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By Leon W. Dupuy

Many articles have been written describing peculiar and particular types of drilling. Little correlation has been made between the character of ground to be drilled and sampled and the type of drilling most desirable for procuring satisfactory samples. In development work, the engineer and metallurgist often desire the recovery of a sample in as physically natural a condition as possible, particularly when the sample must provide material for process tests as well as chemical and physical analyses. This paper describes the results of experimentation in drilling unconsolidated materials carrying titanium minerals in the Magnet Cove area, Ark. The drilling was most difficult in that the ground varied much in consistency, and it was vitally necessary to recover a physically natural sample. Ordinary churn drilling recovered a sample that could be analyzed chemically, but the sample was not in its natural state. The problem was successfully solved by utilizing and further developing methods used in the oil and clay industries.

Jan 1, 1949

By J. L. CAHUTHERS

MANY different methods are used for transporting coal from the working face to the tipple. The common methods are animal haulage, locomotive haulage, conveyor systems, and combinations of these three, supplemented, at times, by the miner pushing his own car. Haulage may also be classified into gathering and main line. Gathering haulage is the collecting of loaded cars to a point whence they are hauled to the tipple. In this there is perhaps more lost-time than on the main line because there are .more units in the operation to be synchronized. Also, conditions on the gathering haul- age, such as bad track, poor timbering, insufficient motive power, etc., cause delays; usually these are corrected on the main-line haulage.

Jan 1, 1931

By H. I. Aaronson, C. Laird

Although the past results of X-ray experiments indicate that the broad faces of 0' plates are coherent with their matrix, dislocations lying in arrays have frequently been observed at these boundaries by transmission electron microscopy. Critical experiments employing the latter technique have been carried out in order to determine the origin of these dislocations. It is concluded that 8' plates are essentially coherent with the matrix at their broad faces throughout the aging temperature/time envelope studied. Virtually all of the dislocation arrays observed are deduced to have been formed by plastic deformation accompanying transformation. The proportion of dislocations arising from convexity of the plates is shown to be negligible by comparison with that from plastic deformation. At the higher aging temperatures, a[001] dislocations appeared in moderate numbers. These dislocations were traced directly, however, to the ledgewise dissolution of 0' occasioned by the formation nearby of 0 crystals. On the other hand, since there is a parametric difference normal to the broad faces of the ?' plates, mismatch dislocations do form at their edges. A previous conclusion that these dislocations have Burgers vectors of type a[001] was confirmed directly. The edges of 0' plates were observed to develop octagonal shapes when growing, but circular shapes during dissolution. 1 HIS paper presents the results of an investigation of the interfacial structures of plates of the transitional phase, 8', formed in an A1-4 pct Cu alloy. In a companion paper, Part 11, the effects of these structures upon the migration kinetics of a:?f boundaries are reported. This work is pa.rt of a general program designed to establish the basis of precipitate morphology. The present authors in Al-Ag,1 and whitton2 previously in U-C alloys, have used transmission electron microscopy to examine directly the vander Merwe3-6 networks of dislocations anticipated7 to compensate the small amount of lattice misfit normally founda at the broad faces of Widmanstatten plates. Since the broad faces of 0' plates are considered to be perfectly coherent with the corresponding habit planes in the a matrix,' no dislocations should be present at these faces. Many reports have been published, however, giving evidence to the contrary.10-18 The primary objective of this investigation was therefore to ascertain the nature of these dislocation structures. An attempt to do this is described in the first three sections of this paper. Inspection of the matching of the a and 8 ' lattices at the orientations of the 0:0' boundary corresponding to the edges of 0' plates raises the possibility that these edges may be made up of rather closely spaced edge- type misfit dislocations oriented so as to be sessile with respect to the lengthening or shortening of the plates. Since this structure should severely inhibit migration of the plate edges (Ref. 7, Part II), a situation not originally anticipated,' an experimental determination of the interfacial structure of the edges of 8' plates was clearly in order, and is reported in Section III. Those aspects of the experimental procedure applicable to both Parts I and I1 are presented in the next section. Specific procedures applicable to individual aspects of each investigation, and also the relevant surveys of the literature, are then individually reported in the appropriate sections. I) GENERAL EXPERIMENTAL PROCEDURE The material used in both parts of these studies was the same as that of a previous investigation:" strips of A1-3.93 pct Cu, 0.009 in. thick, prepared as before, solution-annealed at 548°C for 6 hr, and quenched. Details of subsequent aging, and in some cases deformation treatments, are given in the Experimental Procedure sections of the individual parts of both papers. Specimens of the heat-treated strips were electro-thinned as beforeLg and examined in a Philips EM 200 microscope equipped with a goniometer stage. A commercial hot stage, of the grid-heater type and capable of * 30-deg tilt about one axis in the plane of the specimen, was also used for kinetic studies. The usual precaution of calibrating for the additional heat supplied by the electron beam was taken.19 A 16-mm cine cam-I era mounted outside the viewing window was frequently used to record the transformations. Conventional selected-area diffraction and dark-field viewing techniques were used to identify the precipitates in the foils. Normal bright-field images corresponding to two-beam diffracting conditions or dark-field images were employed to characterize the dislocations observed at the interfaces of the precipitates. The application of these techniques to the study of an interphase boundary, and the interpretation of the images,20'21 has been fully described in a previous paper.'

