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By W. B. Price

AT the New York meeting of the American Institute of Mining and Metallurgical Engineers held in February, 1926, W. H. Bassett and J. C. Bradley presented a paper entitled "Exudations on Copper Castings."' The purpose of the present paper, as the title suggests, is to call attention to somewhat similar phenomena which the authors have encountered in brass and bronze. From a study of the examples given, a more-or-less speculative theory of "inverse segregation" is advanced. Protuberances on Admiralty Brass In the rolling mill of the Scovill Manufacturing Co., there have been found quite commonly bars of certain alloys which had a sort of shaggy roughness on the surface due to slight metallic protuberances. No special attention was paid to these until some bars were found on which these protuberances were heavy enough at the bottom of the bars to produce a blistered appearance. A sample of the protuberances was milled off the surface of the bar illustrated (Fig. la) and upon analysis was found to contain 66.66 per cent. copper, 4.02 per cent. tin and 0.03 per cent. lead, whereas the average composition of the bar was 70.21 per cent. copper, 1.21 per cent. tin, and 0.01 per cent. lead. A sample of the shaggy-rough protuberances at the very top of a bar was also analyzed and was found to contain 2.45 per cent. tin, indicating that it was probably of the same origin as the blistered areas. These results were not entirely unexpected for previous analyses of this alloy had revealed that the surface was richer in tin than the rest of the bar. This, of course, is contrary to what we would expect from a consideration of the equilibrium diagram and has been called "inverse segregation." Fig. 16 is a cross-section of a bar through the protuberances on the surface. It reveals that there is a decidedly different structure through the raised areas and seems to indicate that the bar originally solidified

Jan 1, 1927

By Ellsworth Daggett

THE system of pitwork used with the Cornish pumping engine, and which, for want of a better name, we may call the Cornish system of pitwork, consists essentially of a series of plunger-pumps, situated one below the other, in a shaft or incline, the plungers being operated by a rod called the pitman or pump-rod, which must, therefore, extend from the motor at the surface to the lowest pump. The subject will be best understood by reference to Fig. 1, in which k may be taken as typical of the ordinary plunger-pump, in which S is the suction pipe, u, the lower valve situated in the H piece T; v, the upper valve situated in the valve-box O; I, the mounting-pipe or column through which the water is carried to the surface; L, the plunger-barrel, and P, the plunger working through the stuffing-box, and actuated by the branch rod r, which is attached to the main pump-rod, R. The action of the pump is as follows : On the ascent of the plunger, acting now by suction, the water flows from the reservoir through the valve u, into the barrel, L. On the descent of the plunger, the water is forced up through the valve, v, which acts merely as a check valve, into the pipe, I, through which it is, at each successive down-stroke of the plunger, forced upward until it reaches the next reservoir, from which it is taken by another similar pump, and so on until it reaches the surface or drain-tunnel. The pump is obviously only single-acting, i. e., it acts only during one-half of its entire stroke. The weight of water raised during the up-stroke of the plunger is equal to the weight of a column of water whose base is the area of the plunger and whose height is the mean distance between the plunger-face and the surface of water in the lower reservoir, a distance not usually exceeding 12 or 15 feet, and which obviously cannot under the most favorable circumstances, exceed 25 or 30 feet. The water forced up during the down-stroke is equal to the weight of a column of water whose base equals the area of the plunger and whose height equals the length of the mounting column above the mean position of the plunger-face, say from 150 to 300 feet. Almost all of the useful work, therefore, is done on the de-

