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By C. W. Volek, J. E. Chappelear

The injection of a hot liquid into initially cool porous media, saturated with the same liquid and surrounded by two impermeable but heat conducting media (cap and base rock), has been studied both experimentally and theoretically. The temperature dependence of the viscosity was included in the theoretical model, but it was assumed that the specilic heats and densities of the various materials were independent of the temperature. Solutions to the theoretical model were approximated by numerical methods. Both theoretical and experimental results indicate that center-line temperatures are significantly higher than boundary temperatures. Comparison of experimental and theoretical results with a cold/hot viscosity ratio 01 19:1 were in reasonable agreement. Theoretical calculations show that the effect of the temperature dependence of viscosity was very significant at ratios of 100:l to 1000:1, which are typical of those that occur when injecting hot water to flood heavy oil reservoirs. INTRODUCTION We consider the problem of prediction of fluid flow and temperature distribution in an initially cold-fluid-filled reservoir on the injection of the same hot liquid by the use of mathematical and physical models. The results reported are for a two-dimensional rectangular section of the reservoir, as shown in Fig. 1. The injection and withdrawal faces are assumed to be equipotentials for fluid flow. The ultimate purpose of such models would be to predict hot-water injection performance. However, we note that in the work presented here, one of the most significant aspects of the problem — the instabilities resulting from two-phase, water and oil flow — is not included. We will not give a historical review, but refer instead to the paper of Spillette and Nielsen,1 which contains a rather complete bibliography and critical discussion. The physical problem is exactly the same as Spillette and Nielsen, except for certain simplifications in our assumptions. The mathematical details are somewhat different, and we will present the details of our method here. The mass flow equation, which is elliptic in character, is handled by successive overrelaxation. The heat flow equation, which is parabolic in character, is handled by a straightforward explicit approximation. Some difficulty arose in the over-all heat balance due to small errors in the solution of the mass flow equation, and we feel that a different formulation of the heat flow equation would be desirable for future work. In addition to the mathematical solutions for the temperature distributions in a porous medium due to the injection of hot liquids, experimental data are presented to check the validity of these solutions. A schematic diagram of the model is shown in Fig. 2. Certain qualitative physical conclusions were obtained from our numerical and experimental results. These are: 1. Assuming high (infinite) conductivity normal to the bedding plane in the reservoir is a poor approximation, and may lead to overestimates of the total heat losses (to cap and base rock) of as much as 50 percent. 2. More heat is retained in the reservoir (per unit of heat injected) for higher viscosity changes. 3. Any particular temperature isotherm moves more rapidly along the center line for higher viscosity changes. Consequently, the approximation of temperature independent viscosity is not suitable for obtaining quantitatively correct results. MATHEMATICAL MODEL Our mathematical model is that of a reservoir of thickness 2h. The problem is idealized from that of a linear hot-water drive, and we imagine that the input face is sufficiently far away from the injection wells that the stream lines enter it normally. Similarly the production wells are far enough from the outflow face that the flow lines leave it normally. The reservoir and surrounding cap and base rock

