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By Macelwane

WHAT characterizes a geophysical engineer and sets him apart from all other engineers? This is a question that is important not only for accrediting purposes but is assuming increasing importance in the licensing of professional geophysical engineers by state boards. What is the basis of distinction of one type of professional engineer from another type is answered in part by the need which brought each type into being precisely because that need could not be satisfied by pre-existing types and which nevertheless demanded the special outlook, training, and abilities of an engineer. The need which called for the civil engineer was the adaptation to the tasks of civilian life of the capabilities developed by the military engineer for the design and construction of roads, bridges, dams, earthworks, military buildings, and other structures and of mechanisms required by military operations.

Jan 4, 1954

By J. Gurland

The effects of variations of carbon content on the constitution and properties of sintered WC-Co alloys were studied. The grain growth of tungsten carbide during sintering was measured and it was shown that it takes place mainly by solution and reprecipitation of the carbide in and from the binder at the sintering temperature. It was found that the decomposition of W3C03C by carburization during sintering is responsible for the formation of very large grains. THE properties of sintered WC-Co alloys are critically dependent upon their final composition and structure. Slight changes of cobalt and carbon contents and small variations of grain size result in marked changes of mechanical properties and performance of products. Previous investigators have studied the microstructure as a function of composition' and have dealt with the influence of cobalt upon properties.' The present work is concerned with the effect of carbon content upon constitution, microstructure, and grain growth during sintering, as well as upon the physical properties of sintered compacts. Phase Boundaries at the Sintering Temperature The WC-Co section through the ternary diagram W-Co-C has been studied by Wyman and Kelley,' Takeda,V andford and Trent," and Rautala and Norton." Two phases, namely WC and a cobalt-rich solid solution (P), appear in the sintered structure if the carbon composition corresponds very nearly to the theoretical carbon content of WC (6.12 pct C). But small deviations from the ideal carbon content will bring about the occurrence of either graphite or the double carbide W,Co3C (7) . The 7 phase was long believed to be metastable, this conclusion being based mainly on the work of Takeda. More recent studies have shown that it is a stable phase of the ternary system,"5 but the actual phase boundaries have not been established and there has been some discussion as to whether or not the 7 phase occurs at some stage of sintering in the fully carburized alloys." In view of this uncertainty it was thought advisable to undertake an investigation of the phases present during the sintering of WC-Co alloys. Commercially available tungsten, cobalt, and carbon powders were used in the present study. A typical analysis of impurities in a sintered compact is reported in Table I. The desired carbon compositions were attained by varying the amount of carbon added to the tungsten during carburization and controlling the composition during sintering by packing the compacts into beds of mixed alundum-carbon powders of suitably selected ratios. The alloys were sintered in a hydrogen tube furnace at 1400°C, then brought to equilibrium at the temperature under investigation and quenched in water. The high temperature phases were identified by metallographic and X-ray diffraction techniques. The samples were etched with a 10 pct solution of alkaline potassium ferricyanide. The phase boundaries, established by metallo-graphic examination, are shown in Fig. 1, which is a vertical section through the ternary diagram at 16 pct Co. The temperatures of the invariant planes, at 1298" and 1357°C were established by Rautala and Norton. The vertical section shows that the three-phase field, WC + 7 + L, extends into the two-phase field, WC + L, but does not include the stoichiometric composition of WC. In practice this means that the 7

Jan 1, 1955

Abbey, Robert Graham, District Mgr.. The W. W. Sly Mfg. Co., 50 Church St.. New York, N. Y. '21 Abbott, A. N., Mines Supt., Mazapil Copper Co., LtdConcepcion del Oro, Zac., Mexico. '28 *Abbott, Argyle Campbell, Dev. Dept., E. I. du Pont de Nemours & Co., Wilmington, Del. '29 Abbott, Clarence E., V.P., Charge of Raw Materials, Tenn. Coal, Iron & R. R. Co., 1242 Brown-Marx Bldg.. Birmingham, Ala. '04 Abbott, Louis Benjamin, Chief Engr., Elkhorn Div., Consolidation Coal Co., Jenkins, Ky. '16 Abeel, George H., Jr., Cons. Min. Engr Box 427, Santa Monica, Cal. '18 Abel, Albert E., Asst. to Pres., Valley Mould & Iron Corp Hubbard, Ohio. '19 Abel, Raymond L., Asst. Prof., Dept. of Pet. Refin., Univ. of Pittsburgh Pittsburgh. Pa. '28 Abeel, Leo M., Research Engr., Sullivan Concentrator Chapman Camp, B. C., Canada. '31

