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By L. W. McKeehan, W. C. Elmore

THE magnetic powder method, long used for roughly mapping magnetic fields, has recently been refined 1,2 for investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter' first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators3 have used Bitter's original technique, with slight modifications, to study the variation of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement in the powder technique which led us to the discovery of a new effect throwing considerable light on the magnetic secondary structure of alpha iron4 and of nickel' single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure. SPECIMENS The following list describes the specimens used in the present investigation. DESIGNATION DESCRIPTION A1 Silicon ferrite furnished to us by Dr. W. E. Ruder, of the General Electric Co., for which he gave the following typical analysis: C, 0.05; P, 0.038; 5, 0.026; Mn, 0.15; Si, 3.24. Disk, 0.60 cm. diameter, about 0.05 cm. thick.

Jan 1, 1935

By H. D. Strain

Potash is a generic term used to describe a number of compounds containing the element potassium (K), which is one of the three major plant nutrients. Potash content of these compounds is commonly expressed as percentage potassium oxide (K20), and the market value of the products is usually dependent on contained K20. Most of the potash produced (approximately 95%) is used in agriculture as fertilizer. Potash products today are shipped by producing countries all over the world to meet the need for increased food production. WORLD POTASH RESERVES Apparent world potash reserves are shown in Table 15.2B.1 and total some 96 billion mt of recoverable potassium oxide. The Canadian reserves account for approximately one-half the known world reserves. The reserves shown represent the potassium oxide content of a variety of potash-bearing ores. The major ore is sylvinite (a mechanical mixture of KC1 and NaCl) from which KC1 or sylvite is recovered (63.2% K20 equivalent). Other ores, such as langbeinite (potassium, magnesium sulfate-22.7% K20) and carnallite (potassuim magnesuim chloride-17.0% K20) are also mined in various parts of the world, mainly for the potassium content. Theoretically, potassium is available in almost unlimited qualities from brines and saline waters. To date, the cost of recovery from salt brines has been greater than the costs by mining operations, but new technology could make brines and seawater an increasingly important source. POTASH PRODUCTION Potash production dates back to the 1860s in Germany, which was the only recorded producing country until 1912. By 1912 Germany was producing approximately 1 million tpy of K2O equivalent. Production began in France in 1913 and in the United States in 1915. World potash production and consumption are shown in Table 15.2B.2 for the years 1950-51 through 1967-68. In 1967 and 1968 the major potash-pro¬ducing countries in order of importance were those listed in Table 15.2B.3. By 1972 Canadian production had outstripped U.S. production. WORLD CONSUMPTION World consumption of potash for the years 1950-51 through 1967-68 is shown in Table 15.2B.2. Table 15.2B.4 shows total world consumption of potassium materials in 1967-68 by country. More than 70% of the world's potash is

Jan 1, 1976

By J. Charles Miller

NATURAL carbon dioxide has recently been exploited in the United States in consequence of oil and gas developments in the Western States and the growing demand by transcontinental and transoceanic shippers for solid carbon dioxide. The discovery by drilling of commercial deposits resulted in consideration of its geographic and geologic distribution and occurrence. Its wide distribution in nature is evidenced by its occurrence in the atmosphere, hydrosphere and lithosphere. The question of origin of carbon dioxide involves consideration of theories similar to those concerning natural hydrocarbons, although available evidence favors an inor-ganic rather than an organic source. Areas favorable to development of commercial production appear to be those in proximity to igneous rocks or in the vicinity of decadent volcanic activity, where, it has long been known, the gas is evolved either free or dissolved in the waters of furnaroles, geysers or mud pots. Structure contour maps are presented showing the Wagon Mound anticline in New Mexico and the Farnham anticline, Utah. A well drilled on the latter supplies gas to a 20-ton plant manufacturing solid carbon dioxide at Wellington, Utah, on the Denver and Rio Grande R.R., whence it is shipped to surrounding territory and to the West Coast. Before funds are invested in a plant for the manufacture of liquid or solid carbon dioxide, whether supplied by wells or springs, an effort to ascertain the volume of gas available is advisable. The use of present methods of estimation of gas reserves with modifications to account for the quantity absorbed by any water present in the produc-ing formation is recommended. The Farnham anticline is used as an example and computations are made of the probable volume of gas originally present in the struc-ture. No attempt was made to compute reserves in the Niland area, California, for the reason that in such areas it is believed the volume is indeterminate.

