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By Henry Louis

Four alloys of gold and silver were prepared, containing the metals in the following proportions by weight: I. Gold:Silver::1:2.62.

Jan 1, 1894

By G. W. Josephson

Since the earliest years of recorded history the durability and protective qualities of asphalt and tar have been known and utilized. The mummies of early Egyptian kings were coated with asphaltic materials, and asphalt mastics were common in Babylon. However, according to various authorities, it was not until 1780 that the first forerunner of present-day composition roofing was discovered,l and the large-scale expansion of the industry has taken place since 1900. Historical Background Development was stimulated by the growing popularity of manufactured gas. The by-product tars from these operations accumulated in large waste piles that had no commercial value and were a source of annoyance and expense to the gas companies. These tars were offered at very attractive terms to anyone who would take them away, and the infant "composition" roofing industry benefited accordingly. At first the process consisted simply of dipping sheets of burlap or other fabric in a tank of molten tar or asphalt. The long strip of roofing was rolled up for convenient handling, and the early experimenters soon found that it was necessary to dust the surface of their new "roll roofing" with some kind of material that would prevent the tarred surfaces from sticking together. Any finely divided, low- priced local material like sand or fine gravel served this purpose and from its application the roofing-granule industry grew. As time went on other characteristics of a properly applied mineral surfacing were recognized. As with wooden shingles, tar and asphalt can be ignited by flying embers from near-by fires. It was found that by increasing the largest particle size to the maximum that could be successfully embedded, and by properly controlling the amount of smaller fractions retained in the grade so as to cover the asphalt completely a high degree of resistance to fire was attained. Needless to say, in this early period asphaltic roofing needed such selling points to gain acceptance in a field dominated by wood, slate, and tile. When asphalt is protected from the sun's rays it is extremely durable, but when exposed to sunlight its surface is comparatively rapidly decomposed. Completely covering asphalt roofing with mineral surfacing protects the asphalt and adds materially to the life of the roof—conservatively, 500 per cent. Slate Graftules In the production of split slate shingles a large quantity of waste slate is accumulated, as 60 to go per cent of the rock quarried is discarded. This waste was a continuing burden on the industry. Some was marketed as ground slate flour for filler in paint and linoleum, and there is a record that as early as 1906 two carloads of coarse screenings from slate flour were marketed as granules for surfacing roofing. This new field appeared to the slate Pro-

Jan 1, 1948

By G. W. Josephson

Since the earliest years of recorded history the durability and protective qualities of asphalt and tar have been known and utilized. The mummies of early Egyptian kings were coated with asphaltic materials, and asphalt mastics were common in Babylon. However, according to various authorities, it was not until 1780 that the first forerunner of present-day composition roofing was discovered,l and the large-scale expansion of the industry has taken place since 1900. Historical Background Development was stimulated by the growing popularity of manufactured gas. The by-product tars from these operations accumulated in large waste piles that had no commercial value and were a source of annoyance and expense to the gas companies. These tars were offered at very attractive terms to anyone who would take them away, and the infant "composition" roofing industry benefited accordingly. At first the process consisted simply of dipping sheets of burlap or other fabric in a tank of molten tar or asphalt. The long strip of roofing was rolled up for convenient handling, and the early experimenters soon found that it was necessary to dust the surface of their new "roll roofing" with some kind of material that would prevent the tarred surfaces from sticking together. Any finely divided, low- priced local material like sand or fine gravel served this purpose and from its application the roofing-granule industry grew. As time went on other characteristics of a properly applied mineral surfacing were recognized. As with wooden shingles, tar and asphalt can be ignited by flying embers from near-by fires. It was found that by increasing the largest particle size to the maximum that could be successfully embedded, and by properly controlling the amount of smaller fractions retained in the grade so as to cover the asphalt completely a high degree of resistance to fire was attained. Needless to say, in this early period asphaltic roofing needed such selling points to gain acceptance in a field dominated by wood, slate, and tile. When asphalt is protected from the sun's rays it is extremely durable, but when exposed to sunlight its surface is comparatively rapidly decomposed. Completely covering asphalt roofing with mineral surfacing protects the asphalt and adds materially to the life of the roof—conservatively, 500 per cent. Slate Graftules In the production of split slate shingles a large quantity of waste slate is accumulated, as 60 to go per cent of the rock quarried is discarded. This waste was a continuing burden on the industry. Some was marketed as ground slate flour for filler in paint and linoleum, and there is a record that as early as 1906 two carloads of coarse screenings from slate flour were marketed as granules for surfacing roofing. This new field appeared to the slate Pro-

