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By R. W. Raymond

HAVING had recently the opportunity of examining a transit and a plummet-lamp, manufactured by Messrs. Heller & Brightly, of Philadelphia, and intended for the use of mining engineers in under

By Charles Wert

THE diffusion and precipitation of carbon and nitrogen in a iron have previously been investigated using the internal friction as a measuring tool.' Most of this work has been done on rather pure iron; no effect was observed which would indicate that either of these phenomena is affected by the rather small amounts of impurity found in these samples of iron. Fastz observed, however, that both the diffusion rate and the aging properties of nitrogen in iron were sensibly changed by the addition of Vz pet Mn. The diffusion rate at a given temperature is reduced and the nucleation of nitrides is apparently changed somewhat. He observed no such changes for carbon in this alloy. Later Dijkstra and Sladek" extended these observations on nitrogen to other alloys of iron. They found that metals other than manganese also influence the behavior of nitrogen in iron; chromium, molybdenum and especially vanadium affect the diffusion and precipitation of nitrogen even more than manganese does. Their results have been verified in all essential details by this author, who finds in addition that small additions of nickel have about the same effect on the diffusion of nitrogen as the same amount of manganese. The present work was undertaken to study the effect on carbon in iron of these alloying elements. The alloys used had two sources. The material used as a "standard" (designated Fe in this paper) in the measurements was some iron supplied by J. K. Stanley, of Westinghouse Electric Corp., who reported 0.01 pct 0, as the only major impurity. He also made up an alloy of 0.26 pct Ni and one of 0.9 pct Mo using this same iron as a base. They were supplied by him in 2 lb billets, which were sawed into rods and cold formed into 0.030 in. wires for measurement. The alloys of chromium, manganese, and vanadium were prepared by the metallurgy section of the Institute for the Study of Metals, University of Chicago, by adding these metals in turn to vacuum melts of National Research Corp. iron. The small castings prepared in this way were also cold formed into 0.030 in. wires. After these wires had been prepared they were decarburized for 30 min at 730°C in wet Hz. After this treatment, no trace of carbon (as measured by internal friction) could be found. All specimens were then carburized for about 15 min at 710°C and water quenched. By this treatment the internal friction at 40°C was raised to a Q-' ~ 0.015. The diffusion of carbon in these alloys was studied by observing the shape and position of the internal friction peak at 0.9 cycles per sec. These measurements were made using a torsional pendulum in a manner described earlier.' The data are plotted in Fig. 1. It is seen that there is no apparent difference in internal friction between the various alloys. This is in marked distinction to the broadening and shift-

Jan 1, 1953

By R. O. Williams

A recent article by Chernock, Singer, Mueller, and Beck 1 which supports the use of the integral of I sin $ d$ for comparing fiber texture data does not settle what happens to I sin ø as ø approaches zero, where I is the diffraction intensity for poles oriented 0 deg from the fiber axis. They indicate that they believe that it should approach some constant value (that is, I increases without bound) and the fact that in reality it does not was a result of the diffraction

