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INTRODUCTION IT is 10. years this summer since the first of the contributions which it has been my privilege to make to the working tools of the hydrometallurgist was set at work, but a full description of what has come to be known as "Dorr Machinery" has never been published in the Transactions of the Institute, and it has been suggested to me that an account of the same would prove of interest to members, although most of those engaged in cyaniding and concentration are probably familiar with it. The account which I shall give of the development of the machines must be recognized as being written from the viewpoint mainly of my own local experience and not from that of one who was familiar with the general metallurgical practice throughout the world. Most advances in any art are conceived before the time is ripe for their development and any .invention which comes into general use will usually be found to have been tried out in a crude way and abandoned more than once. If the early experimenter went as far as the Patent Office, his work may serve no other purpose than to prevent the issuance of the broadest patent to those who later may develop a commercial process. The cyanide process in the United States early in 1904 was mainly confined to the leaching of dry crushed ores, both coarse and fine, and sand treatment of tailings from concentration and amalgamation. In the Black' hills some plants were crushing in cyanide solution, leaching sands and handling the slime by the well-known decantation process. Filter pressing, in use for some years in Australia,had been tried in several places in this country and the Moors process had been abandoned at Mercur after' a short run, but was doing good work at the mill of Lindbergh, Dorr & Wilson, at Terry, and being installed at Bodie and the Liberty Bell. A general feeling, however, still existed that, slimes were to be avoided when possible, on account of the losses in treatment and the difficulty of making a good leaching product when they were present in large amounts, especially when the crushing was done in cyanide solution.

Jan 8, 1914

By W. E. Gaby

INTRODUCTION SINCE the time of their discovery, the genesis of the ores at Mount Morgan, and the nature of the changes which have affected the surrounding rocks, have been the subject of investigation and speculation by geologists and mining engineers. Developments at this mine, for a long period the greatest gold producer of the world, show that with depth the orebody grades into copper, of which metal it now furnishes a large output, exceeding in value the gold. In earlier times, the purity of the gold and the first extremely heterogeneous character of the ore made it an interesting problem. Now, the probable depth of the copper enrichment, genesis, and true relations of the neighboring rocks furnish equally profitable material for investigation, and the present somewhat detailed description of these ores and rocks, from microscopic study, may prove of interest. The mine occupies a highly silicified portion of a belt of quartz-porphyry, which is believed to be the oldest rock of the region. This belt of quartz-porphyry and allied rocks runs north and south between two areas of a later intrusive granite, as shown on the geologic map,1 Fig. 1. Near the orebody the quartz-porphyry has been intruded by a dense basaltic mass called the "Old Basic." Cutting all three of these igneous masses are two sets of basaltic dikes, one running northwest-southeast, and the other, cross dikes, northeast-southwest. These dikes may be contemporaneous with, instead of later than, the ore. Their number has caused peculiar difficulties in extracting it, as the clay selvage of decomposed material affords no adhesion between dike and ore, causing great blocks to loosen and come down.

Jan 9, 1916

By J. L. Rodda, R. L. Wilcox, E. C. Truesdale

In recent years various problems in connection with research work on the preparation and properties of zinc-base alloys have required reliable information concerning the constitution of the zinc-rich portion of the iron-zinc equilibrium diagram. On numerous occasions rather positive indications were obtained that, for example, the solubility of iron in zinc was incorrectly represented on the current equilibrium diagrams. A careful study of all the available literature relating to the iron-zinc system led to the conclusion that much of the early work was unsatisfactory as measured by present standards of experimental accuracy, and as a result it was decided to redetermine the location of the liquidus curve and of adjacent portions of the diagram. Part I of this paper comprises a description of the experimental methods and a summary of the results by means of which the zinc-rich end of- the iron-zinc diagram has been revised in the following ways: 1. Measurements of the solubility of iron in liquid zinc by several different sampling methods, leading to a relocation of the liquidus curve. 2. Microscopic, conductivity, and X-ray studies of the solid solubility of iron in zinc, which, together with thermal analyses, have resulted in new values for the solid solubility and the eutectic temperature and composition. 3. Heating and cooling curves, obtained by a refined differential method, leading to new locations for the two peritectic horizontals. In Part I1 of the paper the attempt is made to review all of the published work having a bearing on the constitution of the iron-zinc system, and to correlate the present results, and some recently published data involving the use of X-ray technique, with the earlier work, much of which was done from 25 to 30 years ago.

