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The suggestions of the members of the Institute are very much desired by-the Committee on Nominations prior to deciding upon its nominations to fill the places of those officers who retire early in 1917. The Committee must make its final report to the Board of Directors early ill October. The members are, therefore, -asked to send in promptly their suggestions for Directors as well as for Vice-Presidents and President. The Committee hopes to hear from a large number of the members. The officers to be elected at the annual meeting in February, 1917, are: One officer, known as Director and president. Two officers, known as Director and Vice-President. Five officers, known as Director. The attention of members is called to Articles V and VII of the Constitution, and to By-Law XIII, which reads as follows: "The geographical districts to be considered by the Committee on Nominations shall be as follows, until otherwise ordered by the Board. District No. 1. New England, New York, and New Jersey, excepting New York

Jan 9, 1916

By K. Torssell, U. Lindborg

The kinetics of precipitation deoxidation is considered from a theoretical point of view. The size distribution and the total content of deoxidation products are estimated statistically as a function of time, taking into account Stokes and gradient collisions between the particles and separation at the top surface of the bath. The assumption is made that two particles coalesce into one larger particle as a result of a collision. General expressions are derived and calculations are carried out numerically for the case of silica particles in liquid iron. The analysis predicts a three-stage behavior for the removal of oxygen, an incubation stage, a stage of rapid separation, and a slow final stage where the content approaches the equilibrium value. The agreement with experimentally determined size distributions and deoxidation times is considered to be good. A quantitative estimation of such growth mechanisms as diffusion from the melt and redistribution of oxygen from small particles to large ones shows that these latter mechanisms cannot explain the experimentally observed gvowth of inclusions. This also indicates that collisions provide the important growth mechanism. OXIDE inclusions precipitate when a deoxidizer like silicon or aluminum is added to a steel bath. The inclusions grow and the large particles tend to separate from the bath. For each type of oxide the growth determines the sizes of the final inclusions as well as the total inclusion content of the steel. The mechanism of growth is controversial, however. It has been suggested that an inclusion grows principally by diffusion of atoms through the melt to the inclusion particle or principally by collisions and coalescence with other inclusions. Diffusion growth is always present to some extent but recent experiments and calculations by Torssell,' Kniippel et 'a1.,2 Sano et al. and Miya-shita4 indicate that collisions may be more important than previously realized. A detailed analysis has so far been lacking. The present paper is a quantitative, statistical analysis of the growth and separation of inclusions and is based on a collision theory. Nuclea-tion is not considered. The numerical estimates are based on the experimental conditions of Torssell's' investigation and comparisons are made with his observations. Torssell' studied the growth and separation of silica particles in liquid iron. Samples were taken from a 0.6 kg iron bath at various times after the addition of silicon. By a particle-counting technique developed by Bergh and Lindber~the size distribution of the inclu- sions was determined. The number of particles at the first sampling, 10 sec after silicon addition, was of the order of 3 x lo7 to 10' per cu cm, the largest particles having a radius of 2 to 4 pm. The volume fraction was 0.001 to 0.004; i.e., the dispersion was very dilute. During subsequent holding the largest particles increased their radius by a factor of 10 after about a minute, and the whole size distribution was displaced toward larger values. These results were obtained with allowance for precipitation of the equilibrium concentration of oxygen during solidification. The bath contained less than 0.01 pct of C. Figs. 1 and 2 show the typical appearance of the inclusions. Most particles are very closely spherical and appear to have been liquid or semiliquid in the melt. The observed number of inclusions, about 5x 10' per cu cm, is of the same order of magnitude as found by ~er~h.' This is a large value. It follows that the diffusion distances are very short and that the precipitation

