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By T. G. R. Rawlins, L. E. Brosselard

Direct platinum carbon replicas have been used to study substrates prior to growth and after initial nu-cleation of the layer. Replicas have been directly stripped and correlations have been made with other replica techniques. Mechanically polished substrates are very flat with occasional areas of "dirt", which is apparently silicon. When such substrates are etched in hydrochloric acid gas, scratches and hexagonal defects (thought to be polishing compound) are revealed, together with areas of apparent redeposition. Chemically polished substrates are much less flat although much more homogeneous in appearance. Heat treat)nents have no effect. Nuclei deposited on these surfaces, using a normal silicon tetrachloride system, have been examined. Nuclei on mechanically polished subsrates occur in random areas only, whereas on chemically polished surfaces they are more uniformly distributed. THE interest in the study of thin films and now their rapidly expanding use in many fields has increased over a period of years. Much of this current interest, particularly in the field of single-crystal or epitaxial thin films, has derived its stimulus not only from possibilities for application but also from fundamental electron-microscope studies which have indicated the manner of growth of such layers from the initial nuclei.1-5 Previous work involving study of growth processes may be divided into three categories. First, vacuum deposition, primarily of metals, on a variety of substrates has been studied by electron microscopy and electron-diffraction techniques. These have shown the three-dimensional aspect of nucleation and the remarkable liquidlike behavior of the growing nuclei which coalesce to form a complete layer. More recently this work has been expanded in two ways: by growth inside the electron microscope this has obvious advantages for kinetic studies; and by growth in ultrahigh vacuum—much of this work has been done on semiconductors.8-11 It is of interest to note that metals, specifically gold deposited on rock salt, will form only polycrystalline layers in ultrahigh vacuum unless the substrate surface is contaminated.12 In general the mode of growth for vacuum-deposited semiconductor films is the same as that for metal films. The second method of growth that has been studied is that of electrodeposition.13,14 The little that has been published suggests that the mode of growth is similar to the vacuum case, except that irregularities may perturb the electric field and disturb the growth process. The third and last primary method of growing epitaxial layers is by use of chemical methods. These techniques have generated much interest and much has been published on them. Considerable electron-microscope work has been done on the defects in the layers; however comparatively little work has been undertaken on the initial nucleation and early stages of growth. Confining ourselves now exclusively to the case of silicon, Charig et a1.15 have considered the growth of silicon on silicon substrates by hydrogen reduction of trichlorosilane, and studied the films by means of replica and transmission techniques. Subsequently they have studied the same system for growth on quartz,16 and with the addition of pyrolysis of silane on quartz and alumina.17 Also Manasevit el al. have studied deposits using silane and silicon tetrachloride on sapphire.18-14 Finally, in this volume studies of deposition on beryllia and sapphire are reported. Although Revesz and Evans20 have examined complete layers, grown by means of the widely used silicon tetrachloride reaction, no detailed examination similar to that published by Charig and Joyce21 for the trichlorosilane system has been given. Therefore this investigation has examined substrate surfaces prior to growth and then nucleation on these surfaces for the silicon tetrachloride system. EXPERIMENTAL In this work the surfaces have been studied by means of standard replica techniques. Because of the very real problems associated with artifacts introduced,22 different replicas and different cleaning

Jan 1, 1967

By R. E. Zimmerman

The separation of fine sizes of coal from its impurities by means of various flotation methods has become of increasing importance in the coal industry. This, no doubt, will be even more so in the future as the quantity of high grade coal is depleted, particularly that used for metallurgical purposes. The purpose of this paper is to describe and report the results of research work done under the auspices of the Pittsburgh Coal Co. to determine the amenability of their bituminous fine sizes of coal to flotation, to investigate the value of various reagents and factors affecting their use, and compare the results between froth flotation and bulk oil flotation. Compared with the preferential flotation of complex minerals, or ores, the flotation of coal is comparatively easy. However, this statement should not lull one into the feeling that there are no special problems involved. For instance, the separation of coal from pyrite in high sulphur coals is still far from being 100 pet successful. Size consist has considerable effect on reagent consumption and recovery. Other factors will be described and finally it must be remembered that in the flotation of coal a low priced material is being treated and thus economic considerations govern more closely its application than is generally the case in treating other minerals. As a result of the research work done by the Pittsburgh Coal Co. on the flotation of coal, it was concluded that it was practical to clean the —48-mesh coal commercially by froth flotation and after several different types of flotation units and circuits were investigated by means of pilot plants, large scale units were installed at their Champion Nos. 1, 4 and 5 Preparation Plants for the cleaning of —48-mesh slurries. These large scale operations have been recently described by D. H. Davis.' C. P. Proctor and C. B. Carlson2 in their chapter on Froth Flotation of Coal in the AIME Seeley W. Mudd series book on Coal Preparation describe some of the practical applications of our Pittsburgh Coal Co. laboratory work in actual plant practice as well as summarizing part of the investiga-tional work. The author presents this paper, however, as a supplement to their reports, and records the basic research accomplished in the laboratory investiga-tional work as well as the results of experiments using bulk oil flotation. In presenting this work the author wishes to state much more work must be done in applying the principles of flotation to cleaning coal, especially in view of recent studies and practices in other mineral beneficiation fields. Methods of Conducting Laboratory Tests The bulk of the research work was conducted in the laboratory of the Champion No. I Preparation Plant. This plant has elaborate facilities for sampling and analyzing coal and proved to be an admirable location for the investigational work. Four types of laboratory flotation ma-

