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By Kenneth Seaver

Discussion of the paper of KENNETH SEAVER presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 105, September, 1915, pp. 1913 .to 1927. J. W. RICHARDS, South Bethlehem, Pa.-This paper concerns a very large industry, and an important detail in that industry. Within sight of where I live in Bethlehem, Pa., are coke works in which $2,500,000 was lost by the use of improper bricks in the coke ovens. This was the fundamental reason of the failure of the plant. The old ovens have all been torn out and replaced by new ovens built of proper bricks. This may emphasize the commercial importance of this subject. When speaking about coke-oven brick, the first thing that comes to my mind is how important it would he if it were possible to. get a brick of better heat conductivity. The heat for coking coal has to go through the thickness of the brick. The silica brick used has low heat conductivity as compared with some other refractories; magnesite brick probably has four times its heat conductivity. The coke oven needs bricks of high heat conductivity. Any process which would increase the heat conductivity of silica brick would undoubtedly shorten the coking process.

Jan 12, 1915

By Michel David

One of the most important questions that arises in ore estimation can be stated as follows: What is the error when one extends the grade of a sample to a certain volume? The theory of regionalized variables, with the concept of extension variance, provides a response to that crucial question for any kind of sample extended to any volume. For the usual "extensions" encountered in current mining practice, some simple results can be derived from that theory which was initiated by Dr. G. Matheron. These results have been applied to a stratiform lead-zinc deposit for which several estimations of grade, tonnage and related precision have been made for a series of grid sizes such as might be used in a progressive exploration program.

Jan 1, 1969

IN presenting the medalist, Scott Turner, director of 'the Bureau of Mines, said in part: "Mr. Blaylock is a Canadian by birth, training, ex-perience and preference. He was born in the Province of Quebec, graduated from McGill University in 1899, and immediately thereafter became an employee of the company for which he is now general manager. His outstanding achievements have been the acquisition for his company of the Sullivan mine, and the organization of a metallurgical staff, which, under his leadership and personal direction, solved the difficult problems pre-sented by the extraordinarily complex lead-zinc-silver ores of the Sullivan mine. "By title only, I will suggest to you the high lights of his career: (1) Development, of the great mine at Kimberley, and a huge plant at Trail. (2) Discovery and application of a successful differential flotation process for Sullivan ore which had previously not re-sponded to any process. (3) Improvements in lead-blast-furnace and refinery practice. (4) Development of an electrolytic process for treatment of zinc concen-trates. (5) Development of an electric-furnace-smelt-ing-method for zinc-plant residues. Besides this, we recognize his great organizing ability, his gift of leader-ship, and the cooperative spirit he always displayed.

Jan 3, 1928

HAVING shown you before how moulds of statues and also those of guns are constructed, I wish to tell you at present how, if you wish to cast them in bronze, you are further to prepare and arrange these moulds so that they may receive the melted mass of the metals in a friendly manner and without disturbance. I know that you understand that a real and intense heat has been intro-

Jan 1, 1942

On Feb. 16, 1948, the Board of Directors of AIME authorized the publishing of "Technical Notes" in METALS TECHNOLOGY. The purpose is to provide prompt publication of very short items of the following general types: I. Results of short investigations which do not warrant a paper. 2. The conclusions of extensive investigations of insufficient general interest to justify a regular paper. 3. Conclusions arising in the course of an investigation, which, because of interest to others in the field, the author wishes to present prior to completion of the investigation. 4. Pertinent factual comment (not mere argument) on the subject matter of previous "Notes." Such Notes will be subject to the approval of the Auxiliary and AIME Publications Committees, but can be handled more promptly than regular papers because they need not be referred to readers. The recommended maximum length is 500 words; notes in excess of 1,000 words will not be considered for this type of publication. A graph or photograph may be included as part of the note when particularly illustrative. As with regular papers, contributions to the new section should be submitted to the Secretarv of the AIME. Please furnish two copies, each complete with illustrations.

