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By Francis F. Lucas

A microscope objective of given numerical aperture, when used with light of given wave length, has some fixed limit of resolution. This may be expressed as potential resolving ability—the ability to resolve is inherent in the lens but whether this limit is achieved in practice is quite another matter. Nearly 50 years ago Abbe evolved theoretical considerations which indicated that the ability of a lens to resolve detail is directly proportional to twice the numerical aperture of the objective and inversely proportional to the wave length of the light used. It is true, unquestionably, that as the numerical aperture of the objective is increased the potential resolving ability of the lens is increased and likewise when the wave length of the light used is decreased, the degree of resolution is increased. Whether Abbe's formula expresses the exact relationship is not a matter of great concern. It suffices to know that to improve resolution, other things being equal, two avenues of approach are available. Either the numerical aperture of the objective may be increased or the wave length of the light decreased. With the apochromatic system it is possible to employ successfully wave lengths from 400 to 500 uu and still secure reasonably short exposures. The present limit for numerical aperture is 1.40 N. A. although objectives of 1.60 N. A. are now an experimental possibility for metallurgical work. Thus certain well defined limits are set for those who work within the range of the visible spectrum. In order to take advantage of the increase in resolving power which accompanies a decrease in the wave length of light employed, Dr. A. Kohler and Dr. M. Von Rohr of the Zeiss Scientific Staff developed the "monochromats." These are quartz objectives corrected for the single wave length 275 uu which lies in the ultra-violet region of the spectrum. They also developed a series of quartz oculars and a complete photo-micrographic equipment with which to use the quartz optics. Quartz must be used for the optical parts because glass absorbs ultra-violet light almost completely. Thus there was made available about 20 years

Jan 1, 1926

By T. A. Wright

The sampling of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grat) sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases rnuch material can bc sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to incrcase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to makc sorting and grading more difficnlt in turnings, borings, clippings, etc., and conseqllcntly is making sampling of more moment. In tin, lead, alumiinum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosscs, battery lcad, and aluminunl skimmings are ordinarily sold on what is called "metallic button" or "metallic recovery" or "metallic yield." Coppcr and Icad wastcl, howcvcr, is being sold more and more on actual copper and lead contents bascd on sarrlple and chemical analysts. This paper will be dcvotctl chiefly to the sampling of niaterials suitablc only for refining and recovery of one or more of the metals present. The methods described are often bascd on thc fact that but one, metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect thc final copper result, as the "after-melting" assay can be readily calculated to the "bcfore-nltltingl' basis, but if smelter efficiency continues to increase, so that in tiltie zinc, for instance, may be rccovrred on a paying basis, thc method of sampling dirty brass, for example, will have to bc changed also. As a matter of fact, we may cxpect that improved refining proresses will make possible the partial reeovrry of lcad and tin which are now lost

By J. B. Newkirk, D. L. Martin, A. H. Geisler, R. Smoluchowski

A FUNDAMENTAL investigation of the mecha-nism of the ordering reaction and of the accompanying changes in properties has been undertaken, since an extensive study of this process could well contribute to the knowledge of phase transitions in alloys. Cobalt-platinum alloys were chosen for the study since they exhibit interesting and unusual permanent magnet properties.1,2. In addition, the ordering reaction in cobalt-platinum alloys is a convenient one to study experimentally because of the high maximum ordering temperature, the large difference in the X-ray scattering power of cobalt and platinum atoms, and the relative ease with which the alloys can be plastically worked into wire and strip. In the early stages of this study, it became apparent that the published phase diagrams&apos;, &apos; of the cobalt-platinum system contained questionable features, in the region of 40 to 60 atomic pct Co, which were considered in another publication by the authors.4 That portion of the research reported elsewhere on the equilibrium states of cobalt-platinum alloys does not confirm the presence of a previously reported, high temperature disordered tetragonal phase and a low temperature body-centered cubic phase. On the other hand, the structure of the ordered phase is face-centered tetragonal with an atomic distribution analogous to that of CuAu.4 This lattice forms from the disordered face-centered cubic phase in such an orientation that the <100> directions are parallel to the <100> direc-tions of the disordered phase. At compositions other than the ideal 50 atomic pct the ordered phase can exist in equilibrium at high temperatures with the disordered phase. A Widmanstatten pattern of plate-like particles of the ordered phase parallel to (110) planes of the disordered matrix is observed when an initially disordered alloy is held at these temperatures. The temperature range of the two-phase region has been determined for three alloys by X-ray diffraction analyses, microscopic examination, and electrical resistivity measurements, and these results are incorporated with some of those of Gebhardt and Köster in the revised phase diagram of fig. 1. The purpose of the investigation reported here was to examine the mechanism of ordering in co-balt-platinum alloys by X-ray diffraction and metal-

