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By G. Sachs, G. Espey

Simple methods can be used for the determination of the residual stresses in thin walled tubing if the stresses consist of high tensile stresses at the one surface and high compressive stresses at the other surface. Such a stress distribution is approximated in sunk tubing and in deep-drawn shells. It is possible to cut sections from such articles in such a manner that a major part of the residual stress is relieved by a bending of the Part that is separated from the adjacent metal. The circumferential stress is evaluated from the change in diameter D, occurring on splitting a length of tubing (Fig. Ib) or from deflection resulting from the cutting out of a circumferential tongue (Fig. Ia) .6 The bending moment M released by such a flexure is. M - EI (I-I) = EI R1-R0 I - u2(R0-R1) I -V2 R0XR1 where E = modulus of elasticity, v = Poisson's ratio, I = moment of inertia of the section, R0 =. mean radius before splitting, R1 = mean radius after splitting. The release of this bending moment corresponds to the release of stresses, which, in a thin section, vary linearly from one surface to the other, and have the following value in a particular fiber a certain distance (x) from the surface: S = c d I - V2 x c x d 2 2 RI - R0____E (d ) R1 - R0 X R0 X R1 ~ i - u2 (2 x) Ro X R1 where C is the section modulus and d is the thickness of the section, the ratio M:C being d: 2 for a rectallgular section.* The maximum stress values at the surfaces are. Smax = +E X d X R1-R0 I — u2- 2 R0 X R1 For most purposes the simpler equations: EXd AD1 = ± I - u2 x dm2 and will be satisfactory, where D,, is the aver. age of the mean diameters of the tubing

Jan 1, 1942

By L. D. Fetterolf

The New Jersey Zinc Zompany operates at Depue, Illinois, an integrated zinc smelting plant using tie vertical retort reduction process. The overall operation comprises green concentrate roasting, sintering, vertical retort smelting and metal refining. In the roasting operation, the fine concentrate is pelletized, the dried pellets fluidized and autogenously roasted with air in a “fluid column” with minimal formation of dust requiring recirculation. The roasted pellets and any associated roaster dust are agglomerated in a rotating drum and laid down, in combination with coal for fuel, on a Dwight-Lloyd sintering machine which converts to a semi-fused mass - a physical state more suitable for vertical retort smelting. The smeltins plant of 27 vertical retorts rated at 8 T zinc each per day on average requires the following major processing steps - mix preparation and briquettine, briquet coking, vertical retort reduction, vapor condensation and slab casting of metal. A portion of zinc production is converted to 99.99+ percent purity by boiling and fractional distillation in columns consisting of externally heated, superimposed trays of high-conductivity refractory.

Jan 1, 1970

By N. V. Hansell

The last few years have shown an increasing interest in the subject of beneficiating iron-ores in all iron-producing countries. In the United States, this movement has been slower than in certain parts of Europe, for the obvious reason that the abundance and relative cheapness of the Lake Superior irou-ores has hindered the development of enterprises for the preparation of low-grade ores. Gradually, however, conditions have changed. The world's consumption of iron is increasing enormously. Being in 1900 about 40,000,000 tons, in 1910 it was already 60,000,000; and there is no reason to doubt that for the near future the increase in iron-cousumption mill continue at the same rapid rate, especially with the development of China, certain parts of Africa, and other regions which have hardly been touched as yet by modern industrialism. It is, therefore, not surprising that apprehension is felt that the known available iron-ore resources of the world are gradually being depleted. Signs of this feeling are the recent iuvestigation, under the direction of the U. S. Geological Survey, of the iron-ore resources of the United States, and the estimate presented to the last International Geological Congress, at Stockholm, Sweden, of the iron-ore resources of the world. These investigations have emphasized the fact that the known high-grade ore-deposits are limited in extent, and will, at a not distant future, be exhausted, compelling the iron industry to depend for raw material on the enormous deposits of low-gratle ores which are distributed over almost all the world. The discovery of new deposits of high-grade ore, in countries not yet thoroughly explored, will not materially change this prospect. Of course, the part which such new deposits will play in the future cannot be forecast. The difficulty and cost of transportation will probably exclude many of them from use at the present centers of the iron industry.

