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By Robert Henderson

SEVERAL very interesting articles have been written on the caving system of mining, but most of these papers have dealt separately with the slusher system or the chute and grizzly system. In this paper, a comparison will be made of the two methods, both of which are being used at the Climax mine. The mine is on the Continental Divide, in central Colorado, at an altitude of approximately 11,500 ft. above sea level. The long, cold winters, characteristic of the high Rockies, create a number of operating problems not usually found in other mining areas. THE ORE BODY The Climax ore body is just east of the Mosquito fault. This structural deformation has brought the granite on the east against the sedimentary rocks on the west. The ore occurs in an intensely altered granite and schist around a silicified granite core. The ore is in a highly fractured zone of moderate silicification. The principal mineral, molybdenite, is found in these fractures. Barren dikes of granite porphyry cut through the ore body and core with no apparent regularity. The grade of the ore is fairly uniform and gradually decreases toward the footwall core and also into the hanging-wall granite. The footwall and hanging wall are determined entirely by assays. The ore body is roughly dome-shaped, with the apex truncated at the surface. It is covered to varying depths with talus. A horizontal section of the ore body on the Phillipson level appears as an annular ellipse surrounding the footwall core. The ring of ore varies in width from 300 ft. to as much as 800 ft. The north-south axis of the core is about 1200 ft. and the east-west axis is about 1800 ft. In the ore zone, the rock is sufficiently strong to maintain reasonably large openings, and openings larger than haulage drifts usually have to be supported. The ore is cut by a great many fractures and shears and breaks into rather large blocks when caved, necessitating considerable secondary blasting. The waste that overlies the ore body breaks relatively fine in comparison with the size of the blocks of the caved ore and tends to run through the broken ore in the cave, causing dilution unless the draw is carefully controlled. MINING SYSTEMS For several years the ore was mined by the chute and grizzly system, a system that differs from that used in other caving mines only in the size of openings and equipment. In the chute and grizzly system, main haulage laterals were driven along the footwall core and also along the

Jan 1, 1944

By Benjamin LeRoy Miller, Joseph T. Singewald

For a number of years Russia, India and Brazil have outranked all other countries as producers of manganese ores. During the 5 years immediately preceding the European war, the average annual production of Russia was 844,000, of India 694,000 and of Brazil 200,000 long tons. Since the outbreak of the war there has been a considerable falling off in the Russian and Indian production, particularly in the former, whereas the production of Brazilian ores has been greatly increased, amounting in 1914 to over 250,000 tons and in 1915 to nearly 350,000, with conditions favorable for a still larger production in 1916. Manganese is one of the few industrially important metals that are not produced in the United States in quantity commensurate with our needs, so that we have been compelled to import annually about 300,000 tons, having a value of over $2,000,000, and these ores have been obtained from the three countries mentioned above. Their rank as contributors to our imports of manganese ores was India, Russia, Brazil; and in 1913, Brazil contributed only one-fifth. During the past 2 years Brazil has furnished rapidly increasing quantities to this country, and, with the falling off of imports from India and Russia, has become our principal foreign source. In 1914, Brazil furnished two-fifths of the imports and more than India or Russia, and in 1915 over nine-tenths. The manganese ores of Brazil are consequently of more than usual interest to us at this time. The Manganese-Ore Distbicts of Brazil , The manganese mining industry of Brazil dates from the year 1894, and since that year the total production has been over 3,000,000 tons. With the exception of a small quantity produced in the State of Bahia from deposits west of the City of Bahia, this output has come from the

Jan 1, 1917

By W. E. Remmers

The defect in wire known as "cuppiness" has appeared and disappeared from time to time but the exact cause of its appearance or disappearance has not heretofore been known definitely. This defect is not limited to one particular metal or alloy but seems to be found at various times in all of the materials that are drawn into wire. Fig. 1 represents cuppy wire made from an aluminum alloy and Fig. 2 illustrates copper wire that became cuppy in drawing without intermediate annealing. Differences of opinion are current among the manufacturers of wire and in the literature (see bibliography at end of paper), some believing that the source of the trouble lies in segregation in the wire rod, oxides, sulfides, slag, etc.; others that the trouble is created by an unevenness of stress distribution across the section of the wire, usually thought of as being a function of die shape. All of the published work is of a qualitative rather than a quantitative nature. With this in mind, it was deemed advisable to make a study of the shape of the wire-drawing dies, as well as the oxygen content of the copper to be drawn. Experimental After several methods were tried, it was found that by studying the contour of the butt-end of the rod after drawing a measure of the "working" across the section of the wire could be made. The butt-end of the annealed rod was not sheared but was sawed off. The end was then smoothed with a fine file so that the plane of filing was perpendicular to the drawing axis. It is to be noted that this method is not an absolute measure of the distribution of cold working but is a very good indicative means of studying comparative values. The method of examining a tension break in wire was found to be the most sensitive in detecting cuppiness. Other methods, such as microscopic examination of longitudinal sections, X-ray radiographic studies, etching away of outer layers with nitric acid, and fracture by bending, can all be used to identify cuppy wire but the tension break will give the fracture characteristic of cuppiness before any of the other methods can

