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By K. A. SPENCER

THE production of soft coal from strip mines in the United States has shown a remarkable growth in the last sixteen years, increasing from one and one-quarter million tons in 1914 to approximately twenty-two million tons in 1929. This is a growth of approximately 1660 p& cent, as compared with a growth of approximately 20 per cent in the underground mines for the same period. But even with this marked in- crease the total tonnage produced by open-face mining represents only 4 per cent of the nation's soft coal tonnage.

Jan 1, 1931

C. W. WASHBURNE; New York; N. Y. (communication to the Secretary *).-It has long been known that sulphur and oxygen react upon crude oils, removing hydrogen and thereby creating unsaturated hydrocarbons which unite with each other, producing heavier forms. Dr. Rogers now finds that the percentage of sulphur in the oils of several fields in California is roughly proportional to the specific gravity of the oil. This additional proof is most welcome. It is rather surprising, , in that the impression had prevailed that practically all the reacting sulphur escaped from the oil as hydrogen sulphide, and did not remain in combination with the oil. It would be interesting to know what part of the sulphur-plotted by Dr. Rogers is in solution as free sulphur and hydrogen sulphide, and what part is, in more complex compounds, such as thiophanes, etc.

Jan 10, 1917

By GEORGE A. KIERSCH

The awesome destructive power of known and projected weapons of war presages a new need for geologists and engineers, who may be called upon to locate vital industry underground, thereby protecting it from sky-borne destruction. The Corps of Engineers is now conducting special tests to establish design standards covering the general field of underground installations as well as surveys a of construction methods and the operational hazards connected with such plants. National planning must dictate a policy that is either tactical, where surface manufactured parts; are stored underground and during art emergency assembled, or operational with both the manufacturing and assemblage completed in subsurface plants. Both plans of operation require the use of subterranean plants. Relocation of vital plants underground will probably involve only a small percentage of the production capacity of this nation. The cost of rebuilding in new location will obviously limit its adoption

Jan 1, 1949

By W. M. Corse

AS THE outstanding contribution of the Committee on Correlation of Research of the Institute of Metals Division for 1932, may be mentioned the publication of Bureau of Mines Information Circular 6637, entitled "Research Activities in the Mineral Industries of the United States." This circular was compiled by A. C. Fieldner and Alden H. Emery, members of the Committee, in cooperation with the Bureau, and comprises a285-page list of research problems reported to the Bureau as engaging the attention of the various mineral industries. To obtain this information questionnaires were sent to 106 governmental agencies, 338 trade and professional associations, 524 colleges and universities, 9 endowed research institutions, and 1847 private companies and consulting laboratories. In order that the returns should be as complete as possible, the original mailing list included names from which it was not expected much pertinent information would be obtained. However, the procedure was justified as significant returns were obtained from many of these.

Jan 1, 1933

By Donald M. Liddell, G. C. RIDDELL

THE cosmic ray continues to engage the attention of the physicists, and according to Millikan and Compton, experiments of the past summer indicate that these rays must come from interstellar space, but not from the stars themselves. According to press reports of the International Congress of Physicists at Rome, the view was given there that these rays have an initiating potential of over 750,000.000 volts. In the field of spectrographic investigation great strides have been made. The U. S. Naval Research Laboratories (R. F. Mehl and G. E. Doan of Lehigh) have just finished a year's work with a "radium torch" or "shadowgraphic apparatus" in the field of the X-ray, that bids fair to displace the latter to a great extent. The torch is more powerful., easier to operate and cheaper. Penetration of 10 in. of steel has been accomplished, which. is much -beyond the- -scope-, of the X-ray..

