Search Documents

By Y. Dardel

Since the first determination of Dumas1 in 1880, many authors have tried to measure the solubility of hydrogen in solid aluminum, or at least the amount of dissolved gas in it. However, the interpretation of the results which have been obtained is still difficult. Sieverts? then Baukloh and Oesterlen,a during their gassing experiments could not determine any solubility of hydrogen in solid aluminum. On the other hand, Portevin, Chaudron and Moreq4 leaving the determination of the hydrogen solubility beyond the scope of their experiments, measured only the amount of gas that they could extract by high voltage positive ion bombardment and found up to 151 cm3 of gas per I00 g of metal. Winterhager,6 by repeated vacuum extraction during severe cold rolling, extracted up to 161 cm3 per 100 g. In both series of experiments, the extracted gas contained chiefly hydrogen with a small amount of nitrogen, carbon monoxide, carbon dioxide and methan. Later, Schmidt and von Schweinitze as well as Chaudron and Moreau7 showed the importance of the adsorbed layer of hydrogen, the extracted quantities being proportional to the surface and not to the weight of the sample, when its cleaning was not perfect. In earlier experiments, Steinhausers extracted from more massive samples nothing but a little amount (< 0. 5 cm3 per I00 g) of hydrogen, carbon monoxide and methane. Thus, according to these experiments the quantity of dissolved gas is probably very small and the effect of the surface could falsify the results of the extraction. However, owing to the care taken by Chaudron and his coworkers, it was clear that all the hydrogen extracted could not come from the superficial layer, or that the links which bound hydrogen to the surface were so strong that the usual method of cleaning could not destroy them. After the main parts of the experiments reported here had already been carried out, Eborall and Ransley9 published the results which they obtained with an analysor having an accuracy of 0.03 cm3 per I00 g, while that of the usual apparatus was only about 0.2 cm3 per I00 g. During all their experiments the adsorbed layer would have been a difficulty, for the value of the adsorbed hydrogen was approximately equal to that of the dissolved amount. Table i—Amount of Adsorbed and Dissolved Hydrogen (After Eborall and Ransley) Extraction Hz Adsorbed „ h2 dissolved Temperature Calculated Extraction OCcma 500 0.057 0.050 600 0.062 o.096 Since always keeping the same adsorbed layer is very difficult, an error in the correction for the adsorption can be made when using the apparatus of. Eborall and Ransley, as well as the earlier apparatus.

Jan 1, 1949

By M. J. Shulman

An algorithm used by the US Coast Guard to find lost objects is utilized to optimally allocate exploration efforts during initial stages of an exploration program. Based on classical search theory, the algorithm assumes a target probability distribution function, a detection function, and a cost function. The three functions are analogous to delineating areas of possible mineralization, choice of exploration methods, and exploration budget. Application of the algorithm is shown for a hypothetical target distribution. Using the maximum number of field day available as the cost function, the optimal allocation of effort is shown for different exploration methods, e.g. electromagnetic survey and induced polarization. The adaption of the algorithm for the exploration process is discussed.

Jan 1, 1984

By Frederic E. Carter

There have been many attempts to prove that platinum was known to the ancients, but since no traces of the metal have been found in the relics of early times, it must be concluded that it was not known to them. As far as records go, it was actually first discovered in the 16th century in a Spanish mine on the Pinto River in South America; from which source it received its name of Platina del Pinto (little silver from the Pinto). It was more or less of a rarity and was a subject of interest to a few chemists only, until the year 1822 when the metal was first discovered in Russia. In 1819 there were noticed in the washings of the gold sands of the southern part of the Ural Mountains, grains of a heavy white substance, but it was not until three years later that this substance was found to contain platinum. While at first the amounts of platinum brought from the Urals were meager, prospecting soon disclosed rich deposits extending over a considerable area, and nuggets from 10 to 20 lb. were by no means rare. This discovery assured to chemists an ample supply of platinum for their crucibles, etc. The ore is now found in various parts of the world but the richest deposits are still found in the Ural Mountains. The platinum of commerce is obtained entirely from alluvial deposits at depths varying from 6 to 40 ft. The sand and gravel of former river beds are subjected to a series of screenings and washings to effect the separation of the ore. Actually, probably all gold-bearing gravel beds of the world contain platinum, and it is more than likely that large quantities of platinum ore have been thrown away with the black sand washings from gold placer deposits. This is especially true of the alluvial deposits of the Pacific Coast in California and Oregon. Platinum ore is usually found in the form of rounded or flattened grains of "sand," and occasionally in irregular lumps of the size of peas. Large nuggets are very rare. The ore has a metallic luster and is distinguished by its steel gray color, but shows light gray streak when rubbed on a hard white surface; it has a high specific gravity, 16 to 19; is infusible in the hottest blast furnaces, and insoluble in any single acid. Platinum ore is a complex body consisting of the metal in combination with varying proportions of the other members of the platinum group; iridium,

