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By Louis A. Carapella, William E. Shaw

MAGNESIUM and its alloys have long been characterized as possessing limited capacity for mechanical forming at atmospheric temperatures prior to rupturing despite their outstanding performances in this respect at elevated temperatures. Responsible for this behavior are the fundamental facts that these hexagonal-type metals have comparatively few slip elements at low temperatures for any extensive deformation and that, at high temperatures, additional slip elements become operative, thus enhancing greater plasticity under strain. The transitional point has been set at 225°C by Schmid1 for single crystals, and at 250°°C by Morell and Hanawalt2 for extruded magnesium metal. In a recent X-ray investigation on polycrystalline magnesium-alloy sheets, Barrett and Haller3 have revealed that, below the transitional temperature, the initial plastic deformation proceeds mostly by a twinning action; that, above such a temperature, the action is mostly by slip. The deep-drawing performance of the magnesium + 1.5 pct alloy sheett over a wide range of temperatures has been investigated by Weber and Vanden Berg,' and their results are presented in Fig r. It should be noted from this work that a maximum drawability of about 25 pct at room temperature has been obtained on this alloy under the conventional deep-drawing operations. For the same alloy, it is now possible to augment the cold drawability to about 40 pct by a process to be disclosed. Hitherto, this value has been obtained only by deep-drawing the alloy at around 230°C. That greater plastic flow is attainable at atmospheric temperatures on magnesium under certain deformational techniques was discovered by the authors6 in their analyses of plastic-deformational behaviors of pure magnesium. This fact is best illustrated in Fig 2 from the Hargreaves analysis6 performed by the authors under two different modes of loading. For direct test, a separate unstrained specimen was used for each load duration, whereas for the integrated test the same specimen was employed for all the five intermittent loadings so that the load duration was made additive throughout the investigation. The higher plastic flow-rate at room temperature, as designated by the Hargreaves constant S, was obtained by the integrated or intermittent loading procedure. The authors5 in further tests showed that, under such a procedure greater plastic flow was also realized with a progressive increase in deformational loads. These findings have been applied

Jan 1, 1947

By Hans Lundberg, Basil T. Wilson, H. Steuart Scott

FOR the benefit of those readers who may not be in close touch with present practices in the geophysical prospecting for ore, brief reference will fiat be made to the advantages and shortcomings of the methods to be discussed. Magnetic and electric methods are generally accepted as the most useful for ore prospecting. By magnetic methods, magnetic intensities that are not normal may be recorded and outlined. From these can he located concentrations of such highly magnetic minerals as magnetite or pyrrhotite, which sometimes occur in such large masses that they are of economic value in themselves. More often. however, these magnetic min¬erals are associated with others, such as copper, zinc, lead, gold, and silver, which, if existing in sufficient concentration and quantity, may constitute valuable ore bodies. It is therefore only when pyrrhotite and magnetite are present in these bodies that the magnetic method can be used to indicate their presence.

Jan 1, 1945

By Howard Evans

Moderate but substantive gains were recorded in 1972 in the minerals processing industry. In the area of mill design, a number of large plants under construction during the past two to three years were tuned up and went into production. The application of operating controls has also made some significant strides. Progress here has been made in the areas of on-stream particle size analysis, on-stream x-ray analysis, slurry transportation, tripper control, flotation reagent control and digital control of grinding circuits. The major contributions to improved equipment are coming from smaller specialized equipment makers.

Jan 2, 1973

By Arthur Bell

(San Francisco Meeting, September, 1915) . PRIOR to 1908 the oil production in the State of California, had been almost entirely a heavy fuel, oil, with a high flash point, hut changed within a-short period to a large percentage of refining oil with a low flash, by reason of the coming in of the Santa Maria field, the Midway field, and the increased production of the Fullerton field. This is clearly shown in the following tabulation of California's production: Year Barrels . Below -20° Be, Above 20° Be,, Per Cent_ Per Cent. 1905 48,307,000 90 10 1910 77,698,000 SO 20 1912 90,075,000 6o 31 1914 10:3,600,000 47 53 The bringing in of these high percentage's of light oil with their dangerous low flash and the increasing demand for the refined products necessitated the devising of some cheap and efficient means of quickly separating the lighter elements either in the field or at the main distributing points; also it became necessary to remove the excessive percentage of water which many of the light oils carried in emulsion.

