Search Documents

By AIME AIME

THIS year's Chairman of the Mineral industry Education Division is, like his predecessors, no novice in that field, having been in 1928 Chairman of the Engineering Education Committee which labored so well that it was enlarged into a Division of the Institute's activities . For almost a quarter of a century lie has been a dean in mining and engineering schools, with considerable experience before that as a teacher. A native-born New Englander (June 23, 1881), he naturally went to Massachusetts Institute of Technology where he received the Bachelor's degree in mining in 1904. Just why a Fitchburg. Massachusetts boy yearned to he a mining engineer he has never explained, but why should any boy ever have to explain why lie wants t? be a mining engineer? Like the old rhyme about the reasons why a man should drink, "any other reason why" is adequate..

Jan 1, 1945

By M. E. Fine

IN the apparatus for measuring internal friction shown in fig. 1, a modification of that described by Kê,1,2 the parasitic energy loss or background is equivalent to a Q-1 of approximately 4x10-5. This low value of background was obtained by using a jeweler's collet of appropriate size for the upper support, eliminating lateral motion without immersing the bob in oil, and designing the bob to reduce air resistance. The pendulum is supported on the frame through a snug fitting, sliding rotary joint (fig. I-B). A slight twist of the top imparts essentially pure torsional motion to the pendulum. No evidence of energy loss in the sliding joint has been observed. In the bob (E) steel balls are used in the torsion arm, and the bottom is filled with lead giving a total weight of 94 g. A lighter bob may be used for small diameter specimens. Another bob was a solid disc with provision for adding discs to change the frequency. The oscillating image of the filament is recorded on a revolving drum camera (fig. 1-3) driven by a synchronous motor. This allows use of frequencies higher than can be measured visually on a glass scale. Samples varying in diameter from 0.020 to 0.075 in. have been measured, the frequencies have ranged from 1 to 12 cps, and the maximum strain varied from 0.5 to 10x10-5. With appropriate modification the sample may be placed in a thermostat. The apparatus may also be used to measure the shear modulus. In the examples of measurement given in table I the internal friction of Permendur and the 46.8 Ni-Fe alloy are due, for the most part, to magneto-mechanical hysteresis8 (elastic hysteresis accompanying stress-induced magnetostriction) which depends on strain amplitude and increases with annealing. The internal friction of most materials decreases with annealing. References IT. S. K6: Physics Review (1947) 71, 533. 2 T. S. Kê: Transactions AIME (1948) 176, 448; Metals Technology (June 1948) TP 23703. 3 R. Becker and W. Döring: Ferromagnetismus. 365 (1939). J. Springer.

Jan 1, 1951

NEW MEMBERS The following list comprises the names of those-persons who became members during the month of January, 1914. Members ADIASSEWICH, ALEXANDER, Dept. of Commerce & Industry, 11, Nadejdinskaia, St. Petersburg, Russia. BEARD, JOHN W., Mine Supt., Lane-Rincon Mines, Inca, Temascaltepec, Mex., Mexico; BORCHERDT, WALTER 0., Supt The Bertha Mineral Co., Austinville, Va BREWSTER, BURT B., Sales Engr., Sullivan Machinery Co., 1127 Central National Bank Bldg., St. Louis, Mo: CHASE, ROGER E., JR., Assayer 3906 No. Baltimore St., Tacoma, Wash. CULBERT, J. VICTOR 7S4 Wellington St., London, Ont., Canada; DICKINSON, ALBERT W., Supt. Of Mines Bevier, MO. DODSON, T. M Mores, Colliery, Schuylkill Co., Pa FORREST, CHARLES N., Chem. Engr Maurer, N. J.

Jan 2, 1914

PRODUCTION of nonmetallic mineral raw materials used by the fertilizer, ceramic, chemical, and construction industries and many others, was greater during 1953 than in any previous year. Production of fertilizer minerals was the highest in history despite somewhat decreased consumption in the second half of the year. Marketable phosphate rock production increased 10 pct to an estimated total of 13.1 million LT, valued at $78.5 million, and potash production was estimated at 1.8 million tons of K2O equivalent, valued at over $60 million. Crude gypsum output exceeded the 1952 total and approached the record of 8.66 million tons mined in 1951, with indications that 1953 will show a new all-time high. Gains and losses among gypsum products were irregular, with major gains in plate- glass and terra-cotta plasters, sanded building plasters and miscellaneous building plasters, and principal declines in base-coat plasters, prepared finishes and tile. Lath and wallboard outputs were each about 20 pct higher than in 1952.