Jan 1, 1932

By R. D. Nelson, F. E. Bowman

Assumptions are made of ideal mixing and that the density of silver can be obtained by extrapolating reported liquid density-temperature data through the freezing point back to the temperature range of interest. The results of this procedure using liquid silver density data of Kirshenbaum et al.5 are presented in Table I1 where it is observed that agreement is everywhere within <0.1 pct and generally is within 0.05 pct. Because the Sn-Ag alloys are dilute, the assumption of ideal behavior is, therefore, probably justified. In conclusion, the densities of dilute liquid solutions of silver in tin have been determined. Even for concentrations as low as 0.1 pct, the effect of silver on the density of liquid tin is clearly measurable. This work also suggests that for dilute alloys at temperatures far below the freezing point of the solute metal, densities may be accurately calculated by extrapolation of the pure metal data without having recourse to physical measurement on the alloy itself. plutonium having a grain size of about 100 µ. This paper presents data showing that large elongations of fine-grained a Pu can be obtained by using slow deformation rates. Large plasticity, however, of a Pu in compression has been observed.4 Reductions in thickness of 90 pct have been observed with no edge cracking. These large reductions are accompanied by concurrent re-crystallization. The deformation modes, which are quite complex, have been studied extensively by observing the deformation microstructures of polished surfaces that had been deformed in compression.5-7 Although slip apparently is a predominant mode of deformation at room temperature, grain boundary sliding and concurrent recrystallization become more predominant at high a temperatures.4&apos;7 Although recovery occurs,8,9 no grain growth has been reported in a Pu even at temperatures near the a =ß equilibrium temperature (-115oC), which is 0.7 of the calculated melting temperature of a Pu.10 From studies on other materials, it appears that high elongations can be obtained in alloys when the THE purpose of this technical note is to present briefly some data revealing high ductility of a Pu, which is normally considered brittle. The very low ductility of a Pu in tension has been reported by many investigators.&apos;-3 Gardner,1 for example, reported that the total elongation of a Pu at a testing speed of 0.015 ipm is less than 0.1 pct at room temperature and only about 1 pct at 100°C. The only tensile creep studies that have been reported&apos; indicate no large ductility, but they were performed on relatively low purity

Jan 1, 1970

IT will be recalled that when educational instruction for the mineral industry began at Freiberg, at the beginning of the eighteenth century, the original aim was to organize and systematize the procedures previously followed by young men in gaining familiarity with the technology then in use. There must have been many other ideas current, even then, as to just what a young man needed to learn in order to become capable of assuming responsibility for the supervision and direction of such technical work. The problem in Europe was decidedly different from that in nineteenth-century America, because some of the European mines were actually owned and operated by the governing authority and the others were supervised, regulated, and taxed by it. The American problem was the efficient performance of technical operations; the European one was regulatory supervision. It was natural, therefore, that in the development of educational processes in Europe stress was laid on those factors which conserved and protected the interests of the state. The study of mineralogy and geology, leading to correct judgments as to the workability and value of mineral deposits; assaying, which gave the means of quantitative measurements, as did surveying; chemistry, which furnished a better basis of understanding for assaying, mineralogy, and geology; and physics and mathematics, which are the bases for the understanding and efficient use of mechanical appliances, became the core of systematic instruction for the mineral industry. It was early recognized that men could learn more than was already known about all of these subjects and education took on that dichotomy which still characterizes it; the teaching of established knowledge to the unlearned, and that of extending of the bounds of knowledge, now loosely termed research, which after two and a half centuries of work still shows

