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By R. T. Hukki

IT is no great exaggeration to say that present grinding practice and economics are largely determined by lining design. A record of outstanding liner wear can be achieved with any liner surface pattern that will positively lock the outer layer or layers of grinding media. With no slippage, lining wear is bound to be slight. At the same time, popular practice calls for tumbling loads of about 50 pct of mill volume to obtain maximum grinding capacity. Innumerable parallel grinding investigations have verified that optimum speed for such a mill lies within 70 to 85 pct of theoretical critical speed. If the mill is speeded up to 100 pct of critical, little or no grinding can be accomplished. Earlier Work on Supercritical Grinding: First investigations concerning grinding at supercritical speeds seem to be very old. Remarkable work on the subject has been performed by White,&apos; and his experiments have been described and summarized by Richards.&apos; White&apos;s contributions seem to have passed unnoticed by Fahrenwald,2,3 whose extensive experiments have been well presented, yet apparently very little appreciated. Additional work on grinding at supercritical speed has been reported, e.g., by Lewenson and Tscherny,&apos; USSR; Anselm and Grunder,&apos;, Germany: and Rose and Evans." Great Britain. Subcritical and Supercritical Speeds: In the formula of the critical speed given in the textbooks of mineral dressing, no factor indicating the coefficient of friction is generally included. If this factor = 1.0, which is equivalent to grinding conditions in a mill provided with heavily ribbed lining, the formula of the critical speed holds as such and grinding is possible at subcritical speeds only. In a mill equipped with a smooth or relatively smooth lining, the numerical value of the friction factor in the denominator of the formula becomes <1.0, indicating that grinding at supercritical speeds should be possible in such mills. It has been recently shown by the author&apos; that a wide supercritical speed range will become available for grinding—and especially for fine grinding—if the basic conditions within the mill have been selected properly. Mathematical analysis of mill dynamics at supercritical speeds&apos; has indicated that the mill speed may be increased if: 1) total mass of grinding medium decreases, 2) mass of the individual grinding piece increases, and 3) the coefficient of friction between the outer layer of medium and the mill lining decreases. It is obvious that the mass of the individual grinding piece will be affected by its shape and by its specific gravity. The coefficient of friction decreases with: 1) increasing smoothness of liner surface, 2) increasing roundness of the grinding piece, 3) increasing fineness of material to be ground, 4) decreasing pulp density, and 5) decreasing hardness (abrasiveness) of the mineral to be ground. In a mill equipped with heavily ribbed lining, practically no size reduction will take place between the lining and the outer layer of tumbling medium, because slippage is prevented. In the overwhelming majority of today&apos;s mills the grinding accomplished is by virtue of cataracting and/or cascading media with some action within the tumbling charge. Sub-critical speeds only can be applied. In grate-type or peripheral discharge mills equipped with a smooth lining a tumbling load of any kind of common medium occupying about 50 pct of mill volume will behave in such a way that practically no slippage will take place. This has been verified in experiments run by the author in the laboratory and in pilot plant mills&apos; equipped with smooth lining. Again, the operation is limited to the subcritical range. In a mill with a smooth lining, grinding will be possible either at subcritical speeds or within a wide supercritical speed range as soon as the basic requirements for a desired speed are fulfilled. In a mill operated at supercritical speed, any point on the liner surface proceeds at a speed greater than that indicated by the formula of the critical speed, while any grinding piece situated in the outer layer of the medium against the lining proceeds in the same direction at a speed less than that indicated by the critical speed. This speed difference produces a very effective attrition grinding zone between the liner surface and the outer layer of the medium. The share of attrition grinding of the total grinding accomplished increases rapidly with increasing speed in the supercritical speed range. The smooth surface of the mill lining may be well illustrated by the surface of a bucking board. The outer ball layer may be similarly represented by the lower surface of a muller. If the bucking board, the material to be ground, and the muller all proceed in the same direction at the same speed, no grinding will result. This is the general situation in the mills of today. If, however, the muller is pulled with respect to the board, moving or stationary, grinding will be accomplished effectively. Although grinding in today&apos;s mills is primarily the result of cataracting and/or cascading media, the principal place of grinding at high supercritical speeds will be the attrition zone.&apos; In the mineral dressing laboratory of the State Institute for Technical Research. Helsinki, Finland, large quantities of different ores have been ground in a pilot plant ball mill (3x3 ft) at a top speed about 230 pct of the critical. With the same mill, theoretical investigations concerning the grinding characteristics of ball mills equipped with a smooth lining have been carried out up to the speed of 313 pct&apos; of the critical. With a smaller mill, the grinding characteristics with a variety of grinding media have been investigated at speeds up to 2000 pct of the

