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US 4,185,193-Method of assaying the vicinity of a borehole for uranium ore or thorium ore. A pulsed neutron source IS operated to irradiate the earth formations with fast neutrons. A detector responds to the delayed fission neutrons emitted by the ore as a measure of ore concentration and to the delayed neutrons from oxygen-17 as a measure of the neutron output of the source. The measurement of ore concentration is corrected In accordance with the measured changes in the neutron output of the source. R L. Caldwell, assigned to Mobil Oil Corp. Jan. 22, 1980 4 pp (250-269). Filed: 5-18-78 (906,907).

Jan 1, 1982

By N. A. Gjostein

The self-diffusion coefficient D, for a surface near the (100) plane in copper was determined by means of the Mullins theory of thermal grooving, and was found to obey the Arrhenius relationship, and Do = 6.5 x 10' sq cm per sec. Suppression of surface diffusion by chemisorbed impurities encounters difliculties as a satisfactory explanation for the large Q, and Do. Instead, a model is presented which indicates that Q,, as determined by a mass-transport technique, may involve both the energy needed to form an adsorbed atom from a ledge in the surface as well as that for the movement of the adsorbed atom.; LITERATURE reviews1-3 indicate that the mechanism of self-diffusion on metal surfaces is not clearly understood. The lack of experimental data on the temperature variation of the surface self-diffusion coefficient DJ has contributed greatly to this situation. Radioactive tracer techniques4-rn have been used to measure Ds, but for many years only Nicker-son and Parker8 had determined (for polycrystalline silver) an activation energy B, and a frequency factor Do for the surface self-diffusion process. Even in this case, a mechanism could not be clearly inferred because it was suspeted7 that a contribution from volume diffusion was not taken into account by the investigators. Some later work by Li and parkere on polycrystalline gold, in which they obtained essentially the same results as for silver and in which volume diffusion could be accounted for, seems to invalidate this criticism. In 1957, Mullins10'11 developed the theory for the thermal grooving process. This advance has opened a new and promising technique for measuring the surface self-diffusion coefficient Ds. Recognizing that a thermal groove may form by several different mass transport processes, Mullins first consideredlo the cases where a) the groove forms by evaporation and condensation or b) by diffusion along the groove surface, in either case, in a system where a metal surface is in contact with only its dilute vapor phase. In a later paper," he extended the treatment to cases where the groove forms by volume diffusion into c) the solid phase or d) by mass transport through a passive gaseous phase at 1 atm pressure. The time dependence of the groove dimensions and the shape of the groove profiles predicted by Mullins' treat-

Jan 1, 1962

By Eugene Rabinowitch

The Chemistry of Uranium. By Joseph J, Katz and Eugene Rabinowitch. Published by McGraw-Hill, Book Co. of New York, 1951. 609 P. $7.15.--This volume is the first half of a comprehensive treatise on uranium chemistry. It contains a detailed summary of the properties of the element uranium, including its occurrence in nature, extraction from ores, and the physical and chemical properties of uranium metal. Binary compounds of uranium with hydrogen, oxygen, nitrogen, and the halogens, among others, receive extensive discussion, including methods of preparation and physical properties such as crystal structure, thermochemistry and volatility. A very large proportion of the material in this volume is based on the results obtained in the laboratories of the Atomic Energy Project, much of it not published before. In addition, all of the open literature has been critically surveyed and integrated with the results of the Atomic Energy Project studies. Principles of Geology. By James Gilluly, Aaron C. Waters and A. O. Woodford. Published by W. H. Freeman & Co., San Francisco, Calif., 1951.640 P. $5.75.-This book attempts to summarize some of the knowledge that geologists have won from the study of the earth. It covers such subjects as movements of the earth's crust, records of earth movement, stream erosion and deposition, deserts, the ocean and mineral resources of the earth. The authors have concentrated on the analysis of processes that are at work upon and within the earth. rather than to present a catalog of descriptive facts and terms. The development of stratigraphy is also outlined. Pictures, maps, and tables are used to illustrate the major points of each chapter.

Jan 9, 1951

By J. C. McHardy

During 1980-2000, the Florida phosphate industry will deplete its central Florida Polk County reserves. As a result, new mines will be built in the so-called southern Florida reserve areas. These mines will require new mining, beneficiation, and tailings disposal technologies since southern reserves have different characteristics than have been encountered in the central Florida deposits. Furthermore, government regulations will necessitate development of new tailings and clay disposal methods. This paper reviews these challenges for the Phosphate industry and how these opportunities can be expected to effect plant design and plant operating practices.

