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By J. M. Neilson

The occurrence of iron ore deposits in the State of Western Australia has been known at least since the 1930's,3 but the true significance of the deposits has only come to light within the past four years. Although they are widely distributed throughout the State, it is now known that more than 90% of the available iron ore reserves are located in the "Hamersley Iron Province". Western Australia may well contain the world's largest known reserves of iron ore. Recent reports place this reserve at 15 billion tons and an even higher figure may appear in the future. LOCATION, CULTURE AND COMMUNICATIONS It is difficult to comprehend the immense size of Western Australia (Fig. 1). The State occupies almost one million sq miles and it is more than 2000 miles from north to south. More specifically, it stretches from the 14th to the 35th parallel of latitude south. The Ophthalmia Region in the Hamersley Iron Province is barely halfway up the long dimension of the State. Nevertheless, the region is 800 miles north of Perth, a distance comparable to that from New York to Chicago or to that from Chicago to New Orleans. The Hamersley Iron Province (so named in 1963 to distinguish it from the Pilbara mineral district adjacent to it on the north) covers an area of approximately 30,000 sq miles in the northwestern part of the State. It extends in a roughly oval form from the Indian Ocean to the Gibson Desert of the interior, a distance of about 300 miles. With the exception of the small coastal towns of Onslow, Roebourne and Port Hedland and a few other communities such as the asbestos-mining town of Wittenoom, the region is very sparsely populated. Sheep and cattle stations are scattered thfough the region and these and the main towns are connected by truck tracks and a few main highways. Voice communication is almost entirely by the short-wave radio net operated by the Royal Flying Doctor

Jan 1, 1965

By G. B. Gibbs

Equations are developed which describe the growth of graphite nodules during a-phase graphi-tization under various limiting conditions. When carbon diffusion is rate controlling a modified Birchenall-Mead equation predicts an "apparent activation energy" of 31 keal mole-1 for the parabolic growth constant. If reaction at the graphite or cementite interface is the slowest process growth kinetics are linear and the activation energy must be >50 keal mole-1. A comparison with the experimental observations confirms that carbon diffusion determines the rate of reaction. Apart from minor approximations associated with Lou! carbon solubility in a iron the theory may also be applied to I-phase graphitization. It is well-known that cementite exists as a meta-stable phase in Fe-C alloys and that if a specimen is held at diffusion temperatures for a sufficiently long period the cementite decomposes and graphite is precipitated. Graphitization occurs by the nu-cleation and growth of carbon nodules and several impurity elements catalyze the reaction when present in minute amounts.1 The growth kinetics of nodules have been extensively investigated in the fee ? range2, 3 and recently in the bee a range.1, 4 Experimental growth curves (nodule radius vs time) have slopes which decrease with time, but the scatter of points is generally too great for the precise shape of the curves to be determined with certainty. Birchenall and Mead5 concluded that they are parabolic in ? iron, indicating diffusion control, and that the migration of carbon atoms determines the growth rate. Harris et al, 1 advanced similar ideas for a-phase graphitization. On the other hand, Burke3 chose to regard the initial growth region as a transient followed by a linear law indicating interface control (i.e., cementite decomposition or graphite crystallization as the slowest process). Jeminson and Higgins6 originally considered the initial steep portions of "parabolie" to represent a linear growth law also. In support of these ideas it has been noted that the apparent ac-

Jan 1, 1965

By Dr. O’Neil Thomas J., Donald W. Gentry

Who steals our gold and silver, and copper, zinc and lead? Who takes the joy all out of life and strikes our high hopes dead? Who never wrote a schedule that to anyone else was clear? The sulphur-belching, miner-welching, smelter engineer. -Anonymous From "The Engineer," Engineering & Mining Journal, Apr. 13, 1918 INTRODUCTION A striking characteristic of publications devoted to the principles of engineering economy and investment analysis is that the revenue side of the equation is generally either ignored entirely or addressed only in a superficial manner. This is understandable to a degree in the general case because methods of revenue estimation are highly dependent upon the specific type of project under consideration and the nature of the market served. An important contributing factor, however, is that developing estimates of future sales prices for most products is a risky activity which is less amenable to credible quantitative modeling than other topics in investment analysis. The specific subset of capital intensive investments addressed in this book- mining projects-is particularly sensitive to projections of mineral prices, many of which are notoriously volatile. Furthermore, the unique nature of mineral markets, prices, and product specifications occupies a major role in mineral project evaluation. Even here, however, authors have tended to offer little assistance to the reader in estimating project revenues. For example, the most popular mining engineering textbook for four decades, Elements of Mining (Lewis and Clark, 1967), contains the following advice on estimating future mineral prices (pp. 359-360): "Since the life of the mine will extend over a number of years the future price of mineral products must be estimated in order to calculate the probable profit to be realized. Current prices may be used, but it is preferable to take the average price for the past 25 to 35 years as it covers definite business cycles. Some engineers believe that a mine should make a small profit if its highest-grade ore is marketed at the minimum price during the past 35 years. Business

