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By John Henry Harden

IN 1874, with Mr. H. Y. Attrill, of Baltimore, Md., I made an examination of some property at Goderich with reference to sinking for and mining salt. With this end in view we visited all the wells in the neighborhood, but the information sought being of so unreliable a character I advised the putting down of a borehole on the property. This has since been done, the result of which has lately been published by Dr. T. Sterry Hunt in the Toronto Globe. From this there appears to have been passed through six beds of salt of an aggregate thickness of 123 feet. Rock-salt was known to exist, for, by the boring of existing wells, small crystals had been brought to the surface in the dirt, but no attempt had before been made to obtain a reliable sample or to prove the number and thickness of the beds. The question now remaining for discussion is, shall the present method of obtaining the salt be continued, or shall the beds be won by a shaft in a regular mining fashion, by which means the salt may be gotten in a condition almost ready for the market? The present mode of obtaining salt is by boreholes from 6 inches to 8 inches in diameter drilled to the beds, into which is inserted a pump. The "feeders" of fresh water intersected in drilling the well are allowed to descend on the outside of the pump-tube to the salt beds and there become saturated, when, on use of the pump, brine is obtained for evaporation. In the beginning brine can only be had in limited quantity, but by the daily application of the pump, and the gradual solution of the salt, a larger surface becomes exposed to the action of the fresh water, and a continuous supply of brine is obtained. It will then be understood that the supply of brine is dependent upon the feeders of fresh water intersected in boring the well, which, we are told, have never shown any sign of diminution, and this is the water that must be encountered in sinking a shaft. There are ten wells in operation at Goderich, the most important one to the present project being known as the Hawley Well, located at an elevation a few feet above Lake Huron at the mouth of the river Maitland, at a much lower level and nearer to the proposed shaft than any other well in the district. At this well the feeders

Jan 1, 1877

By J. E. Hanlon, S. R. Butler, R. J. Wasilewski

It is known that stoichiometric NiTi transforms to a structure of lower symmetry near room temperature. The present investigation deals primarily with the changes in the electrical and magnetic properties which occur at the transformation. The effects of composition and various heat treatments on electrical properties are also discussed. In recent investigations by Purdy and Parr,' Wang et a1.,2 Dautovich and Purdy,~ Dautovich et a1.,4 and the authors, ~,' NiTi has been observed to undergo a martensitic phase transformation from the ordered CsCl (B2) structure to one of lower symmetry. The crystal structure of the low-temperature modification is still not completely worked out. This transformation occurs near room temperature for the stoichiometric composition. The thermodynamic, elastic, crystallographic, and microstructural characteristics of this transformation for some compositions have been previously reported.'-= In the present investigation, the changes in the electrical transport properties and magnetic susceptibility of NiTi when it undergoes the martensitic phase transformation have been measured. The approximate composition range covered is 48 to 52 pct Ti.* *All compositions are given in atomic percent._____________________ EXPERIMENTAL PROCEDURES AND RESULTS 1) Sample Preparation. The NiTi alloys were prepared from iodide titanium (>99.92 pct Ti) and vacuum-premelted carbonyl nickel (>99.95 pct Ni) by repeated arc melting under gettered argon and casting in a water-cooled copper mold. After the cast buttons were hot-forged at 800" to 950°C, the oxidized surface was removed by grinding and etching. Samples were cut from the worked polycrystalline buttons. After fabrication, the samples were annealed 1 hr at 900°C and water-quenched. The composition of the alloys was assumed to be the same as in the initial feed. This assumption was supported by material balance checks on 100-g arc-melted buttons which demonstrated quantitative recovery to within k0.02 pct. The oxygen content of the alloys was '150 ppma (weight) and the carbon content was 30 to 50 ppm. 2) Electrical Resistivity and Hall Effect. The electrical resistivity was measured over the composition range 48 to 52 pct Ti for temperatures varying from 4.2"K to 900°C. The high-temperature and many of the low-temperature experiments were carried out using conventional 4-probe dc techniques.7 The Hall coefficient and ac resistivity were measured at 20 cps using the apparatus shown schematically in Fig. 1. The equipment is basically an ac potentiometer: The resistive or Hall voltage of the sample is balanced by a comparison voltage provided by a dividing network across a standard series resistance. The off-balance signal is amplified by a Tektronix 122 amplifier and detected by a Princeton Applied Research (PAR) phase-sensitive detector. The precision of the resistivity and Hall coefficient measurements is i0.1 and i3 pct, respectively. The uncertainty in the data is increased by i2 pct from the precision limits because of uncertainty in dimensions and possible end effects. The temperature dependence of the electrical resistivity and Hall effect for a stoichiometric (50.0 pct Ti) NiTi sample are illustrated in Fig. 2. Above 75"C, this sample has essentially the B2 structure, while below about 0°C it is completely in the low-tempera-