Jan 1, 1949

By N. P. Peterson

The Castle Dome copper deposit is of the porphyry type and occurs in a body of quartz monzonite intruded into the pre-Cambrian formations and possibly into the lower part of Paleozoic limestones. The hypogene sulphide minerals include pyrite, chalcopyrite, and a little molybdenite, sphalerite, and galena. Pyrite and chalcopyrite are disseminated or occur in small closely spaced veins. The hypogene mineralization shows distinct zoning in the distribution of pyrite and chalcopyrite, so that the mineralized area can be subdivided into pyritc and chalcopyrite zones. Supergene enrichment, though not extensive, played an important part in the formation of the ore body, the chalcopyritc zone being the pro-tore. Several thin, gently dipping, diabase sills occur in the mineralized area, and the copper content of the rock in and near these sills is substantially higher than average. The formation of the ore body was caused by the combined effects of three forces: I. Zoning of the hypogene mineralization, 2. Richer copper metallization associated with the diabase sills, and 3. Supergene enrichment. Introduction The Castle Dome copper deposit is about 5 miles west of Miami, Arizona, and about 3 miles west of the Miami-Inspiration ore body. The Castle Dome open-pit mine is on the south flank of Porphyry Mountain, a prominent landmark of the region. In 1941 the deposit was being explored by the Miami Copper Co., but the exploration program was cut short when the decision was made to develop the property as a war project. The Castle Dome Copper Co., Inc., was organized as a wholly owned subsidiary of the Miami Copper Co., and arrangements were made with Defense Plant Corp. for developing and equipping the mine and for construction of a concentrating plant. Construction and development work was begun in January 1942, and milling operations started June so, 1943. Since that date, the mine has been in continuous operation by the Castle Dome Copper Co, under a lease agreement with Defense Plant Corp. producing copper at an average rate of 4,000,000 lb per month. To January I, 1946 the total production amounted to 121,088,000 lb of copper,4,271 oz of gold, and 211,755 oz of silver. A detailed study of the copper deposit and the surrounding area was undertaken by the U. S. Geological Survey in June 1943. Other members of the Survey participating in the work were C. M. Gilbert, G. L. Quick, and J. P. Albers. The results of this work will be published as a comprehensive report by the Geological Survey. General Geology The Globe quadrangle, which includes the Castle Dome area, was studied by F. L. Ransome1 of the Geological Survey in 1901 and 1902. His maps and descriptions were

