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By David J. Mack

THE structures and properties of the copper-aluminum alloys have been the subject of much study since the classic investigation of Carpenter and Edwards1 focused attention on the engineering utility of these alloys. It was recognized at an early date that the metallographic structures developed in the aluminum bronzes were similar to those developed in steels, both in the annealed and the rapidly cooled state. Most investigators have been concerned with the acicular, martensitic-like structure formed from the ß solid solution upon rapid quenching; the transformation of the ß under equilibrium cooling to a lamellar eutectoid having been relatively neglected. With the introduction in 1930 by Davenport and Bain2 of the isothermal transformation technique for studying eutectoidal decompositions, a new field was opened. Although an enormous amount of work has since been done on the isothermal transformation of steel, study of structurally analogous systems has been almost totally overlooked. The outstanding exception was the prize-winning paper† of Smith and Lindlief3 who investigated the decomposition of the ß phase in copper-aluminum alloys by isothermal methods. This was followed in 1934 by Wasserman's reviews of available information on analogous transformations in eutectoid alloys. Since that time no comprehensive study of isothermally transformed eutectoids analogous to steel has appeared, although many valuable contributions have been made to an understanding of the structures developed in such systems. Important papers have been published by Kurdjumow, Gridnew and co-workers, 5-17 Obinata,18,19 Greninger,20,21 and others .22.28 The work to be described in this paper was an out-growth of preliminary studies on the isothermal transformation of a eutectoid aluminum bronze, after it became apparent that the alloy under study was reacting somewhat differently than the similar alloy used by Smith and Lindlief. PRELIMINARY EXPERIMENTS The material used in this study was a high purity aluminum bronze especially prepared by Ampco Metal, Inc. It analyzed: Copper-88.o7 pct, Aluminum-11.89 Oct, Iron-0.02 pct, Manganese-0.01 pct, Others-Balance. Although some disagreement exists on the exact composition of the eutectoid, this alloy was believed to be of essentially eutectoid composition even though some pro-eutectoid* delta particles existed in the microstructure of furnace cooled specimens. Specimens transformed isothermally at temperatures slightly below the eutectoid showed relatively large amounts of pre-eutectoid delta, but as will be shown later, this results

Jan 1, 1947

By Harrison Schmitt

THE definitions of the terms commonly used in connection with metamorphism at elevated temperature near igneous contacts are re-examined. As the study of tactite zones associated with igneous contacts progresses, more and more emphasis is put on the localization of the ore by structural forms. The generally early age of the silicates and late age of the sulphides is well established. Postsilicate structural deformation is likely to localize ore bodies. The silicates are often replaced by the ore minerals. We may not be far from proving that the elements involved in the formation of silicate aureoles are merely normal "volcanic" emanations, that silica, lime, magnesia, and alumina and probably soda and potash are likely to undergo local transfers only. The work of Newhouse suggests the agents of the formation of sulphides in deposits of various classifications are the volcanic emanations.

Jan 1, 1947

By A. J. Miller, G. R. Brophy

The Grossmann principle1 for the calculation of hardenability of steel from composition is attractive because of its simplicity. It postulates that the hardenability of a steel for any particular grain size may be expressed in terms of an ideal critical diameter, which is the product of an ideal critical diameter for a "pure" iron-carbon base multiplied by a succession of factors for each element of composition contained, including the incidentals. It infers that the multiplying factor for a given quantity of an element is constant for all combinations of composition. Gross-mann has stated that in the great majority of cases the experimental values of hardenability are found to be well within 10 per cent of the calculated values. The validity of the scheme has been confirmed in principle by Crafts and Lamont2,3 and by Kramer et al.4 Their results differ from the original in the magnitude of the effect of some elements but, since they accepted the product concept and followed its direction, it is to be ex~ected that similar results would be obtained. Crafts and Lamont, in their second Paper, recognized that the factor relations for manganese and nickel were not continuously linear, but beyond certain critical amounts increase sharply. Austin, Van Note and Prater6 demonstrated nonlinear relations between hardenability and alloy contents. Their curves for chromium, silicon, manganese and nickel were all convex upward to show decreasing incremental effects. They concluded that Grossmann's factors under-evaluate the hardening effect of low percentage additions of these elements, and overevaluate the larger additions. More recently W. Stevens has found that the factor method fails when applied to complex steels containing two or three principal alloying elements other than carbon. Multiplying factors derived from his results bear a complex relation to composition and are not constant for a given amount of an element as the base composition varies. C. A. Liedholm7 found that, using either the Grossmann or the Crafts-Lamont multiplying factor values, not only were the relative hardenabilities of two heats of S.A.E. 6130 chromium-vanadium steel