Jan 2, 1954

By J. V. Gluck, Ping-Wang Chiang

The tellurium-rich region of the Sb-TI-Te ternary system was investigated by means of DTA, metallo-graphic, X-ray, and electron beam microprobe techniques on the sections Sb2Te3-T12Te3, SbTlTe2-Te, SbT1Te2-Sb2Te3, and SbTlTe2-T12Te3. The phase behavior of this region is summarized in terms of four ternary invariant reactions and a schematic reaction diagram is suggested. Isopleths for the sections SbT1Te2-Sb2Te3, Sb2Te,-T12Te3, and SbTlTe2-Te were constructed, and a schematic diagram of the projections of the liquidus lines and invariant planes is presented. No evidence was found to support the existence of the ternary compound "SbTlTe3", or pseudo-binary behavior of the section T12Te3-Sb2Te3, as reported by Borisova and Efremova. Electrical conductivity, Seebeck coefficient, and thermal conductivity measurements were made at room temperature on fully annealed samples. 1 HE phase relationships in chalcogenides are often complex and difficult to resolve, particularly since the approach to equilibrium is a rather slow process. For example, the phase diagram of the T1-Te binary system was in doubt until clarified by Rabenau et al.,1 the phase fields at compositions near Bi2Te3 in the Bi-Te binary system have only recently been satisfactorily elucidated by Glatz,2 and there may still be some question as to the extent of the Sb2Te3 field in the Sb-Te system.3-5 In ternary systems, the existence of the compound "AgFeTe2" was the subject of a number of conflicting reports6-8 and the stoichiometry of the composition "AgSbTe2" was in doubt for a period of time.9 Recently, questions have arisen regarding the existence of certain compounds in the ternary systems Bi-Tl-Te10-14 and Sb-Tl-Te.15 The impetus for studies of these latter systems stemmed from the report of Borisova et a1.10 of a congruently melting ternary compound, "BiTlTe3", which apparently had extremely favorable thermoelectric properties for room-temperature cooling applications. Attempts by other investigators to produce the compound or confirm the transport properties proved to be unsuccessful.12-14 Recently, Chiang and Gluck14 reported studies of the phase relations in the tellurium-rich region of the Bi-T1-Te system which indicated that the section T12Te3-Bi2Te3 was not pseudobinary as suggested by Borisova et a1.10 The contention of Spitzer and sykes12 was supported that the composition "BiT1Te3" was multiphase, with the primary constituent actually being BiTlTe2, a compound whose existence has been well demonstrated.16,17 The investigation reported in the present paper was prompted by a later report of Borisova and Efremova15 on a similar study of the section T12Te3-Sb2Te3 from the Sb-T1-Te system. They also claimed this section to be pseudobinary, and that a ternary compound "SbTlTe," was formed peritectically. Some "preliminary" crystallographic data were given for the compound and thermoelectric transport properties were presented. In view of the questions concerning the behavior of the Bi-T1-Te system and the existence of the compound "BiT1Te3" it was suspected that the Sb-T1-Te system might behave in a similar fashion, particularly in light of the known existence of a compound SbT1Te2, iso-structural with BiT1Te2.17 Consequently, an investigation was undertaken to clarify the phase relationships in the tellurium-rich region of the Sb-T1-Te system. It is the purpose of this paper to present the results of this study, including a representation of the phase relations, isopleths for various composition sections, and the determination of some phase compositions and transport properties. EXPERIMENTAL PROCEDURES Commercially available high-purity (99.999+ pct) elements, purchased from the American Smelting and Refining Co., were used for the sample preparation. All samples were made from thoroughly mixed powders of previously prepared master alloys: SbTlTe2, Te, Sb2Te3, and T12Te3. Stoichiometric quantities of the constituents for each 10-g sample were weighed into a specially cleaned fused silica tube and sealed under a vacuum of better than 5 x 10-5 torr. The sealed constituents were fused and reacted at 650° to 750°C for at least 4 hr under continuous agitation in a "rocking" furnace, and the resulting product was air-cooled. The tube was opened and the sample was ground to a powder. A portion of the powder was rebottled in a DTA tube under vacuum, and the rest of the material was similarly resealed in a separate tube, re-fused in the rocking furnace, and again cooled to make the ingots for electrical and microstructural studies. All samples were subjected to further heat treatments as discussed in the section on experimental results. Each DTA tube was made of 7-mm-OD fused silica tubing with a concentric 2-mm-ID depression about 4 mm long formed in the bottom to accommodate a thermocouple. The size of a DTA sample was 0.5 to 1.0 g. An Aminco Thermoanalyzer whose accuracy was within 2°C18 was used for the DTA measurements. The metallographic samples were prepared by conventional techniques. A solution of FeCL dissolved in a methanol-HC1 mixture was found to be the most satisfactory etchant. Electron beam microprobe scanning and point-count examinations were made on polished and unetched samples using an ARL Electron Microprobe at an electron beam voltage of 20 kv. The detectors were set to receive characteristic La1 radiation. Calibration standards of the pure elements were incorporated in each sample mount; quantitative point counts were calibrated by a method similar to Ziebold