Jan 1, 1970

By I. R. Kramer

The apparent activation energy, U, JOY plastic deformation of aluminium, copper, and gold single crystals and polycrystalline aluminum was found to he dependent upon surface condition. At low strains, the value for U for aluminum single crystals was 4200 cal per mole ; however, this value decreased to 920 cal per mole when the specimens were polished during the test at a rate of 50 X 10-5 win-1 The activated volume also was found to increase with the rate of metal removal. That the surface plays an important role in plastic-deformation processes has been adequately demonstrated.1-4 Of particular interest at this time are the observations4 that the creep rate of single crystals of fee metals is increased markedly when specimens are polished during the deformation process. These observations were interpreted in terms of a dislocation debris layer at the surface regions of the crystal. This layer, which appears to be a region containing a high concentration of dislocations or segments of dislocations, not only will impede the egress of dislocations on the primary slip system, but will also provide a barrier against which dislocations may pile up. By this means, a stress which opposes the motion of dislocations will be generated. It is considered that this stress must be taken into account in any theory which describes the plastic-deformation process. Although a detailed dislocation model cannot be given at this time, it may be stated that the stresses opposing the motion of dislocations arise from the dislocations in the debris layer, Ts, and ti due to the resistance to motion imposed by internal obstacles such as Lomer-Cottrell barriers, subgrain and grain boundaries, forest dislocations, and so forth, as well as the resistance due to the presence of jogs on dislocations and the interaction of the stress fields of dislocations, and so forth. In essence, we have added an additional term, ts, to the usual form of the equation T = Ta- Tb, where Tb is the back stress due to the various types of obstacles which impede the motion of dislocation. Accordingly, the net stress, t, acting on a dislocation may be written as where Ta is the applied shear stress. For deformation which occurs by a thermally activated process5,8 ?=Ae-u/kT = A e(u,-VT)/kT [2] and U = Uo- Vt PI where U = activation energy for plastic flow, y = shear strain rate, Uo = activated energy for plastic deformation in the absence of stress and depends upon the particular deformation process, V = activated volume, k = Boltzmann constant, T = temperature, OK, and A = frequency factor. From Eqs. [I] and [3], U = Uo- V(Ta - Ti - TS) [4] and it is seen that if Ts decreases, the activation energy, U, must decrease if V remains constant. However, as will be shown, V is a function of the surface conditions. In their work on aluminum, Lytton and coworkers7 reported that at low strains the activation energy was 3400 cal per mole and at high strains it was 28,000 cal per mole. The lower value was interpreted in terms of the energy necessary to overcome the Peierls force, while the higher value was associated with the energy necessary for dislocations to move by a cross-slip process. It will be shown that the lower activation energy is associated with the surface debris layer rather than with the Peierls force. EXPERIMENTAL PROCEDURE Single crystals having a nominal cross section of 1/8 in. and a 3-in. gage length were prepared by a modified Bridgman technique using a multiple-cavity graphite mold. The initial purity of the metals was 99.997, 99.999, and 99.999 pet for aluminum, copper, and gold, respectively. The orientation of the specimens is given in Fig. 1. The measurement of the activation energy as a

Jan 1, 1964

By K. E. Nelson

The effect of thorium and zinc variations on the strength and 100-hr creep characteristics of Mg-Th-Zn-Zr alloys was investigated. Optimum resistance to creep at 650° and 700°F are attainable within a certain range of thorium and zinc contents. This range does not conform to that which develops maximum tensile properties. RAPID advances have been made during the last few years in the development of magnesium alloys for elevated temperature applications demanding high resistance to creep. The beneficial effect of rare-earth metals on the creep resistance of magnesium alloys has been emphasized by a number of publications1-13 and such alloys are now in commercial production. The use of thorium as an alloying ingredient in magnesium was mentioned by McDonald and also in two Alien Property Custodian patent applications.10,17 The initial observation of Sauerwald that thorium contributes still higher creep resistance to magnesium than is attainable with rare-earth metals has recently been substantiated.'" " In fact, it has been demonstrated that the useful temperature range of magnesium alloys is appreciably extended by the use of thorium. In all cases, it was observed that zirconium must be included in the alloys in order to render them fine grained and more readily castable. Several recent publications:2-27 indicate that a still further improvement in creep resistance and a further extension of the useful temperature range can be realized by the addition of zinc to alloys. The primary purpose of this paper is to present the results of a comprehensive study of the effect of zinc on the strength and creep characteristics of Mg-Th-Zr alloys. Compositions covering the range of thorium content from M to 6 pct and zinc content from 0 to 5 pct have been investigated. The creep characteristics at 650" and 700°F reported in this paper are based on results of tests of 100-hr duration. It is appreciated that creep tests of 100-hr duration might not yield adequate data for design purposes for parts with much longer expected life. However, for the purposes of the present discussion, it is felt that the combination of stresses and temperatures used in the 100-hr creep tests have yielded a clear representation of the compositional variation of creep resistance at the temperatures investigated. Creep tests of 1000-hr duration are now in progress on a few of the most promising alloys. Preparation and Testing of Alloys The alloys studied in this intensive investigation were prepared in 25 lb capacity mild steel crucibles. The thorium, zinc, and zirconium were alloyed and poured as described in earlier publications The thorium was introduced into the melt in the form of a Mg-Th hardener," the zinc added in the metallic form, and the zirconium alloyed in the form of the commercial hardener containing magnesium and 30 to 50 pct Zr.10, 26 Fluxing practices for melting and refining were the same as for magnesium-rare-earth metal-zirconium alloys. The melts were sampled for analytical determinations and poured into separately cast 1/2 in. diameter standard tensile bars. The test bars were given a precipitation treatment of 16 hr at 600°F in laboratory furnaces. It has been shown by other tests that a high temperature solution treatment followed by an aging treatment is unnecessary for the development of optimum properties in Mg-Th-Zn-Zr alloys. The selection of 600°F as the aging temperature was based on an attempt to achieve metallurgical stability without coalescence of the undissolved phases and the attendant loss in strength. The thorium, zinc, and zirconium contents of each melt were determined chemically. The zirconium contents are reported in two parts, "soluble" and "insoluble," referring, respectively, to the portions present in the alloy which are soluble and insoluble in dilute HCl acid. Distinction is being made between these two components of the zirconium content in the alloys because it has been found that only that portion of the zirconium content which is soluble in dilute inorganic acids affects the structure and properties of the alloys. The usual impurities consisting of copper, iron, manganese, and nickel were determined spectroscopically. The analysis for each melt is listed in Table I. A description of the methods of tension and creep testing has been detailed in earlier papers. The tests were performed with the cast skin re-

