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By Clarence E. Sims

An effort has been made to give both a comprehensive and simplified picture of the origin, modes of formation, and characteristics of nonmetallic inclusions in steel. Exogenous inclusions, those formed by mechanical entrainment or heterogeneous reaction, have their principal source in ladle refractories. Mechanical emulsion is not considered a likely mechanism. Endogenous inclusions, resulting from homogeneous reactions, are formed mainly during cooling and freezing. They are principally oxides and sulfides but include some nitrides and carbides. Deoxidation affects both the quantity and character of such oxide inclusions and significantly affects the size and shape of sulfides. The importance of inclusions is largely in their effect on mechanical properties. It is fitting and proper that we should honor the memory of those technical giants who have left such a rich heritage to our profession. Today, according to annual custom, we pay tribute to such a man. To have been chosen to play a part in this observance prompts in me an inordinate pride while I am humble before the responsibilities of my task. The ranks are growing thin of those who had the good fortune to come under the personal influence of Professor Howe, but the number who continue to benefit from his legacy of technical wisdom con-stantly increases. I am among the latter. One has only to read his works to appreciate his unusual ability to take data and observations from many sources and give them a clear and comprehensive

Jan 1, 1960

By Otto H. Henry, J. J. Cordiano

Though powder metallurgy is one of the oldest of metallurgical processes, it is in its infancy as a branch of the modern field of metallurgy. As early as 3000 B.C., the ancients produced implements and weapons of iron by reducing iron ore in a charcoal fire and forging the resultant sponge while still hot into the desired shape. Melting and casting soon superseded the powder metallurgy practice, and it was not until the turn of the twentieth century that powder metallurgy was applied to the commercial manufacture of tungsten lamp filaments. From this beginning, the use of the powder metallurgy process spread" to the manufacture of porous oil-impregnated bearings, cemented carbide tools, contact points, diamond grinding wheels, clutch facings, starter brushes, resin-bonded radio cores, magnets, metallic filters, and other parts. More recently, and particularly during the present war, there has been a definite trend toward the manufacture of machine parts by this process in competition with the more conventional fabricating methods. Notwithstanding these many developments, scientific progress has been slow. While many articles on powder metallurgy have appeared in the press and various publications, there have been too few contributions to our technical societies, with the result that there is a dearth of the type of information necessary for the full development of this science. It is of primary importance that the results of research and development be freely disseminated if powder metallurgy is to realize its fullest potentialities. Purpose of Investigation Excluding the refractory metal field, all commercial powder metallurgical products made by a cold compressing and sintering operation contain voids. These voids can be substantially eliminated by subsequent severe working and heat-treatment, but ' such practice has not proved economical in most applications. By applying heat during the compressing operation, plastic deformation of the powder particles is substantially increased, and the resultant compact or briquette is practically free of voids. However, hot-pressing has many attendant problems, which at present preclude its use in the manufacture of precision parts. The more important of these are to devise: 1. A die steel capable of withstanding high pressures at elevated temperatures. 2. A high-temperature lubricant capable of preventing excessive die wear and welding of the compact to the die walls. 3. A method of retaining a neutral or reducing atmosphere in the compacting zone of the die assembly. 4. A means of ejecting the hot-pressed specimen into a neutral atmosphere until reasonably cold.

Jan 1, 1946

By Otto H. Henry, J. J. Cordiano

Though powder metallurgy is one of the oldest of metallurgical processes, it is in its infancy as a branch of the modern field of metallurgy. As early as 3000 B.C., the ancients produced implements and weapons of iron by reducing iron ore in a charcoal fire and forging the resultant sponge while still hot into the desired shape. Melting and casting soon superseded the powder metallurgy practice, and it was not until the turn of the twentieth century that powder metallurgy was applied to the commercial manufacture of tungsten lamp filaments. From this beginning, the use of the powder metallurgy process spread" to the manufacture of porous oil-impregnated bearings, cemented carbide tools, contact points, diamond grinding wheels, clutch facings, starter brushes, resin-bonded radio cores, magnets, metallic filters, and other parts. More recently, and particularly during the present war, there has been a definite trend toward the manufacture of machine parts by this process in competition with the more conventional fabricating methods. Notwithstanding these many developments, scientific progress has been slow. While many articles on powder metallurgy have appeared in the press and various publications, there have been too few contributions to our technical societies, with the result that there is a dearth of the type of information necessary for the full development of this science. It is of primary importance that the results of research and development be freely disseminated if powder metallurgy is to realize its fullest potentialities. Purpose of Investigation Excluding the refractory metal field, all commercial powder metallurgical products made by a cold compressing and sintering operation contain voids. These voids can be substantially eliminated by subsequent severe working and heat-treatment, but ' such practice has not proved economical in most applications. By applying heat during the compressing operation, plastic deformation of the powder particles is substantially increased, and the resultant compact or briquette is practically free of voids. However, hot-pressing has many attendant problems, which at present preclude its use in the manufacture of precision parts. The more important of these are to devise: 1. A die steel capable of withstanding high pressures at elevated temperatures. 2. A high-temperature lubricant capable of preventing excessive die wear and welding of the compact to the die walls. 3. A method of retaining a neutral or reducing atmosphere in the compacting zone of the die assembly. 4. A means of ejecting the hot-pressed specimen into a neutral atmosphere until reasonably cold.