Jan 1, 1959

E. O?C. Acker Truman H. Aldrich Walter H. Aldridge Anson W. Allen John H. Allen W. Lawrence Austin W. S. Ayres David Baker John Henry Banks Alonzo F. Bardwell Robert Bentley Andrew A Blair Walter M. Brodie Fredrick Burbidge H.H. Burden Charles Butters

Jan 1, 1939

By Charles E. Barker

Jan 1, 1985

United Engineering Trustees, Inc. GEORGE D. BARRON WILLIAM H. BASSETT R. M. ROOSEVELT The Engineering Foundation GEORGE D. BARRON H. C. BELLINGER E. DEGOLYER Engineering Societies Library Board ROBERT PEELE PHILIP W. HENRY H. K. MASTERS A. B. PARSONS, Ex-officio R. H. SWEETSER

Jan 1, 1932

By R. B. Woodworth

In the sinking of bore holes, there are but two fundamental operations —drilling and hoisting—which determine in the main the character of drilling mechanism and structures. There are endless ramifications, however, in the execution of these fundamental operations, according to the purposes for which the bore holes are drilled, their maintenance after completion, the protection and convenience of workmen, etc. The three main lines of use for bore holes are in mineral exploration, the sinking of water and salt wells, and the exploitation of pqtroleum and natural gas. This paper has to do more especially with the last. Here again there are many divergences. Wells may be drilled by either the percussive, the hydraulic, or the abrasive method. Finally, each of these methods, as applied by drillers of diverse nationalities, has followed somewhat different lines of development. The American system of cable-tool drilling has perhaps had the widest application; the hydraulic rotary is also in extensive use; but the Canadian system, the Galician system, and the Russian free-fall system all have their points of recognized merit and are preferred by operators accustomed to their use. These differences in drilling procedure, which rest ultimately on essential variations in geological conditions, are reflected in the drilling structures as well as in the drilling mechanism. The purpose of the present paper is to record those stages in the development of the application of steel to the construction of drilling mechanism and structures with which the writer has been intimately associated, and to contribute to the history of the art of drilling other data acquired in the course of his personal investigations. It is necessarily limited by reason of space to American practice, with especial reference, therefore, to the cable-tool system and the hydraulic rotary method of drilling wells for oil and gas.

Jan 1, 1916

By C. H. Mahoney, A. L. Tarr, P. E. Le Grand

Magnesium, it is now generally realized, differs in some important aspects from most other structural metals, not excepting even its close neighbors, the aluminum-base alloys. This is particularly true with respect to the effects of elevated temperatures on the two light metals when in the molten state. Aluminum, 0&apos; the one hand, should not be raised above its melting point any higher than is absolutely necessary if one is to avoid danger of gas absorption and a tendency toward grain growth in the resultant casting.&apos; Magnesium alloys, in sharp contrast, actually benefit by being heated to temperatures considerably above their melting point, It is a commonly accepted practice to establish the desired fine grain in the industrial magnesium alloys of the aluminum-hearing group by raising the temperature of the melt after the refining treatment to some 250°C (482°F.) above the melting range. To recall briefly the typical practice for magnesium alloys, the molten metal is refined by fluxing at about 730°C. (I350°F.), and after the melt has been covered with a suitable flux, the temperature is raised to between 870°C. (I600°F.) and 930°C. (1700°F.). It is then cooled as quickly as possible to the casting temperature. This superheating, as it is called, results in a fine-grained cast metal structure which has superior mechanical properties, enhanced amenability to &apos;solution heat-treatment, and better machinability than cast metal that has not been superheated. The minimum temperature of superheating varies to some extent with the composition of the alloys to be treated and usually increases with the percentage of magnesium in alloys containing the same constituent metals.&apos; It should be noted that the grain-refining effect of superheating is markedly apparent only in connection with the alloys containing aluminum as an alloying Constituent—the binary alloy containing 1.5 per cent manganese, for example, is not refined in grain to any noticeable extent by a superheating effort. While the phenomenon of superheating is well known in the magnesium industry, the mechanism of the process has remained a mystery During the superheating cycle something occurs that forces a fine grain upon the solidifying metal. The process has been controlled in an empirical manner, and occasionally, especially on large-scale melts, and for no apparent cause, no grain refinement is obtained from a superheating treatment. Only a few papers of importance have been published on the subject. Of these, one of the most helpful is the paper by Achenbach, Nipper and Piwowarski,3 which gives considerable data concerning the effect of superheating on various properties such as fluidity, shrinkage and hot crack

