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By G. F. Comstock

A serious disagreement as to the effect of titanium on the hardenability of steel exists in published references to this subject. Kramer, Hafner and Toleman reported' that acid-soluble titanium decreased creased the hardenability, with multiplying factors less than unity according to [ ] Grossmann's system for calculating hardenability from the composition. Crafts and Lamont, on the other hand, showed2 how titanium increased the hardenability, with multiplying factors up to nearly 1.7 for about o.' per cent titanium, though reducing the hardenability with higher titanium. Their data, however, were obtained almost exclusively from steels containing more than 2.4 per cent manganese, and thus should be considered as applying mainly to manganese steels. Likewise, the results of Kramer, Hafner and, Toleman regarding titanium are subject to the limitation that although they eliminated the effect of the insoluble titanium compounds from their calculations, they did not make a similar correction for the carbon that was combined with titanium and therefore occurred in a similarly ineffective form. It is suggested by the literature referred to that titanium may have different effects on hardenability, depending on the mode of its occurrence in the steel. The different effects on strength, ductility, etc., have already been discussed by the author.3 In the present discussion some comparisons, on the basis of hardenability as revealed by the Jominy end-quench test, are given between three titanium and two non titanium steels heat-treated in the same ways, and between other titanium steels heat-treated in several different ways. COMPARISON OF PLAIN-CARBON, VANADIUM AND TITANIUM STEELS The five steels used for these experiments were commercially melted and rolled products received in the form of 1.5-in. rounds from three different mills. Their analyses are given in Table I. Steels 2, 3, and 4 are from the same basic electric heat, containing 0.009 per cent of phosphorus and the same amount of sulphur. They were made by, adding aluminum and low-carbon ferrotitanium to different ingots. No. I is a plain-carbon coarse-grained S.A.E. 1040 steel made by the basic open-hearth -process. No. 5

Jan 1, 1945

By Hans Von Höfer

Apart from the hypothesis of a cosmic origin (which failed of acceptance because it was not adequately supported by facts), the only important controversy concerning the origin of petroleum has been, for a long time, between the advocates of inorganic and of organic origin respectively. Each of these theories has had a long history of development, and is still being perfected, under the influence of two causes: (1) the increasingly extensive and thorough study of the oil-fields (of which new examples are periodically discovered and opened); and (2) the progress of synthetic experiments devoted to this question. Moreover, the advance in our physical and chemical knowledge of the properties of this peculiar natural product has necessarily modified all criticism of conflicting views. I. The Hypothesis of Inorganic Origin That the nation of an inorganic origin of petroleum, first set forth by Berthelot in 1866, and afterward ingeniously developed and formulated by Mendelejeff, should thus have proceeded chiefly from chemists, is quite natural; for the question was one of possible chemical processes in the earth's interior, and of imagined chemical reactions to be verified by ex-periment. Hypotheses of this kind were suggested by many chemists, of whom two, P. Sabatier and J. H. Senderens, may be specially named by reason of their highly interesting chemical experiments. Among geologists, Mendelejeff's hypothesis was received at first with much interest and favor; for it rested on the assumption of a central terrestrial mass of iron carbide, and the geologists had good reasons for adopting that assumption. Yet comparatively few of them attempted to furnish geological proofs of the hypothesis: the majority either silently believed in it, or for one or another reason rejected it altogether. An apparently weighty support of Mendelejeff's view was furnished by the American, G. F. Becker, who found in the oil-regions of the United States important and abnormal disturbances of the isogons of terrestrial magnetism, and inferred that in these regions the central iron mass must

