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By H. I. Aaronson

Isothermally formed plates of proeutectoid a, lengthen at approximately the rates predicted by the Zener-Hillert equation, indicating that their lengthening kinetics are controlled by the volume diffusion of chromium in the ß matrix. Solution annealing treatments in the vicinity of the transus introduce a second mode of transformation, in which the lengthening rate is at least 1.8 x 104 faster than predicted by this equation. Little or no volume diffusion appears to accompany the latter transformation. The Presence of oxygen is evidently a Prerequisite for the occurrence of this reaction. X HE effects of thermal history prior to the initiation of transformations which proceed by nucleation and diffusional growth are currently evoking considerable interest. The rate of nucleation (but not the rates of growth) of pearlitel and of bainite,2 and the over-all rates of aging reactions in Al-cu3 and Al-si4 alloys have been shown to be appreciably dependent upon thermal history in the solid-solution region"' or in the two-phase region prior to the onset of pre~ipitation.3,4 In none of these reactions, however, was the transformation mechanism changed by variations in the temperature-time path used to reach the reaction temperature. Preliminary experiments reported by M. K. McQuillan5,8 and a systematic investigation by Farrar and Margolin7 have disclosed that the transformation behavior of hypoeutectoid Ti-Cr alloys is considerably more sensitive to thermal history. Qualitative evidence strongly suggests that not only the rate of nucleation but also the rate of growth and even the mechanism of the ß — a reaction can undergo remarkable changes when a solution annealing treatment in the vicinity of the ß/a +ß, or transus temperature, is interposed between a high-temperature solution anneal (conventionallq at 1000°C) and the isothermal reaction treatment. The present investigation was undertaken in an attempt to ascertain the nature and origin of these effects. Study of the changes in the kinetics and morphology of the ß - a, reaction produced by varialtions in thermal history was the primary means employed for this purpose. EXPERIMENTAL PROCEDURE The compositions of the alloys used in this in~esti~ation are given in Table I. These alloys were homogenized for 5 days at 1050° C in evacuated (2 x 10 -5 mm of Hg), zirconium-gettered fused quartz capsules. The capsules themselves were enclosed in a porcelain chamber evacuated with a mechanical pump during the homogenization anneals. Upon completion of homogenization, the alloys were cooled to room temperature and then reheated to 550°C for 3 1/2 days in order to transform the alloys to a finely divided mixture of a and TiCr2, and thus provide an approximately constant initial mi-crostructure. Individual specimens were sealed in evacuated and internally gettered Vycor capsules and heat treated as previously described.8,9 EXPERIMENTAL RESULTS Ti-10.64 Pet Cr. This investigation was largely performed on the 0.64 pet Cr alloy. The "base"

Jan 1, 1962

By W. A. Anderson, R. F. Mehl

RECRYSTALLIZATION of cold-worked metals has long been known to proceed by a process of nucleation and growth.1 When a cold-worked metal is heated to a temperature at which recrystallization will ensue, nuclei of new grains, essentially strain-free, appear and grow. As the process proceeds, nuclei continue to appear and to grow, until the cold-worked matrix has been entirely consumed and recrystallization has been completed (Fig. I). Conducted isothermally, a measurement of the fraction of the matrix recrystallized plotted against time, yields an isothermal recrystallization curve, showing the time course of the recrystallization process (Fig. 2).2 Evidently, then, the rate of recrystallization is determined by the rate at which nuclei form and the rate at which they grow. The rate of nucleation N is the number of nuclei that form in unit time in unit volume of the unrecrystallized matrix, and the rate of growth G is the increase in radius of the recrystallized grain per unit time. In recent years attempts have been made to determine N and G as these vary with the well-recognized variables affecting recrystallization: time, temperature, degree of deformation, etc.' Such studies yield information that is more fundamental than that conveyed by the conventional recrystallization diagram,' since the rate of recrystallization is thus analyzed into its two component rates.2 Methods are now available by which N and G can be measured, and analytical expressions have been developed for the interrelationships among N, G, the isothermal recrystallization curve, and the final grain size, which greatly facilitate analysis.2-4 The application of these methods has been demonstrated recently for the recrystallization of silicon ferrite.2 Data on N and G in dependence upon the recognized recrystallization variables are, however, very fragmentary;* values of N and G have been determined for some metals, but the effect of temperature, which would yield the fundamentally important activation energies, has been too little studied. Thus far there has been no detailed study of the recrystallization of any one metal in terms of N and G over appreciable ranges of the variables time, temperature, degree of deformation, and original grain size. It is the purpose of the present paper to provide such a study, employing aluminum.

