History. — Petroleum has been known by civilized man from the dawn of history. Herodotus wrote of the springs of Zacynthus (Zante), and the fountains of Hit have been celebrated by the Arabs and Persians. Pliny and Dioscorides describe the oil of Agrigentum, which was used in lamps under the name of “Sicilian oil,” and mention is made of petroleum springs in China in the earliest records of that ancient people. The abundance of petroleum and the firetemple at Baku on the Caspian have been frequently described by travellers who have gone overland from Europe to India, from the time of Marco Polo to recent years. Petroleum in North America was first mentioned by a Franciscan missionary, Joseph de la Roche d’Allion, in a letter written in 1629 and published in Sagard’s Histoire du Canada in 1636. Peter Kalm described the springs on Oil Creek in his book of travels in North America, published in London in 1772. In 1750 the French commander at Fort Duquesne described them in a letter to General Montcalm, and later, towards the close of the last century, frequent mention is made of oil-springs in correspondence relating to what is now western Pennsylvania, Ohio, West Virginia, and Kentucky. In 1765 and 1826 the British Government sent embassies to the court of Ava, in the reports of which mention .'- made of the petroleum springs and wells near Rangoon on the Irawadi. During the early years of the present century the occurrence of bitumen, and particularly of its liquid forms, was noticed by scientific men and travellers in various localities. In Europe, Boussingault’s researches upon the petroleum of Bechelbronn (Lower Alsace) and the discovery of paraffin by Reichenbach attracted much attention. Petroleum was observed and described as early as 1814 in Washington county, Ohio, in wells at that time being bored for brine. In 1819 a well bored for brine in Wayne county, Kentucky, yielded so much black petroleum that it was abandoned. It has continued to yield small quantities until the present time. In 1829 a well drilled for brine near Burkesville, Cumberland county, Kentucky, yielded such a flow of petroleum that it was regarded as a wonderful natural phenomenon. This well is estimated to have yielded, up to 1860, 50,000 barrels of oil, the larger part of which was wasted. Of the rest a few barrels were bottled and sold as a liniment in the United States and Europe under the name of “American oil.”

About the year 1847 E. W. Binney of Manchester, England, called attention to the petroleum discovered at Biddings, near Alfreton in Derbyshire, and a few years later he, together with James Young and others, commenced the manufacture of illuminating and other oils from it. The supply of crude material from this source soon became inadequate, and they then commenced distilling the Boghead mineral that had been found near Bathgate in Scotland. The success attending this enterprise soon attracted attention in the United States of America, and a number of establishments were in operation in the course of a few years, some of them being licensed under Young’s patents. In 1851, when petroleum on Oil Creek was worth 7 5 cents a gallon in the crude state, it was tested as a crude material for the manufacture of illuminating oil by Messrs William and Luther Attwood, and Joshua Merrill, at the United States Chemical Manufacturing Company’s works at Waltham, near Boston, Massachusetts, and its merits for that purpose fully established. But its scarcity at that time prevented its use in commercial quantities, and the establishments at Boston and Portland, Maine, under the charge of Messrs Merrill and William Attwood, continued to use Boghead mineral and albertite for a number of years after petroleum was produced in sufficient quantity. Petroleum was refined and offered for sale in Pittsburgh, Pennsylvania, as early as 1855, but the quantity was too small to influence even the local trade; it, however, created a small demand for the crude oil. The well-known fact that brine-wells often produced petroleum led those who sold the “American oil” to embellish the label on the bottles with a derrick and other accompaniments of a brine-well; and the story is told that the projector of the first well drilled exclusively for petroleum was led to undertake it through reflecting upon this picture. Some oil from one of the natural springs near Titusville, Pennsylvania, was sent to Professor B. Silliman, junior, of Yale College, and he made a report upon it which has become a classic in the literature of petroleum. This report was so satisfactory that a company was organized in New Haven, and E. L. Drake was sent to drill a well upon land that was leased in the valley of Oil Creek, a short distance below the spot where the city of Titusville now stands. The region was then almost a wilderness, and many delays were experienced before he succeeded in getting his men and machinery in operation. He was at first thwarted by quicksands and water, but he finally drove an iron pipe 36 feet down to the rock. This device, said to have been original with Drake, has been of great value in artesian boring ever since he used it. After drilling 33 feet on the 28th of August 1859, the drill fell suddenly 6 inches into a crevice, and was left until the next day, when the drill-hole was found to be nearly filled with petroleum. No spot in the entire territory where petroleum has since been obtained could have been selected where the oil was to be obtained nearer the surface. The success of this enterprise led to the immediate drilling of other wells, first in the valley of Oil Creek and its tributaries, and later over the higher land between Oil Creek and the Alleghany river below Tidioute. As this territory began to be exhausted, the region of the lower Alleghany, in Butler and Clarion counties, yielded wells of great richness, and finally the Bradford field in M i Kean county became the centre of production. A careful comparison of the situations of some of the most productive wells led to the discovery that the areas yielding oil were not irregular in outline, but extended across the country in narrow belts, without regard to the present configuration of the surface. The areas of these belts were in general parallel, and extended in a north-east and south-west direction, 15° to 20° from the meridian. As the exhaustion of the oil-fields of Butler and Clarion counties led producers to seek a more productive locality, lines were run by compass on the supposed axis of the oil-belt over forest-covered hills for many miles, until they reached the town of Bradford, near which wells had previously been drilled without success. Deeper wells were drilled, and oil was obtained, resulting in the development since 1875 of about 68,000 acres of the most uniformly productive and extensive oil-territory yet discovered.