Jan 1, 1946

By H. K. Birnbaum

The termination of a twin lamella in the interior of a crystal requires accommodation of the strains at the tip of the twin which result from coherency of the twin and matrix. In zinc and magnesium crystals,

Jan 1, 1960

By AIME AIME

The Institute Headquarters at Spokane was established at the Spokane Hotel, and included a Bureau of Information for the benefit and comfort of members and guests of the party during the time of the meeting. The first session, held Tuesday afternoon, Sept. 28, 1909, in the beautiful Convention Hall ,of Masonic Temple, was called to order by Mr. E. J. Roberts, Chairman of the Spokane Local Committee, who introduced Mr. J. C. Ralston, City Engineer, representing the Mayor of Spokane and the Spokane Chamber of Commerce. Mr. Ralston extended to the members and guests of the Institute a cordial welcome to the city of Spokane, substantially as follows:

Dec 1, 1909

By G. Howell Clevenger, Bhupendranath Ray

Formerly great divergence of opinion existed in regard to the influence of copper in steel, as affecting its various physical properties. More recently the investigations of Stead,l Breuil,2 Wigham,3 Burgess and Aston: Ball and Wingham,5 Miiller; Dillner,7 and others have shown fairly good agreement in the major points. Copper steel has been shown by these investigators to possess special properties which make it valuable for certain uses. The general range of composition of the useful alloys of copper and iron, and of copper, iron, and carbon, has been quite definitely established, for the former by Burgess and Aston,8 and for the latter by Breuil9 and Stead.10 Stead11 has removed one difficulty in reconciling certain of the earlier data by calling particular attention to the influence 'of carbon in copper steels. Another point which caused confusion in the earlier investigations, particularly in regard to " red-shortness," was the presence of sulphur. Failure to note the presence of sulphur often led to attributing " red-shortness" to the presence of small amounts of copper. Turner12 has called attention to the fact that where copper exists in an iron ore it often occurs as the sulphide, so that the presence of copper in steel made from such ores might also, necessarily, mean the presence of sulphur. It is evident that the effect in this case might be quite different than where pure copper was added.

Jan 1, 1914

Jan 7, 1976

By A. L. Holley

The first session was held in the rooms of the American Philosophical Society, on Tuesday evening, February 26th. The President, Dr. T. Sterry Hunt, called the meeting to order, and after a few introductory remarks concerning the importance of theoretical and speculative science, which often involves principles of the highest economic value, and, more than all that, serves to enlarge our conceptions of the universe, and ennoble us, by the cultivation which it affords to our most exalted faculties, proceeded to discuss some points in the chemistry of the atmosphere. It is known that there is in the crust of the earth a great amount of oxidized carbon, not only in the shape of coal, but also in the graphite or plunlbago of the crystalline rocks, in the various bituminous shales or pyroschists, which are found in all succeeding rock-formations, and also in the forms of bitumen and petroleum. All the analogies of nature lead us to conclude that these various carbonaceous substances have had an organic origin, and have been generated by the deoxidation of carbonic acid, a process effected by the growing plant, and attended with the liberation of oxygen. He showed that the carbon of a layer of coal covering the whole earth's surface to the thickness of one meter, would, in its production from carbonic dioxide, liberate an amount of oxygen equal to that now present in our atmosphere. But bituminous coal contains also a large amount of hydrogen, derived from the deoxidation of water, which implies the liberation of a farther portion of oxygen. The amount from this latter source would equal, for the various coals and asphalts, from one-eighth to one-fourth, and, for the petroleums, onehalf of that set free in the deoxidation of the carbon which these hydrocarbonaceous bodies contain. From what we know of the composition of the stratified rocks, it is probable that they include an amount of deoxidized carbon and hydrogen many times greater than that contained in a layer of coal one meter in thickness, and, consequently, that the disengaged oxygen in past ages must have far exceeded that now present in our atmosphere. To this must be added

