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By Henry M. Howe

THE natural effect of large size should be to increase segrega¬tion. I have previously pointed' to the excessive segregation in many large ingots as tending to confirm this, but I have shown that in case of ingots less than 16 in. square this expected effect of ingot-size is liable to masked by that of other variables. Under these conditions we should expect that if large ingot-size really does tend to increase segregation, this effect would be shown by taking the average of large numbers of cases, so that the effects of these other variables might off-set and cancel each other.

Jan 10, 1909

THE term mountain bump describes the sudden rupture of one or more coal pillars under excessive stress. These bursts occur with varying degrees of violence and sometimes include adjacent strata, especially the bottom rock. Many failures do not develop enough violence to be dangerous and are regarded as an aid to coal production, but severe occurrences are accompanied by tons of flying coal, dense clouds of dust, and excessive gas emission. Such bursts sometimes throw heavy machinery several feet. Major factors to be considered in the problem are the nature of the strata above and below the seam and the depth of cover. Bumps are classified as to their nature, extent of damage, and point of occurrence, e. g., face bump, coal bump, high side bump, low side pavement bump, and district bump.

Jan 8, 1958

By Charles Himrod

In presenting this paper it is not intended to enter into any discussion of the theory of the blast-furnace, but simply to give the results of a number of determinations of CO and CO 2 in furnace gases, and some conclusions arrived at, and the result of an experiment made in hopes of increasing the production of CO 2. In the first table, on page 198, is given the averages of a number of analyses of gases of different furnaces, and in the second, of two stacks of different sizes under varying circumstances. The conclusions arrived at as to what influences the production of CO2 are as follows: lst,. Kind of fuel. Bituminous coal not permitting the formation of as much CO, as coke. 2d. Kind of ores. Rolling-mill cinder being much less favorable to formation of CO2 than hematite ores, magnetites probably less than hematites, but more than cinder. 3d. Length of time of contact of gases with ore. Small furnaces and too rapid driving both waste fuel by riot allowing enough time for conversion of CO into CO2. 4th. The temperature of blast. The hotter the greater the quantity of CO2. 5th. Regularity of passage of stock through the furnace. The hanging and dropping of the stock, however slight, seems to pack it more solidly in the hearth, increases the resistance to the blast, and decreases the quantity of CO2. These are the most common causes noticed which influence the production of CO2, unless we except the one that might be considered the greatest of all, the one that has spoiled so many tons of iron, and the amiability of so many furnacemen, the one most dreaded, the great unknown. It would seem a self-evident proposition that the better the contact of the gases with the ore and the less with the fuel, the greater would be the amount of CO2 produced. To prolong the contact of gas with the ore furnaces are enlarged with advantage, and pains are taken to charge the stock in such a manner as will best promote it. Still, with furnaces of most approved construction and most skilful manipulation, the gases leave the furnace so rich in CO, that not half the heating power of the fuel is obtained, and the highest