Jan 1, 1945

By P. K. Currie, J. V. Walters

Solution mining of magnesium salts (Carnallite and Bischofite) is taking place near Veendam, in the northeast Netherlands. The magnesium salts are used for the production of magnesia sinter, used as a base material for the manufacture of refractory bricks for furnaces. This paper gives, first, an introduction to the operational procedure followed in Veendam, with the emphasis on some of the unique aspects, and then discusses rock-mechanical aspects of the cavity behaviour. The creep behaviour of magnesium salts is described, and Finite Element calculations on cavity stability and potential surface subsidence are discussed.

Jan 1, 1985

The following is an incomplete list of members and guests who called at Institute headquarters during the period Sept. 10, 1919, to Oct. 10, 1919. L. D. Anderson, Salt Lake City, Utah. P. S. Matthews, Newark, N. J. Ray J. Barber, New York City. A. Poole Maynard, Atlanta, Georgia. L. A. Barton, Major U. S. Engineers. L. J. Mayreis, Jamshedpur, India. J. A. Battle, Chicago, 111. Benj. L. Miller, Bethlehem, Pa. R. W. Bissell, New York City. Geo. D. Morgan, Bartlesville, Okla. Gilman E. Brown, Shanghai, China. A. C. Munroe, El Paso, Texas. Stanley Brown, Chuquicamata, Chile, Paul I. Norton, Jr., Columbus, Ohio. S. A. Walter G. Perkins, Stanford University, Norman Carmichael, Clifton, Arizona. Cal. Richard H. Catlett, Newark, N. J. Fred S. Porter, Seattle, Wash. Roderic Crandall Charles E. Prior, Cherry Creek, Nevada John J. Croston, Atlanta, Georgia. G. M. Richards I. N. Dally, Seattle, Wash. Gilbert Rigg, Melbourne, Australia. A. Faison Dixon, New York City. Pierre H. Sauvajol, Paris, France. Walter Dobbins, Springfield, Ill. Carl Scholz, Chicago, Ill. Foss E. Douglass, Rancagua, Chile. Ellsworth H. Shriver, Marysville, Ohio. H. S. Emlaw, Grand Haven, Mich. Harvey B. Small, Magangue, Colombia. R. S. Everet, Barre, Mass. Henry B. Smith, New Britain, Coma. H. W. Gipp, Melbourne, Australia. J. T. Smoody, Cornwall, Pa. F. A. Glass, Brainerd, Minn. S.. J. Speak, London, England. C. D. Grier, New York City. D. R. Thomas, New York City. James L. Head, Rancagua, Chile. Kirby Thomas, New York City. Geo. B. Holderer, New York City. R. M. F. Townsend, Washington, D. C. W. Spencer Hutchinson, Boston, Mass. Carl J. Trauerman, Helena, Mont. Henry Jequier, Paris, France. A. C. Veatch, London, Eng. L. W. Kemp, Chuquicamata, Chile. Myron R. Walker, Pittsburg, Pa. Herbert S. Kohlberg, El Paso, Texas. Curtis C. Webb, New York City. H. M. LaFollette, La Follette, Tenn. James Wilding, San Francisco, Cal. Richard Lamb, New York City. S. H. Zimmerman, New York City.