Jan 1, 1954

Steps were taken for a permanent organization of the scientific and technical employees of the Government at their mass meeting on May 8. This was the result of an informal meeting on Apr. 23 of thirty representative Government scientists and technical men who organized the preliminary committee and called the mass meeting. This subject has been widely discussed during the last year and was brought acutely to the fore by the work of the Joint Congressional Reclassification Commission, because that Commission has stated that it wished to deal with employees only through organizations. Rodney H. True of the Department of Agriculture was Acting Chairman. He pointed out that the principal advantages that were expected to be derived from such an organization were: (1) Improvement of conditions and facilities for more effective scientific and technical work; (2) adequate presentation of the needs. and results of such work to the public and to legislative and administrative officers; (3) -greater freedom in both official and non-official activities; (4) just and reasonable salaries based on service performed and the economic and social conditions which prevail; (5) greater public recognition of the aims and purposes of research; (6) advancement of science and technology as an essential element of national life. Three plans of organization were offered to the meeting, which covered the fundamental principles which could be utilized by these Government employees. The first plan would have permitted the new organization to work only through existing scientific organizations. This is the plan that scientific and technical Government employees in England have adopted and an outline of the English plan was read to the meeting.

Jan 6, 1919

By Frederick G. Bulkley

That portion of the geological structure of the Leadville district which rests upon the Archæan is made up of sedimentary beds of Silurian and Carboniferous formation, consisting of many conformable strata of limestones, quartzites, and shales, which have a total present thickness of about five thousand feet. Interbedded with these strata are found, under somewhat fixed lams of regularity, sheets of intrusive igneous rock,' varying in thickness from a foot or two to several hundred feet. These consist for the most part of various types of felsite rocks, classed, by the sanction of common and long-continued usage, under the general term of porphyries. Mr. S. F. Emmons, in the abstract of his " Report upon the Geology and Mining Industry of Leadville," says in this connection : In their mode of occurrence the type-feature is that of intrusive masses, which are developed on a scale of unprecedented magnitude, and follow certain horizons with remarkable regularity.... It is probable that this mode of occurrence of eruptive rocks, viz., as intrusive masses which originally did not reach the surface but were forced up to a certain horizon and then spread out bettween the beds, is far more common than has hitherto been suspected by geologists. It is difficult to conceive of the conditions under which a fused mass could pry open strata to a width of one thousand feet or more, overcoming the weight often thousand feet of superincumbent rocks, and spread itself out in a continuous sheet between the beds to a distance of ten miles beyond the point or line of eruption. That they did exist, however, can be clearly demonstrated in this region.... In one single section over fifteen sheets, many several hundred feet thick, were counted between the Blue Limestone and the top of the Carboniferous. The region here under discussion is made up of a series of great