Jan 1, 1969

By Ralph Arnold

IN OPENING the symposium under the auspices of the Petroleum and Gas Committee of the American Institute of Mining and Metallurgical Engineers, I wish to call to your attention the following, among other subjects, which it is hoped may receive proper attention: 1. The recording of as accurate an appraisal of the oil possibilities of the various countries as is possible, with information as to the immediate availability of their supply. 2. The development of further support for the move-ment to bring about active cooperation among Ameri-can oil companies in their foreign exploration and development work. 3. The furtherance of the efforts of the industry in securing governmental assistance in foreign oil develop-ment: (a) along the lines of a modification of our domestic oil policy, so that we can go to foreign coun-tries and consistently ask fair treatment as to royalties and bonuses; (b) by a closer cooperation between the State and Commerce Departments and the oil industry. 4. The calling of attention to the unjustifiably drastic action of the price-fixing group of the oil industry during the last year or so, with the hope that it will use gentler methods in the future. None of these subjects are new, and some of them have been discussed before various organizations for years. Our justification for again bringing them forward is the hope that by everlastingly harping on them the industry, the Government, and the people who shape the destinies of this country may some time, some how, realize their importance and take effective constructive action.

Jan 6, 1922

By E. S. Tankins

The main purpose of this work was to study the effect of gold on the activity coefficient of oxygen in the liquid Fe-Au alloy and to determine how copper and silver change the activity coefficient of oxygen. A preliminary investigation has been made of equilibrium in the reaction of hydrogen with oxygen in some of the liquid gold alloys. The experimental method, which has been described in detail elsewhere,' consisted of bubbling accurately known H-A-water vapor mixtures through the Fe-Au alloys contained in alumina crucibles within a vertical closed furnace. When equilibrium was reached, the samples were quenched by rapidly lowering the crucible under an atmosphere of argon to a water cooled brass fixture at the bottom of the furnace tube. The melts were found to freeze from the top in less than 4 sec. The heats were carefully prepared for oxygen analysis. The oxygen content was determined by vacuum fusion analysis.' Only high purity electrolytic materials were used in this investigation. The activity and free energy of oxygen in the liquid iron alloys were studied by means of the reaction; The data for the 80 Fe-Au alloys, obtained as a function of temperature, are summarized in Table I and presented in Fig. 1, where log is plotted against . The results can be expressed by: The data were obtained using water vapor-hydrogen ratios between 0.04 and 0.30, and a 25 pct H2-75 pct A mixture. An oxygen content between 0.030 and 0.060