Jan 1, 1929

By E-Tu Zen Sun

Yunnan, a mountainous province in southwestern China, began to assume its place as an important producer of copper toward the end of the Ming dynasty (latter part of the 16th century), and since then has continued, with minor interruptions, to occupy a leading position as one of the few areas in China where relatively significant amounts of this metal can be produced. Among the copper deposits of this province, those of the following three localities have stood out as being the most significant. 1. Tung-ch'uan, in northeastern Yunnan. Here the ores are primarily bornite and chalcocite, with copper content ranging from 2% to 15% the most noteworthy T'ang-tan mine producing ores averaging 12% copper. Estimated total reserve of pure copper in this area is approximately 1,000,000 metric tons.

Jan 7, 1964

By Paul D. Foote

Most of the treatises on metallurgy intimate that simultaneously with the development by the atomic physicist of a really satisfactory theory of the atom will be inaugurated a new epoch in the science of metals. Metallurgically and metaphorically, we shall dwell in the Utopia of Sir Thomas More. It is my privilege this afternoon to demonstrate that this state has not arrived. An atom is a miniature planetary system consisting of a positively charged nuclear sun about which revolve electrons each carrying the negative charge e. The charge on the nucleus is + Ze where Z is the atomic number and the number of planetary electrons in a neutral atom is equal to Z. These electrons are arranged in several groups having different binding energies. Ordinary x-ray phenomena relate to processes occurring deep within the atom, usually with electrons in the so-called K or L shells. Such electrons in the heavier atoms are so closely bound to the nucleus that the forces exerted by neighboring atoms in a solid are relatively inappreciable. For most practical x-ray investigation, the atom may be considered as in the gaseous phase completely isolated from its neighbors. The K radiation from an element in the gaseous state, in the solid or liquid phase, or even in combination with other elements in all its possible valences, is almost identical.‡ Visual and ultraviolet spectroscopy is concerned with disturbances of the most loosely bound outer or valence electrons of the atom, always in the vapor state. The remarkable progress of the last year in both theo-

Jan 1, 1926

By K. E. Beu

IN the measurement of retained austenite concentrations in steels using the integrated intensity method,1 Averbach has pointed out" that the absorption factor A(0) for a flat sample making a glancing angle 4 with the incident X-ray beam can be combined with his constant factor R to obtain our constant factor" G provided that "1—There is no preferred orientation in the sample, and 2—The geometric requirements [for the sample, film, and X-ray beam] have been met precisely."' If A(0) can be combined with R to give G according to the equation G = R . A(0) [14] then the possibility for making non-compensating errors in the austenite determination has been eliminated. This has been described previously in a technical note." Because of the brevity of the previous note,3 it was impossible to emphasize the fact that the two conditions on preferred orientation and geometry can be easily met experimentally, contrary to Aver-bach's statement that: ". . . the necessary conditions must be tested experimentally for each determination, and this is done most easily by observing whether the apparent absorption has the form of Eq. 2 [the theoretical equation for A(0)]."" he way in which these two conditions can be met experimentally will be discussed briefly to help clear up this point. In addition to these two conditions, other factors such as sample shape, homogeneity, and grain size which also affect A will be included in this discussion. A (0) depends on sample shape. The theoretical function for A was derived originally for a flat surface.' In general we have found that a flat sample surface is readily obtainable." If such a surface can * The effect of surfaces which are not flat on the measurement of retained austenite will be discussed later. be obtained, it has the following advantages: 1—it is easily reproducible from sample to sample, 2—it is the form required for metallurgical examination —this type of examination being frequently desirable for this work, and 3—it is an efficient shape for diffraction purposes. Perhaps the most important of these features is that a flat sample surface is easily reproducible; hence, this requirement on the repro-ducibility of A from sample to sample is met for all such samples. Fig. 1—Schematic diagram of the quartz crystal monochromator diffraction unit. The centerline of the main beam is at 6' to the target face. The tangent to the crystal face is at 16.8' to the moin beam. The centerline of the monochromatic beam is at 33.6 to the main beam. The sample surface can be rotated in its own plane. The angle of the sample surface and the monochromatic beam can be adjusted by rotating about the vertical axis, The film holder can also be rotated about B so that the film can be exposed over the desired angular range. For Fe K, X = 1.932A. 1011 planes of quartz have d = 3.35A. A(0) depends on homogeneity and grain size. If the sample is badly segregated or the grain size is large, the effect of micro-absorption and primary extinction1. ' must be considered. It has been shown, however, that for most plain carbon or low alloy hardened steels, neither micro-absorption nor primary extinction effects are present.' A (0) depends on camera geometry. For a given angle 0, A remains theoretically constant from a geometrical viewpoint only if the following factors are kept constant: 1—the angle of inclination .+ of the sample to the X-ray beam, and 2—the centering of the sample with respect to the film cylinder. These are mechanical problems which can be solved readily if the facilities of a good machine shop are available. The arrangement used to insure that the angle 4 remains constant and the centering of the sample is reproducible is indicated schematically in Fig. 1. The sample is clamped against a thin plate with a hole in it by means of a spring-loaded pres-

