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By Russell Dayton

THE metallurgical polarization microscope has been utilized in several researches in the last few years, thus attaining a fair degree of prominence, but little has been written in a manner suitable to a metallurgist concern-ing the theory of this instrument. In this investigation the theory was carefully studied, and the results are presented here in a detailed manner, yet as simply as possible. The theory is discussed with particular reference to the three chief functions of the instrument: (1) determination of anisotropy; (2) effect of strain; and (3) identification of inclusions. Each of these is investigated experimentally, with especial attention to the mechanism of producing any effect. Where possible, the discussion is supplemented by photomicrographs. The instrument used had numerous defects as a polarization microscope; these and their remedies are discussed. In the microscopic study of transparent mineral sections (chal-cography) the use of polarized light has aided tremendously in the identification of a mineral. The determination of strain in transparent substances (photoelasticity) by the use of polarized light has lately become a commercial process, used in testing finished glass articles. The success of the use of polarized light with opaque materials has not been so great. The magnitude of the effects obtained is much less than that of the corresponding effects with transparent materials, and the mechanical difficulties are much greater. Konigsberger,(1)? in 1909, was the first to apply polarized light to the microscopic study of

Jan 1, 1935

By H. E. McKinstry

MOVEMENT on a fracture of irregular shape can cause local widening of the fissure and thereby offer freer channelways for circulation of ore-depositing solutions. This influence, coupled with large areas of wall rock available for reacting with ore solutions in brecciated and shattered ground can account for locally active deposition of metals and the resulting ore shoots. Such irregularities in the fracture system may be caused by local variations in the strength of rocks and by pre-existing lines of weakness, especially if these stand at favorable angles to certain components of the fracturing stress. Therefore correct interpretation of the mechanics of fracturing should permit deductions as to structurally favorable places on unexplored portions of the vein system. INTRODUCTION IT has long been recognized that movement on a curved or irregular fault surface is capable of separating the walls in certain portions of the fault, but until very recent years the importance of this mechanism as a factor in localizing ore shoots has escaped proper recognition. A short time ago W. H. Newhouse' presented a careful analytical study of displacements and their corresponding open spaces. For reasons that will be discussed later, it frequently happens that portions of the vein which are favorably oriented are not merely wider but also richer than the average. In many cases the widening with its accompanying richness coincides with very minor changes in the dip or strike of the vein, irregularities that commonly escape notice unless the vein is mapped in detail and a careful geometrical analysis made. While the relationship between the width of the vein and the changes in dip or strike has been recognized as a matter of observation, the irregularities have been accepted as more or less the result of accident. There has been very little effort except in isolated cases to find out the causes of these changes in dip or strike. Yet it is clear that if the causes can be recognized and expressed in terms of geologic structure the geologist will know where to look for repetitions of these favorable conditions either on extensions of the same vein or on adjoining veins. Any lack of understanding of the causes is due to the limitations of our ability to interpret our observations and not to the sheer capriciousness of

Jan 1, 1941

By R. Simon

Maurer's review1 summarizes quite thoroughly the various theoretical developments and experimental findings that contribute to the knowledge of rock mechanics in drilling. This discussion supplements Maurer's paper by including generalities that either have been incompletely treated in his review, or formulated from new considerations by the discussant and from hitherto unpublished experimental data. These generalities are associated with the observation that all mechanical methods of rock drilling essentially comprise a sequence of indexed, concentrated loadings on the bottom of the hole being drilled. A concentrated loading is defined as a mechanical loading by a tool that contacts at any one time only a small fraction of the surface of the body being worked and penetrates only a small fraction of the body thickness. The surface in this application is the bottom of the hole. The deformation of ductile material by concentrated loading has received considerable attention because of the importance of indentation tests for measuring hardness of metals. Some of the generalities involved in concentrated loadings on ductile materials apply also to concentrated loadings on more brittle materials such as rock. Among these generalities is the applicability of similitude considerations to scaling laws and to force-displacement and energy-volume characteristics for tools of various shapes, as summarized by Tabor.2 Vork on the flow and fracture behaviors of glass loaded with pyramidal and spherical indenters is reviewed by Douglas.3 Maurer refers to the work of Evans and Murrell on wedge loadings on coal and on mixtures of pitch and sand. It is evident from Maurer's paper that a considerable portion of the studies of rock mechanics in drilling, such as crater formation experiments, has involved concentrated loadings on rock.

