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By R. P. Carreker, J. C. Fisher

Cheep tests are normally constant load tests. Such tests approximate some types of service conditions and therefore are justified from the engineering point of view. Coupled with this consideration is the advantage of simplicity inherent in constant load tests, as contrasted with the comparatively complex requirements of a constant stress test. It is not surprising that the vast majority of creep tests reported are of the constant load type. Despite the enormous amount of accumulated creep test data, plastic flow is by no means completely understood. The widespread use of constant load tests is at least partly responsible for this lack of understanding. Any attempt to analyze deformation must involve the more fundamental quantity stress, rather than load. It is possible to predict constant load behavior from known constant stress data, but the reverse is much more difficult. When a metal specimen elongates, as in a creep test, the cross section decreases, maintaining constant volume. Thus For a constant stress test the force on the specimen must be decreased as the cross section decreases, that is, this force must be inversely proportional to the elongation of the specimen. An-drade has described three methods of obtaining the constant stress condition,l-3 each of which is relatively complex. The most recent proposal,³ suggests a major simplification which maintains the simplicity of the constant load test while approximating quite closely the desirable condition of constant stress. Andrade's device is admittedly more accurate but the method described below has definite advantages Consider a specimen in the form of a "V" supported at its ends. If a weight be applied at the vertex of the angle, the stress in each leg of the "V" If this stress causes an elongation ?1 in each leg of the "V," the angle decreases from a. to a smaller angle a1. The quantity sec — thus decreases with specimen elongation while the quantity 1/A increases. By selecting proper initial conditions it should be possible to hold S/So very nearly constant at unity. The proper initial conditions are realized when a0 is made equal to approximately 90°. Fig 1 compares the ratios of S/S0 for a0 = 85, 90, 95, 100°, with a0 = 0, that is, a straight speci- men, for true strains up to e = 0.10. It may prove convenient to measure X, the movement of the vertex, rather than the true elongation 1. Contour lines of X/lo are also plotted in Fig 1. The method for obtaining constant stress described above is especially suited to the testing of small wires, but may easily be extended to rods of any diameter through the use of a suitable grip which serves as the vertex joining two identical rods forming the legs of the "V." References 1. E. N. da C. Andrade: On the Viscous Flow in Metals, and Allied Phenomena. Proc. Roy. Soc., A, 84, 1, (1910-11). 2. E. N. da C. Andrade and B. Chalmers: The Resistivity of Polycrystalline Wires in Relation to Plastic Deformation, and the Mechanism of Plastic Flow. Proc. Roy. Soc., A, 138, 348, (1932). 3. E. N. da C. Andrade: A New Device for Maintaining Constant Stress in a Rod Undergoing Plastic Extension. Proc. Phys. Soc., 60, (3). 304, (March, 1948).

Jan 1, 1950

By H. M. Roche

IN the first section of- this article, published- Feb. 4, the author reviewed the his¬tory of iron ore mining in New Jersey, listed the reserves and possible markets of this ore, and discussed the role of Lake Superior and foreign ores in domestic steel production. This concluding section of the article emphasizes the metal¬lurgical value, future markets and mining coats of Jersey ores. Mr. Roche's thesis is that industry can profit both metallurgically and econom¬ically through a greater use of Jersey ores --that these orebodies are as yet prac¬tically unexploited, and con¬stitute a valuable national re¬serve fully worthy of careful consideration by Mid-West¬ern steel makers.

Jan 1, 1937

By C. H. Mathewson

MY first reflection on the subject assigned to me by the officers of this symposium was that a critical description of these lesser characters in the cast of inanimate actors now before us under the title "The Role of Metals in New Transportation" would be about as well received as the description of a horse race in terms of harness buckles and jock-ey's buttons. The word "new" in the title of this symposium seems to shout strong aluminum and stainless steel, unless we transfer our attention to transpor-tation on another planet where the strength-density ratios may require very different engineering treatment. To load a speaker with the "heavier nonferrous metals" amidst the airy consideration of flying or 20th century gliding along the earth and through water, like Hermes, the messenger of the immortals, and expect an instructive or enlivening flight into the area of current exploitation and popular interest in transportation would, of course, require the performance of a miracle or at least the exhibition of genius to which I can lay no claim. But copper and nickel, headliners in other classifications, are also indis-pensable as components of the important new structural materials of transportation, and together with lead, tin and zinc perform many minor or contributory functions in this field that may indeed be con-sidered well-nigh indispensable. A complete and well planned fabric of classification, explanation and critique of even these secondary functions would take much time, and I cannot hope in the 25 minutes or so alloted for the purpose to offer more than a rambling treatment, in which a thread of continuity will be sought by anchorage to one after another of the following attributes or appurtenances of the moving vehicle: 1. The machinery and accessories. 2. The framework and superstructure, and the line or travelway. 3. Light, heat, power, water, sanitary and housekeeping services. 4. Embellishment, or style.

