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Ahrenholz, Herman William, Jr., Student, Lehigh Univ Bethlehem, Pa. '35 Allen, Carl A., Student, Colorado School of Mines Golden, Colo. '35 Allen, Paul W., Student, Mass. Inst. of Tech Cambridge, Mass. '35 Allen, R. M., Jr., Student, Virginia Polytechnic Inst., "G" Co Blacasburg, Va. '35 Amberger, K. H., Student, Michigan College of Min. & Tech Houghton, Mich. '35 Andersen, Burton Lee, Student, School of Mines, Univ. of Washington Seattle, Wash. '35 Anderson, Joseph S., Student, Univ. of Texas El Paso, Tex. '35 Anderson, R. C., Student, Univ. of Washington Seattle, Wash. '35 Ansel, Gerhard 627 Clyde St., Pittsburgh, Pa. '34 Anutta, Frederick P., Student, Michigan College of Min. & Tech Houghton, Mich. '35 Apsouri, Constantin N., Graduate Student, Univ. of Arizona Tucson, Ariz. '35 Arakelian, Haig Mark, Student, Mass. Inst. of Tech Cambridge, Mass. '34 Archer, George K 1420 Court Pl., Denver, Colo. '34 Argall, George O., Jr., K. E. House Golden, Colo. '35 Argiielles, Alfredo, Student, Univ. of Texas El Paso, Tex. '35 Atwater, Ralph, Student, South Dakota School of Mines Rapid City, S. D. '35 Austin, Robert B., Miner, Page Mine, Federal Min. & Smelt. CoSpokane, Wash. '34

Jan 1, 1934

By Samuel S. Wyer

The following abbreviations hare been used in the text: Am. Mfr. and Iron World. American Manufacturer and Iron World, Pittsburg, Pa. Can. Min. Rez;. Canadian Mininy Review, Ottawa, Can. Cuss. Mag. Cassier's Mayazine, New York, N. Y. Col. Eng. Colliery Engineer, Scranton, Pa. Col. Guard. Colliery Guardian, London, Eog. Eng. and Min. Jour. Engineering and Mining Journal, New York, N. Y. Eng. News. Engineering News, New York, N. Y. Engr. Engineering, London, Eng. J. I. and 8. I. Journal of the Iron and Steel Institute, London, Eng. Jour. W. Soc. of Engrs. Journal Western Society of Engineers, Chicago, Ill. Lond. Eng. The Engineer, London, Eng. Mines and Min. Mines and Minerals, Scranton, Pa. North of Eng. I. M. E. North of England Institute of Mining Engineers, Newcastle-on-Tyne, England. Oester. Zeitsch f. Berg u. Hüt. Oesterreichische Zeitschrift für Berg-und Hittenwesen, Vienna, Austria. Pract. Engr. Practical Engineer, London, Eng. Proc. I. C! E. Proceedings Institution of Civil Engineers, London, Eng. Trans. A. I. M. E. Transactions American Institute of Mining Engineers, New York, N. Y. Trans. A. S. M. E. Transactions American Society Mechanical Engineers, New York, N. I!. Duns. Fed. I. M. E, Transuctions Federated Institute Mining Engineers, Newcastle-on-Tgne, England. Trans. L 31. E. Transactions Institute Mining Engineers, Newcastle-on-Tyne, England.