Jan 1, 1913

By T. V. Moore

DURING 1910, crude-oil production in the United States reached a record level averaging about 3.700,000 barrels daily. Export declined sharply while imports increased with the result that large quantities of crude oil were run to storage during the year. Imports consisted largely of residual fuel oil brought in from South America bit because of a shortage of that product in this country and of Mexican crude. The price of petroleum products followed the declining trend of the last three year resulting in serious disparity between crude and product prices. This condition was aggravated in some areas by the increasing production of distillate by recycling operations and by the high tanker rates prevalent in the last two months of the year. As a result two small purchasers found it necessary to reduce crude-oil price in the Corpus Christie area of Texas.

Jan 1, 1941

W. H. Blauvelt, New York, N. Y.—One thought lias been running through my mind during the wholc of this meeting and that is that the scientific and the practical men must recognize very clearly their interdependence. The value of scientific classification of coal is going to be of the very greatest importance to the users, the practical men. Is not the scientific investigation and the great amount of work that is being done in a measure at least lost to the world? Therefore the scientific investigations and the practical needs of the users should bo brought as close together, and the work should be done as closely together, as possible; that is, the scientific man should know what the practical man needs, and the practical man should not feel that the scientific man is merely a theorist. Scientific investigation is going to have a great effeet and be of great valuc to the practical man who is trying to solve his problems. In the subject which I discussed' for instance, we must look to the scientific man to tell us why coal cokes in one way and not In another and why certain coals will do certain things and others, which appear on the surfacc to be generally similar, do not act in the same way. Need or Physical Data on Coal H. J. Rose, Pittsburgh, Pa.—There is a subject which is a sort of hobby of mine; that is, the need for what might be called critical tables of constants for coal. The chemist has big volumes giving constants, such as the density, solubility, specific heat, thermal conductivity and all other physical and chemical data that have been determined for chemical compounds. Data arc also available on many common materials, for example, the density, hardness, modulus of rupture or maximum crushing strength of swamp white oak as compared with some other wood. In fact, physical data for practically cvery hype of wood commercially produced in the world can he found. In the same way the metallurgical man has handbooks giving the properties of alloys, etc., but we havc very little tabulated information about coal. Our principal reference works are the volumes published by the U. S. Bureau of Mines on the proximatc and ultimate analysis and calorific values of coals of the United States. That is 3 pioncer work of enormous value, but we have reached the point where we need more diversified information. Mr. Fulweiler raised the question of the relative strength of the different coals and cokes. Dr. Campbell and Dr. Ashley wanted to have some information on the resistance of coal to air slacking. It was brought out in the discussion that we want to know something about the coking properties of coal. There are any number of physical tests that we need, such as the thermal conductivity of certain coals, the coefficient of expansion, or the coefficient of friction; or other constants. A smattering of such information is scattered through the literature; for instance, a research worker in Wales will report a coefficient of expansion on Wclsh coals and one in South Africa will report something else for one or two kinds of African coals, hut it is difficult to find the information that is needed on our own coals. Would it not be worth while to consider collecting reliable critical

