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By J. M. Lommel, B. Chalmers

The transfer of material from the solid to the liquid states can be accomplished in several ways. It occurs by the application of heat in the more familiar metallurgical operations of melting but it can also be accomplished by solution in a liquid, as can occur in systems using liquid metals for heat-transfer media. The kinetics of this reaction were studied to learn more of the separate steps in the process. In the case of a pure material at its melting temperature, Te,A,, thermal energy must be supplied to the solid in an amount equal to the latent heat of fusion in order for the solid-to-liquid transfer to occur. The rate at which heat is supplied, and hence the rate of melting, is a function of the temperature gradients in the system. This phase transfer can also occur in the absence of temperature gradients in the system illustrated in Fig. 1, which is a partial phase diagram between the components A and B. A solid of composition CI will

Jan 1, 1960

By T. M. Morris

THE rate of flotation of solid particles determines the percentage recovery of these particles which can be obtained during a given time interval. It is an established fact that the recovery is greatest in the fine sand size range and falls off on either side of this size range. It is also a fact that the history of the development of concentrating devices has been marked by a desire to recover the small particles: tables were developed to treat material too fine to recover in jigs; flotation recovers material too fine to be recovered on tables. As our ores become more complex and require finer grinding, a greater proportion is in the slow-floating size range. It is therefore of economic importance that the effect of size of particle upon rate of flotation be studied. Many studies have been made along this line. The present investigation attempts to quantify the rate of flotation by means of a rate equation, and then compares the effect of size upon the rate of flotation. It was found that the flotation rate constant increases with increase in diameter of particle in the size range smaller than the optimum size particle. The flotation rate constant decreases with an increase in diameter of particle in the size range coarser than the optimum size particle. This suggested two different actions taking place, and these are discussed. Suggestions for further work in order to improve the flotation rate of both fine and coarse particles are made. The usual method of expressing rate is to plot cumulative percent recovery vs time. If we knew the equation of this kind of curve we could replot it as a straight line, and the slope of the line would be an index of the magnitude of the flotation rate. It is easier to compare straight lines than curves. The basis used for obtaining the equation of the recovery vs time curve is the law of mass action. This law states that the "rate of a chemical reaction is proportional to the `active masses' of the reacting substances present at any given time." This, of course, implies a constant temperature. We can modify this for our use by using the term flotation reaction instead of chemical reaction and the term floatable particle instead of active masses. [ ] where C denotes concentration of particles, t denotes time, k denotes a proportionality constant. If the exponent of C is 1, then we have a first order rate reaction. If the exponent of C is 2, then we have a second order rate reaction. For a first order rate reaction, we obtain, after integration, [ ] where k is again a proportionality constant and has the dimension of the reciprocal of time. C, is the original concentration or weight or percentage of floatable particles. C, is the concentration or weight or percentage of floatable particles remaining in the flotation cell after time t. If all particles of the mineral to be floated were capable of floating we could take C, as 100 and C, would be 100 - R, where R is the cumulative percentage recovery of mineral at time t. But it is not usual for all of the particles to be capable of floating, because of surface oxidation, etc. Therefore, we must introduce a factor x which is the percentage of unfloatable mineral. Hence the first order equation is [ ] It has been proposed by various workers1-3 that this equation describes the flotation rate. More recently N. Arbiter4 states that a second order rate equation fits the recovery vs time curve more closely than does a first order rate equation. Morris' has discussed the evidence presented for this statement. It has been concluded that the first

Jan 1, 1952

By John T. Norton

In spite of the very general errlployment of nitride hardening, there is still considerable doubt as to the real nature of the mechanism involved. Experience has shown that the addition of small amounts of hardening elements to iron or steel results in a wide variety of desirable properties in a nitrided case. Perhaps the foremost of these elements is aluminum and in this investigation an attempt has been made to study the behavior of aluminum during the hardening process. It is believed that the establishment of a complete atomic picture of the metal at various stages of the process will indicate the relationships between the several kinds of atoms and their individual influences on the physical properties in a clear and direct fashion. A consideration of the problem suggests a surprising similarity between the mechanisms of nitride hardening and of age-hardening. It is now generally understood that age-hardening may take place by one of two distinct processes, the first involving the precipitation of a finely dispersed phase and the other being concerned with the modification of an existing phase. Following much the same line of reasoning, two theories of nitride hardening have been suggested. The first explanation, which has been generally discussed, particularly by Fry,' states in brief that the presence of aluminum causes the precipitation of aluminum nitride during nitriding and that this finely dispersed phase is the primary cause of hardening. The second explanation, which has not been published but which has been freely discussed by those interested in the problem, postulates the substitution of aluminum atoms for certain of the iron atoms in the several iron-nitrogen phases in the same manner that the substitutional iron-alurninurn solid solution is formed. The marked increase in hardness, as compared with the aluminum-free system, is attributed to the severe lattice distortion accompanying this replacement.