Jan 1, 1969

By B. D. Cullity

This investigation of bismuth-selenium alloys was made in an attempt to find a suitable material for use in thermoelectric generators. These devices are simply thermocouple circuits designed for the efficient production of electrical energy from thermal energy, which may in turn be derived directly from solar radiation or from the combustion of fuels. The requirements of a material for use in a thermoelectric generator are obviously quite different from those of a material used in a temperature-measuring thermocouple. Naturally, for power generating purposes, the thermoelectric power (voltage produced per degree difference in temperature between the junctions) must be as high as possible. Furthermore, in order to obtain reasonably high power outputs, the materials used in the generator must have an electrical conductivity which is as high as possible. Finally, in order to minimize heat lost by conduction to the cold junction, the thermal conductivity must be as low as possible. The relation between these several factors and the efficiency of conversion of thermal into electrical energy—the thermoelectric efficiency—has been discussed by Telkesl in a recent review of the subject. She gives the thermoelectric efficiency as: W o Efficiency = -Wo ______________i____________ TR-TC+ O2TR-Tc) where W, = power output in external load (watts) Wi = rate of heat input to hot junction (watts) TE,T, = temperature of hot and cold junctions (oA) K1,Kz = thermal conductivity of the two thermocouple materials (watts/cm°C) p,,pz = electrical resistivity of the two thermocouple materials (ohm cm) 9 = thermoelectric power (volts0/C) For many materials, some of the desired properties (for example, high electrical and low thermal conductivity) are almost mutually exclusive; the problem thus becomes one of finding a material which has the optimum combination of pfoperties. Bismuth-selenium Alloys work on the equilibrium diagram of the bismuth-selenium alloys has been reviewed by Hanson who gives the diagram reproduced in There are two intermediate phases in this system, BiSe and Bi²Se3. The existence of an alpha and beta modification of BiSe has not been demonstrated satisfactorily and the writer found no evidence of it in the present work. BiSe and Bi2Se3 have, like bismuth, a rhombohedra1 crystal

Jan 1, 1949

By D. J. Bourne, G. E. Atwood

The new potash refinery of Duval Sulphur & Potash Co. produced its first tonnage of muriate of potash in November 1951. Full capacity was attained in early 1952. Excellent extraction efficiency is being obtained by the process, which is basically froth flotation. System temperature control is practiced and has proved to be of great metallurgical value through high potassium recovery and. low reagent cost. WHEN Duval Sulphur and Potash Co. recently entered the established potash industry, the vast amount of pioneer work essential in an entirely new endeavor was unnecessary. Thus it was possible to screen and assemble proved techniques into a highly efficient process based on the combined knowledge of the industry. It is hoped that the refinements Duval has added to these cumulative achievements will contribute to the rapid advance of the potash industry and related enterprises. The process selected utilizes as raw material syl-vinite ore typical of the Permian Basin. This ore is principally comprised of interlocked crystals of potassium chloride, about 40 pct, and sodium chloride. Also there is as much as 1 1/2 pct of dispersed clay slime which, because of its nature, highly complicates beneficiation of these ores. The refining method is basically flotation in which the mineral sylvite is floated away from the halite-clay gangue to produce a 60 pct K,O muriate of potash product for the plant-food trade. It departs from established practice in the use of an improved reagent scheme, developed by the company's technical staff, and in

