By Mr. ANDREW CARNEGIE, New York.
In these days of depression in manufacturing, the world over, it is specially cheering to be able to dwell upon something of a pleasant character. Listen, therefore, while I tell you about the natural gas fuel which we have recently discovered in the Pittsburg district. That Pittsburg should have been still further favored in the matter of fuel seems rather unfair, for she has long been noted for the cheapest fuel in the world. The actual cost of coal, to such as mine their own, has been between 4s. and 5s. per ton; while slack, which has always been very largely used for making gas in Siemens furnaces and under boilers, has ranged from 2s. to 2s. 6d. per ton. Some mills situated near the mines or upon the rivers for many years received slack coal at a cost not exceeding 1s. 6d. per ton. It is this cheap fuel which natural gas has come to supplant. It is now many years since the pumping engines at oil wells were first run by gas, obtained in small quantities from many of the holes which failed to yield oil. In several cases immense gas wells were found near the oil district; but some years elapsed before there occurred to any one the idea of piping it to the nearest manufacturing establishments, which were those about Pittsburg. Several years ago the product of several gas wells in the Butler region was piped to two mills at Sharpsburg, five miles from the city of Pittsburg, and there used as fuel, but not with such triumphant success as to attract much attention to the experiment. Failures of supply, faults in the tubing, and imperfect appliances for use at the mills combined to make the new fuel troublesome. Seven years ago a company drilled for oil at Murraysville, about eighteen miles from Pittsburg. A depth of 1,320 feet had been reached when the drills were thrown high in the air, and the derrick broken to pieces and scattered around by a tremendous explosion of gas. The roar of escaping gas was heard in Munroville, five miles distant. After four pipes, each two inches in diameter, had been laid from the mouth of the well and the flow directed through them, the gas was ignited, and the whole district for miles round was lighted up. This valuable fuel, although within nine miles of our steel-rail mills at Pittsburg, was permitted to waste for five years. It may well be asked why we did not at once secure the property and utilize this fuel; but the business of conducting it to the mills and there using it was not well understood until recently. Besides this, the cost of a line was then more than double what it is now; we then estimated that £140,000 would be required to introduce the new fuel. The cost to-day does not exceed £1,500 per mile. As our coal was not costing us more than 3s. per ton of finished rails, the inducement was not in our opinion great enough to justify the expenditure of so much capital and taking the risk of failure of the supply. Two years ago men who had more knowledge of the oil-wells than ourselves had sufficient faith in the continuity of the gas supply to offer to furnish us with gas for a sum per year equal to that hitherto annually paid for coal until the amount expended by them on piping had been repaid, and afterward at half that sum. It took us about eighteen months to recoup the gas company, and we are now working under the permanent arrangement of one-half the previous cost of fuel on cars at work. Since our success in the use of this new natural fuel at the rail mills, parties still bolder have invested in lines of piping to the city of Pittsburg, fifteen to eighteen miles from the wells. The territory underlain with this natural gas has not yet been clearly defined. At the principal field, that of Murraysville (from which most of the gas is obtained to-day), I found, upon my visit to that interesting region last autumn, that nine wells had been sunk, and were yielding gas in large quantities. One of these was estimated as yielding 30,000,000 cubic feet in 24 hours. This district lies to the northeast of Pittsburg, running southward from it toward the Pennsylvania Railroad. Gas has been found upon a belt averaging about half a mile in width for a distance of between four and five miles. Beyond that again we reach a point where salt water flows into the wells and drowns the gas. Several wells have been bored upon this belt near the Pennsylvania Railroad, and have been found useless from this cause. Geologists tell us that in this region a depression of 600 feet occurs in the strata, but how far the fault extends has not yet been ascertained. Wells will no doubt soon be sunk southward of the Pennsylvania Railroad upon this half-mile belt. Swinging round toward the southwest, and about twenty miles from the city, we reach the gas fields of Washington county. The wells so far struck do not appear to be as strong as those of the Murraysville district, but it is possible that wells equally productive may be found there hereafter. There are now four wells yielding gas in the district, and others are being drilled. Passing still further to the west, we reach another gas territory, from which manufacturing works in Beaver Falls and Rochester, some twenty-eight miles west of Pittsburg, receive their supply. Proceeding with the circle we are drawing in imagination around Pittsburg, we pass from the west to the southwest without finding gas in any considerable quantity, until we reach the Butler gas field, equidistant from Pittsburg on the northwest, with Washington county wells on the southwest. Proceeding now from the Butler field to the Allegheny River, we reach the Tarentum district, still about twenty miles from Pittsburg, which is supplying a considerable portion of the gas used. Drawing thus a circle around Pittsburg, with a radius of fifteen to twenty miles, we find four distinct gas-producing districts. In the city of Pittsburg itself several wells have been bored; but the fault before mentioned seems to extend toward the center of the circle, as salt water has rushed in and rendered these wells wholly unproductive, though gas was found in all of them.
