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By Leonard Greenburg, William B. Harris, Gustäv Werner

HAULAGE in tunneling operations generally has been done with electric locomotives. As a rule, on short hauls the source of electricity is a storage battery mounted on the locomotive, which, of course, must be removed and recharged periodically. Where the distance from the recharging point to the tunnel face is very long, and where loads are heavy, trolley-driven locomotives are used. Diesel engines have been used in mining and tunneling operations in Europe for a number of years. The recent reports of studies in Belgium1 and by the Bureau of Mines in this country2-4 have indicated the potentialities of this form of power for haulage, mucking, bulldozing and many other underground operations. The hazards attending the use of Diesel engines in more or less closed spaces have long been known. The exhaust constituents that may create a harmful or objectionable environment are carbon monoxide, oxides of nitrogen and sulphur, carbon dioxide, aldehydes and smoke. Lack of precise information regarding the concentration of these gases and the ventilation requirements to reduce them to safe levels has to some extent suppressed their general acceptance in tunneling and mining work. Not until the work of the Bureau of Mines referred to above, and certain experience gained in the construction of the Delaware Aqueduct,‡ has there been available the requisite information regarding the conditions under which their use may be permitted. This paper concerns itself with the successful operation of Diesel engines underground in the construction of certain parts of the Delaware Aqueduct, and describes the conditions under which Diesel engines have been found to operate with a minimum production of noxious gases. The test data reported were obtained during the operation of Diesel engines over a period of two years.* STUDIES BY THE NEW YORK STATE DEPARTMENT OF LABOR Exhaustive tests were made by the Division of Industrial Hygiene, of the composition of the exhaust gases given off by a Diesel engine mounted on. a test block. These tests showed that certain quantities of the gases are discharged from the exhaust. On the basis of these figures, preliminary requirements of design and control

Jan 1, 1942

By Duane H. Haley

Dr. F. Well, the first thing that you have to realize is what is the Bureau of Mines? The Bureau of Mines basically has two functions. First it does the research and development relating to mining, processing, conversion, refining, recycling and substitution for minerals and materials. We work hand in hand with the U. S. Geological Survey on the geological end, although the exploration part of the game is theirs, and there is a very good relationship between the Survey and the Bureau of Mines. There are some overlaps with the Office of Coal Research, and we expect to be able to straighten out the areas of overlap, because it's important than OCR and the Bureau work together. Both the Office of Coal Research and the Bureau of Mines will have increased budgets next year, assuming that they are appropriated by the Congress. The other general area is in the whole area of mineral policy. The Bureau of Mines again is the key agency for developing data and analyses and making recommendations on all types of mineral policy in the Federal Government. It's a focal point for all types of minerals activities. It's the only real centralized focal point, along with the USGS, in the whole Federal Government. The problem areas, to answer your question specifically, are first of all the Bureau of Mines budget this year is $105 million and the budget for next year is $215 million, so it's more than double. Now, assuming that this budget is appropriated by the Congress, most of that money will be used for research and development in the energy area.

