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By Harrison Schmitt

SINCE the U. S. Geological Survey published the data on the Central Mining District collected by Lindgren and Graton1 and by Paige2 much new information has been obtained by development and mapping, but none of it had been published until recently when Kniffin3 published on Fierro, Lasky4 on the Ground Hog mine, Thorne5 on Santa Rita and Landon6 filed a thesis on the Fierro-Hanover-Santa Rita area at the Uni-versity of Chicago. During the years 1927-1930 much of the writer's time was spent in mapping the geology and ore deposits of this district, particularly in the area of the zinc deposits at Hanover. Some of the data collected are presented here. Previous publications have been freely drawn upon and additional data used that were generously supplied by L. M. Kniffin, Wilfred Wright and Gerald Ballmer. Thanks are due Augustus Locke, Samuel G. Lasky, Kniffin, Wright and Ballmer for suggestions and critical readings of the manuscript, and to the Empire Zinc Co. (a subsidiary of the New Jersey Zinc Co.) for the privilege of publishing material compiled largely at its expense. The relation of the Central. or the Santa Rita-Hanover-Fierro district to the Silver City district is shown on Paige's geologic map in the Silver City folio.7 Granodiorite porphyry and quartz-monzonite porphyry

Jan 1, 1933

The following is an incomplete list of members and guests who' called at Institute headquarters during the period Mar. 10, 1918 to Apr. 10, 1918. W. Sinclair Brown, Lebong Donok, Sumatra. F. Laroque, Roodepoort, Transvaal. H. B. Catlin, Syracuse, N. Y. A. H. Means, Camp Upton. A. R. Chambers, New Glasgow, Nova Scotia. J. H. Miles, Nome, Alaska. W. M. Corse, Buffalo, N. 1 . Harvey S. Mudd, Washington, D. C. George C. Crossley, Toms River, N. J. Henry Noyes, Melbourne, Aust. F. A. Dalburg, Montoursville, Pa. C. L. Petzel, Camp Upton. Kuno Doerr, El Paso, Tex. J. L. Schueler, Peoria, I11. V. E. Edwards, Worcester, Mass. J. G. Scrugham, Reno, Nev. H. F. E. Gamm, Rutherford, N. J. Frank M. Smith, East Helena, Mont. J. W. Gerhard, St. Louis, Mo. W. G. Swart, Duluth, Minn. Julius H. Gillis, Sudbury, Ont., Canada. A. L. Sweetser, Boston, Mass. S. J. Gormly, Guayacan, Chile. W. N. Thayer, Cincinnati, Ohio. Fletcher Hamilton, San Francisco, Cal. Felix E. Wormser, Cornucopia, Ore. Dorsey A. Lyon, Washington,. D. C. John B. Arnold has opened offices at 606 Lyceum Bldg., Duluth, Minn. E. E. Barker, formerly mine superintendent with the Chile Exploration Company at Chuquicamata, Chile, has resigned his position to become superintendent of mines for the Cerro de Pasco Copper Corporation at Cerro de Pasco, Peru.

Jan 5, 1918

Executive SIDNEY J. JENNINGS, Chairman GEORGE D. BARRON J. E. JOHNSON, JR. EDWIN LUDLOW ROBERT M. RAYMOND Membership KARL EILERS, Chairman LEWIS W. FRANCIS J. E. JOHNSON, JR. LOUIS D. HUNTOON ARTHUR L. WALKER Finance GEORGE D. BARRON, Chairman CHARLES F. RAND BENJAMIN B. THAYER Library E. GYBBON SPILSBURY,1 Chairman ALEX C. HUMPHREYS2 GEORGE C. STONE2 J. H. JANEWAY4 BRADLEY STOUGHTON1