Jan 1, 1937

By W. W. Colpitts

To me, as to many other students of railroad needs, the necessity for reducing the dead weight in railroad rolling stock, both passenger and freight, has been apparent for, many years. The problem of weight reduction of passenger cars is so entirely different from that of freight cars, is so much more to the fore at the present moment and would seem to be so much nearer solution, that I shall confine myself in these remarks to the former. On the surface of things there would appear to be no close association of thought between the decline in traffic on the railroads, which is largely responsible for their present deplorable financial condition, and new metal alloys. It sounds like a trick riddle a school boy might propound to his parents. But that there is a relationship between the two, and one that bids fair to be of great mutual benefit to the railroads and the makers of .high-strength metal alloys, I hope I shall be able to show before I have finished. To make the situation understandable to those who are not entirely familiar with the problems of railroad management, and, who feel that the railroads have not moved as rapidly as they should in the direction of greater use of newer materials and newer appliances, I shall have to review briefly the course of recent railroad history. If in this part of my talk I seem to the professional man to be a little off key I feel sure my remarks will be fully appreciated by the business man who cannot understand why he is not making better headway in selling things to the railroads. To do this I shall have to go back to war times for a moment.

Jan 1, 1936

By W. H. Brandt

THERE has been much progress in the last two decades in understanding the hardenability of steel. Roughly, the progress has been along two lines, which may be designated as empirical and fundamental. This empirical work has progressed to the point where steels may be manufactured to the desired characteristics quite closely and heat-treatment and application problems can be approached with considerable confidence. Particularly noteworthy among the empirical work is that of Grossmann,12 who has given formulas for calculating hardenability as a function of composition, and the establishment of the isothermal transformation curve by Davenport and Bain.13 The latter does not fall entirely in the class of an empirical study, for while it provides a means of presenting a tremendous amount of empirical data in the form of a single curve, it also outlines clearly the problems that face the fundamental investigator. The isothermal transformation curve shows clearly that the phenomena occurring in the neighborhood of the knee of the curve are those that limit the hardenability of steel. Above the knee of the curve, the product of decomposition of austenite is lamellar pearlite and fundamental progress has consisted chiefly of a detailed study of structure and formation of pearlite, largely at the hands of Mehl and his collaborators.1-5 They have shown that formation of pearlite proceeds by a process of nucleation and growth and they measured both the nucleation and growth rate. However, there is still a wide gap between our empirical knowledge and fundamental knowledge, owing largely to the fact that there is no satisfactory theory of nucleation rate or of growth rate. This paper is being written in an attempt to fill in a small part of the gap. A method was presented recently14 for calculating the velocity of edgewise growth of pearlite using an expression for the carbon concentration that satisfies the diffusion equation. The edgewise velocity of pearlite growth in a plain carbon eutectoid steel was calculated, using linear extrapolations of the ferrite and cementite solubilities. While the results are in fairly good agreement with the experimental facts, the calculated velocity of edgewise growth is smaller at 600°C. than G, the radial growth velocity of pearlite nodules, whereas one would expect it to be larger. In this paper the calculation will be repeated using a new extrapolation for the ferrite solubility, which gives better agreement between G and V, the calculated velocity of edgewise growth. A calculation will also be made of the effect of carbon content on velocity of edgewise growth, and the problems of calculating the effects of other alloying elements on growth rates will be discussed. It will be assumed that the mechanism of pearlite growth, established by Mehl and

Jan 1, 1945

By W. E. D. Jr. Stokes

THE application of aviation to mining and petroleum operations, on the basis of economy and attainment, has become a demonstrated fact. According to Dominion Government records, 30. Canadian companies engaged in air transportation with northland mining camps, carried 13,000 tons of freight in 1935, and in 1936 carried 16,000 tons. In addition, many mining companies used planes to transport prospectors with canoes, outboard motors, gasoline drums and supplies to remote locations, and one company maintained a plane to take radium-bearing ore from its mine on Great Bear Lake nearly 1000 miles south to the rail-way at Waterways, Alberta. Heavy pieces of mining machinery weighing 2 tons are being carried by Ford trimotor planes over the Andes, at an altitude of not less than 15,000 feet. At Bulolo, New Guinea, 17,500 tons of disassembled gold-dredging equipment has been flown over inaccessible terrain, while supplies and building materials for a, community of 1000 whites have been transported by airplane. A 3 1/2-ton shaft was carried on one notable trip, while at another time an automobile, 2 tons of rice and a large safe went over the mountains in one plane. Fig. 1 shows an electric generator that was carried by plane to Bulolo.