Jan 1, 1934

By S. E. Haszko

SEVERAL new XGa2 intermetallic compounds, Table 1, where X is a rare earth, having the AlB, structure were prepared as part of a continuing study of the magnetic and structural properties of rare-earth alloys.' In this note, the crystallographic results of these compounds are presented. Chart, Eq. 121 for the data in Fig. 1 can be adequately represented by The corresponding standard free-energy change is AF; = -4.576 T log K = -20,900 + 10.20T [5I At low nitrogen concentrations the ratio of mole fraction to weight percentage is a constant so that the mole fraction X of nitrogen is given by X = 0.0392 [%NJ. At low values of X, the activity and the concearation approach each other, hence K, = 0.0392 K,, where K, is expressed in terms of the mole fraction of nitrogen. Hence Eqs. [4]. and [5] become

Jan 1, 1962

By Robert W. Phelps

It is gratifying to observe the growing interest in the study of oil-well spacing. It should always be held in mind that the problem of optimum spacing is to obtain the maximum return of capital per acre drained. This naturally evolves.into a mathematical consideration. As mathematics is the basis of all science, an effort should be made to develop formulas which involve data obtainable in the early stages of development. The first information from a discovery well in a new field would be the character of the sand, rate of initial production of oil and gas, viscosity of the oil, rock pressure, etc. Later, from this well, if Herold's theories of hydraulic, volumetric and capillary controls are accepted, could he determined the ultimate production as without interference from drainage by subsequent well completions, and under which control the well is producing. If it should prove to be producing under capillary control, a rough estimate could be made of it's radius of drainage. With but one well, the radius of drainage, or the interference of drainage of individual wells by close spacing, would be estimated by comparison with similar conditions in other fields in which the development has progressed sufficiently to furnish the data. A second well that is spaced sufficiently close so that an interference can he observed after its ultimate production is estimated, will furnish data to develop a desirable spacing of wells which can be inaugurated for that area and which is capable of producing a uniform amount of oil under like conditions. In some fields this area will be extensive, in others each well location will require an individual study. In 1924, Cutlerl developed a scheme whereby he determined by tabulation a spacing of oil wells for the maximum return per acre. After a study of production in a number of fields, he developed the following as a tentative rule: "The ultimate production for wells of equal size in the same pool where there is interference (shown by a difference in the, production decline curves for different spacing) seems approximately to vary directly as the square roots of the areas drained by the wells. This rule may also he stated thus: The recovery from wells of equal size

Jan 1, 1929

By H. A. Coy, H. B. Henegar

The Mascot mines of the American Zinc Co. of Tennessee are situated in the Holston River valley, in Knox County, Tennessee, about 13 miles (20.9 km.) east of the city of Knoxville, and form a property of three operating shafts and one open pit. A second open pit is located at Jefferson City about 16 miles (25.8 km.) east of the Mascot mines. Geology Topography.—The principal topographical features of the region within which the zinc deposits occur is a series of parallel northeast and southwest ridges which reach altitudes of 200 to 400 ft. (61 to 122 m.) above the valley. These ridges are formed of resistant formation such as sandstone, quartzites, etc., while the valleys are occupied principally by limestone, including Knox dolomite, and by shale and other formations subject to quick erosion. The Holston River valley is wide and open with a rolling surface. Sink holes are common to the limestone portion, the general aspect of the valley being that of well-rounded hills with low intervening valleys superimposed upon which is a characteristic sink-hole topography. General Geology.—According to Keith, the rock formation of the area extends from the lower Cambrian into the Silurian. The region has undergone severe deformation with hcavy faulting, the underlying Cambrian having been brought to the surface by a series of low angle thrust faults, the strike of the faults and formations paralleling the general northeast and southwest direction of the topography and dipping at varying angles to the southeast. In general, the Cambrian quartzites, sandstone, etc., occupy the ridges while the Cambro-Si urian dolomites, limestone and shales occur principally in the valleys. Of the latter, the Knox dolomite is of particular interest to this paper in that it is the ore carrier in the Mascot area. The ore is associated with more or less irregular breccia zones, the degree of brecciation varying from a fine crushing to a breaking that involves blocks of large size. The breccia zones

