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By Arthur F. Colombo

The selective flocculation, desliming and flotation process developed by the U.S. Department of the Interior, Bureau of Mines, as part of its goal of maintaining an adequate supply of minerals to meet national economic and strategic needs is described. The application of the selective flocculation and cationic flotation process to three oxidized taconites from the western Mesabi Range in Minnesota is discussed. Data from the operation of a 408-kilogram-per-hour (900 lb/hr) pilot plant employing reclaimed water are summarized for the three types of oxidized taconites.

Jan 1, 1980

By H. C. Rolseth, R. H. Kohler

Jet channeling made its entry into the granite industry in 1955 and quickly gained acceptance as an economical method of quarrying. Developed by the Linde Division of Union Carbide Corp., this method employs a small rocket-jet burner with a high-temperature, high-velocity exhaust flame that causes granite to disintegrate. It can thus make continuous vertical cuts to free large blocks from granite formations. The Thermal Spalling Process The effect of a thermal device on rock depends upon the rock's spallability. In simplest terms, spalling is the decrepitation resulting from differential expansion of rock crystals due to thermally induced stresses.1 the individual rock properties influencing the spalling characteristic are so numerous and their interaction is so complex that it has so far been impossible to predict with accuracy the reaction of any particular rock to a high-temperature source of heat. Perhaps computers will eventually make such predictions possible, but for the present it is necessary to impose the thermal shock conditions on a sample of the rock to establish its spalling characteristics. The properties most favorable to a high degree of spallability are: (1) Large linear thermal expansion at temperatures below 700º C. (2) High thermal diffusivity at temperatures below 400º C. (3) Equigranular interlocking structure with little or no fine-grained clay or mica alteration products. (4) No significant amounts of soft, low-melting, or elastic minerals or materials which yield after thermal decomposition.

Jan 7, 1969

By Phillip E. Butler

The Pennsylvania Dept. of Transportation is actively engaged in the utilization of coal mine refuse in the construction of highway embankments. Long-held objections for utilization are invalidated by research, laboratory data, and construction performance. Laboratory, engineering, construction, and environmental impact analyses are presented from the construction of the Cross Valley Expressway embankment at Forty Fort, Luzerne County, Pa. Comparisons of laboratory data and construction measurements are given. The refuse embankment is the first of its size in Pennsylvania, and possibly the U. S., covering 1.5 million cu yd.

Jan 1, 1977

By W. E. Keck

THERE is a considerable tonnage of iron ore in the Menominee Range Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a rela-tively large quantity of finished concentrate would be obtained (deleteri-ous sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal min-erals in a nearly puree state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,000'. Of this quantity and value, Michigan produced approxi-mately 19 per cent4. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1937

By R. G. Treuting, R. M. Brick

Despite the basic importance of slip in the plastic deformation of metals, and the considerable experimental investigation, thought, and speculation that have been devoted to the fundamental nature of these processes, surprisingly few data have been reported regarding the microscopic appear- ance and distribution of slip lines,‡ the external manifestation of the slip process. Photographs hitherto reproduced in the literature are in general at low or unspecified magnifications with no correlation to the prior shear. A single-crystal cylindrical tensile specimen of alpha brass about 1/2 in. in diameter, one of many previously prepared by H. L. Burghoff,1 was available for study. A plane about 3/16 in. wide, parallel to the specimen axis and normal to the plane containing the slip direction and the specimen axis, was ground and metallographically polished along the entire 5-in. gauge length. Heavy etching produced a surface free of both scratches and flow. The specimen was strained in tension until slip markings first became visible on the polished surface (Figs. 1 and 2). Re-stressing the crystal caused additional markings to appear at an initially lower stress than previously was required. Stretching the specimen to produce a dense concentration of slip lines caused such variations in level in the polished surface (normal to the slip direction) that microscopic study at higher magnifications became impossible. After annealing 15 hr. at 850°C, the specimen recrystallized to form two grains with a boundary approximately normal to the specimen axis and about midway along its length. Each was X-rayed, and two planes were again polished along the length of the specimen, in this case each parallel to the slip direction in one of the two crystals. A light longitudinal scratch parallel to the specimen axis was drawn down the center of each plane. A Huggen-berger extensometer was attached to the crystal A, whose slip plane would have the higher resolved shear stress of the two, and the specimen was again strained in tension.