Jan 4, 1974

By L. A. Rapoport, W. J. Leas, C. W. Carpenter

A program of scaled flow model experiments has been undertaken to study the performance of five-spot water floods. The modeling procedures are discussed and the construction and operation of the flow models are described. The tests were specifically designed to investigate the effects of injection rate and of oil-to-water viscosity ratio on oil recovery. The areal sweep of five-spot water floods was also studied, and direct comparisons between five-spot and linear flooding behavior have been established to permir better utilizatfon of core analysis results for purposes of field waterflood evaluations. INTRODUCTION For a long time reservoir engineering procedures have been confined to the consideration of idealized, one-dimensional or linear systems.11* However, direct application of the linear waterflood mechanism to the evaluation of actual field performance is justifiable only for the purposes of rough approximation. To obtain a realistic analysis of field behavior, it is necessary to account for reservoir geometry and well distribution, and to take into consideration the configuration of the flow of fluids between injection and producing wells. In the past it has been attempted to account for the complex nature of the fluid movement in the reservoir by associating each well pattern with a certain "sweep-efficiency constant", e.g., a sweep efficiency of 72 per cent for the conventional five-spot pattern.' More recently, methods of waterflood evaluation have been improved by the introduction of variable sweep-efficiency factors, defining the areal coverage as a function of cumulative water injection and viscosity or "mobility" ' ratio.""' These variable sweep-efficiency factors, derived from miscible fluid displacement experiments, require the assumption of piston-like displacement of oil by water. This implies that only one fluid, either oil or water, is moving at any one point of the reservoir ht any moment. Such an assumption, however, is incompatible with the bulk of the experimental evidence and also theoretical considerations which indicate that usually in the area invaded by water, both oil and water are flowing in varying proportions, in accordance with the relative permeability characteristics of the porous medium. Another recent approach toward the evaluation of five-spot flooding behavior involves correlations of the areal sweep efficiency (observed in immiscible fluid experiments) with a "mobility ratio," based on the consideration of the "average" relative permeability to the displacing fluid. Combination of these correlations with a modification of the Buckley-Leverett frontal-drive equation leads to a computational procedure for predicting the recovery performance of areal water floods. While of considerable interest, this approach has no complete theoretical justification and, therefore, does not entirely clarify the features of five-spot water floods. Rigorous, theoretical treatment of waterflood behavior in two- or three-dimensional systems as encountered in the reservoir, including proper consideration of relative permeability and capillary-pressure functions, is as yet beyond the scope of analytical or computational methods. The, behavior of such water floods can, however, be studied by means of scaled flow model ekperiments, which is the approach followed in these investigations. The flow model experiments described in this paper simulate a uniform, horizontal formation of constant thickness with fully penetrating wells. The system under consideration is entirely liquid saturated and not influenced by compressibility effects, which is representative of the situation achieved after gas fill-up under practical conditions. Gravity segregation effects are assumed to be negligible, which implies a relatively thin reservoir formation and/or low vertical permeability. THEORETICAL CONSIDERATIONS For a flow system of uniform thickness with no appreciable effects of gravity segregation, the analysis of water-oil displacement can be confined to a two-dimensional treatment based on the consideration of a "slice" of unit thickness. Referring to previously established derivations," the displacement of oil by water in such a system can be described by the following, dimen-sionless equations:

By R. W. Heckel, H. P. Cheskis, A. Lawley, M. R. Pinnel

THERE are discrepancies reported in the literature regarding the micro and macro stress-strain behavior of metals and alloys. In particular, Young's modulus and micro yield measurements often show significant variations depending upon the techniques employed.'-" The purpose of this note is to correlate measurements made with four techniques and to indicate where some of these discrepancies might arise. Allied use of these techniques can provide a complete and consistent characterization of micro and macro stress-strain behavior (over the strain range of 10-9 to 10--2 in. in.-') from a minimum number of samples. Techniques. The techniques employed for measuring stress-strain behavior involved the use of a) linear differential transformers, b) SR-4 strain gages, c) longitudinal resonance waves, and d) X-ray diffraction. Specimen geometries and preparations are summarized in Table I for each technique. Differential Transformer and Strain Measurements. An Instron universal testing machine, modified with an alignment device, was used to apply the load via parallel-jaw grips. The signal from the load cell was applied to the Y scale of a Moseley X-Y recorder (sensitivity of 10 lb load per in. chart). The elongation was monitored simultaneously with strain gages mounted on three sides of the rectangular specimen, and with two linear variable differential transformers (LVDT) mounted at 90 deg to one another on faces that also contained the strain gages, Fig. 1. The signal from one of the LVDT's was applied to the X scale of the recorder (sensitivity 40 µ in. elongation per in. chart) in order to trace a continuous load-elonga-tion curve. Concurrently, the strain on the same face (i.e., the face monitored by the LVDT) was recorded by the corresponding strain gage. A stress-strain curve was plotted from the load cell-strain gage data and was compared to the stress-strain curve (converted from load-elongation) plotted from the continuous load cell-LVDT trace. Identical Table I. Description of Specimens Used in the Present Study Material Dimerisions Preparation Condition 99.99 pct A1 tensile 318 by 3/16 by 3 in. as cast ingot; cut annealed specimen on diamond wheel 2024 A1 tensile 318 by 3/20 by 31/2 in. vacuum hot annealed specimen pressed sheets; cut on diamond wheel 99.99 pct Al 3116 by 3/16 by 2 in. cut from tensile prestrained dynamic modulus specimen after 10"* in. specimen test per in. 2024 A1 dynamic 3/20 by 3/20 by 2 in. vacuum hot annealed modulus specimen pressed sheets; cut on diamond wheel 2024 A1 X-ray gage section 112 by vacuum hot annealed specimens 1/4by1/20in. pressed sheets; cut on diamond wheel