Jan 1, 1930

By H. E. Doerr

The writer has been unable to find much information relative to tests made to determine the effect of forging on the specific density of steel. The opinion, however, among men engaged in the business, seems to be that forging greatly compresses or consolidates the steel. While such is doubtless the case with spongy or porous steel, the following experiments indicate that there can be little or no change in the density with steel initially free from cavities. Ten ingots of basic open-hearth steel cast as shown in Fig. 1 were used in the experiments. All the specimens were 0.53 carbon with all other elements the same, the analysis being determined from drillings taken midway between the center and outside of the upper end, as shown in Fig. 2. The specimens were selected from over one thousand ingots so that the tests could be comparative for the work done in forging only, but no two of the ingots were cast in the same heat. Each ingot remained in the mold approximately 30 min., when it was removed and sir-cooled. About 12 hr. later, when the temperature had been reduced to approximately that of the surrounding atmosphere, the head was discarded and the ingot heated in an oil furnace to approximately 2250" F. (1235" C). Approximately 1 min. was required to forge under the steam hammer to 1 1/4 in. (31.75 mm.), rough diameter, as shown by the dotted lines in Fig. 2. All ingots were allowed to air-cool after forging. Cylinders 1/2 in. (17.7 mm.) in diameter and 1/2 in. high were then turned from the forged and unforged parts of the ingots and numbered. The ten pairs of specimens were submitted to Louis E. Endsley, Professor of Railway Mechanical Engineering, University of Pittsburgh; A. N. Talbot, Professor of Applied Mechanics, University of Illinois; L. Z. Slater, chief chemist, Scullin Steel Co., St. Louis, Mo. NO information was furnished as to which specimens were forged or unforged and each laboratory used the same specimens, submitting the average of three independent determinations, a tabulation of which is shown in the accompanying table in which the laboratories are designated by the letters A, B, and C. While there is considerable difference in the individual determinations for a number of the specimens, the averages

Jan 1, 1920

By E. G. Williams

Conveyors were first used underground at Miami Copper Co., in the latter part of 1947. At that time some of the stoping area was too heavy and too close to the haulage level to use conventional haulage. To get the haulage drifts out from under the stoping area belt conveyors were used for the additional lateral transfer. Since 1947 more than 8 million tons have been mined in this manner, with as many as four belt type stopes in production at one time. When the mining plan for the new low grade was worked out, it was decided to use belts on what otherwise would have been short train haulage transfers to move the ore laterally to centrally located concrete ore passes. One group of these stopes has grizzly levels on the 570, with a belt level on the 670; the other group has grizzly levels on the 720 and belt levels on the 820, with the concrete ore passes bottoming on the 1000, or the existing train haulage level.

Jul 1, 1956

By John H. Bassarear, Harold W. Sorstokke

The never ending search for lower unit costs led Pima Min- ing Company's management to study various alternatives shortly after Expansion III was completed. A considerable amount of ore as- saying 0.35% copper had to be moved to maintain mill feed at the desired 0.54 % copper content, which is the overall grade of the ore reserves. Detailed investigations revealed that for a period of 8-10 yr, about 14,000 tpd of 0.30- 0.40% copper ore pass the crusher enroute to the low grade stockpile. This ore is very hard, very clean and has to be mined at a uniform rate. A six month pilot plant run testing autogenous and semi-autogenous grinding gave encouraging results. Since no mining costs need to be charged to the extra tonnage (it had to be mined anyway), the major costs would be against milling. The decision to proceed was made in August 1970. Fluor-Utah was retained as the prime design construction contractor. Ore was put through the new mill on December 29, 1971. By March of 1972 design tonnage

Jan 5, 1973

By Francois E. Heuze

INTRODUCTION Rock slope stability typically is governed by the geological discontinuities. This stability can be improved by drainage, unloading, adjustment in slope orientation, adjustment in slope angle, and also by reinforcement such as bolts or tendons. This paper addresses the modeling of bolt reinforcement in rock slopes. Most geological discontinuities such as joints have rough surfaces; they dilate during shear displacement. Their shear strength is characterized by two envelopes (Fig. 1); the peak envelope is distinct from the residual envelope when the joints can dilate. If the dilation is restrained transversely, such as with bolts, the normal stress will increase and the joint strength also will increase. It has been demonstrated that this increase may be considerable (Obert et al., 1976). The new normal stress at peak strength is a com- posite function of the properties of the rock mass and of the steel (Heuze, 1979). Hence, the dilation and its resultant effects on joint shear strength must be included in the analysis and design of the reinforcement. We present a model which can be used to perform such an analysis. Early studies of rock reinforcement in mining and civil applications (Lang, 1957 - Panek, 1962 - Osen and Parsons, 1966 - Lang, 19721, did not consider the specific effects of bolts on joint shear strength. In 1973, Heuze and Goodman reported direct shear tests on rough sandstone joints with bolts perpendicular to the joint plane (Fig. 2). The peak shear strength of such joints was greatly in excess of the shear strength of the unbolted joints. The excess