In the province of Ontario, Canada, principally in the vicinity of Enniskillen, a territory of limited extent but great productiveness has been under development for the last twenty years. In the region about Baku and in the valley of the Kuban, at the eastern and western extremities of the Caucasus, petroleum has been obtained for an unknown period, and is now being produced from artesian borings in large quantities. In Galicia and Roumania it is also obtained in commercial quantities. These regions with the United States furnish the petroleum of commerce. Japan, China, Burmah, and Italy have yielded petroleum in quantities sufficient to supply a local demand, but the vast quantity of the American oil and low price at which it is furnished have rendered the production in these countries unprofitable.

Geographical Distribution.— Petroleum “was found about one hundred years since in making the duke of Bridgewater’s tunnel at Worsley, at Wigan and West Leigh in the Lancashire coal-fields, at Coalbrookdale and Wellington in Shropshire and Biddings in Derbyshire, two other coalfields; also in a peat-bog at Down Holland, near Ormskirk, in Lancashire, but never in commercial quantities. The greatest supply has not been more than fifty gallons a day, and even that soon diminished.” A tar-spring was known at Coalport, in Shropshire, early in the present century. Although there are extensive deposits of solid bitumen in eastern France and Switzerland, the petroleum springs that occur at Saint Boès, Basses Pyrénées, are unimportant. In Alsace, at Lobsann and Bechelbronn, petroleum has been obtained for many years for local uses. Although reported from many localities in Germany, the only point that has promised to be of any importance is the Lüneburg heath, south of Hamburg. Petroleum is also reported near Hölle, in Dithmarschen, Schlesλvig-Holstein. On the eastern shores of the Adriatic—in Dalmatia and Albania—and in the Ionian Islands, petroleum springs have been mentioned by the writers of classical antiquity. In Armenia and Persia petroleum has been used for unknown centuries, and it appears to be widely distributed in the mountains that surround the tableland of Iran. In Algeria, Egypt, Kashmir, the Punjab, Assam, Java, and other East Indian islands petroleum is reported. In North America the successful development of the petroleum-fields of north-west Pennsylvania following the completion of Drake’s well led in a few years to the drilling of wells in a great many localities λvhere petroleum-springs had been observed. The following so-called “petroleum-fields” have produced oil in commercial quantities more or less valuable. [table]

Besides these localities petroleum has been observed over an area 1500 miles long by an unknown breadth in the valley of the Mackenzie and its tributaries, and in New Brunswick, Newfoundland, and other portions of eastern Canada. It also occurs at many different points along the Appalachian system of mountains from Point Gaspé on the St Lawrence to northern Alabama. It has been noticed in Kansas, Missouri, Wyoming, Colorado, and Texas in the United States, in southern Mexico, in the West India Islands, and in the northern states of South America. Petroleum is one of the most widely distributed substances occurring in nature, but an examination of the geographical localities in which it chiefly occurs will show them to be intimately connected with the principal mountain-chains of the world.