Jan 1, 1942

By R. M. Brick, R. G. Treuting

Despite the basic importance of slip in the plastic deformation of metals, and the considerable experimental investigation, thought, and speculation that have been devoted to the fundamental nature of these processes, surprisingly few data have been reported regarding the microscopic appear- ance and distribution of slip lines,‡ the external manifestation of the slip process. Photographs hitherto reproduced in the literature are in general at low or unspecified magnifications with no correlation to the prior shear. A single-crystal cylindrical tensile specimen of alpha brass about 1/2 in. in diameter, one of many previously prepared by H. L. Burghoff,1 was available for study. A plane about 3/16 in. wide, parallel to the specimen axis and normal to the plane containing the slip direction and the specimen axis, was ground and metallographically polished along the entire 5-in. gauge length. Heavy etching produced a surface free of both scratches and flow. The specimen was strained in tension until slip markings first became visible on the polished surface (Figs. 1 and 2). Re-stressing the crystal caused additional markings to appear at an initially lower stress than previously was required. Stretching the specimen to produce a dense concentration of slip lines caused such variations in level in the polished surface (normal to the slip direction) that microscopic study at higher magnifications became impossible. After annealing 15 hr. at 850°C, the specimen recrystallized to form two grains with a boundary approximately normal to the specimen axis and about midway along its length. Each was X-rayed, and two planes were again polished along the length of the specimen, in this case each parallel to the slip direction in one of the two crystals. A light longitudinal scratch parallel to the specimen axis was drawn down the center of each plane. A Huggen-berger extensometer was attached to the crystal A, whose slip plane would have the higher resolved shear stress of the two, and the specimen was again strained in tension.

Jan 1, 1942

By J. E. Stukel, J. Cocubinsky

A CONSIDERABLE amount of information is available on the equilibrium distribution of manganese between slag and metal under oxidizing conditions. These data have increased our knowledge of the manganese reactions in the open hearth, ladle, and ingot mold. In contrast, there is a paucity of data on the slag-metal distribution of manganese under reducing conditions. The purpose of the present investigation was to study the equilibrium distribution of manganese between blast-furnace type slags and iron saturated with carbon. Experimental Method Furnace: The induction furnace used for the experiments is shown in Fig. 1. A 1 in. pipe, attached to the transite cover, was fitted with a window through which the charge could be observed. Material could be introduced into the furnace through a tee and plug without removing the cover. A graph-it cylinder (3 in. ID and 10'/2 in. long), centered within the induction coil, was used as a heating element. During a test, a zircon plug kept the top of the furnace from becoming too hot from heat radiation. At the bottom, a graphite block on the vertical center line of the furnace and extending 1 1/2 in. into the coil, was used as a support for the graphite crucibles containing the melt. The graphite crucibles, machined from regular carbon electrode stock, had a 2% in. OD with 3/16 in. walls and were 5% in. long. The fumes present in the furnace during the early part of a run made optical readings uncertain. A noble metal thermocouple was, therefore, adopted to measure the temperatures. The arrangement used, shown in Fig. 1, allowed the silmanite protection tube to be replaced with a minimum effort. The thermocouple was calibrated against a standard Pt-Pt-Rh thermocouple in a fused quartz protection tube. The latter was inserted in the molten iron by removing the glass window on the cover. The lower couple was found to be very sensitive to temperature changes. To insure accurate temperature readings, the graphite crucibles were made to fit tightly against the silmanite protection tube. Further, to avoid contamination of the thermocouple by carbon, the silmanite tube was changed and the calibration procedure was repeated at frequent intervals. By using this temperature measuring technique, the furnace was easily held within *1O°C of the desired temperature. Because of the small free space in the furnace, no attempt was made to control the atmosphere. It

