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On the Art of Metallography (Howe Memorial Lecture), by F. F. Lucas; Beneficiation of Iron Ore. Abstract of paper by C. E. Williams followed by Round Table Discussion; A Statistical Analysis of Blast-furnace Data, by R. 8. McCaffery and R. G. Stephenson; Air Discharge of Circular Tuyeres, by R. S. McCaffery and D. E. Krause; Open-hearth Steel Process as a Problem in Chemical Kinetics. by E. R. Jette; Carbon-oxygen Equilibrium in Liquid Iron, by H. C. Vacher and E. H. Hamilton; A Thermodynamic Study of the Phasial Equilibria in the Bystem Iron-carbon (Abstract), by Yap, Chu-Phay; Influence of Dissolved Carbide on the Equilibria of the System Iron-carbon (Abstract), by Yap, Chu-Phay; Inclusions and Their Effect on Impact Strength of Steel, I and 11, by A. B. Kinzel and W. Crafts: Method for Electrolytic Extraction of MnO, MnS, FeS and Si02, Inclusions from Plain Carbon Steels, by G. R. Fitterer; Permanent Growth of Gray Cast Iron, by W. E. Remmers; Some Notes on Blue Brittleness, by L. R. van Wert; Austenite-pearlite Transformation and the Transition Constituents, by A. Sauveur; Age-hardening of Austenite, by F. R. Hensel; Transformational Characteristics of Iron-manganese Alloys, by H. Scott; Composition Limits of the Alpha-gamma Loop in the Iron-tungsten System, by W. P. Sykes; Magnetic Properties Versus AUotropic Transformations of Iron Alloys, by T. D. Yensen and N. A. Ziegler; Dilatometric Study of Chrome-nickel-iron Alloys, by V. N. Krivobok and M. Gensamer; Low-carbon Steel, by H. B. Pulsifer; Bright Annealing of Steels in Hydrogen, by F. C. KeUey; Development of Continuous Gas Carburieing, by R. J. Cowan. Transactions, Institute of Metals Division, 1931. 500 pages. Index. Papers and discussions presented before the Division at Chicago, Sept. 22-26, 1930 and New York, Feb. 16-19, 1931. X-ray MetallograpIhy: X-ray Determination of Alloy Equilibrium Diagrams (Annual Lecture), by A. F. Westgren; Suppressed Constitutional Changes in Alloys. by G. Sachs; Texture of Metals after Cold Deformation; by F. Wever. Theoretical Metallurgy: Studies upon the Widmanatitten Structure. I.—Introduction. The Aluminum-eilver System and the Copper-silicon System; by R. F. Mehl and C. S. Barrett; Studies upon the Widmanstatten Structure, 11.—The Beta Copper-einc Alloys and the Beta Copper-alumnum Alloys, by R. F. Mehl and 0. T. Mareke; Application of X-rays in the Manufacture of Telephone Apparatus, by M. Baeyerts; Thermal Conductivity of Copper Alloys. 11.—Copper-tin Alloys; 111.—Copper-phosphorus Alloys, by Cyril Stanley Smith; Thermodynamic Study of the Equilibria of the Systems Antimony-bismuth and Antimony-lead, by Yap, Chu-Phay. Ganeral: Cemented Tungsten Carbide; a Study of the Action of the Cementing Material, by L. L. Wyman and F. C. Kelley; Influence of Casting Practice on Physical Properties of Die Castings, by C. Pack; Fabrication of the Platinum Metals, by C. S. Sivil; Effect of Certain Alloying Elements on Structure and Hardness of Aluminum Bronze, by 9. F. Hermann and F. T. Sisco. The WorkinG oF Metals: Metal Working in Power Presses, by E. V. Crane; Forming Properties of Thin Sheets of Some Nonferrous Metals, by W. A. Straw, M. D. Helfrick and C. R. Fischrupp; Die Pressing of Braas and Copper Alloys, by J. R. Freeman. Jr.; Plasticity of Copper-sina Alloys at Elevated Temperatures. by A. Morris: Directional Properties in Cold-rolled and Annealed Copper, by A. Phillips and E. 9. Bunn; Effect of Combinations of Strain and Heat Treatment on Properties of Some Age-hardening Copper Alloys by W. C. Ellis and E. E. Schumacher; Constituents of Aluminum-iron-silicon Alloys, by W, L. Fink and K. R. Van Horn; Equilibrium Relations in Aluminum-antimony Alloys of High Purity, by E. H. Dix, Jr., F. KeUer and L. A. Willey; Equilibrium Relations in Aluminum-magnesium Silicide Alloys of High Purity, by E. H. Dix. Jr., F. Keller and R. W. Graham; Constitution of High-purity Aluminum-titanium Alloys, by W. L. Fink, K. R. Van Horn and P. M. Budge; Experiments on Retarding the Age-hardening of Duralumin, by E. H. Dix. Jr. and F. KeUer; Aluminum-silicon-magnesium Casting Alloys, by R. S. Archer and L. W. Kempf; Modulurr of Elasticity of Aluminum Alloys, by R. L. Templin and D. A. Paul; Quenching of Alclad Sheet in Oil, by H. C. Knerr.