Jan 1, 1885

By Donald Barton

THE elastic, earthwaves produced naturally by earthquakes -have been used for a long time as evidence from which to draw conclusions in re-gard to the constitution of the interior and crust of the earth. The elastic earthwaves produced artificially by occasional explosions and recorded by seismological observatories were used to draw conclusions regarding the-geology of the intervening area. Intentionally pro-duced elastic earthwaves in the past five years have come to be used extensively in the investigation of very local geologic structure. The seismic method of work-ing geologic structure, which makes use of artificially controlled explosions and the resulting earthwaves, has developed almost `clairvoyant power in handling certain geologic situations, and in the discovery of salt domes in the Gulf Coastal: Plain region of Texas and Louisiana has 'scored the, most brilliant success. The. first, proposal for the use of artificial earth-quakes in the study-of velocity of elastic earthwaves in the surface formations of the earth's crust was made before 1888 by the English seismologists, Mallet and Abbot. Partly on the basis of their work, A. Schmidt in 1888 proposed- the use of the time-distance graphs of artificial earthquakes to study the variation of ve-locity with depth. Belar in 1902 proposed the practical application of such investigation in connection with boring tunnels. Galitzen repeatedly (1912, 1913) pro-posed the use of explosions to study the velocity of the longitudinal and transverse waves in the uppermost formations and pointed out that the velocity depended in a high degree on the physical character of the beds and that from changes in the velocity, conclusions could be drawn in regard to the compositions of the beds. Somewhat the same thought: was proposed by von dem Borne (1908), by Benndorf, Udden, and others.

Jan 9, 1928

By Gerhard Derge

A series of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.' There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. Experimental Procedure The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938

By Gerhard Derge

A series of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.' There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. Experimental Procedure The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938

By T. L. Joseph

Charcoal was the predominant blast-furnace fuel until 1838, when it was found, by the operation of a 2-ton experimental furnace, that anthracite could also be used. This information was a stimulus to the iron industry, particularly in eastern Pennsylvania where anthracite was available at low cost. The production of anthracite pig iron increased steadily and, in 1855, its tonnage exceeded that of charcoal iron. Of the 680 furnaces in operation in 1874, the 226 using anthracite produced nearly one-half the total tonnage. In 1869, the production of coke furnaces exceeded that of charcoal furnaces and, in 1875, coke surpassed anthracite as a metallurgical fuel. In 1907, the output of anthracite pig dropped well below a million tons and its present significance is largely historical. In recent years, the production of coke has gone hand in hand with the production of pig iron and it has gradually attained the position it now occupies as a universal blast-furnace fuel. Charcoal, however, has great merit as a blast-furnace fuel chief1y because of its freedom from ash and sulfur. The harmful effect of the latter and the necessity of keeping the percentage of this element in pig iron at a minimum are well recognized. Other contaminating elements can be reduced to specified limits in the steel-making process, but the control of sulfur belongs essentially to the blast furnace. The purpose of this paper is to point out the distribution of this impurity in blast-furnace materials and to indicate how its presence alters the composition, quantity, and free-running or critical temperature of the slag, and the relation between these factors, fuel economy, and the cost of iron. Sulfur Distribution in MateRials Table 1 shows the distribution of sulfur in charcoal practice. Similar figures taken from coke practice are given in Table 2. These data were

Jan 1, 1925

By J. E. Tobey

UNDER war conditions coal immediately assumes a position of highest importance for coal must carry the basic load for industry. The upward trend in production continued through 1941. Bituminous coal production alone about equaled the total output of bituminous and anthracite in 1940. The figures for 1941 approximated 500,000,000 tons for bituminous, and 54,000,000 tons for anthracite, and production of by-product and beehive coke exceeded that of the previous year. The coal industry, under the National Bituminous Coal Act, is going through a period of readjustment, and is beginning to stabilize itself under the statute. The Federal Mine Inspection Nill became law during the year.

