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By H. R. Thresh, A. F. Crawley

THIS paper reports the results of viscosity measurements on cadmium and indium undertaken as part of a continuing program of liquid metals research at the Mines Branch, Department of Energy, Mines and Resources, Ottawa, Canada. For several years this work has continued with support from the Canadian Zinc and Lead Research Committee and the International Lead and Zinc Research Organization. In the literature, existing viscosity data for cadmium are conflicting and for indium are scarce. To achieve reliable viscosity values, further work was deemed desirable. Viscosities were measured using an absolute technique applied to an oscillating closed right cylinder of liquid metal. The apparatus, constructed in this laboratory, and the techniques involved in its use have been described in an earlier paper.' In calculating viscosity coefficients from the experimental data. Roscoe's2 mathematical analysis was used. Because accurate viscosity determinations are dependent on accurate density data, and since the available data in the literature are conflicting, the densities of liquid cadmium and indium were also determined in this laboratory by a pycnometric technique. This increased the control exercised over all the variables contributing to the accuracy of viscosity measurements. For both density and viscosity determinations, cadmium and indium of 99.999 pct purity were used. These materials were obtained from Cominco Ltd. In order to suppress excessive evaporation losses and help prevent oxidation, a technique developed in measuring the viscosity of zinc' was used for cadmium. This involved maintaining an atmosphere of purified hydrogen in the viscosimeter during the rela- tively long periods while the experimental temperature was changed and stabilized between individual determinations of the logarithmic decrement. Then, immediately prior to a decrement measurement. the viscosimeter was rapidly evacuated to a pressure of about 2 X 10-6 torr. On the other hand. with indium. no difficulties arise from vaporization or oxidation. In this case. therefore. the apparatus was held under a constant vacuum of about 2 x 10-6 torr. When all sources of random and systematic error have been evaluated, the technique is considered to yield data accurate within 10.5 pct. The viscosity of cadmium was measured to a maximum temperature of 451.8°C and that of indium to 346.5°C. These temperatures are. respectively. 130° and 190°C above the melting points. Two separate runs were made on indium. The results are given in Table I and, when plotted. yield the smooth curves evident in Figs. 1 and 2. Values of A and C to fit the well-known Andrade1 equation were determined by a regression analysis. The equation is: where n = coefficient of viscosity. i = specific volume. T = temperature in °K Despite its empirical nature. Andrade's equation has been shown by many workers to describe accurately the temperature dependence of viscosity. During the current research program, this equation has been found to fit the data precisely for all the metals and alloys that have been studied.5,6 The A and C' values for cadmium and indium are given in Table 11. Comparing the magnitude of the present data with those of previous workers,7-10 as has been done in Fig. 1, it is evident that the results of Fisher and Phillips10 deviate markedly from the rest. With the exception of one point from Gering and Sauerwald,7 all other data agree within ±2.5 pct. However, the agreement between the present results and the work of Menz and sauerwald9 is especially good over the entire experimental temperature range. Such agreement may be expected since Menz and Sauerwald's

Jan 1, 1970

By B. Y. Ekber, A. S. Gorbachev

The development of economically effective and safe methods of mining thick coal seams allow considerable coal reserves to be used as an energy resource all over the world.

Jan 1, 1979

By J. HUNER

Twenty-four new fields were found in Louisiana during 1945. Of this number 15 were oil fields, eight were gas condensate, and one a dry gas field. None of these fields, with the exception of West Delhi, is as yet of any great consequence. The Weeks Island field in Iberia Parish may eventually develop into a considerable reserve.

