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By Robert Adams

Secondary or scrap materials appear at all stages in the industrial process and in a bewildering variety of forms, grades, and values. It is useful to begin analyzing them by dividing the broad concept of "Secondary Supply" into three parts First, the concept must encompass the stock, or pool, of secondary materials. In the process of satisfying his wants, man produces desired products from the materials and natural resources found around him. As long as the rate of production is greater than the rate of obsolescence of a given product, the total stock or pool of materials embodied in that product will increase in size This stock concept relating to secondary materials is directly analogous to the "resource" concept used for primary raw materials in the preceding chapter, and includes all materials embodied in existing products (Obviously, this excludes those materials which are destroyed in the consumption process, viz , fuel oil burned to provide heat.) Consumption of a primary material in a productive process tends to reduce the resource base of that primary material In direct contrast, however, the production or use of products increases the resource base of the secondary material. Thus, we find that a country which has no resource of a primary material can, by importing products that contain the material, build up a large enough stock to provide a basis for secondary recovery. The estimated growth of the pool of copper in use in the United States through 1967 is shown in Table 5.B.1.a The estimate of 39 3 million tons at the end of 1967 includes only technologically recoverable copper and is, therefore, somewhat less than the stock concept described previously, which does not distinguish between recoverable and unrecoverable material. Nevertheless, Table 5 B.1 does give an idea of how a nation's secondary resource of a material can grow over the years. A second aspect of the concept of secondary supply is the generation of secondary materials. This includes materials generated as scrap in production as well as the movement of a material out of the stock of existing products via wear, damage, or obsolescence The quantity of materials generated is usually either nearly or completely independent of the technologic capabilities and economic forces which prevail in the secondary recovery market.b The justifications for and the qualifications to this statement are considered later. The final aspect of the concept of secondary supply consists in the secondary recovery process It is at this point that the technologic and economic forces of the secondary recovery market become the controlling fac-

Jan 1, 1976

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 Joseph Kaye Wood

A metal is said to be overstrained when it is deformed beyond the elastic limit at a temperature well below the critical range, as in cold working. Quantitatively, overstrain might be considered as that part of the total elastic deformation of the piece of metal, left over after the external load is removed, that added to the permanent deformation due to plastic action will give the total permanent deformation. Ordinarily the effects of this phenomenon, which vary with the internal residual stress probably in accordance with Hooke's law, are more noticeable when the yield point of the metal is exceeded, but they probably also exist to a smaller degree when the load is just large enough to cause the least amount of permanent set. These effects, which we recognize as the result of overstrain, are as follows: 1. An apparent increase of the elastic limit in tension and a decrease of the elastic limit in compression, provided the external load is tensile. The reverse is true when the load is compressive. 2. An elastic after-effeet in which time and temperature are important factors. 3. A state of imperfect elasticity in which Hooke's straight line becomes slightly curved, giving rise to an hysteresis loop. 4. In addition to the apparent increase in the elastic limit, such properties as the hardness, ultimate strength, and resistance to fatigue failure are increased, provided the overstraining has not been carried far enough to make the metal brittle. 5. Correspondingly the ultimate elongation, reduction in area, magnetic quality, ratio of endurance limit (fatigue breaking stress) to elastic limit, and resistance to season cracking (in certain copper alloys) are decreased. The question naturally arises: how do these changes in the properties of a metal resulting from overstrain influence our method of design? The fact that most of the desirable qualities are increased makes overstraining a favorable process, from an engineering standpoint; but on the other hand, the loss of such qualities as perfect elasticity and complete

Jan 1, 1924

By M. R. Geer

THE increase in the number of coal-cleaning plants employing dense-medium processes occurring since 1946 is especially interesting when viewed historically. Both sand and magnetite were introduced as material for heavy mediums at about the same time, sand in the Chance process in 1921 and magnetite in the Conklin process in 1922, but from that point on their records diverge. The Chance process enjoyed a steady growth from its inception, whereas no additional magnetite plants were built in the United States for over 20 years. Then, following the close of the World War 11, magnetite was again introduced, this time with marked success. During the following years some 47 plants employing magnetite medium were built.

