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By L. D. Frink

Those actively interested in mining are fully aware of the ever-increasing difficulty of making conditions such that efficient work can be done in underground openings, especially as higher rock temperatures are encountered in depth. This is also true where an effort is being made to cut down the burden of overhead expense by working headings 24 hr. in a day if blasting is done as often as is possible in that time. That the conditions resulting from both these causes have driven the native-born Americans from the mines and that their places have been taken by less efficient foreigners is a fact that we must all admit. The great war now being fought in Europe and the educational qualification clause written into our immigration law by the last Congress will probably limit very materially the supply of labor, such as we are now using in our mines, and will force upon mine operators the necessity of making this work appeal again to Americans. Metal tubing, with blower or exhaust fans, has long been used in supplying air to dead ends where natural ventilation is impossible, or in driving the smoke from such places, or in doing both, as the need might be. Here in Butte we have now come to use canvas tubing very extensively and find that it has many advantages not possessed by the metal. The use of flexible tubing is not new, but it has not been generally used in mining operations. Recent improvements, however, in the canvas itself and in the jointing of sections and manner of suspension have so increased its usefulness that it promises to add much to the efficiency of mining. There is now on the market a product that is impervious to air, is fireproof, and has a system of jointing which permits it to be put up or taken down in a few seconds. In this article an effort will be made to explain the manner in which canvas tubing is being used in the North Butte company's operations at Butte, Mont. The accompanying photographs will, I hope, help make clear what may be done with this material.

Jan 1, 1918

Connecticut Geological and Natural History Survey, P O Box 1106, New Haven, Conn W. E Britton, Superintendent. A complete list of Bulletins available will be sent upon request. Address all inquiries for publications to: George S Godard, State Librarian, Hartford, Conn Fifty-one Bulletins have been issued, 15 of which are of particular interest, dealing with the geology of the state, and are available as follows; 4, The clays and clay industries of Connecticut, by G. F Loughlin (1905), 35 cents; 8, Bibliography of Connecticut geology, by H E Gregory (1907), 20 cents, 13, The lithology of Connecticut, by J Barrell and G. F Loughlin (1910), 45 cents, 18, Triassic fishes of Connecticut, by C. R Eastman (1911), 30 cents, 23, Central Connecticut in the geologic past, by J. Barrell (1915), 20 cents, 24, Triassic life of the Connecticut Valley, by R Lull (1915), 70 cents, 29, The Quaternary geology of the New Haven region, Connecticut, by F. Ward (1920), 60 cents, 30, Drainage modifications, and glaciation in the Danbury region, Connecticut, by Ruth S. Harvey (1920), 55 cents, 33, Geology of the Stonington region, Connecticut, by L H. Martin (1925), 60 cents, 40, The geology of the Shepaug Aqueduct Tunnel, Litchfield County, Connecticut, by W M. Agar (1927), 50 cents; 41, Guide to the geology of Middletown, Connecticut, and Vicinity, by W. N Rice and W. G Foye (1927), $1, 44, Report on the water resources of Connecticut, by R. H Suttee (1928), $1, 46, The physical history of the Connecticut shoreline, by H S Sharp (1929), 75 cents; 47, The glacial geology of Connecticut, by R F. Flint (1929), $2, 51, Minerals of Connecticut, by J F Schairer (1932), 75 cents Bulletin 51 explains the physical and chemical properties of minerals, their classification, and describes more than 100 common minerals found in Connecticut. A bibliography is included The Survey gratuitously distributes all its Bulletins to state residents, scientific institutions, etc. Prices quoted are to private citizens of other states

Jan 1, 1933

By Michael S. Roscoe

In order to more accurately predict longwall surface subsidence over the Pittsburgh No. 8 Coal in Eastern Ohio, North American Coal Corporation's Quarto Mining Company undertook or participated in several subsidence studies. Due to the changing roof geology and rapid variations in the amount of cover two separate areas were investigated at two different mines to determine the subsidence response if any to these changes. Data generated from these studies were compared with NCB derived,data for accuracy and then used to predict subsidence under houses, gas lines and other critical man made structures. The following report summarizes the results of these studies as well as the subsidence case histories of gas lines, transmission towers, houses and water wells. Problems that were encountered during both phases of this process (investigation and subsequent application) are also included.

