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By Edward N. Trump

EXTENSIVE beds of rock salt occur in New York, Michigan, Kansas, and Texas. Wells are drilled through the beds, cased, and equipped with a suspended center tube. By circulating water through such a well, the soluble saline is dissolved and a brine produced. Operation of a well results ordinarily in the formation of an inverted conical cavity in the saline, inasmuch as the dissolving action of the fresh water is more rapid at the top of the bed than at the bottom. Under continued operations, the side wall of the cavity becomes so flat that a blanket of mud is deposited thereon and if the bed is overlain with shale or a soft rock caving follows. Three methods of operating wells have been employed-the "Tully plan," "the Detroit plan," and "the Trump plan." Both the Tully plan and the Detroit plan involve the formation of the aforesaid conical cavity with constant caving of shale above and deposition of mud on the side wall; the Trump plan was developed to avoid both these circumstances and thus materially prolong the life of a well. Details of the three plans follow. THE TULLY PLAN In the Tully plan, the water passes down the annular space between the casing and the center -tube, the brine rising in the center tube (Figs. I and 2). An inverted conical cavity is formed, the side wall of which relatively soon becomes so flat that it is blanketed by mud and impurities from the rock salt; this blanket limits dissolving action to the perimeter of the base of the cone, situated at the top of the saline bed. Caving of the overlying strata follows, and the total production of brine from the well is comparatively small. THE DETROIT PLAN In the Detroit plan, the water passes down the center tube, the brine rising in the annular space between the center tube and casing (Figs. I and 2). Initially, this flow forms a pear-shaped cavity in the bottom of the salt bed, but this cavity soon changes in shape to that of an inverted cone, as under the Tully plan, with the attendant disadvantages inherent in that plan. Application of the Detroit plan is limited to salt beds 300 ft. thick as a minimum. This depth of bed is necessary to prevent fresh water of lower specific gravity than the brine from rising in the

Jan 1, 1944

By Edward N. Trump

Extensive beds of rock salt occur in New York, Michigan, Kansas, and Texas. Wells are drilled through the beds, cased, and equipped with a suspended center tube. By circulating water through such a well, the soluble saline is dissolved and a brine produced. Operation of a well results ordinarily in the formation of an inverted conical cavity in the saline, inasmuch as the dissolving action of the fresh water is more rapid at the top of the bed than at the bottom. Under continued operations, the side wall of the cavity becomes so flat that a blanket of mud is deposited thereon and if the bed is overlain with shale or a soft rock caving follows. Three methods of operating wells have been employed—the "Tully plan," "the Detroit plan," and "the Trump plan." Both the Tully plan and the Detroit plan involve the formation of the aforesaid conical cavity with constant caving of shale above and deposition of mud on the side wall; the Trump plan was developed to avoid both these circumstances and thus materially prolong the life of a well. Details of the three plans follow. The Tully Plan In the Tully plan, the water passes down the annular space between the casing and the center tube, the brine rising in the center tube (Figs. I and 2). An inverted conical cavity is formed, the side wall of which relatively soon becomes so flat that it is blanketed by mud and impurities from the rock salt; this blanket limits dissolving action to the perimeter of the base of the cone, situated at the top of the saline bed. Caving of the overlying strata follows, and the total production of brine from the well is comparatively small. The Detroit Plan In the Detroit plan, the water passes down the center tube, the brine rising in the annular space between the center tube and casing (Figs. I and 2). Initially, this flow forms a pear-shaped cavity in the bottom of the salt bed, but this cavity soon changes in shape to that of an inverted cone, as under the Tully plan, with the attendant disadvantages inherent in that plan. Application of the Detroit plan is limited to salt beds 300 ft. thick as a minimum. This depth of bed is necessary to prevent fresh water of lower specific gravity than the brine from rising in the

Jan 1, 1948

By Dominique François-Bongarçon

A new method for open-pit design has been devised by G. MATHERON and the writers: it replaces the search for an optimum contour by the determination of a parametrizing function. The isovalue curves of this function give the optimum pit design corresponding to varying economic parameters; The method is described and indications are given about the corresponding program. Simulated data have been processed by the program and by a standard program using LERCES-GROSSMAN graphical method: the comparative results are described.