Jan 1, 1907

By P. B. Baxendell, R. Thomas

Work on the calculation of vertical two-phase flow gradients by Cia. Shell de Venezuela has been based mainly on the "energy-loss" method proposed by Poett-mann and Carpenter in 1952. The "energy-loss-factor" correlation proposed by Poettmann and Carpenter was based on relatively low-rate flow data. This correlation proved inapplicable to high-rate flow conditions. In an attempt to establish a satisfactory correlation for high rates, a series of experiments was carried out at rates up to 5,000 BID in Cia. Shell de Venezuela's La Paz field in Venezuela, using tubing strings fitted with electronic surface-recording pressure elements. As a result of these experiments a correlation between energy-loss factor and mass flow rate was established which is believed to be applicable to a wide range of conduit sizes and crude types at high flow rates (e.g., above 900 BID for 27/8-in. OD tubing). It is anticipated that the resulting gradient calculations will have an accuracy of the order of % 5 per cent. At lower flow rates the energy-loss factor cannot be considered as constant for any mass rate of flow, but varies with the free gas in place and the mixture velocity. No satisfactory correlating parameter was obtained. As a practical compromise for low flow rates, a modification of the curve proposed by Poettmann and Carpenter was used. In practice this was found to give gradient accuracies of approxirnately ± 10 per cent clown to flow rates as low as 300 B/D in 27/8-in. tubing. INTRODUCTION Production operations in Cia. Shell de Venezuela's light- and medium-crude fields are principally concerned with high-rate flowing or gas-lift wells. Under these conditions the analysis of well performance, the selection of production strings and the design of gas-lift installations are vitally dependent on an accurate knowledge of the pressure gradients involved in vertical two-phase flow. Initially, attempts were made to establish the gradients empirically as done by Gilbert,' but the results were not reliable due to scarcity of data over a full range of rates and gas-oil ratios. Several methods of calculation based on energy-balance considerations were attempted, but the computations were cumbersome and the results cliscouraging. In 1952 a paper was published by Poettmann and Carpenter' which proposed a new approach. Their method was also based on an energy-balance equation. but it was original in that no attempt was made to evaluate the various components making up the total energy losses. Instead, they proposed a form of analysis which assumed that all the significant energy losses for mutiphase flow could be correlated in a form similar to that of the Fanning equation for frictional 1osses in single-phase flow. They then derived an empirical relationship linking measurable field data with a factor which, when applied to the standard form of the Fanning equation, would enable the energy losses to be determined. The basic method was applied in Venezuela to the problem of annular flow gradients in the La Paz and Mara fields" This involved establishing a new energy-loss-factor correlation to cover high flow rates and, also, some adaptation of the method to permit mechanized calculation using punch-card machines. The final result was 1 set of gradient curves for La Paz and Mara conditions which proved to be surprisingly accurate. With the encouraging results of the annular flow calculations, several attempts were made to obtain a corresponding set of curves for tubing flow. Here, unfortunately, little progress could be made. The original correlation of Poettmann and Carpenter was based on rather 1imited data derived from low-rate observations in 23/8- and 27/8-in. OD tubing. It did not cover the higher range of production rates, and extrapolation proved unsuccessful. A new correlation covering high flow rates was required, but this proved to be extremely difficult to establish since tubing flow pressure measurements at high rates did not exist—due to the difficulty of running pressure bombs against high-velocity flow. The necessity for reliable tubing flow data increased with the development of the new concessions in Lake Maracaibo, where high-rate tubing flow from depths of 10,500 ft became routine. Thus. it was decided to set up a full-scale test to establish a reliable energy-loss factor for tubing flow conditions. A La. Paz field light-oil producer with a potential of approximately 12,000 B/D on annular flow was chosen. To obtain full pressure gradients, a special tubing string was installed which was equipped with electronic surface-recording pressure measuring devices,

By Cyril Smith

SOMEWHAT over ten years ago the author described studies1,2 on the constitution of the copper-silicon system. The copper-rich portion of this diagram is shown in Fig. 1. The experimental points freely dotted about the diagram seemed to justify an otherwise unconvincing diagram and for several years the curious reverse bend in the alpha-phase bound-ary was accepted as substantially correct, even by later investigators3,4 of the system who introduced changes in the high-silicon phases. The binary diagram has been used as a base for several ternary systems" without any suggested changes. Voce10 suspected the existence of another phase from his study of the cast alloys in the copper-manganese¬silicon system, but evidently hesitated to extrapolate this to the binary diagram, particularly in view of the too ingenious explanation that was advanced" to account for the pools of constituent clearly visible in castings; namely, that they were secondary alpha of twinned orientation deposited from beta. Von Schwarz,12 in 1932, called attention to the fact that this micro-constituent in copper-silicon alloy castings was anisotropic under polar-ized light and asserted that a new phase, not cubic, should be placed in the diagram adjacent to alpha. Sautner,13 on the basis of investigations with the polarizing microscope and with X-rays, introduced this phase into the diagram at about 6 per cent Si. The relevant part of his dia-gram is shown in Fig. 2. Sautner called the new phase beta, renaming the old beta phase zeta. To avoid confusion, in redrawing Fig. 2 the phases have been renamed in accordance with the terminology adopted in the present paper, in which the new phase is called kappa and the other phases retain the designation given them by Arrhenius and Westgren.4