Jan 1, 1970

By John F. Abel

AIME is closing the books on its first 100 years. In the next year the meetings and many papers will doubtless be filled with statistics on the growth of AIME, and, incidentally, on the mining industry. Let's try to keep our cool and avoid breaking our arms patting ourselves on the back. AIME, nationally and locally, runs on the drive and dynamism of a rather small number of its members. If you look at the annual SME Blue Book of national officers and committee members, you will be struck by the repetition of the same names throughout. Trend for a few men to shoulder the burdens and responsibilities can be seen on the local level, too.

Jan 1, 1970

By W. Luyken, E. Bierbrauer

A number of articles have been published, notably those by R. S. Handy, R. T. Hancock and A. P. Watt in Engineering and Mining Journal, dealing with the calculations involved in ore dressing. These publications demonstrate both the importance of the subject and the lack of success in developing a generally recognized method for comparing enrichment effects. Considering that we may wish to compare enrichment results on similar or dissimilar ores, that we may desire to make the comparison on the basis of either the absolute or the economical efficiency, and that the number of factors upon which the result depends is large, the question arises whether it is possible to set up a positive method for such calculations. In the following pages it is our aim to show that a sure, complete and successful way to overcome existing difficulties has been found. Graphical Analysis of Ore-dressing Processes The following is from Truscott's Text Book of Ore Dressing (London, 1923): x = assay of ore treated (feed). y = assay value of the concentrate. 2 = assay value of the tailing. a = weight of feed. 6 = weight of concentrate. c = weight of tailing. C = fractional concentration = = . a y - z K = ratio of concentration = 1/c a/b = y-z/x-z 2 B = fractional recovery = 9 = C y/x (3) 100R = percentage recovery. Copt. = theoretically best concentration. 100 — Copt = waste in the feed.

Jan 1, 1930

By Frederic Dewey

HAVING shown1 the difficulty of assaying so-called cyanide bullion and the extreme variations often found in the results, an investigation was undertaken to discover if possible the causes of these variations by a series of tests upon the specific action of various metals during cupellation. Zinc.-In order to test the effect of zinc, 48 assays were made in sets of 6, 2 rows of 3. The charge for the middle cupels consisted of 500+ mg. Au, 1,125 mg. Ag, 10 mg. Cu. To the end cupels 50, 75, 100 and 125 mg. Zn were added, and a set of each proportion was cupelled with 4 and 8 grants Pb. The cupels were assayed and showed the following gold contents in milligrams, the figures being arranged as the cupels stood in the muffle: TABLE 1 50 Mg. Zn 75 Dig. Zn 100 Mg. Zn 125 Mg. Zn 4 grams, Pb 0.2S 0.25 0.2S 0:29 0.27 0.34 0.33 0.28 0.41 0.31 0:30 0.36 0.30 0.33 0.34 0.31 0.31 0.29 0.35 0.37 0.42 0.41' 0.34 0.38 8 grams, Pb 0.40 0.43 0.42 0.38 0.36 0.43 0.35 0.34 0.41 0.33 0.37 0.37 0.54 0.17 0.59 0.44 0.43 0.43 0.38 0.39 0.41 0.57 0.38 0.46 _ In many instances the zinc does not appear to affect the cupel gold, but various exceptions are apparent, generally in the cupels in the back row. With 100 and 125 mg. Zn, in some cases the Zn burned with its characteristic flame before it could alloy with the other metals. Also, less fusible oxidized lumps were observed during the cupellation and some cupels showed a scum. In order to lessen the premature burning out of the Zn, an alloy of 2 parts Ag to 1 part. Zn was used. A uniform charge of 500,+ mg. Au,

