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By Ben-Zion Weiss, Melvin R. Meyerson

Chromium diffusion coatings on commercial Armco iron lead to carbide precipitation at the grain boundaries in and below the coatings. High compressive stresses are introduced into the coating and, as a result, tensile stresses are introduced into the base material below the coating. In coated samples, fatigue cracks form at the grain boundaries below the coating after only a limited portion of the total lifetime (5 to 10 pct). Residual tensile stresses and a stress concentration caused by precipitated carbides seems to be responsible for early crack nucleation. Stage I of Propagation may be divided into two substages: I-a in which the crack Propagates along grain boundaries, and I-b in which the crack propagates along slip boundaries according to a shear mode. In uncoated samples, the cracks form at slip bands after 40 to 50 pct of the total lifetime. In coated samples the Propagation process takes longer than in uncoated samples because of the moderate rate of crack extension until the crack breaks through the coating. The chromium-diffusion coating causes little if any increase in fatigue life. CHROMIUM diffusion is one of the most popular processes used to apply coatings to iron alloys. This popularity stems from the fact that the diffusion treatment is comparatively easy to carry out, and it improves certain surface properties such as corrosion and wear resistance as well as some other properties. Very little effort has been devoted to the investigation of the effect of chromium-diffusion coatings on mechanical properties and particularly on fatigue properties. Since the chromium coating usually represents a small fraction of the total volume of the base material it is generally assumed that the macro properties are dependent principally on the base material rather than the coating. Insofar as fatigue is concerned, there are indications that the fatigue life of the chromium coating is not less than that of the basic material and the fatigue properties are generally not reduced by it.' But chromium diffusion causes drastic structural and chemical changes in the region of the material surface2-4 which introduce additional residual stresses. Such changes must affect fatigue crack nucleation and may sometimes affect the initial stages of propagation. Furthermore, it is conceivable that the secondary stages of the crack propagation could be influenced by some irreversible structural changes in the core of the material, which stem from the long-time heat treatment at high temperatures required to apply the coating. This paper analyses the structural and compositional changes produced in commercial Armco iron by a chromium-diffusion coating and the effect of the coating on fatigue crack initiation and propagation. EXPERIMENTAL PROCEDURES The investigations were carried out with commercial Armco iron. The chemical composition of the iron, the number of specimens tested, the grain size produced during chromizing and heat treating, and the thickness and microhardness of the chromized layers are shown in Table I. Samples were chromized by a gas diffusion process. The temperature and time of the diffusion coating process were chosen according to a previous grain growth study. It had been found that at a temperature of 970°C and a holding time of between 3 and 9 hr there are practically no changes in grain size. To describe the grain size more accurately the ASTM method5 was supplemented by a statistical analysis of the mean volume diameter as outlined by Fullman6 and The The mean volume diameter was deter- mined from D = p/2m where D is the mean volume diameter, and m is the mean reciprocal value of grain diameters as seen on the micrograph. The shape and the size of the asymmetrical sample, see Fig. 1, were chosen so as to facilitate the study of fatigue crack initiation. Before coating, the samples were machined and the surface of the groove was polished. After chromizing, the two side surfaces were machined and polished so as to retain the coating only on the top surface of the groove. Residual stress in the chromized layer was measured on the top of the grooved section of the specimen after the diffusion process. The inclined incident X-ray beam procedure was used.9'10 The computations were performed with the initial assumption of a zero surface normal stress component. An electron microprobe analyzer was used to obtain the relative amounts of chromium and iron con-

Jan 1, 1970

UNIVERSITY OF ALABAMA University, Ala Mining and Metallurgical Society G T Bator UNIVERSITY OF ALASKA College, Alaska Mining Society Earl H Beistline-