Jan 7, 1953

By W. D. Haselton, J. B. Newsom

SAFER, cheaper, and faster sinking of mine openings seems to have been realized with the completion of a borehole 5 ½ ft. in diameter and 1208 ft. deep, in Minnesota, during 1938. Moreover, as the opening is to be used solely for ventilation, its circular cross section, smooth walls and freedom from fire hazard recommend it in comparison with the usual timbered shafts of rectilinear cross section. It should be pointed out that a drill hole sunk without the use of explosives frequently will stand open without support, whereas a shaft sunk by standard procedure using dynamite usually must be timbered because of the wall-shattering effect of explosives. The saving in maintenance resulting from the elimination of timber is obvious. The work was done by Pickands Mather & Co. at its Zenith mine, Ely, Minn. This company wanted a ventilation opening capable of delivering 50,000 cu. ft. of air per minute to the fourteenth level, 1200 ft. below the surface. While several general articles1-3 have described the method used, detailed time and performance records have not been presented before. Moreover, with a method as new as this, it is important to compare the results attained under widely varying conditions. Among the new conditions faced at Ely were some extremely hard rock, a series of vertical fractures, seepage water, and some long stretches of sound rock which, combined with excellent equipment, gave a chance to operate without unusual delays. Developments in boring large holes have generally taken the obvious course of increasing the size of the equipment, a line of attack that has resulted in putting down 3-ft. diameter holes at damsites for studying the foundations4 and in drilling ventilation openings between levels at Butte.5 Such drills operate from the collar of the hole, and the power from the drill is transmitted to the cutting tool through drill rods or pipes. In order to keep down the volume of rock that must be ground to sludge, the cores in large-diameter drilling are made as large in diameter as possible. Their large diameter increases their weight per foot of length, which

Jan 1, 1939

By E. D. Gardner

AGAIN in 1945, the fourth year of World War 11, the American mining industry met the necessary demand made upon it for metals. Lack of labor prevented full production in some districts; maximum output, however, was maintained with the man power available. Development work and maintenance of mechanical equipment were neglected in favor of immediate production. Drafting of the younger men continued throughout the year, and the loss of personnel to war industries with higher wage rates continued up to "V-J" Day, Aug. 14. Labor shortages were more critical in 1945 than in 1944 though the man-power situation eased for some districts in the last quarter of the year. The trend in mining for the most part was to increase tons per man-shift by continued increased mechanization and refinements in methods and practices; larger equipment was installed where practicable. Labor shortages, together with the current higher wage rates, have advanced mechanization several years ahead of normal progress. The manpower shortage and the employment of inexperienced men had the effect of decreasing the average efficiency of the individual workman, but this condition was largely balanced by improved organization, greater efforts to improve labor relationship, and increased use of incentive pay systems. Safety instruction was emphasized, personnel contacts were increased, and more frequent foremen meetings were held to clarify contract agreements. Many of the large companies maintained schools to train green workmen.

Jan 1, 1946

By Frederick L. Knouse

THE south border of Espirito Santo begins about 400 km. north of Rio de Janeiro and extends along the Atlantic Coast northward some 325 km. and inland 100 to 150 km. The area under consideration, where quartz crystal of strategic grades has been mined, extends from 19° to 21° and 30" south latitude; and from 40° to 41° and 30" west longitude. This includes the central part of Espirito Santo, chiefly south of the Rio Doce from the Atlantic ocean, and west across the border into Minas Gerais near the town of Aimores, in the municipalities of Aimores, Minas Gerais; Baixo Guandu, Santa Teresa, Santa Leopoldina, Colatina, Joao Neiva, Fundao and Domingo Martines, Espirito Santo (Fig. 1). During 1943 and the first half of 1944, this region accounted for approximately 3 to 5 per cent of the quartz crystal produced in Brazil. Shipments of crystal have been made chiefly by rail to Rio de Janeiro. This region is serviced by the E. F. Minas-Vitoria and E. F. Leopoldina to Rio de Janeiro through Vitoria; and by the E. F. Minas-Vitoria and E. F. Central do Brasil through Bello Horizonte, Minas Gerais to Rio de Janeiro. The major deposits are accessible from the railheads by dirt roads, some being 5 to 30 km. off the road, reached by trail. In 1943 and the first half of 1944, the bulk of the production was from inter mountain marshes and adjoining hillside alluvial placer deposits in the zone surrounding the town of Santa Teresa. Most of these deposits were formed from the erosion of pegmatites, quartz veins and pockets in the gneiss, with minor quantities produced from miarolitic cavity fillings in the granitic rock. EARLY OPERATIONS Mining of quartz crystal in this region began in 1928, and has been stimulated by the market demand for military uses. Before 1936 little attention was given to it, either in Espirito Santo or eastern Minas Gerais. From 1936 to 1941 the Japanese sent agents to various points of production or potential production to acquire quartz through purchase. They bought crystal as small as 10 grams. Since 1941 only the United States and Great Britain have received quartz from Brazil. The United States purchases crystals of loo grams and larger for strategic purposes. The first known discoveries were made either in the municipalities of Aimores, Minas Gerais, or in Baixo Guandu, or Domingos Martines, Espirito Santo. Marketable quartz crystal was first found either in the massive quartz replacement veins of the Victor Hugo mine in the municipality of Domingo Martines, or in the large cores of quartz in the pegmatites near Baixo Guandu, extending into Minas Gerais. PRODUCTION The production of quartz in Espirito Santo from 1936 through 1941 as recorded