Jan 1, 1941

By W. A. Backofen, M. L. Ebner

SINCE the early work of Gough with Hanson and Wright,l-3 the study of fatigue has been characterized by experiments on single crystals only in recent times.9-10 Now, increasing attention is given to this aspect of fatigue research for the insight that it may provide into details of mechanism. The investigations have concentrated to a large extent on the development of deformation markings on fatigued crystals, and have shown the cracks to originate in slip bands possibly preceded or accompanied by slip-band extrusions. Experiments of special interest to the present work were conducted by paterson5 on copper crystals and involved both metallographic examination and measurement of change in flow stress. Crystals were cycled in alternating tens ion-compress ion with a constant plastic shear-strain amplitude of approximately 0.8 pct, and were particularly revealing for their demonstration of hardening with accumulated strain similar to that in unidirectional straining, through an easy-glide stage I followed by a stage II of rapid hardening; deformation was not continued beyond 40 cycles, however, so that the eventual course of the hardening curve could not be decided. For the conditions used by Paterson, surface slip markings were similar to those observed in unidirectional straining, but there were no X-ray asterisms and no deformation bands on the surface. In current thinking about the nature of fracture in fatigue, two views relative to mechanism are generally acknowledged, with the reservation that both could apply simultaneously in some measure. As one possibility, fracturing across a slip plane is regarded as a result of loss of cohesion from the creation of many point defects by dislocation movement under the cyclic loading.&apos;&apos; On the other hand, fracture has also been taken to follow as a consequence only of the geometry of slip at a free surface, consisting of offsets and crevices which eventually become fatigue cracks.12, l3 The work of McCammon and Rosenbergl4 showing fatigue in polycrystals at 4.2oK makes clear that any long-range diffusion of point defects is unnecessary, yet studies such as those of Forsyth and stubington15 show that accelerated diffusion may be a characteristic of deformation under fatigue loading. Interest in obtaining data of possible use for resolving such questions led to the experiments described below. Copper crystals were conveniently loaded in alternating four-point bending at constant deflection, a test condition shown to approximate a constant plastic strain amplitude for a wide range of axial orientations. The method of testing was not readily adapted to extensive study of temperature effects, but an investigation of the geometry of crack formation could simply be made by orienting,the slip direction at different angles to the surface. EXPERIMENTAL PROCEDURES Single crystals were grown by a modified Bridgman method in a stationary gradient furnace under an atmosphere of purified dry nitrogen. Purity of as-grown crystals was 99.999 pct as determined by spectrographic analysis plus vacuum fusion and gravimetric analyses for oxygen and sulfur, respectively. Crystals were of reasonable perfection as evidenced by a critical resolved shear stress at 10 deg from (110) of 60 g per sq mm and half-width of a (400) X-ray diffraction line from one crystal of

Jan 1, 1960

By O. B. Ellis, Eric R. Jette, John Chipman

In the study of the chemical reactions orcurring in the open-hearth furnace, it is frequently assumed that a condition of equilibrium between slag and metal is attained. In order to test this assumption it is necessary to have dependable operating data as well as an exact knowledge of the equilibrium state. Considerable progress has already been made in the study of slag-metal equilibria, notably in the earlier work of Hertyl and of Oberhoffer and Schenck2 and in the more recent researches of Krings and Schack-mann3 and of Koerber and Oelsen.4 None of these investigators, however, have employed basic slags comparable to those encountered in basic open-hearth practice, so that up to the present time our only information regarding the equilibria of these slags is based upon observations drawn from steelmaking practice in which there is little assurance that actual equilibrium was attained. The original plan of this investigation was to secure simultaneous slag and metal samples at intervals during the making of an open-hearth heat, recording the heat history in detail and obtaining complete allalyses of slag and metal, then to bring these slag samples into equilibrium with liquid iron in the laboratory induction furnace and thus to determine directly whether or not the observed relationships in the open hearth represent conditions approaching equilibrium. This plan was only partly successful. While slags were obtained from the open hearth under satisfactorily recorded conditions and these were re-melted in the laboratory under equilibrium conditions, changes in slag composition, which accompanied the remelting operation, were so great that the final slag from the induction furnace bore little resemblance to its open-hearth parent and the direct comparison was therefore abnndoned. The results, however, lie within a range of slag composition that is of interest in the making of low-carbon steel. As far as we are aware, they represent the first published laboratory study of equilibria involving slags that contain all the con stituents of basic open-hearth slag. Experimental Heats The first set of measurements on slag-metal equilibrium was made in the Research Laboratories of the American Rolling Mill Co, at Middletown, Ohio. This will be known as series A. The second set was made in the Metallurgical Rescarch Laboratories at Massachusetts Institute of Techology, and will be referred to as series B. Series A.—The induction furnace used has been described. Approximately I kg. of a special ingot iron containing less than

