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By S. P. Ray, B. D. Sharma

THE activation energy values for self-diffusion in pure metals have been correlated with a number of physical properties such as melting points,1 valences,' Debye temperatures,3 and cohesive energy densities.4 Extending the melting point correlation, the self-diffusion activation energy values for the alloys can be similarly correlated with the solidus temperatures. For metals and alloys which exhibit phase transformations, such a correlation is not feasible because of the uncertainty of various physical properties of the corresponding phases. Using thermodynamical approach, Ardell5 calculated the hypothetical melting points of the low melting phases of the polymorphic metals. However, these calculated melting points do not show reasonable correspondence with the activation energy of self-diffusion. Recently, a new approach treating metals and alloys as electron concentration phases has been developed by Engel6 and Brewer.7 These workers have attempted to correlate the crystal structures with the electron configurations of the atoms existing either in ground state or in an excited state of low promotion energy. The basic postulate of this theory is that whereas the contribution to the bonding of the metal comes from the interaction of both d and (s-p) electrons existing either independently or in hybridized states, the existing crystal structure is controlled by the (s-p) electrons alone. Specifically, a metal is supposed to crystallize in bcc, hcp, or fcc phase provided the metal has one, two, or three valence electrons per atom in the (s-p) configurations. The diamond, or ZnO and ZnS structures, occur with four (s-p) electrons per atom. Secondly, the contribution of d electrons to bonding is supposed to increase with atomic number

Jan 1, 1970

By J. Donovan Jacobs

An underground excavation project usually is a highly organized complex of different but interrelated construction activities. It is the whole effort, including the necessary tools, which will be referred to as the System. Tunnel-driving and shaft-sinking operations are among the most systematic of construction efforts. Systems are not new in the performance of construction. It is the Systems Concept which seems only recently to have been discovered and made the subject of much study and discussion. HISTORICAL From the seventeenth century, when explosives were first utilized for rock excavation, until the successful application of the rotary-head continuous tunneler in this decade, the cyclical drill-blast-muck-support method has been standard tunnel-driving procedure throughout the world. Whatever improvements occurred were the result of development of better tools for performing the various operations of the cycle. The electric locomotive replaced the mule and permitted the use of larger muck cars. The steam drill, which ended the day of the double jack, was itself quickly made obsolete when compressed air replaced steam as the source of drilling energy. Power shovels were introduced to save the time and money involved in the hand-loading of excavated materials. A cubic yard of rock tunnel muck can be excavated today for just half the man-hours of labor required in 1948. Developments over 20 years which cumulatively have resulted in this economy include: drifter drills mounted on hydraulically controlled booms and positioners; tungsten-car- bide-tipped bits; long feed shells on the drifters, making it possible to drill the full depth of a round without changing steel; better designed,

Jan 1, 1970

By B. M. Bird

DURING the past four years the experimental work in coal washing carried on by the U. S. Bureau of Mines and the University of Washington has been devoted mainly to the development of special methods for the tabling of fine sizes of coals that are difficult to wash. One important outgrowth of this investigation has been the application of hindered-settling classification to coal tabling. Although used for many years in ore dressing, the term "classification" as used here may be new to many readers. It may be defined as the separation obtained when a bed of particles is held in a uniform state of suspension in an upward current of water, either continuous or pulsating, just sufficiently strong to keep the bed in a mobile condition. A common example of this type of separation is a jig in which there is no suction stroke. When the hindered-settling classifier is used with the coal-washing table, the fine-size raw coal, instead of being fed direct to tables, as is the prevailing practice, is first fed to the classifier and grouped, according to the rate of settling against the upward current of water, into perhaps six separate products. After dewatering, each of these except the sixth, a refuse product, is elevated to a seperate feed bin and washed on a separate table. This paper gives a brief discussion of the basis for the use of hindered-settling classification of a table feed; a description of the experimental work; a comparison of the results obtained with and without classification; and a discussion of the application of the classifier in commercial coal washing.

