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By Samuel Daniels

THE Al-Cu-Ni-Mg alloy is much benefited by heat treatment and, in such con¬dition, is preferable to the Al-Cu-Fe-Mg alloy either as cast or as heat-treated, when both are reheated to temperatures of from 400° to 600° F. and compared, cold, with respect to strength and to hardness. The main differences between the alloys do not arise until the reheating temperature exceeds 400° F., above which they gradually soften. This softening is characterized metallographically by the appearance of intragranular precipitate. The Al-Cu-Ni-Mg alloy is weakest and least hard after being reheated at 600° F., the AI-Cu-Fe-Mg alloy at about 700° F. The former starts to reharden at 700° F., the latter at 800° F. There is a tendency for both alloys to lose strength and hardness with prolongation of time at the reheating temperatures of 500° and of 700° F. The Al-Cu-Ni-Mg alloy is considerably stronger and harder than the Al-Cu-Fe-Mg alloy when both are heat-treated and reheated for long periods of time at 500° and 700° F. Although the latter can be made harder initially than the AI-Cu-Ni-Mg alloy by suitable quenching and aging, heat treatment, in general, favors the retention of this initial (strength and) hardness after reheating to a much greater degree in the Al-Cu-Ni-Mg alloy. The percentage of elongation of the two materials in any condition is very small. CERTAIN aluminum alloys have been used for pistons and other parts operating at temperatures up to 650° F. because of their lightness, high thermal conductivity and specific heat, fair strength and hardness at elevated temperatures, excellent machineability, and moderate resistance o corrosion. In the piston, the inertia forces and the bearing loading and with this the vibration are decreased. The piston head functions at a lower temperature (about 200° F. below one of cast iron), so that, because of the lessened tendency toward carbonization and detonation, higher compression ratios may be used. On the other hand, the aluminum alloys do not have the wearing and bearing qualities of cast iron; also they have a large coefficient of expansion, allowance for which must be made in the design.

Jan 2, 1926

By A. M. Sarem, J. M. Campbell

Molecular refraction is introduced as a new and improved third parameter for prediction of the PVT behavior of hydrocarbon systems. This parameter, characterizing the complex as well as the pure hydrocarbon systems (1) is a direct measure of London dispersion forces which affect the PVT behavior; (2) can be measured directly, accurately and easily for complex as well as pure hydrocarbon systems; (3) varies significantly between the reference substances thus allowing accurate interpolation of PVT properties; and (4) has a fundamentally sound basis. Molal average molecular refraction was used with the pseudocritical mixing rule proposed by Leland and Mueller to predict the molal volume of liquid and vapor for 84 published data points on nC4-nCI0, Cl-nC5, Cl-nC4-nC10 systems in the region of coexisting vapor-liquid and at the critical point. The same technique was applied to predict the densities of liquid hydrocarbon mixtures in the two-phase and single-phase regions near the critical point for seven different systems each having different properties of the heptanes-plus fraction, but all simulating the fluids of either gas-condensate or volatile oil reservoirs. A modification of the Leland-Mueller mixing rule for the determination of pseudocritical properties is also presented which yields more accurate liquid density predictions than the original form when used with the proposed third parameter. INTRODUCTION The PVT behavior of multicomponent systems has received widespread attention in the literature in recent years. A large portion of the reported work has stemmed from attempts to overcome the inherent difficulties encountered when using the standard compressibility-factor chart which shows 2 as a function of reduced temperature T, and and reduced pressure p,. This chart assumes that z, is constant for all systems. The error in this assumption is not pronounced for pipeline-type gases high in methane and low in heavy ends, particularly when contained at moderate pressures. For such gases the error in the calculated z is usually less than 2 to 3 per cent. However, the reliability of this approach becomes somewhat nebulous for gas condensate and volatile oil systems at high pressure. One logical approach has been to recognize the variation of 2,. This idea was first suggested by Meissner and Seferianl and used by Lyderson, Greenkorn and Hougen2 to prepare extensive tables of thermodynamic properties. Other third parameters have been proposed by Stockmeyer, Kihara, Riedel, Lightfoot, Bloomer and Pitzer. These were tested by Satter and Campbel13 for many gas mixtures and it was shown that they were inter-related. All of these third parameters have a common fault — they cannot be directly evaluated for the heptanes-plus fraction. Consequently, one necessary requisite of an improved method for predicting the density of multicomponent hydrocarbon systems, was development of a third parameter that could be evaluated for that fraction. PREVIOUS MULTICOMPONENT DENSITY PREDICTION METHODS Sage and Lacey4 suggested a method of using partial molal volumes for computing the density of hydrocarbon gas mixture for pressures to 3,000 psi. In this technique, they approximate the complex multicomponent gaseous mixtures by a quarternary system of methane, ethane, propane and butane. Sage, Hicks and Lacey5 suggest a method of using partial molal volumes for computing the density of hydrocarbon liquids. The results agree within 3 per cent of the experimental values. However, the composition range is limited to about 10 per cent by weight of methane. Consequently, this correlation does not cover the low-molecular-weight liquid similar to natural gasoline and high-pressure gas condensates.

