Search Documents

By Joseph E. Worthington

Many thousands of years ago when our earliest ancestor first swung out of a tree, picked up a rock, and threw it at what he hoped might be his lunch, the minerals industry, in a manner of speaking, was born. It was then a very long step indeed to the primitive metal industry of our early civilizations, for we know that precious metals were accumulated and some metal objects were produced several thousand years ago. Prospecting, or "exploration" to use the modern euphemism, consisted of little more than outcrop examination and the use of a gold pan, and it probably did not change much from our earliest civilizations until relatively recent times. In a general sense, all the early explorers of North America were also prospectors, for mineral wealth was certainly one of the goals of the first pioneers and settlers. The earliest pioneers didn't do too badly either, for they discovered copper and iron in various places in the Appalachians and Michigan, gold in the Southeast Piedmont and many mineralized areas in the Southwest. In most places these were outcropping ores or gossans, and the prospecting was incidental to the arduous task of ekeing out a living in a new land. It was the explosive discovery of rich placer gold deposits at Sutter's Mill in California that caught the public fancy and precipitated the establishment of prospecting as a full-time occupation. After the end of the Civil War in 1865, full-time prospecting became an important occupation and continued as such for almost three generations. Prospectors equipped with picks, shovels, gold pans and four-footed transportation swarmed all over what are now our Western States, discovering thousands upon thousands of mineral showings-and certainly most of today's large mining districts. Our vigorous western mining industry is a tribute to the courage and persistence of these men. The techniques of these picturesque prospectors, however, were essentially the same as those of their predecessors-examination of every outcrop and assiduous use of the gold pan. The great increase in discovery at this time was therefore due to increased activity rather than to different techniques. An important result of this in- creased prospecting was the growth of interest in geology. It was during this period that the U.S. Geological Survey began to grow. Many of the major mining districts were mapped, and geological studies and projections began to have an impact on further ore discovery. Ore search and development gradually became more geologically oriented and the geologist became a fixture in most mining camps by the 20th century. The development of mass-mining techniques in the early part of the century also changed exploration concepts.

Jan 1, 1971

By W. R. Shimer

IN his valuable report on Finishing Temperatures and Properties of Rails, I Dr. G. K. Burgess, Chief of the Division of Metallurgy, U. S. Bureau of Standards, has begun a line of investigation which should be continued by those interested in the subject, and who have proper facilities for carrying put the work. For the past year or more the Bethlehem Steel Co. has been conducting experiments to learn the effect of rail finishing temperatures on their physical properties and microstructure and the results are here given for the consideration of those interested in the rail situation. . Considerable differences of opinion have been expressed by various authorities, in the past, as to the effect of large or small grain size and high or low finishing temperatures of steel rails on their physical properties and wearing qualities. Low finishing temperatures and, therefore, low shrinkage, have been advocated on the theory that the wearing qualities would be improved. Others have recommended high finishing temperatures. The generally accepted cause for rail failures, due to the development ,of transverse fissures, is excessive wheel pressure on hard rails. One of the causes advanced for hard rails has been that they contain too high per centages of carbon and manganese; another that the rails were finished at too low a temperature, i.e., at or near the critical point. In the experiments herein described the rails were rolled from reheated blooms. All the rail blooms were charged hot in a reheating furnace and brought up to about the original ingot-rolling temperature before rolling into rails. These rails gave better results in deflection, withstood a greater number of drops before breaking, and showed greater ductility, than. rails of identically the same composition and section which were rolled, direct from the ingot. Rails rolled from reheated blooms, finished at somewhat higher temperatures than when rolled direct from the ingot, have a different microstructure, which the writer does not believe is due so much to the difference in finishing temperatures, as to the difference in

