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By B. R. Palmer, M. C. Fuerstenau

Oxide and silicates respond to flotation with a large number of anionic collectors. These include carboxylates (fatty acids), sulfonates, alkyl sulfates, and certain chelating agents. In contrast to sulfide mineral flotation, relatively long-chained collectors (generally longer than 10 carbons) are required to effect flotation of this group of minerals. The structural formulas of these various anionic collectors are presented in Table 1. Formulas and solubilities of various fatty acids are presented in Table 2. These solubilities are those of the dissolved and undissociated species of the acid, e.g. oleic acid, HOl(aq). Of the compounds listed, oleic acid and abietic acid, which IS a major constituent of talloel, are used most commonly in commercial applications. The usage of these two collectors is related to cost and effectiveness. In addition to their high molecular weights, oleic acid contains a double bond in its hydrocarbon chain, while abietic acid is comprised of aromatic rings containing double bonds. The presence of double bonds increases solubility significantly over that of saturated homologues. Stability of metal-collectors assumes a most significant role in these systems, and the solubility products of various metal carboxylates and sulfonates are listed in Tables 3, 4 and 5. In addition to these properties, strength of the acids of these various anionic collectors is also important. The carboxylic and hydroxamic acids are weak acids whereas sulfonic and alkyl sulfuric acids are strong acids. All of the carboxylic acids fall in the range of pK = 4.7 ± 0.5 ([2]); the pK of hydroxamic acid is around 9 ([3]); and the pK of sulfonic acid is about 1.5 ([4]).

Jan 1, 1976

THE great subject of interest in American affairs during February was the consideration of the proposed soldier bonus. This proposal was based upon the idea that, because most of the workers of the United States had enjoyed high wages during war, the soldiers were entitled to "adjusted compensa-tion" in order to equalize things. It overlooked the fact that the soldiers, themselves, had the opportunity to enjoy high wages in 1919 and 1920, when rates were highest. Apart from this, the whole project was founded on fallacies and involved what would be nothing less than economic crime. Although it looked as if the measure were destined to be railroaded through Congress, so great a storm of protest was pelted upon Congress that the present outlook is that the whole project will be abandoned. There was probably some increase in the physical volume of business during February. A rise in prices for agricultural products assisted the farmers mate-rially. These developments, however, are not to be construed as presaging any general upward movement. On the contrary, the current year is to be contem-plated as one of serious labor troubles, following inevit-able reductions of wages. These began in February in the form of an extensive strike in the cotton textile industry of New England, accompanied by some rioting in Rhode Island. The coal miners have had numerous conferences, without coming to any encouraging results, and the stage appears to be fully set for a general strike beginning Apr. 1. About the only question now is whether this will comprise both the bituminous and anthracite miners. If the latter refuse to go out, no serious shortage of coal is anticipated, the belief being that the existing stocks together with the output of the non-union mines will supply the demand, which is sub-normal even now. In the metal industries, lead and zinc were dull but stable. The weakening tendency in iron and steel that was manifest during January appeared to be checked, at least temporarily. Copper was charac-terized by a distinct weakness and a considerable decline in the market. This downward movement was inspired by the news during January that several of the important mining companies were taking steps to resume production. During February the demand for copper, both foreign and domestic, was poor.

Jan 3, 1922

By Eric Jette

IN order to control a chemical process by other than empirical, rule of thumb methods, two types of knowledge concerning the reactions involved must be available: (1) the thermodynamics of the reactions, and (2), by no means less important for efficient operation, the mechanisms and kinetics of the reactions. Information on the thermodynamic side enables the operator to decide upon initial and final conditions, whether heat must be .added or removed from the system, whether the reactions proceed farthest in the desired direction at high pressure or low, etc. Knowledge of the mechanisms involves the determination of the individual steps by which an initial set of reactants, under given conditions, proceed to give the desired final products and kinetic studies upon which the mechanisms are based give the speed at which each of these reactions or steps take place. Thus thermodynamic studies of a 'reaction enable the operator to control the direction and extent to which the reaction can proceed, while kinetic studies enable him to control rates and thus the time' efficiency of the operations. The thermodynamics set the limit to which the reacting system approaches; the kinetics tell how fast the system actually approaches this limit. The two types of information are complementary and not antagonistic even though in discussing the mechanism the introduction of thermodynamics is entirely needless and generally of no assistance, while in thermodynamic studies mechanism need not even be mentioned.

