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By R. E. Head

Some mixtures of sulphide and oxide ores from the Tintic district in Utah are of a sufficiently good grade to be shipped to the smelter without beneficiation. In mining this type of ore, however, a material tonnage of ore of a similar composition but of lower grade is obtained. It is a question of economics whether such ore should be shipped with a certainty of a small return or concentrated if that would yield a sufficiently increased return to amortize plant construction and upkeep and yield a higher rate of profit than at present. It may be assumed that the tonnage of this borderline ore is constantly increasing and that eventually it will attain such proportions as to justify plans for milling on a relatively large scale. Under existing conditions, the producer of mixed sulphide and oxide ores is not greatly concerned about the physical characteristics of his ore or of its mineralogical complexities, since his contract with the smelter calls for payment on the basis of chemical analysis. When concentration is contemplated an entirely different picture is presented. Percentages of valuable metal content must then be con-sidered in terms of minerals, for it is in the form of minerals that recoveries are made and losses sustained. In describing the performance of a given flotation mill and reagent combination, it may be stated as a generality that a specific percentage recovery of valuable elements is made. Technically, however, the concentrator is really constructed and the reagents are selected to recover the valuable minerals. These considerations must be given prominence in discussing borderline ores from the Tintic district because of their physical characteristics and mineralogical composition. Because of these peculiarities they may be justly termed complex, since their lead, silver, and copper contents are each represented by two or more minerals of different chemical composition and presenting widely divergent physical properties. This paper sets forth the results of a microscopic study of a type of borderline ore from the Tintic district that is now being treated by direct smelting. A

Jan 1, 1939

By D. W. Fuerstenau

THE object of this article is to point out the experimental relationship which exists among contact angle, adsorption density, zeta potential, and flotation rate data. In each of the experiments discussed in this article, the surface properties of quartz, as a function of pH, were measured in solutions to which constant quantities of dodecylammonium acetate were added. Morrow1 and deBruyn2 worked with solutions containing 4.08x10-5 moles per liter, whereas Fuerstenau3 and Seele worked with solutions containing exactly 4x10 moles per liter, but this difference is not significant. The pH of the solutions was regulated with HCI or NaOH in all cases. In each case, the addition of collector was constant, but the concentration of dodecylammonium ions decreased because of the formation of dodecylamine at higher pH values2 Contact Angles: Gaudin and Morrow1 presented data for the contact angle of quartz in solutions containing 4.08x10-5 moles of dodecylammonium acetate per liter between pH 2 and pH 10.15. Using the same captive bubble techniques, the writer measured contact angles on quartz in solutions containing 4x10-5 moles of dodecylammonium acetate per liter at pH values ranging from 9.9 to 13.2. Both sets of data are presented in Fig. 1, in which the contact angle in degrees is plotted as a function of the pH of the solution. From pH 2 to about 8, the contact angle increases slightly with increased pH, but further increase in pH causes a sharp rise in the contact angle to a maximum of about 80º. At pH values above 11.6, the contact angle drops sharply, reaching zero by pH 12.6.

Jan 12, 1957

Reports from the Geological Survey, Department of the Interior, indicate that although considerable drilling has been clone in the state of Utah, no oil has been produced in commercial quantities. Sandstone saturated with asphalt and other hydrocarbon compounds and small showings of oil in wells at several places suggest that oil may be found, in commercial quantities where the rocks are favorable for oil accumulation. In some places the structure appears to be very favorable for the storage of oil which may probably be reached by drilling to a depth of 3000 to 4000 ft. It is admitted that this will be wildcat drilling for it is not known whether the unexposed rocks carry oil and there are no surface indications of oil. This entire subject is discussed in United States Geological Survey Bulletin No. 711-A, and most of the report will be found to be contrary to the claims that have recently been advanced for oil properties in Utah.