Jan 9, 1915

By R. H. Johnson

All strata not yielding oil or gas in commereial quantities or a corresponding amount of water may be called dry in a wide sense. In petroleum geology, however, we may exclude all sands of too low or fine porosity to yield gaseous or fluid contents to the hole drilled in the sand before any original pressure that its contents may be under is disturbed. Most rocks are of this class and they are not reservoirs in our definition; their "dryness" is wholly a matter of course. What are the contents of the pores or what is the exact porosity of such rocks is of almost no concern to us, for economically they are "dry." What does interest us is the content of a rock having sufficient porosity and the pores of sufficient size to yield oil or gas in commercial quantities, if they were present under original pressure. Dryness of these reservoirs is a matter of supreme practical importance. Three views current as to such dryness seem, to me, to apply in a few cases only. It is the purpose of this paper to give reasons for this position and for believing that, in ordinary sedimentary rocks, there is only rarely a reservoir of competent porosity and undisturbed pressure that is dry in the sense of not yielding water, oil, or gas when first penetrated. 1. Gardnerl writes of some Kentucky sands, "There has never been present any salt water or other water in the sand." Absence of water cannot demonstrate this position. It is necessary to show that the rocks were not laid down in water, but in air, and that they became so enclosed, while still above the water-table of the ground water, that water has not been able to enter since. Most of these sands, and certainly the productive limestones, were deposited in water; and such sands as have been commercially productive show no reason for believing that the overlying shale or limestone was not laid down progressively from one direction and in water that would have flooded it. NO adequate explanation has been offered for this hypothesis, which is so inherently improbable. 2, Reeves2 urges that "sands originally water filled may have been drained of their water and not filled when later covered." It is difficult I James H. Gardner: Kentucky as an Oil State. Science, N. S. (1917) 46, 279-280. Reeves: Origin of the Natural Brines of Oil Fields. Johns Hopkins Univ. Circ., N. S. (1917) N. 3; Absence of Water in Certain Sandstones of the Appalachian Field. Econ. Geol. (1917) la, 354-378.

Jan 1, 1921

By W. W. Simpson, W. L. Staker, R. G. Sandberg

The Bureau of Mines investigated selective extraction of Au and Ag from a low-grade Au ore containing Hg. Gold and silver were extracted from the ore in cyanide slurries, and Hg extraction was suppressed with sodium or calcium sulfide. Maximum Au extraction and minimum Hg extraction were obtained using solutions containing 17 kg NaCN/t of solution (0.34 lb NaCN/st). Increasing the cyanide concentration increased Hg extraction without increasing Au extraction. Mercury extraction from the ore was suppressed with 0.5-2.9 kg CaS/kg Hg (0.5-2.9 lb/lb) in the ore. Gold-to-mercury ratios of 100:1 to 400:1 were obtained in the leach solution, and on the activated carbon in a CIP circuit.