Jan 1, 1930

By F. V. Shallcross

Physical properties of thin films of CdS and CdSe formed by vacuum deposition onto glass sibstrates have been studied as a function of deposition and processing conditions. The crystallinity and surface features of CdS films were examined using electron microscopy and electron and X-ray diffraction techniques. The films were poly crystalline; the preferred orientation and crystallite size increased with film thickness, substrate temperature, and deposition time. The CdS films consisted primarily of hexagonal-phase material, in contrast to similarly prepared CdSe films which have previously been observed to contain mixtures of cubic and hexagonal phases. As-deposited CdS films showed no major dependence of Hall mobility on crystallite size or degree of preferred orientation. Hall mobility and carrier concentration in CdS and CdSe .films were measured at various temperatures; both parameters increased with temperature and yielded activation energies which depended on fabrication conditions. Surface-desorption phenomena and overcoating of the semiconductor with SiO affected the observed electrical properties significantly. THIN films of cadmium sulfide1,2 and cadmium sele-nide3,4 have been employed by various workers as semiconductors in the insulated-gate thin-film field-effect transistor, known as the TFT. These devices are most commonly made by vacuum deposition of all materials onto an amorphous substrate such as glass. A knowledge of the microstructure and electrical properties of semiconductor layers used in the thin-film transistor is essential in order to form a realistic model for the device and to improve its performance, reproducibility, and reliability. This paper will describe studies of the physical properties of vacuum-deposited CdS and CdSe films prepared under various conditions. Structural characteristics examined in- cluded phases present, crystallite size, nature of preferred orientation of crystallites, surface roughness, and structural homogeneity throughout the film thickness. Electrical properties measured were Hall mobility and conductivity and their dependence on temperature and ambient. Thin-film properties are affected by many fabrication parameters including purity and physical form of evaporant, deposition rate, film thickness, design and temperature of the evaporation crucible, geometry of the deposition chamber, nature of the residual atmosphere, composition and temperature of the substrate, and details of postdeposition processing. PREPARATION OF FILMS In this work the semiconductor films were deposited in a conventional oil-diffusion-pumped system with pressures in the 10-8 torr range. The CdS evaporant was obtained from the Eagle-Picher Co. as a high-purity coarse-grained crystalline powder; the CdSe was a high-purity sintered powder supplied by the Harshaw Chemical Co. The evaporation crucible was a resistance-heated molybdenum-wire basket coated with aluminum oxide and filled with a quartz wool plug at the top. The source to substrate distance was usually 10 cm. This region was enclosed by a Pyrex inner cylinder. The substrate was heated with an overlying Pyrex plate coated with tin oxide. The substrate temperature was controlled using a thermocouple attached to the lower side of the heater. This thermocouple was calibrated against another thermocouple attached to a dummy substrate and by observation of melting points of various metal films deposited in the system. The substrates were polished borosilicate glass plates and conventional glass microscope slides. Substrate preparation included cleaning with an ultrasonically agitated detergent bath followed by isopropanol-vapor de-greasing. Film thickness was measured interferomet-rically during and after deposition. STRUCTURE OF CdS FILMS Structural studies were performed on CdS films using electron diffraction, electron microscopy, and

Jan 1, 1967

By W. B. Jamison

Man's material advance from one level of civilization to the next has involved the development of new, more useful tools and the utilization of energy greater than he alone could produce. These two essentials for material progress have developed at an ever increasing rate in the last century. While the first really successful use of mechanical energy derived from burning fuel was in James Watt's steam engine which pumped water from coal mines in Cornwall about 1770, there was still very little use of mechanical energy in mining by 1900 except for pumping and hoisting. Compressed air, having some of the characteristics of steam and which operated engines not unlike steam engines or steam hammers, powered the first attempts to mine coal with energy greater than human muscle could provide. When direct current-powered traction cars replaced horse-drawn transportation cars on city streets, it was natural that direct current locomotives should begin to replace animal and human power in mine haulage. Slowly, trolley and battery locomotives were developed and introduced. With d-c systems being established for haulage, it was natural that improved cutting machines should be developed and powered by d-c motors. Thus began the years of