Jan 1, 1941

By John Chipman, Eric R. Jette, O. B. Ellis

In the study of the chemical reactions orcurring in the open-hearth furnace, it is frequently assumed that a condition of equilibrium between slag and metal is attained. In order to test this assumption it is necessary to have dependable operating data as well as an exact knowledge of the equilibrium state. Considerable progress has already been made in the study of slag-metal equilibria, notably in the earlier work of Hertyl and of Oberhoffer and Schenck2 and in the more recent researches of Krings and Schack-mann3 and of Koerber and Oelsen.4 None of these investigators, however, have employed basic slags comparable to those encountered in basic open-hearth practice, so that up to the present time our only information regarding the equilibria of these slags is based upon observations drawn from steelmaking practice in which there is little assurance that actual equilibrium was attained. The original plan of this investigation was to secure simultaneous slag and metal samples at intervals during the making of an open-hearth heat, recording the heat history in detail and obtaining complete allalyses of slag and metal, then to bring these slag samples into equilibrium with liquid iron in the laboratory induction furnace and thus to determine directly whether or not the observed relationships in the open hearth represent conditions approaching equilibrium. This plan was only partly successful. While slags were obtained from the open hearth under satisfactorily recorded conditions and these were re-melted in the laboratory under equilibrium conditions, changes in slag composition, which accompanied the remelting operation, were so great that the final slag from the induction furnace bore little resemblance to its open-hearth parent and the direct comparison was therefore abnndoned. The results, however, lie within a range of slag composition that is of interest in the making of low-carbon steel. As far as we are aware, they represent the first published laboratory study of equilibria involving slags that contain all the con stituents of basic open-hearth slag. Experimental Heats The first set of measurements on slag-metal equilibrium was made in the Research Laboratories of the American Rolling Mill Co, at Middletown, Ohio. This will be known as series A. The second set was made in the Metallurgical Rescarch Laboratories at Massachusetts Institute of Techology, and will be referred to as series B. Series A.—The induction furnace used has been described. Approximately I kg. of a special ingot iron containing less than

Jan 1, 1941

By James M. Schopf

Gilbert H. Cady (Senior Geologist, Head of Coal Division Emeritus, Illinois State Geological Survey, Ur-bans)— Those coal mining and preparation engineers and operators who read this article will probably be most concerned with those parts which deal with the applied aspects of coal petrology in the fields of mining and technology. Actually the two categories overlap to such a degree that they are essentially one. The article appears to suggest that there are two points of veiw in the field of applied coal petrology. From one viewpoint the interest is in the attributes of the various macerals (Fig. 4)—vitrinite, exinite, and inertinite—-in terms of utilization (when the coal is burned, coked, gasified, hydrogenated, etc.). From the other point of view, assuming that the macerals do possess individuality in behavior, interest attaches to the possibility that coal of a particular type (maceral composition) can be prepared by discriminating methods of preparation and blending. Most of the 29 items listed for mining and technology can be assigned to one or the other of these two categories. Somewhat the same simplicity that resides in the items of the proximate chemical analysis is desirable for the petrologic analysis. This simplicity appears to be fairly well achieved by the group maceral device provided mineral matter is also included. At present, without fully adequate experimental substantiation, the three types of material represented by the group macerals vitrinite, exinite, and inertinite are regarded as sufficiently different in composition and properties so that the preponderance of any one type gives the coal distinctive properties provided it is not too high in rank. This appears to be increasingly true with coals of decreasing rank from medium volatile bituminous coals downward. The article reflects the great emphasis placed on the technique of descriptive coal petrology in America. Such description has resulted in a good understanding of the nature of the fundamental variability in the physical composition of bituminous coals. Such understanding has been attained very largely by the thin section technique used in coal bed profile analysis introduced by R. Thiessen after the manner suggested by the data assembled in Table 11. In contrast, the group maceral concept of coal analysis in terms of the categories indicated on the left hand side of Fig. 4 is particularly useful for broken coal analysis and applied coal petrology, in which evaluation is largely based on quantitative concepts. It is inadequately emphasized in this article that although the Thiessen procedure is suitable for the purpose of petrologic description in which texture and orientation are of critical importance, it is less well adapted to the technological uses of applied coal petrology. No doubt those persons whose interest may have been aroused in the possibilities of more refined coal preparation by this and other recent contributions to the literature of coal petrology will understand that certain technical aspects of coal petrology, particularly in the field of descriptive petrology, are still a matter of some controversy among the coal petrologists, but they will also appreciate that Schopf has made an important contribution to the field of coal petrology in America by pointing out that such petrology requires consideration of disoriented or broken coal samples and that results are expressed less in descriptive terms than in quantitative values with respect to the four types of material composing coal—-vitrinite, exinite, inertinite, and mineral matter. Unfortunately because so much American coal petrology has been descriptive of the coal in the bed there is a dearth of literature on applied coal petrology. Research and experimental data in this field are greatly needed.

