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By J. L. Christie, W. R. Webster, R. S. Pratt

Since the delivery of our paper on Some Comparative Properties of Tough-pitch and Phosphorized Copper,1 a new brand known as "oxygen-free high-conductivity copper" (brand OFHC) has become available to consumers. It was thought desirable to make a comparison between the properties of this material and those of the materials covered by our original paper and its discussion. Preliminary tests had indicated some notable differences. A billet of oxygen-free high-conductivity copper was taken from regular production. A chemical analysis of the particular billet was not made, but the producer of the material has given as typical the analysis shown in Table 1. The

Jan 1, 1933

By Henry J. Welge

The approximate methods which are now in use for calculating oil displacement from reservoirs by gas-cycling or gravity-drainage at constant gas pressure, or by water flooding, make use of fundamental relationships derived by Leverett' and Buckley and Leverett.2 The mathematical equations needed are derived by applying Darcy's law to the flowing phases, and by material balance considerations. ln general, any treatment of this type gives. for any particular exploitation time considered, a plot of oil saturation against distance in the reser-voir. The oil recovery must then be obtained by integrating in some manner the area under the plot. A useful analytical method has been derived for computing the average saturation, and hence the oil recovery. Use of this method simplifies the calculations because it makes unnecessary any numerical integrations. and even the saturation distribution plots are not needed. A further advantage of the method is that knowledge of the relative permeabilities is required only for a limited and intermediate saturation range. In both the Buckley and Leverett method and the method discussed here, a linear sand section is assumed, and in the case of gas drive the gas pressure is assumed sufficiently constant both with respect to reservoir position and time so that changes in gas density. solubility, or reservoir volume factor are negligiklle. Thus, the exploitation contemplates oil displacement as by an immiscible phase. Examples are given to illustrate how the new method can be used. INTRODUCTION AND THEORETICAL BACKGROUND This paper treats a simplified method for computing oil recovery when the oil is displaced, from the reservoir sand by a fluid which, within the limits of accuracy desired, can be assumed to be incompressible and immiscible with the oil. The method makes use of two basic relations originally developed for the case of water displacing oil. However, the case of gas displacing oil saturated with gas at a constant (or nearly constant) pressure may also be considered a displacement by an immiscible fluid. This is possible for the reason that the concentration of the gas in the oil never changes if tile pressure is fixed. consequently, any additional free gas must remain undissolved in the oil, and so must act essentially as an immiscible phase. For convenience, the cape of gas drive will be considered first. Both of the two basic relations needed refer to a linear reservoir, or one which may be somewhat idealized so that a constant cross-section is exposed to fluid flow. Further, the displacing phase is injected at one end, or face; of the reservoir, while the produced fluids are understood to emerge at one point only. which is the opposite face of the reservoir. As indicated in Fig. 1, the reservoir may he inclined by some angle 8. The first of the required equations may be derived by applying Darcy's law to both displacing and displaced phases, and subtracting the two equations. The result for water drive has been given previously, as Equation (13) of the reference by

