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By F. W. Maclennan

PAPERS by D. B. Scott, E. G. Deane, and J. H. Hensley, Jr.1 describe the succession of mining methods used in the Miami mine—squarelset system, shrinkage stoping, top-slicing method, and the undercut caving system which was then being used, and which embraced the use of finger raises. The last-named system worked well but when the rich ore was exhausted it became necessary to reduce costs so as to make available a low-grade ore containing an average of less than 0.9 per cent. total copper with less than 0.8 per cent. in sulfide form and with no precious-metal values. There was then developed for this low-grade ore the system of separate large block-caving stopes, in lateral dimensions 150 by 300 ft., or 150 by 150 ft., with intervals between stopes of the same size so that subsequently these pillars may be similarly mined. The results have been most favorable. Under the previous system the production of ore per man-shift for all underground labor was 8 tons. The present production per man-shift underground is 28 tons. In starting this work the problems were: 1. How the ground would cave above the stopes. 2. Whether in the first stopes caving would encroach on the pillars as laid out. 3. Whether in subsequent mining of the pillars waste filling would be drawn from the previously caved adjacent stopes. Fig. 1 is a small key plan for showing the location of cross-sections as well as of ore mined and the limit of the escarpment and limit of cracking on the surface caused by the caving of the capping overlying the ore

Jan 1, 1929

Separates of all the Technical Publications published in 1931 are available at Institute headquarters. All the papers are on file in public, university and technical libraries, and when so indicated in the list, may be found in the Transactions. Copies of these papers have been mailed to those members of the Institute who are registered in the different classes: A-Metal Mining; B-Milling and Concentration; C-Iron and Steel Division; D-Nonferrous Metallurgy; E-Institute of Metals Division; F-Coal Division; G-Petroleum Division; H-Nonmetallic Minerals; I-Mining Geology; K-Mining Administration; L-Geophysical Prospecting. Other members may obtain copies by writing to the Secretary. Additional copies are sold at the rate of I cent per page; minimum charge, 25 cents. Metal Mining Tech-nical Publi- Title Author Meeting TRanb. cation Volume No. and Page* 411-A.43 Ventilation at the Portovelo Mines, J. P. Harmon New York. T31, 83 Ecuador (18) Feb., 1931 425-A.44 Use of Models for the Study of Mining P. B. Bucky New York, Problems (28) Feb., 1931 Milling and Concentration 375-B.32 Ball Mill Studies, I (53) A. W. Fahrenwald New York, H. E. Lee Feb.. 1931 401-B.33 Experimental Flotation of Oxidized H. S. Gieser New York. Silver Ores (9) Feb., 1931 410-B.34 Flotation of Minor Gold in Large-scale E. S. Leaver New York, Copper Concentrators (32) J. A. Woolf Feb., 1931 414-B.35 Effect of Particle Size on Flotation A. M. Gaudin New York, (23) J. 0. Groh Feb., 1931 H. B. Henderson 416-B.36 Ball Mill Studies, 11.—Thermal A. W. Fahrenwald New York. Determinations of Ball Mill Effi- G. W. Hammar Feb., 1931 ciency (13) H. E. Lee W. W. Staley Iron and Steel Division 38QC.59 Open-hearth Steel Process as a Prob- E. R. Jette New York, C31, 80, 111 Iem in Chemical Kinetics (34) Feb., 1931 381-C.60 Thermodynamic Study of the Phasial Yap, Chu-Phay New York. Equi1ibriain the System Iron-car- Feb., 1931 bon (26) 382-(3.61 Influence of Dissolved Carbide on the Yap, Chu-Phay New York, Equilibria of the System Iron-car- Feb., 1931 ban (19) 383-C.62 Research on Blast-furnace Slags. R. S. McCaffery New York, Three papers (88) Co-workers Feb., 1931 384-C.63 Statistical Analysis of Blast-furnace K. S. McCaffery New York, C31, 60, 70 Data (13) R. G. Stephenson Feb., 1931