Jan 1, 1879

By N. Standish

By contrast with viscometry and sedimentation, no actual measurements of the applicability of Stokes' law to steelmaking have ever been reported; instead, the proof for and against Stokes' law has been inferred from the frequently observed phenomenon that inclusions collect in the top scum and the bottom of ingots. As such proof is unsatisfactory, continued reference to Stokes' law in steelmaking, even as a model for calculating the terminal velocities of rising inclusions, should be avoided. In fact, all conclusions that have been reached regarding size, density, and viscosity on the flotation of inclusions could be made more rationally without Stokes' law. A worthwhile exception is that of Mitsche1 who in 1934 used Stokes' law to show not only the expected effects of size, density, and viscosity on flotation but also the beneficial effects of i) melting under a slag layer (now Electro Slag Refining); ii) treating melts with synthetic slags (Ref. 2 gives recent applications); iii) bubbling an inert gas through the melt (recent applications in Refs. 3 and 4); and iv) altering the solid/ liquid interface characteristics. At this point, it should again be emphasized that the boundary conditions for which Stokes' law was derived place enormous restrictions on the law but its application, as noted earlier, can yield useful results in some fields under certain conditions and within well-defined limits. When compared with inclusions, which may be solid or liquid, spherical or irregular, dispersed or coagulated, interacting between themselves and the melt, floating in a liquid which is in a state of motion of varying intensity5 and contained in vessels of various shapes and sizes that may change with time as in a solidifying ingot, the conclusion is obvious-Stokes'

Jan 1, 1969

By AIME AIME

FOR the development of a mine, a shaft of small cross-section is usually sunk, of no larger size than is absolutely necessary. After the mine has been developed and put on a production basis it is a common practice to sink a shaft of larger cross-section for hoisting and use the original shaft for the handling of men and material into the mine. While that ar¬rangement is usually expedient, the small size of the supply cages presents a problem in the handling of ma¬terial. Where a cage is, say, 4 by 4 ft., which is not an uncommon size, all lengthy and bulky material must be handled piece by piece several times from the supply department to the underground stations. Thus drill steel and timbers over 4 ft. long will be loaded on cars at the supply department and wheeled to the shaft, where each piece must be unloaded from the cars and stood up in the cage. They are then lowered to the shaft station, unloaded piece by piece and placed in cars, run to the supply station and again unloaded and stored until called for. In such a case handling becomes a major item in the cost of supplies.

Jan 1, 1930

By AIME AIME

WEST TEXAS, New Mexico and Northern Mexico form one of the most interesting regions in America for geologists and mining men and are full of points of historical and human interest for others. Including as the region does, a representative portion of the high plateau of Mexico, the front range of the Rocky Mountains and the great down-dropping plains of Texas, there is variety as well as interest in the geological and mining problems there to be studied. Gold and silver mining were the pioneer industries and are yet of high rank in importance. Among the papers to be presented at the El Paso meeting of the Institute this month will be two dealing with silver mining and ore treatment at the Shafter mine in Texas, that most un- usual property which has for so many years been the largest mining enterprise in its region. West Texas is now better known for its petroleum and gas, and in another paper will be described the problems involved in uding natural gas for smelting at the well-known El Paso smelter of the American Smelting and Refining Co. In still other papers, presented at the session sponsored by the West Texas Geological Society and cooperating organizations, the general geology of the region, the potash and the sulfur deposits will be de- scribed. At El Paso the refineries of the great com- panics will be available for visits.