By P. T. Chiang

Chemical etching methods for the simultaneous revealing of the tellurium or selenium Phase and the chalcogenide grain boundaries of the alloy systems are given. A tellurium eutectic was found Present in zone-melted ingots. Similarly, a selenium monotectic was present in ingots. In general, the second phase (tellurium or seleniumn) occubies three different sites; viz., along the chalcogenide grain boundaries, as inclusions within the chalcogenide grain, and on the undersurface of the ingot. The detection limit for the tellurium phase is about 1 u in width. THERMOELECTRIC materials based on Group V (bismuth, antimony) and Group VI (selenium, tellurium) elements have aroused considerable interest in recent years in the practical application of thermoelectric cooling. In many cases, a small amount of excess tellurium (or selenium) was added to the material to optimize its thermoelectric properties. Then the question immediately arises as to the number of phases present in the resultant alloy. In the binary systems of Bi-Te, Sb-Te, and Bi-Se, the congruent melting compositions have been reported to be non-stoichiometric and are represented by Bi~Te respectively. It is to beexpected and known that Bi2Te3 and SbzTe3 crystallize from the melt with an excess of bismuth and antimony in the lattice and that tellurium forms a eutectic.~' The same could be assumed to take place in the pseudo binary systems of (Bi,Sb)zTe3 and Bi2(Se,Te)3 as well as in the system studiedby puotinen5 and other workers. Likewise, BiaSe3 crystallizes from the melt with an excess of bismuth in the lattice and selenium forms a monotectic.~ Therefore, in practice, alloys solidified from the melt often contain a second phase (tellurium or selenium) in one region or another of the solid mass even without the addition of excess tellurium (or selenium). ~u~~recht' studied the thermoelectric properties of (Bi,Sb)2Te3 alloys with excess tellurium and simultaneous additions of selenium. He mentioned that the materials show two phases because of the considerable excess of tellurium or selenium. However, he did not report as to how the tellurium or selenium phase was identified. It is generally believed that the presence of an excessive amount of tellurium or selenium phase in the alloy would adversely affect its thermoelectric properties and its uniformity. Consequently, there is a need for a simple method for the identification of the tellurium and selenium phase. The quantity of the second phase present is usually too small to be detected either by chemical analysis or by normal X-ray techniques. This investigation was therefore carried out, first, to devise a simple metallographic method for the identification of the tellurium or selenium phase coexisting with the chalcogenides and, second, to determine the distribution and specific location of the tellurium or selenium phase in the ingots. EXPERIMENTAL PROCEDURE The starting materials used for the alloy preparations were 99.999 pct pure bismuth, antimony, and tellurium and 99.997 pct pure selenium. The bismuth and antimony were obtained from Consolidated Mining and Smelting Co. of Canada Ltd., while the selenium and tellurium were obtained from Canadian Copper Refiners Ltd. The tellurium was purified further in the laboratory by zone refining. The elements were pulverized in a stainless-steel pestle and mortar. The amounts for the desired composition were weighed out each time on an analytical balance to make up a 100-g sample. Then the sample was introduced into a Vycor ampule (19 by 150 mm), pumped down to a vacuum of 10"5 Torr for 15 min, and sealed off. The ampule was then heated in a horizontal resistance furnace at 800" to 900°C for about 20 hr. During this period the assembly was rocked back and forth several times to ensure good mixing. At the end of the heating period, the ampule was quenched in cold water and then transferred to the zone-melting apparatus described in a previous publications to grow large-size aligned polycrystals. The background and ring-heater temperatures were adjusted to make the freezing solid-liquid interface slightly convex to the liquid. The recorded temperature gradient in the vicinity of the freezing solid-liquid interface was around 15°C per cm. The ampule was moved horizontally at a speed varying from 0.4 to 2 cm per hr so that the ring heater would cover the whole ingot length from end to end. A single zone-melting pass was used for the Bi-Te, Sb-Te, and Bi-Sb-Te ingots. Two passes in the forward and reverse directions were carried out for the Bi-Se and Bi-Se-Te ingots. Six passes in the forward and reverse directions were performed for the Bi-Sb-Se-Te ingot. The zone-melted ingots were found to contain several large crystals, with their basal planes (0001) approximately parallel to the growth axis. Samples of bismuth and antimony tellurides coated with a layer of tellurium, and bismuth selenide coated with a layer of selenium, were prepared for comparison in phase identification. These coatings were made by dropping a piece of the zone-melted ingot into some molten tellurium or selenium under argon atmosphere and allowing them to cool slowly to room temperature. The metallographic specimens were prepared by

Jan 1, 1969

By R. Taggart, R. H. Ericksen, D. H. Polonis

Transmission electron microscopy techniques hare been used to study the spontaneous marfensite phase that forms during the thinning of Ti-Cr alloys. The structure of this phase has been found to differ. from the hcp martensite and has been identified as a clisforted fcc lattice. The spordaneous marlensile in this system is interpreted as a metastable isomorph of the equilibriunz TiCr, phase. WHEN thin-foil specimens for transmission electron microscopy were prepared from metastable alloys of the Ti-Cr system, a spontaneous transformation occurred' when the foils contained the untrans-formed 0 phase or two-phase mixtures of the 0 and w phases. The purpose of this paper is to examine the relationship that exists between the crystal structure of the spontaneous product and that of the matrix. The differences between the martensite transformation that occurs in the bulk material and the spontaneous reaction that occurs during the preparation of thin foils are compared with the observations that have been reported for similar phenomena in a commercial titanium alloy.' A spontaneous reaction that exhibits characteristics similar to a martensite transformation has been reported to occur in thin foils prepared from the retained metastable structures of several alloy systems.1'3"7 ~ull~ observed such a spontaneous reaction in 0 brass and attributed the apparent increase in the martensite transformation temperature to a decrease in the non-chemical free energy associated with bulk strain energy. He also showed that the spontaneous product did not have a specific habit plane, but that its orientation relationships to the parent matrix were dependen on the thickness of the transforming region. It has also been pointed out by Breedis6 that in thin films the absence of the constraints imposed by a bulk matrix can cause different requirements for the martensite plate interface and lattice distortion which is reflected bv a dependence of the transformation mechanism on the specimen geometry. In the case of the spontaneous reaction reported for Au-Zn alloys7 a definite habit plane was determined and shown to correspond with the habit plane calculated on the basis of the Bowles and Mackenzie crystallographic theory of the martensite transformation.'- lo EXPERIMENTAL PROCEDURE A series of titanium alloys containing 5.5, 5.9, 6.4: 7.6, 8.0, 11.3, and 18.7 at. pct Cr were prepared from high-purity (iochrome) chromium and iodide-grade titanium by levitation melting. The experimental procedure used for sectioning the alloys and for thin-foil preparation has been reported in an earlier paper.' X-ray diffraction patterns were obtained using a 114-mm Debye-Scherrer camera and Cu-Ka radiation. In order to minimize fluorescent radiation from the specimen, a strip of aluminum foil 0.002 in. thick was placed in contact with the X-ray film. After a specimen was removed from the camera: an additional X-ray experiment was performed, to insure that no spurious lines were obtained due to the presence of the aluminum foil. The interstitial impurity analysis for the alloys used in this study was as follows: oxygen, 100 ppm: hydrogen, 30 ppm: nitrogen, 28 ppm. EXPERIMENTAL RESULTS Electron diffraction patterns were obtained from several individual crystals of the spontaneous marten-