Jan 1, 1931

By B. N. Whittaker, C. J. Bonsall

The paper gives an account of the factors influencing the stability of coal mining tunnels and goes on to examine various bases of support and lining design of such tunnels in relation to geological and mining conditions. The different types of coal mining tunnels are compared and comments made regarding the factors influencing their choice and basic design features. Foremost amongst design considerations is the design method and special thought has been given to the validity of different formulae as related particularly to UK Carboniferous geological conditions. Emphasis is placed on the role of the stress field in relation to tunnel stability. Shape of mining tunnel has been investigated and conclusions drawn regarding the merits of different commonly excavated geometries from a stability point of view. Detailed design aspects pertaining to determination of tunnel lining strength and resulting stability are critically examined and current design methods are compared. Data from UK mining tunnels are included as the basis for comparison of these design methods.

Jan 1, 1983

By AIME AIME

THE difficult problem of visitors is being met by the Hudson Coal Co. at Scranton in an ingenious fashion. The Company had long made it a point to have dealers selling its coal visit the mines, whenever possible. "The excellent reaction obtained from these dealer visits brought up the question of whether it would not be possible to open one or more mines to the public, and give the consumer an opportunity of seeing for himself how anthracite is mined and prepared. Ac-

Jan 1, 1929

By W. G. Pfann

The problem of forming points on wires that were from 0.002 in. to 0.010 in. in diam arose in the recent appearance of silicon and germanium point contact rectifiers as elements in microwave radar.' In these devices a pointed tungsten wire makes a delicate contact with the surface of a semiconductor. Because the quality of such rectifiers is largely determined by the nature of this contact, considerable attention has been given to the formation of the metal point. Reproducibility of contour and freedom from burrs and even microscopic irregularities are considered essential. The operations involved must be simple and rapid enough for mass production. Previously tungsten wircs had been provided with conical points by a grinding method which involved rotating a wire about its axis and causing it to bear at an oblique angle against a spinning abrasive disc. This was later complemented with an electrolytic polishing treatment which removed irregularities from the ground point and also rounded it off at the tip—a desirable feature. Finally, these operations were supplanted by the electrolytic pointing method described here. Mechanism of Point Formation The wires to be pointed are partially immersed in an electrolyte in a vertical position whereupon they are provided with smooth rounded points entirely by electrochemical action. The process is independent of the depths to which the wires penetrate the electrolyte because the points are formed at the surface level. It may be used to point a single wire or many of them simultaneously and is applicable to wires of different diameters within a limited range. Solution of the immersed portion of a tungsten wire is accomplished by making it the positive electrode in an electrolytic cell, as shown in Fig I. While the wire is maintained at constant voltage the current through the cell falls continuously, principally because of the decrease in wetted area which results from solution of the tungsten. This increase in resistance occurs in a reproducible manner and is used as a control in the process. As thc immersed portion of the wire dissolves, it remains cylindrical in shape except for the short section which is wetted by the meniscus. Here the rate of solution is lower and decreases as the top of the meniscus is approached. The result is the formation of a tapered section inside the meniscus. As solution continues, the cylindrical section either dissolves entirely or drops off just before complete solution, leaving only the taper which is now sharply pointed. Further action causes this point to become rounded and then quite blunt, until finally the end of the wire is almost plane. Fig 2 shows the stages in this development. Contour PF is most representative of those used in point contact rectifiers. Thus a variety of point

