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By C. O. Fairchild

ONE of the fundamental principles of efficiency is the use of adequate and permanent records. The rapid increase in the manufacture and use of recording pryometers is a proof of the appreciation of efficiency principles on the part of the manufacturers engaged in the various technical industries. Where recording pyrometers are not employed in an industry in which temperature measurements are necessary, one will generally find that a printed form is used upon which is written, periodically, the temperatures measured by an indicating instrument. It is no serious condemnation of the workman to state that such records are often "doctored," but it is rather a reflection upon the executive who puts such temptation in the way of a workman. One of the well-known "tricks of the trade" is to "force." a furnace so that it will be at the proper temperature during the periodic trips of the foreman or other official. Indicating instruments and recorders may be used together to great advantage. The recorder furnishes .a printed record and a check upon the operator of the furnace, and a record of value in correlating properties of the finished product with the heat treatment. The indicator should be of assistance to the operator in controlling the furnace or oven. Modern practice requires a temperature-recording instrument that is as simple as possible, rugged, reliable, and sufficiently accurate. Of these qualifications reliability is paramount, particularly in cases where the recorder is used for controlling the temperature automatically. By a reliable instrument is meant one that will run continuously with little attention and with a consistent degree of accuracy. That is, if it is in error by 5 per cent. one day, it must be in error by a like amount on any other clay, and not by 2 per cent. or 10 per cent. The earlier forms of recorders were complex and delicate, or mechanically unsatisfactory and inaccurate, and required considerable attention to keep them in operation. Within the past few years, however, the development in the manufacture of temperature recording devices has been highly satisfactory and many excellent instruments are now available. .

Jan 9, 1919

By M. King Hubbert

In 1856 Henry Darcy described in an appendix to his book, Les Fontaines Publiques de la Ville de Dijon, a series of experiments on the downward flow of water through filter sands, whereby it was established that the rate of flow is given by the equation: q= - K(h2- h2)/I1 in which q is the volume of water crossing unit area in unit time, I is the thickness of the sand, h1 and h2 the heights above a reference level of the water in manometers terminated above and below the sand, respectively, and K a factor of proportionality. This relationship, appropriately, soon became known as Darcy's law. Subsequently many separate attempts have been made to give Darcy's empirical expression a more general physical fornzulation, with the result that .so many mutually inconsistent expressions of what is purported to he Darcy's law have appeared in published literature that sight has often been lost of Darcy's own work and of its significance. In the present paper, therefore, it shall be our purpose to reinform ourselves upon what Darcy himself did, and then to determine the meaning of his results when expressed explicitly in terms of the pertinent physical variables involved. This will be done first by the empirical method used by Darcy himself, and then by direct derivation from the Navier-Stokes equation of motion of viscous fluids. We find in this manner that: q = (N4(p/p)[g - (l/p) gradPI = WE, is a physical expression for Darcy's law, which is valid for liquids generally, and for gases at pressures higher than about 20 atmospheres. Here N is a shape factor and d a characteristic length of the pore structure of the solid, p and IL are the density and viscosity of the fluid, a = (Nd2)(pip) is the volume conductivity of the system, and E = [g - (l/p) grad p] is the impelling force per unit mass acting upon the fluid. It is found also that Darcy's law is valid only for flow velocities such that the inertial forces are negligible as compared with those arising from viscosity. In general, three-dimensional space there exist two superposed physical fields: a field of force of charucteristic vector E, and a field of flow of vector q. The force field is more general than the flow field since it has values in all space capable of being occupied by the fluid. So long as the fluid density is constant or is a function of the pressure only, curl E = 0, E = - grad F where F = gz + dp/p The field of flow, independently of the force field, must satisfy the conservation of mom, leading to the equation of continuity div pq = — f ap/at , where f is the porosity, und t is the time. For steady rnotion ap/at = 0. and div pq = 0 .