Jan 1, 1918

By Harry A. Lipsitt, Rollins E. Hook, Attwell M. Adair

A necessary condition for a uniaxial stress distribution in compression testing is that the specimen end surfaces make full contact with the apparatus compression plates. In addition all compression surfaces must be machined perpendicularly to the loading axis. In general this condition is not sufficiently fulfilled in a simple apparatus. Therefore on application of the load the compression plate may first touch the specimen at one point only. This may cause crumbling of the specimen if the material under investigation is brittle (e.g., ionic crystals). It also precludes a precise study of the beginning of deformation as the effective cross sectional area is unknown. In addition a complex stress state is set up which renders quantitative work impossible, e.g., on dislocation density and arrangement as a function of stress. To overcome these difficulties a "self-adjusting" upper compression plate is required. A simple and reliable method of achieving this is shown in Fig. 1: A steel hemisphere is placed on the specimen. As soon as the compression plate (which no longer needs precise machining) makes contact with this hemisphere the load is uniformly distributed over the whole specimen surface, and a homogeneous uniaxial state of stress results. An advantage of the method is that the loading is always central, even when the specimen surface is not parallel to the compression plate (Fig. 1, dashed line). Therefore to a first approximation a uniaxial state of stress is maintained if the misorientation of the specimen end surface is small. Two typical stress strain curves of identically prepared sodium chloride crystals are shown in Fig. 2; curve 1 was taken without and curve II with the hemisphere under otherwise identical conditions. The improvement in the accuracy of defining the beginning of elastic and plastic deformation is clearly indicated. The writer wishes to thank the Deutsche Forschungsgemeinschaft for financial support, and Professor P. Haasen for providing facilities for this work.

Jan 1, 1962

By William P. Blake

THE use of diamonds upon a large scale in drilling rocks, and the substitution to a certain degree of rotary diamond drills for the ordinary steel percussion drills, marks a new era in the art of mining. Since the invention by Leschot of the diamond drill, it has steadily advanced in its utility and range of application, and in the appreciation of miners and engineers. I t must be claimed as one of the many gifts of science to the arts ; and it is, in particular, one of the fruits of the scientific education given at the Ecole Centrale, at Paris. Members are all, doubtless, more or less familiar with the construction of the drill and of the machinery by which it is applied in boring. I t is, therefore, my present purpose only to direct your attention to some recent marked improvements, made by the American Diamond Drill Company, by which the economy and efficiency of the machines have been increased. Form of Bit.-The annular or ring form of the drill-head or bit was, I believe, the earliest; and it is still in use, without essential modification, wherever it is desired to obtain a sample " core" or specimen of the rock traversed. But for mere drilling, regardless ~f the preservation of a test-core, a solid-head bit is preferred, except for very large holes. Until recently, these solid-head bits were made with a pointed cutting face shaped like an obtuse cone. This form was assumed to be the best, being most in accordance with the experience obtained with percussion drills. I t is found, however, that the exact reverse