Jan 1, 1952

By N. J. Grant, D. Carne, J. B. Seabrook

IT is unnecessary to review much of the literature on hydrogen embrittlement of steel since several excellent reviews and bibliographies exist.1-3 Hot acid pickling and cathodic charging have been known to cause hydrogen embrittlement of steel and have been used as laboratory methods to charge steels with hydrogen.4-8 Experimental Procedure The problem of prime concern in all instances, except in the work of Sims and coworkers,10 is that at no time was there a definite known hydrogen value reported which could be related to a particular value of the degree of embrittlement. It was the purpose of this research to determine the relationship between hydrogen content and degree of em-brittlement quantitatively. The 1020 stock used for the specimens was hot-rolled 7/16 in. diam rod of the following analysis: 0.19 pct C, 0.40 pct Mn, 0.012 pct P, 0.036 pct S' Vacuum-fusion analyses for nitrogen and oxygen gave 0.014 pct O2 and 0.0011 pct N2. Cathodic charging was used to cause embrittle-ment. The advantages of this method were that no quenching was necessary, the impregnation was reasonably controllable, and representative samples for analysis could be prepared simultaneously with the charging of the tensile bars. Analyses for hydrogen were made in a vacuum-fusion type of apparatus which extracted gas from the samples by fusion in a molten tin-iron bath' This apparatus, which has recently been described in detail elsewhere, will not be discussed here.". " Consecutive samples can be analyzed every 15 min with an accuracy of 0'03 ppm. A A from an electrolytic or pickling bath can be charged for analysis in about 3 min, and analysis completed in 15 min. Samples of as-received 1020 stock were analyzed and found to contain a negligible amount of hydrogen (0.06 ppm). Preliminary pickling and electrolytic charging gave highly variable results. Cold-worked samples showed higher values but ranged from 0.6 to 6.0 ppm of hydrogen. Charging at 90°C gave higher values of charged hydrogen, but troublesome films on many of the specimens resulted. It was not until a few drops of a catalytic poison, prepared from 2 g of yellow phosphorus dissolved in 40 ml of carbon disulphide,8 was added to the electrolytic cell that fairly consistent high values of hydrogen could be charged into the as-received 1020 steel at room temperature. The cell used is sketched in fig. 1. The anode and fixture for the tensile specimens were fastened to the cell cover as shown, and the specimen was screwed in place, centrally located with respect to the anode. At first, anodes of lead and graphite were tried, but they contaminated the electrolyte and gave a slight deposit on the specimen. Later, a platinum wire was used in the form of a uniform helix. A current of 2 amp, corresponding to about 0.5 amp per sq in. of cathode, was used for most specimens. The electrolyte was 4 pct H2SO4 solution. Fig. 1 shows the form of the special tensile bar, the main portion of which was an ordinary 1/4 in. diam, 1 in. gauge length test bar, except that two to four small cylinders of stock were left attached by small links to the bottom end of the tensile bar for the purpose of providing samples for hydrogen analysis. Thus the bars and samples were charged with hydrogen simultaneously and an analysis could be made while the bar was being tested mechanically. Experiments were performed to determine how representative the test cylinders were of the middle of the test bar proper. While the bar center was being analyzed, the small cylinder was stored in dry ice, since it had been shown that such storage prevents loss of hydrogen for many hours.12 The results of these checks are shown in table 1. The checks are very good (0.3 ppm) and indicate that it is permissible to use the small end cylinders to establish the hydrogen content of the tensile test bar proper-

Jan 1, 1951

By A. A. Brant

Mining men, quite as exploration minded as petroleum interests, are in the position where most of the exposed crustal portions of the earth have been examined, where the demand for metals is high and likely to continue so, and yet where, perhaps, the tools fail for the economic exploration of many of the possible mineral areas more deeply covered with drift, alluvium, and later formations. At the same time the incentive exists to create acceptable substitutes for many of the duties of metal. The problem of the economic exploration of possible mineral-bearing areas is hence a vital one. In oil exploration, the absence of surface or shallow occurrences and the high cost of test drilling has led to the intensive study of geophysical techniques. Hence the development of the seismic method with its high certainty factor and its adaptability to standardized procedure.

Jan 1, 1949

J. K. EVELETH, Anaconda, Montana (Communication to the Secretary): Partly for the reasons which Mr. Jones enumerates, and partly because of the presence of copper in greater or less quantities in so large a proportion of the ores throughout this region, I have also found Marguerite's method the most convenient and satisfactory for the determination of iron. In order to avoid the previous precipitation of the copper with H2S on the separation of the iron by means of ammonia, with the consequent necessity for re-precipitation