Jan 1, 1936

By Leroy Gardner

EVERY reader of this paper is well aware of the fact that the prolonged inhalation of large amounts of free silica dust results in fibrosis of the lungs, and that other inorganic dusts, except those of asbestos and the mineral poisons, are thought to be relatively harmless. But probably few have had opportunity to visualize the effects of silica, asbestos and other minerals upon living tissues. The ideal demonstration would be based upon sections of lungs from human beings that had inhaled com-parable concentrations of different dusts for a unit period of time. Such material is generally difficult to obtain and in some instances is of ques-tionable value because the subject has been exposed to more than one kind of dust. A demonstration could be prepared from the lungs of animals. However, so many months or even years are required to com-plete the exposure to each kind of dust that enough material has not been accumulated. For a general survey of the action of different types of dust, I am therefore compelled to use the tissues of animals that have been injected with suspensions of dust particles. The injection method offers certain advantages. The quantity, the particle size and the state of dispersion can be controlled with sufficient accuracy so that the tissue responses to different minerals can be accu-rately compared. The method insures contact between the tissues and the mineral particles; protective mechanisms, which may prevent the inhalation of certain types of foreign body, never come into play. If the pathway of injection be one that minimizes nonspecific injury, the tissue responses may simulate those produced by inhalation but they develop somewhat more rapidly. It should always be remembered that injection methods merely demonstrate the capacity of various kinds of minerals to provoke reaction in the tissues; whether the same substances are inhaled from atmospheric suspension and accumulate in the lungs in dangerous quantities can be demonstrated only by inhalation.

Jan 1, 1938

By Alexander L. Field

IN a previous paper,' the experimental methods used and some of the results obtained in an extensive investigation of steels containing zirconium were described. The present paper considers in greater detail one of the most interesting of these effects, namely, the elimination of " red shortness" and the occurrence in steel of a compound of zirconium and sulfur. A consideration of the actual percentages of zirconium, manganese, and sulfur in numerous steels in the light of behavior during rolling has led to new conclusions of the most practical import regarding the reciprocal relationships of these elements. The microscopic examination of high-sulfur steels containing zirconium has also been productive of interesting results. Before discussing the experimental data in question, it may be stated, briefly, that the rettetion between zirconium and sulfur in molten steel may be represented by the simple equation, Zr + 25 = ZrS², and that the zirconium sulfide thus formed occurs in the finished steel in the form of gray-colored inclusions, closely resembling manganese sulfide and, like the latter, exhibiting plasticity at rolling temperatures. Molten steel containing zirconium retains such a negligibly small amount of oxygen in solution that the foregoing reaction goes to completion. Hot-rolling Properties of High-sulfur Steels with and without Zirconium The chemical composition of twenty-eight steel ingots embracing eleven heats made in a basic-lined electric furnace is shown in Table 1. The practice followed in the manufacture of these high-sulfur steels was described in the previous paper. Table 1 also gives the behavior of the

Jan 1, 1924

By H. G. Doll

An earlier paper on the general subject of the SP log has analyzed the limitations of that log, in particular when dealing with thin permeable beds enclosed in thick highly resistive ones. Under such conditions, the SP log does not give a good definition of the permeable beds. Selective SP logging is a new method which gives an accurate determination of the permeable beds; even in highly resistive formations, except when the salinity of the mud is extremely high. It also permits a close approxi. mation of the static SP to be obtained. The method consists generally in controlling the potential of auxiliary electrodes located in the drill holes in the vicinity of the measuring electrode. In this manner. the flow of SP current along the drill hole is modified to counterbalance the effect of highly resistive strata. Several procedure; and arrangements used to record selective SP curves and static SP curves are explained. Field examples illustrating these methods are given and discussed. INTRODUCTION In an earlier paper,' the shape of the SP curves and the amplitude of the SP peaks were analyzed, considering how the circulation of the SP current is influenced by the subsurface media as a function of their geometrical configuration and their resistivities. It was shown, in particular. that the permeable beds situated between highly resistive formations are sometimes indistinctly indicated by the deflections of the SP log. It is the purpose of this paper to dircuss a new method now being developed, namely selective SP logging, whose principal feature is to enable a more accurate determination of the depths of the permeable beds present in highly resistive formations, such as occur in limestone fields. It will be shown also how an addi-tional curve called the static SP log can be derived from the selective SP log, or recorded directly, to facilitate the interpretation. Another purpose of the static SP log is to provide an approach toward the determination of the value of the static SP, where this value is not readily given by the SP log. This application. although less important at the present time than that mentioned above, nevertheless is of interest, inasmuch as, according to laboratory and field experiments conducted by several investigators, the determination of oil saturation of reservoirs from the data of the electric log implies the knowledge of the resistivity of the connate water,2,3 to which the static SP seems to be related.4,5,6,7 PRINCIPLE OF SELECTIVE SP LOGGING The method of selective SP logging of the formations traversed by a bore hole consists in recording two curves under the following conditions: The measuring device comprises one measuring electrode M and two additional electrodes G-G', connected to each other. located above and below