Jan 1, 1942

By R. W. Gurry

WHEN a steel in the austenitic state, with all its carbon in solution, is maintained, at constant temperature, in contact with a gas that removes the carbon from the surface, vet without otherwise altering the composition of the steel, the change in weight of the specimen, after any period of exposure, is a direct measure of the amount of carbon it has then lost. The purpose of the present paper is to show how, by application of established mathematical reasoning based on the fundamental diffusion law and on certain postulates, this loss of weight yields a complete picture of the distribution of carbon throughout a specimen of regular shape after any period of exposure, with all the accuracy required in any practical occurrence of decarburization. Precisely the same is true for the gain in weight during the reverse process of carburization, or for the gradual gain or loss of any element, so long as the steel comprises only a single phase at temperature, provided always that the experimental conditions conform to the postulates. The change in carbon content from surface to center of the specimen is always continuous, when everything is in solution, even though under the microscope the decarburized zone (or carburized rim) may appear to be sharply defined. The experimental procedure is described and some typical results are presented, which are then interpreted by application of the diffusion law. EXPERIMENTAL PROCEDURE Initially an endeavor was made to follow the gain of weight during the process of carburization in a hydrogen-toluene atmosphere, but it was soon found that the specimen became coated with graphite, which could not be removed without some loss of metal; therefore it was decided to continue carburization until the steel was saturated throughout, to remove all graphite from the surface of the specimen, and then to follow the loss of weight during decarburization in a moist hydrogen atmosphere at the same temperature as that used for carburizing. The carburizing procedure has been described in an earlier paper;1 it suffices to state here that the carburization lasted about 140 hr. at 760°C. (1760°F.) and 44 hr. at 1110°C. (2030°F.), these periods being long enough-on the basis of the calculations presented later-to ensure that the specimen was about 9.99 per cent saturated at each temperature. The speci¬men was a cylinder about 3.8 cm. long and 0.475 cm. in diameter; the materials were carbonyl iron, a commercial low-metalloid iron, and a steel with 3.6 per cent nickel and the usual proportion of other elements. The fully [carburized] specimen, after cooling at the top of the furnace tube, was placed in a lathe and sandpapered to remove all graphite; then the diameter was measured with a micrometer caliper, and the initial weighing (corresponding to complete saturation) was made. By means of a

Jan 1, 1942

By John Chipman, Helen Towers

DEVELOPMENT of a simple radioactive tracer technique for measurement of the diffusion coefficient of calcium ion in liquid slag has already been reported. The investigation was of a preliminary nature designed to explore the possibilities of using radioactive isotopes and to establish a method, and no great accuracy was claimed for the results. It was shown, however, that Ca15 could be used successfully, and the values obtained for the diffusion coefficient appeared to be of the right order of magnitude. However, it was considered that a better technique could be devised for carrying out the diffusion. The experiments were, therefore, continued to find a more accurate method, to check the calcium results, and to extend the investigation to include measurements of the diffusion coefficient of silicon in the same slag. There were two flaws in the original technique. Convection was the cause of too many failures, and the interface between the two slags in the diffusion cell was curved rather than plane, probably due to a surface tension effect caused by the addition of the tracer Ca45 in the form of chloride. Two methods of overcoming these defects were tried. Since it was planned to study diffusion of the short-lived isotope Si"' also, the development of methods was restricted to those which gave promise of being reasonably rapid. Method 1—The principle was identical to that previously used with respect to the diffusion conditions, but there were three differences in technique. Temperature control was more rigid, the tracer was added to the slag as Ca45O rather than the chloride and, finally, an effort was made to translate to high temperatures the elegant method developed by Cohen and BruinV or bringing together the two liquid layers and beginning the diffusion. A master slag was melted in graphite, ground to a fine powder, and analyzed (38.5 pct Ca0-20.9 pct Al2O3-40.5 pct SiO2). The tracer was received as Ca45C12 in an aqueous solution of CaC12 + HC1. From this, calcium oxalate was precipitated, ignited to calcium oxide, and added as such to the slag to give an activity of approximately 5 µc per g. The mixture was then melted into the form of a cylinder 3/16 in. diam and about 1 in. long. A solution identical to the tracer solution without Ca45 was given exactly the same treatment. The resulting Ca40O was mixed with that slag which was to form the tracer-free half of the diffusion cell, and this was likewise melted into a cylinder of the same size. Slag cylinders, two with and two without Ca15, were set in graphite blocks as shown in Fig. 1, and the crucible was lowered into position in the fur-

