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By Will H. Coghill, Fred D. DeVaney, R. G. O’Meara

The size of ball mills in the ore-dressing industry has increased from about 4 ft. in each dimension to 10.5 ft. in diameter by 8 ft. in length. In the cement industry they are as long as 45 ft. Plainly the trend has been toward larger mills. The common belief is that the big mills economize in floor space and first cost, but the advantage with respect to friction has not been clearly defined. In the ball-mill studies at Rolla, Mo., laboratory mills as small as 2 by 2 ft. have been found as efficient in terms of the amount of grinding per unit of net power as mills 6 by 4 or 6 by 12 ft. Therefore, if supremacy can be claimed for the big mills, advantage must come from other sources. The advantage to be considered here is reduced loss by friction or dead load. In the study to determine whether big mills have relatively less loss by friction the commercial catalogs were used for fundamental figures. The dimensions and weights of Table 1 are taken from the catalogs (the last line gives data on a Rolla laboratory mill). The net power—that is, the power expended within the mill for grinding—is calculated by a new formula.' The assumed speeds are each at 70 per cent of their theoretical critical speeds, and the mills are loaded to the center with balls. In other words, they are assumed to be working under analogous conditions and are set for good grinding. In the last column the ratio B: A shows that the larger commercial mills are lighter per unit of net power than the smaller mills, and more of the motor output should therefore go into grinding. The laboratory mill seems to have some advantage over the larger mills; it would be expected to be light because it has no liners.

Jan 1, 1935

By L. A. Morley, W. T. Parry

Engineering design problems encountered by mining engineers often depend on the properties of natural granular materials such as soil, poorly consolidated sediment, fault gouge, and hydrothermally produced clay. The physical properties of such granular materials frequently are determined by the properties of silicate clays. In most mining applications, the clays are in contact with water. Swelling of clay due to water infiltration can interfere with underground support and haulage systems. Water-saturated clay on fault, fracture, and bedding planes causes slope failures in open pit mines, roof falls and heaving of weak underclays in coal mines. Water may be removed and cementing agents may be produced in clays by electrical methods. When an electrical potential gradient is applied to a charged capillary by two electrodes, water moves toward the negative electrode.1 This electrokinetic phenomena is known as electroosmosis and has been used to successfully dewater clay minerals which lack strength because of water. A consolidation effect occurs when the flow of water is accompanied by a decrease in water content. Electrochemical changes in the clay result in cementing and irreversible hardening. Theory A mathematical basis of electroosmotic phenomena is presented by Helmholtz.3 Smoluchowski5 modifies Helmholtz’ model and presents Eq. 1 to describe fluid flow velocity due to electroosmosis. For this formula, the zeta potential can be measured experimentally. The Helmholtz-Smoluchowski model is reasonably valid for clay aggregates with large pores saturated with fresh water or dilute electrolyte solutions.° An assumption used for Eq. 1 (equations are given Table 1; terms are defined in Table 2) is that the thickness of the electrical double layer surrounding the clay particles is small compared with the pore radii. Because this is generally not the case, Schmid7 presents Eq. 2. The volume charge density in the pore may be approximated from cation exchange capacity and porosity measurements. Casagrande8 offers a semi-empirical relationship (Eq. 3) for volume rate of electroosmotic flow and finds that k, is relatively constant for most clays with an average

Jan 1, 1972

THERE are many kinds and varieties of earth* that are used for the loam compositions for making the moulds for casting bronze, brass, or other metals. Since this is a very necessary thing, you must try to have the best kind and one that resists the fire well. It must be disposed to receive the metals well, must make a neat casting, and must not shrink or break with cracks on drying or baking. Aside from actual trial, I believe that there is little that can help you, since the clay in itself has no color or [77] visible sign that I know of to show how satisfactory it is. Understand that their colors are no less varied than their natures, for, as you see, one is white, one black, one yellow, and another red. Perhaps none will show by its color that it is good for this work, yet it might also happen that all colors are good. But all that I can say about it is to show you by their effects how the good ones should be in their nature; and so by trial you will choose among those that come into your hands. All earths are either sandy or tufaceous, either argillaceous and lean or pasty with unctuous viscosity. The lean ones make the loam powdery and without toughness and hold together poorly by themselves when they are dry. The unctuous and viscous ones shrink and break. Becoming smaller by shrinking, they often twist the forms and they stick together badly. They swell up again in the fire and produce works that are neither exact-a nor neat. Therefore, the good ones must be those that are neither unctuous nor lean, neither wholly tender nor rough, and with a grain that is fine, without pebbles or shells. When applied to a work they easily dry out without fractures and, when dry, hold their own shape well. Above all they must resist the fire well. These are usually of a yellow or red color, but whatever their color may be, the color does not force me to say that the yellow are really better than the black, and the red than the white or gray. Their quality depends on what trial shows. Thus, to summarize, whenever you have to do this work, you must try to have the best clay that you can, because it is to be the foundation of

