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By W. F. M. GOSS

For the purpose of procuring data that could be used in estimating the value of the briquetting process as applied to American fuels, the United States Geological Survey, in cooperation with other interests, began in 1904, at the Louisiana Purchase Exposition, certain experiments involving the production and use of bituminous-coal briquets. It installed at St. Louis, and later at Norfolk, machines for the manufacture of such briquets, and the output of these machines has been tested in locomotive service on several different railroads in comparison with natural fuels. An elaborate and carefully executed series of tests involving the use of natural coals and of briquets made from the same coal, previously crushed, was carried out on a locomotive mounted at the testing plant of the Pennsylvania Railroad Company at Altoona, Pa.; and some preliminary experiments involving the use of briquets in marine service were made in connection with one of the Government's torpedo boats. A description of these tests is presented herewith. The results sustain the following general conelusions: 1. The briquets made on the Government's machines have well withstood exposure to the weather. and have suffered but little deterioration from handling. 2. In all classes of service involved by the experiments, the use of briquets in the place of natural coal appears to have increased the evaporative efficiency of the boilers tested. 3. The smoke produced has in no test been more dense with the briquets than with coal; on the contrary, in most tests the smoke density is said to have been less when briquets were used. 4. The use of briquets increases the facility with which an even fire over the whole area of the grate may be maintained.

Jan 1, 1911

By David White

The purpose of the studies that form the basis of this report was to learn from microscopic examinations of coal how far and in what ways the grouping of coal by types depends on differences in the kinds of plant material from which it was formed and on the condi- tions of its accumulation, or how far the special characters or qualities of coal of any type were determined by the nature and the state of the plant débris from which the coal was formed. The fact is almost universally accepted that beds of coal represent accumulations of vegetal matter in varying stages of preservation, with, as a rule, very small proportions of the remains of animal life. Mingled with the organic substances are different inorganic mineral sediments, which, together with the mineral matter originally con- tained in the plants themselves, constitute the "ash" of coal. The examination of coal shows that the kinds of ingredient plants range all the way from algee and fungi to large trees of various orders, and that these in turn vary in their own groups according to the depth and the nature of the water in which they grew and according to the other conditions of growth, such as moisture, temperature, soil, light, climate, and the competition of individuals. The species or kinds of plants and the numbers of each kind also differ greatly among themselves, not only during any one geologic period because of the changes of environment, but also from one geologic period to another, and it will be remembered that well-developed coal has been found in the strata of every period since the Silurian." Most geologists now agree that coal is transformed peat. True there is wide difference of opinion as to how the transformation has been accomplished and even as to whether coal started as such peat as is now found. Some writers insist that the higher grade coal, in its processes of development, never passed through geologic stages

Jan 1, 1913

By D. T. Randall

Several years ago investigations were begun by the United States Government to determine the most efficient methods of utilizing the coals of the United States. These investigations, which were continued along several different lines, are now being carried on by the Bureau of Mines, in accordance with the provisions of the act creating this bureau . . It was because of the need for more complete information concerning the conditions under which coal could be economically burned in boiler furnaces without objectionable smoke that tests were made at the Government fuel-testing plants at St. Louis, Mo., and Norfolk, Va. In addition to this experimental work a number of commercial plants in the larger cities were inspected to ascertain what were the best methods then in use for abating smoke. The results of these investigations were reported in Bulletins 334 and 373 of the United States Geological Survey. Because of the continued demand for the information contained in these bulletins, the original editions of which are exhausted, they are reprinted by the Bureau of Mines. The text of this bulletin, particularly the information relating to smoke ordinances, was revised in the latter part of 1910 and the early part of 1911 by S. B. Flagg, engineer, who has charge of the steaming tests being conducted by this bureau.