Jan 1, 1947

By G. K. Manning, C. H. Lorig

TWO metallurgical tools have acquired wide use within the past several years as a means of studying the transformation characteristics of steel. One is a technique used first by Bain and Davenport for determining the transformation characteristics of a steel at constant temperature; the second is the end-quench hardenability test. Constant-temperature transformation curves like those of Bain and Davenport have done much to rationalize the metallography of steel; however, in commercial practices, constant-temperature transformation is seldom encountered, therefore only rarely can such curves be directly applied. The real reason for the determination of such curves lies in the fact that they provide a way of thinking about transformation that is both convenient and productive. The end-quench hardenability test is a more practical means of studying transformation, for, by correlating positions on the hardenability bar with shapes of different masses, an almost direct application of the results can be made. Unfortunately, the end-quench test, though practical, can do very little toward improving the metallurgists' way of thinking about transformation. These two metallurgical tools, dealing with precisely the same phenomenon, should be very closely associated in metallurgists' minds. Actually, they are frequently pushed into separate mental corners and considered as being more or less distinct and unrelated. The reason for this is that no strong connecting link between them has been developed. An attempt is sometimes made to relate these two tools by projecting the critical cooling rate on the isothermal transformation plot as illustrated in Fig. I. The critical cooling rate is considered as a constant rate-though in practical applications, cooling rates are never constant—and this constant cooling rate is given uniform significance from the Ae temperature down to the temperature of initial transformation. A little thought indicates the errors of such a procedure. Certainly the time interval spent just below point A of Fig. I cannot be as effective in promoting nucleation as is the time interval spent just above point B. Yet the procedure represented in Fig. I considers all the time spent between temperatures A and B to be just as effective in promoting nucleation as though all the time were spent at temperature B. Furthermore, change the shape of the isothermal curve between points B and C in any way desired, and the required critical cooling rate is not changed one iota. This cannot possibly be true. Such a way of thinking about critical cooling rates not only is incapable of giving any results that are quantitatively satisfactory but is likely to give very misleading qualitative results.

Jan 1, 1947

INDEX OF CONTENTS.1. Historical.2. Manufacture.3. Heat Treatment.4. Fatigue, Failures.5. Consideration of the Establishment o£ a Central Testing or Proving Station.HISTORICAL.Since the introduction of improved high air pressure drilling machines in the early part of the century, efforts have been made to develop the quality of the rock drill bit, in order to take advantage of the greater increase of power output per unit weight of the machines (1). This resulted in the change from solid to hollow steel in the second decade of the present century (2).As the greatest sufferers from the dread disease of silicosis (3), it seemed appropriate that the South African gold mines should be the first to use hollow drill steel. Since then solid drills have become practically obsolete for mining purposes.Water is used with hollow steel drills not only to keep the cutting end cool, but also to assist in preventing the formation of undue dust during drilling. It is of interest to note, however, that water fed through hollow steel or sprayed into the air is only partially effective in removing fine dust particles a few microns in diameter, which particles are said to be the most potent in producing silicosis (3a).So far as the composition of "straight" carbon steel drills is concerned, a commission appointed by the Johannesburg mines carried out a very exhaustive series of tests on drill steels.These drills were manufactured from steel made by all the standard methods, including Swedish, Bessemer, crucible, openhearth, and, to a limited extent, electric furnace steel. It should be remembered that the commissioners' report was issued in 1913, when hollow drill steel had not yet been introduced. Only solid steel drills were then in use.