Jan 1, 1915

By Gerald Edmunds, R. K. Waring, E. A. Anderson

Brass is liable to failure under the combined influence of stress, certain corrosion media, and time, a phenomenon commonly termed season cracking or stress-corrosion cracking. The consequences of this are serious in applications of brass generally, including the important field of cartridge cases. Cartridge cases (70 Cu: 30 Zn) that fail from this cause may allow the escape of gas from the gun breech, a hazard to the shooter, and may not eject, thus temporarily putting the gun out of action. In loaded cartridge cases, the stress present is partly residual from the, drawing and necking operations and partly applied by the insertion of the projectile. Ammonia, present as a decomposition product of smokeless powder, air and moisture constitute corrosive media. The prevalence of season cracking has been reduced considerably, but not eliminated, during the past quarter of a century by low-temperature annealing to relieve stresses residual from fabrication, a method suggested by Diegel 38 yr. ago(I).2

Jan 1, 1945

By Harrison Souder

In view of the proposed visit of the Institute to Cuba this winter, the following brief sketch of the principal mineral deposits near Santiago de Cuba has been prepared largely from notes taken in February, 1903, during a visit to the mines then in operation in the province of Santiago de Cuba. Westward from Cape Maysi, the most eastern point of the island, the coast is rocky and uninviting. The usual course of the steamers is well in toward the shore, and the lines of stratification of the rocks can be distinguished clearly, the presence of iron or other ores being indicated by frequent blotches of mineral stain. One is impressed with the general rugged character of the southeastern coast-line,—an almost unbroken barrier of coral-limestone bluff's, full of caves and hollows, into which the surf rushes with a roar and bursts into tall fountains of spray. Beyond rises abruptly the Sierra Maestra range, whose sharp, peaked crest-line betrays its eruptive or igneous origin. From a height of about 800 ft. near Cape Maysi, this range gradually rises to the westward, attaining its maximum elevation of more than 8,300 ft. in the Pico Turquino, beyond Santiago. A general resemblance to the mountain-ranges of southern New Mexico is noticeable. At Daiquiri, 20 miles east of Santiago harbor, the extensive

Jan 1, 1905

By V. G. Mooradian, John T. Norton

The diffusion of metal atoms into the crystal lattice of another metal and the assumption of regular positions to form a homogeneous alloy are some of the most fundamental phenomena of structural metallurgy. The mechanism of this process has been the subject of a great deal of study from many viewpoints, but the picture is still far from complete. It is generally believed that if one metal is to diffuse into another, the first must have some solubility in the second1. This means that the solvent must be able to accommodate the stranger atoms, either on points of its own lattice or in the interstices between, without losing its own crystal-lographic identity. It is also a general observation that cold-working is a distinct aid in the diffusion process, causing it to take place with greater rapidity at the same temperature or with the same speed at a lower temperature. There is considerable doubt, however, as to the real significance of the deformation in its effect on the diffusion mechanism. Several factors associated with the cold-working may be responsible for the increased diffusion rate. The plastic deformation causes a distortion of the solvent lattice, which may be an aid in the assimulation of atoms of another kind. There are many references2 in the literature that suggest that some distortion or "loosening" of the lattice is necessary for atomic migration and that diffusion cannot take place in the undis-torted lattice. On the other hand, it may be that the cold-working causes an increase in surface of contact between the two metals through fragmentation or provides a more intimate contact that is necessary for diffusion. If it is true that lattice distortion is an important factor in diffusion, it seems as if there should be some particular relation between