Jan 1, 1937

By W. F. Boericke

NOT the least interesting sights that New York has to offer the visiting mining engineers are the extensive tunnel operations that are being pushed in connection with the subway construction. While a "hard rock" man might feel at home on these jobs, the engineers driving the subway tunnels have necessarily had to encounter some new problems pe-culiar to the largest permanent mining camp in the country. To drive a heading 36 by 18 ft. in hard rock, with a station section to follow 52 by 27 ft. across-and to do it in the midst of a city's traffic-demands engineering skill of a high order. Not the least of the problems overcome by the engineers in charge was to provide adequate ventilation for the men at the face at all times, so that there would be no delay in the work. With a crew of 40 men (32 drill runners and helpers on the machines alone, working two shifts) a hold-up due to inability to get back promptly to the face after shooting would affect costs quickly. AIR VITIATED BY EXHAUST FUMES FROM MOTOR TRUCKS A complication not encountered by metal miners, but which the subway engineers had to meet, was pollution of the air in the tunnels by fumes from the exhaust of the motor trucks used to haul away the broken rock. As shown in the cut, motor trucks were constantly em-ployed to remove the heavy tonnage broken as the tun-nels went ahead, amounting, according to R. J. Van Wagner, chief engineer of the Del Balso Construction Co., to 48 cu. yd. per ft. of tunnel advance. As the length of the tunnel under his management was 900 ft., it was essential for the safety of the men that suffi-cient air be introduced to dilute the poisonous fumes so that no ill effects would be felt for the entire distance that the trucks had to travel. The presence of the ex-haust fumes was especially noticeable on foggy days.

Jan 2, 1928

By M. C. Dow

INTRODUCTION BELT conveyors generally are conceded to be the most economical method yet devised for the transportation of large quantities of bulk materials within plants. Belts are coming into greater use for transportation over long distances and are replacing other forms of long-haul conveyance. It is not the intent of the writer to comment on the design of belt conveyors, but to offer some suggestions for improvement in the operation of conveying belts, based on many years experience with belts in several stonecrushing plants. It is the contention of this writer that opportunities for improvement not fully realized by most operators exist in many plants and that a study of the individual conveyors can result in lower unit belt costs. GENERAL RELIABILITY It is the fool-proof nature and general reliability of the belt conveyor that is responsible for its neglect. Even when abused, a belt will carry large tonnages and last a long time, often outlasting the personnel responsible for its care. Some operators look upon the purchase of a new belt as an expensive outlay every so many years, rather than a constant and steady cost amounting in belt wear alone to several dollars every operating day. This belt wear for all conveyors in one stone-crushing plant known by the writer costs 1 1/2 cents per ton or $12 to $15 per hour, based on the present cost of belt replacements. The fact that these replacement costs are double those of prewar quality emphasizes the necessity of improving the conditions that make belts wear out. Some of those conditions are the responsibility of the conveyor designer, and if a serious original error has been made, this handicap cannot be overcome by the operator. If the belt is too narrow, too steep, or too fast for good loading, the operator finds that he has an inherently expensive belt. The other factors that decrease the life of a belt are more or less under his control. The two factors of most importance are the loading conditions and the alignment. Most of the cover wear and carcass cutting occurs at the loading point and if the alignment is not good under all conditions, edge wear or damage may result, Fig I. LOADING THE BELT It is difficult to load a belt in an ideal manner; that is, to flow the material on the moving belt at a steady rate, without impact, without turbulence, and with a velocity equal to and in the same direction as the belt. An inclined belt is especially difficult to load and particularly when its speed is over 300 or 350 fpm. Inclined conveyors require longer skirt plates to prevent spillage until the load settles. It does not seem reasonable to expect an inclined conveyor to carry the same load as a horizontal belt of the same width and speed, because of the difficulty in loading

Jan 1, 1947

By B. D. Cullity, A. Freda

It is well known that deformation by cold drawing or swaging produces a kind of preferred orientation called fiber texture in metal wires. Such textures have been extensively studied by means of X-ray diffraction, chiefly by techniques in which the diffracted X-rays are recorded photographically. This paper describes some results obtained with a new method, involving the use of a diffractometer. X-RAY METHOD Since the pole figure of a material having a fiber texture is symmetrical about the fiber axis, there is no need to present the entire pole figure. Instead, texture data can be summarized by means of a curve showing the variation of pole density along any meridian of the pole figure, if the north-south axis of the latter is made parallel to the fiber axis. The position of a pole on the meridian is specified by the angle 9 between the pole and the fiber axis (wire axis). The X-ray method1 used here to measure pole density as a function of 9 actually consists of two methods, referred to as A and B. In method a, X-rays are reflected from the wire surface. Pole densities can be measured by this method from O = 90 deg down to a limiting value which is dependent on the Bragg angle 8 and is typically of the order of 30 to 40 deg. Method B involves diffraction from the wire cross section and covers a range of 0 values from 0 up to an angle sufficient to overlap the measurements made by method A. By a combination of the two methods, a complete pole-density curve can be obtained. However, method A alone, which requires no specimen preparation other than etching, can often reveal enough of the pole-density curve to provide complete information about texture components. Both methods require that the measured diffracted intensities be corrected for changes in absorption and diffracting volume with changes in 9. A11 intensities I reported in this paper are corrected diffracted intensities; they are propor-