Jan 1, 1912

By D. T. Randall, H. W. Weeks

The burning of coal without smoke is a problem that concerns the Government directly because of the advantages of smokeless combustion both in public buildings and on naval vessels. In addition, smoke abatement is a factor in conserving the fuel resources of the United States. Hence, as part of its general investigation of the best methods of utilizing the coals of this country, the Bureau of Mines, which is in charge of the fuel-testing work formerly carried on by the United States Geological Survey, has made extended tests to determine the conditions necessary for the smokeless combustion of bituminous coal in boiler furnaces. Bulletin 39,a a preliminary report, treats the smoke problem from a theoretical point of view, detailing the steps that are being taken by . municipalities, manufacturers, and citizens to abate smoke, also showing the possibility of a clean city. The present bulletin not only shows that bituminous coals high in volatile matter can be burned without smoke, but also that large plants carrying loads that fluctuate widely, where boilers over banked fires must be put into service quickly and fires forced to the capacity of their units, can be operated without producing smoke that is objectionable. Proper equipment, efficient labor, and intelligent supervision are the necessary factors.

Jan 1, 1912

By Joseph D. Davis, GEORGE S. POPE

This bulletin is the fourth of a series a showing the results of the purchase of coal by the Government under specifications. The work of inspecting and analyzing coal delivered on Government contracts was transferred to the Bureau of Mines by an act of Congress effective July 1, 1910. It had been carried on for several years before that date by the technologic branch of the United States Geological Survey. The purchase of coal on the dealer's statement as to quality or on the reputation of the mine or district producing the coal is gradually being discontinued. At present most coal-purchasing contracts make definite provision regarding the desired heating value of a coal and the composition as shown by analysis. The heating value is usually expressed in British thermal units" and the composition specified is that shown by proximate" analysis. The price to be paid for delivered coal is made to depend on whether the analyses and heating-value tests of samples representing the delivery show the quality to be above or below the quality set forth in the contract. Large coal consumers are beginning to appreciate more and more the importance of the cost of power as a factor in the cost of producing a finished article. The endeavor to increase the efficiency and the economical operation of a power plant calls for an intimate knowledge of the quality of the coal being used. The purchase of coal under specifications insures the purchaser getting what he pays for and the coal being of the quality guaranteed. In addition, the analyses and tests of the delivered coal furnish data whereby the power-plant results can be comprehensively studied and a continuous check maintained on the conditions of operation.

Jan 1, 1912

By George A. Burrell, Frank M. Seibert

The Bureau of Mines, as part of its designated duty of investigating the causes of mine accidents, is conducting at its experiment station in Pittsburgh, Pa., a study of mine gases. Some of the work already done in connection with this study is outlined below. A large number of mine-gas samples have been collected under normal conditions in returns and in splits, and at other points in the ventilating current, also at the face, in the goave or gob, in unventilated places, and wherever the air was still. Samples have also been obtained under abnormal conditions, as after explosions and while mine fires were in progress, or from sealed areas behind stoppings and darns where the air had been stagnant for some time. Chemical changes in the composition of mine atmospheres during mine fires have been studied," and conditions peculiar to certain mines have been investigated. The question of the effect of a change in atmospheric pressure on the escape of gas (methane) in coal mines has been studied. Explosives have been fired in both coal and metal mines, and samples of resulting gases have been collected to ascertain the degree to which these gases vitiate the air. A series of samples in mines where gasoline locomotives were being used have been examined in order to ascertain the degree to which the exhaust gases from such locomotives foul the mine air. Experiments have also been performed in regard to the relative effect of carbon monoxide b upon men and small animals. A preliminary report relating to the inflammable gases in mine air has been published. Full reports of the results of the investigations outlined above will be published as soon as all the necessary data have been gathered. The first part of this report deals with the methods used by the bureau in the collection and examination of the various mine gases; the latter part discusses the bureau's methods of sampling and examining natural gas.