Jan 1, 1948

By P. A. Freeman, T. W. Healy, D. R. Dixon, L. O. Kolarik, D. N. Furlong

The effect of water, acid and alkali washing on the surface properties of natural magnetite were investigated by microelectro-phoresis. The general control on the isoelectric point ([i]ep) of the natural magnetite that is effected by colloidal and adsorbed silicate species can be reversed by various acid/alkali washing procedures. Added aqueous silicate and aluminium ions lower and raise the [i]ep to values consistent with hydrous silica and alumina coatings respectively.

Jan 1, 1980

I. PRESIDING OFFICERS. At all Business meetings of the Institute the President, or, in his absence, the Vice-President, or, in the absence of both of them, any other member of the Board of Directors to be chosen by the meeting, shall preside. At all other meetings of the Institute the President of the Council or, in his absence, one of the Vice-Presidents, if present, shall preside II. ORDER OF BUSINESS. At each Business meeting of the Institute the order of business shall be as follows 1. Reading of minutes of preceding meeting. 2 Report of the President. 3. Report of the Treasurer. 4. Report of the Secretary. 5. Election of Directors. 6. Election of Members of the Council. 7. Reports of Standing Committees. 8. Reports of Special Committees. 9. Special Orders 10. Miscellaneous business. This order of business may be changed by a vote of a majority of the Members and Associates present in person or by proxy. The usual parliamentary rules shall govern all meetings of the Institute except in cases otherwise provided by the Constitution or the By-Laws. At all sessions of the Institute other than business meetings, the order of proceedings and the time of adjournment, shall rest in the discretion of the presiding officer

Jan 1, 1910

Iraq Petroleum Co. together have produced more than 2,000,000 bbl. from all areas since 1927, most has been returned to the reservoir through the wells. Iraq Petroleum Company's small skimming plant at kirkuk supplies its operating requirements. Drilling Operations The Iraq Petroleum Co., since 1930, has discontinued exploratory drilling and concentrated on the exploitation of the Kirkrik field preparatory to filling its 84,000 bbl. pipe line. Drilling operations are on schedule and the I.P.C. expects to have its initial producing wells ready to turn into the line by April of this year. The Mosul Oil Fields Ltd., holding company of all the shares in the British Oil Development Co., after acquiring the "West Tigris Concession" in May, 1932, has completed a geological survey of its 46,000 square miles and is entering upon an exploratory drilling program with three cable-tool rigs. Petroleum in Iraq Transferred Territories in 1933* The Khanaqin Oil Co., which operates the Naft Khaneh field in the so-called Transferred Territories, has continued to supply the Iraq market with petroleum products during the period under review. The output of it's refinery at Alwand during the past three fiscal years ending March 31 has been as follows:

Jan 1, 1934

By Charles Clayton

CAST-STEEL runners, while not interesting from a commercial standpoint, furnish valuable material for microscopic study. Foley1 found not only the usual ingot structure, but zones of Widmannstattian structure, which he explains as due to differential crystallization. The writer, in examining nickel-steel runners, found a type of pro-eutectoid ferrite that is unusual and most probably new. The runner in question was 8.75 cm. (3.5 in.) in diameter and analyzed at its center 2.69 per cent, nickel and 0.350 per cent. carbon and at its edge 2.62 per cent. nickel and 0.359 per cent. carbon. The macrostructure, which is the usual type, is shown in Figs. 1 and 2, which are a cross-section and the longitudinal surface, respectively. Slight segregation of ferrite can be seen near the center of the segment and at other points near the edges of polyhedral grains. Stead's reagent brings out the dendritic structure within the grains as shown in Figs. 3 and 4. This texture is what would be expected of such a steel. Figs. 5 to 10 show the peculiar swirls of pro-eutectoid ferrite, the finding of which prompted this paper. These swirls, or eddies, if such a term can be applied, occur in all parts of- the runner and in all parts of the individual grains. I he tipper left-hand figure shows this ferrite at a grain boundary; the middle left-hand figure shows the inner portion of a grain; and the lower left-hand figure shows these swirls at the edge of a grain which is also the outer edge of the runner. Straight-lined ferrite associated with swirls is found in the areas of Figs. 11 and 12. The texture of the carbon-bearing constituent of the runner is shown to- some extent in Fig. 12, the pearlite being very fine or sorbitic. Higher magnification does not bring out any new features either in the peculiar ferrite or in the pearlite. Figs. 13 and 14, at 240 diameters, show the curved and straight-lined ferrite.