Jan 1, 1970

By R. D. Carnahan, G. A. Stone, R. J. Arsenault

An experimental technique has been developed for carrying out a dynamic tensile stress-strain test in which plastic strain is measured continuously throughout the microstrain region extending through the macroflow region to total deformations of 5 pet. The tests were carried out on niobium, samples having interstitial impurity levels of 160 and -800 ppm at temperatures ranging from room temperature down to 100°K. A band spectrum of activation energies was obtained from calculations based on the measured activation volumes and temperature dependence of flow stress. The inability of a single rate-controlling process to predict such a phenomenon has led to the proposal that several sequential rate-controlling dislocation mechanisms are operative in the preyield micro-strain region. These are thought to be: the motion of geometrical kinks, the formation of double kinks in edges, and finally in the macrostrain region the formation of double kinks in screws. In less pure niobium the effect of interstitial impurities is shown to be dominant in the microstrain region, suggesting that a fourth probable mechanism is overcoming interstitial barriers instead of geometrical kink motion and the formation of double kinks in edge dislocations. THE principal fundamental aim of most mechanical properties studies of crystalline solids is to determine the dislocation mechanisms responsible for the plastic behavior. The extension of such studies to the region of preyield microstrain behavior has received renewed attention in the past few years as the details of macroscopic flow behavior have become better understood. For the most part, microstrain studies have been carried out using one of two variations of a single experimental technique.1 The first method involves loading the sample at a constant extension rate to a predetermined stress level (less than the macroscopic yield stress), instantaneously unloading, and then determining the extent of plastic deformation to a sensitivity of 10"6. The microscopic stress-strain curve is then constructed from the results of a repeated series of such individual measurements, each of which involves loading to an incrementally higher stress level, by relating the accumulated plastic microstrain for each step to the maximum applied stress in that step. The second variation, also carried out by step-wise increases in stress, measures the total strain to a sensitivity of ~10"6 and relates the maximum stress to the area of closed hysteresis loops that are generated under certain conditions (namely, prestrained samples). The foregoing methods have yielded interesting information about the nature of preyield deformation and plastic response to stresses below the yield stress, but they offer certain disadvantages for studying the dynamic behavior of dislocations. In the first method it is physically impossible to specify a plastic strain rate inasmuch as the test sample is reexposed, as it is loaded to its maximum stress in a particular step, to lower stresses at which flow will take place. The strain corresponding to a given stress level on the stress-microstrain curve thus generated will then always be greater than that at the corresponding stress level of a truly dynamic test carried out at the same extension rate. The second method has been used to obtain correlations with dynamic macroscopic flow parameters by applying dislocation damping theory to the hysteresis loop areas.2 The approach has had some success but suffers in that only samples that have been prestrained a few percent can be studied. Although the stresses

Jan 1, 1968

By Eugene McAuliffe

It is not possible to include in this paper, limited as it is in scope, the many diverse steps toward the reduction of mine accidents that are taken in the mines that produce the nation's coal. Every coal-producing state has enacted laws covering proper mining practices, and the major portion of these are directly related to the safety of the mine employees. The United States Bureau of Mines, the American Institute of Mining and Metallurgical Engineers, The American Mining Congress, a number of national, regional and state organizations, as well as the coal technical press, have covered time and time again all of the '(do" and "don't" phases of mine operation that bear on the important question of mine and employee safety. Within the past 15 years The Union Pacific Coal Co, has attempted to put into practice in its mines in southern Wyoming these many good recommendations, finding some value in all, and yet, to secure substantial results, the management found it necessary to resort in the end to what might be referred to as i'extra-territorial" methods. It is the writer's purpose to show in this paper that marked and even extraordinary betterment, can be brought about when employer and employee work together with due sincerity. In presenting our own experience, one that has been duplicated in so far as results are concerned on numerous other properties, no theory of perfection of management exists; on the other hand, our organization feels that as long as our record of accidents remains as shown by even our latest and best performance we still have far to go. Safety work in some form has been carried on in and about the mining properties of The Union Pacific Coal Co. since the first mine was opened at the now long-abandoned town of Carbon, Wyo., in 1868. On June 30, 1903, an explosion and subsequent mine fire occurred in mine No. 1 at Hanna, taking 169 lives, and a second explosion occurred in the same mine on March 28, 1908, in which 59 additional lives were lost. Looking back with impartiality on the causes leading up to these two unfortunate disasters, we can only conclude that shooting from the solid, the absence of adequate ventilation, rock dusting, the use of water at the face to allay