Jan 1, 1960

By Juanito C. Fernandez

INTRODUCTION The Philippines is endowed with mineral resources, much of which still remains unexploited. The country's known reserves, at least for the major mineral commodities, have increased every decade since the first major discoveries more than 80 years ago. Mining, therefore, naturally evolved as one of the pioneer industries and has ever since been a major factor in economic development. The Philippines has entered a new era in mineral resources development and management. One significant feature of this era is the degree to which the government is involved with the industry. In recent years, the state has increasingly encouraged the private sector to carry out detailed exploration aided by governmental contributions through extensive geological and geophysical surveys, fundamental researches and even indirect financial assistance in some specific areas. Significant changes in mineral resources development policies were brought about with the promulgation of Presidential Decree 463 or the Mineral Resources Development Decree of 1974. The Decree provides for a more rational system of administration and disposition of mineral lands to promote mineral resource exploration and exploitation. Various forms of incentives are provided. Foreign entities are allowed to participate in development through service contracts with leaseholders or with the government in the case of reserved areas. The thrust in mineral resources development has been focused on the base metals which as envisioned would provide the foundation for sound economic development. In recent years, however, major strides have been made to promote the exploitation of the non-traditionally produced commodities especially the non-metals. Development likewise point to the growing determination of the government and the private sector to expand benefits from mining. This is evident in efforts to promote downstream processing operations and to encourage investments in exploration, exploitation and mineral processing ventures. The integrated mineral resources development plan, therefore, proposes the vertical integration of mining extraction activities with the processing requirements of the metal-based manufacturing industries. While mining activities shall continue to be carved out by the private sector, the government shall influence the industry's direction by establishing legitimate goals to maximize benefits through an integrated approach giving due consideration to environmental protection and resource needs of future generations. STATUS OF MINERAL RESOURCES DEVELOPMENT Extent of Exploration Application of modem exploration tools and concepts complemented by intense infusion of foreign technology and rapid development of indigenous expertise have enabled the government jointly with the private sector to geologically explore vast grounds and to expand the country's known mineral resources. Approximately 93% of the country's total land area of 30 million hectares have been geologically mapped on at least 1:250,000 scale. Of the 93% total coverage, roughly 37.54% or 11.07 million hectares have been done on scales of 1:10,000 to 1:50,000 as shown in Figure I. Only 3.07% of the total coverage have been surveyed in detail. Land gravity surveys have been undertaken on over 45% of the total, while some 77,300 line km. of aeromagnetic surveys have been flown over 110,000 sq. km. of land area. Processing of data is almost complete. Total magnetic intensity and IGRF-corrected maps are available. Geological interpretation utilizing Landsat MSS imagery and low altitude aerial photography augmented by ground truthing have been undertaken in several large areas with very encouraging results. Beach and offshore mineral surveys were initiated in 1977 and have covered substantial areas in northwest and southeast Luzon and northeastern Mindanao. Highly promising areas for detrital magnetite, chromite, gold and some heavy minerals including ilmenite and titanium have been identified. In the petroleum sector, two offshore oilfields are currently producing from Miocene limestone reefs in Northwestern Palawan. Another field from the same area will be on stream in mid-1982.

Jan 1, 1982

By B. C. Craft

The principal events in the oil and gas operations for Louisiana during 1933 have been the rapid development of the Converse field in Sabine Parish, the discovery of three new salt domes, one in North Louisiana and two in South Louisiana, increased development in the Iowa field on the Calcasieu-Jefferson Davis Parish line, and extensive geophysical operations over a wide territory. Other miscellaneous events worthy of mention are the continued leasing of prospective oil lands over a wide area, extension of production at the East Hackberry field, Cameron Parish, discovery of deep sands at Caillou Island, Terrebonne Parish, and the completion of several important wildcats. Despite proration, oil production showed a substantial increase during 1933. The total output for this area was 25,599,802 bbl. as compared with 22,507,387 bbl. during 1932. North Louisiana There were 111 oil wells and 47 gas wells completed in North Louisiana during 1933 as compared with 109 oil wells and 33 gas wells during 1932. North Louisiana oil production decreased approximately 692,625 bbl. in 1933 from its 1932 figure. The normal decline in the old fields was partly offset by increased production at the Zwolle and Converse fields in Sabine Parish. Acid treatment of wells in the Zwolle, Converse and Monroe fields was highly successful. The method of application has been described by H. K. Shearer, Geologist, Pelican Natural Gas Co., as fo1lows:l With tubing in the hole and standing valve removed, the casing is filled with oil to the surface. The limestone solvent is pumped in through the tubing, at the same time bleeding off enough oil from the casinghead to equal the volume contained in the tubing plus the volume of open hole to be treated. The amount of solvent used in most of the wells treated was 1000 gal., which is enough to dissolve about 11 cu. ft. of chalk or limestone. After the computed amount of oil is bled off, the casinghead is closed and the remainder of the solvent is pumped in at whatever pressure is necessary to force it into the oil-producing horizon. The solvent is followed up with enough oil to

