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By G. R. Fitterer

By means of the C-Sic thermocouple1, liquid metal temperatures have been found to vary much more than was previously supposed, and fortunately these variations can be directly associated with some of our former knowledge which combined to form the "art" of liquid-metal manipulation. Commercial Development of This Device Several types of installations are operating in different plants. There are so many variables in steel plants in regard to operation, procedure, arrangement of pouring platforms, ladles, etc., that most of the installations now in service in this country are "tailor-made"; nevertheless, it is felt that satisfactory gains have been made, inasmuch as each installation has indicated some effect of temperature upon the metallurgical operation, and has pointed the way toward technical and financial benefits. In most cases, it has been necessary to accumulate the temperature data until sufficient metallurgical information is available for the drawing of conclusions. When mechanical difficulties have been eliminated, a distinct correlation of these factors has been obtained. The installations now in service are used for the determination of temperatures in the basic open-hearth furnace prior to tapping and in ladles from both acid and basic furnaces prior to pouring. Some of the installations are in shops making the higher priced steels; others are in "tonnage shops." The errors of human element, smoke screens and emissivity corrections connected with the use of the optical pyrometer do not affect the C-SiC thermocouple readings. The accuracy of the C-Sic thermocouple and the temperatures measured are discussed later in this paper. Temperature Variations or Liquid Pig Iron One well-known discussion between the blast-furnace and open-hearth (or Bessemer) departments has occurred intermittently for more

Jan 1, 1936

By Roger V. Pierce

INTRODUCTION IN the last few years, much study has been devoted to increasing stoping efficiency. The reasons for this are shortage of manpower, shorter working hours, operating regulations, and shortages of essential materials. More efficiency in mining methods is needed to offset these adverse factors. In the past, attention has been centered upon haulage, hoisting equipment, mill flowsheets, etc., but recently the spotlight has been focused on the cost of stoping and the cost of handling materials. Scrapers and scraper hoists have thus assumed greater importance. In order to make it possible for certain ore bodies to be mined at a profit, it has been necessary to apply assembly-line practices to the streamlining of mining methods. All cycles of the mining operation must balance, and the sooner broken ore is removed from the working face, the sooner another round can be started. Since the introduction of scraper hoists in metal mines more than thirty years ago, much progress has been made in their design and application. Alert operators are now constantly watching for methods in which to apply scrapers. The saving of manpower in development work and the changing of mining methods that once employed manual handling of materials are increasing vital wartime tonnages. Essential ores from newly discovered ore bodies are moving rapidly from stopes to reduction plants-because it is now possible to develop an ore body and place it in production with a minimum of manpower and development work. Today, speed is one of the prime essentials of mining. Everywhere, there is a concentrated effort to use experienced miners in breaking rock, in timbering, and in carrying out the various phases of mining that require many months of training. Much effort is being made to mechanize the working places because experienced men naturally prefer to work where the majority of materials are handled mechanically. In line with this policy, many new men are being taught the details of scraper work, because even green men can quickly become acquainted with scrapers and thereby release older heads to perform the more skilled phases of mining. In some places it has been found economical to change from one system of stoping to another that more readily allows the application of mechanical muck-handling equipment. Where blocks are worked faster, the cost of materials, time, and labor is cut drastically. This favorable situation allows more manpower to remain on straight breaking and timbering-or straight production mining. More-over, when blocks are mined faster, more floors can often be mined vertically before the mucking or wheel floor is moved. This results in several direct savings. There are cases where it has been proved that by working a given block faster more area, longitudinally or vertically, could be mined at one time, thus permitting the reduction of development cost. (Fig. I.)