Jan 1, 1936

Jan 1, 1929

By George Frederick Kunz

The manifold inconveniences resulting from the absence of a uniform standard of mass for determining the weight of precious stones have long been obvious. This lack has been keenly felt in commercial transactions, and those who have devoted time and research to the study of historic diamonds and precious stones have had frequent occasion to deplore the absence of such a standard in the past. In a paper read in Chicago in 1893, before the International Congress of Weights and Measures, held in connection with the World's Columbian Exposition, the writer suggested dividing the carat into 100 parts, and constituting a standard international carat of 200 mg.; that is, 5 diamond carats or 20 pearl grains to a French gram, making 5,000 carats or 20,000 pearl grains to a ki1ogram. He also called attention to the fact that while this would depreciate the present diamoiid carat or pearl grain only about 2.5 per cent., it would abolish the troublesome discrepancies between the various carat-weights now in use, and could be easily explained and understood everywhere.' The subject of the various diamond carats, their incongruity, and the resulting confusion as to the correct weights of historic gems when definite records of them are searched for, has been fully treated by me in an extensive study of this subject in The Book of the Pearl2 To the earnest and unremitting efforts of C. E. Guillaume, Director of the Bureau Internationale des Poids et Mesures at Sévres, is largely due the eventual success of this eminently desirable reform, which he has constantly urged both by articles on the subject and by addresses delivered in Paris before the International Committee for Weights and Measures.3 The general adoption of a uniform standard for dealings in pre-

Jan 1, 1914

By Nathan C. Rockwood

LIME is a very general term applied to products of limestone, in popular treatises often incorrectly, including ground or pulverized limestone used in agriculture. When used without qualifying adjective, the term usually means burned or calcined limestone, or quicklime, or calcia. The corresponding calcined product of magnesite is magnesia. If the calcined rock is relatively pure calcium carbonate, the resulting lime is a "high-calcium" lime; if the rock is dolomite, or a combination of calcium and magnesium carbonates, the lime is a "dolomitic" or a "high- magnesium" lime. There are various grades in between, depending on the percentage of magnesium carbonate and other ingredients in the raw rock. For some industrial purposes only high-calcium limes are suitable; in other processing-as, for example, neutralizing acid wastes -the relative percentages of magnesium and calcium carbonates in the raw material are not important. Limestone is burned (roasted or calcined) in furnaces known as lime kilns by direct exposure to the hot gases and flames. When heated to incandescence, the carbon dioxide content of the rock is expelled, leaving calcium and magnesium oxides, according to the formula usually written: [ ] This thermal reaction is reversible, which requires that the lime be withdrawn from the "calcining zone" of the kiln about as fast as made. Pure calcium carbonate would lose 44 pct of its weight in the calcining process; dolomite, 48 pct. Generally, the lime will retain the approximate size and shape of the piece of rock from which it is made but some few limestones tend to break down into granules or dust. Hence lime (quicklime) comes from the kilns in lumps or granules and normally is packed in water- tight containers in these forms, or is pulverized after calcination.

Jan 1, 1949

Jan 1, 1902

By E. A. Gulbransen, J. W. Hickman

ONE of the important factors that determine the resistance of a metal or alloy to further chemical reaction is the structure of the superficial oxide film A thorough understanding of the physical and chemical structure as well as the stability of the oxide film formed on the surface as a function of time and temperature of the chemical reaction might furnish clues as to the nature of the reaction process and the protective nature of the film A comprehensive program has been undertaken to study these phenomena This paper summarizes the structure of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper at temperatures up to 700°C Before the introduction of the electron diffraction technique, it «as necessary to use either direct chemical analyses or X-ray diffraction analyses to determine the nature of the oxide film formed on the metal or alloy Chemical analyses yields information on the percentages of the several atomic species present in the film while X-ray diffraction analyses yield information on the atomic geometry In special cases the information obtained may be identical, but in general both view-points are necessary Much of, the early work was carried out on the oxidation of bulk samples where thick films were obtained The products were identified after cooling to room temperature by X-ray diffraction and chemical analyses Although much useful information has been obtained in this manner, little could be learned about the character of the protective oxides during the period when the films were actually protective Evidence concerning the chemical structure of thin oxide films has been made possible by the development of the electron diffraction reflection technique In this method the most fruitful investigations have been made by carrying out the reaction in situ at the temperature at which the film is actually protective LITERATURE The oxidation of iron has been extensively investigated by X-ray and electron diffraction Jackson and Quarrell1 found that oxide films formed and examined at the same temperature differed considerably from those allowed to cool to room temperature The results showed that below 400°C the oxide that was stable in intimate contact with iron was Fe304, between 515° and 900°C the stable film was FeO Above the upper change point of iron the oxide was found to be Fe304 prom 400° to 515°C , FeO, Fe304 or a mixture of the two oxides was found Recrystallization of the air-formed film below 400° and above 900°C led to the formation of Fe304 In the range where thicker films consisted of FeO, the air-formed film was converted to a new hexagonal oxide not previously described

