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By G. E. McElroy

MUCH attention has been directed to mine-air flow in recent years, more especially in Great Britian where there is frequent reference to a theory of fluid flow developed by English engineers. Briefly stated, this theory is that for similar passages of the same relative roughness, in which fluid flow occurs, the conditions of flow are exactly the same for equal values of the product W D V, where W = density of the fluid, D = diameter of the passage through which flow occurs, V = mean velocity of flow, and m = absolute viscosity of the fluid flowing. This, the "Reynolds Criterion" of fluid flow, had its origin in the work of Prof. Osborne Reynolds' more than 40 years ago. Later, Lord Rayleigh amplified the theory2 which has been conclusively proved for small pipes by the experiments of Stanton and Pannel3 over a large flow range, and by Lacey4 over a somewhat more limited range. Concordant results on small pipes have also been obtained by numerous other investigators with single fluids over more or less limited ranges of flow. According to this theory results in one medium, such as water, are immediately applicable to another, such as air; and experimental results on models are (theoretically, at least) applicable to full-scale designs. This is of great importance in aeronautics and can be of considerable value in mine ventilation research. Hodgson, in a recent paper,5 has outlined the application of this theory to mine-air flow and recent English experiments' on the resistance of a timbered mine airway have been expressed in this form.

Jan 10, 1926

By George F. Comstock

It has been known for many years that the alloy containing 90 per cent. copper and 10 per cent. aluminum can be hardened, like steel, by quenching from a suitable temperature, and that the hardened alloy can be softened again by annealing or drawing the temper. It does not seem to be generally appreciated, however, that the effect of the first slight reheating after quenching is actually increased hardness, the softening effect not taking place until a certain temperature of "drawing" has been exceeded. This paper gives the results of a few experiments on various specimens of cast 10 per cent. aluminum bronze, quenched for maximum hardness, and subsequcntly annealed at different temperatures. The hardness measurements were made with both a scleroscope and a standard Swedish Brinell machine; some peculiarities of the scleroscope test on this material are described. The author is not aware of many previous investigations of the hardness of this alloy when quenched and drawn, but two important papers on the subject should be mentioned. The earliest was by Portevin and Arnou,1 in which it was stated that tempering quenched 10 per cent. aluminum bronze at 400" C. increased the hardness as compared with the quenched untempered alloy and that reheating above that temperature ' was necessary to obtain any softening effect. A later paper was by Seidell and Horvitz,2 who mentioned Portevin and Arnou's work, but did not report any increase in hardness obtained

Jan 1, 1925

By B. Egeberg, H. B. Smith

Britannia metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375" I?., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later. The approximate analysis of the metal we investigated was 91 Sn, 7 Sb, 2 Cu, and the molten metal was bottom-poured into an iron mold yielding an ingot 7 3/4 in. wide by 11 in. long and % in. thick, the casting temperature being 800" F. The ingot was cold-rolled to a sheet 0.032 in. thick, sufficiently large samples for experimental purposes being cut from the sheet at intermediate stages. The samples were all tested for hardness with scleroscope and Brine11 machine, then heated to 212" F. for 30 min., and again tested after cooling to room temperature. The same samples were heated successively at 300°, 400°, and 440" F., followed

Jan 1, 1929

By H. B. Smith, B. Egeberg

Britannia metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375" I?., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later. The approximate analysis of the metal we investigated was 91 Sn, 7 Sb, 2 Cu, and the molten metal was bottom-poured into an iron mold yielding an ingot 7 3/4 in. wide by 11 in. long and % in. thick, the casting temperature being 800" F. The ingot was cold-rolled to a sheet 0.032 in. thick, sufficiently large samples for experimental purposes being cut from the sheet at intermediate stages. The samples were all tested for hardness with scleroscope and Brine11 machine, then heated to 212" F. for 30 min., and again tested after cooling to room temperature. The same samples were heated successively at 300°, 400°, and 440" F., followed