Jan 3, 1918

By A. B. Kinzel

MUCH work has been done recently in an attempt to analyze the physicochemical mechanism involved in the production of steel by the open-hearth process. . This has resulted in reducing the process to a series of interrelated phenomena obeying the usual laws of mass action and diffusion. Of these, the reaction of the iron oxide and carbon in the molten steel is of most interest from a technical point of view as it con-stitutes the main action in the usual steelmaking processes. A. L. Feild1 has formulated a basic differential equation expressing the open-hearth reactions and Hefty has done considerable experimental work on the determination of a number of constants involved in the basic open-hearth reaction. In considering the application of the law of mass action. to the reaction FeO +C ?? CO +Fe, the iron will be taken as constant, as is the case in the open hearth and the carbon monoxide pressure will be assumed' constant at one atmosphere. From this xy = m at equilibrium, where x is the percentage weight of carbon, y percentage weight of iron oxide and m the weight-concentration equilibrium constant. While it is customary for physical chemists to express equilibrium constants in terms of molar concentrations, the constant is here expressed as the product of the percentage-weight concentrations for ease of comparison with the constants quoted by Herty and by Feild, and for more ready applicability to the open-hearth reactions. Herty and his associates have attempted to calculate the value of this constant from data on open-hearth heats. So many variables affect these results that an adequate calculation presents very great difficulties. A value of 4 X 10-2 was first arrived at, but this was later changed to 1.6 X 10-2. Feild, in order to illustrate the operation of the differential equation of the open hearth, has assumed a value considerably lower than Herty's, namely, 1.0 X 10-2, the largest value consistent with certain theoretical

Jan 1, 1929

By W. M. Brown

SEQUACHEE Valley includes portions of the counties of Marion, Sequachee, Bledsoe and Cumberland. It extends in a general direction parallel with the Great Valley of East Tennessee, some 75 miles northward from the Alabama state line. It is separated from the Valley of East Tennessee by a mountain arm about a dozen miles wide, known as Wallen's or Walden's Ridge. The genesis of the valley, geologically speaking, is simple. It is an erosion-valley along the axis of an anticlinal. The point of the wedge remains in a row of low "saw-tooth" hills, running up the center of the valley. These hills are of Lower Silurian age, and consist of Trenton limestone, covered and protected in some measure by chert. Walls of Carboniferous age form the inclosing mountains on either side; whilst a magnificent arch of Hudson River, Niagara, Hamilton and Subcarboniferous strata closes the valley at the

Jan 1, 1886

By William Copp

THE SEAL BEACH oil field is between the Long Beach and Huntington Beach oil fields, south of Los Angeles, and about half the productive area is with-in the city limits of Long Beach. The proved area lies in portions of Sections 2, 3 and 11, T. 5 S., R. 12 W., S. B. B. & M. Seal Beach is 'an additional link in that remarkable chain, of oil fields extending from Newport to Beverly . Hills, filling in one of the few remaining gaps. It differs from other fields along this line of folding in that it is an oil field in an area of tide lands. Ocean-connected sloughs have access to this area, which ac-counts for its extensive mud flats. The surface eleva-tion of the low ground varies from 2 to 5 ft. above sea-level. This condition called for much preliminary work in building roads prior to field development. Roads are constructed with dredges and drag-line scrapers, which excavate mud from alongside the proposed road and pile it up to a grade high enough to be above high tide. The road bed is then surfaced with gravel, or decom-posed granite, which makes it serviceable in all kinds of weather. An immense amount of road material has already been hauled into this field. Well locations are staked in the mud flats, sometimes ahead of road build-ing, and material is dragged to its place on the ground by tractor. It is necessary to drive piling to support derrick foundations. The present practice is to drive 5 piles for each derrick leg, 4 under the rotary table, 2 under the draw-works, 2 under the Samson post and 4 under the pipe rack, a total of 32 piles. This pro-cedure is, of course, varied to suit special conditions, using either more or less piling.

Jan 6, 1927

By George Burrell

J. S. HALDANE, M. D., F. R. S., Oxford, England (communication to the Secretary?).-The valuable paper of Messrs. Burrell and Gauger is of special interest to me as, through the courtesy of the management, I had an opportunity of visiting the Portland mine, Cripple Creek, in 1911, in connection with the investigations on acclimatization to high altitudes, carried out on Pike's Peak, near Cripple Creek, by Professors Yandell, Henderson and Schneider, Dr. Douglas and myself.1 The analyses of one or two samples of the vitiated air were entirely confirmatory of those of the authors. A fatal accident owing to two men being lowered down a shaft filled with the gas had occurred in a neighboring mine just before our visit.

