oil must be heated in contact with the air to take fire and burn on the surface. The burning point is commonly from 6° to 20° C. higher than the flashing point. Kerosene for lighting. purposes should have a flashing point of not less than 110° F., and a burning point of not less than 125°. Both the flashing point and burning point are carefully regulated by law in most civilized countries so as to run the minimum risk from explosion. The cold test is of importance for lubricating oils, and is made in order to determine the temperature at which the oil thickens or becomes cloudy. It can be made by cooling the oil in a small tube and noting the temperature at which the oil ceases to flow when the tube is inclined.

USES. The two chief uses of the distillates from crude petroleum are for illumination and lubrication, but the various fractions in many cases have special applications. Rhigolene is used as a local anesthetic; petroleum ether is employed as a solvent for caoutchouc, fatty oils, and plant principles, and for carbureting air in gas machines; gasoline is employed in the extraction of oil from oil seeds, in carbureting coal gas, in gasoline lamps, stoves, and plumbers' lamps. Naphthas in general are employed as solvents for resins in varnish-making, and in the manufacture of oilcloth. Boulevard gas fluid is a product of 0.68 specific gravity used in street lamps, while benzoline is a deodorized naphtha of 0.70 specific gravity. Benzine is employed for dry cleaning, as a substitute for and adulterant of turpentine for cleaning printer's type, and for dyers' and painters' use. The benzine of the U. S. Pharmacopoeia has a specific gravity of 0.67 to 0.77, and a boiling point of 122° to 144°, and therefore represents a higher distillate. Astral oil and mineral sperm oil are special illuminating oils of high flashing points. Crude petroleum is much used for fuel purposes in engines. Along the Pacific Coast, especially in southern California, where good coal is scarce, the locomotives consume large quantities of crude oil. Paraffin residue is placed on the market for medicinal purposes under the name of vaseline, petroleum ointment, and cosmoline. It is also used in the manufacture of chewing gum, and for insulating purposes in electric work.

PRODUCTION. The growth of the petroleum industry in the United States is shown in the fol: