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By A. V. Deforest, A. R. Anderson, C. W. MacGregor

ONE of the important problems in the design of structures and machine parts subjected to rapidly applied loads is the determination of the strength and ductility of the material itself under such conditions. Realizing the need for such information, many investigations have been carried out in the past. Most of these experiments have been made using notched bars in bending either with the Charpy or Izod impact machine. While yielding valuable data on the effect of notches in the energy absorption of the material and on the condition of heat-treatment, this form of test does not lend itself readily to a determination of fundamental stress-strain relations. For this and other reasons, more attention has been paid recently to the tension impact test. An extensive literature already exists on the subject and only those investigations somewhat closely related to the present paper will be mentioned. For a more comprehensive list, the reader is referred to the Symposium on Impact Testing of the A.S.T.M., 1938. The work of Mann,1 Clark and Dätwyler,2 Nádai and Manjoine,3 Winlock and Leiter,4 Deutler,5 and Brinkmann,6 however, deserve especial mention. In most of the previous investigations on the subject, when stress-strain relations were obtained under high rates of loading, it was the common procedure to determine stresses based on the original area and strains based on the original length. Stress-strain curves were then constructed by plotting [So = ooT as a function of eo =o] where A o and Lo refer to the original area and gauge length, respectively. At present there exists a paucity of true stress-strain data in the impact problem. The advantages of constructing so-called true stress-strain curves in order to reveal the fundamental physical properties of the material for the tension test were discussed recently by one of the authors? It was shown that the true physical behavior of the material in the tension test could best be represented by plotting the average true stress, [S = P] as a function of [e = q' = log A-le = log Lo] where P, A, L, S, [e], and q' refer to the load, the cross-sectioned area while the load P is applied, the actual gauge length, the average true stress, the true strain and true reduction in area, respectively. Besides giving a better physical representation, the method has certain additional advantages in that the stress-strain curve so plotted becomes a straight line from the maximum load point to fracture. The construction of such curves, however, while comparatively simple for the slow rates of loading customarily used in the tension test, presents certain difficulties for tensile impact in that both loads and diameters are required throughout the test. The continuous measurement of test-piece

Jan 1, 1941

By David B. Reger

The substantial expansion of previously discovered gas pools was the principal feature of petroleum activity in West Virginia during 1940. At least one new gas pool was discovered and various other successful wildcat completions may prove to be gas-pool openers. Some slight extensions of oil pools were also made. The new productive territory, principally gas, added by these extensions was approximately 33,800 acres. ' In general, oil activity was slight because of unfavorable crude prices. Gas activity, on the contrary, increased considerably, although the price of gas did not materially change. The account of operations, as gathered from trade journals and other reporting services, shows that 709 new wells were drilled, resulting in 102 new oil wells with I055 bbl. of daily new produc-tion; 468 new gas wells with 633>g47,000 cu. it. of daily open flow; and 139 dry holes. Also, 91 old wells were drilled to deeper sands, with 143 bbl. and 44,833,000 cu. ft. of added production. On the new wells the oil average was 10.34 bbl, per well per day; and the gas average was 1,354,000 cu. ft. per well per day. On new wells the ratio of dry holes to completions was 19.61 per cent. On deeper drilling to other sands the ratio of failures was 12.I per cent. From an exploratory standpoint, one strictly new gas pool (Lorentz) was opened in Upshur County. Little forecast of its extent or reserve can now be made. The new extensions of various other previously discovered pools, however, give assurance of a new gas reserve that will equal approximately a year of gas demand. In addition to these definite supplies two widely separated Oriskany sand (L. Dev.) wildcats in Jackson County, one of which was completed late in 1940 and the other early in 194.1, may indicate two separate pools or may greatly extend known pools. In south-ern Kanawha County, also, an old Oris-kany-sand well deepened to the White Clinton sand (Sil.) showed a volume of 733,000 cu. ft. and rock pressure of 1800 Ib., giving rather clear assurance that this deep sand, in which only slight quantities of gas had previously been found, should eventually supply much new gas. On the other hand, various deep tests to the Oriskany sand in Harrison, Putnam, Randolph and Wood Counties were totally dry or gave only small volumes of gas, The principal oil wells completed, by counties, were: Calhoun, 15; Clay, Ir; Pleasants, 14; Ritchie, 15; and Roane, 7. Production for the year was estimated by the U. S. Bureau of Mines as 3,444,000 bbl., as compared to 3,684,000 bbl. in 1939. The leading counties in gas-well completions were: Boone, 36; Braxton, 17; Cabell, 25; Calhoun, 16; Clay, 22; Gilm.er, 47; Jackson, 38; Kanatvha, 77; Lincoln, 18; Putnam, 32; IGtchie, 40; and Wayne, 31, Production for the year is estimated by me as I70,000,000,000 cu. ft. as compared to I59,226,000,000 cu. ft.* in 1939. No long pipe lines were built but various gas-line extensions and cross connections,

Jan 1, 1941

Jan 1, 1941

By Maurice Rey, H. Brevers

THROUGH circumstances connected with the war, the senior author lost his records therefore it has been impossible to include numerical data in this paper. The arsenical quicksilver ore investigated had been roasted, with poor metallurgical results. The vapor-tension temperature curves of mercury and arsenious trioxide are similar, and the arsenical compound hampers the coalescence of mercury drops in the condenser and is the cause of large stack losses. The ore was a gray limestone carrying small amounts of carbon and mineralized with cinnabar and two arsenic minerals, realgar (As2S2) and arsenopyrite (FeAsS). The proportion of realgar often exceeded that of cinnabar; the proportion of arsenopyrite was smaller. The grade of the ore varied between 0.8 and 4 per cent Hg. The problem was to make a high-grade mercury concentrate, as free from arsenic as possible. The water used throughout the testing was hard, having a pH- of about 8. FLOTATION OF REALGAR Realgar showed a very strong tendency to float. It formed a film at the surface of the pulp and floated in abundance with only pine oil. Therefore an attempt was made to float the realgar before the cinnabar, but this was not very successful; the percentage of mercury in the realgar concentrate could never be brought below 2 or 3 per cent. Cinnabar slimed easily and floated with pine oil, so that some of it always accompanied the realgar. There was also the question of the cinnabar-arsenopyrite separation. On further investigation it was found that realgar can be floated not only with pine oil but even better with a combination of hydrocarbons and pine oil. Washing the ore with ether revealed that it contained hydrocarbons, which helped to float the realgar. In this connection it belongs to the same class as carbon, sulphur and talc. It can be floated also with a xanthate, when activated by a heavy-metal salt. The conditions favoring the two types of flotation are opposed, as activation by a copper salt facilitates xanthate flotation (in fact, is even necessary to it), whereas it hinders pine oil and petroleum flotation. One type of flotation can be termed nonpolar and the other polar, a distinction that has been stressed in a previous paper. DEPRESSION OF REALGAR AND FLOTATION OF CINNABAR Many chemicals were tested in an attempt to float the cinnabar and depress the realgar. Finally starch rendered soluble with caustic soda was tried, also several grades of commercial soluble starch, and dextrin was found to be the best and the most convenient reagent. Several of these starch preparations have a strong flocculating effect on the pulp, which is a distinct disadvantage. Dextrin, with its low flocculating power, is excellent. It is noteworthy that starch preparations are also depressants for carbon and talc, so that the fact apparently has a general