Jan 1, 1879

THE first session was held in the rooms of the American Philosophical Society, on Tuesday evening, February 26th. The President, Dr. T. Sterry Hunt, called the meeting to order, and after a few introductory remarks concerning the importance of theoretical and speculative science, which often involves principles of the highest economic value, and, more than all that, serves to enlarge our conceptions of the universe, and ennoble us, by the cultivation which it affords to our most exalted faculties, proceeded to discuss some points in the chemistry of the atmosphere. It is known that there is in the crust of the earth a great amount of oxidized carbon, not only in the shape of coal, but also in the graphite or plumbago of the crystalline rocks, in the various bituminous shales or pyroschists, which are found in all succeeding rock-formations, and also in the forms of bitumen and petroleum. All the analogies of nature lead us to conclude that these various carbonaceous substances have had an organic origin, and have been generated by the deoxidation of carbonic acid, a process effected by the growing plant, and attended with the liberation of oxygen. He showed that the carbon of a layer of coal covering the whole earth's surface to the thickness of one meter, would, in its production from carbonic dioxide, liberate an amount of oxygen equal to that now present in our atmosphere. But bituminous coal contains also a large amount of hydrogen, derived from the deoxidation of water, which implies the liberation of a farther portion of oxygen. The amount from this latter source would equal, for the various coals and asphalts, from one-eighth to one-fourth, and, for the petroleums, one-half of that set free in the deoxidation of the carbon which these hydrocarbonaceous bodies contain. From what we know of the composition of the stratified rocks, it is probable that they include an amount of deoxidized carbon and hydrogen many times greater than that contained in a layer of coal one meter in thickness, and, consequently, that the disengaged oxygen in past ages must have far exceeded that now present in our atmosphere. To this must be added

Jan 1, 1878

The first session was held in the rooms of the American Philosophical Society, on Tuesday evening, February 26th. The President, Dr. T. Sterry Hunt, called the meeting to order, and after a few introductory remarks concerning the importance of theoretical and speculative science, which often involves principles of the highest economic value, and, more than all that, serves to enlarge our conceptions of the universe, and ennoble us, by the cultivation which it affords to our most exalted faculties, proceeded to discuss some points in the chemistry of the atmosphere. It is known that there is in the crust of the earth a great amount of oxidized carbon, not only in the shape of coal, but also in the graphite or plunlbago of the crystalline rocks, in the various bituminous shales or pyroschists, which are found in all succeeding rock-formations, and also in the forms of bitumen and petroleum. All the analogies of nature lead us to conclude that these various carbonaceous substances have had an organic origin, and have been generated by the deoxidation of carbonic acid, a process effected by the growing plant, and attended with the liberation of oxygen. He showed that the carbon of a layer of coal covering the whole earth's surface to the thickness of one meter, would, in its production from carbonic dioxide, liberate an amount of oxygen equal to that now present in our atmosphere. But bituminous coal contains also a large amount of hydrogen, derived from the deoxidation of water, which implies the liberation of a farther portion of oxygen. The amount from this latter source would equal, for the various coals and asphalts, from one-eighth to one-fourth, and, for the petroleums, onehalf of that set free in the deoxidation of the carbon which these hydrocarbonaceous bodies contain. From what we know of the composition of the stratified rocks, it is probable that they include an amount of deoxidized carbon and hydrogen many times greater than that contained in a layer of coal one meter in thickness, and, consequently, that the disengaged oxygen in past ages must have far exceeded that now present in our atmosphere. To this must be added

Jan 1, 1879

By W. D. France, H. l. Burghoff

FABRICATORS of copper and copper alloys have contended with the problems of reconversion during the past year in endeavoring to return to the full-scale production that is demanded of them. The problems have not been easy, for the industry, like so many others, has had to deal with strikes of long duration, and material shortages, particularly in the raw materials, copper, zinc, lead, and tin. Despite all these obstacles, it was possible to gear production to new peacetime records during the latter part of the year. This was made possible not only by the use of multiple shifts of personnel, but also by the improved production equipment, the development of which had been stimulated by wartime necessity. The work of installing new and better equipment is still continuing, and virtually every company is engaged in improving or planning to improve its processes.