Jan 1, 1930

By R. F. Mehl, C. E. Birchenall

R. E. Hoffman and D. Turnbull—The authors have presented evidence which they have interpreted as indicating that the rate of self diffusion is not intrinsically more rapid at grain boundaries than within the grain. Grain-size effects which apparently exist are attributed rather to impurities concentrated at the grain boundaries. In view of our own experiments and the existing evidence, we believe that the support for this hypothesis is not convincing. We have in progress an investigation in which the rate of self diffusion of silver is being measured over an extended temperature range in both single-crystal and polycrystalline specimens. The results of the single-crystal experiments and some preliminary data on fine-grained polycrystalline specimens have already been reported:' and it is anticipated that a complete report will be published in the near future. The self-diffusion coefficient of large-grained polycrystalline silver (1 grain per sq mm) has previously been measured by Johnson" between 730" and 940°C. The diffusion coefficients which we have measured in single crystals (210 plane normal to diffusion direction) agree within experimental error with values calculated from an extrapolation of Johnson's curve down to temperatures as low as 500 °C. However, it has been demonstrated that the overall self-diffusion rate in fine-grained polycrystalline specimens (initial grain size of 0.003 cm) becomes measurably larger than the overall rate in a single crystal at a temperature of 600°C, and the discrepancy between the two rates becomes greater as the temperature is further decreased. In fact, it has been possible to obtain satisfactory penetration curves for polycrystalline specimens using the sectioning technique at temperatures as low as 400°C. At this temperature, the penetration is 50 to 100 times greater in the polycrystalline specimens than in a single crystal. Fisher" has developed an analysis whereby the ratio of the rate of the unit diffusion process at the grain boundary to the corresponding rate within the grain can be calculated from the penetration curves and an assumption as to the width of a grain boundary. This analysis applied to our data indicates that the unit process at the grain boundary is faster by a factor of 10' at 475°C when the grain boundary width is taken to be 5. The silver used in most of these experiments was obtained from the Handy and Harmon Co. and listed as 99.97 pct pure. Preliminary experiments on 99.999 pct silver from the Jarrel-Asch Co. indicate a grain-size effect of the same order of magnitude as in the less pure silver. Nominally, these purities are as good, at least, as that of the carbonyl iron used by the authors, but of course if an impurity effect does exist its magnitude might be very dependent upon the nature of both major and minor constituents. The authors have cited the work of other investigators who have found no grain-size effects. Neither Steigman, Shockley and Nix" nor Maier and Nelson8 were able to correlate self-diffusion coefficients of copper with grain size. However, all their measurements were performed at or above 750°C; and on the basis of our work with silver, no grain-size effect would be expected at temperatures above about 0.7 of the absolute melting temperature unless the grain size were exceedingly small. Likewise, in the investigation of the self diffusion of lead by Seith and Keil,14 the lowest temperature at which the diffusion coefficient was measured in polycrystalline specimens was 207°C, which is still sufficiently high so that the lack of a grain-size effect is not surprising. Finally, in those experiments on iron from which they concluded that there was no grain size effect, Drs. Birchenall and Mehl seem to have no information as to the actual grain sizes immediately prior to and following the diffusion anneal. Without this information, we believe that their own experiments offer little support for their hypothesis. F. S. Buffington, I. D. Bakalar, and M. Cohen—The results given in this paper agree in order of magnitude with those tentatively reported by us.27 However, significant differences exist in the two sets of data, and it may be well to make an explicit comparison. The diffusion studies at M.I.T. were conducted on somewhat higher purity iron (99.98 pct Fe) than the grades used by the authors, but this is undoubtedly not the answer. Fig. 4 shows the diffusion results of both laboratories for the gamma phase, omitting the authors' data on the commercial steels, while fig. 5 presents a similar comparison for the alpha phase. The divergence is much more marked in the latter case than in the former. In connection with the M.I.T. determinations, all of the runs in the gamma range and those above 800 °C in the alpha range were conducted with specimens having a relatively thick (0.002 cm) electrodeposit of radioactive iron. This practice minimizes any possible error due to extraneous diffusion that may occur during the heating to and cooling from the operating temperature. An exact solution of Fick's law for these boundary conditions was used in calculating the diffusion coefficients. At a later time, three runs were made below 800°C, using very thin electrodeposits similar to those of the authors, and the points fell considerably below the values expected from the extrapolation of the results based on the specimens with the thick deposits (compare dash-dot line in fig. 5). However, in the runs with the thin deposits, deviations of 100 pct were found between the individual specimens, whereas the maximum deviation with the thick deposits was less than 25 pct. Accordingly, it is not known at the moment whether the M.I.T. points below 800 °C should be given as much weight as those above 800°C. If this were done, the frequency factor would be of the order of 400 cm2 per sec, which is quite high. In other metals, the frequency factor for self diffusion lies between about 0.1 and 10 cm2 per sec. As the points below

Jan 1, 1951

By Charles Maier

IT has long been supposed that when crystalline materials are com-minuted the energy used in the production of increasingly smaller grain sizes is not entirely dissipated as heat but that a certain portion is "stored" as a part of the internal energy of the material. This portion usually has been called the "surface energy" of the particles. The practical interest of the Bureau of Mines in this subject in connection with the energy requirements of crushing processes has led to the author's attempt to measure the "stored" energy in finely divided calcite by heat-of-solution methods1. The experiments on calcite showed that "storage" of energy could not be proved for this material, because fine grinding caused a lack of chem-ical homogeneity evidenced by loss of carbon dioxide and subsequent adsorption of water on the surfaces of the calcite particles. When thermochemical correction was made for composition changes the cor-rected heat of solution was less for fine material than for coarse. Con-tinuation of the experimental work into the problem of comparing work and heat in the deformation of metallic crystals, where the calorimetric difficulties were less, showed, however, that in the case of copper and aluminum a real discrepancy between work and heat could be shown. similar results had previously been obtained by Farren and Taylor2 and Hort3 and more or less simultaneously with the author's work by

