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By N. Brown, M. Herman

IT has been pointed out by Cottrell' and Fisher that long-range order would produce superdis-locations, consisting of two partial dislocations separated by an out-of-phase region. The mutual repulsion of the partial dislocations is balanced by the surface tension of the out-of-phase domain boundary joining the dislocations (Fig. 1). The calculation of the equilibrium spacing of the dislocations has yet to be made. The argument uses the Bragg and Williams theory of long-range order." The metal under consideration is the A-B, body-centered type, such as ß brass. The slip system is taken to be [Ill], (110). Since nearest-neighbor interactions are considered, only the atoms position in the two (110) planes adjoining the slip plane have to be labeled. Corner sites are called a and a' in the top and bottom (110) planes, respectively. Similarly ß and ß are the body-centered sites. Thus, a and ß and 0 and a sites are nearest neighbors. Assume that the bottom plane moves and the top plane is fixed during slip; the atoms in a and ß sites exchange sites but atoms in a and ß sites remain fixed. Fraction of A atoms in a sites, for example, is given by fa and fa. for the un-slipped and slipped condition, respectively. Similarly number of A atoms in the a sites is given by n, and n'a for the unslipped and slipped condition, respectively. As the dislocation moves into the ordered region the change in number of A-A bonds is given by

Jan 1, 1957

By E. J. Yoder, N. B. Aughenbaugh, R. B. Johnson

Mineral aggregates experience degradation during field and laboratory compaction. Reduction in the aggregate size is accomplished by abrasion of the particle edges and fracturing of individual pieces which have become overstressed. Little is known of the factors that govern the amount of breakdown experienced for a given situation. A field study was made of the factors affecting aggregate breakdown under compaction using three carbonate aggregates of different physical properties. The preliminary results indicate that rock type, compactive effort, gradation, and thickness of compactive layer are factors which exert the greatest influence. Mineral aggregates experience a mechanical breakdown of some of the aggregate pieces into smaller fragments during any compaction process, whether in the field or laboratory. This phenomenon occurs as abrasion of the sharp edges during movement and reorientation of the particles in densifying and/or as granulation and fracturing of those pieces which have become overstressed. Two types of aggregate breakdown occur in the field. These may be classed in a general category of aggregate degradation.* One occurs during the con- * Aggregate degradation has been defined in many different ways. For this paper it is considered as any breakdown of larger particles into smaller ones, whether mechanical or chemical. struction period and is related to the densification of the aggregate body from a loose state to a relatively dense mass by heavy compaction equipment. This type is almost entirely a mechanical action. The other occurs after the construction period when the roadway has been put into use. This in-service breakdown is; a different phenomenon from the breakdown during construction in the sense that it combines mechanical with chemical changes. Time becomes an important consideration that may cause subordinate factors in construction degradation to develop into principal ones for in-service breakdown. Breakdown of aggregates in service has been extensively studied by investigators from the northwestern

Jan 1, 1962

By Carl H. Samans

In their recent complete review of the subject of age-hardening,' R. F. Mehl and L. K. Jetter classify the main types of precipitation-hardening alloys under two headings, depending upon the nature of the precipitate and the character of the precipitation. In the alloys falling under the first heading, which display "continuous precipitation" and are typified by the aluminum-copper alloys, "precipitation seems to occur without much regard to grain boundaries and apparently at much the same rate at every point," although an acceleration in regions plastically deformed has definitely been established.2 In the second type of alloys the precipitation is "discontinuous," as in the copper-silver system for example, and "seems to start in restricted regions, primarily those contiguous with the grain boundaries, and to spread inward in an advancing wave." The reasons for the occurrence of these two greatly different types of precipitation are unknown, as are those for many other reactions that take place in the solid state. In the present paper only the first or "continuous" type of precipitation will be dealt with, for which a complete crystallographic mechanism has been worked out for the process of precipitation from a supersaturated solid solution of copper in aluminum. Based upon this mechanism, an explanation of the various property changes found experimentally will be developed in the second paper of this series. In later papers ('discontinuous precipitation" in copper-silver alloys will be explained, and an effort will be made to rationalize the two processes and types of precipitation. Crystallography of the Precipitation Process Through the extensive investigation by R. F. Mehl, C. S. Barrett and F. N. Rhines3 on the Widmanstätten structure in aluminum-rich copper

Jan 1, 1940

By E. W. Schilling

THE-separation of hematite by hysteretic repulsion was first brought to the attention of the public in 1922, by W. M. Mordey1. Three-years later another paper2 was published and after another four years a third paper3 appeared in the South African publications. Certain data were lacking in these papers. In order to continue the work intelligently a knowledge of the shapes of the hysteresis curves for certain minerals was very necessary. This information was not available until the present year4. It was known that reduction of certain ores rendered them amenable to this process of separation but definite data in. the form of curves showing exactly the effect of such treatment were lacking. Prob-ably our best source of information on the separation of minerals by the use of alternating-current magnetic fields today is the reports from the U. S. Bureau of Mines 5-7. It is not the purpose of this paper to tell the reader in detail how to make a commercial separator. Experimental models have recently been made7 and the results obtained have been so good that it is the opinion of the authors that the public will soon take an active interest in the subject and its development. The writers have constructed a separator that is considerably different in construction and operation from the two types described by Mr. Davis. This will be described; but the real purpose of this paper is to outline certain experiments and give curves showing data that have a fundamental bearing upon the practical construction of a separator of this type.

Jan 1, 1936

By David R. Mitchell, R. B. Hewes

MANY processes for cleaning coal that are in use depend primarily on physical properties of coal and refuse other than specific gravity and surface conditions relating to froth flotation. These properties are' shape, coefficient of sliding friction, resilience, friability, magnetic susceptibility, and electrical conductivity. In many of these processes specific gravity does have some effect and many separators are designed to utilize more than one of the physical properties cited. Although the processes described herein do not have a widespread application, yet for specific coals and specific conditions, they are economically important. A problem confronting many coal-mining districts is the marketing of the slacks or screenings and dust passing the final sizing screens. Proc¬esses in commercial use installed primarily to increase the form value, and hence the market value, of these slacks and dusts include briquetting, packaging, and low-temperature carborization. MECHANICAL PICKERS Machines utilizing shape, frictional resistance, and differences in resilience of coal and impurities are usually called mechanical pickers. They require a closely sized feed, therefore their use is confined to the pea, nut, and egg sizes. Various types of these devices are described by Berrisford, 1. 2 Taggart, and Yeele.

Jan 1, 1943

By H. Scott

IN a paper read before the Institute of Metals, Rosenhain 1 described a new type of furnace designed primarily for the thermal analysis of metals by the inverse-rate method and used by him in the metallurgical department of the National Physical Laboratory with considerable success. In his discussion of this furnace, Rosenhain pointed out some difficulties met with in its operation, such as uniformity of rate of heating or cooling being inadequate for the degree of accuracy aimed at. To overcome this difficulty, he suggested, in place of motor propulsion, a gravity drive controlled by a"hydraulic cylinder with a relief valve whose width of opening can he regulated to allow of any desired rate of motion." The authors, in constructing a thermal-analysis furnace of Rosenhain's type, have therefore followed this suggestion and also added certain features that increase somewhat the convenience and simplicity of its operation. Requests for information regarding this furnace and the highly satisfactory results obtained from its use, it is believed, justify describing its construction and operation in sufficient detail to make possible its duplication or improvement. Description of Furnace.-The details of the furnace construction are shown in Fig. 1, which is drawn to scale. The heating tube is of /4 in. (6.35 mm.) wall "alundum" heated at the upper end by seventeen turns of 0.52 mm. platinum wire, which is coated with "alundum" cement supplied for this purpose. The cement coating is essential when a high temperature (over 1000° C.) is required, as it prevents hot spots with the resulting burning out of the heater. This platinum-wire winding, unlike "nichrome," is entirely satisfactory for temperatures of at least 1000° C. It has been maintained at that temperature continuously for 2 months and shows no signs of deterioration. This temperature is maintained by a current of 5 amp. drawn from 30 volts potential, so its necessarily continuous operation is quite economical.

Jan 8, 1919

By Strathmore R. B. Cooke, Iwao Iwasaki, C. S. Chang

PYRRHOTITE has long been considered a gangue mineral to be eliminated as tailing in the treatment of various sulphide ores. However, in recent years the world-wide lack of sulphur resources has called attention to this mineral as a potential source of both sulphur and iron. Its importance as an economic mineral, however, has not been particularly emphasized. For this reason very little is known about its response to flotation, except that it can be depressed easily in alkaline circuit, by long aeration,1,2 addition of oxidizing agents3 or by starch.4 The object of this work was to study the floatability of pyrrhotite. This includes the effect of oxidation by aeration, of copper activation, and of change in pH.

Jan 2, 1954

SUMPEARY OF CURRENT PRACTICES History The outcrop and surrounding area of Comincots Sullivan Mine was originally mined by small open cuts on surface and small open stopes underground to which shafts and adits were driven for access. When it was established that a commercial grade of ore was available, an adit was driven on the 4600 level (feet above sea level), and OM was extracted by larger scale open stoping leaving supporting pillars where necessary. After the depth of the ore body was proven to the 3900 level and an adit driven at this level, many miles of drifts, crosscuts, raises and sublevels were driven for the extraction of the ore above this level. Larger open stopea were extended from this development. The mining method was, and to a very limited degree still is, a benching method. Due to the strong hanging wall in this area of the mine, stopes with a width of 100 feet or more were opened. In 1931, because the orebody was proven to extend below the 3900 level, a winze was sunk from the 3900 level to the 3350 level. From this winze three intermediate levels were opened. Following a plan of development well in advance of production requirements, further sinking was done by winzes and eventually a large shaft was raised to surface. Prior to 1958 the 2850 level was bottom which since that time has been extended to the 2500 level. Open stopes were developed and mined as this area was opened up.

Jan 1, 1970

By A. R. Denison

This field in 1933 continued as in 1932, although to a much less extent, to dominate the drilling and production situation throughout the oil business. The 2466 producers completed in this field during the year are 28 per cent of such wells completed in the United States. The 2556 completions reported in the five counties within which the East Texas field lies are 21 per cent of all such wells reported in the United States. It follows that with such a command of the development situation, every other factor with regard to this field has an important bearing on the entire oil business. As a consequence, the important developments in the East Texas field are the important developments of the year. Very little new productive territory was added to the already known limits of this enormous field. On the other hand, drilling has shown that with a few very minor exceptions this field is a continuous productive area, with a regular outline and no "dry spots" other than that of a single well surrounded by producing wells. Drilling was confined to the already proven limits of the field. This consisted essentially of more adequate coverage of leases by wells, the meeting of required offsets and the drilling of a large number of small tracts which developed from subdivision of larger leases due to court action and other causes. The allowable throughout the year was, with minor variable factors, on a per-well basis. With the steady decline in per-well allowable after May, every operator was faced with declining

Jan 1, 1934

By R. Buehl

ALTHOUGH the main features of the transformations occurring in 18-8 have been published already,1-4 certain conclusions merit questioning and discussion. The questions may be summarized as follows: PERCENT REDUCTION BY COLD ROLLING FIG. 1.-VARIATION OF FERRITIC INDUCTION AND PERCENTAGE OF FERRITE WITH COLD REDUCTION. Composition of Alloy: C, 0.08; Mn, 0.40; Si, 0.24; P, 0.014; Cr, 18.13; Ni, 8.94. 1. If ferrite is formed by cold-working austenite, what happens to the carbon with which the ferrite and austenite are both pre-sumably supersaturated? 2. What is the nature of the alpha-ferrite formed at grain boundaries by chromium-carbide precipitation at these boundaries?

Jan 1, 1939

By F. E. Crane, H. A. Kendall, G. H. F. Gardner

Two effects of a difference in density may be observed in miscible displacement. As the difference is increased from zero there is first a change in mode from multiple fingers to a single finger. A further increase results in a more rapid growth of the single finger. Miscible displacement with multiple fingers has been discussed by Blackwell, et al, whereas miscible displacement with a single finger has been discussed by Craig, et al. In the present paper experiments are described which bridge the gap between these extreme cases. INTRODUCTION Craig, et al,1 investigated the effect of gravity on frontal displacements for circumstances in which the gravity forces were significant. Blackwell, et a1,2 dealt with the other extreme in which gravity forces were negligible. The considerable difference between their results is illustrated in Fig. 1 where the breakthrough recoveries are plotted against the mobility ratio. The experiments described in the present paper were conducted to examine how the transition from the one extreme case to the other occurs when the gravity forces are gradually reduced. The transition is well illustrated by the production history after breakthrough. Fig. 2 shows how the number of pore volumes which must be injected at a constant rate to displace 98 per cent of the original fluid depends on the gravity force. For each mobility ratio there is a transition range, and a very significant change in the number of pore volumes occurs when this range is traversed. This range of the gravity force is physically linked with the formation of viscous fingers. A single finger is predominant for larger gravity forces; a multiplicity of fingers is formed for smaller gravity forces. Improved recovery and the occurrence of multiple fingers is concomitant with a large increase in the amount by which the fluids are mixed within the porous medium. The transition range depends on all the dimension-less groups which characterize the problem; but this dependence has not been exhaustively studied as yet and only fragmentary results are discussed in this paper.