Jan 3, 1915

By C. W. Washburne

Continued discussion of the paper Of ROSWELL H. JOHNSON, presented at the New York meeting, February, 1015, and printed in Bulletin No. 98, February; 1915, pp. 221 to 226. See also Bulletin No. 101, May, 1915, pp. 1157 to 1162, and No. 103, July, 1915, pp. 1449 to 1450. C. W. WASHBURNE, New York, N. Y. (communication to the Secretary*).-Mr. Johnson recognizes that connate waters must be driven, outward toward the earth's surface. He considers the ascent due to the settling and packing of the underlying sediments and to the formation of gas within the rocks, supplemented by abyssal pressures. The origin of the methane in the sedimentary strata probably is not simple. There are three possible modes of origin: (1) as marsh gas formed near the surface and entrapped in the sediments; (2) from abyssal sources; (3) by the decomposition of organic matter buried in the sediments. The abyssal source is generally negligible, and in all cases doubtful. The third origin is the most important in the gas fields. A fourth mode of origin, by the dissociation of liquid hydrocarbons, frequently has been suggested, but it is improbable, because crude oils are exothermic. Therefore they have no tendency, to split or decompose at low temperatures, as do endothermic substances, such as coal, which is geologically by the loss of methane, water, and carbon dioxide. This cannot happen to a hydrocarbon until its temperature of dissociation (" cracking point") is reached, which is over 250'.C. for the most easily cracked hydrocarbons and over 400° C. for others. Engler says that the dissociation of fats and waxes into oils is an endothermic process, thereby unconsciously nullifying his own theory of the dissociation of these substances at low temperatures. However, recently I have found reason to think that heat is liberated by the disruption of the molecules of fats and waxes, as it is in the molecular decomposition of the substances of wood, coal, etc. If this tentative opinion is correct, and Engler wrong, then it seems that the Engler-Höfer hypothesis of the origin of oil becomes not only possible, but even probable.

Jan 9, 1915

By Edwin C. Barringer

IRON and steel scrap has again become page one news, as it was during the war. To many this is anomalous because the common concept is that the theaters of war are literally paved with scrap as the by-product of war damage and abandoned materiel. To an extent this is true, the bottleneck being the ferreting out and transportation of this scrap. While you as consumers of the electric-furnace grades of scrap-the premium grades-are concerned primarily in only one segment of the scrap market, I believe you ill be interested in a general discussion of the market with subsequent funneling down to your specialty.

Jan 1, 1947

By C. S. Simons

The conversion of a successful research and development effort into a money-making business venture requires careful attention. Problems of a business nature, such as market size, product selling price, raw materials and fuel availability and cost, financing factors, local and national taxes, licensing arrangements, etc. must, of course, be considered and resolved. In addition, the technical questions involving the scale-up of pilot plant or laboratory results to the full-scale plant must be resolved in order to avoid the financial disaster that attends a major delay in the startup of a commercial facility. The very difficult and demanding task of providing the interface between the research laboratory and the profitable metals processing plant will be discussed with examples from the author's extensive experience. After I had accepted the invitation to present a paper on the above subject of the interface between R & D and production operations, I began to give some serious thought to the subject. The program chairman had told me, in conveying the invitation, that what the committee had in mind was a discussion of positive and negative, forces in that interface, based on "gray-hair" experience. I am, therefore, at least physically qualified! My first reaction was one of mild shock; after over twenty years in the direct pursuit of the conversion of research and development findings into plant operations, I had never tried to sort out my , experience into a formal system of DO'S and DON'TS for the edification of posterity. However, after a little further reflection, I realized that this carries no stigma. No one has been able to formulate such a set of rules, and it is not really very likely to be done. Particularly if they are to be practical. I shall therefore settle for a more modest goal; I will simply discuss the factors that I have come to believe are the most critical in insuring that re- search and development results are converted into successful operation.

Jan 1, 1973

By Linn Bradley, W. W. Strong, H. D. Egbert

Marked differences of opinion have been expressed by engineers interested in cleaning iron blast-furnace gases for use in hot-blast stoves and under boilers, in reference to the advantages of a hot-dry method over a cold-wet method. One point at issue involves the sensible heat energy in the moisture contained in the gas. Some advocates of the cold-wet methods claim that the condensation and resultant removal of the greater portion of this contained moisture by wet scrubbing, spraying or similar methods, results in a saving of some of this sensible heat energy, by reason of the fact that water vapor has a high capacity for sensible heat energy and may carry from the exit of a hot-blast stove, for example, more heat units than are sacrificed or lost when the gas is cleaned by this cold-wet method. Other advantages claimed for the latter method are: That gas burns more readily when it is free from moisture in any form; that because gas is made denser by cooling and removing the moisture it has a higher calorific value than hot gas carrying moisture; and that higher flame temperatures are obtained when the gas is cleaned by the cold-wet method. A search through the available literature fails to disclose any extensive calculations or records of conditions obtained in practice, bearing upon these phases of gas cleaning. This paper deals with these problems from the standpoint of the economy of using a gas of higher flame temperatures, of improved stove design, and of economy in the gas-cleaning department. Calculations have been made which show that by cleaning the gases by a cold-wet method the sensible heat energy of the blast-furnace gases is greatly reduced; and, in general, this loss of heat energy is far greater than that lost from the stoves or boilers due to the sensible heat capacity of the water vapor if carried away by the exit gases. By making use of the