Jan 1, 1928

By Oliver B. Hopkins

During 1931 Peru maintained its position as the ninth oil-producing country of the world, with an output somewhat greater than that of Trinidad and Argentina, and considerably less than for Colombia and Mexico. Outside of the three old producing fields, there was little or no activity of importance; no new areas were brought in and no extensive wildcat drilling was done. On the other hand, the old fields continued to produce at a rate only slightly below normal and such restriction as existed may be attributed to market and not to field conditions. Political disturbances during the spring led to several strikes in the field, causing temporary suspension of activities there. However, such troubles were of short duration and no permanent loss of production was sustained. The production in barrels during the past three years for the three coastal fields of Peru has been as follows: The oil industry in Peru is relatively old; 29 wells were drilled in the Negritos area between 1888 and 1898. Prior to 1900 the production was relatively insignificant but from 1900 until 1929, it has slowly but steadily increased to a maximum annual production of over 13,000,000 bbl. The potential production of the fields since 1939 has exceeded the production of those years; the actual production has been controlled by market conditions. The production of the property of the International Petroleum CO. since 1900 has been just over 100,000,000 bbl. The production from the Peruvian fields will doubtless remain for some years at approximately the same level as during the past few years.

Jan 1, 1932

The John Fritz Medal was awarded in January, 1916, to Dr. Elihu Thomson, "For -Achievements in Electrical Inventions, in Electrical Engineering, and in Industrial Development, and in Scientific Research." The medal will be presented to Dr. Thomson at a meeting, to be held in Boston on Friday evening, Dec. 8, 1916, in the Central Lecture Hall of the new buildings of the Massachusetts Institute of Technology. The program of the evening will include adresses by John J. Carty, Chairman of the Presentation Committee of the Board of Award, E. W. Rice, Jr., President, General Electric Co., and Dr. Richard C. Maclaurin, President, Massachusetts Institute of Technology. The presentation will be made by Dr. Charles Warren Hunt, Chairman of the Board at the time the award was made, and the ceremonies will conclude with the response of Dr. Thomson. The John Fritz Medal is awarded from time to time for notable scientific or industrial achievement, and was provided for in a fund subscribed in memory of the great engineering pioneer, John Fritz. The award of the medal is made by a permanent board composed of four members from each of four American National Engineering Societies, namely, the American Society of Civil Engineers, the American Society of Mechanical Engineers, the American Institute of Mining Engineers and the American Institute of Electrical Engineers. The members of the 1916 Board are: CHARLES WARREN HUNT, Representing the A. S. C. E., JOHN A.. OCKERSON, GEORGE F. SWAIN, CHARLES D. MARX. JOHN R. FREEMAN, Representing the A. S. M. E., AMBROSE SWASEY, JOHN A. BRASHEAR, FREDERICK R. HUTTON. ALBERT SAUVEUR, Representing the A. I M. E., E. GIBBON SPILSBURY, CHARLES F. RAND, CHRISTOPHER R. CORNING.

Jan 12, 1916

By Carl E. Reistle

ENGINEERS as a group are often criticized because they have been responsible for the development of many technical improvements only to allow the administration of them to pass into the hands of others who may have little understanding of how they operate and little competence in their use. These criticisms are not always justified. There are many engineers who have shown themselves to be great administrators in addition to being great creators or builders, and more and more one sees the engineer demonstrating unusual administrative ability as he moves into the executive ranks. The last five or ten years have seen a new movement developing in this country-a movement brought about through the recognition by business statesmen that successful business administrators and executives just cannot be expected to develop like Topsy, that the management of a company must deliberately take steps to cultivate the proper climate or environment for growth if it wishes to provide an adequate and capable succession of executives in the future. This movement has taken on a number of names-Management Development, Executive Development, Personnel Development-but are these not actually misnomers? Can we develop anybody? In the strictest sense of the word, the author doubts that anyone can change any other person, at least, not much. The change must come from within. Perhaps this movement should be looked at not as a program of developing people but as one of giving people an opportunity to develop themselves. In the Humble Oil & Refining Co. there is an Executive Development Program; maybe it might better be called a Program of Development for Executives.