By W. R. Hibbard Jr., R. W. Guard, N. G. Ainslie

Evidence is presented that copper-base solid solutions of different solutes having equal grain sizes, no preferred crystal-lographic orientation, equal electron-atom ratios, and, within experimental scatter, identical initial yield strengths, need not have identical stress-strain curves at strains larger than about 0.04. The stress-strain behavior is rationalized in terms of the proposed Suzuki chemical interaction between solute atoms and extended dislocations using what is thought to be a somewhat different means of representing stress-strain data. ALTHOUGH the effect: of alloying element upon the strength characteristics of sold solutions is a subject which has received considerable attention in the past, the exact relationships between the common deformation parameters and certain common variables are not really known in some cases. As a result some of the experiments reported in the literature in which these variables are inadequately controlled lose some of their persuasion regarding underlying principles. Nonetheless, facts are known which bear pointing up: When the true stress, a, and true plastic strain, E, of tensile deformatic~n are plotted on a double logarithmic coordinate system, one may observe a straight-line relationship at strains greater than 0.02. The form of the curve in the linear region is given by a = Ken! where a represents true stress, E, true strain, and K and tn, constants. If the relationship holds, K and m define the flow characteristics of the material being tested. m and K, however, may vary with other parameters. Hollomon found that in a-brass, m is influenced by grain size. French and HibbardZ found in alloys of copper that inverse relationships existed between m and 1) the solute concentration for a given solute, 2) the 0.01 yield strength, and 3) the constantK. Lacy and Gensamer3 observed (du/d~) (= U/Em) to increase with increasing values of K in systems of alloyed ferrites (although with considerable scatter of data which may be attributed to uncontrolled grain size). Brick, Martin, and Angier* deduced in copper-base alloys a straight-line relationship (with some scatter) between the change in the Dph number due to solid-solution strengthening and the change in the Dph number due to work hardening which suggested that copper-base alloys having equal yield strengths might have identical stress-strain curves in the plastic flow regions. French and HibbardZ concluded that the yield strength of copper-base solid solutions is the proper basis for comparing the effects of solute elements. Also, Allen, Schofield, and ate&apos; showed that, within their experimental variation, copper-base alloys of zinc, gallium, germanium, and arsenic having the same electron-atom ratios have the same true-stress true-plastic strain curves. Dorn, Pietrokowsky, and ~ietz&apos; also found that with aluminum-base alloys the stress-strain curves in the flow regions are approximately the same if "equivalent" concentrations of alloying elements are used. Solute valence and lattice parameter distortion were the parameters used to determine equivalency. The present report describes an investigation in which an attempt was made to obtain copper-base solid-solution alloys of four solute elements having within close tolerances equal grain sizes and yield strengths, and to see if the level of yield strength does indeed define the flow curve regardless of solute type. During analysis of the data certain unexpected features of the stress-strain curves became apparent which gave rise to some speculation and are discussed at length in the paragraphs that follow. EXPERIMENTAL PROCEDURES Alloy Preparation—Using the data of French and HibbardZ as a first approximation, four different binary copper-base alioys were designed so as to have the same yield strength. In addition, other alloys were prepared in which the solute aoncentrations varied slightly from those calculated above so as to span a range of yield strengths, see Table L The yield strengths of all alloys prepared except the copper-tin alloys were subsequently found to Lie fairly close to one another. The copper used in the alloys was produced by the American Smelting and Refining Co. and was of very high purity (99.999 pct). The alloy additions and their initial purities are as follows:

Jan 1, 1960

By James H. Courtright, Kenyon Richard

TOQUEPALA is a porphyry copper deposit in which mineralization is localized by a large breccia pipe formed in close genetic relation to intrusive rocks. The deposit is in southern Peru, 55 airline miles north of the small city of Tacna and the same distance inland from the port of 110. Quellaveco and Cuajone, geologically similar deposits, lie 12 and 19 miles north of Toquepala. Chuquicamata is 400 miles to the south. The deposit is high on the southwestern slope about 20 miles from the crest of the Cordillera Occidental of the Andes Chain. It lies in a mountainous desert where the steep southwesterly slope of the Andes is dissected by a succession of rapidly downcutting, deep canyons. Local topography is moderately rugged with a dendritic drainage pattern and an elevation of 8000 to 14,000 ft. Volcanic peaks along the crest of the Cordillera rise over 19,000 ft. Local precipitation, including a little snow, amounts to about 10 in. during January and February, but general runoff in the region is slight. Throughout southern Peru the springs and streams are widely separated. Crude canals irrigate small farms on terraced slopes along the streams and provide sparse subsistence to the semi-nomadic inhabitants. During the past decade, engineering and geological explorations of the region, as well as the mineral deposits themselves, have required construction of a network of several hundred miles of roads. Before this, roads extended only a few miles inland. Many areas still can be reached only by trail. Toquepala was briefly described in 19th century geographical literature as a copper deposit, and it received desultory attention from Chilean prospectors early in the present century. It was first recognized as a mineralized zone of possible real importance by geologist O.C. Schmedeman during an exploration trip for Cerro de Paso Copper Corp. in 1937. The discovery was late as compared to earlier recognition of Chuquicamata, Potrerillos, and Braden of Chile and Cerro Verde of southern Peru. This was due partly to the region&apos;s difficult accessibility but principally to the obscure character of the outcrop evidence of copper. From 1938 until 1942 Cerro de Pasco Copper Corp. partially explored the deposit by adits and diamond drillholes. This campaign was supplied by a 60-mule pack train continuously shuttling over a 30-mile trail. Northern Peru Mining & Smelting Co., a wholly owned subsidiary of American Smelting & Refining Co., undertook regional engineering stud- ies in 1945 and drill exploration in 1949. According to published data1 the deposit contains 400 million tons of open pit ore averaging a little over 1 pct Cu. It is currently undergoing large-scale development by Southern Peru Copper Corp., which is owned by American Smelting & Refining, Phelps Dodge, Cerro de Pasco, and Newmont Mining. Summary of Geology: The deposit is situated in a terrane composed of Mesozoic(?) and Tertiary volcanic rocks intruded by dioritic apophyses of the Andean Batholith. These formations are exposed in a northwesterly trending belt about 15 miles wide. Along the northeast they are unconformably overlain by Plio-Pleistocene pyroclastic rocks, which occupy much of the crest of the Andes, and along the southwest they are covered by the Moquegua formation of Pliocene(?) age. The mineralized area, oblong in shape and about 2 miles long, has been a locus of intense igneous activity. Several small intrusive bodies having irregular forms occur within and adjacent to a centrally located, large breccia pipe. The mushroom-shaped orebody consists of a flat-lying enriched zone of predominant chalcocite with a stem-like extension of hypogene chalcopyrite ore in depth within and around the pipe. This breccia pipe is relatively large and has been formed by repeated episodes of brecciation. Small satellitic pipes occur at random within a 2-mile radius of this central pipe. These too were individual sourceways of mineralization, although not always of ore grade. Within and around the zone of breccia pipes and mineralization there are a few faults and veins, but these are discontinuous random structures of minor significance. There are no regional or local systems of faults or other planar structures recognized which could account either for the mechanical development of the breccia pipes or for their localization as a group or as individuals. Hydrothermal alteration is pervasive in the zone of mineralization. Clay minerals appear to be abundant in places, but their percentages are undetermined. Quartz and sericite are the principal alteration products, and in many instances original rock textures are obliterated. The principal sulfides, hypogene pyrite and chalcopyrite and supergene chalcocite, occur mainly as vug fillings in the breccia and as small discrete grains scattered through all the altered rocks. Sulfide veinlets are relatively scarce. Sulfides are more abundant and alteration is more intense in certain rock units, such as the diorite and most of the breccias. Although the Toquepala mineral deposit is similar in most respects to the porphyry copper deposits of southwestern U. S., it most closely resembles the Braden deposit of Chile, as described by Lindgren

Jan 1, 1959

By A. B. T. Werner, J. J. Schanz

A survey of the world&apos;s sources and markets for natural graphite and some predictions of future trends are presented here. The authors feel that there is no indication of major changes in sources of graphite over the next few years, but it is possible that the importance of domestic graphites as opposed to foreign carbons may increase in the more distant future. U.S. consumption of natural graphite, which has been in general decline for the past six years, and will probably continue downhill with the virtual disappearance of some markets. However, other markets such as bearings, brake linings and crucibles will probably grow. Natural graphite is the name given to all the naturally occurring mineral forms of carbon that crystallize in the hexagonal system. Natural graphite~ are generally divided into three broad classifications that are based on physical rather than chemical differences — crystalline flake, Ceylon amorphous and other amorphous. Crystalline flake graphites occur as thousands of small individual flakes disseminated throughout the ore and closely resemble shiny black fish scales. Ceylon amorphous graphite is mined from narrow veins of almost pure mineral. It is produced in lump form and often has a coarse platy or needlelike structure. Other amorphous graphites include all those that are extremely fine-grained and have a crystalline structure that is not visible under normal circumstances. In the primary raw material markets, the graphite&apos;s country of origin is also important. Crystalline flake graphites may, for example, be of the Alabaman, Bavarian or Madagascan types; Ceylon amorphous graphite may have originated in Montana or Ceylon; and other amorphous graphites may come from Mexico, Hong Kong or Korea. The distinctions between the graphites from each particular locality are small yet important, for the country of origin will signify certain inherent physical characteristics and will often give an idea of the amount of graphitic carbon contained in the shipment in question. .In certain instances, however, even this is not enough, since the actual mine at which the graphite is produced may have to be known before its true commercial value can be ascertained. Thus, the Madagascar flake graphite shipped from the Sahalambo mines of the Societe des Graphites de la Sahanavo is a thick flake which is known to be especially suited for use in crucibles, while the dull black earthy amorphous material formerly mined at Cranston, R.I., was ideal for stove polish. Synthetic, artificial, electric furnace and manufactured are terms used to describe graphites made from coke. These graphites will be considered in this paper only to the extent that they enter competition with natural graphite. DOMESTIC SOURCES OF NATURAL GRAPHITES Natural graphites have been produced from mines in Alabama, Alaska, California, Georgia, Montana, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, Texas and other states. The exception is the crystalline minerals resembling Ceylon graphite that have come from Montana and the amorphous meta-anthracites from Rhode Island. All the products mined have been flake graphite. In 1960, production was reported only in Texas and Pennsylvania. The Alabama graphite deposits of flake in quartz-mica schists are found southeast of Birmingham in a narrow belt that extends for about 60 miles southwest from Delta in Randolph County to Verbena in Chilton County. Since the long-run prospects for Alabama graphites appear to be fairly bright, especially if regular production of high quality output becomes possible, regional ore reserves of all kinds, including indicated and inferred, are estimated to be of the order of 25 million tons. Of this amount, 14 million tons are of the weathered variety. Alabama graphites are favored by their relative ease of mining, and by the fact that special methods of milling have been developed at the larger properties. In addition, the steady rise in ocean freight rates for Madagascar graphites, the tendency among crucible manufacturers to use flakes of a smaller size, and the possibility of producing other salable byproducts in addition to the graphite are favorable to Alabama producers. Against