Jan 1, 1943

By W. H. Bassett, J. C. Bradley

In considering the effects of reducing gases on hot solid copper the following conclusions have been reached. (I) Depth of deoxidation of copper heated in reducing gas is grealer the smaller the amount of cuprous oxide originally present in the copper, the range studied being from 0.015 to 0.136 per cent. oxygen. It is suggested that the reason for this diflerence in depth of deoxidation is thai, when the copper is low in cuprous oxide, the reducing gas is diluted less by the gas that is formed in the reaction than when the copper is high in cuprous oxide; and the greater the concentration of the reducing gas the deeper the deoxidation. (2) The rate of deoxidation is much more rapid at the beginning of exposure than at the end, a condition especially noticeable at temperatures around 900" C.; that is, deoxidaion is retarded as the depth penetrated by the reducing gas increases. (3) Within the accuracy of the experiments arsenic in copper up to 0.5 per cent. has no tendency to increase or decrease the action of a reducing gas on the cuprous oxide presenx in the copper. In 1912 pieces of 0.365-in. hard copper rod 1/2 in. long were heated in a porcelain tube in an electric furnace, while illuminating gas was passed through. An approximate analysis of this gas is: Hydrogen 38 per cent., carbon monoxide 30 per cent., illuminants 13 per cent., methane 10 per cent., ethane 3 per cent., carbon dioxide 3 per cent., nitrogen 2 per cent., oxygen 0.4 per cent. After heating for various lengths of time at various temperatures, samples were quenched

Jan 1, 1926

By L. L. Swift

.It the present time there are four base metals being used for automo-tive bearing alloys. Of course there are numerous variations in the amounts of alloying elements added to each base metal and nearly all of these alloys have the conventional, if not classical, duplex structure; that is, they are composed of a hard constituent embedded in a soft matrix. The well-known theory is that the former will wear well, while the latter will be plastic enough to allow the bearing to be broken in and conform to the contours of the shaft. The requirements of the modern bearing have been most aptly described by W. M. Corse: In order to meet the engineering demands of today a good bearing metal must be able to carry the weight of the shaft and stand up under steady or suddenly applied loads, or even blows ill sorne types of service. A certain amount of plasticity is desired to compensate for minute irregularities in the shaft or bearing surface, and to permit yielding, thereby avoiding dangerous stresses in bearing and shaft and pre-venting overheating and rapid wear of parts. Less plasticity is required in a bearing tuetal if the surfaces of bearings and journals are machined accurately, aligned, and kept in alignment. It is desirable, of course, that a bearing metal have a low coeffi-cicnt of friction. Under most operating conditions the friction depends on the unit, pressure of the bcaring, the speed, the temperature, and the properties of the lubricant. A good bearing metal must have a low rate of wear to reduce the necessity for frequent replacements, and adjustment of the bearings. It must wear more rapidly, however, than the journal or shaft running on it, because replacement of the journal or shaft is more difficult and costly than replacement of the bearing.' The hardness of the bearing alloy is a property closely related to several of the foregoing. With a duplex microstructure, the measurement of hardness with any of the usual commercial devices means little. The Bierbaum method of measuring the hardness of the individual canstituents was developed to fill this need. MICROCHARACTER The Bierbaum MicroCharacter~,~ measures the scratch-hardness of a solid by pulling a weighted diamond point over the surface. The diamond point is ground so that it is the corner of a cube, and Mounted

Jan 1, 1939

By L. L. Swift

.It the present time there are four base metals being used for automo-tive bearing alloys. Of course there are numerous variations in the amounts of alloying elements added to each base metal and nearly all of these alloys have the conventional, if not classical, duplex structure; that is, they are composed of a hard constituent embedded in a soft matrix. The well-known theory is that the former will wear well, while the latter will be plastic enough to allow the bearing to be broken in and conform to the contours of the shaft. The requirements of the modern bearing have been most aptly described by W. M. Corse: In order to meet the engineering demands of today a good bearing metal must be able to carry the weight of the shaft and stand up under steady or suddenly applied loads, or even blows ill sorne types of service. A certain amount of plasticity is desired to compensate for minute irregularities in the shaft or bearing surface, and to permit yielding, thereby avoiding dangerous stresses in bearing and shaft and pre-venting overheating and rapid wear of parts. Less plasticity is required in a bearing tuetal if the surfaces of bearings and journals are machined accurately, aligned, and kept in alignment. It is desirable, of course, that a bearing metal have a low coeffi-cicnt of friction. Under most operating conditions the friction depends on the unit, pressure of the bcaring, the speed, the temperature, and the properties of the lubricant. A good bearing metal must have a low rate of wear to reduce the necessity for frequent replacements, and adjustment of the bearings. It must wear more rapidly, however, than the journal or shaft running on it, because replacement of the journal or shaft is more difficult and costly than replacement of the bearing.' The hardness of the bearing alloy is a property closely related to several of the foregoing. With a duplex microstructure, the measurement of hardness with any of the usual commercial devices means little. The Bierbaum method of measuring the hardness of the individual canstituents was developed to fill this need. MICROCHARACTER The Bierbaum MicroCharacter~,~ measures the scratch-hardness of a solid by pulling a weighted diamond point over the surface. The diamond point is ground so that it is the corner of a cube, and Mounted