Jan 3, 1920

By Eugene Guccione

It would be extremely difficult and unfair to compare the United States to Australia when wondering about which of the two countries offers the best opportunities for running a mining operation. However, if somebody would ask "Where is the best place to mine outside the US?"-I'd answer without reservations: Australia. Some of my Australian mining friends will disagree with me for my giving their country such a high rating. And they'll probably accuse me of being an optimist by telling me, as one of them did, that "the difference between an optimist and a pessimist is that the pessimist is better informed."

Jan 1, 1977

THE progress in lead smelting practice in the United States during 1930 has been along previously defined lines. Since most of the material treated is high-grade concentrate relatively high in zinc, practically all the plants have been forced to adopt double sintering. This generally results in there being' no matte fall, and most of the copper in the charge is recovered in the furnace dross. The furnace dross is . smelted with. scrap iron and flux .in small reverberatories, giving a shipping matte or speiss high in copper and low in lead. Details of this reverberatory. furnace practice vary at the different plants. There is a decided tendency toward moreintensive filtration of blast- furnace and sinter fume. Bag capacity has been in- creased by using higher pressures and more frequent shaking.

Jan 1, 1931

By A. D. K. Laird, John A. Putnam

This paper describes the application of x-ray theory to design procedures in connection with fluid saturation determinations during fluid flow experiments with porous media. A reliable and rapid method for calibrating the x-ray apparatuy is described. Extension of the method to fluid saturation determinations in three-fluid systems is described. INTRODUCTION In rerearch on oil production problems a method is required which will give quickly the quantity of each component of a fluid flow system present at any cross-section of a porous medium. The sample of porous medium under investigation is usually referred to as a core. The ratio of the volume of one component to the total fluid volume is defined as the saturation of the porous medium by that component. This ratio is generally given as per cent saturation. Some means of measuring saturation which have received consideration include: electrical conductivity of the fluids;1,2 emissions from radioactive tracers dissolved in the fluids; the radioactivity of silver caused by reflection of neutrons from hydrogen atoms in the fluids;' the attenuation of a microwave beam. the diminution and phase shift of ultrasonic wave trains.4,5 and the reduction in intensity of x-ray beams in passing through the fluids. X-rays have already been used with some success. Since every material has a different power to absorb x-rays, the reduction in intensity of an x-ray beam as it passes through a core depends on the fluids present. The strength of the emergent beam can be found by converting its energy into a measurable form such as heat or ionic current. or by its effect on a photographic plate or fluorescent screen. The beam strengths could be interpreted as quantities of known fluids in the core if, previously, these beam strengths had been identified with a known combination of the same fluids. With some fluid cornbinations it might be desirable to dissolve powerful x-ray absorbing materials in one or more of the fluids, to increase the differences in the beam strengths for various fluid saturations. Boyer, Morgan and Muskat6 have described a method of measuring two component fluid saturation. One component was air or water; the other. minerat seal oil in which was dissolved 25 per cent by weight of iodobenzene to increase its absorbing power. The x-ray source was a tungsten target tube operated at 43 kv potential. The beam emerging from the core was measured as ionic current flowing across an air-filled ionization chamber by means of an amplifying circuit and galvanometer. Another portion of the beam from the x-ray tube was passed through a metal plate and measured in another ionization chamber. This portion, called the monitor beam, was used as an indication of the performance of the x-ray tube. The galvanometer readings were calibrated against air-oil core saturations, gravimetrically determined. The method was apparently established by experimental means. In the present investigation the available theory of x-radia-tion was surveyed with a view to extending the usefulness of the method and to developing design procedures for its application to measurement of fluid saturation in porous media. Application of the theory permits prediction of relative meter readings to be expected for any combination of porous matrix, various saturating fluids and auxiliary filtering media. It is thus possible to calibrate the equipment in terms of fluid saturation by an indirect but rapid technique. The results of calculations based on x-ray theory indicate. and results of the saturation calibration technique confirm. that a valid measurement of the saturation of the core can be made for any two components and in some cases for three components. THEORY The strength of an x-ray beam, after it has passed through a distance. 1, of matter of density, p, and mass absorption coefficient, µ at a given wavelength, A, may be expressed by the absorption formula I = I0 e ...........(1) where I, represents the intensity of the incident x-ray beam and I is the intensity of the emergent beam. The expression e is called the transmission factor of the material. The variation of I,, with wavelength depends upon the materials through which the x-ray beam has previously passed and upon the spectral distribution of energy at the source of the x-radiation. A group of curves. called spectra. which show the variation of intensity with wavelength and x-ray tube voltage are given in Fig. 1. These curves represent the general radiation from a tungsten target tube. When the tube voltage is greater than 69.3 kv, the characteristic radiation of the tungsten is emitted and is superposed on the general radiation. At a given voltage the minimum wavelength A,,,,, at which energy can be emitted by an x-ray tube is given by the formula 12,340 xml. = ——..........(2) volts where A,.,,.. is in Angstrom units. The wavelength at which the spectra have maximum intensity a1so decreases with increasing x-ray tube voltaue. The area under each curve represents to an arbitrarv scale the total energy emerging from the x-ray tube for that voltage. The variation of µ with wavelength has been determined for many substances and may be found in such references as those by Compton and Allison7 and by Hodgman.8 The phenomenon of absorption is composed chiefly of the capture of photons by the atoms of the absorbing material with associated displacement of electrons, and of the scattering, or the deflection, of the photons by the atoms. Curves of these mass absorption coefficients show jump discontinuities. or absorption edges. at wavelengths which are short enough for the photons,