Jan 1, 1931

By E. S. Grumell

THE correct sampling of coal and coke is becoming important to an ever increasing number of producers and consumers. This, therefore, may be an opportune moment to examine where we stand with regard to existing and proposed methods. In this paper an attempt will be made to review, as briefly as possible, some of the considerable amount of painstaking research which has been done in the last 10 years, and which has unquestionably led to a much better understanding of the subject. In so doing we shall try, on the one hand, to make clear where substantial progress has been made, and on the other hand, to draw attention to points that require further investigation. The paper is divided into sections in order to emphasize the major divisions of the subject; further, in order to retain this emphasis, detailed consideration of some of the points has been relegated to appendixes. No attempt has been made to give a complete survey of the literature, as this has already been done by L. A. Bushell.2 The following abbrevia-tions will be used: A.E., average error; P.E., probable error; S.W.R., size-weight ratio; B.S.I., British Standards Institution.

Jan 1, 1939

By A. R. Denison

The Permian Basin as it appears in the title of this article refers to three rather widely separated areas of production. It includes what are commonly known as the "Panhandle" fields of the northwest part of Texas; the West Texas fields, in the southwest part of Texas; and the New Mexico fields, in the southeast corner of New Mexico. These three areas are all included in a single province and produce the majority of their oil from limestones or dolomites of Permian age. The manner of accumulation of oil in the three areas is somewhat diverse. In the Panhandle, production is found on the flanks of an enormous structural ridge, the core of which is granite. In southwest Texas and New Mexico oil is produced from both gentle and steep folds and from lenticular areas of porosity. Production in Texas During 1927 Texas produced a total of 216,306,000 bbl. of oil of which the Permian Basin contributed 89,797,000 bbl., or 42 per cent. During 1928, Texas produced 255,021,000 bbl. of oil of which the Permian Basin contributed 145,955,000 bbl., or 57 per cent. The increase in total production is entirely due to the West Texas fields. All other districts in Texas declined during the year while the west Texas fields registered an increase of more than 71,000,000 bbl. West Texas daily average production increased from 260,752 bbl, at the beginning of 1928 to a maximum of 406,318 bbl. per day the first week in May. Due to prora-tion agreements, the production was held at a fairly constant level around 340,000 bbl. during the remainder of the year, having 345,660 bbl. the last week in December. Daily average production of the Panhandle fields decreased from 80,178 bbl. at the beginning of the year to 59,025 bbl. at the close of the year. The combined daily average production of the Panhandle and West Texas fields at the beginning of the year was 341,138 bbl. and at the close of the year was 405,408 barrels. Fig. 1 gives a comparison of the production in the Permian Basin in relation to the production of the entire state. It is clearly shown that

Jan 1, 1929

By A. A. Jr. Smith, J. S. Smart

Numerous investigations of the effects of the various impurities common to commercial coppers have been published, and the data have found wide use in industry. Naturally, emphasis has been placed on the oxygen-bearing coppers of the tough-pitch variety, but need is now evident for data covering the oxygen-free condition as well. Furthermore, relatively few of the important reactions between oxygen and the various impurities are well understood, and often the data at hand are not applicable to the low concentrations encountered in commercial coppers. This paper presents the changes in conductivity and softening temperature derived from individual additions of the group VIII triad, iron, cobalt and nickel, to high-purity copper, and constitutes a portion of the copper-research program being conducted at the Central Research Laboratory of the American Smelting and Refining Co. The method of preparation of high-purity copper and its alloys in either the oxygen-free or oxygen-bearing form has been described previous1y.l The purity of this material, and the methods developed to produce it, provide the means for direct investigation of the very low concentration range in which the various impurities generally exist in commercial coppers. The usual necessity for extrapolation to this range using the results obtained from higher concentrations, and the interfering effects of extraneous impurities, are thus simultaneously circumvented. Since previously published data have adequately presented the effects of higher concentrations of iron, cobalt and nickel, the present investigation has been confined to the composition range o to 0.05 per cent. All alloys were initially prepared in the form of oxygen-free continuous cast rod, the weighed alloying additions in suitable form being charged with the pure copper to the continuous casting crucible. The best of the available high-purity alloying materials were used, and spectrographic analyses confirmed the absence of interfering elements from the alloys formed. Each series was compounded in the direction of increasing concentration, starting with pure copper in a new crucible and finishing with the 0.05 per cent alloy. Composition was closely controlled by adding the alloying element in the form of a carefully compounded and analyzed master alloy rendered uniform by continuous casting. The accuracy of this method of synihesis was proved by chemical analysis of the more concentrated alloys, and, accordingly, there is every reason to credit the stated composition of the very dilute alloys in the range where chemical analysis becomes highly uncertain. Oxygen-free samples for measurements of conductivity and softening temperature Were obtained by drawing the continuous cast rod to wire of 0.08I-in. diameter. employing a number of intermediate anneals to refine the grain structure. The

