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By T. L. Joseph

Blast furnaces are most efficient thermally when the CO2 in the top gas is highest. Oxygen introduced in the air blast is converted to CO in the combustion zones. The extent to which CO, generated in front of the tuyeres, is converted later to CO2 depends upon the ratio of ore to coke in the charge and the degree to which CO2, formed by reduction of iron oxides with CO, reverts to CO by the secondary reaction C + CO2 = 2CO. About 300 to 400 lb. of carbon' per ton of pig iron is normally involved in the solution-loss reaction or direct reduction of FeO with carbon, which produces the same over-all results; that is, lower CO2 in the top gas. Rich2 has recently reported a reduction in fuel consumption at slower rates of blowing on two furnaces in spite of higher heat losses per ton of iron. Lower fuel consumption at slow operating rates was due to more complete reduction of the ore that resulted in higher CO2 in the top gas and consequently more efficient use of carbon. Kinney3 has reported substantial savings in fuel as a result of crushing and sizing the ore charge. Improvements in practice brought about by sintering magnetite concentrates, flue dust and fine ores have been due to the establishment of conditions favoring more complete reduction of the ore in the upper part of the furnace. The extent to which oxides and fluctuations in composition in pig iron affect the quality of steel and finished product needs further study. There is evidence that more thorough preheating and reduction of the ore in the upper part of the furnace tend to give a better quality of iron. Bogatzkii4 found from laboratory work that the amount of oxygen entering electrolytic iron, melted under various slags, was directly proportional to the concentration of free FeO in the slag and inversely proportional to the basicity of the slag. Herty and Gaines5 concluded that the silicate content of open-hearth steel before deoxidation is related to the concentration of silica in the pig-iron charge, indicating that most of the persistent inclusions are silica from the iron. They also found that

Jan 1, 1936

Jan 1, 1925

By James Gayley

(Presented at the Washington meeting, May 3, 1905, and simultaneously sent to the Iron and Steel Institute, for presentation at the meeting of that Society in London, May 11, 1906.) It is to be regretted that the data respecting the use of dry-air blast, which were presented to the Iron and Steel Institute at its meeting in the United States, in October, 1904, should have been restricted to the period from August 25th to September 9th inclusive, and from September 17th to 30th inclusive. In order to present the paper at all it was found necessary to limit the record of operations to the period above stated. It appears from the reported discussion that some of those who took part felt themselves to be at a disadvantage, in considering the economies secured through the use of dry-air blast, by reason of the fact that the data presented covered so short a period. It is the purpose of this communication to present in detail the record of operations of the Isabella Furnaces from November, 1904, to March, 1905, inclusive, as shown by the furnace-records. The month of October, 1904, is not included, as the furnace using dry-air blast was stopped several times for repairs; and while the record was a very good one considering these interruptions, yet it was not a continuous one. The record for Furnace No. 1 using dry-air blast, and the comparison with Furnace No. 3 using natural air for the month of November, 1904, is set forth in Table I. By a reference to my former paper it will be noted that the month of November is the beginning in this country of the winter period, when the atmosphere decreases rapidly in humidity. The month of October being the transition month in the autumn and April in the spring, and furnaces using natu-ral air approach more closely, from November on, to the conditions obtained by the use of dry-air blast. The data given in