Jan 1, 1938

By Eugene McAuliffe

It is not possible to include in this paper, limited as it is in scope, the many diverse steps toward the reduction of mine accidents that are taken in the mines that produce the nation's coal. Every coal-producing state has enacted laws covering proper mining practices, and the major portion of these are directly related to the safety of the mine employees. The United States Bureau of Mines, the American Institute of Mining and Metallurgical Engineers, The American Mining Congress, a number of national, regional and state organizations, as well as the coal technical press, have covered time and time again all of the '(do" and "don't" phases of mine operation that bear on the important question of mine and employee safety. Within the past 15 years The Union Pacific Coal Co, has attempted to put into practice in its mines in southern Wyoming these many good recommendations, finding some value in all, and yet, to secure substantial results, the management found it necessary to resort in the end to what might be referred to as i'extra-territorial" methods. It is the writer's purpose to show in this paper that marked and even extraordinary betterment, can be brought about when employer and employee work together with due sincerity. In presenting our own experience, one that has been duplicated in so far as results are concerned on numerous other properties, no theory of perfection of management exists; on the other hand, our organization feels that as long as our record of accidents remains as shown by even our latest and best performance we still have far to go. Safety work in some form has been carried on in and about the mining properties of The Union Pacific Coal Co. since the first mine was opened at the now long-abandoned town of Carbon, Wyo., in 1868. On June 30, 1903, an explosion and subsequent mine fire occurred in mine No. 1 at Hanna, taking 169 lives, and a second explosion occurred in the same mine on March 28, 1908, in which 59 additional lives were lost. Looking back with impartiality on the causes leading up to these two unfortunate disasters, we can only conclude that shooting from the solid, the absence of adequate ventilation, rock dusting, the use of water at the face to allay

Jan 1, 1938

By A. Steiner, E. Miller, K. L. Komarek

Equations have been derived to calculate the chemical potentials of the components of liquid binary alloys from liquidus and enthalpy data. The equations are applicable to systems with intermetal-lic compounds of limited solid solubility. The liquidus curve of the Mg-Sn system was accurately redetermined, and the melting point of the compound Mg2Sn was found to be 770.5° * 0.3°C. The thermo-dynamic properties of the liquid alloys were calcu -lated from the liquidus data. The activity of tin shows both positive and negative deviations from Raoult&apos;s law and the relative integral entropy is positive. THE phase boundaries in an equilibrium phase diagram are functions of the thermodynamic properties of the coexisting phases. Specifically, the shape of the liquidus curve near an intermediate compound is determined by the properties of the compound and the liquid phase. Hauffe and wagnerl have derived an equation for the chemical potential differences (ui) of the liquid alloys near the congruent melting point when the heat of fusion of the compound and the liquidus curve are known. In their derivation the temperature dependence of the ui value was neglected, and liquid of stoichio-metric composition was chosen as the reference state. To obtain chemical potentials over the ntire composition range of the phase diagram with the pure components as the reference state, equations have been derived which incorporate the temperature dependence of the chemical potentials. Such a thermodynamic analysis can be carried out when the liquidus curve and the enthalpy values are known. The equations have been applied to the redetermined liquidus curve of the Mg-Sn system to obtain the thermodynamic properties of liquid Mg-Sn alloys. The Mg-Sn phase diagram has been studied by various investigators and the results have been compiled and critically assessed by Hansen.2 Preliminary thermal analyses showed that the basic features of the diagram were correct. The system has one congruent melting compound, Mg2Sn, two eutectics, and some solid solubility of tin in magnesium. However, the published liquidus temperatures show considerable scatter. In order to perform an accurate thermodynamic analysis, the liquidus curve between the magnesium-rich and tin-rich eutectic compositions was therefore redetermined by careful thermal analysis using highest-purity starting materials. EXPERIMENTAL PROCEDURE The magnesium metal (Dominion Magnesium Ltd, Toronto, Canada) had a purity of 99.99+ pct with the following impurities (in ppm): 20 Al, 30 Zn, 10 Si, <1 Ni, <1 Cu, <10 Fe; tin (Cominco Products, Spokane, Wash.) contained 99.999+ pct Sn. The graphite crucibles were machined from graphite rods (United Carbon Products Corp., Bay City, Mich.) which had an average total ash content of less than 30 ppm. All the graphite parts were baked out in vacuum at 950" to 1000°C for a minimum of 24 hr to remove volatile organic materials. The graphite crucibles (3 in. long, 1-5/8 in. OD, 1-3/8 in. ID) were tightly closed with a threaded cover (1/2 in. thick) which had a central thermocouple well (2-1/4 in. long, 5/16 in. OD, 3/16 in. ID). Cover and thermocouple well were machined from one piece of graphite. A thin sheath of quartz was inserted in the well to protect the thermocouple