Jan 1, 1954

By Young C. Kim, Francis Martino, Ish Chopra

For the past two and one-half years, various emission control strategies were jointly developed by the University of Arizona and the Homer City Owners to com- ply with the clean air requirements at its Homer City Power Plant. Some of the available options for the SO2 emission control by the Homer City Owners were:l)cleaning of run-of-mine coal,2) scheduling of mining operations at its captive mines, 3) blending the captive mine coal with externally purchased low sulfur coa1,and 4) placing a partial FGD system. This paper describes two specific emission control strategies developed and implemented. These are: 1) production scheduling at the mining face to minimize sulfur variability, and 2) external purchasing of low sulfur coal for further blending. The main objective of this paper is to share our experiences on implementing the developed strategies. This paper emphasizesthe need for proper mine planning on a short-term basis, if the power plant is to meet the desired objective.

Jan 1, 1983

By Paul A. Flinn, Jean-Marie Robert Genin

The MCssbauer effect was used to study the distribution of carbon in Fe-C alloys of high carbon content during room-temperature aging. In freshly formed rnartensite the carbon distribution is approximately random; carbon clustering occurs dun'ng aging. In the retained austete the carbon atoms are isolated, suggesting an efiective repulsion; and no rearrangement during room-temperature aging is evident. The kinetics of the carbon clustering in martensite has been studied in detail at 0" . 10". and 20°C. The time and temperature dependence observed is sinzilar to that reported for a variety of other aging effects, such as resistance change, hardness increase, and recovery of internal friction. The stabilization of the martensite kransformation also appears to be related to the clustering effect. DESPITE extensive efforts since the early days of Reaumur, the mechanism which provides the strengthening of steel remains controversial in many cases for several reasons: 1) The structure of as-quenched martensite is not well-determined. 2) Experimental methods capable of distinguishing between various hardening mechanisms are not well-developed. 3) The temperature of formation of many low-alloy martensites is so high that the martensite formed during quenching may be already tempered to some extent before any observation. Among all the hardening phenomena, the most puzzling one occurs at room temperature, where no structural changes have been detected by the usual methods of X-ray diffraction or electron microscopy. However, a new and more sensitive technique became available with the discovery of the MBssbauer effect. This effect makes possible the detection of changes in the local environment of iron atoms in solid solution. It has been extensively used in the study of substitutional alloy systems, for example, Fe-Al,1 Fe-Si,2,3 Fe-Rh,4 and Fe-Ni.5 Making use of the possibility of obtaining new structural information, we undertook an investigation of the aging of high-carbon Fe-C martensite to follow the structural changes involved in the aging at room temperature. Preliminary results6 showed that a clustering of the carbon atoms occurs with time. A systematic study of the kinetics of the process showed a striking similarity to the kinetics of stabilization of the marten-sitic transformation, thus suggesting further investigation of the relationship. EXPERIMENTAL TECHNIQUE To eliminate difficulties with the aging of martensite prior to the first experimental measurements, we needed an alloy with an M, temperature not above room temperature. Other investigators7 were misled by results obtained on alloys which transformed above room temperature and underwent structural changes prior to the first Mossbauer measurements. Winchell and cohen8 dealt with this difficulty by using a third element, nickel, to depress the MS below room temperature. The presence of nickel did not seriously interfere with hardness or resistivity measurements, but it would complicate the interpretation of the Mossbauer data by increasing the variety of iron environments. We chose, therefore, to obtain the necessary lowering of the M, simply by increasing the carbon content. After the first quench to room temperature, our specimens are retained austenite, which we later quench into liquid nitrogen. The martensitic transformation takes place suddenly, so that the as-quenched condition of the samples is retained, since the temperature is low enough to prevent any carbon diffusion. A Massbauer spectrum at 77°K can be taken and analyzed; after an appropriate up-quenching to the aging temperature, a new Mossbauer measurement at 77°K can be made. Fig. 1 shows a typical cycle of experiments. The samples were foils 25 p thick of high-purity