Jan 1, 1939

By C. M. Tucker, K. R. Van Horn, W. P. Sykes

Recent investigations of the molybdenum-carbon alloys have been reported by Becker and Ebertl,‡ Westgren and Phragmén2, T. Takei3, and H. Tutiya4. Takei3 studied the Mo-C system by employing metal-lographic and X-ray methods, and the other publications described the determination of the crystal structure of the molybdenum carbides. In exploring this system by a technique previously applied to the tungsten-carbon series5, the results of Takei were confirmed with two definite exceptions; i.e., first the composition of the eutectic, and second the nature of the carbon-rich intermediate phase. Consequently, a more thorough examination of the molybdenum-carbon constitution was initiated in an effort to correlate the data supplied by the microstructures, diffraction patterns and chemical analyses. Metallographic Investigation A briquette of molybdenum powder when heated in a carburizing atmosphere at 1500" to 1600" C. for several hours develops the carbon-rich layer shown in Fig. 1. The carburization was accomplished by placing the briquette in a carbon tube, which was heated in the hydrogen atmosphere of an alundum muffle wound with tungsten resistor. While the macrostructure indicates two distinct shells, and suggests the possibility of two carbon-rich phases, no evidence of this condition could be detected by the microscope, which revealed but one high-carbon constituent. This carbide forms next to the molybdenum as a relatively dense, light-colored zone (Fig. 2) which passes abruptly into an outer layer of spongy texture. As will be noted later, only one intermediate phase was observed in the X-ray photograms prepared of different locations in the carburized zone. The metallographic structure at the inner border of the shell, reproduced in Fig. 3, shows a marked porosity accom-

Jan 1, 1935

By C. M. Tucker, K. R. Van Horn, W. P. Sykes

Recent investigations of the molybdenum-carbon alloys have been reported by Becker and Ebertl,‡ Westgren and Phragmén2, T. Takei3, and H. Tutiya4. Takei3 studied the Mo-C system by employing metal-lographic and X-ray methods, and the other publications described the determination of the crystal structure of the molybdenum carbides. In exploring this system by a technique previously applied to the tungsten-carbon series5, the results of Takei were confirmed with two definite exceptions; i.e., first the composition of the eutectic, and second the nature of the carbon-rich intermediate phase. Consequently, a more thorough examination of the molybdenum-carbon constitution was initiated in an effort to correlate the data supplied by the microstructures, diffraction patterns and chemical analyses. Metallographic Investigation A briquette of molybdenum powder when heated in a carburizing atmosphere at 1500" to 1600" C. for several hours develops the carbon-rich layer shown in Fig. 1. The carburization was accomplished by placing the briquette in a carbon tube, which was heated in the hydrogen atmosphere of an alundum muffle wound with tungsten resistor. While the macrostructure indicates two distinct shells, and suggests the possibility of two carbon-rich phases, no evidence of this condition could be detected by the microscope, which revealed but one high-carbon constituent. This carbide forms next to the molybdenum as a relatively dense, light-colored zone (Fig. 2) which passes abruptly into an outer layer of spongy texture. As will be noted later, only one intermediate phase was observed in the X-ray photograms prepared of different locations in the carburized zone. The metallographic structure at the inner border of the shell, reproduced in Fig. 3, shows a marked porosity accom-

Jan 1, 1935

By Robert Goodrich

THERE is a small area about Murray where bedded gold quartz veins occur in Prichard slate. The ore taken from the upper levels, during the early days, was free milling and was treated by stamp milling and amalgamation. There was likewise a considerable placer working. The report is current that tungsten (scheelite) was encountered, which interfered with the amalgamation in the stamp mills and which, in placering, collected in the riffles in the sluice boxes and. clogged them. Consequently, in the quartz mines, the scheelite, when encountered, was rejected, being thrown into the waste, sometimes inside the mine and at other times outside on the clump. The free surface ores became worked out and as the ore in depth became pyritic and rebellious to amalgamation the mines closed down. Last spring tungsten ore brought a high price, near $80 per unit, 60 per cent. W03 and up. This so stimulated the output of tungsten ore that old clumps were explored and waste stored in the mines was gone over. Tungsten was likewise mined from virgin ground. So the district produced quite heavily for a time. The condition now is different. The price is not so high, about $20 per unit W03, which makes profits questionable when mining in new ground. The accumulations from early clay mining have been exhausted and the output has greatly declined. The Golden Chest mine was the heaviest producer of tungsten. The months of June and July were spent at this mine studying the problem. Since the mine had produced both gold and tungsten, we looked forward to the problem of recovering both from what might be called a gold-tungsten ore. A study of the Golden Chest vein showed this not to be so there. While gold ore and tungsten ore come from the same vein, the tungsten ore is confined to a more or less disturbed or distorted portion