Jan 1, 1964

By J. S. Kasper, R. M. Waterstrat

IN view of the recent findings of a pronounced ordering of atoms in s phase alloys containing elements of the first long row of the periodic table (and including molybdenum),l it is of interest to resolve the question of ordering for s phases containing second and third-row elements. Examples of the latter have been provided recently by Greenfield and Beck2 and two of them, Re-Cr and Ru-Cr, would appear to be favorable for a study of ordering by X-ray diffraction methods because of the considerable differences in the scattering factors concerned. In addition, s phase is found to occur in the Os-Cr system, where the difference in scattering factors is even larger. Accordingly, X-ray powder intensities have been measured in an attempt to learn the nature of the ordering, if any, in these three v alloys. Since there is no reported work on intermediate phases in the Os-Cr system, an exploratory investigation was made in this system, and it was found that, in addition to the s phase, the phase with the A-15 or ß-W structure also occurs. Specimen Preparation—The alloys were prepared by compressing mixed powders of —200 mesh size and sintering in an atmosphere of pure dry hydrogen. All alloys were rapidly cooled from the annealing temperature to room temperature in a stream of cold dry hydrogen in a water-cooled chamber. Table I lists the sources and purities of the starting materials, as well as the details of processing for each of the alloys investigated. Intermediate Phases in the Os-Cr System—In the absence of information on intermediate phases in the Os-Cr system, it was suspected that this system would resemble that of Ru-Cr, where a s phase, RuCr2,2 and a phase with the A-15 structure, RuCr3,3,4 have been identified. Both these phases were found in the Os-Cr system and at compositions

Jan 1, 1958

By G. W. Preckshot, J. W. Gorman

MOLTEN metals offer an excellent medium for the study of molecular diffusion and interphase transfer. In the absence of intermetallic compound formation, solutions of molten metals are solutions of elements. Therefore, complicating factors such as molecular structure, dissociation, association, polarization, and so on, are generally absent. Further, metals remain in the liquid state over a wide range of temperature. Thus, the effect of temperature on transport processes can be studied in more detail. Although some data are available for the diffusion of metals in the molten state at high temperatures,"""".&apos;!&apos; the most useful and accurate data are those for the diffusion of various elements in mercury at room temperature. The effective radius of diffusion for the various elements in mercury may be calculated from the Stokes-Einstein relation.&apos;-These calculated radii are compared with the atomic and ionic radii calculated from X-ray data on crystals." The effective radii of diffusion of the alkali and alkali-earth metals correspond to those of the neutral atom; those of cadmium, silver, lead, zinc, thallium, bismuth, and tin correspond to ionic radii; and those of copper and gold indicate larger radii due to association with mercury or more likely, faulty diffusion data. Independent evidence"&apos; supports the notion that alkali metals are uncharged in amalgams. The concept of metals moving free of their conductance electrons in the liquid state has been discussed by Eyring, et al,&apos;" in connection with studies on the viscosity of pure molten metals. Considering the approximate nature of the tabulated atomic and ionic radii and the variance in the diffusion measurements, the application of the Stokes-Einstein equation to the diffusion of metals in mercury gives gratifying results. It is noted that a number of these metals have article radii eaual to or less than those of the solvent mercury.".&apos;*,"&apos; Soba1,&apos;" sing the inaccurate Roberts-Austin20 data, indicated that the effective radius of diffusion might well be a function of temperature. Additionally in studies of mass transfer between phases, many conflicting opinions have been expressed concerning the assumption of equilibrium at the interface." ,","," The results of the present work on the diffusion of solid copper in molten lead throws light on the tempera- ture variation of the diffusion radius as well as the extent of the interfacial resistance. The theoretical background and experimental procedure are presented here in detail. Results on other systems will be presented in subsequent papers. Nomenclature The following nomenclature is used in the paper: A—cross-sectional area of diffusion column, sq cm C, C,—concentration of solution and saturated solution respectively, g per cc D,D&apos;—-diffusivity, sq cm per sec e—Naperian base h—ratio, k/D k—mass-transfer coefficient, cm per sec L—diffusion column length, cm n—series index q—flux, g per sq cm-sec r—radius, cm or A R—-gas constant t—time, sec T—temperature, K V—volume, cc w—weight of copper-lead alloy on copper cylinder WT—-total copper transferred to lead diffusion, column, g Z—distance from top of diffusion column, cm 2&apos;—distance from copper-lead interface, cm (2&apos; = L-2) u,,—roots of diffusion equation Mathematical Apparatus The model shown in Fig. 1 applies to the diffusion of solid copper into molten lead. Here Fick&apos;s first law may be written where all terms are defined in the nomenclature. It is assumed that the volume of the lead column is constant. This is justified since experimental densities compared favorably with calculated densities based on perfect interstitial mixing. Thus there is no counter diffusion of lead. It is clear that 2 in Equation [I] should be measured relative to the interface which moves relative to the diffusion cell but not to the liquid phase. Hence, the frame of reference is the plane of the copper-lead interface. The diffusivity calculated at constant volume, D", is that defined by Hartly and Crank" and is designated herein as D. No Interfacial Resistance—The two situations of the presence and absence of interfacial resistance will be treated. The simplest is the latter which re-