Jan 1, 1962

By G. S. Scott, H. G. Turner, W. L. Kleene

It is well known that different forms of carbon show differences in chemical behavior under apparently identical conditions. It is fairly well known that these differences persist, although to a lesser degree, in a single group of carbons, such as the anthracites of Pennsylvania. It is the purpose of this paper to show the extent of these variations for Pennsylvania anthracites from actual quantitative measurements of the amount of carbon dioxide reduced under the standardized test conditions employed. As the amount of carbon dioxide reduced to the monoxide (under comparative conditions termed, for convenience, the "reactivity") is important in combustion, gas production and metallurgy, it is hoped that this paper will be a useful contribution to the store of knowledge on these subjects. In carrying out the investigation, considerable time and thought were spent in obtaining what seemed to be the best possible design of apparatus. The next step consisted in making a number of trial runs on the same sample, varying temperature, particle diameter, etc. and then outlining a standardized procedure to be followed in testing all samples. Fifty anthracites were tested. As a matter of interest, some 10 miscellaneous samples were also tested. The data show initial reaction temperatures (abbreviated I.R.T.), reaction velocity constants at 900" and 950" C., some effects of added substances, and a few additional tests designed to throw some light on the causes of differences in reactivity. The sample of charcoal, as was anticipated, proved to be easily the most reactive of any sample tested. The anthracites as a group came second. The five samples of gas and by-product cokes, obtained from five different coke manufacturers, came third, and a single sample of Rhode Island anthracite ranked fourth, with respect to reactivity as above defined. Although the five coke samples do not necessarily represent the average market coke, and five samples constitute a rather small number of samples to serve as a basis for comparisons, the fact that none

Jan 1, 1934

By H. W. Weart, S. Sarian

The effect of temperature, impurities, and capillarity on the morphology of solid particles in a liquid matrix is investigated. For the NbC-liquid iron system, at least, it is found that those particles which are dissolving will assume a spherical shape; all others will take the equilibrium shape. An aniso-tropic-isotropic transition in the interfacial tension is observed at about 1725°C and is believed to be due to cooperative roughening of the interface on an atomic scale. The presence of boron as an impurity lowers the transition temperature. It is the purpose of this paper to present some observations on the shape of particles in a system consisting of solid particles of nonuniform size in a liquid matrix and to propose an explanation for these observations. Although qualitative only, these observations, which were made largely in the course of a study of particle-growth kinetics,&apos; are presented separately to draw attention to them. They reveal the effect of particle size, temperature, and surface-active impurities on particle shape in the solid NbC-liquid iron system, and are unique in demonstrating for the first time the reversible effect of temperature and impurity concentration on the anisotropy of the energy of the solid-liquid interfaces involved. Some of the changes are readily demonstrated with the few particles whose shapes can be clearly shown in a single photomicrograph, but others are more subtle, and their recognition depends upon some experience and the study of a much larger sample. For this reason, a certain amount of judgment must be acknowledged to underlie their detection, but every effort was made to maintain proper scientific objectivity in evaluating the observations. The observations will be presented first, and then an explanation rationalizing them will be offered. Brief reminders of the relevant theories will be inserted into the discussion at the appropriate points. EXPERIMENTAL The observations were made of the shape of NbC particles dispersed in liquid iron. All specimens were prepared by pressing NbC powder and car- bony1 iron powder treated according to standard powder-metallurgical procedures. Except as noted, all specimens were heated to 1900°C for 1/2 hr. In investigating the effect of temperature, specimens were quenched from 1900°C to various lower temperatures, and held long enough (48 hr) to allow shape changes to be completed. Boron, in the form of amorphous powder, and oxygen, in the form of niobium oxide powder, were added as impurities to some specimens. Nitrogen was introduced into some specimens as an impurity by heat treating the samples under a partial pressure of nitrogen gas. Effect of Temperature. It was first observed that increasing temperature had a marked effect in rounding the corners and edges of the particles. At 1900°C the particles are all very nearly spherical and remain so even when the holding time is extended to 48 hr. As can be seen from Fig. 1, there is virtually no evidence of the presence of low-index planes. At 1300°C, however, most of the particles are prismatic with very slightly rounded edges and corners, Fig. 2. (In making these shape comparisons, attention should be focused on the larger particles, even though the smaller ones would be expected to be the first to change shape, owing to the shorter diffusion distances involved. The cause of the mixed particle shape will be explored later.) It was established that these structures are re-