Jan 1, 1967

By W. R. Aufricht, E. H. Koepf

The theory, measurement, and application of capillary forces in reservoir rock have been treated ex-tensively in the various petroleum publications.1,2,3,4 These forces are of prime importance in oil production, and data on capillary properties are among the most important tools used in the study of reservoir mechanics. The principal application of measured capillary pressure data by the production and reservoir engineer is in the determination of the initial distribution and mobility of fluids in the reservoir. The distribution refers to the magnitude of the oil and interstitial water saturations under capillary equilibrium conditions and to their variation throughout the reservoir as a result of changes in rock properties and nearness to free water. The magnitude of the water (or oil) saturation, as well as the porosity, is required in volumetric calculations of oil in place. In low permeability reservoirs, where long transition zones are common, the magnitude of the oil content, even below the depth interval where commercial rates of flow of oil can be obtained, must be evaluated since this oil contains energy available to the production of the remainder of the reservoir. The mobility of the water phase is of particular importance in water-flood calculations since mobile water may condemn what would otherwise be a successful water flood. In reservoirs with predominantly small pores, high immobile water contents are possible. Conversely, reservoirs with predominantly large pores may contain mobile water even though the interstitial water contents are relatively low. This presentation reviews the distribution and mobility of interstitial water contents as determined from capillary pressure data and shows typical data for various types of carbonate reservoirs. A discussion of the variations found in different types of carbonate reservoirs is given. DISCUSSION Interpretation of Laboratory Data Fig. 1 is a typical laboratory capillary Pressure curve where water saturation as Per cent of Pore space is plotted vs capillary Pressure (psig) for an air-water system. This par- ticular curve was obtained by measurement on a sample of San Andres dolomite with intergranular-type porosity. The sample studied had a permeability of 10.0 md and a porosity of 18.8 per cent. The capillary pressure-saturation relationship illustrated is an inherent property of the rock (a function of the size and distribution of the pores) and represents the ability of this water-wet rock to retain water against the pressure differential exerted by a non-wetting fluid (oil or gas) to remove it. In the laboratory a known pressure differential is exerted from a pressure source; in the reservoir the pressure differential is controlled by the density difference between the hvdrocarbons and the water. The laboratory capillary pressure values may be converted into terms of equivalent height of water column using known values of reservoir oil and water density and measured or average values of interfacial tension

Jan 1, 1958

By Harold Markus, Arthur H. Grobe, Gerhard Derge

THE high corrosion resistance possessed by tin under most circumstances, combined with its generally satisfactory appearance and useful physical properties, has led to many and varied uses for the metal. These uses have been partly limited by the fact that tin is an expensive metal, therefore many applications have been developed in which tin has been employed in combination with lead, either by coating, as in tin-lined collapsible tubes, or by the formation of alloys containing various proportions of tin-rich and lead-rich phases, as terne plate. A detailed knowledge of the corrosion characteristics of the tin-lead couple therefore is of general interest and has become specially important at the present time, when every effort is being made to conserve tin as much as possible. The present study. has been limited to carbonate solutions with a pH range from 8.4 to 11.2 so that the results may be related to earlier work on the corrosion of tin and its alloys.1-3,6 In these papers, the effects of a number of anion and cation additions to these solutions have been observed. APPARATUS AND METHOD The electrodes for the corrosion cell were cut from rolled sheet about 1/16 in. thick. The length of all specimens was held constant at 7 in., while the width was varied from 1/2 to 2 in. These electrodes were fastened to brass electrode supports, which were attached to rubber stoppers fitting into tall-type one-liter Pyrex beakers that contained the electrolyte. The lead electrodes were prepared from Omaha pig* and the tin was rolled from a slab of Chempur.? After cutting to size, the sheets were polished with No. I emery paper and cleaned with carbon tetrachloride. The edges, back and upper parts of the specimen were coated with a synthetic lacquer, which was supplemented with beeswax for the lead electrodes. The binding posts were coated with beeswax after the electrodes had been damped. The pH of the electrolyte was controlled? by adjusting the ratio of carbonate to bicarbonate. Approximately 600 ml. of electrolyte was used in each beaker. The entire assembly was placed in an oil bath thermostatically adjusted to operate at 30°C. ± 0.10. Potentials were measured against a saturated calomel electrode connected. to the cell by an agar-agar salt bridge. The carbonate solution used in the salt bridge was the same as that used in the corrosion cell. Currents were measured with a milliam-