By L. C. Uren

Field studies and laboratory research have established the fact that the expulsive force which drives petroleum into wells, from the reservoir sands in which it is stored by nature, is primarly an expression of the energy latent within compressed natural gas dissolved or occluded in, or otherwise associated with the oil. Each barrel of oil produced is forced into the recovery well by the expansive energy of a certain volume of compressed gas, originally stored with the oil in the pores of the reservoir rock; and each cubic foot of gas so produced with the oil and expanded to atmospheric pressure reduces by so much the total natural energy available for oil expulsion. This relationship between the volumes of gas and oil produced has seemed so important that petroleum production technolo-gists have come to regard the "gas-oil ratio," or the "gas factor" as it has been more conveniently termed, as a measure of oil-production efficiency. Different methods of oil recovery and production devices are now Com pared on this basis and estimates of ultimate recovery obtainable through their use are considered by many to be inversely proportional to the values of their respective gas factors. The writer has been among those who have given support to a widcspread movement toward a proper recognition of the significance of the gas factor as a guide in the control of producing oil wells, and does not wish to oppose its more extended application. It seems necessary, how-cvcr, in view of the almost elemental faith with which the principle of the gas factor has been received in many quarters, to point out that it is a most complex factor, and one which cannot be regarded as an absolute index of production efficiency without due regard to other contributing factors by which it is influenced to an important degree. Variables Influencing Gas Factor The mere recording of a low gas factor, obtained through the use of some method or device, does not necessarily imply efficient oil production; and conversely, a high gas factor does not always signify inefficient recov-

Jan 1, 1928

Executive HOWARD N. EAVENSON, Chairman FREDERICK M. BECKET EDGAR RICKARD ERLE V. DAVELER WILLIAM WRAITH Finance HENRY KRUMB, Chairman PAUL I). MERICA J. V. W. REYNDERS H. G. MOULTON, Consultant Admissions JOHN M. LOVEJOY, Chairman GEORGE D. BARRON DONALD M. LIDDELL ELI T. CONNER WILLIAM W. LYNCH Alternates WM. H. BASSETT, JR. L. B. LINDEMUTH W. A. SINSHEIMER

Jan 1, 1934

Report of Secretary TO THE BOARD OF DIRECTORS OF AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen -I have the honor to present the following report for the calendar year 1920 The activities which-seem to call for special com¬ment are THE NEW FORM OF MAGAZINE MINING AND METALLURGY appeared every month during the calendar year and has been developed until it contains some ten departments It has brought forth more commendatory letters than have been received at headquarters on any other subject throughout the year Less than a dozen letters unfavorable to the change have been received, and the indications are that the magazine has met a want deeply felt, especially by members distant from headquarters The technical papers printed by the Institute are published in abstract in the magazine and opportunity is given to members who desire them to receive full copies of any or all papers published The Bound Volumes, as usual, contain all the papers in full and discussions thereof FINANCES The greatly increased cost of paper and printing has put a tremendous burden on the Institute's finances, since the dues of $12 per year are only 20 per cent greater than the members paid when the Institute was founded forty-nine years ago This has resulted in a temporary deficit, similar to that encountered by many of our sister engineering societies The fact that our Institute has lower dues and gives more in the way of publications to its members than any other of\the national engineering societies has rendered the situation more difficult for us MEETINGS The Annual Meeting in New York, the Field Meeting in the Lake Superior District, the meeting of the Petroleum and Gas members at St Lours, and of the Institute of Metals Division in Columbus, Ohio, have all been described in full in the magazine

Jan 1, 1923

By AIME AIME

FRANCIS ANDREW THOMSON was born in London, Dec. 21, 1879, coming to the United States by way of British Columbia where he lived until he matriculated at the Colorado School of Mines. When only sixteen he was inducted into the mining industry as apprentice assayer and millman at the Victoria Metallurgical Works. Following his training at Golden he had more practical mining and milling experience at several properties in the West, and studied a little as well at the Royal School of Mines, in London, and at the Ecole des Mines, in Paris.

