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MR. Woo's succinct description of the mining and smelting of silver-lead in Mongolia, with the roasting-and-reduction process and cupellation, has much interest as a picture of methods that not only may have been in use, as he suggests, a thousand years ago, long before the existence of mining schools or chemical laboratories, but probably vary little, if at all, from the practice of prehistoric times, when King Priam's handsome silver vases, cups and bowls were formed. For it is highly improbable that such large objects were made from comparatively rare native silver, and the metal must have been smelted from ore, and most likely in great part from galena,, with cupellation of the lead. Dr. W. A. P. Martin, in his excellent book on the Lore of Cathay, points out that Chinese alchemy is over 2000 years old, antedating the European by at least six centuries; and he infers that the Chinese skill in metallurgy and many branches of practical chemistry owes its origin to " those early devotees of the experimental philosophy who passed their lives among the fumes of the alembic." Those alchemists, however, may have more likely derived some of their leading ideas from the mys terious, and at that time wholly unexplainable results observed in already very ancient metallurgical processes; in which, for example, certain stones were transmuted, as it were, into metals widely divergent in character from their ores, and even silver and gold were obtained from the most unlikely-looking mate rials. It is therefore, in any case, not improbable that the Chinese may have preceded western nations in the discovery of metallurgical methods. At all events, it is now evident that the Japanese acquired these arts from China, the former source of all their higher civilization. My own observation of old-fashioned silver-smelt ing at Hosokura, on the main island of Japan, and about 220

Jan 1, 1903

By Charles Hardy, George D. Cremer

POWDER metallurgy has been established for some time as a novel method for manufacturing a great variety of articles generally specialties that could not be made conveniently by any other method. In this category are such parts as porous hearings cutting tools of sintered carbides, and electrical contacts in which the metallic constituents do not tend to alloy in the proportions employed. The industry, however, is now at a stage where it has begun to manufacture articles that can and have been made by other methods. Thus, powder metallurgy is now preferred technique for the production of numerous machine parts characterized by high strength, accuracy of configuration, and substantial lack of porosity. Manufacture of such machine parts from metal powders has no doubt been stimulated by the war, although the trend in this direction has been apparent for several years. In any case, quantity production of high-density precision pieces by ponder metallurgy is now in full suing in the United States, and such production can and should continue to expand during and after the war.

Jan 1, 1942

By Jacques B. Wertz

Both the San Andreas fault complex and the Murray fracture zone are apparently found to be contemporaneous with the Laramide mineralization period. Their compounding effects certainly have disturbed the Texas lineament belt and its components with serious lateral offsets and most probably have been instrumental in allowing intrusives to be emplaced as well as mineralization to accompany these intrusions at some of the fracture intersections. While the main fracture centers can be almost accepted as being structurally linked together, the Texas lineament trend definitely predominates, exerting a prevailing direction to graben (Silver Bell) and to elongated depressions (Bisbee). That this lineament belt also influenced the concomitant mineralization seems a logical inference. The orebodies are generally found at intersections near the most centrally-located intrusive with a distance varying from contiguity to one or two miles. The Southeast Arizona copper province owes its existence primarily to a particularly favorable structural setting of broad semi-continental scope. Thus, various regional structural elements are to be considered as possibly direct or remote cause for the widespread mineralization, although the one or the ones really responsible may never be singled out. There arc three basic regional elements: (1) The north-northwest-trending anticlinorium that diagonally crosses Arizona is quite obvious because many mountain ranges follow this direction. This anti- clinorium, which merges northward into the Wasatch-Jerome Belt, marks a broad zone of weakness where tension seems to prevail. Mineralized trends such as Jerome-San Manuel-Bisbee may give some weight to the economic value of this structural element. (2) Northeast-trending fractures, parallel to the Colorado Mineral Belt (Landwehr, 1967), appear troincident with mineralization as evidenced by the Questa-Grants-Morenci and the Lordsburg- Tyrone-Santa Rita alignments. This structural direction is accepted as one of the most economically significant in the Southwestern United States. (3) The Texas Lineament.

Jan 1, 1970

By Mehmet Guney

At the Armatcuk mine in Turkey, various modifications of sublevel methods have been tried during the last decade in an effort to eliminate gob fires, dangers from roof falls, and surface subsidence, and also to increase extraction efficiency. From the experience thus gained, it was decided that the most likely system to give maximum benefits, considering the existing geological conditions and coa1-seam characteristics, was hydraulic stowing. This paper examines trends in the working techniques of hydraulic stowing and discusses the favorable results and technical problems that the method produced at Armutcuk. The Armutcuk mine, a subsidiary of Eregli Coal Mines (EKI), produces 1300 tons of run-of-mine coal daily from thick (about 10-90 ft) and highly dipping (about 50-90°) coal seams. The coal is highly volatile with good coking properties that make it highly suitable for industrial use. Most of this coal is used in the iron and steel industry at Eregli on the Black Sea coast. Complete recovery of the coal is of vital importance to industrial development and progress. Initial coal extraction was carried out by means of a sublevel mining system modified to accommodate local geological conditions and coal seam characteristics. This method is similar to that employed in metalliferous mines. Several problems arose from the application of the method, one of them being the prevalence of gob fires which caused periodic shutdowns in some sections. To achieve maximum coal extraction with minimum dilution, to eliminate gob fires and surface subsidence, and to reduce fatal accident rates, a decision was taken to change from this method to a hydraulic stowing system. The pres- ence of large deposits of conglomerate and sandstone on the surface contributed to the decision to employ this new method. Although hydraulic stowing practices have been carried out in America and Germany, Upper Silesia may, so far as coal is concerned, be considered the birthplace of the method. Here the process was adapted to thick coal seams on a large scale to reduce dangers from gob fires and damage from surface subsidence. Today, the mining system is not only widely used in the coal mines of France, the Saar, India and Poland, but has also been successfully applied to the iron ore and potassium salt mines in Russia and Germany. LOCATION AND HISTORY The Kandilli-Armutcuk coal field, the most western outcrop of the North Anatolian coal basin, extends for five miles along the Black Sea coast (Fig. 1). The Armutcuk Mine is situated on the southern boundary of the coal field about 40 miles from Zonguldak and about 12 miles from Eregli. The history of coal mining in the North Anatolian coal basin goes back more than a century. Mining commenced on a small scale in the Kandilli-Armutcuk coal field in the late 1880's, and from this time until nationalization in 1940 the mines were operated by private Turkish and foreign interests. In 1940, Eregli Coal Mines was established to takeover the management of these enterprises. The Armutcuk Mine was developed for the first time in the mid-1940's. Since then it has been in continuous production and it now produces an annual 440,000-ton run-of-mine output from which 320.000 tons of salable coal is obtained. MINE GEOLOGY The carboniferous inlier of the Kandilli-Armutcuk coal field crops out over an area about three miles long and one mile wide. The major part of the inlier consists of the Namurian formation with only a relatively small area of Westfalian-A visible on the surface (Fig. 2). The Namurian formation, which has no exploitable coal seams in the Armutcuk Mine, consists mostly of arkose sandstones and black shales often having

Jan 1, 1969

By F. Lowell Lawrance

JOHN SMITH, citizen of the U.S.A., has become so accustomed to reading that Congress has appropriated billions of dollars to pay war costs. that he no longer is impressed by relatively small figures, such as several hundred thousand or a few million, in connection with Government departments.

Jan 1, 1944

By A. E. Anderson, H. J. Hilll

Laboratory data for 155 field muds and 77 .shales have been used to develop correlations to estimate the net streaming potential component of the SP. Analysis of these data and comparison with field tests show that streaming potential corrections must be made to obtain an accurate estimate of the electrochemical potential for use in the determinntion of formation water resi-iiviy. The self-potential curve is related to formation water resistivity, and considerable effort within the oil industry has been directed toward clarifying this relationship. The Schlumbergers and Leonardon1,2 recognized that two types of potentials, electrochemical and electro-kinetic, resulted in the net potential variation in the borehole. Most of the later papers have dealt with the electrochemical component and its controlling parameters. The investigations of Wyllie,2" Salisch' and Moore5 provide the most extensive sources of data on streaming potentials across mud cakes. These authors observed streaming potentials of sufficient magnitude to be of critical importance in SP interpretation, if it is assumed that streaming potentials develop only opposite permeable beds. Streaming potentials across shales have been reported by Schenck and by Gondouin, et al.7 Since SP magnitude is the difference in potential opposite shale and sand beds, these authors suggested that the net streaming potential component may be negligible. The present investigation was initiated to evaluate empirically some of the parameters controlling the magnitude of the net borehole streaming potential and to determine whether useful relations between mud properties and net streaming potential could be established. Field muds were used in this investigation. These muds were characterized by the amount and type of chemical treatment utilized for five days before Sampling. Filter loss, mud resistivity, mud density and filtrate resistivity were determined for each mud with conventional methods and apparatus. Mud filtrate pH was estimated with Hydrion pH paper for the appropriate range. Streaming PotentIals Across MuD Cakes Commercial calomel-saturated KC1 electrodes are subject to potential changes attributed to contamination of the very small fiber-tip bridge by particles of clay from the drilling mud.3 To minimize this difficulty, a large diameter bridge (Fig. 1) was constructed with saturated KC1-agar gel and a filter disc of microporous porcelain. Experiments showed that streaming potentials across this bridge are less than 0.2 mv at pressure dif-