Jan 1, 1969

By Lewis T. Wright

IT is commonly believed by metallurgists that in copper-smelting, the copper in the slags, which is irreducible by continued smelting, is retained in the form of "prills" of matte. I have frequently held well-settled slag in a molten condition for a long period without being able thereby to reduce the copper-content. The slag acted as though it contained a minimum of dissolved or combined copper that could not be settled out by gravity. I have used reagents, but without satisfying myself in what form this copper existed. The same slags, by fine grinding and elutriation, could not be separated into portions containing more or less copper than the average content. By treating copper-slags in an electric furnace an impure button of copper. was produced, but the high temperature and the strong reducing-action of the furnace were influences that suggest an explanation of a result not obtainable with ordinary smelting-temperatures. If all the copper in the slag were in the form of copper-matte, and not existing as a dissolved compound with some of the elements of the slag, then the other metals in the matte, such as gold and silver, should occur in the slag in the same ratio to the copper as to the copper in the accompanying matte. This reasoning led me to study the ratio of metals in the products of smelting, and, apart from the issues discussed in this paper, the research has proved both interesting and illuminative. On the assumption of a similar ratio of metals in matte and slag, if the percentage of copper in the slag accompanying; a matte containing 50 oz. of silver and 1 oz. of gold per ton of copper was 0.3 per cent., or 96 oz. per ton of slag, there should be found 0.15 oz. of silver and 0.003 oz. of gold per ton of slag:; but, in my experience, there is less silver and much

Sep 1, 1909

For the year ending February, 1936 PRESIDENT AND DIRECTOR HENRY A. BUEHLER ROLLA, Mo. PAST PRESIDENTS AND DIRECTORS FREDERICK M. BECKET NEW YORK, N.Y. HOWARD N. EAVENSON PITTSBURGH, PA. VICE-PRESIDENT, TREASURER AND DIRECTOR KARL EILERS NEW YORK, N. Y.

Jan 1, 1934

By William Klement

KNELLER' has recently reported that extensive metastable solid solutions may be obtained in Cu-Fe alloys by simultaneous vapor deposition. This note reports that solid solutions, apparently single -phase, can be obtained for Cu-Fe alloys containing 0 to 20 and 85 to 100 at. pct Fe by rapid quenching from the melt; the inability to extend the solid solubilities further is related to the liquid miscibility gap, Fig. 1, as for Cu-Co alloys.2'3 Accurate lattice spacings of the copper-rich fcc and iron-rich bcc solid solutions have been obtained. Homogeneous alloys were prepared by casting4'5 and sintering2 from elements of 99.9+ pct purity. The quenching techniques were as before,' except the iron-rich alloys were liberally covered with argon while at elevated temperatures. Flakes about 1 sq mm in area were obtained and investigated with the Debye-Scherrer technique, as previously described.2,4 All X-ray work was done at 25° 2°C using filtered copper and cobalt K radiation. Relative visual intensities of the diffraction lines for the phases in the quenched alloys are shown in Table I. The lattice spacings of the fcc structure for alloys containing up to 80 at. pct Fe are plotted in Fig. 2. The variation of these lattice parameters with composition is in good agreement with the re- of cementite spots usually present (all hkl reflections are allowed) and the ease of confusing them with ferrite or martensite reflections. Copies of the report can be obtained by writing to the Materials Research Department, Rocketdyne. 6633 Canoga Avenue, Canoga Park, Calif., 91304. A copy is also available at the Engineering Societies Library, 2nd floor, 345 East 47th Street, New York, N.Y., 10017. Photocopies, either full-size or microfilm, may be purchased from the Engineering Societies Library. sults6 of Andersen and Kingsbury, Fig. 2, although there is some disagreement in absolute value. This discrepancy may be due to the different temperatures at which the X-ray measurements were carried out and perhaps to the different extrapolation procedures. Also, Andersen and Kingsbury6 state that their lattice spacings were computed relative to the wavelengths given by Siegbahn in 1933; this reference has not been found and it is assumed that the well-known 1931 wavelengths were used, the lattice spacings then being in kx units which are converted into angstroms by the factor 1.00202. There is no support for the contention that solution of iron decreases the lattice parameter of copper, as con-

Jan 1, 1965

By C. A. WARNER

IN all the meetings of the Petroleum Division, emphasis was placed on the essential importance, in the successful furtherance of our war effort, of efficiently producing, transporting, refining, and utilizing maximum quantities of crude oil and natural gas with the minimum expenditure of critical material. With representatives present from all branches of the petroleum industry, from all parts of the United States, the sessions were opened Tuesday morning with Commander Harry P. Stolz. U.S.N.R., Chairman of the Division, and A L. Haider as associate chairmen. From that time until the symposium on petroleum economics was closed Thursday afternoon papers of exceptional interest and importance were presented and discussed in a most frank and open manner.