Jan 1, 1906

By Maurice Ewing, L. Don Leet

Assuming that wave velocities in seismic prospecting increase as a continuous linear function of the depth, the authors have derived formulas for computing, from two time-distance observations, the amount of velocity increase, depth of penetration and a graphical determination of the path of the vibrations, and have discussed the ground, reflected and refracted waves. The application of the formulas is illustrated numerically. Earlier Investigations Observations of the energy propagated from the center of an earthquake disturbance have been used to give information about the velocities and paths of elastic waves in the interior of the earth. One method of accomplishing this depends on the use of the times of transmission. Herglotz(7) § and Bateman(3) obtained a solution of the integral equation involved, which determines the velocity of propagation at any point as a function of the distance from the center of the earth, with no assumption as to the manner in which the velocity of the disturbance varies with depth below the earth's surface. The expressions on which the value of the time and the form of the ray of propagation depend contain an unintegrable definite integral, involving the velocity as an unknown function of the distance from the center of the earth. Wiechert and Zoppritz(15) obtained a manageable form for this function by assuming a law of variation which required a constant curvature form for the path within each of a succession of concentric spherical layers of the earth. C. G. Knott(9) worked out the problem for the first time by an absolutely rigorous method from the data of observation (Zoppritz-Turner tables), without making any assumptions as to the functional relationship connecting the speed of propagation and the distance from the earth's center. His method is a numerical solution of an integral equation, giving each velocity and the corresponding distance from the center of the earth in figures.

Jan 1, 1932

Shoveling ore cost so much at Tyrone during the year 1917 that it was deemed advisable to conduct tests to see where the fault lay. These tests were in the nature of time studies and extended over a period of very nearly a year. No data were available on this work to supply a starting point, so it was necessary to begin in a very elementary way, to find out the capacity of the average Mexican laborer. To' obtain a basis for comparison, it was necessary to determine the capacity of various types and sizes of shovels, so as to know whether the 21-1b. (9.5-kg.) load was the best load underground as well as on surface. A list of essential factors influencing shoveling was also made out during the course of a short series of preliminary time studies, and the motions involved in shoveling were analyzed and subdivided for convenience in studying. The necessary forms and record sheets were also decided upon at this time. A second short series of tests was then conducted on the surface, so as to be able to estimate the negative effects of underground work on the shovelers, and to minimize, as far as possible, the need for studying obviously poor types and sizes of shovels under the difficult conditions to be encountered in the mine. The test work underground consumed by far the greater proportion of the time and was divided into three series: Shoveling directly into a chute; shoveling into a wheelbarrow and tramming to a chute; and shoveling into a car and tramming to a chute. In each series the following points were determined for various lengths of time worked: Number of shovelfuls handled per minute, effect of distance thrown on shoveling speed, amount of rest required, amount of time consumed in tramming and dumping, proportion of working day occupied in shoveling, total tonnage handled during various working periods, effect of distance on tonnage handled during the day.

Jan 2, 1919

By R. H. SWEETSERS

A Discussion of Mr. Hall's paper, read at the Washington Meeting, February, 1905. R. H. SWEETSER, Sault Ste. Marie, Ont. (communication to the Secretary*) :-The recent work of furnace No. 1 of The Algoma Steel Co., at Sault Ste. Marie, Ontario, using for fuel, first all charcoal, then a mixture of charcoal and coke, and finally all coke, upsets the estimates given by Mr. Hall in the last two paragraphs of his interesting paper. Furnace No. 1 was built for a charcoal-furnace, and it was run on charcoal fuel from March 6 until July 9, 1905; then, for a week, a mix¬ture of charcoal and coke was used, and, since then, coke alone has been the only fuel. It is to be regretted that at no time, during the run on charcoal, was there enough charcoal on hand and " in sight'" to warrant blowing the furnace as hard as it should have been blown. During April and May the supply of charcoal limited the amount of blast to about 8,000 cu. ft. of air per min.; in June, to about 8,900 cubic feet. For a few days in July about 10,000 cu. ft. were blown, and then the maximum daily output, 173 tons (2,240 1b.), was reached. At all times the quality of the charcoal was poor, having been made from wood cut from three to four years before. Doubtless this furnace could have produced .200 tons of iron per day, even with this quality of charcoal, provided the supply had been sufficient; and with good charcoal I see no reason why it could not make as much iron per day as it has made with coke. During the one week of using a mixture of charcoal and coke, the changes in quantity of blast and composition of the slag followed each other so closely that no single condition could last long on the furnace. The results were good, and the pig-iron was about the same in quality as that made during the

