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By AIME AIME

THE sixteenth annual meeting of the Woman's Aux¬iliary, A. I. M. E., was held Tuesday morning, Feb. 16, at the Engineering Societies Building. The meeting was well attended, there being 99 registered from the metropolitan area and 78 from the sections throughout the United States. Mrs. Sharpless, the secretary, read the minutes of the annual meeting held a year ago, after which Mrs. Bassett, the president, gave her address of welcome. Mrs. Bassett said in part: "I would like, at this time, to welcome you all to this, our sixteenth annual meeting, and to express my appreciation to all the national officers and members of the board of directors for their loyal support and for the excellent work done by the chairmen of sections and their members. It is with much pleasure that I look back upon my visits with the sections in Washington, Arizona, Northern and Southern California, Chicago, Colorado, Western Pennsylvania and Utah before I assumed the office of president. During the last year I have much enjoyed meeting with the sections in Boston, Washington and New York. It is our duty to see that the achievement for 1932 be equal to that of the year that has just passed."

Jan 1, 1932

By Frank G. Snyder

INTRODUCTION Numerous deposits of lead and zinc sulfides, often accompanied by barite and fluorite, occur in carbonate host rocks throughout central and eastern United States. So similar are the deposits in broad general characteristics that they long have been classified as Mississippi Valley type. They differ widely, however, in details such as metal ratios, age of host rock, type of ore-bearing structure, and probable time of mineralization. The theories developed to explain the source and transport of the metals are many and are known to all. The deposits have been termed telethermal on the basis of their presumably shallow occurrence and the attempt to relate the metals to the classic hydro- thermal sequence. 1t is now recognized that deposits of this type can occur at any depth; the only depth limitation is thickness of the sedimentary section. Ideas on the source of the metals also have changed, A rapidly growing body of evidence suggests that the metals were brought by concentrated brines from nearby sedimentary basins. The hypothesis preferred today by many geologists postulates that the metals were deposited during the course of normal sedimentation in depositional basins of miogeosynclinal or orthogeosynclinal type. At some time after deposition of the sediments, the metals were carried out of the basins by migrating brines; the brines moved laterally and upward into structurally high areas; they entered any reservoir-like structure, either primary or secondary in origin, that happened to be available; in this reservoir, possibly in a sulfur-rich environment, the metals were precipitated as ore minerals.