Jan 1, 1960

By S. V. Krusiewski, J. W. Gabelman

Regional metallogenic zones and areas of equal paragenetic range have been interpreted from a compiled metallogenic map. of Mexico. Mineralization gradients of the pattern subsequently identified extend inland from coastal zones of high-temperature mineralization, and join in a central longitudinal zone of relatively low-temperature mineralization, apparently leaving no zonal room for lowest temperature deposits. The striking regional zoning pattern can be correlated with regional deformation gradients of similar position and orientation. The gradients represent at least three major orogenic cycles in two structural belts. Paleozoic structural belts existed along each coast with deformation gradients diminishing inland toward a narrow, central peninsular craton. The Mesozoic-Tertiary Mexican (Cordilleran) belt covered the entire country with a gradient oriented toward the Gulf of Mexico. Most ore deposits in this belt are of Tertiary age, although Tertiary mineralization gradients seem to have "inherited" the pattern left by Paleozoic tectonic gradients. Mineralization gradients can be used to identify the regions most favorable for the occurrence of selected metals. A metallogenic province is characterized by particular proportions of various metals, and the relative proportions can vary from province to province; but within any province the same intensity of mineralization would produce similar deposits in different places. Declining intensity of minetalization produces different kinds and sizes of deposits in zones that are concentrically arranged around sites of strongest rock alteration. On a regional basis, districts of similar average intensity of mineralization occur in zones that generally parallel some tectonic grain with the result that tectonic deformation has been designated a principal cause of mineralization. Variations in the type and intensity of deformation would determine the type as well as size of metal deposits. Mexico is especially favorable for such a study be- cause of its great abundance and variety of epi-genetic mineral deposits in various lithologic, structural and tectonic environments. The concept is also useful in recognizing portions of Mexico favorable for the occurrence of specific metals. METALLOTECTONIC ZONING IN MEXICO Theory: In studies of individual districts and groups of districts throughout North and South America, areal zoning of metal deposits generally seemed to respond to the paragenetic sequence of iron, gold, copper, zinc, lead, silver, antimony and arsenic, gold and fluorite. However, the definition of district zones is greatly obscured by contemporaneous or rhythmic deposition of metals, especially in the middle of the paragenetic range, and by the common superimposi-tions of different generations of metals. Zones could usually be distinguished only for groups of metals, such as early precious metals, base-metal sulfides, sulfosalts and late precious metals. The best defined zoning in a district is normally the spatial separation of the greatest volumes of altered and metallized rocks.' Exceptions are districts representing the high- and low-temperature extremes of the mineralization range where the former creates a matrix for the latter. In most districts the total quantity of alteration products is greatly in excess of, and appears to be roughly proportional to, the total quantity of metallization products. Subsequent to the bicomponent nature of each district, the most important mineralogical feature is the great excess of one to several metals or minerals which results in a district identifiable as one of predominantly gold, copper, lead-zinc, fluorite, etc., although a great variety of other elements may be present. The para-genetic range for the abundant elements in any district is only a portion of the entire possible range for all the elements representing the complete process throughout the region. Early during investigations of this type, it became apparent that the consistent bicomponent character of districts allows two methods for studying epi-genetic mineralization patterns. One is to identify and plot altered rock "pipes,"* which are easily recognizable in the landscape by their anomalous

Jan 1, 1969

By Dale K. Fields

With today's technological advances in mineral processing equipment, there is an increasing demand for accurate system control. This can only come about through representative sampling. The purpose of this paper is to guide in the selection of sampling equipment and outline design parameters for the cutters used in dry and wet sampling without adding redundant mathematical probability formulas. Special attention will also be given to the equipment wed in conjunction with samplers and sampling system, such as feeders, crushers, chutes, launders, and controls.

Jan 1, 1980

Jan 1, 1947

By M. Cross

INTRODUCTION The development of refining processes involving gas injection into liquid metals has seen the evolution of a variety of designs [I]. During the last few years or so the top, bottom and side blown processes have, essentially, been combined to produce a series of mixed gas blowing schemes (eg. the LBE [2,3] and LD-OB processes [4,5]). Although, a variety of mixed gas blowing processes have been carefully engineered and recorded operational experience now attests to their effectiveness, optimising their design and operational performance is another matter. Detailed process analysis of such operations is impeded by the complex nature of the physical and chemical processes involved: . fluid flow behaviour of the liquid metal and injected gases, . chemical reactions in the vessel, . mass and heat transfer within the fluid phases in the vessel, . influence of the geometry (eg. location of the tuyeres, etc.), . monitoring the operational performance. By and large, design and operating parameters evolve from a combination of laboratory scale experiments, pilot plant work and, of course, practical engineering experience. Conventionally, the gas-liquid system used to model the industrial process is air-water, for a number of valid reasons including – . visual demonstration plus geometric and (to some extent) dynamic similarity, . the fact that the system demonstrates, at least, qualitatively many of the complex features of gas injection - interaction between the gas and the liquid - the nature of the gas flow behaviour - qualitative indications of mass transfer rates Important experimental contributions to the understanding of gas liquid systems include the work of Brimacombe [6], Wraith [7], T.Robertson [8], D.Robertson [9], Guthrie [10] and Szekely [11] (these references provide starting points to identify the major published work in this area). Although air-water systems have been instrumental in providing a great deal of qualitative insight into the fluid flow behaviour of the processes, reliable quantitative predictions are more problematic. A number of workers (notably Brimacombe and colleagues [6, 12])have demonstrated that different gas-liquid systems can lead to wide variations in behaviour. Other limitations of physical modelling include the assumptions of isothermal flow, scale- up of turbulent flow behaviour and the inability to directly include the effects of chemical reactions. The above limitations in physical modelling, therefore, yield a natural role for mathematical modelling provided that it can be made comprehensive enough whilst remaining cost-effective. The major physical processes involved in gas injection systems may be summarised as . behaviour of the gas envelope structure in moving through the liquid metal . the global movement of the liquid metal . momentum interaction between the liquid metal and the injected gas . heat transfer and mass exchange via the chemical react ions. The behaviour of gas envelopes forming at a tuyere and then moving through the liquid has been investigated thoroughly by a large number of workers. Such models are generally based upon simple physic- al concepts derived from visual observation. An early model by Davidson and Schuler (DS), based upon a force balance between the liquid inertia and a combination of the bouyancy and momentum forces on the envelope, has proved to be a useful tool in predicting bubble volumes at detachment [13]. The DS model has been successfully modified in a number of ways [14-17] to cope with heat transfer and reactive transfer rates, etc. Furthermore, the basic ideas summarised above have also been confirmed on industrial converters by both Guthrie [I8] and Brimacombe [19]. Models have also been developed to predict the behaviour of the "chemical" component of some gas-liquid systems. However, one thing is clear; all gas-liquid reactive systems are governed by the degree to which effective mixing occurs. As such, the processes are dominated by the behaviour of the heat and mass exchange of the two phase fluid flow system. It is the pattern of movement of the turbulent liquid metal plus its interaction with the injected gas which must be predicted reliably, if sufficiently comprehensive comp-