Jan 1, 1985

By J. P. Hammond, C. J. McHargue

THERE have been no publications on the wire texture, on the cold-rolled sheet texture, nor on the recrystallized sheet texture of vanadium. Since it has a body-centered cubic structure, it would be expected to show strongly preferred orientations such as are found in iron' and molybdenum.' The wire textures of body-centered cubic iron,3 tungsten," molybdenum,5 antalum,6 iobium,6 and brass6 have been found to have [110] directions lying parallel to the wire axis. Wires of iron,' containing 1.95 pct V or 1.95 pct Si,7 and steel8 retain their texture upon recrystallization. Molybdenum9 and tungsttln' wires retain their texture after recrystallization at low temperatures. A [loo] recrystallization texture has been reported for mo1ybdenum9 and for a Fe-Ni alloy (53 atomic pct Ni).10 The cold-rolled sheet texture for iron,' mild steel," and molybdenum chiefly one in which the [110] directions lie parallel to the rolling direction and the (100) planes lie parallel to the rolling plane with a deviation from this position chiefly about the rolling direction as an axis. This paper presents the cold-rolled and the re-crystallized wire textures, and the cold-rolled and the recrystallized sheet textures for vanadium. The results show that the textures in vanadium are not significantly different from those reported for other body-centered cubic metals. The vanadium used in this investigation was the so-called "ductile" vanadium which has a nominal composition within the following limits:12 0, 0.05 to 0.12 pct; H, 0.001 to 0.004; N, 0.02 to 0.04; C, 0.03 to 0.07; and V, 99.8 to 99.9. The wires were formed by rolling annealed rods of 0.280 in. diam to 0.028 in., a reduction in diameter of 90 pct. The wires were then electrolytically etched to 0.005 in. diam and used as such for specimens. Annealed sheet was reduced 95 pct in thickness from 0.100 to 0.005 in. with a two-high, 4-in. diam mill using reductions no greater than 10 pct per pass. In order to avoid temperature effects, the sheet was allowed to cool between passes. X-ray specimens were made in the form of posts from the sheet. The sheet was mounted in a fixture and the edges were polished using metallographic technique. Each edge was alternately polished and etched during the last stages in order that all worked material would be removed. These post specimens were approximately square in cross-section. The specimens to be recrystallized were wrapped in tantalum foil, sealed in evacuated quartz tubes, and annealed at 1600°F. The X-ray data were obtained from transmission shots made with a 0.030 in. pinhole camera, and molybdenum radiation with a zirconium filter inserted between the specimen and film. The grain size was sufficiently small in both the cold-worked and recrystallized material to give satisfactory results with the specimens stationary. In order for the wire texture to be determined, transmission X-ray patterns were taken with the

Jan 1, 1953

By C. B. Dudley

bas shown us that the railroads of this country can save several milt liohs a par by adopting uniform rail sections, and as unfortunately for him, he cannot patent his idea, it only remains for the railroads to adopt it, and to thank him for his payer. Dr. C. B. Dudley, Altoona, Pa. : 111 rising to close this interestin~ discussion, I want, in the first place, to thank every one who has contributed to it for his full and open criticism. The work tvhich has been done on steel rails, and which has been diwu&e,l here Juring thee two days, was not done to establish any pet theories, nor to make out that any person was great or any person small, but with a sincere desire to get at what is the truth in regard to the wedring capacity of steel rails. There are enormous commercial coneiderations invoIved in this question, and, as I look at the matter, the more honest criticism and fair discussion there is, the Inore likely it is that the truth will appear. Ad first I would like to say that it seems to me very little has been said here upon the main conclusion of the paper, namely, that the softer rails give the better wear. All sorts of side issues have been discussed; but this poiat, which is really the principal one at issue, has been largely ignored, aid I cannot But feel that it still remains unshaken. Witb regard to ohemists end chemical work, there has been considerable said tending to throw discredib on chemists and their work; and while I believe that there have been in the past, are now, and may be in the futnre, a good many poor chemical analyses made, X also believe that chemists are, as a rule, as honest and competent as gentlemen who belong to other professiomc. There are chemisb who are chemists, and who are not chemists. The determination of -manganese has bee* called in question. Now I think the chemist at almost every steel works in the country will tell you that, in his experience, the manganese diffe1.s in different parts of the same ingot. Mr. T. T. Morrell, chemist of the Camhria Iron Company, whom I believe to be s thoroughly competent and hone6t chemist, tells me that he has often found different amounts of manganese in different parts of the same ingot. Come with me to Altoona, and I will take you into the machine shop where steel is king cut aud shaped, and I will show you that it is often necessary to stop the lathe or planer and take a cold chisel to cut oat a hard spot, or else ntn the risk of breaking the tool. This hard spot is simply a pttrt of the syiegel which was not thoraughiy mixed with the ma

