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By J. W. Halley

THE effects of tin on steel have become increasingly important because of the necessity of using poorly detinned scrap, tin cans, and terne plate, in the open hearth. Since a tin can contains about 1.5 per cent tin, it would be possible to have up to 0.75 per cent tin in steel made with a 50 per cent scrap charge. In order to use tin-containing scrap, it is necessary to know the effect of tin on various grades of steel. The following investigation is by no means comprehensive but covers a number of steels in which tin content is important. PUBLISHED WORK A number of investigations of the effects of tin on rolling quality and physical properties have been published. It has been found that tin increases strength and hardness and reduces ductility and notched impact resistance. The decrease in ductility and notched impact resistance becomes more marked as the carbon decreases. McKimm1 found no change in Olsen ductility, Rockwell hardness, yield strength, tensile strength or elongation in cold-reduced strip containing up to 0.124 per cent tin. A tin content of 0.15 per cent gave difficulties in rolling and increased the hardness but 0.21 per cent tin showed no change in properties from material containing very little tin. No explanation of this contradiction is offered. Andrew and Peile2 investigated steels containing 0.10 to 0.25 per cent carbon and up to 0.63 per cent tin. They found an increase in tensile strength 0f from 100 t0 200 lb. per sq. in. for each 0.01 per cent tin on normalized samples. The elongation and reduction of area were decreased and the notched impact resistance was reduced markedly. Quenched and drawn samples did not show embrittling if water-quenched from the draw temperature of 1148°F. (620°C.). They could find no evidence of tin under the microscope. Whitely and Braithwaite3 investigated the effect of tin on rail steel containing 0.55 to 0.60 per cent carbon. They found that 0.08 per cent tin caused a marked decrease in elongation, notched impact resistance and the degree of bend. The tensile strength was increased in some tests and not in others. Bolsover and Barraclough4 investigated the effect of tin up to 0.50 per cent on a 0.35 per cent carbon steel and on several alloy steels with from 0.30 to 0.40 per cent carbon. They found a comparatively uniform decrease in notched impact resistance with increasing tin on quenched and drawn samples. If the samples were quenched from the drawing temperature or reheated to the drawing temperature and quenched, the embrittling was much less severe. Steels containing molybdenum suffered much less embrittlement than other steels. EXPERIMENTAL WORK Effect of Tin on Low-carbon Rimmed Steel Increasing quantities of tin were added to four ingots of a heat of the following ladle analysis: carbon, 0.08 per cent; manganese, 0.39; phosphorus, 0.009; sulphur, 0.025.

Jan 1, 1942

By T. L. Fritzlen

Extrusion of aluminum alloys in this country is performed mainly by direct extrusion, therefore this paper is confined only to factors affecting the rate of extrusion by this method. Many factors affect the rate of extrusion of aluminum alloys. It is the purpose of this paper to present a discussion on the factors that are subject to technical control. Most of them are closely related, so that a clear-cut distinction between them is rather difficult. However, an attempt will be made to evaluate the effect of each factor separately, as far as possible. The most important factors only will be considered, and these will be discussed in detail under three general headings: (I) characteristics of the equipment, (2) size and structure of the ingot, and (3) temperature of ingot, cylinder, and other parts. It is a well established fact1 that the pressure and the speed of extrusion are related and are exponential functions of one another. Therefore, whenever a certain condition tends, for instance, to increase the pressure required for extrusion, it will reduce the extrusion speed if the pressure is maintained constant. For this reason, in this paper the effect of various conditions is expressed either in regard to their effect on the pressure required or the extrusion speed. Another established fact is the relation- ship between the temperature of the material being extruded and the pressure required to extrude. According to Schi-shokin,= this relationship is of the exponential type, and as the temperature is increased the pressure required is decreased. It would seem from the preceding that the greatest rates of extrusion can be obtained by the use of higher temperatures. However, as is well known, other factors intervene to limit the rate of extrusion of aluminum alloys when increasing the temperature. These factors will be discussed in detail later. Characteristics of the Equipment The capacity of the press determines * the maximum unitary pressure that can be applied for any given cylinder diameter. Pressures used for extrusion of aluminum alloys range from approximately 50,000 lb. per sq. in. to 150,000 lb. per sq. in., dependent upon the alloy and the size of the shape extruded. Higher pressures could be used to advantage, but existing steels limit pressures employed in the production of extrusions. Numerous mechanical characteristics of the extrusion press affect extrusion rate. The most important characteristics of the press itself are: (I) sensitivity of the main pressure valve and accuracy of pressure gauges, (2) accuracy of equipment to heat the cylinder uniformly and to control cylinder temperature, and (3) accuracy of means of measuring the speed of extrusion. The variables subject to control during the extrusion operation are pressure, temperature, and speed, and it is evident that the preceding characteristics