Jan 1, 1977

By W. G. Moffatt, J. Wulff

BRAZED joints and their strength have for some time been of great practical as well as theoretical interest. A good summary of the previous work in this field may be found in the reports of the Armour Research Foundation. In spite of excessive scatter in test data, the fact that the strength of a brazed joint may exceed the ultimate strength of the brazing material itself by many times continues to be of interest and of value in engineering. That this is qualitatively due to plastic constraint of the brazing material by the faying surfaces of the base metal is not in dispute, yet no complete interpretation of the data exists. The purpose of the present work is not to provide such a new interpretation, but to report new experimental data which we hope may lead to a better understanding of the important variables concerned. The work of Bredz' definitely shows that the thinner a brazed joint is, the greater is its strength. Dianeter of a joint has seldom been taken into

Jan 1, 1958

By Sumner M. Anderson

Any discussion of outside support to Latin American mineral industries must concede at once the pre-eminent role of U. S. industry and business. American capital has developed the great copper resources of Chile and Peru, the lead-zinc of Peru and Mexico, the bauxite of Surinam and Jamaica, the petroleum and iron ore of Venezuela. American consumers have provided the market for their products. U. S. companies operating south of the border have trained Latin American geologists, engineers, chemists, and skilled labor-including metal, mineral, and fuel technicians-to new and greater competence. The industrial demands of World War II drastically altered world economics and concepts of U. S. foreign mineral requirements. In this country discovery of vital mineral resources fell far behind the alarming depletion rates, and there was new appreciation of the actual and potential importance of the world's less extensively explored areas. During the war and afterward, the task of supplying the nation's mineral requirements became greater than private industry could carry alone, and the Government assumed a position of continuing support.

Jan 11, 1958

By H. E. Rorschach

Activity in the oil and gas fields of Oklahoma was more pronounced in 1935 than in 1934, with 2320 completions, an increase of about 21 per cent. The state produced approximately 185,000,000 bbl. in 1935. Osage County and shallow pools in northeastern Oklahoma showed considerable activity. The assembly of a complete table of the oil fields of the state (Table 1) was not achieved, as many of the early records of operators and pipe line companies are not complete, and data for the older fields will perhaps never be fully tabulated. Table 1 includes all of the new fields and most of the important fields of the State of Oklahoma. Increased Field Activities The discovery of large production in the deep Simpson group in the old Fox field in Carter County in the southern part of the state, the discovery of new producing horizons in the Fitts pool, and the extension of Wilcox production in the "Mansion" area at Oklahoma City were the outstanding developments in Oklahoma in 1935. Wildcatting resulted in the discovery of new pools such as Jesse, Hoyt, Grayson, South Keokuk, Wofford, Britton and Stillwater. The Fitts and Edmond pools were rapidly developed during the year. Fox Pool.—Deep production in southern Oklahoma became a reality in October when the Williams No. 1 well of Carter Oil Co. and others, in the Fox pool, began producing oil at the rate of 10,000 bbl. per day from a depth of 8088 ft. After flowing wild several days, the well was killed after pipe stuck and a difficult fishing job resulted. The job had not been completed at the end of the year 1935. This test, considered one of the most important oil discoveries in the Mid-Continent area, opened the entire South Oklahoma area to a deep exploration campaign for Simpson production and production in the Pennsylvanian series on the south flank of the Arbuckle Mountains.

