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By M. G. Cheney

Careful estimates indicate that during 1942 new discoveries and extensions in West Central Texas added oil reserves slightly in excess of the eight million barrels produced. Drilling activity fell 40 per cent below 1941 and 82 per cent below the normal drilling activity of the late 1920's. Total production for the district continued its downward trend, now being less than % of the 42.7 million barrels peak in 1921. Rapid revival of activity is not probable under existing conditions, as costs of discovery, development and operations on the average probably now exceed current market price for the oil, the latter having remained constant since the spring of I941. Costs have advanced materially since the third quarter of 1941, when reports to the Tariff Commission indicated a margin of profit of 13.3 per barrel. Physical as well as economic conditions are holding back the amount of drilling in this district. The lenticular sands are not suited to 40-acre spacing regulations. There is no surplus of experienced oil-field labor. To reduce costs, much second-hand material is used for all except the deeper wells.. Price controls have retarded movement of used equipment by prescribing maximum prices that arc too low for the better grade materizl, thus making , owners reluctant to sell. On the other hand, buyers are unwilling to pay ceiling prices asked by sellers for poor material. Seventeen new oil fields and five new gas fields were found during 1942. Extensions and deeper 'drilling brought favorable results in eight older fields. The most significant new developments appear to have been in Coleman, Jones, Shackelford and Taylor Counties. A 5800-ft. completion in Wise County brought this county into the producing column for the first time. None of these new discoveries can he rated above one million barrel reserve on the basis of present development. Probably the most important development was discovery of a deeper pay (Gunsight lime) in the Wimberly field of Jones County, which shows promise of producing over an area of about 1000 acres. Jones and Shackelford Counties still lead the district in total annual production. Discovery of the Reddin pool, north central Taylor County, is credited to geochemical methods, making one success out of five or more wildcats based on such methods. Geophysical surveying increased decidedly during 1942 and returns from these studies are expected during coming years. Most of the wildcatting in the district is still based on surface and subsurface geological structural mapping, study of log data as to distribution of prospective producing reservoirs, and drilling in proximity to previous showings of oil and gas. Geological debate continues as to the proper correlation of the 100 to 300 ft. of gray lime that has produced more than 100 million barrels in the Parks, Brecken-ridge, Curry, Eliasville, Ibex, Pioneer and other important fields of this district. Fossils indicate that this limestone is younger than the Atoka beds of Oklahoma. On a structural basis most geologists include this formation with the Bend but a number of paleontologists believe it is more properly classified with the Strawn.

Jan 1, 1943

By J. R. Low, M. Gensamer

During the course of an investigation into the drawability of automobile-body sheet steel, it became apparent that certain advantages would be possessed by a deep-drawing steel with a very low yield strength, but almost normal tensile strength, provided a reduction in yield strength could be accomplished without sacrifice of ductility and fine grain size. It would also be desirable to have this steel free from strainaging; that is, free from the tendency for the yield point to return after it had been eliminated by straining. It was known that wet hydrogen treatment acted to eliminate aging, but as carried out by other investigators, at relatively high temperatures, this treatment resulted in grain coarsening. It has been established by some of the experiments reported in this paper that all of these objectives can be accomplished by treatment in wet hydrogen at a low temperature, in the neighborhood of 720°C. The time of treatment is relatively short (about 3 hr. to completion with 20-gauge sheet) if the water content of the hydrogen atmosphere is made fairly high, say almost 30 per cent by volume. At this temperature, the grain size remains fine in the time required. After this treatment sheet reduced the usual amount by cold-rolling has a grain size of about A.S.T.M. No. 7. The yield point is completely eliminated, and the yield strength is reduced to a very low value, in the neighborhood of 15,000 lb. per sq. in. The stress-strain curve departs gradually from the straight-line elastic part after the fashion of nonferrous deep-drawing alloys. This elimination of the yield point is accompanied by a very low indentation hardness; for example, 32 Rockwell B or even lower. There is no aging as measured by increase in the yield strength upon aging at room temperature or for 3 hr. at 200°C., after stretching about 10 per cent in tension. Tensile strength is only slightly less than the box-annealed sheet, seldom dropping much below 40,000 lb. per sq. in. Elongation is practically unchanged, or increased slightly. The term yield point, as here used, refers to the phenomenon of heterogeneous deformation occurring at a substantially constant load, observed principally in annealed low-carbon steels. If such a steel is loaded in tension, the load increases steadily with elastic strain, suddenly falls, fluctuates slightly about some constant value for a time and then begins to rise again as deformation proceeds. The maximum initial load before the sudden drop is generally called the "upper yield point"; the value of the load where deformation proceeds at a