Jan 1, 1965

By Charles Barrett

METALLURGISTS are making use of the stereographic projection to a steadily increasing extent. In the last five years no less than 20 papers in American metallurgical journals alone have employed the stereographic projection; recent books on physical metallurgy, plastic deformation, X-rays and their applications, and crystal structure use it. Mineralogists have used the stereographic projection for many years in the description of symmetry classes and crystal planes, for it presents an accurate, easily understood plot of any angular relations in crystals with all unessential features eliminated (such as the accidentally deter-mined size and shape of crystal faces). In metallography and physical metallurgy the projection is much used for the analysis of markings appearing on polished grains: slip lines, twins, cracks, structures formed by precipitation, magnetic-powder patterns, etch pits, etc. Data from certain types of X-ray photograms are most conveniently analyzed by its use, particularly those for determining the orientation of single crystals or the preferred orientation of grains in an aggregate. Calculations of how to tilt or cut a crystal parallel to a certain crystallographic plane or to reflect X-rays from a certain plane are rapidly carried out. It has been adopted almost universally to the exclusion of other methods by those studying the deformation of metallic crystals, save where the accu-racy required is greater than a few tenths of a degree. Any directional property in a crystal or polycrystalline material can be shown on a stereo-graphic projection; for example, the modulus of elasticity, yield point, etc. It has been repeatedly called to our attention that there is need of all elementary explanation of the principles and methods of stereographic projection, covering all the, common applications in the field of metal-lography and physical metallurgy. The following contribution is an attempt to fill this need. The description of each method is supplemented with references to publications in which the method has been used. For convenience to the reader, these illustrative references are chiefly in American journals, particularly the publications of the American Institute of Mining and

Jan 1, 1937

Discussion of the paper of J. V. EMMONS, presented at the Pittsburgh meeting, October, 1914. and printed in Bulletin No. 93, September, 1914, pp. 2233 to 2248. ALBERT SAUVEUR, Cambridge, Mass.-Mr. Emmons is to be congratulated for having placed before us in so forcible and satisfactory a manner a question of much importance-that of the surface decarbonization of steel. Of course, both manufacturers and consumers have known for many years that during the heat treatment of high-carbon steel, surface deca.rbonization is always likely to occur to a greater or less degree, but the subject does not seem to have been investigated with the method and thoroughness it deserves. I am in substantial agreement with Mr. Emmons&apos;s conclusions, and I have but little to add to what he has so well said. His statement that carbon dioxide is just as effective an oxidizing agent as pure oxygen is likely to cause surprise and some will wonder whether his investigation has been carried far enough to warrant so unexpected a conclusion. The reaction C + 0 = CO, expressing the oxidation of carbon by pure oxygen, is decidedly exothermic, whereas the reaction C + C02 = 2C0, expressing the oxidation of carbon by carbon dioxide, is endothermic. Decarburization by pure oxygen, therefore, should take place much more readily than by carbon dioxide. One cannot help regretting that the author does not mention&apos; the best way of preventing in a practical manner surface decarbonization while treating tool steel and other high-carbon steels.

Jan 4, 1915

By E. G. Leonardon, C. Schlumberger, M. Schlumberger

In the search for practical geological problems amenable to solution by the potential methods, the geophysicist is led to study mathematically various theoretical cases. In these idealistic discussions, the media under consideration are generally supposed to be homogeneous and iso-tropic. The geophysicist, of course, realizes perfectly that these conditions do not occur in their entirety in reality. However, the assumptions made are justified, because very often they are necessary in order to render possible an exhaustive study of a given problem, which otherwise would be too complicated, and would not lend itself to a complete mathematical analysis. Of the above two assumptions, that concerning the homogeneity of a given geological formation is satisfactorily realized except in so far as isotropy is concerned, since this property is not often encountered in practice. As a consequence, it is very desirable for the geophysicist to have quite an extensive knowledge of the properties of anisotropic formations, and of the laws that govern the propagation of electric current therein. With such principles in mind, he will be able to decide whether the conclusions arrived at in simple, isotropic conditions are still correct in more complex cases, or in what way they must be modified or adapted in order to constitute a sound basis for the interpretation of the results obtained in anisotropic media. On the other hand, the fact that in anisotropic formations the mobility of the ions is greater along the strike than perpendicular thereto can be utilized for determining the direction of the dip by induction measurements. We therefore propose to study in three successive chapters the following points: 1. Propagation of the electric current in anisotropic media. 2. Some consequences of the anisotropy of geological formations with reference to the surface electrical measurements, and their interpretation. 3. Determination of the direction of the dip of anisotropic formations by surface induction measurements.