Jan 1, 1943

By GUY C. RIDDELL

ZINC, manganese, and aluminum received attention at the two nonferrous metallurgy sessions at the Annual Meeting. L.P. Davidson, general superintendent of the rebuilt Monsanto zinc plant, described its operation, which reflects Polish practice and is really a combination of electrolytic, Waelz, and retort procedure. Briefly, it embraces leaching of roasted concentrate with sulphuric acid, electrolysis of sulphate solution using Tainton lead-silver anodes with ?goulac? added to the electrolyte, treatment of tailing in Waelz kilns, and retorting of the recovered zinc oxide, casting furnace dross and residues. Recovery is good, equipment and maintenance costs low. Ferrate zinc that might be lost in the electrolytic process appears to be recovered as oxide in the Waelz treatment.

Jan 1, 1942

By T. F. Witherbee

In a paper read at the Lake Superior meeting, August, 1580, an account was given of the successful use of Rendrock. and Monaky powder upon a .scaffold- and salamander in the furnace. On April 5th, 1881,' the same trouble called for like treatment, which, though not so immediately successful, was on the whole more instructive than the first trial, and points, I trust, to a reasonably sure remedy for all such difficulties. Up to December 4th, 1880, foundry and mill iron were made from Old Bed and Sew Bed magnetite, and Kearney red hematite, when a return was made to Bessemer iron, from an inferior quality of New Bed ore as compared with that used during first blast. January lath, 1881, New Bed, Chateangay, and East-shaft, a newly-opened Bessemer deposit of Messrs. Witherbee, Sherman $ Co., were first used, and continued up to February 13th, on a fuel charge of 80 per cent. anthracite and 20 per cent. coke, the product on the three ores being about 10 tons more per day than on New Bed alone. From this time until March 11th all coal was used, and New Bed, Chateaugay, and East-shaft ores, up to February 224 and from that date Chateaugay and New Bed, the product falling off 9,8, tons per day as a result of not using coke. It is fair, however, to state that the furnace was not in good condition during this period, being over-burdened, and the New Bed ore was, temporarily, uncommonly poor, for reasons of no particular interest here. It required to properly flux it at least 140 per cent. of limestone; and 101 per ent. was actually used. March 11th, all Chateaugay ore aid 80

Jan 1, 1882

By I. E. Rosenzweig

GeophyGical prospecting by earth-resistivity methods is frequently applied to investigation of structural problems in geology. Fig. 1 indicates a scheme of the general arrangement used in these methods of measurements. The battery (or generator) E is connected with two "current electrodes" I1 and I2. The current of intensity J, supplied by this battery, passes through the earth between these elcc- trodes. A potential difference U will be measured between two other electrodes V1 and Vz, called "potential electrodes." According to the configuration of electrodes (Fig. I), the resistivity of a homogeneous soil results from the formula p — 2rca-j [1] where 1 C = -------------------------------------- a a 1 a a [2]

Jan 1, 1940

By I. E. Rosenzweig

GeophyGical prospecting by earth-resistivity methods is frequently applied to investigation of structural problems in geology. Fig. 1 indicates a scheme of the general arrangement used in these methods of measurements. The battery (or generator) E is connected with two "current electrodes" I1 and I2. The current of intensity J, supplied by this battery, passes through the earth between these elcc- trodes. A potential difference U will be measured between two other electrodes V1 and Vz, called "potential electrodes." According to the configuration of electrodes (Fig. I), the resistivity of a homogeneous soil results from the formula p — 2rca-j [1] where 1 C = -------------------------------------- a a 1 a a [2]