Jan 1, 1949

By Glen R. Neighbors, Sylvan Cromer

HIGH subsurface temperatures and pressures are making cementing operations more difficult as deeper producing horizons are being sought. Recorded bottom-hole temperatures above 200°F. and pressures in excess of 12,000 Ib. per sq. in., obtained by combining hydrostatic and pump pressures, are not uncommon. Insufficient time is available for proper placement of standard Portland cement, because of the shortened setting time produced by these excessive temperatures and pressures, therefore special types of cements have been developed to overcome these difficulties. From the standpoint of placement, the ideal slurry would be one that would remain fluid long enough to be placed, then harden rapidly, so that there would be a limited amount of contamination and the well could be placed on production in a minimum of time. It is highly desirable, therefore, that some method be devised to measure accurately the time that any slurry will remain in a fluid state while being pumped into the well. To study the effect of elevated temperature and pressure on fluidity, the authors have developed the pressure-type consistometer (Figs. I and 2) described below, and are presenting data obtained with it, using slurries of both quick-setting and slow-setting cements. Studies were made over a temperature range from 110° to 270°F., and a pressure range from atmospheric to 3000 lb. per sq. inch. APPARATUS The fluidity of cement slurries at atmospheric pressure is usually determined with the Halliburton consistometer1 or the Thickening Time Tester.2 These instruments are similar, in many respects, to an ordinary ice-cream freezer. The slurry to be tested is placed in a container that is rotated at a constant speed with an electric motor. Constant temperature is maintained by surrounding the container with a thermostatically controlled bath. The torque on the paddles, which is proportional to the force needed to shear the slurry, is indicated on a scale. The Halliburton instrument is calibrated from 0 to 100 poises against fluids of known viscosity. To permit direct correlation of observed elevated pressure data with those published at atmospheric pressure, the authors' designs of the slurry container, paddle, and torque indicator closely resemble those used on the Halliburton instrument. Duplicate results may be obtained at atmospheric pressure in either instrument. Instead of the atmospheric constant-temperature bath, one was built from a high-pressure steel bull plug. A Uni-Bolt union equipped with a blanking plug serves as the top, permiting the instrument to be opened or closed in less than one minute. The slurry container is built from Shelby steel tubing. A wrench socket welded to the bottom of the container engages a hexagonal nut on the top of the steel shaft that rotates it. This acts as a universal

Jan 1, 1941

By V. R. Garfias

Principal events in petroleum operations of Mexico during 1934 have been the completion of three producing wells in the Poza Rica area and the plans for the expansion of operations of the Cia. de Petroleos de Mexico, S.A. (Petromex). Production for 1934 is estimated at close to 38,000,000 bbl., an increase of 4,000,000 bbl. over the previous year; an increase due in large part to the successful development in Poza Rica. The output of the South fields (Golden Lane) and Tehuantepec fields also increased somewhat during the year. Production of natural gasoline increased from 382,000 to 431,000 bbl. in 1934. Crude run in local refineries is estimated at 26,000,000bbl., some4,000,000bbl. more than the previous year. Exclusive of bunker fuel exports totaled 24,000,000 bbl., or 3,000,000 more than in 1933. Domestic consumption increased approximately 500,000,bbl. during the year, reaching a total of close to 13,600,000 bbl., exclusive of ships' bunkers. A total of 148 wells were completed as compared to 91 in 1933 and 40 in 1932. In proven areas, 133 completions resulted in 54 producers and 79 failures. The 15 wildcats drilled during 1934 gave no encouraging results. Seven of these were located in the border zone of northeastern Mexico; three tested possible northeast extensions of the Northern fields; two were drilled for possible extensions of the "Golden Lane" and three were completed in the Isthmus of Tehuantepec. Fields Northern Fields (Heavy Oil District).—There were 34 producing wells and 71 failures completed in the Northern fields, as compared to 20 producers and 20 failures in 1933. Practically all new producers were drilled to the shallower San Felipe formation, while wells drilled to the deeper Tamasopo limestone encountered salt water. Production of the field totaled 11,890,000 bbl., a decrease of 7.5 per cent from the previous year. Acid treatment was attempted during the year in seven wells

Jan 1, 1935

By G. R. Gohn, S. M. Arnold

The results of stress-corrosion tests upon several non-ferrous sheet metals are presented in this paper. The metals include tough pitch copper, five binary brasses, two leaded brasses, one copper-silicon alloy, two tin bronzes, and two nickel-silver alloys. The tests indicate that for most of these sheet metals, externally applied bending stresses below the yield point (0.01 per cent offset) do not result in stress-corrosion cracking as determined by the A.S.T.M. Tentative Method of Mercurous Nitrate Test for Copper and Copper Alloys (B 154-41T).~ Only in the cases of low brass, high brass and medium leaded brass, all cold-worked 4 B & S numbers hard, was any corrosion cracking observed below the yield strength, and in all cases such failures occurred at stresses above the proportional limit for these materials. However, when some of the same materials which showed no evidence of stress-corrosion cracking at stresses below the yield strength, are stressed beyond the yield point, stress- corrosion cracking is quite apt to occur. Since experience has shown that some of these materials, particularly the brasses, are susceptible to stress-corrosion cracking under service conditions, these tests would indicate that, besides externally applied stress and corrosion, plastic deformation in addition to that resulting from the original cold working of the material is also required to produce conditions conducive to stress- corrosion cracking.

