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By McHenry Mosier

This paper describing mining practice at Morenci, Ariz., is one of a series of articles on mining method, and practice in the various mining districts in the United States. At present (1929) practically all the mineral production in the Morenci district is from the Humboldt mine of the Morenci Branch, Phelps Dodge Corporation. The mining method used is adapted to the type of ore body being exploited; it has been developed by adopting methods used elsewhere and making necessary changes to fit local conditions. Improvements in current practices are still being made.

Jan 1, 1929

By Greenwald, H. P

The Bureau of Mines has been conducting experiments on the explosibility of coal-dust in the experimental mine for more than 17 years. The results have been published from time to time3, and a forthcoming technical paper4 will summarize the results and discuss them in some detail. The present paper will be limited to a statement of the more important facts that these researches have discovered.

Apr 1, 1929

By J. W. Paul

This report is one of a series of papers on coal mining methods and costs which are being prepared through the sponsorship of the U. S. Bureau of Mines for the purpose of bringing to the industry a knowledge of methods as they are used at the present time, and data on certain features which govern costs, safety, and conservation. The methods employed are, influenced by local conditions with respect to the character and dip of the coal, the nature of the, roof and the thickness of the overburden, and the means employed for roof support and its control.

Jan 1, 1929

By Paul M. Tyler

Graphite occurs in many places in the United States, but previous to 1914 the domestic production amounted to only 15 to 20 per cent of the natural graphite consumed in this country. Including artificial, graphite, the proportion was about 25 per cent. During the World War the production of both natural and artificial graphite increased until, in 1918 it, contributed more than one-half of the available supply, and since 1919 the proportion has not fallen below 40 per cent. Except during the war period, however, this apparently increasing independence has not been due to any large increase in production from domestic mines. It simply reflects a larger output of artificial graphite and reduced imports of Ceylon lung and chip, grades which have never been produced in substantial quantity in the United States. DOMESTIC DEPOSITS3 American graphite deposits, though numerous and often large, are characteristically low-grade. They constitute an abundant source of potential supply, but in normal times they have proved relatively costly to work, and even at the same price the various products have never been able wholly to displace certain imported qualities, notably crucible grades from Ceylon and pencil graphite from Mexico.

Jan 1, 1929

By Paul M. Tyler

The outstanding trend in the graphite market is the fast-growing demand for cheaper qualities of graphite and the declining consumption of the more expensive varieties. The manufacture of graphite, crucibles for melting metals was one of the earliest applications of the-mineral and for many years constituted by far the leading source of demand. In later, years, however; and more especially since the Great War, the increasing demand for high-grade steel ingots and castings instead of enlarging crucible sales has permanently curtailed the domestic demand for crucibles because it has hastened the introduction of electric, oil or gas fired furnaces to replace the older types requiring pots to hold the metal during melting. While there has been a substantial increase in the use of graphite for miscellaneous refractories the total consumption for such purposes is too small to offset the shrinkage in demand for crucible making, and though it consumes the better and hence more expensive grades of crystalline flake graphite, it does not call so insistently for the still costlier Ceylon grades.

Jan 1, 1929

By Paul M. Tyler

Graphite is an essential war mineral and for that reason has received much attention from the standpoint of national defense. During the World War the situation with respect to graphite supplies, though it never became acute, caused considerable concern. Even in peace time, however, graphite has aroused more interest than the actual size of the industry seems to warrant. Despite this wide interest the facts of the industry do not seem to be generally known. Often there has been an almost total disregard of the essential' economic and technical problems involved. Long ago Bastin3 made the following statement; in a Government' report: "To-day there are more abandoned mines and mills in the United States than the number in operation * * *. In the number of times' some of these properties have changed hands in the course of a few years, there is a record of misrepresentation and disappointment that can hardly be equaled in any other branch of mining; and many properties have been notoriously associated with stock manipulation of doubtful character." According to one authority fully 600 graphite mines have failed in the United States, and the record shows that of all these properties scarcely a score have ever succeeded in operating for as much as a year or two. More than 40 mines have been worked at various times in the State of New York alone and at least that many in Alabama. Throughout the country, in fact, there are scarcely a dozen States in which efforts have not been made at some time to exploit graphite deposits. At the present time the list of mines that can be classed as at all active is reduced to less than ten. Failures inevitably occur in all lands of mining, but the disheartening feature of the record of graphite mining in this country is that so few ventures have even paid back the money put into them and. that none has been a conspicuous success.