Jan 1, 1983

By L. H. Sjodahl, J. B. Conway

of each particle on grain boundary movement is proportional to the area it occupies on the grain boundary and this increases with the square of the particle radius. In contrast to the impression gained by Tiwari the effectiveness of a particle, as a grain boundary obstacle, increases rapidly as the particle size increases. The counterbalancing factor in a dispersion of constant volume (e.g., those considered by Zener) is of course the rapidly diminishing number of particles, a situation which does not exist in thoria dispersed materials where the volume fraction of thoria remains constant. Although it has been assumed that the Zener approach is valid for the sake of the above argument, it is open to the following objections: 1) It assumes that the effect of many small particles along a grain boundary is cumulative and does not take into account the possibility of each small particle being overcome separately. In this case the boundary will not be able to move forward until the largest particle on the boundary has been overcome. This means that the rate controlling factor will be the rate at which a few relatively large particles are overcome with the remaining small particles playing a negligible role. 2) When the dispersion consists of very small particles the interparticle spacing is usually small compared to the grain size and most particles are located away from grain boundaries where they can play no part. The most efficient dispersion, from a purely geometrical viewpoint, is one where the particle spacing is equal to the grain size so that all the particles are on grain boundaries. Tiwari's second point that voids cannot prevent re-crystallization seems to be unfounded as several workes20-23 have shown that voids alone can retard grain boundary movement and recrystallization. To further convince Tiwari, Fig. 17 shows a void in deformed TD Nichrome holding back a recrystallization interface. Tiwari's explanation for the effect of voids on recrystallization, i.e., they reduce local strain energy and hence lower the driving force for recrystallization may be valid in itself but is irrelevant to the present case where even complete recrystallization after ONE of the more recently proposed expressions for describing stress-strain behavior is that due to Voce.1,2 This equation is usually written: s =s8 ?(s8?so)e??/?c [l] where s is the true stress, ? is true strain, cC is a constant called the characteristic strain, s8 is the asymptotic stress approached at high strain values, and so is the threshold stress at which the plastic deformation begins. While this expression has not been universally accepted as yet it does contain certain features which are consistent with experimental stress-strain behavior. In a more recent publication Hsu, Davies, and Royles3 employed the concept of generalized strain proposed by seth4 and identified a method for linearizing the stress-strain plot. In this approach the generalized strain was given by: where 7 is the generalized strain, 1 is the instantaneous length, 1, the datum length, and n is a constant called the "coefficient of strain measure". A value of n was said to exist which would yield the linearity: s —s+ S[.-(tf] [3] In recent studies of both these approaches, it has been found that while the Voce equation and the gen-