Jan 1, 1942

By G. B. Gibbs

Equations are developed which describe the growth of graphite nodules during a-phase graphi-tization under various limiting conditions. When carbon diffusion is rate controlling a modified Birchenall-Mead equation predicts an "apparent activation energy" of 31 keal mole-1 for the parabolic growth constant. If reaction at the graphite or cementite interface is the slowest process growth kinetics are linear and the activation energy must be >50 keal mole-1. A comparison with the experimental observations confirms that carbon diffusion determines the rate of reaction. Apart from minor approximations associated with Lou! carbon solubility in a iron the theory may also be applied to I-phase graphitization. It is well-known that cementite exists as a meta-stable phase in Fe-C alloys and that if a specimen is held at diffusion temperatures for a sufficiently long period the cementite decomposes and graphite is precipitated. Graphitization occurs by the nu-cleation and growth of carbon nodules and several impurity elements catalyze the reaction when present in minute amounts.1 The growth kinetics of nodules have been extensively investigated in the fee ? range2, 3 and recently in the bee a range.1, 4 Experimental growth curves (nodule radius vs time) have slopes which decrease with time, but the scatter of points is generally too great for the precise shape of the curves to be determined with certainty. Birchenall and Mead5 concluded that they are parabolic in ? iron, indicating diffusion control, and that the migration of carbon atoms determines the growth rate. Harris et al, 1 advanced similar ideas for a-phase graphitization. On the other hand, Burke3 chose to regard the initial growth region as a transient followed by a linear law indicating interface control (i.e., cementite decomposition or graphite crystallization as the slowest process). Jeminson and Higgins6 originally considered the initial steep portions of "parabolie" to represent a linear growth law also. In support of these ideas it has been noted that the apparent ac-

Jan 1, 1965

By Falih Ergunalp

REGULAR production of chrome in Turkey started in 1860 with the operation of the Bursa deposits (5, Fig. I). Others were discovered at Makri, near Fethiye (3, Fig. I). For 33 years Turkey remained the principal source of this mineral. While new discoveries were coming in elsewhere, Turkey's output declined until 1921, as a result of four successive wars, which ruined the economics of the country. In 1927 a revival came with the production of 18,000 tons. In that year the Société Minière de Fethiye was formed. This company now operates mines in the Vilayets of Aydin, Denizli, Burdur and Mentese, and it has reached a maximum production of between 80,000 and 90,000 tons annually. The Turkish output therefore increased from 29,000 tons in 1930 to 55,000 tons in 1931; and to 119,009 tons in 1934. The second phase in the increase in chrome production in Turkey came about in 1935, when the Government decided to reorganize and control the mineral industry of the country according to the principles of "government control" of the present regime. Up to that time the mineral resources of the country had been exploited by private concerns. In 1935, the M.T.A. (Maden Tetkik ve Arama) Institute (Institute of Mining Research and Geological Survey) was established by the Government to do the geological and geophysical survey work and discover new mineral resources for the country. Before the establishment of the M.T.A. Institute, the chief chrome-producing region was Fethiye (3 and 4, Fig. I). As a result of the extensive work of this bureau, many new chrome deposits have been discovered and are now in production. The operational field of the mineral industry was given to Eti Bank, another Government-sponsored and Government-controlled establishment. Eti Bank gradually took over the exploitation of existing mines by purchasing them from privately operated companies. Attention was first given to the Zonguldak collieries and to the different chrome deposits scattered over the country. The Guleman mines (14, Fig. 1) were developed and put in operation in 1936. Since then the bulk of Turkish chrome output has come from this mine, which yields the highest grade ore in the world (averaging 52 per cent Cr2O3). In 1939, the recently discovered chrome deposits to the north of Eskisehir went into production, yielding ore having a Cr2O3 content of 51 to 52 per cent. Today, more than ever, the efforts of both the M.T.A. Institute and the Eti Bank are concentrated on finding new deposits and placing them in operation. There are still many promising regions of the country that merit systematic surveying and prospecting for chrome ores. Thus it is probable that Turkey will continue to make noteworthy progress in chrome output. As the annual chrome production of