Jan 1, 1929

By E. D. Eastman

The basic character of the free energy r data relating to water and the oxides of carbon makes it desirable that the most representative values that can be obtained should be constantly available. The calculations of Lewis and Randall3 retain much of their of original value, but appear to require some modification in the light of more recent work. This paper has been written to incorporate the newer information and to present some estimate of the reliability of the resulting figures. The data upon which the calculations are mainly based are, for these substances, the equilibrium constants of the various reactions involved. The original work relating to these equilibria has, been reviewed and, where possible, weighted to correspond with its probable reliability. The differences in the results of the present from the earlier calculations are partly the consequence of this appraisal and partly of the inclusion of more extensive data, as will be indicated in detail in the succeeding sections.

Jan 1, 1929

By C. W. Owings

When explosions have occurred in mines where rock dust has been used to some extent, generally to a very limited extent, the press has immediately characterized those mines as "rock-dusted." To persons familiar with the method of rock-dusting, it is apparent that if rock-dusting is done properly, if all mine surfaces are rock-dusted to within at least 40 feet of the faces of rooms and entries, and if the incombustible content of the dust is more than 65 per cent, there is little likelihood that an explosion of coal-dust will occur. The report that an explosion has occurred in a "rock-dusted" mine immediately conveys to the mind of the alert safety advocate the information that the mine is inadequately rock-dusted or that either dust sampling of the rock-dusted surfaces has not been done or, if done, the mine has not been redusted with sufficient promptness. Rules for Collection of Samples Collection of dust samples is by no means intricate, but a few simple rules must be kept in mind if the results are to be dependable. A sample must represent the true average conditions of the dust in the section or zone in which it is taken, and therefore 'the point at which the sample is to be collected must be selected with care. During an explosion much if not all of the dust on the ribs, roof, timber, and road in the affected region is blown into the air; the sample, therefore, should contain all loose dust and material on: the surfaces to a depth of about 1 inch, if that amount is present. If there is considerable sand locally along the track, care must be taken not to include enough of this material to vitiate the sale and distort the results; however, if the sand is distributed throughout the region being sampled it should be included. Dust should not be collected from recesses in the ribs, such as hitches cut for timber, as the character of the dust in such places is often different from that on the ribs proper. Samples should not be collected at points where the dusting machine has been loaded or at a point where the machine has stopped and discharged for a longer period than at other points on the entry or in the rooms. In short, the sample must represent AVERAGE CONDITIONS, and if there is any doubt as to the character of the dust it is far better to have too much combustible matter than too much incombustible matter in the sample, as it is best to err on the side of safety if it is necessary to err.

Jan 1, 1929

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Colombia has been prepared from the best available information in Washington, but is released subject to correction and amplification; if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State. SYNOPSIS OF LAW Minerals in Colombia belong to the owner of the soil unless otherwise provided in the law. The following lands and deposits, however, are described as fiscal property of the State: Class 1. The public lands, mines, and salines which belong to the individual States (now Departments) prier to the adoption of the present constitution (1886).

Jan 1, 1929

The content of the book covers: (1) The theory of the Eötvös torsion balance; derivation of the working formulas; description of the instrument; method of observation; relation of the magnitudes observed to the lines of force and the level surfaces of gravity; corrections or normal effects, near and distance terrane; subterranean effects; effects due to certain mathematical bodies. (2) Notes on the practical employment of the Eötvös torsion balance; initial testing of the instrument and of accessories; hints on planning the survey; work at the station site; office computation and plotting of results; the interpretation of the results: (3) A description of the instrument and instructions for its manipulation. This book was the best discussion in English on the theory and use of the Eötvös torsion balance and is surpassed only by a later paper by the same authors that covers much of the same ground. The book is suitable for a textbook for beginners, and advanced students will find it of use. It should be available as a reference book in all geological libraries and in all torsion balance department offices.