Jan 1, 1936

By Charles Maier

PART I DENSITY AND ENERGY CHANGES IN COLD-WORKED COPPER IT has long been supposed that when crystalline materials are com-minuted the energy used in the production of increasingly smaller grain sizes is not entirely dissipated as heat but that a certain portion is "stored" as a part of the internal energy of the material. This portion usually has been called the "surface energy" of the particles. The practical interest of the Bureau of Mines in this subject in connection with the energy requirements of crushing processes has led' to the author's attempt to measure the "stored" energy in finely divided calcite by heat-of-solution methods1. The experiments on calcite showed that "storage" of energy could not be proved for this material, because fine grinding caused a lack of chem-ical homogeneity evidenced by loss of carbon dioxide and subsequent adsorption of water on the surfaces of the calcite particles. When thermochemical correction was made for composition changes the cor-rected heat of solution was less for fine material than for coarse. Con-tinuation of the experimental work into the problem of comparing work and heat in the deformation of metallic crystals, where the calorimetric difficulties were less, showed, however, that in the case of copper and aluminum a real discrepancy between work and heat could be shown. Similar results had previously been obtained by Farren and Taylor2 and Hort3 and more or less simultaneously with the author's work by

Jan 1, 1936

By Gerald Edmunds

CASTINGS of pure metals and many alloys usually have a coarse-grained structure characterized by long columnar grains throughout the main body of the casting. Frequently, the surface exhibits finer, some-times nearly equiaxed grains, and such grains may also compose other parts of the casting. This paper deals primarily with determinations of the grain-orientation textures of the columnar and surface grains of polycrystalline zinc castings. It includes some results upon a cadmium casting and a magnesium casting. A hypothesis is devel-oped to account for the observations on columnar grains and to use as a basis for predicting orientations in other cast metals. A general description of the position of the columnar grains in castings is that their long axes are approximately parallel to the direction of the thermal gradient during crystallization. Thus, in cylindrical castings the columnar grain axes tend to be radial, and in large flat castings where most of the cooling is through one or both of the large mold surfaces they tend to be perpendicular to the mold surfaces. At the edges and corners the direction of heat flow and there-fore the position of the grains is more com-plex. Actually observation shows that even in castings made in flat molds the cooling seems to be somewhat irregular, since columnar grains tend to emanate from certain areas of the cooling surface, indicat-ing that thermal contact was better there than in neighboring areas.

Jan 1, 1940

By Kent W. Pilz

Wet dust suppression can be achieved by 1) confinement of the dust within the dust producing area with a curtain of moisture, 2) wetting of the dust by direct contact between the particles and droplets of moisture or 3) the formation of agglomerates too heavy to remain airborne, or too heavy to become airborne, by combining small dust particles with each other and with the droplets of liquid. From the standpoint of economy, availability and safety, water is the ideal fluid; however, it is not as effective for dust suppression as when small percentages of specially formulated dust control compounds are blended with it. Performance of dust control com pounds is related to surface active agents and surface activity. In all liquids there is an attractive force between molecules which varies inversely as the sixth power of the distance between molecules. Thus, in the liquid phase where molecules are crowded together, the intermolecular forces are powerful; whereas in the liquid-vapor phase where the molecules are relatively far apart, these forces diminish rapidly. In the body of a fluid there is an uneven distribution of forces resulting in an inward pull called surface tension. The force which keeps two surfaces apart or causes them to coalesce is termed interfacial tension. Fluids of high surface tension exhibit poor wetting, spreading and penetrating qualities. Water has the unusually high surface tension of 72.75 dynes per cm at 20°C.

