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By M. R. Tek, F. H. Poettmann, M. L. Grove

The general problem of single-phase natural gas flow through porous media has been considered both by mathematical analysis and field experiments. Theoretical studies on the fluid dynamics of natural gas wells resulted in derivations of expressions which permit a ber-ter understanding of the flow mechanism for conditions under which Darcy's law is no longer valid. In applying these results to natural gas production and testing technology, special emphasis war placed on the study of low permeability, slowly stabilizing formations. These applications resulted in a method of predicting the performance coefficients of tight natural gas wells. The calculation of the performance coefficient requires the determination of the "test-index", pkh/µ, the drain- age radius, R, and the effective wellbore radius, rw. Methods for estimating these parameters from field data were also developed. Field data from 15 wells were collected and analyzed. The measured values of the performance coefficients were compared with the predicted values. This statistical evaluation gave a bias of 7.14 per cent and a standard deviation of 11.6 per cent. INTRODUCTION The performance of a natural gas well is determined by the physical properties of the reservoir rock, the extent and the geometry of the drainage area, the properties of the flowing fluid, and the conditions of pressure distribution within the drainage matrix. The relation between the quantity of gas delivered and the pressure drop within the reservoir is characteristic of the behavior of each well and is often referred to as the back-pressure behavior of the well. It is well established that for normal, single-phase gas wells the relationship between the gas delivery rates and the bottom-hole pressure take, in general, the form, Q = c(P3 8 -P2 1)n. ,.......(1) where C is the performance coefficient, and n is the exponent corresponding to the slope of the straight-line relationship between Q and (P2 s, — P2 l) plotted on logarithmic coordinates. The determination of a well's performance by the back-pressure behavior not only permits the production engineers to analyze many operating problems, but also provides necessary information useful and essential to predict the future development of the field.' Important engineering and production problems such as calculation of gas deliverability into a pipeline at a predetermined line pressure, design and analysis of gas-gathering lines, determinations of spacing and number of wells to be drilled during field development to meet future market or contract obligations, etc., all depend, at least in part, on the availability and use of reliable back-pressure curves.' In the past the behavior of gas wells was evaluated

Jan 1, 1958

By Evans B. Mayo

As a result of studies distributed over the earth- including ocean basins as well as continents- some tectonists recognize four dominant structural trends: 1) northwest; 2) northeast; 3) nearly east- west, or equatorial; and 4) nearly north-south, or meridional. Baker' proposed a theory to account for these trends and Sonder5 called their world-wide arrangement the regmatic shear pattern. Moody and Hill6 proposed a much more complicated shear network which, although fascinating and perhaps ultimately useful, will not be followed here. In a recent review of deformation within the Cordillera, Wisser7 mentioned the four fundamental directions. The fact that many geologists deny the existence of the regmatic shear pattern implies that the fundamental structures are far from obvious. It may mean, also, that some geologists are not accustomed to examine regional and world maps analytically. The maps require much study, and certain features, should be isolated on overlays. Even so, with the present limited knowledge, uncertainties remain. The following analysis is a qualitative experiment, subject to change as information accumulates, and should be supplemented by the western sheet of the Tectonic Map of the United States.8

Jan 11, 1958

By C. D. King

THIS year the American Institute of Mining and Metallurgical Engineers celebrates its seventy-fifth anniversary as well as the same anniversary of iron and steel in this country as we now know it. The society's span of life comprehends the very beginning and gradual development of the present-day iron and steel industry and its TRANSACTIONS are rich with the trials and achievements of the pioneers in this field. It is difficult to believe that in the first year of the Institute's existence there was produced in this country only 84,000 net tons of ingots, of which only 2000 tons was made by the open-hearth process; that the bessemer process was just barely beginning; that charcoal and anthracite were virtually the only blast-furnace fuels; that Mesabi ores had not been used in blast furnaces, and such pig iron as was then made was produced at a number of small units, each adjacent to its ore and fuel supply. The growth from 84,000 net tons production of steel ingots to 95,500,000 tons in 1945 eloquently tells the story of America's industrial growth.