Jan 1, 1947

McCulloch, Leon.-Experiments with Sherardizing. Discussed by Fred. L. Wolf, Willis M. Peirce, Jesse L. Jones, O. W. Storey, David R. Kellogg, William H. Finkeldey, L. H. Marshall 2 Bassett, W. H. and Davis, C. H.-Spectrum Analysis in an Industrial Laboratory. Discussed by C. S. Brainin, C. H. Davis, W. H. Bassett, George K. Burgess, George K. Elliott, Leonard Waldo, Keivin Burns 8 Roast, Harold J. and Pascoe, Charles F.-Arsenical Bearing Metals. Discussed by Jesse L. Jones, William A. Cowan,. William K. Frank, William M. Corse, Harold J. Roast 10 Bain, Edgar C.-Crystal Structure of Solid Solutions. Discussed by Ancel St. John, Edgar C. Bain, Paul D. Merica 14 Peirce, Willis M.-Studies on the Constitution of Binary Zinc-base Alloys. Discussed by George K. Burgess, Willis M. Peirce, D. H. Ingall, J. L. Haughton, K. E. Bingham 16 Webster, William R.-Application in Rolling of Effects of Carbon, Phosphorus and Manganese on Mechanical Properties of Steel. Discussed by George B. Waterhouse, J. O. Liebig, Ralph H. Sweetser, H. T. Morris, F. D. Carney, W. P. Barba, John H. Nelson, George K. Burgess 19 Barba, W. P. and Howe, Henry M.-Acid Open-hearth Process for Manufacture of Gun Steels and Fine Steels. Discussed by W. J. Priestley, Haakon Styri, C. T. Patterson, Harry Brearley, W. P. Barba, George F. Comstock, Alexander L. Feild 24 Kellogg, David R.-Electrolytic Deposition of Iron for Building up Worn or Undersized Parts. Discussed by Jesse L. Jones, William Blum, C. R. Hayward, George K. Burgess, C. P. Perin, David R. Kellogg 33 McQuaid, H. W. and Elm, E. W.-Effect of Quality of Steel on Case-carburizing Results. Discussed by H. J. French and L. Jordan, W. J. Priestley, M. H. Schmid, A. E. White, H. J. Stagg and S. C. Spalding, Henry S. Rawdon, J. S. Vanick 35 Phillips, Arthur and Davenport, E. S.-Malleableizing of White Cast Iron. Discussed by Samuel Epstein, H. A. Schwartz, A. E. White, R. S. Archer.... 58 Priestley, William J.-Effect of Sulfur and Oxides in Ordnance Steel. Discussed by Harry T. Morris, William J. Priestley, C. P. Perin, James H. Gray, W. P. Barba, Haakon Styri, Frank D. Carney, W. L. Harbrecht, George F. Comstock, E. J. Janitzky 67