Jan 1, 1934

By G. F. Loughlin

Nearly 55 years have elapsed since the U. S. Geological Survey was organized. During this period the mineral industries have grown from infancy or early childhood to well developed maturity, and some mining industries appear to be declining. Decline in mining is even more conspicuous in certain districts, or even states, than in any mining industry as a whole, and discoveries or developments of important new districts have been very few in recent years. Our reserves of most metals and nonmetals are adequate for many years of normal production, subject to changes in rate of exploitation that may be caused by foreign competition and by changes in technology and market conditions; but the declining production of many districts and the scarcity of important new discoveries to compensate for them is cause for some apprehension. It is likely that future production will depend to a considerable extent on deep exploration and on the thorough examination of places in and adjoining existing districts where significant outcrops are lacking and only apparently insignificant geologic features offer encouraging clues—more so than on the discovery of entirely new districts. Even the possible discovery of new districts, which have escaped the intensive search by the nontechnical prospector, must be dependent on geologic information. There is therefore no need for argument as to the value of geology to the mining industry; and the need of continuing to advance the science. The U. S. Geological Survey's past contributions to mining geology, as expressed in its official reports and other publications, are recognized by Ransome in his historical review of mining geology in the Lindgren volume.' These contributions have helped to form the basis of modern mining geology, which has grown rapidly in the last 25 years. This growth has witnessed the organization and maintenance of geologic staffs by mining companies in several districts, and their detailed work, together with the fact that nearly all of the larger mining districts have

Jan 1, 1935

Report of the Secretary TO THE BOARD OF DIRECTORS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen:-To a Board of Directors keeping in as close touch with all of the affairs under their care as do the Board of Directors of the A. I. M. E., through their monthly meetings, a report of the year's progress is almost superfluous. To the members who read the monthly reports of. the Board Meetings and of the various activities of the Institute as published each month, a yearly report cannot carry much fresh information; yet for both it may be well, as is the custom, to glance over the field of our activities during the past year, and to make an estimate for the year to come. The beginning of 1924 was not propitious for the members of the mining profession, though tonnage production for 1923 had been high and the gross value higher than for several years. The margin of profit had been narrow, prospecting and development were limited, and many of our members were unemployed, or were working in other industries. Toward the end of the year, higher metal, prices were in sight. Old-time optimism began to grow, and it now brightens the outlook for 1925. An excellent barometer of the prosperity of the industry, and that of the Institute, for they go hand in hand, is the work of our Employment Bureau. During the past few months, the percentage of our members for whom openings have been found has been increasing to a marked extent, and many members who had fallen in arrears are placing themselves in good standing. The number of new members joining has remained about as it was in 1922 and 1923. The Directors have reason to congratulate themselves on the interest maintained during a dull period, for it is not humanly possible to take a keen interest in the technology of an industry when our hands and minds are not actively engaged in it Now, with a much brighter outlook, we can look forward to a year of increasing prosperity for the industry and for the Institute.