Jan 1, 1939

By Robert H. Richards

Walter Renton Ingalls recently gave a very interesting talk before the student mining society of the Massachusetts Institute of Technology. In it he showed the present status of mining as he sees it. In the talk he explained that, while discoveries of great mining districts are still pssible, they are being made less and less often; that the great mining companies, although there are large numbers of mines offered for sale, are finding it less and less possible to find new mines that are up to the standard of richness that they wish for purchase. The natural conclusion is that better, cheaper, and more efficient methods of mining, concentrating, and smelting are needed if the lower-grade mines are to be worked at a profit. This is true also if the high-grade mines are to yield their greatest profit. This paper deals only with the concentrating or ore-dressing problem, and gives some thoughts which point towards greater profit. In a paper on The Development of Hindered-Settling Apparatus the writer showed that there were two main lines of work that would lead to greater saving, lower tailing assay, and, therefore, greater profit. The first is the recrushing of middling or tailing products for the saving of the contained values. This is well understood and largely carried out in existing mills. The second is the saving of fine free mineral at the first opportunity. This is a matter less well understood in the mills, and to dwell upon this the present paper is written. The writer is himself convinced and hopes to convince the reader that, for obtaining the above result, not only is better classification needed, but also more classification; that is, there should be more spigots or pockets to the classifier. His attention was recently called to a small mill which had a three-pocket cone classifier fed with from 2 to 0 mm. stuff, supplying feed to four Wilfley tables. The first spigot had about all the

Jan 1, 1914

By W. R. Ingalls

In choosing the unusual title given to this paper, in which the term "cyclic " might be substituted for "intermittent," my idea has been simply in respect of precision. We might say old method vs. new method, but that antithesis implies something of substitution that has not occurred and perhaps is not in sight. We may say horizontal retorts vs. vertical, but none of the older retorts are truly horizontal, and there are three different types of vertical retorts. Other complexities might be suggested. There is, however, a broad distinction between distilling that is accomplished in a periodic cycle, generally daily; and distilling that is accomplished continuously, irrespective of whether it be done in the vertical retorts of the New Jersey process or in the retorts of the Trollhät-tan process. In offering a summary of the present state of the art with the intermittent process, I shall not have any idea of exemplifying it through descriptions of any single plants, but shall rather divide among the main steps of the process and outline what is best developed among them. In pursuing this thought, it will manifestly be impossible to make a composition that will exemplify the acme of good practice, for the latter will always be a function of the cost of labor, fuel, etc., which are widely variable. As of 1929, in respect of labor we might generalize the average plant wage in the Pittsburgh-Wheeling district of the United States at $5 per day; in Oklahoma at $3; in Great Britain at $3; in Germany at $1.75-$2; in Belgium and France at $1. With high labor costs the metallurgist will naturally use means of the nature of mechanization that with low labor would be uneconomical when capital charges are taken into account. Nor may we from records of performance safely make positive deductions in respect of the efficiency of different types of furnaces unless they have been tested comparatively under identical conditions in the same works. We shall find gas-fired regenerative furnaces showing coal consumption from 1.2 tons down to 0.7 per ton of roasted ore, which may be ascribable to difference in the thermal value of the coal that is used or to differences in proportions of the parts of the furnace, which is something quite distinct from the principle of the furnace. Thus, we have

Jan 1, 1937

Coal was known in this county before 1819, but there is no record of its use before that year. In that year a furnace, the first one built in the northwestern countries, was put in blast on Bear Creek; it was built to use coke and its first blast was with this fuel, which was made in heaps, but the blast was too weak and the furnace chilled after two or three tons of iron had been made. Charcoal was then substituted, and this use of coal ceased.1 In November of the same year a resolution was adopted urging state aid for a road from Kittanning to. Hamilton, New York: "that this road will increase the trade and industry of the whole county, between Pittsburgh and the New York line; and that our soil will in consequence be better tilled, our mines of coal, of iron and of salt, be better wrought, etc."2 In 1828 an advertisement of lands situated near Freeport on the Allegheny River and contiguous to the canal nearly completed between the Kiskiminitas and Pittsburgh stated that they contained "large and never failing springs, Coal in abundance, and a great deal of Fine Timber."3 In 1830 there were said to have been 24 salt wells in this county producing 327,000 bushels of salt, chiefly on the Kiski and Allegheny Rivers. In 1837 there were a number of wells in the vicinity of Freeport. As all the salt works on the Conemaugh River, were using coal long before 1830,4 it is safe to say that a considerable tonnage of coal was used for some years in these plants. In 1837 a tract of land in Clarion Township having a new saw mill and abounding "in Stone Coal" was offered for sale,5 and also one in Toby Township having "an abundance of the best quality of iron ore and stone coal."' In 1839 an advertisement in the Pittsburgh Mercury said