Jan 1, 1957

For more than 100 years, the Republic of Chile has been one of the leading copper-producing countries of the world. Between 1877 and 1880 Chile accounted for over 50 pet of total world copper production. Today it has the world's largest known reserves of copper ore and a capability of producing over 600,000 tons per year. This capacity can and will be increased as the world demand for copper grows steadily during the remaining years of this century. The Potrerillos mine of Andes Copper Mining Co., a subsidiary of The Anaconda Co., was developed in the rugged, high Cordilleras in the early 1920's, and the townsite, concentrator, leaching plants, smelter, railroad, power and port facilities were completed so that it came into full production in 1927. Since then and until the closing o f the mine in June of last year, 1,762,192 tons o f copper were produced.

Jan 4, 1960

By A. Eilers

THE telluride of gold and silver, the " Tellurgold-silver" of Hausmann, and " Petzite" of other mineralogists, has been found in so few localities, that a late discovery of the mineral in a new locality may not be uninteresbing. So far this mineral has been found in Europe only in a few mines in Transylvania, and in Hungary; and in the United States in the Stanislaus Mine, in Calaveras County, California, in the Golden Rule Mine, Tuolumne County, California, and in a mine in Montana, the precise locality of which I have forgot, ten. The new locality referred to is at the Red Cloud Mine, Gold Hill District, Boulder County, Colorado.

By David B. Brooks

INTRODUCTION Resources are not; they become (Zimmermann 100) . The companion concepts of reserves and resources appear, one way or another, in almost all considerations of mineral supply. Yet, no other concepts in the economics of the mineral industries have occasioned so much confusion. Whereas everyone agrees that in general the terms refer to the amounts of material that-depending upon technology, market conditions, and institutions-will become available for production in the near or more distant future, the apparent agreement disappears when we come to more specific definitions or to application of the definitions. Some definitions emphasize the physical aspects of reserves and resources, while others emphasize the economic. Some treat reserves and resources as fixed quantities, while others regard them as continually varying. Some consider that reserve and resource estimates have validity only for individual deposits, while others insist that they can be measured with sufficient accuracy for regional or national planning. This confusion in concepts that lies at the very heart of mineral economics is both strange and not so strange. It is common in the social sciences to find concepts that have been adopted into scientific jargon from popular usage and given rather special meanings -at the same time that they continue to be widely used without such qualifications. Psychologists have the same trouble with personality and sociologists, with community. Nevertheless, an attempt must be made to straighten out the various meanings of reserves and resources, or at least to clarify the conditions under which different meanings are applicable, before much progress in analysis of mineral problems can be expected. That is the objective of this chapter. Throughout the chapter, an attempt has been made to provide enough references to guide the interested reader to the most pertinent works on the concepts under study. However, even in a review article, it is no longer feasible to provide a comprehensive set of citations; there are simply too many. In many instances the works cited will themselves include the bibliographies needed to complete a literature search; those that are particularly useful in this respect are so noted. Also, because of the limited availability of foreign periodicals, some important works -originating largely in Canada, France, the

Jan 1, 1976

By Benjamin L. Miller, Charles H. Breerwood

From earliest recorded times, limestone has been employed in the industrial life of peoples of all sections of the world where it exists. It is widely distributed and therefore has been available in almost every country and has been employed for a variety of purposes. Its earliest use was for buildings, since it is more easily quarried and dressed than most other kinds of rocks and so could be utilized by early inhabitants, poorly equipped with tools. The next use was in the manufacture of lime, which was employed by the ancients in mortar. These two uses of limestone are still all important, but they have been overshadowed in scores of regions by literally hundreds of new applications for raw limestone or products made from it. Anyone familiar with modern manufacturing processes can quickly call to mind many industries in which limestones are essential, and new uses are continually coming to notice. Any enumeration would probably be incomplete and soon out of date. Origin of Limestone Disregarding details and unusual types concerning which often there is insufficient evidence and considerable difference of opinion, limestones have been formed by the precipitation of calcium carbonate from solution through the action of organisms, both plants and animals, or in a limited number of instances by chemical reactions without the intervention of living forms. Some of the organisms extracted the calcareous material in order to build up hard structures, either as bony skeletons or as coverings (clams, snails, etc.), whereas others in their life functions emitted substances that resulted in the precipitation of the soluble constituents outside the organisms themselves. In some instances the organisms utilized only calcium carbonate but in some cases other compounds as well were precipitated. Various materials have been found in the hard parts of animals, and for that reason it is almost impossible to find a pure natural limestone; that is, one composed entirely of CaCO3.