Jan 1, 1889

By Arthur C. Simmons

The State of Pennsylvania produces approximately 60 per cent of the total production of Pennsylvania Grade oil, and naturally represents the dominant factor in the area producing that grade. The producing area comprises the states of New York, Pennsylvania, West Virginia, and a small part of Ohio. The importance of this area is too commonly neglected because it produces only 2 per cent of the total amount of crude produced in the United States. It is, of course, unimportant in its percentage of total crude production, but extremely important for its production of lubricating oil. The lubricating fraction from a barrel of Penllsylvania Grade crude oil represents about 22 per cent of the total, whereas the lubricating fraction from the total United States production represents only about 2.5 per cent of the crude oil. The Pennsylvania Grade area produces about 6,000,000 bbl. of lubricants, which is 15 to 20 per cent of the total produced in the United States. All Pennsylvania Grade lubricants are classified as "high-grade," and with a production of 15 to 20 per cent of the total lubricants, it appears probable that the Pennsylvania Grade area accounts for 25 to 50 per cent of the high-grade lubricants produccd in the United States. Production Bradford Field The production figures quoted in Table I apply only to the part of the Bradford held that lies wholly within the state of Pennsylvania; approximately 15 per cent of the Bradford field is in Cattaraugus County, New York, and 10 per cent of the production is obtained from that sector. The Bradford-field production in 1941 was 12,729,900 bbl. as compared with a production in the year 1940 of 12,748,279 bbl., or a reduction of 18,379 bbl. The year 1941 represents the fourth successive year in which production in the Bradford field has declined. All of the production from the Bradford field is obtained by water-flooding methods and increases or decreases in production are due more to economic factors than to any physical limitations of the pool, inasmuch as additional drilling of water-intake and producing wells would increase the total production of the field. It is apparent that increased drilling of oil and water-intake wells does not take place except under stimulps of a favorable price; and while oil prices during 1941 were moderately favorable, they were not sufficient to prevent a mild decline. Too many wells were drilled in the Bradford field in 1937, but this was compensated by subnormal drilling activities in 1938 and 1939 and a large increase in 1940, The increase in 1941 over 1940 was about 7 per cent. The effect of new drilling is becoming less pronounced on a per well basis because more properties yielding less per acre are being drilled than were drilled in former years. Central and Southern Pennsylvania The production in central and southern Pennsylvania amounted to a total of

Jan 1, 1942

By Arthur C. Simmons

The State of Pennsylvania produces approximately 60 per cent of the total production of Pennsylvania Grade oil, and naturally represents the dominant factor in the area producing that grade. The producing area comprises the states of New York, Pennsylvania, West Virginia, and a small part of Ohio. The importance of this area is too commonly neglected because it produces only 2 per cent of the total amount of crude produced in the United States. It is, of course, unimportant in its percentage of total crude production, but extremely important for its production of lubricating oil. The lubricating fraction from a barrel of Penllsylvania Grade crude oil represents about 22 per cent of the total, whereas the lubricating fraction from the total United States production represents only about 2.5 per cent of the crude oil. The Pennsylvania Grade area produces about 6,000,000 bbl. of lubricants, which is 15 to 20 per cent of the total produced in the United States. All Pennsylvania Grade lubricants are classified as "high-grade," and with a production of 15 to 20 per cent of the total lubricants, it appears probable that the Pennsylvania Grade area accounts for 25 to 50 per cent of the high-grade lubricants produccd in the United States. Production Bradford Field The production figures quoted in Table I apply only to the part of the Bradford held that lies wholly within the state of Pennsylvania; approximately 15 per cent of the Bradford field is in Cattaraugus County, New York, and 10 per cent of the production is obtained from that sector. The Bradford-field production in 1941 was 12,729,900 bbl. as compared with a production in the year 1940 of 12,748,279 bbl., or a reduction of 18,379 bbl. The year 1941 represents the fourth successive year in which production in the Bradford field has declined. All of the production from the Bradford field is obtained by water-flooding methods and increases or decreases in production are due more to economic factors than to any physical limitations of the pool, inasmuch as additional drilling of water-intake and producing wells would increase the total production of the field. It is apparent that increased drilling of oil and water-intake wells does not take place except under stimulps of a favorable price; and while oil prices during 1941 were moderately favorable, they were not sufficient to prevent a mild decline. Too many wells were drilled in the Bradford field in 1937, but this was compensated by subnormal drilling activities in 1938 and 1939 and a large increase in 1940, The increase in 1941 over 1940 was about 7 per cent. The effect of new drilling is becoming less pronounced on a per well basis because more properties yielding less per acre are being drilled than were drilled in former years. Central and Southern Pennsylvania The production in central and southern Pennsylvania amounted to a total of