Jan 1, 1947

By D. Turnbull, R. E. Cech

FISHER, Hollomon, and Turnbull have developed a theory for the nucleation of martensite. They first tested the theory on Fe-C alloys and low alloy steels. The major factor influencing nucleation of martensite was considered to be statistical composition fluctuations occurring in small regions at high temperature and frozen-in on quenching. These local regions of varying size and composition serve as nucleation centers. They become supercritical, one by one, as temperature is progressively lowered, resulting in temperature-dependent or athermal transformation. Fisher next applied nucleation theory to substi-tutional solid solution alloys. Detailed predictions were made for Fe-Ni alloys because of the availability of free energy data on this system. It was shown that composition fluctuations that were significant energy-wise did not occur, and nucleation frequencies could be calculated from average properties of the system. Nucleation was predicted to occur as time-dependent and having the functional relationship to give a C curve of nucleation frequency vs temperature. The analysis further predicted that the nucleation frequency was extremely sensitive to composition. Experimentally, it would be found that the transformation in some compositions is so slow that measurable amounts will not form in a reasonable length of time. With other compositions, only slightly different, the nucleation frequency becomes so great that the material becomes transformed while still distant in temperature from the maximum nucleation frequency. On quenching an alloy of such composition, the observed transformation kinetics would be similar to those found in Fe-C alloys. Cech and Hollomon repeated experiments of Kurdjumov n which the kinetics of transformation were similar to those predicted by Fisher for Fe-Ni alloys. The alloy studied in this investigation contained 73.3 pct Fe, 23.0 pct Ni, and 3.7 pct Mn. Fisher,' using an idealized model for the extent of transformation as a function of the number of martensite crystals per grain of parent phase, derived nucleation frequencies from the transformation curves of Cech and Hollomon. Complicating influences such as coupling effects between grains in the polycrystalline specimens were neglected. Nevertheless, excellent agreement was found between the theoretically and experimentally derived nucleation frequencies. These experiments, however, could not provide a critical test of the theory. Experimental nucleation frequencies could vary widely from those calculated, depending upon the extent of deviation from ideal partitioning and the extent of coupling effects. Further, since the compositions of material theoretically analyzed and experimentally determined were different, the free energy changes involved in the experimental work could only be estimated. Also, the effect of heterogeneities on the transformation kinetics was not considered. For these reasons, it was decided that experiments designed to test the validity of the Fisher analysis must be conducted on binary Fe-Ni alloys, which were the ones considered theoretically by Fisher. The martensite transformation in Fe-Ni alloys has been the subject of considerable study. Machlin and Cohen have shown that transformation proceeds in a manner quite unlike that in any other ferrous alloy system. They found that single crystals would transform to a large extent in a single burst. In large grain polycrystalline specimens, frequently more than one grain and sometimes the whole specimen would transform at the same instant in this manner. Results on filings indicated that different particles would undergo the burst transformation at widely different temperatures. These results support the conclusion that the transformation behavior could not be described by a single nucleation frequency as would be the case if the nucleation were homogeneous. It appeared that further work was necessary to define the factors responsible for burst-type transformation, so that the conditions could be altered to favor homogeneous nucleation of martensite if such could be accomplished. This report summarizes the results of some experiments conducted with powdered Fe-Ni alloys for this purpose and the re-

Jan 1, 1957

By James H. Pannell, John Dasher, Wilfred L. Freyberger, A. M. Gaudin

A new sorting process for beryllium minerals is described. This depends upon emission of neutrons upon irradiation by gamma rays, a nuclear reaction which is specific for beryllium at the appropriate energy level. Signals given by neutrons when ore passes on a belt are changed to mechanical commands through amplifiers and other electrical equipment.

Jan 4, 1950

AT THE beginning of February the British Government announced acceptance of the American terms for funding the war debt, the main features-being as follows: Interest rate of 3 per cent. for the first 10 years and then 3 ½ per cent. up to the final extinguishment of the debt at the end of 62 years. The interest from the time since the loans were made to the actual beginning of the funding arrangement to be recomputed at 4 1/4 per cent. instead of the 5 per cent. rate now in effect. Congress ratified the contract respecting the British debt. The ship subsidy bill was relegated to the rear, which is indeed an end to the project. The natural consequence of this will be a liquidation of the Govern-ment's shipping business. The joint committee on the reorganization of Govern-ment departments made its report to the President. In general this seems to offer a well-considered plan for the coordination of Government service. The pro-posals respecting the bureaus that are particularly associated with the mining industry may be subject to criticism. According to the committee's plan, the Geological Survey remains in the Department of the Interior, but the Bureau of Mines and the compilation of the statistics of mineral production are transferred to the Department of Commerce. The Lausanne conference among the European powers came to an end early in February, without any treaty having been signed, owing to the refusal of the Turks to accept the ultimatum of the Allies. Theoreti-cally this left conditions in a state-of war between the Allies and Turkey. However, no actual movements have resulted. The French and Belgians continued to hold the Ruhr district of Westphalia, extending their lines and administration of the region. The Germans adhered to the policy of passive resistance. In the Parliament of Great Britain the French and Belgian policy was plainly declared to be unwise and dangerous. French and Belgian industries, moreover, were troubled by strikes among their own coal miners for higher wages. The Poles and Lithuanians engaged in border war-fare;. the civil war in Ireland continued. The rest of the world was quiet insofar as military operations are concerned.