Jan 1, 1948

By G. Donald Emigh

Nothing is more important to life-plant and animal-than phosphate. Its compounds are essential to the energy functions of all living systems and for the formation of bones and teeth. Animals get their phosphate from eating plants and other animals, or domestically from feed supplements. Plants get their phosphates from the soil. Man's most important use of phosphate is for fertilizer; approximately 95% of the world's phosphate rock production is consumed by fertilizers. Most of the balance is processed in electric furnaces into elemental phosphorus, the important raw material for making industrial phosphates. Recovery of uranium from phosphates has been possible but not widely used. However, recent significant developments have generated interest in such recovery in the US and elsewhere. Phosphate occurs in all igneous and sedimentary rocks, and in all fresh and salt water. However, economical recovery is limited to deposits where natural concentration of the phosphate mineral has occurred. Occasionally natural concentration is great enough that the material can be used as mined; generally, however, the ore is low grade_ and must be concentrated. Phosphate rock is produced in 31 countries. Fig. 1 shows the location of major phosphate rock producers as well as some of the known phosphate deposits not yet in production. In the last decade the world phosphate industry has experienced steady growth. World production rose from 98 Mt of phosphate rock in 1973 to 140 Mt in 1982. Fig. 2 shows the growth curve of rock production and graphically illustrates the almost straight-line rise since 1945 in both US and world production. Table 1 gives the breakdown, by countries, of world rock production, 1974 through 1979. Table 2 shows US rock production by producing areas. Definitions of Terms Used in the Phosphate Industry Phosphate Rock: Commonly called rock in sedimentary deposits and apatite in igneous deposits. Those expressions generally include any mined, or mined and beneficiated, fluorine-containing calcium phosphate used as the raw material for the next stage of manufacturing. The average phosphate content in rocks is 0.1 to 0.2% P2O5, as documented by McKelvey (1973). About 200 minerals contain more than 1 % P2O5. However, the important mineral in igneous rocks is fluorapatite, [Ca5 (PO4),3 F], containing about 42% P205 and 3.8% F2; in sedimentary rocks the important mineral is francolite, a carbonate fluorapatite containing up to 2% molecular CO2. Both are in the apatite family of minerals. Most phosphate rock, whether beneficiated or not, is a fine-grained material. The expression phosphate rock has no relation to its phosphate content. For example, phosphate rock from Idaho used in the production of phosphorus may contain about 24% P205, whereas rock from Morocco may contain 36.6% P2O5. Phosphorite: A deposit of phosphate directly or indirectly of sedimentary origin, which is of economic interest. Grade of Phosphate Rock: The calcium phosphate content of phosphate rock is expressed in different world areas by one of the following terms: BPL (bone phosphate of lime) TPL (triphosphate of lime) P2O5 (phosphorus pentoxide) P (phosphorus-not commonly used) An illustration of relationship is: 80% BPL = 80% TPL = 36.6% P5O2 = 16% P

Jan 1, 1983

By A. F. Crawley

The densities of some liquid Pb-Sb alloys up to 11 wt pct Sb and Pb-Sb-& alloys up to 10 pct Sb/10 pct Sh have been determined by a pycnometric technique over a temperature range of about 130°C above their melting points. The data given are accurate within 0.05 pct. Density is shown to vary linearly with temperature , and equations relating these quantities have been formulated. Molar volumes calculated from the density data indicate that volumetric deviations from ideal mixing are undetectable within the limits of experimental error. A continuing research program into some fundamental physical properties of liquid metals is being pursued at the Mines Branch, Department of Energy, Mines and Resources, Ottawa, Canada. This work has received support from the Canadian Zinc and Lead Research Committee in cooperation with the International Lead and Zinc Research Organization. This paper, which reports some density data for Pb-Sb and Pb-Sb-Sn alloys, follows previous work from this laboratory on lead, tin, and Pb-Sn alloys.' Of previous data from others, Greenaway2 and Sato and Munakata3 have reported results on Pb-Sb alloys. No previous work has been published on the ternary Pb-Sb-Sn alloys, reported here. EXPERIMENTAL METHOD Densities were measured by a pycnometric technique which has been described in detail and appraised for accuracy in earlier Mines Branch reports.475 Fig. 1 shows the densitometer with the pycnometer in position for a run. The pycnometer is also shown in some detail. The pycnometer of dense, high-purity graphite, about 14 cu cm in volume, was carefully machined to a uniform, smooth finish. The height was measured by a depth micrometer and the diameter by fitting precision gage blocks between steel balls.' In each case several readings were taken, and the final results were considered accurate within 0.01 pct. The resulting volumetric uncertainty together with small inaccuracies in the coefficients of linear expansion of graphite lead to a maximum systematic uncertainty in the method of ±0.03 pct. As shown in Fig. 1, the pycnometer lid is a threaded cap. Thus, the charge, a cylinder of the alloy, can easily be inserted and the solidified metal can readily be removed after a run. The dimensions of the cylindrical charge are chosen to ensure that, once molten, the metal will not only fill the pycnometer completely but will discharge an excess into the excess-metal float chamber. AS the temperature is increased above the melting point, the volume of metal in the excess chamber increases until the system has equilibrated at the desired temperature. At this point, the excess chamber is moved to one side by twisting the shaft F, leaving a fixed volume of liquid metal in the pycnometer. This volume of fluid is readily calculated using measured coefficients of linear expansion of the graphite which expands anisotropically. The associated weight of fluid is determined as the weight of the solidified metal removed after the furnace has cooled down. Alloys were prepared from 99.997 pct Pb, 99.999 pct Sn, and 99.999 pct Sb, being melted by an electric furnace in a graphite crucible and poured into graphite molds. Several density specimens of the same nominal size were machined from each ingot, and, by comparing specimen weights, relative differences in specimen composition resulting from segregation in the ingots could be detected. In this way, segregation was found to have occurred in Pb-Sb alloys at compositions beyond the eutectic (11.2 pct Sb) and this

Jan 1, 1969

By R. I. Garrod, R. A. Coyle

The shapes and positions of X-ray reflections from specimens of copper, steel, and aluminum alloy haue been examined in the elastic and plastic ranges both while the specimen was under stress and in the unloaded condition. For the aluminum alloy the shape was unaltered by the application of stress either within the elastic limit or in the plastic range provided that no additional plastic strain was induced. In copper the broadening accompanying plastic deformation was very slightly reduced when the specimen was unloaded. A similay but more marked elastic component of broadening was also found for steel, but in this case below the yield stress. Line profiles corrected for instrumental and particle-size broadening indicate very large internal stresses in local regions of the plastically deformed metals. The results are discussed in terms of a recent suggestion that the heterogeneous dislocation distribution between the cells and their boundary walls plays a major role in the peak shifts and broadening of the X-ray reflections. STUDIES of the X-ray line profiles from strained polycrystalline aggregates concentrate usually on one or the other of two main parameters: a) the displacement of the peak of the intensity contour from its position for a strain-free aggregate, or b) the shape of the profile. From peak shifts data can be obtained either on the relation in both the elastic and plastic ranges between applied external stress and average lattice strains in a given (hkl) direction, or, alternatively, on the residual lattice strains which are present after a plastically deformed specimen is unloaded.' On the other hand, the shapes of the broadened profiles from cold-worked metals can be analyzed to separate the broadening produced by small particle size and by heterogeneous lattice strains.' In this paper the terms "size broadening" and "strain broadening'' are used in the general sense adopted by warren.' In the past, apart from two early qualitative observation, it has been customary to examine only the movements of the peaks of the profiles while the specimen is actually under load, since the line broadening induced by plastic strain remains after removal of the external stress. Consideration of the implications of existing data of this type suggests, however, that fruitful additional information on a number of fundamental aspects might be gained by careful examination of whether the X-ray line profile is in fact different in the loaded and unloaded states of the specimen. By taking advantage of the sensitivity and convenience of modern diffractometer techniques it is possible to explore with relative ease the magnitude and importance of any elastic effects which may be superimposed upon the well-known permanent changes in profile. The main aim of the work to be described was thus to investigate this point for typical metals and alloys. For this purpose annealed specimens were extended first elastically and then plastically and the positions and shapes of X-ray reflections were recorded. Initially it was anticipated that prime interest would center on observations within the plastic range; it has been found, however, that small changes in profile sometimes occur both before and after the nominal elastic limit of the material is reached. It is shown that the results obtained have important implications in relation to the structural changes and processes associated with deformation. I) EXPERIMENTAL To enable the diffraction lines to be recorded while the specimen was under uniaxial-tensile stress, a small hydraulic testing machine was designed and constructed for direct attachment to the goniometer of a Philips diffractometer. The specimens, which were machined from 1/2-in.-diam rod and had a central rectangular section 3/8 by 1/16 in. over a gage length of 1 in., were held in the machine by split collets mounted in grooves in the cylindrical ends of each specimen. No special precautions were taken to ensure precise axiality of loading. Constant oil pressure was maintained by a lever and weights system and transmitted to the loading rig by flexible pipe. The actual load on the specimen was measured by a load cell in the machine to an accuracy of * 1 pct. To enable smooth X-ray profiles to be obtained the specimen and machine were oscillated continuously during recording through *7-1/2 deg about the normal half-angle position of the goniometer. The three materials chosen for the investigations were high-purity copper as representative of a ductile fcc metal, a low-carbon steel for a bcc metal, and an aluminum alloy as a material in which the proof stress/ultimate strength ratio is high. Details are as follows. a) Copper. 99.999 pct purity. After machining the specimen surface was polished mechanically and