Jan 1, 1938

By Charles H. Breerwood, Benjamin L. Miller

From earliest recorded times, limestone has been employed in the industrial life of peoples of all sections of the world where it exists. It is widely distributed and therefore has been available in almost every country and has been employed for a variety of purposes. Its earliest use was for buildings, since it is more easily quarried and dressed than most other kinds of rocks and so could be utilized by early inhabitants, poorly equipped with tools. The next use was in the manufacture of lime, which was employed by the ancients in mortar. These two uses of limestone are still all important, but they have been overshadowed in scores of regions by literally hundreds of new applications for raw limestone or products made from it. Anyone familiar with modern manufacturing processes can quickly call to mind many industries in which limestones are essential, and new uses are continually coming to notice. Any enumeration would probably be incomplete and soon out of date. Origin of Limestone Disregarding details and unusual types concerning which often there is insufficient evidence and considerable difference of opinion, limestones have been formed by the precipitation of calcium carbonate from solution through the action of organisms, both plants and animals, or in a limited number of instances by chemical reactions without the intervention of living forms. Some of the organisms extracted the calcareous material in order to build up hard structures, either as bony skeletons or as coverings (clams, snails, etc.), whereas others in their life functions emitted substances that resulted in the precipitation of the soluble constituents outside the organisms themselves. In some instances the organisms utilized only calcium carbonate but in some cases other compounds as well were precipitated. Various materials have been found in the hard parts of animals, and for that reason it is almost impossible to find a pure natural limestone; that is, one composed entirely of CaCO3.

Jan 1, 1938

By W. M. Weigel

LESS advances in the technology of non-metallic minerals than for several years past mark 1931, and the cause is easily found. The universal depression and decreased markets for non-metallic as well as other mineral commodities has forced the producers to cut out all unnecessary expense and reduce operating costs to a minimum in order to keep going, even on a reduced output, and to prevent insolvency. The result. has been that but 'little research has been carried on, and such as has been completed has in but few cases been put into commercial practice on account of the expense involved in new equipment and plant changes. The trend in the industry has been more economic than technologic, and the greatest effort put on market studies and sales attempts to expand markets and scrutiny of present operating 'practice leading to reduction of cost of production. This tendency has been increased by highly competitive conditions and the buyer's market which has prevailed and to the fact that price has been a greater factor than quality in placing orders. Only in cases where improvements in technology would immediately and effectively reduce costs or where in special cases there was but little competition with almost a monopoly control has actual technical development taken place.

Jan 1, 1932

By Wilhelm Rohn

IN discussing the influence of a content of gases on metals and alloys we should probably first consider the physical and chemical conditions under which these gases may be present. By a chemical analysis, such as the total extraction of gases from the liquid metal by melting in a graphite crucible in vacuo, we find only the sum of gaseous chemical elements contained in the metal in any form and no reference is made to the special form under which they have been present previously. CONDITION OF GASES IN METALS In considering. gases in metals we may first turn our attention to gases simply dissolved. Because the solubility of almost, any gas decreases suddenly at the freezing point, most of them are released during solidification, developing rise of ingots and blowholes. If only a little gas is dissolved in the molten metal the size of such blowholes may be miscroscopical, or even submicroscopical, resulting in, a certain reduction of the notched-bar impact test values. Hydrogen is believed to become less soluble as the temperature is lowered and therefore increasing quantities of this gas may be evolved during cooling between the freezing point and room temperature, leading to unsoundness of the ingot at weak spots; i.e., at the grain boundaries. This gas at the grain boundaries probably is present at high pressure and therefore impairs the mechanical properties to a degree similar to that found in the hydrogen embrittlement of copper. Usually we may trace such gases by observing rising ingots, or at least by the formation of a characteristic pattern of small grooves upon etching. Another condition of gases present within metals is that of chemical compounds, the most common being oxides and mostly present as slag inclusions of various kinds. If such oxides are insoluble in the liquid metal and emulsify with it, we find microscopical or submicroscopical slag inclusions distributed homogeneously throughout the metal and spread through the whole mass of the crystals. This special form does little harm to the mechanical properties. Some oxides are somewhat soluble