Jan 5, 1922

By E. M. Porbansky

DURING the investigation of the electrical transport properties of copper, it became necessary to prepare large single crystals of the highest obtainable purity. In an effort to meet these demands, single crystals of copper have been grown by the conventional pulling technique—as has been used for the growth of germanium and silicon crystals.' Low-temperature resistance measurements made on these crystals show that, as far as their electrical properties are concerned, they are generally of significantly higher purity than the original high-purity material. The use of these pure single crystals with very high resistance ratios has made possible the acquisition of detailed information regarding the electron energy band structure of copper2-' and has stimulated widespread effort on Fermi surface studies of a number of other pure metals. It is the purpose of this note to describe our method of preparing very pure copper crystals by the Czochralski technique. Precautions were taken to prevent contamination of the melt from the crystal growing apparatus. A new fused silica growing chamber was used to prevent possible contamination from previous groqths of other materials such as germanium, silicon, and so forth. A new high-purity graphite crucible was used to contain the melt. This crucible was baked out in a hydrogen atmosphere at -1200°C for an hour, prior to its use in crystal growth. Commercial tank helium, containing uncontrolled traces of oxygen, was used as the protective atmosphere. A trace of oxygen in the atmosphere appears to be necessary for obtaining high-purity copper single crystals. A 3/8-in-diam polycrystalline copper rod of the same purity as the melt was used as a seed. The copper rod was allowed to come in contact with the melt while rotating at 57 rpm. When an equilibrium was observed between the melt and the seed (that is, the seed neither grew nor melted), the seed was pulled away from the melt at a rate of 0.5 mils per sec. As the seed was raised, the melt temperature was slowly increased, so that the grown material diminished in diameter with increasing length. When this portion of the grown crystal was -1 in. long and the diameter reduced to less than 1/8 in., the melt was slowly cooled and the crystal was allowed to increase to - 1-1/4 in. diam as it was grown. By reducing the diameter of the crystal in this manner, the number of crystals at the liquid-solid interface was decreased until only one crystal remained. Fig. 1 shows a typical pulled copper single crystal. The purity of the starting material and the crystals was determined by the resistance ratio method: where the ratio is taken as R273ok/R4.2ok. The starting material, obtained from American Smelting and Refining Co., was the purest copper available. Most of the pulled copper crystals had much higher resistance ratios than the starting material. The highest ratio obtained to data is 8000. Table I is an example of the data obtained from some of the copper crystals. Note that Crystal No. 126 had a lower resistance ratio than its starting material and this might be due to carbon in the melt. The melt of this crystal was heated 250" to 300°C above the melting point of copper. At this temperature it was observed that copper dissolved appreciable amounts of carbon. The possible presence of carbon at the interface between the liquid and the crystal will result in reducing conditions and negate the slight oxidizing condition required for high purity as discussed below. The possible explanations of the improvement in the copper purity compared to the starting material are: improvement in crystal perfection, segregation, and oxidation of impurities. Of these, the latter seems to be most probable. A study of the etch pits in the pulled crystals showed them to have between 107 and 108 pits per sq cm. The etch procedure used was developed by Love11 and Wernick.10 The resistivity of the purest copper crystal grown was 2 x 10-10 ohm-cm at 4.2oK; from the work of H. G. vanBuren,11 the resistivity due to the dislocations would be approximately 10-l3 ohm-cm, which indicates that. the dislocations in the copper crystals would contribute relatively little to the resistivity of the crystals at this purity level. Segregation does not seem likely as the reason for purification of the material, since the resistivity of the first-to-freeze and the last-to-freeze portions are approximately the same, as was observed on Crystal No. 124. On most of the crystals that were examined, the entire melt was grown into a single crystal. If the

Jan 1, 1964

By M. T. Hepworth, T. P. Papazoglou

Hydrogen diffusion in hcp and bcc titanium in the temperature range 610° to 900°C was measured by reacting cylindrical specimens of high-purity titanium at constant temperature with small constant pressures of hydrogen of the order of a few Torr. In the range 0 to 6.7 at. pct H in hcp titanium, the diffusion coefficient D in sq cm per sec is given by: where T is in °K and R in cal per g-atom OK. Only three measurements of diffusivity in bcc titanium were made: at 900' : the diffusivity in ß titanium was found to be 1.8 x 10-4 sq crn per sec. McQUILLAN1 has studied the constitution of the Ti-H system and reported the concentration of hydrogen as a function of pressure of hydrogen and temperature. He found hydrogen absorption was reversible and rapid at temperatures above 500°C in both crystallographic modifications, the a (hcp) phase and the ß (bcc) phase, with the latter phase stabilized by hydrogen additions. Wasilewski and Kehl 2 measured the diffusivity of hydrogen in hcp and bcc Ti-H alloys. For bcc alloys, they reacted cylindrical specimens of titanium with hydrogen gas at 1 atm pressure. They measured the rate of absorption of hydrogen isothermally on specimens ranging from zero hydrogen content when above the transformation temperature to hydrogen contents sufficient to stabilize the bcc phase when below the transformation temperature. By integrating Fick's second law for a cylindrical geometry, assuming a diffusion coefficient independent of composition, they calculated diffusivities as a function of temperature. In the range 650" to 1000°C their results in bcc titanium yielded the expression: where D is in sq cm per sec, T in OK, and R the gas constant in cal per g-atom-OK. Their studies on the hcp a phase were conducted by exposing long cylindrical titanium specimens to hydrogen at a sufficiently high pressure to establish a surface layer of fl phase 80 to 120 u thick for the duration of an isothermal experiment. Concentration profiles were then determined by hydrogen analysis from chips obtained upon machining quenched specimens. The diffusivity of hydrogen was then calculated yielding the expression: The present investigation was undertaken principally to redetermine the diffusivity data on a titanium by a direct absorption from the gas phase at sufficiently low hydrogen pressures to avoid the presence of a surface bcc phase and also to check the diffusivity data at low hydrogen concentrations in the bcc stmcture. EXPERIMENTAL PROCEDURE High-purity electrolytic sponge titanium (99.9 pct) of BHN 91 was arc-melted, forged, rolled, and machined into cylinders of final hardness, upon annealing, of BHN 92. Cylindrical specimens of two sets of dimensions were used: 1.524 by 2.931 cm and 1.905 by 3.663 cm diam and length, respectively. The experimental apparatus used for annealing specimens and for admitting known amounts of hydrogen at constant pressure is shown in Fig. 1. In a typical experiment, a specimen was lightly abraded with fine-grain silicon carbide, washed with water and detergent, and then thoroughly degreased with reagent-grade tri-chlorethylene and acetone. The specimen was suspended by a Chrome1 wire in the center of a quartz furnace tube, without contact with the tube, and heated to 925°C (as measured by a thermocouple adjacent to the specimen, outside the tube) for a period of at least 4 hr under a vacuum of from 10-6 to -7 Torr as measured by an ionization gage. The furnace temperature was then adjusted to the temperature chosen for the particular diffusion study and the specimen allowed to equilibrate thermally. Hydrogen was then ad-

