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By John W. Vanderwilt

THE fluorescence of scheelite has been an important aid in recent years in the discovery and development of scheelite deposits. The use of fluorescence of synthetic compounds in industry, particularly in advertising, also has expanded greatly during the past decade. As a result, a number of new and convenient units for producing ultraviolet energy have become available, which have led to a greater application of fluorescence in the study of minerals. Studies have shown that the fluorescent color of a mineral may vary: (I) with the kind and quantity of trace elements, and (2) with the particular wave length of ultraviolet energy used. The wave length is dependent first on the type of generating equipment used, and finally on the filter employed to remove the visible light that may be present. A number of so-called ultraviolet lamps are listed and described, together with suitable filters known to be available. Scheelite fluoresces brilliantly with wave lengths of 2200 to about 3000Å., but not with longer wave lengths. The most convenient and efficient sources of ultraviolet for scheelite fluorescence- are portable and laboratory units designed particularly for use with scheelite. So-called ultraviolet light globes of the photo-flood type emit wave lengths too long to cause scheelite to fluoresce. Attention is called to the minerals that fluoresce in a manner similar to scheelite, which necessitates a check test by means of characteristic physical properties. Chemical tests are the final authority both for identity and content of tungsten in scheelite ore.

Jan 1, 1946

By T. S. Lovering

Geochemical prospecting extends the age-old method of searching out lodes with a gold pan and rationalizes the prospector's hunch that certain plants are associated with ore. It uses sensitive but cheap and rapid analytical methods to find the diagnostic chemical variations related to hidden mineral deposits. Exploration geologists can gain tremendous assistance from this new tool, although its optimum use is not simple. To bring out the geochemical pattern that reveals the presence of a hidden ore deposit with a minimum number of samples requires a combination of shrewdness, chemical knowledge, and exploration geology. The use of sensitive analytical methods for prospecting had its start in the 1930's in northern Europe, where Scandinavian and Russian geologists had some success in these early efforts. Very little geochemical prospecting was carried on in the United States at this time, and no sustained interest was manifest until the close of World War II, when geochemical investigations were started by the Mineral Deposits Branch of the U. S. Geological Survey. The purpose of these investigations was to apply geochemical principles and techniques to surface exploration for mineral deposits. Both the research on analytical methods and the routine trace analyses for field investigations were at first conducted by a single group, but it later became apparent that the trace analyses could be done by men of less experience than that required for successful research on methods. For the past several years there have been two groups of chemists, and although their functions overlap, three of the chemists are chiefly concerned with research, while four to six other men make the trace analyses for field projects.

Oct 1, 1955

By R. E. Gilmore

This paper is a revision of a former paper published in mimeograph form by both the Canadian and American coal classification committees, and is now presented for the purpose of acquainting those interested with the present status of coal classification in Canada. The classification employed for "Customs purposes" is detailed, and the classification schemes from which the customs classification was derived are reviewed and discussed. The activities of the Canadian coal classification committee, namely, the Associate Committee of Coal Classification and Analysis of the National Research Council, is also reviewed. Reserves, Production and Uses of Canadian Coals The total coal resources of North America are estimated to be 69 per cent. of those of the world, and of this portion, the distribution is 52 per cent. for the United States and 17 per cent. for Canada. Accordingly, Canadian coal resources amount to approximately one-third of those of the United States, and one-sixth of those of the world. As for the geographical distribution, the bulk of the known coal deposits are in the extreme eastern and western portions of the country. Employing the usual, more or less loosely defined, designations for the different classes and subclasses of coal, the distribution of the Canadian coal resources, according to provinces, is as follows: Maritime Provinces: Nova Scotia and New Brunswick Bituminous and semibitu- minous coals. Ontario (northern part).............................Lignite. Saskatchewan, (and Manitoba)....................... Lignite. Alberta and British Columbia........................ Lignites, subbituminous, all kinds of bituminous, semibituminous and semianthracite coals. Of the total reserves, roughly 92.5 per cent. is credited to the noncok-ing lower rank subbituninous and lignite groups, the bulk of which are

Jan 1, 1930

By Oscar M. Wicken

Industrial minerals - being the basic materials for much of the industrial activity in the world -suffer or gain in the market place with changes in that activity. The period 1970 and early 1971 has been one of little growth in many of the mineral-consuming industries, particularly those associated with building and construction. Consequently, the production of many commodities revealed little or no increase above 1969 levels. The pick-up of construction activity in the last half of 1971, however, is expected to be at an intensity which will result in an over-all good year; for example, cement shipments may, establish a record. Some industrial minerals products that bucked downward trends were those allied with the agricultural industry. Phosphate rock shipments increased, particularly from Florida which contributes over 400/c of the phosphate rock in the western world. Potash had higher sales and production for the third straight year, which means that inventories are being eased. The catch-all term of ecology is an oft-mentioned theme among industrial minerals suppliers. Specifically, the need for control of dust emissions is adding a heavy capital investment burden to many of the producers; such a burden, in fact, that plants have had to cease operations because the cost of dust collection equipment could not be born. As an order-of-magnitude estimate, dust collection equipment for cement plants can run $2-3 million for a single plant; some estimates are that the total cost of dust collection equipment in a new plant can be approximately 20% of total investment. All minerals processers have dust control expense of greater or lesser proportion.