Jan 7, 1917

Assaying, mineralogy, and geology appear in ancient records as early as mathematics, physics, and chemistry. Agricola was the first author to unify the earth sciences, the mineral extractive industries and the mineral processing industries. His text, De Re Metallica, published in Latin in 1556, is recognized as the first technical literature. In 1702 mining instruction was started at Freiberg, Germany. The purpose of this school was to train skilled workers, a program corresponding to present-day, on-job, vocational-technical, upgrading extension training. Formal instruction in mining engineering began at Schemnitz, Hungary, in 1763, at Freiberg, Germany, in 1766, and at St. Petersburg, Russia, in 1773. It is interesting to note that these three schools initiated instruction in mining engineering before formal instruction in civil engineering began at Paris, France, in 1775. Early mining engineering, 1763-1900, was expected to cover all eventualities in the mineral industries. Optional curricula were offered early in the 20th Century but did not reach into all branches until after World War I. Specialization crystallized during World War II under three organic units: (1) Earth Sciences; (2) Mineral Engineering; (3) Mineral Technology, the three together constituting the mineral arts and sciences of the modern world (Fig. 10).

Jan 1, 1950

By Auguste J. Rosh

The use of titaniferous ores in the blast-furnace has been the subject of much controversy for many years. Divers objections have been raised against them, and, for one cause or another, the verdict

Jan 1, 1893

By George R. Ensminger, E. Heaton Hemingway

During the past year, the Watertown Arsenal has been interested in the occluded gas and oxide content of certain ordnance steels in order to determine, if possible, whether some of the peculiar failures in their physical properties might not be traced to these causes. For the purpose of best accomplishing a study of this nature, it was decided to heat the various samples of steel in a vacuum for definite periods of time at high temperatures and carefully examine the quantity and composition of the gases evolved. By the use of a fused quartz tube fitted with a water-cooled, ground-glass stopper, it was possible to maintain a vacuum at a temperature of 1000" C. for 10 hr. without perceptible leakage being evidenced as measured by a McLeod gage. The silica tube was connected with an evacuating system so constructed that the volatilized gases could be removed from time to time and a low vacuum of 0.0002 to 0.0010 mm. of mercury continuously maintained. At no time during the period of heating or in the removal of the gases did the evacuated system come in contact with rubber stoppers or any rubber connections, making contamination from such a source, impossible. In other words, the only volatile products that could be: obtained must necessarily have come from the steel itself or from the glass and fused quartz system or from the mercury used as a sealing agent. In the carlier experiments, the steel treated was in the form of turnings, but this practice was discarded because the weight's of the turnings before and after being heated were widely inconsistent,, even when taken from the same piece of steel. This discrepancy developed largely through variation in the amount of metal volatilized with the gases; this metal could always be seen in the form of a ring where it condensed in the cooler portion of the tube in either the amorphous or crystalline condition. Because of the frequency in occurrence and the variation in the manner of deposition, this material was roughly analyzed and found to consist for the most part of iron. At the same time two samples of steel that had been

