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By R. A. L. Black

Between March and June 1962, the privilege of holding a Carnegie Corporation Fellowship enabled R. A. L. Black to travel extensively in the northeastern and western U.S. and in Canada, seeing mining schools, mining research establishments and a cross-section of the American and Canadian mining industry. Visits were paid to 12 university mining schools, 7 research establishments and 19 mining operations. The author had previously spent two months in Britain in a similar manner and eventually returned to his home in South Africa after a short period studying mining problem in Australia. Thus, although the following remarks are mainly concerned with the educational problems of mining in North America, a comparison of impressions of American and Canadian conditions could be made with impressions gained from first-hand experience of other mining centers in the English-speaking world. The conclusion was reached that the problems and conditions of mining, research and mining education are very similar in all areas visited.

Jan 4, 1963

Meeting, June 26, 1913).-On the petition of 29 members residing in and near San Francisco, Cal., the San Francisco Local Section was established. The territory of the St. Louis Local Section was established to include the following States and parts thereof: All the State of Missouri ; That part of the State of Illinois south of and including the city of Urbana ; That part of the State of Indiana south of and including the city of Indianapolis ; That. part of the State of Kentucky west of and including the city of Frankfort ; That part Of the State of Tennessee west of and including the city of Nashville That part of the State of Arkansas north of and including the city of Little Rock.

Jan 7, 1913

By Paul M. Tyler

ROUGHLY one-half the value of mineral products at mines or quarries must be spent for wages. In view of the steady increase in hourly wages that continued for several decades prior to the onslaught of the recent depression, it is perhaps surprising to discover that labor's share of the gross proceeds of the mining and quarrying industries of the United States declined to 46.8 per cent in 1929, compared with 52.2 per cent in 1919 and 53.2 per cent in 1909. The actual percentages vary in different branches of the industry and in different localities but the downward trend is unmistakable. For the period 1909 to 1919 it was quite marked in every industry and from 1919 to 1929 it was apparent in all but six: namely, gold and silver lode mining, placer gold mining, crude gypsum production, marble quarrying, asbestos production, and fluorspar Tninino mining

Jan 1, 1933

On the following pages are abstracts of papers published by the Institute during the year 1935 as TECHNICAL PUBLICATIONS and CONTRIBUTIONS, papers in bound volumes appearing for the first time, and papers in MINING AND METALLURGY. For abstracts of papers that appeared in bound volumes in 1935 but that were published as TECHNICAL PUBLICATIONS in 1934, see the YEAR BOOS dated January, 1935.. Many of the TECHNICAL PUBLICATIONS have been reprinted in bound volumes. Information regarding this disposition, and number of pages in each paper, may be found in the list beginning on page 64. Volume numbers are given as listed at the beginning of the index, page 71. The abstracts are grouped as follows: [Page Metal Mining 17 Uses of Metals 23 Milling and Concentration 23 Iron and Steel Division 26 Nonferrous Metallurgy (Reduction of Ores)...: 34 Institute of Metals Division (Founding and Metallography of Nonferrous Alloys) 36 Page Coal Division 43 Petroleum Division 50 Industrial Minerals Division (Nonmetallics) 57 Mining Geology 60 Mineral Industry Education Division 62 Geophysical Prospecting 62]

Jan 1, 1936

By H. O. Hofman

At the Lake Superior meeting, September, 1904, Messrs. A. Gibb and R. C. Philp presented a paper entitled " The Constitution of Mattes Produced in Copper-Smelting,"' in which they concluded that ferrous and cuprous sulphides formed the chemical compound, 5 Cu2S, FeS. They arrived at this inference from the observed fact that a matte containing Cu,S, 90.4, and FcS, 9.6 per cent. (or, in round figures, Cu2S, 90, and FeS, 10 per cent.), did not contain any metallic copper, while one with more than 10 per cent. of FeS readily dissolved copper, and with less than this amount retained copper in mechanical suspension. Although they determined the melting-points of five mattes containing from 32.6 to 80.1 per cent. of copper, they did not draw a freezing-point curve, as the necessary apparatus was not available. A microscopical examination of 11 polished samples gave them a grayish-black field of very uniform appearance, except that five of the specimens showed the presence of metallic copper. The object of the present investigation was to supplement the above paper by drawing the freezing-point curve of the ferrous sulphide-cuprous sulphide series, and to see how the constitution could be further revealed by microscopical work. The results obtained lead to conclusions very different from those of Gibb and Philp. While their paper bears the date 1904, it was published only in 1906.2 In the meantime, Bolles3 had presented his paper, " The Concentration of Gold and Silver in Iron-Bottoms." The raw material which formed the basis of the research was a matte containing Fe, 61.68, and Cu, 11.20

