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By E. C. Harder

BAUXITE is known mainly as the ore from which aluminum is smelted but it has large use also in the manufacture of artificial abrasives and as a basis for certain chemical industries. A small amount is used for refractories and for other purposes. COMPOSITION Dana and others give the mineral formula of bauxite as A1203.2H20 and the composition as A12037 73.9 pct; H2O, 26.1 pct. It has been definitely shown, however, that bauxite does not exist as a specific mineral but rather as a rock. The term is now used synonymously with aluminum ore and it embraces gibbsite (hydrargillite or alpha trihydrate), A1203.3H20 (A12037 65.4 pct; H2O, 34.6 pct); boehmite (alpha mono¬hydrate), A1203.H20(Al203) 85 pct; H2O, 15 pct); diaspore (beta monohydrate), A1203.H2O(A12037 85 pct; H2O, 15 pct), and mixtures in various proportions of any two of them. Bauxite of the Mesozoic and Cenozoic in Europe is predominantly a mixture of gibbsite and boehmite, subordinately a mixture of boehmite and diaspore, or gibbsite and diaspore. The bauxite of North and South America, tropical Africa, Asia, and Australasia consists largely of gibbsite. Corundum (A1203) is not included under bauxite, although gradations from bauxite to emery or corundum exist. All bauxite, irrespective of the aluminum minerals composing it, contains certain impurities, including silica, in the form of clay minerals (kaolinite, halloysite, and others) or quartz, iron oxide (as hematite or goethite), titania (as leucoxene or rutile), iron sulphide (as pyrite or marcasite), iron carbonate (siderite), and calcium carbonate (as calcite); the last three mentioned in minor amount and of local occurrence only. Bauxite belongs to a group of partly consolidated materials called laterites, formed by surface weathering. This group includes also impure siliceous and ferruginous bauxite and siliceous and

Jan 1, 1949

By J. O. Brittain, E. Lautenschlager

An investigation was conducted on fine grained airon wire to measure the influence of the temperature of deformation on strain aging near room temperature. Specimens were deformed various amounts at 77°, 195°, or 273°K and aged. The strain aging was followed by either internal friction or return of the yield-point measurements. The results show that strain aging occurs in three stages. During the first stage there is small, almost immediate return of the yield point. The solute carbon concentration, as mesured by internal friction, remains constant in stage I but is lower than the concentration in the unstrained condition. In the second stage, the solute concentration decreases while the magnitude of the yield point increases. In the third stage, the solute atoms continue to drain from the solution, the yield point approaches a maximum, and the strain-hardening coefficient and flow curve increase. The kinetics of the strain aging reaction are not the same for the two sets of measurements since the internal friction results lag behind the yield-point measurements. However, the strain-aging kinetics measured at 44° and 64°C showed no effect due to the difference in initial deformation temperature; nor were the strain aging kinetics influenced by low-temperature anneals at 77°, 195°, and 273°K. 1 HE object of this investigation was to measure the effect of initial deformation temperature on the strain aging of a-iron by tensile tests (i.e., return of the yield point) and internal friction methods, to correlate the results of the two measuring methods, and to measure the effect of low-temperature annealing (<273°K) after low-temperature deformation upon strain aging. The experiments were performed on fine-grained a-iron wire containing 0.02 wt pct c.l According to Thomas and Leak,&apos; return of the yield point and internal friction are similar measures of strain aging since both are dependent on solute atoms leaving the solid solution. The decrease in internal friction as a function of aging time is indicative of the removal of solute atoms from the solid solution, while the return of the yield point as a function of the aging time gives the rate of arrival of solute atoms at the dislocations. According to Cottrell and Bilby,3 during aging the solute atoms create an "atmosphere" which locks the dislocations and causes a return of the yield point on subsequent testing. It has been shown that after low-temperature neutron bombardment, a-iron goes through a stage of recovery at low temperatures which can be attributed to the annealing of iron interstitials&apos; and/or vacancies.4 If, after low-temperature deformation, there is an interaction during a low-temperature anneal between mobile point defects and the solute atoms (i.e., carbon atom interaction with vacancy or iron interstitial), it is possible that some solute atoms will be found at defect sites other than dislocations. Such changes in the sinks for the carbon atoms might be expected to alter the strain-aging kinetics sufficiently to be detected by either inter-