Jan 1, 1951

By John A. Putnam, A. D. K. Laird

This paper describes the application of x-ray theory to design procedures in connection with fluid saturation determinations during fluid flow experiments with porous media. A reliable and rapid method for calibrating the x-ray apparatuy is described. Extension of the method to fluid saturation determinations in three-fluid systems is described. INTRODUCTION In rerearch on oil production problems a method is required which will give quickly the quantity of each component of a fluid flow system present at any cross-section of a porous medium. The sample of porous medium under investigation is usually referred to as a core. The ratio of the volume of one component to the total fluid volume is defined as the saturation of the porous medium by that component. This ratio is generally given as per cent saturation. Some means of measuring saturation which have received consideration include: electrical conductivity of the fluids;1,2 emissions from radioactive tracers dissolved in the fluids; the radioactivity of silver caused by reflection of neutrons from hydrogen atoms in the fluids;' the attenuation of a microwave beam. the diminution and phase shift of ultrasonic wave trains.4,5 and the reduction in intensity of x-ray beams in passing through the fluids. X-rays have already been used with some success. Since every material has a different power to absorb x-rays, the reduction in intensity of an x-ray beam as it passes through a core depends on the fluids present. The strength of the emergent beam can be found by converting its energy into a measurable form such as heat or ionic current. or by its effect on a photographic plate or fluorescent screen. The beam strengths could be interpreted as quantities of known fluids in the core if, previously, these beam strengths had been identified with a known combination of the same fluids. With some fluid cornbinations it might be desirable to dissolve powerful x-ray absorbing materials in one or more of the fluids, to increase the differences in the beam strengths for various fluid saturations. Boyer, Morgan and Muskat6 have described a method of measuring two component fluid saturation. One component was air or water; the other. minerat seal oil in which was dissolved 25 per cent by weight of iodobenzene to increase its absorbing power. The x-ray source was a tungsten target tube operated at 43 kv potential. The beam emerging from the core was measured as ionic current flowing across an air-filled ionization chamber by means of an amplifying circuit and galvanometer. Another portion of the beam from the x-ray tube was passed through a metal plate and measured in another ionization chamber. This portion, called the monitor beam, was used as an indication of the performance of the x-ray tube. The galvanometer readings were calibrated against air-oil core saturations, gravimetrically determined. The method was apparently established by experimental means. In the present investigation the available theory of x-radia-tion was surveyed with a view to extending the usefulness of the method and to developing design procedures for its application to measurement of fluid saturation in porous media. Application of the theory permits prediction of relative meter readings to be expected for any combination of porous matrix, various saturating fluids and auxiliary filtering media. It is thus possible to calibrate the equipment in terms of fluid saturation by an indirect but rapid technique. The results of calculations based on x-ray theory indicate. and results of the saturation calibration technique confirm. that a valid measurement of the saturation of the core can be made for any two components and in some cases for three components. THEORY The strength of an x-ray beam, after it has passed through a distance. 1, of matter of density, p, and mass absorption coefficient, µ at a given wavelength, A, may be expressed by the absorption formula I = I0 e ...........