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By Lawrence Addicks

SOME three years ago the smelter connected with the Chrome, N. J., refinery of the United States Metals Refining Co. found itself embarrassed y constantly increasing piles of unsmelted blast-furnace flue dust. The charge was fine and 10 to 15 per cent. of it was blown over into the flue. Sulphur was at that time too scarce to make the sintering of the finer part of the charge attractive, and raw-ore smelting in a reverberatory with a partly oxidized charge. was not to be thought of. A great many schemes were considered, including leaching, blowing into the converters, and briquetting, the problem finally narrowing down to blast roasting and nodulizing. It was found by experiment that blast roasting would not yield a satisfactory sinter without the addition of coke dust or sulphide fines to augment the fuel value of the flue dust, and on this account, together with the low first cost of a kiln, the latter was decided upon. A couple of tons of flue dust Were tried out in the experimental kiln in the laboratory at Yorktown, Va., of J. H. Payne, who acted as consulting engineer in this connection. This kiln was approximately 2 ft. in diameter and 20 ft. long and Was fired with fuel oil. A run of several hours yielded excellent nodules. The kiln showed no tendency to build in and form "nose rings" and gave a fuel consumption of 50 gal. of oil per ton of flue dust. There was no indication of any stack loss. The roasting was strongly oxidizing. A study of what full-size kilns were doing on cement clinker and on nodulizing pyrites cinder indicated that a 60 by 6 ft. kiln would certainly not consume over half of the oil per. ton of flue dust shown on the test and as fuel oil at that time Was selling around 2 1/2 c. per gallon it was decided to let it go at that.

Jan 7, 1914

By Charles Barrett

METALLURGISTS are making use of the stereographic projection to a steadily increasing extent. In the last five years no less than 20 papers in American metallurgical journals alone have employed the stereographic projection; recent books on physical metallurgy, plastic deformation, X-rays and their applications, and crystal structure use it. Mineralogists have used the stereographic projection for many years in the description of symmetry classes and crystal planes, for it presents an accurate, easily understood plot of any angular relations in crystals with all unessential features eliminated (such as the accidentally deter-mined size and shape of crystal faces). In metallography and physical metallurgy the projection is much used for the analysis of markings appearing on polished grains: slip lines, twins, cracks, structures formed by precipitation, magnetic-powder patterns, etch pits, etc. Data from certain types of X-ray photograms are most conveniently analyzed by its use, particularly those for determining the orientation of single crystals or the preferred orientation of grains in an aggregate. Calculations of how to tilt or cut a crystal parallel to a certain crystallographic plane or to reflect X-rays from a certain plane are rapidly carried out. It has been adopted almost universally to the exclusion of other methods by those studying the deformation of metallic crystals, save where the accu-racy required is greater than a few tenths of a degree. Any directional property in a crystal or polycrystalline material can be shown on a stereo-graphic projection; for example, the modulus of elasticity, yield point, etc. It has been repeatedly called to our attention that there is need of all elementary explanation of the principles and methods of stereographic projection, covering all the, common applications in the field of metal-lography and physical metallurgy. The following contribution is an attempt to fill this need. The description of each method is supplemented with references to publications in which the method has been used. For convenience to the reader, these illustrative references are chiefly in American journals, particularly the publications of the American Institute of Mining and