Jan 1, 1970

By Robert M. Yerkes

The following is a brief account of the methods of measuring intelligence especially prepared for use in the U. S. Army, of typical results, and of some of their immediately practical applications. It has been prepared for the assistance of army examiners and for the information of all who are interested in the relations of scientific placement to military efficiency. Purpose of the Intelligence Tests Under the direction of the Division of Psychology, Medical Department, and in accordance with provisions of War Department General Order No. 74, mental tests are given recruits during the 2-wk. detention period. These tests provide an immediate and reasonably dependable classification of the men according to general intelligence. Their specific purposes are to aid: 1. In the discovery of men whose superior intelligence suggests their consideration for advancement; 2. In the prompt selection and assignment to development battalions of men who are so inferior mentally that they are suited only for selected assignments; 3. In forming organizations of uniform mental strength where such uniformity is desired; 4. In forming organizations of superior mental strength where such superiority is demanded by the nature of the work to be performed; 5. In selecting suitable men for various army duties or for special training in colleges or technical schools; 6. In the early formation of training groups within regiment' or battery in order that each man may receive instruction and drill according to his ability to profit thereby; 7. In the early recognition of the mentally slow as contrasted with the stubborn or disobedient; 8. In the discovery of men whose low-grade intelligence renders them either a burden or a menace to the service.

Jan 1, 1919

By C. R. Kuzell

GEOGRAPHICAILY the industry of reducing and refining of copper continued to migrate from the .United States during 1931. While this country is losing the predominant position of its copper industry, our engineers still enjoy their pre-eminent position as leaders in the design and operation of the new plants being brought into production in the four quarters of the globe. Progress in the art, as indicated by the construction of the recently completed works, has not been revolutionary. Standard methods have been followed, augmented by novel features in flow-sheets demanded by the results of progress in the art of ore-dressing, and by reason of problems incidental to the peculiarities of the new ores being treated. Design and construction progress has likewise been orderly and without radical departure from less recent practice; new features in primary and secondary equipment being logical developments to provide for special conditions to keep abreast of improve¬ments in accessory apparatus. The new plants are being rapidly brought in without hazardous novelties and for the purpose of yielding the principal ingredient, copper, in as large a volume as it will he possible to market; the old United States procedure. In the meantime the domestic plants are shut down or operating at a very low capacity, threatened with untimely demise unless the metallurgist can extract and develop other valuable products from the ores. International agreements .and tariff protection may be a temporary reviving stimulant, but for many mines the days of profit will be numbered unless the ores can be made to yield as values the ingredients now being discarded. Invisible progress in this direction has been made during the past year, and it is to he hoped that time will prove that the outstanding progress of 1931 was in the development of processes for the ultimate recovery of by-products from copper ores, perhaps even relegating the value of the copper yield to secondary importance.

Jan 1, 1932

By B. S. Butler, H. D. McCaskey

The New London copper mine, about 8 1/2 miles east of Frederick, Md., was visited by the writers for a few hours in the spring of 1909 and the following brief notes on ore specimens collected are presented as a contribution to studies in chalcocite ores. For certain data on the structural and areal geology of this portion of Maryland the writers are under obligation to the unpublished notes and maps of Arthur Keith. The detailed study of the ores is the work of B. S. Butler. The deposit here discussed has many similarities to those of the Virginia district of Virginia and North Carolina, which have been described by Gratonl and Laney,2 except that in the deposits of the New London mine chalcocite is by far the most important ore mineral, while in the Virginia deposits bornite is commonly the most important sulphide. In the New London occurrence calcite is the most important gangue mineral. Field relations The -town of Frederick lies in the center of a narrow belt of limestone ranging in age from Ordovician on the east to Cambrian on the west. This belt is about + mile wide at Noland's Ferry, on the Potomac, and broadens to a width of 3 miles at Frederick. The general direction is east of north. The eastern boundary is, in places, a fault plane along which a series of metamorphic rocks of presumptive pre-Cambrian age have been thrust up. These ancient rocks, for several miles east and west of New London, are phyllites in the main, but closely inter-folded near the New London mine are long, narrow lenses of epidote