Jan 1, 1939

By G. Osuch, G. Derge, G. M. Pound

Using a new dternating-current potentiometer circuit and a specially designed four-terminal cell, the specific conductance of molten Cu2S-FeS mattes was measured as a function of temperature, from the liquidus to 1500°C, over the complete range of composition. The high conductivities, about 1500 ohm-I cm-l for FeS and 100 ohm-l cm-l for Cu,S, indicate that the conduction is electronic rather than ionic. Molten FeS has a negative temperature coefficient of specific conductance, resembling metallic conduction. Molten Cu,S has a positive temperature coefficient, resembling semiconduction. The binary roughly follows an additive rule of mixtures with respect to both magnitude and temperature coefficient of specific conductance. Metallic bonding in the liquid is postulated to explain these phenomena. MUCH has been learned in the past about the nature of liquids and the ionic or molecular species in solution by means of electrical measurements. Thus, dielectric constants','2 have given information about molecular liquids such as water and benzene. Measurements of dielectric constant usually are impossible in electrically conducting liquids, such as aqueous solutions of ionic salts and molten ionic salts. However, measurements of electrical conductance and ionic transference have provided much knowledge about the latter systems.a-" In recent years, the ionic nature of certain molten metallurgical slags has been established by Derge and Martin7 through electrical conductance and electrolysis measurements. Chipman, Inouye, and Tom-linsonq ave studied the electrical conductance of molten FeO and report a high specific conductance of about 200 ohm-' cm-' (compared with 4 ohm" cm-' for an ordinary ionic liquid such as molten NaCl) and a positive temperature coefficient of conductance. They interpret these results in terms of p-type semiconduction by analogy to the situation in solid FeO.Y imnad and Derge" have studied cell efficiency in the electrolysis of molten FeO-SiO, systems and conclude that ordinary ionic conductance increases with SiO, content. Very recently, interest has been revived in the electrical conductance of liquid metals and liquid metallic solutions. Scala and Robertson1' report a close resemblance between the liquid and solid states with respect to thermal, structural, and compositional relationships. Molten sulphides have not received a great deal of attention. Bornemann and von Rauschenplat" measured the specific conductance of molten Cu2S as a function of temperature with a four-terminal cell using direct current. A high specific conductance and a positive temperature coefficient were found in that investigation." Using a two-electrode apparatus, Savelsberg" electrolyzed various molten sulphide mixtures. He concluded that pure molten Cu,S and FeS were electronic conductors but that the mixtures exhibited some ionic conduction. In the present investigation, the specific conductance of the industrially important Cu-Fe sulphide mattes was measured as a function of temperature and composition in order to investigate the mode of electrical conduction and the structure of these molten mattes. An alternating-current circuit was used to eliminate the effect of any possible electrode reactions. Apparatus The Conductance Cell: Due to the high specific conductance of the systems studied (10' to 10" ohm-' cm-'), the classical two-terminal cell and Wheat-stone bridge apparatus could not be used. A four-terminal cell was developed in order to eliminate lead resistance, and an ac potentiometer circuit was designed to give rapid and sufficiently accurate measurements of the cell resistance. A diagram of the conductivity cell is given in Fig. 1. The molten matte is contained in a dense alundum crucible, and spectrographic graphite rods that dip into the molten matte serve as the four conductance terminals. Two of the graphite rods on opposite sides of the cell serve as current-carrying leads, and the other two graphite rods are null-current probes that detect the potential drop across the cell. These graphite rods are contained in silica tubes, and the lower constricted portions of the two silica tubes define the column of liquid whose electrical resistance is being measured. The electrical resistance of the broad ex-