Jan 1, 1881

Member ship L P MATHEWSON, Chairman GEORGE D BARRON LOUIS D HUNTOON JOHN A CHURCH, JR H N SPICER Alternates LEWIS W FRANCIS WILBER JUDSON F T RUBIDGE Increase of Membership JOHN A CHURCH, JR, Chairman Other members to be appointed

Jan 1, 1923

C. P. BOWIE, San Francisco, Cal.-In my work with the U.S. Bureau of Mines, I have been detailed to report on oil storage containers, and in going around the country I have, been much interested in, the possibilities in the use of concrete for such containers. In talking with a good many people, I have discovered that concrete is being used A good deal for a wide variety of oils ranging from 14° to as high as 40° Bé., especially, by some of the western railroads:, If any member has had experience, in storing gasoline in concrete, I should like to learn of it. DORSEY HAGER, Tulsa, Okla.-Mr. M J. Munn, formerly .with the U. S. Geological Survey, acid connected with the Gypsy Oil Co., until a short time ago, has invented a invented a method for the application of concrete to the storage not only of crude oil but of refined products:. The Cosden Oil Co., of Tulsa, is now working on that plan, and, expects to store refined products in concrete tanks. THE CHAIRMAN (I.N. KNAPP, Ardmore Pa.).-I have had considerable experience in building masonry tanks for gas Holders. I do not believe it is possible to build a concrete or masonry tank of any kind. With hydraulic cement, mortar, which will be absolutely water-tight, unless the bottom and inner wall, after completion are waterproofed with some impervious material. The same will be true of oil tanks, the bottom and inner face of which must be made impervious to oil. Masonry tanks are intended to be sunk in the ground. All that the wall of the tank then amounts to is a retaining wall to keep the excavation in shape and to receive an impervious coating. The bottom of, a; tank, when empty, must be protected by a relief valve from any hydraulic: pressure acting from below. At ordinary prices, for sheets, a tank 100 ft. diam by 20 ft. deep can be built of steel much quicker and cheaper than of masonry. Several years, ago I saw very large oil storage tank under construction in California the bottom and sides being concrete. The sides were, sloped at about the single of repose for the material excavated: If you build a steel oil tank, you can get. .men for the work who do nothing else, and you, are likely to get a satisfactory job; but if you wish to build a concrete or masonry tank it is almost: impossible to find men skilled in building absolutely water-tight masonry Work. The general idea is that any laborer can mix up concrete in any old way and make a,

Jan 1, 1918

By Grimes, J. A.

EXTENSIVE discovery 'and rapid exploitation of orebodies within the past half century have attracted many able geologists to the mining industry and furnished them a wealth of data from which to develop theories concerning ore genesis. By tosting and elimillating theories which are not sufficiently sup- ported by fact, or which are based on inaccurate observation of field data, the trend of geological opinion has . moved strongly in certain directions until, at the present time, large numbers of geologists subscribe to a broad concept of .ore genesis that I would summarize as below:

Jan 1, 1928

By Clyde Williams

A MAN who is a first-class metallurgist, engineer, and scientist and an outstanding organizer, administrator, and executive and who, at the same time, has an innate ability to "make friends and influence people" everywhere he goes is an exceptional personality at any time. And if such an individual can retain this combination of virtues during a great war despite the fact that the Government loaded him with enough work and responsibility for three such men. he is a most exceptional personality. And if he can keep his head and maintain an unfailing sense of humor during the trying war years and, while dealing with hundreds of jittery metallurgists and metalworkers, with Army and Navy brass, and with red-tape-entangled war agencies by the dozen, he is a rare personality indeed. Such a man is Clyde Williams, director of Battelle Memorial Institute. who will be President of AIME in 1947. The Institute is fortunate in having him as its mentor during what may be a critical and important year.

