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By H. F. Korman, M. C. C. Mow, P. K. Dai

INTRODUCTION Detonations of high explosives in soil and rock have been used frequently in civil engineering applications. Of particular interest in recent years has been the development of test methods to simulate the desired blast and shock environments for the testing of protective structures. The United States Air Force, in particular, the Air Force Weapons Laboratory, in conjunction with the Defense Atomic Support Agency, has in recent years, developed special technology for simulation testing of protective structures in soil and rock media. Such a technology, although initially developed for military applications, is rapidly finding its way into civil applications. One of the major problems in the design of the simulation test is the correct prediction of ground motion induced by the detonation of high explosives. This paper presents a useful prediction method which is developed specifically for ground motion in rock that is induced by the detonation of a buried planar array of explosive columns (See Figure 1). The technique of simulating shock environment using such an array is called the Direct Induced High Explosive Simulation Tech- nique (DIHEST). Normally, each shot hole may contain canisters of ammonium nitrate positioned at various depths, or a slurry explosive with detonators positioned along its length (See Figure 1). The depth and width of the array, the spacing of shot holes, the spacing of detonators, the degree of containment, and the charge weight are the variables which govern the induced ground motion

Jan 1, 1971

Jan 1, 1890

YEAR OF ELECTION 1913. FRANK DAWSON ADAMS, Montreal, Canada. 1933. KARL EIKERS New York, N. Y. 1922. FEDERICO GIOLITTI Torino, Italy. 1906. SIR ROBERT A. HADFIELD London, England. 1921. FRANK WILLIAM HARBORD London, England. 1917. HERBERT HOOVER Washington, D. C. 1941. DANIEL COWAN JACKLING San Francisco, Calif. 1939. HENRY KRUMB New York, N. Y. 1921. C. McDERMID London, England. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1935. ROBERT PEELE New York, N. Y. 1938. A.M. PORTEVIN Paris France 1937. JOHN V.W. REYNDERS, New York, N. Y. 1937. GEORGE S. RICE Washington, D. C. 1911. ROBERT H. RICHARDS Cambridge, Mass. 1934. T.A. RICKARD Victoria, B.C., Canada

Jan 1, 1941

By J. B. Cohen, B. W. Howlett, M. B. Bever

The partial molar heats of solution at infinite dilution in tin of aluminum at 300° and 350°C and of gallium, indium, and thallium at 240°, 300°, and 350°C have been measured by tin solution calori-metry. Aluminum, gallium, and thallium are endo-thermic on solution; indium is exothermic. Any temperature dependence of the heats of solution lies within the experimental scatter. Over the dilute ranges investigated, only aluminum has a measurable change in its heat of solution with composition. HEATS of solution of one element in another reflect the interaction between them. The investigation of partial molar heats of solution in dilute alloys is of particular interest as the properties of the solvent are altered to only a limited extent by the presence of the solute and also as the interaction between solute atoms is small. When the heats of solution of a related series of elements in a solvent are known, a systematic comparison may be made. In the investigation reported here, the partial molar heats of solution of the Group III elements aluminum, gallium, indium, and thallium in dilute solution in tin were measured. This work follows an investigation of the heats of solution in tin of the Group IB elements.' EXPERIMENTAL PROCEDURES Materials. Samples of gallium, indium, and thallium were obtained from Johnson, Mathey and Co., Ltd. Indium and thallium were supplied as wire, 1.6 mm in diam; gallium was in the form of irregular pieces. The supplier reported the following minimum purities: gallium—99.95 pct; indium—99.99 pct; thallium—99.99 pct. The aluminum, obtained from Alcoa Research Laboratories, was reported to be 99.995 pct pure. The tin was supplied by Baker and Co., Inc.; the reported analysis indicated a tin content of at least 99.96 pct with lead as principal impurity. Calorimeter. this description will cover only the essential features of the calorimeter with special attention to modifications made since an earlier description was published.' A Dewar flask containing the tin bath was held in a constant-temperature bath of a near-eutectic mixture of lithium, sodium, and potassium nitrates. This bath, which was stirred vigorously, was heated by a primary resistance winding in the container wall and by a secondary winding immersed in the salt. The voltage supplied to both windings was stabilized. The temperature of the salt bath was controlled by means of a platinum resistance thermometer in one arm of a Wheatstone bridge. The light from a mirror galvanometer in the bridge circuit fell on a photocell which controlled the current in a saturable reactor in series with the secondary winding. In this manner, the temperature of the salt bath was controlled to ±0.003°C and that of the tin bath to at least ±0.002°C. Each of these temperatures was measured by two iron-constantan thermocouples in series, coiled in a helix to minimize heat loss and immersed in the salt and tin baths in protective sheaths. The temperature of the laboratory was kept constant to ± 1°C during a run. Specimens were dropped into the tin bath from an addition arm held at O°C which was part of the cal-orimetric system. The system was evacuated to about 0.02 1 to minimize oxidation and to reduce transfer of heat. The bath was stirred by a glass stirrer introduced through a double Wilson seal. The samples were scraped clean before weighing, which was carried out as rapidly as possible. Each sample was immediately placed in the evacuated addition arm to minimize contamination. These precautions were especially necessary with aluminum. After the runs with gallium and thallium at all temperatures and with indium at 240° and 350°C (Series I) were completed and before the runs with indium at 300°C and aluminum at 300° and 350°C (Series 11) were begun the following changes were made. The shape of the Dewar flask was changed so as to result in a lower surface to volume ratio of the bath and at the same time the amount of tin was reduced from 500 to 400 g. The paddle type stirrer was replaced by a helical screw and the rate of stirring was increased to about 150 to 200 rpm.

