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By W. D. Forgeng, R. L. Folkman, D. C. Hilty

The solubility of oxygen in molten Fe-Cr alloys has been determined at 1550° , 1600°, and 1650°C for alloys containing up to alloyshasbeenabout 50 pct Cr and found to decrease as chromium increases to 6 pet and then to increase gradually. Phase relations in the Fe-Cr-0 system at steelmaking temperatures have been evaluated and two previously unreported oxides have been identified. OPERATIONS in the melting and refining of chromium steels are dependent to a major degree on the reactions of chromium and iron with oxygen and are primarily directed toward controlling and modifying these reactions to secure maximum advantage in the utilization of chromium. Although fairly effective practices have been developed empirically, understanding of the specific reactions is limited. Moreover, the ability of molten steel to dissolve oxygen that subsequently precipitates as oxide inclusions during solidification is well known, so that clarification of the effect of chromium on the nature and mechanism of formation of these inclusions is desirable. Study of the problem indicated that increased knowledge of the fundamental Fe-Cr-0 system is essential to further technical and economic improvement. Consequently, an investigation of the influence of chromium on the solubility of oxygen in molten iron and of phases and phase relations in the Fe-Cr-0 system was undertaken at the Metals Research Laboratories of the Electro Metallurgical Co. as part of a general program on the effective utilization of chromium in chromium steel production. Experimental Procedure All of the experimental runs made during this investigation were carried out in the rotating crucible induction furnace which has been described in detail in a previous publication.' In review, the principle underlying this furnace is that rotational forces in the crucible cause the molten metal to assume a concave shape in such a manner that the slag is contained in the molten metal cup, thereby minimizing slag/crucible contact and subsequent reaction. Practically all of the heats were melted in commercial-quality magnesia crucibles of the type usually furnished for laboratory induction furnaces. All of the runs were made under an argon atmosphere after the furnace chamber had been degassed. Bath temperatures were controlled by Pt—Pt-10 pct Rh thermocouples. The basic furnace charge consisted of a premelted 12 to 15 lb electrolytic iron slug which had been cast to a shape convenient for fitting into the rotating furnace crucible. A typical analysis of the electrolytic iron slugs is given in Table I. For certain runs, it was desirable to melt down charges containing high initial chromium contents. In these cases the chromium was added to the electrolytic iron during the premelting operations. Chromium was added to the rotating furnace bath in the form of electrolytic chromium of the analysis given in Table 11. In all of the constant temperature runs, the standard procedure was to melt down the electrolytic iron or alloy slug under vacuum, admit argon to slightly greater than atmospheric pressure, and adjust rotational speed to develop a well formed "cup" on the bath surface. The melt was then saturated with oxygen by an addition of ferric oxide and the temperature of the bath adjusted to within +5°C of the desired level. At this point the heat was permitted to come to equilibrium prior to sampling or further addition. This time interval was varied from 15 min to 2 hr but generally was about 20 min. After sampling, the desired chromium addition was made and the bath again equilibrated prior to subsequent sampling. This cycle of addition and sampling continued for the duration of the run which lasted from 4 to 8 hr. At the end of this period, power was shut off and the bath allowed to solidify in the furnace. Quenched metal samples were taken from the equilibrated melts by means of the "Taylor sampler" which has been described by Taylor and Chipman.' Before being submitted to chemical analysis, all samples were carefully examined for surface slag occlusions and cold shuts. Later in the study, each sample was radiographed and examined metal-lographically in cross-section to determine the presence of internal defects. On the basis of these examinations, sound and apparently clean specimens were selected from the Taylor samples for chemical analysis.

Jan 1, 1956

By A. S. Michaels, R. S. Timmins

A study of the effect upon oil recovery from an un-consolidated porous medium of chromatographic transport of selected reverse-wetting additives during water displacement is described. Flow tests were performed on hydrocarbon oil-saturated sand columns (containing connate water) into which small volumes of short-chain aliphatic amine solutions were introduced during water flooding. Concurrently, meusurements of oil-silica contact angles, oil-water interfacial tensions and oil-water distribution coefficients were measured us a function of additive concentration. Certain treatments were found to cause a slight reduction in oil recovery, while others produced a significant increase (up to 50 per cent of the normtzl irreducible rninimum oil saturation). Recovery eficiency was correlated most satisfactorily with the maximum degree of reverse wetting produced during additive transport; conditions which resulted in only mild oil wettability of the sand reduced recovery, while those favoring strong oil wetting increased recovery. A mechanism of reverse-wetting additive action during chromatographic transport is developed which ascribes the results to transient changes in oil-solid contact angle during flow, with consequent release of oil trapped by capillary forces. Implications of these observations with regard to improved waterflood efficiencies are discussed. INTRODUCTION The need for finding improved methods of oil production is amply illustrated by the large volume of oil considered economically unrecoverable by existing production practice. Water flooding has long been an excellent method of secondary recovery. However, even in those areas of a formation which are well swept by a water flood, 20 per cent or more of the oil remains trapped within the formation and is not recovered. This trapping of oil within the pores of the rock structure results primarily from interfacial forces. If these interfacial forces were altered, it is possible that the trapped oil could be released and recovered. The addition of surface-active agents to a water flood to alter the interfacial properties of the oil-water-solid system has received considerable attention as a method of increasing oil recovery. Studies of surfactant treatment have yielded varied and, in some cases, apparently conflicting results. Increased oil recovery using surface-active agents has been reported by a number of investigators. Others have found that use of surfactants in a water flood either has no effect upon oil recovery or decreases it. Since surface-active agents tend to alter the formation wettability and oil-water interfacial tension simultaneously, several investigators have tried to determine the role these two factors play in oil recovery. Data have been presented which indicate that the most desirable condition for the solid surface is strongly water-wet. Other results indicate that, although breakthrough recovery may be less, the greatest ultimate recovery is obtained when neutral wettability prevails.", " The desirability of low interfacial tension seems to depend upon the wettability of the formation. Reports of higher recoveries, when the interfacial tension is high in a water-wet system and low in an oil-wet system, are at odds with reports of increased recovery in water-wet systems when surfactants which decrease the interfacial tension are added to the water flood. A review of previous work studying the effects of using surface-active agents in a water flood shows that these agents produce widely different effects and that opinions as to the role of the various interfacial properties are diverse. The consensus, however, is that the interfacial properties are quite important in the displacement of oil from a porous medium by water. Even in those investigations where appreciable increases in oil recovery resulted from treatment with a surface-active agent, economic considerations generally made practical application of the treatment unattractive because surfactants tend to be adsorbed within the formation. This adsorption would necessitate using large quantities of surfactant if all of the flood water were treated to contain a given surfactant concentration, even if this concentration were quite low. Preston and Calhoun suggested that the principles of chromatography could be applied to the use of surface-active agents as a means of increasing oil recovery. A small volume of surface-active material is injec-

By Otto Wartenweiler

After the phenomenal development of the new mine, the United Eastern Mining Co., with Mr. Frank A. Keith as President, decided to install a reduction plant. The character of the ore, closely resembling the product of other mines in the district, did not offer any particular metallurgical problems, since these neighboring mines had been operating milling plants very successfully for several years. Thus, with the general metallurgical treatment fairly well-defined, the matter of next importance was to design and construct a plant as economically as possible, that would give the best results obtainable. The ore consists of a mixture of calcite and quartz in about equal quantities, with some decomposed andesite, while the average value of mill feed was calculated to be $20 or more in gold, no silver being present. The tonnage to be treated at the start was fixed at 200 tons, but, in view of the favorable condition of the mine, it was considered advisable to arrange facilities for increasing the capacity to 400 tons. While it is best in some cases to adopt a distinct independent unit system where future enlargement is contemplated, in this instance the plans worked out differently. Summarized, the treatment adopted consists of coarse crushing, coarse grinding, fine grinding and cyanidation. For coarse crushing the selection of the No. 6 size gyratory crusher was governed not so much by its capacity as by the size of the feed openings to receive the run-of-mine material, which was too coarse for a No. 5 crusher. TO accomplish the coarse grinding to best advantage, a careful comparison was made between the modern steel ball-mill—the last word in crushing and grinding—and one of its older, and, at that time better-established, competitors, the rolls. The following conclusion was reached: While it is possible that for the sized plant under consideration the cost of operating rolls might be a little cheaper, it is preferable to use ball-mills because a simpler arrangement is possible, and because the handling of ball-mills is preferred by the operator. A marked departure was introduced for fine grinding. Instead of the long type of tube-mill, using pebbles, a mill of similar design was selected, but of much shorter length, using small cast-steel balls as grinding medium. For cyanidation, the Dorr continuous countercurrent process was