Jan 1, 1942

By A. R. Kaufman, P. Gordon

THE large-scale manufacture and use of uranium in conjunction with the atomic energy development during the war led to a need for knowing the equilibrium diagrams of uranium with various other metals. The alloys of uranium with aluminum and with iron were among the first that were studied for this purpose. Much of the work was done in the manner of a survey since it was necessary to determine the important features of the phase diagrams rather than to obtain completely detailed results. For this reason no attempt was made to locate exactly such features as liquidus lines, solid solubility limits and compound and eutectic compositions. It is believed, however, that there are no great inaccuracies in the diagrams reported here and that no important points were overlooked. Earlier work on alloys of uranium with aluminum and iron is almost nonexistent and in each case is considered to have been of little value by M. Hansen. It is interesting to note, however, that the compound UAl3 was first reported in 1902 by L. Guillet. Experimental Procedure Materials: The uranium used for making most of the aluminum alloys was obtained from material prepared by Metal Hydrides, Inc., and melted in vacuum at M.I.T. Because of the lack of an adequate supply of metal, it was necessary to use material from several different batches and hence it is impossible to state an exact analysis. However, a few results indicated about 0.01 to 0.03 pct iron and probably about 0.03 to 0.05 pct carbon. Toward the end of the work a small amount of metal was obtained from Brown University and from Iowa State College and this was used in determining the transformations in pure metal and in some dilute alloys. All of the aluminum used in this investigation came from a supply of high purity metal (greater than 99.9 pct aluminum) which was obtained through the courtesy of Dr. Mehl of the Carnegie Institute of Technology. The uranium used for making the alloys with iron was produced by the bomb reduction process which has been described by J. Chipman.² This metal, after vacuum melting, contained about 99.9 pct uranium by weight with carbon and iron as the chief impurities. Electrolytic iron containing about 0.012 pct carbon, 0.020 pct nickel and 0.009 pct copper was used in making the melts. Melting Equipment: The melting of the alloys went through a stage of development which culminated in the use of beryllia or beryllia-lined crucibles and in the use of high frequency heating in either vacuum or in an atmosphere of argon. It was found that uranium at a few hundred degrees above its melting point would pick up aluminum and to a lesser extent silicon from an alundum thimble while aluminum above 1000°C would extract silicon from the impure alundum. No reaction of either metal with beryllia was noted at temperatures as high as 1800°C. The distillation of aluminum from the aluminum-rich alloys was quite troublesome at temperatures above about 1300°C and was only partially avoided by the use of argon instead of vacuum. Melting in resistance furnaces,

Jan 1, 1951

It is not often that a mining district is discovered, opened up, exploited and developed into a rich producer within the space of three or four years. Not until the year 1903 was the existence of the rich cobalt-nickel arsenides and silver of Northern Ontario even suspected by the mining public. But it is worthy of record that Dr. W. G. Miller, the man who has done so much to develop sanely and honestly the mineral resources of Ontario, pointed out [ ] the possibilities of this region at least two years before the first discovery was made. . Dr. Miller, then Professor of Geology at the School of Mining, Kingston, Ont., referred in these words to the district: "It will be seen from what has been stated on preceding pages that the district examined contains as great a variety of rocks as probably any part of the Province of equal area . . . Although few discoveries of economic minerals have been made in this territory, it may reasonably be expected that deposits of value will be found when

Jan 1, 1907

By M. TAYLOR

AT Grand Saline, some 65 miles east of Dallas, the Morton Salt Co. of Chicago has for some years operated a brine pumping and evaporation plant on a salt dome. They recently drilled trial holes to obtain data on the dome, preparatory to opening, a new mine, with the following results: The dome is in the form of a truncated cone, with an average of 210 ft. of cover. The top of the dome is approximately one mile in diameter, with the town of Grand Saline lying over the northern rim, and the sides slope off at an angle of 50" to 80" from the horizontal. The deepest holes were drilled to 900 ft. without penetrating beyond the salt, and indications are that the salt deposit is several thousand feet thick. As the deposit increases in area with the depth, there is undoubtedly enough salt to supply a mining operation for an almost unlimited period of years.