Jan 11, 1919

Abadilla, Quirico A., Geol.. Lago Pet. Corp Box 172 Maracaiho, Venezuela. IIAbbw. Robert Graham. The W. W. Sly Mfg. Co.Train Ave.. Cleveland. Ohio. Abbotf A. N., Mines Supt., Maznpil Copper Co.. Ltd..Conception del Oro, Zac., Mexico. Abbotf Clarence E, Mgr.. Mines & Quarries, Tenn. Coal. Iron & R. R. Co., 1242 Brown Marx Bldg., Birmingham, Ala. Abbott. Louis Benjamin. Chief Engr.. Consolidation Coal Co. ... .Elkhorn Div., Jenkins, Ky. Abeel, George 8.. Jr., Cons. Min. Engr...4612 West 17th St., Los Angeles, Cal. Abel. Albert E.. Asst. to Pres.. Valley Mould & Iron Corp..Hubbard, Ohio. Abel. Raymond L Asst. Prof., Dept. of Pet. Refin.. Univ. of Pittsburgh. .. .Pittsburgh. Pa. Abernathy. George Elmer. Prof. of Geol. & Min.. Kansas State Teachers College. Pittahurg. Kans. Abernethy, D. Carl, Jr. Min. Engr., Hudson Coal Co. .Scranton, Pa. Abw, Hirouhi. Min. & Met. Engr., Min. & Met. Dept., The Higher Technical School, Osaka, Japan. Aborn. Robert H.. Research Assoc.. Mass. Inst. of Tech..Cambridge, Mass. Abouchar. Bylvain Sley. Min. Engr. & Geol., c/o S. H. Sekaly, 13 Rue El Nimr, Cairo, Egypt. tAbozeid. Mahmood. Pet. Min. Engr., Marland Oil Co. of California, Subway Terminal Bldg., Los Angeles, Cal. Abraham. Arthur W.A. pt. 40, Barcelona. Anzoatmui, Venezuela. Abrahams. Alexander I.. Gen&apos;l Mgr., Racon Electrical Co.. ..... .Slough, London, England. tAbrahamuon, C. W., Min. Engr.. The Mond Nickel Co., Ltd.. ..... .Levack. Ont., Canada. Abstein, Henry T.. Engr. & Mgr.. Profile-Tamarack Mines Co.. ...... .Yellow Pine, Idaho. tAcker, E. WC.. Met.. ........ .I28 East Washington Lane. Germantuwn. Philadelphia, Pa. IlAckerman, D. E.. Research Engr.. Research Lab., International Nickel Co., Bayonne, N. J. tAckerman. Ernest R., Pres., Lawrence Portland Cement Co.. . .Plainfield, Union Co., N. J. Adachi. Jinzoo.A..d dress Wanted Adachi, Yuichi, Chief Engr.. Anzan Steel Works, South Manchuria RY. Co., Anzan, South Manchuria. China. (Via Dairen). Adair, Arthur C, Valuation Engr., Internal Revenue. Treasury Dept.. . .Washington, D. C. Adami. Arthur E., Prof. of Min. Engrg., Montana State School of Mines. Butte, Mont. Adami. Charles J.. Min. Engr., Gen&apos;l Mnr., St. Jos~ph Lead Co.. ....... .Bonne Terre, Mo. Adama, C. W., Pres. Adams Pacific Corp .I66 Montgomery St., San Francisco. Cal. Adams. Cuyler .Dee rwood, Minn. Adams, David T, 514 Wrigley Bldg.. Chicago, Ill. ADAMS, FRANK DAWSON, Logan Prof. of Geology and Dean, Faculty of Applied Science. McGiU Univ., Montreal. Que.. Canada. Adams. Gale L, Research Engr.. General Pet. Corp...Los Angeles. Cal. Adams. George I.. Prof. of Geol. & Mineralogy. Univ. of Alabama. .Tuscalmsa, Ala. Adams. H. H.. Cons. Gml..Room 415, W. T. Waggoner Bldg., Fort Worth. Tex. Adams, Henry, Cons. Min. Engr. . 934 Park Ave., Plainfield, N. J. Adame, Henry H. 285 Madison Ave., New York. N. Y. Adams. Henry Farnum. Engr.. Charge Experimental Work, Inspiration Concentrator. Inspiration Cons. Copper Co.. Box 364, Inspiration. Ariz. Adams, Huntington, Min. Engr, 149 Broadway, New York, N. Y. Adams. Leland D, V.P.. Leslie-California Salt Co., 166 Montgomery St.. San Francisco. Cal. Adams. Louie W.. Illinois Steel Co Gary, Ind. Adama, XL L. Min. Engr.. Old Ben Coal Corp., Mine 12.. Christopher. IU. Adams, Robert M. Robert M. Adam Co. .I201 Fidelity Bldg., Duluth, Minn. Adams. Sidney F.. Geol., Empire Zinc Co .Gilman, Colo. tAdams, Waldo Peck..P ittsfield, Pike Co.. Ill. Addams. Charles 1. Min. Engr.. Bo x 663. Phoenix, Ariz. Addicka, Lawrence. Cons. Enar..... .61 Maiden Lane. New York. N. Y. Addison, Herbert, V.P.. Big Horn Collieries Co ,412 Colorado Bldg., Denver, Colo. Adkemn. J. Carson. Min. Engr.. HY Grade Manganese Co., Inc..Woodstock, Va. Ady. Joseph Wesley. Jr.. Min. Enar., 314 Mining Exchange Blda., Colorado Springs, Colo. Affelder. William Lewis. Asst. to Pres., Hillman Coal & Coke Co. & Allied Companies. 2006 First National Bank Bldg.. Pittshurgh, Pa. Ameck, B. F.. Pres.. Universal Portland Cement Co. .. .210 South La Salle St., Chicago. Ill. Agabeg, Edgar C.. Cons. Min. Engr.. ..... .Evelyn Lodae. Asansol, E. I. R. Bengal, India. tAsar. William M.. Aest. Prof. of Geol.. Kirtland Hall, Yale Univ.. ... .New Haven, Conn. Agaeniz. Rodolphe L, Pres.. Calumet & Hecla Consolidated Copper Co. ...... .Boston, Mass. tAgens, William Holmes. District Mgr.. Traylor Engrg. & Mfg. Co., 362 I. W. Hellman Blda.. Los Aneeles. Cal.