Jan 1, 1946

By H. B. Pulsifier

The following report on the structure of copper is the result of work done in the laboratory of the Rome Wire Co. early in 1925. Previous work had indicated to the author that excellent results might be expected if a suitable technique in surfacing and etching could be developed. The resources of the Rome Wire Co. enabled this metal to be studied more intensively than previously, although none of the materials were investigated exhaustively. The material presented is hardly more than a preliminary summary of the most obvious character of the metal; a much longer research would have been necessary to solve many of the pressing problems connected with the casting and working of copper. The Rome Wire Co. has generously released the paper; to Dr. E. H. Darby, technical supervisor of the company, are due particular thanks for his appreciation of the importance of metallographic study of copper and for his effective support in the prosecution of the work and in making its publication possible. Dendrites, Cells and Granules The microscope reveals at least three orders of structural units in copper, as in other metals. The largest structural units are the dendrites —spine-shaped crystals building up the masses of metal when it solidifies from a melt or is crystallized from solutions by chemicals or electricity. The nucleus cells, commonly called "grains," are the largest and most conspicuous units of recrystallized solid metal; the limitations of their growth usually confine their sizes to microscopic proportions, although in "single crystals" they may become as large as the piece of metal itself. The granules are the microscopic fine-structural blocks or laminations that build up the nucleus cells; they are revealed when metal is etched with suitable chemicals. The granules are commonly visible at 500 diameters magnification and are plainly visible at 1000 diameters; magnification of the granular surfaces up to 6000 to 9000 diameters shows no finer units, not because of lack of optical resolution but because the chemical attack has left an unfeatured smooth surface.

Jan 1, 1926

By AIME AIME

DOUBT in anyone's mind that this is the age of metals, industrially speaking, could easily have been dispelled by attending the National Metal Congress in Chicago, Sept. 22 to 26. Iron, copper and aluminum; zinc, lead and nickel, often alloyed with each other or with some of a dozen minor metals, make the materials without which the modern world could not run. Science, pure and applied, is doing marvels in finding new mixtures, new alloys to meet new needs; in developing new means of rolling, fabricating, casting and welding metals cheaply-and effectively. These and related matters were the subject of 100 papers presented at 33 seperate sessions of the organizations that participated in the congress.

Jan 1, 1930

By W. J. Reagan

In a study of the life of ingot molds, it is essential to eliminate all of the variables. In the commercial manufacture of steel this is almost an impossibility. In this study many of the variables have been eliminated, and because of the unusually consistent furnace practice, with small variations in the type of steel manufactured, and a similar type of mold design for all ingot sizes, it is possible to determine with some degree of accuracy the cause of variations in ingot-mold life. All of the ingot molds in this study were used in the production of basic open-hearth killed steel with chemical analyses within the following range: C, 0.50-0.85 per cent; Mn, 0.60-0.80; Si, 0.20-0.30; S, 0.04 max.; P, 0.04 max. All ingot molds were of the closed-bottom type and used for bottom casting only. None of the molds in the study failed from cutting of the sides due to top casting; in fact, on only rare occasions are any molds used for top casting. The general type of this mold is shown in Fig. 1. All sizes have rather a heavy band of metal, about 6 in. wide, at the top to give mechanical strength at this point, and all have cast lugs. Cross sections of the various sizes from top and bottom sections are shown in Fig. 2. Ratios of wall thickness to ingot weight, ratio of ingot diameter to ingot length, and other figures of interest are shown in Table 1. In the majority of cases, the cause of failure in this type of mold is due to heavy fire cracking on the "flats" at a point from 3 to 6 in. from the bottom radius of the mold. Fig. 3 pictures this type of failure. The start of failure at these points usually begins with a very small section of the interior surface becoming involved. As a rule, a section of 1 or 2 sq. in. is the first noticeable indication that mold failure is taking place. Gradually the small section increases until a sizable cavity develops, causing a protuberance on the bottom of the ingot, which eventually becomes too large to be stripped. The mold is then removed from service. At the time of failure, this cavity often reaches a size of about 5 sq. in. and about 1/2in. deep. Sometimes cavities are found on only two or three sides and at other times all twelve sides appear to be invoIved.

Jan 1, 1937

By W. J. Reagan

IN a study of the life of ingot molds, it is essential to eliminate all of the variables. In the commercial manufacture of steel this is almost an impossibility. In this study many of the variables have been eliminated, and because of the unusually consistent furnace practice, with small variations in the type of steel manufactured, and a similar type of mold design for all ingot sizes, it is possible to determine with some degree of accuracy the cause of variations in ingot-mold life. All of the ingot molds in this study were used in the production of basic open-hearth killed steel with chemical analyses within the following range: C, 0.50-0.85 per cent; Mn, 0.60-0.80; Si, 0.20-0.30; S, 0.04 max.; P, 0.04 max. All ingot molds were of the closed-bottom type and used for bottom casting only. None of the molds in the study failed from cutting of the sides due to top casting; in fact, on only rare occasions are any molds used for top casting. The general type of this mold is shown in Fig. 1. All sizes have rather a heavy band of metal, about 6 in. wide, at the top to give mechanical strength at this point, and all have cast lugs. Cross sections of the vari-ous sizes from top and bottom sections are shown in Fig. 2. Ratios of wall thickness to ingot weight, ratio of ingot diameter to ingot length, and other figures of interest are shown in Table 1. In. the majority of cases, the cause of failure in this type of mold is due to heavy fire cracking on the "flats" at a point from 3 to 6 in. from the bottom radius of the mold. Fig. 3 pictures this type of failure. The start of failure at these points usually begins with a very small section of the interior surface becoming involved. As a rule, a section of 1 or 2 sq. in. is the first noticeable 'indication that mold failure is taking place. Gradually the small section increases until a sizable cavity develops, causing a protuberance on the bottom of the ingot, which eventually becomes too large to be stripped. The mold is then removed from service. At the time of failure, this cavity often reaches a size of about 5 sq. in. and about 1/2 in. deep. Sometimes cavities are found on only two or three sides and at other times all twelve sides appear to be involved.