Jan 1, 1946

By S. Maemura

Miike Colliery of Mitsui Coal Mining Company, the biggest and oldest coal mine in Japan, is producing a quarter of the national coal production, about 5.2 million tons of clean coal annually and almost a half of which is now being mined under the "slicing Mining System". The slicing system is a mining method to mine a thick coal seam dividing it into two faces, upper and lower. Its history started nearly 20 years ago. However, the all-around modernization of this system has made little progress up to recent years, while mining methods for single longwall faces has made a remarkable progress together with the improvements in mining machineries, self advancing supports and so on. The reason was that the tremendous difference in adaptabilities of mechanized face equipments existing between the upper and lower faces has made it very difficult to increase the total production capacity of slicing system. After our persistent study for seventeen years, we have recently realized successfully the quite satisfactory slicing system, applying the combination of shield type self advancing supports and double ranging drum cutter at both faces. We are now fully convinced of that the high efficient, quite safe and improved slicing system has been basically established for the present. This paper intends to brief the transition on the combination of self advancing supports and mining machines, its results and further to detail the development of shield type self advancing support for upper face and artificial roof material which shall be the key point to be successful in full mechanization of slicing faces.

Jan 1, 1976

By C. G. Rhodes, D. Kramer

The kinetics of precipitation of transient a phase during the transformation in U-16 wt pct Mo between 400° and 550°C were studied using quantitative metallography and electrica1 resistiuity measurements. The volume percent of a phase goes through a maximum in time, corresponding to a critical degree of progress of y' formation. prior to its re-solution after prolonged annealing. The fastest rate of a precipitation oc-cuvs at 500°C with a concomittant lowest peak of 9.5 vol pct a. At 450°C, 14 vol pct a, greatest fov any temperature, was observed after 24 hr witlz an associated slowest rate of formation. a precipitation at 400°C ceases after approximately 160 hr and the amount of a present remains unchanged after long times at temperature; no y' was observed metallographically at this temperature. IN the U-Mo system at 16 wt pct Mo, an ordering reaction takes place below 600°C, see Fig. 1, whereupon the random bcc solid solution, y, transforms to the ordered bct phase, y'."2 The new unit cell is constructed of three old unit cells somewhat distorted. While attempting to study the kinetics of this transformation it was observed that an unexpected phase was precipitating out early during the transformation anneal reaching appreciable amounts before disappearing after long times. The y' appeared in the presence of this new phase and after long times constituted the whole sample. Owing to the high optical activity of this unexpected phase under polarized light, it was suspected to be the a phase. Subsequent X-ray powder pictures confirmed this belief. The kinetics of a phase formation and disappearance is the subject of this paper. EXPERIMENTAL PROCEDURE A) Alloy Preparation. Alloys for this study were prepared by vacuum induction melting normal reactor grade uranium and 99.5 wt pct Mo pellets in thoria crucibles. Two ingots were prepared, and sections of the top and bottom of each ingot were chemically analyzed for uranium and molybdenum content. The results of the analyses appear in Table I. B) Metallography. Samples of 16M were wrapped in tantalum foil, sealed in evacuated (5 X 10"6 mm of Hg) quartz capisules, and annealed at 1110"C prior to being transferred directly to the transformation temperature. They were examined metallographically after increasing times to determine the progress of the transformation at 400°, 450°, 500°, and 550°C. The samples were prepared for metallographic examination by mechanical polishing with diamond paste and electrolytic polishing with a solution of glacial acetic acid and chromic acid. Since the y' phase is tetragonal, its presence can be detected by viewing the sample in polarized light. To increase the contrast between y' plates, the samples were electro-etched in a 10 pct oxalic acid solution. To reveal a phase in bright field (it can be seen in polarized light in the "as-polished" state), the samples were electro-etched in a solution of citric acid and nitric acid. To determine the vol pct a phase, a variation of the one dimensional systematic point count method as described by Hilliard and cahn3 was used. The