Jan 1, 1961

By C. Scala, F. Bernstein

General expressions are derived relating the streaming potential to the electrochemical potential of a permeable junction separating two electrolytic solutions. By the methods of irreversible thermodynamics, these potentials are related to the flux of mobile species arising from differences in pressure and chemical composition. The flux is conveniently expressed as a transference number, the equivalents of a mobile species transferred through the junction per faraday of electricity. At constant pressure, the flux equation gives the electrochemical potential across the permeable junction. The streaming potential across the junction is obtained by imposing the condition of constant chemical composition. The familiar expression for the borehole SP is shown to be a particular solution of the general flux equation. The derived exprersions were verified in experiments with seven shale samples. Both the theory and experimental data provide additional proof of the presence and magniturle of the streaming potential in shales. INTRODUCTION In the interpretation of electric logs, there has been much concern over the correction to be made to the recorded SP for an electrokinetic or streaming potential originating from the difference in pressure between the mud column and the formation. It was long recognized by M. R. J. Wyllie that such an electrokinetic potential source mas in the mud cake opposite permeable sands.' More recently, M. Gondouin and C. Scala2 showed an additional but opposing electrokinetic source of potential to be in shale beds. Their work was supported by the very extensive and excellent work of Hill and Anderson.3 n the present contribution, the general relationships between the electrochemical potential and the corresponding streaming or electrokinetic potential are examined and clarified. A notable advance towards understanding the relation between the various sources of electrical potential in a borehole has been the application of the now common methods of irreversible thermodynamics to describe the passage of ions and water through charged electrolyte junctions such as in shales.' The advantages of these methods are twofold. Unlike classical thermodynamics, they can be applied to non-equilibrium sys- tems, i.e., systems in which flow takes place, provided the flow processes have reached a steady state. They also permit conventional thermodynamic properties to be related to the steady-state dynamic properties. These methods arc used here specifically to derive expressions relating the potential behavior of shales in terms of ion and water transport. Experimental verification of the expression for the shale streaming potential is given which in turn offers theoretical support to the existence of a streaming potential in shales.' Importantly, the relative contribution of transport parameters to the SP is clarified. The theoretical treatment is essentially that of Lori-mer, Boterenbrood and Hermans3 ut has been extended to derive the general expression for the SP.

By John W. Wagner, Robert K. Willardson

Single crystals of Pbl-xSnXTe have been grown from The melt under liquid B2O3 using the Czochralski technique. The PbTe-SnTe crystals were grown from near-stoichiometric melts and from melts with slight deviations from sloichiometry. Crystal growth rates ranging from 1 mm per hr to 1 cm per hr were employed, the latter being generally used. Several investigations were performed to characterize the single crystals grown In this study. The phase diagram of the PbTe-SnTe system was examined. X-ray analyses verified the single-crystal character of the crystals, and powder pattern lattice parameter determinations showed that Vegard's law was followed within the limits of the experimental error. The as-grown crystals were p-type with apparent carrier concentrations of -8 x 1018 to -8 x 1020 carriers per cu cm. Hall coefficients, resistivities, and carrier mobilities were determined as a function of composition. Dislocations were revealed by an electrolytic etch, and the crystals were found typically to contain 2 to 4 x 105 dislocations per sq cm. Microhardness measurements were performed; no maximum in the Vickers hardness us composition curve was seen. Mass spectrometry was used for impurity analyses, and the crystals were found to contain 1 to 2 x 1017 total p-type impurities per cubic centimeter. Distribution coefficients were calculated for the major impurities which were Na, Mg, Al, Si, Cl, and Zn. RECENTLY interest has been stimulated in the preparation and characterization of many alloys of the binary compound semiconductors. This interest is due primarily to the almost unlimited possibilities of adjusting the semiconducting characteristics of these materials by varying the alloy compositions. One alloy system which has been receiving extensive investigation is the PbTe-SnTe system, since these alloys show promise of being useful as emitters and detectors of electromagnetic radiation in the spectral range of 8 to 14 µ. This paper reports on the growth of PbTe-SnTe single crystals by the Czochralski technique and investigations of the general properties of these crystals. The phase diagram of the PbTe-SnTe system was investigated so that specific alloy compositions could be attained. I) CRYSTAL GROWTH The PbTe-SnTe single crystals were pulled from the melt using the Czochralski technique. Generally, the crystals were grown from near-stoichiometric melts, although special growth runs were made from both lead-rich and tellurium-rich melts. Growth of single crystals from up to 5 pct lead-rich melts presented no problems; however, melts with tellurium in excess of -1 pct caused volatilization problems which generally made crystal growth impossible. All melts were prepared from high-purity materials as follows: 1) lead— 6 N— Cominco (Cominco Products, Inc., Spokane, Wash.); 2) tin—5N—Cominco; and 3) tellurium— 5N+— American Smelting & Refining Co., Plainfield, N.J. No further purification of materials was undertaken in this study. The elements were reacted at -1000°C in a vacuum-sealed silica tube for a few hours, a gentle rocking action being used to ensure thorough reaction. The cast ingots were then transferred to a silica crucible for crystal growth. A schematic diagram of the growth apparatus is shown in Fig. 1. The Vycor tube is sealed at both ends by O-ring flanges so that a vacuum or a positive pressure may be maintained in the growth chamber. The pull rod and crucible may be rotated; all crystals produced in this study were grown with the crucible sta-