Jan 1, 1936

By Gerald Sherman

LARGE part of the mining industry is still under the shadow of the depression, and unwilling to undertake changes in plant or methods of operation that require large preliminary expenditures of money. Certain metals command fair prices: nickel, tin, and molybdenum. The precious metals, gold and silver, have been given greater values by natural processes of economics or by proclamation, but are of so much less importance in industry, in total value, and number of men employed, that they have not greatly raised the average for the mining business. The increased value of gold which was established in 1933 has stimulated .the search for new deposits, and aided efforts to revive some of the old mines 'Where it is hoped to find quantities of marginal ore now become profitable. The higher price did not increase production very much for 1934, but two discoveries of major importance, and others yet to be proved, will help later. The two referred to are the Lupa gold field in Tanganyika Territory, and the Silver Queen mine on Soledad Mountain near Mojave in California. The first was recently discovered, and is being developed by the East African Goldfields, Ltd. Uncompleted explorations of the croppings early in the year had exposed for measurement and sampling to a shallow depth, three ore shoots as gregating 7400 ft. in length and 6 ft. in width, containing 0.375 oz. of gold per ton. In the Silver Queen. an ore-

Jan 1, 1935

Year of Election 1959 Andrew Fletcher, New York, N Y "For his outstanding leadership in the lead and zinc mining industries, and for his able and devoted services to the Institute as its Treasurer and President, and as a Director for many years " 1917 Herbert Hoover, New York, N Y 1955 George M Humphrey, Cleveland, Ohio 1950 Zay Jeffries, Ptttsfield, Mass 1942 Essington Lewis, Melbourne, Vic, Australia 1959 John M Lovejoy, New York, N Y "For his distinguished service to the Institute, for his outstanding contributions in furthering the professional status of petroleum engineers, for his pioneering in application of engineering to petroleum production, and for his outstanding record of public service on behalf of the petroleum industry " 1957 Donald H McLaughlin, San Francisco, California 1957 C H Mathewson, New Haven, Connecticut 1938 Albert M Portevin, Parts, France 1957 Fred Searls, Jr, New York, N Y

Jan 1, 1960

[A Aall, Christian H., M49 D Mgr, American Metal Climax, Inc., 61 Broadway, New York 6, N.Y. Aaroe, S. L., A54 B Sales Mgr, The W. S. Tyler Co. of Can. Ltd., St. Catharines, Ont., Canada Abalos, Teodulo Q., J57 A Foreman, Lepanto Cons. Ming. Co., Mt. Province, Philippines Abbass, G., M55 P. O. Box 680, Hong Kong, China . Abbitt, James M., A54 770 Sole Blvd., Bartow, Fla. Abdullah, M. Y., J53 Dept. of Mines Res. Div., P. O. Box 1016, Tiger Lane, Ipoh Perak, Malaya Able, John F., Jr., J53 A Ming Engr, USA SIPRE 1215 Washington Ave., Wilmette, Ill. Abell, Leo M., M31 B Conct Supt, Phelps Dodge Corp., Morenci, Ariz. Abenius, Hakan Wilhelm, M52 A Mng Dir, Stora Kopparbergs Bergslags AB, Falun, Sweden Abenoroth, Harry F., A57 Natl. Carbon India Ltd., 18A Brabourne Rd., Box 217, Calcutta, India Abercrombie, Harry W., J56 1645 Camphor Dr., Lakeland, Fla.]