Jan 1, 1940

By H. B. Huntington

Some of the basic problems in understanding elec-tromigration in metals are discussed, along with the attempts that are being made to handle them. One such problem is the effect of the electrostatic forces. It is now acknowledged that the momentum exchange with charge carriers plays generally a dominant role in the driving force but the question remains to what extent the electrostatic force may still be effective. The electromigration of interstitial impurities is also an area which presents some intriguing questions. For the substitutional impurity, moving by the vacancy mechanism under the influence of an electric field, the correlation considerations are somewhat more complex than have been previously recognized. Another problem of basic importance in the calculution from first principles is the strength of the "electron friction" force, say for a simple one-band metal. A related problem growing out of the preceding is the prediction of the direction of the "electron wind" force for metals with band structure involving both holes and electrons. THE term electromigration has come to be used to describe the flow of matter in condensed phases carrying high electronic currents such as metals and alloys, whereas one usually reserves the term electrolysis for situations where the current is largely ionic, particularly in the liquid state such as molten salts. It follows that the mass transport number in electromigration is always very small, of the order of 10-7. Studies of electromigration date back some 30 years but the modern period would appear to date from the work of Seith and Wever1 who in the mid 1950's first incorporated markers to display mass motion relative to the lattice and first suggested that the direction of the mass flow was primarily determined by the sign of the charge carriers. Since that time interest in the field has grown steadily and more rapidly recently as certain technological applications became apparent. Chief of these is certainly the deleterious effects that electromigration can cause, even at relatively low temperature, to current-carrying elements in integrated circuitry.2 These phenomena have been the subject of intense study and considerable ingenuity. On the constructive side electromigration has proved a useful tool in the purification of certain metals.3 The interest of this paper is, however, centered more on the basic aspects of the subject than on its technological applications. That high electric currents should give rise to mass flow in metals and that the driving force should be more directly associated with momentum exchange with the charge carriers than with the electrostatic field are ideas that no longer cause surprise or particular interest. The field has matured to the point where the general concepts are widely accepted and continued progress in basic understanding rests on more detailed and quantitative exploration. It is the purpose of this paper to point out what are some of the current problems. As a result, we expect to raise more questions than we answer. The first of these will be the role of electrostatic forces, if any, in electromigration. A second section will deal with the electromigration of interstitials. A third and final section treats with electromigration of substitutional impurities or of the matrix atoms themselves. ELECTROSTATIC DRIVING FORCE In the conceptual treatments of electromigration it has been customary to write the driving force in terms of an effective charge number Z* and to divide it into two terms F = e£Z* = e£[Zel- z(pd/Nd)(N/p)(m*\m*\)] [1] The first of these represents the electrostatic force under immediate consideration in this section and the second and usually dominating term for metals arises from momentum exchange with charge carriers, commonly called the "electron drag" term. As can be seen it is set proportional to the electrons per atom, z, and the ratio of the specific resistivity of the moving entity to the corresponding resistivity per matrix atom. The (m*/Im*I) factor takes into account the fact that the sign of the charge carrier determines the sign of the driving force. The specific resistivity of the moving entity is averaged over its path. In the case of motion of the matrix atoms by vacancies this gives rise to approximately one-half the resistivity at the saddle point since the scattering power of the atom at its equilibrium position bordering the vacancy differs only slightly from that of a normal matrix atom. Although the formulation of the "electron drag" term in Eq. [I] is based on a highly simplified model for electron defect scattering, the essential features implicit in the expression are common to all the theoretical approaches that have so far appeared in the literature.4-6 As for Zel, most treatments of electromigration have included the quantity as the parameter which measures the direct interaction of the electrostatic field with the ion and equated it to the nominal valence of the latter. However, there has been considerable discussion whether this interaction may not be 0 in many cases.6 If the moving ion is always enveloped by the same distribution of shielding charge, then clearly its motion will not involve any work done by the electric field and one can expect there will be no electrostatic force exerted on such a neutral composite. From this point of view the shielding charge around the ion would be said to be complete and hence the entity within the Debye shielding sphere would be unaffected by the electrostatic field per se. There is, however, the prospect that, as the moving ion progresses, new charge comes in to participate in the shielding action

Jan 1, 1970

By R. V. Norris, E. W. Parker

Edward W. Parker,* Philadelphia, Pa.—At the New York meeting of the Institute a year ago, Mr. R. V. Norris presented a paper on anthracite mining costs, in which he gave the results of an intensive study of this subject by the Engineers' Committee of the United States Fuel Administration. Within the last 30 days, the Federal Trade Commission has issued an official report on the same subject, which covers a longer period of time and comprises statistics of realization values and margins that were pot comprehended in the paper by Mr. Norris. As, however, the data utilized by Mr. Norris formed also a part of the basis for the report of the Federal Trade Commission, a brief digest of the latter may not be out of place at this meeting. The report of the Federal Trade Commission covers primarily the two calendar years 1917 and 1918, divided into five periods which furnish opportunity for the study of how the influence of certain definite factors affected either the cost of production or the price, or both, during the 24 months. The first period, January to April, 1917, which may be considered the basic period, comprised the 4 months in 1917 during which the wage agreement of May, 1916, without modification, was in effect. During this period, the labor cost on fresh-mined coal is placed by the Commission's report at $1.79 per gross ton, the total cost at $2.66, the average realization at $3.29, and the "margin" (sales realization over total f.o.b. mine cost) at $0.63. The second period covers the four months from May 1 to August 31, during which time the first of the supplemental wage agreements (supplemental to the agreement of 1916) was in effect. It was also the period during which the summer discounts were in effect and when prices were practically fixed by a voluntary agreement between the operators and the Federal Trade Commission. It was, further, the period in which the 75 cents differential on prepared sizes permitted to the individual operators by the Federal Trade Commission began; at that time, also, on account of war conditions an unusually large quantity of steam sizes were marketed at exceptionally good prices. On account of the two latter conditions, not explained in the Commission's report, the "margin"1 on operating