Jan 1, 1955

By Waldemar Gooskov

IN his well-known work,1 published in 1867, P. Ritter von Rittinger gives the following formula for the velocity of a particle settling in still water: v=C/D(a -1) and for average grains he assigns to the constant C a value of 2.44. As is well known, the value of C depends on the shape of the grains resulting from crushing, and it is obvious that values obtained for coal particles will not only be very different from those for ore particles but will even be characteristic of coal from a certain seam. The only way of finding an accurate value of C, applicable to conditions in Russia, where all coal-washing plants are built on German principles, is to conduct a series of tests of which the results will determine what value of C is to be used. In the investigation outlined in this paper the theories of Prof. Robert H. Richards2 were taken as the basis of the tests; the slimes were removed from the charges to eliminate the trouble of handling them; and to obtain accurate results free from errors inevitably resulting from human observation, photographic apparatus was used and a series of pictures taken which form the basis for constructing a suitable diagram of velocity vs. time.3

Jan 1, 1928

(The following list contains the names of those members of the Institute of whose connection with military service we have only recently become acquainted; it also includes the names of a few who have recently been promoted or transferred. A complete list was published in the Year Book, issued as a supplement of the Bulletin for March, 1918.) ANDREWS, CLARENCE W., 2d Lieutenant, 12th Batt. Infantry Replacement Regiment. ANDREWS, JOSEPH C., Ordnance Dept., U. S. A. ARLUCK, A. A., Headquarters, 1st Corps of Artillery, A. P. O.. No. 759, A. E. F.

Jan 9, 1918

By Frederick N. Rhines

Pure copper that has been allowed to oxidize at an elevated temperature in the air is found to be covered with two distinguishable layers of oxide scale. The outer of these, which is very thin, is composed of cuprie oxide, while the inner layer, comprising the bulk of the scale, is made up chiefly of cuprous oxide (Fig, la). If a small quantity of an alloying element, such as silicon, is present in the copper, silica particles are found disseminated through the cuprous oxide, deposited most abundantly near the metal surface, and, in addition, silica particles occur to a limited depth within the copper itself (Fig. 1b). It is this inner layer, composetl of oxide particles precipitated in a matrix of metallic copper, that is known as the "subscale" or the zone of internal oxidation. Under a low oxygen pressure it is possible to produce the subscale without the formation of external layers of copper oxides, thus leaving the metal surface bright and apparently clean while oxidation has occurred, in fact, to a considerable depth within the metal (Fig. 2). Although little is yet known in a detailed way of the mechanism of internal oxidation, the general nature of the process is evident. By virtue of the considerable solubility of oxygen in copper,' it is possible to bring the alloying element in contact with oxygen within the metallic solid solution. If the oxide of the alloying element is more stable than cuprous oxide, the foreign oxide may form and, since most oxides are relatively insoluble in copper, it will not long remain in solution, but mill separate as a precipitate. As the metallic solute is exhausted in the zone of precipitation, oxygen that is constantly being supplied at the surface diffuses farther into the alloy and thus produces an ever-thickening shell of subscale. The distribution of the reacting elements in the subscale and adjoining zones must be somewhat as indicated in Fig. 3. The conditions requisite to internal oxidation to be anticipated are thus: (I) a solubility of oxygen in the alloy, (2) the ability of oxygen to diffuse at an appreciable rate into the alloy, (3) the possibility of the

