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By L. C. Graton

THE Federal taxes on incomes and excess profits are of course heavy. In 1917, the value of the mineral production of the United States was a little in excess of $5,000,000,000. The total of Federal taxes for that year, for the mineral producing companies, as computed by themselves, amounts, according to tentative compilations, to about $207,000,000, and the total for the comprehensive group of mineral and metal indus-tries to about $766,000,000, which figures represent respectively 9.5 per cent. and 35.1 per cent. of the total tax paid by all corporations. Be-cause of greater complexities in applying the revenue laws to mineral properties than to most other industries, opportunity is afforded for wide differences of view. The taxes indicated above, therefore, are not final

Jan 11, 1919

By J. T. Price

The study was undertaken to investigate the effect in the charge to a blast furnace of zinc and alkali contents, which tend to form accretions and scaffolds in the upper sections of the furnace. Commercial iron oxide pellets were reduced in a CO:N2, 40:60 gas mixture in a 5-cm by 5-m counter-current reactor (Rist-type apparatus) designed to simulate blast-furnace conditions. Pellets from a commercial magnetite concentrate were prepared in the laboratory with zinc (1% ZnO) and alkali (1% KOH) additions to the concentrate. Reducibility, crushing strength and swelling tests were carried out and the results compared with test data from pellets prepared without additions. The results indicated normal behaviour for those pellets containing zinc, whereas those containing alkali swelled catastrophically under the same reducing conditions.

Jan 1, 1977

By James B. Cathcart

Marine phosphorite deposits occur in Braxil, in the Bambui Group of late Precambrian or Early Cambrian age. The phosphorite is laminated, isoclinally folded, and is composed of black, elongated apatite pellets and quartz grains cemented by quartz and muscovite. Abundant, narrow quartz veinlets cut through the .rock at right angles to the elongation direction of the pellets. The phosphorite is 0 to 80 m thick and contains 5 to 30 percent P2O5. The deposit is elongate towards the northeast, and the central, thickest, and richest part is bounded by faults. Measured reserves are about 250 million tons that average a bout 13 % P205. Preliminary testing indicates that grinding, scrubbing, and desliming will produce a material usable for fertilizer manufacture at a cost competitive with imported phosphate fertilizers.

Jan 1, 1979

By Lauren A. Wright, A. E. J. Engel

Under the designations "industrial talc" and "soapstone" are included earth materials of widely different chemical and mineral compositions. Talc, the mineral, is a hydrous magnesium silicate, with a suggested theoretical formula H2Mg3(SiO3)4 or H2O.3MgO.4SiO2, which postulates 63.5 pct SiO2, 31.7 pct MgO, and 4.8 pct H20.18 Single grains or leaves of talc, however, seem to have variations in water content that range from 3.5 pct to more than 7 pct, as well as slight differences in the proportions of MgO and Si02.20 Most of the industrial talcs produced in the United States do not approach the composition given above (see Table 1), but are essen- [ ]

Jan 1, 1960

By R. Chanchani

Single and mixed mineral flotation behavior and the mechanisms for the loss of selectivity in 1:1 and 95:5 apatite: dolomite mineral mixtures are presented. Loss of selectivity in mixed mineral systems is attributed to depletion of oleate ions available for adsorption by bulk precipitation with calcium and magnesium ions dissolved from dolomite. Flotation after two-stage conditioning was found to be a potential technique to separate dolomite from apatite. This method involves conditioning at pH 10 followed by reconditioning at a lower pH. The results indicate that selective flotation of dolomite, a minor mineral in south Florida phosphate deposits, could be obtained by reconditioning at pH below 4.5. Higher selectivity was observed for mixed minerals as compared to that of single minerals.