Jan 1, 1920

By John W. Gabelman

Uranium exploration technology historically has followed the economic cycle of demand, exploration spurt, and trailing supply; but with a greater lag. Greatest progress was made during the wane of demand as geological investigation caught up with the flood of new discoveries made during relatively short periods of peak demand. Updating brought technology to a new level based on the deposits which were discovered and not on the total range of deposit types which might exist. The technology was seldom able to predict new deposit types or new districts, which have consistently been surprises. Yet each new cycle of increased demand was at a new higher level, occasioned by a new use, which required the discovery of previously unrecognized larger types of deposits. Hindsight shows that data sufficient to have predicted most discoveries were available. The predicted growth of uranium demand far in excess of estimated resources is an incentive to examine current technology for data or promising techniques that might foster discovery by technical prediction rather than by systematic drilling. The world could well be reexamined systematically with new geophysical techniques including gamma spectrometry, radon emanometry, and magnetometry. Known occurrences could well be reevaluated in the light of new data on mineralization process and supergene leaching. Less-leachable extrinsic elements associated with uranium might he sought as clues to unleached uranium at depth. Uranium is increasingly being noted in environments containing coal and petroleum which might become targets. High-temperature replacement disseminations are increasingly reported and particularly attractive as exemplified by the Rossing district. The number of formations containing uranium occurrences is growing so that new, not necessarily fluvial, formations might be productive. Enough drilling has been done to indicate that uranium is selectively distributed regionally under some control yet to be determined. Exploration should address those environments and areas where uranium could occur rather than only those where it is already known.

Jan 1, 1976

By Nicholas J. Grant, David S. Bloom

An investigation of the Cr-Ni system has revealed that there exists a eutectoid transformation at about 1180°C. 'The transformation in chromium implied by the eutectoid reaction was detected at about 100°C below its melting point. Associated with the eutectoid transformation, a metastable transition structure has been found. THE Cr-Ni phase diagram is shown in current literature to be a simple eutectic system in which the high chromium end of the diagram is incompletely determined, Fig. 1. The last investigation of this system was undertaken in 1936.' Because of limitations in metal purity, especially of chromium, and temperature measuring techniques, the diagram should be accepted with some reservations, as was indicated by Hansen.V or examwle.-, the wresence of the compound Cr²Ni, with a tetragonal structure," remains unverified and incompatible with the simple eutectic diagram. The work reported here began because of discrepancies that appeared in experimental studies in the binary alloys Cr-Ni and in the ternary system Cr-Mo-Ni. The existing binary Cr-Ni diagram failed to provide a complete explanation of observations made by microscope, X-ray, and thermal analyses. Experimental Methods The materials employed were of a higher degree of purity than were available to previous investigators. The Mond nickel used had a nominal purity of 99.87 pct, while the electrolytic chromium analyzed 99.03 pct with the major impurity being 0.5 to 0.7 pct oxygen with some iron. All alloys were melted in a vacuum furnace to remove dissolved gases, sufficient carbon was added to the charge to combine with all the oxygen as CO. Final analysis determined the carbon as about 0.02 pct and the oxygen around 0.06 pct or slightly more. Stabilized zirconia crucibles and thermocouple protection tips were used throughout and contributed no detectable impurity to the melts, as long as the oxygen in the chromium was kept low. Heats averaged about 250 g, which permitted about 2 in. of the thermocouple protection tips to be submerged. The temperature drop across the thermocouple protection tip was determined to be about 3°C, a minor source of error. The alloys, after removal from the vacuum furnace, were placed in a furnace operating in a purified argon atmosphere for the thermal analyses. An- nealed wolfram-molybdenum thermocouples provided the primary means of temperature determination, though a Pt-Pt-10 pct Rh couple was employed for a check when possible. A sensitive, high-speed Leeds and Northrup Speedomax recording potentiometer indicated the thermocouple output. X-ray diffraction patterns were obtained primarily on a Norelco unit, which permitted diffraction angles only up to 45" (28 = 90"). In general, either rotated or stationary solid samples were used, because it later evolved that many samples were susceptible to transformation resulting from the cold working involved in pulverizing. It was also noted that rotating a sample sometimes suppressed weak lines, so, usually, samples were not rotated. Later a high temperature camera was adapted for use at temperatures up to 1400 °C on the Norelco unit utilizing both solid and powdered samples. Unless otherwise noted, all X-ray patterns were made with a chromium tube and a vanadium filter. Further-