Jan 1, 1961

By D. M. McFarland

A FEW years ago a novel electric detonator known as the split-second or millisecond delay electric blasting cap was introduced for use in quarry blasting. Regular electric blasting caps fired in series may be depended upon to fire within a millisecond or so from the first to the last in a series. Regular delay electric blasting caps are provided that fire one period after the other period in intervals of 1/2 to possibly 1 1/2 sec. Most split-second or millisecond delays are designed to fire one period after the other period in possibly 25 to 50 millisecond intervals. The ear is not capable of detecting time intervals of this magnitude. The primary thought at the time millisecond de- lays were introduced was to investigate the results on rock breakage by firing a line of holes in a quarry face.so that charges in adjacent holes would not be detonated simultaneously. This could not be accomplished satisfactorily with regular delays. The time interval between successive periods of $5 to 1 sec was sufficient to permit considerable movement of the burden. If the burden of one hole was reduced to a great extent by the firing of an adjacent hole, the firing of the hole with the reduced burden would likely reveal this lack of confinement by a terrific report and wild throw of rock.

Jan 1, 1950

By A. F. Bertuzzi, M. R. Tek, F. H. Poettmann

A method is presented for predicting pressure drop for two-phase fluid flow in horizontal pipes. A set of 267 experimental measurements randomly sampled from approximately 1,000 measurements from various literature sources was used. Pressure gradients calculated by the procedure developed and compared with the experimental values showed a bias of +0.82 per cent and a standard deviation of 20.8 per cent. The advantatges of this method over other available methods of predicting two-phase flow pressure drop are (a) its comparative simplicity of application, (b) its relative independence of flow patterns, (c) its accuracy, which on the basis of a statistical evaluation predicts pressure drop closer than other available methods, and, (d) its ability to satisfactorily correlate laboratory data from various sources while the correlations from these sources do not appear to agree with one another. The method has been reduced to a simplified graphical procedure, suitable for field use. A two-phase f factor is defined and correlated with parameters involving the flowing gas-liquid mass ratio, a Reynolds number for the gas phase, and a Reynolds number for the liquid phase. The choice of parameters allows the correlation to reduce to the usual f factor plot for the limiting conditions of (111 gas or all liquid. INTRODUCTION The mechanics and characteristics of two-phase flow systems have been of interest throughout the industry for some time. In numerous engineering installations such as pipe lines, chemical reactors, and heat exchangers, two-phase flow conditions are of every day occurrence. In oil production operations it has been desirable, in some cases, to consider transporting gas and oil together in a common pipe from oil field to process plant. The trend toward centrally located stock tank batteries in oil fields has resulted in longer gathering pipelines in which more than one fluid phase is flowing. The increase in the producing capacity of oil wells due to new production tech- niques has created the need for review and re-design of many surface gathering lines for properly handling the increased production. Optimum pipe size for the situations described above has become an important factor. The problem which is of interest here involves the ability to predict the relationship between pressure drop, fluid properties, fluid rates, pipe diameter, and pipe length. Although the literature1,5,10,13,18,19 contains various articles dealing with specific cases of the problem, Lock-hart and Martinelli17 proposed the most general solution. Their method has been later modified by Baker:1 Alves2 demonstrated that different flow patterns are possible for a flow mechanism defined by Martinelli such as gas turbulent, liquid turbulent. Baker explained deviations experienced with Martinelli's correlations on the basis that different flow patterns could exist for the same flow mechanism. Using Martinelli's method of correlatioil, Baker correlated data for each flow pattern for the turbulent-turbulent flow mechanism. Bergelin and Gazley6,7 presented a correlation for predicting gas phase