Jan 1, 1935

By Raymond Mancha

The number of installations of propeller mine fans completed during the years of 1936 and 1937 is evidence of the increasing popularity of the propeller fan with the American mining industry. During the period from 1931 to 1936, there were several different low-pressure, low-efficiency propeller fans available, which filled a definite need in replacing inefficient centrifugal fans operated at comparatively low pressure by means of purchased power. Since 1936, however, the trend toward the propeller fan has greatly increased, as propeller fans are now available practically without pressure limitations and capable of efficiencies high enough to warrant replacement of efficient centrifugal fans in many instances. Few manufacturers of propeller mine fans base their fan-operating characteristics upon similar test methods, primarily because of inadequate facilities for testing in the factory and the need of a test code incorporating a calibrated duct or nozzle that makes possible the testing of large propeller fans quickly, accurately and without prohibitive expense and space requirements. As a result, fan manufacturers have resorted to various methods for testing large propeller fans in the factory, and different yardsticks have produced uncomparable and often inaccurate performance data. It is the purpose of this paper to describe and discuss in detail the test procedure of the Jeffrey Manufacturing Co., which has been proved both accurate and practical. Fig. 1 shows a plan, a side elevation and two end elevations of the test duct with a propeller fan of the exhaust type in place. Testing propeller fans exhausting permits greater accuracy than testing these fans blowing, because in the former uniform flow conditions are more easily established at Pitot tube stations where fan pressure and air-volume measurements are desired. Any residual rotation remaining in the air discharged from a propeller fan blowing into a test duct must be removed before an attempt is made to obtain accurate pressure and volume readings. Although various devices for straightening the air may be placed between the blowing fan and the volume-measuring station without resulting complications, uniform flow so obtained at the pressure-measuring station necessitates corrective calculations to compensate for duct resistance

Jan 1, 1940

By Arthur F. Daily

8.5-1. Bucket Line Dredge. INTRODUCTION. The modern bucket-line dredge for mining placer deposits is a combined floating excavating machine and a gravity concentration system. Material is excavated at the forward end by the buckets, elevated, washed and screened, concentrated for recovery of valuable mineral, and discharged off the stern as coarse and small fractions. The end product is a concentrate consisting either of the valuable mineral(s) and associated heavy minerals, which are taken to a treatment plant on shore; or in the case of gold, a clean amalgam ready for retorting. The bucket-line dredge may be adapted for purposes other than mining for valuable mineral by installing, in lieu of a concentrating system, machinery for pumping all of the solids ashore in a pulp, or for producing washed gravel in selected size fractions of which all or a selected fraction is pumped to disposal areas on shore or into side barges. The two principal types of bucket-line dredges designed for mining are: 1) those having an inclined belt conveyor stacker to discharge the coarse fraction of washed tailing well astern of the hull, and sluices to discharge the sand fraction (Fig. 8.5-1), and 2) those having only sluices for discharge of all tailing astern. Use of the latter type has been confined, with few exceptions, to mining cassiterite-bearing deposits in Malaysia and at sea off Indonesia. Small dredges having only flumes for washing and concentrating all material dug by the buckets have been used for mining shallow stream valley deposits. GENERAL ARRANGEMENT. The general arrangement of a modern bucket-line dredge for mining tin, with a primary concentrating plant on board, is shown in Fig. 8.5-2. The hull and superstructure of most dredges are fabricated of structural steel; wood also has been used for both small and large dredges with complete satisfaction. All-riveted or partially welded unit hulls have been widely used and are desirable for exceptionally severe service. The hull

Jan 1, 1968

By R. C. Hepworth

Heaving in roads built on the Mancos Shale is a serious problem in east-central Utah. Heaves are expressed as local bumps, general rises and severe cracking of the pavement. The heaves usually occur in shale road cuts and generally show a seasonal cycle, which reaches a maximum development in the winter. The presence of certain salts, absorption of moisture and physical properties of the subgrade materials were considered, in Utah, to be the main factors in the heaving mechanism. Work done on similar problems elsewhere and studies conducted by the author indicate that the latter two factors are the most important. Results of this investigation indicate that heaving areas are associated with slaking shale or expansive clays, with and without salts present. Laboratory studies show that the initial moisture content of remolded samples and the desiccation history of un- disturbed samples have a major effect on swelling. Swell tests on compacted samples at various temperatures indicate that water has more influence on swell than temperature, except for samples containing sodium sulphate, which swelled with decreasing temperature. Chloride salts inhibited swelling. Tests on shale cores indicate that the stability of slaking shale can be preserved by maintaining its original moisture content. It is concluded that shales and expansive clays, when exposed in road cuts, become desiccated and are subject to expansion when moisture is subsequently available. The seasonal cycle of heaving may possibly be explained by the annual moisture excess and deficiency. To minimize the problem, freshly exposed shale should be kept wet, and the thickness of the subbase and base courses should be increased. The Utah State Department of Highways has been plagued for many years with a distressed condition that develops in roads constructed on the Mancos Shale. Locally these distressed areas are known as heaves, frost boils and alkali boils. These names refer to the surface expression, time of year