Jan 1, 1984

By G. R. Gardner, D. H. Davis

INCREASING realization of the importance of dust control, and the recommendations of various agencies, have led the mining industry to become actively concerned with this problem. The background and necessity for adequate dust-suppression measures have been discussed in a number of publications, including those of the U. S. Bureau of Mines, and the use of spray water to reduce dust at the face and on roadways has been recommended. The problem resolves itself into obtaining adequate dust reduction at a reasonable cost. Inasmuch as the term "adequate dust suppression" has never been clearly defined, nor have permissible limits of dustiness (in terms of dust count) been established, it is apparent that any method selected may be required to meet additional demands. Until the industry has been given some indication of permissible limits of dustiness, no permanent solution is possible. Progress will be somewhat handicapped until such information is available. In addition, dust reduction must be obtained without the addition of any excessive moisture to the coal, since consideration must often be given to: I. Quality standards, particularly reduction in heat value. 2. Handling characteristics, particularly in regard to unloading from railroad cars and bins. 3. Application of dry methods of coal cleaning. 4. Necessity for fine screening within specified limits of oversize and undersize. Little detailed information is available as to the advantages and disadvantages of the several methods of water distribution, the location and protection of sprays, operating data on pressure, quantity of water, and so forth, and results obtained. In 1940 an investigation was undertaken to determine and evaluate the principal factors involved. This paper constitutes a progress report on this work and cannot in any way be regarded as complete on any one of the several phases. CLASSIFICATION OF DUST SOURCES The various sources of underground dust may be classified as primary or secondary. A primary source is one associated with appreciable degradation of size, that is, where the greater part of the actual fines capable of becoming air-borne dust are produced. A secondary source may be considered as one in which the greater part of the fines have been produced at some previous operation and are in such condition that they can be dispersed as air-borne dust. These conceptions appear to be of practical significance, as experience indicates that when dust is controlled at the primary sources the importance of secondary sources is minimized. For these reasons, investigations to date have been concerned principally with the primary sources of dust, and this paper is concerned particularly with one of these-namely, undercutting. In accord with the foregoing definitions, the sources to which the following opera-