Jan 7, 1972

By R. V. Norris

THE wage rates and working conditions in the anthracite. region of Pennsylvania have been governed for nearly 20 years by the award of the Anthracite Coal Strike Commission, appointed Oct. 16, 1902, by President Roosevelt. The report of this com-mission, made in March, 1903, was accepted and, with eight modifications made at various dates, has had .almost the force of law, and has kept this great indus-trial region free from strikes for almost a generation. In 1920, President Wilson appointed an Anthracite Coal Commission, and its report, accepted Aug. 30, 1920, governed wage conditions to April 1, 1922. Actually, the agreements have been for terms of two to four years, and lately, in 1916 and 1920, the employ-ees have continued at work pending the negotiation of new agreements which were made retroactive, and which have all been modifications of the original 1903 award. With the expiration, April 1, 1922, of the 1920 award approaching, Mr. Lewis, president, of the United Mine Workers of America, addressed a letter, on Feb. 20, to the operators, suggesting a meeting on March 15; this date was accepted by the latter, with the notation that the time was short. At the meeting, the Mine Workers presented 19 demands, and advised that if a satisfactory agreement was not reached by April 1.a suspension of mining would occur, contrary to the practice since 1916 of continuing work with a retro-active adjustment.

Jan 6, 1922

By George Bell

THE mine and milling plant of Demonstration Gold Mines, Ltd., is near the city limits of Baguio, Mt. Province, P. I. The mine road connects with the main highway to Manila. The nearest railway point is near sea level, approximately 40 miles distant. The Baguio district is very mountainous and has one of the heaviest rainfalls in the world. It is therefore difficult to maintain roads or to impound tailings and mine dumps. All supplies are trucked into the district direct from Manila or the nearest railway point, which means uncertain deliveries and high freight rates. Installation of equipment is difficult and costly. The average elevation at the mine is 4000 ft. and the climatic condi-tions.are ideal except for a three months rainy season. The company generates its own power for mining and milling opera-tions with three 400-hp. Ruston Diesel engines direct connected to 250-kw. General Electric alternating current generators. Labor conditions have been excellent, although at present social security laws are causing some unrest. Labor receives a higher average wage rate in this district than other labor in the Islands. The com-pany also furnishes free living quarters, hospitalization and work-men's compensation. Taxation has been reasonable up to the present time, but some of the new mining legislation may make it difficult to operate and pay dividends. The future depends largely upon the continuation of $35 gold and the political outcome in the Islands.

Jan 1, 1939

By Henry J. Williams

The main difficulty in the determination of silicon in pig-irons containing very high percentages of that element, has been due to their almost complete insolubility in acids, or mixtures of acids. The object of the present paper, which presents no new principle, is to suggest a method of determination which has repeatedly given accurate results, and which obviates completely the tediousness and uncertainty of the usual slow solution in acids. This method has been tried with pig-irons containing from 7 to 14 per cent. of combined silicon, and properly called ferro-silicons. When reduced to an impalpable powder in the agate mortar, an 11 per cent. ferro-silicon was found to resist the action of all acids, or mixtures of acids, with the exception of sulphuric acid of about 1.25 specific gravity. But the action of this acid, even during long continued heating, was very slow, 72 hours being necessary to com pletely dissolve half a gramme of the metal. The complete decomposition of 1 gramme of the metal may, on the other hand, readily he effected in a few minutes by fusion with sodium carbonate in a covered platinum crucible over a blast-lamp —the idea being to dissolve the silicon, leaving the iron in condi tion to be readily attacked by acids. The silicon dissolves as soluble sodium silicate, and metallic iron remains in a very spongy and finely divided condition. The addition of a little hot water

Jan 1, 1889

By A. Coskun, J. F. Elliott

The activity of aluminum in liquid Al-Fe alloys .has been measured by an improved version of the transportation method in which the metallic vapor has been collected by its solution in a metallic condenser. The results can be represented by the equation: log yAl = -3.0(1 - xAl2) (0.6 < XAl < 1.0) This equation applies at 1315°C. MORRIS and zellarsl adapted the transportation method for measuring the vapor pressure of a com- ponent of an alloy at high temperature. We have modified their technique further2 for use with metals that are strong oxide formers. In the present case the method has been applied to the Al- Fe system to obtain the activity of aluminum in the liquid region at 1315°C. Dried ultrahigh-purity hydrogen (Matheson) is the carrier gas. The operations, Fig. 1, of deoxidizing the gas, equilibrating the gas with the sample at 1315";, and then collecting the aluminum vapor are all accomplished within a single, continuous alumina tube to avoid contamination of the system by leaks. De-oxidation to a very low level of PO2 (<10-25 atm) is Obtained by passing the hydrogen through a tightly packed bed of aluminum powder. The temperature of this bed increases to approximately 550°C in the direction of the gas flow. The boat containing three pellets of the alloy is supported on the end of a