Jan 1, 1944

By Jose M. Sobral

The approximate production of petroleum in the various fields and for the country as a whole is shown in the following table, the figures for the later months of the year being estimated. Among the developments of the year may be mentioned the finding by the Standard Oil Co. of a small production, about 6290 bbl., at Aguas Blancas in the Province of Salta near the Bolivian border, and of about 88,000 bbl. at Lomitas, near Tartagal in the same province. The Government (Yaciementos Petroliferos Fiscales) in the last four months of the year also obtained about 6290 bbl, from Quebrada Galarce. .The oil found in Salta is of good grade and while the quantity is small great hopes of larger production are entertained. Approximate Total Argentine Production for 1928 Barrels Barrels Comodoro Rivadavia............................... 8,165,615 Plaza Huincul..................................... 783,514 8,949,129 Distribution of Production Government, Comodoro Rivadavia................... 5,165,159 Government, Plaza Huincul......................... 306,166 5,471,325 Private, Comodoro Rivadavia....................... 3,000,456" Private, Plaza Huincul............................. 477,348b 3,477,804 a The companies represented are Astra, 649,474 bbl.; Oriente, 42,237; Ferrocar-rilera, 1,337,380; Comp. Indust. y Comm., 609,092, Solano, 64,158; Diadema, 298,114. b Standard Oil Co. and a few smaller companies, Exploratory drilling has also been conducted around the Comodoro Rivadavia field. The Government is drilling at Vuela del Senguer south of Colonia Sarmiento and about 200 km. west of the main field hut the prospect of success is not as yet large. The country around Castillo, where the Royal Dutch Co. has property, is regarded more favorably. perhaps the most interesting event of the year was the discovery of a productive horizon at Comodoro Rivadavia about 200 m. below that previously exploited. This new horizon was found by the Ferrocarrilera Co. at 769 m. in its well No. 81, the previous yield for this

Jan 1, 1929

By J. Campbell

Long freezing range casting alloys are particularly susceptible to a type of porosity which is observed to form in layers parallel to the supposed position of the isotherms in the solidifying casting. Under favorable conditions (which appear to be typified by low-temperature gradients in the casting giving rise to a wide and more or less uniform pasty zone, and which arise from several factors, particularly: a) wide freezing range alloy, b) high thermal conductivity of metal, c) low thermal conductivity of mold, and d) high mold temperature3) layer porosity has been observed in many different casting alloys: copper,' aluminum, magnesium,' steels, and high-temperature alloys.3 Baker4,5 and later cibula6 argue that layer porosity occurs because of thermal contraction, in a manner analogous to hot tearing. In outline, the theory consists of the establishment of a coherent dendrite network by the impinging of dendrite tips. Subsequent shrinkage imposes tensile stresses on the network which tears perpendicularly to the stress, i.e., parallel to the isotherms. If these tears are not filled by the inflow of residual liquid then layers of porosity result. Baker7 attempted to test whether the porosity was the result of thermal contraction by casting test pieces in a mold designed to accentuate hot tearing. However, no significant increase in porosity was observed. This negative result of Baker's critical experiment appears to be substantiated by numerous observations, particularly the experiments by Lagowski and Meier8 on Mg-Zn alloys covering the range of zinc contents up to 30 pct Zn. These clearly reveal that the maxima for the incidence of hot tearing and layer porosity are well-separated, occurring at 1 and 6 pct Zn, respectively. Furthermore, the thermal contraction maximum occurred at 1 pct Zn, indicating that hot tearing is associated with contraction in the solid state, and not with porosity. These observations are further substantiated by the elementary consideration that the thermal contraction of the casting is likely to produce (if anything, since the temperature difference across casting of high thermal conductivity, such as aluminum and copper, is likely to be negligible) a compressive stress on the

Jan 1, 1969

By W. L. Finlay

Size effects in quenching steel are particularly prominent and well recognized because of the existence of a critical cooling rate separating nuclea-tion and growth transformations, as exemplified by the formation of pearl-ite, from the shear type of transformation characterizing the martensite reaction. The absence of a similar, sharply demarcating cooling rate is characteristic of precipitation hardening systems and size effects in these are correspondingly less prominent. This paper is concerned with a size effect in high-purity, precipitation-hardenable alloys which appears not to have been recognized previously. This effect is believed to result from the thermal fluctuations which inevitably occur in quenching a specimen of finite size into a cooling liquid rather than from the existence of a critical cooling rate. QUENCHING "ANOMALIES" The precipitation hardening literature contains many references to so-called anomalous quenching and aging results. By "anomalous", investigators usually meant that their alloys did not consistently harden on aging after quenching according to some anticipated pnttern: not infrequently virtually no age hardening occurred with compositions known to be precipitation-hardenable. Perhaps the most prominent series of anomalies was reported over a 15-year period by Gayler and coworkers on aluminum-copper.l,2,3,4 Working with silver-rich copper alloy, Cohen5 secured some very interesting Rockwell F hardness changes of from 1-5 Rockwell points between the first peak and valley. Fink and Smith borrowed one of Cohen's specimens and, following his heat treatment and quenching practice to the letter, secured6 very different results in which only one peak was obtained and in which the hardness level at the aging lime of Cohen's first peak was 20 Rockwell F points higher. Fink and Van Horn7 encountered serious deviations in age-hardening high purity aluminum-zinc alloys. They stated that "the discrepancies were larger than might be expected from possible experimental errors in the Brinell readings." Geisler, Barrett and Mehl8 likewise encountered anomalous hardening results in aluminum-silver alloys, securing quite different age-hardening curves from two identical specimens. They stated that "the treatments of these samples had been the same, so that the different behaviors could be attributed only to accidental variations in the quenching practice."