Jan 1, 1970

By J. H. Jackson, P. D. Frost, C. H. Lorig, L. W. Eastwood, A. C. Loonam

It is well known that for equal weights of material, thin sections of the lighter structural alloys are more resistant to buckling under a compressive stress than thin sections of more dense material. Therefore, structural parts having the same resistance to buckling stresses are generally lightest when they are made of magnesium alloys. Consequently, there is considerable interest in the development of strong alloys having densities equal to or lower than that of magnesium and strength-weight ratios equivalent to those of the strongest aluminum alloys. The development of commercial magnesium-base alloys has been very successful, and their importance among materials in the structural field has been amply demonstrated. However, an even wider structural application of magnesium alloys might be effected if improvements could be made in the cold rollability and cold-forming characteristics. Such improvements, along with production of less directionality in properties. could be effected if the hexagonal close-packed lattice of present alloys could be replaced with a cubic lattice. In 1942, a project, having as its objective the improvement of some of the characteristics of commercial magnesium-base alloys, was initiated at Battelle Memorial Institute under the sponsorship of the Mathieson Chemical Corporation. At that time, one of the authors,* then Chief Metallurgist for the Mathieson Chemical Corporation, postulated that the addition of lithium to magnesium in sufficient quantities to change the crystal structure of the resultant alloy from a hexagonal to a body-centered cubic lattice should produce a magnesium-rich alloy which would have the desired improvements in cold-working characteristics with less directionality in properties. To test this view, a series of alloys was made and was found to have many of the attributes that were predicted. The view that magnesium-lithium alloys were of structural interest was also held by others. In 1943 and 1945, Dean and Andersonl,² obtained patents on magnesium-base alloys containing from about 1 to 10 pct lithium, from about 2 to about 10 pct manganese, and the balance substantially all magnesium; and on magnesium-base alloys containing from about 1 pct to about 10 pct lithium, from about 2 to about 10 pct manganese, from about 0.5 to 2 pct silver, and the balance substantially all magnesium. They noted that an alloy containing 83 pct magnesium, 10 pct manganese, 5 pct lithium, and 2 pct silver could be cold rolled by any of the usual methods and that this alloy was considerably harder and stronger than most other magnesium-base alloys heretofore available. In 1945, Hume-Rothery, et al.,3 predicted that magnesium-lithium base alloys should be soft and ductile and that such compositions, to which was added a third element for the purpose of producing a precipitation-hardening type of alloy, should be ductile, strong, and lighter than magnesium itself. Hume-Rothery investigated the binary magnesium-lithium and ternary magnesium-lithium-silver equilibrium relations and criticized the existing equilibrium diagrams. The binary magnesium-lithium equilibrium diagram has also been investigated by Grube, Von Zeppelin, and Bumm, Henry and Cordiano, Sal'dau and Shamrai, Hof-mann,' and Shamrai.8 The work of most investigators agreed with that of Grube, whose constitution diagram is shown in Fig 1. From the standpoint of development of structural alloys, the room-temperature equilibrium relations are of great interest. An examination of Fig 1 reveals that, from 0 to 5.7 pct lithium, the existing phase is alpha, which is a solution of lithium in hexagonal magnesium. The boundary between the alpha, and alpha plus beta regions, occurs at a Mg/Li of 16.5, corresponding to 5.7 pct lithium by weight. Between 5.7 pct and 10.3 pct lithium, there exists a mixture of the alpha phase (lithium dissolved in hexagonal magnesium) and the beta phase (magnesium dissolved in body-centered-cubic lithium). The boundary of the alpha plus beta and beta regions occurs at a Mg/Li of 8.7, corresponding to a lithium composition of 10.3 pct. Much of the work described here was directed toward obtaining an alloy made up of a large proportion, or entirely, of the body-centered-cubic beta structure. In his early work, Loonam found that specimens of lithium-bearing alloys were very malleable. Ingots of alloys prepared at that time were extruded to 3/8-in. diam bars, and the mechanical properties and the effects of heat treatment were then determined. These data are given in Table 1. The outstanding ductility of the alloys, combined with their moderately high strength, evoked considerable interest.

Jan 1, 1950

By Samuel M. Brock

Problems related to strip and auger coal mining have grown with the development of the industry and the economy. New technology has produced equipment that has made mining by surface methods not only highly productive, but potentially highly destructive of water resources and natural environments. On the other hand, growth of the economy has produced an increased demand for clean water and created new demands for amenity values that natural environments provide. Thus, opposing forces have created conflicts in resource use. And these conflicts have made surface mining highly controversial. Resolving the controversy will require the solving of complex economic and social problems. The essence of the economic problem created by surface mining is that, in the absence of proper regulation, substantial costs resulting from the process are borne by the public rather than the mine operator. The major goal for the regulation of the surface mining industry is to provide controls which will promote the attainment of maximum social welfare. Deciding upon the type of controls required, and how to apply them to attain a social optimum, however, poses some very difficult problems. In a comprehensive article on this subject, David B. Brooks defined the problem and suggested that benefit- cost analysis might be helpful in providing guidelines for making decisions about surface mining regulations.1