Jan 1, 1936

By H. E. Rorschach

Activity in the oil and gas fields of Oklahoma was more pronounced in 1935 than in 1934, with 2320 completions, an increase of about 21 per cent. The state produced approximately 185,000,000 bbl. in 1935. Osage County and shallow pools in northeastern Oklahoma showed considerable activity. The assembly of a complete table of the oil fields of the state (Table 1) was not achieved, as many of the early records of operators and pipe line companies are not complete, and data for the older fields will perhaps never be fully tabulated. Table 1 includes all of the new fields and most of the important fields of the State of Oklahoma. Increased Field Activities The discovery of large production in the deep Simpson group in the old Fox field in Carter County in the southern part of the state, the discovery of new producing horizons in the Fitts pool, and the extension of Wilcox production in the "Mansion" area at Oklahoma City were the outstanding developments in Oklahoma in 1935. Wildcatting resulted in the discovery of new pools such as Jesse, Hoyt, Grayson, South Keokuk, Wofford, Britton and Stillwater. The Fitts and Edmond pools were rapidly developed during the year. Fox Pool.—Deep production in southern Oklahoma became a reality in October when the Williams No. 1 well of Carter Oil Co. and others, in the Fox pool, began producing oil at the rate of 10,000 bbl. per day from a depth of 8088 ft. After flowing wild several days, the well was killed after pipe stuck and a difficult fishing job resulted. The job had not been completed at the end of the year 1935. This test, considered one of the most important oil discoveries in the Mid-Continent area, opened the entire South Oklahoma area to a deep exploration campaign for Simpson production and production in the Pennsylvanian series on the south flank of the Arbuckle Mountains.

Jan 1, 1936

A permanent exhibition of mining machinery has just been opened in the Grand Central Palace, New York City. The exhibits include: Aerial tramways, amalgamation, assaying and laboratory appliances and supplies, blast furnaces, coal, coal-breaker plant, coal excavation, coal products, compressed-air plant, concentrating, crushing, cyanidation, distillation, drainage and pumping, drilling, earth excavation, electrical supplies, explosives, fire prevention, flotation, general supplies, hoisting, hygiene, welfare, iron products, leaching, mechanical conveyors, metal products, natural gas, petroleum, petroleum products, electric, steam, hydraulic, gas, air, and internal-combustion engines, power machinery, preparation of coal, pumping, refining, roasting, rock excavation, rotary drilling; boring, safety appliance, screening and washing, sizing and classifying, smelting, storage of coal, storage of petroleum, surface transportation, surveying, underground timbering, underground trans-port, ventilation, mine. This exposition is operated by the Merchants and Manufacturers Exchange of New York for the purpose of showing under one roof all lines of machinery and mechanical appliances. As for as possible, the exhibits will be shown in operation. The Advisory Committee is as follows: General Howard R. Ward and H. C. Parmelee. Coal and Coke.-Prof. H. H. Stoek, Samuel A. Taylor, Edwin Ludlow. Petroleum and Gas.-Frederick G. Clapp, Ralph Arnold.¬ Extraction of Metals.-Charles W. Merrill, E. Gybbon Spilsbury. Refractories.-Kenneth Seaver.

Jan 12, 1919

By John V. Beall

W hen the blasts went off on West 11th St., just off 5th Ave. in New York City, James Michaels, editor of Forbes magazine, was in his office a few doors away reviewing color layouts with his production manager. Having once been a reporter, he grabbed his trench coat and dashed for the street to be con- fronted by the demolished townhouse which had been turned into a bomb factory by youths. To Michaels, this shocking episode supplied the exclamation point to thoughts he was formulating that an era had ended and a new one was beginning in the economic and social climate of the U. S. "For twenty years corporate profits, the stock market, middle income pay have gone up and up. . . The illusions of twenty years are in confrontation today with changed needs," he said. "International omnipotence is economically beyond our means, . . The anti-pollution and community renewal people are not nuts in tennis shoes who will go away. . . That corporation presidents can report an increase in earnings every year is an illusion that will be dropped. . . There has been a $200 billion shrink in value of stocks and bonds since Nixon came into office" were some indicators Michaels mentioned.