Jan 1, 1942

Jan 1, 1967

By Lewis W. MacNaughton

The North Texas district, as herein defined, includes the counties of Archer, Baylor, Clay, Cooke, Foard, Hardeman, Knox, Montague, Wichita, and Wilbarger. This area covers generally the crest and south flank of a system of buried mountains known as the Red River uplift. The oil and gas accumulations along this feature arc in traps, which, although localized by structures incident to the regional uplift, are usually modified by stratigraphic changes in the sediments. Excepting the fields in southeastern Baylor, southern Archer, and southwestern Clay counties, all the fields within the district are on this Red River uplift. These exceptions, which have the same type of oil and gas accumulation as the other fields, are on the extreme north end of the Bend arch, which is a broad anticline plunging northward from the Llano uplift in central Texas to Archer County. The larger part of past oil and gas production has come from Pennsylvanian strata, with less important amounts from the Permian, and minor but increasingly important quantities from the Ordovician. Developments during 1939 With the later stages of development being reached in the K.M.A. field during the first half of the year, some 400 fewer producing wells were drilled in North Texas in 1939 than in 1938, when some 1750 wells were drilled. Despite this decrease in activity, production in 1939 increased about 3½ million barrels over 1938 figures, and at the end of the year the oil reserves were somewhat larger than on the first of the year. As is usually characteristic of the district, this resulted from the discovery of a large number of relatively unimportant fields. Owing principally to no appreciable abatement in wildcat drilling, more new fields and extensions to old fields were discovered this year. Although none of these discoveries was of such magnitude as to be important to the oil industry, the new developments in Montague and Cooke Counties portend greater and probably more important operations in these areas.

Jan 1, 1940

By T. S. Plaskett

A striated structure perpendicular to the growth axis was observed by the copper-decoration tech-nique in dislocation-free, .float-zoned silicon crystals. The striations, which were spaced about 100 p apart, fitted the relationship d = f/u , where d is the spacing, f is the growth rate, and u is the crystal rotation rate. Each stria was resolved into an UNDOPED silicon crystals pulled from quartz crucibles by the Czochralski technique usually exhibit a striated structure perpendicular to the growth axis.'-' This structure has been attributed to oxygen segregation, with the oxygen being introduced from the quartz crucible. If the crucible is rotated, the level of oxygen contamination has been reported as high as 10° atoms per cu cm.10 These striations are similar to solute striations commonly observed in doped Czochralski-grown crystals. The periodic nature of the striations is caused by a periodic variation in the growth rate",12 which is attributed mainly to thermal gradients in the melt.13 A finer striated structure14 attributed to constitutional supercooling is sometimes observed between the coarse striae. The oxygen striations have been observed by infrared transmission techniques,' by the copper-decoration technique,' by X-ray diffraction microscopy,6-8 and by 9 p absorption measurements3 on crystals pulled from the melt both with and without dislocations. In this investigation float-zoned dislocation-free crystals were examined by the copper-decoration technique. The level of oxygen for float-zone material is less than 1016 atoms per cu cm the lower limit of detection by 9 p absorption measurement. EXPERIMENTAL TECHNIQUE The crystals were grown by the float-zone process with the rf heating coil outside of the quartz envelope containing the silicon. All float zoning was done under an atmosphere of purified helium. The Dash technique15 was used to grow the crystal dislocation-free. This involves growing the crystal initially with a diameter between 2 and 3 mm and at array of starlike precipitates of copper. The strucLure was not .found at the surface tor a depth of about 1.5 mm, or in a region of similar width ahead of a dislocation network. The structure is postulated to consist of vacancy clusterings or dislocation loops. very rapid rates, about 20 mm per min, for a distance of about 3 cm. The diameter of the crystal is then increased to the diameter of the source of silicon, which in this case was about 19 mm. Because of the arrangement of the apparatus, the zone was passed downward rather than upward, contrary to the standard float-zoning practice. Also, the source was rotated rather than the seed. ziegler17 has made dislocation-free crystals by a similar technique but has passed the zone upwards. The starting material was zone-refined and had a p-type resistivity of 150 ohm-cm. The major impurity was boron; the total impurity excluding the boron was reported by the supplier (Dow-Corning) to be typically less than 2 x 1013 atoms per cu cm. The crystals were examined by the Dash copper-decoration technique18'19—a method in which about 10" atoms per cu cm of copper are diffused at a temperature between 900" and 1000°C into silicon which is then quenched to room temperature. On quenching, the copper precipitates on crystalline defects which are then visible when viewed by transmission infrared microscopy. The photomicrographs shown were taken either of the infrared image tube screen or directly on infrared film. All sections prior to decorating were chemically polished and, for some sections, given a sirtlZ0 dislocation etch-pit examination. After decorating, the samples were mechanically polished. RESULTS A photomicrograph, taken in transmission of a decorated cross section, is shown in Fig. 1. The portion of the section shown is near the surface of the crystal. The entire cross section showed no dislocation etch pits after being given a Sirtl etch treatment. It is seen that the copper precipitated randomly. Each precipitate, as has been reported by others, was found to have a starlike structure.