Jan 1, 1945

William Clinton Brown, Brooklyn, N. Y.: The demand for an apparatus for cooling water for condensers, refrigeratingmachinery and air-compressors, as well as water-jacketed furnaces, has led manufacturers to put such an apparatus on the market, so that it is now possible to purchase a cooling-tower, properly designed and constructed, by simply stating the amount of water to be cooled and the temperatures of the hot and the cold water. The principle is similar to that described by Mr. Henrich, but wood is not used in the best apparatus. There are two great objections to wood: First, it cannot last long under the very trying conditions to which it is subjected; and second, it absorbs the organic matter with which water in constant use becomes impregnated, and the resulting odor is very disagreeable. A few days ago I saw a cooling-tower and condenser, built by the Henry R. Worthington Co., in operation at the Edison electric-lighting station in Brooklyn, N. Y., cooling the water for a 700 horse-power condenser. It consisted of a large stack of iron, about 15 feet in diameter by about 30 feet high. This stack was filled with tiling through which the water falls. A whirligig distributes the water evenly over the top, and a large fan, about 6 feet in diameter, driven by a 10 horse-power electric motor, blows air into the bottom, thus giving a positive circulation. The water, in running down the sides of the tiling, is met by the blast of air, and enough is evaporated to cool the rest. The vacuum-gauge on the condenser showed 26 inches; so the condenser was undoubtedly getting sufficient cool water.

Jan 1, 1896

By Joshua I. Tracey, Mackenzie Gordon

THE bauxite deposits in central Arkansas were formed by weather¬ing, in early Eocene time, of fresh or kaolinized nepheline syenite above the water table in a subtropical climate of fairly continuous moisture. Four types are recognized: (1) residual bauxite deposits on kaolinized nepheline syenite, (2) residual deposits on kaolin and bauxite detritus, (3) alluvial deposits of sorted pebbles and pisolites of early Wilcox age, and (4) rubble deposits of later Wilcox age. All were invaded by kaolin and siderite during subsequent burial by Eocene sediments. PART I-FIELD RELATIONS OF THE DEPOSITS The Arkansas bauxite region for years has produced about 95 pct of the domestic supply of bauxite of the United States and it contains today reserves of more than 40 million tons-nine tenths of the known domestic reserves. During World War II, the Arkansas bauxite deposits were explored jointly by the U. S. Geological Survey and the U. S. Bureau of Mines. Some 6000 holes were drilled by rotary rigs under contract to the Federal Govern¬ment, which resulted in the discovery and delimiting of approximately 20 million tons of ore in place. Detailed study of the many sections cored through the bauxite, of data from a much greater number of drill holes made available by all the operating companies, and of the extensive mine faces exposed in the strip pits, has yielded valuable geologic information about the origin of the deposits. It is now possible to piece together a paleotopographic picture of the deposits and the now-buried land surface on which they formed. The bauxite region in the center of Arkansas (Fig 1) contains two producing districts: one in Pulaski County, just south of Little Rock, and the other in Saline County, about 15 miles to the southwest. The deposits in both districts are associated with hills of nepheline syenite, bosses of a large batho¬lith that was intruded into Paleozoic rocks and later buried beneath coastal plain sediments deposited during Cenozoic time. The folded Paleozoic rocks are exposed in the northwest half of the state and are covered in the southeast half by the nearly flat-lying coastal plain sediments. The older rocks were intruded by nepheline syenite, probably in Late Cretaceous time, and sub¬sequently were eroded so as to expose the top of the batholith. In Paleocene time, marine limestone and laminated black silty clay of the Midway group were deposited in an advancing sea, and covered all but the most elevated parts of the batholith. Erosion of the islands of nepheline