Jan 1, 1962

By Oscar A. Glaeser

MINE VENTILATION is an important factor in mine maintenance as well as having direct bearing on labor efficiency. Effective ventilation systems are costly, especially those for the deeper mines, but with intelligent direction the worth of a system is usually greater than its cost. In most mines using mechanical ventilation, and practically all deep mines, it has been found beneficial to equipment, timber, and the ground, to run the fan or fans continuously even though production has been curtailed or entirely suspended. Therefore, economies in ventilation may be overlooked when general cost reductions are necessary. The operating costs of a well-designed ventilation system should be capable of reduction during periods of curtailed or suspended operations. A mine that is ventilated by splits, or that can be sectionized, can reduce its fan-power costs considerably, and provisional divisions can sometimes be made in other mines, in which the air is ordinarily coursed through all the workings, without harmful effects.

Jan 1, 1932

By S. A. Mahon

AN interesting feature among the mining structures, on the Mesabi. iron range is the iron ore stacker erected in 1934 at the Mesabi Chief washing plant at Keewatin, Minn. It is built of structural steel, and carries a system of belt conveyors which collects the washed product of the plant and places it on a stockpile for subsequent shipment. Although the only one of its kind in the Lake Superior iron district, installations of similar nature have been used elsewhere in the handling of coal and gravel and in earthwork construction. The reasons for stocking Lake Superior iron ores may be as various and diversified as the methods used in building the piles. At the under¬ground mines the existence of the huge piles in evidence at each active shaft is due, principally, to climatic conditions in this north country where the shipping period is much shorter than the operating season. Conversely, at the washing. plants it may be desirable to stockpile washed ores because the shipping season is commonly of longer duration than the period during which the plants may be operated. Washed ores, and mixtures of which washed ores are a component part, have found high favor with the oper

Jan 1, 1935

By D. A. Farmen

INTRODUCTION In early 1978, engineering personnel at The Carter Mining Company began using photogrammetry coupled with a computer modeling technique to aid in mine planning efforts. The decision to develop this approach was based on the following needs: 1. A method to accurately capture excavated quantities for reporting purposes, 2. A method to produce accurate up-to-date maps for planning purposes, and 3. A computer-based mine-planning technique that would be compatible with techniques used in the past. The system developed utilizes a photogrammetric contractor to provide thousands of aerially-surveyed data points for input into the computer system. Each month the Rawhide and Caballo mines are flown by the photogrammetric contractor. The terrain of the active pit area is digitized and punched out on computer cards. This information is read into The Carter Mining Company's computer facilities, and an updated two-dimensional topographic grid model of the pit is generated. This surface is used to generate quantities moved during the month, to update isopachs, and to update quantities contained in fixed block progression polygons used for forecasting purposes. The system has greatly reduced the amount of manhours spent in field surveying and provides a useful tool for expeditiously evaluating many different forecast cases. It also provides the

Jan 1, 1983

By F. S. Crawford

IRON and copper are mined in the Lake Superior district. The iron mines of the district have the best safety record for that industry in the country as a whole, while the copper mines of the district rank second in two of the four years recorded (Table 1). In Utah copper comes mainly from open-pit mines, which enables that state to lead easily in safety. All of the Michigan production comes from deep underground workings. About 60 per cent of the iron miners in St. Louis County, Minnesota, are employed at open-pit mines; this favorably affects the combined open-pit and underground accident-frequency rate, as this county provides most of the Minnesota-mined iron ore. In Michigan, however, there are few open-pit mines, the bulk of the production coming from underground mines, while all of the Wisconsin production, just across the state line from Michigan, is from underground mines. In spite of the fact that fewer mines in Michigan use the safer open-pit method, the iron-mining industry of that state maintained a consistently low record from 1931 to 1934; however, it was many points behind its nearest competitor, Minnesota, with its much greater production from open-pit mines.