Jan 1, 1951

By Stephen Taber

A VEIN may be defined as an aggregation of mineral matter, more or less tabular or lenticular in form, which was deposited from solution and is of later origin than the inclosing rock. This definition differs from the one found in many text-books in that no assumption is made as to the origin of the space occupied by the vein or the manner in which the mineral matter was deposited. In the present paper the writer purposes to discuss the mechanics of vein formation, and does not wish to begin by begging the question. The origin of ore deposits has been diligently investigated in recent years, but, while much has been written concerning the chemistry of the process, the physical side of the question has received less attention. The source of the ore minerals; the chemical composition of ore-hearing solutions; the relative importance of magmatic and meteoric waters as agents of concentration; and the causes of mineral precipitation have all been discussed at length. On the other hand, little has been written concerning the mechanics of vein formation, and the theories given in text-hooks today are essentially the same as those developed by the early Cornish and Saxon miners. Early investigators often regarded both veins and dikes as igneous in origin, but today the theory that vein minerals have been deposited from solutions, either liquid or gaseous, is firmly established. The latter view is supported by the fact that many vein-forming minerals are not found in unaltered igneous rocks; by evidence obtained in the laboratory regarding the solubility of minerals; by the presence of many ore minerals in hot-spring waters; by the occurrence of some veins in regions consisting exclusively of unaltered sedimentary rocks; by evidence as to the temperature at which some minerals are formed; and by the absence of mineral segregation due to difference in specific gravity. There is still, however, much difference of opinion as to whether certain tabular-shaped &apos;masses should be classed as veins or as dikes. Some of

Jan 8, 1918

By John I. Yellott

Since the days of Newcomen and Watt, when men first sought to turn the energy of fuels to useful purposes, coal-generated steam has supplied most of the power needed for both stationary and mobile applications. The low efficiency and large water requirements of the nineteenth century steam-power plant caused many engineers to turn their thoughts toward more direct means of converting heat into power. As far back as 1791, John Barber secured an English patent on a combination&apos; which he might well have called a "gas turbine." He proposed to generate producer gas from coal or charcoal, to burn it under pressure in air obtained from a reciprocating compressor, and to drive a turbine wheel with the resultant hot combustion products. With the optimism characteristic of the inventor, he hoped that the turbine would not only operate his compressor but also perform useful work. There is no record that Barber ever built his machine, but if he had done so he would have learned that useful power can result from such a combination only when both turbine and compressor are highly efficient and when the temperature of the gas entering the turbine is not far below 1000°F. Hot-air prime movers continued to attract attention, and both Stirling in England and Ericsson in America2 built reciprocating engines that operated with some success upon coal-heated air. The internal-combustion engine, burning liquid fuels, supplanted the hot-air type, and, for the first time, challenged the supremacy of both the steam cycle and its familiar fuel, coal. Liquid Fuels Compete with Coal As the increasing use of the automobile multiplied the demand for gasoline, the supply of residual fuel increased rapidly, and heavy oil declined in price to the point where it became competitive with coal. First in the marine field and later in stationary plants in areas adjacent to refineries, oil began to be widely used. Oil&apos;s greater convenience and higher heating value per pound of weight or per cubic foot of bunker space have caused it to take over much of the marine field. The introduction of the highly efficient diesel engine, capable of burning a fuel that is cheaper than gasoline, again threatened the position of coal, for the operating costs of the diesel became directly competitive with those of coal-burning equipment. In isolated power plants and smaller marine installations, the diesel provided the medium by which oil again successfully invaded fields formerly dominated by coal. The diesel engine, provided with an electrical transmission, found an excellent application in railroad service. The high availability of diesel-electric locomotives, resulting in part from freedom from water