Jan 1, 1922

By E. Heaton Hemingway, George R. Ensminger

During the past year, the Watertown Arsenal has been interested in the occluded gas and oxide content of certain ordnance steels in order to determine, if possible, whether some of the peculiar failures in their physical properties might not be traced to these causes. For the purpose of best accomplishing a study of this nature, it was decided to heat the various samples of steel in a vacuum for definite periods of time at high temperatures and carefully examine the quantity and composition of the gases evolved. By the use of a fused quartz tube fitted with a water-cooled, ground-glass stopper, it was possible to maintain a vacuum at a temperature of 1000" C. for 10 hr. without perceptible leakage being evidenced as measured by a McLeod gage. The silica tube was connected with an evacuating system so constructed that the volatilized gases could be removed from time to time and a low vacuum of 0.0002 to 0.0010 mm. of mercury continuously maintained. At no time during the period of heating or in the removal of the gases did the evacuated system come in contact with rubber stoppers or any rubber connections, making contamination from such a source, impossible. In other words, the only volatile products that could be: obtained must necessarily have come from the steel itself or from the glass and fused quartz system or from the mercury used as a sealing agent. In the carlier experiments, the steel treated was in the form of turnings, but this practice was discarded because the weight's of the turnings before and after being heated were widely inconsistent,, even when taken from the same piece of steel. This discrepancy developed largely through variation in the amount of metal volatilized with the gases; this metal could always be seen in the form of a ring where it condensed in the cooler portion of the tube in either the amorphous or crystalline condition. Because of the frequency in occurrence and the variation in the manner of deposition, this material was roughly analyzed and found to consist for the most part of iron. At the same time two samples of steel that had been

Jan 1, 1922

By H. LeChatelier, B. Bogitch

Page Introduction........................... 134 Methods of Investigation....................... 135 The Tridymite Network...................... 137 Independent Variables....................... 146 Manufacturing Operations..................... 153 Introduction Silica brick are indispensable in the manufacture of steel because they alone are able to withstand the high temperature of regenerative furnaces. All attempts to replace silica brick by other refractory materials for this purpose have failed, but the reason for this failure has remained obscure; we shall give an explanation later in this paper. Before the war, silica brick employed in France came principally from abroad, for which reason, since the beginning of hostilities, certain French steel works have been seriously handicapped. Our attention was first directed to the question by M. Bied, Engineer of the Teil Works. With him, we began certain investigations, at first using our laboratory and the furnaces of neighboring steel works. The larger part of our experiments, however, have been made in the laboratory of the Faculty of Sciences at the Sorbonne. For the heating of our samples, we are deeply obliged to MM. Charpy, Yeatmann and Guerineau. In undertaking these studies, our first aim has been to render assistance to French industry, by indicating, as precisely as possible, the necessary conditions for the manufacture of high-grade brick; but at the same time me have

Jan 1, 1919

By G. C. Wallick, J. S. Aronofsky

This paper presents an experimental verification of numerical solutions of the differential equation describing the transient flow of an ideal gas through a porous material including gas slip effects. Several experiments previously proposed by one of the authors are described together with the correlation of the experimental results with the numerical solutions. Excellent agreement is shown between experiment and theory, thus demonstrating the validity of both the basic assumption made in the derivation of the differential equation and of the numerical solutions of the differential equation. INTRODUCTION In a recent paper,' one of the authors has discussed a numerical solution of the differential equation describing the unsteady flow of an ideal gas through a porous material. This paper was primarily concerned with the effect of gas slip on the flow behavior. In steady state measurements, Klinkenberg2 and others have observed that the apparent gas permeability Kn of a porous material may be expressed as a linear function of the reciprocal average pressure 1/P of the form, ka = b + m/P........(1) where the intercept b is a constant for a given porous material and the slope m is a constant for a given porous material-gas combination. Aronofsky1 assumed that Equation (1) could be used to describe transient flow if P was replaced by the average pressure in an infinitesimal volume element. A number of numerical solutions of the resultant differential equation were presented and specific flow experiments were proposed as a means of testing the numerical solutions. The purpose of the present paper is to describe the results of several of these experiments and the correlation of the experimental data with the results of the numerical analysis. Reference should be made to the previous paper' for details of the mathematical and numerical analysis. EXPERIMENTAL PROCEDURE A simplified schematic drawing of the experimental apparatus is shown in Fig. 1. An 8.89 cm diameter limestone core of length L = 14.82 cm was mounted in a conventional rubber sleeve permeameter cell. The external sleeve pressure in this cell was maintained equal to 500 psig during all experimental tests, thus permitting only longitudinal flow through the core. One end of the core, X = L, was connected to an adjustable cavity of volume V as well as a pressure gauge or manometer. The other end of the core, X = 0, was connected to a Nullmatic pressure regulator which was in turn connected to a nitrogen cylinder or vacuum pump. In each experiment, the core and adjacent dead volume were charged with nitrogen to a uniform gas pressure P1. The pressure at X = 0 was then suddenly raised or lowered to a constant pressure P, and the resulting pressure buildup or pressure decline at X — L was recorded as a function of the time. The porosity + and the permeability constants m and b were determined using the transient method which was suggested by the results of the numerical analysis and which was described in the earlier paper.' The following average values for these constants were obtained as a result of 19 separate evaluations: 171 -0.259 2 0.005 md-atm; b = 0.374 5 0.008 md; and F = 0.098 ± 0.005*. It should be noted that in order that transient phenomena will be slow enough to be observed conveniently, it is desirable to use a porous material of very low permeability, e.g., less than I md. Moreover, it is in this low permeability range that the gas slip effects are most significant. Thus, such a low permeability sample is very suitable for use in an experimental verification of the numerical solutions previously described.