Jan 1, 1959

By T. E. Leontis, D. H. Feisel

MAGNESIUM alloys containing rare earth metals have received considerable attention during the past several years because of the need for light alloys having high strength and creep resistance at elevated temperatures. Although much of the work reported earlier has dealt with alloys containing Mischmetal, it has been shown in two previous papersl, V hat distinctly different effects are produced by various rare earth metals and rare earth metal mixtures on the properties of magnesium. For example, much higher strengths are obtained in magnesium alloys containing didym-ium (essentially neodymium plus praseodymium) than in alloys made with Mischmetal, which contains all the rare earth metals in the proportions in which they occur naturally in the monazite ore. Mg-rare earth metal alloys are characterized by a relatively coarse grain size, which greatly impairs castability. The addition of zirconium as a second alloying ingredient has been shown8,7 to refine the grain size, which also produces a distinct improvement in the strength properties. Certain Mg-Mischmetal-Zr and Mg-Mischmetal-Zn-Zr alloy compositions which are currently being produced commercially have been discussed in dytail by Nelson and Strieter,8,4 who also present some in- formation on a Mg-low Ce-Mischmetal-Zr alloy, and by Nelson.8 A patent issued to Jessup, Emley, and Fisher9 emphasizes the superiority of Mg-didymium-Zn-Zr alloys over the corresponding alloys made with Mischmetal. The purpose of this paper is to present the results of an extensive investigation concerned with the effect of increasing amounts of zirconium on magnesium sand casting alloys containing several different rare earth metal mixtures in varying amounts. The effect of the addition of zinc to some of these alloys is also being reported. Preparation and Testing of Alloys The alloys studied in this investigation were prepared in small laboratory melts according to the melting procedures described by Nelson1" as the Crucible Method. Electrolytic magnesium having the composition shown in Table I was used as the starting material. The rare earth metal alloying ingredients used in preparing these alloys were essentially of the compositions listed in Table 11. Some of the didymium-containing alloys were prepared using a Mg-didymium hardener. The rare earth metal content of this hardener analyzed 1.2 pct Ce, 10.4 pct Pr, 80.8 pct Nd, and 7.6 pct La. The zirconium was added in one of three forms: 1) as sponge zirconium obtained from the Bureau of Mines; 2) as a fused salt consisting of 50 pct ZrCl, and 50 pct alkali chlorides from which the zirconium is reduced by the magnesium; or 3) as a Mg-Zr hardener. The alloying procedures and melt hand-