Jan 1, 1913

By R. M. Strong, Lauson Stone

Under the terms of the act establishing the Bureau of Mines, this bureau was authorized to carryon the work of testing and analyzing fuels which had been conducted by the technologic branch of the United States Geological Survey. That work included in its scope an investigation of the availability and uses ofliquid as well as solid fuels, for the original outline of the fuel-testing investigations contemplated, as soon as the funds would be available, a study of the liquid-fuel resources of the country and the making of related researches to determine how these resources could be utilized with greatest efficiency. Owing to the fact that many difficulties were being encountered in the adaptation of the heavier fuel oils for convenient use in internalcombustion engines, it was deemed best to begin the investigation of liquid fuels with tests of gasoline, a fuel in more or less general use. When this investigation began, the extensive introduction, especially by foreign powers, of liquid fuels for small naval craft had awakened much interest. However, the quality of gasoline was reported to vary materially in different countries and the quantity available was said to be rapidly decreasing, with the probability of a prohibitive increase in price. At the same time the claim was made that denatured alcohol, of fairly uniform quality, could be procured in all parts of the world, that unlimited quantities could be readily produced at a low cost, and that this fuel could be used much more efficiently than gasoline in internal-combustion engines. Such statements naturally led to a widespread belief that the time was near at hand when denatured alcohol would entirely displace gasoline as engine fuel. Therefore, the first investigations of the liquid mineral fuels logically embraced a careful series of comparative tests of gasoline and denatured alcohol in engines. A series of over 2,000 such tests was conducted at the Government fuel-testing plants at St. Louis, Mo., and Norfolk, Va., details of which are given in the following pages. The report is published by the Bureau of Mines because of the transfer of the fuel-testing investigations to this bureau.

Jan 1, 1912

By Albert H. Fay, Herbert M. Wilson

The national mine-safety demonstration at Pittsburgh, Pa., was projected and undertaken in the hope that it would aid the increase of safety in the mining industry. That the national mine-safety demonstration was warranted and has served a useful purpose was evidenced by the attendance, not only at the public demonstration in Forbes Field, but also at the more special exhibit of the work of the Bureau of Mines at the arsenal grounds and at the experimsntal. mine. Nearly 2,000 persons witnessed the demonstrations and exhibits of the Bureau of Mines at the arsenal grounds on the morning of October 30, 1911. The spectators were all mine operators, miners, or persons interested in mining, and represented operations in all parts of the United States. Nearly 1,200 of these persons visited the bureau's experimental mine at Bruceton to witness ~th~explosion of coal dust. Had the weather, which was exceptionally inclement, been more favorable, there would doubtless have been a much larger attendance. At the public demonstration in Forbes Field, which· was witnessed by President Taft, from 12,000 to 15,000 persons, chiefly mining men, were present and attested their interest and enthusiasm in the minesafety exhibits by remaining throughout the proceedings, regardless of the rain which fell all the morning .. Sincethis demonstration, the organization of first-aid corps and of rescue corps has been undertaken at mines where there had previously been no such organizations. The bureau has received letters of commendation attesting the value of the demonstration in drawing· attention to the dangers and to possible means of greater safety in mining. Many of these letters have urged that the results of the demonstration be published for the guidance and instruction of those who were present. In response to these reauests the following account of the mine- BlIIeLY demonstration lias been prepared. IIi its preparation various division and section chiefs of the Bureau of Mines have cooperated. The authors acknowledge the assistance they have received from those section chiefs and other members of the bureau who contributed detailed descriptions of apparatus exhibited at the demonstration or of investigations represented.