Jan 1, 1984

By L. P. Teas

ALTHOUGH 1927 in the Arkansas-Louisiana territory will probably pass into history as a year of small profits and little new production, nevertheless during this period two large gas fields were developed; two new oil fields were discovered, and two new oil horizons, hitherto of minor Annual Production in Millions of Barrels FIG. 1.-PRODUCTION OF NORTH LOUISIANA AND ARKANSAS BY FIELDS FOR 1926 AND 1927. importance, were developed; In spite of the "hard times" some of the leading, supply houses did more business this year in this. district than in any year since 1920.

Jan 1, 1928

By David B. Reger

The expansion of the previously discovered gas pools and an intensified search for additional pools in the Oriskany and deeper sands were the principal petroleum activities in West Virginia during 1941. One small oil pool was discovered and another was considerably extended. One small gas pool was discovered, several isolated well discoveries were expanded into definite pools, and various recognized pools were substantially increased. The proved oil territory of the state was increased about 600 acres and the proved gas territory about 45,000 acres. The new discoveries of oil did not equal withdrawals but gas reserves added were greater than gas withdrawals. Oil activity, as in the past several years, was slight because of unfavorable crude prices. Most operators prefer to leave oil in the ground rather than to drill for it without a better return. Gas activity increased greatly because of better demand, even though the price of gas did not improve. The account of operations, as gathered from trade journals and other reporting services, shows that 838 new wells were drilled, resulting in 114 new oil wells with 2606 bbl. of daily new production; 558 new gas wells with 949,226,000 cu. ft. of daily open flow; and 166 dry holes. Also, 86 old wells were drilled to deeper sands with 9 bbl. and 56,030,000 cu. ft. of added production. On the new wells the oil average was 22.86 bbl. per well per day; and the gas average was 1,701,000 cu. ft. per well per day. On new wells the ratio of dry holes to completions was 13.61 per cent. On deeper drilling to other sands the ratio of failures was 15.12 per cent. From an exploratory standpoint one strictly new oil pool (Higginbotham Run) was opened in Kanawha County and one strictly new gas pool (Lost Run) in Taylor County. One entirely isolated wildcat gave commercial Oriskany-sand gas production and may open a pool. Various other wildcats greatly extended the boundaries of known Oriskany-sand gas pools and various others may have opened new pools in the shallow sands. On the other hand, various Oriskany tests in Harrison, Monongalia, Roane and Wood Counties were dry and all five tests to the White Clinton sand (Sil.) in Boone, Harrison, Kanawha and Wood Counties failed to find commercial production. The principal oil wells completed, by counties, were: Calhoun, 24; Clay, 7; Gilmer, 6; Hancock, 9; Kanawha, 9; Pleasants, 10; and Ritchie, 14. Production for the year was estimated by the Oil Weekly as 3,421,000 bbl., compared with U. S. Bureau of Mines final figures of 3,444,000 bbl. in 1940. The leading counties in gas-well completions were: Boone, 32; Braxton, 19; Cabell, 16; Calhoun, 46; Clay, 20; Gilmer, 37; Jackson, 94; Kanawha, 82; Lincoln, 17; Putnam, 46; Ritchie, 33; Upshur, 20; and Wayne, 33. Production for the year is estimated by the author as 210,000,000,000 cu. ft., as compared to the U. S. Bureau of Mines' final figures of 188,751,000,000 cu. ft.* in 1940.