Jan 1, 1942

President MRS. HARRISON SOUDER south Paramus Road Ridgewood, N. J. First Vice-president MRS. ROBERT HURSH New York N. Y. Second Vice-president MRS. RICHARD LLEWELLYN LLOYD Great Neck, L. I'. N. Y. Third Vice-president MRS. PERCY E. BARBOUR New York N. Y. Fourth Vice-president MRS. E. P. MATHEWSON Tucson Ariz.

Jan 1, 1937

By F. M. Drake

IN this paper I propose to describe a plant which I lately erected for the Mount Stewart Lead and Silver Mining Company of Leadville, New South Wales, Australia. I am indebted to Mr. W. F. Burrow, of the Roads and Bridges Department of New South Wales, for the drawings which I present herewith, he having reduced and assembled them from my working drawings. The works are situated on a sloping hillside, but sufficient fall mas not available to have the furnace as high as desired, and at the same time have a good slag-tip and sufficient depth on the ore-floor to store a supply of ore and flux. The ore is delivered on the ore-floor (which is of the full width of the furnace-building, and extends back into the hill a distance of seventy feet) by two overhead tramways (not shown in the drawings), one on each side. From these the ore-mixture is made up on one side, while it is being taken to the furnace from the other. The fuel also is delivered by these tramways. The fluxes are stored on a floor directly at the back of the boiler and engine room. The boiler is a Cornish one, 6 feet 6 inches in diameter by 25 feet long. Its flue is 3 feet in diameter and does not contain Galloway tubes. The working-pressure is 40 pounds per square inch. The engine is an old-fashioned one, with a cylinder 16 inches in diameter by 30 inches stroke. Both the engine and boiler had been part of the plant of a defunct gold-mining company. They were very extravagant in their consumption of fuel. The blast is supplied by a rotary pressure-blower, of the Baker pattern, made in England. It has a capacity of 60 cubic feet per revolution. The furnace, which has several novel points, is shown in detail in Figs. 1, 2 and 3. The jackets are of cast-iron, and are higher than those generally used. They are different, too, in that the feedwater inlet is through a hand-hole plate near the bottom. This plate is fastened to the jacket by stud-bolts, and is provided with a baffleplate, which prevents the cooling water from impinging against the inner plate. The outlet is by a goose-neck at the top, which dis-

Jan 1, 1893

By M. A. Grossman

The harden ability of most steels can be predicted within 10 to I5 per cent provided the complete chemical composition is known, including "incidental" elements; and provided the as-quenched grain size is known; and provided, finally, that the composition and heating temperatures for hardening are such as to result in austenite free from carbide particles. In the method proposed herein, the steel is considered as having a base hardenability due to its carbon content alone (the hardenability of a "pure steel" of the given carbon content, without any other elements), and this base hardenability is multiplied by a multiplying factor for each chemical element present. After multiplying all these together, the final product is the hardenability. Grain size may be taken into account either in the base hardenability or after the multiplication. Hardenability is stated in terms of "ideal critical diameter", namely, the diameter of bar, in inches, that will just harden all the way through (absence of un-hardened core) in an "ideal" quench, and the calculation may also be related to the Jominy test The data bring out certain features rather clearly. For example: i. It is quite useless to attempt to predict hardenability unless all elements, including "incidentals,,) are known; thus an "incidental,, chromium content of 0.20 per cent increases the hardenability by about 50 per cent. 2. The relative effectiveness of different alloys is sometimes unexpected; thus molybdenum when calculated in this way appears to be of the same order of effectiveness as manganese, rather than much more powerful, as would appear to be common experience; observe that an increase from no manaanese to 0.20 per cent Mn provides a multiplying factor of 1.67, and an increase from no molybdenum to 0.20 per cent Mo provides a factor of 1.63, an increase of over 60 per cent in each case. However, if to a steel containing 0.50 per cent Mn there is added "20 points of manganese," the factor is raised from 2.65 (for 0.50 per cent Mn) to 3.35 (for 0.70 per cent Mn), or an increase of only 26 per cent. Thus the fist small addition of an element has a much more powerful percentage effect than an equal further addition when some is already present, and in most cases the effect of molybdenum is considered in relation to a steel in which molybdenum is absent. 3. If two elements are equally effective, a greater hardenability will be obtained by using, for example, 0.5 per cent of each than by using I.o per cent of either of them alone. 4. A knowledge of the as-quenched grain size is essential for precise work, since a difference of only one grain size number (say No. 7 instead of No. 6) makes a difference of almost 10 per cent in hardenability (in these units); this, however, does not apply to certain It should be emphasized that in chromium steels (over 0.30 per cent Cr) and chrome-molybdenum and chrome-vanadium steels, un-dissolved carbides are likely to be present in the steel as quenched, and that in such cases the charts can indicate only a maximum Passible hardenability, whereas the extent of hardening actually obtained may be much less. Thus tests on a number of chrome-molybdenum steels have indicated a degree of hardening amounting to only 50 to 65 per cent of the maximum possible, and in chromium steels from full hardening (100 per cent) down to as low as 70 per cent. On the other hand, when the amount of such elements is small (Cr under 0.30 per cent, Mo up to 0.25 per cent in the

