worked by open quarrying is at the mines of the Baltimore Company, near Wilkesbarre. Here, too, an immense bed of coal was found so close to the surface that it was easily uncovered over a considerable area. As the overlying slates and sandstone increased in thickness, it was found at last more economical to follow the coal under cover; and it was then worked after the manner of mining the bituminous coal-beds west of the Alleghany Mountains. Horizontal drifts 25 feet high, which was the thickness of the bed, were carried in from the abrupt wall, several of them near together and separated by great pillars of coal left to support the roof. The gangways were so broad and spacious that a locomotive and train of cars might have been run into the mine. Within they were crossed by a succession of other levels, and through the wide spaces thus left open, the light of day penetrated far into the interior of the hill, gradually disappearing among the forest of black pillars by which it was obstructed and absorbed. In the anthracite region, several coal-beds of workable dimensions are often found in close proximity, so that when dipping at a high angle they are penetrated in succession by a tunnel driven across their line of bearing. Larger quantities of coal are thus concentrated in the same area than are ever met with in the bituminous coal-field. In the northern coal-fields, between Scranton and Carbondale, tracts have brought $800 or more per acre, and single tracts of 650 to 700 acres are reported upon by competent mining engineers as containing five workable beds, estimated to yield as follows-each one over nearly the whole area: one bed working 7 feet, 11,200 tons per acre; a second, working 8 feet, 12,800 tons per acre; a third, 6 feet, 9600 tons per acre; a fourth, the same; and a fifth, 3 feet, 4800 tonsaltogether equalling a production of 48,000 tons per acre, from which 20 per cent. should be deducted for mine waste, pillars, etc. The anthracite as usually brought out from the mines is mostly in large lumps of inconvenient size to handle. In this shape it was originally sent to market, and when sold to consumers a man was sent with the coal to break it up in small pieces with a hammer. At present every mine is supplied with an apparatus called a coal-breaker, which is run by steam power, and which crushes the large pieces of coal in fragments. It consists of two rollers of cast iron, one solid, with its surface armed with powerful teeth, and the other of open basket-work structure. These revolve near together, and the coal, fed from a hopper above, is broken between them, and the pieces discharged below into another hopper are delivered into the upper end of a revolving cylindrical screen, made of stout iron wire, and set on a gentle incline. The meshes of this screen are of four or more degrees of coarseness. At the upper end the finer particles only drop through; passing this portion of the screen, the coarser meshes which succeed let through the stove coal sizes, next the "egg coal," and next the "broken coal," while the coarsest pieces of all, called "lump coal," are discharged through the lower end of the screen. Under the screen are bins or shutes, separated by partitions, so as to keep each size by itself. Their floor slopes down to the railway track, and each bin at its lower end is provided with a trap-door, through which the coal is delivered as required into the wagons. The general plan of this arrangement is seen in the preceding wood-cut of the Colliery Slope and Breaker at Tuscarora. The coal wagons are here run from the mine up into the top of the engine house, and thence through the building to the breaker at the upper end of the slope over the shutes. As the coal falls from the screen into these, boys are employed, one in each bin, to pick out and throw away the pieces of slate and stone that may be mixed with the coal. This they soon learn to do very thoroughly and with great activity; and upon the faithfulness with which their work is done depends in no small measure the reputation of the coal. USEFUL APPLICATIONS. While anthracite, by reason of its simple composition, is fitted only for those uses in which the combustion or oxidation of its carbon is required to generate heat, or else to extract oxygen from other substances, the bituminous coals, containing a greater variety of ingredients, serve to produce from their volatile ingredients illuminating gas and coal oils. These two subjects will be treated in distinct chapters, and that upon the oils may properly include an account of the petroleum wells which have come within the past ten years to furnish so large and important an item of our exports and home consumption. CHAPTER X. ILLUMINATING GAS. combustible bodies-even water itself-are all resorted to as sources from which the cry for "more light" shall be satisfied. heating; but the first attempts to light buildings by gas distilled from bituminous coal were made about the year 1798 by Mr. Murdock in the manufactory of Messrs. Boulton and Watt, at Soho, England, and about the same time in France by a Frenchman named Le Bow. The London and Westminster Chartered Gas Light and Coke Company was incorporated in 1810, and Westminster bridge was lighted with gas, Dec. 31, 1813. The process was introduced into this country about the year 1821. Some attempts had been made at an earlier date, as in Baltimore according to some statements in 1816, and in New York four years before this. In the New York News of August 15, 1859, is an account of the ef forts made by Mr. David Melville of that The distillation of carbonaceous and biTHE supply of artificial light in abun- tuminous substances to obtain an illuminatdance and at little cost is one of the most ing gas is a process, the practical applicaimportant benefits which science and me- tion of which hardly dates back of the preschanics can confer. It contributes not ent century. The escape of inflammable merely to physical comfort and luxurious gases from the earth, in different parts of living, but supplies the means to multitudes the world, had been observed, and the of obtaining instruction during those hours phenomenon had been applied