Jan 1, 1943

By J. R. Low, M. Gensamer

During the course of an investigation into the drawability of automobile-body sheet steel, it became apparent that certain advantages would be possessed by a deep-drawing steel with a very low yield strength, but almost normal tensile strength, provided a reduction in yield strength could be accomplished without sacrifice of ductility and fine grain size. It would also be desirable to have this steel free from strain-aging; that is, free from the tendency for the yield point to return after it had been eliminated by straining. It was known that, wet hydrogen treatment acted to eliminate aging, but as carried out by other investigators, at relatively high temperatures, this treatment resulted in grain coarsening. It has been established by some of the experiments reported in this paper that all of these objectives can be accomplished by treatment in wet hydrogen at a low temperature, in the neighborhood of 72o°C. The time of treatment is relatively short (about 3 hr, to completion with 20-gauge sheet) if the water content of the hydrogen atmosphere is made fairly high, say aimost 30 per cent by volume. At this temperature. the grain size remains fine in the time required. After this treatment sheet reduced the usual amount by cold-rolling has a grain size of about A.S.T.M. No. 7. The yield point is completely eliminated, and the yield strength is reduced to a very low value, in the neighborhood of 15,000 lb. per sq. in. The stress-strain curve departs gradually from the straight-line elastic part after the fashion of nonferrous deep-drawing alloys. This elimination of the yield point is accompanied by a verv low indentation hardness; for example, 32 Rockwell B or even lower. There is no aging as measured by increase in the yield strength upon aging at room temperature or for 3 hr. at 200°C., after stretching about 10 per cent in tension. Tensile strength is only slightly less than the box-annealed sheet, seldom dropping much below 40,-ooo lb. per sq. in. Elongation is practically unchanged, or increased slightly. The term yield point, as here used, refers to the phenomenon of heterogeneous deformation occurring at a substantiallv constant load, observed principally in annealed low-carbon steels. If such a steel is loaded in tension, the load increases steadily with elastic strain, suddenly falls, fluctuates slightly about some constant value for a time and then begins to rise again as deformation proceeds. The maximum initial load before the sudden drop is generally called the "upper yield point"; the value of the load where deformation proceeds at a