Jan 1, 1932

By H. W. McQuaid, E. W. Ehn

It is usually assumed that chemical specifications are sufficient for steel to be used for case carburizing, and if the steel analyzes within the ordinary limits specified for steel for this purpose, no difficulty traceable to the steel used should be encountered in obtaining satisfactory results in the case carburizing and hardening. Much work has been done to determine the effect of various alloying elements on the rate of carbon penetration, etc. but, to our knowledge, little if anything has been published in regard to the effeet of the quality of the steel on the final results in the hardening of case-carburized steel parts. The writers believe that the structure of the case both before and after quenching is greatly affected by the actual condition of the steel itself as made, and that for good results in the case-carburizing and hardening departments, the steel should be of the best possible quality as regards non-metallic impurities. It is the purpose of this paper to prove that the presence of excess dissolved oxides in the steel, as made in the melting furnace, affects permanently the results obtained in carburizing and hardening and that it is possible that the presence of dissolved oxide call result in total unfit-ness of low-carbon steel for case hardening purposes. When races and rolls for roller bearings are made from a low-carbon steel, case carburized and hardened, it is of primary importance that the results of this treatment be of the highest quality. It is necessary, therefore, that in the case-carburizing work each detail be rigorously checked to avoid any defects which would cause the loss of much time and material. The case carburizing with which this paper deals was done in under-fired oil furnaces. The temperature of each furnace is controlled by means of a platinum platinum-rhodium thermocouple, in connection with a potentiometer indicator and potentiometer recorder. The temperature of each furnace is registered every 15 min. by an operator, who is continually checked by the automatic recorders.

Jan 1, 1922

By H. W. McQuaid, E. W. Ehn

It is usually assumed that chemical specifications are sufficient for steel to be used for case carburizing, and if the steel analyzes within the ordinary limits specified for steel for this purpose, no difficulty traceable to the steel used should be encountered in obtaining satisfactory results in the case carburizing and hardening. Much work has been done to determine the effect of various alloying elements on the rate of carbon penetration, etc. but, to our knowledge, little if anything has been published in regard to the effeet of the quality of the steel on the final results in the hardening of case-carburized steel parts. The writers believe that the structure of the case both before and after quenching is greatly affected by the actual condition of the steel itself as made, and that for good results in the case-carburizing and hardening departments, the steel should be of the best possible quality as regards non-metallic impurities. It is the purpose of this paper to prove that the presence of excess dissolved oxides in the steel, as made in the melting furnace, affects permanently the results obtained in carburizing and hardening and that it is possible that the presence of dissolved oxide call result in total unfit-ness of low-carbon steel for case hardening purposes. When races and rolls for roller bearings are made from a low-carbon steel, case carburized and hardened, it is of primary importance that the results of this treatment be of the highest quality. It is necessary, therefore, that in the case-carburizing work each detail be rigorously checked to avoid any defects which would cause the loss of much time and material. The case carburizing with which this paper deals was done in under-fired oil furnaces. The temperature of each furnace is controlled by means of a platinum platinum-rhodium thermocouple, in connection with a potentiometer indicator and potentiometer recorder. The temperature of each furnace is registered every 15 min. by an operator, who is continually checked by the automatic recorders.