Jan 1, 1931

By S. Saito, P. A. Beck

The crystal structure of MoNi3 was determined by means of X-ray diffraction. This structure is isotype with that of ovgered TiCu3. The lattice parameters are: a. = 5.064A, bo = 4.224A, co = 4.448A, and zf 0.157. If the orthorhombic distortion (slight relative to the corresponding orthohexagonal unit cell) is disregarded, the structure may be described in terms of a close-packed ordered atomic layer, stacked in the sequence: abab. The structztres of ordered TiCu3 and TiAl3 are homotectic. The three types of ordered hexagonal phases, iso-structural with TiNi3, MgCd3, and VCo3, are known to occur in AB3 alloys of transition elements of the first, second, ad third long periods. It was noted1 that phases with the TiNi3 structure occur selectively in alloys of Ti-group elements with Ni-group elements. In AB3 alloys of Ti-group and V-group elements with Co-group elements the AuCu3-type structure predominates.' The vCO3 structure, which was determined very recently,' has hexagonal symmetry, but the actual atomic arrangement here, too, is rather closely related to the ordered cubic structure of AuCu3-type. However, an ordered hexagonal close-packed structure of the MgCd3-type occurs in MOCO33 and WCO3.4 Consequently, the question arises as to whether or not the crystal structure of MoNi3 is also of the MgCd3-type. Grube and winkler5 found that MoNi3 has a hexagonal close-packed structure with a = 2.54A and c/a = 1.65. They pointed out that some additional weak diffraction lines could be observed in the powder pattern, which may have been due to an ordered atomic arrangement in this phase. However, no detailed information was obtained by them and the structure was apparently not further investigated by others. The present work was, therefore, undertaken in an attempt to determine in detail the structure of MoNi3, and to investigate the possibility of ordering. EXPERIMENTAL METHODS Alloys used in the present work were arc-melted in a water-cooled copper crucible under helium atmosphere. Electrolytic nickel and molybdenum, both 99.9 pct pure, were used. Chemical analyses were not made, but the melting loss was not higher than 2 pct for any alloy. Ingots were first homogenized at 1200°C for 48hr, quenched, heavily cold worked, and then annealed at 820" or 860°C for 1 week, followed by quenching in cold water. Powder specimens for X-ray work were prepared by crushing the heat-treated solid specimens. In order to remove strains, the powders were reannealed in evacuated scaled fused silica capsules for 6 hr at the same temperature at which the corresponding solid specimens were annealed. X-ray photographs were taken with an asymmetric focussing camera, using unfiltered CrK or CuK radiation. EXPERIMENTAL RESULTS The X-ray diffraction patterns of alloys containing 20.8, 25, and 26.4 at. pct Mo, homogenized at 1200°C, showed the face-centered-cubic structure of the Ni-base a-solid solution. It was revealed, however, by micrographic examination that the 26.4 at. pct Mo alloy contained in addition very small amounts of a second phase, in accordance with the phase diagram.6 On the other hand, the 20.8 at. pct Mo alloy after annealing at 820°C gave the X-ray diffraction pattern of the ordered face-centered-tetragonal MONi4.7 In this pattern several additional weak diffraction lines were also observed, corresponding to the strongest diffraction lines of MoNi3. The alloys containing 25 and 26.4 at. pct Mo after annealing at 820" or 860°C gave X-ray diffraction patterns, as shown in Tables I and 11, corresponding to MoNi3. Each one of the reflections which could be tentatively indexed on the hexagonal close-packed cell of Grube and Winkler,5 with the exception of the basal plane reflections, was split into a doublet, as seen in Table I. Since microscopically the alloy consisted of a single phase, it seemed probable that the lattice of MoNi3 is actually slightly deformed, as compared with the tentative hexagonal unit cell. In addition to these diffraction lines, several weak lines were also present, as shown in Table 11, which could not be indexed at all on the hexagonal close-packed cell considered. Satisfactory indexing of all diffraction lines observed was found to be possible by using an orthorhombic unit cell with ao = 5.064A, ft = 4.224A, and c = 4.448A. These values, whose accuracy is estimated to approximately ± 0.008A, correspond to 95.14A3 for the volume of the unit cell, and to an X-ray density of 9.50 g per cm3. If no attention were paid to the weak reflections listed in Table II, a reduced -unit cell of half the volume (a = 2.532A, b = 4.448A, and c = 4.224A), closely related to the orthohexagonal cell, might be used. The dimensions of the orthohexagonal cell of the same volume as the reduced cell are: a = 2.562A, b = 4.437 A, and c = 4.183A. It may be seen that in the reduced cell the a axis is slightly shorter, while the b and c axes are slightly longer than those corresponding to the orthohexagonal cell of the same volume. This slight orthorhombic distortion is re-