Jan 1, 1929

By R. T. Walker

GROUND waters-hot or cold-containing small amounts of the more common earth acids, such as carbonic acid, silicic acid, hydrogen sulfide, sulfurous acid and sulfuric acid, have only a very limited "solvent effect on dominantly siliceous rocks, whether of igneous or sedimentary origin, but in limestone they often form extensive cavities; and such "limestone caves" are the only openings of considerable size and continuity in rock formations that do not owe their existence directly and almost wholly to dynamic action. Limestone caves such as are developing at the present time must have been formed in all past geological ages in which limestone beds existed and where suitable conditions for the development of such caves prevailed; hence it would seem a reasonable expectation that, in the course of geological history, a certain number of ancient limestone caves must have been utilized as channels for the passage of mineralizing solutions, during portions of their course, at least, and that, in consequence, orebodies must have been deposited in such caves. Such a conception is not novel; it was proposed many years ago, but its possibilities, as explaining certain types of ore deposits, have been rather lost sight of in the development of the theory of the metasomatic replacement of rocks by minerals. It is the purpose of this article to assemble evidence to show that many of the orebodies found in limestone beds have been deposited in pre-existing caves; to discuss the criteria whereby such orebodies can be distinguished from others which have been formed along fissures and fracture zones traversing limestone, by the more common method of metasomatic replacement, analogous to orebodies in other formations; and to describe certain orebodies-particularly the "ore channels" of the Tintic district, Utah-as illustrative of the principles discussed. Limestone caves may be divided into two classes: those formed by cold, descending surface waters, which emerge again at some lower elevation as cold springs; and those formed by hot, ascending waters of deep origin or circulation, which attain the surface as thermal springs. Although these two classes are similar in many respects, there are certain characteristic and inherent differences whereby they can usually be distinguished.

Jan 1, 1928

THE preceding chapter has recorded the initiation of mineral industry education during the period 1890-1910 in numerous institutions that had not previously offered it. It should also be emphasized that in many institutions where instruction had begun before 1890, as recorded in earlier chapters, but had not yet become firmly established, this period was one of marked growth and development. This was not universally true, however, for at the Universities of Pennsylvania, Michigan, Illinois, Wisconsin, Washington (St. Louis), Iowa, Vanderbilt and Tennessee, and at the Polytechnic College of Pennsylvania, mineral industry instruction was being dropped during this period, instead of gaining in strength. It is necessary to emphasize this, because writers on the subject have not infrequently attempted to make a much too simple correlation between mineral discovery or production and the intensity of student interest in mineral industry curricula. It would naturally be true that periods of large mineral production would, in general, coincide with cycles of business prosperity, and the latter are conducive to starting new ventures, educational as well as business. It should be equally evident that opportunities for business and professional success might, in such periods, appear to increase at a more rapid rate in industries other than mineral, or in the utilization of minerals rather than in their production. The author has not been able to perceive any simple and clear relation between interest in mineral industry education and mineral discovery, production, and utilization, or general business prosperity. On the contrary, the more the problem is studied the more complex the factors involved in it appear to be. In a later chapter an attempt will be made to analyze them in more detail