Jan 1, 1949

By N. P. Peterson

The Castle Dome copper deposit is of the porphyry type and occurs in a body of quartz monzonite intruded into the pre-Cambrian formations and possibly into the lower part of Paleozoic limestones. The hypogene sulphide minerals include pyrite, chalcopyrite, and a little molybdenite, sphalerite, and galena. Pyrite and chalcopyrite are disseminated or occur in small closely spaced veins. The hypogene mineralization shows distinct zoning in the distribution of pyrite and chalcopyrite, so that the mineralized area can be subdivided into pyritc and chalcopyrite zones. Supergene enrichment, though not extensive, played an important part in the formation of the ore body, the chalcopyritc zone being the pro-tore. Several thin, gently dipping, diabase sills occur in the mineralized area, and the copper content of the rock in and near these sills is substantially higher than average. The formation of the ore body was caused by the combined effects of three forces: I. Zoning of the hypogene mineralization, 2. Richer copper metallization associated with the diabase sills, and 3. Supergene enrichment. Introduction The Castle Dome copper deposit is about 5 miles west of Miami, Arizona, and about 3 miles west of the Miami-Inspiration ore body. The Castle Dome open-pit mine is on the south flank of Porphyry Mountain, a prominent landmark of the region. In 1941 the deposit was being explored by the Miami Copper Co., but the exploration program was cut short when the decision was made to develop the property as a war project. The Castle Dome Copper Co., Inc., was organized as a wholly owned subsidiary of the Miami Copper Co., and arrangements were made with Defense Plant Corp. for developing and equipping the mine and for construction of a concentrating plant. Construction and development work was begun in January 1942, and milling operations started June so, 1943. Since that date, the mine has been in continuous operation by the Castle Dome Copper Co, under a lease agreement with Defense Plant Corp. producing copper at an average rate of 4,000,000 lb per month. To January I, 1946 the total production amounted to 121,088,000 lb of copper,4,271 oz of gold, and 211,755 oz of silver. A detailed study of the copper deposit and the surrounding area was undertaken by the U. S. Geological Survey in June 1943. Other members of the Survey participating in the work were C. M. Gilbert, G. L. Quick, and J. P. Albers. The results of this work will be published as a comprehensive report by the Geological Survey. General Geology The Globe quadrangle, which includes the Castle Dome area, was studied by F. L. Ransome1 of the Geological Survey in 1901 and 1902. His maps and descriptions were

Jan 1, 1949

By Dorsey Lyon

I. INTRODUCTION THE utilization of hydro-electric power in electro-metallurgical indus¬tries, aside from purely mechanical operations, may he of two kinds. The electric energy may be used to supply the heat necessary for the per¬formance of the chemical reactions of a metallurgical process, or the elec¬trolytic action of a direct current may be employed for extraction of metals, either in a reduction process or a refining process. In discussing this subject, it is well to distinguish between established industries, which are producing metals and alloys at a profit by use of the electric current, and the many processes which are either still in the experimental stage or have not even passed the paper stage of development of a patent. That is, we consider electro-metallurgical industries as commercial operations which are now consuming large blocks of electric energy, while processes which are not in commercial operation are only prospective consumers. Also, owing to the difficulty and risk of any attempt to foresee the effect of the European war upon electro-metallurgical industries, we have felt obliged to disregard the war entirely, and state our opinions regardless of its existence.

Jan 8, 1915

By O. D. Sherby, J. E. Dorn, C. D. Wiseman

MCLEAN' has shown that the total strain obtained during creep of aluminum polycrystals arises exclusively from the mechanisms of 1) microscopically observable slip, 2) subgrain tilting, and 3) grain boundary shearing. Extensive analyses, however, suggest that the high temperature creep of metal polycrystals is controlled by a single thermal activation process."" These somewhat contradictory observations might be reconciled if it could be shown that the activation energies are identical for each of the mechanisms isolated by McLean. Such identity of the activation energies, of course, would demand that the same unit process controls the functioning of each individual mechanism. Under these conditions the activation energies for creep of single metal crystals and polycrystalline aggregates and for grain boundary shearing should be identical. This paper is primarily concerned with the possible identity between the activation energies for high temperature creep of single crystal and polycrystalline metals. In addition, comparisons will also be made between the activation energies for creep of single crystals and polycrystals with previously reported activation energies for grain boundary shearing.0"8 Materials and Techniques The same high purity aluminum, lead, and tin were used in the creep tests for single crystals and polycrystalline aggregates. Single crystals of aluminum and tin were prepared by the strain-anneal technique, whereas lead single crystals were prepared by growth from the melt. The tensile creep stress was maintained constant by Chalmers-Andrade parabolic-type lever arms. Strains were measured to &0.0002 in. per in. with rack and pinion type extensometers, and temperatures were maintained to within & 0.2"C of the reported values by mercury-thermoregulated resistance-heated silicone oil baths. The previously reported unambiguous technique for determination of the activation energy for creep was employed throughout this investigation.' ." It involves periodic abrupt small changes in temperature during the course of creep, accomplished by rapidly replacing one creep bath at temperature TI by a second bath at T,. The abrupt change in creep rate from i, to & attending the abrupt change in temperature is due exclusively to the change in temperature, since both the stress and the substructure are identical the instant before and the instant after a change of temperature. Therefore, all other factors being identical where AH is the activation energy for creep and R is the gas constant. Results Typical examples of the creep rate vs creep strain data during temperature cycled creep tests of single