Jan 1, 1942

By Wolfgang Hermann

The ancit-process of the Eschweiler Bergwerks-Verein, an affiliate Company of ARBED S.A., Luxembourg, was developed in its principles by the Dutch State Mines, Limburg, in the mid-50's with the aim of producing a smokeless domestic fuel on the basis of low volatile hard coal. In 1967, the EBV erected a 10 t/h large- size pilot plant along these principles in the Aachen mining district and further developed the acquired know-how. In hardly 10 years more than 650 000 t of ancit briquettes with unit weights between 17 and 100 grams were produced and in the meantime stream rates of over 85 % of the yearly utilization hours have been reached. In more than 10 blast furnace trial runs involving substitution rates up to 100 p. c. ancit have proved the suitability of ancit as a metallurgical fuel both for a burden with a high and a poor iron content. Construction work for a minor process-step to enable processing of coal with a higher content of volatile matters is finished and first results are expected by summer this year. A pilot plant with a 30 t/h capacity working on a low-volatile coal basis is being planned. Engineering and construction are supervised by MecanARBED. Luxembourg, as responsible contractors.

Jan 1, 1977

By O. W. Simmons, L. W. Eastwood, C. M. Craighead

H. Schwartzbart and W. F. Brown, Jr.—The authors have divided the effects of recovery on the true stress-true strain curve into two types; metarecovery, which effects only the first part of the curve or the yield strength, and orthorecovery, which effects the flow stress at any strain. Both of these are said to be true recovery effects, involve no recrystallization, and are explained by the removal of two different types of imperfections caused by work hardening. However, there seems to be some question as to whether the data are sufficiently conclusive to exclude, as an explanation of the authors' results, a mechanism based on the relief of residual stresses between the grains or slip bands and recrystallization. It appears that metarecovery could be interpreted in the same fashion as a customary interpretation of the Bausch-inger effect. The balanced system of internal stresses which exists between grains in a strained specimen due to varying orientation and, hence, yield strengths, of the different grains is responsible for a reduced yield strength in compression following pre-tension, and, similarly, for an elevated yield strength in tension following pre-tension. If the specimen is now heated so that the internal stresses are relieved by creep, then the yield strength in tension following tension will have been reduced and in compression following tension will have been raised. There seems to be a very strong case for the lack of recrystallization in the aluminum investigated by the authors, if one defines recrystallization as the presence of visually detectable new grains or accepts the X-ray evidence as conclusive. One must remember, however, that the appearance of spots on the back-reflection X-ray patterns cannot be taken as the time when recrystallization first started. The areas of recrystallized strain-free material must first have grown to a size large enough to give distinct spots on the patterns and this may take some time. Averbachl7 in an investigation of brass has shown that recrystallization can be detected by extinction measurements at temperatures lower than those based on hardness or X-ray line width determinations. It can be seen from fig. 10 that the rate of recrystallization is extremely low over a considerable time period at the onset of the process. Observations on the rate at which small amounts of recrystallization effect the flow stress would have given further insight as to whether undetectably small amounts of recrystallization might have been responsible for orthorecovery. Also, the question arises as to whether the effects observed in fig. 6 for various times and temperatures could not have been obtained if the time at 212°F were sufficiently long. In addition, the argument that the curve in fig. 10 is not sigmoidal seems weak in view of the scattering of the points. It is conceivable that an accurate determination of the curve for the first 100 hr would exhibit a relationship other than the one drawn. There is one point we would like to raise about the condition of the starting material. The authors annealed their material at 750°F for 15 min to remove the effects of any previous work hardening or machining strains. Reference to the work by Anderson and Mehl shows that this treatment may not have completely recrystallized the aluminum, so that the starting material may have had some strained areas. Higher temperatures or longer times may have been required to remove the effects of any small strains. We would like to mention some results of tests being conducted at the Lewis laboratory of the National Advisory Committee for Aeronautics in an investigation of the Bauschinger effect in relation to fatigue. Tests were performed on annealed electrolytic copper and several annealed brasses. Specimens were pre-strained 1 pct in tension and then tested in compression or tension with and without intermediate stress-relieving annealing treatments at 500°F for various times. Specimens heated at 500°F for 10 1/2 hr showed an elevation of the flow curve in compression and an approximately equal lowering of the flow curve in tension when compared with the curves for the un-heat treated specimens. After approximately 0.8 pct strain, all flow stresses coincided and were equal to the flow stress of the virgin material at this strain. This behavior is consistent with the metarecovery observed for aluminum by the authors and for which a residual stress model can be used. On the other hand, increas-