Jan 1, 1939

By Nicholas J. Grant, William H. Ferguson, Bill C. Giessen

Ta-lr alloys have been examined over the complete range of compositions using metallographic and X-ray techniques. The terminal solid-solubility limits, solidus temperatures, and intermediate phases were determined. There are four inter-mediate phases: o, tetragonal, analogous to a (Fe-Cr); 0,. orthorhombic; az, tetragonal; and a TaZr,, cubic, AuCu, structure. Of these, o and a, melt peritecticaLly, a, decomposes peritectoidally, and a TaIrs has a congruent melting point. Three peri-tectic and one eutectic reactions occur. 1 HE Ta-Ir phase diagram has not been treated in the literature. Intermetallic phases and terminal solid solubilities have been described and estimated.'-4 The previous findings have been confirmed in this work. A complete diagram with additional phases and solidus curves is presented. EXPERIMENTAL METHODS Starting materials were tantalum powder of 99.8 pct purity, supplied by the National Research Corp., Cambridge, Mass., and iridium powder of 99.9 pct purity, supplied by the Bishop Co., Malvern, Pa. Both powders were -200 mesh. Table I lists the analyses as given by the suppliers. A standard procedure was employed in making the alloy buttons, which was described in detail in Refs. 5 and 6, and which included repeated arc-melting of powder compacts and determination of the composition by the weight-balance method. This is especially justifiable due to the similar vapor pressures of tantalum and iridium. In the critical parts of the diagram, a spacing of 1/2 at. pct was used, based on premelted master alloy material. The observed structures and X-ray spectra were consistent with the composition sequence of the alloys. Table II lists the final alloy atomic percentages with the calculated percent error of composition. Cross sections representative in grain size and composition were selected for the study, as described in Ref. 5. Based on prior experience, no contamination from the tungsten electrode was considered. Temperature measurements were obtained using a Leeds and Northrup optical pyrometer and have been described extensively in Refs. 5 and 6. All heat treatments were made in the high-vacuum tantalum tube furnace mentioned in Ref. 5. Samples annealed in tantalum containers cooled from 1800" to 1000"~ in 5 sec; those annealed in ceramic crucibles cooled over the same range in 15 to 30 sec. The thermal treatments are listed in Table 111. All specimens were homogenized at 1735°C for 24 hr. Tantalum-rich compositions were treated in tantalum buckets. Iridium-rich compositions were annealed in tantalum buckets below the eutectic temperature of 1950°C; up to 2200°C, tungsten-lined tantalum baskets were used; and above 2200°C thoria crucibles were used. It was found that refractory oxides (in early stages of the investigation alumina crucibles were used up to 1800°C and thoria crucibles were used to 2400"~) give off minute amounts of oxygen and thereby influence the microstructure considerably, or react directly with the alloys.

Jan 1, 1963

By Charles E. Wait

The old laboratory at the School of Mines was among the notoriously bad ones, being situated in apartments of the main collegebuildings not originally intended, and conspicuously unfit, for the use to which they were put; while, as in many of our schools and colleges, the assaying was done in the basement of the college. Prominent among the disadvantages of such an arrangement are insufficient light, poor ventilation, and little or no provision to carry off offensive gases. It is not my intention now to present a complete description of this building. I wish merely to call attention to a few points in its construction and equipment, which may prove of interest to those who contemplate erecting buildings for snch work, and who may be, as we were in this instance, limited as to funds. In this laboratory every room is well lighted; all rooms used by students are well ventilated, and are provided with closed hoods for

Jan 1, 1887

By AIME AIME

A PAPER recently presented before the Anthracite Section of the A. I. M. E. by S. J. Phil- lips, Mine Inspector, Fifth Anthracite District, Department of Mines of Pennsylvania, covering the water hazards in the anthracite coal mines of the Lackawanna River Valley, was especially timely because the conditions there are duplicated to a large extent in the Wyoming Valley, which is traversed by the Susquehanna River with its many large tributary streams. Also, in the southern anthracite field, where there are a number of large creeks, similar pumping problems and mine water hazards will in time be presented if mining is continued to its conclusion.