Jan 1, 1952

Edward K. Landis, Philadelphia, Pa.: In studying Mr. Thackray's paper it seemed that a critical comparison of the results from different methods therein reported would he of interest. For this purpose Table I. was constructed by grouping all determinations made by the same method, and the probable errors were calculated. In this table all chemists titrating with permanganate (A1, E, F, G and 0 of Mr. Thackray's paper) are classed under "Emmerton;" those titrating with nitric acid (C, J, S and Y) under " Handy; " those re Probable error of result: a, ±0.0008996; b, ±0.000694; c, ±0.00107; d, ±0.00115; e, ±0.000674; f, ±0.000473; g, ±0.003675; h, ±20.0007959; i,0.000.5098; k, ±0.0008303. Probable error of single determination: a, ±0.001989; b, ±0.001547; c, ±0.00214; d, ±0.0023;e, ±0.00116;f, ±0.000818;g, ±0.0019;h, ±0.00224; i, 40.00143; k, ±0.00234. The formula for calculating the probable error is 0.6745, where N (N— 1)' S is the sum of the squares of the differences from the mean and N is the number of determinations.

Jan 1, 1897

By Zay Jeffries

Tungsten has the highest melting point of all the known metals, namely 3350 C.; it is one of the hardest of the metals; it has the highest equiaxing or recrystallization temperature after strain hardening, of any pure metal known. It is particularly distinguished because, when composed of small equiaxed grains, it is extremely brittle and fragile at room temperature, and when possessing a fibrous structure it may be ductile and pliable at room temperature. The common ductile metals act in exactly the opposite manner in this respect. The present paper will include a brief note regarding the manufacture of wrought and ductile tungsten. The metallography of wrought and ductile tungsten in the various stages of manufacture will be considered more or less in detail. The general relationships between the properties of tungsten and other metals will also be considered. A discussion will be given explaining why fibrous tungsten is ductile at room temperature, even though past experience with other metals would indicate that it should be brittle. Finally, a brief note regarding some new fundamental metallographic propositions relating to all metals will be given. Manufacture of Wrought and Ductile Tungsten Up to about 10 years ago, it had not been possible to work tungsten mechanically. About the year 1908, Dr. William D. Coolidge, of the General Electrie Go., produced ductile tungsten from what was then supposed to be an inherently brittle metal and which, in fact, was inherently brittle in its normal state, that is, when composed of equiaxed grains. Since that time many products, chief among which are the filaments for electric incandescent lamps, have been made from wrought and ductile tungsten. Tungsten is produced chiefly from the minerals wolframite and scheelite.1-8 The ores may be reduced in many ways. For example, the ore may be fused with alkali carbonates and the fusion dissolved in water; sodium tungstate is formed, which is soluble in water. This

Jan 1, 1919

By L. D. Clark, S. S. Saluja

A physical law, governing the rupture of rock by confined explosive charge correspondent to current expressions for determining weight of charge to rupture rock burden, W, was developed in the form Q = cVw3 by two early investigators performing unique experiments with ice. The coefficient C, is found by trial blast. Recent physical tests conducted with rock, synthetic materials and ice to establish the validity of the theory on which it and other related formulae are based indicated: (a) that failure under hydrodynamic impact pressure is by tension rather than shear as was assumed; (b) that the fundamental law of mechanics, enabling the determination of Q = cvw3, modified to the form P = R x Sa x Wb is valid when low velocity explosives are used; (c) that rock breakage under the action of low velocity explosives is entirely due to explosion gas pressure, as was believed; (d) that under the action of high velocity explosive it is due to the joint effects of scabbing and gas pressure; and that further possible modification could make the above equation also applicable to these joint mechanisms. shape could be easily frozen and because large loads would not be required. They found: (a) that the not unfamiliar shearing equation for metals was applicable to ice where P = load in lb; S = periphery of pressure surface, in.; W = burden, in.; K = modulus of rupture by shear in lb per in.2; and (b) that "the form of cavity produced by the application of gradual pressure is similar to that obtained by blasting in rock under similar conditions of free face and pressure surface!" This similarity in crater shapes leads to the conclusion that rock would rupture by shear, as did ice, and its behavior under the force of a blast could be governed by such a relationship as P = S x W x K. Three important interrelated empirical expressions were derived and rock, charging and spacing coefficients C,, C, and e were established and substantiated by trial blasts. In checking the accuracy of the main assumptions, duplication of the ice tests, substituting rock, suggested that K is not constant and that P = K x W x S, though valid for ice, does not necessarily hold for homogeneous limestone.' Conclusions from this later work raised questions making continued investigation desirable because such conclusions do not destroy the practical value of the empirical equations or theory. Further study for the establishment of the relationship between load, burden and periphery of the pressure surface and possible application of these to the mechanism of rock blasting was undertaken by the authors of this paper. MECHANICAL TESTING - EXPERIMENTAL PROCEDURE Certain inconsistencies in the results of the aforementioned tests repeated on three types of limestone suggested these inconsistencies be attributed to rock inhomogeneity. It was also suspected that the loading speed, which could not be held uniform, may have contributed. The earlier work with both rock and ice