Jan 1, 1945

By S. J. Matas, R. F. Hehemann, R. H. Goodenow

The hot-stage metallographic method has been employed to determine radial growth rates of upper and lower bainite. Lower bainite appears to grow as individual plates that increase in both length and thickness while upper bainite grows as sheaves of closely spaced plates or needles. A discontinuity in the temperature dependence of the growth rate appears to be associated with the transition from upper to lower bainite and stepped quenching experiments suggest that lower bainite will not continue to grow when the temperature is raised to the upper range. Thus, a single process does not appear to control the growth of both upper and lower bainite. A tentative model based on the forces acting on a dislocation interface is proposed to account for the slow growth of bainite. It has been recognized since the early studies of Davenport and Bain that a close relationship exists between the martensite and bainite transformations in steels. However, diffusion of carbon during the transformation has lead to considerable controversy concerning the reaction mechanism.1-7 Many studies4,5,7-9 have emphasized the structura and kinetic aspects of the bainite reaction and, in particular, the difference observed between the two forms of bainite—frequently termed upper and lower bainite. A kinetic difference between the two types of bainite has been revealed in the activation energy determined from the overall reaction;4,5 however, many difficulties arise in an interpretation of these activation energies since a number of temperature dependent factors contribute to the kinetics of the overall reaction. The displacive surface relief10 accompanying the bainite reaction permits a separation of the nuclea-tion and growth contributions to the reaction and allows the kinetics of the growth process to be examined. Several investigations of this type have been conducted; however, they have been restricted to the low temperature range.3'6'11 Here, bainite plates are observed to grow slowly in both length and width. The present investigation extends such studies to include the upper bainite range. MATERIALS AND PROCEDURE Materials. The composition of the steels studied in this investigation are presented in Table I. The range of composition permitted a study of the effect of carbon content on the growth rate of upper bainite in the 9 pct Ni steels and consideration of both upper and lower bainite in the higher carbon steels. These steels were received as hot-rolled rounds and were forged to approximately 1/2 in. thick plates for preparation of metallographic specimens. In order to produce an essentially zero carbon steel, Steel A was decarburized in wet hydrogen at 1550°F for 15 days with the result tabulated as Steel AD. Experimental Procedure. In order to study the slow growth of the displacive transformation product, a commercially available Leitz hot stage was modified to permit heating of the specimen by its own resistance in a manner similar to that employed by other investigators.6 The furnace chamber was maintained at a pressure of 2 to 3 X 10-5 mm Hg prior to austenitizing at 2000° ± 12° F for 5 min. Samples could be cooled from the austenitizing to the transformation temperature in approximately 15 sec and the progress of transformation was recorded with a 9 cm by 12 cm single frame camera or a 16 mm movie camera. RESULTS AND DISCUSSION Growth Characteristics. The general growth characteristics observed in this investigation were analogous to those reported previously.3,6,11 Typical growth sequences for the high temperature and low temperature forms are illustrated in Figs. 1 to 5. In both temperature ranges, bainite plates increase in length at slow, temperature dependent rates until interrupted by a grain boundary, another plate, or