Jan 1, 1917

By G. M. Yocom

Blowing acid Bessemer converters with oxygen-steam produces steel of below 0.002 pct N2 content. This method of blowing, combined with a dephosphorizing treatment in the steel ladle, results in low-carbon steels of low nitrogen and low phosphorous (under 0.035 pet) contents, which has physical properties equivalent to open-hearth steels of similar analysis. Using a 50-50 mixture of oxygen and steam, the refinitzg rate is increased 25 pct over blowing with natural air, and scrap charge increased from 3 to 10 pet. Bottom life is normal with proper tuyere area and arrangements, fumes are decreased, yields increased, and hydrogen content is normal. THE acid Bessemer plant at the South Works of Wheeling Steel Corp., consists of two 15-ton bottom blown converters with a monthly capacity of 57,000 N.T. The product of the shop is skelp billets for continuous welded pipe and slabs for ordinary drawing and forming quality sheets. Approximately 50 pct of ingot production is regular Bessemer steel of natural Phos content and the remainder is a dephosphorized grade of steel made by a special treatment of the blown metal as it is poured into the steel ladle. The low Phos grade of steel has certain advantages over the higher Phos grade but since both grades were produced by blowing natural air, the N2 content was in the range of 0.015 pct which limited its application. In 1954 it was decided to explore the possibilities of blowing with a steam-oxygen mixture for the production of steel of both low N2 and low Phos contents. The necessary equipment was installed to operate one converter in this manner and early in 1955 an experimental run of 160 heats was made by blowing with a steam-oxygen blast and excluding natural air entirely. During this period the proper operating techniques were established, such as blast pressures, steam-oxygen mixtures, valves and instrumental control equipment, tuyere arrangement in the bottoms, blowing times and production rates, and a thorough study made of the final steel quality. Also during this experimental period the dephosphorizing practice was improved by the use of a tap hole below the lip of the vessel. This provided a clean separation of the acid converter slag and blown metal which made the dephosphorizing treatment more effective. The results of this experimental run dictated further development of this practice and a second run of 720 heats was made in 1957. The quality features and conversion cost results were in line with expectations and accordingly a 400-ton per day oxygen plant is now being installed. The plant is scheduled for completion in September of this year. This will provide sufficient oxygen to operate both vessels on steam-oxygen blast and delete natural air blowing entirely. The steel will then be below 0.002 pct N2 bar content and the dephosphorized grades will be between 0.015 and 0.040 pct Phos. STEAM-OXYGEN BLOWING The steam for the process is fed to the plant at 220 psig pressure through a 6-in. line. The high-purity oxygen is compressed to 200 psig and conducted through an 8-in. line. The oxygen from the main line is valved down to 100 psig and passed through a steam heated heat exchanger. The heat exchanger is regulated to supply oxygen at 300°F to the steam-oxygen mixing station. It is essential that the incoming oxygen be held at this temperature to avoid condensation of the steam with resulting excessive erosion of the clay tuyeres in the vessel bottom. Oxygen is admitted to the mixing chamber by a 6-in. hydraulically operated valve driven by the ratio control regulator on impulse from the flow of steam. Steam is admitted to the steam-oxygen mixture station through a 2 1/2-in. hydraulically driven valve. The ratio control regulator acts to increase or decrease oxygen input as the steam flow increases or decreases with changing positions of the Blower's control lever. The important point to note here is that steam flow always precedes the oxygen flow as a safety measure. The control valves have sufficient capacity to afford protection should blow pipe trouble develop. A 50-50 mixture for these 15-ton heats demands an oxygen flow of 3800 standard cu ft per min along with 317 lb of steam. The Blower's stations is provided with an indicating blast pressure gage, and indicating steam and oxygen flow meters. Signal and warning lights indicate the valve positions and line pressures. A control room at the real of the Blower's pulpit room houses the ratio control and pressure regulators, as well as the various meter bodies. The hand actuated wheels used to change the conditions are mounted on a panel on the front of the meter control house. The recording steam and oxygen meters used for totalizing and accounting purposes are also mounted on this panel.