Jan 1, 1956

By G. M. Schwartz, J. N. Gundersen

John W. Gruner (Professor Emeritus, College of Science, Literature, and the Arts, Dept. of Geology, University of Minnesota, Minneapolis) — It is surprising that two men as well acquainted with the taconite rocks of the Mesabi District as Drs. J. N. Gundersen and G. M. Schwartz should have concluded that the taconite of the Eastern Mesabi before the intrusion of the Duluth gabbro consisted largely of quartz and magnetite. These minerals were "locally reconstituted" into "a wide variety of silicate mineral assemblages" by the gabbro. It is well known, of course, that the silicate mineralogy of the Eastern Mesabi ('about 14 miles in length) is quite different from that of the Main Mesabi which is over 60 miles long. The change from one to the other is abrupt and cannot be attributed to any other cause than the thermal effects of the gabbro. Are we to assume or believe that the taconite of the Eastern Mesabi was radically different from that of the Main range before the gabbro metamorphosed it?

Jan 1, 1962

By J. Hunter

LouisiaNa ranks fifth among the oil-producing states. In 1941 the state-wide production was slightly in excess of 118,000,000 bbl. of crude oil and conden-sate—an increase of 15,000,000 bbl. over the total production for the year 1940. During 1941, south Louisiana produced approximately 90,900,000 bbl. of oil, while north Louisiana produced approximately 27,000,000. South Louisiana, therefore, produced about 3¼ times more oil than north Louisiana. During the past year, 574,800,000 M cu. ft. of natural and casinghead gas were produced in Louisiana; thus 1941 gas production exceeded the 1940 production by 104,900,000 M cu. feet. Completion records for the year 1941 show that 1512 wells were completed in or adjoining producing fields. These wells, which were drilled to extend known producing areas or were located within producing areas, are not considered as wildcat wells. Of the total number of field wells drilled, 1152 wells found production; the remaining 360 were junked or dry and abandoned. This means that 76 per cent of the wells drilled were successful. Considering the precarious nature of oil-field development, this percentage of new producing wells is exceedingly satisfactory. Of the total number of field welis com-pleted as producers, approximately 86 wells found new and distinct producing sands. During the past year, 30 new fields were found. Four parishes—namely, Caldwell, Catahoula, Orleans, and Natchitoches— entered the ranks of oil-and-gas-producing parishes in the state during that period. This brings the total number of oil-and-gas-producing parishes in the state up to 48. Thus, 75 per cent of the parishes in Louisiana now contain one or more oil and/or gas fields. Although sufficient data are not available to list the addition reserves found in Louisiana during 1941, it is felt that such reserves undoubtedly exceed twice the total production for that year, or at least 200 million barrels. In reserves, therefore, Louisiana ranks third among the various oil-producing states. South Louisiana Although 16 new fields were found in south Louisiana, the outstanding developments in that part of the state were not limited to new discoveries. In fact, most of the increase in reserve in that area has been most consistently accumulated through extensions of known producing sands and through the finding of new sands in already productive fields, especially at depths below the presently producing sands. Since data concerning most of the new extensions and sands are too extensive for discussion here, the more important developments arc briefly outlined below: Abbeville, Vermilion Parish.—Production extended ½ mile to the west. Anse La Butte, St. Martin Parish.—New oil sand discovered at 9400 ft., thus extending production to east flank. West flank defined by dry holes. Barataria, Jefferson Parish.—New oil sand discovered on east side of field at 7620 ft. New