By AIME AIME

WITH the recent increase in the price of gold, its economic recovery at depths formerly considered impractical has become a present possibility. Two important difficulties must be met: pressure bursts of the rock, and the reduced efficiency of human labor subjected to the higher temperatures and the increased humidity at the greater depths. In the following abstract of a paper by J. H. Dobson, presented before the South African Institution of Engineers on

Jan 1, 1935

By T. K. Perkins, L. R. Kern, R. E. Wyant

Many factors influence the results of hydraulic fracturing to stimulate well productivity. Most of these factors have been studied and their effects discussed in the literature. However, the movement of sand through the crack during fracturing has received little consideration. Exactly where the sand goes in the fracture, how it gets there, and how this might influence results have not been studied, judging from published reports. To get an answer to some of these questions we have studied sand movement through a simulated crack segment in the laboratory. Although the work is preliminary, we have answered some questions about sand movement in a semiquantitative sense. We are reporting our results at this time in the hope of stimulating interest and further study in this important aspect of fracturing. LABORATORY EXPERIMENTS Fig. 1 is a schematic diagram of equipment used in this study. A segment of a vertical crack 0.25-in. wide was formed between two Plexiglas plates, and movement of sand in fluid through the crack was observed under various conditions. Sand and fluid were injected into the crack at constant rates. The top and bottom of the crack were closed so that the fluid flowed horizontally. Because of gravity most of the sand settled to the bottom before moving very far through the crack. If the fluid velocity exceeded a certain critical value, then all the sand injected was washed on through the crack even though it had settled to the bottom. When the fluid velocity was less than this value when sand injection was started, most of the sand which settled in the crack remained in place until enough of the area open to fluid flow was blocked by the settled sand to increase the fluid velocity to the critical value.. At this point all injected sand moved on through the crack even though it settled to the lower portion of the moving fluid section. All sand previously settled remained in place. When fluid velocity was increased at this paint by increasing fluid injection rate (without also increasing sand injection rate), some of the previously settled sand was washed out until enough area was open to flow that the velocity dropped to the critical value. Conversely, when the fluid velocity was decreased by decreasing the fluid injection rate (without changing the rate of sand injection), additional sand would settle until the critical velocity was again attained. In short, the critical velocity is an equilibrium value which the system will automatically seek, if possible. The equilibrium (or critical) velocity was measured under several conditions. The results of these measurements are shown in Pig. 2 where the equilibrium velocity is shown as a function of the amount of sand injected per minute. The points falling in the shaded band shown in Fig. 2 were obtained with water. The higher viscosities were obtained by adding CMC (carboxymethylcellu-lose). Data indicate that the equilibrium velocity is not very sensitive to sand size or transport fluid viscosity, or to sand injection rate (except at very low rates). Points connected by the solid CUrve in Fig. 2 were obtained with water and 20- to 40-mesh steel shot. The equilibrium velocity is apparently fairly sensitive to difference in density between particle and fluid. Only one run was made with a gelled fluid and that was gelled water at zero sand injection rate as shown in Fig. 2. (Measurements of equilibrium velocity at zero sand injection rate were made by filling the crack

By R. C. Earlougher

Jan 1, 1970

By Claus G. Goetzel

POWDER metallurgy is known as the art of producing metal powders and fabricating them in a nonfusion process by a simultaneous or consecutive application of pressure and heat under controlled operating conditions. Before the advent of powder metallurgy, the high melting points of the refractory metals and nonmetals made their manufacture and use practically impossible. Today, however, the uses of refractory materials in high-speed cutting tools, surgical instruments, brake linings, electrical contact switches, and filaments in incandescent lamps are commonplace in industry. Lately designers have even been turning to powder metallurgists to develop new techniques of fabricating refractory materials for extreme-service use in high-temperature zones of such modern products as gas turbines and jet engines. The new techniques being born will undoubtedly provide industry with a great number of new alloys and materials for future designing.

