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By Charles Barrett

SINCE 1925, when the preferred orientations in compressed aluminum were first determined1, 2 the orientations have been described as a fiber texture in which a face diagonal, [110], of the face-centered cubic lattice is parallel to the compression axis. Subsequent experiments have seemed to confirm this texture,3-5 and a number of theories (recently summarized in references 6 and 7) have been proposed to explain it and to relate it to the behavior of single crystals during compression. 3,8-11 The experiments reported in this paper prove that the orientations are not adequately described as quoted above-i.e., as a [110] fiber texture-although this is a first approximation to the actual texture. They also show that the texture cannot be thought of as a stable orienta-tion that is reached and maintained after a sufficient amount of deforma-tion. The actual texture, when studied in detail at successive stages of compression, indicates that a hitherto unsuspected range of orientations is present, both in the polycrystalline metal as a whole and in various individual grains in its interior, and that a state of dynamic equilibrium exists within this range. The reasons for the failure of previous theories to predict the actual texture become obvious when the heterogeneous nature of the flow is considered. In addition to the deformation texture, the manner of its develop-ment, and its theory, this paper presents data on the following related subjects: the identity of strain markings in aluminum; the orientation changes in aluminum single crystals during compression and a com-parison of these with the conditions in individual grains of a polycrystal-line specimen; the origin of asterism in deformed single crystals, which heretofore has been regarded as a distortion localized at the surfaces of slip planes; and the relation of plastic strain in individual grains in an aggregate to the strain of the whole.

Jan 1, 1939

1. How Does One Determine Whether an Ore Body Will Block-cave? Page Mark A. Smith......... 122 Harry A. Leidich........ 122 McHenry Mosier ...,.. 22 R. W. Hughes ........ 122 Sherman R. Burdick ....... 123 R. T. Gallagher........I 23 Benjamin F. Tillson...... 123 Lucien Eaton...........123 C. F. Jackson..... . .. 123 Philip B. Bucky........... 126 2. How Does One Determine the Block Dimensions and the Development Work Necessary to Make an Ore Body Cave? Mark A. Smith... 125, 127, 129 Harry A. Leidich..........126 McHenry Mosier......126, 127, 132 R. W. Hughes...........126 Sherman R. Burdick.........127 R. T. Gallagher...........127 Benjamin F. Tillson......127,131 L. E. Young............127 Robert D. Hoffman.......128, 132 Gerald Sherman..........128 Philip B. Bucky......130, 131, 132 K. S. McClellan..........132 Tell Ertl.............132 3. How Do the Forces Act and What Are the Stresses Developed in a Block That Cause It to Block-cave? Mark A. Smith.........132, 135 Harry A. Leidich........133 McHenry Mosier . .. 133 R. W. Hughes ....... 133 Sherman R. Burdick..... . 133 R. T. Gallagher..........134 C. F. . Price, Jr. ........134 Benjamin F. Tillson.........134 C. F. Jackson......134, 135,137 R. Taborelli...........135 Frank A. Ayer ... .....136 Philip B. Bucky . .........136 Rollin Farmin . . .......136 . . . Weysser.....135, 136, 137 George S. Rice...........137 4. What Determines the Procedure in Removing Caved Ore? Harry A Leidich...........137 McHenry Mosier........137,141 R. W. Hughes...........137 Sherman R. Burdick........138 R. T. Gallagher...........138 Mark . Smith...........138 Philip B. Bucky......140,141,143 C. F. B. Price, Jr..........140 R. H. Bennett...........141 C. F. Jackson..........141, 143 Gerald Sherman..........141 Tell Ertl.............141 .. .. ..................143 C. H. Shoemaker..........143 5. What Are the Criteria for Determining the Efficiency of a Block-caving Operation? Harry A. Leidich.......... 143 McHenry Mosier......... 144 R. W. Hughes........... 144 Sherman R. Burdick.......144 R. T. Gallagher . ......... 144