Jan 8, 1917

By Colin C. Harris, Nathaniel Arbiter

Flotation kinetics is the study of the variation in amount of froth overflow product with flotation time, and the quantitative identification of all rate con- trolling variables. With such variables maintained constant, the algebraic relationship between the proportion of mineral floated and flotation time is a flotation rate equation. This contains the constant values of all the rate determining variables implicit in one or more rate constants which must be evaluated from experimental data. The form or forms of the rate equation can either be deduced from assumptions or facts established about the mechanism of the process, or, more commonly, determined empirically or by analogy with similar rate process. (See pages 215 to 226 and 221 to 227.) The earliest contributions on flotation kinetics came in the mid- ~hirties,3,27,31 with interest increasing in recent years. The broad goal of these studies is the reduction of the total variability of a flotation system to equations among the individual variables, or among a lesser number of dimensionless groups.43 Although the goal is at present far from realization, its attainment will yield many practical advantages. The quantitative under- standing of the process should lead to improvements both in metallurgical results and flotation cell design. It should lead also to reliable methods for scaling-up* of laboratory and pilot plant results to full size operation without the need for expensive and time-consuming mill tests on commercial machines. Finally, this type of quantitative information will assist the automation of flotation cells and circuits as well as control by computers. Replacing present methods of control based on post-mortem assays and trial and error manipulation of reagents and cell variables by control through exact process analysis should yield higher levels of grade and recovery through reduction of the large variability of present-day results. CHEMICAL ENGINEERING ANALOGIES: Industrial flotation always involves flow of pulp through a series of stirred tanks. It thus bears formal analogy to many chemical engineering processes, the kinetics of which in flow systems has been studied for many de- cades.38,39,73,83 It will be useful to review these studies before considering flotation kinetics. Batch and continuous treatment are classified in Fig. 1. Batch operation in the true sense is unknown in flotation where concentrate is always removed