Jan 12, 1916

By F. C. Farnham

THERE has been very little, if any, uniformity in the reference datum used for magnetometer surveys. It has been the practice to choose a base station at which the magnetic field is assumed to be normal and call the difference in field strength between a given station and this base the anomaly at the given station. For small-scale surveys latitude and longitude corrections may or may not be applied, but for large-scale surveys such corrections usually are applied. The United States Coast and Geodetic Survey maps showing lines of equal magnetic intensity are commonly used to determine the normal latitude and longitude variation by scaling values from the map for given points and computing the change per mile north and the change per mile east. This method has been quite satisfactory for isolated surveys, but when two surveys originating at different base stations were extended until they joined, difficulty arose, not only because of discrepancies between base-station values, but also because of differences between the latitude and longitude correction factors used for the separate surveys. It is the purpose of this paper to describe a reference datum for magnetometer surveys which, it is believed, will eliminate most of the difficulty arising from this source. In order to be satisfactory, a general datum for magnetometer sur-veys should be as close as possible to the observed field and still he based on some assumed distribution of magnet poles, in order that the "normal" value of any component of the field for any given point may be computed to as many significant figures as desired. Such a field has been com-puted, and a comparison of the intensity of its vertical component with the average vertical intensity for the United States as shown by the U.S.C.G.S. map of lines of equal intensity for 1935 is shown in Fig. 1.

Jan 1, 1939

By William J. Robinson

What is the cumulative rate of recovery of copper from a sulfide leach dump? The technical answers to this frequently asked question may vary from "I don't know" to "quite good" from people of the same company. Management also poses this question because it plays a vital role in planning future production. The answer is difficult because of the many variables between different operations such as physical construction of the dump, topography of the original site, characteristics of dump material, mineralization, and water application. Each of these factors and others have a bearing on the rate of recovery. Anaconda's method of water distribution at Butte is unique in that each dump is drilled to allow physical injection of water into the dump. The injection holes are drilled vertically on 25-ft centers from the surface of the dump [(Figs. 1 and 2)]. Normally, the holes are drilled 40 ft deep and cased with 4-in. PVC perforated pipe. The pipe is perforated at 1-ft intervals with four 1 -in.-diam holes at 90° spacing on the pipe circumference. Formerly, shallow holes (20-40 ft) were alternated with deep holes (80-180 ft) in an effort to cover the entire dump and hasten oxidation. The shallow hole depth varied according to the compaction thickness. The deep hole depth varied according to the height of the dump and the original ground profile. It is preferable to have the deep holes end 20-30 ft above the original ground level. This generally allows penetration of the coarse material at the bottom of the dump. Deep holes had to be discontinued in order to cover more

Jan 1, 1974

By D. R. George

Preliminary research has identified several organic and aqueous solutions that are effective absorbents for SO, from simulated smelter gas containing 0.3 to 2% SO2. These SO2 loaded solutions are also compatible to the reaction of H2S and SO2 to precipitate a readily filtered elemental sulfur. The economic removal of SO2 and production of elemental sulfur from stack gases discharged by base- metal smelters is a challenging goal. The magnitude of this task is illustrated by the estimate that about 3.5 million tons of SO2 are discharged to the atmosphere by smelters annually in the U.S. The SO2 concentration of the gases ranges from about 0.5 to more than 3%. As the sulfur content of SO2 is 50% a potential production of 1,750,000 tons of sulfur per year is indicated.

Jan 1, 1970

Jan 3, 1953

By F. G. Miller, E. B. Wilson

In 1972, coal mine productivity was in steady decline and labor and maintenance costs were spiralling upward. Yet, despite this sad state of affairs, nowhere in the US at that time was there a comprehensive and coordinated coal research and development plan in the offing. The Bureau of Mines had not yet been charged with such a responsibility, and industry was content to rely on machinery manufacturers for innovations. It was during this period that Bethlehem Steel Corp. determined that a new approach to coal mining research was needed for the industry as well as for the company itself. After studying Bethlehem's own mining practices, the state-of-the-art of mining research elsewhere, and development work by manufacturers, a comprehensive research package was presented to company management in late 1972. The ideas and experience of many operating and management personnel in the company contributed to the formulation of the final plan as approved.