Jan 2, 1923

By E. T. Peters, L. E. Tanner

In the course of a study concerned with the rnechanical behavior of the intermetallic compound CO3V, both structural observations and anomalous electrical-resistivity behavior indicated the presence of a new high-temperature phase in an alloy with the stoichiometric composition, Co-22.4 wt pet V. The evidence, which is given below, suggests that the new phase is situated between the low-temperature ordered hexagonal phase, k,1, 2and the high-temperature disordered fee solid solution, a,3 within a small range of temperature in the vicinity of 1070°C. Structural studies included X-ray diffraction analysis* and electron-transmission microscopy examination* of stoichiometric composition speci- mens homogenized for 1 hr at 1200oC and either air-cooled or water-quenched. The air-cooled specimens yielded X-ray diffraction evidence of the k phase, while electron microscopy revealed a microstructure of both heavily and moderately faulted regions as shown in Fig. 1. The high density of stacking faults (or fine twins) in region A is reminiscent of hexagonal cobalt following its allotropic transformation.4 Selected-area diffraction from this region revealed distinct superlattice reflections of the ordered hexagonal phase, as well as continuous rel-streaks which were normal to the fault planes in the micrograph. The latter is indicative of extremely small spacings between the faults.' Regions such as ß were found to be only partially transformed to the k phase. Attempts to study the antiphase domain structure by either bright- or dark-field techniques were unsuccessful in these initial studies. This was due to the low intensity of the superlattice reflections arising from the closeness of the cobalt and vanadium scattering factors. Quenching Co3V from above Tc appears to suppress the formation of the k phase. Both X-ray and electron-diffraction results indicated that the disordered phase, a, was partially ordered during severe cooling and that the structure of the ordered phase was of the L12 (Cu3Au) type,6 designated here as a'. As in the case of the hexagonal phase, examination of the domain structure was unsuccessful; however, significant information concerning the morphology of this condition was revealed by the appearance of dislocation arrays. In particular, it

Jan 1, 1965

By Jack M. Jodrey, Neil D. Donnell, O&apos

Bituminous sands of the Lower Cretaceous McMurray Formation in northern Alberta constitute the ore for the surface mining operation at Syncrude Canada Ltd. These sediments represent a complex succession of fluvial, estuarine and marine depositional environments. Grade prediction is realized through a combination of geological interpretation, computer modeling, and reference to past mining experience. Accurate forecasts of feed grade permit reliable predictions of volumes for removal to meet budgeted synthetic crude oil production. This planning facilitates efficient allocation of mining equipment and resources. The feed grade to the Extraction Plant is monitored at various points along the delivery system.