Jan 1, 1969

By F. E. Lathe, L. Hodnett

This paper summarizes extensive data supplied by 40 copper converter plants in 18 countries, and includes a partial analysis and comments on the effect of converter slag composition and temperature on the fomzation and elimination of magnetite and the life of basic and neutral refractories. APRELIMINARY draft of this paper, including data from 26 companies which had submitted replies to a questionnaire, was presented at the Annual Meeting of the AIME held in New York in February, 1956. Publication was delayed in the expectation that additional replies would be received, and justification for the subsequent delay may be found in the fact that the present revised paper contains data from 40 converter plants situated in 18 different countries. The suggestion that a questionnaire be sent to the major copper and copper-nickel plants outside the U.S.S.R. and associated countries arose at the Los Angeles Annual Meeting in February, 1953, where several papers dealing with converter construction and operation were presented. In private discussions which followed, a group of metallurgists and refractories engineers raised the question why practices varied so much at different plants. Why did magnesite brick give superior service to chrome-magnesite in some plants but chrome-magnesite prove superior in others? Would metallurgical studies point the way to the development of still better refractories? Could magnetite formation be prevented in converter slags and reverber-atory furnace mattes? If this was feasible, why was a heavy circulating load of magnetite tolerated, when, in all probability, it increased copper losses in the reverberatory slags and, in some cases, made it necessary to shut down the furnaces periodically to clean out the accumulated magnetite? Was the sole purpose of coating brick with magnetite that of

Jan 1, 1959

By Mi Chung

T HE ore-dressing problem at Tul Mi Chung is complicated by the unusually complex nature of the ores. These come from replacement ore- bodies in limestone at the contact with a granite batholith, and contain copper, gold, silver, bismuth, molybdenum, iron, arsenic, zinc, and lead, the first two metals constituting the principal sources of profit. Iron is present as pyrite, magnetite, and hematite. Arsenic occurs both as mispickel and lollingite (FelAsa), the latter carrying a certain amount of finely divided gold. The gangue minerals are those typical of limestone con- tact-metamorphism and include a large percentage of garnet, together with diopside, serpentine, calcite, epidote, zoisite, actinolite, 'mica and other minerals. A part of the gold occurs in a free state; some is combined with chalcopyrite and lollingite, and a consider- able proportion is contained in the pyrite. Researches towards the improvement of recovery have been energetically conducted since 1915. Amalgamation, gravity concentrating tables, vanners, can- vas plants, etc., have all been tried and discarded in favor of flotation. It was very quickly established that fine grinding was essential for satisfactory recovery. This was and is still accomplished in Hardinge ball and pebble mills. A comparative test showed that when the ore was crushed to the point at which it contained 20 to 26 per cent. coarser than 100 mesh, the gold recovery was only 55.9 per cent., whereas when crushed so that only 11 to 15 per cent. was coarser than 100 mesh, the gold recovery was increased to 82.5 per cent. No particular difficulty was ever experienced in making a satisfactory recovery of copper but the losses in gold were considered serious and led to the investigation described in this paper.