Jan 1, 1960

By H. E. Elliott, R. S. Busk, A. T. Peters

One of the problems of the fabricator of metals and alloys is the propensity of some composition rarnges toward abnoermal grain growth during certain stages of fabrication. In this respect magnesium alloys are no exception among alloys. Fortunately, convenient foundry control methods have been developed by which the abnormal grain growth possible in certain magnesium-alloy castings can be suppressed. An unusual characteristic of magnesium alloys, however, is that castings of some composition ranges are subject to local grain growth during heat-treatment without the necessity of intentional mechanical stressing of the part prior to heat-treatment. This effect occurs only under certain critical casting conditions, and only in certain alloys of greater than about 8.5 per cent aluminum content, such as C alloy (Mg, 9 per cent A1, 2 Per cent Zn, 0.2 Per cent Mn) and G alloy (Mg, 10 per cent Al, 0.2 per cent Mn). The first observation of this phenomenon in cast magnesium alloys occasioned much surprise, since it is not observed in other meta1s- Jeffries and Archer1 have stated that "the grain size of cast metals, provided they have not been plastically deformed, cannot be changed by heating below the melting point." The study of the conditions leading to abnormal grain growth in cast magnesium alloys, and of the mechanism of this phenomenon, has led to some very interesting observations. Perhaps the most significant of these was the observation that stresses originating from cooling contraction in magnesium-alloy castings are the only stresses necessary, under certain conditions, to cause local recrystallization and subsequent grain growth in the casting during heat-treatment. Before recent developments, this phenomenon of abnormal local grain growth Was a definite problem in the production foundry on C alloy sand castings. Illustrated (Fig. I) is a picture of a casting scrapped because of this defect. A mottled effect is produced in coarse-grained areas by suitable etching solutions. The properties of metal in the affected area are much impaired by such grain coarsening. Ultimate tensile strengths of half the normal value have been measured in metal of this nature. In this paper are described the techniques that have been developed by The DOW Chemical Co. for studying, and in large measure solving, this production problem. Also discussed are studies of the mechanism by which excessive grain coarsening occurs, and the fundamental conditions that produce this effect. The abnormal grain growth discussed in this paper will be referred to as "germinasium since this term has been definedl as any process leading to an abnormally coarse grain size. This paper deals only with abnormal local grain growth that may occur during the solution heat-treatment of certain magnesium-alloy castings, as dis-