Jan 1, 1947

By Charles Williams

BOYLE'S law states that the volume of a gas at B constant temperature varies inversely as its pressure, PV = C, or V = C/P Therefore, the volume of a gas at any pressure is to its corresponding pressure as the volume of the same gas at atmospheric pressure is to atmospheric pressure, V, = V° Also, P1 P0 the volume of the gas at any other pressure is to its corresponding pressure as the volume of the gas at atmospheric pressure is to atmospheric. pressure, V2/P1 V0/P0 V°P VA Solving for V1 and V2, V2 = and V2 =V0P2/P0

Jan 2, 1927

By George A. Miller

OIL, the abundance of it in the hands of the Allies and the lack of it in the hands of the Axis, played a major role in winning World War II. It bids fair to implement the winning of the peace. In fact the signing of the revised agreement on petroleum between the Government of the United Kingdom of Great Britain and Northern Ireland and the Government of the United States of America on Sept. 24, 1945, may be considered as the first step in establishing a new pattern in foreign relations by our Government. The significance of this agreement on petroleum is that it was arrived at on the part of the United States of America through the advice and consent of the most interested parties, the leaders of the petroleum industry and the Government, distinctly a first step toward unifying the power of business and the strength of the Government, which places us on a par with the British Crown which has always had the advice and counsel of its business leaders in formulating its foreign trade policies. And what is the thing so patently discernible in this new first step toward winning the peace? It is that the petroleum agreement, the first draft of which, signed in Washington on Aug. 8, 1944, almost caused an epidemic of apoplexy among the leaders of the oil industry, represents the desire of the people most concerned with the problems of petroleum both at home and abroad. This new agreement, which will come up before the Senate for ratification this month-hearings will commence in January - derives its "power from the consent of the governed," something about which our forefathers were vitally concerned once upon a time.

Jan 1, 1946

By L. D. Godshall

The latest revised edition of Mr. C. A. stetefeldt's book on the Lixiviation of Silver-Ores, which appeared very recently, contains no mention of the volatilization of silver in chloridizing-roasting—an omission which is the more remarkable in view of the fact that in former editions of the work this important subject was noticed. Moreover, Mr. Stetefeldt has discussed it to some extent in his paper on " The Stetefeldt Furnace," * in which he criticised certain statements made by me before the Colorado Scientific Society in May, 1893, in a paper entitled " A Review of the Russell Process;" ? and Mr. Morse, in his paper on " The Lixiviation of Silver-Ores by the Russell Process at Aspen, Colorado," $ has given statistics showing the loss of silver by volatilization (including the dustloss, which Mr. Morse estimates at not more than 1 per cent.) on more than 30,000 tons of ore roasted, to have been 9.16 per cent. The matter must certainly be deemed important enough to warrant me in returning to it, and offering, with the aid of the figures made public since my first paper, a reply to the criticisms of Mr. Stetefeldt. The passages of my paper which he deemed to be " ques-

Jan 1, 1897

By AIME AIME

COUNCIL.* PRESIDENT OF THE COUNCIL. CHARLES KIRCHHOFF NEW YORK, N. Y. (Term expires February, 1912.) VICE-PRESIDENTS OF THE COUNCIL. BENJAMIN B. LAWRENCE NEW YORK, N. Y. JOSEPH W. RICHARDS SOUTH BETHLEHEM, PA. ALBERT SAUVEUR CAMBRIDGE, MASS. (Term expires February, 1912.)