Jan 1, 1906

By O&apos, R. G. Meara, B. W. Gandrud

In 1034 the Southern Experiment Station of the U.S. Bureau of Mines in cooperation with the University of Alabama began an investigation of the availability of kyanite ores as a source of raw material for the manufacture of refractories. Under this program, gravity concentration and flotation tests have been made on two varieties of Georgia kyariite ore, mica schist and massive. Most of the attention has been directed to the mica schist ores, as they are more widely distributed and seem to offer greater economic possibilities than the massive ores. It is evident that the preparation of kyanite for use as a refractory material involves other considerations than the mere elimination of impurities. A concentration process that eliminates impurities satisfactorily may have to be followed by some additional treatment, since the final product must be of a coarseness and size ratio that will make it suitable for refractories manufacture. So far in the investigation at the Southern Experiment Station of the U.S. Bureau of Mines only the concentration problem has been considered, and this paper is intended as an interim report. Ores The schist ores contain 1 to 9 per cent of kyanite crystals embedded in mica and quartz, with smaller amounts of graphite, garnet and iron oxide and minor amounts of other heavy minerals. The garnet content varies from a trace to a few per cent. The minerals are easily released by moderate grinding. The size of the kyanite ranges from fine needles to crystals 1 1/2 in. long, 1/2 in. wide and 1/4 in. thick. The garnet, quartz and iron oxide grains have a smaller mean mesh than most of the kyanite. The maximum size of the garnet crystals corresponds to about 14 mesh and that of the sand grains is considerably less. Most of the iron oxide is still finer, for the minus 100-mesh size is greatly enriched in Fe²O3. The massive ore consists of radiating masses of kyanite interlocked with quartz, mica, corundum and small amounts of other heavy minerals.

Jan 1, 1938

By B. W. Gandrud, R. G. Meara, O&apos

In 1034 the Southern Experiment Station of the U.S. Bureau of Mines in cooperation with the University of Alabama began an investigation of the availability of kyanite ores as a source of raw material for the manufacture of refractories. Under this program, gravity concentration and flotation tests have been made on two varieties of Georgia kyariite ore, mica schist and massive. Most of the attention has been directed to the mica schist ores, as they are more widely distributed and seem to offer greater economic possibilities than the massive ores. It is evident that the preparation of kyanite for use as a refractory material involves other considerations than the mere elimination of impurities. A concentration process that eliminates impurities satisfactorily may have to be followed by some additional treatment, since the final product must be of a coarseness and size ratio that will make it suitable for refractories manufacture. So far in the investigation at the Southern Experiment Station of the U.S. Bureau of Mines only the concentration problem has been considered, and this paper is intended as an interim report. Ores The schist ores contain 1 to 9 per cent of kyanite crystals embedded in mica and quartz, with smaller amounts of graphite, garnet and iron oxide and minor amounts of other heavy minerals. The garnet content varies from a trace to a few per cent. The minerals are easily released by moderate grinding. The size of the kyanite ranges from fine needles to crystals 1 1/2 in. long, 1/2 in. wide and 1/4 in. thick. The garnet, quartz and iron oxide grains have a smaller mean mesh than most of the kyanite. The maximum size of the garnet crystals corresponds to about 14 mesh and that of the sand grains is considerably less. Most of the iron oxide is still finer, for the minus 100-mesh size is greatly enriched in Fe²O3. The massive ore consists of radiating masses of kyanite interlocked with quartz, mica, corundum and small amounts of other heavy minerals.