Jan 1, 1937

By R. F. Stewart, A. W. Hall

A method has been developed for continuously measuring the moisture content of coal. The method is based on the thermalization of fast neutrons by hydrogen in the coal. Neutrons from a small radio-isotope source penetrate the coal, are scattered by hydrogen, and measured by a thermal neutron detector. The number of thermal neutrons counted can be directly correlated with the moisture content of coal. In a pilot-scale system, moisture was measured continuously within 0.2% in coal moving at rates up to 20 tph. The method is adaptable in industry for continuously measuring the moisture content of coal at high tonnage flow rates. Such an application would permit continuous recording of moisture in coal without sampling and facilitate quality control. An automatic and continuous method of measuring the moisture content of coal is needed by the coal industry. Automatic control of the coal quality would reduce the cost of coal preparation, improve the product, and thus indirectly increase the use of coal. Moisture in coal can be determined by several methods, but the time required to obtain samples and analyze them by existing methods makes it difficult, if not impossible, to control the quality of the product. Both producers and consumers need a method for continuous and instantaneous measurement of moisture content without sampling in order to regulate process equipment and keep the moisture content of coal within specifications. At the Morgantown, W. Va., Coal Research Center we are developing a nuclear method for continuous measurement of moisture in coal. This method is based on the thermalization of fast neutrons by hydrogen in the water and organic matter of coal. Neutrons from a small radioisotope source penetrate the coal, are scattered by hydrogen, and are measured by a thermal neutron detector. The number of thermal neutrons counted can be directly correlated with the moisture content of coal. Design of a moisture meter based on neutron thermalization depends on many variables, any or all of which can affect the sensitivity of the meter. These factors include those related to the nuclear aspect; type and size of neutron flux and source, type of detecting device, and background count; and those related to the coal being tested: rank, particle size, and ash content. A survey was initiated to eliminate the relatively insignificant factors and to ascertain the magnitude of the major effects. Such information was necessary to fully evaluate the technique and to establish design criteria. Coal contains a relatively large amount of hydrogen in the organic coal substance and the water of hy-dration of the shaly material as well as in the moisture. To apply this concept of moisture measurement to coal requires that the organic substance in coal from any one seam of a particular mine be uniform in hydrogen content. The difference in total hydrogen content of wet and dry coal is relatively small, so that a moisture measurement based on this concept requires a measurement between two large numbers to a high degree of precision. Thus, it was necessary to develop a highly precise instrumentation system for continuous measurement and to obtain a physical arrangement permitting measurement of moving coal with a minimum effect from density variation. EXPERIMENT WITH TRAYS OF COAL Tests were conducted with metal trays containing SO to 100 lbs of coal to develop an instrument system of high precision. A scaling system with a maximum instrument error of 0.2% was used to test different types of thermal neutron detectors. The most suitable type of detector was a boron-10-lined proportional counter tube. While this type of detector showed satisfactory stability, extensive testing disclosed a long-term count reduction probably due to some type of deterioration in the detector. However, development of an electronic system using dual detectors eliminated this deterioration as a serious problem. (The second detector would be used to measure a reference drum of dry coal — the difference in count rate between the wet coal and dry reference coal being a direct measure of moisture content.) Table I, column 1, shows typical results with a 1-curie plutonium-beryllium neutron source and a thermal neutron detector beneath a tray of coal and illustrates the precision of measurement. Consecutive measurements (indicated in Table 1, columns 2-5) of thermal neutrons at various times and positions be-

Jan 1, 1968

By B. Post, D. Moskowitz, F. W. Glaser

Lattice parameters of various hafnium compounds, two borides, a carbide and a nitride were determined. Some physical properties were measured and comparisons with the properties of the corre-sponing zirconium compounds were drawn. A LTHOUGH borides of transition metals have A been extensively investigated in recent years, there are few references in the literature to borides of hafnium. This is not surprising, in view of the extreme scarcity and great cost of the purified metal. Becker' reported the existence of a boride, carbide, and nitride of hafnium; he listed the formulas as HfB, HfC, and HfN. However, in his work no mention was made of chemical analyses of the reaction products. In this paper results of a study of various hafnium compounds, including borides, carbides, and nitrides, are reported. It was expected, of course, that these compounds would closely resemble their zirconium analogues, which have previously been extensively investigated. Three borides of zirconium are known: ZrB,² ZrB,² and ZrB212.4 In addition, one carbide, ZrC,5 and one nitride, ZrN,5 have been reported. It should be noted that ZrB and ZrB12 are stable phases only in relatively high-temperature regions, unlike ZrB2, which is stable from room temperature to its melting point." It was felt that hafnium would yield corresponding borides, carbides, and nitrides with similar stability ranges. Experimental Procedures and Results A quantity of hafnium metal that was better than 97 pct pure, with zirconium as its major impurity, was furnished by the Argonne National Laboratories. The boron powder used was approximately 96.5 pct pure. In general, the procedure involved mixing the metal and boron powders in the desired proportions, and subsequently hot pressing them. The resulting specimens were analyzed chemically and phases present were identified by X-ray diffraction methods. A Philips Norelco Geiger counter spectrometer was used for identification of components and for measurement of lattice constants. Filtered copper radiation was used for all X-ray work. Electrical resistivity and density measurements were carried out at room temperature. The stable diboride, HfB2, will be described first. Stoichiometric quantities of boron and metal were heated to approximately 2000°C during hot pressing. The reaction product was shown by X-ray diffraction methods to be isomorphous with ZrB2 (space group Dlgh; P6/mm). Values of lattice constants of HfB2 compared with those of ZrB2 are shown in Table I. The calculated density of HfB2 is 11.2 g per cc, compared with a measured (pycnometric) value of 10.5 g per cc. HfB2 specimens prepared under a wide variety of conditions (including variations in initial Hf-B ratios) showed only insignificant variations in lattice constants, indicating a very narrow range of homogeneity. Like ZrB2,7 HfB2 is an excellent electrical conductor. The resistivity at room temperature of hot-pressed samples, approximately 85 pct dense, is 12 microhm-cm. This compares favorably with the electrical resistivity of 10 mi-