Jan 1, 1950

By Alexander Squire

One of the principal factors that have contributed to the hesitancy of design engineers to use metal-powder parts is the difficulty experienced in the determination of the mechanical properties of compacted components. Because standard test methods cannot usually be applied in the inspection of such parts, and because adequate special test methods have not been developed, it has been considered desirable to investigate the methods that are applicable. These may then be included in specifications for metal-powder materials and components in order that the design engineer may be assured that the subject parts possess the desired mechanical properties for satisfactory performance. It is known that direct relationships exist between usually nonmeasurable properties as tensile strength and elongation and shear strength and the angle through which compacts may be plastically deformed before fracturing. These correlations are valuable in the inspection of specific parts, but it is necessary to set up standards before they may be satisfactorily employed. Apart from the use of correlations, the number and character of the inspection methods that are applicable to almost all powder parts is limited to three—chemical analysis, density, and hardness. The last of these may or may not be a pertinent characteristic, since the indentation hardness of many powdeied-metal materials is so low as to have little significance. It is, however, occasionally desirable to use hardness measurements as an indication of the uniformity of the structure of pieces of a given type. Chemical analysis reveals very little about the physical properties of metal-powder compacts, since the unpressed powder is usually of a composition almost identical with that of the finished pieces. Density determinations are simple to perform and have the advantage of being nondestructive in character. If the dimensions of a machine part are known (and usually they are), the average density may be determined by weighing a given number of pieces and dividing by the calculated volume of the parts. More accurate measurements may be made by the water-displacement method. It is recognized that mechanical properties of metal-powder materials are related to their density, but usually these relations are determined for only one type of powder, processed under a given set of conditions. Comparisons of the pioperties of compacts formed from different types of powders are made on the basis of compacting pressures instead of density, and for this reason the results obtained by using powders of different types appear widely variant.

Jan 1, 1947

By Alexander Squire

One of the principal factors that have contributed to the hesitancy of design engineers to use metal-powder parts is the difficulty experienced in the determination of the mechanical properties of compacted components. Because standard test methods cannot usually be applied in the inspection of such parts, and because adequate special test methods have not been developed, it has been considered desirable to investigate the methods that are applicable. These may then be included in specifications for metal-powder materials and components in order that the design engineer may be assured that the subject parts possess the desired mechanical properties for satisfactory performance. It is known that direct relationships exist between usually nonmeasurable properties as tensile strength and elongation and shear strength and the angle through which compacts may be plastically deformed before fracturing. These correlations are valuable in the inspection of specific parts, but it is necessary to set up standards before they may be satisfactorily employed. Apart from the use of correlations, the number and character of the inspection methods that are applicable to almost all powder parts is limited to three—chemical analysis, density, and hardness. The last of these may or may not be a pertinent characteristic, since the indentation hardness of many powdeied-metal materials is so low as to have little significance. It is, however, occasionally desirable to use hardness measurements as an indication of the uniformity of the structure of pieces of a given type. Chemical analysis reveals very little about the physical properties of metal-powder compacts, since the unpressed powder is usually of a composition almost identical with that of the finished pieces. Density determinations are simple to perform and have the advantage of being nondestructive in character. If the dimensions of a machine part are known (and usually they are), the average density may be determined by weighing a given number of pieces and dividing by the calculated volume of the parts. More accurate measurements may be made by the water-displacement method. It is recognized that mechanical properties of metal-powder materials are related to their density, but usually these relations are determined for only one type of powder, processed under a given set of conditions. Comparisons of the pioperties of compacts formed from different types of powders are made on the basis of compacting pressures instead of density, and for this reason the results obtained by using powders of different types appear widely variant.