Jan 1, 1945

By M. H. Yoo

Possible interactions of the perfect dislocations of six slip systems or the c dislocation with the (10i2f (ioii), {ioIi}(ioiZ), {1122}(1123), and {1121}(ii26) type twins in hcp metals have been analyzed from the crystallographic and the energetic points of view. Twenty-six distinct types of possible interactions were identified, and those selected based on crystallographic constraints were examined for their energetic feasibilities by use of the anisotropic energy factors. No long-range elastic interaction exists for a dislocation when its Burgers vector is parallel to the twin interface. Under a suitable applied stress, a screw dislocation can cross slip at the twin interface. For basal mixed dislocations in cadmium and zinc, the interaction with {1012} twins is found to be attractive, indicating that incorporation of these dislocations into the twins is energetically feasible and that twin growth will result. On the other hand, the interaction between both basal and Prism mixed dislocations and the {1012} and (1121) twins is found to be repulsive in Mg, Co, Re, Zr, Ti, Hf, and Be. This indicates that under an applied stress a local stress concentration will develop due to a dislocation pileup at the interface, which may result in a site for either the nucleation of other twins or the formation of a crack, depending on the cleavage strength. WHEN a metal undergoes plastic deformation, a certain configuration of slip dislocations will result in a state of dislocation pileup against an obstacle. The stress concentration thus developed may enhance the process of twin nucleation and also twin growth. Furthermore, once formed and dispersed in the crystal, twins can act as effective barriers against slip dislocations. The degree of such mutual influence or interrelation between slip and twinning is generally known to be pronounced in the case of hcp, metals. It is also known that deformation by twinning occurs more commonly in hexagonal metals than in cubic metals. In fact, under suitable stress states, all hexagonal metals exhibit {1012) <1011> type twinning.&apos; In addition to this common type, deformation by (1151) <1126> type twinning occurs in zirconium, titanium, and rhenium, which show remarkable ductility.&apos; The importance of twinning during general deformation to the ductility of hcp polycrystals has been briefly discussed in recent review works.2&apos;3 The purpose of this paper is to analyze the interaction between slip dislocations and twins in the hcp structure and to discuss the nucleation and growth processes of twinning and the role of twinning in the <"°" noil) o, 1/3[112O] (OOO2) 1/3[1123] Fig. l—-Slip systems in hcp structure. ductility of hexagonal metals. The problem will be discussed from the geometric and the energetic points of view in a manner similar to that of the previous work on zinc.4 Since hcp crystals deform by several slip and twin systems, numerous interactions result as possibilities. The Burgers vectors of six slip systems and the c dislocation shown in Fig. 1 and the four twin systems listed in Table I are considered here. A complete tabulation of the possible interactions is followed by discussion of those that are more likely to occur on the basis of crystallographic constraints and energetic considerations. 1) CRYSTALLOGRAPHY OF TWINNING The crystallographic elements, K1, K2, n1, and n2, for the four compound twin systems are now well established.= A unit cell with the base vectors n1, and n2 is shown in Fig. 2 for each twin system. The unit cell before twinning is shown in solid line, and the corresponding unit cell after twinning is shown in dashed line. Also shown in Fig. 2 are the following crystallographic parameters: S is the plane of shear, d the interspacing of the twin habit planes K1,Ø Iis the acute angle between n1, and n 2, e is a numerical factor, and q is the number of K, lattice planes intersected by 17&apos;. These parameters can be expressed in terms of the axial ratio, y = c/a, as listed in Table 11. The macroscopic shear strain of twinning, s, and the magnitude of a "unit twin dis-l~cation,"4 bt, are also expressed in terms of y and given in Table 11. In Table 11, K1 and q1 are given in both Miller-Bravais and Miller indices. In double lattice structures, shuffling of atoms in addition to a homogeneous shear of the lattice is generally required if the original crystal structure is to be restored after twinning. The extent of current understanding on this problem of atom shuffling is per- Table I. Four Twin Systems in Hcp Structure