Jan 1, 1942

By M. A. Grossman

The harden ability of most steels can be predicted within 10 to I5 per cent provided the complete chemical composition is known, including "incidental" elements; and provided the as-quenched grain size is known; and provided, finally, that the composition and heating temperatures for hardening are such as to result in austenite free from carbide particles. In the method proposed herein, the steel is considered as having a base hardenability due to its carbon content alone (the hardenability of a "pure steel" of the given carbon content, without any other elements), and this base hardenability is multiplied by a multiplying factor for each chemical element present. After multiplying all these together, the final product is the hardenability. Grain size may be taken into account either in the base hardenability or after the multiplication. Hardenability is stated in terms of "ideal critical diameter", namely, the diameter of bar, in inches, that will just harden all the way through (absence of un-hardened core) in an "ideal" quench, and the calculation may also be related to the Jominy test The data bring out certain features rather clearly. For example: i. It is quite useless to attempt to predict hardenability unless all elements, including "incidentals,,) are known; thus an "incidental,, chromium content of 0.20 per cent increases the hardenability by about 50 per cent. 2. The relative effectiveness of different alloys is sometimes unexpected; thus molybdenum when calculated in this way appears to be of the same order of effectiveness as manganese, rather than much more powerful, as would appear to be common experience; observe that an increase from no manaanese to 0.20 per cent Mn provides a multiplying factor of 1.67, and an increase from no molybdenum to 0.20 per cent Mo provides a factor of 1.63, an increase of over 60 per cent in each case. However, if to a steel containing 0.50 per cent Mn there is added "20 points of manganese," the factor is raised from 2.65 (for 0.50 per cent Mn) to 3.35 (for 0.70 per cent Mn), or an increase of only 26 per cent. Thus the fist small addition of an element has a much more powerful percentage effect than an equal further addition when some is already present, and in most cases the effect of molybdenum is considered in relation to a steel in which molybdenum is absent. 3. If two elements are equally effective, a greater hardenability will be obtained by using, for example, 0.5 per cent of each than by using I.o per cent of either of them alone. 4. A knowledge of the as-quenched grain size is essential for precise work, since a difference of only one grain size number (say No. 7 instead of No. 6) makes a difference of almost 10 per cent in hardenability (in these units); this, however, does not apply to certain It should be emphasized that in chromium steels (over 0.30 per cent Cr) and chrome-molybdenum and chrome-vanadium steels, un-dissolved carbides are likely to be present in the steel as quenched, and that in such cases the charts can indicate only a maximum Passible hardenability, whereas the extent of hardening actually obtained may be much less. Thus tests on a number of chrome-molybdenum steels have indicated a degree of hardening amounting to only 50 to 65 per cent of the maximum possible, and in chromium steels from full hardening (100 per cent) down to as low as 70 per cent. On the other hand, when the amount of such elements is small (Cr under 0.30 per cent, Mo up to 0.25 per cent in the