Jan 1, 1941

By McDonald G. G

In the deformation of a metal or a single-phase alloy all the crystals composing the metal after their shape in a similar manner as the metal in bulk and to about· the same extent. This is not the case in an alloy consisting of two phases of different resistance to plastic deformation. In such an alloy the two phases take part in the deformation approximately in inverse proportion to their hardness, at least at the beginning of the deformation. (1) The hardness difference becomes less in the course of the deformation and thereby the deformation more equal. The phenomena occurring during cold-rolling of some two-phase alloys have been investigated by H. Unckel who made statistical grain measurements of the degree of deformation of the two phases after various reductions by rolling and also microscopical observations of the flow in the neighbourhood of the grain boundaries. Because of the different relative flow of the two phases, the normal flow is disturbed in the vicinity of their boundaries, and some additional plastic flow must take place in these regions, the disturbance being levelled out at some distance from the boundary. The deformation of the two phases present simultaneously in the material should thus be different from that of each phase separately. The investigation of theimportance and the effects of this interaction of crystals of different phases is the subject of this paper.The deformation of crystals occurs as a gliding of crystal layers following crystallographic laws. In consequence of this slip the crystals composing the material tend to assume a common orientation, i.e. some crystallographic axes tend to become parallel to each other in all the crystals. The type of this preferred orientation depends on the type of the crystal and the working process. Any change in the mechanism of deformation results, therefore, in a change in the preferred orientation. Such a change in kind and degree of preferred orientation will, therefore, also occur if the interaction of crystals in a two-phase alloy gives rise to a mechanism of deformation different from that in the free phases.The present paper describes a study of the preferred orientation, the microstructure and hardness in wires of brass drawn to various extents.The development of preferred orientations in the two phases with increasing reduction was followed up in various layers of the wire.EXPERIMENTAL DETAILSThe experiments were carried out with a commercial 5 S.W.G. wire (0,212 in. diameter) containing: 62·7% Cu, 37·3% Zn, very faint traces...

Jan 1, 1941

By E. W. McAllister

THE decision of the California Oil Umpire's1 office to accept well potentials established from subsurface-pressure data has brought to the attention of many operators for the first time the application of such data to production problems. This paper reviews the development and application of subsurface-pressure data in Kettleman Hills, where these data have been used in production work since 1932. The Kettleman Hills field was discovered in October 1928. The first subsurface-pressure surveys were made early in 1932 and by the middle of 1933 the two major operators in the field were making routine pressure runs in their respective wells. Shortly thereafter, these companies agreed to exchange pressure data, and later a third company entered into the agreement. This made it possible to analyze the effects upon the reservoir pressure of past production practices, which are discussed in the latter part of the report. It is interesting that many of the applications of subsurface-pressure data discussed herein were anticipated by C. L. Clarks and C. B. Kimberlin‡ in a reports dated March 1933. PRODUCTIVITY INDEX In the majority of individual well problems involving the use of subsurface pressure data, it is necessary to use a factor known as the "productivity index," which indicates the ability of a well to produce and represents the number of barrels of oil or oil and water per day that will enter the well bore for each pound per square inch pressure drop made opposite the producing interval of the well. The productivity index may be determined from pressure and production data for one or more rates of flow and a static or shut-in pressure survey or from production and pressure data for two or more rates of flow. Productivity indices may be based upon either net oil or total fluid production. All indices referred to in this report are based upon net oil. The value of the productivity index for Kettleman Hills wells decreases generally with time and it is not uncommon for the index to vary in value at any specific time for various rates of flow. The decline of the productivity index may be attributed partly to the loss of reservoir pressure. As. the reservoir pressure decreases, gas originally in solution is released from the oil, congesting the flow of fluids through the formation and increasing the viscosity and surface tension of the oil; thus the flow resistance of the fluids through the formation is increased, resulting in a decrease of the productivity index. For convenient reference, the productivity indices for each well are plotted against time and a curve is drawn through the points showing the trend of the average index value. Plotted on Fig. I are index values for five

Jan 1, 1941

By B. A. Rogers, K. O. Stamm

BECAUSE it is the basis of the economically important operation of hardening steel by quenching, the A3 transformation in iron has been the subject of numerous investigations. Although the contributions to this subject are interesting, no general review will be given here. Readers who care to follow the matter further are referred to the comprehensive summary by Cleaves and Thompson,1 which covers the literature to about 1935. Their references to 53 papers on the subject suggest that further investigation is hardly justifiable. However, considerable interest has developed recently concerning the reversibility of the transformation. From thermodynamic considerations, the transition ought to occur at the same point on heating or cooling, if the change of temperature is sufficiently slow. Yet all of the earlier investigators found a difference of several degrees. Burgess and Crowe,2 who used thermal methods, obtained average temperatures of 912° for Ac3 and 900°C. for Ar3 on electrolytic iron. Their data indicate a considerable range of temperature over which the change occurs, both on heating and on cooling. Terry3 measured the susceptibility in the critical range and estimated from the steepest parts of his curves that Ac3 came at 9180 and Ar3 at 903°C. Ishiwara4 was one of the first investigators to report a shorter interval between the temperature of the change in the two directions. He measured the change of susceptibility of kaolin-coated samples of steel, in a hydrogen atmosphere, at rates of heating and cooling so low that about 3 or 4 hr. were required for the transformation to complete itself. His results show some variability between samples, but indicate that the difference between Ac3 and Ar3 is in the vicinity of 6°C. Roberts and Davey5 measured the space lattice in pure iron in the vicinity of 900°°C. and concluded that a change occurs reversibly between 907° ± 3° and 9100 ± 3°C., probably between 907° and 910°C. Wells, Ackley, and Mehl6 made dilatometric determinations of the Ac3 and Ar3 points in samples of hydrogen-treated carbonyl iron maintained under a vacuum. They used three rates of heating and cooling: 2°, '1/2°, and 1/8°C. per min. and found the spread between the two points decreased with low rates. At the slowest rate, the Ac3 transition occurred at 909° to 909.5°C. and the Ar3 change at 907°C. in three of the samples believed to contain the lowest percentages of alien elements. They concluded that if the rate of temperature change and the content of alien elements were low enough, the A3 transformation would be completely reversible at 909.5° ± I°C. The question of reversibility is an interesting one and when some iron with especially small percentages of alien elements became available the opportunity to conduct an investigation was welcomed. This iron was prepared by the Division of

Jan 1, 1941

By M. Muskat, H. H. Evinger

Although the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.' In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was measured and an attempt was made to determine the effectiveness if sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to deter-mine the effect of tamping were performed by Snelling and IIalL2 Small charges (zo grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.~ The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.6 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941

By Clarence Zener

IT has long been known that the density of a metal usually decreases with cold-work. Thus O'Neill1 observed as early as 1861 that cold hammering of commercial hot-rolled copper is accompanied by a decrease of density of 0.2 per cent, and that subsequent annealing restores the original density. The origin of this density change, however, has remained obscure. In particular, experiment has not yet decided whether it is due to the presence of small cavities and an increase in intergranular surface or to an actual expansion of the lattice itself. This uncertainty in the origin of the change in density is a reflection of our uncertainty as to the changes induced in a metal by cold-working. One school regards cold-working as a breaking up of the original grains into a large number of perfect crystallites somewhat randomly orientated with respect to one another.2 According to this viewpoint, the mere introduction of a large intercrystallite surface induces a net volume expansion. Another school regards cold-working primarily as a distortion of the grains. It is not obvious that this second viewpoint will lead to a net volume expansion. The purpose of the present paper is to show that this is indeed the case, and that this expansion is of the right order of magnitude to explain existing experimental data. The physical basis for the association of an expansion with distortion lies essentially in the variation of the elastic moduli with volume. This variation is considerable. Thus from Table I we see that a I per cent increase in volume for the case of copper will decrease the bulk modulus K by i0 per cent, the shearing modulus µ by 3.8 per cent. If we thus twist a rod through a given angle, we shall do less work upon it if it increases slightly in volume, thereby reducing the torsion modulus that involves as a factor the shearing modulus. A general principle' in physics states that the rod will so adjust itself as to have a minimum potential energy consistent with the end restraints. It will therefore expand. [ ] In order to obtain a quantitative comparison with experiment, we follow Maier4 in comparing the lattice expansion with the latent energy of cold-work. This latent energy has been measured directly by Taylor and Quinney5 on copper rods subjected to torsion, and may amount to as much as 15 per cent of the total work done upon the specimens. We shall assume that this