Jan 1, 1944

By J. R. Low, M. Gensamer

During the course of an investigation into the drawability of automobile-body sheet steel, it became apparent that certain advantages would be possessed by a deep-drawing steel with a very low yield strength, but almost normal tensile strength, provided a reduction in yield strength could be accomplished without sacrifice of ductility and fine grain size. It would also be desirable to have this steel free from strain-aging; that is, free from the tendency for the yield point to return after it had been eliminated by straining. It was known that, wet hydrogen treatment acted to eliminate aging, but as carried out by other investigators, at relatively high temperatures, this treatment resulted in grain coarsening. It has been established by some of the experiments reported in this paper that all of these objectives can be accomplished by treatment in wet hydrogen at a low temperature, in the neighborhood of 72o°C. The time of treatment is relatively short (about 3 hr, to completion with 20-gauge sheet) if the water content of the hydrogen atmosphere is made fairly high, say aimost 30 per cent by volume. At this temperature. the grain size remains fine in the time required. After this treatment sheet reduced the usual amount by cold-rolling has a grain size of about A.S.T.M. No. 7. The yield point is completely eliminated, and the yield strength is reduced to a very low value, in the neighborhood of 15,000 lb. per sq. in. The stress-strain curve departs gradually from the straight-line elastic part after the fashion of nonferrous deep-drawing alloys. This elimination of the yield point is accompanied by a verv low indentation hardness; for example, 32 Rockwell B or even lower. There is no aging as measured by increase in the yield strength upon aging at room temperature or for 3 hr. at 200°C., after stretching about 10 per cent in tension. Tensile strength is only slightly less than the box-annealed sheet, seldom dropping much below 40,-ooo lb. per sq. in. Elongation is practically unchanged, or increased slightly. The term yield point, as here used, refers to the phenomenon of heterogeneous deformation occurring at a substantiallv constant load, observed principally in annealed low-carbon steels. If such a steel is loaded in tension, the load increases steadily with elastic strain, suddenly falls, fluctuates slightly about some constant value for a time and then begins to rise again as deformation proceeds. The maximum initial load before the sudden drop is generally called the "upper yield point"; the value of the load where deformation proceeds at a

Jan 1, 1944

By Harrison Schmidt

Since the U. S. Geological Survey published the data on the Central Mining District collected by Lindgren and Gratonl and by Paige2 much new information has been obtained by development and mapping, but none of it had been published until recently when Kniffin3 published on Fierro, Lasky4 on the Ground Hog mine, Thorne5 on Santa Rita and Landon6 filed a thesis on the Fierro-Hanover-Santa Rita area at the University of Chicago. During the years 1927-1930 much of the writer's time was spent in mapping the geology and ore deposits of this district, particularly in the area of the zinc deposits at Hanover. Some of the data collected are presented here. Previous publications have been freely drawn upon and additional data used that were generously supplied by L. M. Kniffin, Wilfred Wright and Gerald Ballmer. Thanks are due Augustus Locke, Samuel G. Lasky, Kniffin, Wright and Ballmer for suggestions and critical readings of the manuscript, and to the Empire Zinc Co. (a subsidiary of the New Jersey Zinc Co.) for the privilege of publishing material compiled largely at its expense. The relation of the Central or the Santa Rita-Hanover-Fierro district to the Silver City district is shown on Paige's geologic map in the Silver City folio.7 Granodiorite porphyry and quartz-monzonite porphyry

Jan 1, 1935

By Harrison Schmidt

Since the U. S. Geological Survey published the data on the Central Mining District collected by Lindgren and Gratonl and by Paige2 much new information has been obtained by development and mapping, but none of it had been published until recently when Kniffin3 published on Fierro, Lasky4 on the Ground Hog mine, Thorne5 on Santa Rita and Landon6 filed a thesis on the Fierro-Hanover-Santa Rita area at the University of Chicago. During the years 1927-1930 much of the writer's time was spent in mapping the geology and ore deposits of this district, particularly in the area of the zinc deposits at Hanover. Some of the data collected are presented here. Previous publications have been freely drawn upon and additional data used that were generously supplied by L. M. Kniffin, Wilfred Wright and Gerald Ballmer. Thanks are due Augustus Locke, Samuel G. Lasky, Kniffin, Wright and Ballmer for suggestions and critical readings of the manuscript, and to the Empire Zinc Co. (a subsidiary of the New Jersey Zinc Co.) for the privilege of publishing material compiled largely at its expense. The relation of the Central or the Santa Rita-Hanover-Fierro district to the Silver City district is shown on Paige's geologic map in the Silver City folio.7 Granodiorite porphyry and quartz-monzonite porphyry