Jan 5, 1969

By T. E. Leontis, D. H. Feisel

MAGNESIUM alloys containing rare earth metals have received considerable attention during the past several years because of the need for light alloys having high strength and creep resistance at elevated temperatures. Although much of the work reported earlier has dealt with alloys containing Mischmetal, it has been shown in two previous papersl, V hat distinctly different effects are produced by various rare earth metals and rare earth metal mixtures on the properties of magnesium. For example, much higher strengths are obtained in magnesium alloys containing didym-ium (essentially neodymium plus praseodymium) than in alloys made with Mischmetal, which contains all the rare earth metals in the proportions in which they occur naturally in the monazite ore. Mg-rare earth metal alloys are characterized by a relatively coarse grain size, which greatly impairs castability. The addition of zirconium as a second alloying ingredient has been shown8,7 to refine the grain size, which also produces a distinct improvement in the strength properties. Certain Mg-Mischmetal-Zr and Mg-Mischmetal-Zn-Zr alloy compositions which are currently being produced commercially have been discussed in dytail by Nelson and Strieter,8,4 who also present some in- formation on a Mg-low Ce-Mischmetal-Zr alloy, and by Nelson.8 A patent issued to Jessup, Emley, and Fisher9 emphasizes the superiority of Mg-didymium-Zn-Zr alloys over the corresponding alloys made with Mischmetal. The purpose of this paper is to present the results of an extensive investigation concerned with the effect of increasing amounts of zirconium on magnesium sand casting alloys containing several different rare earth metal mixtures in varying amounts. The effect of the addition of zinc to some of these alloys is also being reported. Preparation and Testing of Alloys The alloys studied in this investigation were prepared in small laboratory melts according to the melting procedures described by Nelson1" as the Crucible Method. Electrolytic magnesium having the composition shown in Table I was used as the starting material. The rare earth metal alloying ingredients used in preparing these alloys were essentially of the compositions listed in Table 11. Some of the didymium-containing alloys were prepared using a Mg-didymium hardener. The rare earth metal content of this hardener analyzed 1.2 pct Ce, 10.4 pct Pr, 80.8 pct Nd, and 7.6 pct La. The zirconium was added in one of three forms: 1) as sponge zirconium obtained from the Bureau of Mines; 2) as a fused salt consisting of 50 pct ZrCl, and 50 pct alkali chlorides from which the zirconium is reduced by the magnesium; or 3) as a Mg-Zr hardener. The alloying procedures and melt hand-

Jan 1, 1958

The Keweenaw Peninsula in the Upper Peninsula of Michigan is plagued with abandoned prospectors' test pits and mine shafts, the result of exploration and operation of mines for over 100 years. The Fort Wilkins State Park in Keweenaw County alone has three open prospectors' pits within its boundaries, protected by wooden fences and maintained by the (Michigan State Conservation Department as a tourist attraction.

Jan 1, 1967

A remarkable industrial renaissance is underway in the People's Republic of China (PRC), says USBM's Dr. K. P. Wang in his recently released 96-page report on "The People's Republic of China-A New Industrial Power with a Strong Mineral Base." Dr. Wang's summary of the current mineral position of the PRC includes many insights into its future potential and trade possibilities with the West.

Jan 2, 1976

By Selma Hermann

For the past century, the so-called aluminum bronzes have been assuming a role of ever-increasing importance in the metallurgical field. The last quarter of that century has marked many efforts to find alloying elements that would alleviate some of the undesirable qualities of the aluminum bronzes-for example, the heterogeneity of the alpha solid solution and the extreme hardness of the beta. Much of this work, however, has been rather haphazard-compositions and heat treatment are usually so much at variance as to make comparison impossible. It is the object of this research to study the effect of certain percentages of common alloying elements on aluminum bronzes of analogous compositions and heat treatments. It is hoped that the material gathered here will at least serve as a basis for further systematic study.

Jan 1, 1930

By Bror Nordberg

SAND and gravel are unconsolidated granular materials resulting from the natural disintegration of rocks. The two materials nearly al- ways occur together, variably proportioned in widely available de- posits. A commercial sand comprises the fine granular material, usually less than f in. in diameter (ASTM Designation C58-28), and gravel consists of the coarse, granular material larger than sand (ASTM Designation C125-46T). Gravel falls within the range of 1/4 in. and a top size usually of 3 ½ in. Chemical definition is impossible. Sand and gravel are always of secondary origin. They were formed from various massive rocks through the action of chemical and mechanical forces; then transported, abraded, washed, sorted, and classified by streams, glaciers, waves, or winds, to be redeposited in beds as they are found. Chief disintegrating forces in the reduction of rocks into granular particles were frost, rain, the dissolving action of acid and alkaline ground waters, the mechanical action of streams and waves, and the action of glaciers. Method of formation and deposition have imparted physical properties to sands and gravels that largely determine the commercial value of the materials for particular use and influence the manner of exploitation. In the early days of the commercial industry, purchasing specifications were relatively lenient but in. the past decade much more rigid quality requirements have had to be met for acceptance by all classes of purchasers. The trend to further severity in requirements is a challenge to the industry that commands full knowledge of the nature of raw materials at hand and skillful application of processing into commercial products. Mechanical strength, the ability to resist disintegration, chemica