Jan 1, 1941

By Francis M. Walters, Irvin R. Kramer

THE substitution of cobalt for part of the nickel in Invar was found by P. H. Brace1 to lower the coefficient of expansion. Scott1 extended the use of cobalt to alloys of higher inflection temperatures. Such alloys have a larger temperature range of low expansion than those without cobalt, and [ ] their use up to 400° or 500°C. offers decided advantages in certain applications. However, it has been found that the iron-nickel-cobalt alloys are not stable in this temperature range. EXPERIMENTAL METHODS Two methods were used in studying the stability of the low-expansion iron-nickel-cobalt alloys. Dilatometer specimens were held at 480°C, for 9 months and the change in expansion characteristics was determined. Filings were held for about 2 months at various temperatures and the change in structure was determined by X-ray diffraction. As shown by Table I, the alloys studied covered a wide range in nickel plus cobalt content (which determines the inflection [ ] temperature) as well as some variation in the ratio of nickel to iron (which controls the temperature of the gamma to alpha transformation). Included also are alloys containing carbon and vanadium, carbon and titanium and three with various amounts of copper. The alloys were melted in a high-frequency induction furnace with a magnesia crucible, using ingot iron, electrolytic nickel and commercial cobalt. Fifteen-pound heats were cast into iron molds after deoxidizing with silicon, or

Jan 1, 1941

By Walter Kauzmann

EyRing'S general theory of shear rates as a function of the properties of molecular units of flow is outlined and applied to the creep of metals. This theory regards the unit molecular processes involved in the flow of matter as typical chemical reactions requiring an energy of activation in order to proceed. The externally applied stresses are assumed to influence the rate of flow solely by lowering the activation energy for flow in one direction and raising that for flow in the other, owing to the work that is done by or against the external forces in going from the normal to the activated state. The rates of flow in the two directions are then no longer equal arid there is a net, macroscopically observable flow in one direction. This is understood to be the physical basis for the well-known exponential dependence of the creep rate on the stress. The amount by which the activation energy is raised and lowered by a given external stress is directly related to the molecular dimensions of the unit of flow, so that some insight into these call be found from the behavior of the strain rate with changing stress. When Eyring's equation is applied to the flow of ordinary liquids, such as water or benzene, it has been found from the values of the constants required to fit the observed data that the unit molecular process here involves the passage of single molecules by one another. In metallic creep, on the other hand, the unit molecular process is shown probably to involve the shear of rather large blocks of material (100 to 1000 or more atoms on a side). This agrees with present ideas of crystal flow by means of dislocations such as have been presented by Taylor, Oroaan, and Polanyi, as opposed to flow by a mechanism related to that taking place in atomic diffusion. The dimensions of the dislocations are found to depend markedly on the temperature. The questions of why some metals are so much softer than others, the effects of impurities on hardness, the softness of single crystals, and the role of self-diffusion in creep are considered in the light of the theory and it is shown how answers to these questions (and others similar) might be obtained by use of the theory.

Jan 1, 1941

THE decades immediately before and after the end of the nineteenth century (1890-1910) were a period of increased activity in mineral industry education. One reason for this, undoubtedly, was the rapid increase in mineral production in the decade 1880-1890; pig iron and copper production tripled; coal, lead, and zinc output more than doubled. Most of the other mineral substances followed the same general trend. Aluminum production began in 1886; petroleum output, which in 1888 was less than it was in 1882, almost doubled in the next three years. Gold alone showed no appreciable change until its discovery at Cripple Creek in 1891, followed by the Klondike in 1896, brought to boiling a public interest in minerals that had been simmering for some years previously. The first cyanide plant in the United States was erected at Bodie in 1892, and the first chlorination plant at Cripple Creek* the next year. Silver- lead smelting had already greatly developed, and the metallurgy of copper was almost transformed. The hearth area and smelting capacity of copper reverberatory furnaces more than quadrupled between 1878 and 1894; matte converters were first erected at Butte in 1884. Copper production of the United States in 1899 was 20 times that of 1872. While it was the increased technology used in mineral production that really made the field attractive for educated young men, undoubtedly they did not realize that, and were impressed mainly by the quantitative increase in output. Another factor was the increased general interest in engineering education; three times as many men took engineering degrees in the United States in 1890 as in 1880; 1892 showed almost a 56 per cent increase over 1890. Industry had come to recognize that technical training was worth while. The mineral industry lagged somewhat at first; the total number of mining degrees