Jan 1, 1952

By J. W. Martin, L. K. Singhal

Grain boundary M23CB precipitates have been shown to form by a process involving the migration of an austenite grain boundary, and each plate of precipitate is in parallel orientation with one of the austenite grains constituting the boundary. The carbide distribution and morphology appear to be sensitive to grain boundary mis orientation. Some areas of austenite grain bowzdary permit the development of an array of M,C, particles, some of which are in parallel orientation with one grain and some with the other grain constituting the boundary. Massive carbide at grain boundary triple points is also shown to be in parallel orientation with one constituent grain. PREFERENTIAL precipitation during aging of carbides of the type (Fe,Cr)23C6, usually written MZ3C6, in grain boundaries of quenched austenitic stainless steels has been widely recognized. M23C6 has a complex cubic crystal structure' which contains ninety-two metal atoms and twenty-four carbon atoms per unit cell. Less energy is involved in forming grain boundary precipitates than in the formation of intragranular precipitates, and the process is further enhanced by the accelerated diffusion rates in the boundaries and by the probability of segregation of chromium atoms and carbon atoms to the region of the grain boundaries during prior solution heat treatment in order to reduce lattice strain. Early electron micrographic studies2, 3 involving either extraction replica or normal replica techniques established the geometric or dendritic form of the carbide particles, although this approach led to dis- pute as to whether the particles grew within the plane of the boundary or grew into the matrix.4-6 More recent thin-foil studies' have claimed to identify a discontinuous precipitation process involving M23C6 at grain boundaries, and the object of the present work was to attempt to clarify the situation using modern electron micrographic and diffraction techniques. 1) EXPERIMENTAL 1.1) Material. The steel selected for this work had a base composition of 24 pct Ni-25 pct Cr-3 pct Ti and contained about 0.04 pct C. The full analysis if given in Table I. This alloy was in the form of strip which had been hot- and cold-rolled to a thickness of 0.6 mm. 1.2) Heat Treatment. Specimens 4 cm long by 1 cm wide were solution-heat-treated for 3 hr in argon at 1150°C, followed by water-quenching. Specimens were subsequently aged in vacuo at 750°C for periods up to 500 hr. 1.3) Preparation of Electron Microscope Specimens. The heat-treated strips were cut bv spark machining into discs of 3 mm diam and 0.6 mm thickness. he-discs were dished on both sides using an electrolytic jet of 15 pct HCl electrolyte at 80 v. Final electro-polishing of the discs was carried out using 10 pct perchloric acid, 20 pct glycerol, and 70 pct ethanol at 10 v. The current density was kept below 300 ma. cm"2 by cooling the electrolyte to 0" to 5°C. As soon as a small hole appeared, the electropolishing was stopped and the specimen was quickly washed with ethanol.