Jan 1, 1962

IT is necessary that all men who wish to bring things to a certain end should think of the agents needed to attain this. Now whichever one of the above processes you wish to use you must consider the nature of the material and see whether it is disposed to render what you wish to extract. Then you must see whether you have the other agents sufficiently powerful and proportioned to attain this result, for if the things were not in harmony your work would be vain and very laborious. Therefore, if you should wish to make waters or oils by way of distilla-

Jan 1, 1942

By William H. Shockley

There was an extensive mining and industrial exploitation of Russia, about 20 years ago, by Belgian, French and British capitalists; but the results were discouraging. It is said that the Belgian and French public together lost approximately $400,000,000, chiefly in the coal and iron industry of southern Russia. This loss is largely accounted for by the fact that most of the companies were formed, as usual in " boom" times, to sell stock; and that thorough investigations were not made. I11 1906, renewed interest was taken in Russian mines, especially in those of gold and copper, and a considerable literature is growing on this subject; but as yet I have seen no account of one of the large Russian mining estates. The following notes on such property, where the conditions are so different from those in the mining regions of the United States, should be of interest: This inadequate and probably somewhat inaccurate account is made up, partly from my own notes made on the ground, in the summers of 1904 and 1905, and partly from a volume on the geology and resources of the estate issued several years ago, containing surface- and mine-maps, and from a pamphlet published in 1904, giving a general account of the condition and prospects of the property. This pamphlet includes a report made in 1899 by Arthur L. Pearse, a member of this Institute. Both these books are in Russian, and were prepared by the Bogoslovsk Mining Co., which owns and operates the property. Articles in many other languages have appeared dealing with various matters connected with the estate; but I know of no other general account of it. In numerous books and articles on the Urals and Siberia, however, localities are described in which somewhat similar conditions prevail. Recent papers by

Jan 1, 1909

By H. A. Dierks

PENNSYLVANIA's anthracite region lies in the heart of the richest and most densely populated area of the U. S. Nearly 70 million people live within a radius of 500 miles, in which 130,000 manufacturing plants employ more than 8 million workers. The region comprises some 3000 sq miles and contains 484 sq miles of coal measures, which folding and erosion have divided into four separate and distinct fields, known as the Northern, Eastern Middle, Western Middle, and Southern. One million people live in the anthracite region proper, and their prosperity depends to a great extent on the anthracite industry, which produces more than $200 million in new wealth for the U. S. each year. Nearly 80 pct of the tonnage shipped out of the region is handled by nine railroads, which depend on this traffic for a large part of their revenue. It follows that the economic health and the very existence 0: this industry is of real concern not only to the region itself but also to the state of Pennsylvania and the country as a whole. Anthracite mining is one of the oldest mineral industries in America. About 1760 burning rock or stone coal was discovered on the hillsides of northeastern Pennsylvania. Within a few years a systematic search for coal bed outcrops was under way, and hand mining was begun. At first production was very limited, since anthracite was difficult to burn and was not readily accepted as a fuel. Pennsylvania anthracite is one of the densest and hardest of all coals, and its content of volatile matter is low. Consequently it does not ignite easily and it burns without smoke. About 1808 Judge Fell of Wilkes-Barre burned anthracite in an open grate fireplace and demonstrated proper handling of an anthracite fire. From

Jan 1, 1958

By Roswell H. Johnson

What becomes of the water which must have filled the oil and gas sands at the time of deposition, has long puzzled students of oil and gas and has found expression in Munn's well-known article on the hydraulic theory. Both Munn and Clapp have pointed out that in the Appalachian field the deeper sands carry increasingly less proportionate amounts of water. It seems to me probable that the principal source of oil and gas has been in the shales in proximity to the sands which now contain these products. The sand spits which mark off the lagoons from the sea comply particularly with the requirements of a limited sand imbedded in shales rich in organic matter. Cunningham Craig has objected to this view that the rich organic muds of lagoons are found only at the surface. That such muds do extend to considerable depth 1 am assured by Prof. Douglas W. Johnson, who has made an extensive study of the Atlantic Coast marshes. As any particular sand body becomes weighted by a heavier and heavier overburden, the result of increasing deposition, a part of the very large percentage of water in the uncompacted sand and mud is forced out. The water percentage of freshly settled mud is vastly higher than that of the resultant shales, or even of a very porous sand. If beds of less compressible material meet or underlie the shales in question, there will frequently be a lateral motion along such beds to some point where the upward movement will be resumed. We find in our laboratory work here that oil, gas, and water have extremely slight capacity for gravitational sorting while in a state of rest, but when moving the gravitational sorting is readily accomplished. As the oil, gas, and water pass a body of larger pores, the gas, owing to its lack of capillary attraction, is retained in the large pores. This has been predicted by Washburne, Blatehley and others on the ground that the water has a higher capillarity and grips the finer pores in such a way that there will be a greater proportion of oil and gas in the large