Geological Relations.— It has been frequently remarked that petroleum occurs in all geological formations, from the Silurian up to the Tertiary. While this is true as a general statement, it is misleading, for petroleum is not uniformly distributed through all formations, but occurs principally in two epochs of geological history; these are the Silurian and the lower half of the Tertiary. The vast accumulations along the principal axis of occurrence in the western hemisphere are found in Silurian and Devonian rocks; the most productive axis of occurrence in the eastern hemisphere lies in the Eocene and Miocene of the Carpathians, Trausy1vania, and the Caucasus. In England the small quantity of petroleum that has been observed has sprung from the Coal-measures. In the valley of the Rhone and in Savoy it is in Jurassic limestones. The bitumen of the Apennines, of Dalmatia and Albania, of Roumania, Galicia, and the Caucasus, issues for the most part from rocks that are Eocene. But little is known respecting the geology of the bitumen of Asia Minor and Persia; the Punjab is also Eocene, and the little that is known of the deposits in Burmah and the East Indian Islands indicates that they are of the same age. East of the Mississippi river petroleum has been reported from localities that describe an ellipse upon the border of the Cincinnati anticlinal, which consists of an elevation of Silurian rocks extending from central Kentucky to Lake Erie, with the city of Cincinnati nearly in its centre, sloping beneath the newer formations in all directions. Starting at Great Manitoulin Island, in the northern part of Lake Huron, it is next reported at Port Huron, Michigan; Chicago, Illinois; Terre Haute, and in Crawford county, Indiana; Henderson, Cloverport, Bowling Green, and Glasgow, Kentucky; and around Nashville, and south-eastwards to Chattanooga, Tennessee, where the Silurian rocks again reach the surface. Turning north, the line extends almost unbroken through the eastern counties of Kentucky into Ohio and West Virginia, into Pennsylvania and New York, the ellipse being completed by the petroleum-fields of Canada. At Great Manitoulin Island petroleum was obtained in the Trenton limestone, at Chicago and Terre Haute in the Niagara limestone, both of which are Silurian. The Kentucky geologists regard the great Devonian black slate as the source of the oil in that State. There it is found saturating sandstones at Glasgow, and in crevices at Burkesville and other points on the Cumberland river. In the neighbourhood of Nashville, where the Lower Silurian rocks reach the surface, petroleum occurs within geodes, which are enclosed in the solid mass of the blue limestone. North-east of Nashville the present location of the oil is found to be in rocks that lie in an ascending series. Around Burkesville it is found in the Upper Silurian, immediately beneath the Devonian black slate. Farther north it lies in the Devonian and Subcarboniferous sandstones, which, in Johnson county, Kentucky, are now partly above the drainage-level of the country. The so-called “oil-break” of West Virginia and Ohio yields petroleum from sandstones that lie within the Coal-measures. Still farther to the north-east, in Pennsylvania and New York, the oil-sands are all found beneath the Coal-measures in the Upper Devonian, while in Canada they again descend to the Lower Devonian. “Petroleum exists in the Cretaceous rocks which extend along the eastern slope of the Rocky Mountains from British Columbia to Mexico, and in many of the interior valleys.” The bitumen of the Pacific slope, of Mexico, the West Indies, and South America, is Miocene in California and Eocene in Trinidad and Peru. From these statements it will be seen that there is a vast area in the Mississippi valley, estimated at 200,000 square miles, beneath which petroleum has been obtained, the formations of λvhich are nowhere more recent than the Coal-measures. Another vast area, extending from California through Mexico to Peru, and including the West India Islands, yields petroleum from Tertiary rocks; while on the eastern continent a belt of country extends from the North Sea to Java, the bitumen-bearing rocks of which are Tertiary so far as is known. At present the bulk of petroleum produced issues from rocks older than the Carboniferous, while the formations yielding bitumen, in by far the greater number of localities, are of Eocene age. In the great “oil-region” of the United States petroleum occurs in crevices to a very limited extent. In Canada and West Virginia it occurs beneath the crowns of anticlinals, and in Pennsylvania it saturates the porous portions of formations that lie far beneath the influence of superficial erosion, like sand-bars in a flowing stream or detritus on a beach. These strata are not of any particular geological age, but run through a vast accumulation of sediments embraced in all the formations between the Lower Devonian and Upper Carboniferous. They lie conformably with the enclosing rocks, and slope gently to the south-west. The Bradford field in particular resembles a sheet of coarse-grained sandstone 100 square miles in extent, by from 20 to 80 feet in thickness, lying with its south-western edge lowest and submerged in salt water, and its north-eastern edge highest and filled with gas under an extremely high pressure. In Galicia the sandstones holding the oil are very much disturbed, while in the Caucasus the deposits of sand are erratic both in regard to position and extent, and lenticular in outline, being enclosed in a formation consisting of stiff blue clay.