Jan 1, 1962

By Thomas M. Drown

THE means relied on to attain uniformity in Bessemer steel may be enumerated as follows I. The appearance of the flame. II. The appearance of the slag. III. The spectrum of the flame. IV. Examination of the steel itself. At present, I wish briefly to bring forward a few considerations with reference to the last two mentioned, namely, the conditions favoring the employment of the spectroscope and examination of the steel. From the amount of careful investigation which has been devoted to the examination of the Bessemer flame by the spectroscope, both on the part of scientists and practical metallurgists, one might reasonably expect some results definite and satisfactory in their nature, first, as regards the nature of the flame, and second, as to the practical value of the spectroscope as a guide in conducting the process. We find, in fact, however, that uncertainty and confusion still exist. In Germany, where this subject has received the greatest attention, it is now very generally conceded that manganese is the cause of the well-known groups of dark bands that characterize the Bessemer spectrum. Nor is it easy to see how we can avoid accepting this conclusion, when Wedding and Von Lichtenfels have produced the manganese spectrum and found it to correspond closely with that shown by the Bessemer flame. But it is evident, on a moment's reflection, as Roscoe has recently brought forward, that manganese cannot be the only cause of the Bessemer spectrum, for we notice the characteristic bands quite as

Jan 1, 1873

By N. A. D. Parlee, I. D. Shah

ThIS reports on some work done on the solubility and diffusivity of oxygen in liquid silver. Solubility. Improvements in the measurement of the solubility of oxygen in silver and silver alloys were made because precise data were needed for calculating diffusion coefficients of oxygen in these alloys. The apparatus and the procedure used were similar to those of Parlee and Sacris.' The main improvement was in the temperature-measuring technique. A MV30 mullite protection tube containing a calibrated Pt-Pt, 10 pct Rh thermocouple was inserted in the reaction tube from the top through a vacuum-tight swage-lok fitting. The protection tube was well-immersed in the liquid silver, which was heated by induction. A Leeds and Northrup potentiometer was used in connection with the thermocouple. All runs reported were made at 1 atm. The temperature range investigated varied from 940" to 1200°C. The ternary point in Ag-0 phase diagram2 is at 939°C and 0.32 wt pct O. This point was reinvestigated using the above-described apparatus and was found to be at 939°C and 0.315 wt pct 0. It was determined by observing the sudden evolution of oxygen at this point while the solubility measurements were made. The point was easily reproducible if precautions were taken to keep the liquid silver essentially in equilibrium with oxygen and to lower the temperature very slowly. All of the results of this new solubility investigation are plotted in Fig. 1. They are represented by the "least-squares" line shown in the figure and the following equation for solubility at po2 = 1 atm: log% O =695.4/T - 1.086 This equation differs only slightly from that proposed by Parlee and sacrisl and that of Diaz, Masson, and Richardson.3 The points of Parlee and Sacris, using an optical pyrometer, are shown for comparison.