Jan 1, 1951

By B. E. Eakin, A. L. Lee

Atmospheric pressure viscosity values For light hydrocarbons were calculated by a simple mixing rule based on the Sutherland constants for pure components. This method was further extended so that the atmospheric pressure viscosity of a mixture may be calculated based on the molecular weight information only. INTRODUCTION A proven method for estimating the gas-phase viscosity of a mixture is the one by Herning and zipperer.l This mixing rule has the following form: One method for calculating the pure component viscosity i is the Sutherland equation,2 which has the following form: The Sutherland constants B and S are determined from experimental data. A set of Sutherland constants for light hydrocarbons based on the data of several investigators3-5 is presented in Table 1. APPLICATION The Herning-Zipperer equation and the Sutherland equation were used to obtain an equation for calculating the gas-phase viscosity of light hydrocarbons. This equation has the form, Eq. 3 was used successfully in the study of methane-n-butane mixtures.6 Further analysis indicated that the Sutherland constants are a function of molecular weight.7 The gas-phase viscosity may be calculated based on molecular weight information only. The following equation was developed: The atmospheric pressure viscosity of ethane, propane, n-butaneand four methane-propane mixtures calculated on the basis of Eq. 6 are compared with the data of other investigators in Tables 2, 3, 4 and 5, respectively. A plot of atmospheric pressure viscosity vs molecular weight based on Eq. 6 is presented in Fig. 1.

Jan 1, 1965

By Hermann Schmalzried, Carl Wagner

UPON heating a metal oxide or sulfide in H2, first only oxygen or sulfur is removed from the surface. Thus the metal/nonmetal ratio in the oxide or sulfide increases and the thermodynamic activity of the metal increases accordingly. For the formation of metallic nuclei, a certain super saturation is necessary, i.e., the activity of the metal must become greater than unity. Once nuclei of the metal have been formed, the supersaturation is supposed to decrease. Even under steady-state conditions of a reduction process, however, the activity of the metal inside an oxide or sulfide phase must be greater than unity in order to have a driving force for the individual steps of the reduction process. As an example, consider the reduction of Ag2S with a high mobility of cations and electrons. As shown schematically in Fig. 1, the reduction process involves the following steps:' 1) sulfur removal along the entire Ag2S surface in form of H2S, 2) migration of Ag' ions and electrons from the Ag2S surface to nuclei of metallic silver, 3) transfer of Ag+ ions and electrons from the Ag2S phase to the metal. For a finite rate of step 3, the activity of silver in Ag2S next to the Ag2S-Ag interface must be greater than unity. Moreover, for a finite rate of step 2, the activity of silver at the gas-Ag2S interface must be still somewhat greater. Theoretical considerations lead to the tentative conclusion that at least under steady-state conditions the supersaturation will be rather low.' To test this conclusion, the average activity aAg of silver in a Ag2S tablet about 2 mm thick with a diameter of 5 mm was followed as a function of time by measuring the electromotive force E of the cell Pt I Ag | Agl I Ag2S I Pt where AgI is used as a solid electrolyte in which only Ag+ ions are mobile. The activity aAg is calculated as aAg=exp(-EF/RT) Since the diffusion coefficient for transport of silver in Ag2S is very high (- 3 . l0-2 sq cm per sec),3 the average activity aAg is representative for both the bulk and the surface of the Ag2S tablet. Experiments were conducted at about 400°C. The cell was surrounded by an aluminum block in order to secure a uniform temperature and to eliminate thermoelectric effects. With the help of a potentiometer, first a potential of 0.16 v was applied to the above cell in argon in order to obtain a well defined initial state with a Ag/S ratio close to 2.000.~ Then the cell was disconnected from the potentiometer and a gentle stream of H2 was passed along the Ag2S surface. In view of the removal of sulfur in form of H2S, the electromotive force E decreased within 20 to 30 min to zero corresponding to a Ag/S ratio of 2.003 and became negative, indicating a value of aAg> 1. A representative plot electromotive force E vs time is shown in Fig. 2. The minimum of the electromotive force characteristic of the onset of

Jan 1, 1963

By Arthur Notman

YEAR ago, the Committee on Mineral Economics ventured to predict a more realistic attitude by the public toward the folly of seeking to have more by making less under the guidance of the Blue Eagle. A unanimous decision of the Supreme Court of the United States has now laid that embattled bird to rest. De rnortuis nil nisi bonum. In spite of dire predictions of disaster to follow its early demise, the metal industries and many others have improved substantially. One could name many indications of that improvement, and on the strength of stock-market activities might assume