Jan 1, 1948

By J. A. Berger, R. J. Towner

The pjPocesses of polygonization and subgrain growth were followed in slightly stretched 99.99 pct A1 single crystals heated for cumulative times at 400°, 500°, and 600°C. Changes in sub-grain size and boundary angle were determined from measurements on X-ray micrographs. CAHN1, 2 studied polygonization in stretched and heated aluminum single crystals of 99.99 pct A1 using various techniques, including etch pits, Laue patterns, and a slight restretching of heated specimens to reveal small changes in lattice orientation by the direction of new slip lines. He found that kink bands, which had well-defined boundaries lying in a plane perpendicular to the slip direction (at least in the early stages of deformation), formed during stretching. Also, he noted that bending occurred about the <211> axis lying in the (111) slip plane perpendicular to the <110> slip direction. His studies of polygonization were largely confined to the kink bands rather than to the weakly bent matrix regions between bands. The minimum temperature required to bring about polygonization was established at about 450 "C. Guinier and Tenevin used a focusing Laue X-ray diffraction technique to study polygonization in aluminum single-crystal specimens of 99.99 pct purity. Stretching the crystals 5 pct in tension caused a widening of the focused Laue spots. After heating for 4 hr at 450°C, their method revealed no change in the specimen. Above 450°C polygonization was detected and further annealing near 600°C led to subgrain growth. They concluded that the orientation of the crystal relative to the axis of deformation had no marked effect on polygonization. Gay and Honey-combe4 using an X-ray microbeam technique found that polygonization did not occur in a stretched aluminum crystal heated at 250oC, although some decrease in the yield strength occurred. When the temperature was raised to 475oC, the asterism became broken up as a result of polygonization. Honeycombe5 noted that reflections on X-ray mi-

Jan 1, 1961

By C. E. Melbye

A serious problem confronted the city of Gunnison early in 1958 in that, for a few months during each spring runoff, the water supply derived from the Gunnison River became polluted to an unsafe point. The city management had the choice of building a new filter plant to replace the old unworkable one or drilling wells to develop a ground water supply. The cost of a new filter plant was estimated at $180,000 compared to $50,000 for 6 wells, pumps, and additional water lines, hence their decision to attempt the development of sufficient ground water. Six wells at 300 gpm per well were estimated as necessary to handle the peak usage of 1800 gpm, compared to only 600 gpm winter usage. Although the water table is only about 7 feet below the surface, existing private wells drilled at random locations were producing much less than 300 gpm. The problem was to find sufficient quantities from about 6 wells. Since the presence of an ancient bedrock channel was suspected, which would be expected to localize greater quantities of water, the city of Gunnison authorized a resistivity survey to investigate bedrock topography below unconsolidated gravels. Survey results were highly satisfactory and led to the preparation of a fairly detailed bedrock contour map, Fig. 1. This map was used in selection of all well sites. The city of Gunnison is situated in a flat, broad, Quaternary gravel-filled valley (terrain dips south at 20 feet per mile) at the junction of the Gunnison River and Tomichi Creek. The valley, about 2-4 miles wide, is bordered by hills of Tertiary volcanics to the northwest, Cretaceous and Jurassic sediments to the north and northeast, and pre-Cambrian granite and gneiss to the south. One previous deep test well at the west end of the city hit pre-Cambrian granite at 496 feet, which, allowing for 40 feet of surface gravels, makes the older sedimentary section 456 feet thick. This section is probably all Jurassic Morrison formation, consisting of the Saltwash sandstone overlain by the much thicker section of Brushy Basin shales and mudstones. According to the driller&apos;s logs, each well was bottomed in what is believed to be Brushy Basin shale. FIELD PROCEDURE A standard Gish-Rooney type of resistivity apparatus was employed, which used 45-volt dry batteries as a direct-current power source. Applied voltages could be selected from 45 volts to a 270-volt maximum. Copper-coated steel stakes were employed as current electrodes and porous porcelain pots as potential electrodes to avoid possible polarization effects with direct current. The expanding Wenner electrode configuration was utilized for this investigation and measurements were made at 20 40, 60, 80, and 100-foot spacings,