Jan 1, 1962

By E. Parthe, J. P. Pemsler

TWO references can be found in the literature concerning the ternary system uranium-tantalum -carbon. C. H. Schramm, P. Gordon, and A. R. Kaufmam reported in this Journal1 on the existence of the ternary carbide "UTa10C4." They also report a second face-centered-cubic carbide phase in the system U-Ta-C, which they denote as "white" phase. The publication includes a reproduction of a Debye-Scherrer powder photograph of "UTa10C4" and a list of the sin2 0 values of this compound. H. Nowotny, R. Kieffer, F. Benesovsky, and E. Laube2 report the complete solid solubility between TaC and UC with a B1 structure. Since the ternary phase "UTa10C4" lies very close to the binary system Ta-C, and the established phase Ta2C with a C27 structure had not been mentioned by Schramm et al., it was thought worthwhile to compare the patterns of "UTa10C4" with Ta2C. The strong lines of the given pattern were indexed on a hexagonal unit cell with the approximate cell parameters a = 3.09A and c = 4.93A. These are the values reported for Ta2C in the literature.3 The correspondence between reported and calculated sin2 8 values may be studied in columns 4 and 5 of Table I. The agreement is fair, but there remain weak lines which cannot be assigned to the hexagonal unit cell. The extinctions correspond to those of Ta2C, but a comparison of the calculated and observed intensities of the Ta2C lines (columns 2 and 3) with those of the corresponding lines of "UTa10C4" (column 6) show occasional deviations. To clarify this situation, four new samples were prepared. The compositions of these samples were chosen in such a way as to observe any existing ternary phase in the system TaC-UC-U-Ta. The samples were arc melted in an inert atmosphere and annealed at 1100°C for 36 to 72 hr. Compositions of the samples determined by chemical analysis are given along with the results of X-ray investigations in Table 11. The following conclusions may be drawn from these data: a) No ternary compounds occur in the section TaC-UC-U-Ta of the ternary system Ta-U-C. The "white" phase reported by Schramm et al. corresponds to a solid solution between TaC and UC. Only one three-phase field exists: C27-B1-A2. (Both tantalum and ? uranium have body-centered-cubic A2 structures.) The a uranium observed in sample 4 transformed from the high-temperature ? phase on cooling. b) The phase Ta2C with a C27 structure extends into the ternary system. "UTa10C4" is, therefore, a uranium-enriched Ta2C. Good agreement is ob-

Jan 1, 1960

THERE is at least one concrete indication that Soviet Russia&apos;s two most important iron ore producing centers are seriously depleted. While keeping in mind Russia&apos;s penchant for reverse propaganda, one piece of evidence indicates that Magnitugorsk in the southern Urals and Krivoi Rog in the Ukraine have been mined to a point where lower grade ores are being recovered. An article in Pravda, Soviet newspaper, by I. P. Bardin. a Russian metallurgist, says that ore presently mined must undergo an expensive enriching cycle before it can be used in blast furnaces. Com- pounding Russian metallurgical troubles is the low quality of coking coals. High ash and sulphur content typifies the coal Badin talks about. Coal from the Ukraine, Eastern Siberia, Kazakhstan, and the Far East requires extensive treatment before it can be used, according to the article in Pravda.

Jan 7, 1953

By R. E. Zimmerman

Wide attention is being placed upon various methods for cleaning the fine sizes of bituminous coals. The author describes and analyzes the results achieved on wet concentrating tables of modern design on unclassified feeds of —Vz in. particle sizes, including tests on high-sulphur coals. THE increased economic necessity of cleaning the small sizes of coal has forced wide attention upon various methods or processes being used. Although numerous cleaning plants in the past have been cleaning coal smaller than Vz or % in., the large quantities of higher ash fines being produced by mechanical mining and the need for cleaner coal under competitive market conditions have brought about many new installations of fine-coal cleaning plants. Of various methods used, one of the more popular types is the wet concentrating table. Approximately 525 tables have been installed in the United States in the past four years of which 320 have been installed in 20, large new plants. There are now probably 1600 tables of all types in existence in this country for cleaning coal. The purpose of this paper is to describe the cleaning of fine coal by wet concentrating tables. Its scope is confined to a discussion of the theory of tabling and some of the factors entering into tabling action, a description of the Deister SuperDuty diagonal-deck coal table and a discussion of the results of tabling various fine sizes of coals. Al- though tables have been used for cleaning coal as coarse as 2 in. and favorable results are reported, this paper is limited to reporting on the results of cleaning coal fines from 1/2 in. down. Also, although it is well known that the performance of tables is even superior under classified or closely sized feed conditions, this paper concerns itself with the results achieved by tabling unclassified feeds. History of Wet Concentrating Tables The wet concentration of minerals by some form of tabling is quite old, starting originally from fixed, smooth surfaced, tilted boards taking advantage of the laminar flow of liquid films and the separation of minerals according to specific gravity. This was followed by the development of rough deck surfaces