I spent a few days very pleasantly last autumn driving with some friends to the two principal fields, the Murraysville and the Washington county. In the former district the gas rushes with such velocity through a 6-inch pipe, extending perhaps 20 feet above the surface, that it does not ignite within 6 feet of the mouth of the pipe. Looking up into the clear blue sky, you see before you a dancing golden fiend, without visible connection with the earth, swayed by the wind into fantastic shapes, and whirling in every direction. As the gas from the well strikes the center of the flame and passes partly through it, the lower part of the mass curls inward, giving rise to the most beautiful effects gathered into graceful folds at the bottom—a veritable pillar of fire. There is not a particle of smoke from it. The gas from the wells at Washington was allowed to escape through pipes which lay upon the ground. Looking down from the roadside upon the first well we saw in the valley, there appeared to be an immense circus-ring, the verdure having been burnt and the earth baked by the flame. The ring was quite round, as the wind had driven the flame in one direction after another, and the effect of the great golden flame lying prone upon the earth, swaying and swirling with the wind in every direction, was most startling. The great beast Apollyon, minus the smoke, seemed to have come forth from his lair again. The cost of piping is now estimated, at the present extremely low prices, with right of way, at £1,600 sterling per mile, so that the cost of a line to Pittsburg may be said to be about £27,000 sterling. The cost of drilling is about £1,000, and the mode of procedure is as follows: A derrick being first erected, a 6 inch wrought-iron pipe is driven down through the soft earth till rock is reached from 75 to 100 feet. Large drills, weighing from 3,000 to 4,000 lb., are now brought into use; these rise and fall with a stroke of 4 to 5 feet. The fuel to run these drills is conveyed by small pipes from adjoining wells. An 8-inch hole having been bored to a depth of about 500 feet, a 5-5/8 inch wrought-iron pipe is put down to shut off the water. The hole is then continued 6 inches in diameter until gas is struck, when a 4-inch pipe is put down. From forty to sixty days are consumed in sinking the well and striking gas. The largest well known is estimated to yield about 30,000,000 cubic feet of gas in twenty-four hours, but half of this may be considered as the product of a good well. The pressure of gas as it issues from the mouth of the well is nearly or quite 200 lb. per square inch. One of the gauges which I examined showed a pressure of 187 lb. Even at works where we use the gas nine miles from the well, the pressure is 75 lb. per square inch. At one of the wells, where it was desirable to have a supply of pure water, I found a small engine worked by the direct pressure of the gas as it came from the well; and an excellent supply of water was thus obtained from a spring in the valley. Eleven lines of pipe now convey gas from the various wells to the manufacturing establishments in and around Pittsburg. The largest of these for the latter part of the distance is 12 inches in diameter. Several are of 8 inches throughout. The lines originally laid are 6 inches in diameter. Many of the mills have as yet no appliances for using the gas, and much of it is still wasted. It is estimated that the iron and steel mills of the city proper require fuel equal to 166,000 bushels of coal per day; and though it is only two years since gas was first used in Pittsburg, it has already displaced about 40,000 bushels of coal per day in these mills. Sixty odd glass works, which required about 20,000 bushels of coal per day, mostly now use the natural gas. In the work around Pittsburg beyond the city limits, the amount of coal superseded by gas is about equal to that displaced in the city. The estimated number of men whose labor will be dispensed with in Pittsburg when gas is generally used is 5,000. It is only a question of a few months when all the manufacturing carried on in the district will be operated with the new fuel. As