Jan 1, 1930

By Clarence Seyler

THE technical difficulties of cutting thin sections of coal for examination by transmitted light have hitherto restricted the investigation of the important subject of the microstructure of coal to the few possessed of the requisite skill and time. Apart from this, the method fails with anthracites and other coals rich in carbon, owing to the opacity of the material. Occasional use of the method of polishing a surface, with or without etching, has been made, but it was not until Winter1 published an account of his results that attention was seriously directed to the method. In May, 1923, a specimen of dull anthracite came into my hands; I tried Winter's method on it and the presence of megaspores and other vegetable structures became clearly visible. A preliminary notice was published by me;2 but I soon abandoned the use of Schulze's solution having found that a mixture of chromic and sulfuric acids gave far better results. In the meantime Turner and Randall, in America, had independently developed the method of flame etching, as applied to anthracite, with great success. I have spent a year studying the method of chromic etching, which gives excellent results with bituminous coals and cannels, as well as with anthracite. For anthracites, I have used the chromic method and Turner's method of flame etching, whichever was the more convenient or as a check one on the other. The polishing is done, according to metallurgical practice, by the use of a polishing machine and successively finer emery paper, followed by polishing on cloth moistened with a suspension of levigated green oxide of chromium, and a final rubbing on "selvyt" (a cotton velvet polishing cloth) moistened' with alcohol. The polished sample is examined by reflected light with a 2/3 and 1/6 in. objective. Bituminous coals usually show considerable structure, and even anthracites show it faintly in places. The sample is then etched by immersion in a boiling solution made by adding 10 c.c. of concentrated sulfuric acid to 30 c.c of a saturated solution of chromic acid; enough water is then added to dissolve

Jan 3, 1925

By D. C. Jackling

I BESPEAK your indulgence for a brief expression of the views of a patriarch in the field of mineral industry technology relative to young men's problems in that sphere of education and endeavor. Wherever hereafter I employ the terms "technical education," "engineer," "technologist," or similar expressions, these are intended to be understood as relating to the broad field of the sciences and arts applicable to the mineral industries. First, the usefulness of technical education to either the possessor of it or those to whom its services may be made available industrially depends primarily upon the quality of the education and the capabilities of the educated to put his talents to effective and constructive employment in his chosen field of applied science.

Jan 1, 1940

By DR. RICHARD RATHBUN

(Washington Meeting, May, 1965.) THE remarks of Dr. Rathbun in his address of welcome render it unnecessary that I dwell either upon the history or aims of the National Museum, and enable me to proceed at once with a brief descriptive outline of the Department for which I am responsible, and this with particular reference to that division devoted to applied geology. The amount of geological material brought together prior to 1876, under the various Congressional acts quoted, was, though valuable, comparatively small. It consisted mainly of the collections made by Professor J. D. Dana and his assistants during the Wilkes Exploring Expedition; by the various geologists accompanying the surveys of the Pacific railroads in 1854-55; the Surveys West of the 100th Meridian under the direction of the Engineering Corps of the Army; the United States geological surveys under direction of Dr. F. V. Hayden ; and the various Land Office surveys. Prior to 1873 there were no paid assistants to care for these collections. They were studied, if studied at all, by " collabrators," so-called, several of whom had offices and even sleeping apartments in the Smithsonian Institution. In the list of these collaborators are found such names as Conrad, Cope, Gabb, Leidy, Lesquereux, Meek, and Newberry. The building now occupied by the National Museum was designed primarily to make room for the great mass of material secured in 1876 at the close of the Centennial Exposition in Philadelphia. As completed in 1880, it afforded opportunity for expansion and incidental organization on much more practical basis than had previously existed. This found expression in the creation of numerous departments with salaried officials to take charge of the various collections. With the appointment of Dr. George W. Hawes to the position of Curator of Geology and Mineralogy, in 1881, and Dr.

Jul 1, 1905

By Henry Lloyd Smyth

In 1891-92 1 was entrusted with the geological survey of part of the large area lying between the Marquette and Menominee iron-ranges in the Upper Peninsula of Michigan, and extending from the Republic trough on the north, through portions of the valleys of the Michigamme and Fence rivers, to and including the intermediate Felch mountain range on the south. Until a few years back the larger part of this area has been very difficult of access, and much of it is difficult still. The rock-surface is for the most part covered with swamp, forest and glacial deposits of various kinds, and therefore has not invited geological study. For these reasons the district, as a whole, with the exception of the Felch mountain range, remained almost unknown from a geological standpoint until our work in 1892. Our main object was to map the pre-Cambrian rocks, particularly the iron-bearing formations of Algonkian or Huronian age, and to obtain as much information as possible with reference to their sequence and structure, In carrying out this purpose, the use of simple magnetic instruments was found to be of the greatest assistance, and indeed indispensable. In this paper the results of our experience in tracing magnetic rocks by means of the disturbances produced in these instruments, have been brought together in systematic form, with such references to the particular area as are necessary in order to illustrate general principles, with the hope that they will prove useful to other workers in the same region, or in other regions where similar conditions may be encountered. The writer was efficiently aided in the field-work by Messrs. Samuel Sanford and Charlea N. Fairchild for nearly the whole period, and E. B. Mathews and H. F. Phillips for part of it,