Jan 1, 1963

By Arthur S. Dwight

From the latest and best literature on lead-smelting, little can be learned concerning the present state of the art of mechanical feeding in the United States. H. O. Hofman, in his Metallurgy of Lead (5th ed., 1899), briefly describes the main features of the system in use at Pueblo, Colo., and later (p. 235) says " the only successful mechanical feeding, as far as the writer is aware, is that found at the works of the Pueblo Smelting and Refining Co." H. F. Collins, in his Metallurgy of Lead and Silver (London, 1899), covers American practice pretty thoroughly; but as to mechanical charging, he says: "The German plan of taking off the gases by means of a small iron pipe suspended in the center, and the plan of charging by means of cup and cone, as in iron blast-furnaces, have both been tried, but have not found favor, chiefly on account of the difficulty of obtaining free access to the furnace-shaft for barring, etc., with such devices."' . H. W. Hixon, in his Notes on Lead and Copper Smelting (3d ed., New York, 1900), gives a description and drawing of the Hixon feeding device, as originally installed at East Helena. Evidence that this system of feeding has passed its experimental stage, and deserves more serious consideration than it has heretofore received, is furnished by two large plants—the Pueblo and the East Helena—of the American Smelting and Refining Co., where mechanical feeding has been in continuous and successful operation for a considerable period; one new plant now erecting at Salt Lake City, Utah, and one old one belonging to the same company, the El Paso works, now being rebuilt after a disastrous fire, in both of which mechanical feeding is to be a prominent feature ; one new plant of an independent concern at Torreon, Mexico, which will adopt mechanical feeding; and a number of other smaller plants, among

Jan 1, 1902

By Cecil Desch

THIS annual lecture, under the auspices of the Institute of Metals Division, and which was illus- trated by lantern slides, has been printed in full and a limited number are available for distribution on request. Some excerpts from the lecture are given below: Ever since the simple geometrical relations of crystals were discovered, it has been recognized that their proper-ties are best explained by assuming that their ultimate particles are arranged on a space lattice, and that the char-acteristics of that lattice determine the shape of the crystal and its physical and mechanical properties. Modern ex-amination by means of X-rays has widened that concep-tion and given it greater; definiteness, and the atoms are now regarded as the particles forming the space lattice. The splendid achievements of investigators in this field have made it possible to state, for a large number of sub-stances, the form and dimensions of the lattice. The char-acteristic of a lattice is that a unit of simple geometrical form is repeated at regular intervals in three dimensions so as to fill the entire crystal. It follows that there must be certain planes in which the atoms are more closely packed than in planes drawn at any angle to them, and it is these planes of closest packing which play the greatest part in determining the growth and other properties of the crystal. There are actually two stages in crystallization, what-ever be the medium in which it occurs. The first is the ap-pearance of crystal nuclei; the second the growth of those nuclei to form crystals of appreciable .size. The first is clearly a kinetic phenomenon. In the molten mass, solu-tion, or vapor, the molecules are in a state of rapid motion and frequent collision. When the temperature has fallen so far. that it is possible for a crystal to exist, a few col-liding molecules may fail to rebound, and so become at-tached to one another, the balance between the attracting and repelling forces-between them causing them to arrange themselves on a space lattice, to which other molecules sub-sequently attach themselves. It was once maintained that the X-ray evidence demanded that the molecule should dis-appear in the solid crystal, but this was a wrong inference, and in many crystals, but not in all, the chemical molecule retains its identity in the solid state. In pure metals the atom and the molecule are identical, so that the conditions are unusually simple. How many. nuclei will be formed in a given mass is evi-dently a problem in probability. Experiments to deter-mine the relation between the temperature and the number of nuclei formed in a given time have been made with some success by using viscous organic substances, but metals offer much greater difficulties, and the few determinations which have been published are vitiated by serious errors. However, the examination of sections of ingots of the same composition and cast at 'the same temperature in similar molds will show, that the number of crystals does not vary widely.

Jan 3, 1927

By T. Egleston

The importance of making analyses of gases in furnaces which are used for metallurgical purposes is every day growing more and more evident. It is the only method of understanding the reactions that take place in the furnace, and of economically conducting the operations both with regard to the fuel used and the reactions which take place on the bodies to be subjected to the influence of the heat and gases. As a knowledge of the composition of gases is becoming every day more necessary to the proper conduct of furnace operations, it seems desirable that furnace managers should generally know that the analysis of gas for commercial purposes is neither difficult, tedious, or expensive, and that it does not necessarily imply the use of corrections requiring difficult instrumental observations and long and tedious mathematical calculations. Any method, therefore, which will tend to render these analyses simple will also tend to having them made and repeated as frequently as the analyses of the ores and other materials charged in the furnace. They should be made even more frequently, as their composition is affected by any change in the condition of the furnace, and a knowledge of their composition will give a ready clue to the unseen and otherwise not easily detected changes which are taking place. The only practicable method of making industrial analyses of gas is that of measuring volumes in graduated tubes. The methods by