Jan 8, 1954

By F. D. George, M. J. Salkind

Al3Ni whisker-reinforced aluminum was found to exhibit good Charpy impact toughness and little notch sensitivity even though its room-temperature tensile elongation parallel to the whiskers is only 2 pct. This impact behavior was maintained d liquid nitrogen temperature (-196"C). It is postulated that this behavior is due primarily to the presence of the continuous aluminum matrix which provides sufficient 10calized ductility in the vicinity of the crack tip to absorb considerable energy from the advancing crack. The impact behavior of Al-Alni was found to be quite anisotropic. Of six orientations studied, the transverse orientation having the notch normal to the whisker axis was found to exhibit the lowest impact energy, whereas the transverse orientation having the notch parallel to the whisker axis was found to exhibit the highest impact energy. A significant differnce was noted between the impact behavior of material containing needlelike whiskers and that containing bladelike whiskers. Only two of the six orientations studied exhibited complete fracture for the material containing needlelike whiskers. On the other had, most of the specimens containing bladelike whiskers exhibited complete fracture. It was postulated that the bladelike whiskers block transverse flow, thus reducing the amount of plastic deformation ahead of the crack tip. One of the more significant advantages of composite materials is the prospect of combining high strength with toughness. In general, toughness is associated with materials which exhibit considerable ductility and can deform plastically in the presence of a stress concentration. Very strong materials which resist plastic deformation generally exhibit low toughness. At first glance, then, it would appear as though strength and toughness are mutually incompatible so that useful engineering materials would have to be a compromise between the two. One approach to the problem of combining the high intrinsic strength of ceramics with the toughness of metals was to mix them together to form a cermet. Unfortunately, the toughness of cermets was found to be rather disappointing. Whisker reinforcement of metals, however, appears to be a more promising approach. It has been demonstrated that whisker-reinforced metals produced by unidirectional solidification exhibit enhanced strength due to the presence of high strength nonmetallic whiskers. The total strain capacity of these composites in the direction of fiber alignment is limited to that of the fibers, the matrix being unable to carry the load once the fibers have failed. A characteristic, then, of whisker composites is low ductility in the direction of whisker alignment, on the order of a few percent elongation. This low elongation, which is usually associated with brittle behavior, should not be taken as an indication of low toughness. Such a material can exhibit significant ductility in directions other than parallel to the fibers7 and can therefore possess significant intrinsic toughness. Toughness in a fiber-reinforced metal is derived from several mechanisms. The first is due to the toughness of the matrix itself. A continuous ductile metal matrix can act as an effective crack arrest medium by undergoing localized plastic deformation. Cracks initiated from the surface of the composite or from a brittle fiber failure must travel through the matrix before reaching another brittle phase particle. A second crack arrest mechanism peculiar to fiber composites is due to the fact that, as a crack travels through the matrix and approaches a fiber, the plastic deformation ahead of the crack tip will result in loading of the fiber. This causes the matrix shear strength in the plastic zone to be apparently higher, thus extracting more energy from the crack and diverting the crack at an angle to the original direction of propagation. A third crack arrest mechanism occurs in fiber composites which exhibit a weak bond between fiber and matrix. The idea was proposed by Cook and Gordons that if a crack propagating transversely in a fiber composite were made to turn and run along the fibers by decohesion of the fiber-matrix bond, then toughness would be imparted by the blunting of the crack tip and the creation of new surfaces. The last mechanism, interfacial decohesion, is commonly noted in naturally occurring fiber composites such as wood, bone, and bamboo, and has been observed in man-made composites such as glass fiber-reinforced resins,g silica fiber-reinforced aluminum," laminated steel," and tungsten and silica fiber-reinforced electroplated copper.'' The first mechanism, crack arrest by plastic deformation in the matrix, has been noted in tungsten wire reinforced cast copper." The purpose of this investigation was to quantitatively assess the toughness of a whisker-reinforced metal as a function of orientation. Previous investigation considered only cracks propagating nominally perpendicular to the reinforcement. In this investigation, crack propagation in three mutually perpendicular directions as well as three intermediate orientations was investigated. The system chosen for study was the unidirectionally solidified A1-A13Ni eu-tectic alloy which has a microstructure consisting of 10 pct by volume of A13Ni whiskers in a matrix of aluminum This material exhibits two different kinds of whisker morphology, depending upon the rate at which it is solidified.' At low rates of solidification (less than 2 cm per hr) the whiskers are bladelike, whereas at higher rates of solidification they are