Jan 1, 1966

By George Smith

The Australian Broken Hill Consols mine is situated within a third of a mile eastwards of the famous Broken Rill Proprietory mine; but, so far as has yet been proved, the respective lodes have no connection whatever. The Proprietory line of lode, striking N.E. and S.W., is coincident with the bedding-planes of the inclosing gneiss, and, according to Mr. E. F. Pittman, A.R.S.M., government geologist, is undonbtedly a saddle-formation. This opinion, which met with much opposition at the time it was advanced, is now, I understand, being generally confirmed as the work of development opens out fresh areas for observation along the line of lode. The lode is of immense thickness—in places over 300 feet and though it has been found to contain sufficient quantities of secondary silver compounds to yield phenomenal outputs of silver, its principal constituents are various lead and other ores, and it would appear more correct to regard it as an argentiferous lead-deposit than as a silver-lode proper. The Consols lode differs from its gigantic neighbor in every respect. With an average thickness of not more than 18 inches, it has been worked along its course for upwards of 1300 feet, and at every point yet explored has been found remarkably well-defined and persistent. With a strike E. and W., it cuts obliquely across the bedding of gneiss and schist, continuing uninterruptedly through various bands of eruptive amphibolite. The dip, which is to the south, ranges from 24 near the surface to nearly vertical in the lower levels; but the alteration is not regular, as in places the lode is almost flat, and this at a vertical depth of over 300 feet. These changes of inclination have had no effect on the ore-deposits, which, as I shall endeavor to show, have been governed entirely by " cross-

Jan 1, 1897

By A. Eilers

ALTHOUGH the process to which I refer in this paper has been in successful operation for nearly five years, during which time it has been introduced, superseding all other processes having in view the same end, in almost every lead refinery in the country, no description of it, giving economical data, has ever appeared in print, nor has the process been known in its details to any considerable number of engineers beside those conducting it at their works. A discussion of this subject at the present time becomes especially interesting in view of a late publication in the Prussian ministerial organ for Mining and Metallurgy, by Dr. Wedding, in which the method of treating the zinc-silver-lead alloy by distillation, as finally settled upon at Tarnowitz, is very minutely and fully described. It is the more interesting, because in that article reference is made to the American method in an unfavorable light, while, at the same time, it is clear from the article itself, that the most important details of the process, besides the one that it is conducted in black-lead retorts, were not at all understood. In publishing herewith the details of our American method, one of my objects is to invite comparisons between our simple and direct process and the elaborate one at Tarnowitz. In extracting the silver from work-lead by means of zinc, it is always the intention, in this country, to obtain a zinc-crust so rich in silver that the rich lead resulting from subsequent distillation

Jan 1, 1875

By Percy A. Robbins

The central power-station of the De Beers Consolidated Mines, Ltd., was designed and built under my supervision about five years ago. Since no detailed description of this plant has ever appeared, it may possess sufficient interest to arrant its publication, even at this late date. Although some additions may have been made to the plant, the following account, prepared from my notes, and accurate up to May, 1905 (at which time I severed my connection with the De Beers Company), will, I think, be found substantially correct. Certain local conditions governing the design of this plant should be stated first. IT. General Considerations. The climate is hot and dry. The region around Kimberley is arid and water is very scarce. The supply obtained from the mines contains so much material in solution that it is unfit for use in boilers or condensers (although tests recently made with a water-softening plant, built by Hans Reisert, of Germany, would indicate that water thus treated is suitable for boilers). And the amount of water required for concentrating about 30,000 tons of ore per day is so large that the question of adequate water-supply for this power-station had to be carefully considered. The rainy season extends from December to April, and the rainfall averages about 15 in. per year. Droughts are frequent; and in some years there is scarcely any rain at all.