Jan 1, 1942

By David B. Reger

The expansion of the previously discovered gas pools and an intensified search for additional pools in the Oriskany and deeper sands were the principal petroleum activities in West Virginia during 1941. One small oil pool was discovered and another was considerably extended. One small gas pool was discovered, several isolated well discoveries were expanded into definite pools, and various recognized pools were substantially increased. The proved oil territory of the state was increased about 600 acres and the proved gas territory about 45,000 acres. The new discoveries of oil did not equal withdrawals but gas reserves added were greater than gas withdrawals. Oil activity, as in the past several years, was slight because of unfavorable crude prices. Most operators prefer to leave oil in the ground rather than to drill for it without a better return. Gas activity increased greatly because of better demand, even though the price of gas did not improve. The account of operations, as gathered from trade journals and other reporting services, shows that 838 new wells were drilled, resulting in 114 new oil wells with 2606 bbl. of daily new production; 558 new gas wells with 949,226,000 cu. ft. of daily open flow; and 166 dry holes. Also, 86 old wells were drilled to deeper sands with 9 bbl. and 56,030,000 cu. ft. of added production. On the new wells the oil average was 22.86 bbl. per well per day; and the gas average was 1,701,000 cu. ft. per well per day. On new wells the ratio of dry holes to completions was 13.61 per cent. On deeper drilling to other sands the ratio of failures was 15.12 per cent. From an exploratory standpoint one strictly new oil pool (Higginbotham Run) was opened in Kanawha County and one strictly new gas pool (Lost Run) in Taylor County. One entirely isolated wildcat gave commercial Oriskany-sand gas production and may open a pool. Various other wildcats greatly extended the boundaries of known Oriskany-sand gas pools and various others may have opened new pools in the shallow sands. On the other hand, various Oriskany tests in Harrison, Monongalia, Roane and Wood Counties were dry and all five tests to the White Clinton sand (Sil.) in Boone, Harrison, Kanawha and Wood Counties failed to find commercial production. The principal oil wells completed, by counties, were: Calhoun, 24; Clay, 7; Gilmer, 6; Hancock, 9; Kanawha, 9; Pleasants, 10; and Ritchie, 14. Production for the year was estimated by the Oil Weekly as 3,421,000 bbl., compared with U. S. Bureau of Mines final figures of 3,444,000 bbl. in 1940. The leading counties in gas-well completions were: Boone, 32; Braxton, 19; Cabell, 16; Calhoun, 46; Clay, 20; Gilmer, 37; Jackson, 94; Kanawha, 82; Lincoln, 17; Putnam, 46; Ritchie, 33; Upshur, 20; and Wayne, 33. Production for the year is estimated by the author as 210,000,000,000 cu. ft., as compared to the U. S. Bureau of Mines' final figures of 188,751,000,000 cu. ft.* in 1940.

Jan 1, 1942

By Alexander Squire

A BRIEF study of the effects of material and processing variations upon the tensile properties of steel formed from mixtures of iron and carbon was made in order to provide information regarding the .properties obtainable in iron-carbon compacts as influenced by forming pressure, sintering temperature, and graphite particle size. Sintered steels formed from mixtures of iron and graphite have been studied by Stern,1 who investigated the effect of various percentages of graphite on compacts formed from electrolytic iron that were repressed and heat-treated after sintering. A further study, by Stern and Greenberg,2 is concerned with the heat-treatment of steels formed by the carburization of iron compacts, and Margolies3 has reported work on the simultaneous sintering and carburization of iron-powder parts. Glauch4 investigated the effect of various types of graphite on the properties of iron-carbon powder alloys but did not determine the effect of different particle sizes of the same graphite alloyed with different types of powder. In the investigation reported in this paper, powders typical of those produced by electrolytic deposition and the decarburization of shotted steel scrap were used. The powders were mixed by tumbling in a jar mill with graphite powder ground to an average particle diameter of 2, 4, 6, and 16 microns (as determined by microscopic measurement). The properties of the iron and graphite powders are presented in tabular form as Table I. In order to obtain the maximum information from a minimum number of test specimens, the study was divided into two sections with one set of specimens treated identically in each section as a basis for comparison. In the first section, iron powder produced by the shotting and subsequent decarburization of scrap steel was mixed with 2-micron graphite powder, pressed at 50,000, 100,000, and 200,000 psi, and sintered in hydrogen at 1200°C for the periods of time ranging from 15 to 120 minutes. In the second section of the investigation, electrolytic iron powder was mixed with graphite of an average particle diameter of 2, 4, 6, and i6 microns, pressed at 100,000 psi, and sintered at temperatures ranging from 1000° to 1200°C. for periods of time of 30 to 180 minutes. By following this procedure an indication of the effect of the following variables upon the density and tensile properties of iron-carbon powder compacts was obtained: (I) forming pressure, (2) sintering time, (3) particle size of graphite powder, (4) sintering temperature, (4) type of iron powder.