Jan 1, 1941

By J. H. Brophy, A. L. Prill, H. W. Hayden

An error lzas been found in the conventional way of determining the time exponent of linear shrinkage for the solution-precipitation stage of liquid-phase sintering. Large amounts of shrinkage due to initial rearrangenzent result in erroneously low exponents and tni si dentification of the rate-controlling process. Two alternative, mathematically correct, methods of calculation are applied to existing data on Fe-Cu, WC-Co, and Tic-Ni-Mo. This results in reidentifi-cation of the rate-controlling process and somewhat better agreement with related data. In each case the solution-precipitation process is solution-controlled and not diffusion-controlled. THE liquid-phase sintering process has been the object of a considerable amount of research for many years. Linear shrinkage vs time data at various sintering temperatures have been used recently in an attempt to identify the prevailing mass-transport processes in a number of metallic and nonmetallic systems. There is an analytical error inherent in the methods previously used for handling data during the "solution-precipitation" stage of shrinkage which must be recognized before the correct rate-controlling processes can be determined. It is the purpose of this paper to show how the error has affected previous conclusions and to suggest corrections. A number of mechanisms have been proposed to explain experimental observations during sintering in the presence of a liquid phase. The earliest of these is due to Price, Smithells, and williamsl who attributed the observed growth of the solid phase to the simultaneous solution of smaller particles and growth of larger particles. From the work of Lenel et al.2,3 and Gurland and Norton4 has come the suggestion that the liquid-phase sintering process may be divided for analysis into three steps: 1) rearrangement upon formation of the liquid phase; 2) solution and reprecipitation of the solid phase in the liquid; and 3) "coalescence" or a final stage of sintering, characteristically slower than the solution-precipitation process. The sequence of steps is shown schematically in Fig. 1. Kingery5 presented a thermodynamic and kinetic analysis of the first two "stages" of the liquid-phase sintering process in which the functional dependence of lineal shrink- age on time at temperature was used to identify the rate-controlling mass-transport process. Table I summarizes the time dependences and processes considered by Kingery.5 This method of data presentation has been employed by Kingery and coworkers for Fe-CU,6 WC-Co, and a number of nonmetallic systems," and bv Whalen and Humenik for Tic-Ni-Mo and Fe-cu.8 In each of these studies, the rate-controlling step during the "solution-precipitation" stage was identified from the slope of the curve in that stage on a logarithmic plot such as Fig. 1. However, in all of the previous studies, at a certain composition, relatively large amounts of shrinkage due to rearrangement preceded the solution-precipitation stage. Under these conditions, the larger the amount of rearrangement shrinkage the

Jan 1, 1965

By Burt C. Mariacher

To note that environmental considerations had a major im¬pact on the minerals processing industry in 1971 would be something less than a profound observation. The degree of its importance was demonstrated by MBD when it established the Environmental Committee as a new unit committee within the Division to achieve greater participation in exchange of information relating to the technologies and problems involved. It is appropriate and necessary to devote special attention to this timely aspect of minerals processing, as its influence penetrates the research, engineering and operations of almost all unit technologies that comprise minerals processing. The pollution abatement aspect of this industry has been such a dominant factor in recent years there is reason to wonder whether progress in unrelated technologies has been curtailed. Perhaps so, to some degree, but unit committee reviews presented in this article suggest rather that it would appear to have served as a catalyst for accelerated progress in development of new methods and improvement in more conventional ones. Present concepts regarding primary metal or mineral recovery and by-product potential may change considerably as a result of improved technology in waste product treatment.

Jan 2, 1972

By Henry Rawdon

THE structure of wrought iron as usually described by metallographists and workers in metal in general is that of a fairly pure iron. Impurities, if present, are usually considered as being in solid solution in the crystals of the ferrite matrix or as forming part of the ever present "slag streaks." Attention is herein directed to one type of these dissolved impurities; to the detection of such impurities, particularly in low-grade irons, and to their possible influence on the physical properties of the metal. The attention of the Bureau of Standards was first directed to wrought iron of the peculiar and unusual characteristics to be described later, in material which had failed in service and was submitted for test. The examination was extended to other grades of wrought iron, to see whether such features are of common occurrence in this class of material. MICROSTRUCTURE OF WROUGHT IRON Usual Structure The general microstructure of wrought iron is so well known that a detailed description of it here is needless. There is shown in Fig. 2 the structure of a sample of Swedish iron which illustrates well the matrix of ferrite crystals in which are embedded the slag threads so characteristic of the puddling process and the subsequent working of the material. The usual commercial product contains varying amounts of the impurities commonly associated with iron and steel, i.e., manganese, phosphorus, silicon, and sulphur together with small amounts of carbon. Of these, the larger part of the phosphorus and some of the silicon present are held in solid solution in the ferrite while most of the remaining impurities, other than carbon, exist in the inclosures of slag. Aside from the discontinuities introduced by the slag streaks the ferrite matrix has the microstructure and appearance of a pure metal. No definite orientation of the various crystals or grains is apparent; deep etching of the specimens reveals no intracrystalline features (i.e., within the grains) other than those noted in "pure" metals in general (etching pits).