Jan 1, 1938

By L. H Levenson, Charles S. Barrett

The orientation of metal crystals and grains, both large and small, can be detcrmined conveniently and accurately without the use of X-ray apparatus. This seems to be appreciated by so few metallurgists that it may be useful to explain in detail the method we have found most satisfactory in the laboratory—the reflection of light from crystallographie etch pits. This note includes a description of a suitable inexpensive instrument and instructions for etching various metals and for plotting the data. As the stereographie projection is used to facilitate handling the data, this note may he considered as an appendix to an earlier review of the metallurgical uses of the stercographie projection.' Various methods involving etch pits have been used by other investigators. Bridgman's method2 consists of attaching the specimen to a sphere (a transparent sphere is convenient4 , holding it at arm's length, and marking a spot on it when it has been turned so that the eteh pits reflect light into the eye of the observer from a lamp standing behind him. It has an accuracy of about 2" and is extrernely rapid. A greater accuracy can be obtained by having the reflected light fall on a screen, as has been done by Czochralski,5 Chalmers,6 and Schubnikov.7 All of these methods have been intended for undeformed single crystals. Tammann and his coworkers3,8 developed a method for estimating the number of grains in a polyerystalline aggregate having orientations in a given region of the stereographic triangle and thus obtained statistical information about deformation and reerystallization textures. While the method has had some use in recent years,9 it is not applicable to the majority of problems in physical metallurgy. Smith and Mehl10 determined orientations by plotting the directions of the sides of individual etch pits on a stereographic projection. The accuracy is limited to about 3" and the method requires careful polishing and high magnification.

Jan 1, 1940

By Charles S. Barrett, L. H. Levenson

The orientation of metal crystals and grains, both large and small, can be detcrmined conveniently and accurately without the use of X-ray apparatus. This seems to be appreciated by so few metallurgists that it may be useful to explain in detail the method we have found most satisfactory in the laboratory—the reflection of light from crystallographie etch pits. This note includes a description of a suitable inexpensive instrument and instructions for etching various metals and for plotting the data. As the stereographie projection is used to facilitate handling the data, this note may he considered as an appendix to an earlier review of the metallurgical uses of the stercographie projection.' Various methods involving etch pits have been used by other investigators. Bridgman's method2 consists of attaching the specimen to a sphere (a transparent sphere is convenient4 , holding it at arm's length, and marking a spot on it when it has been turned so that the eteh pits reflect light into the eye of the observer from a lamp standing behind him. It has an accuracy of about 2" and is extrernely rapid. A greater accuracy can be obtained by having the reflected light fall on a screen, as has been done by Czochralski,5 Chalmers,6 and Schubnikov.7 All of these methods have been intended for undeformed single crystals. Tammann and his coworkers3,8 developed a method for estimating the number of grains in a polyerystalline aggregate having orientations in a given region of the stereographic triangle and thus obtained statistical information about deformation and reerystallization textures. While the method has had some use in recent years,9 it is not applicable to the majority of problems in physical metallurgy. Smith and Mehl10 determined orientations by plotting the directions of the sides of individual etch pits on a stereographic projection. The accuracy is limited to about 3" and the method requires careful polishing and high magnification.

Jan 1, 1940

By Y. S. Bonillas

Page I. Introduction.......................... 286 II. Physiography.......................... 286 : 111. Introductory Geology...................... 287 IV. Rocks of the District ...................... 288 (A) Sedimentary Rocks..................... 288 Pinal Schist ........................ 288 Bolsa Quarteite....................... 289 Abrigo Limestone...................... 290 Capping Quartzite..................... 291 Martin Limestone...................... 292 Escabrosa Limestone .................... 295 Naco Limestone....................... 296 Cretaceous Deposits..................... 296 Glance Conglomerate................... 296 Morita. Mural and Cintura Formations........... 297 (B) Igneous Rocks........................297. Pre-Cambrian Granite.................. 297 Pre-Cretaceous Granite Porphyry............. 298 Rhyolite........................301 Other Dikc Rocks.................... 301 V. Structural Geology........................ 304 General Structure of Mule Mountains............. 304 Fault Blocks and Other Divisions............. 304 Igneous Rocks...................... 312 Copper Queen Block..................... 313 Fault Blocks...................... 313 Intrusions....................... 315 Don Luis Block....................... 315 Intrusions and Orebodies................. 316 VI. Geologic History......................... 316 VII. Metamorphism and Mineralization................. 318 General Metamorphism.................... 318