Jan 1, 1947

By J. D. Davis, A. C. Fieldner

The older coal chemist had a much simpler conception of coal than we have today. To him coal was a mineral composed essentially of carbon, hydrogen, oxygen, nitrogen, sulfur, ash, and water, in various proportions. His studies on the constitution of coal were directed along the conventional lines of proximate and ultimate chemical analyses and making deductions from these data without any real appreciation of the fact that coal is a conglomerate of various chemical compounds, including many of the most complex structures known to organic chemistry. The view of the modern coal chemist is well expressed by Franz Fischer,' who says that while proximate and ultimate analyses are important both from the scientific and technical point of view, they tell the chemist no more concerning the number and kinds of chemical compounds that constitute coal than the reader would learn of the contents of a book if told that the printed contents consisted of 15 per cent. of the letter "e," 5 per cent. of the letter "n," 1 per cent. of the letter"g," 4 per cent. of the letter "b," etc. As the reader must have the grouping of letters into words and words into sentences, so the chemist must have the grouping of atoms into molecules and the proportion of each molecular compound in the coal aggregate before he acquires an adequate knowledge of the constitution of coal. Modern investigators2 are laying the foundation of a new chemistry of coal based on the biochemistry of plants and the chemical changes involved in processes of fermentation and decay. As

Jan 1, 1925

By Kenzo Ikeda

The Kosaka smelter is situated in the extreme northern end of Hondo (the main island of Japan) 15 mi. east of Odate, on the government railroad, to which it is connected by a private railway. It contains ten blast furnaces having a maximum daily capacity of 1600 short tons of ore, conducting a slow pyritic smelting entirely without coke or limestone, and with a charge carrying over 50 per cent. of briquetted and agglomerated fines. The matte (35 per cent. Cu) is blown in two basic-lined barrel converters, the blister copper (98.8 per cent. Cu) being cast at once into anodes. The adjoining refinery contains 600 tanks with a maximum capacity of 1300 tons of cathodes per month, the byproducts being gold, silver, and bismuth. At present, working at about half capacity, the whole plant consumes 2000 kw. of hydro-electric power, and employs 850 men and women. The ores are derived from two principal sources: The relatively new Hanaoka mine, 20 mi. from the smelter, yielding copper pyrites by underground mining, and the old Kosaka open-cut mine, 1 1/2 mi. from the smelter, yielding three different ores: (a) kuromono, a compact finegrained mixture of barite (32 per cent.), zinc blende, galena, and pyrite, the whole carrying about 2.5 per cent. Cu; (6) cupriferous pyrites with 2.4 per cent. Cu; (c) siliceous ore with 2 per cent. Cu. The Hanaoka ore now constitutes approximately one-half of the charge, almost replacing the Kosaka kuromono which was the ore chiefly smelted until 1913.'

Jan 1, 1923

By Kenzo Ikeda

The Kosaka smelter is situated in the extreme northern end of Hondo (the main island of Japan) 15 mi. east of Odate, on the government railroad, to which it is connected by a private railway. It contains ten blast furnaces having a maximum daily capacity of 1600 short tons of ore, conducting a slow pyritic smelting entirely without coke or limestone, and with a charge carrying over 50 per cent. of briquetted and agglomerated fines. The matte (35 per cent. Cu) is blown in two basic-lined barrel converters, the blister copper (98.8 per cent. Cu) being cast at once into anodes. The adjoining refinery contains 600 tanks with a maximum capacity of 1300 tons of cathodes per month, the byproducts being gold, silver, and bismuth. At present, working at about half capacity, the whole plant consumes 2000 kw. of hydro-electric power, and employs 850 men and women. The ores are derived from two principal sources: The relatively new Hanaoka mine, 20 mi. from the smelter, yielding copper pyrites by underground mining, and the old Kosaka open-cut mine, 1 1/2 mi. from the smelter, yielding three different ores: (a) kuromono, a compact finegrained mixture of barite (32 per cent.), zinc blende, galena, and pyrite, the whole carrying about 2.5 per cent. Cu; (6) cupriferous pyrites with 2.4 per cent. Cu; (c) siliceous ore with 2 per cent. Cu. The Hanaoka ore now constitutes approximately one-half of the charge, almost replacing the Kosaka kuromono which was the ore chiefly smelted until 1913.'