Jan 1, 1955

By G. W. Imholz

A number of interesting wells were drilled in north central Texas during 1940. The Shell Oil Company's Smith well in scc. 143, block I, H. and T. C. survey, Stonewall County, was completed for an initial production of 581 bbl. per day from the Mississippian limestone, with a total depth of 6065 ft. The same company's Patterson well, sec. 393, block D. H. and T. C. survey, Stonewall County, tested the Ellenburger limestone and was abandoned as a dry hole with a total depth of 6760 feet. In Nolan County the Tex-Harvey Oil Co. drilled a well in sec. 43, near the Tipton well, which was completed as a small producer in the Strawn section. The Tex-Harvey well tested this producing horizon but was abandoned as a dry hole with a total depth of 5210 feet. The Montour-Haggart well, sec. 184, block 2, H. and T. C. survey, Fisher County, tested the Strawn and was abandoned with a total depth of 5664 feet. The Georgian Oil Company's Blach, sec. 309, T. R. and L.. Shackelford County, encountered the top of the Ellenburger limestone at 4725 ft. After being plugged back to 3915 It. from a total depth of 4825 ft., the well tested 10 bbl, of oil per day and 300 bbl. of water. The W. I. Sothern No. 2 Carlisle well in sec. 293 was deepened to the Cambrian. The top of the Ellenburger was encountered at 6540 fcet. A wildcat well in Fisher County, the E. A. Stephenson-Maberry, apparently opened a new pool when the well encountered sand from 3298 lo 3302 ft. and was completed for 50 bbl. per day in the Cook sand horizon. In Jones County, the King Oil Company's Olsen well, sec. 158, B. B. B. and C. survey, extended the Avoca-Olander pool. The well was completed for 263 bbl. in 8 1/2 hr. from the Palo Pinto limestone, from 3298 to 3302 ft. Ungren-Frazier extended the Akard pool with No. I Akard, in the D. 'T. Bruce survey. The well was completed for 83 bbl. per day from the Cook sand, encountered from 2109 to 2126 feet.