Jan 1, 1940

By Frederick N. Rhines

Pure copper that has been allowed to oxidize at an elevated temperature in the air is found to be covered with two distinguishable layers of oxide scale. The outer of these, which is very thin, is composed of cuprie oxide, while the inner layer, comprising the bulk of the scale, is made up chiefly of cuprous oxide (Fig, la). If a small quantity of an alloying element, such as silicon, is present in the copper, silica particles are found disseminated through the cuprous oxide, deposited most abundantly near the metal surface, and, in addition, silica particles occur to a limited depth within the copper itself (Fig. 1b). It is this inner layer, composetl of oxide particles precipitated in a matrix of metallic copper, that is known as the "subscale" or the zone of internal oxidation. Under a low oxygen pressure it is possible to produce the subscale without the formation of external layers of copper oxides, thus leaving the metal surface bright and apparently clean while oxidation has occurred, in fact, to a considerable depth within the metal (Fig. 2). Although little is yet known in a detailed way of the mechanism of internal oxidation, the general nature of the process is evident. By virtue of the considerable solubility of oxygen in copper,' it is possible to bring the alloying element in contact with oxygen within the metallic solid solution. If the oxide of the alloying element is more stable than cuprous oxide, the foreign oxide may form and, since most oxides are relatively insoluble in copper, it will not long remain in solution, but mill separate as a precipitate. As the metallic solute is exhausted in the zone of precipitation, oxygen that is constantly being supplied at the surface diffuses farther into the alloy and thus produces an ever-thickening shell of subscale. The distribution of the reacting elements in the subscale and adjoining zones must be somewhat as indicated in Fig. 3. The conditions requisite to internal oxidation to be anticipated are thus: (I) a solubility of oxygen in the alloy, (2) the ability of oxygen to diffuse at an appreciable rate into the alloy, (3) the possibility of the

Jan 1, 1940

By P. E. Baker

Approximate solutions are presented for the heat-flow equations in a loss-free linear system with a moving source and with heat transfer by convection and conduction, representing in situ combustion in an oil reservoir. The rate of heat generation and the velocity vf of the source (flame front) are assumed constant. A cold front or convection front caused by the cooling effect of in-jected air develops behind the flame front and moves with velocity vc, which is determined by the thermal properties of the air and rock. Because of thermal conduction the fronts are not sharp; i.e., they do not represent temperature discontinuities. The following solutions apply after a sufficiently long time. where Q is heat generated per unit volume of formation, k is thermal conductivity, CF is volumetric heat capacity, a is thermal diffusivity, and subscripts 1 and 2 refer to values behind and ahead of the flame front, respectively. The parameter CF2 is contained in v . Te is initial reservoir temper- . C2 e ature and air-injection temperature. Other mathematically possible solutions are presented. The different solutions result from the use of different values for various physical parameters. The solution just presented is thought to be most commonly applicable. INTRODUCTION In this paper, approximate analytical expressions are derived for the temperature profile developed in the underground combustion method of oil recovery. A qualitative description of the process may be found in a paper by Tadema.1 The flame front is regarded as a moving source with a constant rate of heat generation. Heat transfer is by conduction and convection. Previous publications, of which a few are cited here, 2-5 have also attacked this problem and have presented solutions pertaining to different methods of approximating or idealizing the process studied. The present paper also treats an idealized case: linear flow is assumed for heat and fluids, and vaporization and condensation effects are neglected. The results obtained are similar to those derived by Bailey and Larkin,3 but are obtained by an entirely different procedure. The method used here should give considerably greater insight into the physics of the in situ combustion process. Four types of cases are considered, distinguished by thermal and fluid-flow properties of the system. A constant rate of heat generation and constant rate of flame-front advance are assumed. Flame-front temperature is determined for each case using a heat balance which involves the entire temperature profile. The applicability of the different solutions to real systems is discussed after they are all presented. Again, this is done for the purpose of understanding better the physics of the process. Consideration of the nonapplicable solutions and of the reasons for their not applying is significant. In a paper by Cooperman,4 the only case solved is one considered here as not applicable. Fluid flow, as such (pressures, saturations, oil recovery, etc.), is not treated. This subject has been covered in a paper by Wilson, et al.6 Also, we are not concerned with requirements for continuance of the process; we only attempt to determine the temperature history for cases where the process has continued for some time. PHYSICAL SYSTEM AND APPROACH TO PROBLEM A linear flow (heat and fluid) system is assumed and the x-axis is taken parallel to the flow direction. The combustion zone (flame front) is vertical,