Jan 1, 1951

By R. E. Zimmerman

Wide attention is being placed upon various methods for cleaning the fine sizes of bituminous coals. The author describes and analyzes the results achieved on wet concentrating tables of modern design on unclassified feeds of —Vz in. particle sizes, including tests on high-sulphur coals. THE increased economic necessity of cleaning the small sizes of coal has forced wide attention upon various methods or processes being used. Although numerous cleaning plants in the past have been cleaning coal smaller than Vz or % in., the large quantities of higher ash fines being produced by mechanical mining and the need for cleaner coal under competitive market conditions have brought about many new installations of fine-coal cleaning plants. Of various methods used, one of the more popular types is the wet concentrating table. Approximately 525 tables have been installed in the United States in the past four years of which 320 have been installed in 20, large new plants. There are now probably 1600 tables of all types in existence in this country for cleaning coal. The purpose of this paper is to describe the cleaning of fine coal by wet concentrating tables. Its scope is confined to a discussion of the theory of tabling and some of the factors entering into tabling action, a description of the Deister SuperDuty diagonal-deck coal table and a discussion of the results of tabling various fine sizes of coals. Al- though tables have been used for cleaning coal as coarse as 2 in. and favorable results are reported, this paper is limited to reporting on the results of cleaning coal fines from 1/2 in. down. Also, although it is well known that the performance of tables is even superior under classified or closely sized feed conditions, this paper concerns itself with the results achieved by tabling unclassified feeds. History of Wet Concentrating Tables The wet concentration of minerals by some form of tabling is quite old, starting originally from fixed, smooth surfaced, tilted boards taking advantage of the laminar flow of liquid films and the separation of minerals according to specific gravity. This was followed by the development of rough deck surfaces

Jan 1, 1951

By F. Julius Fohs

A comparative balance sheet for 1924 and 1925 follows: 1925 1924 Barrels Barrels Gross production..................................... 763,000,000 714,000,000 Imports of crude oil.................................. 62,005,000 77,776,000 Imports of refined oil................................. 16,263,000 16,470,000 Total......................................... 841,268,000 808,246,000 Surplus supply....................................... 25,000,000 30,246,000 Indicated domestic demand........................... 704,465,000 667,000,000 Exports crude oil.................................... 13,353,000 17,913,000 Exports of refined oil................................. 98,450,000 93,087,000 Total......................................... 816,268,000 778,000,000 Stocks, Dec. 31 (crude 410,654,000).................... 538,000,000 513,000,000 These figures show an increase of 49,000,000 bbl. in production and little change in oil imported; 37,000,000 bbl. greater apparent domestic consumption and actually greater utility in consumption, due to increased gasoline production by cracking; and 1,000,000 bbl. more crude and refined oil exported in 1925 than 1924, representing a total apparent increased demand of 38,000,000 bbl. The excess of demand over supply in 1925 was 25,000,000 bbl. The increase of stocks over those at the close of 1924 was 25,000,000 bbl. Of the stocks on hand at the close of 1925, about 82,000,000 bbl. in California were not refinable. Imports from Mexico and South America It would not be surprising if, by 1930, we should actually welcome the imports from Mexico, Venezuela, Colombia, Peru, Argentina and Trinidad. If these States produce 155,000,000 bbl. and use, perhaps, 30,000,-