Jan 1, 1908

P. W. BRIDGMAN.-Owing to a misunderstanding, I did not see Dr. McAdam's and Dr. MacGregor's remarks on my paper on Flow and Fracture (Metals Technology, December 1944, Pp. 32-38), until after their publication. Both Dr. McAdam and Dr. MacGregor speak of my analysis for the stress distribution at the neck of a tension specimen as containing several assumptions; in particular, that the strain is uniform across the section of the neck, that there is no hoop tension at the periphery, and that the plasticity conditions of von Mises hold. As far as the mathematics goes, the situation is no different in this problem of plastic flow than in a conventional problem of elasticity. That solution is unique which satisfies the boundary conditions on the stresses, the stress equations of equilibrium, and in addition the constitutive equations connecting stress and strain in the elastic case, or a corresponding set of equations, of which the von Mises relations are a special form, in the plastic case. In the particular case of the necked tension specimen I have found that there is a solution satisfying the boundary conditions, the stress equations of equilibrium, and the von Mises plasticity conditions in which the strain is uniform across the section, and there is no hoop tension at the periphery. This is therefore the solution, and the uniformity of strain and vanishing of hoop tension at the periphery are to be described as discoveries, over which the operator has no control, rather than as assumptions. The only part of the solution that can properly be described as an assumption is the von Mises plasticity condition. With regard to this it is to be noted that the condition is needed only in a much weakened form, for the analysis uses the condition only at the neck, where the strain is approximately constant. Thus, in the extreme case referred to in a footnote of my paper (p. 37, Met. Tech. Dec. 1944) the actually measured strain across the section varies from 2.4 to 2.6. Obviously it is a much weaker assumption to postulate that the von Mises condition holds in the strain range 2.4 to 2.6 than to assume it to hold for the entire range of strain from o up to 2.6, which would be necessary if the solution applied to the entire tension specimen rather than to the immediate region of the neck only. Furthermore, it is to be commented that under the special conditions of this problem the von Mises condition becomes identical with the maximum shearing-stress criterion of plastic flow; this amounts also to a weakening of the restrictions imposed by the von Mises condition. Dr. MacGregor refers to actual experiments of his own in which the strain was found not to be uniform across the neck. It is to be emphasized, however, that these were experiments on bars of rectangular section, and that the nonuniformity established was a nonuniformity around the perimeter, not a nonuniformity from the surface toward the axis. My method of solution applies only to a circular cross section. It can be said that the solution that satisfies the boundary conditions, etc., would definitely not be expected to demand a uniform strain for noncircular sections. In discussing my results, Dr. McAdam uses a definition of "flow stress" different from mine, so that the immediate applica-

Jan 1, 1945

By Robert S. Archer

THE proper material of construction for a given purpose is that material which meets the requirements satisfactorily at the lowest ultirnatc cost. It is consistent with this principle that most aluminum castings are made of an alloy containing about 8 per cent. copper. This alloy possesses mechanical properties satisfactory for general engineering purposes together with manufacturing characteristics leading to the production of finished castings at low cost. It is to the aluminum industry what gray iron is to the iron and steel industry. Just as some services require "semi-steel," malleable castings or steel castings instead of gray iron, there is a certain and growing demand for aluminum castings of superior strength or ductility, or both. Since the beginning of .the industry producers and others have sought to develop alloys or processes by which such castings could be made. Out of these efforts have emerged many alloy compositions and special processes, of which only a few have had sufficient merit to survive. It is the purpose of this paper to describe those which seem to the authors to offer the greatest promise for the production on a commercial scale of aluminum castings of superior mechanical properties, with special reference to heat-treated castings. The suitability of an alloy or process for actual manufacture is affected by so many factors that the problem of appraisal is not a simple one. Since this is such an important part of the whole subject it is proposed to discuss briefly some of the requirements. The final verdict is of course the result of commercial trial and experience. It will therefore, perhaps, be profitable to employ a somewhat historical method of treatment in discussing the subject of alloy development. The alloys or processes to be used in the production of aluminum castings are to be considered from the standpoint of their effects on both the utility and the cost of the finished casting. Specific gravity and mechanical properties come under the first head, while the properties