Jan 9, 1917

By Samuel B. Christy

The present paper is a continuation of a study of the reductionworks of New Almaden, the first part of which was published under the title " Quicksilver-Reduction at New Almaden," in the Transactions of this Society, vol. xiii., p. 547.* Frequent reference will be made to some of the data there given. The following is an outline of the contents of this paper: I. Condensing appliances used at New Almaden: a. Brick condensers, b. Iron condensers—flues and " water-backs," c. Glass and wood condensers, d. Friction-coudensers—filters and revolving screens, e. Flues, towers, and chimneys. II. Analysis of condensing-systems. III. Temperature of condeusers. IV. Product of condensers. V. Treatment of soot. VI. Losses of treatment: a. Nature of losses, b. Composition, weight, and volume of dry gases, c. Volume of wet gases, d. Specific weight of quicksilver vapor, e. Vapor-loss at various temperatures. VII. Comparison with New Almaden practice. VIII. Comparison with results at Idria, Austria. IX. Comparison with results at Almaden, Spain. X. Future improvements in quicksilver-condensation. I. Condensing Appliances. The complete condensation of mercurial fumes in a large way presents numerous practical difficulties, familiar to all who have had to retort amalgams. In condensing the quicksilver-fumes discharged

Jan 1, 1886

By J. J. Pye, J. B. Drew

The surface-diffusion coefficients of Ni63 diffusing on low-index planes of nickel single crystals have been measured over the temperature range from 400° to 1000°C using a precision autoradio-gvaphic technique. The activation energy for sur -face diffusion appears to he the same on the {111}, {110), and (100) planes and amounts to -0.60 ev. This is in good agreement with the value (-0.62 ev) reported for (111) planes obtained by mass-transport techniques. In an earlier paper, the authors have reported self surface-diffusion coefficients on silver.' In that work, a deviation of the diffusion coefficients from linearity in the Arrhenius plot was observed at high temperatures. This effect was attributed to a loss of tracer atoms into the bulk by volume diffusion. The purpose of the present work was to extend the technique developed to the nickel surface-diffusion system up to the point where volume diffusion would come into play. The nickel system especially lends itself to this technique due to the high efficiency of the isotope in darkening the film and the large absorption of the weak radiation (0.063 mev /3- particle of the trapped tracer atoms. The diffusion coefficients and ictivation energy for different orientations on nickel can also be compared with a report published by Blakely and Mykura 2 where a mass-transfer technique was used. This paper reports the self surface diffusion of nickel on the low-index planes over a wide temperature range using a precision autoradiographic technique. EXPERIMENTAL PROCEDURE The experiment is similar to that described in the earlier publication consisting of a radioactive needle as a source resting on a flat, smooth, chemically polished surface annealed in a dynamic dry-hydrogen atmosphere. The needle is held snugly on the surface by a holder fabricated from commercially pure nickel. The point source is made by grinding down a small-diameter nickel rod until a tip of approximately 0.1 mm radius is formed. It is then etched and the needle tip plated with the radioactive isotope Ni63. Nickel single crystals were used whose main impurities were spectrographically determined as Co 0.05, Fe 0.007, C 0.005, and S 0.003 pct. The surfaces, oriented to within 1/2 deg of the low-index planes, were carefully mechanically polished and etched in a 50-30-10-10 hot solution of acetic, nitric, sulfuric, and phosphoric acids giving a smooth polished surface. The crystals were then washed in distilled water and alcohol. Annealing temperatures ranged from 400° to 1000°C with a furnace arrangement in which the crystals could be brought up to temperature in times short compared to diffusing times. The temperature was maintained constant to ±10°C. In the temperature range investigated, the ratio of the surface-diffusion coefficient to the volume-diffusion coefficient (Ds/Du) was 105 or more and the mean bulk-penetration values, calculated from literature values of volume-diffusion coefficients,3 were on the order of 10-5 cm. After the diffusion anneal, the sintered needle is removed, and both the radius of the needle point and spot left on the crystal face are measured. The crystal is then placed on photographic film. Diffusion profiles are obtained by scanning the film with a recording microdensitometer which has a slit width of 10µ. DISCUSSION AND RESULTS The experimental conditions are such that the source strength and needle radius are essentially constant and the time is adjusted such that the mean bulk penetration is small. An exactly analogous heat-flow problem has been considered by Carslaw and Jaeger4 and the solution can be written in integral form as:

Jan 1, 1964

By Thomas Fraser, Alvaro Abreu

The work described in this paper was carried out under the sponsorship of the Foreign Economics Administration and in cooperation with the Departamento Nacional da Produggo Mineral, Rio de Janeiro. The project was undertaken to obtain complete data on the variations in washability of coal to be used for coke manufacture in the steel industry and to determine the economy of preliminary hand-sorting operations. The coal-producing industry of Brazil is in that pioneering stage in which operating practices and methods are just being developed. Increased wartime demand for fuel, coincident with a drastic curtailment of foreign supplies due to lack of shipping facilities, has put a tremendous pressure on the national industry to furnish more coal. Under this incentive, production facilities are being -expanded- and new methods of operation are being tested. Such changes are being developed both by improvement of existing methods that originated in the field and by adaptation and modification of methods introduced from the United States and Europe. These mining conditions and mining practices in Brazil are typical of what the American mining engineer will find in many instances when he goes pioneering into the developing coal fields of the Southern Hemisphere. The producing coal fields of Brazil are all in the southern states of that country. The coal measures are in a band roughly paralleling the coast and extending in a generally southwesterly direction from northern Sao Paulo through the states of Paraná, Santa Catarina and Rio Grande do Sul to near the Uruguayan border in the vicinity of Bajé. The accompanying map1 (Fig. I) shows the general location of these fields and also the principal routes of movement of both national and imported coal in a late pre-war year (1940). Statistical data on production by states up to that year are given in Table I. Rio Grande do Sul is still the largest producer among the coal states; but wartime

Jan 1, 1947

By Alvaro Abreu, Thomas Fraser

The work described in this paper was carried out under the sponsorship of the Foreign Economics Administration and in cooperation with the Departamento Nacional da Produggo Mineral, Rio de Janeiro. The project was undertaken to obtain complete data on the variations in washability of coal to be used for coke manufacture in the steel industry and to determine the economy of preliminary hand-sorting operations. The coal-producing industry of Brazil is in that pioneering stage in which operating practices and methods are just being developed. Increased wartime demand for fuel, coincident with a drastic curtailment of foreign supplies due to lack of shipping facilities, has put a tremendous pressure on the national industry to furnish more coal. Under this incentive, production facilities are being -expanded- and new methods of operation are being tested. Such changes are being developed both by improvement of existing methods that originated in the field and by adaptation and modification of methods introduced from the United States and Europe. These mining conditions and mining practices in Brazil are typical of what the American mining engineer will find in many instances when he goes pioneering into the developing coal fields of the Southern Hemisphere. The producing coal fields of Brazil are all in the southern states of that country. The coal measures are in a band roughly paralleling the coast and extending in a generally southwesterly direction from northern Sao Paulo through the states of Paraná, Santa Catarina and Rio Grande do Sul to near the Uruguayan border in the vicinity of Bajé. The accompanying map1 (Fig. I) shows the general location of these fields and also the principal routes of movement of both national and imported coal in a late pre-war year (1940). Statistical data on production by states up to that year are given in Table I. Rio Grande do Sul is still the largest producer among the coal states; but wartime

Jan 1, 1947

By Richard W. Smith

KYANITE, long known to occur in Georgia, did not excite commercial interest until about 1930. Investigations revealed two main types of deposits: (1) separate kyanite crystals embedded in mica schist; and (2) crystal aggregates of kyanite associated with quartz in small and very irregular veins. The second kind at first sight appeared to be the best source of supply. Large boulders or dornicks of kyanite with more or less quartz were found on the surface at many places throughout the Piedmont and Highland sections of the state, but prospecting failed to disclose a sizable vein. These dornicks seem to be a surface accumula-tion from small veins or lens-shaped masses not more than one or two feet thick, and with a horizontal extent of not' more than a few feet. The larger surface accumulation of kyanite dornicks, where not too badly stained by iron oxide, may prove to be marketable, but it is extremely doubtful whether a vein large enough to mine will ever be found. In 1932 deposits of the kyanite-mica schist were known to occur in two places northwest of Clarkesville, in Habersham County. In 1934, at the request of and in cooperation with the Georgia Geological Survey, the United States Geological Survey made a thorough investigation2 of the deposits and found that the two known areas of kyanite-mica schist in Habersham County were but a part of an unsymmetrical, U-shaped belt (Fig. 1) with a western limb extending into Rabun County and somewhat longer than the eastern limb. The total length of the belt is about 30 miles. The width of outcrop ranges from 100 ft. to 1/4 mile or more. Deposits of kyanite-mica schist of very doubtful commercial importance were found in several other counties. Only the deposits of this kyanite-mica schist belt in Habersham and Rabun counties will be discussed in this paper.