Jan 1, 1927

The Mining Journal Annual Review. The Mining Journal, London. $1.00, 200 pp., 1952.-Contains 70 specially contributed articles reporting on events in the metalliferous mining industry throughout the world during 1951. The articles are written from the standpoints of: Economics, world mining fields, progress reports on Empire mining companies, and British mining taxation. The review has appeared for a period of 20 years. Technical developments in mining, ore treatment, refining, and metallurgy are covered. Dun & Bradstreet Reference Book. Dun & Bradstreet Inc. 4000 pp., 1952. -Changes, brought about by the expanding economy, have been made for the three million listings for the United States and Canada. Planning for the changes started more than 10 years ago. New listings have been included for the metals and mining industries on all levels. The rapid development and specialization of industry have made the old symbols used in previous editions outmoded and a new system is substituted. Atlas of World Mineral Resources, . Edited by William Van Royen and Dr. Oliver Bowles. Prentice-Hall Inc. $10.75, 180 pp., 1952.-Scheduled for publication this fall, the book contains information that has never been published in map form before, as well as much that has not been presented in map form for many years. Facts on 29 minerals most important in world trade are dealt with, along with interpretation of all data available on each mineral, discussion of the world&apos;s mineral economy from viewpoint of specific minerals related to mineral exploration, geographical distribution of world&apos;s consumption, and appraisal of the adequacy of world&apos;s mineral resources.

Jan 1, 1952

By Andre Hubaux

In the writer&apos;s opinion, more stress should be put on field and microscope observations, as J. L. Gillson does. His discovery of relics of big labradorite feldspars from the Marcy anorthosite in all the other rocks is proof enough that previous field observations have been inadequate. The writer&apos;s field experience with anorthositic massifs is limited to the Egersund-Sogndal district in southern Norway; however, this is a very large and well exposed area. It seems to have so many points in common with the Adirondack region that a detailed comparison should be beneficial. This comparison was not possible 20 years ago, owing to the scarcity of geological data, at least for Norway. Both regions are now far better known-the Norway district because of the work of Professors Bugge and Barth33-35 and especially because of the extensive field and microscopic research of P. Michot,36-46 who introduced me in the field to the problems of that region.

Jan 3, 1958

By A. C. Fieldner

THE older coal chemist had a much simpler conception of coal than we have today. To him coal was a mineral composed essentially of carbon, hydrogen, oxygen, nitrogen, sulfur, ash, and water, in various proportions. His studies on the constitution of coal were directed along the conventional lines of proximate and ultimate chemical analyses and making deductions from these data without any real appreciation of the fact that coal is a conglomerate of various chemical compounds, including many of the most complex structures known to organic chemistry. The view of the modern coal chemist is well expressed by Franz Fischer, I who says that while proximate and ultimate analyses are important both from the scientific and technical point of view, they tell the chemist no more concerning the number and kinds of chemical compounds that constitute coal than the reader would learn of the contents of a book if told that the printed contents consisted of 15 per cent. of the letter "e," 5 per cent. of the letter "n," 1 per cent. of the letter "g," 4 per cent. of the letter "b," etc. As the reader must have the grouping of letters into words and words into sentences, so the chemist must have the grouping of atoms into molecules and the proportion of each molecular compound in the coal aggregate before he acquires an adequate knowledge of the constitution of coal. Modern investigators2 are laying the foundation of a new chemistry of coal based on the biochemistry of plants and the chemical changes involved in processes of fermentation and decay. As