Jan 1, 1972

By Elizabeth L. Robinson

INTRODUCTION The financial structure of the mining industry has changed strikingly over the last thirty years. The changes that have taken place in the last ten years include both the acceleration of adverse trends in familiar balance sheet numbers and ratios, and the subtle but extensive increase in the complexity and diversity of funding sources, both on and off the balance sheet. The objectives of this paper are: 1. to briefly trace the evolution of trends in the mining industry's financial structure; 2. to focus in more detail on changes in the last decade; and 3. to analyze those trends both within the framework of capital structure theory, and in the context of changes in business and economic conditions. This survey focuses primarily on the mining companies listed on the major U.S. stock exchanges, since financial data for these firms are readily available. The producers of minerals are a diverse lot, however, and the quantitative data on "the mineral industry" as characterized in this survey fails to encompass the financial arrangements for the bulk of production worldwide, whether owned by governments or private-sector enterprises. Even large portions of the U.S. minerals industry - subsidiaries of still larger firms, medium-sized privately-held companies, and the small miners - were not included in the quantitative part of the analysis. THE EVOLUTION OF THE INDUSTRY'S FINANCIAL STRUCTURE In the aftermath of the business failures of the Great Depression, most borrowers and lenders considered minimal debt on the balance sheet the soundest policy. By the 1950's, however, a body of literature was developing which demonstrated that the use of leverage could improve the value of the firm, given a corporate tax structure which allows interest, but not dividends, to be deducted from income. Optimal Capital Structure The objective of undertaking a new project is to improve the wealth of the current owners of the firm. If internally-generated funds are insufficient to allow growth at the desired rate, the company can raise funds either by issuing new equity, or by incurring debt. The most attractive source is the one which will provide the funds for the lowest cost. Both stockholders and lenders expect to receive compensation for use of their funds at a rate which reflects two things: (1) the return they could earn in alternative investments, and (2) the riskiness of the projected return. Factors which increase business risk include the variability of demand, sales prices and input prices, and "operating leverage", or the proportion of fixed to variable costs. In addition, from the investors' point of view, the use of financial leverage concentrates risk onto the shareholders, because lenders enjoy a prior claim in the event of bankruptcy. So although financial leverage can increase a project's expected rate of return, and therefore, presumably, earnings per share, too much debt will be perceived as uncomfortably risky by equity investors, and have a negative effect on stock prices. In theory, then, there should be an optimal level of debt which the firm's managers should seek to obtain in its financial structure. The desirable proportion of debt should in general be lower for a firm with a higher inherent business risk. In addition to their own judgement, financial managers are sensitive to the attitudes of lenders, rating agencies, and investment bankers in setting financial targets (Scott and Johnson). In practice, financial structure will also depend upon the company's growth rate and level of profitability, and conditions in the capital markets at a given time.

Jan 1, 1985

By A. E. Dwight, P. A. Beck

A search was made for ordered phases of AB3 composition in various combinations of Ti- and V-group elements with CO-and Ni-group elements. Three new TiNi3-type phases ZrPd3, HfPd3, and HfPt3 were found. In addition, twelve new Cu3Au-type phases TiRh3, Tilr3, ZrRh3, Zrlr3, HfRh3, Hflr3, VRh3, VIr3, CbRh3, Cblr3, TaRh3, and TaIr3 were also found. The lattice contraction for all three structures considered increases with increasing relative size of the A atom, suggesting that it is mostly the A atom that cont~acts. It was noted that, for the same radius ratio the lattice contraction is larger when the A atom is Ti than if it is Cb OY Ta. It is well known that elements or disordered solid solutions, which have structures with spherical close-packing, may be described in terms of various stacking schemes of close-packed layers. Stacking of the type abab corresponds to the hexagonal close-packed structure, and stacking of the type abcabc corresponds to the face-centered-cubic structure. In binary alloys of the first, second, and third long period transition elements various AB3 phases occur with close-packed ordered structures. It was observed that these ordered structures also may be described by suitable stacking of close-packed ordered layers, Fig. 1, as first shown by Laves and Wallbaum for TiNi3.' It is clear that the units of translation in such a close-packed layer consist of four atoms, one of which (black circle) is atom A and the three others (empty circles) are atoms B. Because of the alternation of A and B atoms in every second row of each layer, the unit-cell dimension in the layer is equal to the sum of the diameters of atoms A and B: a0 = 2(rA + rB). Stacking of such layers in the sequence abab results in a hexagonal close-packed structure of the MgCd, type. The unit-cell dimension in the basal plane is approximately double of that for the disordered hexagonal close-packed structure, but in the direction of the hexagonal axis it is about the same, so that 2co/uo = 1.63 in case of spherical close-packing. Ordered hexagonal close-packed structures of this type were found to occur in MoCo3,2 WCo3,, and UPt, .4 When the ordered layers shown in Fig. 1 are stacked according to the scheme abcabc, the resulting ordered structure is of the AuCu, type (cubic). Structures of this type were found to occur in TiPt3,5 CrPt,,' CrIr,,' and URu, .4 Finally, the stacking scheme abacabac of the same ordered layers results in a hexagonal close-packed structure of the TiNi3 type.' In this case, the unit-cell dimension is doubled not only in the basal plane, but also in the direction of the hexagonal axis, so that co/ao = 1.63. Structures of this type were found to occur also in TiPd3,5 ZrPt,," and UPd,.4