Jan 1, 1946

By Philip B. Bucky

[CONTENTS t. How Does One Determine WhetherPAGE an ore Body Will Block-cave?R. W. Hughes13 Sherman R. Burdick 13 PAGER. T. Gallagher 14 Mark A. Smith 2 C. F. B. Price, Jr.14 Harry A. Leidich2Benjamin F. Tillson 14 McHenry Mosier2C. F. Jackson14,17 R. W. Hughes2R. Taborelli15 Sherman R. Burdick3Frank A. Ayer16 R. T. Gallagher 3Philip B. Bucky16 Benjamin F. Tillson 3Rollin Farminr6 Lucien Eaton 3J. L. G. Weysser15, 0,17 C. F. Jackson 3George S. Rice17 Philip B. Bucky32. How Does One Determine the Block4. What Determines the Procedure in Dimensions and the DevelopmentRemoving Caved Ore? Work Necessary to Make an OreHarry A. Leidich17 Body Cave?McHenry Mosier17,21 Mark A. Smith 5,7,() R. W. Hughes17 Harry A. Leidich6Sherman R. Burdick 18 McHenry Mosier6,7,12 R. T. Gallagher 18 R. W. Hughes6Mark A. Smith I8 Sherman R. Burdick 7Philip B. Bucky20, 21, 23 R. T. Gallagher 7C. F. B. Price, Jr20 Benjamin F. Tillson 7,11R. H. Bennett21 L. E. Young7C. F. Jackson 21, 23 Robert D. Hoffman8, 1 2Gerald Sherman 3 . 21 Gerald Sherman8Tell Ertl21 Philip B. Bucky10, 11, 12G. K. Foster 23 R. S. McClellan 12C. H. Shoemaker23 Tell Ertl 12 3. How Do the Forces Act and What Are5. What Are the Criteria for Determining the Stresses Developed in a Blockthe Efficiency of a Block-caving That Cause It to Block-cave?Operation? Mark A. Smith 12, ISHarry A. Leidich23 Harry A. Leidich13McHenry Mosier24 McHenry Mosier13R. W. Hughes24 Sherman R. Burdick 24 R. T. Gallagher 24]

Jan 1, 1942

By Cyril Stanley Smith, W. Earl Lindlief

A study of the mechanical properties of the alloys of copper and silver led to the discovery that the solubility of silver in copper was greatly different from that generally supposed, therefore some work was done to determine the solubility with greater accuracy than had previously been achieved. After the work had been completed, two papers were published' giving solubility figures which agreed closely with one another and with the work described herein. A detailed comparison of that work with the present will be given later. Preparation of Allots The copper used in making the alloys was electrolytic ingot of high purity. The silver was prepared by precipitation as chloride from nitric acid solution, followed by fusion of the washed precipitate with sodium carbonate and potassium nitrate. This method gives metal containing at least 99.99 per cent silver. The copper was first melted under charcoal in a small electric resistance furnace and the silver added as pure silver, it being unnecessary to make any intermediate alloys. After thorough stirring the metal was poured into a mold of suitable form. The alloys contained between 0.008 and 0.015 per cent of oxygen. Small amounts of oxide were visible under the microscope, but it is not believed this would have much effect on the results. Copper-silver alloys are notorious for segregation, consequently a few experiments were carried out to find a form of casting with as little segregation as possible. A mold 6 in. long and 1/2-in. dia. was first used, and an alloy nominally containing 5 per cent silver was cast in it, while some of the same alloy was poured directly into water to obtain the maximum rate of cooling possible. Analyses were made both on this sample and on turnings from the top and bottom of the 1/2 in. dia. cast-ing, the turnings being separated into three parts according to the position