Jan 1, 1915

Discussion of the paper of G. K. Burgess and J. J. Crowe, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 82, October, 1913, pp. 2537 to 2591. HENRY M. Howe, New York, N. Y. :-I think we can hardly rate the importance of the entry of the Bureau of Standards into our field. There is no body in the world that is better fitted to undertake this work than that Bureau, and it is work which really calls for the aid of some national organization. The skill and care with which this work has been done speaks for itself. It is very striking that within a very few months the distinguished English investigator, Professor Carpenter, of whom I spoke before, thought that he had disproved the existence of beta iron by proving that the A2 retardation which Professor Burgess has now demonstrated did not occur. Dr. Burgess's demonstration of the existence of. this retardation makes the existence of beta iron very probable, in my opinion. Osmond used to call beta iron " decipuum." You knew of its existence as you know of the existence of certain planets, only by the perturbation which it caused. Certain phenomena could not be explained, except by assuming the existence of a third allotropic form, beta iron. The evidence that you got was always evasive and susceptible of other explanations, except that which we have to-day, which it seems to me is not capable of other explanation. Professor Carpenter proceeded in the same way that Dr. Burgess has, by taking the heating and cooling curves of exceedingly pure iron, and thought that he had shown that there was no thermal change, no absorption or evolution of heat at the supposed A2 point, and hence that the A2 point did not exist. This he did by a piece of reasoning which I think seems to most of us rather surprising. That is to say, if of ten witnesses, three have seen a thing and seven have not, the evidence of the seven who have not is set aside, and that of the three who have seen stands. In Dr. Carpenter's own experiments under certain conditions he found the A2 change, the heat evolution., under certain others he did not. That is like the three witnesses who saw and the seven who did not see. You can arrange your test so that this change will not become visible or so that it is masked. But though an existent change can be masked a non-existent one cannot be shown. So that the reasoning seemed to me wholly fallacious.

Jan 12, 1913

By R. Floyd Farris

A THOROUGH knowledge of the behavior of cement slurries under elevated tempera-tures and pressures is necessary in order to solve properly the many problems pre-sented in deep-well cementing operations. In the earlier days of the petroleum indus-try the depths of wells were shallow as compared to those of today, and the subsurface temperatures and pressures were not of sufficient magnitude to affect seriously the problem of proper control of cement-slurry properties. Today, however, the search for new reserves has extended drilling to such depths that bottom-hole temperatures of more than 200°F. and bottom-hole pressures of 3000 to 5000 lb. are not uncommon. Moreover, there is every indication that within the next few years wells will be drilled to even greater depths and bottom-hole temperatures and pressures will be correspondingly higher than those with which we are concerned today. It has been realized for some time that the behavior of cement slurries at high temperatures and pressures might be very different from that at atmospheric tempera-ture-pressure conditions, but while the temperature effects have been investigated with a reasonable degree of thoroughness, the pressure effects have received little public attention. While the trend toward deeper drilling may make changes in cementing technique and the choice of cements imperative, it was the purpose of this investigation to consider factors having a bearing on the latter, only secondary consideration being given, for the present, to details of tech-nique and equipment for oil-field use. More specifically, the purpose of this work was to consider the effect of temperature and pressure upon the behavior of cement slurries.