Jan 1, 1941

By G. W. Imholz

A number of interesting wells were drilled in north central Texas during 1940. The Shell Oil Company's Smith well in scc. 143, block I, H. and T. C. survey, Stonewall County, was completed for an initial production of 581 bbl. per day from the Mississippian limestone, with a total depth of 6065 ft. The same company's Patterson well, sec. 393, block D. H. and T. C. survey, Stonewall County, tested the Ellenburger limestone and was abandoned as a dry hole with a total depth of 6760 feet. In Nolan County the Tex-Harvey Oil Co. drilled a well in sec. 43, near the Tipton well, which was completed as a small producer in the Strawn section. The Tex-Harvey well tested this producing horizon but was abandoned as a dry hole with a total depth of 5210 feet. The Montour-Haggart well, sec. 184, block 2, H. and T. C. survey, Fisher County, tested the Strawn and was abandoned with a total depth of 5664 feet. The Georgian Oil Company's Blach, sec. 309, T. R. and L.. Shackelford County, encountered the top of the Ellenburger limestone at 4725 ft. After being plugged back to 3915 It. from a total depth of 4825 ft., the well tested 10 bbl, of oil per day and 300 bbl. of water. The W. I. Sothern No. 2 Carlisle well in sec. 293 was deepened to the Cambrian. The top of the Ellenburger was encountered at 6540 fcet. A wildcat well in Fisher County, the E. A. Stephenson-Maberry, apparently opened a new pool when the well encountered sand from 3298 lo 3302 ft. and was completed for 50 bbl. per day in the Cook sand horizon. In Jones County, the King Oil Company's Olsen well, sec. 158, B. B. B. and C. survey, extended the Avoca-Olander pool. The well was completed for 263 bbl. in 8 1/2 hr. from the Palo Pinto limestone, from 3298 to 3302 ft. Ungren-Frazier extended the Akard pool with No. I Akard, in the D. 'T. Bruce survey. The well was completed for 83 bbl. per day from the Cook sand, encountered from 2109 to 2126 feet.

Jan 1, 1941

By J. E. Burke, A. M. Turkalo

IN 1923 Desch¹ pointed out that the grains in a metal which is anisotropic with respect to its thermal coefficient of expansion would contract differently upon cooling, and that the stresses developed might approximate the plastic strength of the metal. More recently Boas and Honeycombe2-5 studied the behavior of several metals upon thermal cycling and observed that the stresses developed in arlisotropic metals are great enough to produce slip lines in individual grains and a roughening of the specimen surface. This phenomenon they have named "thermal fatigue." The mechanism they propose involves essentially a kneading of the grains, the deformation being alternately in compression and tension in a given grain as the temperature is changed in one direction and then the other. The present work was undertaken to investigate the possibility that an additional mechanism might operate to produce plastic deformation during thermal cycling—a "thermal ratchet" that depends upon a combination of grain boundary flow to relax the stress that develops between differently oriented grains upon raising the temperature and transcrys-talline slip to relax the oppositely directed stress which develops on lowering the temperature. Thus, thermal cycling should produce a nonreversible distortion such that certain grains will change shape differently from their neighbors with a simultaneous displacement being produced at the grain boundary. Temperature Dependence of Grain Boundary and Grain Strength The critical resolved stress for the initiation of slip in metal grains is only mildly affected by temperature." For example, in cadmium it decreases from 0.15 to about 0.05 kg per sq mm when the temperature is increased from 20° to 458°K and further temperature increase causes little further decrease. On the other hand, the work of KG1 indicates that the grain boundaries behave in a viscous fashion that can be described8 by the expression: t = BVexp(Q/RT) [1] t is the shearing stress on the boundary; B, a constant; V, the flow rate at the boundary; Q, the activation energy for grain boundary flow; R, the gas law's constant; and T, the absolute temperature. Eq 1 indicates that the stress necessary to cause a given grain boundary flow rate, V, decreases rapidly with increasing temperature. The value of the constant B is such that at sufficiently low temperature and ordinary strain rates deformation will occur preferentially by slip rather than by grain boundary flow. There is considerable evidence to indicate Consider the bicrystal shown in Fig. 1. In grain 1 the slip plane lies 45 " to the boundary while in grain 2 the slip plane is 90" to the boundary. The coefficients of expansion of the grains in a direction parallel to the length of the crystal are a1 and a, with a, > a2 for the orientations shown. The sequence of events that can occur upon heating and cooling this specimen is illustrated schematically in Fig. 2. Initially there is assumed to be no stress in the specimen (A). Upon heating, grain 1 attempts to become longer than grain 2, but is constrained by grain 2. Thus grain 1 is loaded in compression and grain 2 is loaded in tension, and a shearing stress is present across the boundary (B). As the temperature is increased, the stress will build up, and finally grain 1 will be plastically deformed by slip, since the greater stress is resolved on its slip planes. Any further heating will result in more slip and the stress will remain constant until some temperature T* is reached where the stress can be relaxed by grain boundary flow.† At this relaxation temperature (C) a step will appear between grain 1 and grain 2. Further heating above T* will cause grain 1 to become relatively longer, but no stress will appear because the grain boundary is too weak to support the stress (D). Upon cooling again, at T* (E), the grain boundary will again be able to support a shearing stress, and upon cooling further, grain 1 will be loaded in tension and grain 2 in compression (F). When the decrease in temperature below T* is sufficient to impose the critical shear stress upon the slip plane of grain 1, it will be stretched by slip.