Jan 9, 1919

By J. B. Sellers, G. R. Haworth, P. G. Zambas

Rock mechanics research was carried out in the Anvil Points mine, Rifle, Colo., in the period 1964-1968, with the dual purpose of providing oil shale to the retorts of six major oil companies and to perform research on mining cycle operations to maximize extraction under safe conditions. An 80% extraction ratio within the mining area proved feasible. Test results provided data on optimum pillar and roof design. Studies of mine orientation showed that the mining headings should take into account the prevailing joint patterns and also the directions of the principal in-situ stresses acting in the region.

Jan 1, 1973

Discussion of the paper of MANUEL EISSLER, presented at the New York meeting, February, 1915, and printed in Bulletin. No. 9.5, November, 1914, pp. 3661 to 2703. J. W. RICHARDS, So. Bethlehem, Pa.-I do not see in the paper a description of the Mabuki hearth as used for ore smelting. I noticed it described for concentrating matte, but I believe the older Japanese process was to use it for-smelting directly, by a pyritic smelting and Bessemerizing all in one operation, in the same simple hearth apparatus. There is a monograph published in German, on Copper-Ore Smelting in the Mabuki Hearth. At Ashio the practice of injecting bituminous coal at the, tuyères is noteworthy. It is very interesting to see two men load little cartridges on the end. of an iron rod with bituminous coal, and push them into the furnace tuyères, and with a piston inject 2 or 3 lb.. of bituminous

Jan 5, 1915

By G. C. Stone

At the conclusion of my paper on the same subject read at the Boston meeting of the Institute, I offered to send some of sample No. 2 to any chemist who wished to analyze it. Eight chemists wrote to me for samples; so far I have received results from five. I give these results in a table (on the following page), together with the results previously obtained: As to the chemists and their methods : K is an iron-works chemist whom I only know by correspondence; lie writes: "No. 27(13.64) was obtained by the method I generally use, as follows : Dissolve 0.8 grams spiegel in hydrochloric acid and a little potassium chlorate, in a half-liter flask. Boil off most of the acid, add ammonia in slight excess, redissolve in acetic acid, using rather more than is really necessary, and then add 8 or 10 grams of sodium acetate and make up to the mark with warm water. Boil hard for fifteen minutes, then allow to settle (cool?), until the liquid reaches the mark, and withdraw 300 C.C. of the nearly clear liquid. Add to this an excess of hydrochloric acid, evaporate to dryness, take up with hydrochloric acid and water, and separate the iron by two precipitations with ammonia (I have often tested the ferric hydrate for manganese, but have never found any, if the separation by ammonia was properly made). Finally, precipitate the manganese as phosphate." Nos. 28, 29 (13.35, 13.07) were by Ford's method." No. 30 (13.50) was by Troilus's method He writes, " I may add the results are quite as good as I expected, although for any element except manganese, they are not close enough for anything like accurate work." L is a firm of commercial chemists of large experience who have made a specialty of iron work. Their method is as follows : Dissolve

Jan 1, 1884

By Frank C. Green

Drilling for oil and gas in Missouri in 1935 was mostly confined to proven areas, but was marked by the completion of one of the largest oil wells, 53 bbl., and one of the largest gas wells, 2,000,000 cu. ft., drilled in recent years. A new oil pool, discovered in southern Cass County late in 1934, was further developed; a new pool in southern Platte County is possibly indicated by the completion of a single small well, which flowed naturally; and a deeper sand was developed in the Marota gas pool in Jackson County. Completions dropped to a lower level than in any recent year. A total of 73 wells, which included the deepening of 8 old wells, was drilled. In Bates County, there was one gas well with an open flow of 100,000 cu. ft., and one dry hole. Cass County had six oil wells with about 100 bbl. initial production; one gas well with an open flow of 500,000 cu. ft., and three dry holes. In Jackson County there were seven oil wells with 25 bbl. initial production; 24 gas wells with 7,358,968 cu. ft. open flow, and 27 dry holes. Platte County had one oil well, one small gas well and one dry hole. The oil well flowed naturally about 4 or 5 bbl. per day. It is rather difficult to obtain production figures on either oil or gas leases, but in cases where the figures have been given to the writer in confidence, they disclose conditions comparable with many other regions. One oil lease of 32 acres has produced 125,000 bbl. in four years, or nearly 4000 bbl. per acre. Another lease has made 50,000 bbl., or about 3000 bbl. per acre. It is probable that the total daily production at the end of 1935 was close to 200 hill. per day. A gas pool covering less than one square mile has made 110,111,000 cu. ft. in about 18 months. In this period, the open-flow capacity has been reduced from about 10,500,000 cu. ft. per day to about 3,500,000.