Jan 1, 1940

By C. S. Anderson

Georgia, since 1829, has produced nearly $18,000,000 from her gold mines, but in late years the output has dwindled to insignificance. In view of present universal efforts to increase gold production, it seems pertinent to record some recent observations in that field, briefly review its past and weigh probabilities of reviving gold mining there. Little in this paper can be claimed as new or original, and it does not present results of a detailed or profound investigation of the whole region. The Allatoona gold mine was reopened in January, 1932, and explored at greater depth during the period from January to June of that year. A number of other abandoned mines were visited, but since the workings, in common with most such mines in Georgia, were flooded or caved, underground conditions could not be examined. For a wider knowledge of the subject, a search was made through available pertinent literature and statistics, a bibliography of which is appended hereto. To all the sources obligations are gratefully acknowledged. Production The discovery of gold in Georgia, in 1829, led to an influx of 6000 to 7000 miners and a production of over $200,000 in the following year. A branch of the United States Mint, established at Dahlonega in 1838, accounted for $6,115,569 up to the time of the Civil War. The output fluctuated greatly from year to year, with an all-time peak of $582,782 in 1843. In only one other year, 1845, was the half million mark exceeded. After the war mining began again, but 1883 is the last year for which an output of $200,000 is reported. Placers, always the main source of production, were yielding less and less, and in spite of increased quartz-mining activities the downward trend continued. The last year in which there was a production of $100,000 was 1902. In 1914, $16,270 came from 26 placers and 11 deep mines, with the latter reporting 1750 tons of $3 average value. In 1925, one placer and four lode mines that mined 8100 tons assaying $1.19 per ton produced $9500. One placer and one quartz mine, operating in 1930, reported a total output of $4194. Table 1 pictures the waning output.

Jan 1, 1934

By E. B. Brauer, W. Hurst, J. D. Clark

Because of drilling, completion, and workover practices, the permeability around a wellbore generally is different from the permeability of the formation. The zone with the altered permeability is called "skin" and its effect on the pressure or flow behavior of the well is called "skin effect". Hawkinsl has shown that the radius and the permeability of this zone are related to the skin by: If the permeability in the skin zone is less than that of the formation, the skin is positive; if it is more than that of the formation, the skin is negative. If the two permeabilities are equal, s is zero; that is, there is no skin. Van Everdingen2 and Hurst3 have given mathematical solutions to the case of a zone of reduced permeability around the wellbore. This skin effect is illustrated in Fig. 1. They treat the positive skin as a zone of reduced permeability of infinitesimal thickness around the wellbore. When applied to a well with negative skin, however, their solutions lead to the calculated flowing well pressure which is smaller than the formation pressure, i.e., an injection situation. This is a physical contradiction. In this paper, it is shown that this mathematical difficulty can be overcome by assuming an effective wellbore radius larger than the actual wellbore. Existing solutions2"4 are modified to include the effect of an enlarged wellbore radius, and thus enable the engineer to deal with negative as well as positive skins. Theoretical Development Van Everdingen and Hurst,4 through the use of Laplace transformation, obtained the following expression for transient fluid influx into a wellbore: The values for QtD, reported extensively by van Everdingen and Hurst,4 are obtained from the following integral:

Jan 1, 1970

By R. P. Carreker, J. G. Leschen, J. H. Hollomon

The external appearance of a crystal which has undergone plastic flow suggests that adjacent blocks of the crystal have glided bodily past one another along the slip planes. However, the great discrepancy between the shear stresses calculated to effect such a movement and those actually observed has for many years stimulated searches for more satisfactory interpretations of the slip process. Appreciable success in these efforts has been realized by assuming the presence in the crystal of various sorts of imperfections and by considering the consequences of the presence of these flaws when stress is externally applied. The theory that has received the most attention recently—that of dislocations—postulates the occurrence of small, mobile imperfections or dislocations which move through the crystal along the slip direction, each dislocation being attended by a local shear displacement of one interatomic distance. Thus only that portion of the crystal through which the dislocation has passed may be said to have slipped. Since each dislocation produces a displacement of only one interatomic distance, an avalanche or train of many dislocations would be necessary to account for the observed displacements of several hundred or thousand interatomic distances. The salient point of the theory of dislocations is the concept that a slip band does not suddenly appear in its entirety. On the contrary, it grows progressively across the slip plane as the individual dislocations successively appear and advance in a train through the crystal. However, the concept of growth is not intrinsic only to the theory of dislocations, since atomistic mechanisms other than that postulated by the dislocation theory can quite probably also describe the growth of a slip band. For instance, a slip band might resemble a disc-like interface that appeared and then grew continuously from a small size, producing a displacement that increased with the size of the disc. Whatever the precise mechanism, the concept of growth is in itself consistent both with the observed low values of critical shear stress and with the experimental observation that slip bands frequently do not traverse the entire crystal. The likelihood that slip bands grow implies that they must first be nucleated and that the initiation of slip can therefore be analyzed in terms of the general concepts of nucleation. Indeed, this suggestion was advanced1 several years ago, but the matter does not appear to have been further pursued. Recent advances in the theory of nucleation 2,3,4 have encouraged such a treatment of the slip process. As will presently be demonstrated, this approach to the problem not only accounts successfully for the incubation periods that have been observed 5,6 to precede slip but also predicts certain transient effects in the deformation process. The existence of these transients apparently has not hitherto