Jan 1, 1957

By Guillermo V. Borquez

INTRODUCTION The basic factors that influence the selection of a mining method are the geometry of the ore deposit and the strength of the ore and surrounding rock. These factors usually determine the ore recovery and dilution of the deposit under analysis. For the purpose of this paper we will consider a generalized case of a block caving system and the sequence of the analysis needed to optimize ore recovery. The analysis presented is intended for the preliminary planning stage. The critical factors involved in the caving process are identified and the methods for evaluating the suitability of a particular deposit to the caving method of mining are outlined. The mine design is approached by identifying the two most important, dimensions: the size and spacing of the draw points. These dimensions are estimated from a simulation model which takes into account the ore recovery, the incremental value of the ore recovered, and the safety conditions of the operations. The model estimates the number of draw points required to extract efficiently and safely the broken ore from the caving area. This number is found in the range where the net incremental value of the ore is maximized and the probability of pillar failure does not exceed the limit which is acceptable for a safe mining operation. A mining method and its design are in a continuous process of optimization. This process is unique for each deposit because of the many parameters involved; therefore, a back analysis of the operations should be performed when possible. These analyses will indicate if the ore body responds in a predictable manner to the parameters contained in the geological, fragmentation, and draw point models. SELECTION OF ALTERNATIVE MINING METHODS The selection of a mining method best suited to define the minable ore reserves of a given deposit involves consideration of the geometry of the ore deposit and the strength of the ore and surrounding rock. These two factors are usually sufficient to determine the ore recovery and dilution of the deposit. After analyzing the geological reserves and defining the limits of the deposit, either an open pit or an underground mining method can be selected to define the minable ore reserves. The sequence of steps to follow in the selection of a mining method is presented in Figure I. From an economic point of view, the strip- ping ratio is the determining factor for the selection between an underground or open pit method. In turn, the stripping ratio is a function of the grade distribution and con- figuration of the ore body. In order to obtain a preliminary estimation of the stripping ratio, a parametric analysis could be applied, such as the approach used by Professor E. P. Pfleider (1972) and summarized in Table 1.

Jan 1, 1981

By I. S. Levy, J. L. Brimhall, B. Mastel

Specimens of' Hastelloy X-280, a low-cobalt version of the solid-solution- hardened nickel-base alloy Hastelloy X, were given a series of thermomechanical treatttzents. They were then Lensile-tested at room temperature and 1350°F. The Microstructures of the specimens tested at 1350°F were studied by electron Microscopy. Microscopy showed that dislocation tangling, caused by the cold working, mas still in evidence after aging-for 24 hr to temperatures as high as 1550oF. (Cr, Mo)23 C6, (Fe, Mo)6 C'. as well us an unidentifiable phase precipitale due to the combination of the thermomechanical treatments and subsequent tensile strain. The room -temperature and 1350°F tensile properties show a general increase ill strength and decreccse in ductility with increusing cold-work level. This is due to the dislocation taangling-. PerLurbatiot~s to this general trend occur- due to solid-solution weakening at the higher cold-work levels as a direct result of the preciplitation reactions. THE requirements for corrosion resistance and high-temperature strength place nickel-base alloys among the more promising materials for advanced nuclear reactor applications. However, when these alloys are irradiated at service temperatures, they generally suffer severe embrittlement'" and reduction in rupture life.3 Certain experimental treatments resulted in improvements in the tensile and stress-rupture properties of Hastelloy X-280, a solution-hardened nickel-base alloy.' To provide a basis for understanding these improvements, unirradiated tensile specimens were examined by electron microscopy. The results are reported in this paper. EXPERIMENTAL DETAILS Material. Hastelloy X-280, a low-cobalt version of Hastelloy X, is a member of the solution-hardened class of nickel-base alloys. The Hastelloy X-280 was obtained from 4- and 1-in: thick plates in the mill -annealed condition. Table I gives the chemical composition of the material as reported by the National Spectrographic Laboratories. ~x~erimental Treatments. Plates of suitable size, 12 by 3 by 1 in., or by + in., were cut under a water jet from the stock material and examined ultrasonic -ally for homogeneity of grain size and absence of voids. The acceptable plates were solution-treated at 2150°Ffor 1 hr and air-cooled. These plates were then reduced in thickness by cold rolling 0, 10, 15: or 20 pct along the original rolling direction. The plates were machined into buttonhead tensile specimens with a gage diameter of 0.125 in., with a gage length of 1.125 in., and with their tensile axes parallel to the rolling direction. The specimens were examined for quality of finish with a penetrant dye, ultra son ically checked for voids, and finally given a dimensional tolerance check with an optical comparator. The acceptable specimens were aged for 24 hr at either 1000" or 1500 F and air-cooled. These specimens were then held at 540°F in a water loop for approximately 18 days to qualify as controls for similar specimens irradiated under the same conditions of time, temperature, water chemistry, and flow rate. Table U summarizes the treatments. These treatments were investigated to establish whether prior precipitation and stabilization of carbide phases at strain sites within the matrix could reduce the amount of carbides available for precipitation at grain boundaries during service. Tensile-Test Conditions. Specimens were tested to fracture at room temperature or 1350 F in air on an Instron tensile-testing machine at a crosshead speed of 0.05 in. per min. The time for the furnace to reach equilibrium at 1350°F was approximately 30 min; soak time prior to testing was 15 min; and test duration was approximately 5 min.