Jan 1, 1969

By Joseph Gurland

EVERAL carbide-cobalt compositions were pre-^-5 pared for the purpose of determining the transverse rupture strength of various carbide-binder systems. The binder content was held at 10 and 37 volume pct Co, so as to be representative of low and high bjnder compositions. The carbides used, WC, Tic, TaC, CbC, VC and ZrC, were selected on the basis of availability, knowledge of their properties, and small solid solubilities in the binder metal at room temperature. The methods of preparation and carbon analysis of the carbides are summarized in Table I. The carbides with cobalt added were ball milled, pressed, and sintered. vacuum sintering was used throughout, except for the WC-Cs alloys, which were sintered in hydrogen. The sintering temperatures ranged from 2500" to 2750°F for the low binder alloys and from 2300" to 2550°F for the high binder alloys. Compositions and properties of the sintered com- pacts are presented in Table 11. For the transverse rupture strength, the average and range of the five best samples of each alloy are listed. Discrepancies between the actual and theoretical densities are attributed to carbon deficiencies in some samples. The theoretical densities were calculated by assuming mixtures of carbides of stoichiometric compositions and cobalt. Representative microstructures are shown in Figs. 1 to 6. The porosity was A-2 or better&apos; in all alloys except those with ZrC. A grain size of about 3 p was

Jan 1, 1958

By Robert H. Hafner, Irvin R. Kramer

IN recent years considerable interest has been shown in surface-alloyed metals, particularly those of chromium (chromized steels), which have excellent corrosion [ ] resistance under a variety of severe conditions, and may undergo bending and flanging operations without spalling. An early method&apos; employed to produce a high-chromium case on steel was developed by Kelley in 1921. It consisted of heating a low-carbon steel in intimate contact with powdered chromium in the presence of hydrogen at temperatures sufficiently high to permit diffusion of chromium into the steel. The usefulness of this process was limited because the extremely high temperatures of 1200° to 1400°C. (2200° to 2550 F.) caused excessive grain growth and warpage. Louenstein and Ulmer2 packed iron castings in ferrochromium and com- [ ] mon salt, and heated for approximately three hours at 930° to 1040°C. (1700° to 1900°F.). A recent and more practical method of depositing chromium on steel surfaces has been developed in Germany by Daeves, Becker and Steinberg3-8 and in Russia by Izgaryshev and Sarkisov.9 This process consists of passing gaseous chromium chloride over the steel to be chromized at temperatures of 900° to 1000°C., or packing them in a porous, ceramic material that previously had been saturated with chromium chloride. They reported obtaining a chromized layer, 0.004 in. thick, on low-carbon steels. Later, Daeves4 established a relationship between the carbon content

Jan 1, 1942

By H. O. Hofman

The mining and metallurgical laboratory, as we understand the term in this country, is a place .in which mechanical and chemical working-tests are made on ores, fuels and furnacematerials. It is of quite recent origin. The first laboratory of this kind to be used in connection with teaching was put into operation in 1871 at the Massachusetts Institute of Techilo1ogy. † The idea had already existed in the mind of President W. B. Rogers when he wrote, in 1864, his pamphlet &apos;on " The Scope and Plan of the School of Industrial Science of the Massachusetts Institute of Technology;" but several years elapsed, and an extended visit to the mines and mills of Colorado, Utah, Nevada and California was required before this idea could take a form adapted to the purposes of original research as well as of instruction. The laboratory was given from the first into the charge of Prof. R. H. Richards, who, by improving its methods and enlarging its scope, has brought it to the position which it occupies to-day as the leading representative of its class. Private laboratories for making tests upon ores had previously existed here and there, especially on the Pacific coast, for silver and gold ores; but in the educational field the