Jan 1, 1958

By AIME AIME

MANY of the important papers to be presented at the World Congress of Engineering at Tokyo, in November, 1929, are being furnished by members of A.I.M.E. and a list of them is given below: "Fifty Years of Physical Metallurgy,,-by H. M. Boylston, Case School of Applied Science, Cleveland, Ohio.

Jan 1, 1929

By Cyril Smith

SOMEWHAT over ten years ago the author described studies1,2 on the constitution of the copper-silicon system. The copper-rich portion of this diagram is shown in Fig. 1. The experimental points freely dotted about the diagram seemed to justify an otherwise unconvincing diagram and for several years the curious reverse bend in the alpha-phase bound-ary was accepted as substantially correct, even by later investigators3,4 of the system who introduced changes in the high-silicon phases. The binary diagram has been used as a base for several ternary systems" without any suggested changes. Voce10 suspected the existence of another phase from his study of the cast alloys in the copper-manganese¬silicon system, but evidently hesitated to extrapolate this to the binary diagram, particularly in view of the too ingenious explanation that was advanced" to account for the pools of constituent clearly visible in castings; namely, that they were secondary alpha of twinned orientation deposited from beta. Von Schwarz,12 in 1932, called attention to the fact that this micro-constituent in copper-silicon alloy castings was anisotropic under polar-ized light and asserted that a new phase, not cubic, should be placed in the diagram adjacent to alpha. Sautner,13 on the basis of investigations with the polarizing microscope and with X-rays, introduced this phase into the diagram at about 6 per cent Si. The relevant part of his dia-gram is shown in Fig. 2. Sautner called the new phase beta, renaming the old beta phase zeta. To avoid confusion, in redrawing Fig. 2 the phases have been renamed in accordance with the terminology adopted in the present paper, in which the new phase is called kappa and the other phases retain the designation given them by Arrhenius and Westgren.4

Jan 1, 1939

Charles R. Eeyes, Des Moines, Ia. (con~munication to the Secretary*):—It is not in a spirit of criticism that I offer a supplemental suggestion or two on the subjects covered by this valuable and highly instructive memoir. There are two points which, in my opinion, should have received greater emphasis in Mr. Emmons's excellent paper. One is the fundamental r6le played by the chlorides under certain conditions in ore-formation. The other is the possible establishment of geographic relationships among the four pheilomena of (1) excessive chlo-ridic content of mine-waters; (2) the abundance of chloridic compounds of the precious metals; (3) the presence of man-gancse oxides; and (4) the diminishing importance, in ore-genesis, of the metallic sulphates. Although Mr. Emmons's notes refer to gold alone, it may be pertinently asked whether the same principles do not hold good for silver and copper also, since these metals form, together with gold, a distinct and well-known chemical group. That the reactions involved apply equally well to the other two metals mentioned, is sbown by a number of recent observations and discussions. Chloridic ores of silver are, as I have lately endeavored to show, mainly worked in arid or desert regions only; and the great deposits of disseminated copper-ores are similarly characteristic of such regions, in which both classes doubtless owe their formation to the abundance of saline materials derived from desert dusts, and to the plentiful and almost universal presence of manganese oxide. Under these climatic conditions, silver is somewhat more abundantly deposited than copper and gold, because its chloride is so much less soluble. During volcanic emanations, the metallic chlorides perform at all times distinct functions; when these are