Jan 1, 1984

By J. L. Ratliff, R. I. Jaffee, H. R. Ogden, D. J. Maykuth

An experimental program was carried out to improve the low-temperature ductjlity of tungsten through the combined use of dispersed oxides for grain-size control and Groups VII and VIII metal additions for matrix softening. Separate binary -alloy studies showed that increasing amounts of finely dispersed thoria or zirconia and critical amounts of rhenium, osmium, and iridium were effective in significantly reducing the ductile-to -brittle bend transition temperature of tungsten as well as in increasing its re crystallization temper - LIKE most of the high-melting point bcc metals, tungsten undergoes a marked transition from ductile to brittle behavior with decreasing temperatures. The material factors which influence the transition temperature include grain size, metal purity, and the presence of dispersed phases. ature and decreasing its recrystallized grain size. The beneficial effects shown by each of these additions on transition temperature and grain size in binary combinations appeared to be additive in tevnary combinations. Thus, combined additions of 2 to 8 vol pct thoria with 5 pct Re, 0.87 pct Os, or 0.30 pct Ir were effective in lowering the transition temperature of tungsten pom 2000 to 75"C, increasing its re crystallization temperature from 1600 to 1800°C, and decreasing its recrystallized gain size from 1175 to 6800 grains per sq mm. The mechanism by which these factors are operable in tungsten is not yet clearly understood. Nevertheless, it has become increasingly apparent that the interrelationship of grain size and matrix composition governs to a large extent the degree of low-temperature ductility which can be achieved. Though it is not possible to accurately assess the relative importance of these variables, the available evidence suggests that, at low temperatures, grain-size effects predominate over purity effects. This was indicated in recent studies by Allen, Maykuth, and Jaffee,' involving single crystals containing 20 to 40 ppm 0 and 1 to 30 ppm C. Thus, while each

Jan 1, 1964

By Joseph A. Holmes, Henry Kreisinger

At the Mining Experiment Station of the U. S. Geological Survey, in Pittsburg, an investigation of the process of combustion is being carried on in a specially-designed furnace having an unusually long combustion-chamber. This work is conducted by a con~mittee consisti~lg of 11. Kreisinger, mechanical engineer; Dr. J. C. W. Frazer, chemist; and Dr..J. K. Clement, physicist. The problem, essentially one of physical chemistry, is estremely interesting to all who are concerned in the burning of coal or the construction of furnaces. The main object of these experiments is to ascertain the relation between the amount of' the volatile combustible driven from the coal and the combustion-spaces necessary to burn it completely. Our best steam-coals vary from 15 to 45 per cent. in volatile matter and from 40 to 75 per cent. of fixed combtistible. The greater part of the latter is burned on the grate: but the volatile combustible leaves the freshly-charsed coal and must be burned in the combustion-space. If this space is not large enough, the volatile combustible mill leave the furnace only partly burnecl, and the result will be a considerable heat-loss and a smoky stack. Strictly speaking, the factor which determines the completeness of combustion of the volatile matter, after it has been mixed with a certain amount of air, is the length of time the mixture is allowed to remain in the combustion-space; but this length of time depends on the extent of the space itself. Let us suppose, for instance, that, when a given coal is burned at a certain standard rate, the volume of the volatile combustible driven oft' per second is 10 cu. ft. Adding, say, 10 cu. ft. of air, the volume of the resulting burning mixture is increased to 20 cu. ft. If the combustion-space is 30 cu. ft., the burning mixture will stay in it,