Jan 1, 1897

By W. A. Ver Wiebe

The year 1940 was singularly unmarked by sensational developments in Kansas. Routine operations were carried on in a systematic, orderly fashion and the efforts of oil producers were concentrated on extending known fields. In Kansas an arbitrary yardstick for wildcats has been set up. A well drilled mile or more from a known pool or well is now considered a wildcat. A "rank wildcat" is one that is drilled at least 2 miles from any known producer. During 1940, rank wildcats resulted in the completion of 116 test wells, among which 16 were successful in finding new oil pools and the remaining I00 were dry holes. The ratio of successful wells to dry holes, therefore, was approximately I:6. During the year, 1890 wells were completed in eastern and western Kansas. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or wells that were recompleted in a different geological horizon. About three fourths of these (1423) were completed as commercial oil wells (I220 in western and 203 in eastern Kansas). The commercial gas wells completed number 58 of which 10 are in eastern Kansas and 48 in western Kansas. Of the remzining completions 147 are dry holes in eastern and 262 are dry holes in western Kansas. Based on daily potential capacity, the new discoveries of the year account for a cumulative initial production of 46,000 bbl. in eastern and 2,128,000 bbl. in western Kansas. The state of Kansas attained a new peak in production, with the total of 66,245,000 bbl. for the year 1940, the number of contributing wells being 20,779. Thus the increase over 1939, when about 58 million barrels was produced, is considerable. The previous peak occurred in 1937, when 70,761,000 bbl. was marketed. In another still earlier peak, in 1917, slightly more than 45,000,000 bbl. was produced and sold. The production of gas probably reached a new peak also during 1940, with its total of 85 1/2 billion cubic feet. Between the peak of the year 1908, when over 80 billion cubic feet was produced, and that of 1940, the production dropped to a low point of 16 billion cubic feet in the year 1921. The number of test wells drilled was larger than in 1939; that is, 1890 compared with 1458. The first peak was reached in 1904, when 2782 wells were drilled. The number dropped off rapidly, to 368 three years later, but rose to the second and highest peak in 1918, when 4671 test wells were completed. In the period between 1904 and 1912 more gas wells were completed than oil wells. Between the high peak of completions in 1918 and somewhat lower peak of 1937, the low point was reached during 1931, with the completion of only 470 test wells. In the number of new pools discovered, Kansas again ranks high among the states. The exact number depends somewhat upon the interpretation of a "new" area— whether it should be called a new pool or a long extension of an old pool. Unfortunately, the matter of securing the right kind of production allowable also enters into this question. Often the decision regarding a new pool cannot be made until other wells

Jan 1, 1941

By W. A. Ver Wiebe

The year 1940 was singularly unmarked by sensational developments in Kansas. Routine operations were carried on in a systematic, orderly fashion and the efforts of oil producers were concentrated on extending known fields. In Kansas an arbitrary yardstick for wildcats has been set up. A well drilled mile or more from a known pool or well is now considered a wildcat. A "rank wildcat" is one that is drilled at least 2 miles from any known producer. During 1940, rank wildcats resulted in the completion of 116 test wells, among which 16 were successful in finding new oil pools and the remaining I00 were dry holes. The ratio of successful wells to dry holes, therefore, was approximately I:6. During the year, 1890 wells were completed in eastern and western Kansas. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or wells that were recompleted in a different geological horizon. About three fourths of these (1423) were completed as commercial oil wells (I220 in western and 203 in eastern Kansas). The commercial gas wells completed number 58 of which 10 are in eastern Kansas and 48 in western Kansas. Of the remzining completions 147 are dry holes in eastern and 262 are dry holes in western Kansas. Based on daily potential capacity, the new discoveries of the year account for a cumulative initial production of 46,000 bbl. in eastern and 2,128,000 bbl. in western Kansas. The state of Kansas attained a new peak in production, with the total of 66,245,000 bbl. for the year 1940, the number of contributing wells being 20,779. Thus the increase over 1939, when about 58 million barrels was produced, is considerable. The previous peak occurred in 1937, when 70,761,000 bbl. was marketed. In another still earlier peak, in 1917, slightly more than 45,000,000 bbl. was produced and sold. The production of gas probably reached a new peak also during 1940, with its total of 85 1/2 billion cubic feet. Between the peak of the year 1908, when over 80 billion cubic feet was produced, and that of 1940, the production dropped to a low point of 16 billion cubic feet in the year 1921. The number of test wells drilled was larger than in 1939; that is, 1890 compared with 1458. The first peak was reached in 1904, when 2782 wells were drilled. The number dropped off rapidly, to 368 three years later, but rose to the second and highest peak in 1918, when 4671 test wells were completed. In the period between 1904 and 1912 more gas wells were completed than oil wells. Between the high peak of completions in 1918 and somewhat lower peak of 1937, the low point was reached during 1931, with the completion of only 470 test wells. In the number of new pools discovered, Kansas again ranks high among the states. The exact number depends somewhat upon the interpretation of a "new" area— whether it should be called a new pool or a long extension of an old pool. Unfortunately, the matter of securing the right kind of production allowable also enters into this question. Often the decision regarding a new pool cannot be made until other wells