Jan 1, 1935

Since the U. S. Geological Survey published the data on the Central Mining District collected by Lindgren and Gratonl and by Paige2 much new information has been obtained by development and mapping, but none of it had been published until recently when Kniffin3 published on Fierro, Lasky4 on the Ground Hog mine, Thorne5 on Santa Rita and Landon6 filed a thesis on the Fierro-Hanover-Santa Rita area at the University of Chicago. During the years 1927-1930 much of the writer's time was spent in mapping the geology and ore deposits of this district, particularly in the area of the zinc deposits at Hanover. Some of the data collected are presented here. Previous publications have been freely drawn upon and additional data used that were generously supplied by L. M. Kniffin, Wilfred Wright and Gerald Ballmer. Thanks are due Augustus Locke, Samuel G. Lasky, Kniffin, Wright and Ballmer for suggestions and critical readings of the manuscript, and to the Empire Zinc Co. (a subsidiary of the New Jersey Zinc Co.) for the privilege of publishing material compiled largely at its expense. The relation of the Central or the Santa Rita-Hanover-Fierro district to the Silver City district is shown on Paige's geologic map in the Silver City folio.7 Granodiorite porphyry and quartz-monzonite porphyry

Jan 1, 1935

By Harrison Schmidt

Since the U. S. Geological Survey published the data on the Central Mining District collected by Lindgren and Gratonl and by Paige2 much new information has been obtained by development and mapping, but none of it had been published until recently when Kniffin3 published on Fierro, Lasky4 on the Ground Hog mine, Thorne5 on Santa Rita and Landon6 filed a thesis on the Fierro-Hanover-Santa Rita area at the University of Chicago. During the years 1927-1930 much of the writer's time was spent in mapping the geology and ore deposits of this district, particularly in the area of the zinc deposits at Hanover. Some of the data collected are presented here. Previous publications have been freely drawn upon and additional data used that were generously supplied by L. M. Kniffin, Wilfred Wright and Gerald Ballmer. Thanks are due Augustus Locke, Samuel G. Lasky, Kniffin, Wright and Ballmer for suggestions and critical readings of the manuscript, and to the Empire Zinc Co. (a subsidiary of the New Jersey Zinc Co.) for the privilege of publishing material compiled largely at its expense. The relation of the Central or the Santa Rita-Hanover-Fierro district to the Silver City district is shown on Paige's geologic map in the Silver City folio.7 Granodiorite porphyry and quartz-monzonite porphyry

Jan 1, 1935

By Harrison Schmitt

SINCE the U. S. Geological Survey published the data on the Central Mining District collected by Lindgren and Graton1 and by Paige2 much new information has been obtained by development and mapping, but none of it had been published until recently when Kniffin3 published on Fierro, Lasky4 on the Ground Hog mine, Thorne5 on Santa Rita and Landon6 filed a thesis on the Fierro-Hanover-Santa Rita area at the Uni-versity of Chicago. During the years 1927-1930 much of the writer's time was spent in mapping the geology and ore deposits of this district, particularly in the area of the zinc deposits at Hanover. Some of the data collected are presented here. Previous publications have been freely drawn upon and additional data used that were generously supplied by L. M. Kniffin, Wilfred Wright and Gerald Ballmer. Thanks are due Augustus Locke, Samuel G. Lasky, Kniffin, Wright and Ballmer for suggestions and critical readings of the manuscript, and to the Empire Zinc Co. (a subsidiary of the New Jersey Zinc Co.) for the privilege of publishing material compiled largely at its expense. The relation of the Central. or the Santa Rita-Hanover-Fierro district to the Silver City district is shown on Paige's geologic map in the Silver City folio.7 Granodiorite porphyry and quartz-monzonite porphyry