Jan 1, 1962

By Charles L. Mantell, George Ferment

This investigation determined the jeasibility of current-potential curves as an analytical tool for monitoving manganese electroicinning solutions for metallic impurities. Nine metallic impurities were studied: trickel, cobalt, silver, copper, zinc, molybdenum, catlmiun magnesium, and sodium. The individual effect of each metallic irzplrl,iLy on the standard point-izatiorr was determined for a range of 'concentration. Not all of Ihe impurities affected the polarization curve; correlation between transition current and cotrcetztration of impurity. Molybdenum had an uncorrelated effect on the polarization curie. The effects of binary mixtures of impurities were studied to see if the transition current of the mixture could be predicted. Interactions occurred between impurities which prei'etzted the pvecliction the transition current of tile rrlisLitr.e by additive laws. The polarization curve was shown to be sensitive to metallic impurities which affect the current efficiency of a manganese cell. THE application of current-potential curves in manganese electrowinning is not new but played an important part in the conversion of an inoperative large-scale pilot plant into a continuous comnercial operation.1"" The effects of trace metallic impurities in manganese electrowinning solutions on cathode current-potential curves,5-19 specifically nine impurities (nickel, cobalt, silver, copper, zinc, molybdenum, cadmium, magnesium, and sodium) were studied for a range of concentrations. Cadmium, magnesium, and sodium had no effect. Nickel, cobalt, silver, copper, and zinc yielded a correlation between transition current and concentration of impurity: molybdenum had an uncorrelated effect. Binary mixtures of impurities were studied to de-termine if the transition current could be predicted from the values for the individual constituents. Interactions between impurities prevented the prediction of the transition current of the mixtures by an additive law. The polarization curve was shown to be sensitive to metallic impurities which affected the rurrent efficiency of a manganese cell. The electrowinning of manganese relies upon maintaining a high-purity electrolyte. Purification schemes were developed to remove all of the heavy metals, the magnesium and calcium. Concentration limits have been established for single impurities. With high-purity electrolytes, favorable cell efficiencies are consistently obtained; but with impure solutions there is a reduction in efficiency. With the rapid rise to commercial prominence of electrochemical processes, there has been a lag in developing rapid methods for determining whether an electrolyte is sufficiently pure for efficient electrolysis. The most sensitive test for impurities is the behavior of the electrochemical cell. Impure electrolytes will cause a serious reduction in cell efficiency, and in many cases metal deposition will be prevented or reversed. The effects of impurities are not usually evident until after long periods of electrolysis, resulting in a disruption of the process. A method which could predict the behavior of an electrolyte in terms of cell efficiency prior to reaching the commercial cell is needed. Van Arsdale and Maier," Allmand and Campbell,a1'22 and others attempted to develop an electrochemical process for manganese,"3"29 but all met with some degree of difficulty. Jacobs et a studied the effects of metallic impurities in manganese electrowinning. Plant methods were based on a 2-hr plating in a small electrolytic cell. The final method was based on a 24-hr plating run, performed in a relatively large test cell. Here, current efficiencies were calculated with and without impurities in the electrolyte, and the critical concentration was established as the maximum amount of impurity that the electrolyte could tolerate before there was a serious loss in efficiency. The amount of impurity that could be tolerated decreased as the plating time increased, indicating deposition of the impurity. This test duplicated the conditions of commercial practire, and was sensitive to impurities. Small amounts of impurities significantly affect the hydrogen overvoltage at a metal surface, increasing or decreasing it depending upon the nature of the impurity. ockris established the limit for the onset of poisoning at 10-l moles per liter. The effects of impurities were studied by potential-time curves at a constant current density. The technique did not lend itself to rapid analysis in that several hours were needed to establish stable potential-time curves. Serfass and coworkers3' developed calorimetric and spectrophotometric techniques for analyzing for trace impurities. Our method4'" is based on current-cathode potential curves produced by continuously changing the cell voltage at a programmed rate. Starting with a clean stainless-steel cathode, the cell voltage was initially adjusted to yield zero current: the program was then started and the current was plotted as a function of the cathode potential. Fig. 1 is a typical current-potential curve. In initial region A the hydrogen-evolution reaction predominates and the polarization curve

Jan 1, 1967

By Lawrence Wright

THE occurrence of gold, gold-silver, silver-lead-zinc ores in the post-Cambrian sediments in the Black Hills of South Dakota, and their genetic relationship to the Tertiary intrusives, is well known and accepted, but the occurrence of gold in the pre-Cambrian rocks at the Homestake mine, which underlie this Tertiary gold mineralization, has given rise to differ-ences of opinion as to the period of major gold introduction into the older rocks. Fig. 1 illustrates. the distribution of mineralization along the axis of the Tertiary uplift in both pre-Cambrian and post-Cambrian rocks. The following possibilities have been presented: 1. The Homestake gold deposit was formed in pre-Cambrian time and the deposits in the overlying Cambrian sediments formed during Ter-tiary time. 2. The Homestake lode existed at the beginning of Cambrian time, but was enriched by the passage of Tertiary auriferous solutions. 3. The Homestake lode was represented by pre-Cambrian quartz-chlorite sulfide mineralization, very low in gold content and the gold superimposed on the older nearly barren mineralization during the Ter-tiary metallogenic epoch. 4. The sulfides and sulfarsenides as well as gold were deposited in both pre-Cambrian and post-Cambrian rocks during the Tertiary period. Those favoring the first proposition feel that the question is pretty well settled, while the proponents of the second theory are more flexible in their view, feeling that the amount of gold introduced in either period is still an open question. The third and fourth theories, with some modifi-cations, are supported by the proponents of the Tertiary theory, who feel that the evidence strongly favors that period. The following pages are intended to present the evidence and to give the reaction of various observers with my own comments and conclu-sions; also, the accumulated facts of observation gathered over a period of close association with the area under discussion, beginning in 1919.