Jan 1, 1947

By C. S. Barrett, C. T. Haller

TWINNING in magnesium is known to occur profusely under certain conditions, and when it occurs in polycrystalline materials it brings about a partial or even a complete change in the preferred orientation. The amount of research on this subject, however, has not been in proportion to its importance as a mechanism of deformation and reorientation. Much of the research has been limited to twinning in single crystals. The present study' concerns polycrystalline sheet, and is an investigation of the twinning produced by plastic deformation as a function of the following variables: I. Direction and type of deformation. 2. Amount of deformation. 3. Speed of deformation. 4. Temperature of deformation. 5. Composition and temper of the sheet. 6. Twins previously produced. 7. Twins previously produced, then annealed. By proper control of these variables it is shown that, on a laboratory scale, samples can be produced that are free from preferred orientations. MATERIALS AND METHODS The materials used were samples of commercial magnesium-alloy sheets with nominal compositions given in Table I. [ ] X-ray diffraction was used in most of this work to detect the twins and to estimate the amount of twinning. Since twinning on {102} planes causes a reorientation of the crystal lattice by 86°, it is very easy to study with X-ray diffraction patterns, particularly if one notices the diffraction ring from the basal plane the 002 reflection. By properly directing the X-ray beam, it is possible to produce 002 reflections from twinned material at, say, the 6 and 12 o'clock positions on the 002 ring, with the untwinned material reflecting to 3 and 9 o'clock positions; and by judging the relative intensity of the arcs on the diffraction ring at these positions, it is possible to judge the amount of twinned material relative to the untwinned. This X-ray method of estimating the amount of twinning is generally superior to metallographic observation, for it was found

Jan 1, 1946

By J. B. Austin

IT is now well established, chiefly through the work of Davenport and Bain,1 that the influence of temperature upon the rate of transformation of austenite to ferrite at constant temperature is represented by a curve of the type shown in Fig. 5 of Tech. Pub. 589; and the reasons for this general shape have been discussed by them in a qualitative way. Thus, the upper part, or nose, of the curve is the resultant of two factors of which the rate of change with temperature is not the same, and by analogy with other like cases it is almost certain that these factors are: (1) the chemical potential, or driving force, of the transformation, which is zero at the equilibrium temperature and increases rapidly as the temperature falls below this point; and (2) a factor analogous to viscosity, or resistance of the crystal lattice to a change in structure, which also increases as the temperature is lowered. Just below the equilibrium temperature this virtual "viscosity" of the metal is relatively low-that is, the metal offers little resistance to a change in lattice-but the driving force is also small, and the net result is that the reaction proceeds slowly. As the temperature is lowered the magnitude of both factors increases; but at first the driving force increases more rapidly than the resistance and the reaction is observed to proceed more rapidly. At lower temperatures, however, the resistance begins to increase faster than the driving force, and eventually, at the nose of the curve, overbalances it, causing the reaction to proceed more and more slowly thereafter. This concept is somewhat, though not completely, analogous to that employed in certain electrical cases where the precise factors are known and are separately measurable. The current I (in amperes or coulombs per second) flowing through a given wire is proportional to the impressed potential, or driving force E, and is inversely proportional to the resistance R of the wire; that is, I = E/R. Stated in a slightly different way,

Jan 1, 1935

By Maurus Seet

Mainland China, with one-fourth of the world's population and one-tenth of its coal production, can no longer be ignored as a considerable force on the world energy scene. In terms of annual productivity, China's 300 million tons of coal rank third behind the Soviet Union with 655 million and the United States 557 million (1968 Minerals Yearbook. USBM). When viewed from another angle, 1967 figures show that increased productivity from all coal-producing continents, with the exception of North America, was led by Chinese-dominated Asia with a 19% gain. Not unpredictably though, China, on a per capita basis, is closer to the bottom of the list among members of the industrial community. Despite its misspent youth, and despite the set- backs caused by the Big Leap Forward of the late 50's and the Cultural Revolution of the late 60'S, the People's Republic has managed to make some impressive strides in developing its coal industry over the past twenty years.