Jan 1, 1941

By Wing G. Agnew

[This report presents the results of tests made by the Mining Division, Bureau of Mines, on the relative durability of manganese-steel drill rods and carbon-steel drill rods for use with detachable bits.]

Jan 1, 1941

Papers presented at two joint meetings of the Mineral Industry Education Division, Geophysics Committee, the American Geophysical Union and the Committee on College Curricula of the American Association of Petroleum Geologists, at the A I M E meeting in New York on Feb 17 and 18, 1941 At the first meeting, the Musing Geology Committee, the Society of Economic Geologists and the Committee on Applications of Geology of the American Association of Petroleum Geologists also took part [ ]

Jan 1, 1941

By H. Landsberg

THE curriculum presented here is an outgrowth of discussions by the Committee on Geophysics Courses of the A.I.M.E. in previous years. It had to be a compromise between the desires voiced by employers of geophysicists, professional geophysicists and the possibilities at an average college. There one has to face the questions of the available teaching staff, the inertia of administrators and teachers set in their ways, and the red tape involved in modernizing antiquated curricula. It is, of course, not ideal to have colleges and universities lag 10 years behind the times. Rather, instead of being prodded by industry, -they should be ahead of industrial needs. There should also be a certain amount of leeway for the student in any college curriculum. All these points had to be considered in drawing up a curriculum, which, instead of being narrowly termed "geology" or "geophysics" was rather called "earth science." It gives the student a chance to specialize in one of the various branches represented by teachers on the faculty of The Pennsylvania State College, giving as options Geology (with subdivisions of Mineralogy and Paleontology), Geophysics, Geography, and Meteorology. Table IA. represents the option of geophysics in the curriculum that envisages that a student may want to make his career in any of the fields encompassed by the American Geophysical Union or in geoexploration. This is, of course, only the start of an education that in most cases will have to be followed by graduate work for complete professional training. The outlined curriculum is definitely of an engineering type and is identical for all of the four options mentioned for the first two years. Specialization will start in the junior year but even thereafter the branches are kept as closely allied as feasible in order to permit a student to change from one to the other (e.g., because of a different aspect in the employment situation) with a minimum of additional work. Table IB shows the geophysics option according to subject matter, indicating the considerable amount of work in the fundamentals of mathematics, physics and chemistry with a liberal number of geology courses, and some engineering. The courses in the field of geophysics are limited-just two lecture courses as a general introduction and one field course, to permit the student a visualization of the correlation between mathematically analyzed physical data and the geological realities. Thesis work is considered essential to teach the student, while he is still in college, some things S. F. Kelly has mentioned as desirable: (I) following of instructions for somewhat independent work; (2) organizing of material, and (3) producing a readable report. This, together with the personal contact with the advising faculty member, will help in forming a student's personality. The seminar course attempts to get the student into the habit of reading current literature, so that he can keep abreast of the times.