Jan 1, 1960

By J. O. Lewis

The operation of gas-condensate fields is comparatively new and involves physical principles with which the industry was not prcviously familiar. It has been necessary to devise methods for testing gas-condensate wells and to correlate laboratory and field data. In this paper new methods are advanced for interpreting well G.P.M.† tests whereby dilution by dry gas can be estimated and information supplied on revaporization of condensates by dry gas. Inaccuracies in well test data are discussed. Changes in flow rates can cause changes in the G.P.M. of the effluent and it may take some time for a well to become stabilized after an important change in flow rate. Retrograde tests as usually conducted cannot be directly compared with field G.P.M. data, because the retrograde tests usually include solution gas in the condensates, which are reported On the cumulative basis whereas field data (G.P.M.) usually report pentaneS PlUS on a rate or instantaneous basis. Introduction Though long known to physicists, the phenomena Of retrograde condensation became known to the oil and gas industry Only in recent years, when deeper drilling disclosed that the behavior of vapors under changing pressures was different in high-pressure reservoirs than under the low-pressure operations with which the industry was familiar. These deep, high-pressure reservoirs in which condensation and vaporization behaved inversely to the accustomed manner became known as "gas-distillate," or preferably "gas-condensate" fields. Partly to prevent precipitation and retention of liquids in the reservoir, but still more to prevent the waste of residue gas, the operation known as "recycling," or preferably "cycling," was instituted, in which the residue gas is reinjected into the reservoir, thus maintaining pressure and driving the wet gas to the producing wells. For lack of field experience to serve as a guide, the industry had to assume that theory and laboratory experiments could accurately forecast retrograde behaviors in operating these gas-condensate fields, but it is obvious that these assumptions should be checked at the first opportunities against actual field experience. To make such checks, it is necessary to accumulate a large quantity of reliable field data, but experience has shown that it is difficult to obtain reliable field data and that the laboratory data as usually presented are not in directly comparable form. The problems of correlation involve the complex phase behavior on the one hand, and a knowledge of field data and a visualization of underground conditions on the other hand. This paper is an approach from field experience, The purposes of this article are to discuss the sources of uncertainty in the data and to present methods of analyzing, interpreting and correlating laboratory and field data. Data mostly from lower Gulf Coast fields are presented, from which some conclusions can be derived, but better data from more sources than those available to the writer will be required before satisfactory answers to many questions can be obtained. This paper is presented to stimulate the analysis and publication of data from other fields, the reexamination of field and laboratory methods, and the taking of more complete and reliable field tests. For these purposes, the writer presents some speculations that otherwise would not be appropriate.

Jan 1, 1947

By J. O. Lewis

The operation of gas-condensate fields is comparatively new and involves physical principles with which the industry was not prcviously familiar. It has been necessary to devise methods for testing gas-condensate wells and to correlate laboratory and field data. In this paper new methods are advanced for interpreting well G.P.M.† tests whereby dilution by dry gas can be estimated and information supplied on revaporization of condensates by dry gas. Inaccuracies in well test data are discussed. Changes in flow rates can cause changes in the G.P.M. of the effluent and it may take some time for a well to become stabilized after an important change in flow rate. Retrograde tests as usually conducted cannot be directly compared with field G.P.M. data, because the retrograde tests usually include solution gas in the condensates, which are reported On the cumulative basis whereas field data (G.P.M.) usually report pentaneS PlUS on a rate or instantaneous basis. Introduction Though long known to physicists, the phenomena Of retrograde condensation became known to the oil and gas industry Only in recent years, when deeper drilling disclosed that the behavior of vapors under changing pressures was different in high-pressure reservoirs than under the low-pressure operations with which the industry was familiar. These deep, high-pressure reservoirs in which condensation and vaporization behaved inversely to the accustomed manner became known as "gas-distillate," or preferably "gas-condensate" fields. Partly to prevent precipitation and retention of liquids in the reservoir, but still more to prevent the waste of residue gas, the operation known as "recycling," or preferably "cycling," was instituted, in which the residue gas is reinjected into the reservoir, thus maintaining pressure and driving the wet gas to the producing wells. For lack of field experience to serve as a guide, the industry had to assume that theory and laboratory experiments could accurately forecast retrograde behaviors in operating these gas-condensate fields, but it is obvious that these assumptions should be checked at the first opportunities against actual field experience. To make such checks, it is necessary to accumulate a large quantity of reliable field data, but experience has shown that it is difficult to obtain reliable field data and that the laboratory data as usually presented are not in directly comparable form. The problems of correlation involve the complex phase behavior on the one hand, and a knowledge of field data and a visualization of underground conditions on the other hand. This paper is an approach from field experience, The purposes of this article are to discuss the sources of uncertainty in the data and to present methods of analyzing, interpreting and correlating laboratory and field data. Data mostly from lower Gulf Coast fields are presented, from which some conclusions can be derived, but better data from more sources than those available to the writer will be required before satisfactory answers to many questions can be obtained. This paper is presented to stimulate the analysis and publication of data from other fields, the reexamination of field and laboratory methods, and the taking of more complete and reliable field tests. For these purposes, the writer presents some speculations that otherwise would not be appropriate.