Jan 1, 1909

By H. Van F. Furman

As the cyanide-method for the extraction of gold from ores is extensively used in the United States and elsewhere, and appears destined to prove a factor of increasing importance in the metallurgy of gold, a description of the latest laboratorymethods may prove of interest. The history of the development of the process in the United States has been analogous to that of all new processes. Many failures are to be recorded and a few successes. It is the opinion of the writer that, had the following simple tests been better understood, many of the failures would not have occurred, and we should probably have a larger number of successful plants in operation. While the process is not simple, but requires a high degree of chemical and engineering skill, the determination of the adaptability of an ore to the method is generally not difficult. While the laboratory-results will not always coincide with the actual results obtained in the mill, they will serve as a guide and control on the working of the mill, and mill generally suffice to determine if the ore can be

Jan 1, 1897

By Harvey T. Kennedy, Erasmo T. Guerrero

In this investigation, the effects of the surface tension of brine and the interfacial tension between oil and brine on the recovery of oil by water flooding of Woodbine sand were studied. Variation of the surface forces was obtained by the addition of small amounts of commercially available chemicals, which did not appreciably change the surface tension of the oil. Fourteen surface-active agents, which were found to be effective in lowering the surface and interfacial tensions, were further investigated to determine the extent of their adsorption by the Woodbine Sand cores. It was found that adsorption was sufficient in all cases to prevent any substantial concentration of chemical at the flood front. The flow system was, therefore, brought to equilibrium with definite concentrations in the flood water by circulation before each test. The data thus have no relation to the results obtainable by using the chemicals in full-scale water floods, but should be helpful in predicting the performance of surface-active chemicals which are not lost by adsorption, if such can be found. Flow tests were made on various concentrations 01 six chemicals selected from the 14 investigated for surface activity and adsorption, with and without the presence of gas in the core. It was found that lowering the interfacial tension had a tendency toward reducing the recovery of oil and that the reduction of the surface tension of the brine had little or no effect. A substantial beneficial effect, however, resulted from the presence of gas in the cores. INTRODUCTION The movement and distribution of crude oil in a porous medium are governed by such factors as surfacc and interfacial tensions, viscosity of the oil, pore size configuration, and wetting characteristics of the medium. The knowledge of the part played by each of these factors is limited. If the oil is assumed to be distributed in droplets whose movement is restricted only by the pore openings, the following equation may be applied: ?P= 2r(1/r1-1/r2) .......(1) In this equation ?P is the pressure drop necessary to force an oil droplet through the construction, r is the oil-brine interfacial tension, r1 is the radius of curvature at the forward and smaller end of the deformed droplet, and r2 is the larger radius. This equation neglects the effects of viscosity, as a static or near static condition is assumed. It would apply equally well for a bubble of gas in liquid if r were taken as the surface tension of the liquid. This relation shows that droplets can be more easily displaced if the interfacial tension is decreased. The displacement of oil from the surface of a sand particle may also be considered from the basis of selective wetting assuming that the oil droplets are smaller than the pore constructions and that the sand surfaces may be considered as planes. A relation of the forces involved can be derived from Dupre's equation to give: Wos = row (1 +Cos?)........(2) where Wos = Work of adhesion between the sand and the oil row = Oil-water interfacial tension 0 = Contact angle ros = Oil-solid interfacial tension This equation would indicate that the displacement of oil from a sand surface is more readily obtained when the water-oil interfacial tension is reduced provided the contact angle remains constant. Evidently. however, the values of Cos 0 may vary along with the water-oil interfacial tension due to changes in the other surfaces of the system. The above theoretical considerations suggest that perhaps even the static behavior of a dispersed oil phase in a porous medium is considerably more complex than may be inferred by the simple systems

Jan 1, 1955

THIS paper presents briefly some of the principal results of 3 ½ months field work during the summer of 1938 in the Chichagof mining district, southeastern Alaska. The report is preliminary and presumably will be followed later by a more complete report to be published by the Geological Survey. The paper is concerned principally with the structural geology of a block of steeply dipping graywacke as revealed underground in the Hirst Chichagof and the Chichagoff mines, the two principal mines of the district. The two mines have produced about $16,000,000 worth of gold and silver. The attitude of the graywacke, which is locally cut by dikes and sills of aplite, is remarkably uniform and trends about N. 62º W. The average dip is about 67º SW. The graywacke is cut by large faults, the best known of which are the Hirst and the Chichagof, whose average trends are about N. 30ºW. and average dips about 75º SW. The faults at some places split into the bedding of the graywacke and at others are deflected from their normal trends for considerable distances along the bedding. The relative movements along the faults was northwest and up at about 30º for the south- west or hanging-wall sides. The ore bodies are elongate quartz lenses in the faults. Most of the quartz is mineralized but locally large quartz masses are too low grade to be mined. The emplacement of the ore bodies appears to have been structurally controlled in large part by the intersections of the faults with the bedding surfaces. Places where the faults split or are deflected appear to have been particularly favorable places for ore deposition. There has been some post-quartz movements along the faults but it is thought that such movements have not been extensive enough to greatly modify the original positions and shapes of the ore bodies.