Jan 1, 1954

By G. F. Loughlin

MORE than 20 years have passed since the publication of Lindgren and Ransome's report on the Cripple Creek District,1 which was made when the district was much more active and prosperous than in recent years. They concluded that the output of the district, which had reached its maximum of about $18,200,000 in 1900, would gradually decline, and their conclusion has been confirmed by records of subsequent production. Between 1905 and 1915 annual declines were partly compensated by encouraging increases, especially in 1908, 1914, and 1915; but a rapid continuous decline followed, due largely to the war and its after effects, until in 1922 the value of output was only slightly more than $4,000,000. It rose to nearly $5,000,000 in 1924, but declined again in 1925 and in 1926, when it was about $4,400,000, and represented ores mainly from deep levels in the Cresson and Portland mines. The profitable operations of these two mines were the principal factors leading to a study of ore at deep levels in the district by the U. S. Geological Survey in coopera-tion with the Colorado Metal Mining Fund. The principal reasons for Lindgren and Ransome's conclusion were three: (1) the greater cost and difficulty of deep exploration; (2) the decrease in the number of veins with increasing depth, and (3) the probability that the telluride ore, believed to have formed at comparatively low temperature, would not persist indefinitely -in depth. Operations since they made these statements have verified the first two, but call for some modification of the third. Rich telluride, ore is being mined at a profit in the Portland mine 3000 ft. below the present surface, or 5000 ft. below the original surface of the Cripple Creek volcano, as interpreted by Lindgren and Ransome. The question arises, therefore, as to the number and extent of such deep deposits, and the answer, so far as it can now be given, must be based mainly on structural data, supplemented by data on the processes of ore deposition. Presentation of these data based on a study of deep mines in the southeast quarter of the district, the only

Jan 1, 1927

By R. G. Weavind

ONE of the most important fields of investigation at the Diamond Research Laboratory in Johannesburg is concerned with improvements in metallurgical practices for the diamond mining companies, with particular reference to increased recoveries of the smaller industrial stones. Considerable work has been done on the possible application of flotation processes to the diamond industry.