Jan 1, 1932

IN the preceding chapter on thermochemistry and the reactions in and between metal and slag phases and in the following chapter on fuel combustion the main emphasis is placed on the equilibrium or "static" conditions. This equilibrium viewpoint is not concerned with the rate of change in the process or with the mechanisms or paths followed between initial and final states. The questions of just "how it works" and "how fast" belong to the kinetic aspect of any process; their answers are helpful in speeding up or slowing down and thus controlling its operation, and also in understanding its limitations. Any treatment of kinetic factors in the open hearth such as is attempted here and in Chapter 22 must at present be largely qualitative and incomplete. We are only beginning to get quantitative data on rates of reaction and diffusion at high temperatures, as indicated in Chapter 15. Empirical data in the literature on furnace operating rates do not help much to illuminate the details of gas-flow patterns and the complexities of heat flow in the many parts of the furnace system. This chapter is intended to give the reader an introduction to the problems of the flow of gases through the furnace system and the flow of heat in this system. An adequate discussion would require several times the space available here; it is possible here only to outline a few fundamentals and to indicate some of the conditions of heat and gas flow peculiar to the open hearth. Several good general treatments of these subjects may be found in the literature (see references at the end of the chapter). For the designer of open-hearth furnaces, the principles of gas flow are of paramount importance. They are also important to the operation of the process, at least to the extent of a general qualitative picture of the movement of gases in the system. MOTION OF GASES IN FURNACE DUCTS Fluid [flow] in general can vary between the extremes of laminar or streamline flow with a minimum energy loss, to irregular

Jan 1, 1964

By B. H. Kear, S. M. Copley

A dynamic theory of precipitation hardening in alloys containing cohevenl, stvess-.free, ordered particles is developed. The yield stvess is predicted from the stress dependence of the plastic strain vale, which is related to a derived dislocation velocity-stress function. The theory is shown to predict the magnilude and temperature dependence of the yield stress of a commercial nickel-base superalloy as well as many details of its slip structure. GLEITER and Hornbogen have developed a theory of the yield stress in alloys hardened by coherent, stress-free ordered ptrticles based on the observation that dislocations (b = a/2 (110)) glide in pairs.' When a dislocation pair shears through an ordered particle, the glide motion of the leading dislocation is impeded since it must create antiphase boundary (APB), whereas the motion of the trailing dislocation is assisted because it annihilates APB produced by the first one. Taking into account the APB energy, the size, and spacing of the particles, G-H predict the observed yielding behavior in Ni/18.8 Cr/6.2 A1 alloys composed of a matrix phase y '(nickel-solid solution) and particles of y' (basically Ni3A1). The G-H theory, as well as all previous theories of hardening by coherent ordered particles, do not include the details of dislocation motion; the present dynamic theory is an attempt to overcome this limitation. In the dynamic theory, the yield stress is predicted from the stress dependence of the plastic strain rate, which is related to a derived dislocation velocity-stress function. This function can be evaluated if the structure of the alloy, the APB energy of the ordered phase, and the characteristic drag or frictional stresses of the matrix and precipitate phases are known. The theory is shown to account for the observed temperature dependence of the yield stress in a commercial nickel-base superalloy. 1) NICKEL-BASE SUPERALLOYS Although their compositions are complex, the nickel-base superalloys have remarkably simple structures. A detailed examination of the commercial superalloy

Jan 1, 1968

By Earl S. Greiner, Bradley Stoughton

As a part of the systematic study of the alloys of iron under the auspices of the Engineering Foundation, and preliminary to the commencement of comprehensive work on this larger subject, the authors have undertaken an investigation of the available literature dealing with the alloys of iron and silicon. The purpose is to collect all the data in English and foreign languages and present them in two monographs, one of a more scientific and the second of a more industrially useful nature. Of course, a great deal of information upon the constitution of the iron-silicon alloys was found specificially upon the changes of phase in the equilibrium diagram and the different phases present, such as solid solution, chemical compounds (iron silicides), etc. While no extended research was contemplated in the particular study undertaken, nevertheless the data collected proved to be so contradictory in many respects that a simple study of some of the outstanding problems involved in the constitution and equilibrium diagram was undertaken. Because research was not a primary object of the work, and also because of the extreme industrial importance of the silicon alloys between 0.80 and 14 per cent. silicon, and finally because of the unsatisfactory state of knowledge existing as to these alloys, the experimental investigation was limited entirely to alloys with less than 10 per cent. silicon. Discussion oF Continuous Series It has often been said in print that the iron-silicon alloys form a continuous series of solid solutions from 0 to 15 per cent. silicon. This claim the authors are inclined to doubt: first, because the alloys from 0 to 4.25 per cent. silicon are ductile and malleable at atmospheric temperature, while those with 5 per cent. or more of silicon are comparatively hard and brittle. Furthermore, the alloys with more than 4.25 per cent. silicon are comparatively hard and low in ductility at atmospheric temperature, but become much more ductile when heated slightly. It is well known, for example, that the alloy containing 4.75