Jan 1, 1936

By R. E. Grant

THE Cerro de Pasco Railway Co., owned and operated by the Corporation, is a common carrier whose chief functions are transportation of ore and concentrates from the mines at Cerro de Pasco to the smelter in Oroya, and haulage of coal from the coal mines at Goyllarisquisga to the coal washery at Fundicion. Connecting with the Peruvian Central Railway at Oroya, the C. de P. Railway maintains joint, daily freight and passenger service from Lima and the port of Callao to Cerro de Pasco, terminal of the C. de P. main line and gateway to the Huanuco Valley. Extending from Oroya to Cerro de Pasco the main line is a standard-gauge roadbed of 70-lb. rail, 132 km. long with a maximum compensated grade of 2.25 per cent and a curvature of 16°, climbing from an elevation of 12,272 ft. above sea level at Oroya, lowest station on the line, to 14,208 ft. at Cerro de Pasco. The highest point reached by the C. de P. is on the coal branch at Alcacocha where the rails are 14,385 ft. above the sea.

Jan 1, 1945

By R. W. Smith, R. W. M. Lai

Although several recent papers have shown that equilibrium contact angle in dodecylamine solution-quartz systems can often be directly correlated with flotation behavior, it appears that under conditions of relatively high amine strength and pH such a correlation can't be made. Under these conditions, when there are precipitated amine dipoles present, it appears that a dynamic contact angle formed immediately after introduction of fresh gas bubbles into the system is also of importance. The dynamic angle decreases in magnitude as a function of time. Apparently the decrease is the result of changes in interfacial tensions (liquid-gas and solid-gas) as a function of time. Dynamic angles of the type described can't be observed in trimethyldodecylammonium chloride solution-quartz systems. Several recent papers1-3 have shown quite conclusively that contact angle data can often be correlated directly with flotation behavior in cationic surfactant solution-quartz systems. At the same time, Iwasaki, Cooke, and Colombo4 have shown data for a dodecylammonium chloride solution-goethite system where, in the vicinity of pH 12 and a collector concentration of 10" M, 100% flotation occurs when equilibrium contact angle appears to be zero. A clue to this discrepancy can be found in the work by smith2 who reported the occurrence of dynamic, time dependent, contact angles in a quartz-dodecyl-amine solution system at relatively high pH values and at surfactant concentrations greater than or equal to 10-4 M. It was found that under these conditions, if a fresh bubble was brought into contact with a properly conditioned and polished quartz surface, a large angle was obtained. The large angle, however, instantly started to diminish in magnitude, sometimes to a smaller stable angle and sometimes to its complete disappearance. Also, if the bubble was preconditioned for some minutes (or sometimes even seconds) in the same amine solution, the smaller or sometimes zero stable angle was obtained when the bubble was brought in contact with the quartz surface. One is immediately led to the thought that perhaps it is these dynamic angles when they exist, not stable angles, that are of primary importance in flotation. The present investigation attempts to further study the relationship between contact angle and flotation

Jan 1, 1967

By B. L. Dunic, Terkel Rosenqvist

rr has long been suspected that sulphur has a small but finite solid solubility in iron, but up to the present more accurate data have been lacking. The survey given by Hansen' illustrates the divergence of data and opinions. Solubilities between 0.01 and 1.5 pct have been suggested, and opinions vary regarding the effects of temperature and phase transformations in iron on the sulphur solubility. The extent of solid solution and its variation with temperature might be expected to be an important factor in the occurrence of hot shortness in steel. Therefore, the object of the present investigation was to study this problem more systematically. It was furthermore hoped that solubility data for sulphur might contribute to an understanding of the factors which determine solid solubilities in general. Experimental Procedure The present work was based on the measurement of the chemical activity of sulphur in the solid solution by means of equilibrium with a mixture of hydrogen and hydrogen sulphide. When the solid solubility limit is reached, the sulphur activity in the iron becomes equal to that in the coexisting sulphide phase. A gas mixture of a controlled H,S/H, ratio was passed over pure metallic iron heated to a temperature in the range 900" to 1500". The amount of sulphur absorbed by the iron was determined by analysis, and from a plot of percentage of sulphur vs. gas composition the sulphur activity and the solubility limit were determined. As the rate of diffusion of sulphur in solid iron is very small, often several days were needed to be sure that equilibrium conditions had been established. To produce a gas flow with less than 1 pct H,S of constant composition for several days, was in itself a problem. The most satisfactory arrangement was obtained by a continuous synthesis of hydrogen sulphide from the elements. This was done in the part of the apparatus shown to the left in Fig. 1. The hydrogen used was first purified in tank batches by passage through activated charcoal cooled in liquid nitrogen under a pressure of 150