Jan 1, 1922

THERE has been a lot of talk about the shortage of engineers and we have done our share of it; but recently we heard a spot radio commercial-between broadcasts-urging high school seniors to study engineering. We think this is going too far. Engineering is an exacting profession requiring the highest personal qualifications. Publicity for the purpose of interesting capable young people in choosing courses in engineering should emphasize qualification. The opportunities for a career in a great constructive profession which is the basis of our high standard of living should be properly evaluated. Although there is a need for more engineers today, nobody knows what the employment potential is going to be four years hence. The profession may do itself a grave disservice by attempting mass recruitment in the face of an unpredictable national economy. The mining and metals industries are in a special position as fewer engineers are needed in these fields. Only 10 pct of all engineers are mining and metallurgical engineers. Today's shortage is not so much in recent graduates, but in trained practicing engineers. The shortage has served the profession to good effect because it directed the talents of engineers into more productive channels. In some areas high school graduates have been put into routine jobs such as, surveying. If there is one thing the mining profession does not want, it is an oversupply of graduates which would relegate college men to years of work and discouragement in routine jobs. The public has a clear cut picture of the legal and medical professions and thus the respect knowledge imparts. But the engineer is variously thought of as a man who pulls the throttle lever on a locomotive, tends a furnace, or builds a bridge. The term engineer is too loosely used. For instance we have heard of "crowd engineers" and "exterminating engineers." In some unions an engineer designation has been established to describe a person doing routine checking or other control job. We do not disparage these positions but they are different from the work done by the man qualified by years of experience and study. Many of these so-called engineers are not engineers at all. The engineering profession has cooperated closely on a program of recruiting high school graduates for engineering study. It should start a cooperative public relations program to enlighten the public on the accomplishments and work of engineers. This type of publicity need not be of the bombastic type. It can be educational and dignified. Radio, television, and the periodicals can be used to convey information. It is time that laymen and interested young people learn to make a distinction between the true engineer and the technician. Such a program would instruct parents and high school students and thereby interest the right type of people in the engineering profession. The Centennial of Engineering sponsored by the American Society of Civil Engineers is a step in the direction of instructive public relations. This fine start should not be allowed to remain as a one pass venture. The engineering profession as a whole should follow this exposition with a sustained, well directed effort to inform the public of the engineer's work and the possibilities it holds for a constructive career.

Jan 1, 1952

In the death of Major A. B. desaulles at South Bethlehem, Pa., on Dec. 24, 1917, the Institute lost a valued and esteemed member, one of the last few of those who, in May, 1871, at Wilkes-Barre, attended the first meeting of the Institute, in response to a call that had been issued by R. P. Rothwell, Eckley B. Coxe, and Martin Coryell. Major desaulles was born Jan. 8, 1840, at New Orleans, and was the son of Louis and Armidc Longer desaulles, each of French descent. As a boy he was privately tutored in the South, and then schooled in New England to enter the Rensselaer Polytechnic Institute, where he was graduated with honors in the class of '59. Following his graduation he studied in France and Germany for two years, returning to New Orleans in 1861 to enter the Confederate Army, in which he served with distinction as an engineer throughout the Civil War, rising to the rank of Major and the command of his Corps. After the close of the war he pursued his studies abroad for another year, returning to New York in April, 1866, when he became engineer for the New York & Schuylkill Coal Company, and remained at its plant near Wilkes-Barre until October, 1871, when it was sold to the Philadelphia & Reading Coal and Iron Company. He then returned to New York where for several years he was engaged in the practice of his profession. In 1869, he married Catharine M. Heckscher, daughter of Charles Heckscher of New York City. Mrs. desaulles survives him. In 1876, Major desaulles became superintendent of the Dunbar Furnace Company in Fayette County, Pa., with which company he remained until 1883. As a feature of the Pittsburgh meeting in May, 1879, Major and Mrs. desaulles entertained the members of the Institute at dinner at Dunbar on the occasion of the Institute's visit to Dun-bar furnace. In 1883, he took up the formation of the Oliphant Furnace Company in that county, of which he became and remained the head for five years. He was then called to the superintendency of the New Jersey Zinc Company at South Bethlehem, Pa., in which position he remained until his retirement,from active service in 1911, maintaining, however, hi.; keen interest in the metallurgy and smelting of zinc, in collaboration with his son Charles, a member of the Institute and a Director of the American Smelting and Refining Company. From 1888, until his death, he resided in South Bethlehem, a prominent and highly respected citizen of that progressive and stirring community. Major desaulles was a member of the Protestant Espicopal Church, and at the time of his death was a vestryman of the Church of the Nativity at South Bethlehem. He was president of the Men's Club of the Church of the Nativity. His kindly nature led him to take an active interest in the promotion of healthful sports among young men. He was ever active in all things pertaining to the general welfare and uplift of his fellowmen. In his death the profession has lost a distinguished engineer and mctallurgist and our country a patriotic able citi-zen and man of affairs—one greatly beloved by those whom he honored with his friendship, and respected and looked up to by all who were privileged to know him.