Jan 1, 1968

By James W. Shaffer

Aluminum is the most abundant metallic element of the earth's crust and is a constituent of nearly every type of rock (Clark, 1924, p. 13). The sources of aluminum and aluminous material most commonly used by modern industry are the bauxitic raw materials consisting of bauxite, bauxitic clay, and aluminous laterites. These are mixtures of hydrated aluminum oxide minerals and mineral impurities. End Uses Bauxite is used as an aluminum ore and in the manufacture of refractory products, aluminous chemicals, and abrasives. Other raw materials are used for aluminum ores, but their use is minor compared to bauxite. Refractory products made from bauxite are synthetic mullite, high-alumina fire bricks, castables, monoliths, cements, and ramming mixes used by the iron, steel, and cement industries. Chemicals made from bauxite are aluminum sulfate and sodium aluminate for water treatment and aluminum chloride used in refining crude petroleum. Among the abrasive products made from bauxite are coated abrasives, sharpening stones, and grinding wheels. Special grades of bauxite are used in the decolorization and clarification of raw sugar and lubricating oils. Bauxite has been used for road surfacing but mainly because other material was not more readily available. Perhaps the oldest use of bauxite and aluminous laterite is for a building stone. Ancient temples and more recent structures in India have been made from these and some varieties are suitable for decorative stone. Geology Mineralogy and Properties – Bauxite is a mineral raw material composed principally of one or more hydrated aluminum oxide minerals and impurities of silica, iron oxide, titania and elements in minor or trace amounts. The hydrated aluminum oxide minerals are gibbsite, boehmite and diaspore. Corundum is not included as a bauxite mineral although it does occur in some bauxite deposits. Boehmite and diaspore are both alumina mono-hydrates and have essentially the same composition, but diaspore has a greater hardness and a higher specific gravity because of a more tightly bonded and compacted atomic structure. Gibbsite is an alumina trihydrate mineral. Properties of bauxite minerals are shown in [Table 1].

Jan 1, 1975

By P. Pollard

A method has been developed for evaluating acid treatments in fractured limestone fields by breaking down pressure drawdown into three component parts: (I) pressure differcntial across "skin" near the borehole face, (2) pressure differential due to flow resistance in the coarse communicating fissures and (3) pressure differential between the fine voids and the coarse fissures. It is apparent that in most successful acid treatments the first term, skin resistance, has been reduced or eliminated. Further, it is often possible to estimate the volume of coarse fissures associated with the second term, coarse fissure flow resistance. In cases where this volume is comparable with practical acid volumes it seems likely that this resistance also may be attacked with a suitably retarded acid. INTROD UCTION Acid treatment has been successfully applied as a general practice in the limestone wells in the Mara/ Maracaibo districts of Venezuela for some 10 years. At the same time the need has been felt for a more precise method of: (1) evaluating the effect of an acid job and (2) selecting wells which should benefit from an acid treatment. The following method, based on an analysis of build-up curves for wells producing from fractured limestone, provides a means of forecasting the effect acid will have on a well and in many cases the probable order of production rate increase which may be expected. In certain cases it is also possible to calculate the fissure volume through which the acid has to be displaced for best results. Various approximations are introduced in the method, but within the limitations of these the analysis gives an indication of how a well, whether previously acidized or not, may be expected to respond to acid treatment. Suitable build-up curves cannot be obtained on "tight" wells which do not give sustained production and the method is not applicable to such wells. Figs. 1 through 7 illustrate various types of build-up curves obtained from limestone wells in Western Venezuela. Curves are included showing (1) both skin and coarse fissure resistance, (2) skin resistance only, (3 and 4) reduction of skin resistance by acidization, (5) fissure resistance only, (6) reduction of coarse fissure resistance by acidization, and (7) acidization failure. This theory has been successfully applied for over three years during which 22 acid treatments have been carried out specifically to reduce skin resistance and three treatments to reduce coarse fissure resistance. The method has been found to be a useful aid in the selection of wells for acidization.