Jan 5, 1925

By J. E. Kirby, L. B. Schnitz, H. E. Stamm III

The production history of a gas-cap-drive reservoir was reproduced by calculations, and predictions were made for operations under primary depletion, pressure maintenance by gas injection, and pressure maintenance by water injection. Although the general equations used in this analysis have been available to the industry for a number of years, the procedure has not had extensive use because of the unusually large time requirements for developing numerical results. The use of digital computing equipment for processing the calculation work generally reduced the time usually required for an extensive analysis of this type. Calculation techniques were developed that were equally applicable for solving the gar-cap-drive problem, whether digital computing equipment or desk calculators are used. These techniques are outlined and the procedures are illustrated by the field problem. INTRODUCTION The analysis of a gas-cap-drive res-ervoir requires the simultaneous solution of the volumetric balance1 and displacement2 equations. Equations for the analysis of combination drive reservoirs were presented by Wooddy and Moscrip in a previous paper." These equations permit the evaluation of possible operating processes in order that the optimum method of pro- ducing the reservoir may be determined. Although these equations represent the basic technique known for the detailed analysis of gas-capdrive reservoirs, the calculation processes are quite complex and time consuming; hence, the procedure has not had extensive use. Recently, these equations were satisfactorily applied with the aid of a digital computer to investigate the completion history of a gas-cap-drive reservoir under the following operating methods: primary depletion, depletion under full pressure maintenance by gas injection, and depletion under full pressure maintenance by water injection. The use of digital computing equipment substantially reduced the time necessary for making the computations and permitted a more concise investigation of the reservoir&apos;s depletion history than was possible when the desk calculator was used. This more rigorous investigation also permitted a detailed analysis of the calculation procedures necessary in the solution of the gas-cap-drive problem. This paper outlines the procedure of analyzing a gas-cap-drive reservoir and illustrates the process with an actual field problem. CHARACTERISTICS OF THE RESERVOIR ANALYZED Production in the field under consideration is obtained from a Frio formation of Oligocene age at a depth of approximately 5,740 ft sub-sea. The accumulation, which is bounded on the flanks by strand lines, is semirectangular in shape with gentle narrowing toward the base of the structure as shown by the sand limits and completion map in Fig. 1. The reservoir development indicates an oil column of 319 ft that is defined by gas-oil and oil-water contacts. Basic data relative to the characteristics of the formation and the formation fluids are shown in Table 1. The formation exhibits considerable shaliaess and thinning near the oil-water contact indicating that little or no benefit will be received from natural water influx. This is substantiated by the fact that wells completed near the original oil-water contact have not produced water. A sizeable gas cap is present; however, considerable faulting is in evidence, and it is believed that only a limited portion of the gas cap will aid in oil displacement and pressure maintenance. Although the reservoir was in an initial stage of depletion, it was believed that as soon as the equilibrium gas saturation in the oil zone was exceeded and a number of upstructure wells were invaded by the expanding gas cap, the resulting high gas-oil ratio production would rapidly dissipate the natural drive and lead to limited oil recoveries and inefficient reservoir operation. This analysis evaluated the effectiveness of the primary displacement mechanism and

Jan 1, 1958

By Fred Hellmann

IT IS hardly to be doubted that the opportunity within the grasp of the mine manager for beneficent and helpful action in relation to young engineers seeking employment under him is very broad and very big. It is my experience that a manager usually has a strong inclination to help along those who have chosen the career which he has selected for himself, and to aid them and support them as their steps tread the paths which his own feet have previously followed. He has .a strong sympathy for them in their efforts, he almost yearns to shield them from the mistakes into which he himself fell, and to assist them to avoid the pit-falls of which he knows by bitter experience. Yes, this tendency and inclination is strongly developed in most managers, and they would welcome the opportunity of extending the helping hand, if they knew precisely how best this could be done.