Jan 3, 1925

By Hansheinz Portisch, Harold Margolin

A surface expansion was found to occur sometime after etching in Ti-A1 alloys containing 9.5 to 12.5 wt pct Al. The structure formed, grew, and disappeared with tzrrze. The surface expansion was followed by microscope observations and interferometric and lattice parameter measurements. Activation energy measurements for the growth of the "expansion structure" and chemical analysis indicated that the phenomenon occurred as a result of hydrogen pzckup during etching. It is proposed that hydrogen initially enters octahedral sites of Ti3Al coherent with a Ti and later shifts to the tetrahedral sites. It is postulated that expansion occurs when hydrogen enters the tetrahedral sites. The expansion structure disappeared, it is proposed, because of diffusion of hydrogen from the surface into the body of the alloy and because of loss of coherency of Ti3Al. In examining Ti-A1 alloys, Ence and arolinl observed markings on the surface of specimens. These markings did not appear after electropolishing only, but rather appeared only after etching. The markings appeared to grow as a function of time after etching and later seemed to disappear. Although the markings had some similarity to precipitates, showing, frequently, a Widmanstatten type of arrangement, the observation that other microstructural markings continue to be seen within the new structure suggested that it was actually not a precipitate. The source of this structure was unknown and an attempt was made in the present investigation to develop some understanding of its nature. It has been labeled expansion structure. 1) EXPERIMENTAL PROCEDURE A) Alloys. Alloys in the range 6.5 to 14.5 wt. pct A1 were studied. Bars, 4 in. sq, forged from Bureau of Mines (73 Bhn) titanium consumably arc-melted 4-lb ingots,' as well as 50-g arc-melted buttons of desired aluminum contents were used. The 50-g buttons also used Bureau of Mines titanium (73 Bhn) and aluminum of 99.99 pct purity. Buttons containing up to 8.5 wt pct A1 were hot-rolled from a furnace at 900' . Those with higher aluminum contents were hand-forged on a titanium anvil, and heated with an oxygen-hydrogen torch in the region of 1200" to 1300°c. Frequent reheating kept the samples at the desired temperature range. After a reduction of about 30 pct, the samples were water-quenched. To eliminate any contamination picked up either during hot rolling or forging, at least 1 mil of the surface of the sample was taken off. B) Heat Treatment. Prior to heat treatment all alloys were vacuum-annealed to remove hydrogen. Samples were annealed at 900' until a vacuum of 10'5 mm Hg was established. After this treatment, the samples were wrapped in molybdenum sheet and heat-treated in argon-filled quartz capsules, which were broken under water or iced brine at the conclusion of the heat treatment. All heat treatments under dynamic vacuum were performed in a rapid-quench furnace. This consisted of a molybdenum-lined quartz tube attached to a vacuum system and through a stopcock to a beaker of water. At the completion of the heat treatment the vacuum stopcock was closed, the furnace shut off, and dropped below the quartz tube. Then immediately the inlet stopcock was opened and water admitted until the tube was filled. The steam formed was allowed to escape through the inlet stopcock. This method was used in heat treatments up to llOO°C. C) Metallography. Specimens for metallographic examination were ground, then electropolished using a Disa Electropol machine with a perchloric acid electr01te. Specimens were etched with R-etch.3 A standard etching time of 3 min was used, with the specimen being agitated during immersion. D) Sample Preparation for X-ray Analysis. Samples 0.2 to 0.5 mm in diam were produced from heat-treated rods which were turned to 2 mm diam on a lathe and then rotation-etched. An etchant consisting of 1 pt HF, 7 pt HN03, and 12 pt HzO was satisfactory. With the rod rotating in a vertical position at 50 to 100 rpm, a needle with uniform dimensions could be obtained. Care had to be taken to insure that the rod was at the center of rotation, otherwise cavitation developed. If a small unevenness developed, it was possible to grind it off with a fine emery paper. E) X-ray Diffraction. All X-ray work was done on a North American Phillips X-ray diffraction apparatus and a Jarrell Ash microfocus X-ray unit. The Phillips unit was used with a copper target and nickel filter. The Jarrell Ash unit was fitted with a cobalt target and iron filter. For the Phillips unit 35 kva and 20 ma were used, whereas for the microfocus unit with the 100-p fixed-focus gun 40 kv and 1.5 ma were used. It was found that alignment of cameras on the Jarre11 Ash unit was very critical. The X-ray beam contains an intense area which is not the beam center. The cameras were aligned with the intense region by monitoring the beam coming out of the camera with a Geiger counter. Adjustments were made until a maximum intensity was obtained. A Phillips diffractometer with a Brown chart recorder furnished some of the lattice parameter data. The divergence slit up to 80 deg 28 was I deg; above 80 deg, a 4-deg opening was used, while the scatter slit was1 deg and the receiving slit had a 0.003-in. opening. The general scanning rate was 1 deg per min, while peaks of special interest were rescanned at -j deg per min. For elevated-temperature X-ray diffraction a Uni-cam High Temperature Camera with a film diameter