Jan 1, 1936

By Frank C. Green

Drilling for oil and gas in Missouri in 1935 was mostly confined to proven areas, but was marked by the completion of one of the largest oil wells, 53 bbl., and one of the largest gas wells, 2,000,000 cu. ft., drilled in recent years. A new oil pool, discovered in southern Cass County late in 1934, was further developed; a new pool in southern Platte County is possibly indicated by the completion of a single small well, which flowed naturally; and a deeper sand was developed in the Marota gas pool in Jackson County. Completions dropped to a lower level than in any recent year. A total of 73 wells, which included the deepening of 8 old wells, was drilled. In Bates County, there was one gas well with an open flow of 100,000 cu. ft., and one dry hole. Cass County had six oil wells with about 100 bbl. initial production; one gas well with an open flow of 500,000 cu. ft., and three dry holes. In Jackson County there were seven oil wells with 25 bbl. initial production; 24 gas wells with 7,358,968 cu. ft. open flow, and 27 dry holes. Platte County had one oil well, one small gas well and one dry hole. The oil well flowed naturally about 4 or 5 bbl. per day. It is rather difficult to obtain production figures on either oil or gas leases, but in cases where the figures have been given to the writer in confidence, they disclose conditions comparable with many other regions. One oil lease of 32 acres has produced 125,000 bbl. in four years, or nearly 4000 bbl. per acre. Another lease has made 50,000 bbl., or about 3000 bbl. per acre. It is probable that the total daily production at the end of 1935 was close to 200 hill. per day. A gas pool covering less than one square mile has made 110,111,000 cu. ft. in about 18 months. In this period, the open-flow capacity has been reduced from about 10,500,000 cu. ft. per day to about 3,500,000.

Jan 1, 1936

By H. D. Kiddle

IN mining in Malaya has been a courageous ad- venture in private enterprise, attended by all the hazards of prospecting in unexplored areas of tropical jungles-jungles that still cover four-fifths of the country. To assess the contribution of an industry to a country's revenue, it is necessary to consider not only duties levied on the products, but also the revenue from all businesses and individuals directly and indirectly deriving income from the industry. Exact figures are not obtainable, but from 1850 until shortly before the first World War, tin mining in Malaya was a dominant factor in the Federation's development. Even at the turn of the century, tin export duty alone represented 45 pct of total Government revenue, while in the 40-year period up to the end of 1937, tin ore duties collected by the Federated Malay States Government amounted to 383,- 81 0,284 Malayan dollars,* approximately one-fifth of the total revenue for the same period.