Jan 1, 1947

By John I. Yellott

Since the days of Newcomen and Watt, when men first sought to turn the energy of fuels to useful purposes, coal-generated steam has supplied most of the power needed for both stationary and mobile applications. The low efficiency and large water requirements of the nineteenth century steam-power plant caused many engineers to turn their thoughts toward more direct means of converting heat into power. As far back as 1791, John Barber secured an English patent on a combination&apos; which he might well have called a "gas turbine." He proposed to generate producer gas from coal or charcoal, to burn it under pressure in air obtained from a reciprocating compressor, and to drive a turbine wheel with the resultant hot combustion products. With the optimism characteristic of the inventor, he hoped that the turbine would not only operate his compressor but also perform useful work. There is no record that Barber ever built his machine, but if he had done so he would have learned that useful power can result from such a combination only when both turbine and compressor are highly efficient and when the temperature of the gas entering the turbine is not far below 1000°F. Hot-air prime movers continued to attract attention, and both Stirling in England and Ericsson in America2 built reciprocating engines that operated with some success upon coal-heated air. The internal-combustion engine, burning liquid fuels, supplanted the hot-air type, and, for the first time, challenged the supremacy of both the steam cycle and its familiar fuel, coal. Liquid Fuels Compete with Coal As the increasing use of the automobile multiplied the demand for gasoline, the supply of residual fuel increased rapidly, and heavy oil declined in price to the point where it became competitive with coal. First in the marine field and later in stationary plants in areas adjacent to refineries, oil began to be widely used. Oil&apos;s greater convenience and higher heating value per pound of weight or per cubic foot of bunker space have caused it to take over much of the marine field. The introduction of the highly efficient diesel engine, capable of burning a fuel that is cheaper than gasoline, again threatened the position of coal, for the operating costs of the diesel became directly competitive with those of coal-burning equipment. In isolated power plants and smaller marine installations, the diesel provided the medium by which oil again successfully invaded fields formerly dominated by coal. The diesel engine, provided with an electrical transmission, found an excellent application in railroad service. The high availability of diesel-electric locomotives, resulting in part from freedom from water

Jan 1, 1947

By Richard N. Hunt

Bingham has produced 6 per cent. of this country&apos;s copper. In total production, it ranks fourth among the copper camps of North America, the order being Butte, Michigan, Bisbee, and Bingham. In its annual production, it held that same rank until 1919, when its production was exceeded by the combined production of the Globe-Miami district of Arizona. Bingham has also been a lead camp of the first order. Utah ranks third among the lead-producing states, and its production comes largely from three camps which, in the order of their productivity, are: Bingham, Tintic, Park City. Bingham&apos;s silver production is important, but it does not rank high as a silver producer. Utah owes its rank as first among the silver-producing states to Tintic, a camp 40 miles due south of Bingham. The United States Mineral Resources reports a total production from Bingham for the period 1865-1920 having a gross value of $528,043,432. History of the Bingham District Bingham is on the eastern flank of the Oquirrh range 30 miles southwest of Salt Lake City, from which it can be reached in an hour by auto, or by the Denver & Rio Grande or the Bingham & Garfield railroads. The automobile route is a paved road across the floor of Great Salt Lake Valley, through farming country. The Bingham & Garfield railway leaves the level of Great Salt Lake at the northern end of the Oquirrh range, and in 20 miles it climbs 2100 ft., and deposits the traveler upon a shelf cut in the side of Bingham Canyon below most of the mines, which are farther up Bingham Canyon and its tributary Carr Fork. Below lies the town, a narrow ribbon running for a couple of miles along the bottom of a canyon 2000 ft. deep—an almost impossible site for a community numbering, in prosperous times, 5000 to 7000 inhabitants drawn from all quarters of the globe. Up the canyon and down, and beneath the steep slopes nearby, and beneath the town itself, are the mining operations of over half a century. During the past two decades one mine, the Utah Copper, has become so gigantic an operation as to dominate all other activity in the camp. It has become the greatest copper mine on the continent in production,