By H. B. FERNALD

THE interesting and carefully developed formula which Professor Bucky presents for answering the question of whether proposed new equipment will give a net return on investment equal to or greater than that on present equipment starts with an assumption that the management may make this relative return a determining factor in its decision whether or not the new equipment should be provided. I do not question that in some cases the management may take this position, but I would point out the error involved in so doing. The proper test is not a comparison of the return on new as compared with the return on old investment, but is rather a comparison of the return on a particular new investment as compared with the return which would be obtainable from some other new investment which now might be made. Then I would point out that I believe Professor Bucky is in error in using as a factor in his computations the item of unamortized cost of old investment. The financial advantage to be derived from a new investment does not depend on the extent to which we may in the past have written off the cost of old equipment, nor does it even depend upon what was the original cost of that old equipment. Even the salvage or resale value of the old equipment will only enter into the picture to the extent that the present salvage or resale value differs from the ultimate salvage or resale value otherwise to be obtained, after due allowance for the interest factor.

Jan 1, 1930

By C. M. Weld

In the course of my professional work in China during the fall of 1907, I had an opportunity to visit the iron-ore mines at Ta-yeh in Hu-pei province (long. 114O 50t E., lat. 30' 20t N.). It occurs to me that a rescript and discussion of my notes taken at that time should be of interest, particularly as supplementing the exceedingly interesting recent paper of Thomas T. Read on The Mineral Production and Resources of China.' Ta-yeh is situated near the right bank of the Yangtze river. The mines are at an average distance of about 16 miles from the river-port Shi-hui-yao, which in turn is some 70 miles SE. of Hankom. The ores are shipped to the works of the Han-Yeh-P'ing Iron & Coal Co. at Hanyang, as also very largely to the Japanese government iron- and steel-works at Wakamatsu, Japan. Smaller qnantities have been exported to the Pacific coast of the United States. These ore-deposits have been briefly noticed in a number of publications, but, so far as I know, Mr. Read's description, in his chapter or1 the iron-ores of the Chinese Empire,2 contains the first attempt to define their geological character. In his more recent paper Mr. Read follows very closely the text of his earlier description. To quote briefly from the recent paper, he says : " The iron-ores at Ta-yeh .... lie along the contact between a marble and an intrusive body of a dark-gray syenitic rock." He refers to a figure which exhibits in plan, but not in section, the relative positions of the syenite, ore-bodies, and limestone. The contact is seen to trend approximately E-W., with the syenite on the north and the limestone on the south. " The syenite lies to the north of the marble, and a few miles farther north the marble again appears, iron-ore again being present along the contact." No litho-

Jan 1, 1913

By C. H. Mathewson

MY first reflection on the subject assigned to me by the officers of this symposium was that a critical description of these lesser characters in the cast of inanimate actors now before us under the title "The Role of Metals in New Transportation" would be about as well received as the description of a horse race in terms of harness buckles and jock-ey's buttons. The word "new" in the title of this symposium seems to shout strong aluminum and stainless steel, unless we transfer our attention to transpor-tation on another planet where the strength-density ratios may require very different engineering treatment. To load a speaker with the "heavier nonferrous metals" amidst the airy consideration of flying or 20th century gliding along the earth and through water, like Hermes, the messenger of the immortals, and expect an instructive or enlivening flight into the area of current exploitation and popular interest in transportation would, of course, require the performance of a miracle or at least the exhibition of genius to which I can lay no claim. But copper and nickel, headliners in other classifications, are also indis-pensable as components of the important new structural materials of transportation, and together with lead, tin and zinc perform many minor or contributory functions in this field that may indeed be con-sidered well-nigh indispensable. A complete and well planned fabric of classification, explanation and critique of even these secondary functions would take much time, and I cannot hope in the 25 minutes or so alloted for the purpose to offer more than a rambling treatment, in which a thread of continuity will be sought by anchorage to one after another of the following attributes or appurtenances of the moving vehicle: 1. The machinery and accessories. 2. The framework and superstructure, and the line or travelway. 3. Light, heat, power, water, sanitary and housekeeping services. 4. Embellishment, or style.