Jan 7, 1951

By William J. Gillich, Gerald L. Moss

PREVIOUS studies of the shock loading of randomly oriented polycrystalline aggregates have firmly established that, after rather short load duration, hydrostatic compression closely approximates the shocked state.' However, McQueen deduced from pressure measurements with good time resolution that, during shock loading, metals begin to undergo a stress relaxation at the yield stress. He suggested that the relaxation is due to plastic deformation accompanying the change from a one-dimensional compression to a three-dimensional, hydrostatic, compression.' Stress relaxation may occur faster as stress is increased above the yield stress, but the existence of unidirectionally compressed states for finite times suggests that the concept of a unidirectionally distorted lattice should furnish considerable insight into the mechanical behavior of materials subjected to shock loading. Here, a crystallographic analysis is presented for the hypothetical situation where atom motion may be considered as unidirectional which, as indicated above, is a useful extension of the macroscopic concept of shock loading to the microscopic domain. Only motion caused by the com-pressive forces is treated; i.e., lattice vibrations upon which this motion is superimposed, as discussed by Fitzgerald, are ignored.3 The purpose of the analysis to be presented is to develop a description for single crystals of the lattice rotations that occur for idealized uniaxial strain deformation. The usefulness of such an analysis in realistic deformation is to give a method of specification of those properties of an initially distorted lattice which would affect the subsequent deformation. Non-axial complications that arise experimentally, such as off-axis rarefaction waves, must be treated in proper context. Consider the material element shown in Fig. 1 and let the compression be uniform at all regions of the element. Then, any interior point of the element is displaced in proportion to its distance from the base of the element. Accordingly, if the top of a unit element is displaced by an amount, (-K), with respect to the base, a point P(X, Y) will be displaced by (-KY). Crystal planes are, therefore, rotated by the compression. Analysis of this rotation may be accomplished from the geometry shown in Fig. 1 where the line OP is the edge of the plane {hkl} and N is its normal. The orientation of the crystal plane with respect to the shock direction is specified by the angle, before deformation. After deformation the edge of plane {hkl}

Jan 1, 1969

By E. Marburg

Most ingots complete solidification vertically rather than transversely. This conclusion is based on complete solidification patterns of big-end-up and big-end-down ingots developed from dumped and split ingots. New mechanisms for segregation in ingots are proposed. Internal soundness in ingots is found to depend upon adequate width of vertical core. A LTHOUGH it has long been recognized that the A internal soundness of ingots is principally been recognizedthatthedependent on the process of solidification, knowledge of this process is still only fragmentary. The mechanisms causing the several types of segregation in ingots, which mechanisms are necessarily related to the solidification process, are not well understood. In absence of a better conception of the solidification process, it seems hardly surprising that mold design varies widely. Guiding principles for mold design are needed. At stake in the improvement of ingot quality are not only improved properties of steel but also appreciably higher yields of sound steel, which would considerably decrease manufacturing costs. In the present study, following a general description of the several types of segregation in ingots, Fig. 1, complete solidification patterns of a big-endup and a big-end-down ingot, including the zones of accelerated solidification, have been reconstructed. In both ingots, a core of vertical solidification extends from the base cone to the hot-top junction. Based on the finding that ingots complete solidification vertically rather than transversely, as has been previously assumed, new mechanisms for segregation in ingots are proposed. Internal soundness in ingots is found to depend upon the width of the vertical core, which in turn depends principally upon the width to height (w/h) ratio of the ingot. Solidification patterns of ingots are of three general types: 1—those in which vertical solidification does not reach the top, 2—those in which vertical solidification just reaches the top of the ingot, and 3—those in which vertical solidification reaches the top some time before transverse solidification would reach the middle of the ingot, so that a vertical core of definite width at the top of the ingot is developed. Axial defects vary characteristically with the solidification pattern. Examples of ingots of each type are presented. Dumped ingot data reported by Nelson' have been used in developing families of curves of transverse and vertical solidification, and in deriving the effect of the w/h ratio upon the solidification pattern. Photographs of many ingots split at Homestead and at Duquesne Works, United States Steel CO., as well as those published by the British Iron and Steel Institute,' have been studied and analyzed. In the interest of brevity, only typical ingots of each type or classification from the above sources have been reproduced. Segregation in Ingots Segregation in ingots falls into three principal classifications: 1—lamellar segregation, as revealed in sulphur prints (Figs. 2 and 3); 2—zone segregation, or broad variations in composition; and 3— interdendritic, or microsegregation. The last class, of minor importance, is not considered here. When liquid metal cools, according to the theory of differential or selective solidification,2 metal of relatively high purity selectively solidifies first. Liquid segregates (principally carbon, phosphorus,