Jan 1, 1918

By Bruce A. Kennedy

Lufthansa flight 497 roared down the runway and climbed rapidly through the early morning mist hanging over Pudahuel airport and the city of Santiago, Chile, into the brilliant sunlight above the clouds. As the plane banked onto course for Lima, Peru, we got what was possibly our last look at the beautiful snowclad mountains that ring Santiago. To the northeast was the massive hump of Aconcagua, the highest mountain in the Southern Hemisphere, wreathed in clouds and virtually looming over Rio Blanco, the new mine put into production by Cerro de Pasco just one short year before. Almost a thousand miles to the north lay the massive open pits of Chuquicamata and Exotica, and a little closer to Santiago the El Salvador mine. Behind to the southeast, clinging to the steep slopes of the Andes, was the large and awe-inspiring El Teniente mine at Braden. These mines, once the bastions of such companies as Anaconda and Kennecott, had a new owner-the Government of Chile. On the plane were a number of people who had spent a large part of their lives in Chile operating these mines and plants, and who now were suddenly faced with the necessity of starting new lives somewhere else. To them, this was their last look at the country which not too long ago was their home, a bittersweet moment of reminiscence and a time for questioning what the future held.

Jan 1, 1971

By S. F. Shaw

Fox some time it has been more or less recognized within the industry that a scientific control of flowing wells would result in increased production and a greater ultimate recovery of oil. About two years ago it was proposed by the writer that this control should follow principles worked out by him while handling large air-life operations. In the case of wells that had ceased to flow where a large quantity of liquid was present, the use of these principles would result in a large increase of production by using compressed air or gas to flow the well; in the case of a well flowing naturally it would take the form of controlling the gas associated with the oil, resulting either in immediate increase of production or in a reduction of the gas consumed per barrel of oil, and in both cases would result in a greater ultimate recovery from the sand. The Roxana Petroleum Corp., appreciating the advantages to be obtained by a scientific application of the principles of the air lift to oil wells, recently engaged, for a limited time, the services of the writer to work out some of the problems involved. The work was carried out at Braman, Garber and Tonkawa in Oklahoma, and at Oxford in Kansas. Following some suggestions of the writer a well was also equipped by the Roxana company at Smackover by A. S. Field.

Jan 11, 1926

By Eugene McAuliffe

HAVING reached the status of an octogenarian plus, I suddenly decided to take a trip to Great Britain by airplane, before the possibility of hardening of the arteries made such a program too precarious. Of thirty June and July days spent in the islands, five were spent in the south of Ireland, or Eire as the politicians like to call their country. On June 15 I arrived in Glasgow where a day was spent with old friends before moving on to Edinburgh, where the Institution of Mining Engineers was billed to hold its summer session. I had received a cablegram before leaving New York inviting me to attend the sessions which I accepted with avidity, spending three most enjoyable and informative days with old friends and the officers of the Institution, Douglas Hay, president; Ian McDermid, secretary; and members of the council.

Jan 1, 1947

By Sheldon P. Wimpfen

RESEARCH is undertaken to find out what must be done when what we are doing now is no longer adequate. To accomplish this end, researchers apply the truths of nature to industrial evolution. A survey conducted with the co-operation of 58 universities and colleges offering degrees in mineral engineering was the basis for the table accompanying this article. This survey was undertaken with the object of presenting to faculties and student bodies, as well as to industry, all available information on what action the educational institutions of the country have taken to provide the properly trained researchers so vitally needed. A hoped for result is that the great variety of opportunities available will encourage some undergraduate students to continue in their field beyond attainment of a B.S. degree.

Jan 1, 1947

By Carl S. Westerberg

Coal preparation practice and trends follow, among other factors, production trends in any given area. Considering an area the size of a state, some broad predictions may be made after a review of the annual production records. As this paper is concerned with coal cleaning in Utah, data on its production record are pertinent. Table 1 shows the percentage relation of coal production in Utah to the national total as a single figure up to 1935 which includes all recorded production. From 1935 through 1947 these data are presented by years. It is evident from these data that the production of Utah coal is ascending. The reason for this trend is industrial growth in the West resulting in a population shift which accounts for more people than the normal increase would supply together with Utah's relatively fortunate geographical location and its abundance of good-quality coal. Utah is also hopeful of supplying more coal in the future for West Coast power generati0n.l