Jan 1, 1952

By Robert L. Bates

Definition An industrial mineral, says the Glossary of Geology, is "any rock, mineral, or other naturally occurring substance of economic value, exclusive of metallic ores, mineral fuels, and gemstones; one of the nonmetallics." Probably most geologists and engineers would accept this simple and straightforward definition, at least as a general statement. On analysis, however, certain anomalies crop up. For example, it may be considered arbitrary to include industrial diamond and corundum and to exclude their precious varieties, gem diamond and sapphire. So the present volume has a section on gems and gem materials, in spite of the definition. Another problem arises when we try to define precisely what is metallic and what is nonmetallic. Bauxite and ilmenite certainly qualify as metallic ores, but both are also raw materials of important nonmetallic substances; hence they are included in the book, A third anomaly is that, by common consent of geologists, engineers, mineral economists, and others concerned, the term industrial minerals may include not only rocks and minerals but also certain manufactured products like cement and lime, and even mixed groups of natural and artificial products, such as abrasives and refractories. Thus the central realm of the industrial minerals is clear enough, but its boundaries tend to be indefinable. Since a definition that allowed for every irregularity in the outer fringes would be excessively unwieldy, the one quoted above may be considered satisfactory. The expression industrial minerals is commonly equated with nonmetallics, and with the somewhat more precise phrase industrial minerals and rocks as in the title of this book. Characteristics of the Field The industrial minerals as broadly interpreted are a highly diverse group of materials; indeed, we may say paradoxically that diversity is about all they have in common. At one end of the spectrum are ordinary earth materials such as gravel and crushed stone, with a value of perhaps $3 per st; at the opposite end are industrial diamonds, which sell (by the carat) at the rate of roughly $18,000,000 per st. Neither the metals nor the fuels, and few if any categories of manufactured products, include items that differ in value by more than six orders of magnitude. Most gravel and stone are of no value unless close to a market; diamonds and other exotic substances possess such unique and desirable properties that their occurrence in remote corners of the earth is no deterrent to their use. The broad range of industrial minerals falls between these extremes of unit value and place value. The industrial minerals penetrate the entire fabric of modern industrialized society, from such fundamental operations as drilling for oil and smelting iron ore to the manufacture of virtually the whole array of consumer products. There is no industrial-minerals industry; there are many industries. The simple term field is convenient as an all-inclusive expression. An industry is considered to belong in the industrial-minerals field if its operations consist of extraction and processing, but not manufacturing. Thus the mining and beneficiation of feldspar is a mineral industry, but the manufacture of ceramic products is not. In the cement and lime industries, processing merges into manufacture, and the line is less distinct. It disappears altogether in a plant that extracts salt as artificial brines, and makes sodium and chlorine chemicals, all under the same roof. An aspect of some industrial minerals that differentiates them from the metals is that their physical properties carry over into ultimate use of the product. Such minerals as mica, asbes-

Jan 1, 1983

By Harrison, Henry Fay

The study of an entirely new series of alloys may be undertaken from a desire to obtain knowledge applicable to the perfection of industrial alloys, or merely to test certain theoretical considerations. In the case of antimony-tellurium alloys, the theoretical side only is at present important; but it is hoped that the results of this investigation may have some industrial value, at least indirectly, by furnishing one more example for comparison when studying commercial alloys. The statement is found in various places that antimony is isomorphous with arsenic, bismuth and tellurium; but very little experimental evidence has been offered in support of this assumption. All four metals crystallize in rhombohedra, and the ratio of the axes a: c is approximately the same—which seems to indicate, but does not prove, their isomorphism. The close association of these metals in minerals also seems to indicate that they are isomorphous. There are, however, certain differences in their properties which render this coriclusion somewhat doubtful, and it is therefore desirable that inde-

Jan 1, 1902

By Frank Foote

IN recent years the constitution of the high-silver aluminum-silver alloys has been extensively investigated. Hansen1 has re-viewed the literature to 1935. More re-ently, Obinata and Hagiya,2 Hofmann and Volk,3 Taziri4 and Tishchenko5 have con-firmed the general features of the phase diagram in the region around 25 atomic per cent aluminum. In this paper we present the results of high-precision measurements of lattice con-stants of the silver-rich alpha solid solution in the homogeneous range and the neigh-boring two-phase regions. These results are used to establish the nature of the solid solution, the identity of directly measured densities with those calculated from lattice constants and the homogeneity limits of the alpha solid solution with respect to three different neighboring phases. A study of the earlier investigations indicated that the last two subjects in particular required new and accurate data.

Jan 1, 1940

The mines of the country are called upon to bear a very large part of the enormous taxes to be raised for 1917 and later years. The Internal Revenue Bureau, which is charged with the assessment and collection of these taxes, desires that the taxation laws shall be administered in a fair and business-like way. The application to mines, however, which have wasting assets, involves questions of particular complication and difficulty. To meet this situation, there has been established in. the Income Tax Branch, a Section of Mine Valuation in which these specific problems of the industry will be handled by competent engineers. But it is realized that something more than this is required for the satisfactory application of the tax laws to the mines, namely, as complete understanding as possible between the Government and the taxpayer, a spirit of cooperation as between the two and every possible assistance and advice from mine owners and mining engineers.