Jan 1, 1954

By Henry S. Munroe

The plan of organizing a summer class of students of tha Bchool of Mines, for the practical study of mioing and miner's work, rewived at the outset the following cordial indorsement: ...." 1 have thonght over the plan proposed by you of taking the students to the mines during the summer, acd of having them actuaily ttrke part, under the direction of skilled worktnbn, in dl the various kinde of mining work; and of using them as a cerps of engineers to make inside and outside surreys, particularly with a view to the detailed study of the geology of the mine. I have no beitation in saying, that if the students have been previously instructed in the theoretical part of thrir studies, by lectitras and practice during the winter, the plan would be an admirable one. Of courae experience will suggest modiflcations of detail. Frorn the work you have done at our mines this spring, I feel sure that you would be perfectly competent to curry out your plan, and 1 shall gladly aid you in uny wny I can. " Yours, sincerely, The plan of the proposed summer school thus indorsed by Mr. Coxe was adopted by the trustees of Columbia College, and an appropriation of one thousand dollars, or so much thereof ss might be necessary, was voted for the experitneat. A volunteer class of thirteen students was formed, and the first summer school was held at Drifton, in July and August of that year (1877). The following extract, from an editorial notice in the iden of the organization of the school and the work required of the stiudens. "The students, on reporting to Professor Munroe, were divided into sqoade of two or three men each, and on Monday, July 2d, were aesigned to the qre of skilled miners, selected for the purpose by the mine boss, for instruction in gangway work. Half of the students worked in the morning and the other half in the atternoon, one squad at a time with each miner, The times of going and coming to and from work were so arranged that each student spent four to four and a half hours in the mine each day. While in the mine they assisted the miner to load his car, thereby learning readily to distinguish I slate ' and

Jan 1, 1881

By A. A. Smith, J. S. Smart

THE controlled amounts of phosphorus, arsenic, sulphur or selenium found in commercial coppers perform a variety of highly useful functions. Indeed, a large segment of modem copper technology is essentially dependent upon the presence of one or more of these elements. Consequently, the literature contains many references to their effects but the scope is broad and has been only partly covered. New data are presented herewith directed toward a better understanding of the basic behavior of these elements in copper, with particular emphasis on the composition range 0 to 0.05 per cent. These data are a part of a general program of research on the effects of impurities on the properties of oxygen-bearing and oxygen-free copper, other portions of which have been reported previously.1-2-3 Schematically, the behavior of individual elements is determined from measurements of conductivity and softening temperature,1, 2 and the binary alloys employed are synthesized from high-purity copper in order to eliminate interference from the effects of extraneous impurities. Alloys of selected composition were first prepared in the oxygen-free form by continuously casting the melts in the form of 3/8-in. diameter rod. Oxygen was added subsequently to portions of the alloys, either by remelting or by diffusion at 850°C. from a surface scale. Test wires were drawn one B. and S. number per pass, using four 30-min. 600°C. anneals at o.3125, 0.257, o.204 and o.162 in., and a final cold reduction of 95 per cent t0 0.081 in. Oxygen-bearing slugs made by remelting were hot-rolled to 5/16 in., drawn to 0.162 in., annealed for 30 min. at 600°C. and cold-drawn 95 per cent to 0.081inch. The alloys containing phosphorus, having been compounded very early in the program, were prepared in the form of 5/16-in. rod, and processed to wire with only the last three intermediate anneals listed above, all of these having been conducted in commercial nitrogen. In addition, the conductivity anneals on these alloys were also performed in the same atmosphere, and the small amount of oxygen present as an impurity in the gas resulted in some loss of accuracy at temperatures of 700° to 800°C., as will be shown later. Subsequently, the anneals for all oxygen-free alloys were conducted in hydrogen to prevent oxidation, and purified nitrogen was employed only for oxygen-bearing samples. All conductivity anneals were of one hour duration followed by a rapid quench in 10 per cent H2SO4. EFFECT OF PHOSPHORUS The widespread use of phosphorus as a deoxidant has resulted in universal appreci-

Jan 1, 1945

The 118th, meeting of the Institute, which has been arranged primarily for the benefit of the Institute of Metals Division and of those members who are particularly interested in iron and steel, will be held in the Milwaukee Auditorium, Milwaukee, Wis., on Oct. 8 to 11, 1918. This date has been selected because at that time, and at the same place, the American Foundrymen's Association and the American Malleable Castings Association will hold meetings. A notable exhibit of metallurgical and mechanical processes and products, at which over 165 firms will be represented, has been arranged in Machinery Hall, of the Auditorium Building. Wherever practicable, the machinery will be in operation. The program of the Institute's sessions was published in Bulletin 141. A special announcement of the meeting, together with a program of the sessions of the American Foundrymen's Association, has been mailed to every member who was thought to be directly interested in the meeting. A report of the meeting-and of the discussion of papers will be printed in the December Bulletin.