Jan 1, 1969

By Timothy Collins

There was once a speculative period of interest in small mining companies that is commonly referred to as "the uranium boom of the 50's." In the late 60's, there was a second mining stock boom: it centered around uranium and silver, when silver had reached a new high of $3.60. In the mid 1970Js, there may be a new boom in the making, and it appears that substantial public and institutional interest in mining equities will finally result in a viable long-term capital market rather than the boom-or-bust pattern of the 50's and 60's. The reason for Wall Street's renewed interest in mining is understandable: most mineral commodities have recently gone up in price. Domestically, these price increases have come in the wake of the inflationary spiral unleashed by years of unbridled government deficit spending and erratic fiscal and monetary policies. Internationally, of course, the biggest push for higher prices has come from third-world countries whose primary income derives from indigenous natural resources. Many of these countries-whose fiscal and monetary policies haven't been models of excellence either-have attempted to cope with the worldwide economic mess by forming cartels that could control the price of commodities. What's happened to petroleum is well-known; what's happened to copper, bauxite, phosphate, and uranium is part and parcel of the same syndrome.

Jan 9, 1975

By Ernest Gayford

This is a nontechnical paper on flotation, subdivided under three general headings: (I) Definition of flotation; (2) what flotation is now doing in Utah; and (3) what is the future of flotation? Definition T. A. Rickard defines flotation' as "the act or state of floating," from the French flottaison, water-line and flotter, to float. The dictionary defines flotation as "the science of floating bodies." The flotation process is a method of concentrating ores by frothing. Weinig and Palmer,2 define flotation as follows: What is the flotation process? Briefly, it consists in the agitation of finely divided ore in water containing bubbles of air or gas, a small amount of oil and, usually, other reagents, soluble and insoluble; under these conditions the small particles of native metals, sulfides, arsenides, antimonides, selenides and tellurides show a tendency to attach themselves to the films of the bubbles, and are thus carried to the surface of the water. The oxidized gangue minerals, such as quartz, feldspar, limestone, hematite, etc., show much less affinity for the bubbles, are easily wetted by the water, and either remain in suspension in the water, or sink to the bottom of the vessel. If the bubbles are sufficiently stable they can be removed, carrying their load of sulfide-mineral particles with them. Thus there can be effected a separation of the two classes of minerals from each other, assuming that the grinding has been sufficient to unlock all of the particles of different composition. The separation does not depend upon differences in specific gravity of the various minerals; in fact, the sulfides are usually heavier than the oxides, and some of the heaviest sulfide minerals are the easiest to float. A particle of mineral may be so large, however, that its weight will counteract its affinity for the film of the bubble. In most cases the ore must be fine enough to pass a screen having at least 48 meshes to the linear inch. Taggart3 defines flotation as follows: Flotation is a method of wet concentration of ores in which separation of mineral from gangue is effected by causing the mineral to float at or above the surface of a body of liquid pulp while the gangue becomes or remains submerged. The method

Jan 1, 1928

NORTH AMERICA Number Members Alaska 43 Canada 340 Mexico 205 Newfoundland 4 United States Alabama 39 Arizona 120 Arkansas 11 California 699 Colorado 168 Connecticut 89 Delaware 18 District of Columbia 140 Florida 20 Georgia 6 Idaho 78 Illinois 214 Indiana 77 Iowa 12 Kansas 24 Kentucky 33