Chemistry.-— The first chemical research upon petroleum was conducted by Vauquelin in 1817 upon the naphtha of Amiano. Prior to the discovery of petroleum in commercial quantities, a number of European chemists had made determination of the atomic constitution of several different varieties, and it had become generally understood that the oil consisted of an equal number of atoms of carbon and hydrogen. It has since been determined that some varieties of petroleum contain nitrogen and others contain sulphur and oxygen. These last-named elements are, however, to be properly considered as components of impurities. The proximate principles of petroleum have been determined and examined chiefly by Schorlemmer in England, Pelouze and Cahours in France, and C. Μ. Warren and S. P. Sadtler in the United States. Many other chemists have contributed valuable assistance to the work. These researches have established the fact that Pennsylvania petroleum consists chiefly of two homologous series of isomeric compounds having the general formula C π H2n+2, at one extremity of which marsh gas is found and solid paraffin at the other (see Paraffin). This oil also contains a smaller proportion of the olefine series, having the formula C m Ho 7 ι, with traces in the Bradford oil of the benzole series. Rangoon petroleum contains a larger proportion of both the olefine and the benzole series than Pennsylvania oil. It has been shown that Caucasian petroleum contains the additive compounds of the benzole group which have the same percentage composition as the olefines and furnish an illuminating oil containing more carbon than Pennsylvania oils of the same specific gravity. The residues from the manufacture of petroleum have been shown to contain very dense solids and liquids of high specific gravity, having a large proportion of carbon and possessed of remarkable fluorescent properties. Some petroleums are easily oxidized into asphaltum and kindred products. Colourless illuminating oils under the action of light absorb oxygen, which is converted into ozone, and they become yellow and viscid and of greatly impaired quality when the action is prolonged.

Origin.— The origin of petroleum has been a subject of speculation among scientific men during the last half century. It is a subject involved in much greater obscurity than the origin of coal, for, unlike coal, it has no organic structure; hence it can only be inferred upon circumstantial evidence that it is of organic origin; yet such evidence is so strong that few competent judges have ventured to decide otherwise. The arguments in favour of a chemical origin have been advanced almost wholly by a school of French chemists during the last twenty years. They are based upon the results of a class of experiments first inaugurated by Berthelot, in which powerful deoxidizing agents like the alkali metals or iron at a white heat are caused to react with steam and carbonic acid. The hydrogen of the water and the carbon of the carbonic acid, having been deprived of their oxygen, unite in the nascent state to form a mixture of oily fluids closely resembling petroleum. Sufficient quantities of these oils have been prepared to prove their identity with each other and with crude petroleum. Before concluding from this circumstance that petroleum is the product of similar reactions, it is necessary to assume a condition of the earth’s interior concerning which we know nothing; and, while the theoretical chemistry of the earth, based upon the nebular hypothesis, does not forbid such possibilities, there are other considerations relating to the origin of petroleum based upon the known rather than the possible that render the assumption that petroleum is of mineral origin forced and unnecessary. It is found that, when shale, coal, peat, wood, or animal matter, in fact any recent or fossil organic matter, is subjected to destructive distillation at low temperatures, there is obtained among other products an oily fluid which chemistry shows to consist chiefly of the same compounds of carbon and hydrogen as are found in Pennsylvania petroleum. There are other petroleums, however, occurring in Canada, Tennessee, and other localities somewhat different in composition, which are often found under conditions that make it extremely difficult to account for their origin upon any hypothesis that does not regard them as a product of the decomposition of animal remains. They fill the cavities of fossil corals and orthoceratites in Canada and of geodes in Tennessee, in all of which the oil appears to be hermetically sealed until the rock-mass is broken. The formation in which these oils occur consists of thickly-bedded Silurian limestones that were probably deposited in a deep sea at a somewhat high temperature, in which vast quantities of sea-animals perished and became buried. It is therefore most strictly in accordance with observed facts to assume that these oils, in whatever manner they may have been produced from the original animal remains, are indigenous to the rocks in which they are found. These indigenous oils do not occur locally in considerable quantity, although the aggregate amount scattered through any formation in which they occur can easily be shown to be large.

In those localities, notably north-western...