Jan 1, 1964

By THEODORE DWIGHT

Members of the Institute have already received a special pamphlet descriptive of the United Engineering Society building, and wilt doubtless be interested in the progress that has been made up to date-February 24th-in erecting this home for the engineering profession. The old buildings on lots Nos. 25 to 33 W. 39th St., New York, were,' removed many months ago, but final contracts for the new, building were not let until the summer of 1905. The size of the building is 115 ft. on 39th Street, and 88 ft. in, depth; the height from, the sidewalk to the top of the parapet is 220 feet. The cubic contents of the building from the. bottom of the basement floor, to the top of the roof, including the pent houses, is 2,290,000 cubic feet. The number of light's, in the building will be between 4,000 and 4,500. The air supply for Auditorium and Lecture. Halls will amount to nearly 10.0,000 cu. ft, per minute, and the exhaust. to 90,000 cu. ft. per minute. In excavating for cellar and foundations, the average depth where good rock was. found was 37 ft.-it varied, however,: from 27 to 65 ft., due to an old water-course having run through the center of the lot; this condition, and the presence of soft rock, which rapidly disintegrated when exposed to air and water, made the foundation-work very difficult. As two of the column-footings of the building have to sustain a weight of 3,000,000 11) each, the most substantial foundations are necessary; 13,000 cu. yd. of earth were excavated for the foundation and basement; and 1,600 cu. yd. of concrete were necessary, to build up the footings. In the completed building there will be about 3,500,000 bricks. Owing to the number of auditoriums, and their location, and the placing of the library on the top floor; where allowance will have to be made for the enormous weight of 300,000 books, the structural steel work has been unusually complicated in this building. For instance, over the auditorium there are two 60-ton plate-girders, made up

Mar 1, 1906

By J. L. Rodda

THE desirability of a uniformly sized abrasive for metallographic polishing has probably been recognized in a general way for a long time. Certainly all metallographers have recognized the damage that can be done to a polished surface by a piece of grit, especially if one of the softer metals, such as zinc or aluminum, is being polished. It is to be doubted, however, whether many metallographers have had any adequate idea of the particle size of the abrasives they were using or of the range of sizes encountered in any given grade of abrasive. At any rate, the descriptions of abrasives for metallographic work found in the literature are generally very meager. It was with the idea of securing an abrasive with a limited range of particle size that a study of this problem was commenced. Commercial abrasives, even when recommended for metallographic work, are made up of particles of varying sizes. One such abrasive contains some particles so fine that they remain in suspension for days and other particles so coarse that they settle at the rate of 3 in. per minute. It is evident that the coarsest particles are over 100 times the diameter of the smallest ones, or over 1,000,000 times the volume. The hopelessness of avoiding scratches under these conditions is evident. Vanderwilt1 has described a laboratory method for grading abrasives in which the elutriator is used. Le Chatelier's method, described by Goerens,2 also makes use of an elutriator. However, the elutriator is too slow for this purpose and requires too delicate a control for the range of sizes desired. The method of stirring up the abrasive in water, allowing it to settle for as given time, then drawing a measured depth off the top of the suspension, has been finally adopted as the simplest proce-dure. The largest particle in a given portion is. then determined by Stokes' law:3