Jan 1, 1965

By H. M. Chance

(Butte Meeting, August, 1913.) ADEQUATE treatment of the difficulties surrounding the valuation of mineral lands requires that agreement be first reached defining value as understood for the purpose of appraisal. To define value as the price of a product is not sufficient, and does not assist us in using the factors that cause variations in values and in relative values. The real value of any product depends primarily upon its relation to the necessities, comforts and pleasures of mankind. As the necessities, comforts and pleasures of the civilized races differ from those of more primitive man, the value of products varies with the degree of civilization and the environment of the consumer. Coal has no value to the savages of warm climates, and arrow-head flint none to the residents of New York. It has long been recognized that what has been termed ? intrinsic value " must be limited to materials that are essential to existence-air, water, food. But "intrinsic value" cannot be measured in monetary terms. The intrinsic value of a bushel of wheat is due to the fact that it will support the life of an individual for a certain definite time, but this fact does not enable us to measure or to express that value in monetary terms. It has often been proposed to adopt as a measure of the value of any product the quantity of labor necessary to produce it, but this method is of limited application, and will not apply to what may be termed "intrinsic values." For many reasons it might be well, while assenting to the fact that any material may he intrinsically valuable, to abandon the use of the term " intrinsic value." One of these reasons is the tendency to confuse the idea of intrinsic value with a value that is conferred by economic conditions, that is purely artificial and that may be permanent or evanescent; Intrinsic value must from its nature be permanent and unchangeable.

Jan 7, 1913

By W. B. Boggs, J. N. Anderson

Originally, the copper produced at the Noranda smelter was shipped in the form of blister bars to the Laurel Hill refinery of the Nichols Copper CO, New York. In 1930 a refinery was built at Montreal East to refine Noranda copper and copper from the Hudson Bay Mining & Smelting Co., at Flin Flon, Manitoba. After investigation of the probable costs of making anodes at Noranda and at Montreal, it was decided to make them at Noranda rather than to continue to make blister bars there. Fuel is a major item of expense in making anodes, and since less fuel would be required in making them from molten copper than from blister bars, a lower anode-furnace cost could be expected at Noranda than at Montreal. Further, the expense connected -with making blister bars at Noranda would be eliminated. The cost of treating anode and wire-bar furnace slags is a serious item in a refinery, and it was found that the cheapest method would be to ship such slags back to Noranda. With the anode furnace at Noranda, much less anode-furnace slag would be made at the refinery. Against these savings effected by making anodes at Noranda must be set the high operating cost of an anode furnace at Montreal, using only tank-room scrap and the Flin Flon copper. This furnace would be handling a comparatively small tonnage and would have a high cost per ton. The usual equipment for making anodes from liquid copper consists of either a stationary reverberatory furnace or a tilting Tacoma-type furnace together with an anode wheel of the Clark or Walker type. The reverberatory type of furnace has been developed from the furnace used in the old Welsh process of smelting and refining copper, while the tilting furnace is a development of the holding furnace, which is essentially a Peirce-Smith converter without tuyeres and provided with burners. Refining as carried out in either of these furnaces is a batch process; that is, several converter charges are accumulated and then refined and cast. Colonel H. H. Stout recently developed in Arizona a so-called