Jan 1, 1968

By Frank G. Snyder

The Precambrian of Midcontinent United States includes a metamorphic belt of probable Middle Precambrian age, a belt of Keweenawan volcanics and sediments, and widespread igneous activity that extended from Iowa to Texas. Most of the present structural configuration of the Midcontinent was developed by epeirogenic movements during the Paleozoic. The dominant elements are basins and arches. Three major metallogenic provinces occur in the Midcontinent. They include the Missouri Precambrian iron ores, the Lake Superior copper ores, and the Mississippi Valley lead-zincbarite- fluorite deposits. Several large iron deposits, occurring in rhyolite and andesite host rocks, are known. Both discordant massive bodies and replacement- type bodies occur. The iron deposits are believed to have been formed during the period of igneous activity. They are essentially the same age as the volcanics and older than the granites that intrude the volcanics. The Lake Superior copper ores include two established districts, the Keweenawan district and White Pine, and the copper-nickel deposits in the Duluth gabbro. The lead-zinc-barite-fluorite deposits include four major districts, Southeast Missouri, Upper Mississippi Valley, Tri-State, and Illinois-Kentucky, and at least eight minor districts. Ore may occur in stratiform deposits and in veins. The major districts all contain stratiform deposits, but several have produced appreciable quantities of vein ore. Only vein deposits are known in some of the smaller districts. The major features of all districts can be catalogued in terms of host rocks, structural patterns of districts, types of ore-bearing structures, and mineralogical characteristics. From these features, a Mississippi Valley type ore body, in its type area, can be defined.

Jan 1, 1968

By J. M. Lohr

A COMMERCIAL development requiring a suitable alloy or alloys for sealing into various grades of glass made it desirable to have a more exact knowledge of the expansion characteristics of the nickel-iron alloys than appeared in the published literature. The expansion of the more common. FIG. I.-EXPANSION CURVES OF SEVERAL FIG. 2.-EXPANSION CURVES OF TWO TYPES OF GLASS. (Courtesy of R. C. A.) TYPES OF GLASS. (Courtesy of R. C. A.) types of glass under consideration varies from 2.7 to 10.4 X 10-6 per degree Centigrade, over the range 20° to 400° C. For reference, the thermal expansion curves f several types of glass used for sealing by the lamp and tube industries are given (Figs. 1 and 2). This paper covers a detailed investigation of the thermal expansion of a series of nickel-iron alloys in which the nickel content varies from 30 to 70 per cent. Particular stress is laid on the alloys that contain between 40 and 55 per cent Ni.

Jan 1, 1938

No. 345.-Assayer. A man 35 years old, or over, experienced in general mineral assaying, particularly of tin and tungsten ores. To locate in Bolivia with a strongly established house. No. 346.-A firm of consulting and managing engineers, having charge of certain coal-mine properties in Illinois, requires the services of the following: (a) Mine transitman, who has had underground experience and is capable of making accurate surveys. Salary $150 per month to start. (b) Mining engineer, possessing strong personality, and experienced both in surface and underground work, who is capable of taking complete charge of several coal properties. Salary $175 per month. (c) Four rodmen for mine surveying. Salary $85 per month to start. Candidates for the above positions should be able to report to the company's Illinois office at once. No. 347.-A South African development company will shortly require the services of a mill superintendent, who has :a general knowledge .of concentration, particularly of flotation, and is able to take charge of a copper concentrator treating 15,000 tons per month and employing 200 natives and a small number of white men. Salary is £60 per month to start, and the company supplies an unfurnished room or house, including free light, free water and free sanitary service, together with one native house servant. I A contract will be made for six months, and notice of three months by either party will be required to terminate the engagement after six months. An allowance of £75 for travelling expenses will be paid on arrival in South Africa to a single man, or £125 to a man who brings his family. Salary begins upon arrival