Jan 1, 1954

By R. Schuhmann

The expression "unit process " comes up with increasing frequency in discussions among metallurgists and mineral engineers, especially among those concerned with training the next generation. The unit process approach characterizes a significant advance along the road from metallurgy as an empirical art to metallurgy as a branch of engineering. The purposes of this paper are to define and list the unit processes in specific terms, to indicate the scientific and engineering principles basic to all the unit processes, and finally to show how these ideas have been applied to a reorganization of instruction in chemical metallurgy. Unit Operations and Unit Processes Metals are extracted from ores and other raw materials by stepwise procedures. In general, each metallic element is extracted by a different procedure. For many of the metals there is a choice of several flowsheets. However, the procedures all have steps in common. In fact, the many different flowsheets are all made up of a relatively small number of steps which are combined in different groups and sequences. For example, crushing, screening, roasting, sintering, melting, and gaseous reduction are steps which each appear in the Bowsheets for extracting the majority of the metals. The individual steps or flowsheet units can be designated as unit operations or unit processes. These terms are well established in the field of chemical engineering, as the American Institute of Chemical Engineers' definition of chemical engineering shows: " Chemical engineering is that branch of engineering concerned with the development and application of manufacturing processes in which chemical or certain physical changes of materials are involved. These processes may usually be resolved into a coordinated series of unit physical operations and unit chemical processes. The work of the chemical engineer is concerned primarily with the design, construction, and operation of equipment and plants in which these unit operations and processes are applied. Chemistry, physics, and mathematics are the underlying sciences of chemical engineering, and economics its guide in practice."'1a In this definition, the distinction between unit operations and unit processes is that the unit operations are physical while the unit processes are chemical. Table I gives a list of the principal unit operations and unit processes of chemical engineering, taken from Shreve.1b Table 2 lists the principal unit operations and unit processes used for metal extraction. The division between unit operations and unit processes is similar to the chemical engineers' distinction and also correspollds approximately to the division of labor bctween mineral dressing and chemical metallurgy which has been customary in the past. Furthermore, it will be noted that in the proposed classification the unit processes primarily involve chemical reactions and/or changes in state of aggregation; the unit operations primarily do not involve either bulk

Jan 1, 1949

By R. P. Olsen, A. K. Schellinger

Molten silicate salts, the important industrial byproducts termed "slags," are known to be electrolytic conductors at furnace temperatures. This property is due to their partial dissociation into ions with the ion kind and size being closely related to the slag composition. Ionic conductance, in liquids, is a function of the viscosity, which in turn is a function of the temperature. It could be anticipated, therefore, that a semi-log plot of conductivity vs. reciprocal absolute temperature might yield a straight line, in the case of molten silicates and salts. As liquids, the viscosity of these slags should follow the Shepard1 relationship: log viscosity = A/T + B Then, if the resistance of the molten slag is directly proportional to the viscosity: log Rs = A/T + B Resistance measurements of molten halide salts,2 and silicate salts34 by various investigators have, indeed, shown this straight line relationship between resistance and temperature. A further relationship between the conductivity versus the degree of ioni-zation, the size of the ions, and the slag composition is, also, to be expected. Large ions, and fewer ions, would move more slowly in a potential field and could not carry as much current as smaller, more numerous, and mobile, ions. Conductivity, therefore, would be smaller in the presence of such large ions and higher slag viscosities. The conductivity-composition relationship is of considerable interest in the case of the industrial slags produced in iron blast furnaces, and non-ferrous smelting furnaces. These slags usually approximate three component systems with several minor components as impurities. At least one of the major components is commonly purchased for the sole purpose of rendering the slag less viscous at a reasonable furnace temperature. Should the conductivity be related rather directly to the concentration of such a purchased slag component (that is, CaO) instrumental measurement and control at the furnace might be possible. Modern tele-metric control methods in aqueous chemical process industries are often based on the property of conductivity of solutions, and its variation with composition. Investigators3 of the phenomenon of electrical conductivity in molten blast furnace slags have established that these systems show lines of equal conductivity on their ternary diagrams at one temperature level. These isocon-ductivity lines form closed contours on the diagrams, and at times, minimum areas occur at which these contours are essentially closed down to a point. The conductivity reading at such a point, at one temperature , would, of course, locate one on the diagram, and give the slag composition. Research in this field is understandably scanty. The reactive nature of