Jan 1, 1969

By D. C. Buffum, L. D. Jaffee

QUANTITATIVE measurements of the temper brittleness of steel are made by comparing the difference between embrittled and unembrittled specimens in the temperature of transition from ductile to brittle fracture. Since hardness affects the transition temperature, a study of the combined effects of hardness and temper brittleness appeared desirable. In this investigation a commercial SAE 3140 steel, which has been reported on previously in temper brittleness studies,* was used. Blanks from this steel were austenitized for 1 hr at 900°C and water quenched. The blanks were then divided into six groups and further heat treated as follows: Group 1—tempered at 675°C for 4 hr and water quenched; Groups 2, 3, 4, and 5—tempered at 675", 650°, 625', and 600 °C respectively for 1 hr and water quenched; and Group 6—tempered at 500°C for y2 hr and water quenched. Each of these groups was divided into two parts; one part was tested without further heat treatment, and the other was embrittled for 48 hr at 500°C and water quenched. Tempering treatments between 500" and 600°C were avoided because of the rapid embrittlement occurring in that range for this steel. The heat-treated blanks were machined into standard V-notched Charpy bars. Each group was tested over a range of temperatures on a 217 ft-lb Charpy machine. The energies necessary to fracture the bars and the percentage fibrous fracture of each bar were recorded. The transition temperatures were obtained from a plot of the percentage fibrous fracture as a function of testing temperature. They were taken as the lowest point on these curves at which the fracture was 100 pct fibrous. The transition temperatures for both embrittled and unembrittled specimens are presented in Fig. 1 as function of the hardness. It will be noticed in this figure that the point for the unembrittled condition at 21 Rockwell C is out of line. These specimens were tempered for 4 hr at 675 °C and this point indicated that under isothermal conditions at this temperature, as is well known, embrittlement may develop fast enough to more than offset the effects of softening. From this data, it was concluded that the difference between transition temperatures for the embrittled and unembrittled conditions at any given hardness, within the range of Rockwell C 24 % to 32lh, is constant. It is also concluded that, within the hardness range studied, the transition temperatures for embrittled and unembrittled specimens rise in a parallel fashion with an increase in hardness. The authors wish to acknowledge the assistance of Frank Carr in this work.

Jan 1, 1952

By C. Augustus Carlow

THE subject which has been allotted to me is so vast and far-reaching that it is impossible to deal adequately with it in the time available. A complete survey would occupy the spare time of any one man for many years, whereas the time available to me is measured in weeks In the circumstances, I have been fortunate in securing the aid of several willing collaborators, and shall endeavor to re present such information as presently exists in published form, examine the situation critically in the light of present-day conditions, and arrive at certain conclusions' which I shall venture to put forward for your consideration No one who has lived through the past 25 or 30 years, and who has witnessed the amazing achievements of recent scientific research, would venture to deny the possibility that new sources of energy-may yet become available, or to prophesy to what extent these may be harnessed to the service of mankind So far as we can see, however, coal, as a source not only of power and heat but also of that wonderful range of derivatives that form the raw materials of so many industrial processes, must continue to play a vital role in our economic life It is the chief mineral fuel, exceeding all other mineral resources in value, production and demand In value coal overshadows the industrial metals, while of the sources of energy-coal, oil, gas and water power-the first named is the most important Thus, for example, in the United States, coal as a fuel (that is, as a source of heat and power) is still predominant, the figures of percentage of

Jan 1, 1947

A. A. CENTER*—This paper reminds me of the beginning of the work of the Electrolytic Zinc Company of Australasia. Early work for this Company, as some of you may know, was done at the Bully Hill Plant in California. After working there for some time Herbert Gepp, now Sir Herbert, came to the Anaconda Co. plants in Montana where I met him. He spent some months there, in fact almost a year if I remember rightly. That was when we were breaking in the new electrolytic zinc plant at Great Falls, Montana. From there he went back to Australia and started in on the plant there. I believe they had an original plant of about 20 tons per day of cathode zinc. We heard from them for some time, until they were able to go along on their own, and they have done very well ever since as you have heard. Their practice, (the flow sheet, the leaching practice), has been quite different as reported in the paper and apparently they are still following that practice to some extent. While the earliest work on selective flotation was done down in Australia, the big companies there, strange to say, were far behind the American companies in taking it up; and it is only in comparatively recent years they have gone to the alkaline circuit and dropped out thereby more of their iron and lead. The zinc plant now is up to a capacity of 100,000 tons a year and I believe that may be notched up to about 105,000. T. H. WELDON*—I would like to ask