Jan 1, 1936

By R. E. Reed-Hill

Recently Levine applied the Conrad-Wiedersich17 equation where H is the activation enthalpy, v the activation volume, T* the effective shear flow stress, T the absolute temperature, and ? the strain rate, to an analysis of titanium single-crystal data. The activation energy as a function of testing temperaturs obtained from specimens oriented for single (1010) prismatic slip is shown in Fig. 12. This diagram indicates a different linear dependence of H on T in the temperature interval from 220° to 300°K than from 0° to 220°K. Levine interpreted the break in this curve as indicating a change in the thermally activated mechanism controlling the flow stress. The purpose of this communication is to point out that the data in Fig. 1 is not consistent with the concept of a flow stress controlled by a simple thermally activated mechanism between 220° and 300°K. The Conrad-Wiedersich relation assumed that the strain rate can be expressed by:

Jan 1, 1968

By R. L. Loofbourow

Trends in the metal mining industry were definitely down in 1954. With a record in 1953 of $1.8 billion output, the last year dropped to $1.5 billion, the lowest value since 1950. The decrease in iron ore production alone accounted for at least 10 pct of the decline. PROBABLY more than any previous year, political debates of 1954 marked a new high for the mining industry. Lead and zinc prices gave forth with minor rallies producing no real improvements. An anticipated drop in copper prices never came to be. Early in the year arguments for more free trade versus tariffs to restrict imports were voiced eloquently by Charles P. Taft, president, Committee for a National Trade Policy, and Andrew Fletcher, president, St. Joseph Lead Co.

Jan 3, 1955

By J. B. Newkirk

Results of a Debye-Scherrer X-ray investigation are given which show that the order-disorder transformation is a first-order or heterogeneous reaction in Cu-AU alloys with compositions near CuAu. Evidence was found for conventional tie-line segregation across a usual type of two-phase field separating the ordered and disordered fields in the Cu-Au equilibrium phase diagram. The horizontal and vertical widths of the two-phase fields are about 3 atomic pct and 20°C, respectively, at 43 and 54 atomic pct Au. No evidence for the existence of an ordered structure based on a stoichiometric composition of Cu3Au2 could be found. ALTHOUGH the modern theories relating the de-Agree of order of binary alloys to temperature and composition have met with considerable success, the nature of the transformation from the disordered state to the ordered state and vice versa has never been well understood. It has been assumed by some' that this is a second-order transformation, that is, a homogeneous change of state. Others2 hold that the transformation is first-order and that the effects characteristic of heterogeneous phase transformation apply. Since this subject is discussed in detail in a recent paper,' the arguments will not be repeated here. The present paper summarizes an experiment which was designed to distinguish between these two viewpoints for the case of Cu-Au alloys near the composition CuAu. The Cu-Au system is an important one because it furnishes prototype alloys, the behavior of which has formed the basis of much of the present-day order-disorder theory. It has recently been shown- hat in alloys near Cu3Au there is a temperature range within which the ordered and disordered states coexist in equilibrium and are distinguishable as separate phases. Therefore, the transformation must be first-order for these alloys. A similar demonstration for alloys near CuAu, however, has been lacking. Experimental Method Essentially the experiment consisted of equilibrating Cu-Au samples at various temperatures, quenching them in water to retain the high temperature states, and then examining them at room temperature for the coexistence of the ordered and disordered structures. The thermal gradient method of heat treatment- as used because it was important that all temperatures over the transformation range should be represented in the test. Briefly, this method consisted of holding a wire of the desired composition, sealed under vacuum in Pyrex, in a known temperature gradient for a long enough time to allow each part of the wire to assume the crystal structure characteristic of the temperature at which it was held. The temperature gradient was produced by inserting into an ordinary wire-wound cylindrical laboratory furnace, an 18 in. length of 1/8 in. ID ceramic tube which was heavily wrapped with asbestos. The furnace power was controlled by a Tag-liabue Celectray controller and a chromel-alumel thermocouple with the junction located on the heating elements. During the equilibrating treatment the widest variation of temperature within the gradient tube was approximately 4°C at the highest temperature. The temperature at various places within the tube was determined, before inserting