Jan 1, 1969

By Donald Jaffe, Michael B. Bever

The solidification of Al-Zn alloys (2 to 70 pct Zn was investigated at different rates of solidification. The resulting structures were studied; the amounts of nonequilibrium eutectic were measured and compared with the amounts calculated on the assumption of no diffusion in the solid. The compositions of the cored primary constituent were investigated by quantitative autoradiography after activation of the zinc by neutron irradiation. These compositions were also determined from microhardness values. IN a recent investigation of the soltdification of aluminum-rich AI-Cu alloys,' the amounts of non-equilibrium eutectic were measured and compared with the amounts calculated on the assumption of no diffusion in the solid. The compositions of the cored primary constituent were investigated by quantitative autoradiography. The work reported here extends the investigation of nonequilibrium solidification to the Al-Zn system in the range from 2 to 70 pct Zn. In addition to autoradiography, microhard-ness values were used to determine compositions on a micro scale. Solidification Experiments The alloys contained approximately 2. 6, 12, 20, 30, 50, and 70 wt pct Zn and the balance aluminum. According to published diagrams the eutectic reaction occurs at 382°C between the eutectic liquid (95 pct Zn), a (82.8 pet Zn), and $ 498.9 pct Zn). Solid-state reactions at lower temperatures (due to the miscibility gap between 350" and 275"C, the eutectoid at 275'C, and the precipitation from supcrsaturated a) did not affect this investigation. Even if they occurred to any appreciable extent, they did not alter the evidence pertaining to the solidification structures. The alloys had to be of high purity to avoid radioact~ve contamination during activation. The aluminum analyzed 0.015 pct Si, 0.009 pct Fe, less than 0.004 pct Cu, and less than 0.006 pct Mg with traces of sodium and titanium; the zinc was reported to be at least 99.99 pct pure with traces of iron and magnesium. The alloys were prepared under argon in an induction-heated, bottom-pouring furnace, and poured into a coated steel mold, which could be preheated to temperatures up to 700°C in order to control the rate of solidification. The pouring temperatures ranged from about 40" above the liquidus for 2 pct Zn alloys to about 130°C above the liquidus for 70 pct Zn alloys. As soon as the melt entered the mold, the readings of a thermocouple placed % in. above the bottom of the mold were recorded by a recording potentiometer. Cooling at the rate induced by the initial temperature of the mold was continued to a temperature 100°C below the liquidus; the mold with its contents was then quenched in icy brine. Quenching from a fixed interval below the liquidus was used to provide a standardized procedure, since the solidus and liquidus temperatures and the interval between them vary greatly over the composition range investigated. The temperatures from which the samples were quenched were below the equilibrium solidus, but under nonequilibrium conditions some liquid was still present. This residual liquid solidified during the quench. The samples measured 314 in. diam and 11, in. height. Drillings for chemical analysis were taken

Jan 1, 1957

By Henry M. Stanley

The methods about to be described have been tested in practice, and are believed to be specially adapted to such extended topographical surveys as mining engineers in particular are sometimes called upon to execute. The assistance of Mr. H. 0. Flipper in the preparation of this paper, and his practical authorship of the second part, is hereby acknowledged. I. Photographic SuRveying. The writer was recently employed; together with Mr. H. O. Flipper, to survey the properties of the Plata-Reina de Sonora Mining and Milling Company, situated in the mining district of Las Planchas, District of Magdalena, State of Sonora, Mexico. These properties, now owned by an American corporation, of which M. W. Evans, of New Orleans, is president, and Richard A. Pomeroy is resident superintendent, are famous in the history of Mexican mining, as the place where planchus, or bolas de plata were foulld about the beginning of the last century. Ward, the English CILargh d7Affaires in Mexico from 1826 to 1828, writing at that epoch, says: "The idea [that the ores in the north of Mexico were richer than those in the south] probably originated in the discovery of the famous bolas de plata [balls of silver] of Arizona [Planchas de Plata de Arizona, a stock-ranch in northern Mexico], in the beginning of the last century, which was, and probably still is, believed in Europe to be one of those fables with which mining countries always abonnd. But the attention of the present government of Mexico having been drawn to the subject, a search was made in the viceregal archives, by order of the president, for the correspondence which was known to have taken place respecting it in the year 1736. This correspondence I have seen, and I have in my possession a certified copy of a decree of Philip the Fifth, dated Aranjuez, 28th May, 1741, the ohject of which was to terminate a prosecution, instituted by the Royal Fiscal, against the discoverers of Arizona, for having defrauded the treasnry of the duties payable upon the masses of pore silver found there. The decree states the weight of the balls, sheets and other pieces of silver discovered (bolas, planchas, y otras piezas de plata), to have amounted to 165 arroba, 8 pounds, in all, 4133 pounds; and mentions particularly one mass of pure silver, which weighed 108 arrobas (2700