Jan 1, 1942

By Ralph E. Davis, Lyon F. Terry

The rapid expansion of the natural gas industry in this country during the past three or four years has necessitated the construction of a number of long and comparatively large diameter high-pressure pipe lines This period of expansion and construction is still at high tide, and the current year will doubtless surpass all prior years in mileage and capacity of gas line installation. The fundamental economics of the business of long-distsrier transportation of natural gas may be briefly and simply stated, although most careful consideration must be given the actual determination and integration of the several more important factors which determine the ultimate success or failure of such a project. Reduced to its simplest form, a sound natural gas transportation project requires: 1. A competent source of gas, where the combination of quantity of gas available, cost of production, and longevity meet the given requirements. 2. A market, reasonably certain to endure in the face of any probable competition, of satisfactory size and price, and having a sufficiently favorable load factor. 3. A cost of installation of pipe line systen and an operating cost such as will, with honest and reasonably efficient management, afford a net operating return sufficient to attract the necessary capital required. In a11 new projects of this kind it is necessary that thehe three cssentials to ultimate success be assured. Hence the necessity of competent surveys of gas supply, and of market, both industrial and domestic. The prudent engineer will allow for "factors of safety" in reaching his conclusions just as he would in the design of a bridge. This paper deals primarily with but one of the major considerations enumerated above, I. e, the economic design of the pipe line system. The "pipe line system" will be considered to include (1) the pipe Iine, and (2) a series of compressor plants along the pipe line for maintaining

Jan 1, 1929

By Simon D. Strauss

INTRODUCTION The changes in ownership, management, and operation of the non-fuel minerals industry since the Second World War have been dramatic. World-leading enterprises have lost their identity; host countries have taken over operations from multi-national firms; marketing practices have been drastically altered - and yet the world industry is supplying minerals on a scale far greater than had been anticipated in projections made at mid-century. The world's known mineral resources have been enormously expanded, despite the doom sayers who for decades have been predicting that depletion of non-renewable resources would impose limits to growth. PALEY REPORT One can set the stage by reviewing how the minerals outlook was regarded in a thoughtful and comprehensive analysis made in the years 1950 and 1951. During the War years, President Harry Truman of the United States had come to appreciate the decisive role played by minerals resources through his chairmanship as a U.S Senator of a committee that investigated the procurement and allocation of natural resources. In 1950, in the Cold War era that resulted in actual military conflict in Korea, he appointed a prestigious five-man commission to study the problems of Materials Policy over the following quarter century. Their findings, published in five impressive volumes in early 1952, became known as the Paley report. The text was prepared by expert scientists and economists who spent 18 months assembling statistics, making projections of future demand, and interviewing leaders in industry, academia, and government. [ ] The Commission had correctly foreseen that aluminum would replace copper as the largest volume non-ferrous metal, but it had fallen short of reality by a wide margin indeed for all three materials. Even though the Commission's expectations for growth proved to be extremely understated, it had concluded its report with grave foreboding about the effect of its estimates of demand in relation to supply, as follows: "Consumption of almost all materials is expanding at compound rates and is thus pressing harder and harder against resources which, whatever else they may be doing, are not similarly expanding. This materials problem is thus not the kind of 'shortage' problem, local and transient, which in the past has found its solution in price changes which have brought supply and demand back into balance. The terms of the materials problem we face today are larger and more pervasive." With respect to some minerals, the Paley Report expressed scepticism that, in fact, supplies would be forthcoming regardless of price. Because the Paley demand forecasts understated the actual growth in demand for virtually every mineral, one could logically have expected frequent and protracted shortages in the years since 1950.