Jan 1, 1969

By C. G. Dunn

Many investigations have been made concerning the nature of plastic deformation and recrystallization of metals either in the form of polycrystalline materials or in the form of single crystals. However, similar work on strip materials composed of large grains as thick as the strip and having a high degree of preferred crystal oricntation has not been carried out extensively. Such materials are ideal not only for studying changes in single crystals under conditions where neighboring grains exert their influences but also for obtaining the complete change in orientation of a grain or group of grains during the course of plastic deformation and subsequent recrystallization. It is well known that first-order twins in the form of Neumann bands may be produced during the plastic deformation of ferrite crystals, particularly silicon ferrite crystals.l--3 Furthermore, it is believed that high-stress regions exist in the vicinity of these bands4. and it has been said that these banded regions would be active in recrystallization processes.5 Evidence to that effect in silicon ferrite had already been presented with photomicrographs showing recrystallization among Neumann bands during the early stages of recrystallizati~n.5,6 Similar evidence has been published for nonferrous metals5 Merging of fine parallel deformation bands during annealing to form twin bands of ordinary appearance in alpha brass has been offered not only as evidence of an active role being played by mechanical twins but also as evidence that such twins cxisted prior to recrystalli~ation.5 Proof that such new structures are actually first-order twins, or even twins at all, must be considered inadequate except for those cases where X-ray or optical data have been obtained to confirm the necessary oricntation relationship.7,8 A. B. Greninger has obtained excellent iliustrations of annealing twins in alpha iron.9 Since his material was previously deformed by sharp hammering, a process that generally induces Neumann bands, the existence of twins following annealing might suggest that they grew from mechanical twins. In connection with transformation twins in alpha iron, Greninger reported that grains containing three twin orientations occurred rarely and none occurred with three sets of well-developed bands.9 The work at the Pittsfield Works Laboratory on silicon ferrite in the form of large-grained strip steel deformed a small amount and annealed to partially recrystallize the grains indicates that the deformation and recrystallization processes that lead to annealing twins involvc more complex processes than the formation of Neumann bands and the growth of such bands. Some groups of annealing twins are obtained which contain not only three well-developed twin structures, but also contain more than one order of twins. It is also shown, in one case, that an interrelated group of twins did not arise within one single parent grain and, furthermore, orientations of grains in the group

Jan 1, 1944

By C. G. Dunn

Many investigations have been made concerning the nature of plastic deformation and recrystallization of metals either in the form of polycrystalline materials or in the form of single crystals. However, similar work on strip materials composed of large grains as thick as the strip and having a high degree of preferred crystal oricntation has not been carried out extensively. Such materials are ideal not only for studying changes in single crystals under conditions where neighboring grains exert their influences but also for obtaining the complete change in orientation of a grain or group of grains during the course of plastic deformation and subsequent recrystallization. It is well known that first-order twins in the form of Neumann bands may be produced during the plastic deformation of ferrite crystals, particularly silicon ferrite crystals.l--3 Furthermore, it is believed that high-stress regions exist in the vicinity of these bands4. and it has been said that these banded regions would be active in recrystallization processes.5 Evidence to that effect in silicon ferrite had already been presented with photomicrographs showing recrystallization among Neumann bands during the early stages of recrystallizati~n.5,6 Similar evidence has been published for nonferrous metals5 Merging of fine parallel deformation bands during annealing to form twin bands of ordinary appearance in alpha brass has been offered not only as evidence of an active role being played by mechanical twins but also as evidence that such twins cxisted prior to recrystalli~ation.5 Proof that such new structures are actually first-order twins, or even twins at all, must be considered inadequate except for those cases where X-ray or optical data have been obtained to confirm the necessary oricntation relationship.7,8 A. B. Greninger has obtained excellent iliustrations of annealing twins in alpha iron.9 Since his material was previously deformed by sharp hammering, a process that generally induces Neumann bands, the existence of twins following annealing might suggest that they grew from mechanical twins. In connection with transformation twins in alpha iron, Greninger reported that grains containing three twin orientations occurred rarely and none occurred with three sets of well-developed bands.9 The work at the Pittsfield Works Laboratory on silicon ferrite in the form of large-grained strip steel deformed a small amount and annealed to partially recrystallize the grains indicates that the deformation and recrystallization processes that lead to annealing twins involvc more complex processes than the formation of Neumann bands and the growth of such bands. Some groups of annealing twins are obtained which contain not only three well-developed twin structures, but also contain more than one order of twins. It is also shown, in one case, that an interrelated group of twins did not arise within one single parent grain and, furthermore, orientations of grains in the group