Jan 1, 1923

By Michel T. Halbouty

The area for which oil and gas development is reported for 1938 in this paper is larger than that covered by the report for 1937, in that besides Duval, Jim Hogg, McMullen, Starr, Webb and Zapata Counties, comprising the Laredo district, this paper also includes the South Corpus Christi district, which is composed of the following counties: San Patricio, Nueces, Jim Wells, Kleberg, Kenedy, Brooks, Willacy, Hidalgo and Cameron, all heretofore included in A.I.M.E. Gulf Coast reports. In the map, Fig. 1, the area known as South Texas is represented by the counties south of the heavy black line. Production in the South Corpus Christi district, which covers an area that extends inland for 50 miles and follows the coast line, is primarily in zones ranging from the Catahoula, through the Frio sands, into the Vicksburg horizon. General exploration is done mainly with geophysics because in this district production is directly dependent upon structural conditions. In the Laredo district most of the production is from sand lenses; therefore, because these shallow sand lenses represent old shore lines which are monoclinic in character, the most satisfactory method of exploration in the Laredo district is drilling. This type of production centers around Duval County and follows a northeast-southwest trend along the Mirando district. Although drilling operations showed a decline from the preceding year, 1938 was highly successful as far as new discoveries and developments were concerned, and results of the year's operations should have an important effect on the near future trend of exploration and drilling. Besides the discovery of several new fields and many new sands in established fields, 1938 saw the discovery of a new Vicksburg sand trend and the first marine drilling off the South Texas Gulf Coast. Many new fields were discovered during the year, but only a few were subjected to an extensive drilling program. Several already established fields, especially in the Laredo district, received a large amount of drilling as new sands and extensions enlarged the producing areas, a

Jan 1, 1939

By Michel T. Halbouty

The area for which oil and gas development is reported for 1938 in this paper is larger than that covered by the report for 1937, in that besides Duval, Jim Hogg, McMullen, Starr, Webb and Zapata Counties, comprising the Laredo district, this paper also includes the South Corpus Christi district, which is composed of the following counties: San Patricio, Nueces, Jim Wells, Kleberg, Kenedy, Brooks, Willacy, Hidalgo and Cameron, all heretofore included in A.I.M.E. Gulf Coast reports. In the map, Fig. 1, the area known as South Texas is represented by the counties south of the heavy black line. Production in the South Corpus Christi district, which covers an area that extends inland for 50 miles and follows the coast line, is primarily in zones ranging from the Catahoula, through the Frio sands, into the Vicksburg horizon. General exploration is done mainly with geophysics because in this district production is directly dependent upon structural conditions. In the Laredo district most of the production is from sand lenses; therefore, because these shallow sand lenses represent old shore lines which are monoclinic in character, the most satisfactory method of exploration in the Laredo district is drilling. This type of production centers around Duval County and follows a northeast-southwest trend along the Mirando district. Although drilling operations showed a decline from the preceding year, 1938 was highly successful as far as new discoveries and developments were concerned, and results of the year's operations should have an important effect on the near future trend of exploration and drilling. Besides the discovery of several new fields and many new sands in established fields, 1938 saw the discovery of a new Vicksburg sand trend and the first marine drilling off the South Texas Gulf Coast. Many new fields were discovered during the year, but only a few were subjected to an extensive drilling program. Several already established fields, especially in the Laredo district, received a large amount of drilling as new sands and extensions enlarged the producing areas, a