Jan 1, 1946

By T. L. Fritzlen

Extrusion of aluminum alloys in this country is performed mainly by direct extrusion, therefore this paper is confined only to factors affecting the rate of extrusion by this method. Many factors affect the rate of extrusion of aluminum alloys. It is the purpose of this paper to present a discussion on the factors that are subject to technical control. Most of them are closely related, so that a clear-cut distinction between them is rather difficult. However, an attempt will be made to evaluate the effect of each factor separately, as far as possible. The most important factors only will be considered, and these will be discussed in detail under three general headings: (I) characteristics of the equipment, (2) size and structure of the ingot, and (3) temperature of ingot, cylinder, and other parts. It is a well established fact1 that the pressure and the speed of extrusion are related and are exponential functions of one another. Therefore, whenever a certain condition tends, for instance, to increase the pressure required for extrusion, it will reduce the extrusion speed if the pressure is maintained constant. For this reason, in this paper the effect of various conditions is expressed either in regard to their effect on the pressure required or the extrusion speed. Another established fact is the relation- ship between the temperature of the material being extruded and the pressure required to extrude. According to Schi-shokin,= this relationship is of the exponential type, and as the temperature is increased the pressure required is decreased. It would seem from the preceding that the greatest rates of extrusion can be obtained by the use of higher temperatures. However, as is well known, other factors intervene to limit the rate of extrusion of aluminum alloys when increasing the temperature. These factors will be discussed in detail later. Characteristics of the Equipment The capacity of the press determines * the maximum unitary pressure that can be applied for any given cylinder diameter. Pressures used for extrusion of aluminum alloys range from approximately 50,000 lb. per sq. in. to 150,000 lb. per sq. in., dependent upon the alloy and the size of the shape extruded. Higher pressures could be used to advantage, but existing steels limit pressures employed in the production of extrusions. Numerous mechanical characteristics of the extrusion press affect extrusion rate. The most important characteristics of the press itself are: (I) sensitivity of the main pressure valve and accuracy of pressure gauges, (2) accuracy of equipment to heat the cylinder uniformly and to control cylinder temperature, and (3) accuracy of means of measuring the speed of extrusion. The variables subject to control during the extrusion operation are pressure, temperature, and speed, and it is evident that the preceding characteristics

Jan 1, 1946

By Samuel S. Wyer

Magnitude and Econonmic Importance THE magnitude and economic importance of the problem of correctly valuing natural-gas leaseholds become evident when we consider that: (a) Natural gas is handled in 55 per cent. of the gas distributing plants in the United States. (b) Present known natural-gas acreage forms 47 per cent. of the total known mineral-land acreage in the United States. (c) Five acres of land are now required to protect and maintain continuous service to each of the 2,000,000 domestic natural-gas consumers in the United States. (d) The cost of acquiring and maintaining this acreage of an expendible resource represents a substantial part of the cost of the natural-gas service to the consumer. (e) "The right of a citizen by means of his ownership of or his mining leases on land to draw gas from beneath its surface is property and sometimes valuable property."1 A large number of other court decisions have established the basic legal principle that the right to drill for gas within a given area constitutes an interest in the land itself, and is necessarily an exclusive property right.