Jan 1, 1934

By Graham Bright

Metal mines were developed long before coal mines and the early lighting of underground workings was effected by torches and candles. The early coal mines were outcrop workings and little trouble was experienced from gas, but as the mines became deeper and shaft mines were opened it became apparent that an open-fame lamp was exceedingly dangerous where gas occurred. No satisfactory way of lighting gaseous coal mines was found until Sir Humphrey Davy brought out his famous safety lamp in 1815. The introduction of the Davy lamp was a great step forward but it was unsatisfactory from a light standpoint because the gauze absorbed a large percentage of the light given out by the flame. Clanny corrected this by the introduction of a cylindrical glass lens, which not only permitted a free distribution of the light from the flame but added greatly to the safety by eliminating the possibility of the flame coming in contact with the gauze and by protecting the flame against air currents. A very complete story of the flame safety lamp since its inception is given in the U. S. Bureau of Mines Bulletin No. 227, by J. W. Paul, I;. C. Ilsley and E. J. Gleim, published in 1924. A little more recent publication, known as Safety in Mines Research Board Paper No. 4, entitled "The Light Power of Flame Safety Lamps," by R. V. Wheeler and D. W. Woodhead, was published in England in 1927. The flame safety lamp was the only lamp available for gaseous mines for about 100 years. Although the incandescent electric lamp has been in use over 50 years, it was not found safe to use this lamp from wired circuits in gaseous locations. The storage battery was advocated shortly after the development of the incandescent lamp but until the introduction of the tungsten filament in the miniature mine-lamp bulb, the battery lamp was not a real possibility because of the excessive weight of the battery necessary to produce a sufficient amount of light. The actual development of the electric-battery type of lamp took place largely between 1910 and 1915. In England and Europe, the developmenb was almost entirely along the

Jan 1, 1936

By A. B. Kinzel

THE demands of the petroleum and chemical industries for steels to be used in pressure vessels and similar structures at artificially low tempera-tures are continually increasing, and the writing of proper specifications with suitable tests becomes increasingly important. Likewise, the selec-tion of suitable steels for such applications is of increasing concern to the metallurgist. It is generally recognized that highly alloyed steels of the austenitic stainless type retain their properties even at very low tempera-tures and represent the best technological solution of the low-temperature steel problem. However, in many instances less expensive carbon or low-alloy steels suitable for service within limited temperature ranges are available. The problem thus becomes one of defining the various factors involved in the production and fabrication of these less expensive steels and determining the temperature ranges in which their properties justify engineering application. Most of the applications involve welded structures, and the heat effect of welding as well as the nature of the weld metal are matters of prime concern. The first problem that the metallurgist faces is the determination of the type of test to be used as a criterion of the performance of the steel in low-temperature service. It has been generally recognized that the static properties of steel as determined in the ordinary tensile test undergo a gradual and relatively slight change as the temperature of test is lowered in the range of current interest; i.e., from room temperature to minus 120° C. It is further generally recognized that the behavior of steel under impact involving notch sensitivity is definitely affected at the lower temperatures. While the major subject of this paper is the effect of grain-refining deoxidizers, of low-alloy additions and of welding on the low-temperature notched-bar impact properties, an inquiry into the general behavior of steel under low-temperature impact testing is included. This is a pertinent portion of the investigation and the results thereof are

Jan 1, 1937

By E. M. Norris

DURING the winter and spring of 1917, an unprecedented number of underground fires occurred in the Butte district. With one exception, these fires were caused by the failure of electrical equipment, and called attention to the increased fire hazard in underground mining operations occasioned by the extensive use of electricity. Five local conditions that contributed toward a heavy fire risk were (1) The heavy continuous timbering necessary for mine supports; (2) the strong ventilating pressures in the shafts and main airways; (3) the subsidence and faulting movements in the country rock, which ruptured cables and displaced trolley and lighting wires; (4) the strongly acid mine waters, which quickly developed any weak points in the electrical insulation;(5) oxidation in old stopes containing large amounts of timber. In the summer of 1917, a comprehensive plan of fire prevention was begun by the Anaconda Copper Mining Co., which involved a thorough and intensive development of the preventive measures then in use. These were as follows: Fireproofing, remodeling and strengthening electrical insulations, extension of underground water system, control of ventilation, maintaining efficiency of fire-fighting crews, and reorganization of fire patrol.