Jan 1, 1949

By David Reger

ONLY a few small pools of oil were found in West Virginia during 1924. The price of oil was so low that there was no incentive for active effort toward the discovery of new pools or the exploitation of reasonably certain productive areas. At present, several encouraging edge-pool developments are being held in reserve in the hope that a more favorable market is not far distant. In the old pools, wells are being carefully tended; there being little tendency toward abandonment. even in cases where production is temporarily unprofitable. In natural gas, however, the total value of which at the well mouth is now more than that of oil, the year has been busy and profitable. , The decline of old pools, together with the increasing demand, has caused the large operators who carry their gas to the consumer to make great efforts to preserve or increase the rate of production; while the small operators, who sell their product to the large companies at the well mouth, have been stimulated toward the same effort by more favorable prices. These conditions brought about the completion of a greater number .of gas wells in 1924 than in 1923. Few pools of gas have been discovered during the year, the principal production having been obtained in old areas and in the unusually large new territory that was revealed as potentially productive by the drilling of 1923. Some of these latter areas are still without pipelines but definite plans for getting most of this gas are now being executed.

Jan 3, 1925

By Warren K. Kourt

Many important discoveries of mineral deposits have been made as a result of routine exploration for oil and gas. Through the presentation of three hypothetical case histories, including cost data, the author shows how mineral evaluation can be performed during routine petroleum drilling operations and how mining companies and oil companies or oil operators can cooperate in such endeavors.

Jan 1, 1972

By Sidney Cornell

THE technical- advantages of adding oxygen to air and producer gas, or using it as a reactive agent, producing 400 B.t.u. gas instead of. the present 150 B.t.u., with higher flame temperatures and a reducing flame possible, with a smaller volume of gases passing through a furnace, will result in quicker melting, sharp working, and the production of a higher quality steel. Probably electric-furnace quality steel can be produced in an open-hearth furnace using oxygen. A modern, standard, 100-ton open-hearth furnace, with all equipment, costs from $350,000 to $500,000; there are about 1000 open-hearth furnaces in this country. When considering the use of oxygen in the open-hearth furnace, it is necessary to study: (1) The use of oxygen in the present furnaces, such that modification of existing furnaces and equipment cost the minimum, although the full advantages of oxygen are not thus obtainable. (2) The use of oxygen in a furnace designed for its use, producing quality and quantity steel at the lowest possible cost. This entails the junking of approximately one-half the value in existing equipment-writing off $250,000,000. The basis of such an estimate is the present cost of manufacturing open-hearth steel. Objection may be taken to some of the unit prices here given, but while some companies obtain their ores for much less, the prices quoted are -market price. They are used to show the maximum economy obtained by oxygen at that point.

Jan 11, 1924

By R. E. Grim

With the exception of the extreme northeastern part of the state, Mississippi lies wholly within the Gulf Coastal Plains. The largest structural feature definitely proved is the so-called Jackson structure1 in the central part of the state. This structure is mainly the result of the burial of an igneous ridge on the old sea floor. The ridge trended in a northwest direction from about the town of Jackson in Hinds County into southeastern Arkansas. The present structure is the burial of the ridge. Recent detailed surface work by major oil companies has suggested smaller structures in other parts of the state, but so far they have not been definitely proved. Also considerable magnetometer and seismographic work has been done in the northern and central part of the state. The results of the operation of the seismograph are not yet available, but the magnetometer located many "magnetic highs" in this part of the state. Outside of the area of the Jackson structure, the exact cause for this magnetic variation is not known. In a portion of south Mississippi, considerable seismographic work has been done recently in an attempt to locate salt domes. While the details are not available, it has apparently met with little success. Prospecting by districts during the past year may be summarized as follows: Five wells of importance were drilled in the Amory district of east Mississippi. This district comprises all or parts of Monroe, Lee, Itawamba, Prentiss, .Alcorn and Tishomingo counties. Small gas was discovered at about 2500 feet. Several wells were drilled in the. Jackson district which is located in part or all of Hinds, Rankin, Madison and Yazoo counties. Some of these wells were abandoned and one was shut down most of the year