Jan 4, 1916

By E. W. Filer, R. P. Smith, L. S. Darken

The solubility of nitrogen gas in purified iron and low alloy steels is determined for the y region (930° to 1350°C). The diffusivtiy of nitrogen is estimated from the rate of approach to equilibrium. The investigation of aluminum-killed steels, held in nitrogen, discloses precipitation of aluminum nitride, the solubility of which is determined. ALTHOUGH several investigations of the solu-bility of nitrogen gas in y iron have been reported, all have made use of the method adopted by Sieverts in his classic work, whereby the solubility is determined by the pressure or volume change of the gas. The agreement between different investigators* is rather poor, particularly as compared to the self-consistency of results of several individual investigators. The present report represents a portion of our investigation of the equilibrium of nitrogen and nitrogenous atmospheres with iron and steels. The method adopted in this temperature region (910" to 1400°C) consists of holding the specimen in gaseous nitrogen, quenching (or cooling), and determining the nitrogen content by direct analysis (solution in acid followed by distillation and titra-tion of the ammonia).** Up to 1050°C a 20 in. vertical wire-wound (Kan-thal) furnace was used; this was wound in three sections so that by proper adjustment of relative currents, and use of a modulator1 and a commercial controller (using a chromel-alumel control couple), a zone almost 6 in. long could be maintained uniform within a few tenths of a degree. Since the temperature coefficient of the nitrogen solubility is low, the full precision was not utilized and a variation of l° to 2" was tolerated; a variation of a similar amount also occurred occasionally between the beginning and end of the experiment. At higher temperature a vertically mounted, tubular Globar furnace and control unit was used; the zone of uniformity (l° to 2"C) was here limited to about 2 in.; fluctuations with time were comparable to those in the wire-wound furnace. Reported temperatures were measured by use of a platinum-platinum-rhodium thermocouple, which was frequently com- pared with a similar standard couple which was calibrated at the gold and palladium points and also compared with one certified by the Bureau of Standards; error from this source is believed to be less than 1 "C. Nitrogen gas from a commercial cylinder was mixed with slightly over 1 pct H by use of a gas mixer described previously.' This mixture was passed over hot copper and through ascarite and phosphorus pentoxide to remove oxygen and water vapor. The purified gas contained 1.05 pct H. This procedure was adopted to prevent the formation on the specimens of oxide film, which is well known to be nearly impervious to nitrogen; its success was attested by

Jan 1, 1952

By A. B. Stickney

UPWARDS of 200,000 engineers in this country are sufficiently interested in engineering as a profession to have joined a society, but not over 10% of them belong to any one society. There is a widely-felt need of an over-all organization of all the societies to act as spokesman for all engineers on matters of common concern. On a local basis, over 100,000 engineers in 35 metropolitan areas have organized themselves into local councils, and are doing an effective job of intersocietal co-operation within their sphere of activity. In the last few years much has been said and written about a similar organization on a national scale. Everybody wants iteverybody is talking about it-it's in the air-it's coming-it's inevitable. Although it is no longer necessary to talk about why or whether there should be such an organization, there is no such unanimity about what it should be like. This paper outlines a proposed organization by answering four questions-who, how, what, and who will pay for it.