Jan 1, 1968

By Hiroshi Oikawa, A. G. Guy

Recent experimental evidence has shown that it is often incorrect to neglect the reactions occurring at an interface with respect to the diffusion reactions. By introducing reaction-rate constants and k for the transfer of components 1 and 2 between the a and b phases, a phenomenological description has been devised for the coupled processes of diffusion and in-terfacial reaction. An illustrative example has been analyzed with the aid of a suitable computer program. The results indicate that for kab values on the order of 10'1 cm per sec and Ð values of about 10¯10 sq cm per sec, the interfacial reactions are significant during the first 10 2 to l0 6 sec of a diffusion experiment. Among the observable effects of the interfacial reactions in this case appear to be the burying Kirkendall markers and an anomaly in the initial shifting of these markers. THE study of diffusion between two phases is especially important because of its direct connection to phase transformations. For example, the transformation of austenite to ferrite involves diffusion in the a and ý phases and also an interfacial reaction (trans formation) at the a/? interface. If ferrite and aus-tenite are the two members in a diffusion couple, the same two reactions occur during the diffusion process. The numerical values obtained for the diffusion coefficients and interfacial-reaction constants from diffusion experiments can then be employed to predict phase-transformation behavior. Refinement of the calculations of phase transformation is also suggested by the present method for treating two-phase diffusion. In the recent paper by Nolfi et al.' only the solute com ponent is considered in the interfacial reaction accompanying a phase transformation. The present analysis demonstrates that both components must be considered. It is generally recognized that reactions of some kind must occur at the interface in a two-phase diffusion couple, but usually it is assumed that the interface reaction occurs so rapidly that its effect on the overall process is unobservable because the slower diffusion process determines the kinetics of the process. However, Seith and Heumann 2 pointed out that effects of the interfacial reaction should always occur in the early stages of diffusion, and recently Eifert et al. 3 have shown that interfacial reactions influence the composition and motion of the interface in a/ß Al-Cu diffusion couples during the entire course of prolonged, high-temperature treatments. A general procedure for handling the combined processes of interfacial reaction and diffusion in a binary, two-phase system is to introduce kinetic coefficients for the interface reactions and to develop the system of equations governing the interlinked processes of diffusion and interface reaction. The resulting equations, although not amenable to solution in closed form, can be usefully manipulated by a digital computer. INTERFACIAL REACTIONS IN TWO-PHASE DIFFUSION Consider the general case of diffusion between two solid solutions, a and ß, which are adjacent phases in a binary system, Fig. 1. Two semiinfinite bars having compositions c1 and c0ß are jointed at x = 0. If concentrations are expressed in volume fraction,4

Jan 1, 1970

By Gerald Edmunds

IN a paper1 before this Institute in 1940, the writer reported that the surface orientation texture of zinc and cadmium differed from the texture existing within the casting, in that basal planes were parallel to the surface. He was unable to rationalize the origin of this surface texture. It is conceivable that the surface orientation texture is influenced by the atomic force fields, which are different at the surface and within the body of metal. It was considered that a radical change in the surface against which the metal is cast might alter the surface texture. In trial of this, zinc has been cast against a surface of molten lead, but the same result has been obtained-i.e., (001) parallel, ±20°, to the surface-as was obtained when it was cast against air, Transite or iron.1 Into the bottom of an open cast-iron tray, 7 by 14 in. by 2 in. deep, preheated to about 275°C., about ¼ in. of lead, then) ½ in. of zinc was poured, and the whole was covered with an electric heater to enforce freezing from the bottom upward. After a lapse of time sufficient for the zinc but not the lead to solidify, the zinc slab was raised free of the molten lead. The bottom surface of the zinc casting was coated with a thin layer of lead. A specimen of the slab 1 ½ in. square was metallographically polished to flatten it and remove the slight film of lead, and the orientation was determined by the method used before,1 with the result stated above. Some determinations have also been made on other metals, as follows: Surface orientation determinations were made on the 3/8-in. diameter grip section of two ¼ -in, diameter aluminum-alloy die-cast tensile bars and on a 1/8 by ½ -in. flat aluminum-alloy die-cast tensile bar. None of these three aluminum die castings exhibited any preferred orientation at-the surface. A brass die casting (nominal composition: 60 Cu, 37.75 Zn, 1.00 Sn, 1.00 Pb, 0.10 Al, 0.15 Si) furnished by C. S. Smith was also examined. The surface showed a random orientation of alpha and beta. SUMMARY A zinc casting solidified against a molten lead surface was found to have the same surface orientation texture, (001) parallel to the surface, as other zinc and cadmium castings. Aluminum and alpha-beta brass die castings were found to have random grain orientation textures at the surface. ACKNOWLEDGMENT The X-ray determinations were conduced by M. L. Fuller.