Jan 1, 1927

By B. S. Butler

PART I SUMMARY CERTAIN relations between the formation of ore deposits and other geological processes are pretty generally accepted, namely: that many ore deposits are closely associated with igneous activity; that ore deposits accompany certain types of intrusive bodies, notably batholiths and stocks, and that they are concentrated near the tops of such bodies; that igneous activity occurs in belts of strong folding and faulting; that folding and faulting are greatest in basins of extensive sedimentation and least in areas of erosion or slight sedimentation; that areas of erosion or slight sedimentation and of heavy sedimentation persist over long periods and exert a major control over structure, igneous activity, and ore deposition; that cycles of erosion, deposition, folding and faulting, igneous activity, and ore deposition, have been repeated through geologic time resulting in rather definite periods in which metal deposits have formed. In short, ore deposition is but one phase of a series of closely related geological events. It is attempted in this chapter to point out the relations of these interreacting geologic processes to the distribution of ore deposits in the western United States. Three great periods of mineralization are recognized; pre-Cambrian, post-Jurassic, and late Cretaceous-Tertiary. In distribution the deposits of the three periods, with certain exceptions, show a concentration about two large positive areas, the Colorado plateau and the Columbia plateau, which suggests a causal relation. The most general age divisions of the rocks of the Cordilleran region of the United States are (1) pre-Cambrian, and (2) Cambrian and later rocks. The pre-Cambrian rocks are exposed mainly through the Rocky Mountain belt from the Canadian boundary southward to Arizona and westward through Arizona to southern California. They have commonly

Jan 1, 1933

By GEORGE D. RAMSAY

WHEN the Ironton blast furnace of the Columbia Steel , Co. was first put into operation the iron ore was mined frol11 the deposit near Iron Springs, Utah. This is principally a hematite with 12 to 20 per cent of magnetite finely disseminated throughout the ore. It varies from a fairly soft broken rock structure to that which is hard and compact. In the broken form it will weigh about 150 lb. per cu. ft., and in place the density is approximately 250 lb. per cu. ft. The first ore received for the blast furnace was crushed so as to pass through approximately a 4-in. square opening screen. A typical screen test of this ore is shown in Table 1.

Jan 1, 1935

By David R. Mitchell

Many of the difficult operating problems of the preparation of coal for market, of sampling coal shipments and in the utilization of coal are caused by segregation in the coal mass. Segregation may be of two kinds: i.e., "size segregation," in which particles of the same size in a mass of coal containing a range of sizes collect together and "density segregation," in which particles of the same density or specific gravity in a mass of particles of varying density gather together. Mechanics of Segregation Size segregation cannot take place with closely sized coal. As the size range increases, the tendency for size segregation increases. Similarly, cleaned coal with particles of approximately the same specific gravity have very little tendency for density segregation. The wider the density range of particles and the more particles of different density, the greater the chances are for density segregation. The following discussion deals primarily with coal of a wide size range as screenings and of wide density differences as uncleaned or run-of-mine screenings. If a mass of coal containing particles of a wide size range is subject to the stream action of a moving current of water, the small particles are transported farther than the coarser. Particles of different density in a stream of moving water are subject to the laws of classification, the heavier settling out first. The familiar sluice box of the gold miner and the action of rivers and other streams in classifying material according to

Jan 1, 1938

By David R. Mitchell

Many of the difficult operating problems of the preparation of coal for market, of sampling coal shipments and in the utilization of coal are caused by segregation in the coal mass. Segregation may be of two kinds: i.e., "size segregation," in which particles of the same size in a mass of coal containing a range of sizes collect together and "density segregation," in which particles of the same density or specific gravity in a mass of particles of varying density gather together. Mechanics of Segregation Size segregation cannot take place with closely sized coal. As the size range increases, the tendency for size segregation increases. Similarly, cleaned coal with particles of approximately the same specific gravity have very little tendency for density segregation. The wider the density range of particles and the more particles of different density, the greater the chances are for density segregation. The following discussion deals primarily with coal of a wide size range as screenings and of wide density differences as uncleaned or run-of-mine screenings. If a mass of coal containing particles of a wide size range is subject to the stream action of a moving current of water, the small particles are transported farther than the coarser. Particles of different density in a stream of moving water are subject to the laws of classification, the heavier settling out first. The familiar sluice box of the gold miner and the action of rivers and other streams in classifying material according to