Jan 1, 1950

By J. Versluys

A well can flow exclusively through the casing or exclusively through a tubing but can also flow partly through a casing and at the top part through a tubing. The main principles of the flowing of wells under these conditions were explained in the author's former paper.' Practically all factors that influence the regular flow are dealt with therein. The question of irregular flow, however, will be discussed briefly here. As a rule, an irregular flow must be avoided, as it may be assumed that the efficiency is thereby very small, while on many fields it is injurious to the sand of the oil-bearing layer. Periodical flowing often occurs with rising mixtures of gas and liquid. The phenomenon can be explained if it is accepted that two conditions are possible in the mixture; namely, the foam condition and the mist condition. If there is no stabilizer in the liquid, the foam condition can exist only when the liquid forms a greater portion of the volume than the gas. The mist condition, on the other hand, can exist only when the liquid occupies a smaller part of the volume than the gas. The foam condition occurs when there are gas bubbles in the liquid mass, while in the mist condition drops of liquid are disseminated in a gas-filled space. For sake of simplicity, it has been assumed that the mist condition prevails when 50 per cent. or more of the volume is occupied by gas, while with less than 50 per cent. gas the foam condition will arise. For distilled water and for oils which do not tend to form stable foams this is probably approximately true. If this does not hold good, however, two cases are possible: (1) The fields of the two conditions overlap or (2) they do not meet. If the fields of the conditions overlap there is an intermediate field where either of the two conditions can exist, depending on the history of the mixture. Suppose the foam condition prevails first and the gas

Jan 1, 1931

By V. Koump, R. H. Tien, W. J. Kim

This paper presents an approximate solution of the problem of freezing of a binary alloy. he alloy is in the form of a one-dimensional slab of finite thickness. The surface temperature of the slab is assumed to be constant and lower than the solidus (or eutectic) temperature. The densities of the liquid and the solid are assumed to be equal. For a given binary alloy system, initial concentration of solute and surface temperature, the solution yields a) the temperature distribution in the solid skin, b) the temperature, concentration, and solid fraction distribution within the solid-liquid region, and c) the positions of the liquidus and the solidus (or eutectic) fronts as a function of time. The results of calculation for Fe-C and Fe-P systems are presented. In this investigation we are considering the problem of solidification of a binary alloy. The alloy is in the form of a one-dimensional slab of finite thickness. The molten alloy is initially at liquidus temperature. At time zero the surface of the slab is reduced to a temperature T, < Te,, where Te, is the solidus (or eutectic) temperature and T, is a constant. The densities of solid and liquid alloys are assumed to be equal and independent of temperature and composition. A qualitative picture of solidification of an alloy, under these conditions, is illustrated in Fig. 1. During the initial stage of solidification, before liquidus front reaches the center of the slab, freezing proceeds by propagation of two isothermal fronts, the liquidus front and the solidus (or eutectic) front. The fraction of solid at the liquidus front is zero; the fraction of solid at the solidus front is unity, The solid fraction and the temperature distribution between the two fronts and the width of the solid-liquid region change with time. During the later stage of freezing, after the liquidus front reaches the center of the slab, the liquidus front disappears. The solid fraction and the temperature at the center of the slab, as well as throughout the solid-liquid region, are now changing with time. The solidification is completed when the fraction of solid at the center of the slab reaches unity. In solution of this problem we seek to determine a) the temperature distribution in the solid, b) temperature, concentration,