By Portland P. Fox, Berlen C. Moneymaker

The development, within recent years, of core drills capable of drilling holes up to 72 in., or even more, in diameter, has made possible an entirely new and valuable method of geologic exploration. Although little used until recently as an exploratory tool except in the United States, by the Tennessee Valley Authority and the Corps of Engineers of the U. S. Army, for the exploration of damsites, the large-diameter core drill may be used to good advantage in other types of geologic exploration. Its principal utility is that of supplementing, rather than replacing, other means of exploration. Although core is frequently recovered intact, the greatest advantage of large-diameter drilling is that the holes produced are large enough to be entered by the geologist and engineer, and thus afford an excellent means of examining undisturbed rock. The walls of the holes are smoothly cut, and in some rocks nearly or quite polished, so that the most minute details of structure and stratigraphy are clearly disclosed. Such features as faults, joints, bedding planes, weathered "seams," and beds or layers of soft materials, which are not always amenable to disclosure by cores recovered from small-diameter holes, are conspicuously displayed in the walls of large holes. Frequent reference to the drilling of large-diameter holes is made in engineering literature, but comparatively little emphasis has been placed on their value in geologic investigation. It is, therefore, intended that the present paper acquaint the geologist, as well as the engineer, with the large-diameter core drill and the technique involved in its use, and also with its advantages, disadvantages and limitations as an implement of geologic exploration. The Equipment The equipment generally employed in the drilling of large-diameter holes consists of a trunnion-type drill head mounted on a sliding base, which allows it to slide clear of the hole and thus permit the introduction

Jan 1, 1941

By Portland P. Fox, Berlen C. Moneymaker

The development, within recent years, of core drills capable of drilling holes up to 72 in., or even more, in diameter, has made possible an entirely new and valuable method of geologic exploration. Although little used until recently as an exploratory tool except in the United States, by the Tennessee Valley Authority and the Corps of Engineers of the U. S. Army, for the exploration of damsites, the large-diameter core drill may be used to good advantage in other types of geologic exploration. Its principal utility is that of supplementing, rather than replacing, other means of exploration. Although core is frequently recovered intact, the greatest advantage of large-diameter drilling is that the holes produced are large enough to be entered by the geologist and engineer, and thus afford an excellent means of examining undisturbed rock. The walls of the holes are smoothly cut, and in some rocks nearly or quite polished, so that the most minute details of structure and stratigraphy are clearly disclosed. Such features as faults, joints, bedding planes, weathered "seams," and beds or layers of soft materials, which are not always amenable to disclosure by cores recovered from small-diameter holes, are conspicuously displayed in the walls of large holes. Frequent reference to the drilling of large-diameter holes is made in engineering literature, but comparatively little emphasis has been placed on their value in geologic investigation. It is, therefore, intended that the present paper acquaint the geologist, as well as the engineer, with the large-diameter core drill and the technique involved in its use, and also with its advantages, disadvantages and limitations as an implement of geologic exploration. The Equipment The equipment generally employed in the drilling of large-diameter holes consists of a trunnion-type drill head mounted on a sliding base, which allows it to slide clear of the hole and thus permit the introduction

Jan 1, 1941

By Portland P. Fox, Berlin C. Moneymaker

THE development, within recent years, of core drills capable of drilling holes up to 72 in., or even more, in diameter, has made possible an entirely new and valuable method of geologic exploration. Although little used until recently as an exploratory tool except in the United States, by the Tennessee Valley Authority and the Corps of Engineers of the U. S. Army, for the exploration of damsites, the large-diameter core drill may be used to good advantage in other types of geologic exploration. Its principal utility is that of supplementing, rather than replacing, other means of exploration. Although core is frequently recovered intact, the greatest advantage of large-diameter drilling is that the holes produced are large enough to be entered by the geologist and engineer, and thus afford an excellent means of examining undisturbed rock. The walls of the holes are smoothly cut, and in some rocks nearly or quite polished, so that the most minute details of structure and stratigraphy are clearly disclosed. Such features as faults, joints, bedding planes, weathered "seams," and beds or layers of soft materials, which are not always amenable to disclosure by cores recovered from small-diameter holes, are conspicuously displayed in the walls of large holes. Frequent reference to the drilling of large-diameter holes is made in engineering literature, but comparatively little emphasis has been placed on their value in geologic investigation. It is, therefore, intended that the present paper acquaint the geologist, as well as the engineer, with the large-diameter core drill and the technique involved in its use, and also with its advantages, disadvantages and limitations as an implement of geologic exploration. THE EQUIPMENT The equipment generally employed in the drilling of large-diameter holes consists of a trunnion-type drill head mounted on a sliding base, which allows it to slide clear of the hole and thus permit the introduction