Jan 10, 1918

By John M. Sharp

John M. Sharp, Jr. (Assistant Professor of Geology, University of Missouri, Columbia, Mo.)-Geothermal gradient and surface temperature data anomalies are potentially useful tools in mineral exploration, These data, however, may reflect a number of geologic and hydrologic processes as well as the thermophysical properties of the geologic materials. The author presents a relatively simple model which may be of value in mineral exploration. The lack of consideration of other processes, however, limits its usefulness. For instance, because of erosion or sediment deposition over geologic time the land surface must be considered a moving boundary in such a model. Evaluation of this effect coupled with annual surface temperature and thermal conductivity variations can result in temperature profiles such as shown in [Figs. 4 to 7]. These effects and others, such as ground-water movement," must be considered and filtered from the data before proper interpretation is possible. Another assumption which should have been discussed is, why were the observed mean surface temperatures not used for extrapolation of the gradients in [Figs. 4, 6, and 7?] Conductive heat transport responds to the actual boundary (land surface) temperature, not to theoretical temperatures in the absence of perturbations. Benfield presents a theoretical model for calculating perturbations in the geothermal gradient for erosion and sedimentation. The temperature (T) at any time (t) and any depth below the surface (x) is given by [ ] where T is the mean surface temperature, G, the geothermal gradient, v, the rate of erosion (or sedimentation),[ ], the long-term rate of change of T0, and k is the thermal diffusivity of the rock. Using the author's values and a rate of erosion of 1.54 cm per yr for a period of 10,000 yr, a thermal profile as shown in [Fig. 10] will be generated. A thermal diffusivity of 0.0164 sq cm per sec was used, corresponding to a thermal conductivity of 0.0082 cal per cm per sec per C. In [Fig. 11], a sediment deposition rate of 3.0 cm per yr for a period of 1000 yr was used to generate the subsurface temperature profile. A surface temperature of 24.3°C was used, as specified in [Fig. 9, 7], was set equal to zero for both cases. Superposition on the generated profiles in [Figs. 10 and 11] of the annual surface temperature variation perturbation (which may be calculated in a number of ways) will yield profiles similar to those in [Figs. 4 and 7]. Similar profiles can also be produced by regional ground-water flow. Models like the author's can be of value in mineral exploration. Other processes, however, which affect surface temperatures and gradients must first be considered, calculated, and filtered from the data if anything but the crudest qualitative interpretation is to be made. Robert C. Edmiston (Author's reply)-Professor Sharp has raised three objections to my interpretation of the subsurface temperature data I collected at Silver Bell. These are: 1) No correction was made for erosion or sedimentation,

Jan 1, 1977

By G. S. Hume

Production of petroleum and natural gas increased in Canada in 1939 principally because of new wells in Ontario and Alberta. Turner Valley The Turner Valley field, Alberta, yielded 7,456,000 bbl. of petroleum in 1939 in comparison with 6,703,548 bbl. in 1938, an increase of 11 per cent. Turner Valley now supplies 96 per cent of all petroleum produced in Canada (Table 1). The Turner Valley field (Table 2) has reached a position where it call supply much larger volumes of petroleum than the Prairie market is capable of consuming. The allowable production is under the jurisdiction of the Petroleum and Natural Gas Conservation Board of Alberta and the daily rate is set from time to time as warranted by the demand. During June the allowable reached a maximum of 27,000 bbl. a day. This, however, was a temporary situation due in part to the completion of a new British American Oil Co. refinery in Calgary capable of processing 5000 bbl. a day and with a storage capacity of about 100,000 bbl. The maximum consumption was reached during the harvest season with

Jan 1, 1940

By G. S. Hume

Production of petroleum and natural gas increased in Canada in 1939 principally because of new wells in Ontario and Alberta. Turner Valley The Turner Valley field, Alberta, yielded 7,456,000 bbl. of petroleum in 1939 in comparison with 6,703,548 bbl. in 1938, an increase of 11 per cent. Turner Valley now supplies 96 per cent of all petroleum produced in Canada (Table 1). The Turner Valley field (Table 2) has reached a position where it call supply much larger volumes of petroleum than the Prairie market is capable of consuming. The allowable production is under the jurisdiction of the Petroleum and Natural Gas Conservation Board of Alberta and the daily rate is set from time to time as warranted by the demand. During June the allowable reached a maximum of 27,000 bbl. a day. This, however, was a temporary situation due in part to the completion of a new British American Oil Co. refinery in Calgary capable of processing 5000 bbl. a day and with a storage capacity of about 100,000 bbl. The maximum consumption was reached during the harvest season with

Jan 1, 1940