By W. E. Crawford

The Fresnillo Company's mill at Fresnillo, State of Zacatecas, Mexico, treats oxide ores from the Fresnillo mine, dump ores and underground ores from the Plateros district, company leases and custom ores from the Zacatecas district, custom ores from other districts and tailings from old dumps at Fresnillo. The normal capacity of the mill is approximately 2600 dry short tons per 24 hours (a ton of 2000 lb.). The final product of the mill is a precipitate containing gold and silver, which is smelted and shipped as doré bullion to the refinery of the Compania Minera de Penoles, S.A., at Monterrey, State of Nuevo Leon, Mexico. The geology of the district was described in 1923, by T. C. Baker,' from whose paper the following data have been taken: The mineralization of the district was effected in the Tertiary period, following the intrusions and preceding the appearance of the flows. The area within which productive veins have been found is 1 mile long by 1/2 mile wide. The important units of each of the four general fracture systems meet in the central portion of Proano hill, which is an outcrop of graywacke, and where the rock was also intensely fractured by subsidiary movements, resulting in a shattered zone 1200 ft. long by 400 ft. wide. The mineralization was more intense in the immediate vicinity of the principal channels through which the solutions rose. The valuable metals are silver and gold, the ratio by weight of the former to the latter being 1000 to 1.5. Argentite is the predominant silver mineral, and is associated with pyrite and manganese mineral. The sulfides are primary throughout. A slight secondary action is represented by small quantities of native silver and silver halides, principally cerargyrite, which are found in the upper part of the mine. Oxidation has penetrated with great thoroughness to the lowest horizon so far exposed, this being 420 ft. below the present ground-water level. The shattered mass within the central portion of the hill and near the surface was sufficiently mineralized to produce a large stockwork

Jan 1, 1935

By Charles Pack

Die castings may be defined as metal castings made by forcing molten metal, under pressure, into a metallic mold or die. It is necessary to keep this definition in mind to avoid confusing this process with other permanent-mold casting processes. The fundamental principles of the process have been known and practised many years. The simplest application is embodied in the modern linotype machine in which molten metal (usually tin-lead alloy) is forced under pressure into a metallic mold. The pressure is derived from a piston and cylinder immersed in the molten metal. Progress in the art of die casting may conveniently be divided into three groups: Machine for imparting pressure to the metal, material for the die or mold, casting alloys. The problem of delivering molten metal under pressure into a die is comparatively simple, when dealing with low-fusing-point alloys, as the alloys of lead and tin, but it is much more complicated when dealing with metals of higher fusing points, such as the alloys of zinc, aluminum, and copper. Although the art of die casting is comparatively new and, to a large extent, unknown, the records of the patent office are replete with patents on the subject. Fig. 1 shows the Underwood machine patented in 1902; this is probably one of the first machines designed for the production of commercial die castings. The relation of this machine to the linotype casting machine is clearly apparent. A cylinder and piston are immersed in the molten metal, the application of power to this piston forcing the molten metal, under pressure, into the mold or die. The Doehler machine, Fig. 2, patented in 1907, is based on the same general principles. This machine is used to a large extent at the present time, throughout the United States, for the production of zinc, tin, and lead alloy die castings. In the machine shown in Fig. 3, patented by Doehler in 1910, compressed air is used for forcing the metal into the die. In Fig. 4 is shown another of this type of machine. Here compressed air is applied to the surface of the molten metal to force it into the die. In a machine patented by Chandler in 1914, shown in Fig. 5, the

Jan 1, 1919

By Erwin H. Leeman, Raymond R. Rice, Gerald L. Hassler

In the past few years a great deal of preeise information has been obtained about the relation of natural gas to oil production1. The improvement of our understanding has been of great value, both in prolonging the life of wells and in providing a much needed technical background for the legal problem of proration. But there are two principal aspects of the problem of production. It is necessary to consider not only the energy available, in the form of compressed and dissolved gas and in the pressure of driving water, but also the tenacity with which the sandstone holds the oil. The amount of oil that each sand condition will produce under given conditions of gas content should be determined. Hitherto the effect of the sand has been judged by a study of the flow of each well coupled with a procedure for extrapolating the production curve; hut, as is well known to evaluation engineers, such production curves are subject to changes that are not well understood, and often are affected by outside disturbances. On the whole, the concept of "potential production" is vague principally because the influence of the sand in production is not known beyond the simple ideas of porosity and permeability. The permeability is a quantity that has only inference value where mixtures of gas and oil or of gas, oil and water are present. Excellent studies of the production of oil from reservoirs packed with unconsolidatcd sand are available2, but these studies treat largely of small-scale analogzes to a producing field, and the conclusions to be derived from them arc necessarily of a qualitative character because it is not known in what way these miniature oil fields resemble large ones.