Jan 1, 1941

By A. L. Jr. Pozzi, A. O. Garder, D. W. Peaceman

A new numerical method is proposed for the solution of multidimensional miscible displacement problems. Besides the usual stationary grid associated with numerical procedures, the method uses moving points for which positions and concentrations are computed each time step. Based on the method of characteristics for treating combined transport and dispersion, the method applies equally well to any number of dimensions and, in contrast with other numerical procedures, properly takes into account the physical dispersion, no matter how small. Extensive tests show that accurate solutions of one-dimensional problems can be obtained over a wide range of values of the dispersion coefficient, including zero. They also show that the moving points do not need to be uniformly spaced, and that increasing the number of moving points beyond 2/grid interval does not significantly improve the accuracy of the solution. Two-dimmsional calculations using the new method were carried out to simulate laboratory model displacements in which gravity caused overriding of solvent. Good agreement between observed and computed profiles and measured and computed concentrations of produced fluid was obtained for a viscosity ratio of 1.89; at higher viscosity ratios, fair agreement was obtained Computed results were found to be significantly affected by vertical dispersion, and negligibly affected by dispersion in the direction of flow, in agreement with conclusions based on experimental observations. INTRODUCTION Although miscible displacement processes are potentially of great economic significance, limited progress has been made in developing mathematical methods for predicting the outcome of a solvent flood. Because of the complexity of the partial differential equations which describe multidimensional miscible displacement, numerical methods are a natural approach to their solution. The task of finding suitable numerical approximations to one of the partial differential equations, which involves both dispersion and convective transport, has been particularly difficult. Dispersion in the absence of transport is described by the heat flow equation, a second-order equation of parabolic type. This equation has been very successfully treated by numerical methods. Transport in the absence of dispersion is described by a first-order equation of hyperbolic type. This equation has been treated numerically with some success in one dimension, both by Lagrangian and Eulerian techniques, 1.2 but extension to two or more dimensions has not been satisfactorily accomplished. Usually one of two things happens: either the numerical solution develops oscillations or it becomes smeared by artificial dispersion resulting from the numerical process. When transport and dispersion are considered simultaneously, this numerical dispersion may dominate the low physical dispersivicy that generally characterizes miscible displacement. Stone and Brian2 have developed a new difference equation for treating combined transport and dispersion in one dimension. By suitable choice of certain parameters, they succeeded in markedly reducing both oscillation and numerical dispersion. However, a satisfactory extension to higher dimensions has not yet been found. Peaceman and Rachford3 presented a centered-in-time and centered-in-distance difference equation combined with a 1,transfer of overshoot" procedure which was demonstrated to work well in one dimension. The technique was applied to the two-dimensional miscible displacement problem, but subsequent calculations with zero dispersivity showed little change in results compared with the calculations they presented. This indicates that their method involved a numerical dispersion of the same order as the physical dispersion. The present paper describes an alternate method for solving the combined transport-dispersion