By T. PH. D. Egleston

THE importance of making analyses of gases in furnaces which are used for metallurgical purposes is every day growing more and more evident. It is the only method of understanding the reactions that take place in the furnace, and of economically conducting the operations both with regard to the fuel used and the reactions which take place on the bodies to be subjected to the influence of the heat and gases. As a knowledge of the composition of gases is becoming every day more necessary to the proper conduct of furnace operations, it seems desirable that furnace managers should generally know that the analysis of gas for commercial purposes is neither difficult, tedious, or expensive, and that it does not necessarily imply the use of corrections requiring difficult instrumental observations and long and tedious mathematical calculations. Any method, therefore, which will tend to render these analyses simple will also tend to having them made and repeated as frequently as the analyses of the ores and other materials charged in the furnace. They should be made even more frequently, as their composition is affected by any change in the condition of the furnace, and a knowledge of their composition will give a ready clue to the unseen and otherwise not easily detected changes which are taking place. The only practicable method of making industrial analyses of gas is that of measuring volumes in graduated tubes. The methods by

Jan 1, 1877

By Arthur Philips

THE purpose of this paper is to present certain data and observations resulting from a series of experiments dealing with the heat treatment and microstructure of commercial white cast iron and its derivative, malleable iron. In planning the experimental work, particular pains were taken to secure for the tests white cast iron of "normal" composition; i.e., within the composition limits commonly prescribed by manufacturers of malleable castings. A review of the literature leads us to believe that much data of a fragmentary character treating of the graphitization of white cast iron have been of little value, mainly because of the diversity in chemical composition of the materials employed in the tests. Moreover, when feasible, annealing periods at least comparable to those of current practice have been adopted. We wish to acknowledge our indebtedness to the members of the research department of the Eastern Malleable Iron Co. for the white cast iron used in the tests and, particularly, for their active cooperation during the experimental stage of the work. In this paper the following subjects will be discussed in the order indicated: Data on the thermal critical points of white cast iron and malleable iron. Changes produced in tensile properties and microstructure of white cast iron by annealing at different temperatures within the range, 760 to 1100° C. Relation of thickness of wall section of hard iron to microstructure and tensile properties of malleable iron obtained under normal annealing conditions. Notes on mechanics of graphitization of normal white cast iron as observed in specimens quenched after various periods of anneal at approximately 800° C.

Jan 1, 1922

By O. E. Kiessling

THE Committee-on Production Control, at its meeting held during the last annual session in February, 1930, evidenced great interest in problems of stabilization affecting all mineral industries. . No immediate program of activity for the Committee as a- unit was decided on, however,, and efforts during the past pear have consisted lirgely of further stressing the economic aspects of mineral production and of the action by committee members, :.serving in their individual capacities, in sponsoring constructive changes, in specific, industries. Of greatest interest to the general subject of production control in 1930 was the very definite advance toward better coordination of demand and supply in the petroleum industry. Furthermore, since opinion both within and without the oil industry now favors a constructive program, and with a gradual change in legal precedents, it seems not unreasonable to expect greater progress in the near future.

Jan 1, 1931

By W. R. Ingalls

In reviewing the history of the metallurgy of zinc, I shall pass hastily over what is only of antiquarian interest. That has been excellently treated by Dr. Bernhard Neumann in "Die Metalle" (1904) and has been described briefly in my "Production and Properties of Zinc" (1902), in my "Lead and Zinc in the United States " (1908), and in other metallurgical works of more or less the same date. In this present monograph, I have it in mind to confine myself mainly to technical practice, especially to that of the last 75 years, prior to which period advance was slow and of no great moment. The ancients made brass by the cementation process, i.e., embedding copper in a mixture of calamine and carbon and heating, whereby zinc oxide was reduced and zinc was vaporized and combined with the copper. Zinc was isolated by some of the alchemists, who named it and knew something of its properties, but made no use of it. Long before then, however, zinc was produced in India. Later it was produced in southern China. Possibly the Chinese obtained their knowledge from India. The Chinese in remote places still produce small quantities of zinc. I have seen photographs of their furnaces; or pots, for they hardly deserve the dignity of being called furnaces. I imagine that they are the same that were used centuries ago, for I cannot conceive of anything more primitive. Anyway, it is certain that the idea of a commercial production of zinc in Europe was imported from the Orient, where the metal was known in commerce as Speauter and Spiauter, whence speltrum and finally our term spelter. Tutanego and Tuteneague are other old names. Dr. Isaac Lawson went to China about 1730, expressly to discover the method of its production. What connection there was between Isaac Lawson and John Champion we do not know, but the latter obtained in 1739 a patent for a process of distillation downward and at some time between 1740 and 1743 erected a works at Bristol and actually began the manufacture of spelter. A production of 200 tons per annum is mentioned. In about the year 1766, Rishop Watson visited the Champion works and saw the process in operation, which previously had been