Jan 1, 1930

By Granville S. Borden

The fruits of industry are divided between capital, labor, and governments. Capital takes its redemption and remuneration through profits or dividends; labor takes its share through wages; governments take their share through taxes. Each must have a just share, and the question of what is a just share and the question of who-shall make the allocation are vital current political and economic issues. Certain political philosophies con- tend that government should take all the fruits and that some dictator or politician should have irrevocable discretion and power to distribute the fruits. Believers in democracy and free enterprise adhere to the view that capital is entitled to redemption and fair remuneration; that labor shall have a fair wage; and that governments shall make equitable levies. But since all human beings, both individually and in groups, are inherently selfish, there are many variable views in regard to the question of what ratios shall be applied in a division of the fruits and who shall have the power to fix these ratios. Perhaps all parties should devote more energy to means of increasing the crop, and not so much time to quarreling over a division of the existing crop. Moreover, all three parties must guard against killing the goose that lays the mineral eggs. For example, if the tax burden becomes oppressive and the taxpayer refuses to carry it, then business stagnates, with consequent unemployment, reduction of profits, and curtailment of government revenue. If a producer assumes the increased tax burden, marginal operations must be closed down, and again the consequences are increased unemployment and diminished government revenue. Quite often an increase in a rate of tax results in a reduction of government revenue. Perhaps the worst detrimental feature of selfishness and greed on the part of any one of the three distributees of the fruits of industry is the retardation of expansion of the enterprise. Growth means new jobs, more government revenue, better trade, and better standards of living. Explorations and discoveries have resulted in tremendous contributions

Jan 1, 1959

THE refining period of an open-hearth heat blends imperceptibly into the finishing period, during which final adjustments are made in slag composition, in bath action and temperature, and in composition of the steel, in order to prepare it for casting into ingots. Operations must be governed by the consideration that alterations in the character of the heat during the finishing period must be held to a minimum. In a broad sense, the finishing and deoxidation period of a heat may be said to begin when the action of the last ore addition has ceased, and to end when the teeming of the ingots is completed. INGOT STRUCTURES A survey of the relative advantages and disadvantages of different types of ingot structure is required because deoxidation treatments during the finishing period control the amount of gas evolved during solidification and consequently determine the type of ingot structure. Four classes of ingots are recognized, depending upon the degree of deoxidation to which the steel has been subjected. These types are killed, semikilled, capped, and rimmed; typical examples of their structures are represented by ingots 1, 2, 5, and 7, respectively, of Fig 9-1. The actual ingots from which these cross sections were sketched were all poured to the same height (indicated by the dotted lines) in the same type and size of bottle-top molds. The eight drawings of the figure represent selected types of ingot structure in a continuous series from "dead killed" to "wild," resulting from variations in the total quantity of gas evolved, from none at all to copious amounts, during solidification of the steel in the mold. Killed and semikilled steels are adjacent at the "quiescent" end of the ingot structure series where only small amounts of gas are evolved. The term "quiescent" describes the action of the molten metal during and subsequent to the teeming of killed and semikilled steels. Capped and rimmed steels are adjacent at the

Jan 1, 1951

By G. E. Goodspeed

The Cornucopia gold quartz veins form a parallel vein system traversing meta-morphic and granodioritic rocks. Field and petrographic evidence suggests that inetasomatism has played an important role both in the emplacement of the grano-diorite and in the formation of the veins. Structurally the veins appear to be related to the major tectonic features of the Wallowa Mountains and to be narrow shear zones rather than filled fissures. Petrographic studies indicate a complex history of formation starting from initial alteration along fractures or joints followed by recurrent fracturing and a quartz-forming stage, and closing with continued shearing and microbrecciation, which permitted the upward percolation of the later ore-forming solutions. The precipitation of ore minerals from these solutions formed ore shoots. Postmineral effects include the injection of Tertiary basaltic dikes, a shght amount of cross faulting, and some movement along the planes of the veins as well as oxidation. Introduction Cornucopia is in the southeastern part of the rugged Wallowa Mountains of northeastern Oregon. It was founded over 50 years ago following the discovery of its system of gold quartz veins. The major veins are roughly parallel and dip into the western side of Pine Valley, which drains the southern slope of the range. Previous operations had cut the upper portion of four major veins with two tunnels over 1000 ft. apart, when the present operating company drove a third tunnel, called the Coulter, at the level of the valley over 1000 ft. lower to intersect the most easterly major vein at over 6200 ft. from the portal. General Geology of District The oldest rocks in the vicinity are metamorphosed sediments and volcanics. These, for the most part, are presumably Mesozoic in age, although some black argillites outcropping along East Pine Creek are considered to be Permian.l,2 These rocks have been deformed and metamorphosed in general to hornfels at the close of the Jurassic. The series was then invaded by a granodiorite batholith, the origin of which is