Jan 1, 1965

By Daniel Hanson

FoR most of their practical applications metals are required to withstand stresses of appreciable magnitude: indeed, it id because they possess the quality of resisting stress without becoming permanently deformed that they find such extensive use in the service of man. Metals and alloys must, in service, usually behave as elastic substances—or nearly so. It is not difficult to satisfy this condition at ordinary temperatures. Iron and its alloys, especially the steels, are at normal temperatures excellent elastic bodies, capable of satisfying most of the mechanical requirements of the engineer: where electrical, chemical or other properties are impor-tant, which cannot be met by steels, it is usually possible to find a non-ferrous alloy such as nickel, copper or aluminum, which will prove satisfactory. When the metals or alloys are not inherently sufficiently elastic, cold-working or heat-treatment may develop elastic properties to a sufficient extent for practical needs. By means of relatively simple, rapid tests we can measure such properties as elastic modulus, limit of proportionality and proof stress, upon which design can be based with confidence. The case of the soft metals, such as lead and tin, is well known to be exceptional. They possess no definite limit of elasticity, and the value of proof stress or tensile strength depends to a great extent on the speed with which the test is carried out. Design here must be based on other considerations than a well-established theory of the proportionality of stress and strain. It is now generally recognized that steels and non-ferrous alloys possess at temperatures not greatly exceeding that of the atmosphere, characteristics quite different from those existing at ordinary temperatures, and that they assume qualities similar to those of the soft metals. Not only have they no limit of elasticity, but the proof stress and the ultimate stress depend on the time of application of the load. Flow under load may persist for long periods of time, possibly indefinitely, and the determination of a true maximum stress becomes a matter of great difficulty.

Jan 1, 1939

By Daniel Hanson

FoR most of their practical applications metals are required to withstand stresses of appreciable magnitude: indeed, it id because they possess the quality of resisting stress without becoming permanently deformed that they find such extensive use in the service of man. Metals and alloys must, in service, usually behave as elastic substances—or nearly so. It is not difficult to satisfy this condition at ordinary temperatures. Iron and its alloys, especially the steels, are at normal temperatures excellent elastic bodies, capable of satisfying most of the mechanical requirements of the engineer: where electrical, chemical or other properties are impor-tant, which cannot be met by steels, it is usually possible to find a non-ferrous alloy such as nickel, copper or aluminum, which will prove satisfactory. When the metals or alloys are not inherently sufficiently elastic, cold-working or heat-treatment may develop elastic properties to a sufficient extent for practical needs. By means of relatively simple, rapid tests we can measure such properties as elastic modulus, limit of proportionality and proof stress, upon which design can be based with confidence. The case of the soft metals, such as lead and tin, is well known to be exceptional. They possess no definite limit of elasticity, and the value of proof stress or tensile strength depends to a great extent on the speed with which the test is carried out. Design here must be based on other considerations than a well-established theory of the proportionality of stress and strain. It is now generally recognized that steels and non-ferrous alloys possess at temperatures not greatly exceeding that of the atmosphere, characteristics quite different from those existing at ordinary temperatures, and that they assume qualities similar to those of the soft metals. Not only have they no limit of elasticity, but the proof stress and the ultimate stress depend on the time of application of the load. Flow under load may persist for long periods of time, possibly indefinitely, and the determination of a true maximum stress becomes a matter of great difficulty.

Jan 1, 1939

By Zay Jeffries

Page Introduction............................. 474 Nature of Experiments ........................ 476 Materials Used in Experiments..................... 476 Description of Samples........................ 476 Details of Tests and Apparatus .................... 486 Determination of Elongation...................... 488 Determination of Reduction of Area .................. 488 Results of Tests........................... 489 Quantity and Arrangement of Amorphous Phase............. 497 Properties of Amorphous and Crystalline Phases............. 501 Intercrystalline Fracture........................ 530 Trans-crystalline Fracture....................... 531 Rupture ............................... 535 Explanation of Beilby's Results..................... 536 Mechanical Properties of Copper Wires................. 537 Mechanical Properties of Tungsten Wires................ 542 Mechanical Properties of Iron Wire................... 546 Effect of Diameter of Wire on Mechanical Properties........... 554 General Considerations on Properties of Metals at Very Low Temperatures .. 556 General Considerations on Physical Properties of Complex Alloys...... 557 Summary.............................. 559 Discussion.............................. 562 Introduction DuRing the period 1914 to 1916. the writer observed many times that tungsten wire could be drawn hot until it became brittle but on cooling to room temperature it became ductile again. In searching the literature for parallel cases. it was found that Beilbyl had produced hard-drawn wires of gold. silver. and copper that showed less than 1 per cent.