Jan 1, 1970

Abbey, Robert Graham, District Mgr. The W W. Sly Mfg. Co,. 50 Church St, New York, N. Y. &apos;21 Abbott, A. N., Mines Supt., Mazapil Copper Co., Ltd ..Concepcion del Oro, Zac., Mexico. &apos;23 Abbott, Argyle Campbell, Dev. Dept, E I du Pont de Nemours & Co, Wilmington, Del. &apos;29 Abbott, Clarence E., V.P, Charge of Raw Materials, Tenn. Coal, Iron & R. R. Co, 1242 Brown-Marx Bldg, Birmingham, Ala. &apos;04 Abbott, Louis Benjamin, Chief Engr., Elkhorn Div., Consolidation Coal Co, Jenkins, Ky. &apos;15 Abeel, George H., Jr., Cons. Min. Engr Box 427, Santa Monica, Cal. &apos;18 Abel, Albert E., Asst. to Pres, Valley Mould & Iron Corp Hubbard, Ohio. &apos;19 Abel, Raymond L., Asst. Prof., Dept. of Pet Refin., Univ. of Pittsburgh Pittsburgh, Pa. &apos;28 Abell, Leo M., Research Engr, Sullivan Concentrator Chapman Camp, B. C., Canada. &apos;31 Abernathy, George Elmer, Prof. of Geol. & Min . Kansas State Teachers College, Pittsburg, Kans. &apos;20 Aborn, Robert H., Research Lab, U. S. Steel Corp. Lincoln Highway, Kearny, N. J. &apos;19 Abozeid, Mahmood, Dept. of Mines & Quarries Cairo, Egypt. &apos;26 Abraham, Arthur W. Box 1466, Bakersfield, Cal. &apos;20

Jan 1, 1923

The Board of Directors, at its meeting on March 22, 1918, extended an invitation to the American .Institute of Metals to become the Institute of Metals Division of-the American Institute of Mining Engineers in accordance with the terms of By-Law VII. This invitation was presented to the membership of the American Institute of Metals for letter ballot, and, at the meeting of the Board of Directors of the American Institute of Mining Engineers on April 26 191 ,it-was reported that the replies had been in favor of accepting the invitation. The American Institute of Metals therefore becomes a division of this Institute and the members thereof are entitled-to all privileges of regular

Jan 6, 1918

By Edward W. Parker

THE agreement of September, 1922, between the anthracite operators and the United Mine Workers of America, which followed the 54.5 months strike during the summer of that year, contained the following provision : The parties unite in a recommendation to Congress that legislation be forthwith enacted creating a separate anthracite coal commission with authority to investigate and report promptly on every phase of the industry and the parties hereby ask the President to request the enactment by Congress of the recommended legislation. The continuance of production after Aug. 31, 1923, shall be upon such terms as the parties may agree-upon in the light of the report of the Commission.

Jan 1, 1924

By W. E. Ruder

It has been pointed out by Stead1 that grains of considerable coarseness may be developed in steels containing from 3 to 5 per cent. of silicon, and in a previous paper2 the present author has shown that under the proper conditions of annealing single grains having an area of 50 sq. cm. may be obtained. It is the purpose of this paper to discuss in more detail the conditions promoting the growth of these grains, in the hope that the experiments described may throw some additional light upon the general problem of grain growth in metals. These silicon steels lend themselves particularly&apos; well to such experiments because of the ease with which the change in structure may be followed and because of the fact that the effect of the carbon present is largely obliterated by the high percentage of silicon. This forms a solid solution with the iron, which acts very much like a pure metal. This alloy has been found to have but one critical point, viz., Ar2. This point, determined by Roberts-Austen for Hadfield&apos;s 4 per cent. Si alloy, was found to lie at 703" C. Vigouroux3, in working with pure Fe-Si alloys, finds this point to rise from 750" C. for 0.5 per cent. Si to 860" for 6 per cent. alloy, with a flat region in the curve from 3 to 4 per cent. Si. No accurate determination of this point has been undertaken by the present author, but it has been roughly determined to lie between 730" and 750:. In the preliminary experiments, some of which have been described in a previous paper, it was found that practically all of these steels, when annealed to 1,200" C. or higher, showed grains of comparatively large size. These grains varied in size, however, from about 4 sq. mm. to 50 sq. cm. (see Figs. 1 and 2) under the same conditions of anneal, and it was for the purpose of determining the cause of this difference in size that the experiments herein described were undertaken. From a preliminary study of the chemical composition of the specimens