Jan 1, 1911

By H. J. French

Within the past few years, particularly because of the rapid growth of the airplane industry during the war, considerable attention has been paid to the manufacture of light-wall cold-drawn seamless and welded steel tubing for structural purposes. While the manufacture of such tubing is not, in itself, a difficult matter, some difficulties have been encountered in producing the same under specifications requiring definite physical properties. It is the purpose of this paper to describe the methods of manufacture and the properties that may be obtained by such methods for tubing coming within about 1/2 to 2 in. (12.7 to 50.8 mm.) outside diameter and 10 to 22 Birmingham wire gage (0.134 to 0.028 in. wall thickness). Such tubing is largely used as structural material in the aircraft industry, and it is of the utmost importance that the physical and chemical properties should be known, and also that the various factors entering into the manufacture should be under such control as to allow these properties to be varied and held within definite limits. In general, tubing may be divided into four classes: namely, specialty tubing, such as riveted-sheet or plate, lock jointed, etc.; brazed tubing; welded tubing; and seamless tubing. Welded tubing may be divided into hot product, such as lap welded and butt welded, and cold product, such as acetylene and electric welded. Seamless tubing may be hot rolled or cold drawn. Specialty Tubing The first two classes present mainly mechanical or structural engineering problems. A simple form of tube is made by riveting together the overlapping edges of rolled sheets or plates formed into a cylinder. Because of the nature of its construction, such a tube is necessarily limited to relatively large sizes. Lock-jointed tubing is produced by passing low-carbon strip through a forming machine having suitable rolls and dies, its manufacture is almost entirely a question of design of the forming machine and its satisfactory operation. The chief application of such tubing is in the manufacture of bedsteads.

Jan 1, 1920

By M. Gensamer

ALTHOUGH a large number of X-ray photograms of cold-rolled steel have been published, two circumstances have led to the experimental work reported in this paper. The first is that no complete study, making use of the pole-figure method of Wever1, has been made of cold-rolled low-carbon steel. Wever has published pole figures of mild steel sub-jected to plane parallel deformation1,2 and undoubtedly he has applied the method to cold-rolled mild steel, but the authors have not found these data published. Kurdjumow and Sachs3 have applied the method to the study of rolling and recrystallization textures in electrolytic iron; their results will be referred to later. The reason for this dearth of papers using the pole-figure method is obvious; a greater number of photograms and more analytical work (although this work is quite simple and straight-forward) are required to construct a pole figure than most investigators have felt worth while, despite the fact that no other method of which the authors are aware will satisfactorily depict the orientations of the crystal-lites in a polycrystalline aggregate. The second circumstance that led to the work reported in this paper was the appearance of a paper by Wayne A. Sisson4 on the same subject. In his valuable study of the factors influencing the development of pre-ferred orientations in cold-rolled mild steel, Sisson made one observation that required confirmation; that is, that at some stage of the rolling proc-ess the type of preferred orientation changed from the type that gives a photogram characterized as a "six-point" X-ray pattern to that known as a "four-point" pattern. A similar observation had been made by Tam-mann and Heinzel5, who studied the orientations developed in the rolling of steel by the specular reflection of light from the etched surface of rolled samples. These workers also found that the type of preferred orientation

Jan 1, 1936

By Jay R. Burns

TWO magnesium sand-casting alloys are commonly favored in the United States. These are referred to as H and C alloys (Dow Chemical Co.) or 4Mz65 and AM260 alloys (American Magnesium Corporation). Both are of an aluminum-zinc-manganese type. H alloy contains 6 per cent aluminum and 3 per cent zinc and is characterized by relatively good toughness. C alloy contains 9 per cent aluminum and 2 per cent zinc and is employed where high yield strength and pressure tightness are required. Examination of magnesium castings poured in Europe and England,'J however, demonstrates that H and C alloys are replaced by .%8 and AZ~I, respectively. That is, A8 reprcsents a magnesiurn alloy having superior toughness while A291 is suitable for high yield strength and pressure-tight applications. The basic difference between the .Ameri-can and European alloys is that the foreign alloys employ a somewhat higher aluminum content and less zinc than is found in H and C alloys. The mechanical properties of the alloys, when divided into high and low-aluminum groups, are quite similar, as determined from separately cast foundry-control type test bars ,In this paper the decrease of mechanical properties caused by any given amount of microporosity is measured for H, C, A8, and AZ~I alloys. The relative susceptibility of each of the four alloys to microporosity is also determined. Typical mechanical properties and nominal chemical analyses are reported in Table I. The apparent similarities between the two alloys in each group have led to considerable discussion as to the relative merits of each of the compositions.2 Popular points for comparison between the alloys have been the relative susceptibility of each of the four alloys to microporosity6 and the effect of this microporosity on their mechanical properties. It is primarily intended, in this paper, to show the