Jan 1, 1934

By T. S. Spicer, C. C. Wright, R. G. Bowman

IN recent years considerable publicity has been given to the problem of atmospheric pollution by fuel-burning equipment. Legislation has been stimulated and smoke ordinances have been enacted, the provisions of which show a definite trend toward stricter control of the emissions not only from the stacks of industrial fuel users but also from the chimneys of domestic consumers. As a result of war conditions, some slackening in the enforcement of these ordinances may be noted, but this is only a temporary expediency caused by the changes necessary in the distribution of the nation&apos;s fuel supplies and difficulties in securing the necessary equipment. Previous trends may be expected to continue in the postwar period. Largely because of the consumer demand for automatic heat, but partly because of the legislation against smoke emission, there has been a marked increase in the use of domestic underfeed stokers with the past decade. When correctly adjusted and operated, these units reduce the smoke emission materially, so that even the high-volatile bituminous coals may be burned with little or no emission of objectionable smoke. Unfortunately, however, the use of the domestic underfeed stoker introduces another problem; namely, fly-ash. PRODUCTION OF FLY-ASH The term "fly-ash" is a misnomer, since the fly material is generally a mixture of small carbonaceous particles varying from green coal to coke, and inorganic particles ranging from fluffy ash to small particles of fused clinker. For want of a more comprehensive name, however, the term fly-ash is used throughout this paper to include all the fly material. Even with hand-fired furnaces a certain amount of fly-ash is produced, which necessitates periodic cleaning of the boiler flues or furnace radiator, the smoke pipe, and occasionally the chimney itself. With stoker operations the amount of fly-ash is increased many fold, because of the higher velocity of air travel through the fuel bed. Frequently the amount of this fly-ash attains such proportions as to constitute a definite nuisance to the householder and his neighbors and distracts very materially from the otherwise automatic or semi-automatic performance of the stoker. Virtually all the boilers and hot-air furnaces marketed in the domestic field

Jan 1, 1944

By Matsubara, A.

THE problem of the equilibrium between iron, carbon, and oxygen was first carefully investigated by E. Baur and A. Glaessner,1 who determined the equilibrium conditions of the two reactions Fe304 + CO ? 3FeO + C02 (1) FeO + CO ? Fe + C02 (2) within the range of temperature of 350 to 900° C. The next series of investigations was made by R. Schenck and his co-workers,2 who sought to check the results of Baur and Glaessner&apos;s work within the range of 550° to 700° C. and to elucidate the conditions of formation of iron carbide. The equilibrium conditions at the higher temperatures, however, are generally understood to be much more complicated, owing chiefly to the formation of solid solutions between iron, its oxides, and carbide; nevertheless their determination is of much more practical importance than those at the lower temperatures. It is well known that each of the reactions is reversible; equilibrium is established when the partial pressure of oxygen in the gaseous phase has become equal to the dissociation pressure of magnetic oxide in equation 1 and that of ferrous oxide in equation 2. These equilibria are subsequently designated by "the Fe304-FeO equilibrium" and "the FeO-Fe equilibrium," respectively. As the Fe304-FeO equilibrium has three phases with three components, it must be bivariant. But the reaction involves no pressure change in the gaseous phase, hence the final composition of the latter is practically unaffected by pressure. To know, the equilibrium conditions, the compositions of the gaseous phase at different temperatures must be determined. At the higher temperature, however, iron and its oxides dissolve one another in various proportions forming solid solutions; in many cases the content of oxygen in the solid phase becomes a new independent variable.

Jan 2, 1921

By Dara P. Antia, Morris Cohen, Frank S. Gardner

THERE is a conspicuous lack of information in the literature on the precise role played by residual quantities of austenite in heat-treated steels. While retained austenite may be expected to have significant effects on such important properties as the impact resistance of tools and carburized parts and the dimensional stability of dies and gauges, attempts to study these problems systematically have suffered from the absence of a reliable technique for ascertaining absolute amounts of austenite. With such a technique, not only could the relation between residual austenite and service behavior be investigated, but the chemical and heat-treatment factors that control the quantity of the austenite could also be established. Thus, the retained austenite content could then be regulated in accordance with the results desired. The presence of retained austenite may be inferred by observing the changes in properties (hardness, specific volume, electrical resistance, etc.) due to its decomposition on subatmospheric cooling1 or on tempering,2 but these indirect measurements are not readily translated into percentages of austenite. Quantitative determinations have been achieved in special cases by means of dilatometric3 and magnetic4,5 measurements; but the former procedure requires that observations be conducted during the hardening and involves difficult calibrations that limit its applicability, while the magnetic procedure is very sensitive to extraneous influences and depends upon assumptions that can only be considered as approximate in an absolute sense. Furthermore, both the dilatometric and magnetic effects are volume properties, and cannot be conveniently utilized to explore variations in retained austenite from point to point in a specimen. Some microstructures lend themselves to accurate evaluation of retained austenite contents by metallographic methods,3 but such instances are not too common, and at best, the procedure is tedious. The characteristic X-ray diffraction lines of austenite permit positive identification of its presence; and in the present paper the intensities of these lines, or the corresponding densities* on photographic film, are employed to measure the amount of the retained austenite. In order to cancel the effect of uncontrollable variations in the X-ray exposure and film-development conditions, a standard reference line is superimposed on each film by maintaining a foil of aluminum in the path of the incident X-ray beam during the entire exposure. With different samples of steel and the same foil, the ratio of the density of some one austenite line to the density of