Jan 1, 1928

By J. O. Brittain, N. R. Adsit

It has been suggested that grain boundary motion during creep is a two-stage process, i.e., sliding followed by migration. Wienbergl found alternate sliding and migration of aluminum tricrystals tested in shear. He concluded that curves of grain boundary sliding (G. B. S.) vs time were not reproducible from specimen to specimen. Couling and Roberts,&apos; who worked on polycrystalline magnesium, found that sliding and migration were interdependent. They were able to correlate the amount of sliding with the number of sliding-migration cycles, i.e., the amount of migration observed metallographically. Rhines, Bond, and Kissel found that the curves of grain boundary sliding vs time were spasmodic but they did not find any migration of the boundary. Some recent creep tests on bicrystals of high-purity zinc (99.99 pct) help to elucidate the role of grain boundary migration in the G. B. S. process. The experimental technique and apparatus are described elsewhere. The tests were conducted in vacuum or a protective atmosphere of argon. All specimens were stressed in simple shear along

Jan 1, 1961

Executive Committee, Board of Directors Howard C Pyle, Chairman, J L Gillson, Vice¬Chairman, A W Thornton, Elmer A Jones, Augustus B Kinzel Finance Committee, Board of Directors J S Vanick, Chairman, John P Hammond, J W Woomer Investments Gail F Moulton, &apos;60, Chairman, Andrew Fletcher, &apos;62, John M Lovejoy, &apos;61, C R Dodson, ex off as AIME Treasurer, J S Vanick, ex off as Chairman of Finance Committee Endowment Andrew Fletcher, Chairman, N G Alford, W J Coulter, Harold Decker, J V N Dorr, R B Gilmore, J B Haffner, Kenneth Hill, 0 H Johnson, J D MacKenzie, D H McLaughlin, J R McMillan, W S Morris, L F Reinartz, H DeWitt Smith, Wilfred Sykes, J R Suman, C E Weed Honorary Memberships C E Reistle, Jr, &apos;60, Chairman, Grover J Holt, &apos;61, Augustus B Kmzel, &apos;62, (ex off as Past Presidents of AIME) M L Haider, &apos;60, D H McLaughlin, &apos;61, John M Lovejoy, &apos;62, L F Reinartz, &apos;63, Howard C Pyle, ex off as President of AIME

Jan 1, 1959

Meeting of April 24, 1914.-President Thayer announced the appointment of the Committee on Safety and Sanitation. The Committee on Nominations for officers for 1915 was appointed, as follows: William J. Cox, Chairman; H. Poster Bain, Joseph Daniels, Charles E. Mills, R. V. Norris, E. Gybbon Spilsbury, and Herbert A. Wheeler. The request of twenty residents of Salt Lake City and vicinity for permission to establish the Utah-Nevada Local Section was granted and R. C. Gemmell was appointed Chairman of the Committee on Organization. The following resolution was adopted: Resolved: That under authority of Article V, Section 7, of the Constitution, a special Committee be and hereby is appointed, to consist of the President and six other members of the Institute, to be named by him, Who shall be authorized to appear before the proper authorities at Washington and urge that Mining Engineers be appointed upon the proposed Commission for revision of the Federal Mining Laws. Further Resolved: That the activities of this special Committee be restricted to the authority given in this resolution.