Jan 1, 1945

By O. G. Paasche, Yuan-Shou Shen

THERE is a disagreement among the various authors about the exact manner of transformation of ZrCr2. Rostokerl and others2 stated that ZrCr2 had a C-14 (MgZn2) type of structure below 1000°C and a C-15 (MgCu2) type of structure at temperatures above 1000°C. Alisova3 and others4 reached the opposite conclusion and stated that the transformation temperature is close to the melting point of ZrCr2. A literature survey shows that various investigators3'= who homogenized the specimens at a temperature higher than 1000°C have concluded that ZrCr2 had the C-15 structure at room temperature. Meanwhile, Jordan et al.4 reached similar conclusions without annealing the specimen. Other investigators1,2,6,7 who X-rayed the specimens in the as-cast condition without annealing reached different conclusions. The investigation reported herein was conducted with the aim of exploring the exact manner of transformation of ZrCr2 by various heat treatment tests. The alloys for this examination were prepared from iodide-reduced zirconium crystal bars, 99.9 pct purity, and electrolytic chromium, 99.9 pct purity. They were melted in a nonconsumable electrode arc furnace with water-cooled copper crucible in a helium atmosphere. The melting loss of each alloy was less than 1.5 pct by weight. Chemical analysis of a randomly selected specimen indicated that there was a very close agreement between calculated and analyzed compositions. Before being heat-treated each specimen was encapsulated in a vycor or quartz tube inside which an argon atmosphere was maintained at a pressure of lower than 1 atm. In determining the crystal structure of each specimen with a Debye-Scherrer camera, the standard procedure8 for X-ray quality analysis (Hanawalt method) was followed. The different series of heat treatment tests in this investigation are tabulated in Tables I and 11. The tests in Series I, specimens from 1-1 to 1-9, which were similar to Rostoker's experiment1 indicated that the transformation temperature seemed to fall between 870° and 900°C and that the crystal structure of ZrCr2 at lower temperature seemed to be of the C-14 type. However, once the compound is transformed to C-15 type, it is impossible to reverse the transformation back to the C-14 type by first heating the specimen above 900°C and then annealing it slowly below 900°C as shown in Experiments II-1 to II-3. Thus, it appears that the specimen of ZrCr2 will transform from C-14 to C-15 structure when heated above 900°C but will not transform from C-15 to C-14 when annealed slowly passing 900° C even after the extremely slow cooling process such as indicated in the experiment of Specimen II-3. As a valid transformation temperature is a temperature at which the transformation is reversible, therefore the temperature 900°C (or other temperature close to 900°C) is not the transformation temperature for ZrCr2 and the C-14 structure is not the stable structure of ZrCr2 at lower temperatures. The C-14 structure is retained at room temperature because the transformation to C-15 structure is very sluggish and the fast cooling after melting does not allow enough time for the transformation to take place. Additional energy is required to alter the metastable condition of the C-14 structure. The sluggishness of this transformation was again demonstrated through another series of experiments. Four specimens with C-14 structure were taken. Then they were annealed at 900°C but each specimen was soaked for a different period of time, Table 11. X-ray diffraction patterns of this group indicated that the C-14 structure gradually disappeared as the soaking period was lengthened. The figures listed under the column "C-14 Structure, pct" were estimated from the intensity of the d = 2.330 line of the diffraction pattern corresponding to the structure. Notice that the intensity of this line became weaker for longer soaking periods. To determine the transformation temperature of ZrCr2, specimens with C-14 structure (as-cast condition) were annealed at 1300°, 1400°, 1500°, 1550°, and 1600°C, respectively. A final specimen was first heat-treated to 1500°C in order to transform it to C-15 structure, then heat-treated at 1600°C again. From the X-ray analyses of this series of tests, Specimen Nos. III-1 to III-6, it is evident that a transition from C-15 structure at lower temperatures to the C-14 structure occurs at some temperature between 1550° and 1600°C.