Jan 1, 1931

By Byron W. Cheever

In the Journal of the Iron and Steel Institute for 1881 (vol. ii., page 379), will be found an article upon this subject. The analyses there reported mere of samples taken from an ingot made especially rich in impurities and then cast in a sand-mould in order to give the elements a better chance to redistribute themselves, on account of the steel solidifying more slowly than when cast in an iron mould. Wishing to ascertain how much, if any, segregation takes place when the steel is cast in the ordinary way, I placed the subject in the hands of Mr. W. J. Olcott, a graduate of the Michigan University, who has carefully collected and analyzed samples taken from different parts of ingots and billets. In this undertaking he found himself somewhat embarrassed on account of being distant from steel-works, and therefore unable to supervise the selection of samples. He found, however, a competent and willing aid in the person of E. F. Wood, M.E., chemist of the Pittsburgh Bessemer Steel Company, Limited, who has spared no pains in collecting the desired samples and furnishing drawings and descriptions of the ingots from which the samples were taken. The following are the results obtained: Ingot No. 1. This ingot was about 5 feet long and 13 X 131/4 inches at the point of fracture, which was 2 feet from the bottom. The samples

Jan 1, 1885

By Gernot Kostorz

In a recent paper, Raffo and itcheell1 compared solid solution hardening of various bcc alloy single crystals at room temperature and concluded that the expression for localized elastic interaction between dislocations and solute atoms2 that gives the critical resolved shear stress (CRSS) 7,: to = Z . µE3/2 C1/2 where c = concentration, e = misfit parameter, (µ = shear modulus, Z = numerical constant Fig. 1—The slope dT0/dc1/2 for niobium alloy single crystals deformed at 570°K plotted against the misfit parameter € = In' I + 1616 I. from Ref. 6, •estimated from Ref. 7. Table I. Plateau Hardening and Alloy Parameters for Niobium Alloys dT0/dc1/2, kg/mm2 Solute Ref. 6 Tantalum 3.7 ± 0.3 1.9 0.73 + 0.06 9 0.0 ± 0.5 15 Vanadium 16.1 ±1.4 - 0.69 i 0.01 9 -7.4 ± 0.5 16 Tungsten 12.5 ? 1.5 20.9 0.92 i 0.05 10 -5.0 t 0.4 17 Rhenium - 25.9 1.24 11.12 -8.5 ± 0.4 I5 Molybdenum - 14.6 1.04 13,14 -4.6 s†±?˜µ?fF?? 0.5 17 Hafnium - 13.9 0.37 12 4.8 ± 0.5 17 Table 11. Solid Solution Hardening and Alloy Parameters for Tantalum Alloys i)' dTo/dc1/2 kg/mm2, dTp/dc1/2 kg/mm2, Ref. 22 1006 Solute ˜570°K Ref. 7 See Text Ref. 25 Rhenium 44.3 32.5 0.65 -8.5 Tungsten 32.1 24.3 0.34 -4.6 Molybdenum 29.3 19.1 -0.19 -5.9 Niobium 5.8 5.5 -0.43 0.I

Jan 1, 1970

While the production of this state has not realized the early hopes that this coal would replace eastern coal on the Pacific Coast, it has been steady though small. Nearly all of the tonnages given are from Goodyear's, The Coal Mines of the Western Coast of the U. s., a carefully com- piled and accurate account of the development of the industry along the Pacific. [ ]