Jan 1, 1943

By Richard Miller

The investigations of large-grained specimens carried out by Polanyi and Schmid,1 Sykes,2 Goucher,3 Yamaguchi,4 Gough, Cox, and Sopwith,5 Carpenter and Elam,6 Aston,7 and others have shown qualitatively that grain boundaries restrain the deformation of adjacent crystals. But whether or not the influence of the grain boundary is confined to the glide planes intersected by the boundary has not been demonstrated in any of these investigations, nor has there been carried out any quanti-tative analysis, of the influence of a boundary on the deformation of a crystal. Indeed, the specimens employed in the previous work con-

Jan 1, 1934

By Edward Keller

Someone some time ago remarked that some chemists still insist on telling us how to determine copper by the electrolytic method. The writer must confess that he believes that everything is not known definitely as yet as to how the exact amount of copper is determined in such material as purest commercial electrolytic copper. Some of us are not yet convinced that the pure copper atom is at all times deposited from an acid solution and that no oxygen or hydrogen will, under certain conditions, accompany it. Difficulties with impurer material are frequent, but erroneous results are not always apparent, since these do not speak so readily for themselves as those in the first case. By this is meant that if a chemist finds 100 per cent. of copper in electrolytic copper it is pretty certain that he perceives the result to be wrong, while if he finds 0.1 per cent. of copper too much in a very impure material he is far more likely to be unconscious of his error. These, in a wide experience, are frequent happenings and the writer has always looked with interest to publications on this subject. In turn, he feels justified in giving to others a few of his own observations. Up to a few years ago there were two methods of electrolytic copper assay in technical use, which had in common, that the amount of copper deposited on the cathode did not exceed 2 g., and they differed in that, for the one a large sample1 (20 to 80 g.) was taken from the general sample by a splitting device, dissolved, and from the solution a small portion (to contain 1 or 2 g. of copper) measured out for the electrolytic deposition; in the other method the copper was determined, generally in 1-g. portions of the separated coarse and fine portions of the sample, all of which passed a 16 or 20-mesh screen, being accomplished by a 40-mesh screen,

Jan 1, 1914

By K. H. Ribe

Water often enters an oil reservoir during completion or workover operations on a well and forms a partial "water block" to oil production. A mathematical study of radial two-phase flow, neglecting capillary effects, has been employed to study the formation of such a water block and subsequent re-moval by production from the well. The effects of reduced oil permeability about the well on the well productivity were studied. The fluid saturation distributions about the well during formation and removal of the water block have also been computed. Several relative permeability relations and viscosity ratios were employed. If water has invaded the formation, its influence through relative permeability effects alone can cause the following. 1. Oil productivity will be depressed for extended periods after production is resumed and will build up only gradually as the water is removed. 2. Oil injected for treatment of water blocking will delay rather than promote restoration of full well productivity by enlarging the region invaded by water. Thus, unless the specific action of chemicals contained in the oil is needed, oil injection appears undesirable. INTRODUCTION During oilwell workover operations, water may enter the oil-bearing formation from the wellbore. When production is resumed, oil must flow through the region invaded by this water. The presence of this region can cause both well productivity and oil production rate to be low and oil to be produced with high water-oil ratio for some time after production is initiated. This situation is sometimes described as a water block. The introduction of water into the formation may result in other actions which also lead to reduction in well productivity and which are also usually included in the connotation of the broad term, water block. Often considered, for example, are the possibilities of clay swelling by contact with fresh water and the formation of emulsions with the formation oil. If it is suspected that such specific actions have taken place, remedial treatments are undertaken which usually involve the injection of chemicals in oil. Since the introduction of water, even in the absence of specific interactions with the formation or oil, will cause a temporary water block (which might be misinterpreted as evidence of a more severe situation), it is of importance to evaluate the magnitude and duration of this blocking which results purely from the reduction in relative permeability to oil in the vicinity of the wellbore. It is also of interest to evaluate the effect of oil injection on the productivity of a well blocked by water in this manner. Inasmuch as this unfavorable condition may persist for some time, it may lead to premature condemnation of a workover or premature abandonment of a potentially productive pay zone. A quantitative evaluation of the influence of water entry on the oil productivity through changes in relative permeability was made by solving a radial form of the Buckley-Leverett equation. The distribution of water saturation around the wellbore during the entry of water was calculated and was followed by a similar calculation of the saturation distribution during the period of resuming production. At any stage in the removal of the invading water, knowledge of the distribution of its saturation permitted calculating the attendant loss in oil productivity. The influence of the shape of the relative permeability relationships was also evaluated by carrying out the calculations for two hypothetical cases. Further, the effect of the oil-water viscosity ratio was examined by repeating the calculations, for several ratios of unity and greater, with the same relative permeabilities. Fi-nally, results are presented to show how the length of time a well must be swabbed to resume production depends on the length of time it has been subjected to invasion by water. STATEMENT OF THEORY Differential Equations Water is assumed to enter a producing formation which is initially at the connate-water saturation and contains no gas. The water and oil are treated as in-