Jan 2, 1922

By Bruce F. Grant, Stefan F. Szasz

During 1947, a Sinclair research team was assigned to investigate thermal methods of oil recovery. The assignment was recommended by a survey of possible research approaches to increase the amount of oil that ultimately can be recovered from oil producing reservoirs. The use of heat to stimulate oil production rates by the melting of paraffin deposited in well bores can be traced back to within one or two decades of the drilling of the Drake well. The application of heat on a larger scale has been discussed by generations of oil producers. Shortly after the turn of the century, one intrepid operator is reported to have injected steam into a Pennsylvania property. After a few weeks, he apparently became discouraged and terminated his experiment. Subsequently, the literature contains references to several well-developed techniques for supplying heat to a producing well bore to melt paraffin or to reduce the viscosity of oil contained in the formation immediately around the well bore.1.?.3.4 Some early references discuss procedures to furnish heat to the reservoir,5,6 with the injection well as the heat source, thus obligating the process to maintain the entire rock mass at a temperature above that at which the desired improvement in oil recovery would occur. Another approach to reservoir heating was reported by a group of Russian technologists in 1935.7,8,9 They definitely demonstrated that combustion can occur within the porous structure of an oil-bearing sandstone. Their field experiments, however, relied less on combustion within the rock than on heat furnished by combustion of oil supplied to the injection well bore. Ignition of the air-oil mixtures in the well bore was found very difficult, and the field tests were carried on for only short periods of time. Publication of the Russian work spurred at least one independent operator in this country to try firing an air-gas injection well, on for only short periods of time. Publication of the Russian work spurred at least one independent operator in this country to try firing an air-gas injection well. The Brundred Oil Corp. reportedly obtained combustion in the sand immediately around the injection well bore, but the experiment was abandoned because of interference with normal production schedules. Injection capacity of the experimental well was greatly reduced by firing. The well was reshot and pieces of sand showing partial fusing of the quartz matrix were recovered. To the authors' knowledge no other field experiments utilizing combustion techniques for formation heating were undertaken prior to 1948, although the patent literature evidences continued interest in formation heating."'," CONCEPT OF COMBUSTION-SUPPORTED HEAT WAVE The references cited were in agreement that heat applied to a reservoir would increase recovery, but there

Jan 1, 1955

By P. H. Strickland, F. Lawson

It is now well established that in the majority of cementation processes used industrially, the rate of reaction can be described in terms of the mass transport from the bulk of the solution to the deposition sites on the metallic surface. Thus it should be possible to design cementation equipment from a knowledge of the flow situation in the equipment, and of absolute kinetic data. One way of obtaining such absolute data is by the use of the rotating disc geometry; this geometry is particularly suitable for a detailed study of cementation reactions. In spite of the similar mass transfer mechanism, cementation processes differ from other ionic transport processes in at least two respects. The presence of an attached deposit generally has a significant enhancing effect on the reaction rate; and side reactions involving oxygen and/or hydrogen ions can completely change the course of a reaction. Investigation of these peculiarities is necessary for a complete understanding of the process; since they cannot be isolated from the basic mass transport mechanism, close control of experimental conditions is essential. It has been found that the enhancement in deposition rate persists even when the deposit reaches a thickness several times that of the transport boundary layer thickness on the smooth surface. An explanation of the enhancement in reaction rate is proposed.

Jan 1, 1973

By Alfred H. Bell, Charles W. Carter

In 1942, Illinois produced 106,590,000 bbl. of crude oil, or 7.6 per cent of the entire amount produced in the United States. It ranked fifth among the oil- producing states. The production for 1942 declined 20.5 per cent from the previous year's total of 134,139,000 bbl. Tie daily average production for 1942 was approximately 292,000 bbl., or 74,000 bbl; less than the 366,000 daily average for 1941. At the beginning of 1942 the daily production was 367,000 bbl. This production declined steadily to 282,000 for June and to 246,000 for December. This steady decline was caused partly by the reduction in drilling resulting from Federal Conservation Order M-68 and partly by the fact that no major pool was found during the year. Discoveries Forty new fields (Fig. 2, Table 2), 48 extensions (Table 3), and 45 additional producing zones in existing fields (Table 4) Were discovered in 23 counties in Illinois during 1942. Of the 40 new fields, three