Jan 1, 1946

By G. Borelius

ABOUT the turn of the century, Gibbs' thermo-dynamic theory of heterogeneous equilibrium, on the one hand, and the experimental methods of thermal and microscopic analysis, on the other, gave to the physical metallurgist his first scientific tool, the equilibrium diagram. The classical equilibrium diagram of a binary alloy system shows the boundaries between ranges of homogeneous and heterogeneous equilibrium in their dependence of concentration and temperature. A homogeneous solid sohtion which on cooling passes such a boundary is assumed to precipitate, forming a mixture of two phases with different concentrations. The equilibriunl diagram and the equilibrium theory, however, give no information about the time scheme of the process or the intermediate states passed during precipitation. For this reason it satisfies neither the practical need of the metallurgist nor the curiosity of the physicist. As a matter of fact, in the heat treatment of alloys for technical use the objective very seldom is the equilibrium state. Thus good mechanical properties of construction material are connected, for the most part, with some intermediate state. As these intermediate states are thermodynamically unstable, there is, from a theoretical point of view, always to be expected a decay of the good properties with time; and it is a matter also of practical interest to know whether this natural life time of a material is of the order of, say, ten or thousands of years. Thus, for many reasons, there is a current demand to complete our knowledge of equilibrium through knowledge of the kinetics of the precipitation phenomena. From the point of view of the physicist, the most interesting question in this case is whether there are any general laws governing the kinetics. According to a generally accepted view, precipitation is ruled by two more or less independent phenomena, the formation of nuclei of a new phase and the growth of these nuclei. It is also commonly accepted that there is a tendency for the velocity of growth to increase with increasing temperature because of the increasing mobility of the atoms. There is also a tendency for the velocity of growth to decrease in the neighborhood of the two-phase boundaries. So far, however, very little is known quantitatively about this fundamental phenomenon in the case of solid metallic systems. In our laboratory attention has been directed especially toward the nucleation phenomena, and a series of measurements have been carried out with the guidance of a work- ing hypothesis (based on experiences from previous work on order-disorder transformations in alloys) about the influence on the nucleation of thermo-dynamic potential barriers. However, before discussing the experiments, the theoretical ideas will be considered. In a binary solid solution the arrangement of atoms on the lattice points approaches with increasing temperature a state of full randomness, as illustrated by the ball model of Fig. 1, that might represent a [111] plane of a face-centered alloy with 30 pct "black" and 70 pct "white" atoms. In reality the atoms are changing places continually with their neighbors so that the picture should rightly have been a moving one. On account of this thermal motion the concentration of black atoms within a certain group of, say, a hundred or a thousand lattice points fluctuates with time around the bulk concentration of 30 pct in a manner governed by statistical laws. With decreasing temperature two independent changes in this state grow more and more important. First, the mobility of the atoms decreases, and second, the forces between the atoms will have an increased influence on the fluctuations. In alloys with a tendency for precipitation, which are the concern of this lecture, the distribution function of concentration fluctuations will broaden, so that the relative probability of great local variations from the bulk concentration increases. Fig. 2 gives an example of such a fluctuation. When the alloy is supercooled below the solubility limit into the range of two-phase equilibrium, the fluctuations will now and then at some point give rise to a state that resembles the equilibrium state and thus will form a stable nucleus that is capable of growing by diffusion processes. In discussions with colleagues and in the literature, I have often encountered the idea that three or four atoms of the dissolved metal could form a nucleus of the new phase. A look at the ball model might be enough to indicate that this cannot be true. If it were true, there should be nothing but nuclei, whereas we know from experiment that nucleation must be a rather rare occurrence. In fact we have, as will be mentioned later, certain reasons to believe that the nuclei are formed by fluctuations containing some hundreds of atoms, which should be the order of the number of black balls in the fluctuating group of the figure, if it were extended into three dimensions. As a working hypothesis we have assumed that the fluctuations producing nuclei, though large and rare, still are ruled by the distribution laws of fluctuations of the supercooled solid solution in its initial state. Thus the probability of nucleation will be connected to the thermodynamic properties of the solid

Jan 1, 1952

By Raymond Moore

THE oil-producing districts of Kansas comprise the northern portion of the so-called Mid-Continent field. As shown in the accompanying map, these districts are located chiefly in the southeastern and south central parts of the state. A considerable area in southeastern Kansas, extending northward nearly to Kansas City, has long been known as oil territory, the productive wells being distributed in patches or spots' of irregular size and shape, the location of which is controlled by conditions of rock structure, and by the texture and porosity of the "sands" beneath: the surface. In south central Kansas, there are a number of producing fields, the location of which appears to be controlled chiefly by well-defined structure. The most important districts are those in Butler County, especially that in the vicinity of El Dorado, which was for a time the most productive district in the entire Mid-Continent field. Recently new production of importance has been brought in the vicinity of Peabody and present development is active to the north across Marion County. Tests in the western parts of Kansas have not been successful in finding new petroleum fields. HISTORY The first well drilled for petroleum, in Kansas, was near the town of Paola, Miami Co., about 40 mi. southwest of Kansas City, in the summer of 1860, only a few months after the completion of the famous "Colonel Drake discovery well in Pennsylvania. Kansas appears to be the second state to engage in a serious attempt to find oil by drilling. The Civil War caused the temporary abandonment, of attempts at oil development in the state.