Jan 1, 1936

By Erwin H. Leeman, Raymond R. Rice, Gerald L. Hassler

In the past few years a great deal of preeise information has been obtained about the relation of natural gas to oil production1. The improvement of our understanding has been of great value, both in prolonging the life of wells and in providing a much needed technical background for the legal problem of proration. But there are two principal aspects of the problem of production. It is necessary to consider not only the energy available, in the form of compressed and dissolved gas and in the pressure of driving water, but also the tenacity with which the sandstone holds the oil. The amount of oil that each sand condition will produce under given conditions of gas content should be determined. Hitherto the effect of the sand has been judged by a study of the flow of each well coupled with a procedure for extrapolating the production curve; hut, as is well known to evaluation engineers, such production curves are subject to changes that are not well understood, and often are affected by outside disturbances. On the whole, the concept of "potential production" is vague principally because the influence of the sand in production is not known beyond the simple ideas of porosity and permeability. The permeability is a quantity that has only inference value where mixtures of gas and oil or of gas, oil and water are present. Excellent studies of the production of oil from reservoirs packed with unconsolidatcd sand are available2, but these studies treat largely of small-scale analogzes to a producing field, and the conclusions to be derived from them arc necessarily of a qualitative character because it is not known in what way these miniature oil fields resemble large ones.

Jan 1, 1936

By P. W. Bridgman

It is characteristic of most scientific investigators that they are not satisfied with the discovery of new facts, no matter how curious or unexpected, but that along with the factual discovery there is a constant effort to understand. It appears that one's interest in, and satisfaction with, the discovery of an array of new experimental facts is enormously increased if one has at the same time a theory or hypothesis guiding one's expectation of what sort of new experimental discovery may lie around the corner. Conversely, as a theoretical physicist one's satisfaction with his theory is greatly enhanced if along with the development of the theory can go the discovery of new experimental facts, confirming or perhaps modifying the theory as it grows. Of course, there have been long arid stretches in the history of physics in which new data of unquestioned ultimate importance have piled up, without much inspiration or illumination in the way of understanding. For 50 years spectroscopy had such an arid history, but how irksome this was felt to be is plainly shown by the almost audible relief that greeted the first success by Bohr in injecting understanding into the situation, and by the fresh rush of experimenters into this field when the prospect of understanding had once been offered. The investigations in the field of high pressure, which have occupied me for a long time,' until the last few years have been in very much the same sort of situation as spectroscopy before the advent of Bohr. A great many kinds of data were collected for a great many solid and liquid substances, and there could be no question of the importance of these data, because the uniform change of dimensions produced by hydrostatic pressure is perhaps the simplest conceivable type of alteration to which a body can be subjected. But except for a few isolated flashes, there was no theoretical illumination, so that it had to be to a large extent the enthusiasm of the collector that kept me going. However, within the last few years the wave-mechanics theory of solids has progressed so rapidly that

Jan 1, 1938

By P. W. Bridgman

It is characteristic of most scientific investigators that they are not satisfied with the discovery of new facts, no matter how curious or unexpected, but that along with the factual discovery there is a constant effort to understand. It appears that one's interest in, and satisfaction with, the discovery of an array of new experimental facts is enormously increased if one has at the same time a theory or hypothesis guiding one's expectation of what sort of new experimental discovery may lie around the corner. Conversely, as a theoretical physicist one's satisfaction with his theory is greatly enhanced if along with the development of the theory can go the discovery of new experimental facts, confirming or perhaps modifying the theory as it grows. Of course, there have been long arid stretches in the history of physics in which new data of unquestioned ultimate importance have piled up, without much inspiration or illumination in the way of understanding. For 50 years spectroscopy had such an arid history, but how irksome this was felt to be is plainly shown by the almost audible relief that greeted the first success by Bohr in injecting understanding into the situation, and by the fresh rush of experimenters into this field when the prospect of understanding had once been offered. The investigations in the field of high pressure, which have occupied me for a long time,' until the last few years have been in very much the same sort of situation as spectroscopy before the advent of Bohr. A great many kinds of data were collected for a great many solid and liquid substances, and there could be no question of the importance of these data, because the uniform change of dimensions produced by hydrostatic pressure is perhaps the simplest conceivable type of alteration to which a body can be subjected. But except for a few isolated flashes, there was no theoretical illumination, so that it had to be to a large extent the enthusiasm of the collector that kept me going. However, within the last few years the wave-mechanics theory of solids has progressed so rapidly that