Jan 1, 1944

By Welton J. Crook

Unless present, in considerable praportion, metals of the precious-metal group—other than gold and silver—are not readily detected by the methods of fire assaying usually applied to ores and metallurgical products. Platinum, when present in small quantity, will ordinarily be reported as silver unless special methods of parting are used. Other elements occurring in the gold itself are all fluxed and slagged in the assay operation and if analyses are made on bullions the melting and slagging operations to which the bullion has been subjected may eliminate most of the associated elements. On the other hand, the analysis of precipitate from the cyanide treatment of gold ores may reveal the presence of many unexpected elements, such as tungsten and molybdenum. It is uncertain, however, whether many of the elements present in the precipitate are derived from the ore gangue or from the gold itself. No very general survey of the distribution of metallic elements in gold seems to have been made. Rose and Newman,l in connection with the composition of native gold, say in part as follows: Gold is occasionally found alloyed with copper and sometimes also with iron, bismuth, lead, mercury, tin, antimony, palladium or rhodium. Rhodium gold from Mexico was found to be of the specific gravity 15.5 to 16.8 and contained 34 to 43 per cent of rhodium. The native alloy of palladium, gold, and silver from Porpez contains 85.98 per cent of gold, 9.85 per cent palladium and 4.17 per cent silver. Mal-donitk, from Victoria, contains gold 64.5 per cent, bismuth 35.5 per cent (Louis). Dana2 says that native gold is usually alloyed with silver in varying amounts, and that sometimes it also contains traces of copper and iron. Rare varieties contain palladium, rhodium and bismuth. Other authors, for instance Zeigler3 and Clark,4 give similar information. Most references on the subject agree that ordinary native golds contain, in common, the elements silver, copper and iron. After completion of the work of which this paper is a record, the conclusion is reached that all ordinary native gold probably does contain these elements and, although in certain cases other elements may be found to be present, that it is difficult to

Jan 1, 1943

By A. W. Peake, F. O. Prior

Considering the great advance in the development and application of electricity, it is not strange that eventually a big field for its use has been found in oil-field operations. So far as is known, the first electric drive in oil-field operations was in the Russian field of Baku in 1900. The first application in this country was made by the South Penn Oil Co. near Folsom, West Va. in 1903. In 1916, electric power was first used in the Burma fields of India for drilling and pumping. Between 1916 and 1922, The Empire Gas & Fuel Co. made the first large electrical installation in the Mid-Continent fields. But although the first application was made 27 years ago, it is only within the last 10 years that oil companies have begun to look upon its use with much favor. Within the last few years, there has been a steady increase in the use of electricity in the oil fields. The first application of electricity for oil-field operations in Wyoming was in the Lander field in 1919; the second was in 1924 in Salt Creek; and the third, and last to date, was made by the Continental Oil Co. in the Big Muddy field during 1926. Lander Field The electrification of oil-field operations in Wyoming was initiated by J. W. Steele, superintendent of the Producers & Refiners Oil Corpn., in the Lander field in 1919. At that time, 32 wells were being pumped from five band-wheel powers, with oil engines as the prime movers. Eight barrels of fuel oil were used for power per day and at the price of 90 c. per bbl. the fuel bill was $36 per day. It was decided to try a 15 to 35-hp. oil-field motor on one of these powers. Electric power was generated with steam at the old Wind River refinery station. This test was so successful that in 1920 all five powers were equipped with 15 to 35-hp. oil-field motors, the power being obtained from the Sinks Canyon hydroelectric station. Four of these powers pumped wells at an average depth of 1450 ft., and the fifth pumped wells at an average of 2100 ft. In 1920, the average production per day from the 32 wells was 325 bbl. The power bill on the