Jan 1, 1985

E. E. THUM,* Salt Lake City, Utah (written discussion?).-While the present paper is confined exclusively to the microstructure of fusion welds, it may be of interest to draw attention to certain appearances existing in resistance welds such as spot or butt-welded joints produced by the Thomson process. For instance, a butt weld between two pieces of carbon tool steel (carbon about 0.90 per cent.) will show concentric ellipsoids of the various materials from pearlite to martensite. The surfaces of demarcation are quite well defined, the center of the ellipsoid being at the intersection of the axis of the piece and the plane of the weld. Often these unannealed welds show a troostitic center; evidently this core was not quenched as rapidly as the surrounding shell. Such specimens are beautiful samples for instruction purposes. An annealed butt weld of this kind will show a very well defined central ellipsoid of decarburized, materials. It is interesting to consider the reason why this change takes place. It must be understood that the heat is on the metal for a very short time, possibly 30 sec. It is therefore evident that the decarburization, or migration, of the carbon takes place with extreme rapidity. Since no blowholes are evident in a well-made butt weld, the deoxidizing air and the products of combustion must migrate with the highest speed; second, the carbon might migrate back into the stock; or, last, a large proportion of the pearlite may be extruded with the hot metal, which forms a fin at the plane of weld. Examining these possibilities in detail, it is not probable that such deep-seated decarburization, extending with maximum effect to the very center of a 2-in. round bar, is done by reaction with the oxygen of the air. This would postulate entrance of oxygen and egress of carbon oxides in large quantity without leaving behind traces in the form of oxides or

Jan 5, 1919

By J. D. Wright

INTRODUCTION The Endako deposit was first explored in 1926, but development waited until the early nineteen sixties. It first came under the control of Placer Development in 1963, and early in 1964 a decision to bring it into production was reached. The deposit is located near the geographic center of British Columbia, and is served by an east-west communication system including a paved highway, mainline railway and good telephone, teletype, and computer facilities. The plant area is shown in Figure 1. The operation is known as the Endako Mines Division of Canex Placer Limited of Vancouver. First production was achieved in June, 1965, at a nominal rate of 10,000 tons per day, but it soon was closer to 15,000 tons per day. In 1967, two new grinding and flotation, sections brought capacity to the present rate of approximately 27,000 tons per day. With mill heads of around 0.15 percent MoS2, production is about 14,000,000 pounds of molybdenum per year. A flowsheet of the operation is given in Figure 2. A legend for this flowsheet is given in Table 1. Published ore reserves are estimated at 214,500,000 tons at an average grade of 0.143 percent MoS2. PRIMARY CRUSHING The 85 or 100-ton haulage trucks dump over a grizzly into a 42 inch x 65 inch C.A.C. (Canadian Allis Chalmers) gyratory crusher. The

Jan 1, 1976

By H. W. Russell, Paul D. MILLER

IT is known that austenitic chromium-nickel steels that have free carbide in the grain boundaries are subject to intergranular corrosion. It is difficult to detect such a susceptible condition in a fabricated article because present test methods require a sample section for examination and in most cases this is difficult to obtain. The question of the nature and prevention of intergranular corrosion in austenitic stainless steels have been ably discussed by Bain and co-workers1-3 and by other investigators.4-10 The present methods of study subject samples to corrosive conditions in such reagents as the Strauss solution, a. mixture of copper sulphate and sulphuric acid. Such tests usually require at least 72 hr. to run. Various methods of measuring the degree of sensitization have been employed, such as the measurement of electrical resistivity, magnetic measurements, measurement of the degree of cracking produced on bending over a mandrel, and microscopic studies. The detection of carbides at the grain boundaries by metallographic polishing and etching methods is tedious and requires a skilled operator. A recent report on such methods of carbide detection is given by the American Society for Testing Materials Subcommittee VI of Committee A-10 11 and by Arness.12 The present investigation was undertaken to develop a simple test procedure for detecting carbide precipitation or susceptibility to intergranular corrosion. The test is designed for use in the plant and for the testing of fabricated structures. Carbide precipitation, the factor leading to susceptibility to corrosion, is produced by heating the alloy in the temperature range 800° to 1600°F., as in welding, in improper annealing or in service where such temperatures are met. The connection between such precipitation and susceptibility to corrosion has been thoroughly discussed, as has been the use of stabilizing addition elements to prevent precipitation. EXPERIMENTAL METHOD A small area of the steel under test is subjected to an anodic treatment in a cell that can be clamped onto a sample or an actual structure. The cell and electrical circuit used are illustrated in Fig. I. The cell C is lead, joined to the steel plate D and insulated from it by a short piece of rubber tubing E. The cell is forced tightly against the steel plate by a spring or clamping device. The seal formed by the rubber against the steel plate is sufficient to retain the liquid bath inside the cell. The spot treated can be made any shape desired, depending on the shape of the rubber gasket. The cell illustrated polishes a circular spot about 3/8-in. diameter. The bath consists of 60 per cent (by weight) sulphuric acid to which is added 5 ml. per liter of Glycyrrhiza extract (U.S.P.). The cell requires about 2 to 2.5