Jan 2, 1920

By Orville R. Lyons, A. C. Richardson

DURING the past few years there has been a growing demand by coal operators for detailed information about the performance characteristics of the various dryers now being manufactured, preferably in such a form that the information could be used to determine the type of dryer best suited to a particular drying problem. A few operators have been desirous of going even further, because they are of the opinion that present-day dryers are not properly designed and that fundamental studies of dryer design should be undertaken. This growing demand for a method of dryer evaluation and the indicated need for fundamental research resulted in the sponsorship by Bituminous Coal Research, Inc. of a project at Battelle Memorial Institute to investigate the thermal drying of coal. In investigating this problem, the most feasible method of attack appeared to be a survey of active operations to determine the present status of the thermal drying of coal. Data were obtained, usually by actual plant tests with the cooperation of the various preparation engineers and their staffs, for Q screen-type dryers, 8 rotary- type dryers, 3 continuous-pallet-type dryers, 2 flash-type dryers, I tray-type dryer, and I cascade-type dryer. The testing program provided: (I) data for 24 coal- drying operations, (2) information about dried, (3) information about the previous treatment that the coal had received, and (4) information about operating costs. The data obtained through the dryer survey and relationships determined from the data make it evident that all of the types of dryers included in the survey can be operated with the same degree of effectiveness if each type of dryer is used to dry the sizes of coal for which it is best suited. It should be noted that it is usually undesirable and often impossible to dry different sizes of coal in one type of dryer. By use of the data in the report, any prospective dryer user, having determined the surface moisture percentage and screen- size analysis of the coal to be dried, the tons of water to be removed per hour, and the final surface moisture percentage desired, should be able to determine with a fair degree of accuracy: (I) the difficulty of the drying problem, (2) the approximate cost of drying, (3) the required dryer inlet gas temperature and volume and exhaust gas temperature and volume, (4) the type of dryer to use, and (5) the size of dryer required. The method of testing the dryers and determining the difficulty of drying can be used by operators already having dryers to check the performance of their particular dryer and determine whether they are operating effectively. Considerably more information was obtained from the survey of thermal drying than was anticipated when the survey was first considered. However, a great deal of work still remains to be done in the field

Jan 1, 1948

By A. R. Jr. Amos

LOG washers have been used for many years in the washing of clay iron ores, phosphate rock and manganese ores, but not until the past 15 years have they been employed to any extent in the preparation of aggregate materials and fluxing stone. For a machine of such importance where tenacious clay or soft rock must be eliminated, there are few data generally available. The purpose of this paper is to set forth the results obtained from several operations, together with a few suggestions for planning a specific installation. Where the material to be washed out consists of loose surface soil, silt, or small amounts of quickly soluble clay, there is little competition with other forms of washers, because greater power and maintenance are required for the operation of log washers, but where the foreign matter is a stiff clay, such as occurs with high-calcium limestones and in marginal gravel deposits, the ability of other kinds of washers to eliminate com-pletely the hard clay balls is at least uncertain. Then the log washer comes into its own field, for with the breaking and churning action of the logs it will clean out the toughest clay. Even with material from the hydraulic dredge, if it contains tough clay, the log washer is desirable unless the gravel is subjected to a costly soaking and rehandling process. Recently there has been a considerable development in other types of machines to accomplish these results but it is not within the scope of this paper to make comparisons between competitive types, but to present the best obtainable data on log washers only. From the primitive design that gave it its name, a long log hewn from a tree, with paddles forged to shape from strap iron and attached by lag screws, the log washer has gradually been developed to the present all-steel type. As now manufactured, the log washer consists essentially of two built-up logs on which are mounted a series of paddles, carried by shafts fitted at the ends of the logs on bearings fastened outside the enclosing steel box, or trough, which is set at an angle of about 5° to 10° and into which the material is fed. Stuffing boxes at the places where the shafts pass through the box at the lower end are equipped with water-