to superstiafter the cessation of their daily labors, tious ceremonials, especially at Bakoo on which are not required for sleep, and the shores of the Caspian. The Chinese which among the poor have in have in great are said to have applied such natural jets measure been spent in darkness, on ac- of gas to purposes of both illumination and count of the expense of artificial light. At the present day it is not unusual, in the less cultivated portions of the country, to see a farmer's family at night gathered around a blazing fire, and some among them seeking by its fitful light to extract the news from a public journal, or perhaps conning their school tasks, and making some attempts at writing or ciphering; and when the hour to retire has come, the younger members disappear in the dark, and the more honored are favored with a home-made tallow candle, just sufficient for this use, and endurable only to those who are unaccustomed to a more cleanly and efficient method of illumination. With the advance of cultivation and learning, the demand for better light has increased the more rapidly it has been met. The sea has been almost exhaust-city to establish the use of coal gas in 1812. ed of whales for furnishing supplies of oil. He lighted his own house with it, and then The pork of the West has been largely con- a factory at Pawtucket. He also succeeded verted by new chemical processes into lard in having it applied to one of the lightoil and the hard stearine for candles; and houses on the coast of Rhode Island, and numerous preparations of spirits of turpen- for one year its use was continued with suctine, under the name of camphene and burn- cess. But on account of the disturbed state ing fluid, have been devised and largely in- of the times and the prejudices against the troduced with ingenious lamps contrived to use of a new material, the enterprise fell secure the excellent light they furnish, with through. In 1822 the manufacture of gas the least possible risk of the awful explo- was undertaken in Boston; and the next sions to which these fluids are liable when year the New York Gas Light Company their vapor comes in contact with fire. The was incorporated with a capital of $1,000,bituminous coals have been made to give up 000. The works, however, were not comtheir volatile portions-by one process to pleted and in operation until 1827. Anafford an illuminating gas, and by another other company, called the Manhattan Gas to produce burning oils; and the earth it- Light Company, was incorporated in 1830 self is bored by deep wells to exhaust the with a capital of $500,000, which has since newly-found supplies of oil gathered be- been increased to $4,000,000. Such were neath the surface at unknown periods by the beginnings of this branch of manufacnatural processes of distillation. The res- ture, which has of late rapidly extended inous products of the pine tree are applied itself throughout all the cities and many of to the production of oil and gas for the the towns of the United States, having same purposes; and peat, wood, and other works in operation representing a capital of Within the last twenty years the use of gas production. In New York city and Brookhas increased with great rapidity throughout lyn, it has ranged from $2.00 to $4.50, the cities and towns of the United States. standing at present at $3.25, but with a In 1860, the number of companies manufac- promise of reduction soon to $2.75. In turing gas was; according to the statements Philadelphia, where the city manufactures of the American Gas Light Journal, 433, for its citizens, it is now, we believe, $2.25, representing a capital of about $59.000,000. and in Pittsburg has been as low as $1.50. In 1870, the number of companies had in- In the smaller cities it ranges from $4.00 to creased to somewhat more than 800, and the $8.00 per thousand feet. On the Pacific capital represented to over 112,000,000, thus coast, owing to the high price of gas-proranking with the most important branches ducing coals, it has been as high as from of industry in the country. The capital $8.00 to $14.00 per thousand feet. If the of the gas companies of the State of New Rocky Mountain coals prove to be of good York, is stated by Mr. Wells in his Report quality for the production of gas, the cost on Local Taxation, to have been $20,000,000 will be materially lessened. Notwithstandin 1870, and in this estimate many of the ing the consumption of petroleum oils, there smaller companies are overlooked. The has been an increase in the demand for illucapital of the gas companies of New York minating gas, and the plans proposed for its and Brooklyn in 1871 was over $14,000,000. production from other hydrocarbons, or by There are certainly five and probably six new processes, have generally failed, so that companies whose annual production exceeds there seems to be a probability of the contin1,000,000,000 cubic feet, and several others ued production of gas from coals. What new are approximating to that amount. The methods of illumination the next twenty price per thousand feet has varied greatly years may develop we cannot say; but it is in different sections, and has fluctuated in certain that a cheap, safe, and brilliant illuall cases with the price of the coal and in its minator is still a thing to be desired. Char SOME OF THE PRINCIPAL GAS LIGHT COMPANIES IN THE UNITED STATES. Prices to private consumers per 1000 cubic feet. $250 Average cost of coal used per ton. $6 50 to $11 00 Localities. tered. 2 50 1825, Brooklyn, N. Y.. 7 28 to 8 15 1859, Citizens' Co., Brooklyn. 