Jan 1, 1964

By Joseph B. Story, John T. Clarke

A modification, of the Kelvin bridge using an inductor was used to measure the conductivities of molten sodium chloride, calcium chloride, and mixtures thereof. A capillary-type four-lead fused quartz dipping cell was constructed. The effect of a small amount of potassium chloride on the conductivity of the melt was determined. IN the electrowinning of sodium and chlorine from sodium chloride in Downs cells, calcium chloride is added to the sodium chloride in an approximately equimolar amount to permit cell operation at a lower temperature. This lower temperature improves current efficiency and ease of operation, but decreases voltage efficiency by decreasing the electrical conductivity of the melt. A knowledge of the electrical conductivity of the Downs cell melt is necessary to the understanding of Downs cell operation, for the IR voltage drop across the melt is responsible for a significant part of the electrical power consumed by the cell. The work of previous investigators on fused sodium chloride-calcium chloride mixtures was reviewed from the standpoint of consistency with the results of others on the conductivities of the pure constituents. The electrical conductivity of pure fused sodium chloride has been established with accuracy by Van Artsdalen and Yaffe,1 by Edwards, Taylor, Russell, and Maranville,2 and by Lee and Pearson.3 It has also been studied by a number of other investigators.4-13 The best values for calcium chloride are believed to be those of Lee and Pearson,3 since the sodium chloride and potassium chloride conductivity values given by them check the best literature values. A number of other investigators have also reported values for calcium chloride.'-"."' Electrical conductivity data for fused sodium chloride-calcium chloride mixtures have been reported by Sandonnini,12 Vereshchetina and Luz-hnaya,18 Ryschkewitsch,11 Barzakovskii,5 and Alaby-shev and Kulakovskaya.15 Sandonnini reports no data at temperatures lower than 850°C. The conductivity values reported by Vereshchetina and Luz-hnaya, by Ryschkewitsch, and by Barzakovskii for pure sodium chloride and for pure calcium chlor- ide vary somewhat from the literature values believed to be best and the sodium chloride-calcium mixture data of these authors and of Alabyshev and Kulakovskaya (who give no data for the pure compounds) show significant variations. In view of these facts, it seemed that an investigation of the electrical conductivities of fused sodium chloride-calcium mixtures would be worthwhile. Apparatus Bridge System—The bridge used,in this investigation is diagrammed in Fig. 1. In general, the elaborations of this bridge over the simple Wheatstone bridge were for the purposes of a) eliminating lead resistances or making them accurately measurable, and b) eliminating major capacitative and inductive effects or balancing them against each other. Lead resistances in the lower arms of the bridge were kept as low as possible by making the leads short and of low resistance wire. This could not be done in the cell arm of the bridge because of the remoteness of the cell from the other bridge components and because of the high-resistance nickel or chrome1 wires used in the cell. Since maximum sensitivity is attained when the resistances of the four arms of the bridge are equal, 50-O resistors were used in the lower arms of the bridge when fused salt conductivities were being measured, and 1000-O resistors were used when the cell was being calibrated with normal aqueous KCl solution. The cell resistance was of the order of 50 ohms with fused salts and of the order of 1000 ohms with normal aqueous KC1 solution. The resistors used were non-inductive and accurate to 50.05 pct (General Radio Co. Types 500-C and 500-H). The lead resistance between point A in the cell and point E at the measuring resistor was eliminated by using the kelvin bridge principle; that is, the voltape drop across the lead from point A to point E was divided between the cell arm of the bridge and the measuring arm of the bridge in proporation to the resistaxes in the lower arms of the bridge.