Jan 1, 1965

By W. A. Hoyer

A pulsed high-energy neturon-induced spectral logging tool has been built and field-tested. The reaction of deuterium on tritium is used to generate pulses of 14-Mev neutrons. By detecting only the prompt gamma rays produced by neutron inelastic reactions in the formation, the presence and relative abundance of carbon, oxygen, calcium, silicon and other important elements may be ascertained from a gamma-ray spectrum. Gamma-ray spectra obtained in a shallow test well and in experimental field use show that it is possible to identify formations and their contained fluids. INTRODUCTION The penetrating gamma rays from naturally occurring radioactive elements in subsurface formations have been used for a number of years in well logging as a means of characterizing and distinguishing strata. Still another nuclear logging method which has been employed for some years consists of the bombardment of strata with neutrons and the measurement of the number of gamma rays produced by neutron capture reactions involving elements in subsurface strata.' Since one of the principal elements entering into capture reactions is hydrogen, the latter procedure essentially results in a hydrogen log, whether the hydrogen be in combined form in either oil or water; thus, the log gives an indirect measure of porosity. These methods, with various refinements, have been developed to such an extent that they have become routine procedures in formation evaluation. Neither gamma-ray logging nor conventional neutron logging, however, yields sufficient information to permit unequivocal identification of the mineralogic composition of formations, and neither method gives information which may be used for the positive identification of hydrocarbons in strata. Accordingly, a number of efforts have been made in recent years to gain additional information from nuclear logs. Brannon and Osoba have shown that it is possible to identify naturally occurring radioactive elements in subsurface formations by spectral analysis of gamma rays emanating from these elements. Such an identification is of value in the characterization of strata. A simplified form of spectral analysis of gamma radiation resulting from neutron capture reactions between elements in earth materials and bombarding neutrons has been used with some suc- cess under favorable conditions to differentiate between petroleum and water. This method relies upon the relatively high energy of gamma radiation from neutron capture by chlorine and, in effect, furnishes a chlorine log. In areas in which interstitial water is of sufficiently high salinity, this log can give valuable information on water saturation and, thus, indirectly on hydrocarbon saturation. Still another approach to obtaining more information by nuclear techniques is "activation logging", in which certain elements yield short-lived radioactive isotopes on neutron activation and, thus, can be detected by gamma-ray spectral analysis. From the standpoint of determining by nuclear logging methods the mineralogic composition of strata and the presence or absence of hydrocarbons, it is essential that information be obtained on the presence and relative amounts of several elements such as carbon, oxygen, hydrogen, calcium, silica and others. Some elements, such as hydrogen, chlorine and sulfur, can be determined by spectral analysis of gamma radiation resulting from neutron capture reactions."" Others — carbon and oxygen, for example — do not enter readily into capture reactions but do yield gamma rays of characteristic energies from inelastic scattering reactions with high-energy neutrons. Accordingly, the latter reactions are of particular interest as a means of identifying hydrocarbons in subsurface strata. Several years ago it was recognized that information requisite to the identification of subsurface strata and of contained fluids could be obtained by pulsed operation of a subsurface neutron generator and associated gamma-ray detector. It was contemplated that pulsed operation would be effective in discriminating in time that gamma radiation which results predominantly from inelastic scattering reactions from that gamma radiation arising from neutron capture reactions. Accordingly, research was continued and construction of such a device was initiated. Although many problems were encountered, they were solved successfully. The following sections describe the tool which has evolved, its performance and the results which have been obtained with it to date. THEORY OF OPERATION OF NEUTRON-INDUCED GAMMA-RAY SPECTRAL LOGGING TOOL THEORY OF INDUCED NUCLEAR REACTIONS Of fundamental importance is the fact that an element, when bombarded with neutrons, emits gamma radiation of energy characteristic of that element. In theory, therefore, an element may be identified by