Jan 1, 1930

By Rossiter W. Raymond

In the case of The Eureka Consolidated Mining Company v. The Richmond Mining Company of Nevada, recently tried at San Francisco, California, the real defendant was the Richmond Consolidated Mining Company, of London; but this being a foreign corporation, holds its mining property in Nevada through the Nevada corporation of similar name, in which the London Company owns all the stock, except the few shares necessary to " qualify" the American directors. The trial would naturally have taken place in the Circuit Court at Carson City, Nevada, and before a jury. But by stipulation of the parties, the case was tried in San Francisco, before Hon. Stephen J. Field, Justice of the Supreme Court of the United States, Hon. Lorenzo Sawyer, United States Circuit Judge of the Ninth Circuit, and Hon. E. W. Hillyer, United States District Judge, for the District of Nevada. The hearing began July 23d, 1877. The witnesses occupied two weeks, and the argument of counsel three days. Very eminent lawyers were engaged on both sides; for the plaintiff, Messrs. Solomon Heydenfeldt, R. S. Mesick, John Garber, and H. J. Thornton; for the defendant, Messrs. S. M. Wilson, Thomas Wren, and J. J. Williams. The court held the case under advisement until August 22d, when Mr. Justice Field delivered its unanimous opinion in favor of the plaintiff. The action was a complaint in ejectment, and an appeal was taken to the United States Supreme Court. The questions at issue between the Eureka and the Richmond Company in this suit, comprised several points in the construction of the mining law of the United States, and its relation to the customs and regulations of the mining districts, which possess an importance and an applicability far beyond the limits of the case in which they arose. It is my purpose to state these points, the arguments

Jan 1, 1879

By W. Francis

Before attempting to describe the application of recently acquired knowledge to the classification of coal it will be as well to consider the objects at which a scientific classification should aim. Here one can not do better than to follow the example of Clarence Seyler,l by quoting from Huxley's "Classification of Animals:" "By the classification of any series of objects is meant the actual or ideal arrangement together of those which are like and the separation of those which are unlike, the purpose of the arrangement being to facilitate the operation of the mind in clearly conceiving and retaining in the memory the characters of the object in question. Thus there are as many classifications of any series of natural or other bodies as they have properties or relations to one another or to other things. But the statement of the characters of the class ... is something more than an arbitrary definition ... it expresses firstly, a generalization based on and constantly verified by very with experience; and, secondly, a belief arising out of that generalization—in other worda. the definition of the class is a statement of a law of correlation or coexistence . . . from which the most important conclusions are deducible." In that same sense writes John Stuart Mill, in the chapter on classification in his "Logic:" "The ends of scientific classification are best answered when the objects are formed into groups concerning which a greater number of general propositions can be made, and these properties more important, than could be made respectiug any other groups into which the same things could be distributed. The properties, therefore, according to which objects arc classified should, if possible, be those which are causes of many other properties, or, at any rate, which are sure marks of them." Now in the case of coal, the properties which have been used from time to time for classification purposes are the ultimate analysis, volatile matter, caking power, calorific power, burning properties, etc. Seyler has shown that there is a general law of correlation or coexistence between the ultimate composition and the other properties. The ultimate composition, therefore, of the natural series of bodies known as coal is the

Jan 1, 1930

By G. Don Sullivan

Although the first application of strip mining dates back to 1866, the true origin of today's problem of land reclamation is found in World War II, when the yawning war machines demanded more, and faster fuel production. To meet the new wartime demands, the strip coal mining companies that had been producing coal for the normal needs of industry and commerce during peacetime worked to the full extent of their capacities but were unable to satisfy the voracious demand. To supplement the production of the established mining firms, a host of temporary, make-shift coal strip operations came into being-road contractors, ditchers and foundation excavators, earth movers of every type became strip coal operators. Unfortunately, many were of the here-today-gone-tomorrow category, and showed little concern for the condition of the land after mining. Likewise, the land owners of the mined properties (most of the land was on royalty lease or tonnage contract) showed little concern. Land owners realized from their acreages more income during the war years of coal production than could have been obtained in two or three lifetimes of conventional farming or other land uses. Most of these mined lands were sub-marginal with little productive promise. As a result the wartime stripping produced most of what are known today as "orphan banks" or "abandoned strip pits." It is of these that so much of the present day complaints about strip mine reclamation are being made.