Feb 1, 1912

By Hugh D. Pallister, Richard W. Smith

The Alabama flake-graphite industry has flourished only in times of war when importations of foreign graphite for crucible use have been greatly curtailed or cut off. World War I was a boom period and in 1918 some 30 plants produced 7,795,475 lb. of flake graphite. The industry languished following the war and no graphite was produced from 1929 to 1939. The Federal Bureau of Mines began investigating the Alabama graphite deposits in 1940 and worked out modern recovery methods that were applied to production during part of World War II. A prospecting program disclosed reserves of over 25 million tons of graphitic schists. In 1942 the War Production Board authorized the enlargement of the only plant then producing flake graphite and the construction of two new plants. Production of flake graphite from these three plants in 1943 is estimated at 8,100,000 lb. Increased imports from Madagascar late in 1943 shut down one of the new plants and curtailed production at the other. Alabama flake graphite has not yet been able to compete with Madagascar graphite for use in the manufacture of any but small graphite crucibles. The future of the industry must depend on meeting the higher carbon content demanded for other uses.

Jan 1, 1945

By M. H. Waxman, M. Gondouin, H. J. Hill

Streaming-potential experiments were conducted within the Muddy- and Dakota-sandstone interval of a Denver basin well. Analysis of the data shows that, for this case, streaming potentials opposite sands were higher than those opposite shales when the mud was fresh. Streaming potentials opposite shales, however, were of sufficient magniiIlde to be important in SP interpretation. They were linearly dependent upon pressure differential, and they increased with mud filtrate resistivity. The magnitude of streaming potentials opposite sands was influenced by the characteristics of the original mud cake formed at the time of drilling. Use of mud samples taken at the time of logging may not always be satisfactory for determining streaming-potential corrections. Both the streaming and electrochemical potentials were found to be affected by the previous history of the borehole system. Following a change in mud characteristics, several days were required for SP stabilization. This was, in part, due to the mud cake acting as an imperfect shale membrane. INTRODUCTION Laboratory investigations by Wyllie,1 Salisch,2 Moore," Sen Gupta and Bannerjee,0 and Hill and Anderson' have shown that streaming potentials developed across mud cakes deposited on permeable filter beds are of sufficient magnitude to be critically important in SP interpretation. Streaming potentials across shales have been reported by Schenck,' Gondouin and Scala; and Hill and Anderson." The magnitude of the shale streaming potentials obtained by Schenck and by Gondouin et a1 led these authors to conclude that in many cases the shale streaming potential would approximately equal the mud-cake streaming potential. Hill and Anderson, however, obtained somewhat lower magnitudes of shale streaming potential. The field experiment described in the present paper was a cooperative project carried out by the respective operations and research departments of Schlumberger Well Surveying Corp., Shell Development Co. and Shell Oil Co. The primary objective of the experiment was to determine in the borehole the streaming-potential behavior of both shales and mud cakes under conditions approaching, as nearly as possible, those normally encountered in logging practice. METHODS AND EQUIPMENT WELL A Muddy- and Dakota-sandstone vie11 in the Denver basin was chosen for the experiment. Both sandstones were water-bearing and, since reservoir pressures in these sandstones are abnormally low (gradient of approximately 0.25 psi/ft), it was expected that studies of streaming potential could be conducted from low-pressure differentials (approximately 200 psi) to about 27000 psi by bailing mud from the hole, filling up and then applying wellhead pressure. The selected well encountered the Muddy sand-

By J. L. Lamon, W. Crafts

P. Coheur and L. Habraken—We read this paper with great interest and are glad to congratulate the authors for their valuable work, supplying an important contribution to the mechanism of tempering on the carbides in vanadium steels. We are in a good position to appreciate this work since we have been studying, for more than a year, Cr-Mo steels of a composition similar, but less highly alloyed (namely 0.1 pct C, 3 pct Cr, 1 pct Mo). Our results are quite in concordance with the authors', however, we wish to point out that it is very interesting to use equally the electron microscope in order to observe the variations of microstructure in steels. We have studied simultaneouslv the evolution of the carbides in situ with the electron microscope, and, after extraction, again with the electron microscope, and then with X-rays. The first results which we have obtained have been communicated at the Congress of Delft (July 1949) and at the "Journbes de la Metallurgie" in Paris (October 1949). These may be summarized as follows: After tempering with varying either the tempering temperatures or the tempering times, the carbides show two evolutions. The first one is connected to the carbides existing in the steels, principally in the boundaries of the grains. For some groups of steels these carbides may coalesce and for other groups they may