Jan 11, 1957

By Burnham E. Field

TAE chemical industry is constantly looking for new materials which either are more resistant to corrosion than those now available or have improved physical properties to meet the requirements of higher temperatures and greater pressures. Attack by acids is-one of the more important forms of corrosion-and in the last few years the development of acid-resistant alloys has been quite rapid. Perhaps the most notable example is that of nitric acid, 'the problem of which has largely been solved by the chromium-iron and chromium-iron-nickel alloys. Sulfuric acid may be handled in lead, iron, or the iron-silicon alloys, depending on conditions. As to hydrochloric acid, no metal or alloy can be called entirely satisfactory for handling. this acid under plant conditions.1 The results of our investigations on the resistance of the nickel-molybdenum alloys to hydrochloric acid have been confirmed by those of Guertler, Rohn, Schulz, Jenge, and others,' but thus far only one such alloy has approached commercial production in Germany; this contains approximately 15 per cent. chromium and 7 per cent. molybdenum with the remainder chiefly nickel. Dr. S. W. Parr, as far back as 1914, developed a complex alloy known as "illium," with a nickel base and containing some molybdenum.3 Dr. Parr was primarily interested in an alloy for lining bomb calorimeters, and while illium does show good resistance to acid it is too expensive for general use. Two United States

Jan 1, 1929

By V. I. Purcell, S. C. Sun. R. E. Snow

A study including effects of 7) pH value, 2) fatty acid collector, 3) fuel oil, 4) interfering ion, 5) particle size, and 6) operational variables. Test results indicate feasibility of fatty acid flotation under certain restrictive conditions. FATTY acids have been used as standard collectors for floating the matrix1-8 but not the leached zone phosphate ores. After a series of investigations, Davenport9 and Tarbutton10 concluded that the Florida leached zone ores tested were unamenable to fatty acid flotation and must be upgraded by floating the siliceous gangue with Armac-T as collector. The cationic flotation was estimated11 to cost almost ten times as much as a fatty acid process that would ideally give the same flotation grades and recoveries of phosphates. Mineralization: Extensive deposits of leached zone aluminiferous phosphate occur in Florida."= The ore sample used for this work was obtained from the Virginia-Carolina Chemical Corp., Clear Springs area, Florida. The ore is a potential source of uranium and aluminum as well as phosphorus. Since the uranium and the recoverable aluminum are contained in some of the phosphate minerals, an upgrading of phosphate results in a corresponding enrichment of both uranium and aluminum. The phosphate minerals in the ore are primarily pseudo-wavellite, millisite, and carbonate fluorapatite, with a minor amount of wavellite. Quartz and clay are the common gangue minerals, quartz being predominant. Others present in small amounts are ilmenite, hydrated iron oxides, staurolite, monazite, and zircon. Experimental Procedures: After being dried to less than 1 pct surface moisture the material was dry-ground in a Hardinge conical ball mill to —6 mesh. The ground product was classified into 6/20, 20/200, and —200 mesh size fractions. On the basis of Table I, the coarse and fine size fractions were considered as phosphate concentrates, because of their high phosphorus contents. In contrast, the 20/200 mesh fraction, which was low in phosphorus, was used as the flotation feed. All the flotation tests, unless otherwise stated, were performed in a laboratory Fagergren machine under the following conditions: 1) 400 g of solid feed for each test, 2) 2000 rpm impeller speed, 3) 8.9 pH and 4-min conditioning, and 4) 3-min flotation. The procedure used for the quantitative bubble pick-up tests has been described previously.18

Jan 1, 1958

By Norman A. Jull, A. L. Mular

Fundamentals of cyclones are reviewed briefly, where a typical cyclone is considered. Graphical cyclone data available in the literature have been converted to mathematical equations for convenience. Preliminary selection and design procedures for both cyclones and pumps are provided, and a sample calculation for a hypothetical grinding circuit is covered in some detail. In general, cyclone and pump suppliers should be consulted for definitive design purposes. Some cyclone suppliers currently employ digital computers for definitive design to ensure greater accuracy.