Jan 1, 1959

By Henry Mulryan

Diatoms are microscopic aquatic plants of the order Bacillariaceae. They are unicellular plants with skelctons made up of amorphous opaline silica. The skeletons show highly ornate, complicated geometrical designs. Diatoms live in water virtually everywhere. They are found in clean sea water, brackish water, and fresh-water lakes and ponds. When conditions are right, diatoms propagate by subdivision in huge numbers. Alkalinity, temperature, and the presence of high concentrations of silica in the water largely control diatom life. When the diatoms die the skeletons drop to the bottom of their habitat to form oozes of varying thicknesses. Diatomites Diatomite, or diatomaceous earth, is composed essentially of the siliceous remains of the diatoms, although other organic skeletons are also present, especially in sea-water deposits where radiolaria, sponges and silico-flagellates are common. Impurities are generally carbonaceous material, fine-grained silt, volcanic ash and dust, and occasional coarse grains of sand. Diatomites are marine, brackish, or fresh-water, depending upon types of diatoms and their method of deposition. Diatoms More than 8000 species of diatoms have been named and classified. Some are definitely classified as to their habitat; some are so well recognized as to their living conditions that they can be stated to be diagnostic types, and when encountered in a deposit determine the origin of the deposit. Some of the commoner types of diatoms found in the freshwater diatomites on the Pacific Coast are: Cymbella lanceolata Agardh Fragilaria virescens Ralfs Encyonema prostratum Ralfs Diatoma vulgare Dory Surirella biseriata Brebison Eunotia major Ehrenberg Amphipleura pellucida Kützing Stictodiscus niagarac Ehrenberg Gomphonema geminatum Lynberg Melosira granulata Ehrenberg Epithemia turgida Kützing

Jan 1, 1942

By Henry Mulryan

Diatoms are microscopic aquatic plants of the order Bacillariaceae. They are unicellular plants with skelctons made up of amorphous opaline silica. The skeletons show highly ornate, complicated geometrical designs. Diatoms live in water virtually everywhere. They are found in clean sea water, brackish water, and fresh-water lakes and ponds. When conditions are right, diatoms propagate by subdivision in huge numbers. Alkalinity, temperature, and the presence of high concentrations of silica in the water largely control diatom life. When the diatoms die the skeletons drop to the bottom of their habitat to form oozes of varying thicknesses. Diatomites Diatomite, or diatomaceous earth, is composed essentially of the siliceous remains of the diatoms, although other organic skeletons are also present, especially in sea-water deposits where radiolaria, sponges and silico-flagellates are common. Impurities are generally carbonaceous material, fine-grained silt, volcanic ash and dust, and occasional coarse grains of sand. Diatomites are marine, brackish, or fresh-water, depending upon types of diatoms and their method of deposition. Diatoms More than 8000 species of diatoms have been named and classified. Some are definitely classified as to their habitat; some are so well recognized as to their living conditions that they can be stated to be diagnostic types, and when encountered in a deposit determine the origin of the deposit. Some of the commoner types of diatoms found in the freshwater diatomites on the Pacific Coast are: Cymbella lanceolata Agardh Fragilaria virescens Ralfs Encyonema prostratum Ralfs Diatoma vulgare Dory Surirella biseriata Brebison Eunotia major Ehrenberg Amphipleura pellucida Kützing Stictodiscus niagarac Ehrenberg Gomphonema geminatum Lynberg Melosira granulata Ehrenberg Epithemia turgida Kützing