Jan 1, 1936

ALTHOUGH the refining period of the heat is generally defined A as starting after the charge has been completely melted, it may more properly be considered as beginning with the first efforts to facilitate the shaping up of the slag and the making of corrective additions for the control of slag or metal composition. Such actions may be initiated during the latter half of the lime boil. The early part of the refining period may, then, in essence overlap the latter part of the melting period. The primary aims of the refining period are: (1) to reduce phosphorus and sulfur from the steel bath to levels safely below the maximum contents specified; (2) to eliminate carbon to a specified level as rapidly as possible and still allow time for proper conditioning of the slag and attainment of the necessary bath temperature; and (3) to have the heat ready for tapping or furnace deoxidation, with slag in the proper physical and chemical condition, and with carbon and oxygen contents and the temperature of the steel at the proper levels for the composition and grade of steel being produced. The particular conditions that fulfill these aims are distinctly different, depending upon whether the steel is to be finished according to fully killed semikilled, or rimming practice and also depending upon the carbon range specified. Regardless of the type of charging practice employed, the object of the refining period is to produce repeatedly the desired finishing and tapping conditions for the grade of steel being produced. The variations and proportions of raw materials used in the charge may cause some variations in the degree of control required during refining, but not in the method of control. The refining period can therefore be discussed from a viewpoint largely independent of charging and melting practice. SHAPING UP THE SLAG In the first helper's vocabulary, refining practice consists in

Jan 1, 1964

By E. P. Mathewson

A Discussion of the Paper of E. P. Mathewson, presented at the New York Meeting, April, 1907, and printed in Bi-Monthly Bulletin, No. 13, January, 1907, pp. 7 to 14. PROF. HENRY M. HOWE, New York, N. Y. (communication to the Secretary *) :-The results presented in Mr. Mathewson's paper are of very great interest. Perhaps the most interesting is that shown in Table I. and Fig. 1, in which the arsenic decreases in 10 min, from 0.22 to 0.07 per cent. This is such a large decrease that it is to be hoped that Mr. Mathewson will verify it by repeating his tests with a matte of similar composition. This is particularly to be desired, because the simultaneous removal of sulphur appears to be very small. All three blows further agree in showing that the removal of arsenic is in the very early part of the blow. The fact that the removal of arsenic then ceases abruptly cannot be explained completely by the fact that the arsenic has fallen so low as by its lowness to resist further removal, because in the first blow the arsenic becomes stationary at 0.06 per cent., whereas in the third blow it does not become stationary until it has fallen to 0.034 per cent. The abrupt ending of the re¬moval of arsenic is more likely to find its explanation in the composition of the slag, and it is to be hoped that. Mr. Mathewson will supplement these extremely valuable data with others in which the composition of the slag at the same time shall be given. The sudden rise of arsenic toward the end of the third blow I suppose must be referred to an error in sampling or analysis. Mr. Mathewson speaks on page 14 of the "percentages of iron . . . volatilized during the first period." Is it his meaning that all this iron is really volatilized, or does he mean that the iron is scorified and the sulphur volatilized ?

Jul 1, 1907

By H. A. Coy

THE Mascot mines of the American Zinc. Co. of Tennessee are situated at Mascot, Tenn., 14 miles northeast of Knoxville, on the Southern Railway. The district is centrally located in the Great Valley, or Appalachian Valley Province. Prior to 1900, a small output of zinc was obtained from oxidized ore mined in open pits. In 1900, a shaft was sunk to sulfide ore, and in 1903, a second shaft was put down, neither being as deep as 200 ft. The American Zinc Co. of Tennessee began drilling in 1911, and outlined an ore body to which its No. 1 shaft was sunk, to a depth of 365 ft. Since that time, the American Zinc Co. of Tennessee has been the only operator in. the district. The Federal mining laws have never been in operation in Tennessee and mining lands are as irregular in boundary and area as farm lands. Ownerships are generally held in fee. In most cases the surface and mineral rights, are transferred together. Electric power is supplied at 66,000 volts by the Tennessee Power do, from a hydro-electric plant at Parksville, Polk County, Tenn., 100 miles from Mascot. No other power is used, but an emergency steam plant is held ready in case of interruption of service. Labor is all native and non-union. Negroes are employed for most of the shoveling, and for a few miscellaneous jobs, but for almost, no other work.