By Guilliaem Aertsen

THE derivation of the word tire (or tyre, as it is spelled in England) is obscure. Some dictionaries suggest that it is the aphetic form for "attire, covering," so called as being the outside covering or band of a wheel; also as a corruption of "tier," the band which holds, or "ties," the rest of the wheel together. One dictionary states: "The supposed derivation of the word is that bands were first used on wheels in the City of Tyre, Syria. " In the infancy of railroads, the tracks consisted of flat baits of iron, spiked or bolted to the upper surfaces of longitudinal timbers, which; in turn, rested upon masonry foundations. Stone blocks installed for this purpose on the old Germantown & Norristown Railroad, now the Chestnut Hill branch of the Philadelphia & Reading Railway, were to be seen for many years on the right-of-way, north of what is now. Wayne Junc-tion, Philadelphia, Pa. The "cornerstone" of the Baltimore & Ohio Railroad was laid Apr. 4, 1828, and the first locomotive in America was built by Peter Cooper at the St. Clair Works, Baltimore, Md., in 1829 "to demonstrate its adaptability to a curved road." It is believed that the first successful locomotive was built in Philadelphia by Tyler & Baldwin in 1832 for the Germantown & Norristown Railroad. Rufus Tyler-and Matthias Baldwin were brothers-in-law; the latter's name will he identified with American locomotives until locomotives are forgotten. The Wheels on these first locomotives, designed to run on this primitive rail, were shod with plain iron bands, bent and welded. The flanges consisted. of separate iron bands, bent sidewise, welded, and, bolted to the sides of the wooden follies, or rings. Before many years had elapsed the tires were fabricated of iron bands, rolled in one, piece with the flange projection on the side. The tire for each wheel was bent and welded and subsequently attached to the wheel center by shrinkage, bolts, rivets and various mechanical devices.

Jan 1, 1917

PRIOR to the World War most of the barite used in the United States for manufacturing lithopone and barium chemicals was imported. Germany, by virtue of an abundance of high-grade ore and low labor costs, was in a position to dominate the world market. With the cessa-tion of imports and with the war demand for barium chemicals, the barium chemical industry and the mining of barite became well; estab-lished in the United States. This industry has continued to expand because of the increasing use of lithopone. In 1914 the sales of domestic crude barite was 52,919 tons and in 1934 it was 209,850 tons. Barite deposits of economic importance occur in at least 20 states, but the principal producers in 1934 were Missouri, Georgia, Tennessee, South Carolina, Virginia, California and Arizona. The main mining centers are located near the crude barite markets of the three principal marketing districts-the Pacific Coast, the Midwestern area, and the Eastern area. The Pacific Coast is supplied entirely by California, Nevada, and Arizona. The Midwestern area uses most of the Missouri crude and a small amount from the southern states. The eastern market is the chief competitive area. Practically all of the imported crude is marketed there; also the bulk of the southern crude and ground barite. In addition, this area absorbs a small part of the Missouri crude and 80 per cent of the ground barite. Besides the advantage of low delivered costs and purity of product, the imported barite has commanded a price differential because it is soft rather than hard, like many of the domestic ores. The inherent physical properties of the southern ores remain, but the purity can be controlled to a great extent by beneficiation. Simple washing or gravity concentra-tion has sufficed in the past, but in many cases a more efficient process now becomes imperative to remove impurities not amenable to these methods. Certain deposits now being opened are of lower, grade and require more precise milling conditions. In some ores, the kind of impurities has changed as the mining advanced.

Jan 1, 1936

By J. N. Ong, J. P. Ratledge, J. H. Boyce

Since German operators opened the Tsumeb mine in the early 1900's, continuous operation has been interrupted only by enforced shutdowns during two world wars and the depression of the 1930's. Original metallurgical practice was blast furnace smelting. This was applicable only to low zinc ore, leaving large tonnages of high zinc ore to be stockpiled on the surface. A gravity concentrator using tables, buddles, and jigs operated for several years, but differential flotation of the ore did not get beyond the experimental stage. When the property was put up for sale by the South African Custodian of Enemy Property there was an estimated 434,000 tons of ore on surface dumps. The dump material, assaying 4.48 pct Cu, 15.8 pct Pb, and 10.9 pct Zn, had become highly oxidized during a stay of many years on the surface. But these dump ores had to be used in evaluating possible metallurgy because the shaft became flooded after the 1940 shutdown and underground ore was unavailable. Many companies examined Tsumeb but quickly lost enthusiasm because of the formidable metallurgical problems presented by the dump ore. However, on the basis of extensive test work, the present company decided that differential flotation would be successful and purchased the property after competitive bidding.