Jan 1, 1969

By H. S. Munroe

To those familiar with ore-dressing practice, it is hardly necessary to dwell upon the importance of the jig. Within its proper sphere no substitute has been found that does the work as well or as cheaply. Its capacity is large, it requires but little attention, and the losses are small. In one form or another, it is the principal machine used in the concentration of low-grade ores, and for the separation of one metallic mineral from another; and it is almost the only machine used for the purification of coal. The present paper is a study of the action of the jig in the light of results obtained in the Lake Superior copper mills, ad at the St. Joseph Lead Co.'s dressing-works, in Missouri; and a description of experiments undertaken with the view of reproducing and isolating the conditions of jigging, in order to develop the laws which underlie the process. There are two recognized systems of jigging, the English and the Continental or German. The English system is a development of the hand-jigging formerly employed in Cornwall and other metalliferous districts of England, and introduced by English miners to this country. In this method the crushed ore, coarse and fine together, is first jigged oh a

Jan 1, 1889

By G. E. Pellissier, C. W. Mason

Tin has long been cited as offering a classic example of polymorphism, second in repute only to the allotropy of sulphul.. The notorious "tin disease," which Cohenl has studied so exhaustively in terms of the enantiotropic transformation of tetragonal white P tin to cubic gray a tin, has apparently encouraged the expectation that one or more additional polymorphic modifications might exist. The search for confirnmntion of this idea has, as might be anticipated, led to the accumulation of a body of miscellaneous evidence, much of which would probably never have been sought, or taken seriously even by its discoverers, but fur previous assumptions. The ball apparently was started rolling iii 1880 by Trechmann,2 who reported a new modification of tin (7 tin), which was brittle and found in "hard head," a highly arsenical, slaggy material produced in a certain stage of tin smelting. A mixture of two kinds of crystals was obtained from a Cornish tin furnace, and those thought to be 7 tin were studied crystallographically. The results indicated that these crystals were rhombic and of different density from the tetragonal tin prepared electrolytically by Miller. Their analysis was given as 98.7 per cent Sn, 1.3 per cent Fe, and traces of As, Sb, Bi and S. In 1881 von Foullon4 obtained similar crystals from a Bohemian tin furnace. Headden5 examined crystals similar to those of Trechmann and von Foullon and reported them to be monoclinic, but of analysis corresponding to stannous sulphide. Later, Stevanovic,~ by goniometric measurements, proved that these crystals of SnS were really rhombic. Groth7 pictures and describes both "rhombic tin" (Fig. 9, vol. 1) ant1 stannous sulphide (Fig. 84, vol. 1); their faces and angles correspond within the accuracy of measurement. Spencers in 1921 examined the above evidence critically; lie lound similar crystals from Cornish tin furnaces, proved them to be SnS, and even was able to analyze some of Trechmann's original specimens, finding high sulphur content. (Apparently Trechmann's analysis had been based on :L second lot of crystals, not described crystallographically.)

Jan 1, 1939

By G. E. Pellissier, C. W. Mason

Tin has long been cited as offering a classic example of polymorphism, second in repute only to the allotropy of sulphul.. The notorious "tin disease," which Cohenl has studied so exhaustively in terms of the enantiotropic transformation of tetragonal white P tin to cubic gray a tin, has apparently encouraged the expectation that one or more additional polymorphic modifications might exist. The search for confirnmntion of this idea has, as might be anticipated, led to the accumulation of a body of miscellaneous evidence, much of which would probably never have been sought, or taken seriously even by its discoverers, but fur previous assumptions. The ball apparently was started rolling iii 1880 by Trechmann,2 who reported a new modification of tin (7 tin), which was brittle and found in "hard head," a highly arsenical, slaggy material produced in a certain stage of tin smelting. A mixture of two kinds of crystals was obtained from a Cornish tin furnace, and those thought to be 7 tin were studied crystallographically. The results indicated that these crystals were rhombic and of different density from the tetragonal tin prepared electrolytically by Miller. Their analysis was given as 98.7 per cent Sn, 1.3 per cent Fe, and traces of As, Sb, Bi and S. In 1881 von Foullon4 obtained similar crystals from a Bohemian tin furnace. Headden5 examined crystals similar to those of Trechmann and von Foullon and reported them to be monoclinic, but of analysis corresponding to stannous sulphide. Later, Stevanovic,~ by goniometric measurements, proved that these crystals of SnS were really rhombic. Groth7 pictures and describes both "rhombic tin" (Fig. 9, vol. 1) ant1 stannous sulphide (Fig. 84, vol. 1); their faces and angles correspond within the accuracy of measurement. Spencers in 1921 examined the above evidence critically; lie lound similar crystals from Cornish tin furnaces, proved them to be SnS, and even was able to analyze some of Trechmann's original specimens, finding high sulphur content. (Apparently Trechmann's analysis had been based on :L second lot of crystals, not described crystallographically.)