Jan 9, 1919

By P. G. Beckett

The problem of handling the large quantities of water encountered in the Old Dominion mine presents many features of interest. In the present paper are discussed the probable sources of water, the pumping equipment, the increased flow into the mine in the early part of 1915, culminating in the flooding of the 18th and 16th levels in March of that year, and the difficulties that were met with during the high-water period. I. PRELIMINARY The Old Dominion mine, situated 1 mile north of the town of Globe, Ariz., has long been one of the prominent copper producers of the State, and until the opening up of the copper schist deposits in the neighboring mines of Miami, was responsible for the greater part of the copper output from the Globe district. As the gradual exhaustion of its orebodies near the surface led to the downward development of the mine, more water was encountered in the western portions directly underlying the dacite formation until the drainage problem became a serious factor in the operation of the mine and in the economical extraction of the ore. A heavy inrush of water on the 10th level of the mine in 1906, preceded by still earlier water difficulties, rendered imperative the immediate installation of a pumping equipment capable of handling large flows of water. While the Old Dominion has been recognized as a wet mine since its early days and one in which the complete control of the water situation was of paramount importance in the development of the lower levels, it is chiefly in the last nine years, since the installation of the increased pumping equipment, that the mine has developed and handled large quantities of water. Its maximum pumping record was reached in the first six months of 1915, during which time, following a prolonged period of abnormal precipitation, the pumps handled 1,624,740,000 gal. of water; while in the month of March alone, over 407,000,000 gal. of water were pumped from the mine.

Jan 1, 1917

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Mining Engineer. Graduate of Colorado School of Mines, 1912, experienced in coal, lead manganese and limestone mining, wishes execu¬tive position. A-2146. Graduate Mining Engineer.-Discharged, reserve officer, age 32, single, 7 years' experience holding responsible executive positions, in iron, copper, and talc mining. Well recommended. A-4913. Mine Manager, Superintendent or Engineer. Age 41, graduate of Michigan College of Mines; 20 years' experience in responsible positions in connection with large operations; in iron, copper, pyrites, lead and zinc mines; successful in finding and developing orebodies, increasing production, and reducing costs. Desires a position with a future. A-4081. Mining Engineer.-Graduate from Polytechnicum, Stockholm; 14 years' practical experience in Sweden, United States, Belgium, and Spain, in iron-ore development, mining, and milling; thorough knowledge of English, French and Spanish; desires position as superintendent or assistant manager. Good references; member; now in Sweden. A-4914. Research Engineer. Now in Chile on the erection of a 50-ton mill with modern machinery for the treatment of Chilean nitrate. Desires connection from the first of next year; with firm operating in South or Central America. A-4915. Metallurgical Engineer. Junior member, age 26, single, graduate Columbia School of Mines; recently discharged as lieutenant in the heavy artillery. A-4916. General Superintendent. Technical graduate, age 35, desires position over a group of four or five mines or as assistant general superintendent for a large. company. Has had experience in superintending mines, construction work, opening new and abandoned mines, safety and effi-ciency engineering and handling organized labor. At present employed by a coal company in the middle West. A-4917.

Jan 11, 1919

By A. N. Holden, J. H. Hollomon

Inhomogeneous yielding during the early stages of plastic flow has been observed in many metals and has long been a subject of controversy. Low carbon steel, when strained at room temperature, exhibits a distinct yield point at which the metal ceases to behave elastically and begins to flow plastically without further increase in stress,† often with an actual decrease in stress from that existing at the yield point. One manifestation of this behavior is the familiar Lüders lines. The extent of the yield point elongation (the plastic strain which results without raising the stress above that at the initial yield point) may be several percent. Several explanations of this type of yielding in steels have appeared in the literature:1-3}; 1. The segregation of carbides or other constituents at the grain boundaries of ferrite forms cell-like blocks which break down at a higher stress than that at which the ferrite alone will flow. 2. The precipitation of various constituents within the ferrite itself in some way blocks initial flow until a higher stress is reached, after which a great deal of flow occurs without further increase in stress. 3. The restraining influence of neighboring, less favorably oriented grains in a polycrystal results in a storing up of energy, which on yielding is sufficient to cause the continued propagation of slip bands on the multiplicity of slip systems available in adjacent iron crystals without increase in stress. 4. Local segregation of carbon atoms increases the stress required for the initial propagation of dislocations. The stress required for further deformation is lower.3 Such an explanation would require the presence of upper and lower yield points in single crystals. Low and Gensamer2 have shown that heterogeneous yielding can be eliminated by removal of carbon and nitrogen from polycrystalline steels by wet-hydrogen treatment. They also demonstrated that the re-introduction of minute amounts of carbon or nitrogen caused a return of the yield point. Observations of the initial flow of single crystals containing small amounts of carbon and nitrogen- should provide a clue to the explanation of inhomogeneous yielding. Previous tests of iron crystals4-6 can not be considered conclusive because it is uncertain whether the carbon and nitrogen were satisfactorily removed by the decarburization technique employed. The purpose of the experiments described herein was to determine whether single iron crystals containing either carbon or nitrogen would exhibit in-homogeneous yielding. Experimental Procedures THE PREPARATION OF SINGLE CRYSTALS All crvstals were formed in the following way. Aluminum killed sheet material 80 mils thick was machined into specimens of the outer contour shown in Fig 1. These mildly tapered specimens were decarburized at 730°C for 16 hr in hydrogen that had been bubbled rapidly through water maintained at 70°. The resultant grain size after decarburizing was approximately ASTM 5. Several stress-strain curves were made of the decarburized niate-