Jan 1, 1985

By G. W. P. Rengstorff, L. E. Olds

High purity molybdenum ingots containing controlled amounts of a single impurity element (oxygen, nitrogen, or carbon) were prepared. These ingots were tested for ductility by bending test specimens at various temperatures. The relationship between the plastic behavior of the ingots and their chemical composition has been determined. MANY proposed applications for molybdenum require ductility at or near room temperature. At the present time, it is possible to obtain wrought molybdenum with considerable ductility only if special fabrication techniques are used to control the grain structure. Starting with are-cast or powder metallurgy ingots, the usual methods for obtaining ductility rely on fabrication procedures that result in fibered microstructures in the finished product. Recently, it has been found that the ductility of either powder metallurgy or are-cast molybdenum can be improved by uniform recrystallization of the metal to a very fine equiaxed grain structure.' The need for a fibered or a fine grained structure may limit the practical usefulness of molybdenum. For example, welding. which may be used in fabricating the metal, generally produces coarse grained structures that lead to brittleness. This applies, certainly, to currently available commercial molybdenum. Although commercial molybdenum is brittle when the grains are coarse, it has been shown experimentally that fine grained structures are not always essential for ductility. For instance, as-cast molybdenum with a coarse columnar grain structure is ductile if it is sufficiently pure.' Because high purity cast molybdenum has good ductility even when coarse grained, it is probable that the brittleness in coarse grained commercial molybdenum is caused by the impurity content of the metal. Although the general effects of impurities on the cold ductility of molybdenum have been known in a qualitative manner for some time, no quantitative evaluation of these effects has been available. The present investigation was made in order to determine more accurately the effects of oxygen, nitrogen, and carbon on the cold ductility of cast molybdenum. Oxygen has long been known to be detrimental to ductility, although the minimum amount which will embrittle molybdenum has been open to speculation. Parke and Ham" showed that ingots with oxygen contents above 0.003 pct could not be forged. Maringer and Schwope have described the embrittle-ment of molybdenum wire by oxygen. A discussion on the effects of heat treatment on the distribution of oxygen in molybdenum has been given by Perry, Spacil, and Wulff." Although nitrogen would also be expected to have harmful effects on ductility, no extensive work has been done previously to determine whether this is so. However, Tury and Krausz" found that wires presumably with less than 0.007 pct N were brittle. Carbon is added to commercial cast molybdenum for deoxidation. Parke and Ham" have shown that molybdenum containing as much as 0.06 pct C could be forged if the oxygen was kept below 0.003 pct. Also, Bruckart and others' found that the room temperature ductility of sintered molybdenum improved with carbon contents up to 0.84 pct. However, Rengstorff and Fischer' found that residual carbide particles in cast molybdenum apparently had an unfavorable effect on room temperature ductility.

Jan 1, 1957

By M. R. Tek, K. H. Coats, D. L. Katz

The nature and the limits of validity of Darcy's law US applied to the flow of natural gas through reservoirs has been considered in order to resolve some controversial aspects of the effect of turbulence on pressure drops. The equivalence between various concepts and viewpoints advanced in the past by several investigators to explain how and why a gas well does not necessarily perform according to Darcy's law is shown. Starting with generalized equations of flow of fluids through porous media, a partial differential equation has been derived which accurately represents the flow at all rates. This equation has been numerically solved using an IBM 704 digital computer. The results permit plots of unsteady radial pressure distribution curves from which specific isochronal backpressure curves may be constructed. These back-pressure curves show the effect of the ,8 factor on the slope of the back-pressure curve. The calculations further indicate that the drainage radius for a gas well in turbulent flow propagates at a rate dependent upon the rate of production at the wellbore. This is quite different from the case with liquid flow or natural-gas flow in laminar regime. Additionally, the effect of reservoir inhomogeneities and crossflow between layers of different permeability on the back-pressure performance of gas wells has been conridered. In light of the current numerical results the significance and linlitation of the rate of flow function Y proposed by Smith" has been discussed. INTRODUCTION The relationship between the pressure drop and flow rate in problems of fluid flow through porous media is known to be affected by the nature of flow through the porous matrix. It has been observed by many that, for a range of flow rates, the pressure drop remains proportional to the rate of flow. When some flow rate is reached, however, it is usually observed that the pressure drop gradually begins to increase more than proportionally to the flow rate. It is well known that this phenomenon was first observed by Osborne Reynolds in 1901 in experimenting with flow through pipes. In his classical experiments, Reynolds made visual observations on the condition of streamlines evidenced by injecting a dye into water flowing through glass tubes. In these experiments, the abrupt transition between steady, "streamline, laminar" flow and unsteady random turbulent flow was found to be a function of the dimensionless group (Dvp/u), now known as the Reynolds number. During these experiments, in addition to observations on the nature of flow regimes, the proportionality between flow rate and pressure drop in laminar flow was contrasted with the nonlinearity between these variables in turbulent flow. Fancher and Lewis' reported data on various consolidated and unconsolidated sands in 1933. Their conclusions were that ". . . the flow of fluids through these porous materials closely resembles that through pipes; that there is a condition of flow in porous systems which resembles viscous flow, another which corresponds to turbulent; that the change from one type to the other takes place at a definite and reproducible condition for each system". In 1947, Brownell and Katz published a method to predict the laminar and turbulent flow behavior from the particle size, bed porosity and the particle sphericity, employing the friction factor-Reynolds number charts for pipes. Several investigators have verified the work of Fancher, Lewis and Barnes and presented their data as friction factor-vs-Reynolds number plots.' The equation which would represent the pressure gradient over the whole range of velocity must have an added term over that represented by Darcy's law. Accordingly, the pressure gradient necessary to sustain flow at the velocity (v) through a porous medium may be represented by the following equation, suggested by Forscheimer." The nature and the range of validity of Darcy's law has been the subject of studies by many investigators over the past years. While everyone seemed to agree on the need for a quadratic correction term to Darcy's law to make it effective over the range of velocities, the concept of inception of turbulence and the use of the term "turbulent flow" remained controversial. Some fluid dynamicists define turbulence as a flow