Jan 1, 1936

By H. K. Work, G. H. Enzian

In the manufacture of steel for commercial purposes, the deoxidation practice used, i.e., the method and degree of deoxidation, is an important factor affecting the structure and mechanical properties of the finished steel. Deoxidation practice exerts a pronounced influence not only on the soundness of the ingots but also on the reaction of the steel to a number of mechanical and thermal treatments. The first mentioned effect of deoxidation is more or less obvious and was first demonstrated, though perhaps not fully appreciated, by Robert Mushet when, in 1856, he added speigeleisen to low-carbon bessemer blown metal. In 1861. Bessemer patented the addition of one pound per ton of silicon to his blown metal to "cause the metal to lie quietly in the mold." The second effect of deoxidation-—that is, the effect on the properties and behavior of the steel—is, one might say, more subtle, and certainly not as well understood as the first, although in many cases it is the more important consideration. This paper is limited to a discussion of only the second effect of deoxidation and: in particular, to the effect on the strain-sensitivity of low-carbon steels. General Discussion Originally it was thought that the function of a deoxidizer was to combine with the oxygen present in the steel as iron oxide and prevent its subsequent evolution as a gas. -More recently it has been realized that a deoxidizer does more than this. Frequent reference has been made to the effect of deoxidizers on the nitrogen in the steel, and some attention has also been paid to hydrogen. As a consequence of the above situation any study of deoxidation must be concerned with the gas content of the steel and the effect of the deoxidizer on the gases involved. The term "gas content" as used here refers to gases extracted from steel during melting in vacuum rather than to elements present in steel in the gaseous state. The extracted gases, at least in the case of oxygen and nitrogen, are generally accepted to be products of decomposition of oxides, nitrides, or other more complex compounds. The manner in which deoxidation affects the gas content of steel and the significance of gases in steel have been and still are subjects of considerable speculation. No attempt will be made here to give a complete discussion of the literature on this subject but a few references will be cited for purposes of illustration. N. Hamilton1 found a correlation between the oxygen content of alloy steel and the behavior of the steel during tube piercing. Davenport, Bain, and others associated oxygen with aging properties of steel while Köster5 and a number of others6-lo made similar claims for nitrogen. Daniloff, Mehl, and Hertyll stated that "deoxidation decreases the susceptibility of steels to aging directly

Jan 1, 1945

By A. J. Lynch, E. V. Manlapig, J. H. Fewings, D. J. McKee

Progress in the development of an automatic control system for the chalcopyrite flotation circuit at Mount Isa Mines Limited is discussed. Preliminary studies have shown that the operating grade/ recovery curve for a sulphide flotation circuit is established by rougher-scavenger behaviour and the operating point on that curve by cleaner-retreatment behaviour. The control strategy of the rougher-scavenger banks involved regulation of xanthate to maintain recovery and control of air to seek the optimum grade/recovery curve. Control of the cleaner circuit to maintain the correct operating point of the plant relative to the ore entering it will be by air. Pulp levels will be used as an additional controllable variable in due course. Sensing instruments include a “Courier” on-stream analyser and several mass flow metering systems each of which contains a magnetic flow meter and a gama gauge. Measurements of concentrate grades and recoveries are made as early as possible in the rougher bank so that a change in the ore entering the plant can be detected as soon as possible. Over a period of six months from initial control systems application, computer control of xanthate resulted in an overall reduction in consumption of 10%. Experimental work has indicated that improved metallurgical performance will result from the introduction of additional air and level control loops.

Jan 1, 1976

OBSERVERS in more than negligible number appear to believe that the achievements of engineers during the last generation have been an affliction rather than a blessing to society. Quite accurately they perceive that scientific progress and technologic advance have reduced to a fraction-often a small fraction-the amount of manual effort required to accomplish a given unit of useful work. They have seen men, as a consequence, deprived of employment in a particular industry; and this so-called technological unemployment they have denounced as inimical to the workers and consequently to the whole social order in progressive nations. To those who subscribe to this thesis the story of the Porphyry Coppers may not make palatable reading, for it is an amazing record of engineering and technologic achievement. But to those others who take the longer and broader view that economic and social progress cannot enduringly lag far behind advance in the realm of science and engineering; and that any improvement in the means and method of doing essential things eventually must make the world a better place in which to live; to these the record of the development of these great mines can- not but be a source of delight. It is an outstanding example of the advantages of mass production coupled with the fruits of scientific research and inventive genius. More, it reflects the pioneer spirit, the initiative, the self-reliance, the independence of thought and action that are traditional with the mining engineer. The word porphyry is a geologic term, the significance of which will be elaborated in later chapters. The essential characteristics of the deposits that are universally, if not quite