Jan 1, 1947

By John Craw

This paper has formulated the methods, both medical and engineering, for the control of pneumokoniosis in the haematite-mining industry in West Cumberland, but this is only part of a general service to improve the lot of the worker in these mines, to make him a better and happier workman, and to permit him to enjoy his work and leisure in comfort and good health. This organization has now been functioning for more than ten years and the results are indeed heartening, but it is only as a result of constant vigilance from the mining and medical point of view that such a plan can operate efficiently. The human element and its full understanding is by no means the least of the problems.

Jan 1, 1947

By Albert J. Phillips

IT is a privilege and a pleasure to deliver this, the Twenty-sixth Annual Institute of Metals Division Lecture. Eleven years ago C. A. Edwards addressed this audience on the subject "Gases in Metals." In spite of this relatively recent presentation, I propose to, present to you some quantitative considerations of industrial significance on the separation of gases from molten metals because recent observations and measurements, presented in the literature, have made it possible to evaluate mathematically the gases or gas-forming elements and to develop an understanding of the mechanism of gas separation that should permit, in many cases, the control of this baffling phenomenon. DEFINITIONS Before becoming involved in the subject it seems desirable, for the sake of clarity, to state certain definitions and axioms: I. We are dealing only with gases that separate from the molten metal either during cooling or in the transition from liquid to solid. Gases injected by the liquid stream and trapped in the solidified metal, or those forced into the solidifying metal from the mold due to either thermal or cher4ical effects are not considered. Neither are we concerned with the separation of gases within the metal after solidification is complete for the data on this subject are at least complete enough to permit the practicing metallurgist to satisfactorily control the phenomenon. 2. Only where there is a decrease in solubility or a change in equilibrium of either a gaseous element or an element that reacts to form a gaseous compound, can there be a separation of a gaseous phase from the liquid or solidifying metal. 3. The amount of gas separating from the liquid during solidification can be computed directly from the amount of the element contained in the liquid when freezing commences less the amount of the element found in the solid either as a separate solid phase or in solid solution. 4. There can be no separation of gas bubbles unless the told pressure of the gases in the liquid meld exceeds atmospheric pressure plus the hydrostatic pressure of ' the liquid metal head. (In addition, pres- sure resulting from surface tension in- creases the total pressure requirement for initial gas separation. Probably the remarkable differences in appearance caused by different gases in the same host metal are influenced greatly by the rate of diffusion of the gas in the liquid metal balancing the decrease in pressure as the gas bubble size increases and the surface tension effect decreases. Thus hydrogen with its high diffusion rate in liquid copper separates in the form of relatively coarse cavities for a given rate of heat extraction.) 5. Gas separation can take place at less than atmospheric pressure in the voids created by the shrinkage from liquid to solid, but since the voids are not caused by the gas the presence of gas in the voids is of importance only where it