Jan 1, 1937

By E. T. Turkdogan, Klaus Schwerdtfeger

OelSEN and Maetz1 detected some 20 years ago the existence of a miscibility gap in iron oxide-CaO-P2O5 slags melted in iron crucibles at about 1400°C. Because of the importance of this system for the dephos-phorization of steel in the basic Bessemer process, equilibria between liquid iron and selected iron oxide-CaO-P2Q slags have been measured since by numerous investigators.2-5 When in equilibrium with metallic iron, the iron oxide of the slag is present mainly as FeO. In connection with oxygen-blowing steelmaking processes, it is useful to know the phase relations in the slag system at higher oxygen pressure, when major parts of the iron oxide are present as Fe2O3. This problem was investigated by Turkdogan and Bills7 by equilibrating the oxide mixtures contained in platinum crucibles with CO2-CO mixtures at 1550°C. It was found that increasing the Fe2O3 content decreases the composition range of the miscibility gap strongly so that the miscibility gap has almost disappeared at pco2/pco = 75. This result was refuted by the careful work of Olette et a1.,''' who equilibrated their slags with controlled Ha-H2-Ar gas mixtures. Their equilibrium measurements, at 1600°C and at oxygen pressures of 5 x 10"* and 10"5 atm, showed that the oxidation state of the iron has almost no influence on the formation of the miscibility gap. The present experiments were undertaken to check the previous results of Turkdogan and Bills. The experiments were performed at 1625°C in the strongly oxidizing atmosphere of air (PO2 = 0.20 atm) for which no experimental data are available. About 10 g of slag were melted in platinum crucibles and held at constant temperature for 1 hr. After equilibration, the crucible was rapidly pulled out of the furnace and cooled in air. The platinum crucible was removed from the sample. The two slag layers were carefully separated with a small diamond disc, and the surface of the top layer, which may have changed its oxidation state during cooling, was removed. The slags were crushed and analyzed chemically for CaO, P2O5, Fe2+, and Fetotal. The starting mixtures were prepared by sintering the desired amounts of reagent-grade 2CaO . P2O5 - H2O, CaCO3, and Fe2O3. Sintering and subsequent crushing were done three times to ensure homogenization. Molybdenum wire resistance heating was used. The furnace was provided with a recrystallized alumina reaction tube which was left open to air at the top. The temperature was controlled electronically. The reported temperature was measured with a Pt/Pt-10 pct Rh thermocouple and is estimated to be accurate within +5°C. The composition of the equilibrated melts is given in Table I. For the graphical illustration of these quaternary slags the type of projection suggested by Trömel and Fritze10 was used. In this representation, Fig. 1, the composition point of a mixture within the tetrahedron Fe2O3-CaO-P2O5-FeO is projected into the Fe2O3-CaO-P2O5, triangle (triangle I) so that the direction of projection is parallel to the side FeO-Fe2O3, and into the triangle Fe2O3-P2O,-Fe0 (triangle 11) so that the direction of projection is parallel to the side CaO-P2O5, of the tetrahedron. The projected point has the coordinates wt pct CaO, wt pct P205, and wt pct (FeO + Fe2O3) in triangle I and wt pct FeO, wt pct Fe2O3, and wt pct (CaO + PzO5) in triangle 11. Both triangles are turned into the same plane around the Fe203-P20, side of the tetrahedron. An illustration of the projection of a quaternary point in the present system is shown in Fig. 1. The advantage of this type of projection is that all four components for an equilibrium curve can be read directly from the diagram. The present results are shown graphically in Fig. 2. The curves depicting the miscibility gap are dashed in parts where no experimental points were obtained. The composition range covered by the miscibility gap