Jan 1, 1939

By F. L. Bosqui

INTRODUCTION The history of the development of gold metallurgy in South Africa is divisible into two periods: That preceding the introduction of the cyanide process on a commercial scale in 1890; and the 24 years intervening between that important event and the present time. The period between the discovery of the banket reefs of the Witwatersrand and the year 1890 was one of phenomenally rapid progress in mining development, but of no special interest to the metallurgist. There were no strikingly original or distinctly local advances in the treatment of gold ores. Californian practice in stamp milling and amalgamation prevailed, in mills ranging in equipment between 5 and 50 stamps, operating within a wide range of efficiency, and under the trying conditions usually en¬countered in a new and isolated field. The somewhat incomplete records of gold output of that period show that in December, 1887, there were 20 producing companies in the Witwatersrand district, of which 10 had mills, the largest being of 20 stamps. The only official record of returns for May, 1887, was that of the Wemmer mine, whose modest achievement with a 5-stamp, mill was 100 tons crushed, producing 887 oz. 3 dwt. of gold. This is interesting in view of the .present-day output of this field, which in 1913 reached 8,430,998 oz. The rapid increase of production during this first period (May, 1887, to January, 1891) is shown by the following summary for the year 1890:1 Total tons crushed 702,828 Number of stamps in operation 1,046 Average number of tons crushed per stamp per day 2.36 Yield of gold, ounces 494,817 Yield per ton, pennyweights 13.36 The stamp duty ranged between 1 ½ and 4 tons per day, according to weight of stamp, fineness of screen, and operating skill available. The prevailing weight of stamp was about 900 lb., and the screen, 900 meshes to the square inch.

Jan 5, 1915

By John Hays Hammond

The Transvaal comprises about 120,000 square miles (nearly • the size of the United States Territory of New Mexico). Besides the famous Witwatersrand, which will here be de scribed in detail, there are two quartz-mining districts of some importance, viz., Lydenburg and De Kaap. The Lydenburg district first attracted attention in 1876, when the alluvial deposits of that section began to be exploited. At a later period vein-rnining was started, and at the present time several companies are operating in that district. The product in 1898 of five companies, running 137 stamps, was 154,560 tons of ore, yielding 108,884 crude ounces of gold (an average of 14.09 dwt. crude gold per ton) valued at £392,378. The De Eaap gold-fields were discovered in 1884. In 1898, seven companies, running 200 stamps, produced 89,760 crude ounces of gold, valued at £314,792. I. Mining Titles in the Transvaal. The mining laws of the Tranuvaal are most excellent in char acter, and while the claims cover every square foot of land for an area of nearly 40 miles long by from 2 to 3- miles wide, there have been practically no conflicts over extra-lateral rights. Notwithstanding the change in the political status of the Transvaal likely to follow the present war, it may be coufi dently assumed that the main features of the mining law of the South African Republic will be retained, and certain op pressive featureu of monopolies, etc., bearing with special weight on the mining industry, will be abolished. The dynamite mo nopoly was one that bore most heavily on the mining industry; and, according to the Reports of the State Mining Engineer, explosives, including fuse and detonators, amounted to nearly 10 per cent. of the total working costs of the mines. Further more, it was impossible to obtain the proper quality for the most economical working, and often 80-per-cent. or 40-per-cent. gelatine had to be used- in many instances where 60-per-cent.

Jan 1, 1902

By George Kunz

(Butte Meeting, August, 1913.) . THE manifold inconveniences resulting from the absence of a uniform standard of mass for determining the weight of precious stones have long been obvious. This lack has been keenly felt in commercial transactions, and those who have devoted time and research to the study of historic diamonds and precious stones have had frequent occasion to deplore the absence of such a standard in the past. In a paper read in Chicago in 1893, before the International Congress of Weights and Measures, held in connection with the World's Columbian Exposition, the writer suggested dividing the carat into 100 parts, and constituting a standard international carat of 200 mg. ; that is, 5 diamond carats or 20 pearl grains to a French gram, making 5,000 carats or 20,000 pearl grains to a kilogram. He also called attention to the fact. that while this would depreciate the present diamond carat or pearl grain only about 2.5 per cent., it-would abolish the troublesome discrepancies between the various carat-weights now in use, and could be easily explained and understood everywhere.1 The subject of the various diamond carats, their incongruity, and the resulting confusion as to the correct. weights of historic gems when definite records of them are searched for, has been fully treated by me in an extensive study of this subject in The Book of the Pearl.2 To the earnest and unremitting efforts of C. E. Guillaume, Director of the Bureau Internationale des Poids et Mesures at Sèvres, is largely due the eventual success of this eminently desirable reform, which he has constantly urged both by articles on the subject and by addresses delivered in Paris before the International Committee for Weights and Measures.2

Jan 7, 1913