Jan 1, 1970

THE following employment items are made available to AIME members on a non-profit basis by the Engineering Societies Personnel Service, Inc., operating in cooperation with the Four Founder Societies. Local offices of the Personnel Service are at 8 W. 40th.St. New York 18; 100 Farnsworth Ave., Detroit; 57. Post St., San Francisco; 84 E. Randolph St., Chicago 1. Applicants should address all mail to' the proper key numbers in care of the New York office and include 6c in stamps for forwarding and. returning application. The applicant agrees, if placed in a position by means of the Service, to pay the placement fee listed by the Service. AIME members may secure a weekly bulletin of positions available for $3.50 a quarter, $12 a year. MEN AVAILABLE Mining Engineer, 41, married, one child, employed. Broad experience, both underground and open-pit, type mining. Exploration, development, exploitation, industrial construction, milling in northwestern United States. Desires position with progressive, established concern. M-666-259¬Chicago. Recent Graduate, 24, married, no children, B.S. mineral economics. Employed-one year's experience in development of deposits, study of problem areas. Will accept position anywhere in the world. Available immediately. M-667.

Jan 1, 1952

A cooperative service for engineers and their employers under the direction, of the American Institute of Mining and Metallurgical Engineers; American Society of Civil Engineers; American Society of Mechanical Engineers; and American Institute of Electrical Engineers, and with the cooperation in Chicago of the Western Society of Engineers, and in San Francisco of the California Section of the American Chemical Society and the Engineers Club of San Francisco. For information as to men available or positions open, address the nearest office. New York Walter V. Brown Manager, 31 West 39th St., Telephone Penn. 9220 Chicago A. Krauser, Manager, Room 1736, 53 West Jackson Boulevard, Telephone Harrison 1238 San Francisco Newton D. Cook, Manager, Room 715, 57 Post . St., Telephone Sutter 1684 UNITED ENGINEERING SOCIETY This is a corporation organized by the American Institute of Mining Engineers, American Society of Mechanical Engineers and the American Institute of Electrical Engineers to hold the title and administer the property at 29 West 39th St. In 1916 the American Society of Civil Engineers was admitted, and each society now holds an equal one-fourth interest in the ownership, occupancy, and administration of the building. The value of this property is estimated at two million dollars. A. I. M. E. representatives are : Arthur S. Dwight, J. Vipond Davies and J. V. N. Dorr. ALFRED D. FLINN, Secretary, 29 West 39th St., New York City. ENGINEERING FOUNDATION This is a fund established by the United Engineering Society in 1915 with a gift of $200,000 from Ambrose Swasey. Subsequent gifts had increased the fund to $600,000 on Jan. 1, 1927. The income, of the fund is used to further research in science and engineering and to advance the profession of engineering and the good of mankind. A. T. M. E. representatives are: H, M. Boylston, J. Vipond Davies, Galen H, Clevenger. ALFRED D. FLINN, Secretary, 29 West 39th St,, New York City.

Jan 1, 1928

The New York Meeting this year will-be held from Monday, February 19 to Thursday, February 22. The Committee on Arrangements, the personnel of which is given elsewhere in this Bulletin, is making plans to duplicate the conspicuous success of last year's meeting in New York. The papers to be read at this meeting, it is believed, furnish material for interesting and profitable technical sessions and symposiums. The social features are being carefully planned since it is believed that these form an important part of such meetings; several functions are to be, given with the object of fostering the get-together, know-each-other-better spirit. Ladies are invited to attend this meeting and participate in the various affairs planned by the Ladies' Committee and by the Committee on Arrangements. This preliminary notice is given in order that members may make their plans now to be in Now York at the time of the meeting. Full details will be sent to the membership through the mails as soon as the program has been definitely fixed.