Jan 1, 1946

By Gifford White

Considerable attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current techniques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alternating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,s and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what typc of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effeet arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

By Chester Purington

THE AUTHOR hopes that this paper will meet with criticism and debate by fellow members of the Institute rather than with that attitude of passiv-ity and indifference which one is inclined to adopt when considering a field completely foreign to one's own experi-ence. After several years of study of voluminous literature, maps, and statistics, and many personal journeys and field inspections of various parts of Siberia, the conclusion is reached .that the area adjacent to the Stanovoi, Zhugd-Zhur, and Yablonoi ranges as below defined is that which .is most accessible to the western world and will soonest give results from exploration. HISTORY The first incursion of the Russians into Siberia east of the Yenesei River appears to have been in 1632 when the fort of Yakutsk was founded on the middle Lena. The early expeditions were in quest of furs. As the Siberians say, "the sable beckoned" and the post of Anadyr was founded in 1639, two thousand miles further northeast. Thus nineteen years after the Pilgrims landed in Massachusetts, the Russians had established a trading post within 700 miles of what is now the town of Nome, Alaska. Parties of Cossaks penetrated to the shores of the Okotsk1 Sea early in the seventeenth century, but it was not until 1688 that the town of Okotsk was founded. In 1712 a grand project was elaborated at St. Petersburg for building a port at Okotsk, but it came to nothing. Vitus Bering, the Alaska explorer, built ships at Okotsk, and made this his point of depar-ture. It is stated that the iron work used in these ships was brought overland partly from Yakutsk, and partly even from St. Petersburg, 5500 miles away. Accord-ing to report a copper deposit was worked on the river Urak, not far from the coast, and copper was smelted for sheathing the bottoms. Grassgrown mounds con-taining slag and shots of copper were inspected by the writer last summer, at the site of the ancient shipyard.

Jan 11, 1923

CHARGING of an open-hearth heat is begun as soon as possible after the previous heat has been tapped. Ordinarily, about 40 min is required to drain and dress the furnace hearth, make up the taphole, and perform routine repairs of the banks. Repairs to the upper back wall and to the front wall and jambs can ordinarily be done while the first scrap charge is being heated and are therefore allowed to wait in order to save furnace time. Any major repairs required on the hearth or other parts of the furnace necessitate longer delays because such repairs must be made while the furnace is empty. Although charging practice varies considerably in detail with the type and proportions of scrap and iron used, many factors are common to all varieties of charge. Such general considerations are dealt with first. CHARGING EQUIPMENT AND STOCK HANDLING The physical equipment available for loading and weighing the stock, transporting it to the furnace, and charging it, may have a major effect on charging practice. Limestone, scrap, and all other solid melting stock are charged mechanically by means of equipment illustrated in Fig 2-1. The charging of hot metal is shown in the background of this figure. Mechanical equipment and plant layout for stock handling are described in Chapter 1. It is generally desirable to charge the scrap about as fast as the physical volume can be put into the furnace. Charging scrap that is too heavy or adding the charge too rapidly (less than 45 min) may be detrimental to melting rate because of excessive chilling of the entire furnace system and also because of poor conduction of heat to the lower layers in the furnace; but the more common problem is the reverse one of charging light 'scrap fast enough to maintain a normal heat time. A limiting factor may be the height to which the scrap may he piled in the fur-