Jan 1, 1949

By Jack L. Taylor

Single crystals of tungsten grown from powder -metallurgy swaged rod by high-temperative annealing were deformed in tetzsion at temperatures from 2500 to 5000 OF. Orientation of specittzen tensile axis, strained ratrix, and defortnation bands was determined optically by reflections from {110} etch pits. Slip traces meve analyzed and slip directiorz determined. Results indicate that {110}(111) , {112){111}. and {123}{111} type slip occur in tungsten over the terpe,atuve rutge investigated. Slip is orientation-dependent occuvring on tCuzt cowzbitzation oj slip plane and direction which has the highest critical resolved shear stvess. Overshooting appears to be a general occurrence between 2500' and 5000°F. Dejornatiotz bands show rotation in a directiorz opposite to the yotation of tire tensile axis. DEFORMATION in bcc metals has been reviewed by Maddin and Chen,' Keh and eissman,' and most recently by Nabarro, Basinski, and olt. From these reviews it is apparent that some disagreement exists concerning the crystallography of plastic deformation in bcc metals. There is evidence of noncrystallo-graphic slip, the crystal slipping on or near a noncrys-tallographic plane in the (111) zone for which the resolved shear stress is greatest. There is also evidence to indicate that crystallographic slip occurs in the planes of the same zone. On the other hand, there is agreement that the close-packed direction ( 111) is the slip direction in bcc metals. Further, in pure bcc metals4 and alloys the operative crystallographic slip systems are strongly dependent on temperature. Both crystallographic and noncrystallographic slip have been reportede8 in tungsten, a group VIA bcc metal. The number of slip families which operate in the case of crystallographic slip, however, has been in question. The earliest study by oucher' of single-crystal tungsten tested at temperatures of 1800 to 5000°F led to the conclusion that only {112)( 111) type slip operated. Raymond and eumann recently reached the same conclusion studying deformation by rolling of plasma-flame single crystals at 1800°F; however, only [loo] and [110] orientations were studied. Work at high temperatures by Leber and Pughs on tungsten and Chen and Maddin9 on molybdenum suggests that conjugate slip on nonparallel (110) planes may account for the slip on (112) and (123) planes found by others working with bcc metals. The present paper presents evidence of three families or modes of slip in tungsten in the temperature EXPERIMENTAL PROCEDURE Material. Standard microtensile specimens, 0.160 in. diam by 0.640 in. gage length, were ground from commercial powder-metallurgy swaged tungsten rod, type MK. Specimens were heated for 10 min at 5150°F or 6 hr at 5400°F in vacuum of 1 x 105 Torr or less to produce single crystals. At the lower temperature an average of two out of seven specimens heated in a group developed single crystals throughout the specimen length as shown in Fig. 1, the rest remaining wholly poly crystalline. At the higher temperature, three or four out of seven specimens became single crystal. Other than to note that Laue X-ray photographs generally showed sharp, well-defined spots, no attempt was made to assess crystal perfection or measure dislocation density. Two tungsten single crystals grown from the melt by the plasma-arc process were also used for this study.