Jan 1, 1939

By B. F. Decker, D. Harker

The recrystallization reaction in OFHC and spectroscopically pure copper has been followed by X ray diffraction determinations of the amount of material with the cold-worked and recrystallized textures in specimens which had been given various heat treatments. The heats of activation for recrystallization are found to be: 29.9 kcal per rnol for OFHC copper and 22.4 kcal per rnol for spectroscopic copper. A reliable and speedy method for measuring the amount of recrystallized material in a piece of rolled metal, together with a new scheme for low temperature heat treatment, have made possible a determination of the activation energy for recrystallization in rolled copper. This method for studying recrystallization rates is different from others reported in the literature.' Oxygen free, high conductivity copper—OFHC copper—of purity 99.98 pct gave an activation energy for recrystallization of 29.9 kcal per mol with recrystallization data taken in the temperature range 208-245°C. Copper of purity 99.999 pct from the American Smelting & Refining Co. gave an activation energy for recrystallization of 22.4 kcal per mol with recrystallization data taken in the temperature range 43-135°C. The great change in activation energy for recrystallization as the small amount of impurity in the metal is decreased suggests that the motion of grain boundaries is conditioned by the impurities which must be concentrated in them. Thus the OFHC copper recrystallizes with an activation energy of the order of magnitude to be expected for the diffusion of the kind of impurities likely to be present. The high purity copper, on the other hand, recrystallizes with a much lower activation energy, in accord with the notion that the grain boundaries need not wait for the impurities to diffuse with them. Copper when strongly cold-rolled has a well-defined crystallite texture which can be described by saying that the [111] direction of the face- centered cubic crystals is aligned approximately in the cross-rolling direction and that faces of the form {110} lie approximately in the rolling plane. When such rolled copper is completely annealed the crystallite texture is quite different: the [loo] direction is in the cross-rolling direction and faces of the form (100) are in the rolling plane. At intermediate stages of annealing, the copper contains both textures. If a Geiger counter X ray diffraction spectrometer is set up so as to measure the intensity of the (200) Bragg reflection from the rolled surface of a piece of copper strip, this intensity increases from a very small value in the cold-worked state to a maximum as the specimen is annealed. The same would be true for (200) reflections from planes normal to the rolling or cross-rolling directions. In view of this fact, the amount of material in the copper which has recrystallized can be measured by comparing the intensities of one of these reflections just mentioned with the intensity from a similar specimen after complete annealing. In much the same way the intensity of (111) reflections from planes normal to the cross-rolling direction could be used to measure the amount of unrecrystallized material in the specimen. In the work to be described here the amounts of recrystallized and unrecrystallized material in partly annealed rolled copper specimens were determined in this way. Experimental Procedure Samples of oxygen free high conductivity (OFHC) copper, cold-rolled 99.7 pct to 0.002 in. thickness, were subjected to heat treatments for various chosen times at four different temperatures, and high purity copper samples, cold-rolled 98.0 pct to 0.0015 in. thickness, at six different temperatures. Each sample, after treatment, was placed in an orientation sample holder for use with a Geiger counter X ray spectrometer and a reading was taken of the intensity of the (200) reflection from planes perpendicular to

Jan 1, 1951

By G. Y. Chin, W. L. Mammel

The problem of selection of the active slip systems for a crystal undergoing an arbitrary strain has been analyzed by Taylor and by Bishop and Hill. The Taylor analysis is based on a principle of' virtual work, and involves finding, among numerous cotnbinalions of slip systems that satisfy the imposed strain, the combination in which the sum of the glide shears is a minimum. Previously, Taylor has treated the case of axisymmetric flow when slip occurs on (111)(110) (or {110)(111)) systems only. His analysis has now been extended by computer methods to the cases of slip on {112}(111) and {123)(111) systerns and of mixed slip on {110), {1 12), and (123) planes with a common (111) slip direction, all of which are important in the deformation of bcc crystals. The results are computer-plotted as contours of the ratio of the floe strength to the critical resolved slzea-r stress for slip, for axial orientations distributed throughout the standard stereographic triangle. Implications of the computer results to texture develop,merit, texture hardening, and dislocation theories oj work hardening are discussed. WhEN a single crystal is extended in the usual tension test, the lateral dimensions can change relatively freely. In this case, the glide shear produced by slip on a single slip system is sufficient to accommodate the (tensile) deformation. Since slip is governed by a critical resolved shear stress law (the Schmid law'), the single active slip system is one for which the stress, resolved on the slip plane and in the slip direction, is the highest among the several equivalent slip systems. This amounts to saying that a value M = U/t = y/~ is a minimum among the equivalent systems, where M is the inverse of the familiar Schmid factor (a and E refer to tensile stress and strain, and T and y refer to resolved shear stress and shear strain). A grain embedded in a polycrystalline aggregate, on the other hand, cannot freely change its shape due to constraint from its neighbors. In this case, slip from five independent slip systems (to accommodate five independent strains) is generally required.' Based on the principle of virtual work and assuming that the critical resolved shear stress for slip is the same for all systems, Taylor hypothesized that, among all combinations of (five) slip systems which are capable of accommodating the imposed strain, the active combination is that one for which the sum of the absolute values of the glide shears is a minimum. Again, this is equivalent to saying that the value of M = CjlyjI/ is a minimum, in analogy to the single slip case. Taylor aminimum,analyzed the case of {111)(110) slip for fcc metals, and applied the analysis to crystals undergoing axisymmetric flow, that is, the same macroscopic shape change as the poly crystalline aggregate under uniaxial tension (or compression). For the twelve equivalent {111}( 110) slip systems, there are 384 independent combinations of selecting five systems to satisfy the five independent linear equations of imposed strain.4 Taylor calculated the value of M for each combination* and obtained the active com- *A number of the independent combinations were omitted from consideration in Taylor's original work (see Ref. 5). bination (minimum M) for a number of axial orientations distributed throughout the standard stereographic triangle. Later work by Bishop and Hill*'8 showed that Taylor's least-shear hypothesis was equivalent to a maximum work principle which they advanced. Using the simplified Bishop and Hill method for {111)(110) slip, Hosford and Backofen' obtained detailed contours of constant minimum M for the same axisymmetric flow case. In contrast to {111}(110) slip in fcc metals, slip in bcc metals is generally described as occurring on {ll~)(lll), {112)(111), {123) (111) systems as well as mixed slip composed of all three. Since the direction cosines of the slip plane normal and the slip direction enter as a product in the Taylor analysis, the Taylor solutions of ,M for {110)(111) slip are identical to those for { 111} 110) slip. The other three cases of slip, however, have not been solved. In view of the numerous combinations of slip systems involved in the calculations, the Taylor analysis is clearly oriented toward computerized solutions. THE TAYLOR ANALYSIS In order to obtain the active combination of (five) slip systems by solving for the minimum value of M = we first express the (small) strain components E,, with respect to the cubic axes 1, 2, 3 ([loo], [010], [001], respectively) of the crystal, in terms of the sum of the glide shears yj from slip systems j: where n, and n,j refer to direction cosines of the slip plane normal, and dri and dsi to direction cosines of the slip direction, of slip system j, all referred to the cubic axes. In practice, the strain components are given with respect to the specimen axes X, y, 2. These components are readily converted to ers through the tensor transformation where irk and 1,~ are the direction cosines between the two sets of coordinate axes.