Jan 1, 1951

By Noel Stearn

WHEN the Age of Machinery was suddenly thrust upon civilization about the beginning of the 19th century, an unprecedented demand for mineral resources sprang up. This demand brought about the rapid development of the known ore deposits and the discovery of such other deposits as could be encountered by energetic and canny prospectors. Thus in the countries now reasonably accessible nearly all orebodies have been located except those which are totally concealed even from the eyes and "senses" of experienced and expert prospectors. The high rate of exhaustion of known ore deposits and the necessity of looking farther and farther ahead for raw materials as a matter of insurance on the stupendous capital outlays involved in mining, development, and conversion operations, have resulted in exceptional activity in three different fields of effort. The first is purely geographic. Prospectors are now penetrating the few hitherto inaccessible regions in the hope of stumbling upon exposed ore deposits or locating visible indications of their presence. The second is chemical. Industrial chemists and metallurgists are seeking to facilitate the exploitation of lower grade ores or to find methods of recovering valuable metals from common substances. In the third field of effort lie the activities of the economic geologist and the mining engineer, who endeavor to locate concealed ore deposits which would remain hidden from the prospector no matter how expert or conscientious he might be. Obviously the task which such a man must face is both exacting and indefinite, and the tools which he has heretofore been permitted to bring to it are, for the most part, abstract-a knowledge of certain fundamental principles and processes involved in the origin, occurrence, structure, and distribution of deposits of natural resources and of the rocks which form the environments of those deposits; and a process. of reasoning by analogy supplemented by the use of the diamond drill, or such artificial exposure as -the test pit, trench, shaft, or tunnel.

Jan 1, 1928

By James W. Shaffer

Aluminum is the most abundant metallic element of the earth's crust and is a constituent of nearly every type of rock (Clark, 1924, p. 13). The sources of aluminum and aluminous material most commonly used by modern industry are the bauxitic raw materials consisting of bauxite, bauxitic clay, and aluminous laterites. These are mixtures of hydrated aluminum oxide minerals and mineral impurities. End Uses Bauxite is used as an aluminum ore and in the manufacture of refractory products, aluminous chemicals, and abrasives. Other raw materials are used for aluminum ores, but their use is minor compared to bauxite. Refractory products made from bauxite are synthetic mullite, high-alumina fire bricks, castables, monoliths, cements, and ramming mixes used by the iron, steel, and cement industries. Chemicals made from bauxite are aluminum sulfate and sodium aluminate for water treatment and aluminum chloride used in refining crude petroleum. Among the abrasive products made from bauxite are coated abrasives, sharpening stones, and grinding wheels. Special grades of bauxite are used in the decolorization and clarification of raw sugar and lubricating oils. Bauxite has been used for road surfacing but mainly because other material was not more readily available. Perhaps the oldest use of bauxite and aluminous laterite is for a building stone. Ancient temples and more recent structures in India have been made from these and some varieties are suitable for decorative stone. Geology Mineralogy and Properties – Bauxite is a mineral raw material composed principally of one or more hydrated aluminum oxide minerals and impurities of silica, iron oxide, titania and elements in minor or trace amounts. The hydrated aluminum oxide minerals are gibbsite, boehmite and diaspore. Corundum is not included as a bauxite mineral although it does occur in some bauxite deposits. Boehmite and diaspore are both alumina mono-hydrates and have essentially the same composition, but diaspore has a greater hardness and a higher specific gravity because of a more tightly bonded and compacted atomic structure. Gibbsite is an alumina trihydrate mineral. Properties of bauxite minerals are shown in [Table 1].

Jan 1, 1975

By John Goheen

RECENTLY the head burner at a brick. plant with over 40 years' experience said that he had burned brick by guess for over half his lifetime and had used pyrometers for 2 1/2 years but hoped that he would never have to burn kilns without pyrometers again. The ceramic engineer in making a special study of the burning of clay ware and the effect the heat of the kiln has on color and vitrification is also rapidly placing the burning of clay on a twentieth-century basis. Clay ware may be divided into various groups, brick and drain tile; sewer pipe; firebrick; and pottery, which, in turn may be subdivided into special classes. As nearly as the analysis of the clay type of kiln, etc., will allow, there are practically the same problems to solve in burning in all of the processes or operations. The underlying objective is the same, namely the production of the best grade of ware under the most efficient and economical manufacturing system. The principal problem in the production of clay ware is the burning off of the kilns. The most modern steam shovel may dig the clay and the most advanced types of pug mills and wire cut machines or molds of various kinds may be installed, but unless the drying and burning of the ware is successful, all of the previous operations will be useless. On this final operation depends the entire result of the plant. In reality, burning of all. clay ware is purely a heating proposition. The kilns, or furnaces, should be so designed as to give equal distribution of heat. Consequently, the problems of design and construction of kilns to produce equal distribution of heat require serious consideration, as do also the questions of heat control and draft control. The three most important factors in the burning of practically all types of kilns may be