Jan 1, 1938

By William Newton Best

Oil burners, oil furnaces, and methods of installation, have been the subject of many articles, but information concerning oil-burning systems, based upon scientific principles, is still in great demand, especially in the manufacturing districts of our country. Fuel oil, as it is termed (this being the residuum from oil refineries), has for many years been of great service to our manufacturers, and has justified its popularity not only by producing a superior manufactured product, but by turning out approximately 50 per cent. more product than can be made with coa1 fuel under like conditions. To install a system requiring only an oil-storage tank, a small pump, and an oil-supply main with numerous laterals leading to the various burners, furnaces, boilers, etc., is a comparatively simple matter; and, because fuel oil is very volatile, it is not necessary to heat it, even during the winter months in a very cold climate. Furthermore, only a small amount of power is required to atomize fuel oil, this often being done by a positive pressure blower, or by a mechanical burner. An analysis of fuel oil, together with that of various other liquid fuels, is given in Table I.

Jan 1, 1915

By W. N. Best

(San Francisco Meeting, September, 1915) INTRODUCTION CRUDE oil attracted attention because of its excellence as a fuel for open-hearth furnaces; for making crucible steel and brass; for melting copper, lead, tin, zinc, nickel, silver, malleable iron, gray iron; and for the production of steam in all sizes and types of boilers. For heating furnaces, mold-drying ovens, core ovens, ore roasters, calciners, hot-air furnaces, sand drying, asphalt road work, etc., its superiority over other fuels is due to the fact that the heat is at all times under perfect control, so that a constant temperature may be attained and maintained at the will of the operator. This means a maximum amount and uniform quality of work. Crude oil is of two kinds, paraffine base and asphaltum base, and varies from 11 to 46 gravity Baumé. The light-gravity oil does not require heating before use; but oil of less than 20 gravity Baumé should be heated to just below its vaporizing point, in order to reduce its viscosity and to obtain the highest efficiency of combustion. Heavy California oil vaporizes at 230°'F., Mexican crude oil at from 175° to 210° F., and Beaumont, Texas, oil at 142° F. Fuel oil vaporizes at 130° F.

Jan 8, 1915

By W. N. Best

THIS paper is not intended as a scientific discussion of the combustion of oil but is written from, the standpoint of an operator who has the experience and qualifications necessary to guide others in producing the most economic results in the use of liquid fuels. Oil, in this paper, usually, means petroleum or its products but incidental reference is made to other liquid and gaseous fuels, so that the term may be considered, as referring to all liquid and gaseous hydrocarbons in comparison with solid fuels, as coal and. wood. However, only a few of the principal factors in the use of oil as a fuel can be given. The present, and prospective, high price of coal is causing users of fuel to renew inquiry as to the merits of other forms of fuel for industrial purposes. Crude oil (petroleum) is proving to be one of the world's most valuable mineral resources. The recent discovery that oil underlies a considerable area of the United States, Mexico, and other parts of the world to a greater extent than was formerly believed and the large production of some of the wells in these areas shows the probable quantity of fuel oil that may now be available. Through the energy of Lord Cowdrey, who was one of the pioneers of the oil industry in Mexico, oil has been discovered in England; some prominent geologists believe that it may be found yet, in quantity, in Great Britain. For years, oil has been known to be of great value in the manufacture of metals. It has proved incomparable in forge shops, steel foundries, heat-treating furnace s, and wherever accuracy of temperatures is essential, or where a maximum output is desired as well as quality of metal. In some types of equipment, the output produced with oil as fuel is double that obtained with coal and, at a reduction of 50 per cent, in the cost of the fuel. For example, in drop-forging plants, the metal is always waiting for the man when oil is used as fuel, whereas with coal, the man must wait for the metal to become sufficiently heated.