Jan 1, 1924

By McHenry Mosier

MeRcuRy is one of the strategic metals of which the supply has been raised from critical uncertainty to more than enough for essential demands. Work by the Bureau of Mines has contributed substantially to increased production of mercury in the United States and to consequent accumulation of Government stocks. Other contributing factors have been higher prices for mercury and Government loans to operators. The Bureau has undertaken 13 exploration projects, 10 of which have been completed. This work has comprised 28,376 ft. of several types of drilling and 23,798 lin. ft. of surface trenching, and has indicated commercial ore containing 34,800 flasks of mercury and marginal ore containing 26,200 flasks, a total of 61,000 flasks; equivalent, respectively, to domestic production for 8 months, 6 months, and 14 months. As Government stocks are now adequate, domestic production (currently at the rate of 50,000 flasks per year) is gradually being curtailed through Government control of labor and operating supplies. Introduction Mercury was one of the seven metals designated as strategic by the Army and Navy Munitions Board in 1939, when Congress appropriated funds for the investigation of domestic sources of supply of war minerals. The Bureau of Mines immediately started a limited search for strategic minerals, but the first mercury project was not begun until December 1940. The U. S. Geological Survey assisted in the search for cinnabar by contributing information on domestic mercury deposits, preparing maps, and making geological studies of exploration projects. The present high rate of production of mercury in the United States was encouraged by the increase in price to $196 per flask at New York (Fig. I) and Government loans to operators for mine development and plant construction. The Bureau of Mines has issued, for restricted distribution subject to wartime controls, 13 War Minerals Reports on individual mercury deposits (listed in appendix A). In March 1942 it also published a Progress Report of the Metallurgical Division, R. I. 3627, Cinnabar-reduction Plants of the Southwestern Arkansas Quicksilver District. Uses of Mercury Mercury and its compounds have more than 3000 uses. Its principal use is as a catalyst in the manufacture of gases for chemical warfare; the next largest is in pharmaceuticals. Mercury is essential also for: (I) certain electrical apparatus, (2) industrial control instruments at many war plants, (3) munitions, including blasting caps, (4) insecticides in agriculture, (5) antifouling paint for ship bottoms, (6) dental preparations, (7) general laboratory use, and (8) amalgamation of free-milling gold ores.

Jan 1, 1949

By McHenry Mosier

MeRcuRy is one of the strategic metals of which the supply has been raised from critical uncertainty to more than enough for essential demands. Work by the Bureau of Mines has contributed substantially to increased production of mercury in the United States and to consequent accumulation of Government stocks. Other contributing factors have been higher prices for mercury and Government loans to operators. The Bureau has undertaken 13 exploration projects, 10 of which have been completed. This work has comprised 28,376 ft. of several types of drilling and 23,798 lin. ft. of surface trenching, and has indicated commercial ore containing 34,800 flasks of mercury and marginal ore containing 26,200 flasks, a total of 61,000 flasks; equivalent, respectively, to domestic production for 8 months, 6 months, and 14 months. As Government stocks are now adequate, domestic production (currently at the rate of 50,000 flasks per year) is gradually being curtailed through Government control of labor and operating supplies. Introduction Mercury was one of the seven metals designated as strategic by the Army and Navy Munitions Board in 1939, when Congress appropriated funds for the investigation of domestic sources of supply of war minerals. The Bureau of Mines immediately started a limited search for strategic minerals, but the first mercury project was not begun until December 1940. The U. S. Geological Survey assisted in the search for cinnabar by contributing information on domestic mercury deposits, preparing maps, and making geological studies of exploration projects. The present high rate of production of mercury in the United States was encouraged by the increase in price to $196 per flask at New York (Fig. I) and Government loans to operators for mine development and plant construction. The Bureau of Mines has issued, for restricted distribution subject to wartime controls, 13 War Minerals Reports on individual mercury deposits (listed in appendix A). In March 1942 it also published a Progress Report of the Metallurgical Division, R. I. 3627, Cinnabar-reduction Plants of the Southwestern Arkansas Quicksilver District. Uses of Mercury Mercury and its compounds have more than 3000 uses. Its principal use is as a catalyst in the manufacture of gases for chemical warfare; the next largest is in pharmaceuticals. Mercury is essential also for: (I) certain electrical apparatus, (2) industrial control instruments at many war plants, (3) munitions, including blasting caps, (4) insecticides in agriculture, (5) antifouling paint for ship bottoms, (6) dental preparations, (7) general laboratory use, and (8) amalgamation of free-milling gold ores.