Jan 1, 1958

By O. W. Simmons, L. W. Eastwood, C. M. Craighead

H. Schwartzbart and W. F. Brown, Jr.—The authors have divided the effects of recovery on the true stress-true strain curve into two types; metarecovery, which effects only the first part of the curve or the yield strength, and orthorecovery, which effects the flow stress at any strain. Both of these are said to be true recovery effects, involve no recrystallization, and are explained by the removal of two different types of imperfections caused by work hardening. However, there seems to be some question as to whether the data are sufficiently conclusive to exclude, as an explanation of the authors' results, a mechanism based on the relief of residual stresses between the grains or slip bands and recrystallization. It appears that metarecovery could be interpreted in the same fashion as a customary interpretation of the Bausch-inger effect. The balanced system of internal stresses which exists between grains in a strained specimen due to varying orientation and, hence, yield strengths, of the different grains is responsible for a reduced yield strength in compression following pre-tension, and, similarly, for an elevated yield strength in tension following pre-tension. If the specimen is now heated so that the internal stresses are relieved by creep, then the yield strength in tension following tension will have been reduced and in compression following tension will have been raised. There seems to be a very strong case for the lack of recrystallization in the aluminum investigated by the authors, if one defines recrystallization as the presence of visually detectable new grains or accepts the X-ray evidence as conclusive. One must remember, however, that the appearance of spots on the back-reflection X-ray patterns cannot be taken as the time when recrystallization first started. The areas of recrystallized strain-free material must first have grown to a size large enough to give distinct spots on the patterns and this may take some time. Averbachl7 in an investigation of brass has shown that recrystallization can be detected by extinction measurements at temperatures lower than those based on hardness or X-ray line width determinations. It can be seen from fig. 10 that the rate of recrystallization is extremely low over a considerable time period at the onset of the process. Observations on the rate at which small amounts of recrystallization effect the flow stress would have given further insight as to whether undetectably small amounts of recrystallization might have been responsible for orthorecovery. Also, the question arises as to whether the effects observed in fig. 6 for various times and temperatures could not have been obtained if the time at 212°F were sufficiently long. In addition, the argument that the curve in fig. 10 is not sigmoidal seems weak in view of the scattering of the points. It is conceivable that an accurate determination of the curve for the first 100 hr would exhibit a relationship other than the one drawn. There is one point we would like to raise about the condition of the starting material. The authors annealed their material at 750°F for 15 min to remove the effects of any previous work hardening or machining strains. Reference to the work by Anderson and Mehl shows that this treatment may not have completely recrystallized the aluminum, so that the starting material may have had some strained areas. Higher temperatures or longer times may have been required to remove the effects of any small strains. We would like to mention some results of tests being conducted at the Lewis laboratory of the National Advisory Committee for Aeronautics in an investigation of the Bauschinger effect in relation to fatigue. Tests were performed on annealed electrolytic copper and several annealed brasses. Specimens were pre-strained 1 pct in tension and then tested in compression or tension with and without intermediate stress-relieving annealing treatments at 500°F for various times. Specimens heated at 500°F for 10 1/2 hr showed an elevation of the flow curve in compression and an approximately equal lowering of the flow curve in tension when compared with the curves for the un-heat treated specimens. After approximately 0.8 pct strain, all flow stresses coincided and were equal to the flow stress of the virgin material at this strain. This behavior is consistent with the metarecovery observed for aluminum by the authors and for which a residual stress model can be used. On the other hand, increas-

Jan 1, 1951

Application of Kutter's Formula to Gases Discussion of paper by F. ERNEST BRACKETT, presented at the Pittsburgh Meeting and issued, as Pamphlet No. 1578-A-F, with MINING AND METALLURGY, June. 1926. C. S. WITHERELL, New York, N. Y. (written discussion).-There is no reason to doubt that the relationship between the rate of flow and the impelling force of all fluids can be expressed by a general typical equation . that takes cognizance of all relevant factors such as density, viscosity (or its reciprocal mobility) and nature of channel-walls. Most fluids that are commonly conveyed by flow in confined channels are so highly mobile that they may be considered non-viscous, hence for these fluids the factor of viscosity does not need to appear in the equation. Water is the outstanding example of this class of fluids and its dynamic behavior has been so thoroughly investigated that proven formulas pertaining thereto, be they rational or empirical, would naturally serve as prototypes for the other non-viscous fluids. As non-viscous fluids can be classed all gases and vapors, most unsaturated aqueous solutions, gasoline, alcohol, etc. Viscous fluids comprise those that have a sluggish flow such as most. oils, tar, molasses, etc., the high viscosity of which is due to shearing resistance between molecules; a force that must be taken into account in figuring the flow of fluids of this class.