Jan 1, 1928

By Welton J. Crook

Unless present, in considerable praportion, metals of the precious-metal group—other than gold and silver—are not readily detected by the methods of fire assaying usually applied to ores and metallurgical products. Platinum, when present in small quantity, will ordinarily be reported as silver unless special methods of parting are used. Other elements occurring in the gold itself are all fluxed and slagged in the assay operation and if analyses are made on bullions the melting and slagging operations to which the bullion has been subjected may eliminate most of the associated elements. On the other hand, the analysis of precipitate from the cyanide treatment of gold ores may reveal the presence of many unexpected elements, such as tungsten and molybdenum. It is uncertain, however, whether many of the elements present in the precipitate are derived from the ore gangue or from the gold itself. No very general survey of the distribution of metallic elements in gold seems to have been made. Rose and Newman,l in connection with the composition of native gold, say in part as follows: Gold is occasionally found alloyed with copper and sometimes also with iron, bismuth, lead, mercury, tin, antimony, palladium or rhodium. Rhodium gold from Mexico was found to be of the specific gravity 15.5 to 16.8 and contained 34 to 43 per cent of rhodium. The native alloy of palladium, gold, and silver from Porpez contains 85.98 per cent of gold, 9.85 per cent palladium and 4.17 per cent silver. Mal-donitk, from Victoria, contains gold 64.5 per cent, bismuth 35.5 per cent (Louis). Dana2 says that native gold is usually alloyed with silver in varying amounts, and that sometimes it also contains traces of copper and iron. Rare varieties contain palladium, rhodium and bismuth. Other authors, for instance Zeigler3 and Clark,4 give similar information. Most references on the subject agree that ordinary native golds contain, in common, the elements silver, copper and iron. After completion of the work of which this paper is a record, the conclusion is reached that all ordinary native gold probably does contain these elements and, although in certain cases other elements may be found to be present, that it is difficult to

Jan 1, 1943

By T. S. Jr. Sligh

OF all the qualities that are essential in a good cigar tobacco none is quite so important as the burn. This term is general and includes many points, the most important of which are evenness of burn, color of ash, firmness and coherence of ash, and fire-holding capacity. The fire-holding capacity refers to the length of time the leaf or cigar will continue to, glow after ignition. Chlorides tend to prevent complete combustion and products are formed thereby that are injurious to the flavor and aroma. On the other hand, the carbonates of the alkalies, particularly of potassium, aid the combustion and increase the fire-holding capacity. Barth1 thought that the harmful effect of the chlorides was due to their fusing and coating the tobacco, thereby preventing complete combustion. Schlosing,2 Nessler,3 and Garner,4 suggested widely different theories to account for the favorable action of potassium salts. In order to study carefully the action of the various salts upon the course of combustion of the cigar a knowledge of the temperature of the burning cigar is necessary. Lehmann5 who seems to be the only investigator who has made any attempt to determine the temperature of a burning cigar gives 480° C. as the maximum temperature which he recorded. It is evident, however, that his measurements were in error, probably on account of the method and apparatus used, since the lowest visible red corresponds to a temperature of about 575° C.

Jan 9, 1919

By Eugene McAuliffe

The mining press, as well as certain federal and state bulletins, refer from time to time to the relative hazards that attach to loading bituminous coal by hand when compared with the so-called "mechanical loading" process. Much of the coal coming under the head of hand-loaded coal is won in part by the use of machinery; the coal-cutting machine is in general use, the electric power drill employed to a lesser extent. Therefore it may be said that the principal difference in the process employed, mechanical loading versus hand loading, lies in the fact that some type of loading machine is employed in the mechanical loading process to lift the coal from the face of the room, place or entry, after it is mined, placing it in the pit cars for transport to the tipple. It is a common practice to compute accident records on the basis of tons mined per fatal and per nonfatal accident, disregarding the fact that it is possible to produce by the aid of coal-loading machines the same daily, monthly and annual tonnage with a much smaller force than is required where the coal is all shoveled by hand. Inasmuch as the men who are released by the substitution of machinery for hand labor must find employment elsewhere, suffering some measure of hazard in their new occupation, we are of the opinion that the true relative hazard that attaches to the processes of mechanical loading and hand loading can be determined only by using as the basis of comparison "man shifts worked" or "hours of exposure" experienced per accident. The Union Pacific Coal-Co., beginning with the year 1929, undertook to maintain a true record of man shifts worked per compensable accident, giving equal weight to fatal and nonfatal accidents. Accidents lacking sufficient severity to come under the compensable terms of the Workmen's Compensation Act were not included in the compilation, the Act providing that "no compensation, except the expense of medical attention, shall be allowed for the first seven (7) days of disability, unless the incapacity runs beyond the period of twenty-one (21) days, in which case the compensation shall run from the time of the injury." With the further thought that all accidents suffered by employees engaged in any service, in or about the place where the loading process