Jan 1, 1971

By E. Clarence Peterson, Rip V. Thompson

ALTHOUGH the metallurgical treatment for the Ophir Hill tailings was developed more than 20 years ago and in the interim a vast amount of experimental work was done with later-developed flotation reagents, it was found necessary to revert to the original oil reagents and their combinations with specific chemical reagents in order to obtain results of economic value. This is of especial interest because in present ore-treatment investigations later-developed flotation reagents are used almost exclusively and the coal-tar derivatives, except in certain patented reagents, are virtually neglected. These coal-tar oils and derivatives still have a definite field of application, especially in the treatment of some oxidized ores when modified sulphidization is desirable. The Ophir Hill tailings deposit is in Ophir Canyon, Tooele County, Utah, about 55 miles southwest of Salt Lake City and 25 miles south of the Tooele smelter of the International Smelting and Refining Co. A road good for trucks leads directly from the Ophir mill to the smelter. TAILINGS These tailings were produced in the old Ophir Hill gravity concentrator previous to 1921. The original mill ore was a heavy lead-zinc-copper-silver-iron sulphide ore formed by limestone replacement. The gangue is a highly siliceous lime. An assay of the original milling ore would approximate 1.0 per cent Cu, 6 to 8 per cent Pb, 6 to 8 per cent Zn, 8 to 12 oz. Ag, 18 to 25 per cent Fe, 2.0 per cent CaO, 20 to 5o per cent insoluble. The gold content was 0.005 oz. or less. Tailing was impounded in a fairly wide area in a canyon about ½ mile below the mill. A number of dirt embankments were thrown up to form settling ponds and the tailing was allowed to flow through them in series. Coarser sand deposited at the upper end of the ponds and the finer slimes settled gradually as they passed through the successive settling ponds. As soon as the coarser tailings filled a pond, the tailings were by-passed to the next pond and teams and scrapers were used to haul the deposited sand onto the banks to make them higher. The final dump was approximately 2500 ft. long and 250 ft. wide at the bottoms, with banks sloping up at 45°. The coarser sands predominated at the upper ends and sides of the ponds while the proportion of slimes increased steadily at the lower ends. The lower end of the pond contained over 50,000 tons of slime tailings, 90 per cent of which passed through a 200mesh screen. SAMPLING The entire tailings deposit was sampled by drilling vertical holes so placed as to give data concerning size segregation and the contour of the underlying ground as well as to secure an assay sample. Different types of auger and post-hole drills were tried. None was found satisfactory because the stratified layers of

Jan 1, 1940

By Yang Tsang Woo

I will endeavor to describe the methods of silver-mining and smelting employed by the natives in Mongolia. Modern methods have been applied there, but with little success; and, since they are familiar to most members of the Institute, I will simply mention that the failure was due to the high price of coke used in smelting the ore in modern furnaces, and to the unsuitable mill-machinery employed for concentrating the galena, which is finely distributed in the ore. The Jehol silver-mines are situated about 45 miles NE. of Jehol, the capital of Mongolia. They embrace two mines, 5 miles apart,—the Ku Shan Tze mine and the Yen Tung Shan mine. They were first worked by natives 50 years ago, about the time when mining was so flourishing in other parts of the world,—for instance, in California and Australia. The upper part of the vein is galena mixed with iron-stone, and is 2 to 4 ft. thick. At lower levels the vein is composed of silver-lead ore running between quartz-porphyry walls. Limestone, talc and black shale, colored by graphite, are found in other parts of the mine. Crystalline limestone is found 1 mile NE. of Ku Shan Tze. Granite is encountered in the Yen Tung Shan mine. Mining.—The native method of working the mines is most primitive. The same method may have been employed a thousand years ago. A small inclined shaft, 4 ft. by 4 ft., is sunk in the vein-stuff where the appearances are most favorable. Another shaft is sunk 20 or 30 yds. away, for ventilation. The shaft follows the vein in a zigzag fashion in whatever direction the vein appears to be richest. Timber is used only in soft ground. Where the ground is hard, the roof is cut into an arch-form. In some places, instead of using ladders, steps are cut in the rock, just wide enough to hold one foot. The deepest native workings are 400 ft. below the

Jan 1, 1903

By John Johnston

When I was honored by being invited to give the Howe Memorial Lecture, I decided to read Howe's book, "The Metallography of Steel and Cast Iron," published in I9I6—that is, about 25 years ago—in search of a text. I found the book written in fine, clear, attractive, yet precise style, as I expected, knowing that his father— Dr. Samuel Gridley Howe, his mother— Julia Ward Howe, and all of his four brothers and sisters had lived in a New England literary atmosphere and had written books. This leads me to suggest that many authors of metallurgical papers and books could well study Howe's writings with a view to the improvement of their own. I failed to find a specific text, but did find a subject, for in reading his book I was struck by the few instances in which time is considered explicitly as a factor in the phenomena examined, and by the fact that many of the hottest arguments would have been settled had time been taken properly into account. Indeed, Howe hardly mentions time except in a rather incidental way, as in a few references to lag; for instance: The lowering of temperature at which the transformation occurs by rapid cooling . . . is a phenomenon of undercooling or lag. It is in part explained by the fact that the transformation itself is a time-consuming reaction which, setting in during a rapid fall of temperature, is naturally protracted till the temperature has sunk far below that at which it is due. He does discuss, quite fully, the iron-clrbon equilibrium diagram, as known at that time, introducing it by stating: As he is a reasonable man who is not deterred from using a hand truck for moving his trunk by the consideration that he has thus to move a trunk plus a truck, so am I reasonable in putting into your hands this useful, indeed indispensable. tool for mastering the ABC of iron metallurgy. Somewhat later, in introducing a discussion of the phase rule, which "it would be hardly proper to pass ... by without an attempt to outline its meaning," for "a clear exposition of its applicability or jurisdiction is needed to restrain the half-initiated from misusing it and the uninitiated from being misled by these misuses," he writes—and I quote his statement because we cannot properly discuss the influence of time on a process until we know the state of equilibrium which would ultimately be reached by the system under consideration: It is a most remarkable and valuable generalization, its conceptions help greatly toward getting a broad outlook on metallography, but its misconception has brought out a flood of obscuring writings. it tells us about the constitution towards which alloys tend, that which they reach when equilibrium is complete, when all tendencies have corrected themselves and have been complied with completely. Its application, in absence of true equilibrium, is like determining density with a telescope or even with a tuning fork; it is like the mad tea party at which the butter put into the works of the watch was the best butter. If the reader learns no more than to beware of attempts to dccipher the conditions of inequilibrium by a law which touches only the conditions of exact