Jan 1, 1968

By N. E. Holden, R. R. Goodrich

TheRe is a small area about Murray where bedded gold quartz veins occur in Prichard slate. The ore taken from the upper levels, during the early days, was free milling and was treated by stamp milling and amalgamation. There was likewise a considerable placer working. The report is current that tungsten (scheelite) was encountered, which interfered with the amalgamation in the stamp mills and which, in placering, collected in the riffles in the sluice boxes and clogged them. Consequently, in the quartz mines, the scheelite, when encountered, was rejected, being thrown into the waste, sometimes inside the mine and at other times outside on the dump. The free surface ores became worked out and as the ore in depth became pyritic and rebellious to amalgamation the mines closed down. Last spring tungsten ore brought a high price, near $80 per unit, 60 per cent. W03 and up. This so stimulated the output of tungsten ore that old dumps were explored and waste stored in the mines was gone over. Tungsten was likewise mined from virgin ground. So the district produced quite heavily for a time. The condition now is different. The price is not so high, about $20 per unit WO3, which makes profits questionable when mining in new ground. The accumulations from early day mining have been exhausted and the output has greatly declined. The Golden Chest mine was the heaviest producer of tungsten. The months of June and July were spent at this mine studying the problem. Since the mine had produced both gold and tungsten, we looked forward to the problem of recovering both from what might be called a gold-tungsten ore. A study of the Golden Chest vein showed this was not to be the case. While gold ore and tungsten ore come from the same vein, the tungsten ore is confined to a more or less disturbed or distorted portion

Jan 1, 1918

September 28, 1915. The Nominating Committee of the American Institute of Mining Engineers has the honor to present the following nominations for officers of the Institute to be voted for at the 1915 Annual Meeting: For President: L. D. Ricketts District 0 For Vice-Presidents: Karl Eilers District 0 James MacNaughton District 4 For Directors: Thomas B. Stearns District 7 Charles F. Rand District 0 Charles W. Goodale District 5 Edwin Ludlow District 2 George D. Barron District 0 F. W. BRADLEY, Chairman.

Jan 11, 1915

By Kenzo Murao, Sei Nakao

HISTORY OF ASHIO SMELTER The Ashio copper mine, which formed the main part of Furukawa mining industry, is located inland of Kanto area, and is known as the oldest copper mine of Japan. The mining started even since 1610, and Mr. Furukawa began management in 1877. Afterwards, within a short period, the mine became to have the highest productivity in the Far East. The total quantity of mined copper reached approximately more than 800 thousand tons. The mother rock of the ore deposit in Ashio was rhyolite, and was formed of sissurefulling and irregular clod that was called Kajika deposit. The lode was nzrrow of 6 to 7cm. The mineral was formed mainly of chalcopyrite, including also pyrite, pyrrhotite, and arsenopyrite that were not favorable. After the founding of the copper mine, the Ashio smelter started the operation of Mabuki process as the beginning in 1611, and subsequently adopted the processes of the blast furnace, reverberatory furnace, and flash smelting furnace of the present use. As indicated above, the copper ore of Ashio mine included arsenic. For the purpose to remove it, the operation of the arsenic trioxide production using MacDougall&apos;s multiple hearth roaster was started in 1918, and it maintained the status of having the most qualified technique within the country. However, as the completeness in the disposition of anti-pollution and safety had been requested in those years, we studied and developed a unique equipment in 1970. It excludes the heavy metals especially arsenic and copper from the waste water of sulfuric acid process of Flash Smelter&apos;s exhaust gas.