Jan 1, 1953

Discussion of the paper of, RICHARD H. RICE, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 89, May, 1914, pp. 721 to 743. S. G. VALENTINE, Oxford, N. J.-In a paper read at the New York meeting of the Institute last February I presented some notes taken from our experience with the turbo blower operating on a blast furnace. In connection with Mr. Rice's very interesting paper there are a few items that might be of further practical interest. The question of the reliability of this type of blower will naturally be presented. In this connection we would say that our turbo blower has been in practically continuous use during the present blast, which was begun June 7, 1912, with only three interruptions for repairs of any consequence. Soon after blowing in there was developed a tendency of the blower to surge or pulsate. This occurred on operating at a point considerably below the normal capacity of the machine, and was checked with comparatively little trouble by throttling the intake slightly and taking up a small lost motion on the governor connections, a legacy of the previous blast that had not been attended to. All this required only a few hours' time. In. March, 1914, the furnace being banked on account of a blizzard that cut off our freight deliveries for five days, the opportunity was used to replace the carbon packing on the steam-turbine shaft and to repack the steam inlet valves. In June, 1914, the blower was off 8 hr. to replace an oil ring and scrape a bearing. With these exceptions we have made continuous use of the machine and find we can depend upon it with entire safety as a piece of machinery.

Jan 4, 1915

By Robert Hunt

(New York Meeting, February, 1913.) I HAVE frequently stated that while the chemical composition of steel is important, yet even greater importance is connected with the mechanical and heat treatment of the metal. During the past year I encountered such a positive example of that fact that I deem it worth putting upon record. A prominent railway system divided an order for open-hearth steel rails between two steel works, both of which are under the control of the one corporation; giving to one about 18,000 tons, and to the other 7,500 tons of the same section and to be made under the same specifications. The rolling results obtained in the two mills varied so widely that a study of the figures is intensely interesting and serves to illustrate the advantages obtained by careful ingot casting, and, quite as pertinently, the possible benefits of careful subsequent heating and rolling with moderate reductions in the rolling process. The smaller order was rolled complete in four installments during the same months that the larger order was being made in six separate installments; but, to permit of exact comparisons, the totals of the four installments (completing the order with the mill which I will call A) are given with the totals of the first four installments of the larger order, made by the mill designated as B. These rolling results are:

Jan 5, 1913

On the following pages are abstracts of papers published by the Institute during the year 1934 as TECHNICAL PWLICATIONB, CONTRIBUTIONS, m bound volumes and in MINING AND METALLURGY. For abstracts of papers that appear In bound volumes in 1934 but that were published as TECHNICAL PWLICATIONS m 1932 or 1933, see the TRANSACTIONS for 1932 and the YEAR BOOK dated January, 1934. Many of the TECHNICAL PWLICATIONS have been reprinted In bound volumes Information regarding this disposition, and number of pages in each paper, may be found m the list beginning on page 92 Volume numbers are given as listed at the beginning of the index, page 99 The abstracts are grouped as follows:

Jan 1, 1935

The General Electric Co., in cooperation with the Montana School of Mines and under a research grant from the Anaconda Co., is presently experimenting on a new non-explosive method of breaking rock with radio-frequency electrical power. The method is known as electrothermal forcing. It must be understood that present equipment has not been designed to perform primary blasting functions. Its conceived use will be restricted to small pieces of rock too large to pass through a chute or grizzly. However, even this use is still far in the future. Experiments to date have been limited mostly to rock smaller than 18 in.

Jan 11, 1961