Jan 10, 1918

By Archer E., Wheeler

COPPER operations in the Congo mean the operations of the Union Miniere du Haut Katanga, because there are no other copper industries there. There is a mine at Bwana M'Kubwa, a little way to the South, in Rhodesia, which has been operated on a small scale, and-another farther south, the Falcon mine, but in quite a different section of the country. This Bwana M'Kubwa mine has recently been reorganized financially and the Minerals Separation interests have taken an extensive share in it, so that it may come into operation. The Union Miniere's operations are in Katanga, the most southeastern province of the Belgian Congo, and the company's concession is in the southeastern part of that province. The usual route for going into the country is by way of Cape Town, thence over the South African Railways through Kimberly and Mafe- king to Bulawayo, then by the Beira, Mashonland and Rhodesia Railways to the Rhodesia-Congo border, passing Victoria Falls on the way, and finally by the Belgian road, the Chemin de Fer du Katanga, to Elisa- bethville, the African headquarters of the company. From Cape Town to the border it is about 2150 mi. and from the border to Elisabethville about 158 mi., making a little over 2300 mi. from Cape Town, by rail.

Jan 1, 1924

By T. J. Bosworth

The effect of hydrogen pretreatment of alumina, magnesia, and zirconia crucibles on reduced oxygen levels in iron charges has been studied. Hydrogen treatment of commercial high-purity magnesia crucibles was observed to produce as high as 70 pct reduction in oxygen content in iron melts. Hydrogen treatment of the commercial high-purity grade zirconia crucibles produced a 25 pct reduction in oxygen levels in iron melts. An average reduction of Knoop hardness of 47 pct was recorded on the iron charges melted in hydrogen-treated crucibles. On the basis of the experiments and the free-energy diagram, it appears that the major source of reducible oxygen to the iron charge is the suboxides and impurity oxides rather than the major oxide of the crucible. Suitable pretreatment of the crucibles to reduce and remove these oxides yields low oxygen levels in iron melted in the crucibles. DURING the last decade, attempts to produce more pure and uniform alloyed metals have brought about the development of many new melting techniques. Notable among these are vacuum-induction melting, inert and consumable-electrode melting, the cold-mold technique, and numerous techniques for removal of impurities by chemical reaction. However great the achievements in this field, metals must still be melted in contact with media of varying reactivity; i.e., gas, ceramic, and slag. Studies have been made to attain an understanding of the reactions that take place during melting, including slag-metal reactions and equilibria, equilibrium of hydrogen and water vapor, and carbon dioxide and carbon monoxide with oxygen in molten iron. These reactions have been treated quite thoroughly. There is one condition, however, that has been widely overlooked, and, to the author's knowledge, only cursive investigation has been made of it. This is the reaction between the ceramic crucible material and the iron charge. In recent years, Hadley and Bianchi' made a series of studies on hydrogen deoxidation of iron in magnesia crucibles. Bianchi2 studied crucible-FeO equilibria in the temperature range 1525°to 1650°C in high vacuum with, however, inconsistent results. Richardson and Jeffes3 in their series of articles on thermodynamic reactions in the making of iron and steel refer to Wentrup and Hieber's4 work on iron and aluminum deoxidation. Their pork included melting iron in alumina crucibles and measuring the aluminum and oxygen content in the iron. Because of the low values obtained, question has arisen of their analytical accuracy.3 Dastur and chipman5 obtained values on hydrogen-oxygen equilibrium in molten iron contained in alumina crucibles similar to those obtained in experiments in the present program. Hochmann6 studied removal of impurities in chromium irons in high vacuum. His results with respect to oxygen level in chromium-iron melted in magnesia crucibles are consistent with results we have obtained.