Jan 1, 1950

By S. W. Ross

A. A. CENTER*—This paper reminds me of the beginning of the work of the Electrolytic Zinc Company of Australasia. Early work for this Company, as some of you may know, was done at the Bully Hill Plant in California. After working there for some time Herbert Gepp, now Sir Herbert, came to the Anaconda Co. plants in Montana where I met him. He spent some months there, in fact almost a year if I remember rightly. That was when we were breaking in the new electrolytic zinc plant at Great Falls, Montana. From there he went back to Australia and started in on the plant there. I believe they had an original plant of about 20 tons per day of cathode zinc. We heard from them for some time, until they were able to go along on their own, and they have done very well ever since as you have heard. Their practice, (the flow sheet, the leaching practice), has been quite different as reported in the paper and apparently they are still following that practice to some extent. While the earliest work on selective flotation was done down in Australia, the big companies there, strange to say, were far behind the American companies in taking it up; and it is only in comparatively recent years they have gone to the alkaline circuit and dropped out thereby more of their iron and lead. The zinc plant now is up to a capacity of 100,000 tons a year and I believe that may be notched up to about 105,000. T. H. WELDON*—I would like to ask

Jan 1, 1950

By Hsun Hu

Based on Kurdjumoiv-Sachs orientation relationship for the fee bee transformation in metals, the jirzal crystal orientation resulting from successive transformations of bee-fee-bee has been analyzed mathematically. There are 528 different variants; many of ther are crystallograpyically equirvalent. Specific examples show that, for equal probability of all the variants, the principal crystallographic axes [100 ], [110], and [111] of the initial bcc crystal can be transformed into vairous axes in the fina1 crystal However, fur each of these principal crystallographic axes, a continuous range of orientation within certain regions of the unit triangle is completely avoided by the finctl Crystals. For uses of higher indices, the final orientations are more uniformly distributed throughout the unit triangle. Results from the PI-esent analysis are in good agreement with preferred Oientations Observed in a zone-meltecl iron bar. THE allotropic forms of iron are characterized by the unusual fact that at both high and low temperatures a bcc structure is stable, whereas at intermediate temperatures (1400" to 910°C) the metal is fcc. Hence, during cooling from its melting temperature, iron undergoes successive phase transformations ofd—? —a with corresponding changes in the crystal structure of bcc — fcc -bcc. while numerous studies have been made in the past of the 1 — a transformation in iron and in various iron-base alloys, no information is available in the literature as to the mechanism of 6 — l transformation and the lattice orientation relationship between these two phases. Experimental difficulties have apparently prevented researchers from undertaking these studies. The laltice orientation relationship between the parent and the new phases of iron resulting from

Jan 1, 1965

By Heber Cole

THE gypsum industry of Canada, like all others connected with the construction business, has felt the full effect of the depression during the past few years, and sales of its products have been greatly curtailed. The year 1934, however, saw a decided turn for the better and a gradual but steady improvement is noticeable in all its branches. In many ways the depression has been a blessing in disguise to the gypsum industry; during the years from 1926 to 1930, demand increased so rapidly that companies were forced to expand and often new apparatus and machinery were placed in operation regardless of expense, or plants already existing were taxed to their limit and forced to keep running with the minimum amount of repairs. The depression, therefore, has really given the industry what might be called a breathing spell, in which it has had time to take stock of its position, to reduce its costs of production, to devote more serious attention to the quality of its products, and to con-solidate its operations into a smooth working whole, which as conditions improve will enable it to meet the demands of the trade with more varied products of a quality hitherto unattained. Progress in the gypsum industry, however, has not been confined to the years of the depression, for some of the greatest advances occurred under the spur of increased demand for its products by the building trade. The purpose of this paper is to review briefly some of the out-standing trends in the development of the gypsum industry in Canada during the past 10 or 12 years.