Jan 1, 1912

By N. H. Darton

In mining coal in the anthracite region of Pennsylvania the general custom has been to leave a large percentage of the coal in place as pillars to support the roof. Evidently any practice that involves partial waste of an important mineral resource is bound to be discarded. It is well recognized that one method of obviating probable waste is to fill the workings with cheap or worthless materials, a process extensively employed in the anthracite and some European mines. At present many of the collieries in the anthracite region of Pennsylvania are utilizing refuse from the old culm banks, which formerly were prominent features in the landscape, and are flushing the fine waste underground so that pillars may be reduced in size or removed. As a result the banks are now disappearing and soon will be gone. The fine culm from the breakers and rock from the mines will continue to be available, but the volume of these materials is insufficient to replace any considerable proportion of the coal removed. The next stage of progress suggested is the use of sand. Fortunately there are available large deposits of this material, much of which can be handled by dredges and pumps. This report is issued by the Bureau of Mines in the interest of safer and more efficient mining methods. I ts purpose is to describe the sand deposits in the northern anthracite coal field in Luzerne and Lackawanna Counties, Pa, Much of the information available is presented in the map, Plate I. Field studies, mostly preliminary, were made in the summer of 1911 to determine the distribution, amount, and character of the larger deposits. It was not thought desirable to make a detailed examination of the region because when the coal companies decide to utilize the sand their engineers will make precise surveys and drill test holes. In preparing the map the various coal companies were consulted; they contributed a large number of facts, especially as to the deposits in the buried valley of the Susquehanna between Pittston and Nan- ticoke, where nearly 1,000 test holes have been bored. The results of these borings were placed at the author's disposal, and have been utilized in drawing the boundaries given in the wide valley area and its extensions up Lackawanna River and NewportCreek. Wyoming Valley contains deposits of sand that are 100 feet thick over a wide area, 200 feet thick in places, and over 300 feet thick in the deep old channel south of Plymouth.

Jan 1, 1913

By H. H. Clark

The term "explosion-proof," as applied by the Bureau of Mines to an electric motor, refers to a motor inclosed by a casing so constructed that an explosion of a mixture of mine gas (methane) and air within the casing will not ignite a mixture of the same gas surrounding the motor. There are two classes of motors so constructed: First, a totally inclosed class built strong enough to withstand high internal pressures and so designed that the efficiency of all inclosing covers can be satisfactorily maintained; second, a class provided with relief openings or valves designed to relieve the pressure of an explosion within the motor casing and to cool any products of combustion dis- charged through the valves. A satisfactory motor of the first class is much more expensive to build than an equally safe motor of the second class. For this rea- son, attempts to make motors explosion-proof have been confined chiefly to motors of the second class.

Jan 1, 1912

By Charles L. Parsons

During the past year, in producing 500,000,000 tons of coal we wasted or left underground, in such condition that it probably will not be recovered in the future, 250,000,000 tons of coal; we turned loose into the atmosphere a quantity of natural gas larger than the total output of artificial gas during the same period in all the towns and cities of the United States; we also wasted or lost in the mining, preparation, and treatment of other important metalliferous and non- metalliferous minerals from 10 to 50 per cent of the year's produc- tion of such minerals. These losses serve to indicate the importance of inquiries and investigations by the Federal Government for the purpose of lessening the waste of essential resources-investigations on the same general lines as those looking to a reduction in the loss of life in the mining operations of the country and the far more exten- sive investigations looking to the more efficient production and use of agricultural products, both of which are being conducted by the Federal Government. In a consideration of the possible activities of the individual, the State, and the Federal Government in behalf of a less wasteful use of our mineral resources certain facts and principles should be kept clearly in mind, namely: That the present generation has the power, and it will exercise the right, to use as much of the country's resources as it actually needs; there can and there will be no such thing as stinting the present gen- eration by bottling up resources for the use of the future. That the Nation's needs are not likely to be curtailed; these needs will increase with the extent and diversity of the Nation's industries, and they will increase more rapidly than population increases, for the reason that the per capita consumption of mineral products is rapidly increasing; and That the men of this generation will not mine, extract, or use these resources at continuous financial loss to themselves in order that some- thing may be left for the use of future generations; there can be no such thing as a mineral industry without profits.