Jan 1, 1943

By Henry S. Washington

I. INTRODUCTION. DURING the last twenty years or so the chemical investigation of rocks has made great advances, and it is now generally recognized that a knowledge of the chemical composition is as essential as that of the texture or mineral composition-if not more so-for the proper classification of rocks and study of their origin and relationships. Rock-analyses have vastly increased in number and, what is of greater importance, in quality. New and improved methods permit of greater accuracy than was possible in the early days, and the list of chemical constituents frequently determined has risen from the seven or eight of the greater part of the nineteenth century, to twenty or more. Indeed, rock-analyses with determinations of so many constituents ire now commonly made by the chemists of the United States and Australia, while in Germany, Great Britain, France, and Italy the rarer constituents are determined more frequently-than formerly. As a consequence of this modern, accurate work, it has been discovered that some elements which were formerly supposed to be rare are of wide-spread occurrence and are often present in considerable amount. The fact is further being developed that the elements tend to show certain relations of occurrence or abundance in connection with each other. This is a fact which is applicable to the rarer elements, and which also finds a broad geological and petrological expression in the recognition of petrographic provinces. We are beginning to obtain some definite, though as yet rudimentary, knowledge of the distribution of the elements among igneous rocks. Some of the results along these lines obtained by study of the vast accumulation of analytical data now available are well known to petrologists, while others do not seem to be so gener-

Jan 1, 1913

By R. S. Archer

In the microscopic examination of aircraft-engine parts made of heat-treated alloy steels, the writer has been forcibly impressed by the failure of the usual etching processes to disclose any but gross defects in heat treatment. It seemed particularly desirable to bring out the grain size of the steel, which is indicated in the ordinary etching processes chiefly by the change in orientation of structure from grain to grain. After various attempts, a fairly successful method has been found, which is here presented in the hope that it may be of use to those who have occasion to examine these steels in the hcat-treated condition. The specimens worked with have been mostly chrome-nickel steels heat treated (that is, hardened and tempered) to a Brinell hardness of around 300. A few experiments with other specimens will be referred to later. Briefly, the method employed consists in etching the steel about 10 min. in a fresh solution of picric acid in ethyl alcohol, and then rubbing off the smudge of carbonaceous matter on moist broadcloth. Different samples of almost identical analysis, heat treatment, and physical properties (including resistance to impact) respond quite differently to this treatment. In some, the grain boundaries are developed quite readily, while in others, especially in those whose grain is unusually fine or in which the final hardening heat has not quite obliterated the previous crystallization, the results are more obscure. The exact time of etching to secure the best results also differs for various samples, and the greatest success is usually attained by a process of "tinkering." Such a process is illustrated in a series of micrographs, the first six of which were taken at a magnification of 300 diameters. The properties of the steel are as follows: Carbon, per cent............... 0.42 Brinell hardness.............. 293 Nickel, per cent................ 1.35 Yield point, pounds per square Chromium, per cent............. 0.90 inch........................ 131,000 Copper, per cent................ 0.025 Maximum strength, pounds per Manganese, per cent............ 0.74 square inch................. 144,500 Phosphorus, per cent............ 0.024 Elongation in 1 in., per cent... 28 Sulfur, per cent................ 0.036 Lod impact, foot-pounds...... 51 Reduction of area, per cent...... 57.3