Jan 1, 1961

Organization Place Date 1917 American Electrochemical Society Pittsburgh, Pa. Oct. 3-6 American Institute of Mining Engineers St. Louis, MO. Oct. 8-13 American Gas Institute : Washington, D. C. Oct. 16-19 American Institute of Architects Philadelphia, Pa. _ Dec.. 26-29 American Society of Mechanical Engineers New York City. Dec. 26-29 American Mining. Congress State Chapter Phoenix, Ariz. Dec. 26-29

Jan 10, 1917

By AIME AIME

EVERETTE LEE DEGOLYER, past President of the Institute and Anthony F. Lucas Medalist, was presented with the John Fritz Medal at a dinner at the Wal-dorf-Astoria Hotel in New York, Jan. 14. Dr. DeGolyer is the third representative of the Institute in recent years to receive the John Fritz Medal which is awarded jointly by the four Founder Engineering Societies through a board composed of sixteen past presidents. In 1938 Paul D. Merica was given the award "for important contributions to the development of alloys for industrial uses" and in 1933 the distinction was given to D. C. Jackling "for notable industrial achievement in initiating mass production of copper from low-grade ores through application of engineering principles."

Jan 1, 1942

By AIME AIME

WAR undoubtedly accelerates metallurgical progress, although its most obvious effect is a tremendous waste of materials. The necessity for restrictions in normal uses of metals results in a search for substitutes or for enhanced properties that will make a limited supply last longer. An insatiable demand for more metal to be produced more quickly favors trial of new processes, new metallurgical tools, and new methods of fabrication. Greatest advance is made, of course, in practical physical and process metallurgy. Theoretical or fundamental research necessarily must take a secondary position, and is so regarded in this review. It is not that developments in theoretical physical metallurgy are lacking entirely, but, following the same trend noted in other countries as they entered war activities, attention in the U.S.A. has been shifted strongly to those developments having an immediate practical application.

Jan 1, 1943

By A Guinier

RECIPITATION in alloys is undoubtedly one of the most essential phase transformations in metallurgy and, besides, it is a phenomenon of great interest to physicists. It seems then that it can be chosen as a topic for an Annual IMD Lecture. Of course, the subject is a very wide one and I shall discuss here only a very restricted part of it. I should like to show why it is now considered that there is, at the beginning of the process, a stage distinct from the real precipitation, which is the pre-precipitation. We shall be chiefly interested in the atomic structure of the metal in this preprecipi-tation stage. Numerous reviews on this subject have been published recently.&apos;, &apos; The latest was given by H. K. Hardyh t the last meeting of the Institute of Metals in London. One of the most complete articles has been written by the late Dr. Geisler." I should like, at the beginning of this lecture, to pay a tribute to the memory of our friend Arthur Geisler. Some of the ideas which will be developed here are different from those advocated by him. But everybody knows the considerable progress in experiment and in theory which we owe to him and, personally, I deeply feel how fruitful have been the long discussions which we have had during many years. Experimental Basis of the Precipitation Problems Let us recall the essential facts pertaining to the problem of the precipitation. The starting point and the final one are well known. The initial stage is the supersaturated solid solution before quenching. The dissolved atoms replace some of the atoms of the solvent at the points of a definite lattice. It is generally considered that the distribution of the atoms is completely random, and that the lattice distortions are relatively weak. These assumptions are only an approximation. It has now beenproven", that, in some cases, the dissolved atoms have a tendency to segregate to form very small nuclei. These fluctuations of composition are greater than the normal statistical fluctuations in a purely random alloy. We shall see the role played by these nuclei later. The final state is obtained by a very long annealing at such a temperature that an equilibrium is reached in a reasonable time. The alloy is then composed of a matrix which is a saturated solid solution, much poorer than the initial one. Imbedded