Jan 1, 1947

By H. R. Deeth, C. J. Koenig

ABOUT ten years ago nepheline syenite was introduced to the ceramic industry and the material has now found application in the various branches of the industry, namely, as a vitrifying agent in white-wares and as a source of alumina and alkalies in glasses, glazes, and porcelain enamels. Spence1 described the early mining and processing developments regarding this material. Since the time of his article many research papers have appeared relating to the usage of nepheline syenite but little has been published relative to subsequent mining and processing methods. A complete indexed review of the literature was issued recently by Ohio State University.2 Since "Lakefield" nepheline syenite from Blue Mountain, Ontario (Fig I); is the only commercial ceramic-grade nepheline syenite now being marketed on this continent, discussion is limited to this operation carried on by American Nepheline Limited, Lakefield, Ont., and its subsidiary in the United States, American Nepheline Corp. at Rochester, N. Y. THE DEPOSIT Blue Mountain is a long ridge rising to an elevation of about 350 ft at its highest point above the surrounding country and extending for about six miles in a northeasterly direction across Methuen township, Peterborough County. The rock of the Blue Mountain central alkaline intrusive is fine grained, light colored and of even granitic texture. The solidified mass consists predominately of the minerals albite, nepheline and microcline in order of abundance. The average mineralogical composition for the deposit obtained by a study of 112 samples taken regularly over the whole formation is as follows:3 [VOLUMETRIC MINERAL PER CENT Albite54 Microcline20 Nepheline22 Muscovite2 Mafics2 (Biotite, hastingsite, magnetite) Total100] The mineral nepheline (or nephelite) belongs to the feldspathoid group but is lower in silica content than are the feldspars. It is a silicate of soda, potash, and alumina (NaKAl2O32SiO2). Its presence with albite (Na2O A1203 6SiO2) and microcline (K20 A12O3 6SiO2) gives the Blue Mountain deposit an alkali content of 15 pct and an alumina content of approximately 24 pct. While this huge alkaline mass is somewhat variable mineralogically, it has a uniform chemical composition. When the iron, mostly in the form of magnetite, is removed during processing, a remarkably uniform finished product is obtained. Geological surveying has disclosed many million tons of nepheline syenite in the Blue Mountain deposit. Diamond drilling in the area where mining is now being carried out indicates a block of about one million tons.

Jan 1, 1947

By A. J. Shaler, J. Prieto Isaza, John Wulff

TANTALUM metal has a number of unique properties which give it widespread application in modern technology and in research. In electronic apparatus involving high temperatures in vacuo some of the refractory metals become brittle. Tantalum retains its ductility at elevated temperatures, and this property, together with its low vapor pressure and its ability to absorb gases, make it important in this field. Its chemical inertness in the presence of acids, halogens, and other corrosive media, makes it useful in chemical apparatus and in neuro and orthopedic surgical applications. As an addition to tungsten carbide in steel-cutting grades of cemented-carbide tools, the carbides of tantalum and of its sister element columbium have found considerable use. The present-day method1 of manufacturing tantalum is to sinter a powder compact of the metal in vacuo. Because tantalum- columbium alloys are difficult to work and since tantalum ores almost always contain columbium, the two metals must be separated chemically, the products of the separation being generally in the form of potassium tantalum fluoride and potassium columbium oxyfluoride. These salts are used in fused-salt electrolytic baths from which coarse metallic powder is deposited as a sponge at the cathode. Finer powder can be made from the coarse product or from tantalum scrap by first submitting it to an embrittling heat treatment in hydrogen and then crushing it. The fine hydrogen- containing powder may subsequently be degassed in vacuo at a high temperature. Prompted by the success of others2,3 in the magnesium reduction of titanium and zirconium halides, one of the authors under- took4 an investigation of the thermo- chemistry of the reaction between solid magnesium and gaseous tantalum penta-chloride, a subject which had not previously been studied. He found that the heat of formation of tantalum pentachloride is approximately 364,250 cal per mol at temperatures lower than the melting point of magnesium. A value of 83 units was found for the standard entropy at these temperatures. With these values, it was shown that magnesium and tantalum pentachloride are capable of reacting exothermically at temperatures less than the melting point of magnesium, and that no great violence is to be expected when these substances are heated together. The exothermic nature of the reaction indicated that the process should be efficient and should not require much externally applied energy. Tantalum pentachloride is not commonlv made commercially, and any process using it therefore involves the subsidiary problem of producing and handling this substance. A series of experiments was carried out in which dried chlorine saturated with carbon tetrachloride was passed over heated tantalum, either in the metallic state or combined

Jan 1, 1947

Summary of the morning's events with a Written Contribution to Paper No. 4 and author responses