Jan 1, 1970

By G. R. Fritterer

Investigators in the field of temperature measurement have long sought a thermoelectric couple fulfilling the following requirements: 1. It should be useful up to and including high industrial temperatures; i. e., 1000 to 1800 C. 2. Its thermoelectric variation with temperature should be linear and be maintained after heating to high temperatures for long periods of time. 3. It should be reproducible; i. e., different couples of the same elements should have similar calibration curves. 4. Its thermoelectric power should be large so as to allow the industrial use of rugged recording instruments. 5. Chemical reactions with, and physical changes within the elements of the couple should not alter its calibration. No thermocouple proposed to date exhibits simultaneously all of these characteristics, whereas the couple about to be described fulfills all requirements to a satisfactory degree. New Thermoelectric Materials A thorough survey of the literature on thermoelectricity revealed that present-day thermocouples could not meet the specifications mentioned above because their thermoelements are metallic. Metals have a marked tendency to deteriorate chemically and their melting points limit their use to low temperatures. Refractory substances, however, are usually resistant to chemical attack and are quite stable at high temperatures. Hence a survey of refractory substances having thermoelectric possibilities was made. One class of thermocouples considered was that in which carbon and a carbide of some metal or nonmetal were the thermoelements. Previous investigators neglected to study this field but certain recommendations were made by them for the use of couples in which carbon served as one element. These proposals are listed in Table 1. The couples suggested are unsatisfactory because of their low thermoelectric powers, the low melting points of their metallic elements, etc. The

Jan 1, 1933

By E. E. ELLIS

THE zinc deposits under development by the Universal Exploration Co., a subsidiary of the United States Steel Corporation, are close to Jefferson City, Tenn., a small town about 30 miles northeast of Knoxville, Tenn., and are served by the Southern Railway. The first zinc mining in this district was in the old Mossy Creek mine at the north edge of the town, opened for oxidized ores in 1871 and later worked for sulfide ores. An oxidized zinc ore deposit (carbonates and silicates) was opened near New Market in 1900 and worked through the war period by the G1'8sselli Chemical Co., producing around 25,000 tons of oxidized ore. In recent years a sulfide deposit has been found and developed but is not producing. About 1% miles south of this a small body of sulfide ore was developed by open cut, but the operation was unsuccessful. The Universal Exploration Co. entered the district in 1926 and, after extensive exploration, has been operating an oxidized ore-body since Janual:y, 1928, and has been developing a sulfide ore body since July, 1928.

Jan 1, 1929

The week of Sept. 22, will be a week of convocation of societies in Chicago with the exposition of Chemical industries. The American. Institute of Mining and Metallurgical Engineers will occupy the stage for most of the week, American Ceramic Society meets on Wednesday, the American Electrochemical Society on Thursday, Friday, and Saturday, and the Technical Association of Pulp and Paper Industry from Wednesday to Saturday. There will also be a symposium upon Safety in the Plant and Mine under the chairmanship of M. L. Leopold, Safety Engineer of the U. S. Bureau of Mines, and in the evening after this sleeting-which will occupy an entire afternoon-there will be shown a series of motion pictures of safety work in plant, field-and mine. The motion picture program will consist almost entirely of films now being made. Even in motion pictures, the Exposition is outstanding as the place of introduction to the public of the newest and most recent developments. Each improvement of the projectoscope in motion-picture projection has been reserved for first public demonstration at the Exposition. Mention cannot be made of the new exhibits that are engaged for the Exposition, other than to say that the electric furnace will be in operation. These will give, probably for the first time, men of science an opportunity to see and compare the various designs and judge them for the various work to which they are applicable.

Jan 8, 1919

By G. F. Comstock

H. M. BOYLSTON, Cambridge, Mass.-It might be asked, since this test is so simple, why it was not discovered before. It seems to me the explanation is that when we have used the sodium picrate solution, it has .generally been on a very, high-carbon or hypereutectoid steel; to detect . the presence of free cementite, and when we have looked for sulphides, it