Jan 1, 1949

By S. Roath, F. Paul, D. Melville

Several attempts have been made over the past 40 years to separate red blood cells from whole blood using a magnet. This has been achieved by the authors by using a high gradient magnetic field and " carrying " the red cells in a suitable reducing agent - the deoxyhaemoglobin so produced has 4 unpaired electrons per atom giving appreciable paramagnetic moment as opposed to the usual oxygenated form which is diamagnetic. Red blood cells so separated appear to be undamaged and can be reinjected into a donor animal where their survival is shown to be normal using an isotope tagging technique. Studies on function of the white blood cells and blood platelets also indicate that they are functionally unchanged by separation process.

Jan 1, 1980

By George Evans

DURING the past ten or twelve years, the average reader of newspaper and magazine articles has been led to believe that enormous deposits of high-grade coal exist in the northland and that these can be mined for practically nothing. But much of the reputed glitter and attractiveness of Alaskan coals disappears when viewed at close range. Many areas of coal-bearing rocks are widely distributed geographically from Cape Lisburne, on Bering Sea, to Admiralty Island south of Juneau. Bituminous coal is found at Cape Lisburne, on the Bering Sea, at Five Finger Rapids on the upper Yukon, and at Herendeen Bay and Chignik Bay; lignite is found on the Kobuck River, along the Yukon River from points near the mouth to Tonakat, near Rampart, at Dawson, on the east shore of Cook Inlet, and in the Tanana Valley, 50 mi. south of Nenana. The Susitna and Matanuska Valleys contain coal ranging from lignite to anthracite, and in the Bering Lake district, there are coals ranging from semi-bituminous to anthracite. No effort will be made to describe all of these fields, but the writer wile confine himself to the four principal fields, namely, the Nenana field, in. the interior of Alaska, tributary to the Fairbanks district; the Matanuska, field, in the Matanuska Valley; the Kachemak Bay field on the east shore of Cook Inlet; and the Bering River field, east of the mouth of Copper River.

Jan 2, 1921

The Librarian of one of the Government Departments at Washington desires to secure one of the first editions of the Posepny Volume. It is a small book of about 265 pages. The Library in question will gladly pay the sum of $2.50 for the copy.

Jan 9, 1919

By Charles R. Fettke

In the present day manufacture of glass nearly pure quartz sands are used almost exclusively as the source of the silica, which is the major constituent of all common varieties of glass. Ordinary soda-lime, such as bottle, common tableware, plate, and window glasses, contains from 65 to 75 per cent. of silica. Occurrence Glass sands occur in nature either in the form of loose, unconsolidated sediments or in deposits in which the individual grains have been more or less thoroughly bound together by some cementing agent so as to form sandstones. While deposits of sand and sandstones occur both widely and abundantly distributed, deposits that are sufficiently free from other constituents than quartz grains, so that they can be employed in the manufacture of the better grades of glass, are, comparatively speaking, of rare occurrence. The major portion of the glass sand produced in the United States comes from sandstones. In order to be suitable for glass sand, they should be rather friable. The rock should break down readily along the cementing material between the grains and should not break across the grains rather than along the bond. Some of the sandstones used are so friable that only light shots of slow-burning dynamite are necessary to disintegrate them sufficiently for hydraulic mining, while others have to be passed through crushers in order to disintegrate the rock into its individual grains. MINERALOGICAL COMPOSITION An ideal glass sand is made up entirely of grains of the mineral quartz free from inclusions of foreign substances. Sands containing 100 per cent. silica, however, are not found in nature, although some very nearly approach this composition.