Jan 1, 1896

By Thomas T., Read

DESIRABLE as it is to summarize what has been set forth in preceding chapters, the task can only be approached with great hesitation. What follows represents the personal views of the author at the moment of writing, reserving the privilege to change them on more mature reflection or in the light of further evidence. With that reservation they may be stated somewhat as follows. Education for the mineral industries falls into two categories; general education and technical vocational, using the word vocational not in its usual sense but to signify preparation for specific activities, in which sense a law school is a vocational school. Even at the beginning, as indicated in the first chapter, mineral industry education was partly general and, partly technical and that relationship still persists, because technical education requires a firm basis of general education. Our general American system is to provide free public&apos; general education through the twelfth grade, or completion of high-school work, though there are already many technical vocational high schools, and even in a community where nearly all the young people are preparing for entrance to college there will be some who wish to qualify for employment at the end of the high-school course, or even on completing junior high. Our educational system, therefore, has not only to provide education for those who intend to proceed beyond the twelfth grade but also for those who, for a variety of reasons, may wish or be forced to cease full-time education at any level between the first and twelfth grades. This study has been chiefly concerned with the problem of what kind and how much technical education to provide for those who have completed the twelfth grade and who wish to make their living in the mineral industries. The obvious fact that the mineral industries employ all sorts of trained persons,

Jan 1, 1941

Discussion of the paper of EDGAR L. NEWHOUSE, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin: No. 92, August, 1914, pp. 1801 to. 1806. G. C. RIDDELL, East Helena, Mont.-As nearly as I can recall at the present moment, there are only four or five large plants on the continent where the lead on charge is carried in the neighborhood of 40 per cent. These are at Herculaneum, Collinsville, and Federal, Ill.; Trail, B.. C.; and East Helena, Mont. Our object at the latter point is to smelt a maximum amount of Coeur d&apos;Alêne lead sulphides in as compact and self-fluxing a charge as possible, and to this end we are now smelting a mixture that at times carries up to 42 per cent. lead. The monotony of producing the 7,000 tons of bullion shipped each month to. the Omaha and Chicago refineries is relieved somewhat by the fact that the 15,000 tons monthly of Coeur d&apos;Alêne ores that are com-ing to us carry enough zinc to provide the one-half slag used with from 6.5 to 7.5 per cent. zinc clay after day. During the month of March, 1914, three lead furnaces in continous operation, each 136 in. long, averaged 249 tons per furnace clay, exclusive of coke and slag shells, which is smelting at the rate of 5.5 tons per square foot of tuyère area. The

Jan 11, 1914

Aalde, Kaare, (S&apos;40) Box 827, Socorro, N. M. Aase, Glenn D., (S&apos;40) Engr. Experiment Sta., Univ. of Utah, Salt Lake City, Utah. Abadesco, Enrique A., (S&apos;39) Student. College of Engrg., Univ- of the Philippines, Manila, P. 1. Abbott, John L., (S&apos;40) Met. Engr., Engr. Trainee. Wright Aeronantical Corp., Paterson, N. .J. Abbott, Robert H., (S&apos;42). Agricultural & Mech. College of Texas, College Sta., Tex. Abreu, Ovidio M., (S&apos;38) Dept. of Geol., Compauia Cousulidada de Petroleo, Caracas, Venezuela. Acomb, Allen, (S&apos;41) 3921 Chestnut St., New Or¬ leans, La. Adam, Howard W., (S&apos;41) Montana School of Mines, Butte, Mont. Adams, Charles E., (S&apos;42) Uuiv. of California, Los Angeles, Calif. Adams, Charles W., (S&apos;39) Student, Michigan Col¬ lege of Min. & Tech., Houghton, Mich. Adams, H. Travis, (S&apos;39) 310 South 5th St., Bur¬ bank, Calif. Adams, John W., (S&apos;42) Univ. of Texas, Austin, Tex. Adams, Rob L., (S&apos;40) Lt., B. 0. C. No. 12, Fort Sill, Okla. Adamson, Charles R., (S&apos;41) Uuiv. of Utah, Salt Lake City, Utah.

Jan 1, 1942