Jan 1, 1950

By R. W. Raymond

This name is applied to the present mining law, as enacted in 1872 and since, to indicate its leading characteristic—in which it differs from all previous mining laws of this or any other country. The earlier act, passed in 1866, was practically the first attempt of Congress to deal with the question of mining titles upon the public domain. It was framed after nearly twenty years of acquiescence on the part of the Government in the self-constituted tribunals, officials, rules, and customs of the mining districts. In its recognition of these, and in several other particulars, the act of 1866 was open to serious criticisms. It is the purpose of this paper, not to trace the history of legislation on this subject, or show in detail what were the faults of the earlier law, but rather, by a discussion of certain aspects of the present law, to point out how great a revoluition it has effected in the rights of mining locators, and to indicate some of the difficulties attending its application. In the attempt to correct the vagueness of the act of 1866 an entirely new elernent was introduced into the law, bringing with it a new set of difficulties. Under the act of 1866 and the miners' customs which it followed, the lode was the thing claimed and subsequently acquired by patent. And the claim to a given number of feet on the longitudinal course of the lode was rooted in 'a discovery of any part of the lode in any part of the claim. ("Extensions" could in many districts—perhaps universally—be located and claimed on the strength of the discovery in the principal claim to which they referred; but this is a point not essential to the present discussion.) It was not necessary to find the outcrop or the upper edge of a lode in order to lay a valid location upon it. An explorer, sinking a shaft and intersecting a lode not already discovered and claimed by another, could claim by that discovery the number of feet along that lode which the local laws might permit (not exceeding the maximum set by the United States statute) whether his sur-

Jan 1, 1884

By R. E. Allen, A. C. Jephson

ELECTROLYTIC zinc plants of the American Smelting and Refining Co. are located adjacent to the present city limits of Corpus Christi, Texas. The original plant commenced operations during 1942, and is designed for the production of special high grade zinc from zinc sulfide concentrates.' Subsequent changes include the erection of an additional acid plant during 1950, and additions for increased generating and production capacity during 1951. New Electrolytic Plant—The new electrolytic plant is a separate unit erected for the treatment of densified fume produced at Asarco plants located in El Paso, Texas and Chihuahua, Mexico. Construction was completed and operation commenced during June, 1953. Decision for the erection of a separate plant for the treatment of densified fume is based on several factors. One of the principal reasons is the assurance of continued production rate of the original plant, which might have been jeopardized by combined treatment of calcine and fume. Of equal importance is the advantage of locating a plant on a site with adequate space for eventual expansion. General Description—The new plant for the treatment of densified fume consists of four main buildings for the following operations: storage and grinding of fume, leaching and purification, electrolyzing and casting, and rectifier units. Auxiliary buildings include a baghouse, reagent storage, and a lunch room. Leaching of ground fume with electrolyte from the cells is a batch type operation in tanks equipped with mechanical agitators and weightometers. Completed leaches are pressure filtered, the resultant residue being recovered for shipment to El Paso by conventional use of thickeners, drum type vacuum filters, and a direct-fired dryer. Filtrates from the filter section are purified in mechanically agitated tanks, filtered after completion through plate and frame presses, and then pumped to an evaporative type cooling tower. Solution discharged from the basin of the cooling tower is collected in storage tanks for use in the cells. The cool purified solutions are pumped as required from storage to the solution circuit for circulation of electrolyte through the cells. Except for the addition of purified feed solution and withdrawal of electrolyte for leaching, the circulating system for the cells is essentially a closed continuous circuit that includes the use of evaporative cooling towers for control of solution temperatures. Aluminum cathodes and Ag-Pb anodes are used for electrolysis, which is maintained at a current density of about 82 amp per sq ft. Cathode zinc produced is melted in a gas-fired reverberatory furnace and then cast into slabs on a straight line casting machine. Unloading and Storage—Fume produced by the Chihuahua plant is shipped in box cars, and fume by the El Paso plant in hopper bottom dump cars. Shipments as received are weighed on a 7 5-ton capacity railroad scale, sampled, and then moved over one of the two unloading hoppers with a car puller. The cars are then unloaded with mechanized equipment, a car scoop being used for unloading of box cars and a car shaker for the hopper bottom cars