Jan 1, 1926

The John Fritz Medal was awarded in January, 1916, to Dr. Elihu Thomson, "For -Achievements in Electrical Inventions, in Electrical Engineering, and in Industrial Development, and in Scientific Research." The medal will be presented to Dr. Thomson at a meeting, to be held in Boston on Friday evening, Dec. 8, 1916, in the Central Lecture Hall of the new buildings of the Massachusetts Institute of Technology. The program of the evening will include adresses by John J. Carty, Chairman of the Presentation Committee of the Board of Award, E. W. Rice, Jr., President, General Electric Co., and Dr. Richard C. Maclaurin, President, Massachusetts Institute of Technology. The presentation will be made by Dr. Charles Warren Hunt, Chairman of the Board at the time the award was made, and the ceremonies will conclude with the response of Dr. Thomson. The John Fritz Medal is awarded from time to time for notable scientific or industrial achievement, and was provided for in a fund subscribed in memory of the great engineering pioneer, John Fritz. The award of the medal is made by a permanent board composed of four members from each of four American National Engineering Societies, namely, the American Society of Civil Engineers, the American Society of Mechanical Engineers, the American Institute of Mining Engineers and the American Institute of Electrical Engineers. The members of the 1916 Board are: CHARLES WARREN HUNT, Representing the A. S. C. E., JOHN A.. OCKERSON, GEORGE F. SWAIN, CHARLES D. MARX. JOHN R. FREEMAN, Representing the A. S. M. E., AMBROSE SWASEY, JOHN A. BRASHEAR, FREDERICK R. HUTTON. ALBERT SAUVEUR, Representing the A. I M. E., E. GIBBON SPILSBURY, CHARLES F. RAND, CHRISTOPHER R. CORNING.

Jan 12, 1916

By Malcolm McColl, C. A. Mead

Thin films (of mica have unique attributes that are exceptionally good for studies of high-field conduction mechamisms in thin-film insulators and the quantum mechanical tunneling of electrons from metal to metal. The principal advantages of using mica films are that the films are crystalline and the cleavage planes occur every 10Å. This property results in films whose thicknesses are integral multiples of 10Å and whose surfaces are uniformly parallel over sizable areas. Hence, very well-defined metal -mica-metal structures are possible. Furthermore, the fact that the insulator is split fro??! a bulk sample allows the index of refraction, dielectric constant, forbidden energy gap, and trapping levels and their density- to be obtained directly from measurements performed on thick samples Of mica rather than requiring that these properties be interred from the conduction characterrsties alone. In the work to he described, all the cleaving was done in a high vacuum just prior to the evaporation of metal elertrodes so as to avoid air contamination at the interfaces. Results of these studies indicate that the current through the 30 and 40Å films exhibited quantitative agreement with the theoretical voltage and temperature dependence derived by Strallon for the tunneling of electrons directly from metal to metal. Thicker films at room temperature exhibited volt-ampere curves suggesting Schottky emission of electrons from the cathode into the conduction band of mica. However, the thermal activation energy was smaller than that found from other measurements, and the experimsntal Schottky dielectric constant was larger than the square of the index of refraction. These facts would indicate that the electrons were being injected into polaron stales ill the iusulator. At low temperatures and high fields, the current through the thicker films did not exhibit the Fowler -Nordheim dependence as would be predicted by a simple extention of the theory of field emission into a vacuum. THE mechanism of electrons tunneling through insulating films has received considerable attention in the last few years due to the devices possible utilizing tunneling'-4 and the success of tunneling in the study of superconductivity.5,6 Until the recent paper by Hartman and chivian7 on the study of aluminum oxide, there had been no reported successful quantitative experimental fit to the theory. Their method of fabrication necessarily results in a polycrystalline insulator, the stoichiometry of which is nonuniform from one side to the other. This structure also introduces complications to the shape of the barrier which is set up by the insulator since the insulator possesses a spatially nonuniform band structure and dielectric constant. Due to these facts an analysis of the data in terms of a pviori barrier shape is of questionable validity. The use of muscovite mica not only overcomes these disadvantages but, as an insulating thin film, provides physical properties (dielectric constant. trapping levels and their densities, forbidden energy gap, and so forth) that are identical to the easily measured values of the bulk sample. Furthermore, it is a single-crystal insulator whose cleavage planes (10Å apart8,9) provide uniformly parallel surfaces of well-known separation. This material is therefore ideally suited to the study of electron-transport phenomena. Von Hippel10 using a 6.5-µ-thick sample was the first to observe the high-field conductivity (=5 x l06 v per cm) of mica. No attempt was made to develop an empirical formula, but Von Hippel concluded from intuitive arguments that the current was being space-charge limited by trapped electrons. Mal'tsev11 in a more recent investigation at high fields observed a dependence of the conductivity a on the field F of the form exp(ßF1/2). This dependence was attributed to the Frenkel effect,12,13 a Schottky type of emission from filled traps. No mention in the English abstract was made of the thicknesses of his samples or, and more important, of how well the value of ß fit Frenkel's theory. In 1962 Foote and Kazan14 developed a technique for splitting mica to a thickness of less than 100Å and observed a dependence of the current density j on the field of the form j = jo exp(ßF1/2) on a thin sample thought to be 40Å thick. Assuming that this was a Schottky emission process and that the appropriate dielectric constant for such a mechanism would be closer to a low-frequency value of 7.6, Foote and Kazan calculated from ß an independent thickness of the mica of 36Å. No further investigation was made of the phenomenon. However, the work reported in this paper indicates that the film measured by Foote and Kazan was probably 60Å thick, the error arising from the measurement of the very small metal-insulator-metal diode areas that were used, along with the diode capacitance and dielectric constant, to calculate the thickness. In the research reported in this paper, Foote and Kazan's technique was modified to cleave muscovite in a vacuum of 10-6 Torr, immediately after which metal electrodes were evaporated creating Au-mica-A1 diodes. Aluminum was chosen because of its strong adhesion to mica, as necessitated by the