Jan 1, 1935

By AIME AIME

FRIEND recently remarked that the career of Scott Turner is characterized by Work and Wild -A Ducks. To these might be added Accomplishment and Persistent Fishing. All of these elements are manifestations of his character. The diversions-hunting and fishing-are in the nature of the proverbial trolley conductor's holiday, for many of Turner's years have been spent in the outdoors, often in distant lands, as in Spitzbergen, where the ducks pictured below were bagged. The election of Scott Turner to the presidency of the Institute marks the culmination of a quarter century of membership, during the last two years of which he has been vice-president. He was born at Lansing, Mich., on July 31, 1880, and received his A.B. at the University of Michigan in 1902, with a B.S. and E.M. at the Michigan College of Mines in 1904. Since then he has been granted two honorary degrees, D.Sc. from the Colorado School of Mines, and D.Eng. from the University of Michigan, but he still prefers to be called "Scott" rather than "Doctor." Government service was not a new experience for Turner when he was appointed Director of the U. S. Bureau of Mines by Secretary Hoover in 1925, for his first employment after graduation was as Field Assistant in the U. S. Geological Survey in Oregon and Idaho. This was followed by work in Tombstone, Ariz.; then his first foreign engagement in 1905-6 as superintendent of the San Pablo Gold Mining Co. in Panama. Various field experiences followed, though there was an interlude in work of a kind that few mining engineers ever experience. This was in technical journalism, for in 1906 he was

Jan 1, 1932

By B. G. Klugh

The present paper represents a preliminary investigation of the ultimate structure of iron-bearing materials which have been subjected to heat treatment for the purpose of agglomerating the fines, or for chemical changes, or for both. Primarily, the object of this inquiry was to determine the relation of the microstructure of each of these materials to its specific susceptibility to the action in the blast-furnace. It is hoped that this small contribution will serve as a nucleus to a line of research that will throw some light upon the debated questions involved in blast-roasting. Thus far the investigation has been conducted along lines of analogy of known principles, rather than through the application of any well-defined system of microscopic petrography. This is obviously due to the fact that we are dealing with ma-terials which are the artificial products of a new art, rather than with the natural materials from which the essence of the pure science has been evolved. In the limited time allowed for this research, it has been conducted upon those materials the chemical content of which allows of their use commercially in the blast-furnace. The following microphotographs are arranged in the order of the degree of complete fusion to which the mass in question has been subjected, in effectively binding the particles together. A very notable fact here clearly demonstrated is that the degree of fusion to which the material has been subjected is inversely proportional to the reducibility of the product. The characteristic of the material under consideration to which reducibility is almost universally attributed call be progressively traced in the following arrangement, through the identity of the obvious microscopic constituent. Furthermore, the degree of fusion to which a bod? has been subjected is recorded in the presence of resultant products of fusion in that body. Such readjustment is generally apparent

Jan 1, 1914

By Thomas Fraser, H. F. Yancey

BefoRe a new coal-washing plant is installed, or an existing washery is remodelled and improved, considerable experimental work on the coal to be washed should be done. A thorough examination of a coal, to determine whether it can be washed successfully and the best and most economical process for securing a satisfactory grade of washed coal, calls for mine sampling, analytical work, and experimental coal-washing tests which may require several months' time and the expenditure of considerable money. Having collected the required data on the characteristics of the coal and the results secured with different types of machines under different sets of conditions, it is necessary to decide what method of treatment should be used. The interpretation of the experimental data is no small part of the problem. The first step in the investigative work is to determine from the characteristics of the coal and the manner of occurrence of the impurities whether it is possible to separate the dirt from the coal and produce a washed coal of the required quality. Then it is necessary to select the type of washer or the system of treatment that will produce the greatest amount of washed coal of this grade for the least cost. To secure this information, tests may be made at laboratories operated by consulting or contracting engineers, at the testing plants of machinery manufacturers, at commercial washeries, or in an experimental washery erected on the site of the proposed plant. Such tests will produce figures in which every factor, including analyses of raw coal and washed coal and yield of washed coal, may vary widely. To reduce these results to a common basis for comparison is very difficult. A number of plans

Jan 1, 1923

By Thomas Fraser, H. F. Yancey

BefoRe a new coal-washing plant is installed, or an existing washery is remodelled and improved, considerable experimental work on the coal to be washed should be done. A thorough examination of a coal, to determine whether it can be washed successfully and the best and most economical process for securing a satisfactory grade of washed coal, calls for mine sampling, analytical work, and experimental coal-washing tests which may require several months' time and the expenditure of considerable money. Having collected the required data on the characteristics of the coal and the results secured with different types of machines under different sets of conditions, it is necessary to decide what method of treatment should be used. The interpretation of the experimental data is no small part of the problem. The first step in the investigative work is to determine from the characteristics of the coal and the manner of occurrence of the impurities whether it is possible to separate the dirt from the coal and produce a washed coal of the required quality. Then it is necessary to select the type of washer or the system of treatment that will produce the greatest amount of washed coal of this grade for the least cost. To secure this information, tests may be made at laboratories operated by consulting or contracting engineers, at the testing plants of machinery manufacturers, at commercial washeries, or in an experimental washery erected on the site of the proposed plant. Such tests will produce figures in which every factor, including analyses of raw coal and washed coal and yield of washed coal, may vary widely. To reduce these results to a common basis for comparison is very difficult. A number of plans