Jan 8, 1920

By W. N. Best

This paper is not intended as a scientific discussion of the combustion of oil but is written from the standpoint of an operator who has the experience and qualifications necessary to guide others in producing the most economical results in the use of liquid fuels. Oil, in this paper, usually means petroleum or its products but incidental reference is made to other liquid and gaseous fuels, so that the term may be considered as referring to all liquid and gaseous hydrocarbons in comparison with solid fuels, as coal and wood. However, only a few of the principal factors in the use of oil as a fuel can be given. The present, and prospective, high price of coal is causing users of fuel to renew inquiry as to the merits of other forms of fuel for industrial purposes. Crude oil (petroleum) is proving to be one of the world's most valuable mineral resources. The recent discovery that oil underlies a considerable area of the United States, Mexico, and other parts of the world to a greater extent than was formerly believed and the large production of some of the wells in these areas shows the probable quantity of fuel oil that may now be available. Through the energy of Lord Cowdrey, who was one of the pioneers of the oil industry in Mexico, oil has been discovered in England; some prominent geologists believe that it may be found in quantity in Great Britain. For years, oil has been known to be of great value in the manufneture of metals. It has proved incomparable in forge shops, steel foundries, heat-treating furnaces, and wherever accuracy of temperatures is essential, or where a maximum output is desired as well as quality of metal. In some types of equipment, the output produced with oil as fuel is double that obtained with coal and at a reduction of 50 per cent. in the cost of the fuel. For example, in drop-forging plants, the metal is always waiting for the man when oil is used as fuel, whereas with coal, the man must wait for the metal to become sufficiently heated. It has only been since January, 1919, that the oil supply could be relied on for boiler service, owing to the war conditions and the inability to get oil tankers for the delivery of the oil from Mexico to Atlantic ports; but now a constant supply is assured, and many manufacturers are installing it in their power plants. The cost varies with the size of the

Jan 1, 1921

By L. Weaver

THE Tennessee Copper Co.'s mines are in the southeast corner of the state of Tennessee. Polk Co., in the well-known Ducktown copper basin. Their new circular production shaft will eventually be the only ore hoisting shaft, and is located for handling ore from Boyd, Calloway, Mary, and Cherokee mines. A circular, rather than a rectangular, shaft was decided upon because: 1-The circular shaft section is stronger when lined with concrete. Reinforcing steel was not required, thus reducing lining cost by one- quarter. 2-Water sealing was desired; it was thought it could best be done with a concrete lining followed by pressure grouting to eliminate water seeps. 3-The shaft labor saving equipment could best be used in a large opening, so the round section was made for economy, sinking, mucking, concreting and water sealing. Less shaft steel is used than could have been possible with steel sets. There are no posts required; center beams and Tee plate assembly placed at 10 ft hold the 100 lb steel guide rails. The shaft is 12 ft 7 1/2 in. ID of the concrete walls. This is large enough for two 10-ton hoisting skips and a ladder compartment. One of the skip compartments is for hauling equipment. The grouting equipment was a 2%xlO-in. Gardner-Denver grout pump, air powered and developing 1000 lb pressure. A grout mixer, also air driven, fed the mixed solution into a tank coupled to the pump suction. Grout materials used were mostly water and Portland cement. Some Bentonite was used to seal porous ground near the surface.

Jan 11, 1950

By C. B. Foster, S. I. Freedman, E. M. Jamgochian

Coal-oil mixture (COM) combustion technology is regarded by the US Department of Energy (DOE) as near term and Potentially applicable to existing utility and industrial steam generators and for injection into blast furnaces. From work done previously, it has been established that COM can be burned in existing boilers and blast furnaces. Therefore, the issues being addressed by the current DOE program are: (1) determination of best available technology to achieve environmentally acceptable long-term reliable operation and (2) determination of applications for which COM can be utilized economically. Some of the technological options have begun to be determined by projects already under way. However, many projects are still in the early stages of development.