Jan 1, 1938

By R. F. W. Pease, R. A. Ploc

A scanning electron microscope with a resolving power better then 100Å has been developed for the direct examination of surfaces. This instrument was used to study iron undergoing oxidation at 500°C. It was found that the electron current in the scanning electron microscope was low enough (about 10-atrzp) to have no observable effect on the growth of the oxide. "Armco " iron, when oxidized, exhibited an oxide film whose thickness and whiskey population varied with pain orientation; but purer iron, when oxidized, exhibited no such pain dependence and whisker occurrence appeared to be caused by impurities. UNTIL recently most surfaces of opaque specimens could either be studied with a light microscope or, if higher resolution was required, by viewing a replica of the surface in a transmission electron microscope. Direct electron microscopy of a surface has, in general, proved difficult owing to excessive foreshortening and the poor image quality obtained. The scanning electron microscope, however, offers an alternative method of directly viewing a surface without these disadvantages. At low magnification it offers a much larger depth of focus than the light microscope, and at high magnifications it offers much higher resolution (about 100Å). PRINCIPLE OF THE SCANNING ELECTRON MICROSCOPE A schematic diagram is shown in Fig. 1. The electron optical system consists of a gun followed by a series of lenses which focus the electron beam onto the surface of the specimen. The beam is scanned in a rectangular raster across the specimen surface and, by amplifying the secondary electron current from the 'pecimen, a picture of the specimen surface is built UP sequentially on the face of the display cathode-ray tube. The magnification of such a system is given by the ratio of the scan amplitude on the display cathode-ray tube to

Jan 1, 1965

By Clarence S. Ross

INTRODUCTION THIS chapter on the rô1e of physical-chemical processes in ore deposition presents unusual difficulties because it attempts to discuss the theory of processes that are very imperfectly under- stood, but which are among the most fundamental problems now before the student of ore formation. It is generally believed that a great variety of ore deposits are in some way derived from igneous rocks; but we desire to know the mechanism of their splitting off from the parent magma, the physical and chemical character of the material that acts as a medium for transfer from magma to the point of deposition, the manner of deposition, and the methods of replacement and removal of the invaded rocks. This problem is difficult for the field geologist because it concerns forces that for the most part have long since ceased to act. It involves a complex system of which the time for completion extends from the first development of the parent magma through its intrusion, its slow cooling and crystallization, and the final escape of its last residuum, a time probably represented by millions of years. In space the processes extend from profound depths of the abyssal magma which can never be directly observed, through the horizons characterizing deep-seated igneous rocks and ore deposits; those formed at moderate depths; and ends with surficial ones and surface thermal springs. The geologist usually can study the effect at but one of these horizons: he must attempt to fit his puzzle together while seeing but a few parts at a time. Thus he must deal with many isolated phenomena, as if they were the result of many physical and chemical systems; when in fact his problem involves a single exceedingly complex system, and will only be understood when that entire complex system is understood. The geophysicist is handicapped because he must attempt to interpret an extraordinary complex system, involving physical and chemical conditions which he can never hope to duplicate fully, through the study of many exceedingly simple systems.

Jan 1, 1933

By Bain, Edgar C.

THE results are presented of an investigation to discover the fundamental atomic conditions existing in Corson's high-copper alloys hardenable by means of silicide solution and reprecipitation. The study attracted the writer because it offered a very convenient example of the general type of hardenable alloys exemplified by duralumin. Sykes' iron-tungsten and iron-molybdenum alloys and the hardenable lead-antimony. SUMMARY OF RESULTS AND CONCLUSIONS In brief, the investigation shows that very perfect crystallinity exists in the solid solutions prepared at high temperature to contain as much dissolved silicide as possible. The lattice parameter of copper is altered very little by the amount of cobalt, nickel or chromium, and silicon dissolved. The hardening by drawing at a temperature to initiate precipitation of excess silicon and metal produces a remarkable change in the atomistics of the solid solution. The old perfection of crystallinity in the solid solution is destroyed and the new atomic spacings are of variable magnitude even in one grain, and a condition in a measure resembling that found in martensite is observed. Were no particles whatever precipitated by the drawing action, still ample causes for hardness would be in evidence in the solid solution alone. The lack of plane continuity in the crystal grains would oppose slip in a very effective manner. Complete annealing restores the crystalline perfection in large measure. In these alloys even the most sensitive methods failed to reveal the characteristic pattern of the silicide precipitated by the anneal, but this was largely to be expected as the amount is relatively small.