By Dermot Macaragh Ross-Brown, Brian Stimpson

Borehole information is often the only source of information on rock conditions at depth during the stage of feasibility studies of a project, and from this data the rock mechanics engineer would like to make some quantitative estimates of rock mass cohesive strength. While judgement and experience will usually play a paramount role at this stage, simple tools for estimating rock mass cohesive strength would be an asset. In this paper, an approximate technique is suggested for assessing the cohesive strength of a randomly jointed rock mass from borehole data on fracture intensity and intact rock strength.

Jan 1, 1980

By Wm. Reuben Webster

BRASS is an alloy of copper and zinc. The brasses (using this term to denote all useful proportions of the two constituents) are the most valuable and widely employed of all [ ] nonferrous alloys, because of their high resistance to ordinary corrosive agencies and the very wide range of properties that may be imparted to them by variations in the proportions of the constituents and by variations in mechanical treatment and heat-treatment. Fig. I shows the normal physical properties, as determined by standard tensile tests, of the series when in the annealed condition. Fig. 2 shows the effect of varying amounts of cold-working on an almost pure brass containing 70 per cent copper and 30 per cent zinc. Fig. 3 shows the effect of annealing at various temperatures on the same alloy. This effect is somewhat modi [ ] fled by the degree of cold-working to which a brass has been subjected, as shown by Fig. 4. A fourth test, which is empirical, has been found useful because of its simplicity -the hot hammer test. Samples Y2 in. in diameter and ¾ in. long are placed in a suitable furnace. These are withdrawn one at a time at successively higher tempera¬tures and are subjected to the blow of a drop hammer weighing 50 lb. with a drop of 4 ft. The percentages of' reduction in length of the cylinders are plotted against temperatures and give a comparative measure of plasticity at different temperatures. The results of this test on several

Jan 1, 1942

By Wm. Reuben Webster

Brass is an alloy of copper and zinc. The brass containing 70 per cent copper and brasses (using this term to denote all useful 30 per cent zinc. Fig. 3 shows the effect of proportions of the two constituents) are the annealing at various temperatures on the most valuable and widely employed of all same alloy. This effect is somewhat modi- nonferrous alloys, because of their high resistance to ordinary corrosive agencies and the very wide range of properties that may be imparted to them by variations in the proportions of the constituents and by variations in mechanical treatment and heat-treatment. Fig. I shows the normal physical properties, as determined by standard tensile tests, of the series when in the annealed condition. Fig. 2 shows the effect of varying amounts of cold-working on an almost pure fied by the degree of cold-working to which a brass has been subjected, as shown by Fig. 4. A fourth test, which is empirical, has been found useful because of its simplicity —the hot hammer test. Samples 1/2 in. in diameter and 3/4 in. long are placed in a suitable furnace. These are withdrawn one at a time. at successively higher temperatures and are subjected to the blow of a drop hammer weighing 50 lb. with a drop of 4 ft. The percentages of reduction in length of the cylinders are plotted against temperatures and give a camparative measure of plasticity at different temperatures. The results of this test on several

Jan 1, 1942

By Wm. Reuben Webster

Brass is an alloy of copper and zinc. The brass containing 70 per cent copper and brasses (using this term to denote all useful 30 per cent zinc. Fig. 3 shows the effect of proportions of the two constituents) are the annealing at various temperatures on the most valuable and widely employed of all same alloy. This effect is somewhat modi- nonferrous alloys, because of their high resistance to ordinary corrosive agencies and the very wide range of properties that may be imparted to them by variations in the proportions of the constituents and by variations in mechanical treatment and heat-treatment. Fig. I shows the normal physical properties, as determined by standard tensile tests, of the series when in the annealed condition. Fig. 2 shows the effect of varying amounts of cold-working on an almost pure fied by the degree of cold-working to which a brass has been subjected, as shown by Fig. 4. A fourth test, which is empirical, has been found useful because of its simplicity —the hot hammer test. Samples 1/2 in. in diameter and 3/4 in. long are placed in a suitable furnace. These are withdrawn one at a time. at successively higher temperatures and are subjected to the blow of a drop hammer weighing 50 lb. with a drop of 4 ft. The percentages of reduction in length of the cylinders are plotted against temperatures and give a camparative measure of plasticity at different temperatures. The results of this test on several