Jan 1, 1924

By Pol Duwez, H. E. Martens

The high temperatures encountered in the operation of jet engines have imposed most drastic requirements upon the materials used in their construction. There are two different approaches to the materials problem connected with the design of parts in contact with high temperature gases. The first approach is to use a material which will perform satisfactorily at a temperature comparable to that of the gas. The second approach is to use a cooling system so that the material is maintained at a temperature appreciably lower than that of the gas. Besides the conventional method of cooling by means of a liquid in contact with the material exposed to a high rate of heat transfer, a less orthodox method consists of making the part to bc cooled of a porous material&apos;, so that the cooling fluid can be forced through the pores, In this scheme, the temperature of the coolant moving in a direction opposite to that of the heat flow increases gradually while passing through the porous material, and the coolant forms a protective layer on the surface exposed to heat, This method, referred to as ((sweat cooling," was pro- posed at the Jet Propulsion Laboratory in September 1944, and the experimental work on the preparation of porous metals was started early in 1945. The sweat cooling method opens new lines of research in powder metallurgy by extending the field of application of porous metals. The porous metals available at the present time are used mostly as bearings or filters, and a rather limited number of alloys are made for these applications. In addition, the fabrication of bearings or filters does not require a very close control of the permeability, while in the case of sweat cooling such a control is of primary importance. In designing a sweat cooled part it is imperative to assure a given rate of flow of coolant under certain conditions of Pressure drop. Generally, the Proper pressure drop and the rate of flow of coolant are deduced from heat transfer and design considerations, and consequelltl~ the Permeability of the Porous metal to be used is also determined. It is therefore necessary for the designer to have available a continuous series of porous metals covering a range of permeability as wide as possible. Contrary to the requirements established in the fabrication of filters, the actual pore size of a porous metal intended for sweat cooling is of little consequence, except for its effect on permeability. The tensile strength is likely to be of great importance for some applications. Since the tensile strength of a porous alloy decreases with increasing porosity, an important problem is to develop porous alloys having the maximum permeability with minimum porosity.