Jan 1, 1950

By T. E. Leontis, D. H. Feisel

MAGNESIUM alloys containing rare earth metals have received considerable attention during the past several years because of the need for light alloys having high strength and creep resistance at elevated temperatures. Although much of the work reported earlier has dealt with alloys containing Mischmetal, it has been shown in two previous papersl, V hat distinctly different effects are produced by various rare earth metals and rare earth metal mixtures on the properties of magnesium. For example, much higher strengths are obtained in magnesium alloys containing didym-ium (essentially neodymium plus praseodymium) than in alloys made with Mischmetal, which contains all the rare earth metals in the proportions in which they occur naturally in the monazite ore. Mg-rare earth metal alloys are characterized by a relatively coarse grain size, which greatly impairs castability. The addition of zirconium as a second alloying ingredient has been shown8,7 to refine the grain size, which also produces a distinct improvement in the strength properties. Certain Mg-Mischmetal-Zr and Mg-Mischmetal-Zn-Zr alloy compositions which are currently being produced commercially have been discussed in dytail by Nelson and Strieter,8,4 who also present some in- formation on a Mg-low Ce-Mischmetal-Zr alloy, and by Nelson.8 A patent issued to Jessup, Emley, and Fisher9 emphasizes the superiority of Mg-didymium-Zn-Zr alloys over the corresponding alloys made with Mischmetal. The purpose of this paper is to present the results of an extensive investigation concerned with the effect of increasing amounts of zirconium on magnesium sand casting alloys containing several different rare earth metal mixtures in varying amounts. The effect of the addition of zinc to some of these alloys is also being reported. Preparation and Testing of Alloys The alloys studied in this investigation were prepared in small laboratory melts according to the melting procedures described by Nelson1" as the Crucible Method. Electrolytic magnesium having the composition shown in Table I was used as the starting material. The rare earth metal alloying ingredients used in preparing these alloys were essentially of the compositions listed in Table 11. Some of the didymium-containing alloys were prepared using a Mg-didymium hardener. The rare earth metal content of this hardener analyzed 1.2 pct Ce, 10.4 pct Pr, 80.8 pct Nd, and 7.6 pct La. The zirconium was added in one of three forms: 1) as sponge zirconium obtained from the Bureau of Mines; 2) as a fused salt consisting of 50 pct ZrCl, and 50 pct alkali chlorides from which the zirconium is reduced by the magnesium; or 3) as a Mg-Zr hardener. The alloying procedures and melt hand-