Jan 1, 1917

By Russell Franks

IN recent years a considerable tonnage of the 18 per cent chromium and 8 per cent nickel steels has been used in lightweight high-strength structures that must be resistant to deterioration under atmospheric conditions. These steels are austenitic in character and their strength can best be increased by cold-working. Although a marked increase in tensile strength is obtained, claims have been made that the cold-worked steels do not possess fully satisfactory elastic properties. Under certain conditions, however, this has caused no great concern, because, as explained by Ragsdale,1,2 the cold-rolled steels have been widely applied for construction of lightweight, high-strength trains using spot welding for joining purposes. Ffield3 agrees that the ease with which thin sections of the cold-rolled 18-8 steels can be joined by spot welding is greatly in their favor, but that they would be more satisfactory if higher elastic properties and a higher modulus of elasticity could be obtained. He states that, as far as the mechanical properties are concerned, the straight chromium stainless steel is superior to the cold-worked 18-8 steel, and in order to illustrate, he presented the data of Fig. 1, which also give a stress-strain curve for a low-carbon 13 per cent Cr steel. Ffield? pro-posed that columbium-bearing or titanium-bearing cold-rolled 18-8 steels be given a heat-treatment (preferably for 1 hr.) in the range 400° to 600°C. to precipitate carbides in order to obtain better mechani-cal properties. Discussions by Sutton,4,5 de Ganahl,6,7 8 Krivobok and Lincoln,9 Knerr,10 and Thaden11 have given further information on the properties of the cold-rolled 18-8 steels compared with other materials used in light-weight, high-strength structures. These investigators and others point out that the ultimate tensile strength of the cold-rolled 18-8 steel can be increased to 200,000 lb, per sq. in. or higher; Krivobok et al. indicate that

Jan 1, 1940

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative. Before examining the problem of presplitting, it is first necessary to study the phenomena which occur when an explosive charge is detonated in a borehole. To do this it is desirable to consider the action of the explosion wave separately from that of the expanding gases.l In the theoretical analysis such a separation poses no problems. Experimentally this was accomplished by use of an underwater-spark discharge to generate the stress wave and by pressurized oil to simulate the pressure of the explosion products. The main role of the wave is to generate a densely radially fractured zone around the borehole. The subsequent gas pressure, exerted against the walls of a highly (radially) fractured cavity, generates a quasi-static stress field (henceforth referred to as static stress field). This stress field was found to be the same as that of a pressurized cylindrical "equivalent cavity" with a radius equal to that of the crack tips. Under these conditions the quasi-static stresses become appreciable and cause further extension of the radial cracks. It was further found that, under gas pressure, the longest of the radial cracks would extend first, and extension of two diametrically opposed radial cracks requires the least pressure. From these observations concerning the single shot the transition to a whole series of more or less simultaneous shots, as in presplitting, can readily be made. In the case of multiple shots, as in presplitting, exactly the same effects occur, but at numerous locations and sufficiently close in time that they interfere with

Jan 1, 1968

By Rudolph Emmel

The mines operated by the South American Development Co. are located in the Zaruma mining district of southwestern Ecuador. They are near the old mining town of Zaruma, which is the only important city in the canton of the same name. The district is situated in the upper end of a valley lying between two spurs of the Cordillera, one of which may be considered the Coast Range and the other an intermediate range. The mining camp proper, known as Portovelo, and the plant are 2.4 km. south of Zaruma, on the north bank of the Amarillo River, a tributary of the Tumbes River, which flows southwestward through Peru to the Pacific. Portovelo is difficult of access; it is reached from Guayaquil by means of river steamers and muleback. 'Embarking at Guayaquil, the route is down the Guayas River, across the Jambeli Canal, and up the Santa Rosa River to Santa Rosa, a distance of 177 km. From Santa Rosa, the road or trail follows the Santa Rosa River, then across the summit of the Coast Range into Portovelo, a distance of 74 km.—a two-day trip on muleback. The mining property of the South American Development Co. comprises 297 lode claims and 142 placer claims. The combined lode claims cover an area, roughly rectangular in shape, 9000 m. long from north to south by 4000 m. wide; the northern edge of the rectangle is about 3000 m. north of the central plaza of Zaruma. Mineral lands in Ecuador are held by virtue of an annual tax per claim paid to the central government, no surface rights being included. HiSTOry The Zaruma mine has been worked by white men since 1549, probably before that it was worked by Indians. The followers of Pizarro, led by traces of gold in the sands of the Tumbes River, followed that stream to its source, worked the gold veins that they found and established the city of Zaruma. Among the mines worked by them were th Sesmo, Leonora, Viscaya, and Mina Grande. Only the soft ores at the outcrop were