Jan 1, 1936

By V. A. Josendal, J. W. Wilson, B. B. Sandiford

Two radioactive tracers have been tested as a means of determining core saturation in multiphase flow studies. Cesium chloride was tried as a water-phase tracer, but complications in its use in low permeability cores resulted from sorption of cesium by the core or water-wet pads. IodoI3'ben-zene proved very satisfactory as an oil-phase tracer. The synthesis of iodobenzene from the sodium iodide as received from Oak Ridge is simple and direct. The tracer is insoluble in water and there was no evidence of sorption by any of the core materials used. use of the method to determine saturation profiles during capillary and dynamic desaturations and relative permeability measurements on oil-water and oil-gas systems is described. Comparisons of the dynamic and capillary methods of relative permeability determination were made using the tracer to check core saturation and saturation distribution. Other experiments are also described in which mobility of the oil phase at various saturations was measured by displacing labeled oil by flowing inactive oil. Similar experiments were made using water labeled with cesium 134. INTRODUCTION To be fundamentally sound. any laboratory method of determining relative permeability must meet, among others, the following requirements: (1) the core saturation between the pressure taps must be uniform, and (2) there must be uniform pressure difference between the phases in the region between the pressure taps. In practice it may eventually be shown that appreciable departure from either or both of these conditions may be permitted without introducing sensible error. but the magnitude of such error remains to be established. There is need then for methods of saturation determina- tion which will determine the saturation profile in a core as well as the overall average saturation given by the gravimetric or material balance methods usually employed. Methods which have received consideration include resistivity, X-ray absorption, gamma ray absorption, neutron diffraction, and radioactive tracers. The resistivity method has use in the determination of profile, but needs checking by independent means.' The X-ray method has been used successfully, but requires elaborate equipment and calibration.23 4 At present gamma ray absorption is practical only for very large cores. The neutron methodo does not appear adaptable to measurement of saturation variations in short cores since it is a scattering method. Russell, Morgan and Muskat' employed radiovanadium in a study of the mobility of interstitial water. Coomber and Tiratsook used radioiodine as an oil-phase tracer and measured profiles in unconsolidated sand packs. ADVANTAGES OF RADIOACTIVITY METHOD A thorough discussion of the theory of radioactive tracers and the technique of using them to study the movement of fluids in sands is given by Coomber and Tiratsoos and need not be detailed here. The method requires less equipment than the X-ray method; the counting problem is similar, but the generation and regulation of the radiation, which is a major problem in the X-ray method, is not required in the radioactivity method. In the X-ray method it is customary to add up to 20 per cent of absorber, usually an iodine compound, to the phase to be labeled. while in the radioactivity method a mere trace is sufficient. A possible disadvantage of the radioactivity method is that a disproportionate amount of the activity comes from the portion of the core nearest the counter, whereas the X-ray gives a true average saturation in the region traversed by the beam. 011 the other hand, this characteristic of the radioactivity method renders it peculiarly adaptable to study of certain types of radial variations in saturation. As with the X-ray method, a tracer may be added to either the oil or water-phase. An oil-phase tracer is more generally useful. however. since it permits work on oil and gas in the

Jan 1, 1952

By Hugh Steele, Brower Dellinger

U. S. mining trends for 1956 continued steadily U+ S. uphill, technique and equipment advanced with the pull, and exploration and development of once mined districts attracted more attention than new areas. Expansion of the Ambrosia Lake district in New Mexico more than doubled known uranium ore reserves, and production began from several of the large new ore discoveries. In Canada the up trend was more spectacular, especially in exploration and development. To combat increasing problems arising from high labor costs, taxes, low grade orebodies, and dwindling discoveries, manufacturers and mining companies have continued to introduce new techniques and new products-reamer bits for enlarging small holes drilled by jacklegs, whup d'whups for drift mucking, Cryderman machines and over-the-head small crawler-type machines for shaft mucking, the 20-ton TL 220 four-wheeled tractor trailer unit for underground haulage, inertia-type dust collectors, roof bolting in conjunction with chain link fencing for wall support, wooden roof bolting using compression support of ground for wall support, and new one-use carbide bits.