Jan 1, 1939

By R. H. Maes, R. E. de Strycker, J. J. Jacobs

A simple method, based upow density measurements, has been perfected in order to determine the critical temperature of liquid miscibility gaps. Applied to the Pb-Cu system, it yielded a value of 980"C for the critical tempevature of the miscibility gap in this system. In the Pb-Cu-As system, the immiscibility between lead and coppev evolves towards a miscibility gap be-tween lead and copper arsenides; the liquation temperatures were determined joy different avsenic contents and values up to 1065°C were found. Combining these results with those given by the clzemical analysis of liquid samples taken at dqj.event temperatures, it has been possible to make a cowzplete determination of the liquid miscibility gap in this ternary system. In the Pb-Cu-Fe-As system, a ternary miscibility gap has been discovered; for some compositions, the molten and slowly cooled alloys separated into three layers: an Fe-As alloy, a Cu-As alloy, and a lead-rich layer. ThE Pb-Cu-Fe-As system is of interest for the study of the behavior of speiss or arsenical alloys in the lead blast furnace. The speisses produced in lead metallurgy generally have complex compositions, but they may be considered, in a simplified way, as a mixture of copper, iron, nickel, and cobalt arsenides; there is often an excess of metallic constituants, and lead is also present. Speisses liquate from lead at various temperatures according to their composition; according to industrial experience, iron speisses are already distinctly separated from lead bullion at temperatures of the order of 1100°C, whereas copper speisses only begin to liquate from lead at much lower temperatures, near their solidification points, which were never accurately determined until now. Besides these considerations of practical interest, the present study is of importance for the knowledge of liquid miscibility gaps. Particularly the data of the literature about critical temperatures of liquation are incomplete and present sometimes considerable disparities; a method has been perfected in the present work to determine these temperatures with accuracy. MISCIBILITY GAP OF THE LEAD-COPPER SYSTEM Review of Literature. The generally admitted outline of the Pb-Cu equilibrium diagram is shown by Fig. 1. This figure, with its numerical indications, is taken from the review of Hansen and ~nderko;' compositions are given in weight percent, as will be the case in the remainder of this paper. Between 36 and 87 pct Pb, Pb-Cu alloys separate into two layers, in the liquid state. The critical temperature of liquation has been much disputed in earlier studies, where values up to 1500°C were claimed; but a reliable study of ~ohnen,' based upon differential thermal analysis, gave a value of 990°C; this rather low value was verified by a recent study of Schiirmann and Kaune? based upon thermodynamical properties of the Pb-Cu alloys, which predicted a value of 1002°C. Liquid miscibility gaps were also studied by means of chemical analyses. Satisfactory results were generally obtained with the method consisting in taking samples of the two liquid layers in equilibrium and submitting them to chemical analysis; however, this method becomes delicate near the critical temperature. With this technique, Friedrich and waehlerts ob-

Jan 1, 1968

By Erskine Ramsay

The following description of the Alabama coal-,fields is taken (with slight omissions) from the report " On the Warrior CoalField, by Henry McCalley, A.M., C. and M. E., Assistant State Geologist:" The coal lands of Alabama are of the great coal basin of the Ohio, or of the great Appalachian coal-field, and are estimated at 8660 square miles. They formed one connected field prior to the great Appalachian revolution, when there was pushed up through them long, narrow, anticlinal ridges which have been denuded into the present well-known anticlinal valleys, and thus this great field has been divided up into three more or less distinct parts. These parts were named by Prof. Tuomey, in 1849, the Warrior, the Cahaba and the Coosa coal-fields, respectively, from the names of the rivers which drain them. They are of very unequal size, the Warrior, with an area of 7810 square miles, being nearly ten times as large as the other two combined, and about two-thirds as large as the coal-area of Great Britain. This Warrior field is the most northwestern of the three coal-fields of Alabama, and comprises all of the coal-measnres in Alabama, northwest of the Alabama Great Southern railroad, or all of those drained by the Warrior and Tennessee rivers. The greater part of this field, almost all of it away from the present railroad lines, has never received more than a surface-examination. Still, we have in the Warrior coal-field one of the richest coal-basins of this or any other country. As a whole, the Warrior coal-field is a broad, shallow, tray-shaped depression, sloping towards the southwest, and with its southwest end covered by a newer formation and its southeast side, especially, complicated by folds and fractures. As is the case with all of our Coal Measures. it is composed of a series of sandstones. conglomerates, shales, slates and coal-seams, with some little limestone at several horizontal positions, but contains no thick bed of this last rock like the Measures of Pennsylvania and other States. The thickest conglomerates are near the bottom and top of the series, and hence these coals might be said to belong mainly to the