Jan 1, 1958

By H. R. Stahl

The disseminated lead district of Southeast Missouri lies 70 miles south of St. Louis. The only metal of economic importance in the ore is lead, but minor amounts occur of iron, zinc, copper, cobalt, nickel, silver and cadmium. These minor metals, as might be expected, tend to concentrate in both the flotation and table middlings. In the past, some zinc has been recovered by differential flotation. The silver and cadmium tend to associate with the zinc, and some recovery is made of these two metals at the smelter. The lead occurs as galena, or lead sulphide. The minor metals are also present as sulphides. The presence of oxidized lead is suspected, but has not been definitely proved. The gangue is chiefly dolomitic limestone, with small amounts of sandstone and shaly glauconitic and chloritic minerals. The ore contains about 3.25 per cent lead, occurring as galena disseminated through the gangue. Some of the galena is very finely disseminated, and the mineral in the gravity tailings, or chat; is seldom or never in the free state. The method of treatment of the ore has been evolved over a period of 75 years; hence probably is not far from correct. The milling processes have tended toward simplification during the past 15 years, but recoveries have never been sacrificed for the sake of simplicity. In many cases, simplification of flowsheets has led to better recoveries and operating economies. A simplified flowsheet is shown in Fig. I. The St. Joseph Lead Co. operates four mills in the Flat River district, with a normal total capacity of about 21,000 tons per day, divided as follows: Federal mill, 11,000 tons; Leadwood mill, 4500 tons; Desloge mill, 3400 tons and Bonne Terre mill 2400 tons. The methods of concentration used at these plants are similar in principle; they differ mainly in details and in the type and size of the equipment used. The process of concentration may be divided into five main steps; i.e., dry crushing, wet grinding, classification with its attendant desliming, tabling and flotation. A brief description of these processes will be given, noting important differences in the various plants, and also noting the more important changes or developments of the past few years. Dry Crushing The run-of-mine ore is hoisted in skips, the capacity of these skips ranging from 23/4 tons to 81/4 tons. At the Desloge plant, the ore is hoisted in 2-ton mine cars on self-dumping cages. All ore is hoisted at shafts adjacent to the various crushing plants, no ore being transported on the surface. Primary breaking at all the mills is accomplished with 9E Telsmith breakers. Preliminary screening is provided ahead of most of these crushers, either by station-

Jan 1, 1943

By H. R. Stahl

The disseminated lead district of Southeast Missouri lies 70 miles south of St. Louis. The only metal of economic importance in the ore is lead, but minor amounts occur of iron, zinc, copper, cobalt, nickel, silver and cadmium. These minor metals, as might be expected, tend to concentrate in both the flotation and table middlings. In the past, some zinc has been recovered by differential flotation. The silver and cadmium tend to associate with the zinc, and some recovery is made of these two metals at the smelter. The lead occurs as galena, or lead sulphide. The minor metals are also present as sulphides. The presence of oxidized lead is suspected, but has not been definitely proved. The gangue is chiefly dolomitic limestone, with small amounts of sandstone and shaly glauconitic and chloritic minerals. The ore contains about 3.25 per cent lead, occurring as galena disseminated through the gangue. Some of the galena is very finely disseminated, and the mineral in the gravity tailings, or chat; is seldom or never in the free state. The method of treatment of the ore has been evolved over a period of 75 years; hence probably is not far from correct. The milling processes have tended toward simplification during the past 15 years, but recoveries have never been sacrificed for the sake of simplicity. In many cases, simplification of flowsheets has led to better recoveries and operating economies. A simplified flowsheet is shown in Fig. I. The St. Joseph Lead Co. operates four mills in the Flat River district, with a normal total capacity of about 21,000 tons per day, divided as follows: Federal mill, 11,000 tons; Leadwood mill, 4500 tons; Desloge mill, 3400 tons and Bonne Terre mill 2400 tons. The methods of concentration used at these plants are similar in principle; they differ mainly in details and in the type and size of the equipment used. The process of concentration may be divided into five main steps; i.e., dry crushing, wet grinding, classification with its attendant desliming, tabling and flotation. A brief description of these processes will be given, noting important differences in the various plants, and also noting the more important changes or developments of the past few years. Dry Crushing The run-of-mine ore is hoisted in skips, the capacity of these skips ranging from 23/4 tons to 81/4 tons. At the Desloge plant, the ore is hoisted in 2-ton mine cars on self-dumping cages. All ore is hoisted at shafts adjacent to the various crushing plants, no ore being transported on the surface. Primary breaking at all the mills is accomplished with 9E Telsmith breakers. Preliminary screening is provided ahead of most of these crushers, either by station-