Jan 1, 1953

The following is an extract of the Engineers' licensing law recently passed by the Colorado legislature; it went into force July 10. On the board of examiners are representatives of the four national societies. R. J. Grant, of Denver, represents the American Institute of Mining and Metallurgical Engineers; H. I. Reid, of Colorado Springs, the. American Society of Civil Engineers; H. S. Sands, of Denver, the American Institute of Electrical Engineers; and Frank E. Shepard, of Denver, the American Society of Mechanical Engineering. Within sixty clays after the taking effect of this act the Governor of the state shall appoint a State Board of Engineer Examiners, to be composed of five members, who shall be legal residents of the state of Colorado and who shall have been engaged in the practice of engineering for at least ten years. Upon the expiration of the term of any members other than the state engineer the governor shall appoint their successors for a term of four years, from a list of five nominees elected by the licensed engineers acting in a general assembly called together for this purpose by the president of the board. Such assembly shall be held in the month of January next preceding the expiration of the terms of any members. The Board of Examiners shall adopt all necessary rules, regulations and by-laws to govern its proceedings, not inconsistent with this act or the laws of the state or of the United States.

Jan 8, 1919

By C. H. Mathewson

Discussion of the paper of C. H. MATHEWSON and ARTHUR PHILLIPS, presented at the New York meeting, February, 1916, and printed in Bulletin No. 109, January, 1916, pp. 1 to 50. ZAY JEFFRIES, Cleveland, Ohio (communication to the Secretary*).¬The authors are to be congratulated for this interesting and valuable contribution. The paper as a whole shows very careful experimentation coupled with rare judgment in drawing conclusions. I have been working along similar lines for the last two years with other metals and alloys. In a short conversation with Dr. Mathewson about July 1, 1915, he mentioned the fact that different degrees of cold work greatly affect the temperature of recrystallization on annealing, Later I determined the recrystallization temperatures of iron, mild steel, and copper, with different degrees of cold work and found that the greater the degree of cold work, the lower the temperature of recrystallization on annealing. In the course of these experiments, I conceived practically the same ideas regarding the reasons for recrystallization as those advanced in the article under discussion. After a metal has been reduced by cold work to about one-fourth of its original area, the differences in orientation of different parts of a given grain can be seen plainly at a magnification of about 1,000 diameters. It is interesting to note that in Fig. A, Plate I, the lines of deformation are not parallel. For example,. in the large grain at the lower left corner of the micrograph, if the lines of deformation about 3g in. from the left edge are continued in a straight line, this line will intersect a straight line drawn as a continuation of the lines of deformation on the extreme right of the grain, at an angle of about 20°. Similarly, if the lines of deformation at the extremities of the large grain in the right central portion of the micrograph are extended, the lines intersect at an angle of about 35°. The individual lines of deformation are not straight. In some of these the parts of the broken lines intersect at angles as great as 15°.

Jan 5, 1916

Air-sand Process of Cleaning Coal Discussion of paper by THOMAS FRASER and H. F. YANCEY, presented at the New York Meeting, 1926, and issued, as Pamphlet No. 1561-F, with MINING AND METALLURGY, February, 1926. T. DEVENNY, Edgarton, W. Va.-How near the size of the sand can the coal to be treated be brought? Do you use an 8-mesh coal on that cleaner? J. J. RUTLEDGE, Baltimore, Md.-From the little I have seen of the apparatus in operation, I should say 8-mesh. In my experience in metalmine concentration work, trying to separate different minerals on one jig, sometimes I have succeeded and sometimes not. This apparatus has appealed to me; something of this kind should be useful with the silicates and carbonates of zinc. I think this apparatus has possibilities in metal mining. Recently in our coal field a screen has been introduced for cleaning coal; it is giving excellent service. When I asked the inventor why he did not take it to the metal mines, he said there was a good and sufficient reason, in a patent way. There may be reasons why it would not be applicable for metal mining; but the simplicity of it appeals to me and I cannot see why it could not be so used. T. FRASER (written discussion).-We feel that 8-mesh would be about -the minimum size of coal practicable to treat by the air-sand process. This would depend partly upon the friability of the coal. The more nearly the lower size limits of the coal- approaches the size of the sand, the more .time will be required in screening the sand out of the cleaned coal, which would mean a little more chance of breakage. In regard to the treatment of ores; this would necessitate the use of some heavier mediums than ordinary silica sand, or some other means of making the separation at a higher specific gravity than is required for coal. We are now working on a method of obtaining this effect for the preparation of anthracite coal without resorting to the use of heavier and more expensive material than common sand.