Jan 1, 1920

By L. L. Melton, W. T. Malone

Fluid mechanics research conducted with non-Newtonian fluid systems now permits prediction of the behavior of these fluid systems in both laminar and turbulent modes of flow through circular pipes. Present work concerns non-Newtonian fluid systems currently used in the hydraulic fracturing process. During fracturing treatments, an unsteady-state condition may frequently be encountered arising from. the reaction rate of a chemical additive. This condition must be evaluated in order to predict the actual behavior of a particular fluid during field application. Design and operation of the apparatus used to determine fluid-flow behavior permit obtaining data under such non-equilibrium conditions. This paper shows methods used to obtain rheology measurements, develop hydraulic relationships and evaluate chemical reactions producing unsteady-state conditions. Engineering application of this research is illustrated by employing measured rheological values and developed hydraulic retationships to produce frictional pressure loss (psi/100 ft) us flow rate (bbl/min) charts of common tubing and casing sizes for an example fracturing fluid. How these charts and chemical reaction rate information are then combined to predict actual turbulent hydraulic behavior during unsteady-state field conditions is also discussed INTRODUCTION Many fluids used in hydraulic fracturing contain chemical additives which impart non-Newtonian fluid properties that may drastically alter their hydraulic behavior. Equally drastic alteration in wellhead pressure, injection rate and hydraulic horsepower requirement may result from these fluid properties. Prior research conducted to relate non-Newtonian fluid properties with hydraulic behavior has not as yet produced a universal relationship, particularly for the turbulent flow region. which of the many Possible non-Newtonian fluid properties is responsible has not been conclusively established. A systematic description, suggested by Metzner, of the many possible non-Newtonian fluid properties exhibited by real-fluid behavior, and a current discussion of theoretical and applied aspects of non-Newtonian fluid technoloy can be found in Handbook of Fluid Dynamics. f Little or no research has previously been attempted with fluids exhibiting time - dependent properties. Addition of chemicals during a fracturing treatment is often accomplished by continuously mixing and displacing the fluid. This produces a time-dependent effect or unsteady-state condition while the fluid is progressing through surface and wellbore conductors. This condition is due to solution or chemical reaction of the additive. Considerable departure from conventional methods of obtaining and interpreting data was found necessary to consider these conditions. Therefore methods were developed to obtain hydraulic behavior information under these complex, unsteady-state conditions. Relationships presented in this paper to predict hydraulic behavior of non-Newtonian fluids in circular pipes were obtained by constructing and operating a small pipeline apparatus in the manner of a pilot-plant study. These relationships are suggested as scaleup equations and are not proposed as fundamental rheological parameters. While perhaps deficient from a fundamental research viewpoint, a pilot-plant study does permit the determination and convenient evaluation of variables pertinent to a process. A pilot-plant study can result in a valid engineering application procedure even when fundamental relationships are still undefined. An excellent series of articles by Bowen has appeared in the chemical engineering literature.2-8 These give a thorough review of proposed hydraulic relationships and their limitations for non-Newtonian fluid behavior in circular pipes. A graphical method is presented to scale up data for a fluid exhibiting an anomalous hydrau1ic behavior in the turbulent flow region. Considerable assistance has been obtained from these articles to interpret the anomalous behavior noted during this investigation. These articles also provided assurance that a pilot plant is a practical approach to evaluate the hydraulic behavior of non-Newtonian fracturing fluids. _____________