Jan 1, 1958

By M. Cohen, S. A. Kulin

AT a recent symposium on thermodynamics in physical metallurgy1 two opposing theories of the austenite-martensite transformation were presented. Both theories agreed that this type of reaction involves a nucleation process which requires activation and that the activated nuclei develop into the well-known martensite plates with tremendous speed. However, there were essential differences in the two points of view concerning the nature of the nucleus and the mechanism by which the nucleus propagates. According to Cohen, Machlin, and Paranjpe,' the nucleus is a strain center with sufficient elastic energy to initiate a cooperative displacement among the atoms of the parent phase when a sufficiently low temperature is reached. This displacement propagates as a wave in shear-like fashion to transform the austenite into martensite without benefit of diffusion. On the other hand, Fisher, Hollomon, and Turnbull3 regard the nucleus as a solute-poor region (in the austenite) of a size which becomes supercritical relative to coherent growth into martensite when an appropriately low temperature is reached. This growth process is taken to be an atom-by- atom transfer from the receding austenite lattice to the advancing martensite lattice through the coherent interface that exists between the two phases. The present paper is not conceded with the divergent views as to the nature of the nucleus but describes some critical experiments which differentiate between the two proposed mechanisms of propagation. Fisher' has summarized the latter issue in the following way: According to the cooperative displacement theory, the speed of formation of mar-tensite plates should not be decreased by lowering the temperature, and martensite should form with extreme rapidity at very low temperatures; whereas with the alternate growth process, the speed of the martensite transformation should be retarded at very low temperatures, decreasing to zero at the absolute zero. The atom-by-atom growth mechanism predicts a marked slowing down of the reaction rate with decreasing temperature because the rate of self-diffusion in the austenite is involved in this picture. For example, Fisher, Hollomon and Turn-bull5 estimate that the activation energy for this growth process in steel is (0.34)2(0.36)* times the activation energy for self-diffusion in y-iron. The two most recent determinations of the latter quantity are 67,900" and 74,2007 cal/mol, which may be averaged as 71,000 cal/mol. This, in turn, gives a value of 3000 cal/mol for the activation energy of the atom-by-atom process, and hence the rate of growth should vary as e 8,000/RT where R is the gas constant

Jan 1, 1951

The research project on size reduction, sponsored by the mining industry through financial support from individual companies, is now embarking on a second three-year program. The first 3-year program had as its objectives assimilation of the literature on comminution and development of simulation programs encompassing the basic mechanisms of grinding. This involved investigating conditions under which a particle in a mill is captured, the stress to which it is subjected, its break probability, and the resulting particle size distributions. The results were used to obtain the most representative simulation models based on current knowledge of mechanisms. As part of this work a set of computer programs has been developed for the following cases: . Batch mill, by numerical integration for completely general selection and breakage functions. . Continuous open-circuit mill by same method as above. . Continuous open-circuit mill by general numerical integration method, including transient behavior

Jan 1, 1969

By J. T. Duce

In viewing the petroleum world as a whole certain tendencies arc to he noted. The first of these is of a legal and political nature. It involves the nationalization of the oil industry; in some instances going into all its phases and in others with reference simply to production.