Jan 1, 1965

By Bernard S. Borie

THE U-A1 binary system has been studied by Kaufmann and Gordon.' They have shown that three intermetallic compounds occur in the system: UAl², UAl², and a third compound tentatively identified as UA15. UA1³ is simple cubic, a, = 4.26A. Its unit cell contains one formula weight, and it is iso-morphous with AuCu³. UA1² is face-centered cubic, a, = 7.72A, with eight formula weights per unit cell. Rundle and Wilson have shown that it is iso-morphous with Cu²Mg.² A Debye-Scherrer pattern of the Al-rich compound indicated a more complex structure than either UA1² or UA1³. The following is a report of an investigation of the crystal structure of this compound and a determination of its stoi-chiometric formula. A melt of uranium (99.9 pct pure) and aluminum (99.9 pct pure) was prepared which contained about 25 pct U by weight. It was cooled from 950" to 650°C at a rate of 500" per hr and then taken from the furnace and air cooled. An X-ray diffraction pattern of the ingot showed only lines of aluminum and the Al-rich compound. Filings from the ingot were reacted with a solution of sodium hydroxide, producing a fine black powder, the diffraction pattern of which showed no traces of aluminum. A comparison of the Debye-Scherrer pattern of our sample with the data published by Kaufmann and Gordon1 showed that it is identical with the Al-rich phase which they reported. Single crystals were obtained by cooling the melt more slowly (about 50°C per hr). After reaction with sodium hydroxide, the crystals appeared as small black needles attached to the ingot surface. Cell Size, Space Group, and Uranium Positions A series of Weissenberg photographs for rotation about two of the crystallographic axes, taken with copper radiation filtered through nickel foil, revealed an orthorhombic cell of dimensions: a = 4.41 ± 0.02A b = 6.27 ± 0.02A c = 13.71 ± 0.03A Reflections of the type hkl were observed only if: h + k + I = 2n, of the type hkO only if: h = 2n and k = 2n, of the type h01 only if: h + 1 = 2n, and of the type Okl only if: k + 1=2n. Hence, the cell is body-centered with an 001 glide plane. The evidence for the existence of the glide plane is the observed extinction of 23 possible re- flections of the type hkO with at least one index odd. There are only two space groups consistent with these data: C"" — I2ma and D28 2h — Imma.³ he possible sets of atomic positions for these space groups are: 12ma: (0 0 0; ½ ½ ½) + 4: (a) x 0 %; x % % (b) x ¼ z; x ¾ Z 8: (c) x y z; x y z; x, ½ + y, Z x, M - y, z Imma: (0 0 0; ½ ½ ½) + 4: (a) 0 0 0; 0 ½ 0 (b) 0 0 ½; 0 ½ ½ (c) ¼ ¼ ¼; ¾ ¼ ¼ (d) ¼ ¾ ¾ ; ¾ ¾ % (e) 0 ¾ Z; 0 ¾ z 8: (f) x 0 0; x 0 0; x 1/2 0; x ½ 0 (g) ¼ Y ¼; ¾ Y ¾; ¾ y ¼; 1 y ¼ (h) 0 y z; 0; ;; 0, ½ + y, z; 0, l/2 - Y, Z (i) x 1/4 z; x ¾ z; ¼ z; x ¾ z 16: (j) xy z; x y z; x y z; x y z; x, ½ + y, Z; x,½ - y, z; x, ½ - y, z; 11 1, + y,Z Though density measurements on different samples were found to vary somewhat, they were all within the range 5.7 * 0.3 g per cu cm. If it is assumed that the unit cell contains four formula weights of UAl,, it is 6.5 g per cu cm. If there were as many as eight uranium atoms per unit cell, the