Jan 1, 1980

By H. E. Cline

Solidification of Pb-Sn alloys ranging in composition from 1.2 to 56 at. pct Pb ws observed with polarized light. Lamellar structures were observed over a larger range of compositions in alloys containing excess tin than excess lead, as expected from constitutional supercooling. The occurrence of pools of supercooled liquid surrounded by lead is explained by the difficulty in nucleating tin. Cells and dendrites weve observed in tin-rich alloys. Evidence was found that the degenerate structure formed at low growth rates, the formation of faults, and abrupt changes in composition and structure can be attributed to non-steady-state growth. The apparent interface shape was observed to have deep grooves at the interphase boundaries. HUNT and Jackson have observed the shape of the interface during growth of organic eutectics. They observed the formation of lamellar faults and shape instabilities upon changes in growth rate. The lamellar structure in these organic eutectics was not restricted to the eutectic composition. Recent work by Mollard and Flemings2 indicated that Pb-Sn alloys from 12 to 26 at. pct Pb could be solidified with a lamellar or rodlike structure if a sufficiently steep temperature gradient was used at a slow growth rate. Observations of the solid liquid interface of the Pb-Sn eutectic were made by Davies3 using polarized light. Photographs were at too low a magnification to determine the interface shape, but he has concluded that tin was the leading phase. In the following experiments, solidification of a range of Pb-Sn alloys from 1.2 to 56 at. pct Pb was observed using polarized light, to determine the factors controlling stability of the lamellar structure. EXPERIMENTAL Procedure. One hundred-gram ingots of alloys prepared from 99.999 pct pure Pb and Sn were cast into graphite molds under argon. The compositions of the alloys were 1.2, 6, 12, 26, 36, 46, and 56 at. pct Pb. Two-gram pieces were melted between two cover glass slides which were squeezed into a 1-mm separation. Samples were then observed under polarized light in a hot stage shown in Fig. 1. A long working distance objective designed for viewing at 500 times was used. Photography was made difficult by the lack of illumination and contrast at these high magnifications. By using an elliptical polarization compensator, as suggested by A. Holik, the contrast and illumination could be optimized. Photographs could be taken only at slow growth rates to avoid excessive interface motion during the 15-sec exposure used. The solidification rate was varied by increasing or decreasing the power to the heater. It was found that insulation was necessary to avoid undesired growth rate fluctuations. The temperature gradient, as measured with two thermocouples 1 cm apart, was 80" ± 20°C per cm during all the experiments reported here. The advantage of this procedure is in being able to observe solidification while it is occurring. However, the observations are restricted to the glass-metal surface and may be influenced by this surface. Also, one has no knowledge of the interior of the sample, in contrast to studies of the freezing of transparent organic eutectics.' Observations. The alloy near the eutectic composition (26 at. pct Pb) solidified in a lamellar structure when the growth rate was uniform. If the growth

Jan 1, 1968

DAVE BARTLEY and Edwin F. Gray, miners, late of Shasta County, California, young, healthy, and "dead broke," arrived at Ely, Nevada, one evening in the summer of 1900. Before rustling jobs and going to work, they decided to look around the camp, and in pursuance of this plan they visited a number of claims owned by D. C. McDonald, Justice of the Peace and pioneer of the district. Among the claims he showed them were the Ruth (named after his daughter) and the Kearsarge. Both were regarded as possible gold or silver properties. For no very definite reason the two miners changed their plan and took a lease and option to buy the two claims for $3500. After the transaction was closed and the partners were alone, Gray asked Bartley what he thought of the ground. "If she's good for anything, it's copper" was the reply; and, so far as the records disclose, that was the first time that anyone ever thought of Ely or the Robinson mining district, as it was called, as a possible copper area. There were some slight surface indications of copper, but it is probable that the fact that Bartley had just come from a copper district had something to do with his predilection for a metal that was much despised around Ely. In any event, his hunch was good, and he spoke with the wisdom of an oracle. For thirty years prospectors had sought gold and silver around the camp. Several stamp mills and cyanide plants had been put up and a hundred shafts had been sunk, but fate had been indifferent in its rewards to the optimistic owners. Copper ore would have to be hauled by wagon, 150 miles down Steptoe Valley to the Southern Pacific Railroad, and there was scant hope of finding ore that would bear this cost. W. B. Graham, who ran the general store in Ely, grubstaked Bartley and Gray, furnishing them with food and mining

Jan 1, 1933

By W. Armstrong Price

INVESTIGATION by German chemists during the World War showed that particles of iron oxide form rapidly in iron pipes carrying hydrogen gas under pressure when the gas contains small amounts of water. Under these conditions, the gas frequently exploded when expanding into a dirigible. The explanation of the explosions lies in the building up of a charge of static electricity in the flow just beyond the orifice and the ignition of the gas by a spark accompanying discharge of the electricity. Friction between the moving particles and the pipe generated the electric charge, which was manifested by a pale blue glow formed in the flow at pressures above two atmospheres. In one experiment, this glow, at eighty atmospheres, extended for a distance of forty to fifty centimetres, but did not ignite hydrogen and air mixtures until the charge was col-lected by a conductor and discharged across a gap between electrodes placed at the side of the column of gas. Autoignition did not occur when this discharge was effected at a distance from the gas column, nor if the gas used was thoroughly dried and free from impurities. The electric charge has been studied by placing various wire and screen conductors in the outcoming stream of gas, Guest having summarized these experiments. The application of these conclusions to fires in petroleum and natural gas issuing uncontrolled from wells is made in the following paper, citing the ignition of a wild gas well in Texas.

Jan 1, 1936