Jan 1, 1891

By James F. Kemp

The iron ores of southeastern Cuba present a subject of exceptional geological interest. Their relations to the inclosing rocks are varied and in some cases unusual. The problem of their geological origin is not a simple one and for this reason has occasioned some divergence of views among previous observers. Profiting, however, by these earlier studies and by more detailed field and laboratory observations as well as by the experience of added years of mining, much more satisfactory descriptions and interpretations can now be prepared. Previous Work In 1884, interest in the southeastern coast of Cuba became active among the consumers of iron ore along the Atlantic seaboard of the United States. Active development was undertaken by the Juragua Iron Co., Ltd., a corporation affiliated with the Bethlehem Steel Co., and the Pennsylvania Steel Co. The property of the Juragua company, which is situated about 15 miles east of Santiago, was studied in June and July, 1884, by Dr. James P. Kimball, at the time Professor of Economic Geology in Lehigh University and one of the best known of American mining geologists. Dr. Kimball published on his return two papers, the first important descriptions which we have of the local geology.1 It is

Jan 1, 1916

By David R. Maneval, Jack M. Campbell

The regulatory process by which governmental authorities acknowledge and, in turn, permit the location, construction, and operation of large scale energy-related facilities has become extremely detailed in recent years. One example of the detail that is entailed in the regulatory process is the number of permits that must be acquired by operators prior to the construction and operation of energy-related facilities. It has been estimated, for example, that 75 permits are required prior to the opening of a new coal mine in Pennsylvania while 50 are required in Kentucky. From the perspective of facility owners and operators the regulatory process often appears overly complex and may be perceived as a constraint to the corporate decision making process. From the perspective of those responsible for administering regulations, the process is perceived as a means by which public desires-pursuant to social objectives such as environmental protection and occupational safety-can be achieved. As a result of conflicting organizational interests, the clash between energy facility owners and operators and their regulators appears to be inevitable. Furthermore, the resolution of this conflict lies in the trade-off between objectives and the costs of regulation. The balance of objectives and costs is a subject of the political process and not a topic of consideration in this paper. This paper is concerned with the actual administration of regulations, that is, the implementation of that which arises from the interplay of organizational interests. The paper assumes that environmental control laws will not likely be repealed, that regulations to implement the intent of these laws are here to stay and thus the paper seeks to assess how regulations are administered at various levels of government pursuant to objectives. The paper hypothesizes that the administration of objectives (or policy) has an impact on decision making which affects energy facility decision making. While recognizing the fact that regulatory policy cannot be totally divorced from administration, this paper proceeds under the assumption that elements of the regulatory process may be examined individually. The subject of this study is limited to the interplay between regulatory agencies and their clientele.

Jan 1, 1979

By J. B. Stubbins, R. A. Blais

Extensive geological work was initiated — and continues — when operations of the Iron Ore Co. of Canada commenced in the Labrador-New Quebec area. Such geological operations include: mapping, test pitting, drilling, underground workings, volume factor and structure tests, and the calculation of ore grades and tonnages. Details of such work are given. Development is carried sufficiently ahead of mining to provide reliable tonnage and grade estimates and allow final mine planning. In order to make full use of geology in mining operations, the pit engineer combines the duties of geologist and mining engineer. The iron deposits of the Knob Lake range are located in the central part of the Labrador peninsula, a territory nearly twice the size of Texas, which is bounded by Hudson Bay on the west, Hudson Strait on the north, the Atlantic Ocean on the east and the Gulf of St. Lawrence on the south. The mining district proper is about 1000 miles northeast of Toronto. A 360-mile railroad links this mining area to the port of Sept-Iles on the Gulf of St. Lawrence. Schef-ferville, which is only a few miles from the open-pit mines, is the center of operations of the Iron Ore Co. of Canada. It has a population of nearly 5000. The nearest settlement is Labrador City, some 120 miles to the south, where this company is erecting a large plant for beneficiating its huge reserves of local low-grade iron ores. HISTORY The mineral possibilities of the area were recognized as early as the end of the last century, when A.P. LOW' of the Geological Survey of Canada made his famous trek across the Labrador Peninsula. After mapping several belts of iron formation, Lovr recommended that the area be thoroughly prospected for iron. In 1929, two well known Canadian geologists, J.E. Gill and U'.F. James, led a private expedition in central Labrador and discovered the first deposit of high-grade iron ore near what is now the Ruth Lake Mine. In 1936 the Labrador Mining and Exploration Co. was formed to 11ake over a prospecting concession of over 20,000 sq miles in central Labrador. An adjoining concession of 3900 sq miles in New Quebec was obtained in 1942 by Hollinger Consolidated Gold Mines, which had just Purchased the Labrador Co. The same year the M.A. Hanna Co. Purchased an interest in both exploration companies. From 1942 to 1950 extensive exploration was conducted by the Hollinger-Hanna technical staff to systematically appraise these vast concessions. More than 40 deposits of high grade ore were found and, by the end of 1950, the total ore reserves reached 418 million tons. In 1949 five American steel companies joined the Hollinger-Hanna interests and formed the Iron Ore Co. of Canada. Financing and full-scale construction were decided upon in 1950. This included the construction of a 360-mile railroad through very difficult terrain, the erection of two hydroelectric plants, the installation of terminal port facilities at Sept-IIes, the building of a modern town-site at Schefferville, the construction of crushing and screening plants, and the preparation of deposits for mining. Ore was first shipped in July 1954. Total open-pit mine production to date is 66 million long tons of direct-shipping ore. GEOLOGICAL ENGINEERING The above achievements would not have been possible without irtegrated teamwork of people of diverse skills and extensive use of geology. In their paper on the role of geologists in the development of this iron ore field, (Gustafson and Moss1 rightly emphasized the difficulties facing the early workers in the area. In an uninhabited land with no roads or railroads and no navigable rivers leading to the interior, everything had to be flown in. It was not until 1948 that aerial photographs and adequate base maps became available. In spite of these and other difficulties, an impressive amount of field work has been done since 1942. Nearly all this work has been directed by geological engineers and geologists. About 15,000 :sq miles have been geologically