Jan 10, 1976

By Paul M. Tyler

HISTORICAL concepts of the economics of the glass-sand industry are changing rapidly. The greatly expanded demand for glass containers combined with higher freight rates on raw materials and manufactured products have induced a migration of glass factories toward densely populated centers and the creation of new standards of place value for sub- standard sand deposits. This migration has been facilitated by the construction of pipelines to bring cheaper natural gas and liquid fuel to large cities and may be further speeded by the adoption of modern mineral dressing methods to permit economical utilization of local raw materials. Our national resources of naturally high-grade 1 silica sand are abundant, but most of the best de- posits are situated so far from large centers of population that it now costs $3.00 to $5.00 a ton to carry the sand from the mine to the optimum site for a 1 factory making beverage bottles, scientific and electrical glassware, and miscellaneous blown and pressed ware for local markets. It follows that on the basis of freight savings alone it may be economical to use material from inferior deposits closer to the factory even though the f.o.b. cost of mining and treatment may be much high

Jan 1, 1950

By J. E. Hilliard, H. E. Cook

It is shown that for systems having a miscibility gap the spinodal composition (c,) in the vicinity of the critical temperature (Tc) is related to the equilibrium composition (c,) by where cc is the critical composition. This expression is exart for the limit T — Tc and is a good approximation down to (T/Tc) - 0.9. If the miscibility gap meets the composition of the pure components THE recent theoretical treatment by cahn1,2 on spinodal decomposition of solid solutions has revived interest in methods of estimating the chemical spinodal, * i.e., the locus on a binary phase By use of the appropriate expression, the spinodal can be drawn on the Phase diagram almost by inspection with an accuracy comparable to that of lengthy calculations in which a free-energy function is fitted to the phase diagram. Satisfactory agveemenf is also obtained with spinodals comPuted from experimental free-energy curves. where G is the Gibbs free energy of the homogeneous solution and c the atomic fraction of component 2, the derivative being evaluated at constant temperature (T) and pressure (P). (These subscripts will hereafter be omitted from the partial derivatives.) If experimental measurements of G as a function of c and T are available in a single-phase region above the spinodal, then these can be extrapolated to obtain a series of metastable free-energy isotherms in the two-phase region, and from these isotherms a series of spinodal compositions can be calculated. Because the value of is very sensitive to experimental errors, an elaborate analytic procedure is required for