Jan 1, 1936

By Howard I. Smith

THE mineral trona was discovered on Government land in 1938, about 18 miles west of the town of Green River, Wyo., in the core of the John Hay, Jr., well, a test well drilled for oil by the Mountain Fuel Supply Co. in sec. 2, T. 18 N., R. 110 W., sixth principal meridian. Although no oil or gas was reported, the drilling led to a discovery of great potential economic importance and exceptional scientific interest. Trona is a relatively rare mineral found at various places in playa deposits but not previously found at any great depth. It is composed of hydrous sodium carbonate and sodium bicarbonate (Na2CO3.NaHCO3.2H20). Pure trona contains the equivalent of 70.35 per cent of sodium carbonate. Total sodium computed to carbonate times 1.42 equals the percentage of trona in the absence of other sodium carbonate minerals in the sample. ANALYSES Two short pieces of core sent to the author a few days after the completion of the Hay well were analyzed by R. C. Wells[t] and found to be exceptionally pure trona. A brief article on this discovery has already been published.1 Arrangements were then made through W. T. Nightengale[$] for the author to inspect and sample the core. The company log of the well included notations of sodium salt crystals from a depth of 1190 to 1820 ft. Not being able to identify all the minerals present, the author selected several specimens of the core for petrographic examinations and sampled the sections of trona for analysis. J. J. Fahey, of the Geological Survey, examined the specimens and reported most of the crystals to be a new anhydrous sodium carbonate and calcium carbonate mineral (Na2CO3.2CaCO3), which he named shortite,2 after Maxwell N. Short.* He analyzed the samples of trona, with the results shown in Table I. [ ] In addition to the 10 ft. I in. of trona in the first section, it is reasonable to assume that the 9 ft. 8 in. for which no core was available for sampling is either mostly trona or some other soluble salt, but it should not be included in calculating reserves. In the part of the core between 1590 ft. 3 in. and I600 ft. 4 in. the material insoluble in cold water, amounting to about 5 per cent, was estimated petrographically to contain 70 per cent clay, 25 per cent shortite, and 5 per cent pyrite. ACCOMPANYING MINERALS Fahey later secured about 600 ft. of the core for a detailed examination and study

Jan 1, 1942

By RUSSELL C. FLEMING

THE important advances that have been made of recent years in mining and milling methods and in mechanical equipment at mines need no re- telling, but there has been a remarkable growth in one type of equipment which has gone nearly unnoticed. That is the increasing use of storage-battery locomotives underground. Since the war the number of these locomotives and their field of use have increased tremendously; their growing acceptance represents an al- most complete reversal of opinion from an earlier period when they were generally looked upon as in- adequate for the strain of mine service. At the time when storage-battery powered units were first making their bid for recognition, the use of power in haulage had already passed through several phases; hand tramming, rope haulage, compressed air locomotives, even gasoline locomotives, had all been used, ending finally in the general adoption of the electric trolley locomotive for practically all power-haulage requirements. It was, and is, conceded that the trolley loco- motive met more adequately the varied and severe conditions of mine service than any previous type of haul- age unit. Subsequent developments have had to endure comparison and surpass in performance that type of haulage before changes would be considered.

Jan 1, 1930

By Robert B. Fulton

Staurolite, an iron aluminum silicate mineral, is used industrially as a high value-in-use sand-blasting agent, as a premium grade foundry sand, and as the source of aluminum in portland cement manufacture in areas where the aluminum constituent is not economically available from shale or argillaceous limestone. It is produced by E. I. du Pont de Nemours & Co. as a coproduct in titanium mineral production in Florida where it was first recovered on a commercial scale in June 1952 from the Pleistocene sand deposit known as Trail Ridge. In the Trail Ridge deposit it comprises about one-fifth of the heavy minerals, the principal other heavy mineral constituents being ilmenite, leucoxene, rutile, zircon, kyanite, sillimanite, and tourmaline. Staurolite and the other silicate nonconductive heavy minerals are separated from the conductive titanium minerals on high-tension separators. The silicates are then separated from one another magnetically, the staurolite being relatively magnetic. In the total processing, 200 tons of raw sand yield 7 tons of heavy mineral concentrate from which about one ton of staurolite is recovered. This process yields staurolite concentrates of the characteristics given in Table 1. These concentrates are sold as three products with the size distribution of subrounded particles shown in Table 2. All three grades are used in sand-blasting for cleaning metal, for paint removal, and for cleaning buildings. Staurolite compares favorably with lower unit cost abrasives, such as boiler slags and mineral aggregates, in applications where the abrasive is used only one time and is not recovered. Because it is hard, fine, clean, and dense it can reduce blasting time, with less material reportedly being required [ ]