Jan 1, 1962

By FRANK R. VAN

I. INTRODUCTION. IN the summer of 1908, R. B. Cochran, Superintendent of the Compania Metalurgica Mexicana at Sierra Mojada, Mexico, presented to the Department of Geology and Mineralogy at Case School of Applied Science an interesting series of silver-, copper-, and lead-ores from the Veta Rica mine. These ores contained several interesting minerals which were associated in a somewhat peculiar manner, so that I was impelled to make a closer study of their occurrence. The investigation has brought out several new facts concerning the geology of the district and the geological occurrence of the ores, and therefore has seemed worthy of record. Two papers have been published previously about the region, one by Chism1 in 1887, and the other by Malcolmson2 in 1902. These articles, however, treat of the district more from the stand-point of the metallurgist and mining engineer, and not much attention is devoted to its mineralogy and economic geology. II. GEOGRAPHICAL LOCATION OF THE DISTRICT. The Sierra Mojada is situated in the extreme western part of the State of Coahuila, near the Chihuahua boundary. It is reached best via the Mexican Central railroad from El Paso, Tex., to Escalon, Chihuahua, a distance of 494 miles. From this point, a branch line, the Mexican Northern railroad, runs 78 miles in a NE. direction to the mines, which are its northern terminus. The railroad was built about 1890, practically on account of the Sierra Mojada mining-district. 1 Sierra Mojada, Mexico, by Richard E. Chism, Trans., xv., 542 (1886-87). 2 The Sierra Mojada, Coahuila, Mexico, and Its Ore-Deposits, by James W. Malcomson, Tram., xxxii., 100 (1901).

Aug 1, 1912

By N. F. Foster

The use of piezoelectric semiconducting materials for the fahrication of ultrasonic transducers has raised the upper fundamental frequency limit for transducers from about 200 mc to above 10 kmc, Several types of semiconductor transducer configurations have been proposed and examined experimentally. Depletion-layer transducers have been made and operated at frequencies below 1 kmc hut they appear to he better suited for operation at considerably higher frequencies around 10 knzc. Diffusion-layer transducers have been made and operated in the range 50 to 1000 mc and have exhihited considerably improved conversion losses and bandwidths compared with other transducers available in the frequency range. A variety of novel structures are possible using these new types of transducers, some of which could lead to substantial advances both in research and in the fabrication of ultrasonic delay lines and memory elements. THE field of ultrasonics today spans some five decades of the frequency spectrum from the audible to the kmc range and finds applications ranging from fundamental research into the atomic structure of matter to the degreasing of machine parts. To cover this wide range it has been necessary to develop a great many types of ultrasonic trandsucers utilizing a variety of materials and physical phenomena. The first ultrasonic transducers were made during World War I for a submarine-detection system. They consisted of plates of single-crystal quartz bonded between metal plates and were one of the first applications of the phenomenon of piezoelectricity discovered nearly 30 years previously. Despite the many advances which have been made in transducer technology, piezoelectric transducers using single-crystal quartz are still used almost exclusively for application above about 30 mc. Transducers at these frequencies are normally made in the form of thin quartz plates which are then bonded onto the medium in which the ultrasonic wave is to be propagated. The crystallographic orientation and geometry of these plates determines the type of wave generated and the way in which the efficiency of the electromechanical conversion varies with frequency. Analysis of the design parameters shows1 that the frequency of maximum efficiency (the fundamental or resonant frequency) is that frequency at which the transducer is approximately half the wavelength of the ultrasonic wave in the material. As the frequency increases, the ultrasonic wavelength, and therefore the optimum transducer thickness, decreases and in practice the fabrication of quartz transducers with fundamental freauencies above 100 mc becomes extremely difficult due to the extreme thinness required. For frequencies above 100 mc quartz transducers can be used in overtone-mode operation, and for very high frequencies (500 to 24,000 me) a technique using a quartz rod inserted in a high-Q microwave cavity4 is available. These techniques, however, exhibit comparatively low fractional bandwidths and rather poor conversion efficiencies. The present trend in ultrasonics is towards high frequencies and greater bandwidth to allow the use of shorter pulses which can give increased discrimination in radar-system delay lines and greater storage capacity in computer applications. The increasing demand for more efficient transducers with greater bandwidth