Jan 1, 1915

By R. A. Deju, R. B. Bhappu

The theory of electrophoresis is briefly outlined and an apparatus which may be used for electrophoretic studies is explained. The results obtained using this apparatus are in agreement with those obtained by other investigators. How to solve some of the complications which occur in the measurement of zero charge and zeta potential is explained. It is believed that the apparatus described in this paper will allow rapid measurements of zeta potential, zero point of charge, electrophoretic mobility and zeta coefficient. For many years the phenomenon of electrophoresis has been studied, and much work has been done in designing an apparatus for better measurements of mobility, zeta potential and zero charge of minerals. Up to the present, most electrophoresis experiments have involved cumbersome equipment and tedious microscopic observation. The modified cell proposed in this paper obviates these drawbacks by using a Rayoscope together with a special system of lenses and filters. It therefore allows a faster and more accurate measurement of zero charge and particle velocity. THEORY Most authors currently regard zeta potential as the potential difference in an otherwise uniform medium between a point some large distance from the surface of the mineral and a point on the plane of shear. Fuerstenau,1 Miaw,2 and Gaudin and sun3 have performed some calculations of zeta potential using Henry's equation.4 Their results show wide discrepancies, probably due to differences in the past histories of the minerals used. The authors have also noticed this difference on determining the zero point of charge of quartz as shown on Table I.

Jan 1, 1967

By J. B. Ackerman, J. D. Miller

Alunite [KA13(S04)2(OH)6] is a promising non-bauxitic aluminum resource, the domestic reserves of which are estimated to be 800 x 106 tons at 35 percent alunite. The major gangue mineral associated with alunite is quartz. The thermochemical process that has been developed for treatment of this ore does not provide for the initial removal of gangue prior to processing. In this regard, it may be desirable to concentrate the ore to gain significant technical and economic advantages. Experimental results indicate the effectiveness of an oleic acid flotation technique and exemplify the problems encountered in fine particles processing. These results show that the quality of separation studied as a function of temperature, collector addition, and depressant addition is dependent on the degree of liberation achieved during size reduction. At coarse grinds the quality of separation was limited by the presence of locked particles while for finer grinds where more extensive liberation is achieved, better separations were obtained. The degree of liberation for each size interval was determined by an SEM/energy dispersive x-ray technique and found to be independent of the extent of size reduction, suggesting that liberation occurs by indiscriminate fracture and not by detachment. Up to 89 percent liberation was realized for a minus 400 mesh grind. Under these circumstances, the quality of separation appears not only to be limited by the remaining locked particles, but, also, by contamination of the alunite concentrate with fine quartz gangue (< 2µm). The best separation for the minus 400 mesh grind was a rougher recovery of 88 percent with a grade of 65% alunite at 50°C.

Jan 1, 1980

By H. Stigzelius

FINLAND&apos;S recent mining history is both dramatic and pitiful in its shifting fortunes, dominated as it has been, by the country&apos;s proximity to the border zone of opposing dictatorships and social traditions; Fascism to the south, Communism to the east, and Democracy to the west. After 108 years under Russia&apos;s more or less harsh rule, Finland gained its democratic independence during the 1917 revolutionary strife in Russia with the official help of Germany and spontaneous help of other neighbors. The young nation was attacked by Russia in 1939 and again in 1941. It is common knowledge how the Finns fought with everything they had and everything they could get against their overwhelming adversary, and how by force of circumstances they landed in the Axis camp in 1941. Finland has never been known as a mining country in the same way as near-by Sweden, whose abundant iron and copper smelters during long periods so greatly contributed to the nation&apos;s welfare. Its largely barren, Archaean-granite geology long seemed forbidding. Some mining was done, to be sure; copper and tin at Pitkaranta near the Russian border, and lead and copper at Orijarvi. But towards the end of the last century the absence of a single producing mine cast a pessimistic shadow of truth over the Finnish poet Runeberg&apos;s words, that