Jan 1, 1931

By Roswell H. Johnson

The principle of sliding or graduation in royalties is accomplished either by the block, period, cumulative, or class method. The block method calls for a very low royalty rate on all oil produced up to a certain amount. This amount would normally be that which is believed to suffice to repay the cost of the well. A higher rate would be charged after the well is making a profit. This method, common in many industries, is peculiarly inadaptable to any industry such as this where the productivity per day of the units gradually and inevitably decreases. This, for reasons given later, is because it forces an early abandonment of the well and so offends against conservation. In the period method, the royalty rate is changed by some definite amount when the well produces less than a specified quantity per day or other given unit of time. While simple to explain, it operates badly because a great deal is made to depend upon a small reduction in production, whereas the reduction as a matter of fact declines rather erratically owing to the exigency of lease management, connecting of tankage, and vagaries of the gaugers. These disadvantages are obviated by the cumulative method. In this method, all the production less than a certain amount per week has one rate of royalty, or none at all, and the oil produced in excess of that amount pays an additional rate of royalty. In the long run the calculation is probably no greater than with the period method, for simple tables will be published and printed in the oil papers that can be cut out, enabling quick readings to be made. Even without the table the calculation is easy with the few royalty rates, two or three, which would be used. In this method, the amount paid in royalty declines gradually, rather than suddenly as in the period method. The following reasons might be advanced for the adoption oi cumulative royalties: 1. To distribute the burden in accordance with the capacity to pay. This principle is a unique one in business, although familiar in taxation. This is because it does not distribute reward in proportion to efficiency.

Jan 1, 1916

By William G. Kranz

Discussion of the paper of WILLIAM G. KRANZ, presented at the San Francisco meeting, September, 1915, and printed in Bulletin. No. 101, May, 1915, pp. 927 to 930. M. PETINOT, Niagara Falls, N. Y. (communication to the Secretary*). -I have read this paper with considerable interest and agree perfectly with Mr. Kranz that steel for castings made in an electric furnace is not necessarily, because of that fact, all good steel, and also that the qualities which he mentions, such as absence of segregation, elimination of `sulphur, great tenacity, etc., can be obtained in an electric furnace if operated under proper metallurgical conditions. An unusually low content of sulphur in steel for castings is not, of course, an absolute necessity and the range of this element usually obtained in steel made in basic open-hearth furnaces is sufficiently low to meet all physical requirements. The main factor in making steel for castings, regardless of the process, is the complete deoxidation of the bath to prevent the formation of

Jan 12, 1915

By Arthur F. L. Bell

Discussion of the paper of ARTHUR F. L. BELL, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 105, September, 1915, pp. 1769 to 1799. WILLIAM A. WILLIAMS, San Francisco, Cal.-Is the Union Avila plant run as a topping plant or as a dehydrating plant? A. F. L. BELL, San Francisco, Cal.-Both. It takes off an average of 20 per cent. water besides topping the oil. Part of the crude oil is run through an electrical separator before running to the topping plant, but the entire crude averages about 20 per cent. when it enters the topping plant. DAVID T. DAY, Washington, D. C.-I suppose most of the work contemplated in these large topping plants is simply to deal with topping the oils with only a small percentage of water in them. A. F. L. BELL.-Not more than 2 per cent. of water can be handled in ordinary stills without causing trouble. At our Gavotte refinery, where the oil runs from 15 to 30 per cent. water, we carry 20 lb., pressure oil our stills to hold the framing down, we can do that with small stills, with large one's it would not be safe; but with a retort, the quantity of water contained in the oil does not affect its working. It simply means additional fuel to evaporate the water.

Jan 12, 1915

By Basil Prescott

Resume.—The district of Santa Eulalia lies 12 miles to the southeast of the city of Chihuahua, Mexico. The ore deposits occur in a Cretaceous limestone of unknown thickness, overlain by a series of rhyolitic tuffs and flows. The limestone is very gently folded and is cut by several systems of fissures, of which only those with a general north-south strike are pre-mineral and control the deposition. The deposits are of two main types; the earlier silver-bearing iron sulphide type occurs as high-grade tabular bodies resembling veins and as large masses of relatively low-grade ore, The gangue of this type is composed of lime-iron silicates that point toward a close association with an igneous rock mass which has not yet been encountered. In the later silver-lead-zinc type the ore occurs in vertical chimneys and horizontal mantas, principally as oxides, though at a depth of 1,500 ft. some sulphides have been encountered. During oxidation the ore chambers have increased in size owing to the solution of the walls by the sulphuric acid generated in the process, and a substitution has taken place of nearly one-half part by weight of the original constituents of the ore, by newly introduced elements and radicals. Both types are believed to have come from greater depths than those yet reached by mining, and their ultimate source, from a consideration of similar deposits, is believed to be an igneous rock in contact with the limestone at some horizon below. The deposits are believed to have been formed at unusually great depths, as indicated by the proved great vertical range of the silicate minerals coupled with the absence of the igneous rock, and by the practically unchanged character of the silver-lead-zinc ores as far as developed. The volcanic capping is believed to be distinctly later than the economically important ore deposition. Introduction The Santa Eulalia district is situated in the State of Chihuahua, Mexico, and lies about 12 miles southeast of the capital, the city of Chihuahua. (See map, Fig. 1.) The district embraces the Sierra de La