Jan 1, 1947

By Richard H. Olson

"Rarely in our technological society does the discovery of a new class of inorganic materials result in such a wide scientific interest and kaleidoscopic development of applications as has happened with the zeolite molecular sieves." That opening sentence in a landmark volume on zeolite molecular sieves by D. W. Breck (1974), is, if anything, an understatement. Zeolites were recognized as a new group of minerals in the 1750s, but it was not until 1930 that the first analysis of the crystal structure of a zeolite mineral was made. In the late 1940s research workers at Union Carbide Corp. began a program of zeolite synthesis and study which has resulted in one of the major research achievements of all time. Naturally, with the vast research and development efforts devoted to the synthetic molecular sieves, Union Carbide became concerned in the mid-1950s about its position should minable deposits of natural analogues be discovered. Zeolite minerals have diverse origins, and even a brief discussion of these is beyond the scope of this paper. The early work on zeolites was confined to igneous rock occurrences (e.g., amygdules and veins) which were formed by "space-filling;" these crystals tend to be euhedral, thereby rendering them appealing to both mineralogists and collectors. During the first year or so of Union Carbide's exploration (which began in mid-1957) attention was devoted solely to such igneous, occurrences. A landmark paper by Bramlette and Posnjak (1933) heralded the potential significance of the occurrence of zeolite minerals as alteration products of vitric ash and similar materials. In the summer of 1958, full attention was directed by Union Carbide to the search for deposits of this type in the western United States. Since then, such exploration has been continuous by both commercial firms and private parties. The future economic potential for natural zeolite deposits seems to be restricted to those of the "open-and-closed system" types as described by Sheppard (this chapter). Therefore, this and the following discussions will concentrate upon these types; the other types of zeolites in sedimentary rocks (e.g., deep-sea sediments, burial metamorphic, and hydrothermal) will be, for the most part, ignored. Despite the relative cheapness of natural zeolite deposits as compared with the cost of synthetic molecular sieves, there has been minimal development of zeolite mining in the US over the past 25 years or so. Mumpton (this chapter) discusses the present commercial utilization of natural zeolites and their future potential in detail, but perhaps the following will serve as useful background. In the early days of synthetic molecular sieve research and production, the efforts were concentrated largely upon such high-value applications as physical separation of components in a stream (based upon molecular size and geometry) and in catalysis. Due to a number of reasons (some of which are difficult for an outsider to understand), natural zeolite ores (beneficiated or not) have not made substantial inroads upon the use of the higher-priced synthetic molecular sieves for the foregoing applications, but this is not to say that such a condition will exist forever. Furthermore, in view of the many other uses which are now known, or which loom in the future, the competitive position of the natural zeolites vs. the more expensive