Jan 1, 1969

United Engineering Trustees, Inc. ARTHUR S. DWIGHT GEORGE D BARRON J V. N DORR Engineering Societies Library Board ROBERT PEELE PHILIP W. HENRY GEORGE C STONE JOSEPH E. POGUE The Engineering Foundation H C BELLINGER GALEN H CLEVENGER J V N DORR

Jan 1, 1923

By R. V. Ramani, Christopher J. Bise, Robert Stefanko

Over 200 billion tons of coal reserves lie locked up in deposits west of the Mississippi River-and of this, well over 100 billion tons are recoverable only by underground mining methods. Yet, because of the associated problems of unfavorable economics and inadequate technology, western underground mines contribute less than 2% to the annual US coal production. In order to reach the billion-ton coal production level called for by President Carter, it a pears the majority of new coal development will come from the West. But for this to be possible, new mining methods and equipment must be designed to match the unique thick seam conditions.

Jan 10, 1977

For the year ending February, 1919 PRESIDENT SIDNEY J. JENNINGS NEW YORK, N. Y. PAST PRESIDENTS L. D. RICKETTS NEW YORK, N. Y. PHILIP N. MOORE ST. Louis, Mo. FIRST VICE-PRESIDENT C. W. GOODALE BUTTE, MONT. TREASURER GEORGE C. STONE, NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 12, 1918