Jan 1, 1958

By C. Perez-Rosales

A simplified method for evaluating specific surface of porous media is described. The theory takes as its point of departure a previous statistical method. Due to its simplicity, it is considered that the proposed method has certain advantages over methods currently used. By making some simplifications, the procedure for estimating specific surface is reduced to superposing, on an enlarged reproduction of a section of the sample to be analyzed, an evenly spaced grid and counting the number of intersections of the grid lines with the perimeter of pores. An indirect test of the theory is presented and the advantages of the method are discussed. INTRODUCTION The specific surface of a porous medium, defined as the surface area of the pores per unit bulk volume, is an important parameter with regard to flow of fluids through porous materials. In particular, it has long been recognized that specific surface is closely related to permeability. Since the internal surface of any porous material is extremely complex, the measurement of specific surface can only be accomplished by indirect means. It is considered that the best method&apos; in current use for determining specific surface is the statistical method of Chalkley, Cornfield and Parka who originally applied it for estimating volume-surface ratios of morphologic components, such as cells or nuclei. This method will be outlined later. A method which has been used extensively in determining specific surface is based on the adsorption of a vapor by the internal surface of porous media. However, this method does not yield the surface pertinent to fluid flow, since it includes the tiny molecular interstices which do not influence the permeability of the porous material.&apos; This method has been employed by Brooks and Purcell measure internal surface area of sedimentary rocks. The Kozeny equation, which relates the specific surface to the permeability of a porous medium, has found wide use in determination of specific surface. However, the KOzeny equation is not strictly correct. Large discrepancies have been found between theory and experiments.&apos; Consequently. the specific surface estimated by this method is subject to serious uncertainties. Finally, there are other methods for specific surface measurements which are based upon a variety of physical and chemical properties: the heat conduction by a gas, ionic adsorption phenomena and direct chemical reactions of the surface with other substances. This paper describes a simplified statistical method for determining specific surface of porous materials. It is considered that, due to its simplicity, it has certain advantages over the methods presently used. For its validity, it is required that the porous structure of the material under study be of a spatially random nature. This is not a serious limitation since the naturally occurring porous media have this characteristic. THEORY The method proposed in this paper takes as its point of departure the interesting result obtained by Chalkley et al The method shows that if a line of length r is dropped repeatedly at random over a section of a porous medium, and counts are made of the number of times the two end points fall within pore areas (denoted by h for "hits") and the number of times the line intersects the perimeter of pores (denoted by c for "cuts"), then in a very large number of throws where S is the internal surface of the sample (surface of pores) and V, the volume of the pores (Fig. 1). Since the specific surface S, and the porosity 4 are given, respectively, by S. = Sl V, and 4 = V,l V,, where V, is the total volume of the sample, it follows from Eq. 1

By J. D. Forrester, Erich Sarapuu, T. C. Cheasley

John G. Tripp-—The concept of converting fuel deposits in-situ to useful forms of energy and chemical raw materials has important possibilities as a means of stretching out our fuel resources. The authors have worked in this field for years and in fact are among the pioneers in developing in-situ techniques based on underground electrocarbonization. Their efforts have aroused great interest in this subject and their contributions will undoubtedly gain even more significance as time goes on. The 4 to 5 billion tons of petroleum are proved reserves, that is, they are completely defined and could be produced economically with present methods of recovery. Reserves of coal, tar sands, and oil shale shown in Table I are not equivalent to proved reserves as the term is used in the oil industry. Incidentally, the 4.3 billion tons of oil shown in the tabulation is equal to about 28 billion barrels of oil and, therefore, presumably does not include reserves of natural gas liquids estimated at about 5 billion barrels. The relative comparisons would be more complete if these liquids together with the reserves of natural gas were included in the tabulation. It is stated in the report that production costs of the order of 10c per million Btu&apos;s could be expected from a large industrial electrocarbonization installation. The authors state that the operation probably could be operated successfully and at a profit. I would like to express my view that for the operation to be profitable extremely favorable conditions would have to prevail. For example, the coal seam would have to be thick and close to the surface in order to minimize drilling costs; the deposit should be dry and so situated that there would be little, if any, inflow of ground water; and the seam would have to be relatively gas tight to avoid excessive gas leakage. Notwithstanding the tremendous strides that have already been made, it is my hope that the authors plan to continue their development work. Experiments on underground electrolinking and initial carbonization at Gorgas, Ala., indicate a need for improved control over the operation. Subsequent examination of the underground system at Gorgas has shown that the gasification zone did not always follow a direct path between the electrodes. Undoubtedly the control of the in-situ thermal processes can be improved by further development work. With respect to the electrocarbonization of oil shale it may be well to point out that the cost of mining oil shale is estimated to be 50c to 60c per ton. These are low mining costs as compared to coal. Thus it would appear that there is less economic incentive for applying in-situ thermal methods to oil shale than there is for applying these methods to coal. As is the case with in-situ methods for petroleum, the product from the shale having the most economic interest would be liquid oil rather than gas. The authors point out that for distances up to several hundred miles it is cheaper to transmit energy as electricity than it is to ship energy as coal. This is a very important point, and with coal shipping rates rising periodically, it could prove increasingly important in the future. I believe that the authors deserve great credit for their outstanding work on underground electrocarbonization. The knowledge resulting from their efforts is of great value to our fuels technology. James L. Elder—The experimental work conducted by the authors on the electrolinking-carbonization of carbonaceous materials in situ is of great interest. The method is of great importance in the development