Jan 1, 1959

By R. H. Thielemann, E. R. Parker

The conventional short-time tensile test provides a reliable means of predicting the sustained load-carrying capacity of steels only when the temperature is such that continuous plastic flow does not occur. At elevated temperatures, stresses considerably less than the short-time rupture value may produce continuous flow, with fracture occurring only after long periods of time. The amount of flow or creep accompanying failure varies for different steels, and depends, to a large extent, on the temperature and the duration of the test. Service records of cracking stills, steam superheaters and high-temperature boilers have shown that brittle fractures sometimes occur with little or no warning. In installations of this type, localized stresses are often encountered, and steels must be capable of withstanding a certain amount of deformation without fracture. The sustained-load rupture test determines the expected life and corresponding ductility of steels at various stresses and temperatures. It also yields additional information regarding the effect of micro-structure and metallurgical stability on the high-temperature properties. Present Status of Sustained-load Rupture Test The sustained-load rupture test conducted at elevated temperatures is not entirely new. Dr. Zay Jeffriesl presented in 1919 the results of a large number of rupture tests made on copper, iron and tungsten. These tests were made with various strain rates and at temperatures ranging from the boiling point of liquid air to 1000° C. At that time he observed the interesting phenomenon characteristic of metals, that a temperature exists below which a metal is ductile and breaks with a transcrystalline fracture (through the grain) and above which the metal is brittle and breaks with an intergranular fracture (through the grain boundaries). He observed that this temperature varied with the testing speed, and that a minimum temperature, slightly above the recrystallization temperature, existed at which the cohesion of the grains themselves was

Jan 1, 1939

By Albert J. Phillips

As early as 1824, Haidinger' described crystals of native copper that were, according to Dana,2 " probably twinned parallel to the octahedral plane and normal to this axis." In 1837, Rose3 very clearly demonstrated that native copper crystals were commonly twinned on the octahedral plane. Lasaulx,4 in 1882, described polysynthetic octahedral twins and stated that enclosed twinning lamellae were observed. Even on crystals formed artificially by electrolysis, twinning was observed as early as 1886, by Brown.5 Many other descriptions of twinning in native copper and in gold and silver are to be found in the literature, and in every case with which we are acquainted the twinning is conformable to the spinel law; i. e., the octahedral plane is both twinning and composition plane. Metallurgists have long been familiar with the straight-sided bars or bands that commonly occur within the irregularly outlined grains of metallic crystalline aggregates. They are certainly found in nearly all metals of the face-centered cubic type after cold working and annealing. If a specimen showing these bands is rotated, keeping the angle of incidence of the illuminating beam constant, they usually exchange color contrast periodically with their respective matrix crystals. Also slip lines, when produced in these specimens, nearly always show a change in direction upon passing through the bands, giving rise to the "stairway" effect often illustrated in metallurgical textbooks. Apparently the only quantitative observations on bands of this sort were made by Osmond and Cartaud6 on austenitic steel. They selected,

For the year ending February, 1919 PRESIDENT SIDNEY J. JENNINGS NEW YORK, N. Y. PAST PRESIDENTS L. D. RICKETTS, NEW YORK, N. Y. PHILIP N. MOORE ST. Louis, Mo. FIRST VICE-PRESIDENT C. W. GOODALE, BUTTE, MONT. TREASURER GEORGE C. STONE, NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 11, 1918