Jan 3, 1967

By R. M. Brick, Arthur Phillips, A. J. Smith

A PREVIOUS publication1§ has described the effect of quenching stresses on the lattice parameter values of high-purity aluminum-copper alloys particularly with reference to the solution and precipitation of CuA12. A similar study has been made of the aluminum-rich aluminum-magnesium alloys. Attention has been directed in the present investigation. to the magnitude of the quenching stresses as affected by the specimen size and shape, the number of solute atoms and the quenching rate. The effect of cooling stresses in causing plastic deformation or cracking has been considered in relation to the physical properties of the alloy. On reheating alloys in the two-phase field, the time required for precipitation to occur has been observed in connection with the degree of supersaturation, the rate of diffusion of the solute atoms as a function of the comparative atomic radii, degree of strain, temperature of reheating and grain size. A few qualitative comparisons on the relative effect of these factors have been drawn between the aluminum-copper alloys and the aluminum-magnesium alloys. STRAIN IN SOLID-SOLUTION ALLOYS A 10 per cent magnesium alloy in the form of chill-cast bars was furnished by the Aluminum Company of America through the courtesy of L. W. Kempf. Additional alloys were prepared using aluminum (99.95 per cent Al) and high-grade magnesium. The alloys listed in Table 1 were melted in an Acheson graphite crucible under a flux of fused MgCl2, CaC12, NaCl. Chill-cast rods were sealed under vacuum

Jan 1, 1935

By S. B. Patterson, A.R. Amos

Log washers have been used for many years in the washing of clay iron ores, phosphate rock and manganese ores, but not until the past 15 years have they been employed to any extent in the preparation of aggregate materials and fluxing stone. For a machine of such importance where tenacious clay or soft rock must be eliminated, there are few data generally available. The purpose of this paper is to set forth the results obtained from several operations, together with a few suggestions for planning a specific installation. Where the material to be washed out consists of loose surface soil, silt, or small amounts of quickly soluble clay, there is little competition with other forms of washers, because greater power and maintenance are required for the operation of log washers, but where the foreign matter is a stiff clay, such as occurs with high-calcium limestones and in marginal gravel deposits, the ability of other kinds of washers to eliminate completely the hard clay balls is at least uncertain. Then the log washer comes into its own field, for with the breaking and churning action of the logs it will clean out the toughest clay. Even with material from the hydraulic dredge, if it contains tough clay, the log washer is desirable unless the gravel is subjected to a costly soaking and rehandling process. Recently there has been a considerable development in other types of machines to accomplish these results but it is not within the scope of this paper to make comparisons between competitive types, but to present the best obtainable data on log washers only. From the primitive design that gave it its name, a long log hewn from a tree, with paddles forged to shape from strap iron and attached by lag screws, the log washer has gradually been developed to the present all-steel type. As now manufactured, the log washer consists essentially of two built-up logs on which are mounted a series of paddles, carried by shafts fitted at the ends of the logs on bearings fastened outside the enclosing steel box, or trough, which is set at an angle of about 5" to 10" and into which the material is fed. Stuffing boxes at the places where the shafts pass through the box at the lower end are equipped with water-

Jan 1, 1938

By A. R. Amos, S. B. Patterson

Log washers have been used for many years in the washing of clay iron ores, phosphate rock and manganese ores, but not until the past 15 years have they been employed to any extent in the preparation of aggregate materials and fluxing stone. For a machine of such importance where tenacious clay or soft rock must be eliminated, there are few data generally available. The purpose of this paper is to set forth the results obtained from several operations, together with a few suggestions for planning a specific installation. Where the material to be washed out consists of loose surface soil, silt, or small amounts of quickly soluble clay, there is little competition with other forms of washers, because greater power and maintenance are required for the operation of log washers, but where the foreign matter is a stiff clay, such as occurs with high-calcium limestones and in marginal gravel deposits, the ability of other kinds of washers to eliminate completely the hard clay balls is at least uncertain. Then the log washer comes into its own field, for with the breaking and churning action of the logs it will clean out the toughest clay. Even with material from the hydraulic dredge, if it contains tough clay, the log washer is desirable unless the gravel is subjected to a costly soaking and rehandling process. Recently there has been a considerable development in other types of machines to accomplish these results but it is not within the scope of this paper to make comparisons between competitive types, but to present the best obtainable data on log washers only. From the primitive design that gave it its name, a long log hewn from a tree, with paddles forged to shape from strap iron and attached by lag screws, the log washer has gradually been developed to the present all-steel type. As now manufactured, the log washer consists essentially of two built-up logs on which are mounted a series of paddles, carried by shafts fitted at the ends of the logs on bearings fastened outside the enclosing steel box, or trough, which is set at an angle of about 5" to 10" and into which the material is fed. Stuffing boxes at the places where the shafts pass through the box at the lower end are equipped with water-