Jan 1, 1941

By T. D. Murphy

The element silicon, with its usual partner, oxygen, plays the same role on this planet relative to inorganic materials as carbon and hydrogen play with respect to living organisms. The crystallographic structure of silicon dioxide (SiO,) consists of one atom of silicon well-nigh inseparably bonded to four contiguous atoms of oxygen, a gas of but slightly more than half its atomic weight, forming a three-dimensional network of SiO, tetrahedra (Dietz, 1968). This wispy arrangement is the fabric of the mineral quartz which is one of the harder, more abrasive, and chemically stable raw materials to be found in Mother Nature's cupboard. Most of us are vaguely familiar with the observation that nearly 60% of the lithosphere to an approximate depth of 10 miles is composed of these two elements, which proportion actually rises to about 75% if the atmosphere, hydrosphere, and biosphere are included (Parker, 1967). Elemental silicon is a brittle steel-gray metalloid with a density of 2.42 and does not occur in nature. In its limited commercial form, which is still brittle and metallic in appearance, its density drops to 2.33. It combines with oxygen to form the gaseous oxide SiO, or the solid dioxide SiO, (analogous to its congener carbon in CO and CO,); a tetrachloride SiCl, (analogous to CC1,); or, combining with oxygen and one or more metal ions, forms the largest rock-making family of all, the silicates. Further, next to the feldspars, quartz is the most abundant known mineral and, in some form or another, accounts for roughly 12% of surficial terrestrial rock. It is this so-called "free silica" to which your attention is chiefly directed in this chapter. In any such consideration of silica, its several crystalline phases with their attendant differing physical properties appear worthy of delineation. Alpha quartz is the only one of this interesting polymorphic family that is thermodynamically stable at normal pressures and temperatures up to about 573°C. The low phases of tridymite and cristobalite can exist in the so-called metastable state below 117°- 200°C but seldom occur in nature in these two different crystal forms (Sosman, 1965). Opaline silica, now considered by most researchers to be a variety of cristobalite, occurs in abundance and is the only exception. The three remaining polymorphs, keatite, coesite, and stishovite, also are metastable under ambient conditions. Keatite, however, is not known to occur naturally and has only been synthesized in the laboratory. The other two have been identified in submicron sizes and in microscopic amounts, occurring naturally as a result of high order shock-wave pressures generating quite elevated temperatures-such as might accompany the impact of a large meteorite on a hard sandstone terrain (Chao, et al., 1962). An intriguing characteristic of these silica minerals, and one which has very practical applications, is their extremely variable densities. The classic 2.65 specific gravity of alpha quartz drops to 2.20 in tridymite, cristobalite, and lechatelierite (natural silica glass), as well as in many man-made glasses of commerce which are merely noncrystalline or amorphous solids in the form of super-cooled liquids which can no longer change their shapes (Pauling, 1950). It rises again to 2.50 and 2.93 for keatite and coesite, respectively, and finally becomes a reported 4.35 for stishovite-nearly a 50% range in density for the known physical combinations that silica naturally assumes (Frondel, 1962; Konnert, et al., 1973; Pecora, 1960).