Jan 1, 1925

By L. G. Huntley

Introduction IN View of the recent advance made in the knowledge of the nature and conditions accompanying the occurrence of oil and gas, and of the recent activity in drilling in Wyoming, Montana, and western Canada, a discussion of the probabilities of obtaining production in such a reservoir as the Dakota sand in general, and in particular districts, is thought by the author to be timely and likely to result in more intelligent operating in certain parts of the territory underlain by this sand. In Canada particularly it is thought that these general considerations have equal if not more significance in a consideration of the oil and gas possibilities of the formations than have the various local conditions.

Jan 6, 1915

By C. W. Vaupell

THE Huitzuco mines lie in north central Guerrero, Mexico; production has been about 90,000 flasks of quicksilver since 1873. Near-surface ores fill extinct mud geysers and the deep deposits are chambered veins, stock-works in brecciated blocks, and replacements in limestone. The epigenetic minerals livingstonite, stibnite and sulphur occur in limestone, gypsum and dolomite through a developed vertical range of 260 meters. The deepest workings expose an increased amount of stibnite, which probably indicates that the lower limit of mercury mineralization is being approached. A resur-gence of heat and water formed geysers over an extended area after the period of mercury mineralization. Mud geysers, which are situated, in the outcrops, contain the secondary mercury minerals, cinnabar and barcenite in the gravel and mud filling the vents. A 150-ton flotation plant is in operation concentrating stope fills that assay 3.0 kg. of mercury per ton. In one open stope, which is more than one hectare in area and 60 m. high, 150,000 tons are available.

Jan 1, 1937

By R. Steinitz, J. L. Orehotsky

An analysis was made of the influence of floating molten zone traversal on the purification of tungsten rods and the effect of this purification on the brittle -to-ductile transition temperature. The major impurities detectable in the original rods, i.e., molybdenum and oxygen, were reduced by zone refining from 30 to 3 Ppm. Changes in the trace amounts of other impurities could not be quantitatively determined since they were below the limit of detection. Tensile tests on 3-mil wires, drawn from these rods and recrystallized to 17,000 grains per sq mm, showed a transition temperature of 60°C for the zone Purified and 175°C for the original material. 1 HE brittle-to-ductile transition temperature is manifest mainly in the bee metals, iron,' molybdenum, chromium,3 tungsten,4 and niobium. Since many of these metals cannot be fabricated at room temperature in a commercially pure annealed poly-crystalline state, a considerable amount of work has been done on evaluating the influence of purification on the transition temperature in order to determine indirectly whether the fabricability of these metals can be improved by removing impurities. Smith and Rutherford8 showed that the transition temperature of iron is lowered significantly by zone purification. Working with chromium, Edwards, Nish, and wain7 found also that purification appreciably lowered the transition temperature. A similar evaluation has so far not been reported for tungsten, probably because of the difficulties in obtaining tungsten in a purified polycrystalline state. carlson8 and, more recently, schadler9 have purified tungsten rods by floating zone traversal, but after zone traversal, their rods were single crystals. To obtain high-purity polycrystalline tungsten, a technique has to be round for transforming the zone-purified single crystal material into a suitable polycrystalline structure. The purpose of this investigation was to obtain zone-purified tungsten in a suitable polycrystalline state and then to evaluate the effect of zone purification on the transition temperature.