Jan 1, 1954

By G. M. Kirwan, Joseph B. Perry

MagnEsitE is found in 22 California counties, but many of the deposits are too small or too impure to be of commercial value. Several of substantial size and quality were entirely exhausted by wartime operation. At present, three properties comprise the only known workable deposits in the state. Of these, the Western mine and the Patterson mine have been known and worked for many years, and have been described in considerable detail in various publications, therefore need only brief mention here, because of their proximity to the Bald Eagle mine. The latter, recently developed, is unusual in type of ore deposit, plant design and operation, as well as products made, and very little has been written concerning it. WESTERN MINE The Western mine, 32 miles south of Livermore, Calif., was formerly operated by C. S. Maltby. It has been a consistent producer for many years.l The ore is of amorphous variety, occurring along fracture zones in serpentine. The veins vary greatly in width, the average being perhaps 8 ft., with the maximum indicated in one early stope of 40 ft.; 2 ft. is considered the minimum for economical mining. The strike of the veins is predominantly north and south, with dip to the west varying from 40" to 75". Walls are well defined and as a rule firm and easily supported. Veins range in length from a few hundred feet to 1000 or more. Their maximum vertical extent is about 350 ft., but many run less. Early mining consisted of open-cut and glory-hole work on the larger outcrops. This was followed underground by a modified shrinkage system, the waste and low-grade horses being removed by hand sorting on the tramming levels and transported to surface dumps. Filled-stope mining is used now, in order to eliminate the handling of waste, which has

Jan 1, 1942

By Joseph B. Perry, G. M. Kirwan

MagnEsitE is found in 22 California counties, but many of the deposits are too small or too impure to be of commercial value. Several of substantial size and quality were entirely exhausted by wartime operation. At present, three properties comprise the only known workable deposits in the state. Of these, the Western mine and the Patterson mine have been known and worked for many years, and have been described in considerable detail in various publications, therefore need only brief mention here, because of their proximity to the Bald Eagle mine. The latter, recently developed, is unusual in type of ore deposit, plant design and operation, as well as products made, and very little has been written concerning it. WESTERN MINE The Western mine, 32 miles south of Livermore, Calif., was formerly operated by C. S. Maltby. It has been a consistent producer for many years.l The ore is of amorphous variety, occurring along fracture zones in serpentine. The veins vary greatly in width, the average being perhaps 8 ft., with the maximum indicated in one early stope of 40 ft.; 2 ft. is considered the minimum for economical mining. The strike of the veins is predominantly north and south, with dip to the west varying from 40" to 75". Walls are well defined and as a rule firm and easily supported. Veins range in length from a few hundred feet to 1000 or more. Their maximum vertical extent is about 350 ft., but many run less. Early mining consisted of open-cut and glory-hole work on the larger outcrops. This was followed underground by a modified shrinkage system, the waste and low-grade horses being removed by hand sorting on the tramming levels and transported to surface dumps. Filled-stope mining is used now, in order to eliminate the handling of waste, which has

Jan 1, 1942

Joseph Esrey Johnson, Jr., had already achieved rare distinction as an able metallurgist, clear thinker, brilliant author, and wise consulting engineer to bankers and operators; he had achieved the essentials of a great career when death cut short his activities on Apr. 4, 1919, in the forty-ninth year of his age. He belonged to a family of iron blast-furnace men and mine managers. His father, Major J. E. Johnson, after serving with distinction in the Army of the North, identified himself with the iron mines and blast furnace at Longdale, Va., with which he was connected during almost his entire business life. It is significant that, during those troublous times of reconstruction in the South, he enjoyed always the affection and respect of his neighbors and associates alike. From him his son obtained not only a thorough training in blast-furnace practice and iron mining, but great personal courage and force of character. His mother, who survives both her husband and sons, possesses rare intellectuality, humor and a tenderness and human sympathy which those who were privileged to know well J. E. Johnson, Jr., recognized beneath his exterior of aggressiveness and will power. In a recently published analysis of the qualities which characterize the world's great men, three traits stand out preeminently; viz., independence, courage, and intellectuality. Each of these characteristics J. E. Johnson, Jr., possessed in extraordinary degree. His early education was obtained under a private tutor at Longdale, and this circumstance probably enhanced , a natural tendency to independence of character and individuality which, however, under the control of his