Jan 1, 1968

By Tracy L. Atherton

The mapping of slant-hole oil fields is complicated by the fact that relationships between wells are subject to variations in three dimensions and are not readily adaptable to representation on a plane surface. Formalized perspectives usually expand into an undecipherable maze of lines and peg models with the necessary supporting dividers serve only to awe the beholder with their perplexity. The usual compromise arrived at is a plotting of the projection of the courses of all of the wells in the field onto a horizontal plane (Fig. I). These complicated plots, when used in conjunction with the individual vertical projections of the wells, heretofore have been the most practical foundation for the study of general field problems. This method has many shortcomings, however, which arc not found in the recently developed straight-hole equivalent projec-tion method. The new method supplies a series of maps similar to the type now in common use in straight-hole fields. It is remarkably simple to use and supplies a ready check on clearances between wells. Perhaps the method can best be understood if the steps that led to its development are described. Common practice of oil-well surveyors is to supply the owner with a tabling of the survey and a plan view plotted against the true meridian. If a vertical projection is plotted, it is usually plotted separately and shows vertical depths against the projection of the stations along a section line joining the top and bottom of the hole on the plan view. A more practical method would be to plot the section line of the plan parallel to the abscissa of the vertical projection (Fig. 2). If this is done, any line parallel to the "base line1' will pass through the points on each projection that represent a single point in the hole. Another very useful graph, which the well surveyor could provide, would be plotting of vertical depths against measured depths. Fig. 3 illustrates the next step facilitated by this form of plotting. The lines designated "well A" represent the proposed course of a hole to be drilled. Superimposed on the drawing, in its proper relative position, is the plan view and a portion of the vertical projection of a present producer, well B." From an inspection of the plan view we arrive at the correct conclusion that the only indicated possibility of collision is at the point of crossing of the wells on the plan view. Referring to the vertical projection, note that the vertical depths of stations on B, in the vicinity of the crossing, are plotted on the same plane of projection as A. The clearance is the indicated distance between the two vertical sections measured along the parallel to the "base line," which passes through the point of intersection of the plan view. Repeat this process for the other wells crossing the proposed course of A on the plan view and you have a preliminary check of clearance for the proposed course. A similar comparison of crossings on the vertical projections of all >

Jan 1, 1941

By Tracy L. Atherton

The mapping of slant-hole oil fields is complicated by the fact that relationships between wells are subject to variations in three dimensions and are not readily adaptable to representation on a plane surface. Formalized perspectives usually expand into an undecipherable maze of lines and peg models with the necessary supporting dividers serve only to awe the beholder with their perplexity. The usual compromise arrived at is a plotting of the projection of the courses of all of the wells in the field onto a horizontal plane (Fig. I). These complicated plots, when used in conjunction with the individual vertical projections of the wells, heretofore have been the most practical foundation for the study of general field problems. This method has many shortcomings, however, which arc not found in the recently developed straight-hole equivalent projec-tion method. The new method supplies a series of maps similar to the type now in common use in straight-hole fields. It is remarkably simple to use and supplies a ready check on clearances between wells. Perhaps the method can best be understood if the steps that led to its development are described. Common practice of oil-well surveyors is to supply the owner with a tabling of the survey and a plan view plotted against the true meridian. If a vertical projection is plotted, it is usually plotted separately and shows vertical depths against the projection of the stations along a section line joining the top and bottom of the hole on the plan view. A more practical method would be to plot the section line of the plan parallel to the abscissa of the vertical projection (Fig. 2). If this is done, any line parallel to the "base line1' will pass through the points on each projection that represent a single point in the hole. Another very useful graph, which the well surveyor could provide, would be plotting of vertical depths against measured depths. Fig. 3 illustrates the next step facilitated by this form of plotting. The lines designated "well A" represent the proposed course of a hole to be drilled. Superimposed on the drawing, in its proper relative position, is the plan view and a portion of the vertical projection of a present producer, well B." From an inspection of the plan view we arrive at the correct conclusion that the only indicated possibility of collision is at the point of crossing of the wells on the plan view. Referring to the vertical projection, note that the vertical depths of stations on B, in the vicinity of the crossing, are plotted on the same plane of projection as A. The clearance is the indicated distance between the two vertical sections measured along the parallel to the "base line," which passes through the point of intersection of the plan view. Repeat this process for the other wells crossing the proposed course of A on the plan view and you have a preliminary check of clearance for the proposed course. A similar comparison of crossings on the vertical projections of all >

Jan 1, 1941

By PHILIP N. MOORE

THE problem of managing the policies of the Institute so that a middle course may be drawn between the close control of a few who are so situated that they can give continuing attention and intermittent control by occasionally present directors presentation .of the subject is to bring clearly before the membership of the Institute a summary of the attendance at the Directors' meetings for the past four years.