Jan 1, 1947

Jan 1, 1947

By Brook W. H

The history of the reduction of iron from its ores is lost in antiquity. Archreologists state that man has practised it for over four thousand years. Until comparatively recent times charcoal was the principal reducing agent for making metallic iron from its various oxidised ores. Coke was first used by iron founders in England in 1619, and its use spread gradually throughout the civilised world from then onwards. Indeed, the destruction of forests to obtain the requisite charcoal made the iron founders, both in England and America, extremely unpopular, and this hampered the iron industry to a considerable extent, until coal provided the metallurgist with a new and better fuel--coke which is used by most pyro-metallurgists today. The transition from wood to coal products for iron smelting had a profound effect on the location of iron works. Particularly was this the case in America where, in the infancy of the industry, practically each of the early States had its own iron producers, but as coal and coke replaced charcoal, there came about a concentration of the iron and steel industry around the coking coal deposits, and so today there are huge steel plants clustered around the soft coal basins in Pennsylvania and Illinois.The development of the iron and steel industry in Australia, which is comparatively recent by world standards, has been cradled in the coal basins of New South Wales. The first steel works of any consequence in this country were built near Lithgow, close by the mines which produced the coal for coking.Incidentally, these works were rather unique in that the three essential materials for iron and steel manufacture-ore, coal, and limestone-were found virtually at the works' back door.When, in 1912, the location of the proposed steel works for The Broken Hill Pty. Co. Ltd. for smelting ore from Iron Knob in South Australia was considered, the site ultimately chosen was at Newcastle, almost on top of seams of satisfactory coking coal. One of the major factors which had determined the site of the steel works was the fact that, about 1912, three tons of coal were required to produce one ton of finished steel product, and the relative economics of ore and coal haulage were much in favour of bringing ore to the coal.

Jan 1, 1947

By W. M. Traver, A. M. Evans

"INTRODUCTION The Bureau of Mines undertook exploration in the Torlingua district, Texas, during June 1943, at a time when the demand for mercury for war industries was considerably more than the anticipated domestic production. In view of the impressive past production of the mines and the favorable geologic conditions in several underdeveloped areas in the district, the investigation was considered of immediate importance.Prior to initiation of the exploratory program, a preliminary examination of the district was made in August 1942 by A. B. Needham, an engineer of the Bureau of Mines. This examination was followed by a comprehensive geological study by the Federal Geological Survey 3/ and further investigation the Bureau of Mines."

Jan 1, 1947

By G. Gutzeit

An inner complex is a cyclic chemical structure containing an inorganic cation that is bound simultaneously to several atoms in a single organic molecule; on the one hand by means of ordinary valence bonds (electron exchange), on the other hand through the action of the electric field thus created, which satisfies the so-called secondary valences. The relative positions of the salt-forming and complex-forming groups are such that most frequently a four, five, or six-membered ring results through this double attachment of the cation.1-6 The formation of inner-complex ring systems depends not only upon the nature and suitable position of the salt-forming and complex-forming groups for ring closure, but, to a great extent, also on the nature of the metallic cation entering the reaction. This selective character of chelate-forming organic compounds is one of their most interesting and most valuable properties. As a matter of fact, the largest number of their practical applications is based upon their specificity.4,7-l3 Once a chelate compound is formed, its character is definitely "organic" in nature. In other words, its properties are conditioned to a much larger degree by the carbon chains or rings than by the metallic atom. Many inner complexes are soluble in nonpolar solvents such as benzene, paraffin oil or carbon tetrachloride, while the chelate-forming reagent before closure of the metal-organic ring is water soluble. (Example: copper complex of salicyl-aldoxime') It is obvious that such particular properties as those indicated above can be utilized whenever specificity and practically complete binding of inorganic ions into an undissociable complex are required. One of the well-known applications of chelate-forming compounds has been the development of specific reagents in analytical chemistry, creation of the spot-test method,4,14-16 and the application of the same principles to the contact print method for determining minerals." Chelate-forming Compounds as Collectors In the field of flotation, where selectivity is often a quality of paramount importance for the collector, various workers have lately attempted to apply their knowledge of specific organic analytical reagents to this purpose. A. C. Vivian18 has concentrated cassiterite by using ammonium nitrosophenylhydroxyl-amine (Cupferron) C6H5NO(=NONH4). Holmanl9 has tested dimethylglyoxime for the flotation of nickel oxide minerals, while deWitt has shown in a series of systematic experiments that alpha-diox-imes were generally selective collectors for nickel ores. Taurin NH2(CH2)2S03H has been proposed for the concentration Of Oxidized lead ores.19 Diphenylthio-carbazone