Jan 1, 1946

By J. F. Myers

THE Tennessee Copper Company&apos;s operations are in the Ducktown Basin, in the extreme southeast corner of Tennessee. The ore is of the heavy sulphide type, the predominating sulphides being pyrite, pyr-rhotite, chalcopyrite and sphalerite. The gangue is a micaceous schist, with varying amounts of free quartz. The mining operation develops two classes of ore, each of which is concentrated by the flotation process in separate mills. Table 1 shows a typical analysis of the ore treated in each mill. TABLE 1.-Typical Analysis of Ore Treated Composition, Per Cent Mill Tons Capacity Cu Fe S Zn London 1,350 1.41 28.4 20.2 1.10 Isabella 850 0.69 44.7 31.6 0.31 LONDON MILL The London mill was built in 1922, with a capacity of 400 tons per day. This was gradually increased to 600 tons by 1926, to 900 tons in 1928, and to 1350 tons in 1938. Fig. 1 shows the crushing and grinding flowsheet in 1928, when the capacity was 900 tons; Fig. 2, the crushing and grinding flowsheet that was developed by 1938, for the treatment of 1350 tons per day. A comparison of these flowsheets reveals that this increase in tonnage, with a subsequent improved operation, was accom-plished with identically the same major equipment. Improving a concentrator&apos;s capacity, metallurgical results, and costs as time goes by is a commonplace practice, and is accomplished in various ways, depending upon the local conditions. The reason for presenting the data of how this was accomplished in the mills of the Tennessee Copper Co. is that a fast-running rod mill plays such an interesting role

Jan 1, 1940

The 139th meeting* of the American Institute of Mining and Metallurgical Engineers was held at New York, February 17 to 20, 1930, the attendance totaling approximately 1800. The meeting consisted of the annual business session, 34 technical sessions at which were presented 166 papers, two meetings of the Board of Directors, two meetings of Section Delegates, two formal lectures and one special lecture, five group dinners and one group luncheon, luncheon daily for members and guests, fourteen committee meetings and conferences, the President&apos;s reception, the dinner-dance, an informal dance, a smoker, an exhibition of rare minerals and metals, two meetings of the Woman&apos;s Auxiliary and a special program of entertainment for the ladies. The Petroleum Division held seven sessions, including two general sessions featuring, respectively, a symposium on unit operation of oil pools and reports on developments in the petroleum industry during the previous year. The Iron and Steel Division held four sessions, at one of which Dr. Zay Jeffries delivered the Howe Memorial Lecture, the title of which was "The Future of the American Iron and Steel Industry." The Institute of Metals Division held six sessions, including two devoted to a symposium on the Melting and Casting of Metals, and the general session at which Dr. S. L. Hoyt delivered the annual Institute of Metals Lecture. The title of his lecture was "Hard Metal Carbides and Cemented Tungsten Carbide." The Coal and Coal Products Committee devoted one session and the greater part of another to Coal Classification and at a third session organized as the Coal Division of the Institute. The Committees on Mining Methods and Ground Movement and Subsidence each held a session, besides which they met jointly. Sessions were held by other Technical Committees as follows: Nonferrous Metallurgy, 1; Geophysical Prospecting, 2; Nonmetallic Minerals, 2; Milling Methods, 1; Rare Minerals and Metals, 1; Mining Geology, 2; Mine Ventilation, 2; Engineering Education, 1. At the annual business meeting on February 18, the following ticket was elected, and the reports of the President, Treasurer and Secretary were presented: William H. Bassett, President; Scott Turner, Vice-president; Henry Krumb, Vice-president; R. C. Allen, Cadwallader Evans, Jr., John M. Lovejoy, John A. Mathews and Milnor Roberts, Directors. At an executive session of the Directors on Tuesday afternoon, H. A. Guess was elected Vice-president to fill the vacancy created by the