Jan 1, 1942

By J. Hunter

LouisiaNa ranks fifth among the oil-producing states. In 1941 the state-wide production was slightly in excess of 118,000,000 bbl. of crude oil and conden-sate—an increase of 15,000,000 bbl. over the total production for the year 1940. During 1941, south Louisiana produced approximately 90,900,000 bbl. of oil, while north Louisiana produced approximately 27,000,000. South Louisiana, therefore, produced about 3¼ times more oil than north Louisiana. During the past year, 574,800,000 M cu. ft. of natural and casinghead gas were produced in Louisiana; thus 1941 gas production exceeded the 1940 production by 104,900,000 M cu. feet. Completion records for the year 1941 show that 1512 wells were completed in or adjoining producing fields. These wells, which were drilled to extend known producing areas or were located within producing areas, are not considered as wildcat wells. Of the total number of field wells drilled, 1152 wells found production; the remaining 360 were junked or dry and abandoned. This means that 76 per cent of the wells drilled were successful. Considering the precarious nature of oil-field development, this percentage of new producing wells is exceedingly satisfactory. Of the total number of field welis com-pleted as producers, approximately 86 wells found new and distinct producing sands. During the past year, 30 new fields were found. Four parishes—namely, Caldwell, Catahoula, Orleans, and Natchitoches— entered the ranks of oil-and-gas-producing parishes in the state during that period. This brings the total number of oil-and-gas-producing parishes in the state up to 48. Thus, 75 per cent of the parishes in Louisiana now contain one or more oil and/or gas fields. Although sufficient data are not available to list the addition reserves found in Louisiana during 1941, it is felt that such reserves undoubtedly exceed twice the total production for that year, or at least 200 million barrels. In reserves, therefore, Louisiana ranks third among the various oil-producing states. South Louisiana Although 16 new fields were found in south Louisiana, the outstanding developments in that part of the state were not limited to new discoveries. In fact, most of the increase in reserve in that area has been most consistently accumulated through extensions of known producing sands and through the finding of new sands in already productive fields, especially at depths below the presently producing sands. Since data concerning most of the new extensions and sands are too extensive for discussion here, the more important developments arc briefly outlined below: Abbeville, Vermilion Parish.—Production extended ½ mile to the west. Anse La Butte, St. Martin Parish.—New oil sand discovered at 9400 ft., thus extending production to east flank. West flank defined by dry holes. Barataria, Jefferson Parish.—New oil sand discovered on east side of field at 7620 ft. New

Jan 1, 1942

By John T. Thorndyke

MOST important of the naturalcalcium silicates is the meta¬silicate, CaSi03, known as wollastonite, after W. H. Wollaston. A large deposit of this mineral was dis¬covered some seven years ago near Code Siding, Rademacher mining dis¬trict, Kern County, Calif., the deposit being some 7500 ft. long and of an average width of 300 ft. It consists of a series of small domes striking north¬erly and southerly and with a dip of 81 ° to the south. This deposit was opened up by a series of small quarries showing a potential tonnage of 12,000,¬000 tons, allowing of cheap mining and transportation, the Southern Pa¬cific R.R. spur track being one mile north of the workings. Numerous sam¬ples taken from different points on the deposit, tested by Mr. Brinker, of the California Testing Laboratories, Los Angeles, showed an average as fol¬lows: Per Cent Silica (SiO2) 47.12 Lime (CaO) 41.72 Magnesia (MgO) 2.72 Alkalies (R,0) Trace Iron (Fe.,O,) 1.60 whereas the theoretical composition of of wollastonite, as given by William Shirley Bayley, is as follows: Silica 51.75 Lime 45.25 The tonnage and purity of this de¬posit led to investigations into its com¬mercial development. Early work es¬tablished the fact that wollastonite was ideal for the manufacture of a tough, almost unbreakable, glass similar to Pyrex. It also established the fact that wollastonite was particularly adapted for use in the manufacture of mineral wool, towards which further research was then directed. Briefly, the prin¬cipal advantages were the substantially unvarying chemical composition of the naturally occurring mineral and its characteristic of being relatively flexi¬ble and highly resilient when fused into a glass. A mineral wool produced therefrom is thus not only of highly uniform composition and color but is most desirable because of the high mechanical strength and length of the individual fibers constituting the wool. It is well known that mineral wool may be prepared by melting a suitable charge of raw material and then intro¬ducing a stream of a suitable fluid, such as air or steam, into a stream of the molten raw material. By this means the molten material is blown into threads or fibers, which are collected in a suitable chamber similar to a tun¬nel, from which they are removed from time to time or continuously. Com¬mercial manufacture of mineral wool has been carried on for only about 50 years, but volcanoes, specifically Kilauea in the Hawaiian Islands, have

Jan 1, 1936

The election of the following officers of the Council for the fiscal year 1919-1920, was confirmed by the Council on June 12th, 1919. President, S. E. Doane; vice-president, Wm. J. Clark; general secretary, Clarence L. Law; treasurer, L. B. Marks; directors, E. C. Crittenden, F. E. Cady, R. B. Ely. The membership of the Council for 1919-1920 will therefore be as follows: S. E. Doane, G. H. Stickney, George A. Hoadley, Wm. J. Clark, H. A. Horror, Otis L. Johnson, H. K. Morrison, Clarence L. Law, L. B. Marks, Adolph Hertz, S. C. Roger, P. S. Young, John C. D. Clark, Evan J. Edwards, James J. Kirk, E. C. Crittenden, F. E. Cady, R. B. Ely.