Jan 1, 1967

* A complete magnetic picture of the Mesabi range is now available for the first time with the release of 21 additional maps based on the aeromagnetic survey of 30,000 square miles made jointly by the USGS and the Minnesota Geological Survey. A potential iron formation with a magnetic pattern remarkably like that of the Mesabi iron range lies buried beneath the glacial drift in a wide belt extending some 30 miles across the northwest corner of Itasca County in north central Minnesota. Identification of three new uranium minerals by the USGS was recently announced. The new minerals, andersonite, swartzite, and bayleyite are, respectively, hydrous uranyl carbonates of magnesium, of sodium and calcium, and of calcium and magnesium. They were first observed by Charles A. Anderson, Survey geologist, in a coating on gypsum on the 300-ft level of the Hillside mine, Yavapai County, Arizona. International Minerals and Chemical Corp. has announced a $4,000,000 expansion and development program in the Polk County phosphate fields in Florida, Plants for the manufacture of multiple superphosphate and phosphate chemicals including dicalcium p osphate for animal feed and chemical purposes, and a sulphuric acid are planned. Office building, machine shop, warehouse, and laboratory are also scheduled for erection. A new type of tramp iron detector is being used on the conveyor belt feeder at the South Agnew stripping operation. It is made of an alloy of aluminum, nickel and cobalt and does not have any electric coils. The alloy, known as Alnico, is remarkable for the permanence and intensity of the magnetism which it retains. The detector was made by Dings Magnetic Separator Co. and it is probable that Alnico will be used in magnetic separators. The American Society of Engineering Education estimates that unless the percentage of high school graduates entering engineering colleges is increased, there is a strong possibility that instead of a large surplus of engineering graduates, which has been propehsied rather widely, there will soon be fewer engineering graduates available than are needed annually by our national economy. This conclusion is reached from a survey that shows that engineering enrollments are only slightly higher than prewar whereas industrial expansion is increasing the need for engineers. * The natural resources of Korea are being investigated under ECA sponsorship. E.J. Longyear has just embarked 8 crews for that country; two drills are scheduled for base metal search while six are slated for development of coal reserves. An innovation in the development work in the iron country has been the adoption of the Drill-Mobile, jumbo-mounted drills on rubber-tired carriage, by Cleveland-Cliffs at the Mather A and B mines. The machine is being used to cut stations in the new Mathed B shaft and for driving development headings at the Mather A.

Jan 5, 1950

By M. Van Siclen

THE outstanding fact in connection with dust disease in the United States at present is the growing recognition of its seriousness by state officials and by the more progressive operators of mining, metallurgical and allied industrial plants. The same may perhaps be said of labor in some of its better organized centers, but the average independent non-union workman continues, .as of yore, to suffer the toll of disability and even of death from dust inhalation without realization of the source of his ill-being. Progress in the betterment of the handling of sufferers from dust disease and of the conditions creating dust hazards in mining and allied industries is pursuing a course similar to that of the now widespread campaign against accidents, in which the risk is more obvious, more severe, and was naturally recognized sooner. The coming on of dust disease is generally relatively slow and its immediate effects not infre-quently masked by or attributed to other diseases. Marked exceptions to this general rule have occurred in districts where the dust is particularly pernicious, such as the Rand and Joplin; yet such exceptions, unhappy in themselves, opened the eyes of medical men, and of those in other localities charged with the responsibility for the welfare of industry, to the much more widespread if less spectacular hazard existing from the inhalation of dust in all rock-excavating operations and all industrial operations creating inorganic dust, whether it be crushing and grinding, sand-blast-ing, granite-cutting, or what not. Advancement to date in the United States in prevention and treat-ment has been slow, yet the record shows that quantitative methods for determining the degree of hazard and means for decreasing it were being developed as far back as 25 years ago; and that more rapid progress may be looked for from now on. In 1908, in this country; F. L Hoffman?(1) discussed the mortality from consumption in dusty trades, especially brass foundries; and in 1913 E. R. Hayhurst(2) described the effects of inhalation

Jan 1, 1933

By George Hunt

THE first practical treatment of wood to prevent decay was devised early in the 19th century. At that time the oaken navy of England, when . the nation was fighting for its very existence, seemed doomed to annihilation by the swift ravages of decay. The acute situation inspired a desperate search for preventive measures and resulted in the development of the Burnett, Bethel and Kyan processes for impregnating wood with zinc chloride, coal-tar creosote and mercuric chloride, respectively. In the century that has elapsed, their use has spread throughout the world and the three original preservatives are used today in enormous quantities. Meanwhile, improved processes have been developed, new preservatives discovered, and the practice of impregnating wood to make it last longer has attained a position of major importance in the field of structural materials. USE OF PRESERVATIVES BY- THE RAILROADS In the application of wood preservatives in the United States the railroads have been the leaders for the past 50 years or more.. Having found, that decay is the chief cause of the early destruction of wood and that preservative treatment is the remedy, they have treated their ties and timber in increasing amounts(1) ?-in 1925 about 220,000,000 cubic feet. By preservative treatment the Santa Fe Railroad saves annually 1,500,000 ties in its 18,000 miles of track, and many other railroads effect similar savings. (2) In like manner the life of wooden bridges and trestles,(3) poles, marine piling, water tanks and other wooden railroad structures has been greatly increased, reducing the amount of timber required annually to maintain them.(5),(7)

Jan 2, 1927