Jan 1, 1930

By Henri S. Swolfs

INTRODUCTION In this paper we present preliminary results of a research program in site characterization methodology. We are interested in under- standing the response of discontinuous rock to mechanical, hydrologic, and thermal loadings. To carry out such a study we selected a field site with simple geology, uniform distribution of lithologies, and easily verifiable boundary conditions on temperature, fluid flow and stresses. The spatial distribution of fractures at the site was established and tests were conducted to determine the temperature field, hydrology, rock-mass properties, and in situ stresses. As part of the study selected borehole instruments were compared to assess their performance and reliability. SITE GEOLOGY The study area is in the eastern part of South Table Mountain, a mesa near Golden, Colo. The exposed cap rock is a single lava flow of uniform thickness (6-7 m) that rests on the clastic sediments of the Denver Formation (Van Horn, 1976). The surface of the cap rock (N. 75º E., 3º S.) is topographically featureless and slopes south- southeast; drainage is predominantly downdip and punctuated by occasional contact springs. The age of the lava flow is 64-65 m.y., or early Paleocene. Paleo- botanic evidence confirms the upper part of the Denver Formation as Paleocene (Van Horn, 1976). "Rapid-rock" analyses of core samples from the lava flow at three depths (0.2, 3.3, and 5.8 m) suggest a uniform chemical composition throughout with an increase in the Fe2O3/ FeO ratio (1.05 to 1.60) with increasing depth, reflecting the existence of a perched water table in the lava flow, To identify the rock

Jan 1, 1984

By W. R. Ingalls

THE propaganda in favor of the adoption of the metric system of weights and measures in the United States is founded upon the idea of compulsory adoption. There can be no argument about this, for the metric system has been legal, by Act of Congress, in the United States since 1866. Nobody ought to oppose an educational movement, and if pro-metric activities were confined to that there might be no reason to gainsay them. I do not propose to enter into any discussion of &apos;the relative merits of the metric and the English systems of weights and measures. The simple case is that the metric system not having made much headway in the United States after more than 50 years of legality, &apos;it is now aimed to force it upon the people by legislative compulsion. The main arguments in favor of such compulsory adoption are that it would- simplify the education of our children and would promote our foreign trade, for the reason that more countries of the world, with which we do business, use the metric system than the English system. I am going to disregard,&apos; in this contribution, the first of these arguments, for it is largely conjectural." Not so with the other, which is specific, and being so its speciousness can be, proved. It is true that the metric system is used by more countries of the world than the, English system. It is commonly stated that of the Indo-European nations only the United States, Great Britain, and her colonies, and Russia have failed to adopt it. However, if with "colonies" we equate Canada, Australia, New Zealand, Tasmania and South Africa, we have a longer list of non-metric countries, and it comprises not only the most populous, but also the most industrial nations of the world.

Jan 1, 1921

By T. H. Aldrich

THE Aldrich Mining Co. holds under lease from the Illinois Central R. R. Co. about 14,000 acres, in the East half of Township 12, Range 12 `V., in Marion county, Alabama, and owns other lands, of which about 1,000 acres adjoin this leased tract, making a total area of about 15,000 acres, all of which is underlain by the coal-seam upon which the company is operating. This seam is nearly horizontal ; and a ravine, diagonally crossing the tract, exposes the outcrop on either side for about 2 miles. The territory has been so divided that nearly the whole of it can be worked out by two collieries. The mines at Brilliant were opened in the Fall of 1898, and shipments began in the following spring. The original plan was to furnish steam-coal for locomotives to the Illinois Central R. R. Co.; and upon this expectation the investment of capital was made. The field was entirely new; and the softness of the coal at the outcrop induced the belief that it could be very cheaply mined. A contract for the delivery of a large quantity of coal to the railroad was accordingly executed. But with the advance of the entries to increasing distances from the outcrop, the coal proved so hard that it could no longer be drilled with a breast-auger; and the expense of mining became so great that the contract for cheap steam-coal had to be cancelled. It became evident that the work must be done with machinery and explosives, if it could be profitably done at all. On the other hand, the excellent quality of this coal opened, at the same time, a possible market not specially contemplated at the outset-namely, that of a first-rate coal for domestic and general uses. Since no other deposit of such coal was known to exist on the line of the Illinois Central, or any other railroad