Jan 1, 1943

By Charles L. Harness

MINERAL pigments give color, opacity, or body to paint, stucco, plaster, mortar, cement, linoleum, rubber, and similar materials. They must be finely divided, substantially insoluble, and generally inert for such uses. Inorganic pigments may be grouped somewhat arbitrarily as follows: A. Natural mineral pigments dug from the earth. 1. Those consisting mostly of iron oxides, such as hematite and Limonite. 2. Those containing large amounts of clay or noncoloring matter, such as ocher, sienna, umber, and colored shales. 3. Those whose color is not due to iron oxide, such as Vandyke brown (including sap brown, an alkali extract of Vandyke brown), graphite, and terre verte. B. Synthetic pigments. 1. Those containing iron oxide as the essential coloring matter, such as "pure" reds, yellows, and blacks, and Venetian reds. 2. Those not containing iron oxide, such as lithopone, zinc white, titanium white, ultramarine, Prussian blue, and the like. Only groups A and B-1 are discussed here. All the pigments in those two categories, except Vandyke brown, sap brown, and some of the carbonaceous slates, contain, as their essential color constituents, one or more compounds of iron; namely, an oxide-Limonite (2Fe203.H20 to Fe203.4H20), hematite (Fe203), or magnetite (Fe203.FeO). Man's first permanent coloring materials were earth pigments- the ochers, iron oxides, and various iron-stained clays. The caves occupied by prehistoric man and the arts of the ancient Chaldean, Egyptian, and Cretan civilizations bear mute witness to this and also testify to the beauty and permanence of earth colors. As the Roman era developed, earth pigments were pushed from their pre-eminent position by white lead and red lead and in the Middle Ages by zinc oxide. Today, of course, the number of acceptable pigments is very large and on a value basis the group of natural and synthetic earth pigments stands

Jan 1, 1949

By John Fulton

The Menominee range is one of the four great mining belts that flank the western prongs of Lake Superior. It has received its name from its location along the north side of the Menominee river, which at this place flows between the States of Michigan and Wisconsin. The term "range" is derived from the elevated ridge, extending in a westward direction, and along the southern flank of which the iron-ore mines are located. This range is some 200 to 300 feet high above the general level of the adjacent country, and is made prominent by its surroundings of low, swampy lands. Its whole length is about 27 miles, and it is intersected, at intervals along its course, by gaps which are threaded by streams. The geology of the Menominee range is peculiarly interesting. It is composed of three distinct groups of Hurouian rocks. The supporting group consists of light-colored limestone beds of a crystalline, siliceous character, called the "Norway limestone belt." The map, Fig. 1, and the section, Fig. 2, will give a general notion of the position and structure of the range. The properties shaded in the map are those of the Penn Iron Mining Company, which is the Michigan representative of the Cambria Iron Company of Johnstown, Pennsylvania. This belt is at least 1200 feet thick. It outcrops boldly at many localities along the range, especially north of the Norway, Quinnesec and Chapin mines. At Quinnesec it can be studied readily. The next, or Banking group, which is estimated at a thickness of 1000 feet, is called the Quinnesec ore-formation. It consists, in the portion next to the limestone, of siliceons or jasper slates, largely impregnated with iron oxide. These are succeeded by argillaceous hydro-mica black and flesh-colored slates. This formation embraces the deposits of the iron-ores. The third group consists of a series of dark gray, slaty or schistose beds, with occasional quartzose bands, having a thickness of 2000 feet. It is called the Lake Hanbury slate group.

Jan 1, 1888

By J. J. Friel, E. S. Erickson

Dolomite-fluxed pellets of various compositions were made from magnetite concentrate, hematite concentrate and a concentrate containing a natural mixture of both. Physical properties and reduction test results were used to ascertain proper compositions and firing temperatures. These pellets were subjected to physical tests and to reduction tests. Petrographic and electron microprobe examinations were made to evaluate the effect of composition and fining on the phase assemblage. We interpreted our test results in terms of chemistry and microstructure and related these to properties. This approach enabled w to determine the composition best suited to each of the three concentrates. Compared with acid pellets, dolomite- fluxed pellets of the optimum compositions had similar physical properties but swelled less, softened at a higher temperature, and reduced faster and more completely.