Jan 1, 1964

By J. B. Bassett, E. S. Rowland

The experimental work reported herein firas inspired by the publication of a paper by Grange and stewart, in which it was suggested that at low chromium contents the effect of this element on the Ma point was greater than at higher chromium contents, It was argued that, if a small increase of chromium in solution in austenite caused a sharp lowering of the M, point, it might lead to an explanation of occasional unsolved stress cracking of SAE 52100 during heat treatment. Commercial hardening is carried out at temperatures of incomplete solution, leaving carbides available to enrich the austenite during any inadvertent increase in temperature, such enrichment of the austenite in chromium content would lower the M, point nearer room temperature where cracking is more likely to occur. According, it was decided to investigate the effect of chromium, in quantities between o and 2 pet, on the M, point of commercial steels. Fig I summarizes the data available on chromium steels. For purposes of comparison, the M, temperature values were corrected by means of the Grange and Stewart formulas to (I) Hypoeutectoid compositions: 0.50 pct carbon and 0.80 pct manganese (z) Hsereutectoid compos-sition': 1." pet carbon and O.35 pct manganese. Only the steels having compositions reasonably close to these corrected values were included, because large adjustments inevitably introduce increased error such as are experienced in using the formula. The straight lines of Fig I were drawn by the authors. These data obviously do not settle the question Of the effect Of chromium On the Md Oint, particularly at low chromium contents. While it is fairly well established that chromium causes the M, to be lowered when present in quantities of I pet Or more, Grange and Stewart1 have suggested that in small amounts (less than 1 pet) it is more effective in lowering the Ma point, while Klier and Troiano2 have suggested that in small amounts it is less effective in lowering the Ma point. Payson and Savage3 concur with Klier and Troiano and further suggest that the effect is not linear at these concentrations. Rose and Fischer4 report that small amounts of chromium actually raise the Ma point of a 0.20 carbon steel. Material Two series of 35 Ib induction heats were melted for this work, the analyses of which are given in Table I. One series was aimed at 0.50 pct carbon and 0.80 pct manganese with chromium additions in 0,25 pet increments from o to 1.5 pct with a single heat at 2.0 pct Cr. This series was considered necessary because the commercial heat treatment of SAE 52100 does not generally introduce more than about 0.60 pct carbon in solution in the austenite. The high

Jan 1, 1949

By James C. M. Li

The thermodynamics of the set of functions including the activation enthalpy. the activation free energy, and the activation entropy for the motion of dislocations at low temperatures is formulated without a specific model or a mechanism. The behniiior near absolute zero of all these functions and of other relevant quantities related to dislocation mobility Is examined in the light of the third law of thermodynamics. The velocity measurements of Stein and Low for edge dislocations in Si-Fe are used .for illustrotion. In the plastic deformation of crystalline materials, a fundamental assumption, which is supported by direct measurements using etch-pit techniques,'-4 is that the average velocity of a certain mobile dislocation is a single-valued function of temperature and the effective shear stress exerted on the mobile dislocation: Sometimes under certain assumptions, even without direct dislocation-velocity measurements, an activation volume can be obtained from a change in strain rate in a simple tension test. Similarly an ac tivation enthalpy can be obtained by changing the temperature in a creep test. However, the assumptions involved should be studied carefully before using the results of these tests. Consider, for example, a tensile specimen at some stage of deformation with a distribution of mobile dislocations. Let the total length of dislocations of type i be pi per unit volume. The Burgers vector of these dislocations is hi which makes an angle ?i with the tensile axis. With respect to the same tensile axis, let the normal of the slip plane of these dislocations

Jan 1, 1965

By J. B. Mackintosh

The quantitative determination of copper, by means of electrodeposition, offers so many advantages, that it is to he preferred, when properly executed, to 611 other methods for ease and accuracy. The object of the present paper is to give the results of a number of experiments made during the past few months, and to indicate some sources of error, which must be avoided in order to attain the necessary accuracy. In 1867, C. Luckow, in competition for a prize offered by the directors of the Mansfield Copper Works, submitted the following