Jan 1, 1927

Alan Stanley (Titanium Dioxide Analysis of Maclntyre Ore by Specific Gravity, P. 971) is currently head of the General Metallurgical Group of the National Lead Co. He has been with National Lead since 1946, after serving with the USAAF as a first lieutenant of engineers during World War II. A native New Yorker, he graduated from Virginia Polytechnic Institute in 1942 with a Bachelor of Science in Chemical Engineering. Since joining National Lead he has been a flotation supervisor, in the high tension pilot plant, and done sinter testing. He is an AIME member and presented one other paper before the Institute, Sintering Characteristics of Minus 65 and 20 Mesh Magnetite. Stanley plays the piano in his leisure moments.

Jan 1, 1952

By I. H. Silberberg, R. L. Reed, O. K. Kimbler

interfacial films have frequently been observed at interfaces between certain crude oils and water. Several investigators have postulated that the presence of these films should influence the efficiency of oil recovery in water drive or waterflood operations. They may also influence the stability of emulsions which are sometimes a problem in petroleum production, and may be a factor in the fonation of paraffin deposits in oil well tubing and flow lines. This paper presents a technique with which a modified Langmuir film balance may be used to study the compressibility and collapse pressure of these natural interfacial films. Experimental data are presented for several nude oil-water systems. Data developed are used to infer the phase state of the film as a function of such variables as rate of reduction of interfacial area, ionic composition of the subtrate and pH of the subtrate. A film of known physical characteristics is shown to have a sinnificant effect on oil recovery from an unconsolidated sand pack. Possible applications of these results to petroleum production are discussed. INTRODUCTION The use of water to displace petroleum from reservoir rocks is of major importance both as a primary and a secondary recovery process. As water invades the rock, oil is completely displaced from some pores and left as a discontinuous phase in other pores. The manner in which water moves from pore to pore is strongly influenced by capillary forces. In view of the complexity of reservoir fluid systems, there can be little doubt that complicated interactions take place at both the liquid-solid and oil-water interfaces. One of the more interesting, and least understood, of the phenomena which take place at the oil-water interface is the formation of interfacial films. These films are believed to result from the adsorption of high molecular weight polar molecules at the interface.l.2 Presence of such molecules may cause a striking alteration in interfacial tension. When the oil-water interfacial area of certain crudes is rapidly reduced, a thin region (film) about the interface assumes the appearance of a solid membrane, and striations, wrinkles and gross distortions may occur. If such a film is solid, it should greatly alter the interfacial tension normally assumed to exist between the oil and water phases. If the membrane is continuous, a solid phase would separate the oil and water. Interfacial films between crude oil and water were observed in 1949 by Bartell and Niederhausers who commented upon the apparent rigidity of the films and their possible importance in the petroleum industry. Morrell and Egloff4 had earlier attributed the extreme stability of emulsions of sea water in fuel oil to very stable asphaltic films. Numerous investigators have observed rigid films in the course of crude oil-water interfacial tension determinations by the pendent drop method. Several investigators5,6,2 have separated inter-facially active materials from crudes and attempted to characterize them chemically. Reisberg and Doscher,2 using Ventura crude, showed the interfacial tension against water (as measured by the pendent drop method) to be affected by aging, contraction and expansion of the interface, and the pH of the water. These investigators attributed the adhesion of oil to a water-wetted surface and the distortions of flow paths in glass capillaries to the presence of rigid films. Dodd7 has studied the interfacial viscosity of adsorbed films and found them to be non-Newtonian in behavior. Craighead and Harvey8 reported a series of displacements in tubes packed with 60 mesh glass beads. They interpreted the results as indicating an effect of stearic acid films on waterflood recovery and imply that natural films may produce similar results.

Jan 1, 1967