Jan 4, 1917

By J. Nagy, D. W. Mitchell, E. M. Murphy

In 1957 research was initiated in the U.S. Bureau of Mines experimental coal mine near Pittsburgh, Pa., to study factors affecting foam generation and transport, to evaluate the effectiveness of high-expansion foam for controlling mine fires, and to develop techniques for applying the method under U.S. mining conditions. These investigations showed that high-expansion foam containing at least 0.2 oz of water per cu ft of foam is effective in controlling experimental underground fires burning coal, wood, and oil. Sometimes the fire was completely extinguished, but more often, it was brought under sufficient control to permit either a direct attack on the fire with a stream of water or loading of the hot material into cars. A progress report' prepared in July 1958 summarized the initial achievements of the USBM experiments. Since then other phases of the foam-plug method for attacking fires have been studied in the laboratory and in the mine. Previous studies by British engineers' of the foam-plug method for fighting mine fires indicated that high-expansion foam was effective in controlling experimental timber fires in an underground passageway. Their subsequent workx-1 pertained to the practical aspects of fighting large fires within a mining area with a foam-plug. CONTROLLING EXPERIMENTAL FIRES In the USBM tests foam was formed by spraying a dilute solution of a foaming agent on a metal or cotton net of 1/8 to 1/4-in. mesh. Air passing through the continuously wetted net forms bubbles of 1/2 to 11/2-in. diam and produces a honeycomb of foam that fills the passageway. Under the ventilating-air pressure, this light-weight plug moves forward through the passageways, around sharp corners, and over obstacles. as illustrated in Fig. 1. High-expansion foam was transported to a wood fire, an oil fire, and 13 coal fires. Figs. 3 and 4 show a typical coal fire before and after attack with foam. In 12 of the 15 experiments the fire was brought under control when the water content of foam was 0.2 oz or more per cu ft. A fire was considered controlled when the flames were quenched and observers could cross the area without wearing breathing apparatus or protective clothing. In the other three experiments, conducted when the water content was less than 0.2 oz per cu ft of foam, the flames were retarded but the fire was not controlled. Coal fires have been attacked successfully by foam introduced at points varying from 155 to 1010 ft from the fire. The time of burning in coal beds 10 in. thick ranged from 11/2 to 5 hrs or more. Most of the experimental fire beds were 15 ft in length. However, in one experiment a floor fire 25 ft long and 5 ft wide was constructed $5 upwind from another fire 15 ft in length; in another instance, the fire was 100 ft long and 5 ft wide. Foam was applied to the fires for periods ranging from 7 to 36 min. The time required for foam application depends on the extent of the fire, time of burning, water content of foam, foam velocity, and degree of fire control desired. In addition to the coal fires, foam was transported to a fire covering 45 sq ft, produced by 15 gal of oil burning in metal trays on the floor. The foam extinguished the oil fire in about 1 min. In one other test, the burning of 1100 lb of dry sawmill slabs stacked in open cribs 4 ft high and 16 ft long was brought under control by foam in 2 min. Composition of Gases in Return Air: In several of the experiments samples of the return air from fire zones were collected; composition of the atmosphere before, during, and after foam application was then determined. Because of condensation in the relatively cool sampling tube, the amount of water vapor was not determined. Analyses showed that concentration of carbon dioxide and combustible gases increased as the foam began passing over the fire. This resulted from the decrease in the volume of air when foam generation started and from the formation of gases when water reached the fire.* The quantity of gases generated would not be greater than that from an equivalent amount of water applied directly to the fire. The highest total concentration of combustibles (CO, CH1, and H2 mixture) obtained during the experiment was about 2 pct; this occurred 6 min after foam reached the fire. This atmosphere was nonex-plosive, but calculations show that if the air flow were reduced to about 5 fpm and if the rate of gas liberation from the fire remained constant, the mixture would be explosive. The use of foam on a fire in all probability would affect the normal ventilation of a mine. If the mine is gassy, this factor must be carefully considered before the foam is applied. APPLICATION OF THE FOAM-PLUG TECHNIQUE IN MINES Equipment and procedures for applying the foam-plug methods must be adapted to the prevailing conditions at a particular mine. Some factors to be considered in developing equipment are: size or extent of the mine, dimensions and number of entries, ventilation system, mining methods, haulage facilities, availability of water, amount of methane liberated, and existing fire-control apparatus. • In most experiments the initial air velocity of 200 fpm decreased to 50 to 100 fpm as the foam plug increased In length.