Jan 1, 1941

By C. H. Mathewson, P.W. Bakararian

The greatcr part of the literature on the plastic behavior of magnesium dates back to that active period of research in crystal mechanics immediately following the widespread preparation of isolated metallic crystals large enough for the application of conventional methods of mechanical testing. These investigations, performed on single crystals, revealed an analogy between zinc and magnesium with respect to their fundamental mode of deformation. in the operation of glide and twinning, respectively, on crystallographically similar planes. Mathewson and Phillips (1928)' by geometrical analysis identified the plane in magnesium as the twinning plane. Schiebold and Siebel (1931) confirmed this twinning planc, established the basal plane as the plane of slip, and a digonal axis I as the slip direction. They also rcported twin formation in a secondary role on the {IOI} plane. Schmid (1931)³ summarized and discussed the earlier evidence and presented the results of his own experiments on the effect of temperature and small amounts of soluble elements. From X-ray studies on extended wire single crystals, he concluded that slip along the basal plane in the direction of the digonal axis I closest to the stress direction was the sole slip system operating at atmospheric temperature. This conclusion was based on experiments with crystals of many different orientations relative to the stress axis. Special attention was directed to the basal plane and the digonal axis I, as the plane and direction of greatest atomic density. Determinations of resolved shear stress at the onset of plastic yielding-—i.e., the critical resolved shear stress—were also made; the average of these calculations showing 82.9 grams per sq. mm. This value varied only slightly up to 300°C. at which temperature it was found to decrease to 70.5 grams per sq. mm. The extension of his crystals at temperatures above 225°C. further disclosed the presence of new slip systems. After the origince specimens of circular section had been

Jan 1, 1943

By J. E. Burke, C. S. Barrett

The fine lines shown in Fig I are typical of markings that ma): be detected after polishing and etching deformed specimens of alpha brass and other alloys. Although they have long been the subject of discussion by metallurgists their nature is still uncertain and the names that have been applied: to them, such as deformation line4 or strain markinas, indicate this uncertainky. In this paper which repotts the results of a furthcr investigatinn of their nature, they will be called strain mxrkings. Introduction Mathewson and Phillips1 described strain markinps in 1 916 and concluded that they appear only after 20 pet deformation. They objected to the markings being called slip tines believing this term should be sewrved for surface markings protluced by plastic deformntion. In 1921. vogel² described similar striations which appeared after polishing and etching the roughly ground surface of numerous alloys. He reported that the markings were crystallo-graphic in nature, and since they resemble Seumann hands in iron, at least superficially, he assumed them to be mechanical twins. In 1928, Matherwson reported work by Phillips which indicated that the lines were more readily produced by impact than by slow deformation and that in many cases the twins inside recrystallized grains were parallel to strain markings in the original deformed grains. This was taken as cvirlence that the markings coalesce into anncaling twins. and hence that they themselves are mechanical twins. Many attempts have been made to demonstrate directly that the markings are mechanical twins. In 1934, Samans described the results of X ray studies of two defomed crystals of alpha brass. Evidence was obtained which could be interpreted to indicate that the strain markings arc mechanical twins, and this remains the only direct evidence to this effect. Several other attempts to obtain similar evidence by X ray diffraction have failed5.8.7 although in no Ease was the original method of Samans employed. An