Jan 5, 1923

By T&apos Ke, ing-sui

NUMEROUS investigators have observed that internal friction accompanies cold-working of metals and the effect of annealing is to reduce this internal friction.1,2 However, - most of the experiments were made at high stress amplitudes and the principal purpose was to study the increase of internal friction as a result of the applied cyclic stress during measurement. In order to study the internal friction introduced by cold-working applied prior to the measurement, the stress level applied during the measurement of internal friction must be sufficiently small. The results of measurement are significant and can be used for a base of comparison only when the applied cyclic stress is so small that the internal friction is independent of stress amplitude. Internal friction of cold-worked metals under small stress level has been studied by a number of workers8 -" he internal friction was measured around room temperature with a frequency of vibration of the order of kilocycles per second. The purpose of this paper is to report a study of the change of internal friction when severely cold-worked aluminum was annealed at successively higher temperatures until it was completely recrys-tallized. The measurements of internal friction were made over a range of temperature extending from room temperature up to the temperature of prior anneal. The frequency of vibrations used was about one cycle per second. The apparatus used for the internal friction measurements to be reported in this paper was a torsion pendulum with the specimen in wire form as the suspension fiber. The description of this apparatus and the method of measurement have been previously given.7,8 The applied stress was sufficiently small SO that the magnitude of internal friction is independent of stress level at each temperature range concerned. Corresponding to this stress the maximum shearing strain on the surface of the specimen is of the order of l0-5 and lower. The in- ternal friction (Q-1) is reported as 1/p times the logarithmic decrement. Internal Friction Versus Temperature of Anneal: Fig. 1 shows the internal friction measurements performed upon 99.991 pct aluminum subjected to 95 pct reduction in area. The final diameter of the wire is 0.033 in. This figure gives a general survey of the effect of temperature of anneal and of temperature of measurement. The internal friction of the cold-worked specimen was first measured at room temperature. It was then annealed at 50°C for one hour and the internal friction measured at 50°C and at room temperature. The same wire was successively annealed at higher temperatures for one hour and measurements were taken at the annealing temperatures and lower temperatures as before. Such a procedure was followed in order to stabilize the internal friction at the temperature of measurement so that during the measurement which generally takes about half a minute, there is no detectable change in internal friction. This series of measurements .was made up to 450°C. After each annealing a short test piece of the specimen, which had received the same past thermal and mechanical treatments, was taken out for metallographic examination. It is seen from fig. 1 that up to the annealing temperature of 250°C we have the following observations: for any given temperature of measurement, the internal friction is lower the higher the temperature of prior anneal. When the annealing temperature is 290°C or higher, the internal friction at the annealing temperature drops abruptly to a value which is much smaller than that for the previous curve. Metallographic examinations showed that the recrystallization of the specimen was completed after the annealing at 290°C. Fig. 1 shows that, as far as internal friction is concerned, there is no abrupt transition between the processes of recovery and recrystallization. Averbach has also reached the conclusion that recovery may be a process analogous to recrystallization on the basis of X ray extinction measurements in brass." The effect of annealing temperature upon the internal friction at room temperature is shown by curve I of fig. 2. In this figure the internal friction at room temperature was plotted as a function of annealing temperature. It is seen that the internal friction decreases rapidly at first with an increase

Jan 1, 1951

By Robert Mehl

THE importance of the Widmanstätten structure to structure theory in metallography has been recognized by many writers.1 It is a structure produced by the precipitation of a new phase from a solid solution upon cooling as a result of changing solid solubility, and displays a characteristic appearance indicating a crystallographic relationship between the new phase and the original solid solution (Fig. 1). First discovered in 1808 by Alois de Widmanstätten2, the structure has been traced by analogy through many alloy systems. Particularly is this true of the steels. Sorby&apos;s classic work3 on the microstructure of iron and steel was in essence an attempt to explain the origin of this characteristic structure in meteoric iron. He observed in a Bessemer steel and in a cast-steel ingot structures which we now recognize as typical Widmanstätten figures.4 Osmond5 observed structures in a steel ingot analogous to those found in meteorites. Arnold and McWilliams6 obtained (and recognized) a

Jan 1, 1930

By Franz Wever

The importance of the Widmanstätten structure to structure theory in metallography has been recognized by many writers.l It is a structure produced by the precipitation of a, new phase from a solid solution upon cooling as a result of changing solid solubility, and displays a characteristic appearance indicating a crystallographic relationship between the new phase and the original solid solution (Fig. 1). First discovered in 1808 by Alois de Widmanstätten2, the structure has been traced by analogy through many alloy systems. Particularly is this true of the steels. Sorby&apos;s classic work3 on the microstructure of iron and steel was in essence an attempt to explain the origin of this characteristic structure in meteoric iron. He observed in a Ressemer steel and in a cast-steel ingot structures which we now recognize as typical Widmanstatten figures.4 Osmond Observed structures in a steel ingot analog-ous to those found in meteorites. Arnold and Mc William6 obtained (and recognized) a

Jan 1, 1931

By David A. Wracher

A geologist may produce for himself a surprisingly accurate photo base map and stereo coverage at low cost without the use of expensive equipment and complex photogrammetry. If care is taken and the program well thought out, good results can be expected. The only equipment necessary in this method is a small format (small negative size) camera, a few rolls of film and the appropriate filters. A light aircraft, with an opening in the bottom, is preferable so that the pictures can be taken vertically and from inside - the aircraft. The method will produce high resolution prints at large scales in the range of 1: 1200 to 1:7200.