Jan 4, 1955

By Dorsey Hager, G. W. McPherson

The rapid increase of water troubles in the Mid-Continent oil fields is causing much alarm. Troubles occur at Towanda, Eldorado, Augusta, Cushing, Blackwell, and Healdton, although they had not been acute in the Mid-Continent field until about two years ago, when the unusual conditions in the deeper oil fields were first encountered. California faced the same situation, but, thanks to aggressive measures, has largely overcome the dangers. The following analysis of water trouble may throw some light on the subject and be of assistance in solving the problems involved. Water Troutles Classified The presence of water in large quantities in oil sands has the following results: 1. Diminishes oil production. 2. Diminishes casing-head gasoline production: (a) By curtailing the gas flow. (b) By making the use of vacuum pumps unsuccessful. 3. Increases lifting costs: (a) By making it necessary to pump large quantities of water, which requires a fast motion and long stroke (third hole). (b) By requiring the use of compressors for air lift. (c) By causing break-downs and delays due to the high speed necessary to pump water. (d) By making it necessary to treat "cut" or emulsified oil. Oil production is seriously curtailed by the presence of large quantities of water. Lease records show that wells are shut down 40 to 60 per cent, of the pumping time where serious water trouble occurs. While a small quantity of salt water may cut the paraffine and keep the oil moving, several hundred feet, or a hole full of water, effectually "kills" the oil and gas. The quick return of wells to production, once the water is shut off, shows how wells have been affected. The killing of gas sands

Jan 1, 1920

By A. L. Field, P. H. Royster

Bureau of Mines Technical Paper 189 consists of a record of the scientific data obtained in the iron blast-furnace slag investigation which is reported in Technical Paper 187, "Slag Viscosity Tables for Blastfurnace Work." It includes a description of the method of preparing the synthetic melts, construction of an improved electric furnace, and refinements in laboratory methods of measurement. Only the general features of the work and the conclusions drawn from the experimental data can be given attention here. Silicates in the Liquid State In the manufacture of refractories, Portland cement, glass, and porcelain, and in pyrometallurgical operations, importance attaches to the behavior of-silicate compounds at temperatures beyond the range of common experience. This field of research has not been investigated as carefully as its scientific and industrial importance would seem to warrant. Probably the most important of the unsolved problems in the chernistry of silicates is the question of their stability in the liquid state. That little progress toward the solution of this problem has been made is not strange if there be borne in mind the difficulties attending experiments made at temperatures at which silicates become fluid, and the comparatively short time since it became possible to measure these temperatures. On the other 'hand, considerable progress has been made in the study of the compounds in the solid state because of the directness and simplicity of methods of optical examination. Important advances have been made by the Geophysical Laboratory at Washington in recent years. An extended study has been made there of saturated solutions representing a considerable number of binary and ternary systems of the more common refractory oxides. The methods

Jan 1, 1918

By AIME AIME

A STUDY of subsidence and ground movement in the copper and iron mines of the upper peninsula of Michigan has been made by W. R. Crane of the United States Bureau of Mines and published as Bulletin 295 of 66 pages and 49 illustrations. As a result of subsidence, the country adjacent to the mines and over- lying the mine workings in this district is often broken to such an extent as to affect its value; mine shafts and development openings are occasionally so damaged as to be rendered useless, and water can enter the workings through fractures and cave-ins. The problem is more serious in the iron-mining districts, where villages and towns not owned by the operating companies have grown up around mining operations.