Jan 1, 1976

By R. G. Powell, R. Schuhmann, E. J. Michal

Liquidus surfaces in the ternary system FeO-Fe2O3-SiO2, were determined from 1250&apos; to 1450°C by the procedure of equilibrating small samples in platinum crucibles, quenching, and microscopic examination. The experimental results were combined with previously published information to construct a ternary diagram for the system showing the entire temperature-composition range of stability of iron silicate slags. Metallurgical applications of the diagram, especially in copper smelting, are discussed briefly. IRON oxides are almost unique among the common oxide constituents of metallurgical slags in that the iron occurs in two different states of oxidation, ferrous and ferric. Moreover, in liquid slags the degree of oxidation of the iron is readily changed by reactions of the slags with oxidizing agents or reducing agents. This behavior of iron oxides in slags accounts, for example, for the effective transfer of large quantities of oxygen through slag layers in open hearth steelmaking. In this process, oxygen supplied by reactions at the gas-slag interface is dissolved in the slag with the oxidation of ferrous iron to ferric. Ferric oxide is transported across the slag layer by convection, and at the slag-metal interface the oxygen reacts with liquid metal while the ferric iron is reduced back to the ferrous state. Another group of processes in which variation in degree of oxidation of iron has great practical importance is in copper smelting. In matte smelting and converting, such large proportions of the iron are oxidized to the ferric state that problems are encountered in preventing or controlling the formation of solid magnetite. The ferrous-ferric relationship also affects the attack of iron oxides on high-SiO2 refractories, which appears to be most severe under reducing conditions for which ferrous iron predominates. Darken and Gurry&apos; determined the chemical properties and phase equilibria of pure iron oxide slags. Their data show that iron oxide melts can have compositions ranging almost all the way from FeO to Fe2O3. The melts of lowest oxygen contents, which exist in equilibrium with metallic iron, approach ferrous oxide in composition but still have a small percentage of ferric oxide. The melts of highest oxygen contents, which have oxygen dissociation pressures of 1 atm, are above magnetite in oxygen content, with over two-thirds of the iron in the ferric state. The previously established phase diagrams for silicate slag systems all show FeO as the iron oxide component. However, Bowen and Schairer? who determined the FeO-SiO2 diagram and many of the other diagrams used by slag chemists, have been careful to point out that their systems always contained both ferrous and ferric iron. Thus, their data are for limiting mixtures with minimum contents of ferric iron, obtained by melting and equilibration in iron crucibles. Under these conditions, the Fe2O3 percentages found by analysis were small enough to justify simplification of the published phase diagrams by calculating the Fe2O3 to equivalent FeO and ignoring Fe2O3 as an additional component. On the basis of experimental measurements of melting points of iron oxides on silica in the presence of various gas mixtures, Darken3 worked out phase diagrams for the Fe-Si-0 system which show the important phase equilibria in terms of temperature and gas composition. This study clarified many aspects of the application of the phase rule to the FeO-Fe2Oa-SiO2 system and was an important basing

Jan 1, 1954

By H. Ries

Introduction BODIES of pyritic ore in schistose rocks have long been known in different parts of the world. The several occurrences resemble each other in being usually of more or less lenticular shape, inclosed in walls of schist or gneiss, and carrying pyrite, chalcopyrite, and pyrrhotite in varying proportions, as the chief ore minerals. The deposits differ, however, in that sometimes one, sometimes another, of the three sulphides mentioned may predominate. The orebodies in general are more or less closely conformable with the schistosity of the wall rocks, although in cases this may not hold true. The boundaries may or may not be sharp, but in general are fairly distinct. The lenses vary in size, may occur singly, or in groups; in the latter case they may be in line, overlapping, or occasionally parallel. Pinching and swelling of individual lenses is not uncommon. The genesis of these pyritic bodies has provoked much discussion, and they have been variously classed as sedimentary, igneous intrusions, hydrothermal replacements or impregnations, etc. Indeed, in some cases different geologists have most positively assigned widely diverse origins to the same deposit, as in the case of Rio Tinto 1 and Rammelsberg.2 It is true that in the light of modern criteria, we have been able in a few cases to decipher clearly the process of origin and so there seems no doubt now regarding the genesis of the deposits at Rio Tinto, Spain;3 Rammelsberg, Germany ;4 Ducktown, Tenn.;5 southwestern Virginia;6

Jan 8, 1917

By Guy Crane

I. INTRODUCTION THE geology of the Tintic mining district, fully treated, would occupy an elaborate monograph. This less comprehensive paper is devoted primarily to the occurrence and origin of the orebodies of the district, while space is given to those phases of the general geology only which seem necessary to a proper setting of such a discussion. The first geological report on the Tintic district to be issued was that by Tower and Smith, published in 1899, in the form of a paper in Part III of the Nineteenth Annual Report of the U. S. Geological Survey, and also as Folio No. 65, Geologic Atlas of the United States. About four years ago a second investigation was begun by Waldemar Lindgren and G. F. Loughlin, of the U. S. Geological Survey. With the exception of a paper on the oxidized zinc ores of the Tintic district by Mr. Loughlin, the results of their work are still unpublished. The writer&apos;s acquaintance with the district began in the fall, of 1913, and has extended over a period of about two years.