Jan 1, 1942

By John Johnston

When I was honored by being invited to give the Howe Memorial Lecture, I decided to read Howe's book, "The Metallography of Steel and Cast Iron," published in I9I6—that is, about 25 years ago—in search of a text. I found the book written in fine, clear, attractive, yet precise style, as I expected, knowing that his father— Dr. Samuel Gridley Howe, his mother— Julia Ward Howe, and all of his four brothers and sisters had lived in a New England literary atmosphere and had written books. This leads me to suggest that many authors of metallurgical papers and books could well study Howe's writings with a view to the improvement of their own. I failed to find a specific text, but did find a subject, for in reading his book I was struck by the few instances in which time is considered explicitly as a factor in the phenomena examined, and by the fact that many of the hottest arguments would have been settled had time been taken properly into account. Indeed, Howe hardly mentions time except in a rather incidental way, as in a few references to lag; for instance: The lowering of temperature at which the transformation occurs by rapid cooling . . . is a phenomenon of undercooling or lag. It is in part explained by the fact that the transformation itself is a time-consuming reaction which, setting in during a rapid fall of temperature, is naturally protracted till the temperature has sunk far below that at which it is due. He does discuss, quite fully, the iron-clrbon equilibrium diagram, as known at that time, introducing it by stating: As he is a reasonable man who is not deterred from using a hand truck for moving his trunk by the consideration that he has thus to move a trunk plus a truck, so am I reasonable in putting into your hands this useful, indeed indispensable. tool for mastering the ABC of iron metallurgy. Somewhat later, in introducing a discussion of the phase rule, which "it would be hardly proper to pass ... by without an attempt to outline its meaning," for "a clear exposition of its applicability or jurisdiction is needed to restrain the half-initiated from misusing it and the uninitiated from being misled by these misuses," he writes—and I quote his statement because we cannot properly discuss the influence of time on a process until we know the state of equilibrium which would ultimately be reached by the system under consideration: It is a most remarkable and valuable generalization, its conceptions help greatly toward getting a broad outlook on metallography, but its misconception has brought out a flood of obscuring writings. it tells us about the constitution towards which alloys tend, that which they reach when equilibrium is complete, when all tendencies have corrected themselves and have been complied with completely. Its application, in absence of true equilibrium, is like determining density with a telescope or even with a tuning fork; it is like the mad tea party at which the butter put into the works of the watch was the best butter. If the reader learns no more than to beware of attempts to dccipher the conditions of inequilibrium by a law which touches only the conditions of exact

Jan 1, 1942

Transit A light weight, totally enclosed theodolite, especially designed for mining, has been placed on the market by Askania Werke, A. G. The instrument weighs only 41/4 lb and measures 51/8 x 71/2 in. without tripod and in a waterproof aluminum hood. It may be mounted on tripod or bracket without removing the protective hood. [ ] Standard equipment includes diagonal eyepiece rotating in all directions which eliminates need to be in line with scope for sighting and makes an auxiliary scope unnecessary for steep sights. The transit reads direct to 1 minute and may be estimated to 6 seconds by means of optical micrometer on both horizontal and vertical circles. The telescope in vertical position serves as optical plummet, sighting through an opening in the base. The instrument is shown above mounted for attaching to a pin driven in timber or rock, eliminating tripod or set-up bar in cramped quarters. The chain clamp in the lower picture is used on timber or steel ground supports. Complete with carrying case and set-up brackets, ready for use in a raise, it weighs less than 6 lb, and the protective hood remains on until the instrument is securely mounted. [ ] Accessories for increasing versatility of this mining theodolite are: tripod, electric illumination for optical micrometer and reticule, close range objective lens, and objective lens prism for sighting vertically in front of the instrument. Circle No. 1