Jan 1, 1955

By H. O. Hofman

THE leading antimony mineral is stibnite. In smelting stibnite ore two processes are available, precipitation and roasting-reduction. The former is suited only for high-grade ores. As low-grade ores are more common than high-grade, roasting-reduction is of greater importance than precipitation. In the roasting process the aim may be to leave the oxidized antimony in the ore, or it may be to volatilize as much of the antimony as possible, collect the volatilized oxide as a rich intermediary product and smelt it for antimony, leaving the gangue poor enough to be considered a waste product. Whichever way the roast is conducted certain difficulties inherent in stibnite are encountered. These are: 1. The low melting point of stibnite which; according to Pelabon,1 is 550°C., according to Wagemann2 540°C., and according to Borgström3 546°C. 2. The ignition temperature: According to Friedrich,4 stibnite, if heated in air, begins to oxidize at 290°C. if the size of a grain is 0.1 mm. in diameter; at 343°, if 0.1 to 0.2 mm.; and 430° if 0.2 mm. 3. The fusibility of a mixture of Sb2S3 and Sb203 which in the form of kermesite (Sb2S3)2.Sb203 melts at 517°C.5 4. The volatility of Sb2S3 and Sb203, for which no numerical data appear to exist, although practical experience has shown that they are volatile at low temperatures.

Jan 1, 1916

By Edward A. Vitunac

The emerging importance of pneumatic conveying systems for bulk materials is largely due to the economic advantages such systems frequently exhibit when compared to alternate methods. Included in these advantages are relative simplicity, ease of installation, flexibility, ease of maintenance, cleanliness, safety and ease of automation to the degree desired. In general, installed costs favor a pneumatic system when compared to competing mechanical systems if the transporting distances are long or to and from many points. In addition, supplemental use such as cooling, heating, or drying may supply the incremental value required to justify its selection.1 The main disadvantages of a pneumatic system are the greater horsepower required per unit weight of material conveyed, material limits in abrasiveness, and density. In addition, material breakage tends to increase at changes of direction and at any obstruction such as that caused by the imperfect butting of two pipe sections in the conveying line. Classification of the material at the discharge may also cause problems in dusting and segregation. Materials weighing less than 4 lb per cu ft tend to cause feeding and collecting problems although they can be conveyed easily. Material between 4 lb and 20 lb per cu ft can be handled with fewer problems, but flow rate is hard to predict. The 20-60 lb per cu ft range offers best results, whereas materials of over 60 Ib per cu ft tend to drop out of the air stream and settle in the pipeline unless careful pro- visions are made to prevent this.2

Jan 5, 1968

By John P. Cosgro

THE increasing use of internal furnace-boilers for mining power-plants (doubtless due to the facility with which they may be installed by reason of their portability; the fact that they require no masonry setting, cast-iron fronts, buck-stays, etc., and practically no foundation; and the successful maintenance of their claim to equal and even superior economy, as compared with boilers of other types) warrants this description of a method of remedying an injury which may occur, to such a furnace, even though it satisfies the requirements of the formula adopted by the U. S. Board of Supervising Inspectors of Steam Vessels.2 I refer to the sagging and deformation which may result from overloading the boilers for a considerable period-say, several days. This is sometimes unavoidable under the exacting conditions of continuous day-and-night service, and (in spite of all rules and precautions, the occasional careless or unskillful work of attendants. Such a trouble is by no means unknown on shipboard, where this type of boiler is so largely employed. In the case here described, two Morrison suspension-furnaces, of half-inch steel, 14 ft. long and 45 in. in mean diameter, with ? dry-back ? boilers, were necessarily operated somewhat beyond their rated -normal capacity for several months, while a third similar unit was -in process of installation, and during this period, though the boilers were kept perfectly clean, heat seems &apos;to have been generated slightly faster than it was absorbed by, the water in the boilers. The corrugations of this.