Jan 2, 1957

By E. A. Gulbransen, J. W. Hickman

ONE of the important factors that determine the resistance of a metal or alloy to further chemical reaction is the structure of the superficial oxide film A thorough understanding of the physical and chemical structure as well as the stability of the oxide film formed on the surface as a function of time and temperature of the chemical reaction might furnish clues as to the nature of the reaction process and the protective nature of the film A comprehensive program has been undertaken to study these phenomena This paper summarizes the structure of the oxide films formed on the metals iron, cobalt, nickel, chromium and copper at temperatures up to 700°C Before the introduction of the electron diffraction technique, it «as necessary to use either direct chemical analyses or X-ray diffraction analyses to determine the nature of the oxide film formed on the metal or alloy Chemical analyses yields information on the percentages of the several atomic species present in the film while X-ray diffraction analyses yield information on the atomic geometry In special cases the information obtained may be identical, but in general both view-points are necessary Much of, the early work was carried out on the oxidation of bulk samples where thick films were obtained The products were identified after cooling to room temperature by X-ray diffraction and chemical analyses Although much useful information has been obtained in this manner, little could be learned about the character of the protective oxides during the period when the films were actually protective Evidence concerning the chemical structure of thin oxide films has been made possible by the development of the electron diffraction reflection technique In this method the most fruitful investigations have been made by carrying out the reaction in situ at the temperature at which the film is actually protective LITERATURE The oxidation of iron has been extensively investigated by X-ray and electron diffraction Jackson and Quarrell1 found that oxide films formed and examined at the same temperature differed considerably from those allowed to cool to room temperature The results showed that below 400°C the oxide that was stable in intimate contact with iron was Fe304, between 515° and 900°C the stable film was FeO Above the upper change point of iron the oxide was found to be Fe304 prom 400° to 515°C , FeO, Fe304 or a mixture of the two oxides was found Recrystallization of the air-formed film below 400° and above 900°C led to the formation of Fe304 In the range where thicker films consisted of FeO, the air-formed film was converted to a new hexagonal oxide not previously described

Jan 1, 1946

By Walter V. Knopp, Laurence Delisle

INTRODUCTION THE aim of this work was the preparation of nickel-steels from elemental metal powders by powder metallurgy techniques. It was known that plain carbon steels could be made from a mixture of iron powder and graphite and that the effect of carbon on iron in powder form was of the same nature as that produced in fusion metallurgy. The problem in making nickel steels from elemental powders consisted therefore in finding out whether sufficient diffusion of the nickel and other incidental metals normally present in such steels could be induced in the solid state to modify the properties of plain carbon steels made from powders and produce the beneficial effect of alloying. The composition selected originally was that of an S.A.E. 2330 steel. Metal powders, in the proportion corresponding to that composition, were mixed with graphite, pressed, and heated at different temperatures for different periods of time, to produce bonding of the metal particles and mutual diffusion of the various elements without melting. Temperatures up to 1325°C and sintering periods as long as 6 hr were first investigated because it was expected that such conditions would produce maximum diffusion with an accompanying improvement in the properties of the alloy. It was found that, although diffusion proceeded to a large extent under the conditions investigated, it would not be complete unless sintering were carried out at a high temperature for much longer than 6 hr. Relatively high temperatures and long sintering times are objectionable from a practical point of view, particularly when a low cost material is to be produced, because they necessitate the use of special, costly equipment. Work could be done to improve the diffusion of iron and nickel by changing conditions other than the sintering temperature and time, i.e., finer primary or alloy powders could be used. However, a marked change in the properties of the steel had been observed even with only partial diffusion. It was thought, therefore, that instead of trying to improve the diffusion, advantage might be taken of its incompleteness to produce a special structure consisting, in the unquenched condition, of a hard constituent, rich in nickel, dispersed in a tough pearlitic matrix. Steels with such a structure, not readily obtainable by fusion, should have desirable mechanical properties. Besides, it should be possible to prepare them from elemental powders under economical conditions. This latter alternative was therefore adopted for the second phase of this work. This report is divided into four parts: 1. General Procedure. 2. Effect of Sintering Temperature. 3. Effect of Varying the Nickel Content. 4. Effect of Alloying Elements. GENERAL PROCEDURE The general technique of cold pressing as used in powder metallurgy was applied.