Jul 1, 1906

By R. H. Johnson

The Manual of the Oil and Gas Industry, under the Revenue Act of 1918, published by the Treasury Department for the guidance of oil companies in preparing their estimates of future recoverable oil for the purpose of calculating depletion, gives the first large public collection of comparative decline curves for the whole country. It is a matter of both scientific and practical interest to so arrange these data that the pools can be readily compared. There are certain difficulties in such a comparison, however: (1) The economic limit varies from 50 to 2000 bbl. a year in different pools taken. (2) Because of this variation in economic limit, the range of data shown makes comparison possible only for wells of intermediate size. In order to be as inclusive as possible, I have taken as an expression of the rate of decline the amount of oil produced in the period during which a well drops from 3000 to 2000 bbl. a year. No period of smaller production could be used because of the high economic limit in California; and no period of larger production and yet include the small well areas of the Appalachian. As it is, the Lima-Indiana wells are excluded. In a few instances, curves were extrapolated to obtain the reading, where the curve seemed regular enough to warrant it. In general, the amount of oil, in barrels, produced while a well declined from 3000 bbl. to 2000 bbl. a year is shown in Table 1.

Jan 1, 1921

By Allan J. Clark

THE September issue of MINING AND METALLURGY might almost have served as a review of the advances in the metallurgy of gold during the current year. In addition to a scholarly article by F. W. Bradley, there were able descriptions by W. W. Bradley and W. F. Boericke of the methods followed in California and in Ontario. Considered together, the two last-named articles indicate the many possible combinations of flotation with one or more of the older processes. This, the prominence of flotation as an aid in the beneficiation of gold ores, is probably the most striking of the year&apos;s developments. It would perhaps be nearer the fact to say that the year has not been marked by the gold metallurgists&apos; discovery of the flotation process, but rather by the flotation merchandizers&apos; discovery of gold metallurgy. I say this because native gold was floated successfully more than fifteen years ago, and a reference to these results was published six years ago.

Jan 1, 1933

By Niels Hansen

Dispersion-strengthened sintered aluminum products are normally manufactured from surface-oxidized aluminum powder, SAP,&apos; or from atomized aluminum powder.&apos; The powder-blending technique consisting in mechanical mixing of the constituents has been used in the manufacture of numerous dispersion-strengthening alloys, but has never been successfully applied to aluminum alloys. This technique may, however, be applicable if it is possible to produce an unagglomerated mixture of the constituents in the form of fine powders, and the present study was initiated to test this assumption in the aluminum/aluminum oxide system.3 Table I lists the two grades of aluminum powder and the aluminum oxide powder used in the manufacture of the alloys. MD 105 A is an aluminum powder with an average grain size less than 5 IJ., which is isolated from the MD 105 powder by centrifugal separation in cyclohexanol. The aluminum powders and the aluminum oxide were blended in a high-speed blender and then subjected to cold compaction and hot compaction at 550" to 600°C. Subsequently the compacts were hot-extruded with an extrusion ratio of 15 to 1. The alloys were evaluated by tensile testing at room temperature and at 400°C, microscopic examination, and heat treatment at 500°C followed by tensile testing at room temperature. For the purpose of comparison, a commercial SAP quality supplied by Swiss Aluminium Ltd. was tested in the same manner. The tensile data at room temperature and at 400°C are plotted in Figs. 1, 2, and 3 as a function of the weight percent of oxide. The oxide content

Jan 1, 1964

By Emery R. Hayhurst

SILICOSIS has been described in a report of the American Public Health Association as a disease due to breathing air containing silica, characterized anatomically by generalized fibrotic changes and the development of miliary nodulations in both lungs, and clinically by shortness of breath, decreased chest expansion, lessened capacity for work, absence of fever, increased susceptibility to tuberculosis (some or all of which symptoms may be present), and by characteristic X-ray findings. ... The disease is divided arbitrarily into first, second, and third stages for convenience of description and possible compensation purposes. At least two distinct types of silicosis are recognized, acute and chronic. The acute form was reported as early as 1713, when a British patent for grinding flint by wet methods was granted because the dry powdered material "proved very destructive to mankind, so much that any person, ever so healthful, working in that business cannot possibly survive over two years."

Jan 1, 1936