Jan 1, 1912

By Walter R. Hibbard

BACKOFEN' reported recently that "the deformation texture of cold-drawn OFHC copper wire, after a reduction in area of 97.3 pct, may still be described as a composite of [lll.] and [loo] directions aligned parallel to the wire axis." In the introduction, he indicated that this was in contrast to the work of Hibbard,' who reported a single [111] texture after a reduction of 96.4 pct. Unfortunately Backofen stated that this was a reduction in area when actually it was a reduction in diameter, as is clearly stated in the reference. Moreover, the results of Backofen are in complete agreement with the results of Hibbard. Backofen's 97.3 pct reduction in area is an 83.3 pct reduction in diameter, after which he foundadouble [ll11 and[l001texture with the former predominating. Similarly, Hibbard; after an 86 pct reduction in diameter found a double [Ill] and [I001 texture with the former predom- inating. Hibbard, however, when he drew the wire further to 96.4 pct reduction in diameter, found primarily a single [Ill1 texture as illustrated by Fig. 2 of ref. 3. Here also, Hibbard- reported evidences of the [loo] recrystallization texture found by Backofen. It might also be pointed out that Backofen not only drew his wire 97.3 pct reduction in area but also etched them over 99 pct reduction in area from 0.125 to 0.01 in. diam. Hibbard's wires were drawn directly to size. In summary, the deformation texture of cold-drawn copper wire still may be described as primarily a single Clll] texture after a sufficient amount of drawing, such as 96.4 pct reduction in diameter." a

Jan 1, 1952

By Sherwin F. Kelly, Bela Low, William B. Creagmile

Electrical methods and instruments for geophysical exploration have been almost exclusively applied, during these years of development of the art, by a few companies specializing in this field. The control of patents, the cost of the instruments and the general lack of published information on details of field procedure and office interpretation have given these owners a monopoly in carrying out electrical surveys. The development of the Megger Ground Tester1 seems likely to change this situation, and to enable mining engineers and geologists, without special training in geophysics, to carry out simple reconnaissance electrical surveys. Nevertheless, the need for such special training and experience in planning surveys and interpreting their results remains, and probably i always will remain, indispensable for a successful outcome. The unique thing about, the Megger Ground Tester, which gives rise to this hope for its general use, is its simplicity of operation. The four binding posts of the instrument are connected by insulated wires to four stakes driven into the ground at appropriate points. The crank of the Megger is then turned, and the resistance of the ground between the two inside stakes is read directly, in ohms, by the deflection of a pointer over a scale. The apparatus is shown in Fig. 1. Fundamentally, the principle of operation is that of determining the resistance of a four-terminal conductor, as applied by Frank Wenner to the measurement of earth resistivity. "A four-terminal conductor is a conductor provided with two terminals to which current leads may be connected and two terminals to which potential leads may be connected. The resistance of such a conductor is the difference in potential between the potential terminals divided by the current entering and leaving

Jan 1, 1932

By G. H. F. Gardner

The boundary conditions F = 1.0 and 4 = 1.0 (100 per cent) are dictated by the definition of F in the equation 1/F = aFp. These conditions have physical significance as the "limiting conditions" for the observed behavior in systems of dispersed particles. The other boundary conditions, cited by Gardner in his Eq. 3 as applying to this system, have no significance in the systems we studied. Maxwell's equation (Eq. 2) cited in Gardner's comments was developed for and limited to a regular, rather than random, dispersion of spheres which are sufficiently removed from each other so that they do not interfere with current flow about their neighbors. These restrictions also apply to Rayleigh's analysis. The title of Rayleigh's paper cited by Gardner is "On the Influence of Obstacles Arrayed in Rectangular Order upon the Properties of a Medium". He is not discussing randomly dispersed spheres. It might be inferred from Gardner's comments that Rayleigh specifically considered the differential equation (Gardner's Eq. 3). This is not the case. Mathematically, Gardner's Eq. 3 is exactly true for the system to which it applies, however, as both Rayleigh and Maxwell note that their equation for F in terms of F is not for randomly dispersed spheres. At the time we wrote our paper, we were aware of the work of Wyllie and Gregory as cited by Gardner. We cited their work in Ref. 5 of our paper. Our comment on page 287 of the paper about the validity of an m value of 1.3 for spheres with a porosity of 38 per cent remains as our answer to Gardner's question on this point. Our data, at 38 per cent porosity, show that the condition a = 1 and m = 1.3 holds for spheres near 40 per cent porosity.