Jan 1, 1983

By C. Dean Starr

The physical basis of the equation correlating electrical conductizlity and temperature coefficient of resistance of solid solution alloys has been inzlestzgated and the nature of the constants evaluated. It is shaun that the same form of correlation is valid irrespective of the magnitude of the temperature coefficient. However, the effect of therma1 expansion and change in resistivity with temberature nust be considered when the magnitude of the temperature coefficient of resistance is near zero. In a comprehensive literature survey conducted at the Armour Research Foundation in 1950, it was found that a linear relationship exists between the electrical conductivity, K, and the temperature coefficient of resistance, a, for solid solution alloys. This was expressed by the equation where B, a constant, depends on the solvent metal but not the solute. A continuing investigation by Hansen, Johnston, and Parks showed this equation was generally appropriate for Cu, Ag, Au, Pd, Pt, and Co base binary solid solution alloys as well as for many ternary alloys of copper over a range of conductivities and temperature coefficient of resistances from 0.02 to 0.60 reciprocal pohm cm and-0.00015to0.004Q per 0 per "C respectively. Eq. [I] was not always valid for alloys that exhibited a change in state (magnetic to nonmagnetic) or for alloys that had a temperature coefficient of resistance near or below zero. For example, in nickel alloys, a simple linear curve as predicted by Eq. [l] was not obtained when the conductivity was plotted against the temperature coefficient of resistance. Hansen suggested that deviations observed were caused by transitions from a ferromagnetic to a nonmagnetic state. Subsequent and more extensive data by ronin on Ni-Mn alloys confirmed Hansen's postulate. While both states independently showed a linear relationship between K and a, the value of B was different for the two states. In some copper and gold base alloys, as well as the platinum and palladium alloys investigated by Hansen, the conductivity did not extrapolate to zero at zero a as demanded by Eq. [I]. This deviation can be readily corrected by simply adding a constant to Eq. [I.] whence Eq. [2] shows the K decreases as a decreases but that K has a positive value when a = 0 which is observed for commercial solid solution alloys as well as the experimental alloys tested by Hansen. While other methods of correlation of electrical properties have been made such as the one by Starr and Wang3 who found a linear relationship between resistivity and temperature coefficient of resistance for Ni-Cr-Al-Cu alloys, the data, in general, can also be correlated by a form of Eq. [2]. Thus, Hansen's empirical equation has considerable merit. The objective of this paper is to determine the physical basis for this equation and to examine the region near zero a in more detail. ELECTRICAL CONDUCTIVITY VS TEMPERATURE COEFFICIENT OF FU3SISTANCE The resistance of a metal or alloy is defined as

Jan 1, 1963

By Harold B. Janzen, M. A. Nobles

Campbell and Martin1 described a new exploratory logging tool which was developed as the result of a new concept of the phenomenon that takes place when a porous formation containing mobile hydrocarbons and irreducible interstitial water is invaded by mud filtrate. They postulate that invasion will create a bank of interstitial water between the flushed zone and the undisturbed formation. This postulate was confirmed by Wyllie.' Thus, if R,, is greater than R, and mobile hydrocarbons are present, the resistivity profile with increasing radii from the borehole is high:low:high, as shown in Fig. 1. If mobile hydrocarbons are absent, the bank of interstitial water is indistinguishable from the undisturbed formation and the resistivity profile, when R is greater than R,, is high:low, as shown in Fig. 2. The zone containing the bank of interstitial water and residual oil was named the "low zone". Campbell and Martin conducted extensive electrolytic wedge and resistivity analog model studies to select a logging system that would reflect the presence or absence of the low zone. The system they selected was that of a family of lateral curves. The model studies indicated that the presence of a low zone could be detected in approximately 60 to 70 per cent of the producing sand reservoirs with a family of lateral curves provided that the sonde effectively occupies 90 per cent of the diameter of the hole. These studies were conducted with D, = 5d. The presence or absence of the low zone is best determined by a plot of the apparent resistivity vs spacing as shown in Figs. 3 and 4. A dip or inflection in the profile that repeats at successive depth intervals is considered diagnostic. To reduce the shunting effect of the hole and mud, a sonde of insulating material that is surrounded by a series of flexible rubber bumpers was designed. The bumper efficiency is considered to be the ratio of the bumper diameter to the hole diameter. Field tests conducted by Campbell and Martin on 10 wells with a tool that provided for station readings indicated that dips or inflections could be detected in 19 out of 25 known producing zones. INSTRUMENT DEVELOPMENT Halliburton developed a logging system to simultaneously and continuously record eight lateral curves. The instrumentation is described in the literature.' The original logs made