Jan 1, 1949

By C. S. Barrett, J. E. Burke

The fine lines shown in Fig I are typical of markings that ma): be detected after polishing and etching deformed specimens of alpha brass and other alloys. Although they have long been the subject of discussion by metallurgists their nature is still uncertain and the names that have been applied: to them, such as deformation line4 or strain markinas, indicate this uncertainky. In this paper which repotts the results of a furthcr investigatinn of their nature, they will be called strain mxrkings. Introduction Mathewson and Phillips1 described strain markinps in 1 916 and concluded that they appear only after 20 pet deformation. They objected to the markings being called slip tines believing this term should be sewrved for surface markings protluced by plastic deformntion. In 1921. vogel² described similar striations which appeared after polishing and etching the roughly ground surface of numerous alloys. He reported that the markings were crystallo-graphic in nature, and since they resemble Seumann hands in iron, at least superficially, he assumed them to be mechanical twins. In 1928, Matherwson reported work by Phillips which indicated that the lines were more readily produced by impact than by slow deformation and that in many cases the twins inside recrystallized grains were parallel to strain markings in the original deformed grains. This was taken as cvirlence that the markings coalesce into anncaling twins. and hence that they themselves are mechanical twins. Many attempts have been made to demonstrate directly that the markings are mechanical twins. In 1934, Samans described the results of X ray studies of two defomed crystals of alpha brass. Evidence was obtained which could be interpreted to indicate that the strain markings arc mechanical twins, and this remains the only direct evidence to this effect. Several other attempts to obtain similar evidence by X ray diffraction have failed5.8.7 although in no Ease was the original method of Samans employed. An

Jan 1, 1949

By C. H. Mathewson, P. W. Bakararian

The greatcr part of the literature on the plastic behavior of magnesium dates back to that active period of research in crystal mechanics immediately following the widespread preparation of isolated metallic crystals large enough for the application of conventional methods of mechanical testing. These investigations, performed on single crystals, revealed an analogy between zinc and magnesium with respect to their fundamental mode of deformation. in the operation of glide and twinning, respectively, on crystallographically similar planes. Mathewson and Phillips (1928)' by geometrical analysis identified the plane in magnesium as the twinning plane. Schiebold and Siebel (1931) confirmed this twinning planc, established the basal plane as the plane of slip, and a digonal axis I as the slip direction. They also rcported twin formation in a secondary role on the {IOI} plane. Schmid (1931)³ summarized and discussed the earlier evidence and presented the results of his own experiments on the effect of temperature and small amounts of soluble elements. From X-ray studies on extended wire single crystals, he concluded that slip along the basal plane in the direction of the digonal axis I closest to the stress direction was the sole slip system operating at atmospheric temperature. This conclusion was based on experiments with crystals of many different orientations relative to the stress axis. Special attention was directed to the basal plane and the digonal axis I, as the plane and direction of greatest atomic density. Determinations of resolved shear stress at the onset of plastic yielding-—i.e., the critical resolved shear stress—were also made; the average of these calculations showing 82.9 grams per sq. mm. This value varied only slightly up to 300°C. at which temperature it was found to decrease to 70.5 grams per sq. mm. The extension of his crystals at temperatures above 225°C. further disclosed the presence of new slip systems. After the origince specimens of circular section had been

Jan 1, 1943

By J. E. Burke, C. S. Barrett

THE fine lines shown in Fig 1 are typical of markings that may be detected after polishing and etching deformed specimens of alpha brass and other alloys. Although they have long been the subject of discussion by metallurgists their nature is still uncertain and the names that have been applied to them, such as deformation lines or strain markings, indicate this uncertainty. In this paper which reports the results of a further investigation of their nature, they will be called strain markings. INTRODUCTION Matthewson and Phillips1 in 1916 concluded that strain markings appeared only after deformations that exceeded 20 pct. They objected to the markings being called slip lines believing this term should be reserved for surface markings produced by plastic deformation. In 1921, Vogel2 described similar striations which appeared after polishing and etching the roughly ground surface of numerous alloys. He reported that the markings were crystallographic in nature, and since they resemble Neumann bands in iron, at least superficially, he assumed them to be mechanical twins. In 1928, Matthewson3 reported work by Phillips which indicated that the lines were more readily produced by impact than by slow deformation and that in many cases the twins inside recrystallized grains were parallel to strain markings in the original deformed grains. This was taken as evidence that the markings coalesce into annealing twins, and hence that they themselves are mechanical twins. Many attempts have been made to [ ] demonstrate directly that the markings are mechanical twins. In 1934, Samans4 described the results of X ray studies of two deformed crystals of alpha brass. Evidence was obtained which could be interpreted to indicate that the strain markings are mechanical twins, and this remains the only direct evidence to this effect. Several other attempts to obtain similar evidence by X ray diffraction have failed5,6,7 although in no case was the original method of Samans employed. An