Jan 1, 1927

Albert SauveuR, South Chicago, Ill. (communication to the Secretary): Mr. Howe remarks (nuns., xxiii., 656) that, running through my paper, there is a tacit assumption that there is a constant and known relation between the coarseness of the grain of steel and its quality. The above assumption was not made tacitly. On the contrary, it is based upon the very experiments embodied in my paper. Indeed, most of those experiments were undertaken with that end in view, i.e., to ascertain the existence of such a relation. Mr. Howe calls attention to the fact that of two pieces of manganese-steel, originally from the same bar, the coarser-grained showed the greater strength and ductility. This refers to the fracture of the pieces; whereas, I have considered the micro-structure only, independent of the fracture; and I do not think that a coarse fracture

Jan 1, 1895

By J. C. Humbert, J. F. Elliott

The solubility of nitrogen in liquid pure Fe, Cr, and Ni, in liquid Fe-Ni, Fe-Cr, and Ni-Cr alloys and Fe-Cr-Ni alloys, has been measured by the Sieverts' type apparatus between 1500° and 1800°C. Tabulations and graphs of the solubility data and activity coefficients are shown. Heats of solution are reported. Interaction coefficients of the several elements in Fe. Cr, and Ni ave also reported. THE solubility of a gas in a liquid metal is usually measured by either the quenching technique or the so-called Sieverts' method. In the quenching method, 1-3 the melt is equilibrated at the desired temperature and pressure with the gas phase having a known fugacity of the gas being studied. The melt is sampled and the sample is quenched and analyzed chemically for its gas content. In Sieverts' method the melt is contained in a closed chamber. The apparent volume of this chamber, i.e. the "hot volume," is usually determined by introducing a known quantity of an inert gas having very closely the same physical characteristics as does the experimental gas. Alternatively, the experimental gas is used with an inert specimen having the same general physical characteristics as does the experimental melt. Subsequently, the experimental melt is equilibrated with the experimental gas by introducing a known quantity of the gas into the calibrated chamber. The solubility of the gas is obtained from P-V-T relationships. The quenching method suffers from' the limitation that some gas may be gained (as in the case of Cr-Fe alloys) or lost (as in the case of Fe-Ni alloys) during solidification and cooling of the sample. With Sieverts' method sampling and analysis are unnecessary. However, errors can result from the difficulty of determining accurately the "hot volume,"

Jan 1, 1961

By Francois E. Heuze

The Crestmore Mine of the American Cement Company lies at the eastern end of the Jurupa Mountains, 50 miles east of Los Angeles. Originally, a quarry was opened in 1908 for "limestone" used in the manufacture of cement. The mining operations eventually went underground employing first a modified system of block caving and later the "room and pillar" scheme. The limestones are relatively small roof pendants preserved in an enveloping and intrusive quartz diorite. They occur as two irregular lenticular bodies roughly parallel at the top and tending towards convergence at depth. Their dip varies between 25 and 30 degrees E. The presently mined lower bed, Chino limestone, is typically composed of alternating bands a few inches to a few feet thick of medium to coarsely granular white crystalline limestone and somewhat yellowish limestone (brucite marble). A "room and pillar" scheme of mining is currently employed in the lower body of the Crestmore Mine. The levels are horizontal and access is provided by a spiraling road starting in the old quarry. The present depth of operations is an average 750 ft below the surface. Fig. 1 gives a three-dimensional general sketch of the mine. The long axis of the rooms is in an E-W direction, normal to the strike of the beds. Fig. 2 is a horizontal map of the 130 level, the deepest level mined presently. It is in this level that most of the in-situ investigations have been conducted. The present investigation was made possible by a non-restrictive grant of the American Cement Company to the University of California. The program included a series of in-situ tests using flat-jacks, plate bearing,

Jan 1, 1968