Jan 1, 1965

By J. N. Maycock, P. W. M. Jacobs

Previous measurements of the thermoelectric power of ionic crystals are reviewed briefly. It is concluded that, while extensive measurerements are available on systems in which the electrode M has a cation in cornon with the sall MX, there is as yet little modern work on systems in which the metal electrode M' does not haue a calion in common with the salt. We haue now measured the thermoelectric power of- single cryslals of KC1 and of KC1 + SrCl2 between plati.nu?n electrodes over a much wider range of temperature than before. individual ionic heats of transport, which, while probably not very accurate, are of a reasonable order of magnitude, are obtained from this data on the basis of an assumption that charge carriers do not cross the electrode/salt interface. RELATIVELY little work has been done on thermal diffusion in ionic crystals. Reinhold and coworkers1-I measured the thermoelectric power and Soret effect in silver and cuprous salts and their mixed crystals. One electrode was kept at constant temperature and electromotive force was measured as a function of the temperature gradient. This is not a satisfactory technique if the results are to be compared with theory; rather should the electromotive force be measured for small temperature differences as a function of the mean temperature of the two electrodes. They used electrodes having the same cation as the salt. Patrick and Lawsons measured the thermoelectric power of AgBr and of AgBr containing 0.25 mole pct CdBr2 using silver electrodes and temperature gradients of 10°C in the temperature range 100° to 400°C. The results were analyzed using the Teltow9 values of the ratio of the mobility of the two types of charge carrier (cation vacancies and interstitials) found from conductance measurements and the wagnerlo estimate of the heterogeneous contribution to the thermopower, Ohet They obtained values of qi = 0.017 ev and q$ = -0.385 ev for the heats of transport of interstitial Ag ions and cation vacancies, respectively. Their data has been reanalyzed by Haga using the corrections to the Wagner formula for ehet given by Howard andLidiard; Haga found ev. Christy et a1.14 have measured the thermopower of AgBr containing 0.01 to 1.0 mole pct CdBr,. They analyzed their results in terms of the theory of Howard and Lidiard and found that excellent agreement with the theory was obtained if q5 + : + hF was set equal to 0.70 ev at 175°C and equal to 0.58 ev at 250°C. Since Teltow's value for hF, the enthalpy of formation of a Frenkel defect pair, is 1.27 ev, this means that qt + q: increases in magnitude from -0.57 ev at 175°C to -0.69 ev at 250°C. This result is in poor agreement with Patrick and Lawson's value of -0.37 ev for pure AgBr (for which the corrections to the Wagner estimate for ehet are very small). christy1' has also reported thermopower measurements for pure silver halides and for the systems he finds that qr + qt for AgBr increases in magnitude from about -0.55 ev at 150°C to about -1.1 ev at 400°C. The temperature dependence of the sum of the heats of transport in AgCl is very similar in magnitude. The sum qi + q cannot be decomposed into the individual interstitial and vacancy heats of transport without a knowledge of the entropy contribution from the change in the lattice vibrational frequencies around the interstitial and vacancy. Despite this it seems an inescapable conclusion from Christy's analysis that and -6 = Q Ag are quite strongly temperature-de pendent and that -q: is much greater in magnitude than the corresponding activation energy for vacancy migration, +0.37 ev. It remains a mystery as to why the data for pure AgBr are fitted so well by the assumption of temperature-independent heats of transport if association of impurity ions and vacancies is neglected.l The values for q$ and q: so obtained are also much more in line with those expected from a simple kinetic interpretation of the heats of transport due to wirtz.17 Christy and Hsueh have also measured the thermopower of CuCl between copper electrodes; 0 for pure CuCl is comparable with that for the silver halides but, owing to the limited solubility of divalent cation impurities it was not found possible to deduce values for the heats of transport. In contrast to these extensive measurements on cells of the type M MX 1 M, there have been relatively few attempts to measure the thermoelectric power of cells of the form M' 1 MX I M'. (We specifically exclude from discussion cells of this type in which the metal electrodes M' are in contact with gas containing a controlled partial pressure of either M or X,, since in these cells the electrochemical reactions are analogous to those of the first type.) The thermoelectric power of Pb12, PbC12, TlC1, TlBr, TlI, NaNO3, and KNO 3 between platinum electrodes was measured by Thie1e.l3 In discussing these measurements Holtan20 asserts that the thermopotential initially fluctuated wildly and even changed sign before approaching a steady value. A high degree of irreproducibility is also evident in the work of Nikitinskaya and Murin21 who first studied the thermopower of NaCl and KC1 between platinum electrodes. Much better reproduci-bility was achieved in our earlier measurements on KC1;22 these were, however, confined to a relatively narrow temperature range and one of the objects of the work reported in this paper was to extend the temperature range of the measurements of the thermoelectric power 8 of KC1. The only other published

Jan 1, 1967

By B. VISWANATH

T HE Mysore iron works, at Bhadravati, about 2000 ft. above sea level in the Shimoga district of Mysore, British India, is served by a meter gage branch line of the Mysore State Railways. The works which were designed and erected by Perin & Marshall, who still act as consulting engineers, are surrounded by a thickly wooded country which sup- plies about 400 tons per day of wood for fuel. The ore deposits lie 20 miles to the south, and limestone quarries are close by the works. The Bhadra river sup- plies the works and the town with the necessary quantity of water. Dwelling houses for the employees