Jan 1, 1936

By A. Kounosu, T. Fujita, J. Shimoiizaka, K. Nakatsuka

Stable aqueous dispersion of magnetite colloid of about 10 nm in diameter was obtained by allowing an anionic or nonionic surfactant to adsorb on the hydrophobic surface of magnetite particles prepared by monomolecular adsorption of oleate. Sodium dodecylbenzene sulfonate, sodium oleate and poly (oxyethylene) nonyl phenyl ethers whose hydrophilic-lipophilic balance (HLB) are higher than 12 were suitable for giving a second adsorption layer to obtain a stable dispersion. Stability of the colloidal suspensions depends upon pH of the solution and is controlled by the dissociation of the adsorbed surfactant in the second layer. The addition of ethyleneglycol, which was used for lowering the freezing point of the dispersion, did not affect the stability when used in amounts smaller than 60% of water. Preparation of diester-based ferrofluids was also attempted by the same procedure using a nonionic surfactant as second layer molecule. Hydrophobic magnetite colloid, which had been preliminarily coated with mono-molecular oleate, was suspended in di(2-ethylhexyl) agipate, azerate, and sebacate respectively, and dispersion stability was investigated by adding various poly (oxyethylene) nonyl phenyl ethers of different HLB values. It was found that those with HLB values between 10.9 and 13.3 were suitable for this purpose. Stabilities of the dispersions in a magnetic field were investigated up to 1 T by applying an electromagnetic field. No separation of dispersant was observed and each magnetite dispersion displayed the characteristics of a magnetic fluid.

Jan 1, 1980

By Edward H. Robie

NEVER before have the annual company reports in the mineral industry field exhibited the typo-graphical art so abundantly as does the current crop. Time was when most company reports made a drab appearance and dry reading, mostly confined to financial data and text that gave little information to the public or technical men. Now, the dollar statistics assume less importance. Considerable information is given on what is going on at the company's plants, new equipment being installed, new methods, properties under development, ore reserves and grades, and similar information of interest to professional men working in the field. We have one suggestion for further improvement: The names of the officers and directors of the company are always given, but only a few companies give the names of the principal operating officials. We think, in the case of a mine for example, that the name of the general manager, his assistant, the mine and mill superintendents, and any other top operating officials who have been largely responsible for the success of operations, are worthy of mention. The reports are now widely read and this recognition is due them. Conspicuous among the annual reports that we happen to have seen, in point of typographical attractiveness, are that of the Texas Co., celebrating its fiftieth anniversary with a gold-plated cover and gold printing inside; and that of Noranda Mines Ltd., with a red and black cover that would attract attention anywhere. Comment on economics, taxes, and labor give an excellent picture of what our industry is facing. Consider the following, from the report of the Union Oil Co. of California:

Jan 1, 1952

By W. E. Forsythe

WHEN measuring ordinary temperatures, the instrument is generally placed in very close contact with the body the temperature of which is desired. However, if the temperature of the source is continually raised, a point is soon reached where no known substance will, in general, remain constant in any of its temperature-measuring properties if placed in direct contact with the source. Also, it is occasionally necessary to measure the temperature of a source that 'is so small or so situated that it would be very hard to bring the measuring instrument into direct contact with the source. When these conditions exist, advantage is taken of the well-known fact that all bodies, when at sufficiently high temperatures, send out radiation in amounts readily measurable. This radiation has been found to be related to the temperature. The temperatures of very hot bodies have probably always been judged by the color, or the brightness, of the light given off. With practice, one can estimate probably within 50° to 100° C. of the correct value. However, if judgment is left to the eye alone, very much larger errors are sometimes made, due to

Jan 9, 1919

By St. John, JOHN Ancel

AT THE New York meeting of the Institute of Metals Division in February, 1927, Jeffries and Tarasov presented a paper on Tungsten and Thoria,1 in which the experimental facts were interpreted in accordance with the prevailing point of view that the thorium is present as the oxide, thoria. In discussing that paper the writer of this article stated that his own investigations, which had been unavailable to Messrs. Jeffries and Tarasov, showed that the so-called "thoriated" tungsten filament failed to disclose any sign of the oxide when subjected to X-ray diffraction analysis, but did give plenty of evidence of the presence of metallic thorium and, in certain cases, of a material believed to bean alloy of tungsten in thorium. Since these results were completely at variance with the results reported in the paper under discussion and with other papers which had preceded it from time to time in the past, it was felt that further discussion should be withheld until the new evidence could be presented adequately. Arrangements were therefore made to present that evidence at this meeting. MATERIAL EXAMINED The material examined was high-emission filament such as is used in radio tubes, supposed to contain about 0.75 per cent. thoria. The actual analysis was not stated.

Jan 1, 1927