1841, Philadelphia. TOTAL OF GAS COMPANIES IN THE UNITED STATES FROM RETURNS OF JULY, 1860. The preparation of illuminating gas from | and the rapidity with which the operation is bituminous coal, wood, rosin, and other conducted. The object in this special disbodies of organic nature, is a chemical proc-tillation is to obtain the largest proportion ess, too complicated to be very fully treated of the gases richest in carbon, particularly in this place. When such bodies are intro- that known as olefiant gas, which consists duced into a retort and subjected to strong of 86 parts by weight of carbon and 14 of heat, the elements of which they consist, as hydrogen, represented by the formula C carbon, hydrogen, oxygen, and nitrogen, re- H. This and some other gaseous hydrosolve themselves into a great variety of com- carbons of similar composition, or even conpounds, and escape (with the exception of taining a much larger amount of carbon in a fixed carbonaceous residue of charcoal or the same volume, and hence having a corof coke) through the neck of the retort in respondingly greater illuminating capacity, the form of gas or vapors, some of the it is found, are produced most freely from latter of which condense on cooling into carbonaceous substances which contain a liquids and solids. These compounds are large proportion of hydrogen compared with rendered more complicated by appropriating that of oxygen. Many of the common bithe elements of air and moisture that may tuminous coals contain about 5.5 per cent. be present in the retort or in the crude ma- each of hydrogen and oxygen, the rest beterial, and also of the foreign substances or ing carbon. Boghead cannel of Scotland impurities contained in the latter. In proc- contains 11 per cent. of hydrogen and 6.7 esses of this kind, the products vary great- of oxygen; rosin 10 per cent. hydrogen and ly in their character and relative proportions 10-6 oxygen; wood 5.5 hydrogen and 44-5 according to the degree of heat employed, oxygen. Of such compounds the cannel If too much carbon be present a part of smoky flame, hence the necessity of the diluents or gases deficient in carbon for neutralizing the too large proportion of those gases richest in carbon. The noxious compounds in illuminating gas, and which should be as far as possible extracted from it before it is delivered for consumption, are the sulphurous ingredients formed by the combination of the sulphur of the iron pyrites commonly present in bituminous coals with the carbon, and with the hydrogen and the ammoniacal products. They are the highly offensive sulphurets of carbon, the sulphuretted hydrogen, etc. Carbonic acid, nitrogen, oxygen, carbonate of ammonia and aqueous vapors are to be regarded as foreign substances, though always present to some extent in the gas. yields the richest gas and in largest quantity. Still, as will be more fully explained it escapes unconsumed and produces a hereafter, the process may be so conducted as to obtain chiefly liquid instead of gaseous products. With the olefiant gas and the others of similar composition, a number of other gases also appear, some of which seem to be essential for producing the effect required in illuminating gas, though they do not themselves afford light by their combustion. Their part is rather like that of nitrogen in the atmosphere, to moderate the intensity of the more active agent of the mixture. Such are the light carburetted hydrogen, carbonic oxide, and hydrogen, all of which are inflammable, but possess little or no illuminating power. The first named contains in an equal volume only half as much carbon as olefiant gas, its composition being represented by the formula C, H, and if its proportion is too great for the purpose it serves as a diluent, the quality of the gas is impaired, and must be corrected by the use of richer material or increased care in the process. The light produced by the combustion of gas is variable, not only according to the quality of the gas, but also according to the manner in which it is burned. If its elements undergo the chemical changes which constitute combustion simultaneously, the hydrogen combining with the oxygen of the air to form aqueous vapor, and the carbon with oxygen to produce carbonic acid, no yellow flame appears, but instead of this, a pale blue flame like that of hydrogen alone. Such an effect is produced when air is thoroughly intermixed with the gas as it passes through a tube to the jet where it is ignited. But if the conditions of the combustion are such that the hydrogen burns first and appropriates the oxygen in contact with the gas, the particles of carbon are brought to an incandescent state and produce the yellow light before they reach the oxygen with which they combine. The particles may even be arrested while in transitu and be deposited upon a cold surface in the form of soot. The greatest heat is produced with the most thorough mode of combustion and the appearance of the pale blue flame; and lamps designed to give great heat are now in general use among chemists, in which gas is burned in this manner. When the air is impelled by a bellows they even produce an intensity of heat sufficient for many crucible operations. The liquids generated by the distillation mostly condense in two layers on cooling, the upper an aqueous fluid, rendered strongly alkaline by the ammoniacal compounds in solution; and the lower a black tarry mixture commonly known as coal tar, which is composed of more than a dozen different oily hydrocarbons, as benzole, tuluole, etc., and contain in solution the solid oily compounds of carbon and hydrogen, as naphthaline, para-naphthaline, and several others. Many of these are likely to prove of considerable practical importance. Benzole is a highly volatile fluid, a powerful solvent of the resins, india-rubber, gutta percha, greasy matters, etc. A most beautiful light is produced by the flame of benzole mixed with due proportions of common air, and the mixture is effected by passing a current of air through the fluid, the vapor of which it takes up and carries along with it. The difficulty attending this application is the condensation of the benzole and its separation from the air at temperatures below 50°. Above 70° too much vapor is taken up, and the effect is a smoky flame. In Europe much attention has been directed to the separation of the more hidden products of coal tar; and among these the following are enumerated in a statement exemplifying the rapid increase in the value of these products as they are obtained by more extended researches. Benzole worth about 25 cents a pound; nitro-benzole, a substance having the odor and taste of bitter almonds and used as a flavoring, worth, crude, 70 cents, or refined, $1.50 per pound. The or |