Jan 1, 1928

By Raymond C. Johnson

GASIFICATION is important to the anthracite industry, as it is to the entire solid-fuel industry and to the nation. However, to the anthracite industry it may have particular significance in that it would increase the market value of many millions of tons of a by-product fuel, which the industry now has in storage and is currently producing, in addition to increasing the potential market for all its products. The by-product fuel is of usable quality but the ash content is higher than it can be in other products and therefore it must be converted or used at the point of production. Gasification is one method by which the product may be given increased value. The inherent characteristics of anthracite make it well suited for producing a fuel or synthesis gas. It is the most concentrated form of natural commercial carbon, noncaking and noncoking; it does not produce smoke, tar, or soot and has a low sulphur content; and the volatile matter, which ranges between 2 and 8 pct, is 80 to 85 pct hydrogen with small amounts of methane, carbon dioxide, carbon monoxide, and nitrogen. The ash fuses at high temperatures, which allows it to be burned at high rates without slagging. However, with the addition of small amounts of dolomite, the ash will form a slag, or glass, which is very fluid. Anthracite has long been used in the manufacture of city gas and it is extensively used in various parts of the country to make water gas to be converted to hydrogen. Buckwheat and rice anthracite are used in Galusha producers to make producer gas. Excellent synthesis gas has been made in a Galusha producer with rice and barley anthracite with oxygen in tests at the Consolidated Mining and Smelting Co., Trail, British Columbia. In these tests, anthracite was shown to have advantages over competitive fuels, in that the gas had a higher hydrogen content and could be cleaned with less difficulty. The anthracite seams are steeply pitching and in mining the parting strata and some of the roof and bottom materials are taken with the coal. In preparation, these materials are separated by gravity from the commercial product and stored in refuse banks. This refuse contains a mixture of rock, slate, or shale, and high-ash anthracite with bone coal, which is low-ash coal that is interspersed with thin bands of shale. The bone coal contains between 25 and 50 pct ash with an average ash content of approximately 30 pct, with a

Jan 1, 1953

EUGENE COSTE, ? Calgary, Alta.-Evidently in Argentine they have a petroliferous province just east of the Andes where very much the same conditions exist as are found on the east side of the Rocky Mountains and in the plains adjacent. It strikes me, though, that the same mistake is being made in Argentine in the exploration for oil as was made in Alberta, Canada; viz., drilling the wells too .near the seepages in the belt in the eastern part of the petroliferous province, too near the mountains. This same mistake was made in Alberta, with disastrous results; viz., only fissure production was found. The strata so near the mountains are tilted at a very strong angle, such as is described in this paper, and the dislocations are intense. On the other hand, we have found that when we get 100 or 200 mi. away from the mountains we get into oil and gas belts which are very prolific. So far our fields in Alberta have been gas, but in Wyoming, as you know, they get many thousands of barrels a day. I have no doubt that conditions in Argentine are exactly similar but that they have so far kept too near the mountains and that they want to explore the belts farther east to obtain better results.

Jan 4, 1919

By Horace V. Winchell

The St. Helens mining-district, indicated in sketch-map, Fig. 1, is chiefly in Townships 9 and 10 North, Ranges 5 and 6 East of the Willamette meridian, in Skamania county, Wash. There is no railroad or even a wagon-road at present connecting it with any base of supplies; access is usually by wagon-road for about 50 miles from the town of Castle Rock to Spirit lake, and from that point by pony-trail from 6 to 10 miles farther. History. Nearly 20 years ago two German farmers, totally inexperienced in prospecting, penetrated this region upon a hunting-and fishing-trip. Their attention was drawn to numerous joints and crevices filled with black, glistening tourmaline, and con-

Jan 1, 1913

By Harry M. Callaway

IN times of a falling metal market the mine operator attempts to remain in competition by lowering his overall cost and raising the grade of ore he processes. But these adjustments can be made only within narrow limits imposed by inherent characteristics of the operation. Is there some additional method whereby the break-even point can be lowered? One approach, perhaps the only one, to lower a break-even point is careful cost analysis considering both fixed and variable costs in relation to mining rate. The following is an analysis of cost distribution and its significance in determining the most economic combination of the factors of ore grade and tonnage output applicable to a given mining operation.