Jan 1, 1914

By R. J. Wysor

Since the outbreak of the European war, few problems of raw-material supply have commanded more nation-wide attention than potash. It is well known that before the war the domestic production of potash was an insignificant percentage of the imports. The average annual importation of raw potash salts for several years prior to 1914 was slightly over 300,000 net tons, and of other potash manure salts about 700,000 tons. The sudden and almost total cessation of these imports created a unique and stringent situation. Methods of recovering potash from feldspar and other native mineral sources, and reclamation from hitherto waste products, have received a marked impetus. Soaring prices have been a keen incentive to research and industrial development. Although several brief articles concerning the possibilities of potash recovery have appeared in recent trade journals, it still may be a matter of some surprise to the average technical mind that potash might be reclaimed as a profitable byproduct in the manufacture of pig iron. At the present time it may be of special interest to present some data, largely of a technical nature, on this subject. A fairly thorough search of the literature reveals a number of articles concerning salts of the alkali metals in the blast furnace. Many of them deal with the theoretical rôle of alkali cyanides in the furnace. Several discuss the probable effect of the alkalies on the furnace brickwork. Two or three ambitious patents have been granted for reclaiming potash or other products from blast-furnace gas. However, we have heard nothing further as to the practical application of these patents. Little literature of importance has appeared during the last 10 years concerning alkalies in blast-furnace practice, and I have discovered no record whatsoever as to the actual sale or commercial disposal of flue dust for its potash content until this was inaugurated in our plant at Bethlehem. A bibliography of the most important articles discovered is appended. About 4 years ago, in the course of investigating blast-furnace stove efficiencies, I analyzed the fine, yellowish fume of which a considerable

Jan 1, 1917

Bernard MacDonald, Guanajuato, Mexico (communication to the Secretary*):—Mr. Iceyes&apos;s paper is very interesting to me because of my personal experience with the development of the ore-deposits of Lake Valley.

Jan 1, 1909

By Joseph W. Richards

ALTHOUGH bad grammar, the above query is probably, at the present moment, good sense. Why was the Institute started and why does it continue to exist? The small group of men who worked out the original idea felt keenly the necessity of mining engineers and metallurgists getting together in order to discuss their professional problems. That necessity still exists but it does not strike the present generation of engineers so keenly because they have always had the Institute: they do not know what it is to be without it. The Institute is a great graduate school of mining and metallurgy. All of its members who have something to say worth saying are the teachers; all the rest may be learners or critics. No university or technical school can match the experience and information which the authors of its papers possess, no institution of learning has a body of potential listeners so extensive and so vitally interested.

Jan 1, 1921

By H. O. Hofman

With the exception of the exhaustive paper on the Father de Smet mill, by its designer, Mr. A. J. Bowie, Jr. (Bans., x. 87), nothing, so far as the writer is aware, has as yet appeared on the stamp-mills of the Black Hills of Dakota, although they have been steady producers for the last ten years. Within the small area of about 6000 by 1600 feet, $2,271,341.14 was produced in 1887† from rock averaging $4 per ton in free gold. I. The Ores. Character of the Ores.—The gold of the district is found in quartz and pyrites finely distributed through vast bodies of mica- and amphibole-schists, argillites and phyllites, and also impregnating the schists themselves. The " Belt," embracing the section of Lead City, Terraville and Central City, is the only part worked at present. The principal associated mineral is iron pyrites, with some arsenopyrite and chalcopyrite, garnet and asbestos. The ores from open cuts and upper levels are more free-milling. than those from underground workings below water-line. Hence

Jan 1, 1889

US 4,190,434 - In the thermal production of magnesium metal, a mixture of calcined dolomite, an iron- silicon-aluminum alloy as a reductant, and residual slag from the production of ferrochromium is smelted to evolve magnesium vapor, which is then condensed. The use of bauxite is lessened or eliminated because of the relatively high alumina content of the residual slag. R. Bonfils, A. Mena, C. Payn, and L. Septier, assigned to Ste. Francaise d’Electrometallurgie (SOFREM). Feb. 26, 1980. 6 pp. (75-10R). Filed: 6-14-78 (915,387). Priority: France, 6-24-77 (77/20,227).