Jan 1, 1882

By C. Willard Hayes

Introduction.—The recent developments in the metallurgy of aluminum and its consequent rapidly growing use in the arts are at present attracting considerable attention to its ores. The success of the Hall electrolytic process, by which the metal is obtained directly from the oxide, has removed bauxite from the position of a rather uninteresting mineral to that of an important ore. Its production on a commercial scale is so recent, particularly in this country, that little attention has yet been paid to its mode of occurrence and origin.. Any investigation, therefore, which throws light upon these points should be of interest to mining engineers- at the present time, especially if the conclusions afford a basis for estimating the probable extent and value of deposits already known and a mane of directing search for others. Two localities in the United States have so far yielded bauxite in commercial quantities. These are in Arkansas and in the Coosa valley of Georgia and Alabama. According to descriptions of the Arkansas deposits by Branner, they bear little resemblance to those in the Southern Appalachians and their geological relations appear to be entirely different. Only the latter deposits are considered in the following paper. These have been briefly described by McCalley† and Spencer.† They were visited by the writer during the past summer and somewhat carefully examined, in connection with the study of the areal geology of the region. Location of the Deposits.—The ore is found irregularly distributed within. a narrow belt of country extending from' Adairsville, Ga.,

Jan 1, 1895

By H. L. Hartman

The drop tester has proved an invaluable tool for the investigation of percussion drilling in the laboratory in "slow motion". It has allowed the process of rock penetration by impact to be studied a single blow at a time. In the present work, the relation of cratering to indexing has been determined under conditions simulating those in the bottom of the hole at atmospheric pressure. Indexed blows form craters which are influenced by others adjacent to them. Two unique effects are involved: (1) the provision of additional free faces in proximity to the point of impact and (2) the creation of subsurface damage by the previous blow(s). Both have a pronounced influence on the volume of rock removed per blow, which governs the rate of penetration in actual drilling. The emphasis in this study was placed on determining effects of index distance and impact energy on crater volume when blows were struck on a previorusly "drilled" or damaged surface, a situation most representative of down-hole conditions. The results indicated that (I) the optimum index distance on a damaged surface is greater than on a fresh, undamaged rock surface; (2) the volume of rock broken at optimum index distance is about the same for both surface conditions with die-shaped chisels but tends to be greater on a cratered surface with wedges; (3) the optimum index distance and maximum crater volume are proportional to the energy level; (4) at a given energy level, the volume of rock broken by dies generally exceeds that by wedges; and (5) maximum crater volume varies, approximately, inversely with width of die but is nearly independent of included angle of wedge. INTRODUCTION This is the third of a series l,2 of papers reporting on one phase of a continuing program of drilling research being conducted in the Rock Mechanics Laboratory at The Pennsylvania State U. The phase under consideration is crater geometry — blow energy relations in percussion drilling. While the previous papers have discussed mainly craters produced by single blows, indexed-blow studies are the subject of this paper. The basic mechanism of drilling under study here — that of penetration of a chisel-shaped bit subjected to impact — is the one employed in probably 90 per cent of all rock drilling in mining, percussion drilling. It also forms the fundamental action in nearly all oil well drilling with the so-called rotary (roller-bit) method. Here, the action is more complex, however, and may in actuality comprise rotary-percussion drilling. Certainly, the down-hole air and mud hammer drills, which superimpose percussion on rotation, belong in this latter category. In any event, impact blows constitute one of the principal mechanisms in the vast majority of drilling, mining or petroleum, and it is essential in drilling research to study percussion in all its basic aspects. Percussion drilling can be simulated in the laboratory by means of an impact drop tester. Striking one blow at a time with chisel-shaped bits, the drop tester permits study of most of the parameters in the drilling process except blow frequency and the interrelationship of certain variables. Single-blow craters, the simplest to produce, allow the determination of basic relationships, such as volume vs blow energy; while indexed craters most closely resemble the action in real drilling and provide data for the establishment of optimum operating criteria. Indexed-blow craters are those which are influenced by others in proximity. The simplest case to visualize, and the one studied in detail here, is that in which a given crater is formed adjacent and parallel to a previous crater, such that the second crater breaks into the first. A more complex situation usually exists downhole, where indexing is achieved by rotation of a radial-winged or rolling-cutter bit. But, admittedly, the phenomenon of indexing is more likely to be understood eventually if it is first studied in its simplest form, that related to parallel craters. Limited research has been conducted on indexed blows. The most complete study was that by Simon, 3,4 who proposed universal indexing curves to relate the important variables. His work, however, was conducted entirely with rows of craters formed on a