Jan 7, 1919

By W. F. Boericke

INTRODUCTION THE Wisconsin zinc district, or the Upper Mississippi lead. and zinc district as it is also termed, lies in the southwestern corner of Wisconsin, and embraces adjacent portions of Illinois and Iowa. It includes Iowa, Grant, and Lafayette counties in Wisconsin, and Jo Davies county in Illinois. In Iowa, Dubuque formerly produced considerable lead, but there has been little mining there in recent years. The map, Fig. 1, shows the entire district, with roads, railways, streams, and the various towns, or "camps," around Which the mines. are clustered. The hatchwork indicates the areas iii which lead and zinc have been mined. The district is about 60 mi. (96 km.) north and south and about 40 mi. (64 km.) east and west. Not all of the territory is mineral bearing, and there are considerable areas that are believed to be barren. The grouping of the mines is patchy and irregular, though certain broad zones of mineralization extend almost the full width of the district, as from Mineral Point west through Mifflin and Livingston, and from Shullsburg west through New Diggings and Hazel Green. It is worth noting that the best mines of the district have, to date, been found within 10 mi. east or west of the fourth principal meridian line, thus lying within a long, narrow, north-and-south belt extending the length of the district. In a field as large as the Wisconsin, which has only within com-paratively recent time been worked intensively for zinc, the. chances are good for, opening new and important orebodies in parts of the district not yet, or insufficiently, prospected. However, the prospecting has been most successful around, or adjacent to, the old lead diggings of nearly a century ago, and the camps that were well known then are still centers of activity. In their order of importance they are: New Diggings, Benton, Mifflin-Livingston, Galena, Linden, Hazel Green, Shullsburg, and Highland.

Jan 8, 1919

By G. R. M. Del Giudice

The term "slime-coating" is not new in the art of flotation; the phenomenon has been observed and described by Taggart;(l)† Taggart, Taylor, and Ince;(2) and by Ince.(3) Notwithstanding that flotation was introduced for the treatment of finely crushed ore, the adverse effects of slimes have been recognized since the earliest days of the process, and the Elmore, Delprat, Potter, and other processes actually specified desliming of the ore prior to treatment. The cause of this trouble has been studied and described by Taggart;(1) Taggart, Taylor, and Ince;(2) Ince;(3) Morrow and Griswold;(4) and by Gaudin and Malozemoff.(5) Old Theory of Slime-coatings At present, so far as published work shows, there seems to be but one theory for the mechanism of slime-coatings. Ince(3) states that they are due to attraction between electrostatic charges of opposite sign on the sulfide and on the slime particles, supporting this theory by migration experiments in the Burton tube. He also used the microscope in conjunction with a glass cell employed by Beans and Eastlack(6) in studying migration, but met with interference from endosmosis. Several attempts have been made in the Department of Mineral Dressing at Columbia University to duplicate Ince's experiments with the Burton tube, but the results have never been convincing. Formation of precipitates which settled through the pulp levels, and evolution of gas at the electrodes, which disturbed the interface between the pulp and the distilled water above it, seriously interfered with observations. However, by use of the migration cell shown in Fig. 1, endosmosis effects and the disturbances due to precipitation and gas evolution were avoided, and distinct and reproducible migrations or absence of migration were observed. The cell was made of bakelite and had platinum electrodes. Objectives were employed which had a working distance of at least three millimeters,1 and the parts of the mounting which came in contact with