Jan 5, 1919

By Robert Anderson

The diffraction of x-rays by cold-worked and heavily polished surfaces of metals gives, no evidence of an amorphous state and typically perfect crystallographic diffraction' patterns are obtained. Severely cold-worked metals, reduced as much as 98 per cent. in area, give true crystallographic diffraction patterns, and polished surfaces of large single crystals of metal give typical crystallographic patterns. The conclusion is drawn, on basis of x-ray evidence, that metals are fragmented on cold work and polishing and not amorphized. THE purpose of this paper is to report evidence, regarding, metal: structures, that is contradictory to the amorphous-metal, hypothesis of Beilby, and particularly evidence that is opposed to the proposition that a vitreous amorphous layer is produced by polishing a piece of metal. According to the theory of Beilby, which has been developed, by Rosenhain and others, polishing a piece of metal greatly affects the condition of the metal at or near the surface polished, making that surface entirely different in character from the metal beneath. A vitreous amorphous surface film is said to be formed. The polishing process, on the basis of Beilby's explanation, is well known-and does not' require discussion here, but it is advisable to seek the precise meaning of,., the term "amorphous." According to Beilby, "amorphous means. Non-crystalline in the most intimate sense of the word'; the molecules are not marshalled in crystalline order and orientation." According to Rosenhain, the amorphous condition is that assumed by a metal when, the .crystalline arrangement is completely broken up so that the atoms exist in a state of disorderly arrangement similar to that ;which exists in the liquid state. Thus, from the point of view of the phase rule, the "amorphous phase" is regarded as being identical with the liquid phase. Amorphous metal is often likened to an undercooled liquid. A crystalline substance is one in which the atoms are arranged in space according to some definite repeating geometrical pattern. The existence of amorphous metal has not been definitely proved.

Jan 1, 1925

By J. A. Wilcox

A NEW LINE of specialists has arisen as a result of the trend toward labor socialization and collectivism in all branches of industry. These men are the ones who will govern the destiny of many companies and the labor policy of our government in coming years. They must be men of integrity and of rather exceptional qualifications; men who can foresee the trend of labor relations with business, and who are willing to sacrifice the immediate fruits of technical training for manual labor and study. They must take their place in industry, not with the idea of following the orthodox line of advancement, but knowing that they must stay at the bottom until they have learned to understand the viewpoints, the work, the advantages and the disadvantages of each classification of labor. They must not be of a radical nature or become easily biased, and they must study. You will say I am looking for a superman and in one sense that is true, but the business man and our government are both in the market even now for this type of man, and with the proper training and background, many of our young technicians can readily enter this field of work.

Jan 1, 1942

By Eugene F. Poncelet

GLASS squares compressed on edge by steel jaws in poor contact with them developed jagged "partial-contact" cracks caused by the formation of local tensile stresses. Compressed by steel jaws in perfect contact, they developed smooth "release cracks" during release of the pressure, caused by the formation of local tensile stresses during the release of the pressure. All these cracks were parallel to the pressure. A Microflash photograph of a disintegrating specimen under sufficient pressure reveals a network of fractures roughly normal to each other, also "release cracks" and a disintegration cloud. The Griffith theory is amended to account for the formation of a first crack. A new theory, based on the theory of thermal agitation and wave propagation, is proposed to account for the progress, velocity and forking of cracks. The network of fractures is shown to have been caused by reflection at a free boundary of pressure pulses emanating from a first crack. Postulating equal distribution of energy in the pulses emitted on either side by a crack in particles, the smaller fragments are shown to continue fracturing preferentially while some of the coarser fragments remain as residual pieces. As comminution of the smaller fragments proceeds, the solid is reduced to a collection of residual particles of smaller and smaller sizes, accounting for the disintegration cloud. EXPERIMENTAL PROCEDURE Apparatus A crushing device was built, consisting of a steel frame and two polished, hardened steel jaws to crush plate-glass samples. This device was placed between the plates of a hydraulic press (Fig. I). For centering the pressure, the upper jaw was guided vertically and provided with a rounded top. Later it was replaced by a steel jaw ground out of a 2 1/2-in. steel ball, the lower surface being ground to an optical flat (Fig. 2). Four rollers were used to eliminate side thrust. Screws and centering blocks served to center the specimen in the crushing device. Hard steel shims placed under the shoulder of the upper jaw limited the "follow through" of the jaw after failure of the specimen. Stress distribution was first examined with a polariscope mounted on an optical bench, using monochromatic light. It was found convenient to mount polaroid, quarter wave and monochromatic plates directly on the device itself. A Microflash unit* was used as light source for the photographs. A gold-paint pattern was fused on the plate-glass specimens and connected into the spark-

Jan 1, 1944