By G. W. Tower

THE YEAR 1931 was for most American copper producers one of restricted output but extremely low production cost.. When compared with 1929, the marked reductions in costs achieved in 1931, operating at rates in many instances a third to a half of capacity, can only be regarded as remarkable. In fact, the recent shut-down of several large operations suggests the probability that 1931 costs represent a bare minimum for many properties. Before discussing the 1931 results a few remarks on cost data are appropriate. The type of cost tabulation here presented was first published in 1929, (A. B. Parsons. E. & M. I. June 8, 1929), and has appeared each, succeeding year following in general the calculation method and company set-up of the original article. (. G. W. Tower, E. & III. L, July 8. 1930; S. D. Strauss, E. & M. J.; July 27, 1931). As far as possible the leading American copper companies are included. In considering these cost tabulations it must be borne in mind that the information from which they have been prepared is entirely contained in the annual report of each company; and that a multiplicity of interests and a condensed income statement for some of the larger companies, such as Cerro de Pasco and Kennecott, make the cost figure an arbitrary one depending upon sundry metal credits, metal products, miscellaneous income, etc. For Granby, Howe Sound. Magma, and Noranda, sundry metal credits are important. Furthermore Andes, Chile and Greene Cananea give costs only against copper sold. Although the individual costs here figured are by no means absolute they are computed by the same method each year and offer a basis of annual comparison; and with attention to footnotes the premises on which the costs are based may be easily followed.

Jan 1, 1932

By P. W. Andrews, R. B. Toombs

ECONOMIC STRUCTURE OF MODERN INDUSTRIAL ECONOMIES The role of minerals in modern industrial economies may be examined in several ways. There are relationships with the various sectors of the economy: the primary, secondary, and tertiary industrial groupings and activities. Mineral supply and demand activities can be measured in terms of national accounts criteria. The economic policy objectives of the modem industrial economy are based to a considerable extent on the needs of the nation for economic supplies of miner- al materials. There is an important role for minerals relative to national security in peace and in wartime and many national policies are directed toward ensuring adequate sup- plies of minerals. Environmental control in the modem industrial economy is increasingly concerned with matters related directly to the production and use of minerals and these matters, in turn, bear importantly on conservation in mineral supply and demand. Mineral polices include specific provision for research and development activities concerned with the production and the use of minerals. In all, national policy objectives will be shaped in considerable part by the circum- stances of mineral supply and demand: the relative degree of availability from domestic and foreign sources, the state of the mineral-processing industries, and the degree of development of the mineral-using industries, and per capita and total changes in requirements. Goods made from mineral raw materials are the basis of all advanced societies and although this is taken for granted, every country is continually dealing with problems of mineral supply and demand. Considering that in the first 50 years of this century the consumption of mineral materials in a highly Industrialized country such as the United States increased by six times while the population was doubling, it becomes apparent that if a country is to enjoy rapid economic growth it must have access to huge and ever-growing supplies of mineral materials at lowest possible cost. Adequate supplies of mineral materials and wise usage of mineral resources have always been among the most important determents of a nation's survival The importance of access to adequate mineral supplies is increasing every year and this has significant international, as well as national, implications because of the unique locational characteristics of mineral resources. It is generally acknowledged that no particular type of natural resource is essential to a high level of national income or to economic progress. A country's endowment of natural resources need not exercise a determining influence on the course of its national income over time, provided it is able to trade. What is required for economic progress is the availability of a substantial quanti-

Jan 1, 1976