Jan 1, 1924

By E. J. Rapperport, J. P. Pemsler

Proton irradiation of high-purity distilled berylliuwz was utilized to introduce various hydrogen contents from 0.00075 to 0.075 at. pct (0.83 to 83 ppm) in a band 0.004 cm wide. After irradiation, the specimens were heat-treated to effect hydrogen agglomeration. Observations of agglomerates in all specimens of the lowest hydrogen content indicate a hydrogen solubility of less than 0.83 ppm in the temperature range 350" to 1050°C. Estimates of the inter diffusion coefficient in the hydrogen solid solution of beryllium were obtained from measurements of the dimensions of hydrogen-depleted zones survounding agglomerated bubbles. A value of (approximately) 3 xlo-' sq cm per sec is obtained for the diffusion coefficient at 850" to 900°C. PREVIOUS investigators found that We solubility of hydrogen in beryllium is very small. Gulbransen and Andrew' state that beryllium does not react with hydrogen at 23 mm Hg between 300" and 900°C. Cotter ill et a1.' report that as-machined beryllium has an adsorbed hydrogen layer of 0.007 cu cm per sq cm of surface. No additional hydrogen is picked up in hydrogen at 0.1 mm Hg and between 200" and 80O°C, or when hydrogen is bubbled through molten beryllium. Beryllium hydride has been reported to exist in an ether solution,394 but decomposes at about 200°C; there is no substantial evidence for the existence of the hydride in the solid phase.

Jan 1, 1964

By E. T. Stephenson

Wert and Marx1 pointed out that a straight-line relationship exists between the activation energy of a relaxation process and the temperature at which the maximum relaxation occurs. The data available at the time indicated that this relationship held for a number of Snoek peaks, several grain boundary peaks, and pair relaxation in a brass. Theoretical justification for the observed relationship was found in the following equation, which Wert and Marx derived from the theory of interstitial atomic diffusion coefficients:' where AH is activation energy, R is the gas constant, T is the internal friction peak temperature, v is the interstitial atomic frequency, f is the frequency of the applied stress, S is entropy of activation. More accurate internal-friction data on interstitial diffusion in bcc metals have become available since Wert and Marx's paper. Table I gives activation energies calculated by several authors from a combination of elastic aftereffect data and the peak temperatures at several frequencies of measurement. (In the case of Fe-C and Fe-N, the referenced authors5'7'8'10 also used high-temperature diffusion data.) However, diffusion experiments at 150°C and above1'-13—rather than anelastic techniques—were used to determine the activation energy of hydrogen diffusion in Fe-H. In order to plot this recent data as a AH vs T graph we calculated the peak temperatures of the systems listed in Table I (with the exception of Fe-C, Fe-N, and Fe-H) by using published values3'' of AH and Do. These calculated peak temperatures varied by only a few degrees from experimentally determined peak temperatures. The calculated values were felt to represent the better average. A number of investigators have found the peak temperatures in Fe-C and Fe-N to be 38 to 40°C and 20° to 24°C, respectively. The values of 39" and 22°C (312° and 295°K in Table I) were determined by carefully executed experiments.6'8 The hydrogen peak temperature has been measured at 1 cps,12 20 cps,14 and 35,000 cps.15 All hydrogen peak temperatures were adjusted to 1 cps for Table I using AH = 3000 cal per mole. As Fig. 1 shows, the data of Table I fit a straight line at least as well as the earlier data used by Wert and Marx. Linear-regression analysis was applied to the data in Table I. The Fe-H data was omitted because the activation energy has not been experimentally determined in the temperature range of the peak. The analysis yields the equation: with a standard error of 860 cal per mole. The agreement of the data in Table I with the Wert-Marx equation is excellent. Strict application of Eq. [I] forces the linear regression analysis through the origin. In this case, the analysis gives a slope of 62.1 cal per mole per deg, and a standard error of *890 cal per mole. With this value, it follows from internal-friction theory that Hence, Do varies by only 30 pct among these bcc-interstitial systems. Thus, a concept suggested originally by Wert and Marx1 is confirmed by recently published data. The