(1) where I, represents the intensity of the incident x-ray beam and I is the intensity of the emergent beam. The expression e is called the transmission factor of the material. The variation of I,, with wavelength depends upon the materials through which the x-ray beam has previously passed and upon the spectral distribution of energy at the source of the x-radiation. A group of curves. called spectra. which show the variation of intensity with wavelength and x-ray tube voltage are given in Fig. 1. These curves represent the general radiation from a tungsten target tube. When the tube voltage is greater than 69.3 kv, the characteristic radiation of the tungsten is emitted and is superposed on the general radiation. At a given voltage the minimum wavelength A,,,,, at which energy can be emitted by an x-ray tube is given by the formula 12,340 xml. = ——..........(2) volts where A,.,,.. is in Angstrom units. The wavelength at which the spectra have maximum intensity a1so decreases with increasing x-ray tube voltaue. The area under each curve represents to an arbitrarv scale the total energy emerging from the x-ray tube for that voltage. The variation of µ with wavelength has been determined for many substances and may be found in such references as those by Compton and Allison7 and by Hodgman.8 The phenomenon of absorption is composed chiefly of the capture of photons by the atoms of the absorbing material with associated displacement of electrons, and of the scattering, or the deflection, of the photons by the atoms. Curves of these mass absorption coefficients show jump discontinuities. or absorption edges. at wavelengths which are short enough for the photons,

Jan 1, 1951

By Robert Parker

Measurements of the latent heat of transformation from a to 0 titanium were made using a pulse-heating technique. Rapid heating was accomplished electrically by discharging a low-inductance capci-tor hank through a thin-strip specimen. Both high-purity titanium and titanium containing 2700 ppm of 0 were studied. An electrical-resistivity technique and a plot of energy input us temperature rise were used to monitor the phase change. It was concluded that: 1) the latent heat of transformation is 800 i 48 cal per mole; 2) phase change occurred in less than 200 sec; and 3) the percentage phase change that occurs is linearly a function of the energy available for phase change. In addition, this experiment provides a simple and inexpensive method for determining specific heat of electrical conductors over large temperature ranges. The chief advantages of this technique over past pulse-heating experiments are: 1) static measurements of capacitor-bank voltage capacitance and specimen resistance can be made quickly and accurately to determine the energy supplied to the specimen; 2) the specimen is heated so rapidly (10 µ sec) that there is no appreciable heat loss during the heating. THE purpose of this paper is to illustrate the use of the capacitor bank as a tool for basic experimental investigations and to determine the rapid phase-change kinetics of titanium. The capacitor provides a number of unique properties: 1) rapid heating rates in the order of l09oC per sec can be obtained; heating rates as slow as l04oC per sec are available by merely adding a given amount of inductance to the circuit; 2) the energy input can be precisely determined and can be varied from several joules to millions of joules, depending on the bank capacitance and voltage; 3) the specimen can be heated uniformly through the thickness and length or non-uniformly, as desired; 4) the apparatus is simple and inexpensive and can be easily altered; 5) the form of the specimen can be wires, sheets, foils, rods, and cylinders; 6) there is great precision in the timing of events; 7) this technique may be readily used in conjunction with rapid cooling.