Jan 1, 1978

By W. J. Keep

Manganese is a nearly white metal, having about the same appearance when fractured as white cast-iron. Its specific gravity is about 8, while that of white cast-iron, reasonably free from impurities, is but a little above 7.5. As produced commercially, it is combined with iron, and with small percentages of silicon, phosphorus, and sulphur. It is generally produced in the blast-furnace. If the silicon is under 0.50 per cent., the product will be white. If the manganese is under 40 per cent., with the remainder mostly iron, and silicon not high enough to make the product gray, the alloy is called spiegeleisen, and the fracture will show flat reflecting surfaces, from which it takes its name. With manganese above 50 per cent., the iron alloy is called ferromanganese. As manganese increases beyond 50 per cent., the mass cracks in cooling, and when it approaches 98 per cent. the mass crumbles or falls in small pieces. When the percentage of manganese is high, the planes of the fracture are not so bright as when it is lower. The ferro-manganese which we have used in the experiments reported in this paper, contains Mn, 81.62; Si, 0.256 ; and combined carbon, 6.153 per cent. We have not been able to make test-bars from this, because the alloy cracks in small pieces in cooling. Manganese combines with iron in almost any proportion, but if an iron containing manganese is remelted, more or less of the manganese will escape by volatilization, and by oxidation with other elements present in the iron. If sulphur be present, some of the manganese will be likely to unite with it and escape, thus reducing the amount of both elements in the casting. Hence, in remelting irons, some of the sulphur which has entered from the fuel with which the iron is melted will very likely unite with some of the manganese in irons which make up the mixture and escape. Remelting, therefore,' reduces the percentage of manganese in cast-iron.

Jan 1, 1892

By John Griffen

THEORY HYDRAULIC classification as explained by Rittinger and others was largely restricted to conditions wherein the free-falling velocities of the particles were conceived as governing the separations effected (see chapter 9). The laws governing classification under free-falling conditions have been summarized by Chapman and Mott as fo1lows:l Nomenclature r represents, in a particle of irregular shape, the round-hole screen through which the particle would pass, or some other linear dimension of the particle equivalent to d, the diameter of a sphere. s, the specific gravity of the particle. 1, the specific gravity of the water used as a medium. K, a constant. W, the velocity of the water. In an Upward Current of water 1. A particle will move upward if [V > K dr(s - 1)] and, by suit- ably regulating the speed of the water current, the larger and heavier particles may be made to fall downward against the current, leaving the smaller, lighter particles in suspension in the current. 2. Particles such that [- = -] cannot be separated in an upward- current classifier with any one velocity of current. Coal particles having a specific gravity of 1.35 cannot be separated from refuse particles of [2.5 - 1 2.5 sp. gr.] unless the ratio of diameters is less than [ 4.3 to 1, 1.35 – 1] and the raw coal must be screened to size limits within this ratio if they are to be separated. Cone-shaped vessels or vessels of other shapes that allow the use of different velocities of current at different points in the flow are used to modify this limitation.

Jan 1, 1943

By Arthur Taggart

SOME years ago, A. M. Gaudin and one of the authors published a paper showing removal of tar acids from solution by sulfides preferentially as compared to gangues (specifically by galena as compared to quartz).1 The underlying phenomenon was classed as adsorption, and the paper went on to develop the general thesis that so far as water-soluble frothing and collecting agents in flotation are concerned, the phenomenon of adsorption is one of controlling importance. Adsorption was defined in that paper as "a process of rearrangement of a system, which results in establishing a difference in concentration, as between the interfacial layers and the bulk of the phases, of a substance or substances initially uniformly dispersed in one or several of the phases." The paper went on to develop the relation between adsorption and surface energy according to Gibbs' equation (which may be thrown into the form U/c = KdT/dc, where U = excess concentration in surface layer, c = concentration, T = surface tension, and K is a constant), and pointed out that, according to this equation, degree of adsorption and change in surface tension vary directly. The present paper offers a somewhat different definition for the term adsorption; and sets up, in sweeping terms, the generalization that simple chemical reaction underlies the functioning of the flotation reagents which control mineral collection, when these reagents are soluble in and act from solution in the water of the pulp.