Jan 1, 1975

By R. D. Pehlke, J. F. Elliott

The equilibrium pressure of nitrogen gas over pure silicon metal and silicon nitride has been measured in the temperature range 1400° to 1700°C. From the experimental data, the standard free energies and enthalpies of formation of Si3N4(a) have been calculated as functions of temperature over the above temperature range. Utilizing data in the literature and the results of this investigation, the specific heat, molar enthalpy, molar entropy, standard enthalpy of fornation, and standard free energy of fornation are estimated for the temperature range 298° to 1400°C. THE high-temperature thermodynamic properties of many metallic nitrides are not well established at present. This is a serious deficiency because nitrogen and nitride-forming metals are important alloying additions to steels, and knowledge of the interaction between nitrogen and these elements is essential to a better understanding of the behavior of steels. Metallic nitrides also are used as refractory materials. Consequently, the investigation reported here was undertaken to provide more complete information on the standard entropy and free energy of formation of silicon nitride. The experimental technique provided a direct measurement of the equilibrium pressure of nitrogen gas in the range of 1413 to 1700°C for the reaction: 3 Si(1) + 2N2 (g) = Si3N4 (a) [ 1 ] and below 1413oC for the reaction: 3Si(c) + 2N2(g) = Si3N4(a) [2] APPARATUS The experimental system consisted of a crucible assembly, a reaction chamber, and a gas supply and vacuum system. The Crucible Assembly which contained the equilibration specimen and molybdenum radiation shields with a susceptor for induction heating is shown in Fig. 1. Two covered, high-purity alumina crucibles, one nested within the other, contained the susceptor, shields and specimen. Central openings in the upper shield and crucible covers permitted on optical pyrometer to be sighted into the central cavity of the specimen. The specimen itself was a 5/8 OD by 1-in.

Jan 1, 1960

By A. H. Lindley, R. Shorr, Frazier M. Stewart, F. Crerie

The mineral industry, so important to industrial development, faces a major challenge in creating the most effective financial structure to provide funds essential for seeking, evaluating, developing, and extracting minerals. The acquisition of funds for mineral development and plant erection do not differ greatly from fund-raising in nonmineral ventures because risks are essentially comparable. High-risk exploration funds, however, are more difficult for the mineral industry to acquire. With the world's ever-increasing appetite for minerals, the internally generated cash of major oil and mining companies cannot be expected solely to maintain the world's mineral supply. The augmented costs, risks, and difficulties of exploration have been shared increasingly by the smaller independent operator and by private and public participation drilling programs within the petroleum industry over the past 30 years. Only recently has the mining industry awakened to the need for utilizing exploration and development funds derived from sources other than established mining and banking circles. Almost from its inception, the oil industry was forced to drill deep holes through overburden without the aid of a mineral "outcropping" which required geological, and in subsequent years, geophysical interpretation. The poorly financed, nontechnical prospector, who depended on a mineral outcrop, was not to play an important role in oil exploration as he did in mining. Because of the high cost of drilling and the demands for technical judgment to locate an exploration drill hole, corporate and sophisticated private funds generally financed oil discoveries. When external funds were subsequently required, these financially sophisticated explorers would turn to the banking community from which came numerous ingenious innovations, taking cognizance of existing tax laws. Like the oil explorer, the miner is now faced with probing below the surface, relying solely on regional geology and geophysical anomalies. The day is gone, for practical purposes, when the prospector discovers a deposit from a mineral outcrop. There is little doubt that the mining industry will now follow the course taken by the petroleum industry in acquiring external funds if it is to meet the future raw material requirements of the world. The oil industry has been able to attract bank funds more readily than the mining industry after a mineral discovery has been made because: (1) with few exceptions, an oil discovery can be placed into commercial production and will generate cash at much less expense and time than a mine; and (2) generally, costs of oil production, the value

Jan 1, 1976

By L. D. Dougan, J. V. N. Dorr

PaGE Geological Conditions......................... 78 Development of Elko Prince Property.................. 78 Prince Vein.............................. 79 Mining Practice.............*.'.......:...... SO Milling Practice............................ 84 Power Plant............................... 96 Construction Costs.......................... 97 Geological Conditions The Elko Prince mine is in the Gold Circle district, Nevada, about 155 miles (2. 4 km.) from the town of Midas, 55 miles (88.5 km.) west of Battle Mountain and 50 miles (8.5 km.) northeast of Golconda. The district is described by Emmons in U. S. Geological Survey Bulletin 408, 1910. Little was said of the Elko Prince, however, as only a small amount of work had then been completed. The geological structure of the region is simple. The oldest exposed formation, covering most of the area, is rhyolite, which has a light-colored devitrified groundmass enclosing phenocrysts of feldspar, quartz, and magnetite. It has been somewhat weathered and partially stained with oxide of iron. There are several outcrops of andesite which cut the rhyolite. The ore deposits occur as fissure veins, replacement veins, and sheeted zones. The Elko Prince vein is of the first type. The rhyolite near the veins is silicified, stained with oxide of iron, and, at some localities, replaced by ore, or is so permeated by metals as to be classed as ore. The vein filling consists chiefly of quartz, and the values consist entirely of gold and silver. Part of the gold exists as the native metal and part is associated with pyrite. Silver occurs free and as argentite in banded streaks through the vein. These veins trend in a northwesterly direction, with dips varying from 65' to vertical. Development of Elko Prince Property Gold was discovered in the district in the Fall of 1907, and a charac-stic rush followed The town of Midas was laid out and shortly had