Jan 1, 1949

By Charles L. Thomas

A novel, highly sensitive, and reproducible nzetlzod for the determination of hydrogen in solid materials is presented. The procedure requires equilibration of the specimen with hydrogen gas, rapid quenching, and hot vacuum extraction of the dissolved gas with subse-quent quantitative analysis by mass spectroscopy. Good linearity is obtained for the Arrl~enius plots of the investigated metals. The advantages in the use of this method over that of Sieverts aye discussed. The solubility data for copper are in reasonable agveewzent with a considerable number of other inuestigations, wllile those fov silver are considerably lower than previously reported. The first known solubility data for gold are presented. Solubility equations and heats of MUCH of the data which are available on the solubility of hydrogen in various metals and alloys have been obtained by the classical Sieverts method.&apos; The method involves the measurement of a decrease in pressure of a gas in a calibrated system, and the calculated contraction in volume is attributed to the solubility of the gas in the metal sample. The procedure requires several corrections, such as the solubility of the gas in the container walls and the diffusion of the gas through these walls, as noted by Steacie and .Johnson2 and others. In addition, errors may be incurred due to reactions between metal surface impurities, such as oxides, and the saturating gas. The precise calibration of the measuring system where large thermal gradients exist can present additional difficulties. Also, accurate volumetric measurements of small quantities of gas are difficult. Many of the objections to the Sieverts method were overcome on solid materials by Ransley and ~eufeld,~ who first saturated the metal with hydrogen and performed a subsequent extraction and measurement of the gas by chemical means. Eichenauer and pebler4 and Eichenauer, Kiinzig, and pebler5 measured the diffusion coefficient and solubility by following the degasification of a sample as a function of a rate of increase in pressure in a previously evacuated system. Here again, however, the procedure involves many of the corrections of the Sie-verts method. The present investigation deals with the solubility of hydrogen in solid copper, silver, and gold by a technique which eliminates many of the aforementioned corrections and possible errors. This procedure requires equilibration of the specimen with gas, rapid quenching, and hot vacuum extraction of the dissolved gas with subsequent quantitative analysis by mass spectroscopy. EXPERIMENTAL Two completely separate systems were employed to accomplish first, the equilibrium saturation of the sample and second, the extraction of the dissolved gas. Saturation Apparatus. The saturation apparatus, illustrated in Fig. l, consisted of a vertically mounted quartz tube with a three-way valve for vacuum or hydrogen near the top and an outlet near the bottom leading to a butyl phthalate seal. The bottom end of the tube was terminated with a joint accommodating an O-ring sealed "Asco Stirring Gland" (The Emil Greiner Co.). This gland facilitated movement of the thermocouple without introduction of air into the system. The upper portion of the tube (above the furnace) was water-jacketed. A Welsh 1405-B mechanical pump provided the necessary system evacu-

Jan 1, 1968

By Andrew W. Jenike

STORAGE AND FLOW Introduction The layout and design of a bin or stockpile for bulk solids should assure reliable feed at the required time and rate without spillage and, when required, without segregation and degradation. The typical procedure in the design for gravity flow follows these steps: 1. The bulk solids to be stored are identified and the range of moisture content, temperature, feed rate and time of storage at rest, as well as the storage capacity, are specified. The materials of construction of the hopper, that is of the converging part of the bin, are decided upon. Hopper liners and coatings to reduce wall friction are considered. 2. The flow properties of the bulk solids and the friction angles against the wall materials are measured for the expected range of conditions. 3. The width of a slot outlet needed for reliable flow of each solid under the full range of conditions is determined from the tests. This dimension is an explicit measure of flowability of a solid. The widest slot determines the critical solid and the critical conditions. 4. A suitable feeder of size sufficient for the widest slot outlet is selected. 5. On the basis of the measured wall friction angles, a suitable wall material is selected and a mass flow hopper is designed to ensure reliable and uniform flow of solid into the feeder and to minimize the load on the feeder. The mass flow hopper may extend upward to the intersection with the cylinder thus producing a mass flow bin. Alternatively, the hopper may terminate at a height equal to a few widths of the outlet and then expand at a less steep slope in its upper part in order to save headroom, or it may terminate in the flat bottom of a bin or stockpile. The choice depends on the flow properties of the solids and the size of the bin or stockpile. 6. The design of the bin is completed for the specified storage capacity. Multiple hoppers and