Jan 1, 1917

By C. H. Wilson, J. J. Jakosky

In recent years geophysical prospecting methods have become well established as important steps in economically initiating new mining ventures in the field of base-metal exploration, placer mining and water-supply problems. The value of these methods as applied to these problems has been greatly increased by new and improved instruments, and a greater degree of skill in laboratory and interpretative technique. Considerable success has been attained, with subsequent drilling checking the predicted depths within 1 to 5 per cent, on problems requiring information on thickness of fill material, depth to and contour of bedrock, extent and yardage of gravels to be mined, and location of hydrostatic water table. In these applications the geophysical work gives data comparable to drilling, and at a cost of about one-fiftieth that of drilling. Discussion of several surveys with accompanying illustrations showing geophysical methods applicable to both simple and complicated placer problems are contained in the paper. The electrical instruments for measuring electromagnetic field strength and surface potentials are described, and their use, coupled with that of other geophysical instruments in modern field procedure, is noted.:

Jan 1, 1934

THIS issue is about Chuquicamata and the new sulphide plant. Chuquicamata is moving into a new cycle of productivity; she has begun to give up the sulphide copper which lies deep-seated beneath the oxide ore zones in large but yet unknown quantity. After forty years of production, Chuqui may be likened to a strapping youngster, with adolescence and maturity still ahead. Mining operations are being projected-not for decades -but for generations. Although there are still many years of open-pit mining ahead, planning of future underground mining has been started. The bottom of the orebody is still unknown, but enough work has been done to show that Chuqui is one of the largest known copper orebodies in the world. Until recently, only the oxide ores have been mined and these have been treated at the rate of 50,000 to 60,000 tons per day by leaching. Construction of the sulphide plant was timed to coincide with reduction in production of oxide ores. The new sulphide concentrator and smelter, designed in keeping with the magnitude of the orebody, will be brought on the production line at the rate of 30,000 tons per day. The capacity of the plant now planned can be expanded to treat 60,000 tons of sulphide ore. Little wonder that Chuqui is a name legendary in the remotest mining circles. But to those who have known her more intimately, and there is hardly a mining camp without a Chuqui graduate, she means much more. She is an orebody that has made engineers. Reposing at 10,000 ft on the western flank of the Andes in the arid northern reaches of Chile, water is scarce, common fuels absent, and volcanoes and earthquakes add drama and hazard. It is these natural difficulties which have created the fascination and challenge which have caused many engineers to devote their lives to unlocking this treasure house of nature.

Jan 1, 1952

By S. J. Sindeband

Prior to discussing the metallurgy of sintered chromium borides, it is pertinent to outline some of the reasoning behind this investigation and the purposes underlying the work. This study was initiated as an aproach to the ubiquitous problem of a material for service at high temperatures under oxidizing atmospheres, and it was undertaken with a view to raising the 1500°F (816°C) ceiling to 2000°F (1093°C) or better. For the reason that no small, but rather a major, lifting of the high temperature working limit was being attempted, it was felt appropriate that a completely new approach be taken to this problem. A summary of the thinking behind this approach was published recently by Schwarzkopf.' In briefest terms, it was postulated that the following requirements could be set up for a material which would have high strength at high temperatures. 1. The individual crystals of the material must exhibit high strength interatomic bonds. This automatically leads to consideration of highly refractory materials, since their high energy requirements for melting are related to the strength of their atom-to-atom bonds. 2. On the polycrystalline basis, high boundary strength, superimposed on the above consideration, would also be a necessity. Since this implies control of boundary conditions, the powder metallurgy approach would hold considerable promise. Such materials actually had been fabricated for a number of years, and the cemented carbide is the best example of these. Here a highly refractory crystal was carefully bonded and resulted in a material of extremely high strength. That this strength was maintained at high temperature is exhibited by the ability of the cemented carbide tool to hold an edge for extended periods of heavy service. Nowick and Machlin2,3 have analytically approached the problem of creep and stress-rupture properties at high temperature and developed procedures whereby these properties can be approximately predicted from the room temperature physical constants of a material. The most important single constant in the provision of high temperature strength and creep resistance is shown to be the Modulus of Rigidity. On this basis, they proposed that a fertile field for investigation would be that of materials similar to cemented carbides, which have Moduli of Rigidity that are among the highest recorded. The cemented carbide, however, does not have good corrosion resistance in oxidizing atmospheres and without protection could not be used in gas turbines and similar pieces of equipment. It would be necessary then to attempt the fabrication of an allied material based upon a hard crystal which had good corrosion resistance as well. It was upon these premises that the subject study was undertaken and at an early stage it was sponsored by the U.S. Navy, Office of Naval Research. Since then, it has been carried on under contract with this agency. Chromium boride provided a logical starting point for such research, since it was relatively hard, exhibited good corrosion resistance, and, in addition, was commercially available, since it had found application in hard-surfacing alloys with iron and nickel. That chromium boride did not provide a material that met the ultimate aim of the study results from factors which are subsequently discussed. This, however, does not detract from the basis on which the study was conceived, nor from the value of reporting the results which follow. Chromium Boride While work on chromium boride proper dates back to Moissan,4 there has been a dearth of literature on borides since 1906. Subsequent to Moissan, principal investigators of chromium boride were Tucker and Moody,5 Wede-kind and Fetzer,6 du Jassoneix,7,8,9 and Andrieux." These investigators were generally limited to studies of methods of producing chromium boride and detennining its properties. Some study, however, was devoted to the chromium-boron system by du Jassoneix,7 who did this chemically and metal-lographically. This system is not amenable to normal methods of analysis by virtue of the refractory nature of the alloys involved, and the difficulties of measurement and control of temperature conditions in their range. Dilatometric apparatus is nonexistent for operation at these temperatures. Du Jassoneix made use of apparent chemical differences between two phases observed under the microscope and reported the existence of two definite compounds, namely: Cr3B2 and CrB. These two compounds, he reported, had quite similar chemical characteristics, but were sufficiently different to enable him to separate them. The easiest method for producing chromium boride is apparently the thermite process, first applied by Wede-