Jan 1, 1965

By Alfred H. Bell

IN 1945, Illinois produced 75,210,000 bid. of oil, or 4.4 percent of the total for the United States, and ranked sixth in the nation in oil production for the third consecutive year. Production decreased about 3 per cent from that of 1944, when the total Illinois production was 77,413,000 bbl. This is the smallest percentage of decrease in production in the state for any year since a peak was reached in 1940. Daily average production for 1945 was approximately 206,000 bbl. Daily averages by months were as follows:

Jan 1, 1946

E. D. TILLYER,* Southbridge, Mass. (written discussion?).-It is quite generally known that there is very little that is standard about a mercurial thermometer at temperatures above 212° F. (100° C.) because so many precautions must be taken-precautions that are rarely realized in practice-such as depth of immersion, aging, elastic fatigue, separation of mercury column, and accidental deformation from very slight excess temperature. One cannot help wishing that Mr. Brown would dwell at greater length on the practical side of both radiation and optical pyrometey, both of which have great possibilities as commercial instruments. In the radiation pyrometer we have ideal conditions for a permanent instru-ment, no materials being exposed to excessive temperatures or subjected to contamination from the furnace fumes which may raise such havoc with an ordinary pyrometer. The development of a radiation pyrometer requires a thermocouple having a relatively high electromotive force but which need stand temperatures of only 200° F. or 300° F. instead of 1500 to 2000° F., which is required of even a base-metal couple. The galva-nometer, if located near the thermocouple, does not need to have a high resistance as at such low temperatures no changes can occur in the thermocouple that will affect its resistance and, consequently, the in-dicated temperature.

Jan 11, 1919

By H. Eklund, R. T. Hukki

This article presents a simple arithmetic derivation for the relationship between sharpness of classification and circulating load, as well as world-wide industrial data which are compatible with the derived equation. It is shown that the sharpness of classification decreases with increasing circulating load. Based on the evidence available a comparison is presented between the performance of the present-day hydraulic classifiers. In a continuously operated closed circuit grinding system the tonnage and the fineness of the components may be indicated as follows: Eq. 8 expresses the relationship between sharpness of classification and circulating load in closed grinding circuits. If CL = 0, E = 100% according to the definition used. This, however, is a purely theoretical case because any apparatus to be called a classifier must produce the conventional two products. Furthermore, if CL = m, E =0%. In order to visualize the meaning of Eq. 8, the effect of factors d (fineness or percentage of under-size of classifier overflow at size x) and b (fineness or percentage of undersize of classifier sands at size x) should be studied. By the most rigid standard, factor d should be given the value of 100%. By so doing the size of classification is defined as that screen size x through which 100% of the classifier

Jan 1, 1965

By O. C. Wheeler

The activity in exploration and in the acquisition of prospective oil lands that reached such a high level in Colombia during 1936 gained momentum and reached unprecedented proportions during 1937. Both national and private lands were taken up. In the Magdalena Valley above Puerto Berrio, leases on large tracts of private lands are held by Richmond (Standard of California), Shell and Texas. Tropical also owns leases covering a block of acreage in this area near Honda. From Puerto Berrio to El Banco most of the acreage is of national ownership, and concessions covering parts of this area have been granted to Tropical, Socony Vacuum, Shell and others, while applications for additional concessions are pending. Latterly leases on private lands below the Lebrija River have been taken out by Shell and Richmond. In the drainage basins of the Meta and Guaviare Rivers of the Llanos region of eastern Colombia, several of the major companies have carried on geological exploration and it is understood that some private properties have been leased or optioned. Under Colombian law, subsoil rights are reserved to the nation on all lands that passed from Government ownership after Oct. 28, 1873. Private titles antedating that day carry both surface and subsurface rights. Conditions under which lands may be acquired, explored and

Jan 1, 1938