Jan 1, 1958

By R. L. Rickett, S. H. Kalin, J. T. Mackenzie

Aluminum killed low carbon steel, § which is now used extensively for severe deep drawing or other difficult forming operations, is unusual in that its grain structure, after cold reduction and box annealing in accordance with conventional continuous sheet or strip mill practice, often is elongated, although at times it is equiaxed. Since this unusual structure has been found superior for many, but not all, severe forming operations, recrystallization of the steel, both at constant temperature and on continuous heating, was investigated and compared with that of rimmed steel in the hope that something might be learned about the mechanism of, and the factors controlling, the formation of such elongated grains. In this structure, the grains are elongated both in the lengthwise direction of the strip and transverse to this direction, even though nearly all of the extension in both hot and cold rolling is in the lengthwise direction. The grains are thus roughly pancake-shaped, being longer and wider than they are thick, as observed also by Burns and McCabe,1 and as illustrated by the typical structures shown in Fig 1. Fig la, representing a conventional longitudinal section, shows the length and thickness of the grains, whereas Fig Ib shows their length and width as seen by examining a section parallel to the sheet surface. Both illustrate the very irregular grain boundaries usually associated with the elongated grain shape. A finer equiaxed grain structure in this same grade is shown in Fig Ic. Either the elongated or the equiaxed structure may be present in the annealed product, and in rare instances the two types may coexist in a single specimen, as shown in Fig 1 d. Isothermal Recrystalliza-tion of Rimmed and Alamimum Killed Steel An aluminum killed steel known to have an elongated grain structure after conventional processing (Steel B, Table l), was selected for the initial recrystallization studies; for comparison, a rimmed steel, A in Table 1, was used. Samples of each in the form of hot rolled strip 0.075 and 0.095 in. thick, respectively, were cold rolled on a small laboratory mill in steps of about 0.010 in. per pass to obtain total reductions of 40 and 60 pct. Small pieces of the cold reduced strip were heated in lead at selected constant temperatures for one of several periods of time, then cooled in air. Rate of heating in the lead was, of course, very fast. Hardness of the cooled specimen was measured and a longitudinal section examined metallographically. Isothermal recrystallization curves for these two steels at 1050°F, based on hardness of the air cooled specimens, are shown in Fig 2 in which the amount of recrystallization corresponding to each plotted point is indicated. The marked difference in the behavior of these two types of steel is evident. After a corresponding amount of cold reduction, the rimmed steel recrys-tallizes in a much shorter time than the killed steel and the shape of its recrystallization curve, (plotted on a logarithmic time scale), is very different. The curve for rimmed steel indicates that recrystallization is analogous to isothermal transformation of aus-i.enite in that it proceeds at a progressively faster rate up to some 50 pct recrystallization, then at an increasingly slower rate. For the aluminum killed steel, however, the start of

Jan 1, 1950

By Perry G. Harrison

The increased use of sintering for the beneficiation of iron ores and the reclaiming of flue dust creates a lively interest in sintering costs and economics. The character of material sintered and geographical location of plants so radically alter sintering costs and economics that it is well.to understand at least the basic elements which control such changes. The following cost factors are believed to be roughly approximated for large-scale Dwight-Lloyd continuously operated sinter-machine installations located anywhere. Per Crude Ton Labor, supplies and repairs 0.15 Power 6.5¢ X kw-hr. rate ? Plant overhead and administration 0.05 Depreciation per ton annual capacity 0.05 Fuel: 6 per cent coke breeze or equivalent minimum ? 1 per cent coke breeze additional for each 5 per cent free and combined water in ore or dust ? Ignition distillate at 0.6 gal. per ton ? Per Sinter Ton Royalty on ore 0.10 Royalty on flue dust 0.15 Per Crude Ton "Winter expense"; i. e., the cost of the five months enforced idle . period for plants tied in to Great Lakes transportation season 0.03 Using the foregoing data, it is possible to roughly approximate the cost of efficient sintering at any location for any ore, viz: Per Crude Ton Per Ton Handled Sinter 1. Flue Dust—Steel Plant Locations Sinter recovery, 15 per cent moisture and carbon 85 per cent Labor, supplies and repairs 0.15 0.18 Power 6.5¢ X 1¢ kw-hr. 0.065 0.08 Plant overhead and administration 0.05 0.06 Depreciation per ton 0.05 0.06 Dust handling and preparation 0.10 0.12 Fuel: free, contained in dust Ignition: blast-furnace gas free Royalty 0.15 Total $0.65 Note:—Cost increased by either deficiency or considerable excess of carbon in dust.