Jan 11, 1973

By F. E. Bash

PREVIOUS to the war, this country depended on Europe for its supply of a number of alloys of great importance in the manufacture of electrical apparatus and equipment. When this source was cut off shortly after the beginning of hostilities and the small stocks in the United States were exhausted, either inferior substitutes had to be used or the manufacture of the apparatus suspended. Since electrical equipment was of primary importance in the prosecution of the war, the substitutes had to be used until the composition and processes of manufacture of the alloys could be determined. Included among these alloys was one generally known as manganin, which is composed chiefly of copper and manganese and which, beside having a low-temperature coefficient of resistance, has a low thermal electromotive force against copper. These qualities make it valuable for the manufacture of electrical instruments and machines in which it is used in the shape of wire, rod, and strip. As a result of these circumstances, an investigation was started to deter mine how manganin could be made on a commercial basis so that a product of uniform quality and the necessary electrical characteristics could be produced. The object was to procure an alloy with temperature coefficient of resistance not greater than T 1 X 10-5 per ° C. and a thermal e.m.f. against copper no greater than that of the imported material. It is characteristic of manganin that the temperature-resistance curve is not a straight line but has a peak, which varies in position with different samples; it is most desirable, however, to have it at a temperature of 25° C. if possible. The coefficients of manganin from all records available ranged from a large negative to a large positive value. The composition as reported by different authorities is given in Table 1. Prof. Matthew A. Hunter, of Rensselaer Polytechnic Institute, made up a number of small melts of manganin in a graphite crucible and the one that he reported as having the best coefficient gave the following analysis: Copper, 83.6 per cent.; nickel 2.5 per cent.; manganese,-13.6 per cent.; iron, 0.3 per cent. An analysis of a sample of German manganin gave the following: Copper, 82.6 per cent.; nickel, 3.8 per cent.; manganese, 12.8 per cent.; iron 0.7 per cent.

Jan 9, 1919

By P. K. Weimer

Coinpletely integrated thin-film circuits inco?,porating more than 1000 active and passive elements have been fabricated reproducibly in the laboratory by evaporation of- all components. A 180-stage modified shift register comprising 540 CdSe TFT&apos;s, 360 resistovs, and 180 capacitors was deposited upon a glass substrate during one pump-down of the vacuum systeitl. Experimental units have been operated for more than 5000 hr at temperatures uP to 85°C without failure of any slages. The present pupper reviews the charvactevistics of evaporated thin-film transistors (TFT&apos;s) and discusses their application to integrnted circuils. INTEGRATED circuits most widely used today are based upon silicon technology, with the circuits formed on the surface of a block of single-crystal silicon1 or on a block of sapphire 2,3 upon which a thin layer of silicon has been deposited. Transistor patterns and interconnections are defined by photographic procedures using photoresist masking. Large groups of transistors are produced in batches which undergo many processing steps, some of which are carried out at elevated temperatures. Passive elements are formed by treatment of the semiconductor surface or are deposited by evaporation alongside the active elements. The size and complexity of the circuits are limited by defects in the devices and by the size of the available single-crystal chips. Capacitative coupling to the semiconducting substrate may also limit useful size and frequency response of the circuits. An alternative approach to integrated circuits is based upon the deposition by evaporation of all circuit components upon a noncrystalline, insulating substrate such as glass.4 Thin-film field-effect transistors,1&apos;6 known as TFT&apos;s, can be deposited in large arrays on glass or plastic substrates at the same time the associated passive elements are being deposited. Although still in the research stage the all-evaporated approach is expected to offer certain advantages for many applications. In particular, the use of thin films upon a noncrystalline substrate offers the prospect of producing complex, large-area circuits not now feasible with single-crystal silicon. Important applications of this type include memory arrays for computers and imaging devices for television. The ease with which the evaporated TFT&apos;s can be deposited may permit continuous, automated production methods not possible with high-temperature batch processing. Recent advances7&apos;8 in the fabrication of thin-film transistors have led to greatly improved reproduci-bility and life of the TFT&apos;s. Experimental circuits having over 1000 active and passive elements deposited upon a common glass substrate are currently being produced in the laboratory. The present paper reviews recent progress in the development of the TFT and in its application to integrated circuits. I) DESCRIPTION OF THE THIN-FILM FIELD-EFFECT TRANSISTOR The TFT is a field-effect transistor of the type having the control gate separated from the semiconductor by a thin insulating spacer. Although its operation resembles that of the silicon MOS transistorg its construction is based entirely on thin-film techniques. Fig. 1 shows a cross-sectional view of an evaporated TFT deposited upon a glass substrate compared with a silicon MOS transistor deposited upon single-crystal sapphire.3 The semiconductor in the TFT is a poly crystal line layer, of a material which can be readily evaporated, such as cadmium sulfide, cadmium selenide,l0 or tellurium." Silicon monoxide layers have usually served as the gate insulator, but other oxides, sulfides, and fluorides may be used. Film thicknesses range from a few hundred to a few thousand angstroms. The source, drain, and gate electrodes in the TFT are of metal. Qpical source-drain gap dimensions are 0.0003 x 0.030 in., with a gate strip whose width slightly overlaps the source and drain. The source and drain electrodes should make low impedance contacts to the semiconductor. With cadmium sulfide films, gold is a satisfactory material for underlying electrodes, while aluminum is preferable for overlying electrodes.12 Considerable variation in design of the TFT is permissible, with the electrodes being