Jan 9, 1924

By J. T. Norton, J. G. McMullin

E. R. JETTE*—The way this ternary was developed there are two directly determined points on each of the iso-thermals except the 700° isothermal, where I believe there is only one. How were the end points determined, and what was the basis for it? Whose work formed the basis for the silver copper line ? M. B. BEVER †—At most temperatures the authors determined three points of the isothermal line. For example it can be seen from Fig 3 and 4 how three points for the 600°C contour line were obtained. The authors took two additional points for each temperature from the copper-silver binary diagram contained in Hansen's volume on constitution diagrams. It is correct that the 700°C contour line is based only on one point in the ternary field which was found by a slight extrapolation of Fig 4. R. I. JAFFEE*—Are the tie lines representing phases in equilibrium parallel to the silver-copper boundary ? M. B. BEVER—Are you asking that as a matter of principle ? R. I. JAFFEE—I assumed that would follow from principle. I wonder if that is in accordance with the authors' ideas too. M. B. BEVER—I do not believe the authors obtained any information on the tie lines in the two-phase field. Of course, in the limiting case of very low gold contents the tie-lines approach to the silver-copper boundary, but generally in the two-phase field I do not think that the tie-lines have to be parallel to the boundary. E. R. JETTE—I am quite sure they do not have to be parallel. You cannot tell from this work in which direction they go. E. A. GULBRANSEN*—Were any pycnometric measurements made to check the lattice parameters of the alloys ? M. B. BEVER—I did not hear any-

Jan 1, 1950

MINING ENGINEERING presents the annual membership report of the Society of Mining Engineers; see page 109.

Jan 7, 1963

By R. F. Mehl, G. V. Smith

THE decomposition of austenite in steels, because of its immense practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1-3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings-pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. PEARLITE Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix .2-5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrongly, as Mehl and Smiths have pointed out, that the lamellae delineate the [210] planes of ferrite.* MARTENSITE It is known that martensite is a transitional constituent of body-centered tetrag-

Jan 1, 1942

By S. V. Krusiewski, J. W. Gabelman

Regional metallogenic zones and areas of equal paragenetic range have been interpreted from a compiled metallogenic map. of Mexico. Mineralization gradients of the pattern subsequently identified extend inland from coastal zones of high-temperature mineralization, and join in a central longitudinal zone of relatively low-temperature mineralization, apparently leaving no zonal room for lowest temperature deposits. The striking regional zoning pattern can be correlated with regional deformation gradients of similar position and orientation. The gradients represent at least three major orogenic cycles in two structural belts. Paleozoic structural belts existed along each coast with deformation gradients diminishing inland toward a narrow, central peninsular craton. The Mesozoic-Tertiary Mexican (Cordilleran) belt covered the entire country with a gradient oriented toward the Gulf of Mexico. Most ore deposits in this belt are of Tertiary age, although Tertiary mineralization gradients seem to have "inherited" the pattern left by Paleozoic tectonic gradients. Mineralization gradients can be used to identify the regions most favorable for the occurrence of selected metals. A metallogenic province is characterized by particular proportions of various metals, and the relative proportions can vary from province to province; but within any province the same intensity of mineralization would produce similar deposits in different places. Declining intensity of minetalization produces different kinds and sizes of deposits in zones that are concentrically arranged around sites of strongest rock alteration. On a regional basis, districts of similar average intensity of mineralization occur in zones that generally parallel some tectonic grain with the result that tectonic deformation has been designated a principal cause of mineralization. Variations in the type and intensity of deformation would determine the type as well as size of metal deposits. Mexico is especially favorable for such a study be- cause of its great abundance and variety of epi-genetic mineral deposits in various lithologic, structural and tectonic environments. The concept is also useful in recognizing portions of Mexico favorable for the occurrence of specific metals. METALLOTECTONIC ZONING IN MEXICO Theory: In studies of individual districts and groups of districts throughout North and South America, areal zoning of metal deposits generally seemed to respond to the paragenetic sequence of iron, gold, copper, zinc, lead, silver, antimony and arsenic, gold and fluorite. However, the definition of district zones is greatly obscured by contemporaneous or rhythmic deposition of metals, especially in the middle of the paragenetic range, and by the common superimposi-tions of different generations of metals. Zones could usually be distinguished only for groups of metals, such as early precious metals, base-metal sulfides, sulfosalts and late precious metals. The best defined zoning in a district is normally the spatial separation of the greatest volumes of altered and metallized rocks.' Exceptions are districts representing the high- and low-temperature extremes of the mineralization range where the former creates a matrix for the latter. In most districts the total quantity of alteration products is greatly in excess of, and appears to be roughly proportional to, the total quantity of metallization products. Subsequent to the bicomponent nature of each district, the most important mineralogical feature is the great excess of one to several metals or minerals which results in a district identifiable as one of predominantly gold, copper, lead-zinc, fluorite, etc., although a great variety of other elements may be present. The para-genetic range for the abundant elements in any district is only a portion of the entire possible range for all the elements representing the complete process throughout the region. Early during investigations of this type, it became apparent that the consistent bicomponent character of districts allows two methods for studying epi-genetic mineralization patterns. One is to identify and plot altered rock "pipes,"* which are easily recognizable in the landscape by their anomalous