Jan 1, 1930

By Douglas R. Cook

The urgent need for new base metal ore discoveries was discussed by various authoritative exploration personnel at a CIM symposium on the future of the Canadian mineral industry held at Ottawa in 1967. Data presented at this meeting showed that approximately 150 new mines have started or restarted production in Canada since 1955. Over half of these mines were discovered prior to 1950. The distribution of Canadian ore discoveries during the last 15 years (shown in Fig. 1) illustrates a striking reduction in the discovery rate in recent years in spite of increasing exploration expenditures. These data indicate that $20 million is now spent in exploration for every significant metal deposit found, and evidently the cost of discovery is still rising. Even fewer discoveries are being made in some other important continental areas of the world such as Africa, Australia and South America. The discovery record in the U.S. is thought to be more rewarding than in Canada because the new deposits appear to be substantially larger. Fortunately, most good base metal ore deposits have attractive investment re- turns to justify large exploration expenditures. The magnitude of the exploration expenditures and the increasing need to develop additional metal resources justifies a critical review of the procedures used in the search for ore deposits. Of particular concern is the need to improve the use of exploration techniques in the attempt to obtain better discrimination and efficiency. There is a tendency by inexperienced exploration groups to think of any geological, geochemical or geophysical anomaly as an exploration target and ignore the fact that anomalies can result from many factors other than economic concentration of metals. The desire for a unique and favorable explanation of exploration data often results in too rapid a movement from the reconnaissance to the drilling stage without the use of all the relevant information.

Jan 7, 1968

By Nicholas J. Grant, John Chipman

A full understanding of the behavior of sulphur in the basic open-hearth process has been delayed by lack of dependable data covering a wide range of slag conditions in the absence of other complicating factors that are likely to be present under operating conditions. It has been generally accepted that strongly basic slags will dissolve more sulphur than will those in which the acidic and basic constituents are more nearly balanced. It has been known that both slag and metal would absorb sulphur from the flame when the sulphur content of the fuel is high. It has been generally believed that manganese assists in the transfer of sulphur from metal to slag. Almost nothing has been known of the effect of temperature upon desulphurization;the data have been conflicting and there has been a tendency to depend rather heavily upon analogy with the better understood desulphurizing reaction of the blast furnace. Many attempts have been made to build up from open-hearth data a satisfactory theory of the chemical reactions involved in the process. That this has been an extremely difficult task is owing to two reasons that have been very generally recognized. The first is the parallel and simultaneous reaction of sulphur transfer between flame and bath. The second is the difficulty of distinguishing between the factors that ultimately limit the transfer from metal to slag—i.e., equilibrium conditions—and those whose influence is only upon the rate of transfer. It has been the object of the work here recounted to study the equilibrium distribution of sulphur between slag and metal in the absence of these complicating factors, with the hope that a better understanding of the equilibria involved would lead to a better control of the over-all process in the open-hearth furnace. A review of the literature on steelmaking reveals almost complete agreement with respect to the paramount importance of lime in promoting desulphurization. In expressing this effect in quantitative terms, however, and in formulating the relationships between the concentrations of other slag components and the desulphurizing power, there is little agreement. For instance, the "basicity" or basic strength of the slag is commonly measured by some kind of ratio of concentration of basic to acidic oxides. Of these, the following have been reviewed by Schenck:20 V radio = % CaO/%SiO, Körber and Oelsen's _ % CaO'. 100/% CaO + % SiO2 where (%CaO') = % CaO- 1.18% P2O5. Herty's B ratio = % CaO - (0.93 . % SO2) - (1.18% P205) Among others there appear the following: 20 References are at the end of the paper.