Mar 1, 1905

By Arthur L. Crawford

PLAGER gold is perhaps the most difficult of the common mineral deposits to evaluate. Not only are the erratic pay streaks a source of never-ending uncertainty, but the spotty distribution of the gold in iso¬lated nuggets is a perpetual source of error and disappointment to the sampler. Experienced engineers have long realized this difficulty and have been wary in predicting assay values except in the most general terms, and then only after extensive and usually expensive sampling. During the past year I have had the opportunity of checking a number of gold placers, and from the results obtained I believe that the microscope may be employed to advantage in placer sampling.

Jan 1, 1933

By Freeman Bishop

This year the metal mining industry is in for some difficult decisions as the nation struggles to control inflationary pressures resulting from higher production costs and a money-squeeze policy. Re- clouding these problems will be campaign oratory as Congress seeks reelection. Charges will be hurled back and forth between a Republican White House and a Democratic Congress. Inflation and Vietnam will be the big one. Hut pollution i. coming on strong. President Nixon has formed a new Council on Environmental Quality although he already had named a similar unit within his Cabinet six months ago. Both are charged with bringing 1.0 bear all of the Federal Government&apos;s talents on the focal points of antipollution measures The biggest task will be to find out how many different "units" are currently mixed up in these efforts.

Jan 1, 1970

By B. S. Tani, R. V. Schablaske, M. G. Chasanov

In the Ti-Cd system two intermediate phases, TiCd and Ti Cd, have been found and characterized by X-ray diffraction powder techniques. An earlier reference&apos; had reported the existence of the compound Tisd. No structural details, however, were given nor was there any indication of the possible existence of other binary compounds. Studies of the solubility of titanium in liquid cadmium2 led to the discovery of both TiCd and Tisd. The solid phase in equilibrium with saturated solutions of titanium in liquid cadmium at temperatures below 620°C is TiCd, whereas TizCd is the equilibrium solid phase above 620°C. Both thermal analysis and X-ray studies show that a peritectic reaction between the y phase (~isd) and cadmium to form the 6 phase (Ti Cd) occurs at 620°C. X-ray diffraction powder photographs of material isolated from the ingots used in the solubility measurements as well as material prepared by a direct heat of the appropriate stoichiometric amounts of titanium and cadmium can be indexed on the basis of a tetragonal unit cell with a = 2.904 ± 0.002A, co = 8.954 * 0.004A, c/a = 3.083. No variation of lattice parameters indicative of a range of composition is evident. With four atoms in the unit cell the calculated density of the intermetallic is 7.05 g per cm3; the observed value is 7.07 g per cm3. The TiCd lattice is primitive as indicated by the fact that there are no systematic absences among hkl reflections. The absence of all hko reflections for which h + k = 2n + 1 is also evident. This systematic absence indicates the following two space groups, C\h — P4/n and D&~4/nmm; both groups, however, have the same two- and four-fold positions. Stoichiometry, symmetry and space group indicate two likely structure types. They are the PbO-litharge3 (B10) type and the Ti CU (B11) type. Spatial considerations favor the B11 structure with atoms placed in the following positions: 2Ti (c) 0, 1/2, Z; l/2, 0, Z 2Cd(c) 0, 1/2, Z; 1/2, 0, Z The TiCd structure may be summarily described as a layered structure in which double cadmium layers alternate with double titanium layers along the c-axis. The best agreement between calculated and observed intensities is obtained for the values ZTi = 0.608 and ZCd = 0.130. Calculated and observed powder intensities as well as other pertinent powder data are recorded in Table I. Interatomic distances for the proposed structure are recorded in Table II and are to be compared with the distances of closest approach for titanium and cad-

Jan 1, 1962