Jan 1, 1969

By J. M. Hodge

This paper represents a start on the problem of choosing alloy steels for a given application on the basis of toughness as indicated by the room temperature notched bar impact value at the desired hardness level, and as such, is very useful. I believe, however, that the authors will agree that it is only a start on this problem. The authors state that neglecting temper brittleness or other possible effects of the tempering temperature level, the impact values at a given grain size level will be determined principally by the hardenability. This is, of course, true inasmuch as the hardenability determines the microstructure, but it serves to emphasize the broad field that hardenability now covers, since this study apparently includes mi¬crostructures ranging from full martensite to coarse pearlite. Furthermore, the + or - 20 ft-lb spread in the correlation with hardenability, which certainly limits the usefulness of these results for many applications, indubitably reflects the wide range of microstructures corresponding to a given value of hardenability in terms of the difference between full martensite and asquenched hardness.

Jan 1, 1947

By Charles H. Foreman, James F. McCarthy

The orebodies of the Hecla mine are from 3 to 40 ft. wide, dip not less than 70°, and in most cases are nearly vertical. The Hecla and Intermediate orebodies are generally associated with a lamprophyric dike, usually about 2 ft. wide, but which attains a maximum width of 7 ft. The ore appears on either or both sides of the dike. The country rock is Burke quartzite with no definite walls and a tendency for nearly horizontal, but irregular, quartz stringers to run from the lode into the walls. This latter condition prevails almost entirely in the hanging wall, causing a natural tendency for portions of the wall to "offset" and resulting in an extremely heavy side pressure. The fact that there are no definite walls causes a great variation in the width of the stopes, as stringers will run into the walls for irregular distances. The ore occurs as galena in varying widths and grades. It is often necessary to mine a face having a " horse"' of waste between two stringers of ore. This block of waste might be 6 or 7 ft. wide but with the Hecla method it is necessary to mine the entire face. In this case an effort is made only to shatter the waste, allowing for easy sorting underground. The Hecla mine requires a flexible system allowing for the extraction of ore from varying widths, with the necessity of close filling to give the needed protection from side weight. About 15' per cent. of the material broken in the face is sorted as waste, either at the face of stope, or in the sorting plant. Shafts, Drifts and Crosscuts The outside dimensions of the shaft are 19 ft. 4 in. by 7 ft. 2 in. The shaft consists of three working compartments, two for the hoisting of ore and one for auxiliary work. The working compartments are 5 ft. 2 in. by 4 ft. 4 in. inside measurement. The rest of the shaft is used for pump column, electric cables, and ladderway. (See Fig. 6 for framing of timbers.) The shaft is about 700 It. from the orebody for topographical reasons. Solid formation was not reached in shaft for 80 ft. Timbers in this section became alternately wet and dry on account of seasonal changes

Jan 1, 1925

By John V. Beall

The mining industry of Japan is not very large, but it is very old. Some of the mines have 1000 years of history. At Nara, the capitol 1300 years ago, the great Buddha of bronze that was cast at that time was of metal mined from several localities in Japan including the Akenobe-Ikuno district, one of the present Mitsubishi properties. Methods of smelting copper and iron, it is believed, came from China via Korea. A characteristic of the Japanese mining industry today is one of buying abroad and treating at home, a variety of ores of different compositions. All in all, Japan's mineral deposits under its own flag are inadequate for its great industrial strengths.