Jan 1, 1930

By F. R. Morral, K. T. Aust

The preferred orientation and earing characteristics of ZS aluminum were studied. An empirical correlation was obtained relating earing behavior and variation of mechanical properties for face-centered cubic metals. Strain-ratio mecsurements for ZS were found to be in good agreement with Hill's theory of plastic anisotropy. DIRECTIONALITY in sheet metals may be revealed by earing in a cupping test, or by the variation of mechanical properties of tensile specimens taken at different angles to the rolling direction. However, no simple correlation appears to exist between earing and variation in mechanical properties in metals and alloys studied.1-5 Aluminum of commercial purity (known as 2S, with a specified minimum of 99.0 pct Al) cast by the direct casting process was chosen in the present investigation since ears at 45° or 0°, 90° can readily be obtained. Preferred orientation is often the principal cause of uneven metal flow, such as earing, and variation in mechanical properties. Consequently, the preferred orientation characteristics of 2s aluminum were initially studied using both X-ray diffraction and micrographic techniques. The variation of mechanical properties with angle to the rolling direction was next determined in an effort to clarify the apparent lack of correlation of earing behavior with mechanical properties for face-centered cubic metals. Strain-ratio*5,8 measurements were finally conducted to determine first, if the maximum values of the strain ratio occurred at the earing positions, and second, if Hill's theory of plastic anisotropy7 is applicable to other face-centered cubic metals such as aluminum. Detailed treatments, working, and heat treating are not given in this paper since this study is not concerned with the methods to produce earing, but to correlate earing with other properties and characteristics of the material. The percentage of earing was measured using the formula specified by the x—Y Aluminum Association, -------- X 100 = pct earing, where x is the height of the ear and y is the height of the valley from the bottom of the cup. Preferred Orientation Characteristics of 2S X-ray Studies: Beck and coworkers8 have determined that the rolling texture of 2s after 95 pct cold reduction may be approximately described by four equivalent ideal orientations near (123) [121]. Also, the recrystallization or annealing texture of 2s aluminum consists of four components of the (123) [l21] type, retained from the rolling texture, and of a (100) [001] or cube texture component." Fig. 1 illustrates the typical appearance of deep drawn earing cups with the corresponding X-ray diffraction patterns. The X-ray patterns were taken with copper radiation using the structure-integrating method'" in which the specimen is scanned during the X-ray exposure. The rolling direction was vertical and the rolling plane was perpendicular to the horizontal X-ray beam. It was found that an increase in the retained rolling texture component resulted in a greater 45" ear height, while an increase in the recrystallization texture component (i.e., cube texture) caused greater 0°, 90° earing. X-ray diffraction studies of 2s cold rolled to final thickness followed by a final anneal have shown that the rolling texture, and also the retained component of the rolling texture after annealing, are increased with greater cold-rolling reduction. The preferred orientation characteristics of 2s sheets given an intermediate anneal between cold rolling followed by a final anneal were found to depend on the position of the intermediate anneal during cold rolling. For instance, three identical samples of 2s homogenized ingot, each 1 in. thick, were given the following cold-rolling and annealing treatments: 1—50 pct reduction, intermediate anneal, 96 pct reduction to 0.020 in. and a final anneal; 2—75 pct reduction, intermediate anneal, 92 pct reduction to 0.020 in. and a final anneal; and 3—90 pct reduction, intermediate anneal, 80 pct reduction to 0.020 in. and a final anneal. The intermediate and final annealing treatments consisted of a 70°F per hr heating rate, held 6 hr at 800°F and air cooled. Typical X-ray patterns after each of these treatments are shown in Fig. 2. It was evident that after treatment 1, the retained rolling texture component predominated; after treatment 2, the retained roll-

Jan 1, 1954

By John Dasher

Extrapolation is a useful technique, but it can be overdone. Seldom is it justified to study over a range of 1 to 6 and extrapolate the results to 150,000. It is especially dangerous if the extrapolation is based on a false assumption. The authors assume settlers scale-up by residence time rather than by area, admit their result (a settler depth of 7 m) is "unreasonable" and suggest longer, wider, shallower settlers might be better. Various authors have noted for a copper-LIX system a total flow basis of 2 gpm per sq ft for sizing settlers. The results of this are compared with those in the paper in [Table 7]. The authors note that flooding of their settlers was never approached. Thus the smallest unit calculated is understandably twice too big. The largest however, is 5% of the required size. I note that the figures in [Table 6] for 1/min/cm2 are based on plan area rather than cross section as titled and are wrong by l0 4. A flow of 2050 1/min/cm2 is about Mach I. It is also 10 5/3 or 46.5 times that of the little one, although the abstract says the design was based on constant flow rate per unit cross section.