Jan 1, 1965

By Leon W. Dupuy

Many articles have been written describing peculiar and particular types of drilling. Little correlation has been made between the character of ground to be drilled and sampled and the type of drilling most desirable for procuring satisfactory samples. In development work, the engineer and metallurgist often desire the recovery of a sample in as physically natural a condition as possible, particularly when the sample must provide material for process tests as well as chemical and physical analyses. This paper describes the results of experimentation in drilling unconsoli-dated materials carrying titanium minerals in the Magnet Cove area, Ark. The drilling was most difficult in that the ground varied much in consistency, and it was vitally necessary to recover a physically natural sample. Ordinary churn drilling recovered a sample that could be analyzed chemically, but the sample was not in its natural state. The problem was successfully solved by utilizing and further developing methods used in the oil and clay industries. In the Magnet Cove area of Hot Spring County, Ark., the titanium minerals include rutile, brookite, ana- tase, leucoxene, and others. They occur in soil, clays, and altered rocks adjacent to novaculite in contact meta-morphic deposits. In preparing titanium minerals for use in the industry, it is necessary to know the physical characteristics of the ore. Also it is believed that the particular physical character of the titanium mineral used is just as important as the chemical character. Brookite and rutile, for example, are the same chemically but differ in crystalline structure. In preparing titanium minerals for market, beneficia-tion is necessary. For the millman to make a satisfactory laboratory test, the sample he uses must be as nearly of the same physical character as he would have from mine run ore. In the past at Magnet Cove, churn drilling had been done on the properties, and assays of total titania had been obtained. It was found, however, that the total titania was indicative merely of the presence of titania but did not tell the metallurgist the character of the material or even give him the slightest indication of what he might expect to recover. When the Bureau of Mines entered the field in the winter of 1947 and 1948, it was therefore necessary that a natural sample be recovered. LIMITATlONS IN ORDINARY PRACTICE The churn drilling that had previously been done had shown that the occurrence of titanium-bearing mineral was somewhat widespread. The samples were, however, completely beaten up and in a finely powdered state. The minerals had been slimed, and such ore dressing tests as were made from the churn-drill samples were found to be worthless. Test pitting and outcrop sampling had provided satisfactory samples of surface ore but did not represent the entire ore body. A quantity of rutile had been produced from the surface residual concentrations in the westerly part of the cove, but production ran into metallurgical trouble as depth was attained. Representative deep samples upon which ore dressing research might depend were needed.

Jan 1, 1950

By W. M. Gray

The determination of the state of stress existing at a point in any solid body requires the determination of the six components of the stress tensor relative to a convenient set of axes. One general method of doing this in rock is to make strain or deformation measurements associated with local relief of stress in a number of boreholes penetrating a limited volume in the vicinity of the point at which the stress is to be determined. The stress is assumed to be constant throughout this volume. Leeman1 has described a number of the instruments that have been developed for making deformation or strain measurements in boreholes. Panek2 has described the application of statistical methods to the determination of the average components of ground stress from sets of measurements made in boreholes by means of deformation meters of the type developed by the U.S. Bureau of Mines. In this paper attention is given initially to the strain cell developed for use on the flattened ends of boreholes by the Council for Scientific and Industrial Research (CSIR) , South Africa. The equations required for evaluating the average components of ground stress from measurements made by means of the CSIR strain cell are derived. These equations are similar in form to those applying to measurements made by the borehole deformation meter developed by the U.S. Bureau of Mines. The results of an investigation of the properties of the equations are described. These results are important in the practical use of both the instruments mentioned above and any instrument based on similar principles.