will be seen from the analyses appended to this paper, it is a much purer fuel than coal; and this is a quality which has proved of great advantage in the manufacture of steel, glass, and several other products. With the exception of one, and perhaps two concerns, no effort has been made to economize in the use of the new fuel. In our Union Iron Mills we have attached to each puddling furnace a small regenerative appliance, by the aid of which we save a large percentage of fuel. The gas companies will no doubt soon require manufacturers to adopt some such appliance. At present, owing to the fact that there is a large surplus constantly going to waste, they allow the gas to be used to any extent desired. Contracts are now made to supply houses with gas for all purposes at a cost equal to that of the coal bill for the preceding year. In the residences of several of our partners no fuel other than this gas is now used, and everybody who has applied it to domestic purposes is delighted with the change from the smoky and dirty bituminous coal. Some, indeed, go so far as to say that if the gas were three times as costly as the old fuel, they could not be induced to go back to the latter. It is therefore quite within the region of probability that the city, now so black that even Sheffield must be considered clean in comparison, may be so revolutionized as to be the cleanest manufacturing center in the world. A walk through our rolling mills would surprise the members of the Institute. In the steel rail mills for instance, where before would have been seen thirty stokers stripped to the waist, firing boilers which require a supply of about 400 tons of coal in twenty-four hours—ninety firemen in all being employed, each working eight hours—they would now find one man walking around the boiler house, simply watching the water gauges, etc. Not a particle of smoke would be seen. In the iron mills the puddlers have whitewashed the coal bunkers belonging to their furnaces. I need not here say how much pleasure it will afford me to arrange that any fellow members of the Institute who may visit the republic are afforded an opportunity to see for themselves this latest and most interesting development of the fuel question. Good Mother Earth supplies us with all the fuel we can use and more, and only asks us to lead it under our boilers and into our heating and puddling furnaces, and apply the match. During the winter several explosions have occurred in Pittsburg, owing to the escape of gas from pipes improperly laid. The frost having penetrated the earth for several feet and prevented escape upward, the freed gas found its way into the cellars of houses, and, as it is odorless, its presence was not detected. This resulted in several alarming explosions; but the danger is to be remedied before next year. Lower pressure will be carried in the pipes through the city, and escape pipes leading to the surface will be placed along the surface at frequent intervals. In the case of manufacturing establishments, the gas is led into the mills overhead, and, all the pipes being in the open air, no danger of explosion is incurred.
The following extract from the report of a committee, made to the American Society of Mechanical Engineers at a recent meeting, gives an idea of the value of the new fuel: "Natural gas, next to hydrogen, is the most powerful of the gaseous fuels, and, if properly applied, one of the most economical, as very nearly its theoretical heating power can be utilized in evaporating water. Being so free from all deleterious elements, notably sulphur, it makes better iron, steel, and glass than coal fuel. It makes steam more regularly, as there is no opening of doors, and no blank spaces are left on the grate bars to let cold air in, and, when properly arranged, regulates the steam pressure, leaving the man in charge nothing to do but to look after the water, and even that could be accomplished if one cared to trust to such a volatile water-tender. Boilers will last longer, and there will be fewer explosions from unequal expansion and contraction, due from cold draughts of air being let in on hot plates.