Jan 1, 1932

By W. M. Weidel

While electric lamps both of the cap and hand type are being introduced into many mines requiring the use of safety lamps, the oil-burning safety lamp is still used in the great majority of cases, and even where the former are used the latter must continue to be employed when testing for gas. It is not the intention to discuss here the relative merits of the two types, but simply to give a comparison of the illuminating effect or candlepower of several kinds of ordinary safety lamps used for general work and for testing. Few data have been published in recent years on this subject and because of this it is hoped that the following information may be of some interest and value. The lamps tested were in all cases of standard size and in good condition, all practically new, and were selected from a collection of about 100 with a view to obtaining results on as many different common types as possible. With the exception of the gasoline-burning lamps, five different oils were used in each lamp to determine whether particular oils were suited to particular lamps and whether there was any great difference in the illuminating power of the different oils, or whether some oils would maintain their illuminating power better than others throughout a working period of 8 hr. No attempt was made to determine the amount or cost of oil burned by each lamp, but the condition of the lamp, wick, glass, and gauzes was noted after each test. Description of Apparatus Used The candlepowcr was determined with a Weber photometer, Fig. 1, which consists of a tube A containing a movable milk-glass screen adjustable by the milled screw B. The distance of this screen from the standard light at C is read on the scale attached to A. The standard light consists of a benzine lamp so arranged that the height of the flame may be adjusted exactly by observing it against a scale in the lamp box through an opening in the front. The lamp to be tested is placed at D so as to illuminate a milk-glass screen in the holdcr at E. At the intersection of the axes of tube A and sight-tube F are placed two 45' prisms with their surfaces in contact so that the light from D may pass through with-

Jan 1, 1917

By J. Spreadborough, D. LaW. King, E. Anderson

Tmzsile tests were performed on Armco iron samples, at various ternpe.ralures and strain rates, ocer a wide range of grain sizes. Analysis of the data suggests that the plot of the lower yield stress, against d-1/2,where 2d is the acerage grain diameter, is not linear (as is often assumed) but is concave toward the d. axis over the range of d-from 7 to 53 . The different values of the parameters obtained by other workers can be explained, in part at least, by the observed curvature. This curvalure is shown to be consistent with a model of yielding based on dislocation pile-ups; however, the values of obtained by fitting our data to this model differ appreciably from the values generally reported. The equation proposed by Cottrell, viz.: is a plausible empirical fit to the experimental results. The purpose of this paper is to comment on the validity of the widely used linear relationship first proposed by all' and Petch and coworkers2"4 between ay, the lower yield stress, and 2d, the average grain diameter, for bcc metals, viz.: Many workers, see Refs. 2 to 7 and Table 11, have fitted this equation to their experimental results and have obtained acceptable fits over the relatively narrow range of grain sizes used by most of them. Indeed, in some cases, so few data points were available that any more sophisticated fit would have been irrational. In most of the interpretations,'-' oi is thought to be a measure of the friction stress accompanying dislocation movement, and ky was originally inter- preted as a measure of the dislocation locking but is now believed by Cottrell" to be a function of the dislocation creation rate. In the "unpinning" theories, k, is equated to where od is the unpinning stress and 1 is the average distance from the boundary of the grain where yielding is taking place to the nearest dislocation source in an unyielded grain. Other considerations (see, for example, Refs. 11 and 12) lead to equations with a similar form to [I] where different meanings may be attributed to the parameters. While there are doubts as to the physical significance of the parameters i and k, they continue to be used by many workers; interpretations of the variations in the behavior of ferrite materials following certain treatments, e.g., aging,'3 neutron irradiation,14 have been given frequently in terms of these parameters. Some theories of the mechanical behavior of bcc metals are based on this relationship. We have investigated experimentally the oy - d-'lZ relationship for Armco iron over a wider range of grain sizes and with more data points than those given in published results. The analysis of our data suggests that the oy—d-'" relationship is not linear but is in fact concave towards the d-'I2 axis. RESULTS AND DISCUSSION The experimental work was carried out on 3-mm-diam Armco iron rods which were prepared by wire drawing from 5-mm-diam rods. By annealing in vacuum at temperatures between 7000 and 1200°C for various times, grain sizes from 7 to 20,000 grains per sq mm were obtained, the grains in all cases being regularly shaped. Grain sizes were measured by lineal interceptand by area methods; only specimens with Amax/A values of 3 to 6 were used in the Petch-Hall plots (where A is the average area of a grain and Amax is the area of the largest grain observed). For all the specimens used, the number of grains in a cross section exceeded 50, which should be adequate to avoid grain size effects.'= Tensile tests were performed at 296", 219, and 17l°K, using