Jan 1, 1933

By P. T. Gallagher, W. A. Oates

THE partial excess entropy of interstitial solutes in metals, SXS , has usually been interpreted as being principally vibrational ever since the initial statistical treatment of hydrogen in metals by Fowler and Smith-ells. The vibrational entropy is considered being due to the optical modes of the light interstitial atom. Little attention has been given to the magnitudes of the values of SXS'. Leiser and Witte2 and Ebisuzaki and O'Keeffe3 have noted that for hydrogen in metals Si is approximately constant for different metals. On the other hand if it is assumed that the interstitial solute is an isotopic defect then, as shown by McLellan, SXS should vary from metal to metal as follows: where S is the standard entropy of the solvent and Mi, M, are the masses of the interstitial and solvent atoms. respectively. Fair agreement with this equation was found for oxygen in silver and nitrogen in iron4 and for carbon in iron.= Ln a subsequent analysis of metal- hdrogen systems McLellan' found a variation of $' from metal to metal but not in a manner expected from the isotopic impurity equation. However, a possible correlation between the energy of solution, Ei, and sf was noted. Similar correlations have been noted for certain dilute substitutional solid Solutions 7, 8 and recently Kubaschewski 9 has demonstrated a correlation between integral heats and ex-

Jan 1, 1970

By AIME AIME

COMMITTEE No. 2 of the Iron and Steel Institute b f Great. Britain has presented its first report, of 27 printed pages, on blast-furnace plant and practice. This report outlines the various features of modern blast-furnace practice with brief comments thereon, and with references to some of the more recent methods devised for applying the principles and attaining the purposes aimed at' under these headings.. In general, the trend in the United States is in the direction of larger and larger furnaces with ever increasing capacity from which, with improved details in methods and equipment, and attention to details of management, considerable progress in. economy of production has been attained, in fuel consumption and in other items of production cost.

Jan 1, 1929

[†AARONSON, ALFRED E., Vice-Pres., Mid-Co. Petroleum Co., Mid-Co. Bldg., Tulsa Okla. '18 ABADIE, EMILE R., Min. Engr Box 927, Porterville, Cal. '76 ¦ABADILLA, QUIRICO A. Student, Colorado School Of Mines, Golden, Colo. '20 ABBOTT, CLARENCE E., Gen'l Supt. Iron Mines Div., Tenn. Coal, Iron & R. I. Co., 1405 Minnesota Ave., Bessemer, Ala. '04] [ ]

Jan 1, 1925

The annual spring excursion of the College of Mines, University of Washington, is being made to the Coeur d?Alene region of northern Idaho. A party of 15 students and, instructors is visiting the Bunker Hill and Sullivan mine, mill and smelter at Kellogg, and several mines and mills in the neighborhood of Wallace and Mullan.

Jan 5, 1917

By R. Clare Coffin

The production of oil in the Rocky Mountain district, including southeastern New Mexico, increased from 33,048,630 bbl. in 1930 to 34,325,163 bbl. in 1931. This increase was due to production in New Mexico, which exceeded the 1930 figure by approximately 5,000,000 barrels. Total production by fields is given in Table 1. Exploration during 1931 resulted in the discovery of a new oil-producing horizon in the Big Muddy field in Natrona County, Wyoming, and ' the discovery of a new gas pool in the Powder Wash structure, Moffat County, northwestern Colorado. Gas was discovered also in the Frontier sands of the Bunker Hill dome, Carbon County, Wyoming, but no test has yet been made by which to determine the significance of this discovery. All other exploration which resulted in increasing the known reserves of oil and gas in the district was confined to drilling in partly outlined fields where known limits of production were extended. During the year two major gas pipe lines were completed in western Montana, and one in southwestern New Mexico was extended into Arizona. One new project involving the marketing of natural gas from Wyoming fields included the conversion of an existing oil line to a gas line to serve towns in southeastern Wyoming and western Nebraska. Colorado The decline of 132,501 bbl. in the production of oil in the Colorado fields during 1931 from the figure of 1930 is due to the natural decline of existing wells, partly offset by the increased production in the Greasewood area. New exploration was limited largely to northeastern Colorado, where attempts were made to find oil in areas adjacent to the Grease-wood field. Powder Wash, Moffat County.—The Ohio Oil Co. is to be credited with the discovery of a gas field in the Power Wash structure in Moffat County, Colorado. The initial well drilled in sec. 5-11-97 encountered a sand at a depth of 2152 ft. which produced 34,188,000 cu. ft. of gas on an open-flow test. The rock pressure was reported as 630 Ib.