Jan 6, 1914

By Homer W. Riley

ANTHRACITE SMALL power-driven, toothed, cast-iron rolls were used first to break anthracite in 1844. Prior to that time, men with hammers, who stood on perforated cast-iron plates, broke the large lumps into commercial sizes. In order to convert run-of-mine into the various sizes required by the anthracite industry, about 20 million tons must be broken, annually, into smaller sizes. This phase of anthracite preparation is of major importance, because the degradation accompanying reduction in coal sizes should be kept at a minimum. The exclusive use of toothed rolls for that purpose indicates that comminution by rolls is the best solution of the problem. Many improvements have been made in tooth design, but the most important was a reduction of the peripheral speed of the rolls from 1000 to 300 ft. per minute. The higher speed was based upon and approximated the velocity of a falling piece of coal when it entered the rolls, Exhaustive roll tests at the slower speed showed that the same size reduction could be affected with less degradation. The adoption, therefore, of slow-speed, compound geared rolls, especially for breaking the larger sizes, became quite general after 1912. A high-speed roll is shown in Fig. 1 and a slow-speed roll in Fig. 2. Anthracite Crushing Problems.-Crushing anthracite presents the problem of selecting a series of rolls that will produce the greatest percentage of the prepared sizes of nut and over. The size distributions to be expected are shown in Table 1. Coal breaking and crushing practices in anthracite breakers involve the use of equipment for comminuting the following classes of material: 1. Run-of-mine-plus 6 ½ -in. coal. 2. Sized coal-steamboat, broken, egg, stove, nut, and pea. 3. Flat coal--coal that is flat and hence not suitable for the market. 4. Bone--a piece of laminated coal and slate, crushed for the purpose of reclaiming the coal. 5. Breaker refuse, reduced to a size suitable for flushing into a mine for back-filling purposes.

Jan 1, 1950

By A. A. Smith, J. S. Smart

THe elements silver, cadmium, tin, antimony and tellurium either are found as impurities in commercial coppers or are intentionally added to produce coppers for special uses. When present in small quantities, each of these metals exerts a significant effect on the properties of copper, but despite considerable experience and investigation much remains to be learned about their specific behavior. The presence of extraneous elements, particularly oxygen, complicates the study of individual additions of impurities in the range o to 0.05 per cent, and the use of high-purity copper has been found extremely helpful in circumventing these difficulties. It has also been found that individual behavior can be satisfactorilv determined from measurements of two commercially important properties, conductivity and softening temperature, according to methods that have been described previously.1,2 Data of this type, obtained in the course of a general investigation of the effects of impurities on the properties of both oxygen-bearing 2nd oxygen-free copper are presented herewith. All samples except those containing cadmium were prepared as 3/8-in. continuously cast oxygen-free rod from pure copper and weighed amounts of a similarly synthesized master alloy. Composition was checked by chemical methods, which in every case verified the calculated analyses. Test wires were cold-drawn one B, and S. number per pass on a string-up machine using four 30-min. 600°C. anneals at 0.3125, 0.257, 0.204 and 0.162 in. and a final cold reduction of 75 per cent to 0.081 in. Some oxygen-bearing samples were produced directly from the 3/8-in. oxygen-free rods by diffusion from a surface scale at 850°C. and drawn to size as listed above, but most of the alloys were remelted in pure graphite and cast through air into a I-in. round mold. The slugs were then hot-rolled to 5/16 in., drawn to 0.162 in., annealed as listed above, and drawn to 0.081 inch. Conductivity wires were annealed for I hr. at 100°C. intervals between 300&apos; and 800°F., using a hydrogen atmosphere for oxygen-free samples and purified nitrogen for the oxygen-bearing type. All samples were quenched from the annealing temperature in 10 per cent H²S04 and conductivity was measured on a Hoopes bridge that had been checked against a Kelvin bridge. The softening temperatures represent the half-hard stage of the annealing curve as determined by a standard procedure.&apos; Effect of Silver Numerous excellent studies of the argentiferous coppers are found in the literature, and these have been adequately