Jan 1, 1969

By Francis Donaldson

The direct injection of cement grout into water-bearing fissures as a means of checking or stopping the flow of water into shafts and tunnels has been experimented with for a decade or longer and seems to have been first attempted in Europe. The earliest application of which the writer has found a record was at a shaft sunk by the Mining Society of Lens; this is described by C. Dinoire in the Transactions of the Institution of Mining Engineers.1 It is only lately, however, that the process has been entirely successful. This success has been accomplished on the Catskill Aqueduct, now under construction by the city of New York. This aqueduct includes a number of deep pressure tunnels, reached by shafts for both waterway and construction purposes. In portions of these shafts and tunnels considerable underground water was met. The contract for the first of these deep pressure tunnels was let to the T. A. Gillespie Co.; this section is known as the Rondout Siphon. It leads under the Rondout valley at a depth of from 400 to 800 ft. and is about 5 miles long. The engineers expected that considerable water would be encountered, but fortunately this was not the case except at one shaft, known as No. 4, which penetrated the rock at a junction between limestone and conglomerate. Water-bearing fissures were encountered almost immediately. At a depth of about 200 ft. a flow of 1,500 gal. per minute was struck. The. shaft then contained as many pumps as could be used, and it seemed impossible to sink it further. After vain efforts had been made to proceed, John P. Hogan, a division engineer of the Board of Water Supply, suggested that cementation of the fissures be tried. The process was attempted for the first time in this country. Since the shaft was partly full of water it was necessary to drill grout holes with a diamond drill. Platforms were placed on the timbers at the water level, the diamond drill was installed and six 90-ft. holes were drilled in the bottom of the shaft. Several car loads of cement were pumped through these holes into the fissures, the drill casings being used for grout pipes. This largely cut off the flow of water from, the bottom and sinking could then

Jan 1, 1915

Joseph K. Stone, Jr. (Kaiser Engineers, Oakland, Calif.)—I would like to compliment the authors on their clear presentation of the results of their study of the pneumatic processes. We hope that the Inland Management decision to make this information available to all will induce others to release additional valuable fundamental data which they have accumulated in the field. There are two points upon which we would like to comment. In the discussion of Table VII it was indicated that the "oxygen consumptions were about the same as has been reported for other oxygen steelmaking processes". This conclusion is apparently based upon the consumption of 2100 cu ft per ton shown in Table VII. The data in Table IV also permits calculation of 2520, 2280, 2250 and 2700 cu ft per ton in heats 1 to 4, respectively. These figures are in the same general range as those reported for the Kal-Do and Rotor Processes using Thomas iron, but considerably above the following figures for four of the operating L-D Process Plants while using iron which is similar to American basic iron: Donawitz 1760 cu ft per ton Adapted from Cuscoleca' LinZ 1900 cu ft per ton Trenkler & Hauttmann2 Dofasco 1850 cu ft per ton D. O. Davis:3 In addition to the differences between the consumption of gaseous oxygen in the Inland operation and in the L-D Process, there is another closely related difference. The L-D plants for which data are cited are using approximately 1 pct ore while the authors' process used about 7 pct of sinter. Assuming 65 pct Fe in the sinter, the difference amounts to 400 to 500 cu ft

Jan 1, 1959

The regular meeting of the Trustees of United Engineering Society was called to order at 4 P. M. Thursday, Feb. 27, 1919, in the Board Room of the American Society of Civil Engineers, Engineering Societies' Building, New York. Minutes of a joint meeting of the Finance Committee of United Engineering Society with finance committees of Founder Societies on Feb. 14, were presented. The President called attention to actions relating to the recataloging of the Library and the support of Engineering Societies Employment Bureau of Engineering Council. The activity of the Employment Bureau was approved and support by the Societies informally assured. In response to a communication from the Fifth Avenue Association, the Secretary was instructed to write favoring the continuance of the daylight saving law. As to recataloging of Engineering Societies Library, it was announced that the Mining, Mechanical, and Electrical Engineers had voted appropriations, as requested, and the action of the Civil Engineers was awaited. A list of applications for offices in Engineering Societies' Building, revised to Feb. 27, was read, showing requests for a total of 29 rooms. The President stated that a decision must be reached soon as to what reply shall he made to these applications. Charles F. Scott, one of the original trustees, who was present, remarked upon the growth of United Engineering Society and his satisfaction at its success. ALFRED D. FLINN, Secretary.