Jan 1, 1982

By Donald C. Barton

Success in the use of the Eötvös torsion balance method of mapping geologic structure depends largely on the accuracy in the interpretation of the observed results. Skill in that interpretation depends (1) on the knowledge of the types of the variation of gravity, the gradient of gravity horizontally, and of the differential curvature produced by bodies of different sizes, shapes, dimensions, and densities; (2) on the knowledge of the possible types of structural bodies which might produce the observed anomalies; (3) on the empirical knowledge gained by experience not only in the geological interpretation of torsion balance surveys, hut of interpretations of inadequate geological data; and (4) on a knowledge of the possible and probable types of geologic structures in the area of the survey. The knowledge of the anomaly which a known body will produce and conversely the knowledge of the body or bodies which will produce a known anomaly may be gained by empirical experience and by mathematical study. The knowledge gained by empirical experience is fragmentary and inexact. The geology of most structures actually is known very superficially. The surface geology may be known accurately. If the structure is petroliferous, the subsurface geology of the oil field will be known down to 3000, 4000, 5000 ft. or in a few oil fields down to 7500 ft., but the deeper geology will be unknown and the metamorphic, igneous, or massive limestone basement below the reach of the drill may contrast sharply in density with the overlying sediments. Away from the oil field, the subsurface geology is known only from scattered drill holes, which do not go to the basement. A fair but not necessarily accurate knowledge of the geology of the nonproductive area can be obtained by correlation of the wells but the degree of its accuracy in general is proportional to the density of the occurrence of the wells. The geology below the bottom of the wells however is unknown. An anomaly mapped by the torsion balance is the sum of the effects of the contrasts in mass of its whole geologic surroundings. If the dimensions of a body of abnormal density are large enough, depth or distance makes no difference in the effects on the gradient and differential curvature; and as a matter of fact, in many places, the basement and irregulari-

Jan 1, 1929

By George S. Rice

A problem of possible subsidence of the surface from mining operations, which might have had disastrous results, arose in 1913 at the Brier Hill mine, of the Penn Iron Mining Co., near Norway, Mich., now managed by Pickands, Mather & Co. for the Bethlehem Steel Co. A double track and sidings of the Chicago & North Western Railroad passed over part of the mine, and if subsidence had reached the surface it might have affected the stability of the tracks. The chief purpose of this paper is to record the facts disclosed by investigations of underground movement from 1913 to 1919, when the tracks were moved, and subsequently at intervals, as engineering data of value from mining carried on below the tracks in the steeply pitching lenses. A secondary purpose of this paper is to describe a novel method for determining the rate of speed of upward breaking above the mine excavations. This method was found effective and might be used elsewhere under similar conditions. The mine workings under consideration were developed from the Brier Hill shaft, which was circular, concrete-lined, 14 ft. in diameter and about 900 ft. deep. They extended about 800 ft. westward from the shaft, and nearly parallel to a corresponding length of the railroad tracks. The highest part of these workings was at a depth of 400 ft. below the tracks (Figs. 1 to 12). The mining company had the right to remove the ore, the railroad assuming that the surface would be supported. Finally, without legal controversy, an amicable adjustment was reached as to what should be done to lessen or obviate the hazard of subsidence. Method oF Mining Before the problem became acute, the mining company, to decrease the possibility of subsidence, had been mining the part of the orebody that lay under the tracks by a room-and-pillar system, back-filling with

Jan 1, 1934

By P. D. Gorsuch, D. L. Newhouse, Irvin R. Kramer

ALTHOUGH many methods have been suggested for the calculation of tensile strength and yield point from chemical composition, their usefulness has been limited to a particular cooling rate or section size. Further limitations have been imposed by failure to take into account many of the alloying elements that exert a considerable influence on the tensile strength or yield point. These systems, nevertheless, have filled an important need in many instances. The value of a system for the calculation of the tensile properties from the chemical composition and cooling rate is that it permits the prediction of the effect of alloying elements and heat-treatment on the mechanical, properties, so that more efficient use of alloying elements may be made. Furthermore, it aids in the choice of steel for a given application and tends to decrease the number of steels that otherwise would have to be tested. It is the purpose of this work to present a method of calculating tensile strength and yield point from the chemical composition and to suggest a method of correlating the tensile-strength and yield-point factors and cooling rate. Steelmakers have been interested for many years in the calculation of the tensile strength of hot-rolled steels. Quest and Washburn&apos; summarize several of the attempts that have been made to devise formulas. They show the inadequacy of each of these formulas and present one of their own. It is apparent from their work that a simple additive equation of the type TS = A + BX + Cy + DZ + ? ? ? , where A, B, C, D, etc. are experimentally determined constants and x, y, z, etc., are the percentages of alloying elements present in the steel, is not adequate to analyze fully the situation encountered in the calculation of tensile strength. For example, it was found that the difference between the calculated and observed values became progressively greater as the carbon and manganese contents were increased. Therefore, the effect of manganese was given as a function of the carbon content. Grossmann,2 in his work on the hardenability of quenched steels, and Walters,3 in his method of calculation of tensile strength of normalized steels, present two cases in which multiplying factors were successfully used to express the combined effect of alloying elements. The factors in both cases were obtained from the fractional increase in hardenability or tensile strength with increase of alloy content. Yield point often is more important in design than tensile strength. For quenched and tempered steels a linear correlation exists between yield and tensile strength .4 This is not true, however, for normalized