Jan 1, 1912

By Clarence Hall, Spencer P. Howell

This bulletin deals with the characteristic features of the principal explosives used in mining and engineering operations, and espe- cially with the tests that show the suitability of different classes of explosives for different kinds of work. The Bureau of Mines pub- lishes the report as one of a series dealing with tests of explosives and methods of reducing the risks involved in the use of explosives in mining operations. The application of explosives to engineering and mining opera- tions has increased rapidly in recent years. According to a pre- liminary report issued by the Bureau of the Census, 469,000,000 pounds of explosives was manufactured in this country during the year 1909, and the greater part of this production was used for industrial purposes. In large engineering projects and in mining operations requiring the use of explosives the selection of a suitable explosive from the many varieties offered for sale is of fundamental importance. Vari- ous considerations are involved in the selection of an explosive of proper class for the blasting to be done. Many explosives suitable for quarry work are unsuitable for use in deep mines or in close workings. In metal mining and in driving tunnels the character of the gases evolved by the explosive on detonation is an important consideration. An explosive for use in gaseous or dusty coal mines must be formulated and compounded so that its flame temperature and the height and duration of its flame are reduced enough to per- mit its being used with comparative safety. In wet workings or in submarine blasting explosives impervious to moisture are requisite. In extremely cold climates explosives that do not require thawing are desirable, provided they are equally good in other respects. An essential requirement of all explosives, especially of those for use in tropical countries, is that they shall remain stable without change in chemical or physical characteristics.

Jan 1, 1913

By Samuel B. Flagg

The Bureau of Mines is endeavoring to ascertain how mineral fuels in which the Government has a direct interest, by ownership or use, can be utilized with highest efficiency. For this reason the bureau has been, and is, carrying on investigations to ascertain the condi- tions of furnace construction and management that are necessary to insure the smokeless combustion of the different coals that are found in public lands or are purchased for Government ships and power plants. Another reason for the bureau undertaking these investigations is the need of better furnace management and a more careful selec- tion of fuel at many Government plants. There are Federal build- ings in hundreds of cities. The coals available at many of these cities differ greatly in quality, and the furnaces in some of the Fed- eral buildings were not designed for efficient utilization of the cheap- est available coal. Hence, some of the boiler plants smoke badly unless fed with low-volatile coal and have caused repeated com- plaints not only from neighboring property owners who have suffered damage, but from persons endeavoring to create a civic pride in clear air. In the course of its fuel investigations the bureau has noted the conditions governing fuel consumption in different cities and has studied the attempts made by these cities to abate smoke through the passage of ordinances imposing penalties on smoky stacks. Some results of that study are presented in this report. The most im- portant conclusion reached is that smoke abatement by ordinance can not hope to succeed unless supported by public sentiment and that a smoke ordinance should look to future prevention rather than to immediate prohibition. In other words, strict control of furnace construction offers much greater hope for smoke abatement than desultory imposition of severe penalties on the escape of "dense" or "black" smoke.

Jan 1, 1912

By E. J. HOFFMAN, L. A. SCHOLL, J. c. W. FRAZER

The danger from coal dust in mines has been thoroughly demon- strated by experiment, and consequently the study of the inflam- mability of coal dust suspended in air, that is, the readiness with which a cloud of coal dust inflames, is of decided importance to those engaged in coal mining. Much knowledge has been gained from the work done in the large galleries constructed at official and semiofficial stations in this country and abroad, but the study of the coal-dust problem in these galleries requires so much time and is so costly that there is need of a reliable laboratory method for obtaining a classi- fication of the great variety of dusts that occur in mines. The investigation described in this paper was an attempt to devise such a method. It was a preliminary investigation, and work in the same direction is being continued by the Bureau of Mines. As Mr. Frazer has severed his connection with the bureau, it is deemed advisable to publish the results of his study substantially as he prepared them, with little attempt to draw conclusions or to show the bearing of the results on other studies now in progress. The results of these studies and a full discussion of the significance of the laboratory investiga- tions will be published in future reports of the Bureau of Mines. The reader should remember that any laboratory method, since it involves conditions that differ so greatly from those of actual mining, should be thoroughly tested, and the results obtained by it should be confirmed by experiments conducted on a scale simulating mining conditions before final conclusions are drawn. The need of a laboratory method has long been felt, and several investigators have devised apparatus and methods. The work done by Vital, Holtzwart and Von Meyer, Bedson and Widdas, Le Chate- lier, and that of the British Coal Dust Commission is of great interest in this connection. Bureau of Mines Bulletin 20 contains a sum-