Jan 1, 1929

By L. C. IlsLey

Cooperation between the United States Bureau of Mines and the Safety in Mines Research Board of Great Britain, continuous since 1924, has made possible this and other papers on safety subjects. Grateful acknowledgment is made to representatives of the Safety in Mines Research Board of the Mines Department for their assistance in arranging visits to several mine safety stations, and to F. R. Wynne, Deputy Chief Inspector of Mines, Great Britain, for arranging visits to mines in Great Britain, Belgium, Germany, and France. During the summer of 1927 the writer had the privilege of visiting the mine safety testing stations in Great Britain, Belgium, Germany, and France, in the order named. All of these countries have large coal mines, many of which are rated as gassy. Therefore, when installation of electrical equipment is contemplated, each of these countries is confronted with the same safety problem as is the United States - the development of electrical equipment that will not ignite gassy mine atmospheres which might, through neglect or accident surround the equipment. The means used by these countries in safeguarding gassy mines should therefore be of general interest to safety engineers of American coal mines, and it is proposed to give a brief survey for each of the four countries mentioned. This paper presents the second of these surveys, which covers conditions in Belgium.

Jan 1, 1929

By D. Harrington

Correct ventilation of underground workings whether in coal or in metal mines consists in establishing such control of air currents that the miners may work in safety, with maximum comfort and efficiency, and without impairment of health; also in controlling the air flow so that the mine workings may at ordinary times be kept reasonably free of harmful gases or dusts, and so that in time of emergency, as when a fire or an explosion occurs, there may with minimum delay be maintained as much or as little air flow as is desired throughout the mine in its entirety or in certain parts of the mine. Control of air flow is the essential point of any mine ventilating system, and is obtained only by the installation of mechanically operated fans, and other ventilating devices such as doors; overcasts, regulators, etc. Every mine, large or small, coal or metal, should from the outset be equipped with a fan. Much has been written about natural ventilation, and many claims have been made that in specific mines or parts of mines there is sufficient natural air flow. As a matter of fact, there are actually very few if any mines, coal or metal, where natural ventilation creates atmospheres anything like adequately safe or healthful for underground workers even at ordinary times or under ordinary. conditions; and at the time of a fire or an explosion mines depending upon natural ventilation are practically helpless, and are decidedly dangerous for the unfortunates forced to be in them either at the time of the disaster or afterwards when trying to handle conditions arising from the emergency.

Jan 1, 1929

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Bolivia has been prepared from the best available information in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State. SYNOPSIS OF LAW All useful substances of the mineral Kingdom belong originally to the State. The soil and subsoil are regarded as two distinct parts, the latter extending indefinitely in depth (Art. 2). The subsoil is under the dominion of the State, which may either abandon it to common use, grant it gratuitously to the owner of the soil, or alienate it, in return for an annual fee, to any individual or association that applies for it. (Art. 1-3.)

Jan 1, 1929

By L. C. IlsLey

Cooperation between the United States Bureau of Mines and the Safety in Mines Research Board of Great Britain, continuous since 1924, has made possible this and other papers on safety subjects. Grateful acknowledgment is made to representatives of the Board for their assistance in arranging visits to several mine safety stations, and to F. R. Wynne, Deputy Chief Inspector of Mines, for arranging visits to mines in Great Britain and other countries in Europe. During the summer of 1927 the writer had the privilege of visiting the mine safety testing stations in great Britain, Belgium, Germany, and France, in the order named. All of these countries have large coal mines, many of which are rated as gassy. Therefore, when the installation of electrical equipment is contemplated, each of these countries is confronted with the same safety problem as is the United States - the development of electrical equipment that will not ignite gassy atmospheres which through neglect or accident might surround the equipment. The means employed by these countries in safeguarding gassy mines should therefore be of general interest to safety engineers in American coal mines, and it is proposed to give a brief survey for each of the four countries mentioned. The third of these surveys covers conditions in Germany.

Jan 1, 1929

By George L. Richert

The Minas de Matahambre is situated on the north coast of Cuba, in the Province of Pinar del Rio, approximately 150 miles west of Havana. This nine is the only producer of copper in Cuba, and has been worked for the past 15 years. In 1921 the property was affiliated with The American Metal Co., Ltd., and has been worked by them since that time under the direction of Mr. D. D. Homer, General Manager. Extracts from P. D. Wilson's ?Preliminary report on the geology at Minas de Matahambre? have been freely used in this report.