By Herbert H. Kellogg

DEPOSITS of high-silica kaolinite clays occur at many places in central Pennsylvania. These white clays were formed apparently by weathering of argillaceous quartzite and limestone. Their geology, distribution and use have been reported by Leighton.1 The larger deposits have been mined from time to time, and the clay, after washing to remove coarse sand, has found use as rubber filler, foundry clay, and in white cements. In general, the clay from these deposits contains too much grit (quartz) to be useful as paper filler, and the silica content is too high to make it useful as china clay for ceramic ware. Gravity methods for the separation of quartz from these clays have failed because of the extremely fine size of the quartz grains, but by the methods of froth flotation described in this paper these sandy kaolins can be made to yield a purified kaolinite that has a chemical composition close to that of good-grade Georgia kaolins, and is free enough from grit to be used as a paper filler. As by-products of the separation, a fine (-325-mesh) sand assaying 95.5 per cent Si02, and a very fine (-3-micron) clay are produced. The possible ceramic uses of these products are being investigated at The Pennsylvania State College. EXPERIMENTAL PROCEDURE The Sample.-The clay sample used in these tests was obtained from a small mine near Tyrone, Pa. It had already been washed to remove coarse sand, and represented the finished product of this small mine and washery. Microscopic examination showed that the clay was composed almost entirely of the minerals quartz and kaolinite, and that the quartz was present mostly in particles larger than one micron, while the kaolinite particles generally were less than 20 microns in size. The kaolinite and quartz particles were physically separable by blunging the clay in water with a suitable dispersant. Preparation of Flotation Feed.-By the addition of NaOH in an amount equal to 3 lb. per ton of solids, the clay was completely dispersed in water. Flotation feed was prepared by allowing a dispersed suspension (10 per cent solids) of the clay to stand for the period of time required for a 2.5-micron particle of quartz to settle from the top of the container to the bottom. After this settling period the suspension was decanted from the settled solids. The settled solids were redispersed in water and the separation was repeated once. The two fine fractions were then combined. Thus the clay was divided into a fine and a coarse fraction by size separation at approximately 2.5 microns.* The fine fraction was found to have a considerably lower sand content than the raw clay (Table I), and was not treated further. The coarse fraction formed the flotation feed for all the tests described in this paper.

Jan 1, 1945

1. Healthy and active Local Section organizations, are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should.

Jan 1, 1939

By Saluja, Sunder S.

Man had to learn to break rocks as early as the Stone Age, when they formed his main source of raw material. He started with chipping and over the years has reached a stage where he can employ atomic blasts and break, with one blast, millions of tons of rock. In between these two extremes there have been several stages of development including fire setting, use of the expansion of water on freezing in chipped cracks in cold climates, the use of low or deflagrating explosive black powder in about the 17th century, the use of high explosives with the discovery of nitroglycerine in 1846 by Sobrero, followed by the monumental discoveries of the great Swedish scientist Alfred Nobel in the latter half of the nineteenth century.

Jan 1, 1968

By D. G. Westlake

Levine has concluded that prismatic slip in titanium is controlled by two distinct thermally activated processes in the temperature ranges O° to 220°K and 220" to 300°K. We feel that his evidence is not convincing. He has drawn a curve through the plot of activation volume u* vs temperature T with a break at 22WK, Fig. 2. We believe that considering the possible experimental error apd the fact that there are only four points between 4° and 196°K, one could be justified to represent these points by the smooth curve we show as a solid line in Fig. 12. Levine believes that (8rf/aT)+ is discontinuous at 220°K, but he hints that he recognizes the possible doubt. We doubt seriously that the results shown in Fig. 1 indicate a discontinuity at 220°K. Certainly if he were justified in drawing a straight line through only four points on Fig. 2, we are even more justified in drawing straight lines through the seven points between 77" and 297°K on Figs. 1 and 3, because a straight line touches all seven of his circles. If his measurements of t were so precise that his decision to draw two curves in Fig. 3 is valid, then the experimental technique is deserving of further mention. We have drawn a smooth curve through the results in Fig. 3 and used this and the curve in Fig. 12 to obtain the values of shown in Fig. 13. Finding continuous is a contradiction of Fig. 4, which deserves comment itself. Levine obtained the solid circles in Fig. 4 using Fig. 2 and a smooth curve through the points shown in Fig. 3. We have replotted these solid circles in Fig. 14. We submit that there is no basis for his two straight lines (dashed in Fig. 14), and therefore have superimposed the curve that we believe is indicated. Certainly, there is reasonable doubt that a discontinuity in dH/dT exists at 220°K, even when one accepts Fig, 2. Furthermore, if one draws the straight lines indicated by least-squares treatments of the results presented as open circles in Fig. 4, their intersection is at about 196°K, not at 220°K as shown. Thus the alleged agreement between Figs. 3 and 4 with respect to "break" temperatures is not apparent. In Fig. 9, Levine has drawn a straight line very much different from the one indicated by a least-squares treatment. Obviously, he has done this because he recognized that H = 0 when T = 0. He is consistent in drawing the low-temperature curves in

Jan 1, 1968