Jan 1, 1968

Writing the Technical Report, third edition, by J. Raleigh Nelson. McGraw-Hill Book Co. $4.50, 356 pp., 1952.-The aim of the book is to inspire a greater interest in report writing. Basis for the increased interest is a development of a keener understanding of the writer's own mental processes and the practical procedures involved in writing a report. The book is concerned with basic principles and procedures, rather than incidentals. It emphasizes the importance of correct attitudes and suggests a method of approach and organization. In the first part of the book, design and composition are considered. Next, the text gives directions for setting up both the long and short term report. The third part of, the book gives a systematic procecure for critical examination of the report. The fourth section presents a 16 week course in report writing. The Rocks of the Sekondi Series of the Gold Coast, by A T. Crow. Gold Coast Geological Survey. 7s. 6d, 73 pp., 1952.-The book describes the results of careful and detailed mapping of the Sekondi Series. The Sekondi-Takoradi area is undergoing intensive development, including extensions to Takoradi Harbor and to the railways. Details are given on the nature, extent, and structure of the Series and many faults which cut into them. The book is aimed at those with a practical interest in the area. It is illustrated with geological maps and drawings of horizontal sections. In the back, the terrain of the series is illustrated in a group of plates.

Jan 1, 1952

By Reinhardt Schuhmann JR

Metallurgical Engineering Volume I, by Reinhardt Schuhmann, Jr. Addison-Wesley Press. $7.50, 390 pp., 1952. -This first volume, engineering principles, of a two volume work, is intended by the author to meet a need for reorganization of instruction in extractive metallurgy. Its three main objectives are to organize the subject matter according to basic principles and unit processes; to integrate the underlying science of physical chemistry with metallurgical engineering; and to put greater emphasis on analysis and quantitative solution of engineering problems. Vol. I deals with unit processes, stoichiometry, thermodynamics, fuels, fluid flow, heat transfer, pyrometallurgical systems and refractories. Vol. II will take up the individual unit processes. Initiation and Growth of Explosion in Liquids and Solids, by F. P. Bowden and A. D. Yoffe. Cambridge University Press. $4.50, 104 pp., 1952.-The book is a study of decomposition by impact and by friction of explosive substances and deals mainly with the work of the authors and their collaborators. Research is still in progress but results thus far indicate that the mechanism of initiation is relatively simple. Findings are thoroughly discussed, and the latter part of the monograph describes the way in which a small nucleus of decomposition can grow into a large scale explosion.