Jan 1, 1950

By Rossiter W. Raymond

The extent to which the divining-rod is still used in this country for the detection of hidden treasure, mineral veins, or springs, is ' much greater than educated persons would be likely to suppose. For many years wells have frequently been located by its aid in New England, where the belief is widely extended among the farmers that in the hands of peculiarly gifted persons this instrument possesses special virtue. Large numbers of the oil wells of Pennsylvania

Jan 1, 1883

By R. B. Sudderth, C. R. Merigold

Greater, emphasis is being placed on recovering nickel from laterite ores by ammonia leaching techniques. New methods are required for lower cost, non-polluting techniques to separate more efficiently the metals of interest. Liquid ion exchange techniques meet these requirements with the added advantage of producing salable electrowon nickel cathodes at the plantsite. A complete solvent extraction- electrowinning process is described, including preliminary engineering and cost data for a typical plant producing 50 million pounds of nickel per year.

Jan 1, 1973

G. SHERBURNE ROGERS,* Washington, D. C. (written discussion?).- We are indebted to Captain Lucas for an interesting contribution to the literature of the salt-dome oil fields, and especially for his suggestion that a more aggressive method -of prospecting be adopted. The occasional discovery of new fields on, the Gulf Coast is in itself sufficient to show that the oil possibilities of the region are by no means exhausted, and those who have studied the area most thoroughly are the most optimistic regarding its future. Nevertheless, the search for new fields, according to present methods, involves the expenditure of great sums of money annually, for the proportion of dry holes to producing wells drilled yearly in the Gulf Coast region is much' greater than in most areas, even if all the wells drilled in what is commonly regarded as proved territory are included. Not only are the present methods of locating new domes very uncertain, but when a dome is discovered there is no assurance that it will be oil-bearing; or, if so, whether the oil occurs in the cap-rock, in the sands above it, or in some small isolated lens of sand far down on the flanks of the salt mass. As Captain Lucas points out, about all we positively know is that the domes are there and that some of them are oil-bearing; their origin is a matter of controversy and the original source of the oil is conjectural. Under these conditions, it is not surprising that the search for oil is conducted more or less blindly and that dry holes are common. Many wells are drilled each year in an endeavor to find oil at depths of 2000 or 3000 ft. (609 to 914 m.) or less, in locations which most geologists would condemn without hesitation. As Captain Lucas suggests, the money spent in this way might be used to far better advantage in, drilling one deep well in a carefully selected locality. Opinions may differ as to whether such a, well would find oil, and many geologists will probably believe that the chances are against it, yet all will agree that the boring, whether it finds oil or not, will probably throw light on the origin of the domes and on the source and mode of accumulation of the oil, and will therefore be of great interest, not only to the scientist, but to the oil operator.