Jan 9, 1919

MARCEL R. DALY (communication to the Secretary?).-The fundamental disagreement between Eugene Coste and the writer proceeds essentially from the contradictory views they hold on the origin of petroleum. This difference cannot be bridged, nor can inorganic and organic theories be discussed here. The writer has suggested that the proper thing in such a case would be to agree to disagree. Coming to the detailed objections further presented by Mr. Coste, the writer feels that, in the main, they take their source in a wrong interpretation of the theory, and the writer is sometimes too generously invested with views that are not his own. 1. The only requirement for the theory is that the oil proceeding from organic remains be distributed in a water-laden sediment, and that this sediment be submitted to the increasing compression due to the continuous accumulation of superimposed strata, which would tend to squeeze out the liquid contents (p. 1152). This squeezing out would be further aided by the distortion of the strata (p. 1148, a). Nothing here makes impossible the slow formation of the oil, if this is considered necessary, as the piling up of the strata in the syncline would require by itself a protracted length of time, and, further, the squeezing-out process is a slow one. Possibly the formation of the oil may even continue during part of the process of distortion. But the mode of formation of the oil and the time and temperature required for it are left to the chemist to decide. The diastrophic theory, which is essentially a theory of motion and accumulation dependent on the laws of mechanics, is not directly concerned with them, provided the general points heretofore outlined be agreed upon. Perhaps it would be wise not to claim too many "eons" for the formation of the hydrocarbons, if the statement made by Sir Boverton Redwood is correct that "the coral reefs of the Red Sea are charged in places with recent petroleum, formed in that torrid climate from the swarming organisms occupying the shallow pools."1

Jan 5, 1917

By Gifford White

CONSIDERABLE attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current tech-niques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alter-nating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,8 and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what type of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effect arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

By Noel H. Stearn

When the Age of Machinery was suddenly thrust upon civilization about the beginning of the 19th century, an unprecedented demand for mineral resources sprang up. This demand brought about the rapid development of the known ore deposits and the discovery of such other deposits as could be encountered by energetic and canny prospectors. Thus in the countries now reasonably accessible nearly all orebodies have been located except those which are totally concealed even from the eyes and "senses " of experienced and expert prospectors. The high rate of exhaustion of known ore deposits and the necessity of looking farther and farther ahead for raw materials as a matter of insurance on the stupendous capital outlays involved in mining, development, and conversion operations, have resulted in exceptional activity in three different fields of effort. The first is purely geographic. Prospectors are now penetrating the few hitherto inaccessible regions in the hope of stumbling upon exposed ore deposits or locating visible indications of their presence. The second is chemical. Industrial chemists and metallurgists are seeking to facilitate the exploitation of lower grade ores or to find methods of recovering valuable metals from common substances. In the third field of effort lie the activities of the economic geologist and the mining engineer, who endeavor to locate concealed ore deposits which would remain hidden from the prospector no matter how expert or conscientious he might be. Obviously the task which such a man must face is both exacting and indefinite, and the tools which he has heretofore been permitted to bring to it are, for the most part, abstract—a knowledge of certain fundamental principles and processes involved in the origin, occurrence, structure, and distribution of deposits of natural resources and of the rocks which form the environments of those deposits; and a process of reasoning by analogy supplemented by the use of the diamond drill, or such artificial exposure as the test pit, trench, shaft, or tunnel.