Jan 1, 1923

By Edmund Newton

The steel industry of the United States has depended in the past almost wholly upon imports for its supplies of manganese. Many of the important domestic sources yield ores leaner in their natural condition than the foreign ores the steel industry. has been accustomed to use. To make them available, therefore, either the ores must be concentrated or the practice of the steel industry modified. Roughly 25,000 T. annually of high-grade manganese ores are used for dry batteries for chemical purpose, and in other ways; while approximately 750,000 T. are required for making steel. , By present practice, every ton of steel takes an average of about 14 lb. (1.8 kg.) of metallic manganese. This is generally added to the steel in the form of an alloy, the standard alloys being the 80-per cent. ferro-manganese and the 20-per cent. spiegeleisen, During the year 1917, 286,000 T. of ferromanganese and 193,291 T. of spiegeleisen were made in this country, the former largely from imported ores; and 45,381 T. of ferromanganese. was imported. The metallic manganese represented by these alloys was 304,000 T., the product of roughly 800,000 T. of high-grade ore and 345,000 T. of low-grade ore. Manganese Deposits in the United States Before the war manganese ore was mined in relatively small quantities in the Appalachian region, including Virginia, Tennessee and Georgia, and in Arkansas, but owing to the increase in prices during the past three years manganese mining has been undertaken also in Montana, California, Arizona, New Mexico, Nevada, Utah, and Minnesota. From data now available it appears that in this country deposits of high-grade manganese ores are usually small, while materials lower in manganese and higher in iron occur in appreciable quantities. Our total quantity of manganese-bearing material is relatively large, but on

Jan 1, 1920

By Henry M. Howe

The brilliant and very original matter in Professor Jeffries' discussion† should rank not only as an independent paper, but as a most important one. In particular, the explanation which it gives of the remarkable Sauveur phenomenon, over which so many of us have puzzled long and hard, is so clear, complete, and cogent as to go far toward establishing Professor Jeffries' hypothesis. The very leatures of Professor Sauveur's photographs which fit this hypothesis so exactly are reproduced in Chap-pell's photographs of steel coarsened under somewhat different conditions.' The ideas developed by these discoveries are so novel that convenicnce of language seems to call for new conventional terms for expressing them. In what follows here I propose certain terms for this end, for criticism and improvement, and I attempt to generalize from Professor Jeffries' hypotheses. Generally speaking, a given set of grains which undergo no growth in the cold will, when the temperature is raised progrcssively, start to grow on reaching a certain temperature, and will continue growing at all higher temperatures. The "germinative" temperature is that at which growth begins, quite as the conditions which cause a seed to grow are "germinative." We have then an inert temperature range below the germinative temperature, and a growth range above it, the germinative temperature being the limit between these two ranges. So, too, a germinant grain is one which is at its germinative temperature, and hence beginning to grow, while inert grains are those below their own germinative temperature, and the term "growing grains" includes those which are germinant and those which are above their germinative temperature. These last could be called " supergerminant" if the distinction should be needed. "Germinative temperature" seems better than "critical temperature

Jan 1, 1917

Although Australia is the world's second biggest producer of iron ore, the last few years have not been easy for companies in Western Australia's Pilbara region (see map) where more than 90% of the nation's iron ore is produced. For at least two years, the industry has been plagued by dwindling markets abroad, production-crippling strikes at home, skyrocketing costs (well above the official 13% annual inflation rate), an acute shortage of investment capital, increasingly ferocious competition from foreign iron ore producers-and, as if all this weren't enough, by an over-valued currency that has caused incalculable damage not only to iron ore producers but to the entire mining industry of Australia. (This last problem was mitigated less than two months ago, on November 28, 1976, when the Australian dollar was devalued by a whopping 17 1/2%.)

Jan 1, 1977