Jan 4, 1958

By W. L. Austin

The only essential difference among the three methods of collecting the precious metals from their low-grade ores by fusion is comprised in the nature of the vehicle in which those metals are concentrated. If lead- or coppper-ores are used, the processes are respectively lead- or copper-smelting; but when the sulphide of iron forms the matrix in which the gold and silver are collected, the process is known as pyritic smelting. The latter method presents rarely any advantages when lead- or copper-ores are available at rates which permit profitable treatment. Pyritic silver-smelting, defined by Percy as " the smelting of silver-ores, which are either free from lead or do not contain it in sufficient quantity to collect the silver, in conjunction with pyrites, in order to produce a regulus in which the silver may be concentrated," is not, as the name would imply, confined to ores of this metal alone, but embraces auriferous silver-ores, or even gold-ores simple. This method of collecting the precious metals from lowgrade dry ores, employed at Freiberg by Barthel Kohler in 1585, does not appear, up to the present, to have been introduced into this country on a working scale. And yet the possibility of getting rid in a single operation of all the earthy or siliceous gangue of a lowgrade ore and concentrating the precious metals in a matte without loss of lead (which includes gold and silver) by slagging, or volatilization, at the same time producing a highly siliceous slag, very nearly if not quite as clean as is usual in lead-smelting, certainly commends itself. In some parts of the country, owing to the com-

Jan 1, 1888

By Edwin R. Phelps

In the year 1900 about 212 million tons of bituminous coal were produced in the United States. Almost none of this was produced by surface mines (Fig. 1), because there was no large equipment suitable for stripping overburden at that time. By 1915 the surface mines had built up their capability largely through use of the steam shovel to the point that they produced 2.8 million tons of the nation's total production of 443 million tons. Over the intervening years between 1915 and 1970 surface mining provided a continually increasing percentage of the nation's bituminous coal, stimulated by the growing availability of giant surface mining machines, some of which are presently capable of removing 220 cu yd of earth with one bite of their mighty buckets. In 1970 the nation's surface mines produced 244 million tons of bituminous coal, over 40% of the total national production. On the other hand, the nation's underground mines hit a peak of 560 million tons in 1920, dropped to a low of 273 million tons in 1961, and are presently on a very slow rise. Environmental pressures generally oppose surface mining, and have forced coal companies to consider more underground mining in future planning. Also, since strippable reserves are decreasing in the eastern states, an increase in underground mining is expected over the coming years. However, in the western states there are enormous reserves to be extracted by surface methods. Why has surface mining increased, while underground mining has decreased? It's largely a matter of economics. The cost per ton is greatly reduced by surface mining because of the relative ease of obtaining the coal. Also, there is a much greater percentage of coal recovery-nearly 85% in surface mines within the minable area, as compared to an average of about 50% in underground mines. Much surface mining recovers coal that could not be extracted by underground methods because of coal bed thinness, or multiple beds close together, split seams, the nature of the roof, and other geologic conditions. What are some of the limitations of surface mining? First of all, with presently available machinery it is difficult to surface mine at depths

Jan 1, 1973

By Joseph G. Debanné

Foreword The three case histories and the liquid fuels planning scenario presented in this paper span a twenty year period, from the pioneering days of computers in the petroleum producing industry during the mid-fifties, to the energy crisis era of the seventies. Inasmuch as two of the main actors, Ian McKinnon and I, are featured in all three case histories, while I am currently involved in the fossil fuels scenario, this paper provides four related and personal spot readings along an evolutionary path: from the one dimensional technical domain to the multi-dimensional techno-socio-economic domain of computer applications in the petroleum industry. Coincident with this evolution in the direction of increasingly comprehensive and powerful computer applications, the evolution in hardware/software capability and in analytical power are also kept in perspective. The three case histories are: 1. The Bonnie Glen-Wizard Lake Case (Calgary, Alberta, 1955-1957); 2. The TransCanada-Great Lakes Gas Transmission Case (Ottawa-Washington, 1966); 3. The Westcoast Transmission - El Paso Pipelines Gas Export/ Import Case (Ottawa-Vancouver-Washington, 1966-1967). The liquid fuels planning scenario is a demonstration exercise rather than a case history; however, it represents an important point on the evolutionary curve and, provides a concrete example of tech-

Jan 1, 1977

By Y. C. Liu, R. H. Richman

The effects of gel,manium and tin on the deformation and 9-e-crystallization textures of copper have been explored in detail with in the copper-rich terminal solid solutions. Addition of solute to copper produces a change in deformation texture from the copper type to the 70 :30 brass type. This transition has been measured quantitatively The types mid proportions of recrystal-lization components have been determined as a function of com-position, and correlation of recrystallization components with specific deformation components is discussed. On the basis of information available in the literature, it has been suggested that the effect of solute elements on the recrystallization texture of copper