Jan 1, 1919

By Herbert Clark Hoover, Lou Henry Hoover

SINCE I have written of the varied work of pre- paring the ores, I will now write of the various methods of smelting them. Although those who bum, roast and calcinea the ore, take from it something which is mixed or combined with the metals ; and those who crush it with stamps take away much ; and those who wash, screen and sort it, take away still more; yet they cannot remove all which conceals the metal from the eye and renders it crude and unformed. Wherefore smelting is necessary, for by this means earths, solidified juices, and stones are separated from the metals so that they obtain their proper colour and become pure, and may be of great use to mankind in many ways. When the ore is smelted, those things which were mixed with the metal before it was melted are driven forth, because the metal is perfected by fire in this manner. Since metalliferous ores differ greatly amongst themselves, first as to the metals which they contain, then as to the quantity of the metal which is in them, and then by the fact that some are rapidly melted by fire and others slowly, there are, therefore, many methods of smelting. Constant practice has taught the

Jan 1, 1950

By L. Seigle, R. Resnick

An inert-marker movement experiment indicates that the ratio of the intrinsic diffusion coefficients DC:DTa = 80:l in TaC at 2500°C. Measurements of the diffmion coefficient of carbon in nonstoichiometric TaC at temperatures from 1700° to 2700°C reveal that Dc increases with decreasing carbon content, but much less than expected from the probable change in vacancy concentration with carbon content. A diffusion process involving two simultaneously operating mechanisms is postulated, and shown to be theoretically feasible. The average value of the carbon diffusion coefficient is given by DC = 0.18 exp[(-85,000 ± 3000)/RT] sq cm per sec over the composition range 46 to 49.5 at. pct C. BECAUSE of their high melting points and hardness, the carbides of the IV, V, and VI group transition metals, along with those of uranium, have attracted considerable interest for applications at high temperatures. In these applications the reactivity of the materials is important, and, since rates of diffusion within the compounds influence reactivity, a knowledge of diffusion kinetics and mechanisms is desirable. While many investigations of the mechanical and electrical properties of these compounds have been made, only two fundamental investigations of diffusion in the carbides are known. Chubb, Getz, and Townleyl measured the diffusivity of carbon and uranium in UC, and Gel'd and Liubimov2 measured the diffusivity of carbon and niobium in NbC. This paper describes an investigation of the diffusion of carbon in tantalum monocarbide and, in particular, the influence of carbon deficiency on this process. Tantalum carbide melts at approximately 3800°C, which makes it one of the highest melting materials known. The compound exists over a rather wide range of carbon Content.3-7 At the peritectic temperature, 3240°C, the phase extends from about 36 to 50 at. pct C. Although the compound can exist with a substantial carbon deficiency, the high carbon phase boundary remains near the stoichiometric composition over the entire temperature range; i.e., no carbon excess is observed. The structure of TaC is the NaCl type wherein carbon atoms normally occupy the octahedral sites in a somewhat expanded fcc lattice of tantalum. Decrease of the lattice parameter with decreasing carbon suggests that the removal of carbon introduces octahedral vacancies into the lattice. I) EXPERIMENTAL DETAILS AND RESULTS Inert-Marker Experiments. In a compound such as TaC the interstitial element would be expected to diffuse more rapidly than the metal. This was confirmed by an inert-marker experiment, following Srnigelskas and irkeendall.8 Ideally, the markers should be placed at the interface between a slab of low-carbon TaC and graphite, and their movement during subsequent inter-diffusion measured. Unfortunately, no solid could be found which is unreactive in contact with carbon at the high temperatures employed in these experiments. In order to circumvent this problem, a specimen was designed in which the markers consisted of several small canals running just below the surface of a tantalum slab. This specimen was prepared by machining grooves on the surface of the tantalum slab and then diffusion-bonding a thin plate of tantalum to the slab over the grooves. The surface of the plate was then ground down until the distance between the canals and surface was as small as possible (about 0.01 cm). Thus, the canals would lie entirely within the TaC phase after a short period of diffusion. The diffusion anneal consisted of immersing the metal sample in high-purity graphite powder and heating for approximately 10 hr at 2500°C under vacuum. At this temperature, the vapor pressure is sufficiently high and the transfer of carbon from graphite sufficiently rapid to allow the surface of the diffusion sample to attain the stoichiometric carbon concentration very quickly. Conclusions regarding the relative diffusion rates of carbon and tantalum in the compound layers (TaC and Ta2C) can be drawn from the location of the canals after the diffusion anneals. If the growth of the layers is governed mainly by the diffusion of carbon, as expected, the canals should remain close to the sample surface. If the diffusion of tantalum contributes appreciably to formation of the compound layers, the distance from the markers (canals) to the surface should increase. Fig. 1 shows, diagrammatically, the appearance of the specimens after diffusion, and Table I presents the depth below the surface at which the

Jan 1, 1967