Jan 1, 1983

By Richard H. Hopkins, R. W. Kraft

A new technique facilitating the rapid determination of the three-dimensional morphology of phases suspended in an opaque matrix is described. The vapidity of the technique is based upon continuous cinephotomicrographic recording of specimen microstructure as the specimen surface is removed under controlled conditions in an electrolytic cell. The advantages of the technique for determining spatial morphologies in opaque materials are illustrated by application of this method to the study of the configuration of faults in a specimen of directionally solidified CuAl2-Al eutectic alloy. A spatial model of the eutectic fault network deduced in this manner has substantiated the facts that faults in this alloy tend to lie parallel to one another in a direction close to that of the specimen growth axis and that the majority of faults tend to bridge lamellae rather than run parallel to them as growth proceeds. For the specimen studied fault density decreased as growth proceeded. ALTHOUGH metallographic observation is a powerful tool for investigating the correlation between structure and properties in metallic alloys, ordinary metallographic methods suffer the fundamental limitation that any conclusions concerning the three-dimensional structure of these opaque materials must rely upon inference from two-dimensional microsections. For this reason it is frequently impossible to make valid judgments regarding the true spatial distribution of the micro-constituents in specimens under investigation. Several techniques have been devised to circumvent the basic limitation of planar microsec-tioning and employed with varying success. These include construction of three-dimensional models of alloy microstructure from sequences of photomicrographs,1-3 quantitative deduction of spatial features based upon statistical studies of data from random and/or selected plane microsections,4-6 and selective dissolution of one phase in a two-phase alloy to reveal the topography of the phase remaining.' However these techniques also have certain obvious disadvantages. Construction of three-dimensional models is a very time-con- suming procedure due to the tedious polish-etch-photograph cycle needed to obtain the necessary photomicrographs to portray the spatial microstructure. Statistical methods by their very nature give only average values of the quantities being studied and cannot therefore give a detailed physical picture of the microstructure to be observed. Finally, the technique of selective dissolution is only applicable in systems where the phases are of vastly different chemical reactivity; it is of little use in the study of single-phase alloys. Since the determination of the three-dimensional structure of opaque materials is hindered by two facts—the materials are opaque to radiation in the visible spectrum and construction of spatial models of microstructure is quite laborious—two solutions to the problem suggest themselves: 1) use radiation of energy great enough to render the alloy transparent, i.e., some microradio-graphic method, or, 2) devise a rapid means to section and record alloy microstructure. Stereomicroradiography has indeed been used to study internal arrangements of phases in several materials8,9 but the method, in general, is limited to very thin specimens (due to X-ray absorption) and simple microstructures. It would seem then that development of a rapid, simple, and generally applicable technique for studying the details of alloy microstructures in three dimensions can best be undertaken by following the second approach above. Using this idea a new technique for rapid evaluation of spatial microstructures was developed based upon cinephotomicrographic recording of the micro-structure of a specimen undergoing controlled electrolytic dissolution. It was further felt that application of this technique to the careful study of the spatial configuration of faults in a CuAl2-Al eutectic alloy would yield information that could be correlated with the extensive data3,6,10-12 already compiled concerning the solidification and crystallography of this eutectic. The practicality and usefulness of similar methods for studying three-dimensional features in alloys has recently been illustrated by the study of dislocation loops in zinc13 and spheroidized structure in steel.14

Jan 1, 1965

By C. T. Malcomson

An elaborate series of experiments has been conducted during the past three years at Irvington, N. J., which has resulted in the perfection of a process for the manufacture of smokeless fuel from high-volatile coals, and for the recovery and refinement of the coal-tar products derived therefrom. These experiments have been financed by Messrs. Blair & Co., of New York, and were conducted under the direction of Charles H. Smith, a member of this Institute, and the inventor of the process. The low-temperature distillation of coal has interested investigators for many years. Sporadic attempts have been made to solve the mechanical problems, but until the Smith process was developed, they were not carried to conclusions of economic value. The present coal shortage and the increasing demand for smokeless fuels make this subject one of timely interest. DescRiption of Plant The following equipment was installed and operated during the experimental period: Four horizontal and two vertical units of commercial size for the low-temperature distillation of the coal; two vertical, two horizontal, and two inclined benches for distillation of the briquets at medium and higher temperatures; presses and auxiliary equipment necessary for making briquets; and a complete byproduct recovery and tar-refining plant. This commercial equipment is provided with gas and electric meters, pyrometers and other apparatus for recording accurately the results of all experiments. There is, in addition to the commercial equipment, a complete chemical laboratory with distillation and recovery apparatus, including facilities far refining and cracking the tar and measuring the yields and calorific value of the gas. This apparatus makes possible a study on a small scale, of the various problems involved in the process. Description of Process Mr. Smith's experiments have resulted in the production on a commercial scale of: 1. A fuel, called Carbocoal, which, for convenience in handling, is prepared in briquet form.