Jan 1, 1942

By P. Hazebroek, C. S. Mathews, E. E. Allen, H. C. Lefkovits

A rigorous study was made of the behavior of reservoirs composed of horizontal layers, unconnected except at the well and filled with a compressible fluid. The report is presented in two parts. Part I deals with the practical implications of the results obtained; Part 11 contains the mathematical derivation of the solution. The main portion of Part I is concerned with application of the results to reservoirs composed of two layers. Relative rates of depletion of the layers are studied, and it is shown that differential depletion between layers exists in the transient stage of the reservoir, which generally is of an order of magnitude longer than the transient stage in a single-layer reservoir. In the transient stage, the more permeable layer is depleted faster than the less permeable. However, the reservoir approaches a steady-state situation where both layers contribute equally to production. Theoretical build-up curves from such reservoirs are presented, and the influence of a skin effect and flow into casing and tubing are also evaluated. The build-up curves are predicted to have, first, the familiar logarithmic straight-line section and, subsequently, a rising and flattened section. The results found are compared with an extension of an approximate theory, and it is found that this simplified theory is applicable over most of the life of the reservoir. Extensions to reservoirs containing more than two layers are indicated, and examples of the performance and build-up curves for three-layered reservoirs are presented. The theoretical results on build-up curves were applied to field examples of such reservoirs, and satisfactory results were obtained. From the build-up curve, the pemeability-thickness product, the wellbore damage and the static pressure are obtained. However, it apparently is not possible to determine the properties of the individual layers from the combined build-up curve. A large number of reservoirs have been found where the producing formation is composed of two or more layers of differing physical characteristics, such as permeability and porosity, and where also the thicknesses of the layers differ. Since in general a differential depletion should exist between the layers of such reservoirs, it would be advantageous to know the amount of the differential depletion under a given production history. It also would be valuable to know the pressure behavior, because it could be undesirable to produce a reservoir in such a manner that the pressure in one of the layers would have fallen below the bubble point of the oil at a time when another layer might still be virtually undepleted. The determination of static pressures in shut-in wells with slow build-up is another feature of importance in layered reservoirs. If the behavior of the reservoir differs appreciably from the predicted behavior of a single-layer reservoir, the type of analysis for build-up curves suggested for single-layer reservoirs is not applicable. Several authors have treated the problem of finding the pressure and production characteristics of multilayer reservoirs. Horner treated the problem of n layers in an infinite field, the layers being connected only at the well. Tempelaar-Lietz2 has presented an approximate treatment of the characteristics of a bounded reservoir composed of two layers of different permeabilities and equal thicknesses. Homer gave no information on differential depletion between layers, and the treatment of Tempelaar-Lietz was not applicable for prediction of pressure build-up behavior. In addition, it was thought that a more rigorous treatment than the one by Tempelaar-Lietz would be valuable in determining the range of validity of this solution. The present study, therefore, was made of a bounded reservoir composed of two or more layers,

W. Morton Webb, Germiston, Transvaal, South Africa (communication to the Secretary*):—The experience of Mr. Boeh-mer in the Leadville district and his reputation as an engineer assure the interest of anything he may write on the ore-bodies of that district; and all engineers who have operated in Leadville will agree that the theory of the origin of the Leadville deposits, as given by Mr. Emmons in his famous monograph, does not adequately explain the genesis of all the deposits. The solutiou of the problem does not, however, appear to be quite so simple as Mr. Boehmer would make it; and the advance pamphlet issued by the U. S. Geological Survey, pending the completion of the main report, shows that there is still much ground for controversy. No doubt the later eruptive0 had a greater influence on the deposition of the ore-bodies than was thought at the time of the first investigation by the Survey; but it has always appeared to me that the influence exerted by these dikes mas more in the nature of a physical than a chemical one. The weight of evidence in recent years is mostly in the direction of ascension rather than lateral secretion; and one of the strongest evidences is the fact that most of the ore-bodies lie under one of the comparatively impervious layers which help to make up the structure of these hills.