Jan 1, 1933

By Blamey Stevens

It is now generally agreed that most metals have been brought to the surface of the earth by volcanic agencies. The question as to how these metals came from the volcanic matrix to the mineral deposit has been often discussed. It might be useful to give more serious consideration to the ultimate origin of the volcanic material. It is possible that some light might thus be shed on the persistent associations of some metals with certain particular kinds of rocks. For example, the very general association of gold with acid types of igneous rocks, of tin with granites or quartz-felsites, of certain types of deep-seated copper-deposits with magnesian eruptives, and so on. One interesting question is as to whether the metals brought near the surface by volcanic agencies appear here for the first time, or whether they came from the central core of the earth. The interior of the earth is, without doubt, much more highly metallic than the crust, and so the core is often thought to be the origin of many of the metals which are uncovered by man. The Differentiation Theory.—Although a great many theories bearing upon these matters have been discussed,' the only one now considered as worthy of much consideration among American geologists is the " Theory of Differentiation of Igneous Magmas."2 According to this theory, lakes of molten magma are supposed to exist very far down beneath the earth's surface. In these lakes a process of differentiation is supposed to be going on whereby the liquid magma is split up into two or more liquid phases. Each of these phases is supposed to take with it the metallic constituents for which it has the greatest affinity.

Jan 1, 1913

By C. A. Worner

THE meeting of the Petroleum Division at the Annual Meeting of the Institute maintained the high standard set in previous years, and attendance of member: of the Division was at a new high. The impact of the war was evident not only in the tone of many of die papers but also in the presence at the meeting of many of our members now serving in the armed forces of our-country. Ken interest was manifested in all papers presented and the discussions which followed developed many additional facts of interist and importance. The first activity of the Division was the joint meeting of the Papers and Programs and the Publications Committees on Monday afternoon; at which time definite plans were formulated for a simplification and co-ordination of the work of the committees.

Jan 1, 1944

By John Cogan

INTRODUCTION Lake tapping is a method of blasting an intake into a body of water from below the natural water surface without first lowering that surface or installing a protective cofferdam around the tap hole. Lake taps are done by first excavating a tunnel almost to the water/rock contact and then blasting out the final protective rock plug at one time to allow water to suddenly inflow into the tunnel from the lake. This procedure can be done "dry" or "wet." In the dry method the tunnel is empty of water before the final plug blast while in the wet method it is partially filled with water. This paper describes a wet method lake tap as performed at Alaska Power Authority's Tyee Lake Hydroeletric Project in southeast Alaska. The Tyee Lake project is located approximately 40 miles southeast of Wrangell, Alaska, in a glacially formed valley called the Bradfield Canal. The project consists of a powerhouse located at sea level on the canal, a system of tunnels and shafts connecting the powerhouse to Tyee Lake at elevation 373 m (1225 ft), and an 129 km (80-mile) electrical transmission line leading from the powerhouse to Wrangell and then Petersburg, Alaska. Tyee Lake itself is a natural lake gouged out of the rock by glacial ice during the last ice age. The objective of the project was to tap into the lake and use the water as a source for power production. The techniques used for lake taps have been developed in Norway where conditions are favorable for their use in hydroelectric proj¬ects. Over 100 have been performed. In the United States the Tyee

Jan 1, 1984

By C. C. Harris

This article presents a general equation describing the xYt surface in batch grinding. This equation contains as special cases most of the relationships which have been deduced from kinetic studies. In an earlier paper an analytical solution of the integro-differential equation of batch grinding was proposed1 as a first approximation of the xYt surface.' A more general equation will be presented here, which appears to combine in a single statement many conclusions reached by experiment. A possible underlying mechanism is that the changing product fineness leads to changes in the particle crushing strength and in the probability of encounter with the crushing media.

Jan 1, 1969

By AIME AIME

This section contains announcements of general interest to the members of the Institute, but not always of sufficient permanent value to warrant republication in the volumes of the Transactions.

Sep 1, 1906

By G. S. Hume

RECENT developments in the Turner Valley gas and oil field, 40 mi. southwest of Calgary, Alberta, have indicated a large producing crude-oil area. Drilling be¬gan in Turner Valley in 1913 but no major developments took place until the fall of 1924, when Royalite No. 4 well at a depth of 3740 ft. in the upper part of the Paleozoic (Mississippian) limestone obtained a production - of 20,000 M cu. ft. of gas with a content of about one imperial gallon of naphtha (73° A.P.I.) per M cu. ft. This well produced as much as 600 bbl. of naphtha per day, and until abandonment in 1934 produced 911,313 bbl., which together with the gas sold was valued at about $5,000.000.

Jan 1, 1937

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Jan 1, 1938