Jan 1, 1946

Sec. 1. The membership of the Institute shall comprise six classes, namely: 1. Members; 2. Honorary Members; 3. Senior Members; 4. Associates; 5. Junior Members; 6. Rocky Mountain Members. All shall be equally entitled to the privileges of membership, excepting that no member of any class whom residence shall be outside of the United States of America, except those residing in Mexico and Canada, shall be entitled to vote. SEC. 2. Members: A person to be eligible for election or transfer into the claw of Member must be at least 27 years of age and must have had at least six years' employment in the practice of engineering, mining, geology, metallurgy, or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. This shall not apply to Rocky Mountain members.

Jan 1, 1944

By D. L. Ritter, N. J. Grant, B. C. Giessen

Forty-six alloys covering the complete concentration range of the Nb-Rh system were examined by metallographic and X-ray methods; solubility limits of terminal ad intermediate phases and transformation and solidus temperatures were determined. There are nine intermediate phases; two eutectic, five peritectic, two eutectoid, and three peritectnid reactions were encountered. The experimental methods and the constitution diagram are described in Part I. Part 11 deals with the crys -tallography and relation of the intermediate phases. The Nb-Rh system was selected for study for three reasons: first, it was hoped that the anticipated similarity of the Nb-Rh phase diagram to the Ta-Rh1 and Ta-Ir2 diagrams treated earlier (see also Ref. 3) and to the Nb-1r4 diagram treated simultaneously would allow a crystallographic and comparative evaluation of the intermediate phases in these related systems; second, it was likely that the previous experimental methods could be carried over without significant change; and third, it was expected that the interesting mechanical properties of the a1 phase of the Ta-Rh and Ta-Ir systems would also be encountered in similar phases of the new systems, and that these phases could be investigated more closely. The phase diagram had not been treated fully in the literature; only brief surveys of some intermediate phases were found.5-7 It was attempted to cover the details of the phase boundaries, Part I, as well as to present the crystallography of the intermediate phases, Part 11. EXPERIMENTAL METHODS Specimen Preparation and Treatment. The following high-purity starting materials were used. 1) Niobium powder, 99.8 pct pure, mesh size -60 +200, from Wah Chang Corp., Albany, Ore. The analysis furnished by the supplier showed the following major impurities: Ta, <500 ppm; Zr, <500 ppm; 0, 300 ppm; Fe, 280 ppm; Ti, <I50 ppm; W, Si, <100 ppm; C, N, 30 ppm; all other impurities, <30 ppm. 2) Rhodium powder, ground sponge, 99.9+ pct pure, mesh size -80, from J. Bishop Co., Malvern,

Jan 1, 1964

By P. B. Bucky

IN previous publications1 it was shown that a scalar model of any weighty structure, where the stresses produced are mainly due to gravita-tional forces, will behave similarly to its prototype if the model and proto-type material are the same arid the model is placed in a centrifugal field of force (substituted for the gravitational field) which has been increased in the same proportion as the linear model scale is decreased. This principle is now being applied to a study of the behavior of mine structures in an attempt to determine the laws that control them. The importance of using models as a means of solving mining problems has been discussed previously, yet it may be well to reiterate here that this method of research and type of solution have been productive of far-reaching results in other engineering fields, notably those of hydraulics and aerodynamics. Model research is a comparatively cheap and time-saving method of checking practical experience. Up to the present time the best guide to what will happen underground has been the judgment of the man who has observed most and been longest acquainted with the local conditions. His experimental work underground is limited by the elements of cost, time and danger, while failure is seldom permissible. In a model, as in a test tube, all elements that affect the solution of a problem are under definite control. Each element may be varied independently at will and its effects noted. Experimental work on a small-scale model may there¬fore be performed at a comparatively small expenditure of time and money, instead of on a full scale in the mine, where the cost, time, and danger elements are necessarily great. The experiments described in this paper are to be considered as part of a progress report and a continuation of Technical Paper 425. One object of the research program is to make each experiment point the way for further research on that particular phase of the general problem. The results and conclusions presented here are therefore not to be considered as final, but are to be interpreted as