Jan 10, 1915

By Nicholas J. Grant, Olaf Troili, John Chipman

D. C. Hilty (Union Carbide & Carbon Research Laboratories, Niagara Falls, N. Y.)—How does this effect of silica compare with the effect of silica in combining with the lime in the slag to reduce the activity of CaO, thereby affecting the first equation? John Chipman(authors&apos; reply)-—That is the object of showing this effect for slags of two different basicities. In the more basic, the silica is more firmly tied up in the slag and is less easily reduced. It is therefore less able to interfere with desulphurization. The important point is that silica is acting in two ways. Of course it is an acid and as an acid it ties up lime and in tying

Jan 1, 1952

By Northcutt Ely

International developments affecting foreign in- vestments in 1960-61 were many, varying from region to region and differing with respect to various categories of investments. Total value of U.S. private investment abroad in 1960 was approximately $32.7 billion, an increase of $2.9 billion over 1959. Production and distribution of mineral resources was, by a sizeable margin, the most important function of American capital working in foreign countries in 1960. Investment in mining or petroleum interests totaled approximately $14 billion, or 42% of all direct foreign investment. In- vestments by industry for 1960 were as follows: Petroleum-10.9 billions, Mining-3.0 billions, Manufacturing-11.2 billions, Utilities-2.5 billions, other-5.1 billions. American investors found Canada and Latin America to be most desirable in 1960 with the greatest percentage of American capital in all areas centered in the petroleum and mining industries. The areal breakdown of total American investments is as follows: Canada-$11.2 billions, Latin America-$8.4 billions, Western Europe-$6.6 billions, Middle East-$1.2 billions, Far East-$1.2 billions, Africa-$.9 billions, other areas-$3.2 billions.

Jan 3, 1962

By Charles S. Barrett, Hermann F. Kaiser, Robert F. Mehl

THE copper-silver system presents several points of special interest in the study of segregate structures. The system is simple eutectic, with limited solid solutions terminal with the pure component metals. The extent of solid solubility decreases with decreasing temperature for both the copper-rich and the silver-rich alloys, thus offering a possibility for the formation of Widmanstätten figures and also a possibility for aging after quenching. In contrast to the structures studied previously the structures in this system are unique in their origin, for one terminal solid solution will precipitate the other, and vice versa. In most of the other systems for which crystallographic data on the precipitation (or transformation) process are available, either intermetallic compounds or intermediate phases partake in the decomposition process; the absence of such phases thus distinguishes this system. The lattice structures of the two solid solutions are identical in type, differing in lattice spacing by approximately 10 per cent; because of this it seems difficult if not impossible to predict on the basis of present theory either the outward form of the precipitate or the lattice orientation relationships between matrix and precipitate. The eutectic temperature in the copper-silver system1 is 779° C. At this temperature copper dissolves 4.3 atomic per cent (7.0 weight per

Jan 1, 1935

By T. L. McCall

The late Walter Herd1 in 1929 gave a full description of past and present conditions in No. 2 mine, Springhill, Nova Scotia, developed theories regarding the cause of these bumps and made certain suggestions regarding possible methods of future development. Recapitulating briefly from Mr. Herd&apos;s paper, the seam is bituminous coal, averages 9 ft. in thickness and has a well defined parting containing fusain about 14 in. from the roof. This roof coal is somewhat stronger than the rest of the seam and has a tendency to cling to the roof. The pitch of the seam where it is now being worked is about 20". The first manifestations of bumps began when the room and pillar workings had reached a depth of cover of 1900 ft. and under continuously increasing depth of cover these bumps increased to such an extent, both in number and severity, that in the year 1924 it became apparent that some change in the system of extraction was necessary. After closely studying all the factors involved and benefiting largely by valuable outside advice obtained by the Provincial Department of Mines of Nova Scotia,2 the system of working was changed from room and pillar to longwall retreating. Mr. Herd&apos;s paper described in detail three remarkable bumps in the year 1928 in April, July and October that affected the 5700-ft. and 5900-ft. East levels, the last bump being so severe both in intensity and in extent of damage done that this district was abandoned. The longwall workings to the west of the slope had been stopped in the year 1926 owing to an inbreak of water, coming from the flooded waste of No. 3 seam lying some 400 ft. vertically overhead. This inflow was not excessive, but a large quantity of water being impounded in the old workings it was considered advisable to take the prudent course and not incur the risk of possibly increasing the flow by further working. This district has remained idle ever since.

Jan 1, 1934