Jan 1, 1947

By Nicholas J. Grant, John Chipman

A full understanding of the behavior of sulphur in the basic open-hearth process has been delayed by lack of dependable data covering a wide range of slag conditions in the absence of other complicating factors that are likely to be present under operating conditions. It has been generally accepted that strongly basic slags will dissolve more sulphur than will those in which the acidic and basic constituents are more nearly balanced. It has been known that both slag and metal would absorb sulphur from the flame when the sulphur content of the fuel is high. It has been generally believed that manganese assists in the transfer of sulphur from metal to slag. Almost nothing has been known of the effect of temperature upon desulphurization;the data have been conflicting and there has been a tendency to depend rather heavily upon analogy with the better understood desulphurizing reaction of the blast furnace. Many attempts have been made to build up from open-hearth data a satisfactory theory of the chemical reactions involved in the process. That this has been an extremely difficult task is owing to two reasons that have been very generally recognized. The first is the parallel and simultaneous reaction of sulphur transfer between flame and bath. The second is the difficulty of distinguishing between the factors that ultimately limit the transfer from metal to slag—i.e., equilibrium conditions—and those whose influence is only upon the rate of transfer. It has been the object of the work here recounted to study the equilibrium distribution of sulphur between slag and metal in the absence of these complicating factors, with the hope that a better understanding of the equilibria involved would lead to a better control of the over-all process in the open-hearth furnace. A review of the literature on steelmaking reveals almost complete agreement with respect to the paramount importance of lime in promoting desulphurization. In expressing this effect in quantitative terms, however, and in formulating the relationships between the concentrations of other slag components and the desulphurizing power, there is little agreement. For instance, the "basicity" or basic strength of the slag is commonly measured by some kind of ratio of concentration of basic to acidic oxides. Of these, the following have been reviewed by Schenck:20 V radio = % CaO/%SiO, Körber and Oelsen's _ % CaO'. 100/% CaO + % SiO2 where (%CaO') = % CaO- 1.18% P2O5. Herty's B ratio = % CaO - (0.93 . % SO2) - (1.18% P205) Among others there appear the following: 20 References are at the end of the paper.

Jan 1, 1947

By E. E. White

In August, 1911, I read a paper before the Lake Superior Mining Institute1 on surveying and sampling diamond-drill holes. The present paper gives a more thorough descriptiou of these methods, together with a few changes and notes suggested by further experience. Since August, 1911, the methods, used constantly by the Cleveland-Cliffs Iron Co., have been developed to a higher degree of efficiency, and have given great satisfaction. Until a few years ago but little attention was paid to the determination of the actual course of drill-holes, to the accurate sampling' and analysis of the material, or to the scientific location of the drill-holes. It has now been common practice for several years in many districts to test the inclination of drillholes by etching glass tubes with hydrofluoric acid, but the direction of deviation from the vertical has not often been determined. Methods of determining the direction by means of a compass were first developed in connection with drilling in Victoria. The latest method used on the Rand in South Africa has been recently described by John I. Hoffman.2 In the same paper Mr. Hoffman describes an ingenious method of wedging-off a drill-hole so as to start new holes at several successive points. By this means a hole can be deflected in any desired direction, and the curvature can be controlled to a considerable extent, provided the rock is soft enough to permit the hole to be wedged off. Unfortunately, in the Lake Superior district, the jasper iron-formation is so hard that it is very difficult, if not impossible, to do this. I tried to deflect one hole so as to avoid drill-rods stuck in the hole, by using a

Jan 1, 1913

Note Any member who desires to be designated as being "Available for Consulting Work" can arrange it simply by sending a written request to the office of the Secretary of the Institute The following list of members is primarily arranged geographically, with secondary consideration to political subdivisions arranged alphabetically First, the states of the United States , then other North America, in order Alaska, Canada, Mexico, the West Indies, and Central America Then cones South America, Europe, Africa, and Asia, each including the near by islands associated with those continents Australia, the islands to the north, and the Pacific islands except Japan are grouped together under Oceania The various countries are indexed on the preceding page NORTH AMERICA UNITED STATES ALABAMA America -Dyar, G C Anniston -DePriest, S H Klugh, B G Lefforge, J W Auburn Poor, R S Bankhead -Armstrong, W D Bessemer -Beck, A IV, Jr Carnes, D Chabot, L S , Jr Creveling, J C

Jan 1, 1952