Jan 4, 1919

By G. D. Oxx, L. F. Coffin

The concept of using a phase that is liquid at service temperatures as a component of coatings for refractory metals has been described. The liquid, an alloy of gold and silicon, is retained on a molybdemum surface by a capillary system made of molybdenum disilicide. The coating has the advantage of good thermal shock and has a self-henling chracteristic. In order for highly stressed structures to exceed a service temperature of 2000°F, it has become apparent that a development that does not depend on the traditional iron, cobalt, or nickel-base alloy is needed. Alloys of the refractory metals, i.e., molybdenum, tungsten, tantalum. niobium (colum-bium), and rhenium are potentially useful at extremely high temperatures that more conventional alloys would never be expected to achieve. A new alloy of molybdenum has become available that has a 100-hr rupture strength of 35,000 psi at 2200°F.1 As a result of this work, it may be assumed that a material with adequate mechanical properties at 2200?F is now available. Unfortunately, this alloy and all other known alloys of the refractory metals suffer from not being; serviceable in an oxidizing atmosphere for a very long time. In order to permit general use of refractory metals at high temperatures, it is necessary to prevent destructive oxidation by appropriate alloying or by protective coatings. The liquid phase coating reported here is representative of a concept for the protection of metals that permits higher service temperatures and introduces a new group of materials for selection as coatings. Coating Requirements—Service conditions that represent potential applications for refractory metals vary considerably: however, it is possible to consider two conditions that are usually present. The refractory metal1 component must be heated to the service temperature at least once and usually frequently. When a solid coating is used, usually the coating and basis metal do not have the same coefficient of expansion. This difference causes thermal stress in the coating that is aggravated by rapid heating and cooling and eventually causes coating failure. The second consideration is the probability that there will be damage to the coating by some environmental condition. In jet engines, for example, it is expected that large particles, stones, metal parts, and so forth, will strike a bucket at high speed and cut a hole in the coating. In addition to the above considerations, the coating must also have other fundamental properties. Obviously, it must be oxidation resistant. In addi- tion, it must prevent permeation of oxygen and subsequent oxidation of the basis metal at the interface. Also, diffusion of the basis metal to the outside surface and subsequent oxidation there must be prevented. Finally, the coating must not react with the basis metal to form a weak bond at the interface. It should be noted that the coating need not support a load: it must only remain intact. Liquid Phase Coating Design Factors—In the use of a liquid as a principal coating constituent, it would be expected that the two service conditions mentioned above would be satisfied. A liquid would flow under the influence of the thermal strain developed by coating-basis metal expansion mismatch such that failure from this source would not be expected to occur. It is also probable that the ability of a liquid to flow would provide a self-healing effect. Thus, damage caused by particles in the atmosphere would be repaired. A third advantage is evident in that vapor pressure rather than melting point limits the service temperature. This latter advantage permits use of low melting but oxidation resistant metals such as gold or copper that would be quite useless if the solid state was required. A low viscosity liquid alone. however, is a totally unsuitable coating because it will simply flow off a component, particularly under the influence of a high acceleration field. A method of preventing liquid loss must be devised. In this case, it is desired that the liquid have a low viscosity so that it may easily flow into flaws; thus, raising the viscosity is not a satisfactory solution. One other inherent difficulty is caused by the high mobility of atoms in the liquid state as compared to the solid state. Because of this mobility, it would be expected that gases would diffuse more rapidly through a liquid. It is also probable that the solubility of oxygen in the liquid would be comparatively high. These factors would tend toward rapid permeation of oxygen and oxidation of the substrate. It is most reasonable that this problem could be solved by incorporating a solid phase, which is impermeable to gases, as a component of the coating. To overcome the tendency of a liquid to flow easily, it is possible to use surface tension to advantage. If the surface were made up of a large number of capillary tubes of sufficiently small diameter, then surface tension would hold the liquid even against the acceleration of a centrifugal field.