Jan 1, 1942

By A. L. Benham, W. E. Dowden, W. J. Kunzman

The mechanism involved in creating a miscible fluid displacement of typical reservoir fluids through porous media by light hydrocarbon mixtures usually involves a number of mixing and separation stages in the contact area. This mechanism has been illustrated on ternary diagrams for miscible displacement of reservoir fluid by rich hydrocarbon gases. A relatively simple method has been devised for calculating the approximate conditions for a miscible displacement of reservoir fluid by rich, light hydrocarbon gases or by LPG mixtures. Miscibility is favored by increased pressures, decreased temperatures, light reservoir fluids and light hydrocarbon-displacing fluids rich in the heavier components. The conditions for miscible displacements of five typical reservoir fluids by various light hydrocarbon mixtures were determined for a range of temperatures from 70" to 260°F and pressures from 1,000 to 3,000 psia. A correlation of these conditions was obtained using the variables of temperature, pressure, C,+ molecular weight of the reservoir fluid, C,+ molecular weight of the displacing fluid, and mol per cent methane in the displacing fluid. This correlation has been applied to data appearing in the literature with very good success. A partial check of the correlation has been made using a step-wise procedure with a windowed PVT cell. INTRODUCTION The term, "miscible fluid displacement", may be defined as any oil-recovery displacement process where there is an absence of a phase boundary or interface between the displaced and displacing fluids. A water flood would not be a miscible fluid displacement, although cycling in a condensate reservoir would be. Another example is displacement of oil by gasoline. Not so obvious, however, are the conditions under which fluids (such as propane, mixtures of propane and methane, or other similar systems) will give a miscible fluid displacement of oil. There are four standard miscible-fluid-displacement processes being used for the recovery of oil from an "nderground reservoir—(1) high-pressure dry-gas miscible displacement, (2) rich-gas miscible displacement, (3) miscible slug using a slug of LPG followed by a lean dry gas under miscible conditions, and (4) gas driven-slug process using a slug of LPG followed by a lean dry gas under immiscible conditions. The first problem faced by the engineer designing a miscible displacement process is to determine the conditions for miscibility. A number of papers have included discussions of the process of obtaining miscibility in these processes.1-8 However, methods for calculating the conditions for miscibility have not been published. This paper includes a method for calculating the conditions for a miscible displacement of reservoir fluid by a rich gas (LPG diluted with methane or natural gas). In this paper, a rich-gas miscible displacement process is defined as an oil-recovery process in the reservoir. The cost of a rich-gas miscible displacement will be decreased by diluting the LPG with methane or natural gas as much as possible. Therefore, it is important to be able to predict the maximum dilution for miscibility. MECHANISMS The mechanisms for obtaining miscibility between a displacing mixture of light hydrocarbons and displaced reservoir fluid often involve a number of displacing and mixing stages. As stated previously, the cost of a rich-gas miscible displacement is decreased by diluting available LPG with natural gas. The problem is to predict the maximum dilution allowed while maintaining miscibility. To get a picture of the displacing and mixing stages, it is helpful to consider these complex hydrocarbon mixtures as pseu do-ternary systems. Graphical representation of a complex system as a pseu do-ternary system can be thermodynamically rigorous if enough variables are used to describe the character of each pseudo-component in one of the phases. However, even if the characterization of each pseudo-component is not complete, pseudo-ternary representation does serve to illustrate the mechanism for obtaining miscibility and can be used to make some general conclusions concerning the conditions for obtaining miscibility. A phase diagram for the ternary system, methane-

The Hurghada field is still the major producing field in Egypt. There was almost no activity in the Abu Durba field during 1936 and no new evidence is available. The following table summarizes the information on the Hurghada field for the year 1936. Hurghada Field Age of field to end of 1936, years.................... 23 Producing area for gas and oil, acres................. 1,050 Barbels Total oil production to end of 1936.................. 29,046,572 Total oil production during 1935.................... 1,212,182 Total oil production during 1936.................... 1,218,708 Daily average during November, 1936............... 3,249 MillionB CU. Ft. Total gas production (Aug. 1925 to end of 1936)...... 3,966 Total gas production during 1935................... 278 Total gas production during 1936................... 280 Maximum daily in 1936............................ 0.9 Number of producing wells completed to end of 1936... 94 Number of producing wells completed during 1936. ... 3 Number of wells abandoned during 1936............. 3 Producing wells at end of 1936...................... 768 Average depth of bottom of producing wells, ft....... 1,720 Average depth of top of producing horizon, ft......... 1,598 Character of oil, approx. average during 1936: Gravity at 60&apos; F., 0.900; base mixed. Character of gas, approx. average during 1936: gallons gasoline per 1,000 CU. ft., 6.2. Producing rock (main): Nubian sands, Cretaceous; character, sand rock and sandy shales. 1 The figures given by the author were in tons. A conversion factor of 6.98. based on 0.900 sp. gr., was used to obtain the number of barrels.—Ed. 2 All pumping.