Jan 1, 1952

By John W. Cloud

IN 1877 the Pennsylvania Railroad Company removed an old bridge from its line at Duncannon, Pa., built intermediate piers and erected shorter spans of the Pratt truss type, which had previously been in use on another portion of the road. The design of this truss would not admit of diagonals larger than 1 5/8 inches diameter, and in order to stiffen the bridge somewhat steel rods were introduced for the main diagonals in the first and second panels, 1 5/8 inches and 1 3/8 inches diameter respectively. These rods were threaded without upsetting, and by the ordinary formulae the strains were of the same intensity upon both, viz., 16,000 pounds per square inch with the maximum loading. The other main diagonals in the truss are 1 5/8 inches diameter, and of iron. It was specified for the steel rods : Elastic limit, - 45,000 lbs. Tensile strength, - 80,000 lbs. Elongation, - 20 per cent. The steel was procured without difficulty, and it allowed a factor of safety of 2 3/4 at elastic limit, while a similar factor of 2 1/2 had for a long time been successfully used for iron. In the course of three years, from time to time, six of these steel rods broke, three of them being 1 3/8 inches in diameter, and three 1 5/8 inches in. diameter. The broken rods were tested, and three of them. analyzed at Altoona to ascertain the cause of failure, and what modi¬fications should be made in the steel for such service. Examination showed that all the rods were broken in detail close under the nut. The threads were well cut and properly rounded at the root. In testing the rods micrometer screws,. reading to .0001" with electric bell to signal the contact, were attached to the test pieces, and by this means the modulus of elasticity and elastic limit accurately obtained.

Jan 1, 1881

By Roswell Johnson

THE prevailing system of wells on a rectangular basis, as shown in Fig. 1-A, has developed because of the exigencies of offsetting at boundary lines. When, however, a very large tract is, being drilled, it is often possible to abandon this inferior method for the superior arrangement C- PROPER STAGGERING FIG. 1.-THREE SYSTEMS OF SPACING WELLS. known as "staggering," which is illustrated in Fig. 1, B and C. The advantages of the triangular over the rectangular method are evident from Fig. 2, computed on the basis of one well to 10 acres (4 ha.). With the triangular system, no land is more than 409.4 ft. (124.8 m.) from a

Jan 8, 1918

By Thomas H. Clagett

ThE Pocahontas coal field comprises the area in Tazewell County, Va. and Mcrcer and McDowell counties, W. Va., in which Nos. 3 and 4, Pocahontas seams of bituminous coal are mined. It is a mountainous region with ridges rising 300 to 1000 ft. (91 to 305 111.) above the very narrow valleys and, except for some poorly kept farms along the tops of the ridges and the area occupied by the mining and coking plants and villages, is wooded throughout. First shipments were made from Pocahontas in 1883. There are now about 100 mines, 95 per cent. of which are drift mines. At the end of 1920, approximately 298,000,000 gross tons of coal had been produced and 35,000 acres of coal mined. No. 3 seam is from 4 to 10 ft. (1.2 to 3 m.) thick, but the change is gradual and the thickness fairly uniform in any particular locality. It has a streak of bone, about 2 in. (5 cm.) thick, to which the coal adheres on both sides. In parts of the field this bone is replaced by hard slate, usually from 2 to 4 in. thick. The seam has a slate or fireclay bottom and a draw-slate top. No. 4 seam is from 65 to 80 ft. (19.8 to 24 m.) above No. 3 seam, and of minable section only in the western part of the field. It is from 3 to 8 ft. thick and has two streaks of bone, cach from 1 to 2 in. thick. It has a fireclay or slate bottom and is overlaid by from 4 to 24 in. of a laminated coal and slate, locally termed "black rash," which is separated from the coal seam by about 3 in. of slate. This "black rash" averages about 2.5 per cent. ash, but contains some clean coal. The coal in both seams is quite soft. Cleavage sufficieiltly well defined to exert an influence on the mining is rare. Overlying strata arc slates, shales, and sandstones, the sandstones predominating, extending from 30 to 1000 ft. above No. 3 seam. The strata directly above the draw slate of No. 3 seam, or "black rash" of No. 4 seam, and up to the first sandstone are usually slates or shales, about 10 ft. thick over the.

Jan 1, 1923