Jan 10, 1926

Application of Kutter's Formula to Gases Discussion of paper by F.-ERNEST BRACKETT, presented at the Pittsburgh Meeting and issued, as Pamphlet No. 1578-A-F, with MINING AND METALLURGY, June. 1926. C. S. WITHERELL, New York, N. Y..(written discussion).-There is no reason to doubt that the relationship between the rate of, flow and. the impelling force of all fluids can be expressed by a general typical equation that takes cognizance of all relevant factors such as density, viscosity (or its reciprocal, mobility) and nature of channel-walls. Most fluids that are commonly conveyed by flow in confined channels are so highly mobile that they may be considered non-viscous, hence for these fluids the factor of viscosity does not need to appear in the equation. Water is the outstanding example of this class of fluids and its dynamic behavior has been so thoroughly investigated that proven formulas pertaining thereto, be they rational or empirical, would naturally serve as prototypes for the other non-viscous fluids. As non-viscous fluids can be classed all gases and vapors, most unsaturated aqueous solutions, gasoline, alcohol, etc. Viscous fluids comprise those that have a sluggish flow such as most oils, tar, molasses, etc., the' high viscosity of which is due to shearing resistance between molecules, a force that must betaken into account in figuring the flow of fluids of this class.

Jan 10, 1926

By Emil Gathmann

INTRODUCTION. IN presenting this paper I will attempt to answer certain questions proposed at this meeting and describe and illustrate methods of producing sound steel in an economical and hence commercial manner, which are adaptable to the production of practically all steel manufacturers, by readily effected rational changes in the methods of casting, cooling, and subsequent handling of the ingots. In some of the high-grade mills of America, where it is essential to obtain perfectly sound billets or blooms, it is the practice to discard from 35 to 40 per cent. of the crop- or pipe-end, and even with this excessive discard, secondary pipe or shrinkage-cavities are frequently discovered during subsequent working of the blooms and billets into their various manufactured products. The usual discard of from 10 to 20 per cent. from the crop-end of the ingot, which is made by the present generally employed methods of form and solidifying of the castings, certainly does not give the slightest assurance of the saleable product being physically sound or chemically homogeneous. I am aware that in the past there has been and at the present time there still is a decided difference of expert opinion as to what constitutes physically sound steel.

Jan 4, 1913

By R. K. Datta, T. S. Davis

YVO4:EU, excited under 3650A radiation, shows a marked increase in total brightness with in~rease in temperature. At 25°C the response to 3650A radiation is about 48 pct of its maximum response which occurs at about 350°C, Fig. 1. In an attempt to explain the phenomenon, one of the present authors' (R.K.D.) investigated the diffuse reflectance spectra of the phosphor at different temperatures (up to -150°C) and was unable to observe any significant change to which the increased brightness could be reasonably ascribed. Since then diffuse reflectance spectra at elevated temperatures have been obtained in this laboratory using an improved device. A significant decrease in the diffuse reflectance of a phosphor in the ultraviolet region—especially in the longer wavelength region—at -300°C has been observed. The purpose of this note is to describe the device used for high-temperature reflectance measurements and to explain the increased brightness of YVO4:Eu phosphor at elevated temperatures under 3650A excitation. Experimental. YVO4 and YVO4:Eu samples were prepared as previously described.' The elevated-temperature reflectance spectra were obtained with a Cary 14 spectrophotometer equipped with a diffuse reflectance accessory and a ring collector. CaF2 was used as the standard. The cell used

Jan 1, 1969

By Clarence Merritt

STAINLESS iron, as mild stainless steel is usually called, an alloy ranging from 11.50 to 15.00 per cent chromium with carbon under 0.12 per cent, has been considered to be not appreciably affected in respect to corrosion resistance by heat treatment. This metal, while one of the most widely used of the "straight" chromium stainless alloys, has failed in many applications because of insufficient information regarding heat treatment. These failures have been attributed to many possible causes from an inherent lack of resistance to corrosion and misapplication to mysterious electrolytic effects or comparatively minute non-metallic inclusions. Many uses for a steel with such excellent physical properties is are latent in this alloy have been lost on account of corrosion failures which could have been avoided by applying proper heat treatment. The alloy has not received the recognition or attention it should because of the fact that' the details of its metallurgical behavior were not thoroughly understood. Response to heat treatment of the steel is well known as regards tensile properties, 1,2 but its application has been for improvement in tensile characteristics or on account of machining considerations rather than for corrosion prevention. The potential user of this steel has not been clearly advised in papers, either technical or commercial, that have been written about it in the last 10 years or more, of particular features that are of prime importance in developing the excellent properties of this metal. The data to be presented in this paper are concerned mainly with the effect of heat treatment on the corrosion resistance, but a study has also been made of the concurrent microstructural changes and an explanation developed for the phenomena revealed, as well as a correlation to the other physical properties-hardness, tensile characteristics and impact strength. Stainless steel, largely used for cutlery purposes, an alloy of approximately 13.00 per cent Cr with 0.30 per cent C, must be hardened and the surface prepared by polishing or pickling for best resistance to staining and corrosion.3 Monypenny reports that a loss of hardness is