Jan 1, 1929

By Warren B. Weeks

The development of the relatively deeper fields discovered during 1937 helped build the 1938 production to 18,456,760 bbl., an increase of 6,295,910 bbl., or 51.6 per cent over 1937, and the largest production for south Arkansas since 1930. Schuler and Rodessa accounted for the increased production as well as for over half of the wells drilled in the state. There were 243 holes drilled during 1938, of which 200 were completed as oil or gas wells. Of the 29 wildcat wells completed, 25 were dry, 3 found oil in the Smack-over limestone, while 1 made a small oil well in the Nacatoch sand. This was less than half the number of wildcats drilled the previous year, but nearly twice as many field wells were drilled. The old depth record of 7973 ft. was exceeded twice during the year, with the present record of 8332 feet. Trend of Prospecting The porous "Reynolds" oolite of the Smackover limestone1 has been the object of most of the wildcat prospecting during the past two years. Seismograph work, which brought 22 crews into this area during 1938, was largely pointed toward a study of the structure of this limestone formation. Thirteen dry wildcats have been drilled to this formation and five pools have been opened in it since it was first found to be productive at Snow Hill in the spring of 1936. With the failure of "updip" prospects to produce, activity moved southward and basinward. Success in five instances in Columbia and south Union Counties has spurred activity in this area. Much of the acreage is under lease and half a dozen deep limestone tests are assured for the current year. Fig. 1 shows the location of the principal oil fields in south Arkansas, as well as one or two minor producing areas. The fields are numbered in the order of their discovery. It is shown that most of the recent discoveries are from the deeper formations. Dry wildcats that penetrated

Jan 1, 1939

By L. H Levenson, Charles S. Barrett

The orientation of metal crystals and grains, both large and small, can be detcrmined conveniently and accurately without the use of X-ray apparatus. This seems to be appreciated by so few metallurgists that it may be useful to explain in detail the method we have found most satisfactory in the laboratory—the reflection of light from crystallographie etch pits. This note includes a description of a suitable inexpensive instrument and instructions for etching various metals and for plotting the data. As the stereographie projection is used to facilitate handling the data, this note may he considered as an appendix to an earlier review of the metallurgical uses of the stercographie projection.' Various methods involving etch pits have been used by other investigators. Bridgman's method2 consists of attaching the specimen to a sphere (a transparent sphere is convenient4 , holding it at arm's length, and marking a spot on it when it has been turned so that the eteh pits reflect light into the eye of the observer from a lamp standing behind him. It has an accuracy of about 2" and is extrernely rapid. A greater accuracy can be obtained by having the reflected light fall on a screen, as has been done by Czochralski,5 Chalmers,6 and Schubnikov.7 All of these methods have been intended for undeformed single crystals. Tammann and his coworkers3,8 developed a method for estimating the number of grains in a polyerystalline aggregate having orientations in a given region of the stereographic triangle and thus obtained statistical information about deformation and reerystallization textures. While the method has had some use in recent years,9 it is not applicable to the majority of problems in physical metallurgy. Smith and Mehl10 determined orientations by plotting the directions of the sides of individual etch pits on a stereographic projection. The accuracy is limited to about 3" and the method requires careful polishing and high magnification.

Jan 1, 1940

By B. B. Zavoico, J. G. H. Crump, P. P. Gregory

West Texas was the scene of greatly increased oil activity during 1937, producing 75,743,000 bb1.l in that year as compared with 61,901,-000 bb1.2 in 1936, an increase of 22.36 per cent. The annual total of wells completed increased from 15863 in 1936 to 28062 in 1937, an increase of 76.92 per cent. Of the total completions in 1937, 2464 were oil wells,2 11 gas wells2 and 331 dry holes.2 The marked increase in the number of oil wells completed in West Texas during 1937 had a substantial effect upon the daily average production per well, which decreased 20.84 per cent from December 1936, when a total of 5310 wells3 produced 5,236,467 bbl.3 for an average of 31.81 bbl. per well per day to December 1937, when 7571 wells2 with a total production of 5,910,257 bb1.2 averaged 25.18 bbl. per well per day. Drilling blocks and checkerboard acreage were being acquired following geophysical work in the northern end of the Permian Basin area, composed of Bailey, Cochran, Hockley, Yoakum and Terry Counties, presaging extension of active development northward. During 1937, at one time 30 geophysical crews were working in West Texas, and an average of 15 to 20 crews was active in this area throughout the year. Discoveries Wasson-Denver Field.—Wasson-Denver field in Gaines and Yoakum Counties was the outstanding field discovery of the year. Production is from porous limestone found at about 5000 ft., and an average well is good for from 300 to 500 bbl. of crude oil per day through 3/4-in. choke. The discovery well was drilled by A. G. Carter and others on the Wasson Ranch, Gaines County, and the field has since been extended into Yoakum County. At the year's end 21 wells had been completed, producing

Jan 1, 1938