Jan 1, 1943

By A. A. Smith, J. S. Smart

THe elements silver, cadmium, tin, antimony and tellurium either are found as impurities in commercial coppers or are intentionally added to produce coppers for special uses. When present in small quantities, each of these metals exerts a significant effect on the properties of copper, but despite considerable experience and investigation much remains to be learned about their specific behavior. The presence of extraneous elements, particularly oxygen, complicates the study of individual additions of impurities in the range o to 0.05 per cent, and the use of high-purity copper has been found extremely helpful in circumventing these difficulties. It has also been found that individual behavior can be satisfactorilv determined from measurements of two commercially important properties, conductivity and softening temperature, according to methods that have been described previously.1,2 Data of this type, obtained in the course of a general investigation of the effects of impurities on the properties of both oxygen-bearing 2nd oxygen-free copper are presented herewith. All samples except those containing cadmium were prepared as 3/8-in. continuously cast oxygen-free rod from pure copper and weighed amounts of a similarly synthesized master alloy. Composition was checked by chemical methods, which in every case verified the calculated analyses. Test wires were cold-drawn one B, and S. number per pass on a string-up machine using four 30-min. 600°C. anneals at 0.3125, 0.257, 0.204 and 0.162 in. and a final cold reduction of 75 per cent to 0.081 in. Some oxygen-bearing samples were produced directly from the 3/8-in. oxygen-free rods by diffusion from a surface scale at 850°C. and drawn to size as listed above, but most of the alloys were remelted in pure graphite and cast through air into a I-in. round mold. The slugs were then hot-rolled to 5/16 in., drawn to 0.162 in., annealed as listed above, and drawn to 0.081 inch. Conductivity wires were annealed for I hr. at 100°C. intervals between 300&apos; and 800°F., using a hydrogen atmosphere for oxygen-free samples and purified nitrogen for the oxygen-bearing type. All samples were quenched from the annealing temperature in 10 per cent H²S04 and conductivity was measured on a Hoopes bridge that had been checked against a Kelvin bridge. The softening temperatures represent the half-hard stage of the annealing curve as determined by a standard procedure.&apos; Effect of Silver Numerous excellent studies of the argentiferous coppers are found in the literature, and these have been adequately

Jan 1, 1943

By H. E. Gross

A plausrsle method of drilling beyond the continental shelves is set forth with limitations of the method. The continental shelves comprise the water-covered portions of land masses out to 600 ft. of water, or roo fathoms. The problems and possibilities of drilling beyond this depth are discussed in this paper. Introduction Much attention is being given the problem of developing petroleum beneath the open sea. Geophysical surveys have been made 26 miles offshore1 from the continental United States, and onco offshore ownership is established it is likely that there will be drilling for oil on the continental shelves. More than two years ago the author presented the means for drilling in deep water.2 at the fall meeting of the Petroleum Division of the AIME at Los Angeles. His concepts then were based on the use of rigid foundations suitable for drilling in water up to 600 ft. deep. The present paper suggests a method for drilling in deeper water. Possibilities and Problems of Drilling beyond the continental shelves It being conceded that because restricted deep-water portions of the hydrosphere might contain oil in commercial quantities, and that at any rate it is pertinent to know more of the nature of the lithosphere beneath the hydrosphere, the possibilities and problems of drilling beyond the continental shelves should be set forth. Drilling in open water would offer few if any advantages over drilling on land. These are: 1. The ocean transportation is available to deep-water drilling sites, and extensive pipe lines and roads are unnecessary. 2. Refinery facilities and markets perhaps are established on the near-by shore where adjacent fields on land are nearing depletion. 3. There is freedom from jungle pests and tropical diseases. 4. Competitive drilling is less likely. 5. Extensive areas attractive for development arc not yet under lease or concession. Disadvantages are great and numerous: 1. Storm hazards from wind and wave. 2. Expensive foundations, either rigid or floating. 3. Shutdown times because of weather. 4. Marine Regulations of Federal Bureaus in addition to customary regulations on land. 5. Frequent difficulty in moving men and materials to and from drilling platforms. 6. Extra precautions required in open sea. For drilling in water more than 500 or 600 ft. deep, rigid foundations2 become too costly, and floating foundations must be used, and they must meet the following requirements:

Jan 1, 1947

By H. E. Gross

A plausrsle method of drilling beyond the continental shelves is set forth with limitations of the method. The continental shelves comprise the water-covered portions of land masses out to 600 ft. of water, or roo fathoms. The problems and possibilities of drilling beyond this depth are discussed in this paper. Introduction Much attention is being given the problem of developing petroleum beneath the open sea. Geophysical surveys have been made 26 miles offshore1 from the continental United States, and onco offshore ownership is established it is likely that there will be drilling for oil on the continental shelves. More than two years ago the author presented the means for drilling in deep water.2 at the fall meeting of the Petroleum Division of the AIME at Los Angeles. His concepts then were based on the use of rigid foundations suitable for drilling in water up to 600 ft. deep. The present paper suggests a method for drilling in deeper water. Possibilities and Problems of Drilling beyond the continental shelves It being conceded that because restricted deep-water portions of the hydrosphere might contain oil in commercial quantities, and that at any rate it is pertinent to know more of the nature of the lithosphere beneath the hydrosphere, the possibilities and problems of drilling beyond the continental shelves should be set forth. Drilling in open water would offer few if any advantages over drilling on land. These are: 1. The ocean transportation is available to deep-water drilling sites, and extensive pipe lines and roads are unnecessary. 2. Refinery facilities and markets perhaps are established on the near-by shore where adjacent fields on land are nearing depletion. 3. There is freedom from jungle pests and tropical diseases. 4. Competitive drilling is less likely. 5. Extensive areas attractive for development arc not yet under lease or concession. Disadvantages are great and numerous: 1. Storm hazards from wind and wave. 2. Expensive foundations, either rigid or floating. 3. Shutdown times because of weather. 4. Marine Regulations of Federal Bureaus in addition to customary regulations on land. 5. Frequent difficulty in moving men and materials to and from drilling platforms. 6. Extra precautions required in open sea. For drilling in water more than 500 or 600 ft. deep, rigid foundations2 become too costly, and floating foundations must be used, and they must meet the following requirements:

Jan 1, 1947

By John Birkinbine

Four meetings of the Institute have been held in the anthracite coal-fields of Pennsylvania, and excursioris into the district, in connection with meetings elsewhere, have familiarized our members with

Jan 1, 1892

By Thomas E. Leontis

INTRODUCTION THE importance of magnesium alloys in the manufacture of aircraft engines has been realized for many years. A concentrated effort has been exerted in the laboratories of the Dow Chemical Co. to develop magnesium-base alloys with improved properties at elevated temperatures whereby greater advantage can be taken of the inherent lightness of these materials. In an earlier publication,1 attention was called to the superior tensile properties and resistance to creep of cerium-containing magnesium alloys at temperatures up to 700°F. More recently, additional data on magnesium-cerium alloys have been furnished by Murphy and Payne.2 The present paper deals with the mechanical properties of sand-cast magnesium alloys containing zinc, at temperatures up to 500°F. The study includes binary Mg-Zn† alloys containing up to 10 pct zinc and several ternary and some polynary alloys based on the Mg-1Zn,†Mg-3Zn, Mg-4.4Zn, Mg-6Zn, and Mg-10Zn binaries. The compositional variation in the tensile properties, hardness, and creep at room and elevated temperatures, and in the electrical conductivity at room temperature has been determined. The results of these tests show that many zinc-containing magnesium alloys exhibit resistance to creep at elevated temperatures significantly higher than that of present commercial magnesium alloys, but lower than that of alloys of the magnesium-cerium type. In addition, they have high tensile properties at room and elevated temperatures and high conductivity. This combination of mechanical properties and conductivity indicates that these alloys should be given serious consideration for commercial applications involving exposure to temperatures higher than those to which present commercial magnesium alloys can be taken safely. LITERATURE The properties of sand-cast magnesium alloys containing zinc as a principal alloying element have not been investigated very extensively, especially at elevated temperatures. The following remarks, which are confined to sand-cast alloys, will serve as a summary of the most important references on this phase of magnesium metallurgy. The first recorded determination of the tensile strength of binary Mg-Zn alloys as a function of zinc content was reported by Aitchison.3 Similar studies, including the measurement of elongation and hardness, have been performed by Gann and Winston,4 Dumas and Rockaert,5 Haughton and Prytherch,6 and by Spitaler, the last being reported by Beck.7 A slight superiority in the tensile strength of chillcast Mg + 8 Zn alloy over the sand-cast alloy was noted by Maybrey 8 That alloys of magnesium containing 5 to 12 pct zinc

Jan 1, 1948

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Jan 3, 1919