Jan 1, 1911

By M. D. Banus, M. B. Bever, A. K. Jena

The heals of formation at 78", 195, and 273°K of the ternary compound h3SbTe2 based on the elements and based on the binary compounds In Sb and [inTe have been measured. The heats of formation at these temperatlcres of the binary compounds In Sb and In Te based on the elements have also been determined. Heal contents and free energies of the three compounds have been calculated from 0° lo 80I)°K. The free energies of joyrrzalion, heats of formations, and entropies of formation at 298°K have also been calculated. The results shown that the tertnary compound is metastable with vespecl to InSh and ln Te below 696 °K. bul is slable above that temperature. The weaker bonding of results in a positice entropy of formation which with incrensirzg temperature makes increasing negative conlvihtclions to the free energy and above 696°K renders the compound slable. THE ternary compound In3SbTez occurring in the quasi-binary system In Sb- In Te' forms on cooling at 829°K by a peritectic reaction.' Observations at 673" and 573 K have shown that this ternary compound decomposes slowly into the binary compounds InSb and1n~e.l'' It has not been possible to analyze the metastable behavior of the ternary compound because up to the present time data on its thermodynamic properties have been lacking. Some information on the binary compounds, however, is available. The heat of formation of InTe at 273°K and its free energy at 673°K are kn~wn.~'~ The heats of formation of InSb at 78", 273', 298", and 723°K have been measured5-' and its heat capacity between approximately 12" and 300"Kg9l0 is also known. In the investigation reported here the heats of formation at 78% 195% and 273°K of the ternary compound In3SbTez have been measured. The heats of formation of the binary compounds InSb and InTe at these temperatures have been obtained by combining new calorimetric results with previously published data. The heat contents and free energies of the three compounds at various temperatures from 0" to 800°K have been calculated. Against the background of this information, the metastability of the ternary compound will be discussed. 1) EXPERIMENTAL 1.l) Preparation of Specimens. The materials used consisted of the elements indium, antimony, and tellurium, the binary compounds InSb and InTe, and the ternary compound In3SbTez. The elements, obtained from American Smelting and Refining Co., had a nominal purity of 99.999+ pct. The compound InSb was Cominco semiconductor grade; the compound InTe was prepared from the elements by melting under a vacuum of 10-h m Hg followed by slow cooling. Three batches of specimens of the compound In3SbTez were used. One batch was prepared by melting appropriate amounts of the elements in an evacuated and sealed Vycor tube. The melt was held at approximately 100°K above the liquidus for about 8 hr, shaken repeatedly, and quenched into a mixture of ice and water. The specimen was annealed in vacuum at 760°K for 4 weeks. In preparing a second batch, a mixture of the component elements was melted and quenched in water. The resulting ingot was powdered. The powder was pressed into pellets, which were annealed in vacuum at 748" to 773°K for 4 weeks. A third batch was prepared in the same manner as the second, except that the starting materials were InSb and InTe rather than the elements. Metallographic examination of samples of the three batches and X-ray diffraction examination of a sample of the second batch did not reveal evidence of microsegregation or a second phase. The results obtained with the three batches showed no systematic differences. 1.2) Calorimetry. The calorimetric method has been described in detail." Samples of the compound In3SbTez, mechanical mixtures of InSb and InTe in the proportion of 1:2, and mechanical mixtures of indium, antimony, and tellurium in the proportion of 3:1:2 were added to a bismuth-rich bath at 623°K in a metal-solution calorimeter. These additions were made from 78°K (liquid nitrogen), 195°K (dry ice and acetone), and 273°K (ice and water). The heat effects of the additions were measured. The difference in the heat effects of the additions of a compound and the additions of the mixtures of its constituents, adjusted for differences in the concentration of the bath, is the heat of formation of the compound. In the concentration range not exceeding 1.5 at. pct solute, the heat effect of the additions was a linear function of concentration. The heat of formation refers to the temperature from which the additions were made, namely, 78", 195", or 273°K. Several calibrating additions were made in each calorimetric run. The calculated heat capacity of the calorimeter and hence the calculated heat effects of the additions of samples depend upon the values adopted for the heat contents of the calibrating substance. In this investigation bismuth at 273°K was used and a value of 4.96 kcal per g-atom was taken for (HGZ3"k . 2) RESULTS AND DISCUSSION 2.l) Heats of Formation. The heats of formation of the ternary compound In~SbTez from the component elements indium, antimony, and tellurium and from