Jan 1, 1982

By David Sinclair

THE dimensions and shapes of mine structures may at present be determined by (1) field experience, (2) structural calculations, and (3) barodynamic tests.§ None of these, however, provide information as to the stresses, their direction and distribution in a mine structure. For the design of pillars, the placing of openings relative to working places such as gangways, haulage levels, etc., this information is desirable. Photoelastic methods provide this and, while relatively new, their appli-cation in all engineering fields is assuming increasing importance. This paper, therefore, will present the method with a few applications to mining, and with sufficient reference for further study by the reader. PART I THE PHOTOELASTIC METHOD The photoelastic method of stress measurement determines the stress distribution in a two-dimensional model by optical means. It makes use of the fact that when a piece of isotropic transparent material, such as glass, celluloid, or Bakelite, is stressed and viewed in polarized** light a picture is seen which indicates by its color bands of light, or fringes, the magnitude of the stresses, their direction and their distribution.

Jan 1, 1940

By R. D. Parks

DESPITE the handicap of reduced production in many districts, the mining industry in 1938 forged steadily ahead toward solution of its minor technical problems and has of-defected major advances in several fields. In California hydraulic mining for gold, shut down for forty years, will shortly be resumed following revision of restrictive laws. Disposal of hydraulicked ground is to be regulated by settling dams so as not to interfere with agriculture. Gold mining has been aided also by the development of a new high-efficiency dry amalgamator which applies the Ramsay mercury separator to the original de Phily process. Based on the principle that crushed ore will follow a rod into a mercury bath, this simple device is primarily adapted to dry areas and is to be available in small, multiple units suitable

Jan 1, 1939

By Frank Rieber

THE discovery that strongly magnetic bodies localized near the surface of the earth could be detected by the distortion which they produced in the resultant magnetic field marked the beginning of magnetic surveying methods. From an original ability to detect bodies of magnetic iron ore and the like when located very close to the, surface, these methods have been extended until today they promise to give much information with regard to the structure of such slightly magnetic material as sedimentary rock containing only a very small proportion of iron.1 The recent extensions have been made possible through the development of more delicate instruments, and of methods for their use. From the original compass and dip needle, the design of apparatus has progressed until equipment Is typified by magnetic balances capable of measuring the components of the earth&apos;s field to an extremely high degree of accuracy. It seems unlikely that the limit of such instrumental development has been reached. Just as the change from compass and dip needle has enabled the location of relatively minor changes in magnetic materials, so additional developments in the direction of increased sensitivity, as well as in greater dependability and constancy of operation, should reveal positively many slight changes which either escape notice in the present surveys or are so small that they cannot with certainty be separated from uncontrollable errors due to inconstant operation of the equipment. The ability to read smaller and smaller variations does not mean, of course, that deductions as to the causes of these variations will be made as accurately and definitely as -is possible with the more pronounced anomalies.

Jan 1, 1928

By R. J. Reynik, F. R. Meeks

IN the classical paper1 of Mehl and Rhines entitled "The Rates of Diffusion in the Alpha Solid Solutions of Copper", the authors state: "It has been mathematically demonstrated that the treatment of the data as though the diffusion were taking place between two flat plates instead of radially in a cylinder has no appreciable effect upon the results. Were the bars of a much smaller diameter, a modification of the analytical treatment would have been required." Unfortunately, the errors in the reported concentrations are much too large to neglect, as shown in the results below. A planar treatment of diffusion data assumes that the reference planes separated by a nominal distance (AX) have identical areas. An adjustment must be made on the concentration data should the successive diffusion planes differ in area. The Mehl-Rhines&apos; diffusion samples were cylindrical with copper electroplated onto copper-based alloys. Successive surface areas through which diffusion occurs are in the ratio ri/r1, where ri is the radial distance between the center of the sample and the center of the i th shell to which the host (alloy) atoms diffuse, and r1 is the radial distance between the center of the sample and the center of the innermost (i = 1) experimentally reported shell from which the alloy atoms diffuse. Hence, ri/r1 (i = 1, ..., n layers) is a dimensionless correction factor to be multiplied by the reported concentration data before planar-data analysis is attempted. In the forty-seven samples reported, the original interface between the copper alloys and the electroplated copper was located at a mean distance of 8.255 mm from the center of the samples. The successive layers, machined off the samples, were approximately 0.0762 mm thick. The distance (xi) at which concentration (ci) was reported was always a distance measured with respect to the original interface, that is, with respect to the fixed distance of 8.255 mm. Hence, the as yet undiscovered Kirkendall Effect was precompensated. The values of ri and r1 are therefore given by ri = 8.255 + xi and Y, = 8.255 + x,. The illustrative table below lists the position xi (mm), ri (mm), the value of ri/r1, the reported concentration (ci) in weight percent (only valid for radial analysis of data), and the corrected concentration [c&apos;i = (ri/r1)ci] in weight percent (only valid for planar analysis of data). Similar tables can be constructed for the remaining forty-six samples. The corrected data can be used to re-evaluate the diffusion coefficients for the reported systems.