Jan 1, 1920

By R. E. Goodman, M. A. Mahtab

The, state of stress around a vertical wellbore in rock following nonlinear stress-strain laws is examined by means of finite element analysis. The wellbore, is considered an axisymmetrier body with axisymmetric loading. The initial vertcal and borizontal stresses are "locked" in the rock elements around the wellbore and a new state of stress is generated by the displacements which occur around the borehole. A point-uise variation of the elastic moduli is made on the basis of the new stress state and the triaxial data. The initial stresses tire now reintroduced along with tile changed moduli and original boundary constraints. This procedure is repeatrd until convergent stresses are reached. The effect of nonlinearity on streases is examined for a 6,000-ft wellbore in a scbistose gnezss and Berea sandstone using results of laborratory triaxial compression tests. The results sbou that the effect is restrited to one well radius from the bottom periphery of the bole. Beyond a distance of one-quarter radius, the elfect of nonlinearity on stresscs IS almost always less than percent for the cases conszdered, The consideration of a static pressure inside the well does not magnify the effect of monlinearity on borehole stresscs. INTRODUCTION The terms " wellbore" and "borehole" here designate cylindrical openings in the ground with vertical axis and a circular cross-section. A knowledge of the stress redistribution that occurs on excavating a wellbore is important in understanding (1) the behavior of the lined or unlined hole, (2) hydraulic fracture response, and (3) the effect of stress redistribution on drillability; also it is important in predicting initial stresses in the virgin ground, and in analyzing the response of measuring instruments placed in the borehole. Our knowledge of the state of stress around a wellbore has been restricted to homogeneous, isotropic, elastic material and derives chiefly from the analysis by Miles and Toppingl and the photoelastic work of Galle and Wilhoit2 and Word and Wilhoit.3 In this investigation the state of stress is examined for a nonlinear elastic material by means of finite element analysis. Many rocks possess stress-strain curves that depart notably from straight lines in their initial or final portions. While the literature contains abundant stress-strain data from triaxial tests (axisymmetric loading) on cylindrical rock specimens, there is little information on rock deformability under nonaxisymmetric loading conditions such as occur at each point around the bottom of a wellbore. Although there is some knowledge of the effect of intermediate principal stress on rock strength, there is virtually nothing known about its effect on rock deformability; therefore, we have assumed here that the effect of intermediate principal stress can be ignored. A schistose gneiss4 and Berea sandstone5 were selected as representative rocks for this analysis. The traditional graphs of deviator stress (ol -o3) vs axial strain were reworked to give the tangent modulus as a function of the deviator stress for varying values of the minor principal stress. The result is a nesting family of skewed, bell-shaped curves for tile gneiss (Fig. 1A) and the sandstone (Fig. 2A). A similar replotting of the lateral strain data defines the variation of Poisson's ratio (v) with the deviator stress and confining pressure. These curves, shown in Fig. 1B for the gneiss and in Fig. 2B for the sandstone, are not so well ordered as the tangent modulus curves. However, all of these display an increase of v with deviator stress application, but the rate of increase diminishes with confinement. The ET and v curves for the two rock types are tabulated in Tables 1A and 1A for use in a digital computer so that material properties corresponding to a given state of stress can be assigned by interpolation. STATEMENT OF THE PROBLEM Given a state of stress in the ground prior to drilling a hole (initial stresses), we assume that

Jan 1, 1969

By J. Brian Eby

Contact metamorphism of coals is any physical or chemical change in the character of a coal directly attributable to heat of surface or intrusive igneous rocks. Coal beds so affected are found in the United States, England, Alaska, Mexico, New Zealand, Greenland, and other countries. Particularly in the United States, there is a wide occurrence of contact altered coals; conspicuous examples are found in Colorado, Utah, New Mexico, Illinois, and North Carolina. During a recent examination of coal beds on Yampa River, in northwestern Colorado, the author had an opportunity to make some detailed observations on the contact metamorphism of coals. In this field, coals over an area of 20 sq. mi. have been affected by dikes, sheets, and sills;' samples of the coals were systematically collected and analyzed,2 with the view of obtaining more specific data on the character of these alterations. The investigation was threefold in purpose: to secure information on the lateral effects of a dike cutting a coal bed, on the range in vertical effects on coal beds overlying sheets or sills, and on the range in the vertical effects on coal beds underlying sheets and sills. Favorable field conditions, such as fresh outcrops and newly dug prospects, made possible many of the field observations and collections. The coals studied in this field belong chiefly to the Mesaverde and 11Laramie" formations. The Mesaverde coals, on the average, are blocky low-rank bituminous coals; the "Laramie" coals, which are considerably younger, are of subbituminous rank. The coals of both formations, in the northeastern part of the Yampa field, have been greatly affected by basalt intrusives, yielding all variations of carbonized coal from natural coke to the unaffected material. The igneous rock that directly affects the coals is a fine-grained olivine basalt that is intruded, in sheets up to 200 ft. thick, into the coal-bearing

Jan 1, 1925

By J. Brian Eby

CONTACT metamorphism of coals is any physical or chemical change in the character of a coal directly attributable to heat of surface or intrusive igneous rocks. Coal beds so affected are found in the United States, England, Alaska, Mexico, New Zealand, Greenland, and other countries. Particularly in the United States, there is a wide occurrence of contact altered coals; conspicuous examples are found in Colorado, Utah, New Mexico, Illinois, and North Carolina. During a recent examination of coal beds on Yampa River, in north-western Colorado, the author had an opportunity to make some detailed observations on the contact metamorphism of coals. In this field, coals over an area of 20 sq. mi. have been affected by dikes, sheets, and sills;1 samples of the coals were systematically collected and analyzed,2 with the view of obtaining more specific data on the character of these alterations. The investigation was threefold in purpose: to secure information on the lateral effects of a dike cutting a coal bed, on the range in vertical effects on coal beds overlying sheets or sills, and on the range in the vertical effects on coal beds underlying sheets and sills. Favorable field conditions, such as fresh outcrops and newly dug prospects, made possible many of the field observations and collections. The coals studied in this field belong chiefly to the Mesaverde and Laramie formations. The Mesaverde coals, on the average, are blocky low-rank bituminous coals; the "Laramie coals," which are considerably younger, are of subbituminous rank. The coals of both formations, in the northeastern part of the Yampa field, have been greatly affected by basalt intrusives, yielding all variations of carbonized coal from natural coke to the unaffected material.