Jan 1, 1965

By G. V. Smith, R. F. Mehl

The decomposition of austenite in steels, because of its immerse practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1"3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings—pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. -As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. Pearlite Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix.2--5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the' parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrong!:!, as Mehl and Smith6 have pointed out, that the lamellae delineate the {2I0} planes of ferrite.* Martensite It is known that martensite is a transiti0nal constituent of body-centered tetragonal lattice,' and that it forms suddenly

Jan 1, 1942

By R. F. Mehl, G. V. Smith

The decomposition of austenite in steels, because of its immerse practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1"3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings—pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. -As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. Pearlite Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix.2--5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the' parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrong!:!, as Mehl and Smith6 have pointed out, that the lamellae delineate the {2I0} planes of ferrite.* Martensite It is known that martensite is a transiti0nal constituent of body-centered tetragonal lattice,' and that it forms suddenly

Jan 1, 1942

By E. L. Dougherty, J. W. Sheldon

A numerical method for computing the dynamical behavior of fluid- fluid interfaces is described. Results of studies made to assess the accuracy and economy of the method on a computer are reported. It is concluded that it is practical to obtain digital computer solutions for fluid- fluid interface problems with two space dimensions. PROBLEM DEFINITION We consider two-dimensional flow in a rectangle as shown in Fig. 1, where a fluid-fluid interface divides the rectangle into two regions. The pressure is specified along the lower boundary (the injection boundary) and upper boundary (the withdrawal boundary). There is to be no flow of fluid across the side boundaries, which are walls of symmetry for the flow, and px = 0 along these boundaries. The fluids are incompressible, the absolute permeability and porosity is constant, and each fluid has its own constant mobility. Thus, the pressure satisfies Laplace's equation in each region. Across the interface, pressure is continuous and the normal component of fluid flux is 1. These conditions are shown in Fig. 1. The velocity of a point on the interface in the direction of the normal from Fluid 1 into Fluid 2 is U,/ Q, where Un is the normal component of volumetric flux at the point on the interface, i.e., For brevity, we call the problem defined above "Problem A". Problem A is a simple example of a dynamical fluid-fluid interface problem. However, the same numerical methods which we use to solve Problem A can be extended to the solution of a large number of fluid-fluid interface problems which are mathematical models for various oil recovery processes,l hence our interest in Problem A. We define the interface by prescribing the x, y coordinates of a finite set of points. These points are called "interface mesh points" and are illustrated by triangles or asterisks in the figures. Fig. 2 is a procedural (flow) chart displaying the main steps in the solution. We comment briefly on some of these steps in this section and then give further details in subsequent sections. For mobility ratio greater than one it is well known that Problem A is unstable.*2 Small amplitude,