By C. G. Dunn

According to a recently suggested effect of silicon on the re recrystallization textures of high-purity Fe-Si alloys with (111)[112] type rolling textures, the recrystallization texture for a rolled (110)[001] oriented iron crystal probably should be entirely different from that of a (110)[001] oriented 3 pct Si-Fe crystal. Comparative studies of iron and 3 pct Si-Fe crystals, however, show that both have (110)[Ool] recrystallization textures when the rolling textures are the (111)[112] type after reductions in thickness of about 70 pct. Qualitatively the results from the iron crystal are like those of polycrystalline high-purity 3 pct Si-Fe and not like polycrys-talline high-purity iron. The large effect previously noted probably involves unknown impurities or processing variables rather than silicon itself. Some problems on experimental and analytical procedure for a spherical X-ray specimen, which was machined from a laminated composite of sheet specimens, are treated in the Appendix. A possible strong effect of silicon on the textures produced in cold-rolled high-purity Fe-Si (HPFe-Si) alloys during primary recrystallization and normal grain growth was suggested in a recent paper.' All the textures were far from the random-orientation type, but that of iron, or of Fe-Si alloys of low silicon composition, was entirely different from the texture of 3 pct Si-Fe. The same effect was noted for the textures obtained prior to normal grain growth, i.e., for primary recrystallization.2 It is the main purpose of the present paper to provide some clarification of this silicon effect. All the HPFe-Si alloys from zero to 3 pct Si, which were rolled by two or more stages separated by anneals, developed (111)[112] type rolling textures.2 Thus, there was no effect of silicon on the rolling textures. Earlier, Gensamer and Mehl3 also found no effect of silicon on the rolling textures of Fe-Si alloys; they obtained the Kurdjum.ow and Sachs (K-S) rolling texture for iron,4 which is characterized as the three ideal components: (100)[011], (112)[li0], and (111)[112]. There is a difference between the HPFe-Si multiple-stage rolling texture and the K-S single-stage rolling texture, but this is a variable processing effect. Of interest here is the fact that the recrystallization textures from (111) [llZ] type rolling textures were different depending on the amount of silicon in the alloy. There was a relatively strong (110) [001] component in the recrystallization texture of HP 3 pct Si-Fe5,8,2 but no such component in HP 0.6 pct Si-Fe, for example; the recrystallization texture for the latter was two (111) [110] type components and a (111) fiber component 1,2 Several publications have shown that a strong (110) [001] recrystallization texture is derivable from a (111) [112] type rolling texture for 3 pct Si-Fe crystals reduced in thickness by about 70 pct.7-10 Furthermore it appears that the strongest of these (110) [001] recrystallization textures occurred when the orientation of the crystal prior to rolling was (110) [001].7 Barrett and evensoon11 found that the rolling texture of a (110)[001] oriented iron crystal was (111) [llj]. Accordingly, it seemed desirable to determine whether a (110) [001] oriented iron crystal, upon rolling and annealing, would behave like the 3 pct Si-Fe crystal (or the polycrystalline HP 3 pct Si-Fe) and thus produce a (110) [001] recrystallization texture contrary to the suggested silicon effect, or would behave like the polycry stalline HP iron or HP 0.6 pct Si-Fe and thus produce (lll) [110] type components in agreement with a silicon effect. Briefly, the idea here involves the use of more precisely defined textures to obtain if possible better control of important variables that affect the recrystallization process. PROCEDURE A (110) oriented crystal of Ferrovac "E" iron (99.9 pct pure) was prepared in sheet form 0.080 in. thick with the [001] direction parallel to the long dimension of the specimen.'' This crystal was etched to 0.073 in. thickness (to remove some small included grains) and then was cold rolled in a 6-in.-diam mill to a final thickness of 0.022 in. The rolling was unidirectional except for an inadvertent reversal at 0.061 in. thickness. At this thickness, and also at 0.040 in., the rolling was interrupted for transmission Laue photographs. Molybdenum Ka-radiation filtered with zirconium was used in a transmission method1' to obtain the cold-rolled (110) pole figure. The sample was a 0.002-in.-thick section taken from the central region of the 0.022-in.-thick cold-rolled crystal. For the primary recrystallization study, cold-rolled samples were etched from 0.022 to 0.021 in. thick and annealed in hydrogen at 850°C. Primary recrystallization to a fine-grained structure, Fig. 1, was obtained in a 5-min anneal. Eleven sheets after

Jan 1, 1963

Jan 1, 1908

Graham Macfarlane, Louisville, Ky. (communication to the Secretary*):—In the paper by S. Whinery under the above caption mention is made of the occurrence of Clinton iron-ore in Kentucky and Tennessee. I believe that this is really a ferruginous limestone in what the Tennessee Geological Survey calls the Fernvale formation. In Davidson and Sumner counties, Tennessee, this occurs at about the horizon stated by Mr. Whinery. The maximum thickness of the deposit is from 10 to 12 ft., but it averages between 6 and 8 ft., lying practically horizontal. The Red River Furnace Co., under my direction, opened a mine in the Fernvale " red rock" near Goodlettsville, Tenn., several years ago. When it was first found we assumed it to be Clinton ore, but the absence of the characteristic Clinton fossiliferous structure and other evidence satisfied us that it is really limestone saturated with iron oxide. I think the very low ratio of SiO2 and Al2o3 to iron content as compared with the usual ratio in the Clinton ore is also evidence in favor of its being the Fernvale. The Tennessee Geological Survey states that at outcrops where this ore has been leached it carries about 44 per cent. of iron; under cover, from 20 to 25 per cent. of iron and from 3 to 6 per cent. of silica, the remainder being chiefly calcium carbonate. Its phosphorus content is irregular and generally rather high for a foundry-iron mixture. Since it is more than self-fluxing, we have at times operated with a mixture of brown hematite and red ore with no limestone.