Jan 1, 1932

By Harold Roast

THE object of this investigation was to compare the arsenical antimony-lead alloy with some of the regular bearing-metal alloys. With this end in view, the following tests were made: 1. Chemical analyses to show the composition. 2. Thermal analyses. 3. Macroscopic examination of fractures. 4. Microscopic examination. 5. Tensile tests. 6. Crushing tests. 7. Scleroscope tests. 8. Brinell tests, at temperatures from 80° to 400° F. Tests 3 to 8 were conducted on both sand-cast and chill-cast specimens. For the purposes of this paper the alloys have been numbered from 1 to 6; their composition is as follows: LEAD, ANTIMONY, TIN, COPPER, ARSENIC, NUMBER PER CENT. PER CENT. PER CENT. PER CENT. PER CENT. 1 82.64 12.95 4.40 0.01 none 2 27.54 9.94 59.87 2.65 none 3 77.65 20.75 none 0.13 1.47 4 82.95 16.85 none 0.20 none 5 83.78 15.35 none 0.05 0.82 6 0.15 7.87 84.13 7.85 none The analysis, in the case of the antimony, was made by solution in sulfuric acid and titrated with permanganate. For tin, the ferric-chloride method was used; for copper, the alkaline separations, and the thiocyanate methods; for arsenic, volatilization of arsenic and titration with iodine. The lead, with the exception of alloy 6, was taken by difference.

Jan 2, 1922

By Waldemar Lindgren

Discussion of the paper of WALDEMAR LINDGREN and CLYDE P. Ross, presented at the New York meeting, February, 1916, and printed in Bulletin No. 106, October, 1915, pp. 2171 to 2190. WALDEMAR LINDGREN, Boston, Mass.-I happened to go down to Cuba rather unexpectedly in the winter of 1914, and spent a few very interesting days at Daiquiri and Mayari. To C. F. Rand and his associates I am greatly indebted for permission to visit the mines and for many courtesies received. A few months after that, I met Professor Kemp who informed me that he had just returned from a geological study of Daiquiri. We talked over what to do in a case like that. We both liked to publish our opinions, and so finally agreed to write two papers entirely separately, I not knowing any of Professor Kemp's conclusions,1 and vice versa. We were rather interested in seeing what would happen. Of course, as might be expected, we disagreed on some points; not, of course, that we ordinarily disagree, but simply because when two men work in the same field and with different ideas, probably they are apt to vary slightly in their conclusions. Some years ago A. C. Spencer went down there for the military interim government and published the results of his study. His view of the origin of the deposit differed from that of Professor Kemp and from mine. So here are three different results obtained by three different geologists. Such differences in opinion on obscure subjects sometimes tend to bring geology into disrepute. It is perhaps not surprising that different opinions have been expressed, for this occurrence of iron ore is one of the most difficult to explain that I have ever seen. MAX ROESLER, Great Neck, L. I.-I had the opportunity this summer of spending about two months down at the Juragua deposits, and studied them with the idea of writing a paper on them, which I hope will come out later. The interpretation of the occurrence at Ocania Mine is the thing which particularly struck me, in the last paper. At the Ocania Mine we may have these large blocks of limestone which have been utterly and entirely altered, to a remarkable extent.

Jan 5, 1916

By Herty, C. H.