Jan 1, 1941

By James Norman

BARITE (BaSO4) is the most important industrial barium mineral from the standpoint of quantity consumed. In 1938 the amount was 365,000 tons. Its uses are numerous, some of the more important being in the production of pigments, as an inert filler in a wide variety of products, as a weighting material in oil-well drilling muds, in the manufacture of some kinds of glass, and in the production of barium chemicals. The barite studied in this investigation occurs as the massive variety in a shale replacement formation near Magnet Cove, Ark. It is intimately mixed with quartz and small amounts of iron oxide and residual shale. Complete liberation of barite and quartz is not obtained when the rock is ground to loo per cent through 325 mesh. The crude rock with which all test work was done assayed 85.1 per cent BaSO4, 11.11 per cent SiO2, and 2.85 per cent R2O3. Its specific gravity was 4.03. It was found in the course of the investigation that the barite contained a small amount of uniformly distributed carbonaceous material, so intimately dispersed that it could not be seen with the microscope, but gave a definite gray cast to the barite concentrates. The color of the barite in polished sections of the crude rock ranged from gray to almost black, while finely ground powder was a reddish gray. The reddish hue was due to the iron oxide present. In 1939, under the supervision of Oliver C. Ralston,* the Bureau of Mines, in cooperation with the Milwhite Company, of Houston, Texas, undertook to study the flotation of barite from Magnet Cove, Ark. Flotation of several southern barite ores had already been investigated by the Bureau of Mines.' The Magnet Cove barite was unique, however, in that it had to be ground to such an extremely small particle size for liberation. The flotation of nonmetallic minerals in the presence of a large amount of slime is usually very difficult and when done is an innovation calling for conditions different from those under which granular material is separated. LABORATORY FLOTATION WORK Preliminary investigation showed that the flotation reagents recommended by O'Meara and Coe1 for separating barite and siliceous material were suitable, but much larger quantities of reagents were required to separate such finely divided material. Moreover, it was found that careful control of the frothing was necessary. When oleic acid and sodium silicate were used a voluminous froth was observed at the beginning of a test, and toward the end there was not enough froth to effect complete recovery of barite. The addition of pine oil as a frother gave proper frothing for the duration of the test, and the substitution of coconut fatty acid (crude lauric acid) for oleic acid produced a more heavily burdened froth. Two different paper-mill fatty-acid products were tested

Jan 1, 1941

By W. L., Yerkes

AN interesting study of the application of air-, conditioning to the problem of mine ventilation and cooling can be found on the Witwatersrand in South Africa. Here there are a large number of deep mines in a relatively small area. Due to the nature of the reef, many mines are working at a depth of 6000 ft. and some have gone down to 8000 and 9000 ft. below the surface. At such depths, even in a country geologically as old as Africa, the virgin rock temperature approaches 110°F. The flow of heat from the- rock to the ventilation air is tremendous though the shaft or drift may have been open to ventilation for some years. In addition, there is the heat produced by machinery, lights, and men at work and the heat of adiabatic compression of air introduced into the mine. The difference in atmosphere pressure between the collar of a shaft and a level 6000 ft. below is nearly 3lb. per sq. in., resulting in an increase in heat content of nearly four B.T.U. per pound of air delivered to the mine at surface. Further the exclusive use of wet mining to reduce the incidence of miner?s phthisis increases the latent- heat content of the air.

Jan 1, 1941

By Augustus Locke, Paul Billingsley

Certain adequately developed mining districts give complete three-dimensional patterns of ore bodies as clusters rising from roots in basement rocks with details controlled by structure of cover rocks. Examples are Goodsprings, Tintic, Bisbee, Leadville, Hedley, Eureka, Ely and Goldfield. In these and others the controlling structures in both basement and cover rock are elements of the neighboring regional structure and have been produced by rock movements in harmony with continental adjustments, which are usually steep tear faults in basement and thrust crumples in cover. Invariably the structures and movements in the districts have long geologic history and result from intersecting or superimposed deformations of different ages. Salt Lake districts show intersecting Uinta and Cordilleran elements; Colorado districts show intersecting pre-Cambrian and Tertiary elements, and Bisbee shows Tertiary superimposed on fina1 Paleozoic folding. Thus the position of districts has been determined by the patterns of North American orogenic belts, which make crossroads in Rocky Mountains and blocks of superimposed deformation in Sierra Nevada, northwest Coastand Canadian Coast Ranges. Essential function of repeated deformation is to strengthen rock, as from shale to slate to schist to gneiss, and thus make it competent to carry channels to depth with or without addition of intrusives. The essence of a mining district is the presence of such competent rocks with long-lived, deep, penetrating breaks reopened to permit passage of heat and associated products from depths to surface. It is suggested that melts such as magmas; metamorphism up to and including granitization; alteration, such as orthoclase-quartz or quartz-sericite or garnet, and also mineralization, may all be by-products of such heat escape along channels made by tectonic forces at specific foci. Magnitudes of Districts (Fig. 1) Any synthesis of ore deposits must deal with comparable units. Ore deposits are innumerable, but great ore deposits, commercially important for a generation or more, are few. The bulk of metals has come from districts of the first and second magnitudes (over $1,000,000,000 and over $250,000,000, respectively), and of these the United States and adjacent provinces of Canada and Mexico contain only 28, of which 9 are first magnitude: Butte, Coeur d'Alene, Bingham, Bisbee, Sierra Gold, in the West; Tri-State, Southeast Missouri, Michigan copper, Sud-bury, in the East. Another 28 or 30 districts are of third magnitude (over $50,000,000).