Freeman, the English historian, said that he had learned from Macaulay "never to be afraid of using the same word or name over and over again if by that means anything could be added to clearness or force. Macaulay never goes. on, like some writers, talking about &apos; the former &apos; and &apos;the latter &apos;, &apos;he &apos;, &apos;she &apos;, &apos;it), and &apos;they’, through clause after clause, while his reader has to look back to see which of several persons it is that is so darkly referred to". He might have learned also from Macaulay that a preposition makes a feeble ending for a serious statement. How often do you hear &apos;the former&apos; and &apos;the latter&apos; in conversation? Good conversation is a guide not to be disdained. When you must use &apos;the latter &apos;, do not confuse it with &apos;the last &apos;. Cheap labor, cheap fuel, and cheap transport are essential, the latter [last] being particularly important in base-metal mining. The apparatus may be used to determine such gases as hydrogen sulphide, chlorine, oxides of nitrogen and some others, as well as sulphur dioxide. In the case of the latter two, etc. The two last mentioned are "sulphur dioxide" and "some others". He should have stated which two, and he should have avoided that wretched phrase "in the case of ". Pinning may be partly prevented by use of chalk, oil, or turpentine. The latter [last] is beat. "Partly prevented" is a poor phrase. &apos;Prevented&apos; is a word that does not lend itself readily to modification. He means &apos; checked &apos; or &apos;corrected &apos;. These steps are necessary to produce the gas, crude oil, and ammonia, the latter [last] of which is in solution in the water obtained along with the oil.

Jan 1, 1931

By Robert Sisselman

Central Sweden&apos;s Grängesberg underground iron ore mine, which accounts for more than three million tons of pellet product annually, is experiencing a major changeover to continuous block-caving. The newly-adopted method, complete with a total revamping of mining equipment, will be fully operational by 1975. For the past 15 years, Sweden&apos;s Grängesberg mine has been mined using two different methods. Those ore thicknesses of 117 ft or greater (they comprise about 70% of the total area) are worked by block-caving techniques with cross-cutting carried out on each 195-ft working level, and loading at the foot wall on each 58-78-ft level. Sub-level caving is carried out in all ore sections less than 117 ft thick.

Jan 1, 1974

By K. E. Starling

Phase equilibria data were used to develop an equation-of-state correlation for complex hydrocarbon mixtures, thereby circumventing difficulties associated with use of pressure-volume-temperature data. Equilibrium phase data for two condensate reservoir fluids were used to determine equation-of-state parameters for hydrocarbons as heavy as C22H46 in a modified form of the Benedict-Webb-Rubin equation of state. Comparative tests of K-values from the resultant correlation were made with data for condensate reservoir, separator and gas plant absorber mixtures. Generally, for temperatures above OF and computed liquid densities below 0.55 Ib-mole/cu ft, the modified BIVR equation predicted K-values in close agreement with the experimental data. INTRODUCTION Accurate predictions of thermodynamic behavior for complex hydrocarbon mixtures are necessary for many calculations in the petroleum industry. Because of the relatively high cost of extensive experimental data, many correlations for prediction of phase behavior have been developed. Some of these, such as the correlation of K-values presented in the NGAA Equilibrium Ratio Data Book, are totally empirical.l Others, such as the Benedict-Webb-Rubin (BWR) equation-of-state method, are semitheoretical.2-4 Unfortunately, published correlation methods often do not accurately predict the phase behavior of complex hydrocarbon mixtures, principally because of inadequate representation of the effects of components heavier than decane. This paper presents a new approach to this problem in which basic equation-of-state relations including heavy hydrocarbon effects are applied. Equilibrium phase data for two condensate reservoir fluids containing hydrocarbons as heavy as C22H46 are used to correlate component K-values. The BWR equation was chosen as the prototype equation of state for this study because of its proven capability for accurately predicting phase behavior and thermodynamic properties of light - hydrocarbon mixtures? Research was directed toward development of BWR parameters for the heavy hydrocarbons and modifications of the mathematical form of the BWR equation for application to complex hydrocarbon mixtures. The new equation-of-state approach presented differs considerably from previous methods in that phase equilibria rather than PVT data are used for determination of equation-of-state parameters. It is an explicit approach since the parameters are determined directly from mixture data. As such, it does not encounter problems inherent in the implicit method used by Benedict, Webb and Rubin 2-4 and numerous other investigators—one in which mixture parameters were postulated to be functions of the pure component parameters. The pure component BWR parameters, in turn, were determined from experimental PVT data. This method has been limited to mixtures containing components lighter than decane because of lack of vapor phase PVT data. Studies have been reported in which BWR parameters have been determined explicitly from PVT data for binary mixtures.6-8 However, since small concentrations of heavier components have only a minor effect on PVT behavior, it is doubtful that these explicit methods would yield useful results for condensate systems. Ellington and Eakin9 have shown that the accuracy of K-values predicted by an equation of state developed from mixture PVT data probably would be more than an order of magnitude lower than the accuracy of the PVT data. On the other hand, an equation of state utilizing parameters developed from phase equilibria data should predict K-values with accuracy comparable to the accuracy of the experimental phase compositions. This work applies this explicit approach with the objective of improving hydrocarbon mixture phase behavior predictions. Results are evaluated by comparing predicted and experimental K-values at reservoir, separator and gas plant

Jan 1, 1967