Jan 1, 1961

A MINING institute open to all men interested in any branch of the mining industry will be held at the Col-lege of Mines, University of Washington, Seattle, during the week beginning March 5. Prospectors, miners, mine owners, persons interested in metallurgy, investors in min-ing enterprises, and the public generally are invited to at-tend. This institute will take the place of the Winter Min-ing Session which originated at Seattle in 1897 and con-tinued for twenty-eight years. The complete new equip-ment of the Mines Laboratory will be used to give demon-strations of new machines and processes of mining, ore dressing, and metallurgy. This year the ceramic industry, including cement and branches of clay working of special Importance in the Northwest, will be included in the insti-tute. All instruction will be given by specialists. Prominent technical men and managers will give lectures on their special subjects. Among the speakers engaged are G. T. Jackson, formerly superintendent of the Alaska-Gas-tineau and the Chichagof mines, who will speak on the mining of large bodies of low-grade ore; R. F. McElvenny, superintendent of the Tacoma Smelter, on the nature of contracts that a smelter can offer to mines and prospects; M. D. Leehey, mining lawyer, on some popular errors re-garding the mining law; H. H. Townsend, on the explora-tion and purchase of prospects by operating companies; J. L. McAllen, on quartz mining in the Willow Creek dis-trict, Alaska; F. Powell, on gold dredging. In the evenings, lectures illustrated by stereopticon views and moving pic-tures will be given. The week will close with an excursion o mines and plants.

Jan 3, 1928

By Philip J. Shenon

IN 1947 the mining industry strove desperately to regain operating normalcy. During the first part of the year the industry in this country was plagued with labor shortages, strikes, and portal-to-portal lawsuits. Then followed the uncertainty of Government policy with respect to subsidies and tariffs; and the long and bitter controversy as to whether we are a nation of mineral "haves" or "have-nots." As the year progressed the labor supply impoved somewhat and the Taft-Hartley law brought partial relief to strike-troubled industry. The uncertainty with respect to tariffs was partly answered by President Truman on April 29 when he announced the suspension of the 4¢ import duty on copper until March 31, 1949, and later, near the close of the year, by the announcement of the tariff agreement signed by the United Nations at Geneva. By this agreement tariff rates are to be adjusted downward, or "bound" at their present levels, for three years, on commodities amounting to some 60 per cent of United States trade. Effective Jan. 1, 1948 the rate of duty will be substantially reduced on ores, concentrates, or metals of zinc, aluminum, copper, manganese, tungsten, iron, steel, barytes, nickel, cadmium, and antimony.

Jan 1, 1948

Discussion of the paper of F. C. NEWTON, presented at the New York meeting, Feb-ruary, 1915, and printed in Bulletin No. 9S, February, 1915, pp. 473 to 477. H. 0. HOFMAN, Boston, Mass.-The results of these large-scale experiments, which were carried on at Perth Amboy, show that there are many differences between theoretical conceptions and their applications to work on a large scale. The author has given reasons why the results of bringing a desilverizing kettle to the high melting point of the zinc-silver alloy, Zn3Ag2, melting at 665° C., are not satisfactory. In all probability the alloy is dissolved in the lead; it may also be decomposed by the lead; the practical result is that this high temperature does not work. It remains now for the laboratory man to carry on systematic experiments

Jan 5, 1915

ON FEBRUARY 13, 1953 the Miami Copper Company signed a contract with the United States Government, through the Defense Materials Procurement Agency, whereby it under- took, with a base price of 27.359 per lb (subject to escalation based on wage scales and wholesale-price indices), to exploit a new ore body in its mine in Gila County, Arizona. Recoverable ore was estimated at 23,000,000 tons, averaging about 0.677 per cent copper. Moreover, the proportion of oxidized copper, difficult to recover by flotation concentrating, was so high that an average net recovery of only ten pounds per ton (0.5 per cent) was expected. The company proposed to mine the ore by the underground method known as undercut block-caving. Unfortunately the ore body, as has been true of all Miami's ore bodies, lay so deeply buried that no possibility existed of adopting opencut mining as has been done in recent years at Miami's neighbors, Ray and Inspiration. Probably the most distinctive characteristic of Miami's operations has been the extent to which it has developed and improved methods and equipment for underground mining. True, necessity was a potent stimulant, because its available ores since 1926 have been exceptionally low-grade; so, if the enterprise were to survive, it was necessary to keep costs at the minimum. This fact does not detract, however, in any way from the remarkable achievements of Miami engineers in conducting efficient and low-cost underground mining.

Jan 1, 1957