Jan 1, 1961

By AIME AIME

WHEN the present Chairman of the Coal Division, A.I.M.E. applied for membership in the Institute 28 years ago one of his endorsers was Howard N. Eavenson, with whom he has now been associated as a partner in a Pittsburgh consulting coal - mining engineering firm for 22 years. Back of that association was some ten years of operating work in Kentucky. Mr. Alford was born in Philadelphia on Dec. 11, 1887, and was educated in Quaker schools, graduating from Swarthmore with an A.B. in 1909, later receiving a B.S. and an E.M. from the University of Pittsburgh. In the summers of 1907 and 1908 he had his first taste of coal mining as a chainman for the U. S. Coal and Coke Co. in Gary, W. Va. Upon graduating in 1909 he got a job on the by-product coke ovens of the Illinois Steel Co. at Joliet, Ill., but a year later went to Kentucky as superintendent of the Shamrock mine of the St. Bernard Mining Co., by which company he was employed for the next ten years. Successively he was assistant chief engineer, chief engineer, and assistant to the president. His duties were varied, including all the engineering duties commonly associated with coal mining, both underground and on the surface, construction of washing plants, prospecting, reports on new properties, power plants, safety work, and labor relations.

Jan 1, 1942

By M. E. Lombardi

THE Coalinga oil field is located on the west side of the San Joaquin Valley, California. The structure is in general a monocline, the edges of the oil horizon resting on the foot hills and dipping gently toward the east. One prominent anticline occurs plunging southeast. The earlier drilling was done in the foot hills comparatively near the outcrop and the wells were shallow. The sands were followed eastward and, in the case of the anticline, along the plunge, the wells becoming deeper and deeper until the depth of 4,000 ft. was reached and passed. There is nothing to show that the oil will not be found in quantity at still greater depth. In fact, some of the best producers have tapped the sand at close to 4,000 ft. The recovery of oil still farther to the east, and therefore at greater depth, seems to be mainly a question of drilling. In this territory the formations drilled through are chiefly sands and shales; they will not "stand up" in an open drilling hole; the casing has to be carried close to the bit, and it is always difficult to keep the casing free for any considerable distance. Ability to carry casing of comparatively large diameter without conductor pipes for distances of 2,000 or 3,000 ft. or over is desirable in such territory chiefly for two reasons. It makes it possible to enter the oil sand with a pipe of ample diameter; it eliminates one or more expensive strings of casing which act only as conductors for the water string, and furthermore, in territory where waters are encountered which corrode steel rapidly, it makes possible the construction of a rust- and alkali-resisting water string. It is always desirable to shut off top waters, which may lie within 100 ft. or less of the oil sand, with 10-in. pipe. Where the depth is so great that a practical weight of 10-in. pipe will not withstand the probable collapsing pressures, 8 ¼ in. at least is desirable. About the limit of rotary drilling to date in California seems to be the setting of the 10-in. string at 3,200 ft., although the rapid advance in rotary work during the past year seems to indicate that this depth may soon be increased. It is my purpose now, however, to treat only of cable-tool drilling.

Jan 2, 1915

By AIME AIME

MEMBERS of the Engineering Education Committee held two meetings at Joplin preliminary to the opening of the main meeting there. The first was held on Sunday afternoon. It was attended by all who had arrived early enough and as among the dozen or' fifteen who were present the heads of a half dozen schools of mines were included it was a representative gathering. C: H. Fulton, chairman of the Committee presided and T. T. Read acted as secretary of the meeting. The chair., man reminded those present that last year there had been some discussion as to the advisability of the proposal, made by Edward Steidle, that a, separate society, devoted to education in the mineral industry, he organized. Many .people had felt that there are already so many societies in existence to demand one's time and attention, that it would be a mistake to add to their number and the counter suggestion had been made that the work of this committee could be so reorganized as to meet all the needs that a separate society could fill. He therefore presented for discussion these four' questions: (1) Shall a subcommittee .be appointed to study, and report in February, 1932, the possibility of the reorganization of the work of the Engineering Education Committee into the equivalent of an' Institute division; (2) if the work is so reorganized what shall be the relation of the work of the Committee (division) to the work of the-Society for the Promotion of Engineering Education; (3.): what are the, cardinal objectives of education for the mineral industry; and (4) what should be done as regards the movement in some institutions to plan their work-in the light of that being done in other institutions, for example, in geophysics?