Jan 1, 1968

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

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

Jan 1, 1968

PRESIDENTS DAVID THOMAS 1871 Born November 3, 1794, Cadoxtan, Glamorganshire, South Wales. Died in 1882. Attended schools in Wales. Came to America in 1839. A.I.M.E.: Member, 1871; Honorary Member. Iron manufacturer; inventor. Built first anthracite fired hot-blast furnace in America. Known as the "Father of the Lehigh Valley." President, Catasauqua and Fogelsville Railroad; Director, Lehigh Valley Railroad; Founder, Thomas Iron Co. and St. Luke&apos;s Hospital at Bethlehem, Pa.; Trustee, Lafayette College.4 ROSSITER WORTHINGTON RAYMOND 1872-1874 Born April 27, 1840, Cincinnati, Ohio. Died in 1918. Brooklyn Polytechnic Institute, 1857; Lafayette College, Ph.D., 1868; Lehigh University, LL.D., 1906; University of Pittsburgh, Hon. LL.D., 1915., Gold Medal, Institution of Mining and Metallurgy (London). A.I.M.E.: Founder, Member of 1871; Vice President, 1871, 1876-1877; Secretary, 1884-1911; Secretary Emeritus, 1911-1918; Honorary Member. Consul¬ing mining engineer; practicing lawyer, sailor, soldier, writer, orator, editor, theologian, teacher, novelist, chess player. Recognized as the "Grand Old Man of the Institute." ALEXANDER LYMAN HOLI,EY 1875 Born July 20, 1832, Lakeville, Conn. Died in 1882. Brown University, 1853; Hon. LL.D., 1878. A.I.M.E.: Member, 1871; Vice President, 1874; Manager, 1877-1879. Bessemer Medal (Iron and Steel Institute, London), posthumously. Brought bessemer process to United States. A statue was erected in Washington Square in his memory and presented to the City of New York in 1889. The inscription notes: "foremost among those whose genius and energy established in America and improved throughout the world the manufacture of bessemer steel." ABRAM STEVENS HEWITT 1876 Born July 31, 1822, Haverstraw, N. Y. Died in 1903. Columbia University, 1842; Hon. LL.D., 1887. A.I.M.E.: Member, 1871; Manager, 1872-1875. Bessemer Medalist and Honorary Member, Iron and Steel Institute (London). Gold Medal, Chamber of Commerce of New York City. Philanthropist, lawyer, statesman, publicist, pioneer in the iron and steel industry. Mayor of New York City in 1887. Business partner of Peter Cooper, Executive Manager of Board of Trustees, Cooper Union, New York City.

Jan 1, 1947

By M. G. Corson

Until recently, the characteristics of cast copper have seldom been studied and such study as has been made has been inadequate. The prevailing idea seems to be that since pure copper is infrequently used in the cast stlate, there is no reason for trying to establish precise data regarding the properties of the metal in that condition. On the other hand, wrought copper either in the shape of sheets or wire rarely fails in service, except as a result of the action of reducing gases at the annealing temperatures, so there is little incentive to study the properties of the cast shapes —cakes, bars, ingots and billets—for the sake of tracing the causes of failures of the wrought metal to the cast stock. However, about a decade ago, wirebars of American origin often cracked badly while being hot-rolled in mills in Germany. This Icd to four investigations: by E. Seidl and E. Schieboldll by P. Siebe12 by 0. Bauer and G. Sachs,3 and by G. Welter.4 These authors came to the conclusion that failures in hot-rolling were due essentially to the presence of a wide zone of columnar crystals between t&apos;he thin layer of fine crystal5 near the surfaces of the bars and the large but more nearly equiaxed grains of the central core. This macrostructural defect was explained in turn by the probable upward deviation in the temperature of the metal while it was being poured into the molds of the castling machine. More recently, cast shapes of copper were investigated by X. 1&apos;. Allenh and by C. Blazey. Allen examined vertically cast wirebars and hori-zontally cast wedge cakes of electrolytic tough-pitch copper, but only for the distribution of densities; i.e., porosity. Blazey was interested mainly in the mechanism of the variations in electrical conductivity due to cold-work and anneal, but gave introductively an account of the composi-tion and average densities of the tough-pitch horizontally cast Wirebars used. As far as the present writer can tell, no investigation mas under-taken for the sake of presenting a picture of the distribution of mechanical characteristics in the wirebars of copper, or otherwise.

Jan 1, 1938