Jan 1, 1948

By Thomas Egleston

DURING the year 1873, my attention was called to the frequent accidents, resulting from the breaking of rails, on the different railroads in this' country, and I was requested to investigate the subject. The plan of investigation I proposed was to ascertain, in as many cases as possible, the exact hist* of broken rails, both in this country and in Europe; to collect information in Europe relating to the tests which rails used there were required to undergo, and to experiment upon the pieces of rails broken on the road, with a view to ascertain whether their fracture was due to their chemical constitution, bad manufacture, to a reduction in strength owing to temperature, or to physical changes in the constitution of the rail. The investigation was commenced by the collection of statistics, and for this purpose I spent several months in Europe, collecting information on the subject of broken rails, as well as the life of iron and steel rails generally, and inquiring into the systems of purchasing and of testing them employed by the railroads there, intending, on my return, to make a series of analyses of rails broken, both in this country and in Europe; to ascertain, if possible, how far great cold had an influence on the fracture; to examine whether the rail broken, either on the road or afterwards, underwent, at or about the fracture, any physical change, and to make a series of experiments on the strength of rails manufactured in the United States or sold in the American market. Unfortunately, the panic of 1873 came on, just before my return from Europe, and prevented the carrying out of the larger part of the plan proposed; as, however, I had collected in the meantime, a large number of statistics of different kinds from all parts of Europe, and had made a number of interesting experiments and investigations, I have thought it would be worth while to communicate some

By T. Egleston

DURING the year 1873, my attention was called to the frequent accidents, resulting from the breaking of rails, on the different railroads in this country, and I was requested to investigate the subject. The plan of investigation I proposed was to ascertain, in as many cases as possible, the exact history of broken rails, both in this country and in Europe; to collect information in Europe relating to the tests which rails used there were required to undergo, and to experiment upon the pieces of rails broken on the road, with a view to ascertain whether their fracture was due to their chemical constitution, bad manufacture, to a reduction in strength owing to temperature, or to physical changes in the constitution of the rail. The investigation was commenced by the collection of statistics, and for this purpose I spent several months in Europe, collecting information on the subject of broken rails, as well as the life of iron and steel rails generally, and inquiring into the systems of purchasing and of testing them employed by the railroads there, intending, on my return, to make a series of analyses of rails broken, both in this country and in Europe; to ascertain, if possible, how far great cold had an influence on the fracture ; to examine whether the rail broken, either on the road or afterwards, underwent, at or about the fracture, any physical change, and to make a series of experiments on the strength of rails manufactured in the United States or sold in the American market. Unfortunately, the panic of 1873 came on, just before my return from Europe, and prevented the carrying out of the larger part of the plan proposed ; as, however, I had collected in the meantime, a large number of statistics of different kinds from all parts of Europe, and had made a number of interesting experiments and investigations, I have thought it would be worth while to communicate some