Jan 1, 1919

By D. McLean

For many pu@oses uniform strength is desired over a long temperature range, coupled to a band of softness at the hot end for easy shaping. Various types of material fulfill such a requirement to different degrees, depending on the regularity of their atomic structure. In long-chain polymers and vitreous glasses the irregular structure leads to a steep temperature dependence of deformation resistance and the temperature band between the hard and brittle condition and the soft condition is only about 100 C. In crystals and especially metals the atomically regular structure leads to a much smaller sensitivity over a wide temperature band, thus approaching the ideal behavim. The reason for this insensitivity is that the regular crystalline structure deforms by the movement of dislocations and the elastic interactions of dislocations in- PLASTICS, GLASSES, AND CRYSTALS The ease or otherwise of deformation varies with temperature much more in some substances than in others. This is an important matter when service over a wide temperature range is needed, especially volve energies of several hundred electron volts compared with which the energy of thermal agitation is insignificant. However, temperature affects a metal's defmmation resistance through its influence on the annealing, m coarsening, of the three-dimensional dislocation network. This coarsening is a phenomenon very similar to grain growth and ideas about grain growth can be applied to it. Taking into account also the temperature dependence of the glide resistance from alloying additions, a reasonable account can be given of the overall effect of temperature on deformation strength and of stress and grain size on deformation rake. Special structures me described. some arising from these ideas and as yet untried, which may benefit metals and polymers but not ni-treous glasses. when in addition a degree of softness suitable for shaping is required at some stage. It would be nice if one could write on this subject in as much detail about plastics, glasses, and so forth, as about metals, but there has been far more study of this matter in metals than in other substances, which is one reason why most of this paper concerns metals. However, in Fig. 1 there are shown the deformation strengths of several nonmetallic substances as a function of temperature. In many tests the attempt at deformation caused breakage and the graph lines are then drawn dashed. Long-chain plastics, a glass, and a crystalline substance are included in Fig. 1. The notable feature of all of them is the sensitivity of the

Jan 1, 1969

By W. L. Honnold

Owing to a unique labor situation and other unusual circumstances, the mining methods of the Rand are hardly comparable with practice elsewhere. They are of considerable interest, however, and their importance is increased by the magnitude of the' industry with which they are identified, gold of $166,186,000 value, say 40 per cent. of the world's production, having been recovered from 25,701,954 tons of ore milled in 1914. In the sketchy remarks to follow, attention will first be drawn to some influential factors of general bearing, after which certain features at two mines of the writer's group will be referred to. It is hoped that engineers associated with similar or different conditions and practice will contribute to broaden the discussion. Before proceeding, recognition is due the generous assistance of C. E. Knecht and F. A. Unger. General Observations The principal mines are situated along the northern limit of an irregularly shaped geological basin, and extend in almost unbroken continuity over a distance of about 60 miles. As the boundaries are defined by vertical planes there are both "outcrop" and "deep-level" properties, all differing in size and in technical features. So much has been written in regard to the geology of the Rand that only a few pertinent features need here be recalled. Briefly, the ore deposits are profitably enriched portions of certain conglomerate beds or "reefs," rarely more than three, which are interposed between quartzite, or quartzite and slate, and lie so closely together that where more than one are mined they are dealt with as a working unit, although they may be stoped separately. Their collective extension is locally referred to as " the Reef." Along the outcrop the series dips more or less steeply, and in depth it flattehs, the latter tendency being most marked in the Far East Rand, where the bottom of the basin is nowhere so deep as to be inaccessible. Dikes and faults are a common feature throughout. They are,