Jan 1, 1965

By Nathaniel Arbiter

There is a history in all men&apos;s lives, Figuring the nature of the times deceas&apos;d, The which observ&apos;d, a man may prophesy, With a near aim, of the main chance of things. W. Shakespeare, Henry IV; Part 2 Introduction This nation&apos;s first century embraced two stages of the Industrial Revolution. During one, what had been a colonial agricultural economy began to industrialize; water power, then steam after 1794, were the energy sources; coal and iron were the essential ingredients. The second stage started after 1850; aided by rich and diverse mineral resources, the country began its transition from the Iron Age to the Age of Metals. Early civilizations had been built on stone, and fairly high levels were sustained on iron. But the spectacular advances in the past century in communication, in construction, in transportation by sea, rail, land and air, and in much that characterizes modern civilization have depended increasingly on the use of the complete metallic and nonmetallic resources of the earth&apos;s crust. Thus it was appropriate to define the Industrial Revolution as “the period during which man&apos;s relationship to natural resources became utterly changed”, 1 with minerals playing a major and indispensable role. But we are now becoming aware that the relationship of man to natural resources must change again. On every hand the dangers inherent in the contamination of land, sea and air by the wastes of civilization are becoming apparent. And from the growing realization that mineral wealth is finite must eventually come other far reaching changes in mineral use and distribution. For on the scale of centuries we cannot continue to exploit mineral resources even at present rates, let alone at expanded rates, without eventual depletion of the more abundant resources, and early exhaustion of the less abundant. In the past our problems were relatively easily met by the development of new and improved machinery and processes. But the future will

Jan 1, 1971

By Joseph M. Locke

The discovery of this asphaltum was made by S. H. Gilson, of Salt Lake, and since then the material has borne the local name of Gilsonite. So far as I have been able to ascertain, however, the first published notice of this discovery was made by Prof. W. P. Blake in the Engineering arid Mining Journal, of December 26, 1885, where he names the new mineral Uintahite, from the place of its discovery, the Uintah Mountains in eastern Utah. The priority of publication and the geographical fitness of the name will probably secure its acceptance by mineralogists.* The following is Prof. Blake&apos;s article. In the month of September last, a sample of peculiar asphalt was received for examination, and recently when in Provo, Utah, I had the opportunity of seeing a considerable quantity brought in from the Uintah Mountains. It is obtained in masses several inches in diameter, and apparently free from mechanically disseminated impurities. It breaks with a conchoidal fracture, is very brittle, and is readily reduced to powder in a mortar. Hardness, 2 to 25. Gravity, 1.065 to 1.070. Color, black, brilliant, and lustrous; streak and powder, a rich brown. It is a non-conductor of electricity, and is electrically excited by friction.

Jan 1, 1888

By E. A. Anderson

In 1918 the American Society for Testing Materials held a symposium2 on what was then known as season cracking. The sessions included six papers, all on brass. During the ensuing 26 yr., many new workers have come into the field and several other metals have been found subject to failure by stress-corrosion cracking when the right combination of stress and environment is achieved. It is not surprising, therefore, that the present symposium has brought forth 29 papers covering alloys of seven important metals. The phenomenon of stress-corrosion cracking is not necessarily confined to these seven metals. Dix3 has stated, "Indeed, it is probable that ingenious investigators can find solutions which will stress-corrosion crack any known metal or alloy." Mears, Brown, and Dix4 have indicated that stress- corrosion cracking failures are not necessarily limited to metals but may include the plastics. It is to be expected that the increase in the number of metals known to crack in service and the general emphasis on such failures at a symposium such as this will alarm many to whom the subject is un- familiar. Such alarm is not justified by the record. It is true that stress-corrosion

Jan 1, 1945