1944. Walter Hull Aldridge New York, N. Y. 1946. Peter M Anderson Johannesburg, South Africa 1946. Charles Camsell Ottawa, Ont. Canada 1946. Charles Augustus Carlow Fife, Scotland 1949. Erie Victor Daveler New York, N. Y 1946. Cecil H. Desch London, England 1946. William Fraser London, England 1917. Herbert Hoover New York, N. Y. 1941. Daniel Cowan Jackling San Francisco, Calif. 1939. Henry Krumb New York, N. Y. 1942. Essington Lewis Melbourne, Vic., Australia 1921. C. McDermid London, England 1944. Walter C. Mendenhall Washington, D. C. 1942. Paul Dyer Merica New York, N. Y. 1938. A. M. Portevin Paris, France 1934. T. A. Rickard Victoria, B.C., Canada 1946. John R. Suman Houston, Texas 1946. Wen-Hao Wong Chungking, China

Jan 1, 1952

PLANS for the World's Engineering Congress in Japan are rapidly taking shape. The Congress itself will be held in Tokyo in the week beginning Oct. 30, and will be followed by a second week of short excursions to points of interest, and this, in turn, by a two weeks' excursion through the Inland Sea and to Manchuria. Aside from the time each may desire to spend in Japan, from 30 to 42 days, according to route, must be allowed for travel from New York to Tokyo and return, with correspondingly' shorter time from intermediate points. The American Express Co., which has been appointed official travel agents by the American committee, has fur-nished the following estimates:

Jan 8, 1928

By H. Bernstein

WHILE the beryllium -copper (2 pct Be) alloy is nominally nonmagnetic, the presence of iron impurity causes variations in the magnetic proper- ties which, at times, attain excessive proportions. This investigation was carried out to establish the effect of small amounts of iron on the susceptibility of the material and to determine if the effect could be minimized. Beryllium-copper is an age-hardening alloy which

Jan 1, 1959

GENTLEMAN: The year 1928 was another in the history of the Institute which was marked by quiet growth and steady progress. The total membership as of December 31, 1928, was 8703 as compared with 8438 on December 31, in 1927. Again the main increase has been in Members and the number of Junior Associates is less. As will be seen also by the Treasurer's report, the increase is reflected in larger receipts for dues indicating that fewer have had to be dropped for non-payment. There has been a gratifying increase in the number applying for reinstatement and it seems clear that interest in and attachment to the Institute has notably increased. The year was signalized by the merging of the Rocky Mountain Club with the Institute which brought to our roll one hundred and forty who were not previously members from among the men who have made the West. It also brought to the Institute a strong tradition of good fellowship and a fund of over $100,000, the interest from which is to be expended so far as may be, for purposes beneficial to the Western states. The Endowment Committee expects to see other and similar funds entrusted to the Institute and the Board has already appointed a special committee to consider all projects for expenditure of the revenue from them. It is felt that with the organization and personnel available in the Institute even modest revenues can be made to yield large returns in the way of scientific and technical knowledge. Within the year also, a third great Division has been organized within the Institute, building on the foundation of the old Iron and Steel Committee. The new Division signalized its independence by joining the Lake Superior Mining Institute in a visit to the Menominee Range in September and by furnishing material for a special volume of 353 pages, "Iron and Steel" Technology in 1928," printed and distributed in December. The Institute of Metals Division held its fall meeting with good attendance as one feature of National Metal Week at Philadelphia in October, and published its volume of Proceedings, running to 836 pages, in August. "Petroleum Development and Technology in 1927," 844 pages, came out in June and recorded the work of the Petroleum Division. A most interesting Fall meeting was also held by the Division at Tulsa,

Jan 1, 1929

By W. A. Wood, H. M. Bendler

Cylindrical fatigue specimens of OFHC* copper were subjected to alternating torsion while under axial tension. The superimposed tension strongly influenced the fatigue life of the specimens as well as causing characteristic changes in the structure of the fissures that form and develop throughout the life of the specimen. A further effect of the superimposed tension is a continuous extension of the specimen throughout its life in a manner formally similar to creep at elevated temperatures. RECENTLY, studies of the structural changes leading to fracture of metals by fatigue have been made by a technique which reveals, in section, the lattice distortion arising from slip movements inside the metal and the disturbances built up by these slip movements at the metal surface.1'2 According to this approach, fatigue develops as follows: a) fine slip movements concentrate in bands, producing little strain-hardening and thus permitting abnormal totals of plastic strain before fracture and, therefore, abnormal amounts of lattice distortion along each slip band; b) both forward and backward slip movements occur in each band which, according to their distribution across the band, may build up surface disturbances that include sharp notches; c) these notches early in the life of a specimen penetrate the distorted slip zones and transform them into deep, fine fissures; d) the fissures on continued cycling locally saturate the metal and cause local collapse in the form of a microcrack. Thus, the significant consequence of fatigue or cyclic