No attempt will be made here to review the previous work done by investigators on the general subject of inclusions, because it was discussed sufficiently in an early cooperative bulletin of this series (No. 36, 1928), and reference was then made to general bibliographies. The work described in this present bulletin deals directly with the study of the mechanism of deoxidation of steel with aluminum and the formation of inclusions containing alumina. Unquestion- ably, such inclusions are encountered in most steel-making practices and little has been done to determine their characteristics. Aluminum is used to ensure rapid deoxidation during the solidification stages of the steel. For this reason the possibilities of inclusion elimination are slight and alumina-containing particles will undoubtedly be present in the ingot. Besides this common practice, aluminum is often used in the ladle with other deoxidizing agents such as silicon and manganese. Ladle additions of aluminum are made to rimming steels to obtain the correct partial deoxidation desired in this type of steel. In killed steels the aluminum is added to ensure soundness, as far as blowholes are concerned, in the ingot. In either rimmed or killed steels, alumina or alumina-containing inclusions are found therein, the amount and type depending on the oxidation of the metal, the amount of aluminum added, and the addition of other deoxidizers.

Jan 1, 1957

By AIME AIME

NO FEATURE of the annual meeting is considered more important at Institute headquarters than the assembly of delegates from the various local sections and divisions. There the president of the Institute and other officials may learn at first hand what the members are thinking and doing in every part of the country, and the delegates, in turn, may find that head- quarters is not a group of more or less cold-blooded New Yorkers whose primary function is to send out annual bills for $15. This year, the section and division delegates required three sessions to thresh out the matters of common interest: Monday morning and afternoon and Thursday afternoon. They were also guests of the Institute at the Directors' dinner on Tuesday night, and at the Directors' meeting afterward.

Jan 1, 1932

By Donald J. Knight

HEAT Treatment at 1500' F of a mild steel containing 0.1 pct C, in an atmosphere which is oxidizing to both carbon and iron, results in the progressive oxidation of the metal surface with little or no change in the carbon content of the underlying metal. Further heat treatment of the scaled metal in either a neutral atmosphere or in a vacuum may or may not result in the decarburization of the metal depending upon the physical nature of the scale. It is apparent that if a continuous layer of oxide is present on the steel surface, the reaction OScale + Cmetal Cogas cannot progress since the SO formed gas would be unable to leave the oxide/metal interface. Thus, in order for the reaction to progress, the oxide must be cracked or porous. Vacuum heat treatment at 1500" F of samples with a thick continuous oxide scale showed no decarburization of the steel. However, when cracks were introduced mechanically into the scale prior to the vacuum heat treatment notable decarburization of the metal resulted and a structure as shown by Fig. 1 obtained, i.e., reduction of the crack walls to ferrite. With reference to the diagram of Fig. 2, it would appear that a mechanism of the following type takes place. Carbon atoms arriving at an oxide/metal/void interface, such as 'A', Fig. 2(a), can combine with oxygen atoms from the scale and leave the reaction site as Cogas thereby reducing the oxide to metal. On a greatly magnified scale, Fig. 2(b),this will appear as a ferrite projection along the crack wall. Carbon atoms entering this projection can react with oxygen atoms at point 'C', which is a new interface, and so on leading to a progressive growth of the ferrite along the crack wall and to the surface, Figs. 2 (c) and 1. It would appear that the only means by which thickening of the ferrite film can take place is by a diffusion of oxygen through the ferrite film to react with carbon at the newly formed ferrite/ void interface. Since the diffusion rate of carbon is reportedly much greater than that of oxygen, and since there is a low probability factor of oxygen and carbon atoms arriving simultaneously at the same site on the ferritehoid interface, there will be a tendency for more rapid lengthening than thickening of the ferrite layer, as is observed.

Jan 1, 1962

By MARCELS CHLUMBER

BY the term making an "electrical log" the authors designate an operation conceived for the purpose of determining electrically the characters of formations traversed in drilling, the determination being carried out by means of measuring the electrical resistivities of the rocks along the uncased portions of drill-holes. As in the case of an ordinary core record, this process connotes a geological studs of the strata, and for that reason it is given a similar designation. The paper is divided into three parts, of which the first deals with the resistivities of rocks in general, since it is through this electrical parameter that they are to be characterized. The second deals with the technique, and the third with the description of practical applications of the electrical logs.

Jan 1, 1929