Jan 1, 1929

By Oliver Bowels

Many inquiries are received by the United States Bureau of Mines for the names of elementary books on geology, mineralogy, methods of identifying minerals, prospecting, and similar subjects. In response to this demand the following brief bibliography has been prepared. As many of the inquiries are received from those who have limited technical knowledge of the subjects involved, the bibliography includes the simpler texts which present the subjects in nontechnical language. Other texts contain glossaries which define the technical terms used. A short note following the title indicates the character of each book, the number of pages, and the price. Thus, elementary mineralogists or geologists, prospectors, mineral collectors, nature students, or travellers may select the texts that best suit their requirements and their capabilities. To supply the needs of more advanced students, quite a number of the standard texts used in schools and colleges are included in a second group. A short list of books on economic geology and mineralogy has also been added.

Jan 1, 1929

By C. H. McNaughton

The Tennessee Copper Co. operated two mines in the Ducktown district during 1928. The Burra Burra mine is much the larger operation and is the chief source of the ore smelted and treated in the, company's smelter and acid plant rat Copperhill, 4.5 miles from Ducktown. This mine operates steadily and furnishes a regular output of about 40,000 tons per month. The Eureka mine is operated irregularly and produces a much smaller tonnage of high-sulphur ore the rate of output depending upon the demand for sulphur. During 1928 about 60 per cent of the combined output of these mines was shipped directly to the smelter, and the balance was concentrated before shipment in the flotation plant located near the mines. ACKNOWLEDGMENTS The author acknowledges the assistance of Lamar Weaver, Assistant mine superintendent of the Tennessee Copper Co, and of C. F. Jackson, mining engineer, U. S. Bureau of Mines, in the, preparation of this paper, U. S. Geological Survey Professional-Paper 139, by W. H. Emmons and F. B. Laney, has been drawn upon for information contained 'in the paragraphs on history and geology.

Jan 1, 1929

By J. W. Paul

This circular is one of a series of reports on coal mining methods and cost s which are being prepared by the U. S. Bureau of Mines for the purpose of making available to those interested in the industry a knowledge of the mining methods employed in mines where mechanical and hand loading is practiced and the cost data on the several operations pertaining to the removal of coal from the working faces and its transportation to the tipple for loading into railroad cars. The methods employed are influenced by the natural local conditions with respect to the thickness and character of the coal beds and the overlying strata, the means employed for roof support and its control, and the disadvantages incident to the development of mines in thin coal beds.

Jan 1, 1929

By J. W. Paul

This report is the second of a series of papers on coal-mining methods and costs which are being prepared by the U. S. Bureau of Mines for the purpose of placing before those interested in the industry a knowledge of the mining methods employed in this particular mine, and cost data on the several operations pertaining to removing the coal from the face into the railroad cars at the tipple with economy and safety. The methods employed are influenced by the natural local conditions, with respect to the thickness of overburden, frequency of local "wants," and the means employed for roof support, and its control

Jan 1, 1929

By W. D. Ryan

The organic act passed by Congress in 1910 instituting the Bureau of Mines provided that the director of the bureau should promulgate such investigations as might be necessary to determine the causes of mine accidents and the best methods of preventing them. With the object of accident prevention in view, Director Joseph A. Holmes, and others who were pioneers in the bureau, conceived the Plan of having first-aid and mine-rescue training as one of the major activities of the Bureau. Out of this plan grew the first-aid and mine-rescue contests, which have been featured as an incentive for men to take courses in this type of mine safety training. The first appropriation for mine-accident investigations became available on July 1, 1908, under the jurisdiction of the U. S. Geological Survey, with Dr. J. A. Holmes in active charge. During 1908 there had been some first-aid training in the Pennsylvania anthracite field and a start made in Illinois, although there appears to be no exact information as to when or where first-aid training in the mining industry first became a reality, it is generally conceded that the St. John's ambulance corps of Scotland was one of the first - if not the first - to make the work effective. In 1911, to celebrate the establishment of the Bureau of Mines and the formal opening of the Pittsburgh, Pa., station, a first-aid and mine-rescue demonstration was conducted on Forbes Field, Pittsburgh. President William Howard Taft and many other men notable in public life were 2 resent. This was the first general national contest of the kind held it the United States; and since then there have been a number of nation-wide first-aid and mine rescue contests, as well as some which have been international in scope. There are over one hundred first-aid and mine-rescue contests of various kinds held annually in connection with mining and the allied industries.

Jan 1, 1929