Jan 1, 1962

By Robert Franke

(Butte Meeting, August, 1915.) IN view of the prominence which the conical mill has attained in the fine-crushing field within the few years since its introduction, the following comparison with its more mature forerunner, the Chilean mill, based on extensive tests, is submitted in the interest of the milling profession. Soon after designing the concentrating plant of the Miami Copper Co. in 1909, the Hardinge conical mill made its appearance in the milling forum. Its possibility as a suitable crushing device for the plant was well recognized, but in view of the lack of commercial demonstration, at the time, as to capacity, efficiency for desired product, and the still more uncertain factors of cost of maintenance and power consumption, it was deemed that the immediate adoption of this machine throughout the plant would be a hazardous undertaking. For these reasons it was decided to equip the majority of the imme diately required units of the plant with Chilean mills, the fine-crushing proficiencies of which were better known, and one section with Hardinge mills, to serve as a test unit for the guidance of future installations and replacements. Thereby, after 1.5 years' operation with both types of mills, a thorough test as to metallurgical efficiency and cost economy has been obtained. The conical mill used in these tests is the 8-ft. Hardinge pebble mill, having a cylinder 22 in. in length. The cylindrical portion of this mill is lined with cast-iron liner plates, and the conical extensions with silex bricks bound together by cement. Each liner plate carries a projecting lifter, the function of which is to increase the height of drop of the lifted material. Danish No. 5 pebbles, obtained from the coast deposits of Denmark, are used for the grinding charge. The Chilean mill used is a fast-running, 3-roller, 6-ft. Saturn mill, with screens of 0.037-in. opening. The feed to these mills is the oversize of Callow screens having 0.029-in. openings, which follow rolls crushing to 0.5 in.

Jan 7, 1913

FRANCIS B. SILSBE,* Washington, D. C. (written discussion?). ?This paper is an interesting example of the -solution by the methods of metallography of what seemed at first a purely chemical problem. The authors have shown: in detail, how the well-known corrosion of spark-plug terminals is due to the dropping out of the individual crystals of the metal as it becomes surrounded by an oxide film. This corrosion is usually quite slow but in special cases may become a serious factor in limiting the life of spark plugs. There still remains the problem for the metallurgist to produce a material that will be entirely free from, this trouble. One of the most startling results of the work is. the demonstration that it affords of the deleterious effect of a mechanical stress continuously applied to material that is at the same time subject to adverse chemical or thermal conditions. The particular style of spark plug shown in the illustration, and in which serious trouble was caused by this corrosion, has the side terminals fastened at both ends and the method of assem-bling is such that a considerable initial tension is applied to the wire. It is without doubt this superimposed tension that causes the inter-crystal-line network to line up, as it were, into a few continuous and deeply penetrating transverse fissures instead of forming a great number of shallow surface cracks. This result is clearly shown both in the case of

Jan 11, 1919

By W. C. Bleimeister

The rock salt deposits of the U. S. occur in five major basins: 1) the Eastern Basin (which includes parts of Michigan, Ohio, Pennsylvania, New York, West Virginia, and Ontario) ; 2) the Gulf Coast Basin (the northern rim of which includes parts of Alabama, Mississippi, Louisiana, Arkansas, and Texas, while its southern rim includes parts of the Isthmus of Tehuampetic and the Yucatan Peninsula of Mexico), 3) the Southwestern Salt Basin (which includes parts of Kansas, Colorado, Oklahoma, Texas, and New Mexico), 4) the Williston Basin (which under- lies parts of North Dakota, South Dakota, Montana, and Saskatchewan), and 5) the Green River Basin (whose periphery underlies parts of Wyoming, Utah, and Colorado). The greatest salt production in the U. S. is obtained from the Eastern Basin,-particularly from the areas of Michigan, Ohio, and Ontario. In 1958 the salt production from these areas amounted to 8.7 million tons or 35.3 pct of the combined total produced in the U. S. and Canada. Of the 24,286,000 tons produced by Canada and the United States, 6,443,000 tons were in the form of rock salt from dry mining, while 17,843,000 tons were produced from wells in the form of artificial brine, the result of dissolving the rock salt formation by fresh water. Three important factors lie behind the location and development of this salt mining area:

Jan 5, 1961