Jan 1, 1942

By C. R. Austin

In a recent paper1 the authors presented information on a refinement of the Rohn type of creep test with data on pure iron that exemplified the behavior of the apparatus. The present paper extends that work to nickel and cobalt and to the examination of the comparative high-temperature properties of two widely used commercial alloys. Careful attention has been given to the effect of plastic deformation in decreasing creep rate, using the elementary metals iron, nickel and cobalt for purposes of analysis. In any endeavor to develop new materials for high-temperature service one soon encounters a real problem as to the sort of test to be employed in evaluating the commercial possibilities of the alloys. At one time it was considered satisfactory to determine the tensile strengths at elevated temperatures and to use these values as a criterion for the commercial application of the alloys. More recently the proportional limit has been used as a means of classification. Data obtained from a form of bend test have also shown promise as providing a "merit index" of high-temperature serviceability.= Koerber and Pomp3 state that since the influence of testing time is small, the high-temperature yield point of steel furnishes sufficiently reliable and concordant values up to about 350" C. (and a maximum of 450" C. for alloy steels) to serve as a suitable basis for comparison evaluations of materials and for judging permissible stresses. Koerber and Pomp consider, however, that above these temperatures creep limit must be substituted for the high-temperature yield point as the all-important characteristic of the material. Whatever may be their definition of

Jan 1, 1934

By J. B. Nau

A short time ago some interesting experiments concerning a new steel-making process in the open-hearth furnace were made by the writer at the Croton magnetic mine, N. Y.

Jan 1, 1892

By Ed Van Eeckhout

As part of a U.S. Bureau of Mines-sponsored project on the utilization of "stiff" backfill to minimize potential rock burst hazards, a finite element study was undertaken to predict stresses and displacements around a stope mined up from the 5400 level of the Sunshine mine, Kellogg, Idaho. This stope was to be backfilled using a high-modulus fill. In preparation for that configuration, certain instrumentation was installed near the 5400 level to monitor stress changes. Due to untenable economics, only 2 cuts of the stope were ever made. This paper presents the results of the instrument readings taken during the first cut and compares them with the numerical predictions, as well as presents the modeling results of closure and fill stresses in the stope if it had been mined.

Jan 1, 1984

By J. L. Wyatt

THE strain sensitivity, K, a property of metals defined as the unit change in electrical resistance per unit strain, was measured for commercial purity titanium wire to determine its usefulness as a strain gage material. A Kelvin double bridge, accurate to 0.000001 ohm, was used to make measurements from 0 to 1 pct total strain. A positive value of 0.17 for K was found. This compares with 2.15 for constantan and 3.5 for cold-worked invar, two of the more common strain gage materials. The effect of temperature also was determined. It was found that a change in temperature of 30°F caused the same resistance change as 1 pct strain. It is therefore concluded that titanium would have utility as a strain gage only if the thermal fluctuations in the specimen could be controlled to a high degree and in applications of very large total strain.

Jan 1, 1953

By J. H. Frye, J. L. Scott, J. W. Woods

THERE are at least two effects of temperature on the stress required to produce plastic flow. 1) Metals plastically strained for the same amount at different temperatures possess different stress-strain curves and different internal structures (e.g., nature and density of imperfections). 2) There is both experimental and theoretical evidence that the stress necessary to produce plastic flow may vary with temperature even though the internal structure remains constant.1-5 Much of the data in the literature is difficult to interpret because these two effects are simultaneously present. In the work reported here, they are considered separately. Standard 0.505 in. tensile specimens were prepared from high-purity Mond nickel and OFHC copper. Nickel specimens were annealed in hydrogen at 1150°C for 30 min and furnace cooled. This produced an average grain diameter of 1.4 mm. Copper specimens were annealed in vacuum at 525°C for 6 hr and furnace cooled. This produced an average grain diameter of 0.11 mm. Nickel tensile specimens were prestrained in tension at 500°K, whereas copper tensile specimens were prestrained in tension at room temperature. All specimens were cooled to 74°K and heated to room temperature. After these treatments all of the tensile specimens of a given set possessed identical structures. All specimens were returned to the tensile machine and tested at various temperatures and constant cross-head speed. Many of the tensile curves showed well defined yields but, in order to minimize personal judgment, the yield was always chosen as the stress corresponding to 0.2 pct plastic deformation. Results are summarized in the graph of yield vs temperature of test, Fig. 1. All of the specimens corresponding to any one line have had identical treatments and, therefore, have identical internal structures. Thus, each line gives the relation between yield stress and temperature for one constant internal structure. The lowest line, which is for annealed nickel, shows no measurable variation of yield with temperature. This is similar to Blewitt's6 results on copper single crystals, but a variation in yield with temperature was found by Andrade and Henderson' in single crystals of nickel, and by Car-recker and Hibbard8 in annealed polycrystalline copper. The three other lines, which are for prestrained materials, show that there is a linear relation between yield stress and temperature when the internal structure remains constant. Such a relation might be expected from a rate equation such as that of Kauzmannl on the assump- tion that the activation energy is either independent of or linear with temperature. These results would also be expected if the shear moduli of copper and nickel are linear functions of temperature for, as Cottrell and Stokes have pointed out," in all dislocation theories of strength the flow stress appears proportional to the shear modulus of the material. In copper and nickel, since the modulus of elasticity decreases roughly linearly with increase in temperature," it is probable that the modulus of shear also decreases approximately linearly with increasing temperature. A detailed discussion of the effect of these and other factors on the temperature dependence of flow stress in face-centered-cubic metals has recently been given by Seeger.4