Jan 1, 1935

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's reception, the dinner-dance, an informal dance, a smoker, an exhibition of rare minerals and metals, two meetings of the Woman'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 R. Bakish, W. D. Robertson

IN the course of a study of stress corrosion cracking of AuCu,, it was necessary to develop new electropolishing and metallographic etching methods. The techniques are generally useful for Cu-Au alloys, including the AuCu composition in which transformation markings are well delineated. For electropolishing, the only satisfactory electrolyte and procedure that has been found1 has the composition given in Table I. The solution must be vigorously stirred while polishing and the temperature maintained in the range of 55" to 62°C. The electrolyte is very unstable and can be used only for 10 to 15 min after which its color changes and a dark-brown precipitate forms. The polishing time is between 1 and 4 min depending on the initial surface preparation. The use of a hood is recommended to avoid the danger of cyanide gas which may form at one of the electrodes even though the solution is alkaline. The optimum current and voltage conditions for vertical anode and platinum cathode are on the plateau shown in Fig. 1, in which voltage is measured across the cell terminals. At voltages below the plateau, etching of grain boundaries occurs and under some conditions, which have not been clearly defined, octahedral etch figures are observed. For general purpose grain-size determination in polycrystalline alloys, a 3 pct solution of iodine in methyl alcohol is used with excellent results. However, when it is necessary to reveal small orientation differences or concentration gradients in an alloy, the iodine etch is not satisfactory. For this purpose, a highly satisfactory etching procedure was developed during this investigation. It involves the use of the vapor given off by freshly prepared aqua regia. The solution employed is 3HC1 to lHNO, which decomposes in accordance with the reaction HNO, + 3HC1 = NOCl + 2H,O + Cl,. The polished specimen surface is held about 1 to 2 cm above an aqua regia solution for 2 to 10 sec depending on the intensity of the contrast required and the surface is not subsequently washed. The results obtained with a coarse grained cast structure are shown in Fig. 2. Subgrain boundaries in a single crystal and concentration gradients within the boundaries are developed by the same treatment with the results shown in Fig. 3. Obviously, any conclusions regarding structure-dependent properties will be modified by the pronounced heterogeneity, which is not clearly evident when more conventional methods are used. Interesting structural details are also revealed by treatment for 4 hr at 850°C in unpurified tank argon. Fig. 4 shows a pattern characteristic of orientation-dependent oxidation.

Jan 1, 1956

Executive.. CHARLES F. RAND, Chairman. JAMES F. KEMP, JOSEPH W. RICHARDS. ALBERT R. LEDOUX, BENJAMIN B. THAYER. Membership. BENJAMIN B. THAYER, Chairman. WALTER R. INGALLS, JOHN H. JANEWAY, Jr., JOHN D. IRVING, HERMAN A. PROSSER. Finance. EDWARD L, YOUNG, Chairman. KARL EILERS, JAMES GAYLEY. Library. JAMES F. KEMP, Chairman. JOHN HAYS HAMMOND,3 E. GYBBON SPILSBURY,2 ALES. C. HUMPHREYS 4 BRADLEY STOUGHTON.

Jan 7, 1913

Jan 1, 1965

By H. W. Morse

INTRODUCTION THE experimental work on the oxidized copper ore at the New Cornelia mine at Ajo, Ariz., ended on Jan. 12, 1916. On that date final decision was made on the general nature of the process to be used in the 5,000-ton leaching plant, and on many of the details, as far as experience on a40-ton scale could decide them. With the approval of the Board of Directors and the General Manager, John C. Greenway, we have compiled what seem to be the most interesting data on the results obtained during the experimental period. The most important part of the data resulted from the operation of a 1-ton and a 40-ton plant at Ajo. Experimental work on Cornelia oxidized ore dates back to April, 1912, and has been going on nearly continuously since that time. A good many variations from the original idea have been tried, but the process finally decided upon is in principle and in all of its details a simple one. The history of the leaching work on this ore has been brought down to about a year ago in papers presented to this Institute by Stuart Croasdale1 and Dr. L. D. Ricketts.2 The present paper will, therefore, deal principally with the results obtained during the last year of the work.

Jan 9, 1916