Jan 1, 1967

By Charles C. Russell

Pressures developed by the coal during the coking process have been responsible for serious trouble to many companies that operate or build by-product coke ovens. The insidious nature of this trouble is indicated by the fact that oven operators, unless they have ascertained the characteristics of the coals they use, cannot determine the existence of dangerous pressures until after the damage has been done. A rather popular misconception is that ease of pushing of the charge at the completion of the coking period indicates that no dangerous pressure has been developed, but this is far from the truth; pressures developed during the coking period are often completely dissipated by the shrinkage of the charge in the completion of coking, and so any criterion based on the ease of pushing is futile. However, methods of testing coals are available that will definitely distinguish the dangerous coals from those that are safe, and such methods have been brought to a high degree of certainty. The operator should take no risk that involves either a lack of knowledge of the behavior of coals during coking or the failure to believe that certain of the coals or coal mixtures can cause damage to the oven structure. This merely tends to minimize the problem and leads to claims that coking coals of all kinds may be carbonized with no danger of damage to the oven structure provided some particular kind of byproduct oven is used. This lack of appreciation of the true situation is in itself one of the main factors leading to damage of coke-oven structures. Coals that develop more than a certain safe pressure cannot be used in by-product coke ovens without causing damage to the side flue walls. The following paper presents a highly certain method for the measurement of the pressures developed during the carbonization of coal—a method that is the culmination of many years of work on the problem in which a number of methods for the purpose were investigated and used. While actual pressures found may appear to be small when expressed in pounds per square inch, the number of square inches in each oven wall is so large that the total pressure on the oven wall becomes an enormous load.

Jan 1, 1940

By Charles C. Russell

Pressures developed by the coal during the coking process have been responsible for serious trouble to many companies that operate or build by-product coke ovens. The insidious nature of this trouble is indicated by the fact that oven operators, unless they have ascertained the characteristics of the coals they use, cannot determine the existence of dangerous pressures until after the damage has been done. A rather popular misconception is that ease of pushing of the charge at the completion of the coking period indicates that no dangerous pressure has been developed, but this is far from the truth; pressures developed during the coking period are often completely dissipated by the shrinkage of the charge in the completion of coking, and so any criterion based on the ease of pushing is futile. However, methods of testing coals are available that will definitely distinguish the dangerous coals from those that are safe, and such methods have been brought to a high degree of certainty. The operator should take no risk that involves either a lack of knowledge of the behavior of coals during coking or the failure to believe that certain of the coals or coal mixtures can cause damage to the oven structure. This merely tends to minimize the problem and leads to claims that coking coals of all kinds may be carbonized with no danger of damage to the oven structure provided some particular kind of byproduct oven is used. This lack of appreciation of the true situation is in itself one of the main factors leading to damage of coke-oven structures. Coals that develop more than a certain safe pressure cannot be used in by-product coke ovens without causing damage to the side flue walls. The following paper presents a highly certain method for the measurement of the pressures developed during the carbonization of coal—a method that is the culmination of many years of work on the problem in which a number of methods for the purpose were investigated and used. While actual pressures found may appear to be small when expressed in pounds per square inch, the number of square inches in each oven wall is so large that the total pressure on the oven wall becomes an enormous load.

Jan 1, 1940