Jan 1, 1929

FOREWORD A SERIES of papers on strategic and otherwise important mineral products was prepared some ten years ago under the joint auspices of the Committee on Foreign and Domestic Mining Policy of the Mining and Metallurgical Society of America and the Committee on Industrial Preparedness of the American Institute of Mining and Metallurgical Engineers. These papers were later published in a joint volume entitled International Control of Minerals (1925). Amongst them was one on manganese. The Subcommittee on Manganese prepared its paper in two forms. One was intended for inclusion with the series above referred to and approached its subject more particularly as an international problem. The other dealt more definitely with manganese as an element in the problem of national defense. This last was first written under date of January 24, 1924 as a confidential report, for and at the request of the War Department. It was later released and published, in slightly modified form, as a separate pamphlet by the Industrial Preparedness Committee of the American Institute of Mining and Metallurgical Engineers. After the lapse of eight years, in view of the vital position of manga-nese in the problem of industrial preparedness against a war emergency, the War Department made a request to have the conclusions of 1924 reviewed and brought up to date. To comply with this request the manganese subcommittee was reconvened (with a somewhat changed personnel) and exhaustive studies were once more made of the entire subject of manganese. A new report, with specific recommendations, was submitted to the War Department in February, 1932. This second report is now herewith released for publication. Certain specific conclusions and recommendations as expressed to the War Department are omitted. Otherwise the report stands as prepared and submitted by the manganese subcommittee of 1931. The members of this committee were: C. Minot Weld, Chairman, R. C. Allen, Arthur S. Dwight, J. W. Furness, D. F. Hewett, Reno H. Sales, Theodore Swann and Scott Turner. ARTHUR S. DWIGHT, Chairman, Committee on Industrial Preparedness.

Jan 1, 1933

A SERIES of papers on strategic and otherwise important mineral products was prepared some ten years ago under the joint auspices of the Committee on Foreign and Domestic Mining Policy of the Mining and Metallurgical Society of America and the Committee on Industrial Preparedness of the American Institute of Mining and Metallurgical. Engineers. These papers were later published in a joint volume entitled International Control of Minerals (1925). Amongst them was one on manganese. The Subcommittee on Manganese prepared its paper in two forms. One was intended for inclusion with the series above referred to and approached its subject more particularly as an international problem. The other dealt more definitely with manganese as an element in the problem of national defense. This last was first written under date of January 24, 1924 as a confidential report, for and at the request of the War Department. It was later released and published, in slightly modified form, as a separate pamphlet by the Industrial Preparedness Committee of the American Institute of Mining and Metallurgical Engineers. After the lapse of eight years, in view of the vital position of manga-nese in the problem of industrial preparedness against a war emergency, the War Department made a request to have the conclusions of 1924 reviewed and brought up to date. To comply with this request the manganese subcommittee was reconvened (with a somewhat changed personnel) and exhaustive studies were once more made of the entire subject of manganese. A new report, with specific recommendations, was submitted to the War Department in February, 1932. This second report is now herewith released for publication. Certain specific conclusions and recommendations as expressed to the War Department are omitted. Otherwise the report stands as prepared and submitted by the manganese subcommittee of 1931. The members of this committee were: C. Minot Weld, Chairman, R. C. Allen, Arthur S. Dwight, J. W. Furness, D. F. Hewett, Reno H. Sales, Theodore Swann and Scott Turner. ARTHUR S. DWIGHT, Chairman, Committee on Industrial Preparedness.

Jan 1, 1933

By George K. Burgess, Robert A. Hadfield

1. Introduction.—The methods of production of sound steel ingots have been described in several papers read recently before this Institute. It was thought by Director Stratton, of the U. S. Bureau of Standards, and ourselves to be of sufficient interest and importance, as a further contribution to this subject, to compare the properties of rails rolled in one mill according to American practice, from several types of ingot of substantially the same chemical composition but cast by several processes; and to compare in considerable detail the properties of an ingot manufactured by the Hadfield special-feeding process and one of the usual type for rolling into rails. We are greatly indebted to F. W. Wood, President of the Maryland Steel CO., who made this investigation possible by kindly placing his rail mill at our disposal; and he and his associates at Sparrows Point did everything possible to make the experiment a success, including the execution of several of the tests and analyses. 2. Classification and Manufacture of Ingots.—Of the ingots used in this investigation, eight were made in Sheffield and furnished by Sir Robert Hadfield, and one was made and furnished by an American steel company,l as a comparison ingot, and was supposed to represent the usual type of ingot from which rails are made. The characteristics of the ingots are given in Table I. Ingots 1, 2, 3, and 4 were cast large end up and fed by the Hadfield method in the usual manner with charcoal and blast continued until the molten steel has set on the top of the head, say varying from 20 to 40 min. To ingots 1, 2, and 4 was added 0.1 per cent. aluminum, and to the nickel-chrome ingot, No. 3, 0.125 per cent. For sake of comparison, there were also included two ingots, Nos. 8 and 9, cast with the small end up and fed by

Jan 1, 1915