Jan 1, 1965

By W. A. Tiller

The unidirectional freezing of a semiinfinite liquid from one end has been treated by calculating the solute and temperature distributions in the liquid and solid phases with time, when the solid-liquid interface advances at a rate proportional to (time)lt2. The nucleation probability for new grain formation is calculated as a function of the constitutional and thermal properties of the alloy, the pouring conditions and the catalytic efficiency of the nucleating agents. The transition from columnar crystal formation to equiaxed crystal formation is assumed to occur at a critical nucleation frequency for a particular alloy and the quantitative dependence of the ratio (columnar zone length/equiaxed zone length) upon the freezing conditions has been predicted. The effects of (i) fluid flow in the liquid, (ii) heat transfer through a mold wall, and (iii) a finite ingot length, have been explicitly tveated as departures from ideality. These departures from ideality are found to have very important consequences on the ingot stmcture. In Part I&apos; of this series, a qualitative description of the general ingot structure was developed. The factors that determine i) the ratio of the equiaxed zone length to columnar zone length and ii) the grain sizes in these zones, were discussed. In the present paper, topic (i) will be treated quantitatively, and it is intended that topic (ii) will be treated quantitatively in Part 111. The complete treatment has been split in this manner for ease of development and coherency of presentation. The treatments are quite mathematical in nature and, although some of the conclusions to Part 11 depend upon the treatment presented in Part 111, it was felt that the intended audience would find the material more readable and more useful in its present form. To this same end, it seems worthwhile to reiterate some of the qualitative aspects of grain nucleation during ingot solidification before embarking on the mathematical description. QUALITATIVE ANALYSIS In the conventional method of casting, a liquid alloy with a certain degree of superheat is poured into a mold. The outer rim of liquid metal cools rapidly to the liquidus temperature of the alloy and begins to undercool. As the degree of undercooling increases, nuclei of solid begin to form in this chill layer, this nucleation being catalyzed by certain heterogeneous particles in the liquid. The grains in the chill layer which are generally of random orientation, begin to grow inwards because of heat conduction through the mold. The grains usually develop a columnar shape since the frequency of nucleation of new grains in the liquid ahead of the advancing interface is generally insufficient to seriously impede the growth of the original grains. Due to the slow diffusion rate of solute in the liquid, a solute distribution is formed in the liquid adjacent to the interface which is either an excess or a depletion if the partition coefficient, ko, of the solute is < 1 or > 1, respectively. Thus, the liquidus temperature of the liquid adjacent to the interface is a function of position. The actual temperature in the liquid is also a function of position and the temperature gradient at the interface decreases as the interface moves away from the mold wall. Since the rate of advance of the interface decreases with time, the equilibrium temperature distributions and the actual temperature distributions as a function of interface position, X, can be illustrated as in Fig. 1. Thus, a region of liquid may exist in which the actual temperature is below the liquidus temperature. This liquid is contitutionally supercooled and therefore unstable with respect to the nucleation of new grains. Now, since the supercooling in Fig. 1 increases as the interface moves further away from the mold wall, the nucleation rate of new grains will increase. When the nuclea-

Jan 1, 1962

By W. O. Crosby

WASHINGTON CAMP, in Santa Cruz county, Arizona, is a small and little known mining district situated on the lower, eastern slope of the Patagonia mountains, about 20 miles east of Nogales and a like distance south of Patagonia Station on the Sonora railroad, which connects it Benson, 83 miles from Nogales, with the main line of the Southern Pacific. This district is also about 4 miles north of the international boundary, 35 miles west of Bisbee and 40 miles north of Cananea, in Sonora. The topography of the district, which lies at a general elevation of 5,500 ft. above the sea, is only very moderately rugged, and presents no obstacles to mining operations. Although some of the claims of the camp, including the Pride of the West, Belmont and Holland, were extensively worked for silver 25 years ago, they passed, at moderate depths, as in so many other districts, out of the argentiferous lead carbonate and sulphide into zinc, copper and iron sulphides; and for two decades the camp was abandoned and almost forgotten. In recent years, however, its apparent possi¬bilities as a copper producer have led to a revival of mining activity; but not, as yet, with conspicuous success. Although economically relatively unimportant, the deposits of Washington Camp are, mineralogically and structurally, nevertheless, typical examples of ore-bodies developed in connection with the garnet ledge now recognized as a normal feature of granite-limestone contacts; and, in the opinion of the writer, this is an instance where a minor example is yet essentially normal and capable of throwing important light upon the origin and genetic relations of the type.

Nov 1, 1905

By T. T. Read

TWO papers on health and safety were given Thursday afternoon when a joint session of the Health and Safety Committee and the Mining Methods Committee was held. T. T. Read presided and the first paper, on ventilation at Climax, was presented by the author, L. H. Glanville. In the subsequent discussion by Cloyd M. Smith, P. B. Bucky, B. F. Tillson, D. F. Haley, J. L. G. Weysser, and others a number of interesting points not covered by the paper, which appears in full in the January Mining Technology, were brought out. Ventilation troubles in mines so often hinge on the air being too hot and damp that it was interesting to hear of one where it is frequently too cold and too dry.

Jan 1, 1943