Jan 1, 1916

By L. C. Graton

Although marked by numerous well-known attributes of its own, gold does not possess a kind and range of physical, chemical and geological characteristics wholly different and apart from those of other metals. Instead, it is merely one of the family of metals, with its individual and distinctive traits subordinate to the underlying family relationships and resemblances. The geologist concerned with pure science will pursue, therefore, the same general course and will examine the same broad kinds of facts and interrelations when studying the occurrence of gold as when studying that of copper or cadmium, or any other metal. But when we come to consider the use and economics of the metals, we discover that gold differs strikingly from all the others. Gold, in short, is unique, not by virtue of its inherent characteristics, but because of a peculiar and concerted psychological regard in which it is held. It will be evident, therefore, that the geologist who would deal with gold supply must give far greater weight to economic considerations than is required in his contacts with any other metal. If the geologist be called the scientist of occurrence, and the economist the scientist of use, the economic geologist stands as the necessary link between them. Perhaps it is in part because the economic geologist has made himself more familiar with the science of occurrence than with the science of use and has thus in some degree failed to bridge effectively the gap between the two fields, especially with regard to gold, that the usen1 of gold now appear to be in a state of general concern and even of alarm for the security and adequacy of future supplies. In the case of no other mineral commodity do the users, as a rule, trouble themselves greatly about the adequacy of supply except in so far as that may affect the price which they shall have to pay for the commodity. Oversupply, with resulting low price, they regard as a gift of good fortune. As to long-term undersupply, they are generally content to go ahead on faith, leaving the producer to discover as best he may the means for meeting their requirements or the inventor to find a substitute. But history has shown that for gold a different situation exists. While

Jan 1, 1931

W. P. Blake, Shullsburg, Wis.: I desire to express my admiration of Prof. Posepny's memoir, and particularly of the charming manner and spirit of the introduction. With respect to his mention of the ore-deposits of Missouri and Wisconsin, reference may be made to my paper presented at this meeting (Trans., xxii., 621)) showing the existence of dislocations and breaks in the bedding, and their apparent close relation with the localization of the ore-deposits as claimed by Dr. James G. Percival, and also so claimed by Dr. Jenney in his paper before us (Trans., xxii., 171). I have in my paper given reasons for believing that the zinc- and lead-ores in the strata above the compact Trenton limestones were formed by lateral secretion and concentration from above downwards, substantially as shown by Prof. J. D. Whitney, and not by the ascent of solutions through the fissures, as Prof. Posepny (p. 304) seems inclined to believe. In regard to the contemporaneity of the ore and the rocks, and in favor of a later introduction of ore through fault-fissures, Prof. Posepny (p. 310) cites the influence of these fissures. In my paper, already referred to, I have endeavored to show how faults may have influenced the deposition of ore without being themselves channels for the flow of mineral solutions, and how they may have caused the contemporaneous formation of metallic sulphides from sea-water in the body of a forming rock; the faulting fissure being formed at an early period in the foundation rocks, and probably continuing to be a plane of break and movement in the deposits of later formation.

Jan 1, 1894

By Earl Oliver

This paper is based on the formula that the petroleum industry is sick—find the cause, eliminate it, and the industry will get well. There is perhaps no difference of opinion that the cause is overproduction, actual or potential. But that, again, is a result rather than a cause. The problem is to study the influences that serve to keep production and consumption out of balance. Production control is a popular theme and a natural one at this time when the whole world is unstable; but production control in its popular sense means little more than the application of emergency measures while danger threatens. Economists differ as to the effectiveness of these, most of which are designed to alleviate and not to cure, but we assume there are none who question the wisdom of promoting conditions under which economic forces are permitted to operate freely in bringing about stable conditions. The petroleum industry suffers from two classes of economic ills that serve to promote overproduction; namely, those which are common to all industries and those which are peculiar to this industry. It is of the latter I wish to speak. Strange to say, government is responsible in large part for this latter class of ills that affect the petroleum industry and we are coming to recognize that only through the assistance of government can they be corrected. Instability of the petroleunl industry, in so far as human agency was involved, had its inception in 1875 when a Pennsylvania jurist, called upon to make a decision for which there was no precedent and fancying he noted some resemblance between the so-called fugitive nature of oil and gas and that of wild game, made mention of that resemblance. Other courts being impressed by the analogy enlarged upon it, and gradually fixed upon oil and gas a legal status in certain important respects similar to that of wild game. Although later the courts abandoned this analogy, certain practices that developed out of that early concept have continued to this day and are largely responsible for the industry's present plight. Thus, instead of ownership in place that is characteristic of private property generally, the law of capture was applied to oil and gas. Now, the rapid and wasteful depletion of game

Jan 1, 1932