Jan 1, 1915

By Joseph C. McCaskill

The writer assumes that this volume is not intended to serve as a source of statistics on international trade and that the reader is not interested in wading through a lot of statistical tables copied from the various reporting agencies. Generalizations therefore are made whenever possible and not always is the source of the information meticulously cited. The United Nations regularly publishes trade data on mineral commodities. E. J. Gealy, and C. L Kimbell, of the U S Bureau of Mines (USBM), work with these data and estimate that they cover approximately 78% of total mineral commodities traded. In addition the General Agreement on Tariffs and Trade (GATT) publishes analyses of certain trade data The most complete report of production and trade in minerals 1s probably the international volume of the U.S. Bureau of Mines Yearbook The latest available edition is for 1968, and some of the data in this edition cover only as late as 1967. Unless otherwise stated, the source of data used in the chapter is this Yearbook Other staff members of the Bureau were most helpful and cooperative They are not to be held responsible for conclusions or points of view to be found in the chapter. THE NATURE AND SCOPE OF INTERNATIONAL TRADE The two and a half decades since World War II have witnessed an unprecedented growth international commerce The end of the war found the world economy seriously crippled. Many countries had suffered severe war damage; international trade was disrupted and nations had to resort to exchange controls and bilateral trading arrangements. The postwar recovery, however, was remarkably rapid Within two decades, world Income more than doubled, and world trade which was less than $60 billion in 1948 exceeded $200 billion in 1968, 8 and reached $278 billion in 1970.18 The growing world trade contributed to world prosperity which in turn fostered growth of trade. This dramatic growth of international commerce was made possible by the progressive liberalization of trade and capital movements by the major trading nations of the world which began immediately after the War and has not yet completely lost its steam. The modern-day stimulus of the expanded trade movement was the enactment by the Congress of the United States in 1934, of the

Jan 1, 1976

By John S. Johnson

THE purpose of this article is to describe several types of borehole lining in common use, and especially to offer a relatively new means of reducing the expense of maintaining boreholes where they are subjected to corrosive action of water flowing either inside or outside of their casing. In the Anthracite region of Pennsylvania, boreholes are used for many purposes, the principal ones being: openings between the surface and underground workings through which are passed steam, water and compressed-air lines, ropeways from surface hoists to underground rope haulages, conduits for electric power and signal lines, water-discharge lines from underground pumping stations, and inlets to mine workings for flushing material. LININGS FOR BOREHOLES The inadequacy of steel pipe for use in boreholes has long been recognized. Various substitute materials have been tried, including screw-joint cast-iron pipe (Fig. I). Cast-iron pipe, while very effective as a discharge line for acid water (mine water) being pumped to the surface, is not so effective when serving as a conduit for silt and crushed rock being flushed underground for filling mine voids. Terra cotta pipe (Fig. 2) has been used in boreholes, and lasts a long time if the glazed inner surface of the pipe remains intact. Its installation in a borehole is very difficult and is recommended only where it is certain that there will be no subsidence of the surrounding territory. Accessibility in order properly to join each section of the pipe is essential to a satisfactory job. In large water holes, where it is possible to lower a man into the hole for sealing the joints of the pipe, glazed terra cotta pipe has been used successfully for delivering mine water from pumps in the mines. For large holes used for flushing refuse into mine workings where the surface wash is shallow, standard paving brick have been used to form a tube through the wash to the bedrock. These brick are laid radially, backed by common brick and cobbles laid in cement. It is obvious that the shaft through the wash must be large enough to permit a man to work in it. The flushing material is carried through bare rock from the juncture at bedrock to the openings underground. This plan has been used, particularly where a cast-iron surface line is laid upon the surface to carry the flushing material from the breaker to the hole, and down the hole continuously, with no opening to the air at the top of the hole, thereby eliminating the necessity of an attendant at this point (Fig. 3). Another similar type of borehole lining is constructed of hexagonal pieces of vitrified brick (Fig. 4). This type requires a steel drive pipe through the surface wash large enough to provide a finished tube of the desired size surrounded by a brick wall about 4 in. thick. The special bricks are laid in cement, six to a circle, around a lubricated pipe used as a form, and lowered in sections inside the large drive pipe; the bottom section is seated in a socket drilled in the solid rock, having the same inside

Jan 1, 1941