Jan 1, 1948

By C. R. Kuzell

The Editor desires to call attention to the charts in the paper of the above title which were published in the August Bulletin on pages 2190 and 2191. It was impracticable to include in the Bulletin. charts of sufficient size to be used as working diagrams for the direct determination of operating values, but the Institute is prepared to furnish copies of these charts on a large-size scale, at a moderate cost, to those who desire to have them for this purpose. CORRECTIONS Page 2185, line 3. For "is accessory apparatus" read "in accessory. apparatus." Page 2188. Substitute for lines 11 and 12: Nitrogen, oxygen, carbon monoxide, Cp = 6.50 + 0.0010T Hydrogen, Cp = 6.50 + 0.0009T

Jan 9, 1914

By Nicholas J. Grant, William H. Ferguson, Bill C. Giessen

Ta-lr alloys have been examined over the complete range of compositions using metallographic and X-ray techniques. The terminal solid-solubility limits, solidus temperatures, and intermediate phases were determined. There are four inter-mediate phases: o, tetragonal, analogous to a (Fe-Cr); 0,. orthorhombic; az, tetragonal; and a TaZr,, cubic, AuCu, structure. Of these, o and a, melt peritecticaLly, a, decomposes peritectoidally, and a TaIrs has a congruent melting point. Three peri-tectic and one eutectic reactions occur. 1 HE Ta-Ir phase diagram has not been treated in the literature. Intermetallic phases and terminal solid solubilities have been described and estimated.'-4 The previous findings have been confirmed in this work. A complete diagram with additional phases and solidus curves is presented. EXPERIMENTAL METHODS Starting materials were tantalum powder of 99.8 pct purity, supplied by the National Research Corp., Cambridge, Mass., and iridium powder of 99.9 pct purity, supplied by the Bishop Co., Malvern, Pa. Both powders were -200 mesh. Table I lists the analyses as given by the suppliers. A standard procedure was employed in making the alloy buttons, which was described in detail in Refs. 5 and 6, and which included repeated arc-melting of powder compacts and determination of the composition by the weight-balance method. This is especially justifiable due to the similar vapor pressures of tantalum and iridium. In the critical parts of the diagram, a spacing of 1/2 at. pct was used, based on premelted master alloy material. The observed structures and X-ray spectra were consistent with the composition sequence of the alloys. Table II lists the final alloy atomic percentages with the calculated percent error of composition. Cross sections representative in grain size and composition were selected for the study, as described in Ref. 5. Based on prior experience, no contamination from the tungsten electrode was considered. Temperature measurements were obtained using a Leeds and Northrup optical pyrometer and have been described extensively in Refs. 5 and 6. All heat treatments were made in the high-vacuum tantalum tube furnace mentioned in Ref. 5. Samples annealed in tantalum containers cooled from 1800" to 1000"~ in 5 sec; those annealed in ceramic crucibles cooled over the same range in 15 to 30 sec. The thermal treatments are listed in Table 111. All specimens were homogenized at 1735°C for 24 hr. Tantalum-rich compositions were treated in tantalum buckets. Iridium-rich compositions were annealed in tantalum buckets below the eutectic temperature of 1950°C; up to 2200°C, tungsten-lined tantalum baskets were used; and above 2200°C thoria crucibles were used. It was found that refractory oxides (in early stages of the investigation alumina crucibles were used up to 1800°C and thoria crucibles were used to 2400"~) give off minute amounts of oxygen and thereby influence the microstructure considerably, or react directly with the alloys.

Jan 1, 1963