Jan 1, 1947

By Charles Trotter

AN instrument has recently been developed for determining the inclination and azimuthal direction of boreholes. This instrument is known as the Tro-Pari Instrument and is the invention of C. Trotter and G. Pajari of Sudbury, Ontario. DESCRIPTION The instrument is characterized by a unit mounted in gimbals and provided with a clockwork mechanism to clamp a compass to indicate azimuthal direction and simultaneously to clamp the unit in its plumb position to indicate inclination (Fig I). By means of a timing ring suitably calibrated in 5-min divisions, the unit may be set to lock after a lapse of time sufficient to allow the placing of the instrument at the desired point in the drill hole where readings are to be taken. The maximum time lapse obtainable with the instrument designed for use in EX or AX size holes is 1 hr 30 min which is considered to be ample time to lower to the greatest depths that may be drilled with this size of equipment. Larger sizes could be developed for larger diameter holes such as BX and NX sizes or the larger oil-well sizes and a correspondingly greater time lapse could be provided for. Up to the present time only the EX-AX size has been built. OPERATION Assuming a borehole is to be surveyed at 1000-ft depth and assuming it will take 30 min to lower the instrument to this depth, the timing ring is rotated through seven divisions which represent a time lapse of 35 min (5-min leeway) and is then returned to its zero position. This operation imparts energy to a spring which drives the clockwork mechanism. Simultaneously the compass needle is freed to swing to its magnetic north-south position and the encased mechanism is freed to hang plumb within a semicircular portion of the frame which is graduated in degrees after the fashion of a protractor. This semicircular protractor portion has a V-shaped notch at each degree division of its inner periphery. The instrument, now in its free position, is inserted in a bronze container made to suit the size of hole to be surveyed (Fig 2). Soft rubber washers are provided within the container to prevent undue shock. The container is connected to the drill rods with three 5-ft lengths of brass or aluminum alloy rods separating it from the steel rods in order to prevent distortion of the magnetic field. The assembly is then lowered to the desired point where readings are to be taken and is allowed to remain at rest until a period of time has elapsed slightly in excess of the time for which the timing ring was set. In the example cited above, when the 35 min has elapsed the compass needle is locked in its north-south position and the protractor locking pin is extruded and locks in the V notch opposite its plumb position. The device may now be removed from the borehole and it will remain in this locked position in spite of jarring or shak-

Jan 1, 1947

By Robert E. Wilson, J. K. Roberts

IN order to make clear the reasons for the basic importance of petroleum and natural gas in the world today, and the problems faced by our scientists and technologists in using efficiently these great natural resources and finding possible replacements for them, it will be necessary to present a brief discussion of hydrocarbon chemistry The most important use of petroleum products is as fuel, particularly for the various forms of the internal-combustion engine There are, of course, hundreds of thousands of chemical compounds that give off heat when they burn, that is, when they combine with the oxygen of the air If a capable chemist were assigned the problem of finding the ideal volatile liquid fuel for use in an engine, he would probably begin by referring to the tables that give the heats of combustion of the chemical elements Of all the ninety-odd elements, hydrogen shows up with by far the highest heat of combustion-about 52,000 British thermal units per pound Unfortunately, however, hydrogen is a very light gas, which can be liquefied only at very low temperatures To burn it as fuel in an automobile would require a balloon about as big as the car to hold the equivalent of a gallon of gasoline, or, the hydrogen could be compressed in heavy steel cylinders, but -this would require about 125 pounds of steel per pound of hydrogen. Obviously, then, hydrogen itself cannot be considered