Jan 5, 1969

By A. Rosen, P. Wynblatt, J. E. Dorn

The temperature, strain rate, and structure dependence of the flow stress in a poly crystalline Fe-2 pct Mn alloy was investigated between 77" and 370°K. It was possible to identify the low-temperature data from 77° to 160°K with Dorn and Rajnak's theory of the Peierls mechanism of plastic deformation. Above 160°K one or more thermally activated mechanisms must he operative; however, these were not identified in this investigation. The mechanistic basis for the rapid decrease in the flow stress of bcc metals with an increase in temperature over the low-temperature range is yet being debated. Various dislocation mechanisms have been suggested in the past but the agreement between the various proposed theories and the experimental results have not been definitive. In the present paper, the authors will demonstrate that the plastic behavior of polycrystalline iron containing 2 wt pct Mn plus interstitials agrees excellently with predictions based on the Peierls mechanism from 77" to 160°K whereas from 160" to about 370°K other as yet unidentified thermally activated mechanisms take over. Undoubtedly, the overlap of these mechanisms with the Peierls mechanism contributed to the difficulties of rationalizing the low-temperature behavior of iron and its alloys. I) EXPERIMENTAL TECHNIQUES AND RESULTS Although extensive data are now available on the effect of temperature and strain rate on the flow stress of various bcc metals and alloys, it was, nevertheless, deemed necessary for the objectives of the present study to obtain highly accurate data of the type most pertinent for checking the theories on a series of well-documented work-hardened states. Iron containing 2 wt pct Mn was used in this investigation in order to obtain a lower ductile to brittle transition temperature than that for iron.' The additional elements present were 0.004 pct C, 0.05 pct 0, 0.004 pct S, 0.003 pct P, 0.006 pct N, and 0.001 pct Si. The as-received 3/8 by 3/4 in. bars were cold-rolled to 0.100-in. thickness, recrystallized under argon for 30 min at 1073"~, further cold-rolled to 0.063-in. thickness, and finally recrystallized under argon for 30 min at 1000°K. This treatment gave a stable reproducible equiaxed grain structure having an average grain diameter of about 90 p. Prior to the final recrystallization treatment, the sheet was machined into tensile specimens 1/4 in. wide having a 1.625-in.-long gage section. All specimens were tested in controlled-temperature baths on an Instron Testing Machine. For convenience in the theoretical analyses the data will be given in terms of the shear stress for flow, 7, the shear strain rate, f, and the shear strain, y. A series of three standard strain-hardened states were obtained by prestraining specimens at 300°K and at a shear strain rate of 7.68 x lo-' per sec to three stress levels of 6.89 X l08, 10.3 X lo8, and 14.5 x 10' dynes per sq cm, respectively. Immediately following this prestrain the temperature bath was changed and each specimen was pulled in tension at either f = 7.68 X lo-' or f = 3.06 X 10"3 per sec. In terms of the accuracy that was achieved, the values obtained did not deviate more than *0.1 X 10' dynes per sq cm and * 1°K from the reported values of stress and temperature and not more than *5 pct in the reported values of the strain rate. The tensile stresses were converted to shear stresses using a factor of 1/2. The shear stress for the initiation of flow at the test temperature was determined by taking a y = 6.16 x 10'3 offset. from the modulus line at which point good accuracy could be achieved in determining y and the associated flow stress 7, with only a negligible increase in the pre-