Jan 1, 1932

By W. B. Vietz, C. W. Hill, T. P. Thomas

FLUXES, in general, may be classified according to their use as soldering, foundry or casting, and metallurgical and the chemistry of their action follows quite closely this division. The term foundry or casting fluxes, as used here, refers to the substances added to molten metals, preparatory to casting into molds or ingots, with the object of removing small amounts of impurities that have been introduced in handling or melting the metal, which was placed in a fair state of purity by the previous refining or metallurgical processes. The sources of these impurities are the oxide coating on the surface of the ingots, material extracted or mechanically removed from the crucible or furnace wall, and those formed by the reaction of the molten metal with the heating gases or furnace atmosphere. As commonly used, the term fluxes is applied to such materials as ammonium chloride, zinc chloride, salt, borax, and boric oxide. A second class of materials, usually called deoxidizers, includes substances such as metallic phosphides, sub-oxides, carbides, and bo-rides, that reduce the metallic oxides present in the metal. A third class includes various compounds that arc molten and non-volatile at the temperature of the molten metal and are used primarily to protect the surface of the metal from the action of the furnace or exterior atmosphere; to this class belong such mixtures as lime and fluorspar, lime and soda ash, various minerals, etc. In some cases these protective layers may act in a manner similar to the metallurgical fluxes and dissolve or unite with the oxide impurities of the metal, but as generally employed this latter action is negligible since there is little opportunity for the coverings to come into contact with more than the surface of the metal, and hence they arc without action on the body of the molten mass. The use of fluxes is the result of factory experience and tradition, but an extensive study has not been made of the chemical and physical actions that occur or the effects of these actions on the properties of the metal. It would seem necessary in any successful study of metal fluxes to determine not only what impurities are present in metals melted under

Jan 1, 1921

By Anson G. Betts

A solution of lead-fluosilicate, containing an excess of fluosilicic acid, has been found to work very satisfactorily as an electrolyte for refining lead. It conducts the current well, iseasily handled and stored, non-volatile and stable under electrolysis, may be made to contain a considerable amount of dissolved lead, and is easily prepared from inexpensive materials. It possesses, however, in common with other lead electrolytes, the defect of yielding a deposit of lead lacking in solidity, which grows in crystalline branches toward the anodes, causing short circuits. But if a reducing-action (practically accomplished by the addition of gelatine or glue) be given to the solution, a perfectly solid and dense deposit is obtained, having very nearly the same structure as electrolytically-deposited copper, and a specific gravity of about 11.36—that of cast-lead. Lead-fluosilicate may be crystallized in very soluble, brilliant crystals, resembling those of lead-nitrate and containing four molecules of water of crystallization, with the formula PbSiF,,4H20. This salt dissolves at 150 C. in 28 per cent. of its weight of water, making a sirupy solution of 2.38 sp. gr. Heated to 60° C., it melts in its water of crystallization. A neutral solution of lead-fluosilicate is partially decomposed on heating, with the formation of a basic insoluble salt and free fluosilicic acid, which keeps the rest of the salt in solution. This decomposition ends when the solution contains, perhaps, 2 per cent. of free acid; and the solution may then be evaporated without further decomposition. The solutioi~s desired for refining are not liable to this decomposition, since they contain much more than 2 per cent. of free acid. The electrical conductivity depends mainly on the acidity of the solution. My first experiments were carried out without the addition of gelatine to the fluosilicate solution. The lead-deposit con-

Jan 1, 1904

By Henry Otto

THE anthracite industry can be divided into two parts-the underground, or mining, and the outside, or preparation or manufacture. To understand recoveries in the two branches, some of the history of the industry and the changes that have taken place in the past century should be considered. It is a long step from 1807, when 55 tons were produced in the Wyoming field, to 1917, the peak year, when 80,841,223 tons were shipped to market from all the fields. In 1820, the Lehigh Coal Co., the predecessor of the Lehigh Coal & Navigation Co., shipped 365 tons in arks down the canal of the Lehigh Navigation Co. The Schuylkill field was not opened until 1822, when 1480 tons were shipped. The Wyoming field really became a producer in 1829, when 7000 tons were mined and shipped. It is well to note, at this time, the passing of the Coleraine colliery after a life of 88 years; in collieries of this age will be found the. romance of the region, as well as the history of the changes to date.