Jan 10, 1918

By E. C. Bitzer

The primary object of the work described in the following pages was to simplify the equipment in the separating circuit of the heavy-media process by substituting a spiral classifier for the separatory cone. Mechanical considerations were the leading attraction and the best that was hoped for on metallurgical performance was that the new vessel would give results equal to those obtained by conventional equipment. Tests have demonstrated in commercial operation on iron ore that the mechanical advantages of the spiral separator are about as predicted; also, the metallurgical performance is superior to the cone on the ores treated. Treatment of iron ore involves the separation of two products: a concentrate that sinks and a float product that contains true float material plus a controlled division of interfering middling. The middling material is heavier than the average specific gravity of the separating medium. Recent work with the spiral separator on Tri-State zinc ore showed that the middling material had to be recovered as concentrate because this fraction contained the bulk of the zinc in the ore. It has been demonstrated that it is possible to make three products with the new separator on an ore such as this: a float tailing, a float middling, and a high- grade heavy sink product. It appears from this last work that the new separator has definite mechanical and metalluigical advantages over any type of separating cone for treating feed that contains large amounts of material of a specific gravity close to that of the separating medium. However, either type of separator should perform equally well, metallurgically, on feed that is free of middlings. Each series of experiments with the spiral separator has required additional work to fully develop the possibilities of the machine. For this reason the paper is divided into chronological parts. History of Development A drag-type classifier was first proposed as a substitute for the cone separator by Butler Brothers technicians during the initial tests with galena medium at Crosby, Minn., in 1937. The desire for finding a substitute for the cone arose from trouble with interfering middlings and certain operating disadvantages of the cone. The possibility of using a spiral classifier was also suggested at this time by Emmett Butler and C. J. Abrams. However, inability to satisfactorily recover fine galena, which was used as a medium, terminated all development work at Crosby. During the winter of 1937--1938 investigation started on magnetic medium with concurrent development of the inverted or closed-top cone, which was found necessary to eliminate iron-ore middlings with the float product. About

Jan 1, 1949

THE following employment items are made available to AIME members on a nonprofit basis by the Engineering Societies Personnel Service, Inc., operating in cooperation with the Four Founder Societies. Local offices of the Personnel Service are at 8 W. 40th St., New York 18; 100 Farnsworth Ave., Detroit; 57 Post St., Son Francisco; 84 E. Randolph St., Chicago 1. Applicants should address all mail to the proper key numbers in care of the New York office and include 6c in stamps for forwarding and returning application. The applicant agrees, if placed in a position by means of the Service, to pay the placement fee listed by the Service. AIME members may secure a weekly bulletin of positions available for $3.50 a quarter, $12 a year. MEN AVAILABLE Geologist-Petrographer. Experienced subsurface geology and petrographic rock and mineral identification. Desires position as either geologist or petrographer. M-682. Geologist, 36, married, employed. Nine years' experience geology connected with engineering, includes planning and supervising core drilling programs, study of stratigraphy and structure, special problems, report writing. Three years' teaching experience. Desires responsible position offering opportunity for advancement with progressive concern. Will travel part time. Available reasonable notice. M-683. Mining Executive with record of accomplishment organizing and directing efficient low cost mining and ore dressing operations available for position in the United States. Broad experience engineering, mechanized mining, flotation, safety, union labor relations and preparation of reports. Married. Employed; available upon reasonable notice. M-684.

Jan 1, 1952