Jan 1, 1957

Large deposits of manganiferous iron ores, representing several million tons of metallic manganese, occur in the United States. The Minnesota deposits of such ore are of outstanding importance because of their size, state of development, ease of mining and proximity to the Great Lakes, which permits water transportation to steel centers. In view of the fact that our steel industry requires large quantities of manganese, for which no satisfactory substitute has been found, and because our reserves of ferro-grade ore are comparatively small, the development of methods that will make our large deposits of manganiferous iron ores available as a source of ferromanganese is an important problem. Realizing the importance of this problem, some years ago the North Central Station of the U. S. Bureau of Mines and the Minnesota School of Mines Experiment Station undertook jointly the development of methods for recovering the .manganese content of manganiferous iron ores in a form suitable for the production of ferromanganese, the 80 per cent. alloy indispensable in producing steel. Two types of manganiferous iron ores have been described in previous reports.&apos; The brown ores are higher in iron and lower in manganese than the black ores; the black ores are more siliceous but contain less phosphorus. The utilization of the iron content of the brown ores in the production of steel appears to furnish the best basis for their treatment. The method of attack has been to work out modifications in iron and steel practice so as to recover manganese in the form of slag comparable to ferro-grade ores. The greater part of the experimental work has been conducted with a 6-ton blast furnace and a 1/2-ton basic open hearth. This paper is devoted mainly to open-hearth tests in which high-phosphorus spiegel

Jan 1, 1930

By Paul. D. Merica

I LIKE to look upon the award this year also as a recognition of the importance of metallic materials of construction to the engineer and of the active progress which I believe is continually being made in almost all branches of that field today. It has been said that metals are the material backbone of industry and technology. Well in that case, I suppose we metallurgists are industry&apos;s bonesetters. And it is possibly not inappropriate that we should occasionally give some atten¬tion to those bony structures of our industrial activities upon which engineers in other fields hang their manifold and striking creations. What is going on in the field of metals development? Well, in the first

Jan 1, 1938

By Arthur Mackwell

The role of the precious metals is changing rapidly. They are becoming primarily materials of modern industry, and their decorative and monetary functions are diminishing in relative importance. Certainly gold is still the premier metal for jewelry, as silver is for silverware. But these uses are not growing nearly so fast as are the uses of these metals in a variety of industries. This is even more true of the platinum metals. Moreover, this is true despite the fact that the precious metals are highly expensive and liable to substitution by the base metals in cases where this is feasible. For the fact is that the physical and chemical properties of the precious metals make them relatively invulnerable to substitution; where they can be replaced by the base metals, they have been, and the opportunity for further substitution is, therefore, limited. SILVER In November 1969 the United States Treasury stopped minting the only remaining coin with any silver content. That was the silver-clad Kennedy half dollar, which had a silver content of approximately 40%. The step was taken out of necessity, because of the rising shortfall between world mine production and consumption. It was important to divert the 35 to 40 million oz of silver per year used for the minting of this coin into the open market, where it would be available for industrial consumption. This decision was important, not only for its practical effect but also for what it symbolized. Only four years earlier, in 1965, the Treasury had used 320 million oz of silver" for the full range of coinage. Now not an ounce of silver goes into the United States coinage. The reason is simple and yet complicated. For many years the U.S. Treasury had purchased silver at prices which provided a subsidy to domestic producers. As a result, silver producers were eager to sell to the Treasury, and that agency built up a huge supply of the metal -almost 2 billion oz by- 1961. But, as the free-market price neared $1.29, the basic melt value of the coinage, the Treasury became a seller of silver, not a buyer, and its stock was depleted rapidly. The Treasury lost more :than a billion ounces of silver in the years 1962 through 1965, and it continued to lose silver, both through coinage and through sales to consumers, through 1969. The Government continued to sell silver to consumers at the rate of 1.5 million oz a week, even after terminating the 40% silver Kennedy half dollar. But it was apparent that the Government stocks could last no more

Jan 1, 1976

By Joseph Jensen

MANY fields have been zoned by nature with shales and intermediate waters between oil zones. Limitations thus imposed have been the basis on which the field was developed. In contrast thereto, in the Ventura Avenue Field, nature proved more generous. Always expecting to find such similar limitations, operators drilled deeper and deeper into the oil zone without finding any distinctive shale bodies other that the Gosnell shale and only one intermediate water, which became the point below which the final water shut-off of each well was made. Thus, on top of the structure, about 3300 ft. of oil-bearing zone has been penetrated below this intermediate w9ter-a distance of 4000 ft. below the Gosnell shale. At first it seemed that the greater the penetration in the zone, the better the well. The error of this assumption became evident

Jan 1, 1930