Jan 1, 1958

By D. G. Wilder

D.G. Wilder I found the suggestion that the amount of displacement of a fault can be numerically related to the thickness of gouge or breccia to be both intuitively satisfying and intriguing. I have long agreed that there is some type of relationship between the amount of gouge and the amount of displacement of faults. I congratulate the author for developing a numerical relationship between them. However, I am concerned that the limits for applying this relationship be fully understood. An underlying assumption in this approach is that there is either a uniform thickness of gouge or breccia along a given fault or the thickness does not vary widely. Since it is not always possible to confirm this, the displacements derived by this method should be viewed with caution unless significant fault extent can be observed. At the Nevada Test Site, in drifts constructed in granite for test emplacement of spent nuclear reactor fuel, we found a fault with 0.3 to 0.4 m (12 to 16 in.) of clay gouge. Within a few meters of this location, the fault had no clay gouge, but rather consisted of a highly fractured zone with significantly altered rock and some slickensides. Based on Fig. 1, the 0.3 to 0.4 m (12 to 16 in.) thickness of gouge would indicate a displacement in excess of 30 m (98 ft). However, no gouge thickness would indicate essentially no displacement. Based on a quartz vein that terminated on the fault, and is not identified nearby, an estimated displacement of more than a few meters was made. This estimate is consistent with that obtained using the regression line proposed in the paper if the 0.3 to 0.4 m (12 to 16 in.) thickness for the gouge is used. However, using the regression curves with zero thickness would not yield results consistent with what was observed in the field. Therefore, it is important to recognize that the suggested procedure would properly yield a range of probable displacements. ? *Work performed under the auspices of the US Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. Reply by E.C. Robertson It is certainly true that the t (thickness) of gg-bx (gouge and breccia) on a fault does vary along the fault. My observations have been that near the termination of a fault, the displacement d is small and the t is also small, whereas the maximum d and t will usually be found in the central part of the fault. The information on gg-bx and t of the fault found in granite in the NTS tunnel by Mr. Wilder could be interpreted somewhat differently than he does. He speaks of the fault changing within a few meters from 0.3 to 0.4 m (12 to 16 in.) of clay gg to "a highly fractured zone with significantly altered rock and some slickensides," but no gg. The highly fractured rock may be taken to be bx, rock not so finely ground as gg but still crushed by the fault movement, equivalent to the gg in my usage, and probably occupying about the same t. Mr. Wilder's estimates for the fault in the NTS tunnel for t of 0.3 to 0.4 m (12 to 16 in.) and for d of a quartz vein, in excess of "a few meters," would place the point on the low side of the central trend line in my Fig. 1, at the lower limit. There is, of course, a problem with determining d using displacement of only one planar surface. It would be greater or lesser depending on the rake of the movement. Finally, estimating the d of a fault from its t should be made with awareness of our present uncertainties, as pointed out by Mr. Wilder. Although the central trend line in my Fig. 1 has a ratio of d/t of 100, I have put the limiting ratios at 10 and 1000. Understanding of the values of the ratio will be improved only with collection of more data, for which the discussion of Mr. Wilder is much appreciated. ? G.C. Waterman E.C. Robertson's paper provides significant information to a geologist attempting to deduce fault offset by noting the products of structural dislocation. However, considerable mapping in underground and open-pit mines, and examination of structures produced in different geological settings, have convinced me that gouge and breccia thickness are controlled by geological conditions and fault movement. The following paragraphs suggest geological variables that control them. 1. Depth of Loading A near-surface fault resulting from tensional stress has more breccia/gouge than is produced by a similar stress at considerable depth. A deep-loaded compressional stress may produce a linear zone of schist, or structural dislocation may occur along an earlier formed belt of schist. Such "shear zones" are common in Canadian mines in precambrian rocks. In neither case can offset be directly deduced by an analysis of the minimal gouge/breccia in the shistose rocks. At greater depth, stress may be partially to wholly relieved by flowage. I vividly recall first noting the regional "Midas Thrust" in the Lark mine, Bingham Mining District, UT (where we called the structure the North Fault). My recorded notes, as I remember them, showed a narrow gouge streak separated the "Jordan" and "Commercial" limestone units from impure, muddy limestone beds of uncertain stratigraphic position. The visible structure did not indicate the great importance of this premineral fault