Jan 1, 1875

MINING, to be precise, ends when the ore is delivered to a bin outside the mine. Usually the next step is concentrating; or, as it is more often called, milling. A few elementary definitions will help make clear the discussion that is to follow. A rock is an aggregate of minerals; copper ore is rock that contains copper-bearing minerals in quantity sufficient to make it profitable to mine and recover the copper in the form of marketable metal. Manifestly, under a literal interpretation, a mass of material might be copper ore one day and merely copper-bearing waste rock a week later, if the price of copper happened to drop in the interim. Emphasis already has been placed on the expansion that took place in the ore reserves of the Porphyry companies as a consequence of the great strides made in the technique of mining and ore treatment. So, even if one inserted a qualifying phrase, "at an average price for the metal," after the word "profitable," the definition would still be open to criticism. Place is another factor. It is evident that a body of excellent ore in Arizona might cease to be ore in the economic sense if it were moved intact to the interior of China. However, it is with ore in its technical and scientific aspect that this chapter is concerned. Speaking in general terms, the ton of Porphyry ore as it arrives at the surface contains 25 to 70 lb. of copper minerals in the form of disseminated particles or thin coats along fracture planes. When subjected to appropriate treatment this ton yields 12 to 40 lb. of metallic copper. These ranges take into account conditions of today and of 25 years ago. Two procedures are available: (1) concentration, followed by smelting of the concentrate, or (2) leaching and precipitation, usually by electrolytic deposition. Smelting and leaching are metallurgic processes in that they involve chemical change; concentration

Jan 1, 1933

By H. Shaw

GRAVITATIONAL measurements made by means of the Eötvös torsion balance over any area enable a representation to be obtained of the total gravitational effects over the surface of that area arising from the combination of all sources of gravitational disturbance. The investigation of gravitational anomalies occurring in the upper layers of the earth's crust, in this way, has been attended with considerable success, and, especially in areas in which no undesirable disturbing factors were present, it has been possible to locate geological structures and mineral deposits with remarkable accuracy and also to delineate their confines and to indicate their depth below the surface with a certain amount of precision. Before this can be done successfully, however, it is necessary to determine the gravitational effect arising from all other extraneous .anomalies in order that these may be satisfactorily eliminated. Disturbing features giving rise to these gravitational anomalies may be divided into two classes, according to whether they are situated at or below the surface. The former are determined readily by a detailed leveling of the ground surface, and may be satisfactorily eliminated provided the specific gravity of the terrain material is known, but the latter are generally unknown, and can only be ascertained with difficulty. When, therefore, the observations obtained by means of the Eötvös torsion balance have been corrected for all surface irregularities, known as terrain and topographical effects, there remain residual gravitational values which are due entirely to subterranean conditions. The task of interpreting these results consists in disentangling the various subsurface anomalies, and subsequently in computing and recombining the effects of these various masses in order to verify the interpretation. When the gravitational anomalies are due to large and comparatively simple structures it is a matter of little difficulty to arrive at a satisfactory interpretation of the subterranean conditions, but in more complex areas, where the geological conditions are more complicated and several irregular features exist, the process of disentangling the various constituents of the complex mass arrangement is more difficult and requires the expenditure of considerable time and labor.

Jan 1, 1929

By Wm. B. Price

The work of Leon Guillet concerning the effect of nickel on the structural properties of brass is checked. The best value for the coefficient of equivalence t, that is, the amount of zinc replaced by 1 per cent. of nickel, is shown to be-1.1 per cent. The best hot- and cold-working nickel silvers, varying in nickel content between the limits of 4 and 18 per cent., are tabulated and plotted diagrammatically. Also, some data are given showing a comparison between the physical properties of a hot- and cold-working low copper-nickel silver, and a commercial cold-working nickel silver containing approximately 8 per cent. more copper. THIS investigation of low copper-nickel silvers was undertaken to check the work of Leon Guillet on special brasses and to determine, more accurately, the effect of the addition of nickel on the microstructure of the binary alloys of copper and zinc. It was hoped that the results could be successfully applied to the practical production of low copper-nickel silvers. To explain the results of his investigations on special brasses, Leon Guillet evolved his conception of "fictitious compositions." He states,1 in his general conclusions, that on the introduction of a small amount of a third metal to a copper-zinc alloy, it enters into solid solution with the normal constituents up to saturation, but by so doing it brings the ternary alloy into a state microscopically equivalent to a binary copper-zinc alloy of fictitious composition, and physically more nearly like the latter than the brass containing copper-zinc in the ratio actually present. The physical properties of the ternary alloy, when compared to the same properties of an actual brass of the fictitious composition, are modified by the natural properties of the third element. Beyond the point of saturation, a special constituent appears and the above generalization no longer holds.

Jan 2, 1924