Jan 1, 1968

By Edgar Stansfield

ONE of the most striking features of the coal series passing from peat through brown coal, lignite, etc., up to anthracite is the gradual reduction of moisture content with the increased coalification of the original plant material. Thus drained peat from a bog may contain 90 per cent water, brown coal contain 50 per cent, lignite 30 per cent, while a bituminous coal may contain only 1 per cent moisture. Moisture, therefore, is one of the important factors to be considered in coal classification, especially with the lower rank coals. With bituminous and higher rank coals the moisture content is less satisfactory for classification; it may even pass a minimum value and then increase with increasing rank to anthracite and superanthracite. Coal in an undisturbed seam contains moisture which is an integral part of the coal, but it may also be wet with free, underground water percolating through the seam. Only the former must be considered in evaluating the moisture content of the coal for classification purposes; this will be called the "true moisture" of the coal. When the seam is mined and sampled the sample taken may show the true moisture; on the contrary, it may contain in addition free mine water or, especially in dry, well ventilated mines, it may contain less than the true moisture. Coal contains unstable organic compounds which may decompose, with the production of moisture, when the coal is exposed to air at ordinary temperatures, or is heated with or without exposure to air. The potential moisture of a coal therefore is higher than its actual moisture. The lower the rank of the coal, the greater its instability, as a rule, and the greater the care necessary to avoid oxidation or decomposition in any investigation of moisture content. The majority of coal workers have preferred, on account of the difficulty in evaluating the true moisture of a coal, and for other reasons, to classify coals by analyses calculated to the dry-coal basis. A number of workers familiar with lower rank coals have recently insisted that the classification of such coals can be satisfactory only if analyses on the moist-coal basis are employed. The moisture-holding capacity of coal is therefore intimately connected with coal classification, and in this paper a procedure is outlined for determining the true moisture of a coal.

Jan 1, 1932

By William B Price, Ralph W. Bailey

Arsenic, antimony and phosphorus are now used in the brass industry as standard inhibitors in preventing dezincification in condenser tubes. This subject has been thoroughly covered by Barry,l who de- scribed the testing procedure by total immersion of suitable specimens in a I per cent cupric chloride solution at definite temperatures. Effects of dezincification were then determined by loss in tensile strength and elongation of the test specimens after definite periods of immersion. In the crystallography of the chemical elements as tabulated by William Hume-Rothery,2 phosphorus (metallic), arsenic, antimony and bismuth are placed in group V-B and the type of crystal lattice for arsenic, antimony and bismuth is given as rhombohedral. The Metals Handbook3 lists them as 'rhobomhedral hexagonal," with the additional notation that for arsenic this is the ordinary form at 20°C.; other modifications known or probable at other temperatures. In view of these statements and of the fact that phosphorus, arsenic and antimony are effective in increasing the resistance to dezincification, it was natural to assume that bismuth would act in the same manner. A series of tests was therefore carried out employing the methods described by Barry. Much to our surprise, bismuth did not inhibit dezincification, but rather seemed to accelerate it. Tensile-test speci-

Jan 1, 1942

By Ralph W. Bailey, William B. Price

Arsenic, antimony and phosphorus are now used in the brass industry as standard inhibitors in preventing dezincification in condenser tubes. This subject has been thoroughly covered by Barry,l who de- scribed the testing procedure by total immersion of suitable specimens in a I per cent cupric chloride solution at definite temperatures. Effects of dezincification were then determined by loss in tensile strength and elongation of the test specimens after definite periods of immersion. In the crystallography of the chemical elements as tabulated by William Hume-Rothery,2 phosphorus (metallic), arsenic, antimony and bismuth are placed in group V-B and the type of crystal lattice for arsenic, antimony and bismuth is given as rhombohedral. The Metals Handbook3 lists them as 'rhobomhedral hexagonal," with the additional notation that for arsenic this is the ordinary form at 20°C.; other modifications known or probable at other temperatures. In view of these statements and of the fact that phosphorus, arsenic and antimony are effective in increasing the resistance to dezincification, it was natural to assume that bismuth would act in the same manner. A series of tests was therefore carried out employing the methods described by Barry. Much to our surprise, bismuth did not inhibit dezincification, but rather seemed to accelerate it. Tensile-test speci-

Jan 1, 1942

PRACTICAL PROBLEMS AND BASIC PRINCIPLES ranging from ore testing to cost estimation get a working over from top men in the minerals beneficiation field. The Minerals Beneficiation Division developed this symposium for presentation at the 1953 Los Angeles General Meeting to assist the many people who think that having a new plant necessitates a lot of trouble and dismay. The papers and free discussion from the floor give ways and means of approaching a new plant that will relieve the strain on the organization, if adequate attention is put on the program before work begins - that is if thought is given to the program itself, before tackling the actual mill design.

Jan 9, 1953