Jan 1, 1892

By P. W. George, G. A. Hellstrand

In 1915, H. A. Guess, Vice President of American Smelting & Refining Co., in charge of its Mining Department, learned that the Anglo-Newfoundland Development Co., Ltd., a pulpwood and paper-mill enterprise, had found upon its large concession in Newfoundland, and had opened up by shaft to the third level and some drifting, a lenticular orebody indicating about 100,000 tons, as an extremely fine-grained sulfide ore, averaging about 0.05 oz. Au, 4 oz. Ag, 1.5 per cent Cu, 10 per cent Pb, 18 per cent Zn; and that having sent parcels of this ore to Minerals Separation, Ltd., and various other metallurgical testing concerns without obtaining any success in commercial separations thereof, had discontinued work thereon and let the workings fill. Mr. Guess wrote to the general manager of that company and obtained a few hundred pounds of the typical ore, which he sent to his company's metallurgical testing laboratory at Flat River, Mo., outlining various flotation tests desired thereon, in an endeavor to obtain separation into a commercial lead concentrate and a zinc concentrate. But the art of flotation had not then progressed far enough to treat such ore, the galena and zinc blende being so fine grained that grinding to about 300 mesh was required to release the mineral particles in their gangue. Mr. Guess had flotation and other tests continued upon this ore from time to time with whatever new reagents and flotation devices were evolved as time went on, and finally, in 1925, he succeeded in effecting in his company's testing plant, then at Wallace, Idaho, separations into lead concentrates and zinc concentrates of satisfactory commercial grade. Mr. Guess then proceeded to unwater, examine and sample the property and made with the owners a partnership operating agreement upon the mine itself and a considerable area surrounding it, and in the early summer of 1926 began to prospect for additional orebodies, utilizing for such prospecting geophysical methods under the direction of Hans Lundberg, methods which up to that time had been little used in mining in the western hemisphere. This geophysical work found two large flat-lying orebodies of a type precisely similar to the smaller body of the original discovery. The larger orebody, some 3500 ft. west of the original

Jan 1, 1935

By M. R. Moharam

The well-known formulae of screening efficiency and circulating load calculations in closed crushing circuits were exploited to achieve graphical estimation of these parameters. Three basic charts were proposed and constructed. The first one is for the regular closed circuits where the new feed goes to the crusher. The second is for the reverse closed circuits in which the new feed reported to the screen is free of screen undersize particles. The third chart controls the reverse circuits when they are receiving new incoming feeds containing undersize material. Compound circuits were also reanalyzed and a concept of equivalent simple circuit was introduced to enable graphical manipulation of these complex circuits with the help of the aforementioned charts

Jan 1, 1982

By P. Duwez, L. Zwell

In recent years, the problem of pressing metal powder in a die has received much attention. The question has been the object of a Symposium held in New York in March 1947 under the sponsorship of the AIME; an excellent review of the subject may be found in Ref. 1. Various experimental techniques have been used to study the behavior of the powder in a die cavity. Two methods have been particularly successful; one consists of measuring the density distribution²,³ and the other makes use of a lead grid in the powder during pressing.4 In the present study, the pressure at various points on the bottom and the sides of a die 1.50 in. in diam was measured by means of small piston dynamometers and resistance sensitive strain gauges. In order to correlate the results with previous investigations, the pressure distribution inside the compact has also been determined by an indirect method based on density measurements. Strain Gauge Measurements of Pressure on Side and Bottom of Die A schematic drawing of the die used for measuring side pressures is shown in Fig 1. The pressure gauge consists of a 0.25-in. diam piston A which transmits the pressure to a dynamometer B, on which two Baldwin Southwark type 4-14 strain gauges are fastened 180" apart. Because the installation of several dynamometer assemblies along the side of the die would have been difficult, the pressure distribution was obtained in successive tests in which the distance from the gauge to the bottom of the compact was adjusted to different values by changing the length of the bottom piston. The dynamometer, disassembled from the die, was calibrated under compressive loads and showed a 1.00 ohm change of resistance for every 15,300 psi change of pressure (750 lb load change). All the strain gauge measurements were made with a null type Leeds and Northrup Wheatstone bridge. The sensitivity of the method was better than 1 pct and the accuracy was within 2 pct. These values were considered satisfactory in view of the rather large scatter in the measurements introduced by the random variation in packing the powder in the die. The stable ambient conditions and short time involved in the taking of observations made temperature compensation unnecessary-. The pressure distribution on the bot-

Jan 1, 1950