Jan 1, 1985

By F. S. Norcross

DEVELOPMENT of the manganese deposits of Cuba is a matter of importance not only to those involved in this industry on the Island but to the United States steel industry and to our Nation as a whole. For years our domestic resources of manganese have been wholly inadequate, but the recent Cuban development points the way toward solution of this strategic mineral problem.

Jan 1, 1939

By W. L. Zeigler

THE tailing from the gravity concentration plant of the Hecla Mining Co., Gem, Idaho, was former-ly loaded into railroad cars to be used for ballast, highway surfacing material, or concrete work, or dis-posed of by an aerial tramway, which dumped it into another gulch. The tailing averages about 1.2 per cent lead and 0.8 oz. silver to the ton. Further treatment for the recovery of the valuable metals had been investigat-ed several times with results that did not warrant the construction of a retreatment plant; but early in 1925 experimental work was again started with small tests, and later with a 10 tons per day flotation test plant. This showed that the tailing could be ground and treat-ed by flotation at a profit. It was decided to make the new flotation plant an addition to, rather than incor-porate it in the old concentrator, the original capacity of which had been increased many times, the present arrangement being by no means ideal. The old mill buildings were of timber and board contruction, creat-ing more or less fire hazard, so all new construction was made fireproof. Construction work on the new plant was started in the middle of July, 1925, and the plant was placed in operation early in December. The building is of concrete and steel with hollow tile walls, steel sash and corrugated asbestos roofing. The ball-mill floor has for its foundation a cellular reinforced concrete block about 14 ft. deep, extending to cemented river gravel, and the cells filled with tailing to give weight to the block. Overhead, built into the steel frame, is a 5-ton hand-operated traveling crane. With both ball-mills running fully loaded, there is not the slightest trace of vibra-tion in the foundation or building. The flotation floor is of reinforced concrete beam construction and spans Canyon Creek. Adjustable plunger feeders are arranged under the the tailing-bin, which feed by gravity to a 14-in. eleva-tor, discharging to a short 18-in. conveyor. From the conveyor the tailing is discharged into a dividing hop-per, from which point the plant is arranged in three separate units. Each unit consists of a ball-mill in closed circuit with a classifier, and an 8-cell flotation machine and has an approximate capacity of 300 tons per 24 hours.

Jan 8, 1927

By R. G. Treuting, W. C. Ellis

D. Whitwham, M. Mouflard, and P. Lacombe (British Council Research Fellow, Labratoire du Professor Chaudron, Vitry-sur-Seine; Inqenieur de Recherches, Labratoire de Vitry; and Maitre de Recherches, Labratoire de Vitry, Professeur Adjoint de Metallurgie, Ecole des Mines, Paris)—The authors' work is of great interest in bringing out the geometrical relations existing between twinned lattices, and for the notion of a coincidence super lattice developed from this. We should like to point out that a similar idea was put forward by Friedel8 in his book on the subject of lattice merohedrism "merihedrie réticulaire:"—When two crystals A and B are twinned with respect to a mirror plane, there exists a common superlattice, "réseau periode," which is independent of the contact surface between the two crystals. The volume V of this superlattice is a simple multiple of the volume v of the lattice of crystals A, or B, (Fig. 5). This "multiple cell" is defined by the twin plane (p q r) and a row of atoms [h k l] normal to this plane, the base being taken as the smallest unit (two-dimensional) of this plane. Two cases must be considered. First when the multiple cell, as defined, has no atom site at its center nor at the center of its faces other than (p q r), v the twinning index is defined by —. In the second v case, when one of the two above conditions does not v apply, then the twinning index is V 2v A more intuitive definition of the twinning index would be the proportion of atoms of C, which would coincide with those of C1 when the C, lattice is imagined to extend on the other side of the contact surface. In the case of cubic crystals, the twinning index

Jan 1, 1952