Jan 1, 1961

By A. J. Jacobs

THE purpose of this note is to draw attention to a set of tables, recently compiled in Rocketdyne Research Report No. 64-19, under the title "Crystal-lographic Data for Indexing Cubic Twin Reflections and Cementite (Fe3C) Reflections in Electron Diffraction Patterns."' These tables were an outgrowth of electron-diffraction work conducted over the past several years on steels, precipitation-hardening aluminum- and nickel-base alloys, molybdenum, tantalum, and tantalum-base alloys. The first table lists the indices of possible twin reflections for all the possible twinning planes in bcc and fcc lattices. The twin reflections correspond

Jan 1, 1965

By B. D. Cullity, K. S. Sree Harsha

When a copper or aluminum single crystal is swaged into wire, the resulting deformation texture depends on the original orientation of the crystal. The<100> and <111>orientations me essentially stable, while <110> is unstable. The greater the <100> content of the deformation texture, the stronger the wire is in torsion. the greater the<111>content, the stvonger it is in tenszotz. The preferred orientation (texture) of fcc wires, either after deformation or recrystallization, is usually a double fiber texture in which some grains have <100> parallel to the wire axis and others have <111>. The relative amounts of these two texture components, as reported by different investigators for the same metal, vary considerably. Previous work in this laboratory&apos; has shown that the starting texture of a wire, i.e., the texture which it has before deformation, can have a decided influence on the texture produced by deformation. In particular, it was found that the deformation texture of copper wire is essentially a single <100> texture, if the wire before deformation contains only a <100> component. This is true even when the deformation is carried to more than 98 pct reduction in area. This paper reports on further studies of the role played by the starting texture. Copper and aluminum single crystals of various orientations have been cold swaged into wire, and quantitative measurements of the resulting deformation textures have been made. The tensile and torsional properties of the deformed wires have also been measured, and the relation between these properties has been correlated with the texture of the wire. These measurements were made in order to demonstrate that a cold-worked wire can be made relatively strong in torsion and weak in tension, or vice versa, by proper selection of the texture before deformation. MATERIALS The copper was of the tough-pitch variety, containing, by weight, 99.962 pct Cu, 0.003 pct Fe, 0.025 pct 0, and 0.0021 pct Si. The aluminum contained more than 99.99 pct .&apos;41; the only reported impurities were 0.001 pct Fe, 0.001 pct Si, and 0.003 pct Zn, by weight. Large single crystals of these metals were grown by the Bridgman method in graphite crucibles and a helium atmospliere. Cylindrical specimens of predetermined orientation, about 1.5 in. long and 0.36 in. in diameter, were machined from the as-grown crystals and then etched to 0.25 in. to remove the effects of machining. Their orientations were checked by back-reflection Laue photographs, and they were then swaged to a diameter of 0.050 in. (96 pct reduction in area). 111 order to study the "inside texture" of the deformed wires, they were etched, after swaging, to a diameter of 0.040 in. before the texture measurements were made. TEXTURE MEASUREMENTS The fiber texture which exists in wire or rod can be represented by a curve showing the relation between the pole density I, for some selected crystal-lographic plane, and the angle $ between the pole of that plane and the wire axis (fiber axis). Such a curve will show maxima at particular values of , and these values disclose the texture components which are present. The relative amounts of these components can be determined2&apos;3 from the areas under the maxima on a curve of I sin F vs F. It is seldom necesszlry to measure I over the whole range of F from 0 to 90 deg, since the existence of maxima in the low-F relgion can be inferred from measurements confined to the high-F region. The X-ray measurements were made with a General Electric XRD-5 diffractometer and filtered copper radiation, according to one or the other of the following procedures: 1) A method developed in this laboratory,4 involving diffraction from a single piece of wire. 2) A modification of the Field and Merchant method.5 This method was originally devised for the examination of sheet specimens, but it can easily be adapted to the measurement of fiber texture. Three or four short lengths of wire are held in grooves machined in the flat face of a special lucite specimen holder. The axes of the wires are parallel to the plane defined by the incident and diffracted X-ray beams, and the holder to which the wires are attached can be rotated step-wise about the diffractometer axis for measurements at various angles 9.

Jan 1, 1962