Jan 1, 1951

By T. S. Lundy, R. E. Pawel

Effects of short-circuiting paths on observed diffusion behavior in real crystalline systems are considered. It is concluded that experimentally measured diffusion coefficients may vary widely from values associated with true lattice diffusion to those appropriate for short-circuiting paths alone depending upon the conditions of the experiment and the sensitivity and completeness of the data. IN 1961 Harrison1 classified experimentally observed diffusion behavior in systems involving both lattice and dislocation-enhanced atomic transport into three categories. His types A and C were limiting cases where the measured diffusion coefficients using the usual serial sectioning techniques were representative of lattice diffusion (with only slight effects of dislocations) and dislocation-network diffusion (with only slight effects from lattice diffusion), respectively. In both cases A and C for a sectioning experiment in which the diffusion couple has the semi-infinite geometry and unidirectional diffusion takes place from a plane source located at the origin of the coordinate system, he pointed out that Gaussian penetration behavior should be observed. For case A the lattice coefficient should be slightly enhanced by dislocation contributions, and the model of Hart2 can be used to predict the amount of this enhancement. For case C the observed coefficient should be that for the dislocation network and have little or nothing to do with lattice diffusion. Hart's model in its general form is still applicable, but the apparent diffusion coefficient for this case is virtually independent of dislocation density. Harrison's case B is that for which non-negligible contributions exist for transport by both mechanisms and "the concentration distribution does not approximate to any simple form." With the possible exception of very low temperatures where diffusion distances approach atomic dimensions, any real diffusion specimen will in general show non-Gaussian behavior provided the data are complete enough to uncover it. Thus, a "complete" set of data for any real system cannot be expected to be totally amenable to treatment by a simple mathematical model which does not take into account the relative distribution of transport by the various modes or submodes. For a particular sensitivity of specimen analysis and at a given temperature of annealing if the concentration profile could be observed as a function of time, "the behavior will initially be type C, and will develop into type B. and ultimately type A".1 Thus, it appears that the type of diffusion behavior which is experimentally observed in a given system depends very much upon the particular experimental conditions and the particular tools available to obtain the data. Interpreted in this fashion, Harrison's classification refers not to the diffusion behavior as a whole but to the relative sensitivity of the method of examination and completeness of the data. In the present paper we will: 1) assume that the measured penetration behavior follows the same general classification as that proposed by Harrison; 2) give, for diffusion in tungsten, examples of the range of diffusion coefficients that it is possible to obtain in a single experiment; and 3) speculate that some arguments which consider the possibility of short-circuiting effects being responsible for "anomalous" diffusion in several bcc metals may have been discarded prematurely.3 Both monocrystalline and polycrystalline tungsten were used in this work. The former was obtained as triple-pass, electron-beam zone-refined 6.0-mm-diam rod from Materials Research Corp.. Orange-burg. N.Y. The latter was swaged, high-purity bar stock which was annealed for 2 hr at 2200°C and 10-9 torr to yield an average grain diameter of about 25 /i. The tracer Nb95 was received in oxalate solution from the Isotopes Division, Oak Ridge National Laboratory. Experimental procedures of specimen preparation, isothermal diffusion annealing, serial sectioning by anodizing-and-stripping, and y counting of the individual sections to determine the tracer penetration profile after a given diffusion anneal have been described elsewhere.4 However, it should be noted that the anodizing-stripping sectioning technique has the particular advantage for this research of permitting sectioning to be accomplished over a wide range of

Jan 1, 1970