Jan 1, 1949

By J. R. Craig, T. N. Solberg, M. A. Linden

The central and southern Appalachian Mountains were the major sources of domestically produced gold throughout the first half of the 19th century and continue to yield gold today. Small amounts of gold were probably extracted by the Indians and the Spaniards but the first documented report of gold in the region was made by Thomas Jefferson who found, in the Rappahannock River of Virginia in 1782, a 1.8 kg (4 lb) lump of gold ore that yielded 26 g (0.85 oz). Gold was subsequently discovered in North Carolina between 1793 and 1799, in Virginia in 1806, in South Carolina in 1827, in Georgia in 1829, and in Alabama about 1830 (Becker, 1894-5; Pardee and Park, 1948). Production climbed to more than 933 kg/a (30,000 oz per year) between 1830 and 1852, but dropped sharply after the California gold rush in 1849 as experienced miners moved west in search of bigger and easier stakes. The Civil War briefly halted gold mining in the Appalachians, but production rose to an average of about 249 kg/a (8,000 oz per year) from 1865 until 1878 and to about 404 kg/a (13,000 oz per year) from 1881 until 1915 when it again fell to near nil (Pardee and Park, 1948). Minor resurgences occurred in the 1930s and 1940s. Although there has been no reported production in recent years, it is likely that "weekend panners" still remove hundreds of ounces from streams annually. The total reported production for the area through 1959 is more than 77 t (2.5 million oz). This paper reports some initial findings of a long-term project designed to investigate the mineralogy, chemistry, mode of occurrence, and petrology of gold occurrences in the Appalachians. The goal of the initial phase was to determine the compositional range of gold in the Appalachians as a step toward deciding if sufficient variations were present to allow the definition of "compositional signatures." The very few published data on gold fineness in the Appalachians are based on assays that commonly include gold and silver from several mineral species. Analyses in the present study were performed on individual grains of electrum using a spot size of 10 µm x 10 µm to 100 µm X 100 µm (394 X 394 micro in. to 3,940 X 3,940 micro in.), and thus reveal the true composition of the principal precious metal-bearing phase.

Jan 1, 1984

By Harold Margolin, W. R. Hibbard, R. W. Fenn, H. P. Moore

Deformation lines, also called etch markings or strain markings, are non-effaceable lines developed in individual grains by etching a metal specimen which has been cold worked sufficiently to cause atomic non-conformity or slight orientation differences within the grains. Etching occurs more rapidly at these lines of high chemical reactivity to produce a result similar to that revealing grain boundaries. Wider etching effects forming bands have been found. They are believed to be bands of deformation lines which form areas of measurably different orientation from the crystal matrix. The crystallite rotations causing these bands have been shown by Barrett2 to contribute to deformation textures. Although deformation lines have been observed in many metals, the amount of deformation requireti for their appearance has been established only in general terms. Mathewson and Phillips3 observed the first appearance of deformation lines in cold-rolled alpha brass at about 20 pct reduction in thickness using the standard ammonium hydroxide hydrogen peroxide etchant. Price and Davidson4 noted defor- mation lines in common high brass after 26.5 pct reduction by cold rolling using the same etchant. Johnson6 observed dark thick forklike lines in 99.99 pct pure copper reduced 31.8 pct. Adcock6 observed deformation lines in 80-20 copper-nickel alloy rolled 50 pct. Samans7 found no deformation lines in alpha brass single crystals cold rolled 9.5 pct but they did appear after 25 pct reduction using ammonium hydroxide and hydrogen peroxide etchant. Barrett and Levenson8 observed deformation bands in drawn polycrystalline iron at very small reductions in area and noted that their initial appearance perhaps depends on grain size and other conditions. They reported deformation bands in a single crystal of iron reduced 6 pct by drawing. Brickg noted that deformation lines in 70-30 brass apparently associated with I I I I ) planes appeared after reductions of from 20-50 pct by cold rolling. Brick and Williamson10 noted that in single crystals of 70-30 alpha brass "as in polycrystalline brass, no deformation markings appeared until reductions exceeded 20 pct." Cook and Richards" reported that in Copper cold rolled less than about 50 Pet few strain markings were apparent but for higher reductions many strain markings appeared transverse to the rolled direction. In a review article Brick and Phillips12 noted that previous studies had not shown deformation lines in cold rolled alpha brass below 20 pet reduction and added that 4

Jan 1, 1949