Jan 1, 1938

By J. Orkiszewski

A method i.s presented which can accurately predict, with a precision of about 10 percent, two-phase pressure drops in flowing and gas-lift production wells over a wide range of well conditions. The method is an extension of the work done by Grifith and Wallis and was found to be superior to five other published methods. The precision of the method was verified when its predicted values were compared against 148 measured pressure drops. The unique features of this method over most others are that liquid holdup is derived from observed physical phenomena, the pressure gradient is related to the geometrical distribution of the liquid and gas phase (flow regimes), and the method provides a good analogy of what happens inside the pipe. It takes less than a second to obtain a prediction on the IBM 7044 computer. INTRODUCTION The problem of accurately predicting pressure drops in flowing or gas-lift wells has given rise to many specialized solutions for limited conditions, but not to any generally accepted one for broad conditions. The reason for these many solutions is that the two-phase flow is complex and difficult to analyze even for the limited conditions studied. Under some conditions, the gas moves at a much higher velocity than the liquid. As a result, the down-hole flowing density of the gas-liquid mixture is greater than the corresponding density, corrected for down-hole temperature and pressure, that would be calculated from the produced gas-liquid ratio. Also, the liquid's velocity along the pipe wall can vary appreciably over a short distance and result in a variable friction loss. Under other conditions, the liquid is almost completely entrained in the gas and has very little effect on the wall friction loss. The difference in velocity and the geometry of the two phases strongly influence pressure drop. These factors provide the basis for categorizing two-phase flow. The generally accepted categories (flow regimes) of two-phase flow are bubble, slug, (slug-annular) transition and annular-mist They are ideally depicted in Fig. 1 and briefly described as follows. RUBBLE FLOW (FIG. 1A) The pipe is almost completely filled with the liquid and the free-gas phase is small. The gas is present as small bubbles, randomly distributed, whose diameters also vary randomly. The bubbles move at different velocities depending upon their respective diameters. The liquid moves up the pipe at a fairly uniform velocity and, except for its density, the gas phase has little effect on the pressure gradient. SLUG FLOW (FIG. 1R) In this regime, the gas phase is more pronounced. Although the liquid phase is still continuous, the gas bubbler coalesce and form stable bubbles of approximately the rame size and shape which are nearly the diameter of the pipe. They are separated by slugs of liquid. The bubble velocity is greater than that of the liquid and can be predicted in relation to the velocity of the liquid slug." There is a film of liquid around the gas bubble. The liquid velocity is not constant—whereas the liquid slug always moves upward (in the direction of bulk flow); the liquid in the film may move upward but possibly at a lower velocity, or it may move downward. These varying liquid velocities will result not only in varying wall friction losses, but also in a "liquid holdup" which will influence flowing density. At higher flow velocities, liquid can even be entrained in the gas bubbles. Both the gas and liquid phases have significant effects on the pressure gradient. TRANSITION FLOW (FIG. 1C) The change from a continuous liquid phase to a continuous gas phase occurs in this region. The liquid slug between the bubbles virtually disappears, and a significant amount of liquid becomes entrained in the gas phase. Although the effects of the liquid are significant, the gas phase is more predominant.