Jan 1, 1962

By R. E. Cech

Metallographic observations on hydrogen-reduced nickel oxide crystals suggest that nucleation of nickel occurs at structural singularities in the oxide. The fully reduced structure contains micron-diameter, worm-like voids occupying 40 to 50 pct of the volume. The crystallographic orientation relationships between nickel oxide and nickel resulting from oxide reduction are recorded and discussed. THE process of reduction of oxide to metal is one of considerable complexity involving a chemical reduction reaction, mass transport of reducing agent to the point of reaction and of reaction product away from it, and finally a transformation whereby metal atoms released from the oxide rearrange to form a stable reduced phase. In addition, nucleation of the reduced phase affects the overall reaction kinetics. Thus far only the thermodynamic aspect of reduction has received the attention warranted by the importance of

Jan 1, 1960

By Ray Light, Everett M. White

Numerous articles have been written about the coal miner ; he has been compared with brave men who have gone out to conquer some unknown hazard throughout the ages. Now, however, modern mining is no longer something to be avoided, but a vocation that anyone can be proud of, with remuneration equal to or above that of almost any industry. A concerted effort is being made each day by both the operators of most mines as well as the state and federal inspectors to see that coal mines are as safe or safer than work places in any other industry. How- ever, it is true that mine fires and explosions have occurred in the mining industry since its inception. One of the earliest accurate references to such an occurrence is found in the transactions of the Royal Society of London. In the Colliery Managers' Handbook, 1898, Caleb Pamely writes of an explosion that occurred ,at Fatfield, England in August 1708, resulting in the deaths of 69 persons. He states: "Three of them, viz, two men and a woman, were blown quite up from the bottom of the shaft, fifty-seven fathoms deep, into the air, to a considerable distance from the mouth of the pit." It is interesting to note that women were employed ,as miners in England during that period. In the United States, the first record of coal mined was in 1702 by the Jamestown colonists. In 1786, about 20 years after Pittsburgh, PA was first settled, a charter was granted by William Penn to mine coal on the banks of the Monongahela River. Then in 1803, the first important coal company, the Lehigh Coal Co., was established. From this beginning, the mining industry continued to grow in importance and the first state mining law was formulated in 1870. The Pennsylvania state mining law was followed in 1873 by Ohio's, and in 1876 by Maryland's. A mine explosion at Avondale, PA in 1869 stimulated state legislatures to formulate these early laws. In 1907 near the town of Fairmont, WV, there were, within three days, two explosions resulting in a total of 597

Jan 1, 1981

By John H. Smith, Michael B. Bever

Pure gold was deformed by wire drawing at room temperature and 78°K. After deformation at room temperature, the stored energy and the resistivity increment reached nearly constant levels at high strains, whereas the yield stress continued to increase with strain. After deformation at 78K, the stored energy, the reszstivity increment, and the yield stress were larger than after deformation at room temperature mzd increased continuously with strain. Annealing at THE stored energy and the changes in properties resulting from cold working of Au-Ag alloys by various processes have been the subject of a series of investigations in this laboratory.'-' The work reported here room temperature after deformation at 78°K did not affect the yield stress appreciably. The stored energy, resistivity increment, and Lncrease in yield stress after deformation at room te-lnperature can be explained primarily in lerrns of dislocations while point defects, as well as dislocations, contribute to the changes in these properties after deformalion at 78°K. extends this research to pure gold. The stored energy, the resistivity increment, and the tensile properties after deformation by wire drawing were measured as functions of the strain at room temperature and at 78°K. The effect of the testing temperature and the effect of intermediate annealing at room temperature before testing at 78°K on the tensile properties of gold deformed at 78°K were also investigated. wire drawing made it possible to use a large range of strains, which was desirable because previous work on the deformation of gold had been carried out mainly at relatively small strains.'-l2 Also, wire specimens

Jan 1, 1969