Jan 1, 1983

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) No. 544.-Mining engineer, 39 years of age, graduate E. M. with extensive experience in the United States, Canada and Spanish-speaking countries. Good organizer, energetic and resourceful. Experience covers mining and milling of gold, silver, lead, copper, zinc and tungsten. At present a Captain of Engineers, U. S. A., expecting to be released shortly. Open for engagement as manager, superintendent or examining engineer. Correspondence and personal interview solicited. No. 545.-Engineer and geologist, member, age 29 years, technical graduate and married. Six years' practical experience as surveyor, chief engineer and in exploration work in West, Southwest and Mexico. Speaks French and Spanish. Desires position with exploration company or as engineer and superintendent of small mine. Will be released from commission in United States Navy about February 1. No. 546.-For staff position-or manager. Member, married, graduate mining and metallurgical engineer, 18 years' experience in underground and metallurgical work on gold, silver, copper, lead and zinc ores. Details, references, and qualifications will be sent if requested, or may be seen at Institute office. Available immediately in United States or Canada. Would go reasonable distance for an interview if desired. No. 547.-Member, experienced in mine operating, engineering, general contracting and constructing. Technical graduate, mining engineer, married, age 38 years. Many years' practical experience while advancing through different positions to manager. Best of references and rating. Desires change. Position with future. Can obtain results. Salary commensurate with position. Available on short notice. No. 548.-Mining engineer, member, technical graduate, age 31, on military service since August, 1914, available after January 31. Best of references.

Jan 3, 1919

By Charles Williams

BOYLE'S law states that the volume of a gas at B constant temperature varies inversely as its pressure, PV = C, or V = C/P Therefore, the volume of a gas at any pressure is to its corresponding pressure as the volume of the same gas at atmospheric pressure is to atmospheric pressure, V, = V° Also, P1 P0 the volume of the gas at any other pressure is to its corresponding pressure as the volume of the gas at atmospheric pressure is to atmospheric. pressure, V2/P1 V0/P0 V°P VA Solving for V1 and V2, V2 = and V2 =V0P2/P0

Jan 2, 1927

By T. H. Aldrich

(San Francisco Meeting, October, 1911.) THERE are two conditions generally prevailing upon the earth-those within atmospheric influence, tending towards oxidation, and those away from atmospheric influence, tending towards reduction. Practically all mineral substances from mines of any depth are in a reducing condition. Since the cyanide process, in order to dissolve silver or gold, requires that the prevailing conditions under which it operates shall be oxidizing, and the materials usually acted upon being of a reducing character, it becomes necessary to supply oxygen to the solution carrying the cyanide. This oxygen is usually supplied through the medium of dissolved air in the solution, or through the medium of various chemical compounds, which upon combining with the solution or the ore give off a part of their oxygen. Strange as it may seem, practically all mineral substances are partly soluble in water, especially water carrying alkali or cyanide. The greater the surface exposed and the finer the material is ground, the greater will be the rate of dissolving of the reducing agents from the ore into the cyanide solution. In most cases, if the solution carrying the ore particles is agitated with air, the air will dissolve into the solution faster than will the reducing-agents; but in some cases the reducing-agents will dissolve more rapidly on account of easy solubility or greater surface exposed. It is a dissolving race between the oxygen from the air and the reducing-agents from the ore, and if the reducing-agents predominate, cyanide will not dissolve the gold from the ore. In many cases it will dissolve some of the gold, because in a mass of irregular shape some of the gold particles might be exposed upon the outside surface of a particle of rock;' but if the solution had to penetrate through cracks, the side-walls of which were lined with reducing-agent-

Feb 1, 1912

By Mungo Park, C. Baring Horwood

This paper is intended, in the light of recent investigations, to call attention to some of the essential features of good practice in sampling and mine-valuation. Mine-sampling may be divided broadly into two classes: (1) development-sampling and cornputatioll of ore-reserves; and, (2) stope-sampling and estimation of stope-values. Development-Sampling. It is with development-sampling only that this paper deals— the term development being taken to mean the opening-up of a mine by cross-cuts, drives, connections, etc., preparatory to actual extraction of the ore for milling. In development-sampling the work of the sampler and the consequent estima-

Jan 1, 1909

FRank FirmstoNe, Easton, Pa.: The effect of lead on brass seems to have been recognized by Berthier, and the facts published by him as early as 1818 (Ann. des Mines, 1st ser., iii., 1818, p. 347 et seq.). He there says expressly that copper containing lead makes " dry " (see) brass, and that, for the same reason, blast-furnace

Jan 1, 1898