"An experiment was made to ascertain the value of gas as a fuel in comparison with coal in generating steam, using a retort or boiler of 42 inches diameter, 10 feet long, with 4 inch tubes. It was first fired with selected Youghiogheny coal, broken to about 4 inch cubes, and the furnace was charged in a manner to obtain the best results possible with the stack that was attached to the boiler. Nine pounds of water evaporated to the pound of coal consumed was the best result obtained. The water was measured by two meters, one in the suction and the other in the discharge. The water was fed into a heater at a temperature of from 60° to 62°; the heater was placed in the flue leading from the boiler to the stack in both gas and coal experiments. In making the calculations, the standard 76 lb. bushel of the Pittsburg district was used. Six hundred and eighty-four pounds of water were evaporated per bushel, which was 60.9 per cent. of the theoretical value of the coal. Where gas was burned under the same boiler, but with a different furnace, and taking 1 lb. of gas to be 2.35 cubic feet, the water evaporated was found to be 20.31 lb., or 83.4 per cent. of the theoretical heat units were utilized. The steam was under the atmospheric pressure, there being a large enough opening to prevent any back pressure, the combustion of both gas and coal was not hurried. It was found that the lower row of tubes could be plugged and the same amount of water could be evaporated with the coal; but with gas, by closing all the tubes—on the end next the stack—except enough to get rid of the products of combustion, when the pressure on the walls of the furnace was three ounces, and the fire forced to its best, it was found that very nearly the same results could be obtained. Hence it was concluded that the most of the work was done on the shell of the boiler."
In no other way can I give the members of the Iron and Steel Institute so much information in regard to this new fuel as by including in this paper a very able communication from the chief chemist at our Edgar Thomson Steel Works, Mr. S.A. Ford, who is to-day the highest authority upon the subject:
"So much has been claimed for natural gas as regards the superiority of its heating properties as compared with coal, that some analyses of this gas, together with calculations showing the comparison between its heating power and that of coal, may be of interest. These calculations are, of course, theoretical in both cases, and it must not be imagined that the total amount of heat, either in a ton of coal or 1,000 cubic feet of natural gas, can ever be fully utilized. In making these calculations I employed as a basis what in my estimation was a gas of an average chemical composition, as I have found that gas from the same well varies continually in its composition. Thus, samples of gas from the same well, but taken on different days, vary in nitrogen from 23 per cent. to nil, carbonic acid from 2 per cent. to nil, oxygen from 4 per cent, to 0.4 per cent., and so with all the component gases. Before giving the theoretical heating power of 1,000 cubic feet of this gas I will note a few analyses. The first four are of gas from the same well; samples taken on the same day that they were analyzed. The two last are from two different wells in the East Liberty district:
ANALYSES OF NATURAL GAS.
--------------------+--------+--------+--------+--------+--------+--------+
| 1 | 2 | 3 | 4 | 5 | 6 |
--------------------+--------+--------+--------+--------+--------+--------+
When tested.........|10-28-84|10-29-84|11-24-84|12-4-84 |10-18-84|10-25-84|
| per ct.| per ct.| per ct.| per ct.| per ct.| per ct.|
Carbonic acid ......| 0.8 | 0.6 | Nil. | 0.4 | Nil. | 0.30|
Carbonic oxide......| 1.0 | 0.8 | .58 | 0.4 | 1.0 | 0.30|
Oxygen... ... ......| 1.1 | 0.8 | .78 | 0.8 | 2.10| 1.20|
Olefiant gas .......| 0.7 | 0.8 | 0.98| 0.6 | 0.80| 0.6 |
Ethylic hydride ....| 3.6 | 5.5 | 7.92| 12.30 | 5.20| 4.8 |
Marsh gas ..........| 72.18| 65.25| 60.70| 49.58 | 57.85| 75.16|
Hydrogen ...........| 20.02| 26.16| 29.03| 35.92 | 9.64| 14.45|
Nitrogen ...........| Nil. | Nil. | Nil. | Nil. | 23.41| 2.89|
Heat units .........|728,746 |698,852 |627,170 |745,813 |592,380 |745,591 |
--------------------+--------+--------+--------+--------+--------+--------+
"We will now show how the natural gas compares with coal, weight for weight, or, in other words, how many cubic feet of natural gas contain as many heat units as a given weight of coal, say a ton. In order to accomplish this end we will be obliged, as I have said before, to assume as a basis for our calculations what I consider a gas of an average chemical composition, viz.:
Per cent.
Carbonic acid............................ 0.60
Carbonic oxide........................... 0.60
Oxygen................................... 0.80
Olefiant gas............................. 1.00
Ethylic hydride.......................... 5.00
Marsh gas............................... 67.00
Hydrogen................................ 22.00
Nitrogen................................. 3.00