Jan 1, 1913

The Institute conducts jointly with the American Society of Civil Engineers, American Society of Mechanical Engineers and American Institute of Electrical Engineers, certain activities as listed below, and is joint owner with them of certain properties. United Engineering Trustees, Inc. When Mr. Carnegie made his gift which made possible a home for the engineering societies, a separate corporation was organized to act as a holding company and to manage the common property. This was long known as the United Engineering Society, but the name has now hen changed to one which more nearly reflects the real function of the corporation. It holds title to the Engineering Societies Building and to various funds placed in its charge and is managed by a Board of Trustees, of which three are chosen by each of the four societies, American Institute of Mining and Metallurgical

Jan 1, 1932

By F. Louis Grammer

THE difference between blast-furnace gas and ordinary producer-gas is chiefly that blast-furnace gas is richer in CO, and poorer in hydrocarbons and hydrogen, as is shown in Table I. TABLE I.-Volume-Composition of Producer-Gas and Blast-Furnace Gas.. Producer-Gas. Blast-Furnace Gas. Per Cent. Per Cent. (Volume.) (Volume.) CO . 22 to 33 25.5 00., . 6 to 3 13.0 H . . 13 to 7 1.5 CH, 3 to 1.5 0.0 N . 54 to 60 60.0 If natural gas, water-gas, or by-product coke-oven gas be available, blast-furnace gas can be made to resemble very closely in calorific value the average producer-gas by merely mixing in one of these products, which are richer in hydro-carbons and, hydrogen. Blast-furnace gas, however, possesses a virtue which is sometimes absent in producer-gas, especially with coals very high in sulphur-namely, that blast-furnace gas is relatively free from sulphur. In some regions the sulphur in coal is an acute problem, and it is highly desirable to find uses for the products which are specially high in sulphur-content. An advantage would be gained if coal was coked before charging into the gas-producers, but this adds to the expense. Sulphur may be partly eliminated from coal by washing it, the success depending upon the form in which the sulphur occurs, and upon the efficiency of the washer, but it cannot always be removed to the extent desired at most American plants. It is not practicable to remove all the sulphur from producer-gas by washing it, though Mr. Reinhardt, of Germany,

Sep 1, 1908

By J. L. Whitlock

An attached growth aerobic biological treatment process has been developed at Homestake Mining Co.'s Lead operation which not only oxidizes free and complexed cyanides, including the stable iron complexed cyanides, but also thiocyanate, and the oxidation byproduct ammonia. Through the employment of a mutant strain of bacteria which has been gradually and specifically acclimated to the waste, these potential pollutants are mineralized to relatively harmless sulfates, carbonates, and nitrates. The resultant effluent, through toxicological testing, has been shown compatible with the receiving stream, which serves as a cold water marginal trout fishery.

Jan 1, 1985

By R. F. Mehl, G. V. Smith

THE decomposition of austenite in steels, because of its immense practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1-3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings-pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. PEARLITE Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix .2-5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrongly, as Mehl and Smiths have pointed out, that the lamellae delineate the [210] planes of ferrite.* MARTENSITE It is known that martensite is a transitional constituent of body-centered tetrag-

Jan 1, 1942

By John Richards

MY remarks will be confined to the experience of our company in mining the No. 8 seam of coal in Ohio, although I believe that the relationship existing here between the method of mining and the method of cleaning will hold true in many of the coal seams throughout the country. The increasing demand for a cleaner and better graded product is being felt throughout the entire coal industry, and the methods of mining are playing an important part in the control of various sizes and quality of coal produced. We have found a definite relation between the mechanical loading of coal and its preparation for the market. In the No. 8 coal seam the location of the non-combustible material is regular. The' marketable coal lies in three benches, separated by streaks or bands of impurities. These impurities must be removed from the coal to properly pre pare the product for the market. Where hand-loading methods are employed, the loader removes as much of this non-combustible material as possible at the working face. The impurities that are missed by the loaders are removed as the coal passes through the preparation plant, by means of picking tables. As this method of cleaning cannot improve the quality of the extremely fine sizes, a practice has been established in the company's hand-loading mines, of undercutting the coal about 2 in. above the bottom of the seam, thereby eliminating any possibility of impurities caused by the cutting machines cutting into the rock bottom below the coal seam.

Jan 1, 1934