Jan 1, 1946

By H. D. Newell

Jan 1, 1938

By H. D. Newell

Jan 1, 1938

By G. D. Van Arsdale

This paper describes a series of experiments leading to the development of a method for leaching the mixed ores of the Inspiration Consolidated Copper Co., containing chalcocite and silicates of copper, by the use of solutions acidified with sulfuric acid and carrying ferric sulfate. Iron is added to the solutions and ferric iron is regenerated electrolytically to a percentage high enough to act as an effcient solvent. The decreased yield is partly compensated for by a higher current density. An important problem in modern copper metallurgy, particularly in the Southwest, has been to obtain good recoveries from what are commonly known as mixed ores; that is ores in which the copper occurs partly as oxide and partly as sulfide compounds. The dividing line between mixed ores and ores commonly accepted as concentrating is not definite. In other words, much ore now being concentrated carries considerable copper in non-sulfide form, on which recoveries are not so good as on ores carrying less of these constituents. While treatment by concentration may be commercially profitable on ores carrying oxide copper within certain limits, there are large deposits for which the application of concentration could not be considered, and yet which have not been considered amenable to leaching because they carried too much sulfide. The Inspiration Consolidated Copper Co. has large amounts of such mixed ores, and this paper is an account of the experimental work by which a method was developed for their treatment, and for which a large plant is now being erected by the Inspiration Co. It is not claimed that the method is a general solution of the problem of mixed-ore treatment but it is apparently well adapted for leaching the ores of the Inspiration Co., for which it was designed. The work done has covered preliminary laboratory and test-plant investigation, and a pilot-plant run, extending from March to the middle of December, 1923. Thoroughly consistent and satisfactory results were obtained continuously for more than six months in the pilot plant; and it is believed that the results and probable costs that can be had on a large scale have been definitely proved. The method, however, was designed for local conditions; and while the basic principles are general, there are ores on which it will not work and other ores for which considerable modification may be required.

Jan 1, 1926

Andrew Carnegie, America&apos;s best-known ironmaster and philanthropist, died at his home at Lenox, Mass., Monday, Aug. 11, after a three days&apos; illness. A pioneer in the steel industry, he introduced into this .country the Bessemer process And formed the plans that have resulted in this country&apos;s supremacy in the steel markets of the world. Known throughout the world for his, gifts, he is also known to engineers as the donor of the home of their National Societies and as the founder of the Carnegie Institute of Technology, of Pittsburgh. For many years, also, he was an honorary member of the American Institute of Mining and Metallurgical Engineers, the American Society of Mechanical Engineers, and of the Engineers Club of New York. What he considered the secret, of his success is shown by the epitaph he wrote for himself, "Here lies a man who knew how to enlist in his service better men than himself." He was buried Thursday, Aug. 14, in Sleepy Hollow Cemetery, Tarry-town, N. Y., the funeral services being private, in accordance with his wish.