Jan 1, 1931

L. D. Ricketts, New York, N. Y.-In recent years the metallurgical field of the copper industry has expanded greatly, the copper ores have become lean and diverse in character, and we are obliged to treat such ores on a very large scale. On the commercial side, the operating and consulting staffs of ,the great mining companies have been enlarged and organized, and no great capital expenditure is decided upon until it has been investigated and recommended by a highly organized force of specialists as a committee. I believe that in the scientific field and in the most valuable proceedings of our various societies the old idea of one-man point of view and one-man treatment of principle and detail together has been. splendidly developed and should continue, but for the advancement of our art we should deliberately discuss subjects among ourselves in order to do away with the idiosyncrasies of the individual and to gain a composite view representing the best thought of many men. In the development of new ideas leading to the introduction of new methods, the societies could enlarge their present great field of usefulness if such discussion be had, and in my opinion further great good could be done if a number of men of different qualifications and experience would join in preparing a joint book, each dealing with his particular problem, but consulting the other men. In this way individualism would be preserved and various processes would be described, and if properly reviewed the paper would be palpably capable of analysis, and the student would have at his command the associated efforts of a group of qualified engineers.

Jan 4, 1915

By N. J. Grant, D. S. Bloom

THE development of high temperature, high stress alloys had proceeded with such rapidity during the war, and for a short time afterward, that our knowledge of the constitution of the alloys had become seriously inadequate. To interpret correctly alloy behavior it is not only necessary to recognize the phases present, but also to know the properties of the phases under all varieties of conditions and treatments. Chromium in these high temperature alloys holds the unique distinction of being the only one element which must be present when an oxidizing or generally corrosive atmosphere is present and when a long life is desired in service. Carbon and nitrogen must also be considered where chromium is present. Carbon is always present, either as an impurity in the raw alloying elements, or as a deliberate addition agent to increase the strength. Nitrogen is generally picked up from the atmosphere during melting or may be added as an alloying element. The effect of nitrogen additions is not too dissimilar to that of carbon additions. As such, chromium carbides and nitrides become of great interest since they are present in a very large number of alloys, including alloy steels, stainless steels, super alloys, and the like. In the chromium-carbon system there are three accepted, carbides: Cr,C, Cr7C8, and Cr3C2. The existence of one more carbide, a still higher carbon form CrC, has been advanced. The phase diagrams of chromium and carbon as published by Friemann and Sauerwald² and by Tofaute, Kuttner and But- tinghaus³ -do not extend beyond the carbide Cr3C2, which contains 13.3 pct carbon; but Hatsuta has extended the diagram up to 20 pct carbon, and in doing so hypothesized, with the use of some questionable experimental results, the compound CrC. This carbide would contain 18.75 pct carbon, 81.25 pct chromium, by weight. It is further known that as the chromium carbides increase in carbon the acid resistance increases but the oxidation resistance decreases4,5 This is of great importance in high temperature alloys where time-temperature stability, as well as oxidation resistance, is of prime importance. The possible existence of a carbide of the formula CrC thus becomes of prime importance and it was considered important to recheck the chromium-carbon binary constitutional diagram for such a compound. In view of the wide spread of values listed for the melting point of chromium (1500° to 1850°C) and 1930°C8, it was considered .that the liquidus temperatures might well be redetermined more ac-

Jan 1, 1951