Jan 1, 1933

By Walter S. McKee

When mixed with common cast steel in quantities ranging from 11 to 131/2 per cent. and properly treated, manganese increases the ductility of the metal and adds greatly to its toughness and resistance to abrasive action, which properties comprise the distinctive characteristics that make manganese steel so valuable for many purposes at the present time.. * At present the manganese-steel foundries of this country have an annual capacity of about 60,000 tons and most of the growth has occurred within the past 10 years. In the early days of the industry it was impracticable to make manganese castings weighing over a few thousand pounds, but at present crusher heads, rolling-mill pinions, and similar castings weighing up to 30,000 Ib. each are produced, and it does not appear that the limit of weight has been reached by a considerable margin. Manganese steel is similar in analysis to ordinary first-class converter metal except that it is high in carbon and contains from 11 to 13.5 per cent. of manganese. From one standpoint manganese steel is similar to malleable iron in that the casting as it comes out of the sand is hard and brittle and must be made ductile by a heat-treating process. The heat treatment is an essential part of the process of making manganese-steel castings and must be properly carried out to secure satisfactory results. The necessity for heat treatment limits the thickness of sections which may be made of manganese steel. Originally the annealing depth was comparatively small, but researches carried on during the past few years have resulted in an increase in the thickness of section up to 51/2 in., which it is possible to treat successfully. Large castings are cored out to a minimum thickness of 51/2 in., thus not only eliminating some of the internal stresses which are invariably set up in a very thick casting, but also reducing the weight and inertia of the piece, an important consideration if the casting is to be a moving part in a machine. At the same time, the thickness of 51/2 in. is sufficient to permit the use of manganese steel for the heaviest classes of machinery.

Jan 1, 1916

By R. F. Mehl

Jan 1, 1936

By R. H. Hawkins

AN investigation of the applicability of geophysical methods to north-ern Ontario lignite deposits was undertaken early in 1930 by the Ontario Research Foundation at the request of the Ontario Department of Mines TABLE 1.-Formations Associated with Moose River Basin Maximum System Formation Lithology Observed Correlation Thickness, Ft. Pleistocene Marine clays 150 Glacial till (Minimum Interglacial 30) clay and peat Glacial till Lower Cretaceous or Mattagami Fireclay, sand 138 Kootenay (?) Upper Jurassic. and lignite Devonian (Upper) Long Rapids Petroliferous, 50 Portage and black and gray Genesee shale Williams Limestone and 87 Tully (?) Island calcareous shale Devonian (Middle).... Abitibi River Gray fossiliferous 65 Onondaga limestone Devonian (Lower) ?... Moose Rive- Limestone and 50 gypsum Devonian (Loner) Sextant Arkose, clay, etc. 50 Pre-Cambrian Syenite, granite gneiss, etc. Igneous intrusives. . Lamprophyre dikes cut the Abitibi River and lower formations. (Permission of Ontario Dept. of Mines) and was financed in part from a research grant made by the latter organ-ization. The work to date has included gravitational, magnetic and electrical resistivity studies. The gravitational and magnetic measure-

Jan 1, 1933

By F. R. Hensel

PURE silver and silver-lead alloys have been studied as to their suitability for bearings.1-8 A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materials.† The silver-rich end of the diagram as reported in the literature9-11 was found to be sketchy and it was necessary to carry out considerable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. TEST MATERIALS In the beginning of the work, only fused alloys were investigated. Later, research [TABLE I. Composition of Fused Silver thallium Alloys Tested for Antifriction Properties PERCENTAGE ALLOY No.OF THALLIUM 15330.48 153406 231 HT2.04 2312.10 232 HT3.83Balance 2324.07Silver 233 HT5.86 2336.38 2349.84 234 HT10.07] was carried out on electroplating methods and diffusion processes. In preparing the fused alloys, care was taken to exhaust the toxic fumes caused by the thallium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in. diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr2O7, 8 c.c. H2SO4, and 100 c.c. H2O. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C. show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475°C. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not result in complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1945

[Holds monthly meetings, except June, July and August, J JOHN A. CHURCH, JR., Chairman JOSEPH E. POGUE, Vice-chairman SIDNEY ROLLE, Vice-chairman EDWARD C, MEAGHER, Secretary, Texas Gulf Sulphur Co,, 41 E, 42nd St., New York M, H, MERRISS, Treasurer, 42 Broadway, New York ARTHUR NOTMAN T. T, READ Boston Meets first Monday of each winter month. EDWARD C. GEITHER, Chairman WILLIAM S. BLACK, Vice- chairman DONALD H, MCLAUGHLIN, Secretary, treasurer, Rotch Bldg,, Harvard Univ,, Cambridge, Mass. J, L. GILLISON A. G, WAITE]