Jan 1, 1937

By Robin P. Gardner

Prior work by the author has established that closedform analytic solutions can be obtained for certain steady-state and transient types of operation of open circuit, continuous ball mills. This is possible when the tanks-in-series concept is used with the segregated flow or lumped parameter milling models. Such models should be useful (whenever they apply) in any calculational application since they are efficient and simple to program for digital computation. For example, they might be used within a computer program such as that developed by Herbst et al. for the calculation of model

Jan 1, 1975

I HAVE previously shown you in the Fifth Book the process of making guns and gun carriages, together with other preparations and methods of moving them. If I now failed to show you more about them, it would be as if I had pointed out only the useless shadow of a thing, for I did not show the kinds and arrangement of their supplies or how the effects for which they are made are achieved. For these reasons I now wish to tell you, in addition to what I have already said, how saltpeter is made and the methods of refining it well; what it is and how without it guns and many effects of violent and artificial fires would have been discovered in vain. After this, I also wish to tell you the methods of compounding the powders for large and small guns, and finally how these are loaded and discharged. I also wish to tell you how mines are made, and fire tubes, [149v] fire pots, squibs, fireballs, rockets, shells, grapeshot, and other similar devices for shooting fire in order to bum ships, supplies, bridges, and ramparts, or, in offense, for firing on batteries. I also wish to teach you to make certain bronze balls for shooting, which carry fire and break in many pieces when they hit. For surely, besides being terrifying to the sight, they would be harmful to armies lined up in battle when they are fighting. Likewise, I wish, to enlighten you as to how artificial fires are made that last long and are difficult to extinguish. Since these are fine and useful things in wars, every captain and soldier should give them consideration and know how to use them when necessary. You will be pleased to have this information if for no other reason than that you can teach it to those who take delight in celebrating holidays with festivities and with fires.

Jan 1, 1942

By John Skelton, E. J. Harvey

Seepage runs (stream flow measurements in a short time at many points in a basin,) and stream flow records are used to locate losing areas in stream basins in the Missouri Ozarks. The terrane consists of dolomitic limestone and sandstone of Ordovician and Cambrian age. Side-looking radar imagery emphasizes variations in topography and reveals two types of drainage basin topography, rough and smooth (deeply dissected and slightly dissected basins). In the deeply dissected basins (rough ones), main streams and tributaries generally gain. In the slightly dissected basins (smooth ones), the streams lose a part or all of their flow. Logan Creek, a tributary of Black River in the southeastern Ozarks, loses much of its storm runoff and all of its dry weather flow. East and West Forks of the Black River, north of Logan Creek, gain water through most of their main stems. On radar imagery Logan Creek basin has a light uniform tone and smooth texture in contrast to the darker tone and rough texture of the East and West Forks. The contrast is due to the difference in degree of dissection. Therefore, radar imagery may be useful in suggesting gaining or losing streams (or reaches of streams).

Jan 1, 1973

By Max Stern

ROOM and pillar coal mining methods employed in the United States keep the roof at original height by leaving untouched pillars of coal in the face area. But, German coal mines of the Ruhr district are exclusively operated on the longwall system. With this method the whole length of the coal face advances and the roof in the face area sinks 10 to 15 pct of seam thickness. Behind the face the roof may drop 50 to 80 pct of seam thickness due to the high rock pressures encountered at average mining depth of 2250 ft. Mining depth is increasing 20 to 30 ft per year.

Jan 5, 1953

By H. M. St. John, T. Rynalski, G. K. Eggleston

Maintaining a satisfactory structure in brass and bronze castings has always been a foundry problem of great practical importance. While metallurgists and scientific investigators have not entirely ignored this matter, it has received less of their attention than has been given to iron, steel and the wrought copper and aluminum alloys. Investigation in this field has probably been discouraged to some extent by the complicated nature of the alloys involved. Hundreds of alloys are in more or less common use, most of them containing copper, zinc, lead and tin in widely varying proportions. They also contain appreciable percentages of iron and antimony as impurities, and often phosphorus, which has been added as a deoxidizer and fluidifier. Small amounts of sulfur are usually present. It is not uncommon to find nickel, sometimes in rather substantial quantities. Traces of other metals are frequently present. So complicated and variable a mixture obviously offers difficulties in any investigation of the various factors that influence the structure and other properties of the casting. Incipient Shrinkage Bolton and Weigandl have called attention to a type of structure characterized by intercrystalline fissures and large dendritic crystals which are frequently tarnished to an orange or reddish brown color. This intercrystalline porosity they term "incipient shrinkage" and attribute to the presence of carbon monoxide in the atmosphere under which the metal was melted. The defective structure to which Bolton and Weigand refer has become a brass-foundry problem of major importance, because it occurs with distressing frequency in leaded brasses and bronzes when these are melted in a neutral or reducing atmosphere. Since the electric furnaces, now coming into general use in brass foundries, normally operate with such an atmosphere and, in fact, depend upon it in part

Jan 1, 1930