Jan 1, 1942

C. R. CORNING, Chairman. ADOLPHE E. BORIE, First- Vice-Chairman. THOMAS T. READ, Secretary, Woolworth Bldg., New York, N. Y. Vice-Chairmen. JOHN H. ALLEN, GEORGE M. COLVOCORESSES, RICHARD M. ATWATER, JR., -ROBERT PEELE, GEORGE D. BARRON, CHARLES P. PERIN, A. CHESTER BEATTY, JOSEPH A. VAN MATER, J. PARKE CHANNING, ARTHUR L. WALKER. D. C. Bard, Howard Eckfeldt, Milton H. McLean, W. de L. Benedict, R. C.Gemmell, ' Philip N. Moore, John C. Branner, F. Louis Grammer, T. H. O'Brien, Palmer Carter, Ernest A. Hersam, James J. Ormsbee, Allan J. Clark, Edwin C. Holden, Edward W. Parker, F. Crabtree, William L. Honnold, John B. Porter, George G. Crawford, Reginald E.. Hore, R. M. Raymond, O. C. Davidson, C. Colcock Jones; Robert B. Richard's, E. V. D'Invilliers, Eugene P. Kennedy, LeRoy Salsich, James S. Douglas, Chester F. Lee, Henry L. Smyth, Walter Douglas, Richard S. McCaffery, F. W. Traphagen, Howard N. Eavenson, James F. McClelland, Elton W. Walker. Meetings of this committee were held at the Institute headquarters on April 18, May, 3 and 15, and June 19.. At the meeting of June 19, the Secretary reported that letters of invitation to apply for membership in the Institute had been sent to all the alumni of the School of Mines of Columbia University and also to all State Mine Inspectors and their deputies. He also reported the securing of lists of the alumni of the Harvard Engineering Schools, and of the Mining Schools at Houghton, Mich. ; Butte, Mont. ; State College, Pa. ; Seattle, Wash. ; Fayetteville, Ark.; Laramie, Wyo.; Montreal, Canada, and Wor-cester and Rensselaer Polytechnic Institutes. Arrangements were made to invite all these to join the Institute. It was suggested that a. member' of the Institute resident in Australia be appointed to this Committee, also one from Japan. Attention of the members of the Committee was drawn to the fact that letters requesting, others to join the Institute will be written in the offices of the Institute if desired. The applications for membership received recently have been as follows March, 30; April, 02; May, 70; June, 54. The next meeting will be held July 17. THOMAS T. READ, Secretary.

Jan 7, 1913

By James T. Gow, Oscar E. Harder, Anton de S. Brasunas

THIS paper deals with the results obtained and the techniques employed in determining: I. Liquidus and solidus temperatures of the HH and HT type heat-resistant alloys. † 2. The relation of true temperatures (thermocouple) to apparent temperatures (optical pyrometer) for the molten HH and HT type alloys. This work was the outgrowth of needing to know something definite about these temperatures in order to study the effect of pouring temperatures, shake-out times, and heat-treatments on the properties of some heat-resistant alloys. The information developed is thought to be of interest to industry for guidance in foundry practices and the industrial heat applications of the alloys. This paper is based upon work that has been done for the Alloy Casting Institute at Battelle Memorial Institute. LIQUIDUS AND SOLIDUS TEMPERATURES OF HH AND HT TYPE ALLOYS Experimental Procedures Temperature-time curves were obtained during the cooling and solidification of several HH and HT type alloys. The metal was melted in an Ajax high-frequency induction furnace and poured into a coresand mold for cooling. The temperature measurements were obtained by means of a platinum, platinumrhodium thermocouple contained within a fused silica sheath, which was extended through the side wall of the dry core-sand mold to a point at about the center of the mold cavity, which was 3 in. in diameter by 5 in. deep. The cold junction of the thermocouple was kept in an ice bottle, and the temperature was recorded automatically on a direct-reading potentiometer recorder. Through a switching arrangement, the temperature recorded was checked occasionally with a portable Leeds and Northrup potentiometer indicator. Less than a 5°F. variation in the two instruments was always found. This is within the limit of accuracy of readings. The thermocouple used was checked for accuracy against a standard couple, both before use on this work and after completion of the work, by the instrument laboratory. Temperature-time Cooling Curves Fig. I is an enlarged reproduction of a part of one of the cooling curves over the temperature range of 2600° to 2200°F. for an alloy of the HT type with 0.45 per cent carbon, 16 per cent chromium, and 36 per cent nickel. This is a typically shaped cooling curve as obtained for the alloys. It will be noted that two temperatures are shown on Fig. r for the liquidus temperature. It is thought likely that the higher temperature, A, at the point at

Jan 1, 1945