Jan 1, 1913

By Walter O. Snelling, C. G. Storm

Although descriptions of the methods of analysis of explosives are to be found in many books on explosives, and in works on engineer- ing chemistry or chemical analysis, most of these descriptions are incomplete and lacking in details. The methods of analysis employed in the laboratories of most explosives factories are frequently treated as trade secrets, and very little information is published from such laboratories. This bulletin outlines the methods of analysis that are used by the Bureau of Mines in the examination of certain classes of explo- sives. The present form of most of these methods has been worked out in the bureau's explosives laboratory. The methods employed by Prof. C. E. Munroe were taken as a basis, and were elaborated to meet the demands incident to the treatment of complicated mix- tures and to the development of the explosives art. A subsequent bulletin will discuss the methods of analysis of "permissible" explosives, many of the latter being of decidedly complicated char- acter and requiring special treatment. This bulletin presents the methods of analysis of "ordinary" dynamite, and the ammonia, gelatin, low-freezing, and granular dynamites, and the common grades of black gunpowder and black blasting powder. The bulletin is published by the bureau for the information of all persons inter- ested in explosives and their safe and efficient use in mining work. As the term "ordinary" dynamite, though much used, has no conventional meaning, and may be used to cover a wide variety of compositions of matter, it may be noted that the standard dynamite used at the Pittsburgh testing station is a good example of the "ordinary" dynamite known in this country. This testing station dynamite has the following composition:

Jan 1, 1913

By L. C. IlsLey, H. H. Clark

As part of its investigations of the causes of mine accidents and of the safest and most efficient methods of handling electricity underground, the Bureau of Mines undertook a study of the ignition of mine gases by the filaments of electric incandescent lamps. This bulletin describes the investigation in detail and gives a complete record of the results obtained.

Jan 1, 1913

By A. S. Watts

Throughout the Appalachian Mountains there are dikes of coarse granite or pegmatite, which were intruded into other rocks. These pegmatite dikes contain feldspar, quartz, white mica (muscovite), black mica (biotite), and other minerals, such as beryl, garnet, and tourmaline. The investigation here reported has to do only with the dikes of the southern Appalachian region, in which the abundance of each mineral is as in the order given above. The pegmatites of this region are in every stage of alteration from those in which the feldspar is fresh to those in which the feldspar has decomposed to kaolin. The muscovite (white mica) shows no evidence of alteration, although most of the other associated minerals show traces of disintegration where the feldspar is completely kao- linized. At many places mining for mica has been done in dikes in which the feldspar is completely kaolinized, though the only evi- dences of disintegration in the mica are clay stains which are some- times noted between the outside lamina. Mining in these pegmatite dikes antedates history, traces of prehis- toric workings and some crude mining implements of stone having been unearthed by recent operations. The prehistoric mining is generally supposed to have been for mica, although investigations fail to show that the aborigines put the mica obtained to any par- ticular use except for ornaments, a few mica ornaments having been found in mounds in this region. The search for kaolin or semikaolinized feldspar is a plausible ex- planation of these prehistoric workings; all of them were in pegmatite that is more or less altered, and seemingly stopped only when the pegmatite became too hard to permit working with crude stone im- plements. The dumps do not represent the amount of material that one would expect, from their extent, the workings to have produced. The kaolin obtained was doubtless conveyed to the coast and sold to English traders for use in the manufacture of some of the early

