Until the discovery of the Pennsylvanian, the Burmese (Rangoon) petroleum, or rock oil, was one of the best known_ It is obained in a treacly state by sinking wells about sixty feet deep in the soil, and consists of several fluid hydrocarbons, with about ten or eleven per cent of the solid hydrocarbon paraffine. The different naphthas it contains are highly prized as burning and lubricating oils, and for removing greasy stains, on account of their agreeable smell. The naphtha which is found abundantly at Baku, on the shores of the Caspian sea, closely resembles the Rangoon in its qualities. The Persian naphtha is frequently pure enough for burning without rectification.
Prominent among tee wonders of our time, however, as regards new fields of industry and wealth, stand the discoveries of the naphtha, or, as they are called, the petroleum regions of the 'United States. Some of these sources of native naphtha were known to the Indians, by whom it was at one time collected for sale; but it is little more than twenty years since, by sinking deep wells, the great extent of the oil-bearing strata became known. The principal supplies are obtained in Pennsylvania, West Virginia, and Ohio, a considerable quantity being also obtained in west Canada. Other regions in North America produce it, bat the Pennsylvanian Meld is six or seven times greater than all the rest put together. Consul Fortnight, in his report on the states of Pennsyl vania, Ohio, etc., for 1870 and 1871, says: "The oil regions are 100 miles in length by 30 to 50 in breadth, and the number of wells to be tapped so great that the supply is I considered to be sufficient for a century to come at least." Much curiosity exists respecting the origin of these great natural sources of petroleum. It seems to be the general opinion of geologists that it has in most cases been produced by the decomposition of both vegetable an animal matters. In this respect it differs from coal, which has arisen from the decay of vegitable matter alone. It would appear that the Pennsylvanian oil proceeds from shales of carboniferous age; the Canadian from those of Devonian age. In both countries the oil is found in cavities in sandstone, and has therefore been derived from subjacent rocks. It is now known that petroleum has formed in rocks of nearly all geological ages. Prof. Dana, the American mineralogist, says that the conditions favorable to the formation of native naphtha, as shown by the characteristics of the deposits in which it is found, are: (1) the diffusion of organic mate rial through a time mud or clay; (2) the material in a very finely divided state; and (3), as a consequence of the preceding, the atmosphere excluded as far as possible from the material undergoing decomposition.
In Pennsylvania the first borings for petroleum took placein'1859; and in that year 82,000 bbls, (reckoned at 43 galls. each) were obtained; in 1861 the produce had reached 2,000,000 bhls.; and since then, as a rule, it has increased from year to year. In 1872 the total produce of North America was 7,394.000 bbls.; Canada furnishing 330,000 bids. In the same year the total exports from the United States of refined petroleum amounted to 2,951,310 bbls., an enormous quantity, considering the first exports took place so recently as 1861. Of late years the petroleum trade is said to have employed in North America as many hands as coal-mining and the working of iron.
In 1862 and 1871 acts of parliament were passed limiting the amcunt of petroleum to be kept in store, and regulating the sale of such kinds as give off an inflammable vapor below 100' F. There are special warehouses for the reception of petroleum at the London and Liverpool docks.
Terrible accidents have now and then happened with some of the more iufiammable American oils, by reason of their vapors exploding in the reservoirs of lamps. Most of these have, no doubt, taken place with oils whose vapors form an explosive mixture with air at a temperature below 100° F., but they can hardly be considered safe if their vapors will take fire on the approach of a light at less than 120° F. The vapor of the parafline oil prepared for illuminating purposes by Young's mineral oil company, and no doubt by other firms, from Scotch shale, will not form an explosive mixture below 120° F., and it is therefore quite safe. Since this oil has to compete with petroleum, such a standard can only be kept up at a loss, and there is therefore a great temptation to keep down the firing-point of these burning oils as low as possible, with a view to greater profit; and although accidents have happened with parafline oil, as well as with American petroleum, there is little doubt that the latter cannot be so thoroughly relied upon for Safety. It could easily be made so, however, if the lighter hydrocarbons which it con-, tons were carefully removed,