Jan 1, 1947

By Walter Miller

A surprising development during the year was the continued high demand for petroleum products and the high level of crude oil charges to the stills. Generally speaking, the petroleum industry during 1946 succeeded in producing a greater quantity of crude oil and petroleum products than in any of the war years, and considerably exceeded the production of any prewar year. Daily crude still charges averaged between 4,700,000 and 4,800,000 bbl per day for 1946 and about equaled the 1945 record, although most pessimistic 1945 guesses, predictions, or fears ranged, for 1946, from only 3,900,000 to 4,400,000 bbl per day. In spite of the high crude charge to the stills, total stock of crude oil was higher at the end of the year by some 7,000,000 to 8,000,000 bbl. A similar story holds regarding stocks of the principal refined products. Gasoline on hand at year's end was two to three million barrels lower, and was considered low for the expected demand during the coming high consuming season, while stocks of light and heavy fuel oils, although some higher than a year previous, hardly reached a comfortable level. The trend in gasoline of high octane number, which has resulted in a marked rise in. the antiknock quality by the end of 1945 (five or six numbers higher than during the war and one number higher than the prewar quality of civilian motor gasoline of 1941) was abruptly arrested by an acute shortage of metallic lead for manufacturing tetraethyl lead. Government action in the form of lead price control, rationing, and the setting of octane ceiling specifications to conform to the reduced ethyl lead compound available were enforced until abrogated at the end of the year. It will be interesting to see how rapidly the octane levels will resume the rising trend, as more metallic lead slowly becomes available for making greater quantities of ethyl lead compound. As octane quality rises over present levels the disadvantage of the refiner without catalytic cracking equipment will increase. Gasoline made by catalytic cracking, without addition of ethyl lead, approximates 77 octane by the official ASTM Motor Method test, compared with 66 for gasoline generally similar in volatility made by the older thermal cracking operation. Catalytic gasoline shows an even greater improvement in the Research octane number, the comparison being roughly 86 Research versus 71 Research octane for the thermal cracked product. This higher differential in Research octane is credited by many, although not universally so, as contributing to better road performance, and consequently resulting in a more desirable product marketwise. In some parts of the country a premium of roughly one fourth cent per gallon is now being paid for gasoline with higher Research octane made possible by including catalytic cracked product in the final blends. If such price differentials in favor of catalytic gaso-

Jan 1, 1947

By F. C. von der Weid

The mining district of Sao Fidelis, in the northern part of the State of Rio de Janeiro, is situated on the Paraiba River, where it crosses the Serra do Mar (Mountain of the Sea), in the center of a mountainous country having numerous graphitic outcrops. For a long time, these outcrops were irregularly explored by local people, who had little means and no technical advice. A few years ago, the Cia. Brasileira de Mineracao de Grafite took over the control of some of the more important outcrops and entrusted to me the task of studying the ores and establishing a flowsheet for a pilot plant to be situated in Sao Fidelis—the ore to be concentrated being mostly of a very high grade. Mineralization and Ores The rocks of the district are mostly gneiss and crystalline schists, with occasional interstratification of dolomitic limestone belonging to the Archean Brazilian Fundamental Complex. The general direction of the beds is roughly between 60' and 80°E., with variable dip, generally nearly vertical. Mostly, direction and dip of the graphitic outcrops is concordant with the embanking gneisses or schists. These outcrops seem to be aligned in two or three parallel zones (Padua, Sao Fidelis, Mac- abu), the Sao Fidelis zone being the best known and the most important to date. Two outcrops of the Silo Fidelis zone, Saudade and Sao Benedito, are now being exploited. Mining has beer] carried out, so far, on a small scale. The mineralization consists of a vein of nearly massive graphite in a very compact, partially granitized gneiss, with vertical dip. The vein is most irregular, nith nests and lenses irregularly distributed along the fracture plane. The ore consists chiefly (particularly in Sao Benedito) of massive graphite appearing and disappearing along the main direction of the vein, forming a succession of irregular lenses in a sort of rosary design. The average width is more or less one foot, with variations from zero to 6 feet. The lode minerals are quartz, a little feldspar and garnet (the latter having its origin perhaps in the embedding gneisses), with rare ferruginous clays on the outcrops. In Saudade a little pyrite, pyrrhotite and chalcopyrite is found occasionally, as well as a carbonaceous mineral, very light, black and shiny, with conchoidal fracture, looking like a sort of jet. The composition of this mineral has not yet been established, but it seems to be very complex. The mineralization seems to be hydro-thermal at a rather low temperature, perhaps mesothermal. The paragenesis, according to samples from Saudade, seems to be as follows, the earlier minerals being listed first: pyrrhotite, pyrite, chalcopyrite, with quartz concomitant to the three and graphite formed later. Age of the mineralization is still uncertain, owing to the very in-