Jan 1, 1913

By A. W. BELDEN

Among the investigations that the Bureau of Mines is conducting witha view to increasing efficiency in the utilization of fuels belonging to or for the use of the Government is an investigation of the processesthat take place in a foundry cupola during a melt. Some observations on the results of cupola tests of cokes at the Government fuel-testing plant in St. Louis, Mo., the coke being fromcoal from many coal fields of the United States, have been stated in a previous bulletin.s Especial attention was given to the meltinglosses that resulted from the use of different grades of coke, light and porous or heavy and dense. These losses amounted in one instance to 52.5 per cent of the iron charged and showed, in convincing manner, the need of exact information in regard to conditions in the fuelbed of the cupola.b Melting losses of iron have been fully appreciated but little under-- stood. The fact that these losses were possible with either light or heavy coke led to the belief that by using small charges 80 placed that. melting would take place in that zone of the cupola where the highest heat and the smallest percentage of oxygen prevailed and by confiningall melting to this zone these losses would be eliminated and the economical use of practically any coke produced for metallurgical purposes would become possible. This widening of the field from whichcoke might be drawn for foundry purposes would serve to place the foundryman in an independent position as regards his source of supply, and would tend to conserve the better grades of coking coals, which are being rapidly exhausted, by making the poorer grades available for mixing with them. In order to investigate conditions within a cupola, the Bureau of Mines as a first step decided to install a commercial cupola, to sample the gases during their travel from the tuy~res upward, and to determine the temperature of the fuel bed.

Jan 1, 1913

By R. H. Fernald

In investigating general problems that relate to the fuel resources of this country, and in testing fuels belonging to or for the use of the Government, the Bureau of Mines has given considerable attention to the efficiency and economic value of producer-gas power plants. Government inquiries during the past eight years not only have shown a very low fuel consumption per horsepower-hour for these plants but have demonstrated conclusively the possibility of utilizing commer- cially low grades of bituminous coal, lignite, and peat in plants prop- erly designed for the use of these fuels. The anthracite plant has been recognized as a commercial possibility for several years, although the cost of the fuel used has in general restricted these plants to com- paratively small units. The commercial development of the producer-gas power plant in the United States has been largely within the past six or eight years. In 1909 the United States Geological Survey published in a bulletin entitled "Recent Development of the Producer-Gas Power Plant in the United States" a list of producer-gas power-plant installations. The data presented in that bulletin showed a strong development in this field and led to much conjecture as to the future of this type of power. Owing to the extensive introduction of the steam turbine, however, many persons predicted the almost immediate doom of the producer-gas plant. In addition to the inroads made by this formida- ble rival, the interest of the gas-engine enthusiasts became centered to such an extent in the oil engine that the gas producer was relegated to second place by many and absolutely abandoned by some. During the past three years the belief of many who were formerly firm be- lievers in the gas producer has been that this type of power has reached its height of development in this country and that from a commercial standpoint it can no longer be regarded as a complete success. This feeling of commercial decadence has become so general

Jan 1, 1913

By W. L. EGY, GEORGES. RICE, L. M. JONES, J. K. CLEMENT

This report has been prepared, not only for the purpose of recording the results of the first series of coal-dust tests conducted in the experimental mine of the Bureau of Mines, but also to place before the mining public a description of the mine and an account of the objects sought in its establishment. Soon after the organization of the technologic branch of the United States Geological Survey, J. A. Holmes, then chief of the branch, concluded that for the solution of various problems relating to the causes and prevention of mine explosions it would be best to carry on large-scale tests in a mine rather than in a surface gallery. The idea of utilizing the underground passage of a mine for making explosion experiments did not at' first meet with general approval among investigators in this country or abroad. Many thought a mine passage was not a proper place in which scientific tests could be conducted, as great difficulty in controlling conditions was expected. However, after all arguments for and against such an investigation had been carefully considered, plans for opening an experimental mine were definitely adopted by the Bureau of Mines in 1910, and an allotment of funds was made to carry out the project. The first endeavor was to find an existing mine suitable for the purpose, but the mines offered by owners were either worked out, were wet, had poor roofs, or presented complications of various kinds, so that it was finally decided to open a mine if a site could be obtained having natural conditions that would fill the various requirements. A most desirable location was found on property of the Pittsburgh Coal Co., near Bruceton, Pa. The president of this company, Mr. W. K. Field, the general manager, Mr. G. W. Schluederberg, and the chief engineer, Mr. E. J. Taylor, rendered every possible service in

Jan 1, 1913