Jan 1, 1938

By V.K. Zworykin

Throughout its development the science of electronics, like so many other branches of science and industry, has been indebted to the metallurgist. Metallurgy has provided the electronic engineer with conductors to furnish passage for electrons outside of his evacuated tubes: it has developed tungsten and tantalum wires for emitting electrons and various refractory metals and alloys suitable for electrodes, which receive them and guide them within the tube; finally it has supplied ferromagnetic materials both for shielding electronic apparatus from magnetic fields and for forming highly concentrated fields for deflecting electron . Today I hope to show you that electronics has not been altogether ungrateful for this assistance. More specifically, I wish to indicate the role that the electron microscope, a relatively recent product of electronic engineering, is playing even now in the study of metals. Every metallographer is aware that his standard metallographic microscope will not reveal structural detail involving separations smaller than a certain fraction —at the very best a tenth—of a micron. This limitation, he knows, is a consequence of the fact that the wave length of the light employed for forming the image has this order of magnitude. It is, thus, a property of all light microscopes. TO overcome it, a different imaging medium must be employed, The existence of such a medium became evident when it was demonstrated1 that electrons were affected by magnetic and electric fields with axial symmetry just as light is affected by glass lenses; these fields, or "electron lenses," curve the paths of electrons reaching them from an object located on the axis of symmetry in such a manner that, at some distance from the lens, a true image of the object is formed. Furthermore, although a wave length may . be ascribed to electron beams just as to light, this wave length is much shorter; for electrons accelerated through a difference of potential of 50 kilovolts, the wave length is only about one hundred-thousandth of that of visible light. Actually, the elcctron microscopes of today resolve detail one hundred times as fine as light microscopes; if the maximum useful magnification of the latter is taken to be a thousand, that of electron microscopes is one hundred thousand. The Electron Microscope Since electrons are readily scattered and absorbed by matter, specimens to be observed in the electron microscope must be prepared to be less than one micron in thickness; furthermore, the interior of the microscope must be carefully evacuated to prevent collisions between the clectrons and the molecules of the air. Finally, as already mentioned, the lenses are formed by axially symmetric magnetic or electric fields, and not by any material medium such as glass. Apart from these basic differences, the electron microscope closely

Jan 1, 1943

By V. K. Zworykin

Throughout its development the science of electronics, like so many other branches of science and industry, has been indebted to the metallurgist. Metallurgy has provided the electronic engineer with conductors to furnish passage for electrons outside of his evacuated tubes: it has developed tungsten and tantalum wires for emitting electrons and various refractory metals and alloys suitable for electrodes, which receive them and guide them within the tube; finally it has supplied ferromagnetic materials both for shielding electronic apparatus from magnetic fields and for forming highly concentrated fields for deflecting electron . Today I hope to show you that electronics has not been altogether ungrateful for this assistance. More specifically, I wish to indicate the role that the electron microscope, a relatively recent product of electronic engineering, is playing even now in the study of metals. Every metallographer is aware that his standard metallographic microscope will not reveal structural detail involving separations smaller than a certain fraction —at the very best a tenth—of a micron. This limitation, he knows, is a consequence of the fact that the wave length of the light employed for forming the image has this order of magnitude. It is, thus, a property of all light microscopes. TO overcome it, a different imaging medium must be employed, The existence of such a medium became evident when it was demonstrated1 that electrons were affected by magnetic and electric fields with axial symmetry just as light is affected by glass lenses; these fields, or "electron lenses," curve the paths of electrons reaching them from an object located on the axis of symmetry in such a manner that, at some distance from the lens, a true image of the object is formed. Furthermore, although a wave length may . be ascribed to electron beams just as to light, this wave length is much shorter; for electrons accelerated through a difference of potential of 50 kilovolts, the wave length is only about one hundred-thousandth of that of visible light. Actually, the elcctron microscopes of today resolve detail one hundred times as fine as light microscopes; if the maximum useful magnification of the latter is taken to be a thousand, that of electron microscopes is one hundred thousand. The Electron Microscope Since electrons are readily scattered and absorbed by matter, specimens to be observed in the electron microscope must be prepared to be less than one micron in thickness; furthermore, the interior of the microscope must be carefully evacuated to prevent collisions between the clectrons and the molecules of the air. Finally, as already mentioned, the lenses are formed by axially symmetric magnetic or electric fields, and not by any material medium such as glass. Apart from these basic differences, the electron microscope closely

Jan 1, 1943