Jan 9, 1919

By W. P. Z. German

Some attention should be given to definitions. The term "unit operation " may have at least two meanings. One meaning is the merging of titles and the development and operation of the unitized area, as if it were one tract of land held under a single oil and gas lease, according to a definite program intended to accomplish a maximum recovery from the pool as a whole at a minimum of cost. It is incomplete when the royalty owners do not also merge their titles to their oil and gas rights in the area, and is complete when they do. The other meaning is not accompanied by any merger of titles, but the development and operation of the area is in accordance, as nearly as reasonably practicable, with such a program. This second conception may be nothing more than a cooperative development and operation plan, but in this paper it is regarded as more than that. If there cannot be unit operation without a merger of titles, it would seem that the state cannot require unit operation, for it cannot require a merging of titles; but if it may consist in requiring each and all of the leaseholders to develop and operate or to submit to a development and operation according to some such common plan as is referred to above without at the same time requiring a merger of titles, it would seem that unit operation may be required by the state. Whether the states have this power is the subject to be herein considered. If the state can so bind the several lessees, it also can so bind the several lessors. The writer does not know what would be an ideal plan for the development and operation of a pool; but it takes into account the fact that the accumulation of gas and oil is not uniform throughout the formation; that often free gas, highly compressed, occupies the upper portions of the reservoir, the oil with compressed gas in solution coming next in order; that at places oil is not overlain by free gas, and sometimes there are peaks where free gas is not immediately underlain by any oil; and the fact that these substances are held under a uniformly distributed pressure, generally referred to as "rock pressure." It also recognizes that the most efficient utilization of this naturally existing reservoir pressure in the recovery of the oil requires that there be no operation of wells completed into areas where gas only has accumulated, for this diminishes the

Jan 1, 1931

By H. S. Coe, G. H. Clevenger

Engineers have long recognized the desirability of correlating the data obtained from small-scale slime-scttling tests with commercial work as carried on in large tanks. This need, though most apparent in designing new installations, frequently arises also in existent plants, since a large range of experimental work can be performed without interfering with regular operation. General Settling Phenomena In order to develop rational methods of laboratory testing, it becomes necessary to study the general phenomena of settling. Since it was desired to give the public the benefit of these methods at as early a date as possible, together with the knowledge of the general principles of slime settling necessary for a clear understanding of the laboratory tests, we have ventured to discuss the subject in so far as brought out by the work which we now have under way. We realize that certain of our preliminary conclusions may be subject to modification, but it seems probable that, with but few exceptions, the general laws enunciated will cover the settling behavior of all pulps encountered in metallurgical plants. However, it must be recognized that there is still a vast amount of work to be done upon certain phases of the subject; therefore, at this time we will attempt only a discussion of the behavior of ore pulps during the process of settling or dewatering, under certain given conditions. The laws and principles controlling these conditions are not fully established, so that a complete discussion of them will not be attempted in this paper. In metallurgical practice, slime pulp consists of water, finely divided sand

Jan 1, 1917

By Ralph A. Sherman, J. M. Pilcher

BY surface treatment of coal is meant the application of a material, either solid or liquid, to the surface of pieces of coal. The purposes of surface treatment are varied. They may be to identify or "trade-mark" the coal, to modify the burning characteristics, the coking tendencies, or the behavior of the ash, to prevent the freezing of wet coal, or to control the dust. The control of dust is the usual purpose of surface treatment. TRADE-MARKING COAL The application of color to the surface of coal for the purpose of identification and registration of the trade-mark has been practiced to some extent. In 1928, the Glen Alden Coal Co. began to color its coal and adopted the trade-mark, "Blue Coal." The Old Ben Coal Co. later followed a similar practice with "Green Coal." A commoner means of identification of coal has been the stenciling of designs or pasting labels on large lumps or in the distribution of small cardboard tags through the smaller sizes. The details of the method used to color coal have not been revealed. Usually all of the coal is not treated, because of the expense. Only enough pieces are colored to show clearly when distributed through the coal.

Jan 1, 1943