Jan 1, 1952

By P. Rama Rao, D. H. Sastry, T. R. Anantharaman

Deformation (a) and twin (a') stacking-fault densities in cold - wor ked filings of fcc silver alloys containing 2, 4, and 6 wt pct Sb have been estimated from Debye-Scherrer peak shifts and asymmetries, respectively. Evidence has been obtained for a possible strain-induced transformation in a two-phase alloy containing 9.0 zut pct Sb. Using Fourier analysis of X-ray line profiles, the effective particle sizes and root mean square strains have been determined for the three fcc alloys in the cold-worked condition. The values of the compound fault probability 0.5a + a') evaluated from peak shifts and asymmetries are in reasonable apeement with those derived from peak broadening. COLD work of fcc metals may produce both deformation and twin (also called growth) stacking faults, which can be detected and quantitatively estimated by X-ray diffraction techniques.' In addition to peak broadening, deformation faults produce a shift in peak positions and twin faults an asymmetry of the Debye-Scherrer reflections. Besides stacking faults, a reduction in the size of coherently diffracting domains and distortion within these also broaden the powder reflections of deformed fcc metals and alloys. Fourier analysis' of peak shapes provides quantitative infor- mation about the effective domain sizes, lattice strains, and also the compound fault probability (1.5a + a'), where a and a' represent deformation-and growth-fault density, respectively. The Paterson method2 for determination of a from peak shifts, the warren3 or wagner4 method for evaluation of a' from peak asymmetries, and the Fourier analysis for quantitative estimates of all the contributory causes of peak broadening have, in the course of the last decade, been extensively applied to obtain data for a number of deformed fcc metals and alloys. One of the useful results of earlier measurements of a in several solid solutions is a correlation between a and the solute valence as well as electron concentration per atom (p) in alloy systems based on a particular solvent. The work of Smallman and westmacott5 on Cu-Zn, Cu-A1, and Cu-Sn, of Foley, Cahn, and ~aynor' on Cu-Si and Cu-Ge, and of Rama Rao and Anantharaman7 on Cu-Si and Cu-Sb has revealed a common trend in the increase of a with p and also a with valency of the solute. Cahn and Davies' and Ad-ler and wagnerg have observed similar trends for silver alloys containing cadmium, indium, and tin. Data on a for silver alloys with a pentavalent solute element are not, however, available. It is primarily to fill this need that the present investigation on Ag-Sb alloys was undertaken. Utilizing the Patersonand Warren methods, values of a and a', respectively, have been determined in three silver alloys containing 2, 4, and 6 wt pct Sb. By Fourier analysis of the broadening of Debye-Scherrer peaks, effective particle sizes, lattice strains, and the compound fault probability (1.5a +a') have also been evaluated.

Jan 1, 1967

By William Metcalf

William Metcalf, Pittsburgh, Pa. : In rising to discuss Dr. Dadley's paper, I feel somewhat as I did at the Baltimore meeting —that a "crucible" man has no right to interfere in a "Bessenier" discussion; yet having read the paper very carefully, I feel impelled to say something, for two reasons: First, because I believe Dr. Dudley is entirely on the right and having undertaken and partly accomplished a great work, he .is entitled to the help of all who have experience in these matters; and second, because the data given force me to colicur in Captain Jones's opinion that the analyses are incomplete, since they ignore sulphur, copper, nitrogen, and possibly other injurious elements. In an experience of fourteen years, and with probably more than a hontlwl tests, we have never found the chemistry and the of crucible steel to disagree. If in any cave a disagreement tins sp- . peared, it has been our invariable custom to go over all our physirtal testa with great care, and if we found no error, then to refer the matter back to the cherubt, who has invariably found some unexjmted element to account for the trouble. It is only just to the chemist to say here, that ordinarily be is only expected to determine phosphorus, silicon, sulphnr. Generally the metals, with the exception of manganese, are not looked for, although a watch is usually kept for copper and arsenic. Further, in most cases we have found our own work more liable to be faulty than the chemist's. Having arrived then at such a degree of experience that we can preJict the analysis from our tests, or our tests from the analysis, with almost absolute certainty, I can see no reason why the same results map not be attained in the Bessemer practice. But two things are essential, neither of which we have here; first, cornplete analyses; and second, a record of the nature of the blow, the heat at which the ingots were bloomed, and the mile finished,—in short, a complete history of the This latter is quite as essential as accurate and complete analyses. Dr. Duclley ignores sulphur and copper on fair enough grounds commercially speaking, bnt when he announces so gmve a conclusion as he has reached, in a scientific way, the omission of any elementn that, may affect the conclusion is hardly justifiable. His diEerenvcs of phosphorus units, which I milst term units of rottenness 83 fr os phosphorus is concerned, and which I am sorry be did not llama wnits of alloys,—are very small, and if eulphur and copper hod been inclurlid they might havo upset hie conclusions sitogether, The

Jan 1, 1881