Jan 1, 1977

By H. C. Fiedler

The development of cube-on-edge secondary re crystallization texture in Si-Fe strip depends upon the ability of inclusions, such as manganese sulfide, to restrain nomal grain gvowth. The ability of inclusions to perform this function is shown to depend upon their size and distribution. The desired uniform dispersion of many small inclusions is obtained by controlling the cooling rate from above the solution tempmature of the inclusions or, alternatively, by drastic 'quenching from above the solution temperature followed by heat treating at a lower temperature. The development of the cube-on-edge secondary recrystallization texture in Si-Fe strip depends upon both establishing the proper primary recrystallization texture and having inclusions to restrain normal grain growth. It has been suggested that the first requirement is met with a texture which, though weak, is near (110)[001]. A mechanism for secondary recrystallization originally proposed by ielsen' is consistent with the presence of this primary texture. It is visualized that a secondary grain appears where two adjacent grains happen to be sufficiently similar in orientation to be capable of behaving as a single large grain. This pair of grains will grow at the expense of its smaller neighbors as a consequence of its having lower grain boundary free energy. Other explanations of the origin of the secondary recrystallization texture have been offered,' and it can be concluded that the mechanism is not fully understood. Nevertheless, it is apparent that operationally the necessary primary recrystallization texture is obtained simply by interposing an anneal during the cold reduction to final gage. The role of inclusions in the development of the secondary recrystallization texture has been demonstrated by May and Turnbull4 in a comparison of a high-purity heat and a heat containing manganese sulfide. They showed that the driving force for secondary recrystallization is inversely proportional to the diameter of the matrix grains and that the function of the inclusions is to maintain a small matrix grain size. Other inclusions, such as various sul- fides,')' silicon nitride,8 and vanadium nitride,' titanium carbide,'' and vanadium carbide," have been shown to be effective in promoting secondary recrystallization to the cube-on-edge texture. There is also evidence that silica inclusions in Si-Fe strip made by powder-metallurgy techniques perform this function.' This report is concerned with the second of the two requirements for secondary recrystallization, namely the importance of the metallurgical control of the size and therefore number of inclusions. While the concepts involved are simple, they are fundamental to the making of this material. EXPERIMENTAL PROCEDURE A heat containing 3.27 pct Si, 0.026 pct S, 0.06 pct Mn, and 0.004 pct C was made in an air induction furnace from electrolytic iron, 98 pct ferro-silicon, electrolytic manganese, and iron sulfide. The heat was divided between graphite and baked-sand molds with a cavity 2-5/8 by 5 in. and with walls 2-3/4 in. thick. Slabs, 1 in. thick and 2-5/8 by 5 in., were cut from the ingots and hot-rolled either in the as-cast condition or after one of the heat treatments described later. After pickling, the 80- to 100-mil-thick hot-rolled band was, unless otherwise noted, heat-treated for 5 min at 900°C before being cold-rolled to 25 mils. After a heat treatment of 1 to 3 min at 860°C, the strip was cold-rolled to 12 mils, the final thickness. The percent cube-on-edge texture was determined by dividing the maximum torque as averaged from four samples by the maximum torque of a 3-1/4 pct Si-Fe single crystal having the (110) plane in the plane of the sample. The torque measurements were made in a field of 1000 oe on 1-in.-diam disks. RESULTS AND DISCUSSION The importance of the thermal history of the ingot is evident in Fig. 1 from the appearance of strips heat-treated in a temperature gradient. The sample

Jan 1, 1964

By Robert M. Weidenhammer

For years before the war, Coal had the reputation of being a sick industry. Currently it is operating at peak production and succeeding pretty well in keeping out of the red. But, says Mr. Weidenhammer, it will have a relapse as soon as the war ends unless (1) working capital can be built up; (2) it gets the support of the people and Congress; and (3) a truly long-range national fuel policy is formulated.

Jan 1, 1943