Jan 1, 1952

By R. Schuhmann, A. M. Gaudin, J. Dasher

Occurrrences of South African uranium have been known qualitatively for over twenty years, but no account was taken of them because of their low grade. In 1945, known uranium deposits were few, but their grades were 20 to 100 times higher than South African ores. Viewed in this light, the exploitation of South Africa's uranium is revolutionary indeed. Development of various analytical procedures capable of dealing with the needs of the project accounted for one-half of the cost and included: a) simple and automatic radiometric analytical procedures, b) sampling procedures appropriate to prevent sample contamination, c) procedures for sample and record-storing to accommodate many thousands of analyses per month, d) chemical methods giving high accuracy analyses for high grade samples not at radioactive equilibrium, and e) development of rapid procedures having moderate accuracy for low grade samples i.e., mill tailings and barren liquors. This task is continuing today with major improvements coming from time to time.

Aug 1, 1956

By R. Varbanov, D. Nikolov, I. Nishkov

An interesting new flotation technique which reportedly improves mineral recovery over an extended particle size range-from 3 mm to 5 microns and below-has been developed by the Institute of Physical Chemistry, Bulgarian Academy of Sciences. Designated the "static" flotation technique, it is suited for upgrading tin, molybdenum, tungsten, uranium, gold, copper, lead, zinc, and other metallic ores. Recoverable nonmetallics include feldspar, sulfur, and phosphorite. Characteristic of the static flotation process are: •longer contact period (up to 1000 times longer between particles and bubbles, •low collision velocity and inertial forces between the contact and aeration in a thin pulp layer, • aeration without the harmful hydrodynamic repulsion upon particles below 5 microns (the pulp layer is only a few millimeters thick and rising bubbles collide with the particles either directly or in the thin foam films formed), •option to conduct the process with or without froth by film flotation at equilibrium contact angles, and • the use of inexpensive frothers and/or unstable froth with separate regulations of froth stability by hydrodynamic, ultrasonic, or electrostatic means.

Jan 10, 1979

Man: A purely detached consideration of nature and the place of man in it may easily result in somewhat pessimistic conclusions as to man and his destiny. However, when we come to the evaluation of man's role in the development of natural resources and his achievements in this field, a more optimistic tone may be justified. Hence the possible contradictions between Man and Nature, Perfection, and the present chapter are more apparent than real. After all, progress must have a foundation of optimism, and we cannot challenge either the faculty or the students to better work and to a progressive and constructive outlook without an underlying tone of optimism and basic faith in the future. Geology is the basic science of Mother Earth; the science of the natural forces that have produced and modified the structure of our globe; the science of minerals and rocks; of landscapes and soils; of water supply and mineral resources, including mineral fuels; and of the history of life, both plant and animal, as revealed by fossils in rocks. It is difficult to reduce man and his historical significance to their proper relationship with regard to the earth and its history. Processes of rock formation have continued for at least two billion years; man's activities have been in evidence only a few thousand years. As a means of comparison, if the height of the Empire State building were to represent geologic time, the thickness of a nickel placed on the tower would just about repre-

Jan 1, 1950

By J. Henry Harden

I desire to call the attention of the Institute to a new form of drawing-board trestle. With the ordinary four-legged trestle, commonly used, one has not the means of adjusting the height of the board to the draughtsman. To obviate this inconvenience, and at the same time to enable one to incline the board, I have devised an arrangement of curved and straight slots and thumb-screws, by means of which the hoard can be raised three or more inches, and placed at any desired angle of inclination on either side. Figures 2, 3 (Plate I) show side and end elevations of the trestle for a single board, and Figure 4 for two boards. The latter form is adapted for use in schools, or where it is desired to economize space.