Jan 1, 1925

By Henry D. Hibbard

Henry D. HibbaRd, Pittsburgh, Pa,: This is a most interesting and instructive paper, some of whose lessons should find immediate application. It points out how fuel-consumption is to be decreased in open-hearth practice, by changes in the plan of the furnace. To look first at the greatest item of loss, radiation, it is seen that thicker brick-work is advisable to lessen this. Especially is this true of the roof, made at present, almost universally, only 9 inches thick to prevent cutting. Now that high roofs, well above the course of the flame, are becoming general, and the average melter is better able to judge the temperature of his furnace, that reason has less force; and we may build roofs 18 inches thick, or perhaps better cover the usual 9 inches with an equivalent layer of sand, which has the advantage of following the arch as it rises and falls with the different degrees of heat. The side-walls of the hearth, usually 131/2 inches thick, may also he thickened up to 18 inches, and the door-linings to 7 inches; and the heat thereby saved will be valuable, while its absence from the working-platform will be much appreciated by the workmen.

Jan 1, 1892

By Percy W. Bidwell

THE statisticians had defeated Germany months before she invaded Poland. With batteries of adding machines they had proved that she was suffering from serious deficiencies in critical food- stuffs and in practically all of the raw materials necessary for the conduct of modern warfare. Their calculations showed that with respect to fats, oils, wool, cotton, hides, petroleum, iron, copper and other metals, the Reich was bound to be at a great disadvantage vis-a-vis the French and British as long as the latter could keep open the lines of sea communication. The conclusion seemed obvious-"Germany can't win." The more cautious of the commentators introduced qualifications as to the length of the war and the tightness of the British and French blockade. They also made a third qualification as to the character of the struggle- whether it was to be a war of attrition or a war of movement. But since the invasion of Norway in April, there is no longer any doubt on this score. It is a war of movement-a war in which fuel, lubricants, and metals are being consumed on a scale never before seen.

Jan 1, 1940

By W. Vickers

Single-point rotating cantilever fatigue tests have been carried out at 550" to 650°C on beryllium produced by a variety of fabrication routes. All the specimens gave similar plots of stress against number of cycles to failure but failure occurred at a lower stress range in the hot-pressed material than in the extruded material. A discontinuity or "kink" appears to exist in the curves and this is considered. A true endurance limit was not evident up to 10 cycles. When Brush hot-pressed warm-extruded beryllium was tested at 600oC a relationship where Nf = number of cycles to failure, ?ep = plastic strain range, and c = constant, was shown to be applicable for values of ?ep > 6.3 x 10-4. Further for this moterial and temperature and for frequencies between 150 and 4500 cycles per min, the variation of number of cycles to failure with frequency obeyed the expression N = Af0.44 where N =number of cycles to failure, f = frequency, and A = constant. Examination of the fracture surfaces indicated that they were generally intergranular and in all cases the higher the stress the more irregular was the fracture. Microexamination has shown that grain boundary cavities and fine intergranular cracks were associated with the fractures. REVERSING or cyclic stresses set up in fuel elements can lead to failure by fatigue. Fatigue stresses may be developed by instability of the fuel element in the coolant flow leading to rattling against the channel wall or fin vibration. Thermal cycling also sets up reversing stresses due to differential expansion of fuel and can. Fatigue resistance is of some importance therefore in the evaluation of canning materials. At the time the work described in this paper was initiated, beryllium was being considered for the can and endcaps of an advanced gas-cooled reactor fuel element. With this in mind, beryllium obtained from different manufacturing routes was tested on single-point rotating cantilever fatigue machines at temperatures the same as those envisaged in the reactor to obtain appropriate fatigue data. The results obtained indicated a discontinuity in the S-N curves coinciding with the yield stress in the specimens. Although in some cases the data is insufficient to warrant a detailed quantitative analysis, a qualitative analysis of this effect was thought to be justified. 1) EXPERIMENTAL DETAILS The materials used are given in Table I together with the production route and available analyses. The specimen shape is shown in Fig. 1. The fatigue specimens were machined slightly oversize, after which they were given a stress-relieving anneal of 1 hr at '750° C in vacuum. This was followed by an etch in sulfuric-phosphoric-chromic acid mixture down to the finished dimensions given in Fig. 1. Etching served to remove the interference colored oxide film formed on the surface during annealing and very small recrystallized surface grains too. The specimen was mounted in the grips of a cantilever machine and rotated inside a furnace controlled at the testing temperature. The specimen was loaded in increments as the speed was increased until the required load was applied at 5000 cycles per min. A revolution counter was used to record the total number of cycles.