Jan 1, 1941

By John T. Galey

Production of crude oil for 1940 in southwestern Pennsylvania was off nearly 70,000 bbl., largely as a result of the great number oi abandonments, together with the lack of extension of the Washington and Green County pools. Oil wells completed numbered 51, which is 26 more than last year, but the total initial production of 259 bbl. is only 18 bbl. greater than in 1939. There was an increase of 72 over last year for a total of 209f gas wells. However, 68 7 dry holes were drilled, which is 40 more than a year ago. Thus, 328f wells were drilled during the year, and rigs are erected or drilling is progressing on 59 t more. Shallow Development Oil.—Butler County led in number of oil wells completed, with a total of 27 for an initial production of only 69 bbl. Washington County, with 12 new oil wells, one of which made 40 bbl. from the Fifth sand in S. Franklin township, has 95 bbl., while in Allegheny County 9 wells gave an initial of 86 bbl. for the highest Per well average in the area. This initial was given a considerable boost by one 35-bbl and another 2;-bbl. well in West Deer township, where the Fourth sand produced at 1840 feet. Greene County had only one oil well completed during 1940, and Washington County had 12. The subnormal totals for these counties may be explained by the higher cost of completions and the declining price of crude. The first price change in crude during the year occurred on May 22, when a 25 cut was made. A second 25 cut was made July 12, and was followed by a 156 cut on .Aug. 28. This price held until Nov. 12, when there was a restoration of 156. On Dec. 17 a second 156 increase was put into effect, bringing the price to $I.So per barrel. Gas The large increase in the number of gas wells completed may be attributed to three factors; namely, the recently discovered production possibilities of moderately deep, hitherto little tested horizons, together with increased demand and price. The latter has been made possible by a recent decision of the court, which ruled restraining the public service Commision's prohibition of a raise in the minimum monthly charge to small consumers by one of the major gas companies. A portion of the revenue derived in this manner is being passed along to the producer in the form of higher prices in the field. This higher field rate will remain in effect until a new ruling is made, when it will be reduced in proportion to the reduction of the monthly minimum charge. In an effort to extend the chambers Dam Fifth sand oil pool southwest from Amwell township, Washington County, several wells have been drilled. One of these, in Morris township, washington County, had an initial of 3.2 million cu. ft. open flow from the Big Injun sand. This indicates an entirely new productive area for the latter horizon. Allegheny County had one spectacular well in South Fayette township-—at a depth of about 2500 ft. a 4-million-CU. ft.

Jan 1, 1941

By Martin A. Elliott

Recommendations for safe practices in the operation of Diesel engines underground must take into consideration the hazards that might be created if the composition of the underground atmosphere differs from that of normal air. One aspect of this problem was discussed in the second report6/ of this series, which presented the results of tests in which a Diesel engine was operated with mixtures of normal air and exhaust gas supplied to the intake of the engine. Atmosphere .of this type were studied first because they will be present whenever the exhaust was is discharged into the atmosphere of underground workings in which an engine operates. Diesel engines in underground service may operate in another type of atmosphere, namely, one

Jan 1, 1941