Jan 1, 1965

By P. Chiotti, J. T. Mason

Metallographic, thermal, X-ray, and vapor-pressure data were employed in establishing the Ce-Zn phase diagram. Nine compounds and three eutectics were observed. The eutectic compositions in weight percent zinc and temperatures are 10 pct and 495"C, 37 pct and 795°C, and 56 pct and 810°C. Three of the compounds, CeZn, CeZnn, and CeZne.5, melt congru-ently at 825°, 87.505°, and 980°C, respectively; the other six compounds, CeZns, CeZns.67, CeZn4.5, CeZn5.25, CeZn,, and CeZnll, decompose peritectically at 820°, 840°, 870°, 885", 960°, and 795"C, respectively. The compound CeZn5.25 is an AB5 type with a small range of composition which lies on the zinc-rich side of the 1 to 5 stoichiometry. Zinc vapor-pressure data obtained by the dewpoint method were employed in calczilating the thermodynamic properties of both the liquid alloys and solid compounds. The data for the A critical review of the information available on the Ce-Zn system up to 1960 has been given by K. Gschneidner, Jr.' Of particular interest is the work by J. schramm2 who investigated the region between 55 and 100 wt pct Zn and reported a CeZn,, compound which decomposes peritectically at 785"C, a CeZn, compound which melts congruently at 972"C, and five temperature horizontals at 79@, 817", 840", liquid alloys were fitted to the relation from which the relation was obtained by integration. In these relations F XS is the excess partial molal free energy, N is atom fraction, and the constants c and d have the values c = (-22,000 + 7.0T) and d = 6171,000 + 74.0T). Relations for the standard free energy of formation for the solid compounds were derived from the data. At 973°K the enthalpy in kilocalories per gram-atom z)aries from —11.3 for CeZnz to —8.21 for CeZn~l and the free energy in the same units varies from —7.1 joy CeZn, to -3.82 for CeZn11. and 942°C in the region between 55 and 75 wt pct Zn. No attempt was made to identify other features of the system. I. Johnson and R. yonko3 used a fused-salt cell to measure the electromotive force between pure cerium and an alloy consisting of zinc-rich liquid in equilibrium with CeZnll. Solubility data for cerium in zinc has been reported by J. Knighton et u1 .4 Johnson and Yonko give the following equa-. tions for the mole fraction of cerium in zinc and the standard free energy of formation of CeZnll:

Jan 1, 1965

By Helmut Thielsch

METALLOGRAPHIC specimens whose surfaces are to be investigated are too thick to allow either light or electrons to pass through them for microexamination by transmission. This difficulty is overcome with optical microscopes by illuminating the surface through the objective lens. For electron microscopes best results are obtained by preparing thin replicas of the surface of the specimen, placing them in the microscope and passing the electron beam through them. Since electron microscopes represent a rather recent invention, they have found little application as compared with optical microscopes. This is true because, aside from the cost of new equipment and development of new techniques, some of the older replica methods necessitated the destruction of the surface from which a thin transparent replica was obtained. In other processes in which the surface is preserved, either too tedious a procedure is required, unsuited to "mass-production " requirements of industrial laboratories, or replicas of insufficient contrast and sharpness are produced. In general, investigations with the electron microscope involve five steps: (I) polishing the surface of the metal specimen, (2) proper etching of the surface, (3) preparing the suitable replica from the surface, (4) examination and photography in electron microscope and (5) interpretation. PREPARATION OF METAL SURFACES Usual metallographic polishing is generally satisfactory. It is important though that the final polish be applied very care- fully, since otherwise evidence of a small amount of deformation might show up even on relatively deeply etched surfaces. A high-power microscope should be used to determine the suitability of the polish and etch. This, of course, is not different from optical examinations, but in these, if a deep etch is used, the problem is less serious. It is frequently difficult to detect with optical microscopes poor polishing aside from superficial scratches before etching. Figs. I and 2 show micrographs of "well" and "poorly" polished nickel etched by immersing the same for 20 min. in a solution containing 8 grams cupricsulphate in 40 C.C. of concentrated HCl and 40 C.C. of H20 (Marble's reagent). The sample shown in Fig. I was polished in its final stages for 5 min. on a carborundum wheel followed by 10 min. on a rouge wheel, whereas the sample shown in Fig. 2 was polished only I min. on the rouge wheel. Generally, this procedure does not guarantee that the surface of the specimen will be either undistorted or deformed. It was applied here merely to show the effects of good and poor polishing. To the experienced investigator, plastic deformation is

Jan 1, 1946