Jan 1, 1947

By Edward Saibel

THE object of this study is to investigate the effect of prior tensile strain on the fracture stress of a metal. This is done in a theoretical manner starting from the point of view developed by the author in his thermodynamic theory of the fracture of metals. The results are compared with experimental findings and a rational interpretation is given to work that shows the variation of fracture stress with prior tensile strain. THEORY OF FRACTURE In the thermodynamic theory of the fracture of metals developed earlier,1 it was shown that a critical strain energy per unit volume exists. This is characteristic of the material and may be calculated from basic thermodynamic data. When the area under the flow curve reaches this characteristic value, fracture occurs. The general criterion for fracture is expressed in the form u ± uo = JLm?AV/V [1] where Lm, is the latent heat of melting of the unit volume, ?V/V is the ratio of the change in volume of the unit volume to the original unit volume on passing from the solid to the liquid state, [uo] is an initial energy density, and J is a conversion factor, which changes energy from heat to mechanical units. As a first approximation, it will be assumed that the stress-strain curve is the straight line that extends from the point of maximum load onward, extrapolated back to the axis of zero strain, for example, line AC of Fig. 1. If the point of intersection of the straight line with the axis of zero strain is represented by so, and the slope of the straight line is p, the analytic form of the flow curve is [s = s + pd [2]] and the strain energy per unit volume evaluated from [JvdS] becomes (vsod + pd2/ 2). When this latter term reaches the critical value JLm?V/V (designated hereafter by M), it is assumed that fracture occurs. This leads to the following expression for the fracture stress: [s1 = \/C r.2 + 2Mp [31] The strain at fracture may be calculated from Eqs 2 and 3. It is assumed in this paper that the initial energy density is either zero or that it may be neglected. Furthermore, the complicated states of stress and of strain existing in the necked region of the tensile specimen after "necking" has occurred will also be neglected for the present, so that average conditions will be assumed to prevail. FLOW AND FRACTURE CURVES Ludwig2 attributed to materials two fundamental properties: (I) a resistance to flow and (2) a resistance to fracture. He reasoned that at each instant the

Jan 1, 1947

By John J. McKetta, Donald L. Katz

Recent experimental data on the methane-n-butane-water system have been combined with data in literature to present: (I) the water-vapor content of natural gases, (2) the solubility of water in hydrocarbon liquids, and (3) the solubility of natural gases in water. Since water is present in petroleum reservoirs, experimental data regarding the behavior of water in hydrocarbon-water systems is of increasing engineering importance. A survey of literature (Table I) shows that data of these types are fragmen-tary at temperatures above the hydrate region. Experimental data taken from the authors' recent investigation of the meth-ape-n-butane-water system are presented.17

Jan 1, 1947