Jan 1, 1964

By John B. Mertie

More than 200 minerals are known that contain the rare-earths and thorium. Monazite and bastnaesite, however, are the principal commercial sources of the rare-earths, and monazite is the principal source of thorium. Monazite was in demand in earlier years mainly for its content of thorium, which was used in the manufacture of Welsbach gas mantles; but beginning in the latter part of the nineteenth century, the rare-earths became progressively more important than thorium. Recently, however, the tenor of thorium in monazite has again become a matter of commercial interest. Rare-Earths and Thorium The rare-earths proper are defined by spectroscopists as the oxides of 14 elements with atomic numbers ranging from 58 to 71; but more commonly lanthanum, with an atomic number of 57, is also included, in which case these 15 elements are often designated as the lanthanides. Chemists also include scandium and yttrium as elements of the rare-earths. A second group of elements, beginning with actinium and including thorium, protactinium, uranium, and all the transuranium elements so far produced, with atomic numbers ranging from 89 upward, are chemically and structurally related to the lanthanides, and are known as the higher rare-earths or actinides. Berzelius discovered that the lanthanides could be separated roughly into three groups, based upon the solubility of their double salts, R2(SO4)3-K2SO4-2H2O, in excess of K2SO4. This separation, with the substitution of sodium for potassium, is still used commercially. The double salts of the cerium earths were found to be almost insoluble; the terbium earths, partly soluble; and the yttrium earths, completely soluble. Based upon the degree of solubility, scandium belongs with the cerium earths; and yttrium belongs with, and gives its name to, the yttrium earths. These three groups with their atomic numbers are shown below. [ ] The prevailing state of oxidation for the rare-earths is R2O3, but cerium may readily be oxidized to the tetravalent state, in which condition it may be separated chemically from the other cerium earths. Praseodymium and terbium may also exist with the valence IV, and samarium, europium, and ytterbium may have the valence II. Most of the elements of the rare-earths, however, are very difficult to separate, and their initial isolation required the work of many chemists over a period of 150 years.20 Fractional crystallization, fractional precipitation, and ion exchange are the principal methods so far used, and fractional precipitation is now employed commercially on a large scale. Ion exchange columns are

Jan 1, 1960

Gentlemen.-It is pleasant to be able to report that the year just closed has been a prosperous and successful one for the Institute. As is shown by the reports of the Treasurer and the Finance Committee, the business affairs of this organization are in excellent condition. With property valued at more than three-quarters of a million dollars, and with considerable sums in various funds and endowments, it is possible to spend on each member of whatever class $22.65 each year, more than the maxi- mum amount of dues received from any one, and substantially twice the average amount, $10.94, received from all. To do this has required close management and a strict regard for our limitations. In 1926, when the Budget was made up, the estimated expenditures for the work which it was felt the Institute must do exceeded the estimated receipts by some $14,000. At the close of the year, despite a number of unexpected decreases in receipts, it had proved possible to accomplish substantially all the work laid out and close the books with the usual transfer of initiation fees to the General Reserve, and still only reduce the cash balance $2,074.54. This was made possible by the hearty and loyal cooperation of the whole staff of employees and the extremely large amount of gratuitous service rendered by the officers, the members of the Divisions and technical Committees, and the membership generally. Even so it was impossible, because of limitations of funds, to undertake many things it is highly desirable for the Institute to do, and it was necessary to refuse the publication of important papers and committee studies, because of the lack of funds. PUBLICATIONS In an analysis of the income and expenses of the Institute published in the February issue of our Journal, MINING AND METALLURGY, it was pointed out that the largest item of expenditure is, as it should -be, for publications. Printing, binding, and distributing the various technical papers sent to the members cost in 1926 more than all the money received from dues, including the portion allocated as subscription to the magazine. Within the. year, the following volumes were printed and, with the exception of the second volume of TRANSACTIONS, which was mailed in January, were distributed : TRANSACTIONS, Volume 73, 1241 pages, covering papers on non-ferrous metallurgy, milling and concentration, non-metallic minerals, iron and steel, and the Institute of Metals Division papers read at the

Jan 1, 1928