Jan 1, 1925

The following is an incomplete list of members and guests who called at Institute headquarters during the period Nov. 10, 1918 to Dec. 10, 1918. Arthur C. Adair, Camp Meade, Md. L. S. Mitchell, Montreal, Canada. Arthur K. Adams, Camp Humphreys, Va. T. E. Mitchell, San Francisco, Cal. Toner Antisell, Chevy Chase, Md. H. Mortimer-Lamb, Montreal, Canada. V. W. Aubel, New Castle, Pa. Edmund Newton, A. C. Black, El Paso, Tex. Paul T. Norton, Jr., Columbus Ohio. 0. F. Brinton, Baxter Spgs., Kans. Elmer W. Pehrson, San José, Cal. C. S. Corbett, Minneapolis, Minn. Joseph E. Pogue, Washington, D. C. W. M. Corse, Mansfield, Ohio. T. C. Roberts, E. Orange, N. J. G. C. Crossley, Toms River, N. J. D. R. Semmes, Richmond, Va. H. S. Emlaw, Grand Haven, Mich. H. L. Slosson, Jr., San Francisco, Cal. Rudolph Emmel, Boston, Mass. W. H. Staver, S. G. Garrett, U. S. N. R. F. A. L. Sweetser, Boston, Mass. Lt. Francis Geib, Denver, Colo. Lt. H. B. Taylor, Kansas City, Mo. Wm. E. Hubbard, Wichita Falls, Tex. Kirby Thomas, New York. Arthur Iddings, Wichita Falls, Tex. Benj. F. Tibby, Salt Lake City, U. Zay Jeffries, Cleveland, Ohio. J. L. Towne, Whitepine, Colo. S. J. Kidder, Mogollon, N. M. Chas. W. Tubby, St. Paul, Minn. Lt.-Col. W. H. Lanagan (Engrs.). A. G. Waite, Brookline, Mass. Major W. F. Lewis (Engrs.). Timothy D. Walsh, Denver, Colo. 0. M. Lewyn, Thomas Warner, Phoenix, Ariz. A. McClintock, DeKalb June., N. Y. J. P. B. Webster, London, England. Major Donald G. Miller, N. M. E. W. Westervelt, Los Angeles, Cal. C. E. LeN. Arnold, formerly with the Inspiration Cons. Copper Co. at Inspiration, Ariz., has accepted a position with the Consolidated Arizona Smelting Co. at Mayer, Ariz.

Jan 1, 1919

By Paul M. Tyler

YEAR after year, the kaolin industry of the United States has been setting new production records and making better products. High-grade paper, pottery, and rubber clays are produced in this country mostly in the South. Georgia alone contributes over 70 pct and South Carolina almost 20 pct of the total domestic output. Residual kaolin is mined in North Carolina, highly plastic but naturally sandy Tertiary (Eocene) potting clays are worked in north central Florida, and good white clays are produced in several other states, but the main sources of kaolin or china clay have been numerous deposits in the Tuscaloosa (Upper Cretaceous) formation. This formation of generally sandy sediments is called the Middendorf member in older geologic reports and corresponds in age with some of the New Jersey clays. As shown in fig. 1, it crops out almost continuously in a generally southwesterly direction across South Carolina and Georgia and into Alabama. Clay is mined from this formation in all three states but the principal producing centers lie within about 10 miles of a straight line drawn between Aiken, S. C., and a point about 10 miles south of Macon, Ga. The white kaolins of the South were recognized and used prior to the Civil War but suitable treatment processes were not introduced until World War I when imports, chiefly from England, were curtailed. Although imports of high-grade clays were resumed after 1918, the domestic industry managed to treble its prewar production record during the early 1920's and has continued to grow. Whereas the 1909 to 1913 average total production in the United States was only 132,104 short tons valued at $705,352 f.o.b. mines, the output in 1948 was 1,568,848 tons worth $19,756,738.

Jan 6, 1950

By Ancel St. John

AT THE New York meeting of the Institute of Metals Division in February, 1927, Jeffries and Tarasov presented a paper on Tungsten and Thoria,1 in which the experimental facts were interpreted in accordance with the prevailing point of view that the thorium is present as the oxide, thoria. In discussing that paper the writer of this article stated that his own investigations, which had been unavailable to Messrs. Jeffries and Tarasov, showed that the so-called "thoriated" tungsten filament failed to disclose any sign of the oxide when subjected to X-ray diffraction analysis, but did give plenty of evidence of the presence of metallic thorium and, in certain cases, of a material believed to be an alloy of tungsten in thorium. Since these results were completely at variance with the results reported in the paper under discussion and with other papers which had preceded it from time to time in the past, it was felt that further discussion should be withheld until the new evidence could be presented adequately. Arrangements were therefore made to present that evidence at this meeting. MATERIAL EXAMINED The material examined was high-emission filament such as is used in radio tubes, supposed to contain about 0.75 per cent. thoria. The actual analysis was not stated. SCOPE OF THE INVESTIGATION The investigation was undertaken because of a feeling that the thorium present in filamentary material of this type exists as metallic thorium or as an alloy of thorium and tungsten and not as the oxide. Attention was therefore directed to determining: 1. The minimum amount of thoria detectible in a mechanical mixture of thoria powder and finely divided tungsten. 2. The amount of thoria detectible in the filament. 3. The condition of any thorium present in other form than as thoria. 4. The amount of thorium dissolved in the tungsten.