Jan 1, 1920

By R. E. Maringer, B. A. Wilcox, A. H. Clauer, J. H. Sovik

Internal friction measurements from 25° to 1100°C have been made on specimens machined from TD nickel bar. The use of miniature torsional pendulum specimens alloived damping measurements to be made on specimens whose axes were parallel to the original bar axis, at 45 deg to the bar axis, and at 90 deg to the bar axis. There was a marked difference in damping with varying specimen orientation, and this was related to the pronounced micro structural anisotropy of this material. Varying the microstructure by cold working plus re crystallization annealing also greatly affected the damping behavior. Recrystallization essentially removed the broad peak found at 400° to 650°C in as-received TD nickel, and in addition greatly lowered the background damping. DlSPERSION hardened metals such as SAP-type alloys (Al + AI2O3) and TD nickel (Ni + 2 pet ThO2) have been developed primarily to improve high temperature strength properties. There have been numerous damping studies on SAP-type alloys,1"9 and one of these6 showed that the damping capacity was greater than that of 99.5 pet pure Al from 25° to 600°C. Several preliminary observations on TD nickel10 and an experimental Ni-ThO2 alloy11 indicated that here, too, the damping capacity was quite high. A high damping capacity in TD nickel, combined with its relatively good high temperature creep strength, could provide an additional benefit for some high temperature structural applications. This work was undertaken to study the internal friction behavior of TD nickel bar over the temperature range 25° to 1100°C. In Ni-ThO2 and Ni-Cr-ThOz alloys, other properties such as steady-state creep rate,12 creep rupture life,12'13 modulus of elasticity,14 and ultimate tensile strength,14 are sensitive to orientation with respect to the primary working direction. Thus, in order to examine anisotropy effects in damping, studies were made on specimens machined with their axes parallel, at 45 deg, and transverse to the original bar axis. MATERIAL DESCRIPTION AND EXPERIMENTAL PROCEDURES The material used in this investigation was from the same £ in. diam TD nickel bar that has been studied previously.13'15 The structure typical of the as-received TD nickel is shown in Fig. 1, and additional details of the structure can be found in Refs. 13 and 15. Elongated grains are parallel to the bar axis and are about 10 to 15 u long and about 1 u in diam. This structure is very stable, since no recrys-tallization or grain growth occurred after annealing for 3 hr at 1300°C.13 The total ThO2 content was 2.3 vol pct and the particles ranged in diameter from 100 to 1000. The average particle diameter was 370Å and the mean planar center-to-center particle spacing was 2340Å. To examine the influence of grain and subgrain structure on damping, a section of TD nickel bar was swaged and drawn at room temperature from 1/2 in. diam bar to 0.040 in. diam wire (99.3 pct re-duction in area). The structure in Fig. 2 resulted after the wire was annealed for 3 hr at 1250°C. The recrystallized grains were much larger than the grains in as-received bar, but still showed considerable elongation in the direction of working. A high

Jan 1, 1970

By Carl A. Allen

Page Introduction................... 367 FactoRs Affecting the Choice of Method......... 367 Review of Stoping Methods.............. 368 Underhand Stoping................ 368 Overhand Stoping................ 370 Longitudinal or Flat-Back Stoping........... 371 Rill-Cut Stoping................. 372 Saw-Tooth Back Stoping.............. 372 Shrinkage Stoping................ 372 Combination Stoping................373 Side Stoping.................. 374* Breast Stoping................. 374 Sublevel Stoping.........,....... 374 Square-Set Stoping................ 376 Filling Methods................. 376 Caving Methods of Mining......... 376 Top Slicing.................. 377 Sublevel Caving................. 379 Block Caving ................. 380 Back Caving into Chutes.............. 381. Costs of Mining Methods.............. 382 Costs of Willing and Blasting. Comparison of Stoping Methods ... 383 Lighting................... 386 Timbering and Handling Ore in Stopes.. A Comparison of Square-Set and Top-Slicing Methods..............386 Tramming.................... 380 Mining oF the Massive Porphyry CoppeR Deposits ....390 Utah Copper and Boston Consolidated Mines.....391 Ray Consolidated Mine.............. 392 Miami Mine.................. 392 Inspiration Mine................ 395 Ohio Copper Mine...........395 Development.................... 398 Appendix..................... 399 Costs of Mining................. 399 Costs of Development............... 406

Jan 1, 1915