By E. V. Kleber, V. F. Novy, R. C. Vickery

The constitutional diagram for the gadolinium-cobalt system has been determined. Seven intermetallic compounds have been found at compositions corresponding to the follwing gadolinium-cobalt ratios: 3:1, 1:1, 2:3, 1:2, 1:3, 1:4, 1:5. The GdCor compound has a congruent melting point above 1600°C. whereas the remaining compounds melt incongruently. Eutectics exist at 16 wt pct Co and 84 wt pct Co, with melting points of 620° and 1260°C, respectively. PREVIOUS papers'" have recorded constitutional data for systems of gadolinium with iron and nickel. This paper presents data obtained on alloys of gadolinium with the remaining 3d transition element-cobalt. voge13 found that cerium forms, with cobalt, the intermetallic compounds; Ce3Co, CeCo, CeCo2, CeCo3, CeCo4, and CeCo5 Other workers4-' found the 1:2 compound in this series to exist in a C-15 (face-centered cubic) structure and the 1:5 compound to exist in a hexagonal crystal system. Comparison of earlier data with that now reported will be made subsequently. EXPERIMENTAL Methods of alloy preparation, annealing procedures, and experimental techniques have been previously reported.' The cobalt content of alloy specimens was determined volumetrically. RESULTS Microstructure—The alloy containing 10.5 wt pct Co corresponds closely to the composition of the first intermetallic compound Gd3CO. In Fig. 1 the microstructure is essentially single phase composed of Gd3Co which formed peritectically. The globular areas are remnants of the peritectic reaction which did not quite go to completion. A eutectic occurs between Gd3Co and the next higher compound GdCO, which is followed by a series of peritectic compounds. Fig. 2, an arc-cast alloy containing 20.2 wt pct Co, shows large primary crystals of GdCo etching either white or black (depending on crystallographic orientation), embedded in the eutectic. Similarly, in Fig. 3 at 31.2 wt pct Co, a compound, probably GdCo3, has separated from the melt. Subsequent peritectic reactions were almost completely by-passed as the alloy cooled, the residual liquid freezing as a fine eutectic. In the 47.5 wt pct Co alloy, Fig. 4, the high melting point compound, GdCO4, has solidified as massive, white-etching grains, which reacted with the liquid to form GdCo3 as the second phase. The microstructure of an arc-melted alloy containing 60.5 pct Co is complex, Fig. 5, and presents some difficulty in interpretation. The grey etching matrix is probably primary GdCO4. The dappled phase represents grains of GdCO5 which have separated from the melt on cooling. The discrete spots in this phase are eutectic liquid. Small light etching crystallites are probably GdCO5 formed by the incomplete high-temperature peritectic reaction. GdCO4 is retained in arc-melted specimens containing 70.5 wt pct Co, Fig. 6. White areas of this compound are held in a matrix of GdCO5 the appearance of which is mottled slightly by inclusions of the second eutectic in this system. The development of the spheroidized eutectic at high cobalt contents is depicted in Fig. 7 (80.3 wt pct Co) in which the white massive crystals are GdCO5 compound. Further development of this eutectic is seen in Fig. 8, the primary white phase here being pure cobalt. Thermal Studies—Differential thermal analyses and melting point determinations have yielded the data shown in Fig. 10. The high gadolinium eutectic, indicated by microscopy, was confirmed at about 16 wt pct Co, melting at 620°C . A eutectic also occurs at about 84 wt pct Co melting at about 1260°C. The thermal arrests at 8803 960°, 1060; and 1210°C,

Jan 1, 1962

By K. E. Niermeyer, J. A. Bratt, B. A. Fahm, B. A. Kennedy

The instrumentation, monitoring, and prediction of a major slope failure at the Chuquicamata mine are described. In December 1967, preexisting tension cracks on the south end of the east wall of the mine began to open. Various forms of instru¬mentation were installed for continuous monitoring. These systems included tension crack stakes, crack extensometers, linear extensometers, tape and transit lines, sliding wire contacts, and a seismograph. From the information obtained, the failure date was accurately predicted some five weeks before failure, enabling the mine to reroute truck and rail access; hence, causing a minimal mine shutdown of 21/2 days and preventing any injuries to person or damage to equipment. The shape and form of the sliding mass are analyzed, as are possible modes of failure.

Jan 1, 1972

At the close of the current academic year, there will be eight vacancies to be filled in research graduate assistantships which are maintained by the Engineering Experiment Station of the University of Illinois. In addition to these assistantships, there are available two research graduate assistantships in gas engineering, which are supported by the Illinois Gas Association. These assistantships, for each, of which there is an annual stipend of $500 and freedom from all fees except the matriculation and diploma fees, are open to graduates of approved American and foreign universities and technical schools who are prepared to undertake graduate study in engineering, physics, or applied chemistry. An appointment to the position of Research Graduate Assistant is made and must be accepted for two consecutive collegiate years, at the expiration of which period, if all requirements have been met, the degree of Master of Science will be conferred. Not more than. half of the time of a Research Graduate Assistant is required in connection with the work of the department to which he is assigned, the remainder being available for graduate study.

Jan 3, 1919