Jan 1, 1928

By Ancel St. John

At the New York meeting of the Institute of Metals Division in February, 1927, Jeffries and Tarasov presented a paper on Tungsten and Thoria,' in which the experimental facts were interpreted in accordance with the prevailing point of view that the thorium is present as the oxide, thoria. In discussing that paper the writer of this article stated that his own investigations, which had been unavailable to Messrs. Jeffries and Tarasov, showed that the so-called "thoriated" tungsten filament failed to disclose any sign of the oxide when subjected to X-ray diffraction analysis, but did give plenty of evidence of the presence of metallic thorium and, in certain cases, of a material believed to be an alloy of tungsten in thorium. Since these results were completely at variance with the results reported in the paper under discussion and with other papcrs which had preceded it from time to time in the past, it was felt that further discussion should be withheld until the new evidence could be presented adequately. Arrangc-mcnts were therefore made to present that evidence at this meeting. Material Examined The material exalllined was high-ernission filament such as is used in radio tubes, supposed to contain about 0.75 per cent. thoria. The actual analysis was not stated. Scope of the Investigation The investigation was undertaken because of a feeling that the thorium present in filamentary material of this type exists as metallic thorium or as an alloy of thorium and tungsten and not as the oxide. Attention was therefore directed to determining: 1. The minimum amount of thoria detectible in a mechanical mixture of thoria powder and finely divided tungsten. 2. The amount of t.horia detectible in the filament. 3. The condition of any thorium present in other form than as thoria. 4. The amount of thorium dissolved in the tungsten.

By A. H. Geisler

INTRODUCTION THE correlation of property changes during precipitation with structure has progressed, sometimes rapidly but other times more slowly, since the fundamental discovery of Merica, Waltenberg and Scott.1 The predominent factor that hampered the progress has been limitations imposed by the various detection methods. Refinements in X ray diffraction techniques and in metallographic methods, which have been extended by the electron microscope, have contributed new information within the last few years. These permit an extension of the theory as proposed by Mehl and fetter in 1940.2 Now that a suffcient number of alloys has been investigated to establish a general mechanism of the precipitation process, a correlation of the facts into a generally applicable theory of age-hardening is both warranted and desirable. 'I he purpose of the paper is to provide an orderly correlation of the phenomenological facts of precipitation hardening. Speculation on mechanism of hardening will be confined to that consistent with existing theories of hardening. Age-hardening accompanies the formation of a new structure, the precipitate, as provided by an alloy system in which solid solubility decreases with decreasing temperature. Upon this premise alone all such systems would be expected to include age-hardenable alloys. Alas, this is not always the case. Few attempts have been made to explain the variable degree of age-hardening among different alloys or to explain the influence of small alloying additions upon the hardening. Dispersion hardening as originally postulated3 is not adequate.* Coherency hardening-the term that will be used to distinguish the properties of a two-phase mixture in the unique and unstable transition state at which the phases are strained into precise atomic registry (continuity or coherency) in planes

Jan 1, 1948

By F. N. Rhines

DESPITE the large amount of study which has been devoted to the subject our present knowledge of the copper-oxygen system remains incomplete and unsatisfactory in many respects. This applies particu-larly to those regions in which solid metallic copper exists. The primary object of the present paper is the contribution of new information relative to the solid solubility of oxygen (or cuprous oxide) in copper at atmospheric pressure, together with certain observations in the low-pressure regions of the system. It seems appropriate also to present a brief summary of the outstanding previous work on the constitution of mixtures of copper with its lowest oxide in order to show the relation between the new facts and the system as a whole. The earliest recorded investigations of the copper-oxygen system are those of M. S. Lucas (1) § and of M. Chevillot(2) in 1819 and 1820. Lucas believed that liquid copper is capable of dissolving its oxide, but neither he nor Chevillot was able to furnish convincing proof of this property. It was not until 1866 that T. Graham° definitely established the existence of such a solubility. Nine years later W. Hampe(4) measured its extent and roughly outlined the copper-rich portion of the system. The first really precise examination of the constitutional relationship between copper and cuprous oxide, however, was that of E. Heyn(5) who in 1900 published a temperature-concentration diagram covering the range from 0 to 10 per cent of cuprous oxide at atmospheric pressure. Within these limits of composition cuprous oxide was found to dissolve in liquid copper, forming at 3.4 to 3.5 per cent a eutectic which melted at 1065° C. R. E. Slade and F. D. Farrow(6) extended these studies to mixtures of higher

Jan 1, 1934