Oil-well driller with extensive experience in this line of work. Location, Bolivia, South America. Salary depends on experience. R.-789. Mining Engineer, with geological knowledge, who can locate suitable spots for drilling oil wells. Location, Bolivia, South America. Salary depends on man. R-788. Construction Engineer, mechanical or civil engineer with experience in installing oil plants for foreign field. Must be able to install entire equipment including tanks, piping, buildings, etc. Salary depends on experience. R-782. Geologist, competent petrographer for micropetrographic work and training of two assistant students under the direction of the Director of a Geological Institute. Engagement is for six months with option on the part of the Director for an equal period: Location, Mexico. Salary, 450 pesos Mexican gold ($225 per month). R-765. Operating Mechanical Electrical Engineer, with extensive experience in charge of the maintenance, repair, and betterment of all mechanical and electrical equipment on mining operations. Desirable that the man have had this experience in connection with phosphate mining. Applicant must be competent to direct shop repairs on motors and generators, including rewinding, the building and maintenance of transmission lines, etc. Must also have ample machine-shop experience to enable him to direct repairs of light locomotives, steam shovels, brown hoists, caterpillar tractors, and auto trucks. Duties will include the betterment and maintenance of phosphate-rock washers and rotary-work dryers. The applicant must also be competent to conduct efficiency tests on all such equipment and be enabled to interpret data collected. Splendid opportunity for the right type of man. Climate and living conditions excellent. The company will furnish house rent free, including light .and water. Location, Florida. Salary depends on experience. R-854.

Jan 7, 1919

By H. K. Work, H. B. Emerick

IN the past year the steel industry underwent an abrupt conversion from a war tempo to a highly competitive peacetime schedule. It is still too early to gain a comprehensive picture as to which of the measures in production metallurgy, that made the war effort so successful, will remain in the postwar production of steel, but many of them undoubtedly will fill an important place after the war. Considerable speculation has developed regarding the disposition of the war-born production facilities of the steel industry. These include new open-hearth and electric furnaces, as well as vast numbers of auxiliary, supplementary, and balancing units that increased and speeded up production beyond the normal capacities of existing melting furnaces and finishing mills. Although these facilities were installed primarily to help meet war requirements, consideration was also given, in planning, to their possible peacetime use. The new equipment is generally modern and efficient, and it seems reasonable to suppose that strategically located units will gradually be absorbed by various steel companies to supplement their own facilities, or to replace in kind, obsolete and inefficient equipment now ready to be scrapped. Some, however,

Jan 1, 1946

Jan 1, 1892

By H. M. Rutherford

The reflection method in seismic prospecting has aroused much interest in the past few years. The purpose of the present paper is to present the method of reflections in the mapping of geologic structure and also to give some indication of its limitations. The reflection method is well adapted to the mapping of geologic structure in the Mid-Continent fields, and has been found most useful there. The refraction method is ideally suited to the finding of structures, such as domes, where the amount of relief is very large. This explains the brilliant success of the refraction method in the Gulf Coastal region of Texas and Louisiana. The additional fact that salt has a much higher velocity than the surrounding sediments made their discovery much easier. By the use of the reflection method, differences of relief of 25 to 50 ft. to the mile may be detected at a depth of 5000 ft., and the depth points accurately plotted on a map. This is hardly possible by the use of the refraction method. The reflection method has been in almost continuous use in the Mid-Continent area since 1926, but very little, if anything, has been published until recently'(7) † regarding either the method or the results. The discovery of several oil fields is now attributed to the use of the reflection method. Reflection methods have been used by the Germans to find the thickness of the ice of several glaciers. (2,8) The depths there considered were of the order of only a few hundred feet. For the method to be of any practical value in this country, it must be able to work to depths of several thousand feet. As was indicated above, this is now possible, though there are many problems connected with the reflection method yet to be solved. The refraction method requires that the shooting be done over long ranges. It was necessary, for example, to take distances out to several miles in order to penetrate some five thousand feet. Naturally this uses a good deal of dynamite. In the reflection method the distances are much shorter and the amounts of dynamite are much smaller, within limits which will be noted below. The chief distinction between refraction and reflection methods is to be found in the analysis of the seismo-gram. Refraction shooting makes use of only the first arrival of energy

Jan 1, 1934