Jan 1, 1928

By Magnus Troilius

INTRODUCTION BY C. P. SANDBERG. SINCE the discussion On steel rails in America has forcibly drawn attention to the value of chemical analysis, if not as a necessary stipulation, at least as a guide to control the usual mechanical tests, some doubt has been thrown upon the accuracy of the analytical results Obtained by different chemists. To any One having the least acquaintance with chemistry., it is quite clear that if exactly similar results are to be obtained from the same borings of steel, exactly the same methods must be used by the different analysts. Hence the necessity (if complications are to be avoided) of establishing what I may call standard or normal methods, to be used both by the inspectors and by the chemists at the works. Remembering that the application&apos; of chemistry to steel-rail inspection is yet in its infancy, it is of great importance to possess a perfect acquaintance with the best methods in use. Being myself a grateful pupil of Professor Eggertz, of the School of Mines in Sweden, it Occurred to me, two. years ago, that I could not do better than start a laboratory of my. own, and engage One of his pupils, Mr. Troilius, for the purpose of analyzing the steel borings from mechanically-tested rails, so that I might thus Obtain without delay thoroughly accurate determinations. Moreover, in Order to carry on the, operations in perfect accordance with the methods used at the steel works in England and Germany, where I had to control the manufacture, I deemed it desirable to allow Mr. Troilius to go through a course of training at these works; and I gladly seize this opportunity of expressing my grateful acknowledgments to several works in England and in Germany for affording every facility for such an exchange of information as was found necessary in arriving at the best analytical methods to be used.

Jan 1, 1882

By Magnus Troilius

SINCE the discussion on steel rails in America has forcibly drawn attention to the value of chemical analysis, if not as a necessary stipulation, at least as a guide to control the usual mechanical tests, some doubt has been thrown upon the accuracy of the analytical results obtained by different chemists. To any one having the least acquaintance with chemistry, it is quite clear that if exactly similar results are to be obtained from the same borings of steel, exactly the same methods must be used by the different analysts. Hence the necessity (if complications are to be avoided) of establishing what I may call standard or normal methods, to be used both by the inspectors and by the chemists at the works. Remembering that the application of chemistry to steelrail inspection is yet in its infancy, it is of great importance to possess a perfect acquaintance with the best methods in use. Being myself a grateful pupil of Professor Eggertz, of the School of Mines in Sweden, it occurred to me, two years ago, that I could not do better than start a laboratory of my own, and engage one of his pupils, Mr. Troilius, for the purpose of analyzing the steel borings from mechanically-tested rails, so that I might thus obtain without delay thoroughly accurate determinations. Moreover, in order to carry on the operations in perfect accordance with the methods used at the steel works in England and Germany, where I had to control the manufacture, I deemed it desirable to allow Mr. Troilius to go through a course of training at these works; and I gladly seize this opportunity of expressing my grateful acknowledgments to several works in England and in Germany for affording every facility for such an exchange of information as mas found necessary in arriving at the best analytical methods to be used.

Jan 1, 1882

New York Holds monthly meetings, except June, July and August JOHN A CHURCH, JR, Chairman JOSEPH E POGUE, Vice-chairman SIDNEY ROLLF, Vice-chairman EDWARD C MEAGHER Secretary, Texas Gulf Sulphur Co, 41 E 42nd St, New York M H MERRISS, Treasurer, 42 Broadway, New York ARTHUR NOTMAN T T READ Boston Meets first Monday of each winter month EDWARD C GEITHER, Chairman WILLIAMS BLACK, Vice-chairman DONALD H MCLAUGHLIN, Secretary-treasurer, Rotch Bldg, Harvard Univ, Cambridge, Mass J L GILLSON A G WAITD

Jan 1, 1923

Iron and Steel ALBERT SAUVEUR, Chairman. A. A. STEVENSON. Vice-Chairman. HERBERT M. BOYLSTON, Secretary, Abbot Bldg., Harvard Sq., Cambridge, Mass. GUILLIAEM AERTSEN, HENRY M. HOWE, E. GYBBON SPILSBURY, JOHN BIRKINBINE. ROBERT W. HUNT, J. 8. UNGER, WILLIAM H. BLAUVELT, J. E. JOHNSON, JR.. FELIX A. VOGEL, CHARLES A. BUCK, CHARLES KIRCHHOFF, LEONARD WALDO, ERNEST F. BURCHARD, RICHARD MOLDENKE. WILLIAM R. WALKER, FRANK D. CARNEY, CHARLES F. RAND, WILLIAM R. WEBSTER JAMES GAYLEY, JOSEPH W. RICHARD$, FREDERICK W. WOOD. HENRY D. HIBBARD, C. F. W. RYS,

Jan 1, 1917