Jan 1, 1986

By Bryan J. Travis, Thomas L. Cook

INTRODUCTION Our growing concern for adequate and secure sources of energy and minerals has stimulated vigorous exploration for new sources, research toward a better understanding of geological processes, and development of new extraction technologies. The need for control, or at least prediction, of subsurface fluid flow is important for many of these technologies for example: primary, secondary and tertiary recovery of oil; ground water and waste management; in-situ fossil energy extraction (oil shale, coal, tar sands); and solution mining of uranium, copper and other minerals. These technologies, especially the last two, are characterized by highly complex systems. A partial list of the physical processes occurring would include flow in porous/fractured media, multi-phase and multi-component flow with heat transport, chemically active fluids and soils, tracers, diffusion and dispersion, fracturing and dissolution. A great deal of understanding of how these processes behave and interact can be obtained from models. MODELS Theoretical models are valuable because they: 1) provide a frame of reference for interpreting results of laboratory and field experiments; 2) once validated by experiments, allow a variety of geometries, injection/production strategies, etc., to be examined (at relatively low cost) for efficiency and stability; 3) can provide guidance to the design of experiments and field operations. Most models are based on the fundamental principles of mass, momentum and energy balance. But from this starting point, many paths can be taken. For example, there is the theory of Payatakes (1973) which concentrates on the microscale dynamics. In this approach, the rock or soil matrix is represented by a complex of characteristic channels (such as periodically constricted smooth tubes). Detail of flow within the characteristic channel is calculated very accurately. A difficulty with this model is that description of a representative channel can require several parameters which may not be easily measured. Also, it is not clear how the channels can be combined practically to model a large scale flow. Another type of model is the "global" one described by Bear (1972). Here, the continuum equations for conservation of mass, momentum and energy are averaged over a distribution of pore channels, resulting in a set of conservation equations in which the small scale structure of the medium is replaced by quantities such as porosity, permeability, dispersion coefficients and tortuosity. This approach allows computation of large scale flows. However, additional constitutive equations are needed which relate averaged quantities such as permeability to observables such as local saturation, particle size distributions, and others. An important difference between models is the way they handle the momentum equation. Payatakes' model solves the full equation. In others, it is replaced by a simpler relation such as Darcy's law (valid for slow flow rates) or by Forchheimer's equation which extends Darcy's law to higher flow rates. These simple relations can nevertheless match a great deal of experimental data (Dullien 1975). The permeability term which appears in Darcy's law and in Forchheimer's expression has been related to other quantities such as porosity and particle surface area. The Kozeny-Carmen equation is a well-known example, valid for some ranges of porosity and particle sizes and for some materials. Several other semi-theoretical, semi-empirical formulations have been devised, none of which are entirely satisfactory. One goal of researchers has been the ability to predict permeability of a porous material from basic measurable quantities such as grain size distributions without recourse to adjustable parameters. This effort has proceeded from consideration of distributions of idealized, non-intersecting channels, to intersecting channels, to consideration of both distributed pore radii and pore neck radii. This last approach has been used successfully to predict permeabilities (ranging over several orders of magnitude) in sandstones (Dullien 1975). Additionally, studies on explicit networks of channels (e.g., Fatt 1956) and percolation theory (e.g., Larson et. al. 1981) have been used to examine interconnectivity effects in porous media with the hope of eventually being able to predict permeability accurately. To be of more than theoretical interest, a model must be compared s controlled laboratory conditions where boundary and initial conditions and relevant material properties can be accurately determined. Also, extraneous forces can be eliminated so that the interactions between processes of interest can be clearly seen and flow models can be vigorously tested. In contrast to the well-defined environment and

Jan 1, 1982

By Robert I. Jaffee, Walter L. Finlay

IN the broad survey of the nonferrous' metallic elements contained in this book, the reader may well be impressed by the wide range of property combinations offered by the many metals and alloys the metallurgist has prepared since before Kubla Khan. The diversity is great and the overlap is considerable. It is particularly surprising, then, to find the latest structural metal new- comer designated by such extravagant terms as "Cinderella Metal," "Wonder Metal," "Miracle Metal," "The Metal of Tomorrow," "Dream Metal or Nightmare?" and "The Middleweight Champion of the Structural Metals." Of these and others, the most appropriate designation for the metal involved, titanium, appears to be that of The Middleweight Champion. Its intermediate density of 4.5 and elastic modulus of 16 million is a unique combination between the lower density and modulus of magnesium and aluminum and the higher density and modulus of copper, nickel, and iron. It is light, strong, ductile, and corrosion resistant. A chemical neighbor in group IV of the Periodic Table, zirconium, is similar to titanium in many respects but is appreciably denser, 6.5 instead of 4.5, less stiff and relatively much less abundant. On the other hand, the resistance of zirconium to acids and alkalies is better than that of titanium. Also, compensating for its higher density, lower stiffness, and somewhat lower strength level compared with titanium, zirconium has much better permeability to slow neutrons and is much more suitable as a material of construction for nuclear reactors.

Jan 1, 1953

By Frank Firmstone

In 1871, two furnaces at the Glendon Iron Works, which had been blown out on account of the "coal strike," were altered from the open-top plan with side flues for collecting the gas, to closed tops with cup and cone. In one furnace the suppression of the side flues permitted a considerable alteration in the profile, but in the other (No. 5) no change in this respect was made; the side flues were simply bricked up and new ones cut through the sides close to the top. This furnace was in blast over four years, and we can, therefore, form a pretty good idea of the effect of the alterations on the furnace process. The principal dimensions are; Height 72'; greatest diameter, 18'; diameter at tuyeres, 8'; diameter of top, 10'; diameter at stock line (point at which the top of the materials is kept), 11'; cubic contents, 11,900 cubic feet. The table below shows the average results for periods of twentysix weeks each. 1st, of the open-topped furnace; 2d, of the furnace with the first charger used, which was an ordinary cup and cone (diameter of cone 5' 2") 3d, with the charger used ever since, a " double " cone 7' 5" diameter outside, having a central opening 3' in diameter. The diagram (Plate 11) shows the daily variations, in the grade of the irons for the same periods.*

By AIME AIME

A JOINT meeting of the Canadian Institute of Mining and Metallurgy and the American Institute of Mining and Metallurgical Engineers was held at Spokane, Wash., and Cranbrook and Kimberley, B. C., on Oct. 13 to 16, 1926, with a total attendance at one or another or all of the meetings of about 300 members, ladies and guests. At the opening meeting, on Oct. 13, in the Davenport Hotel, Spokane, about 175 were present. The morning was occupied with addresses of welcome by M. H. Sullivan for the Columbia Section, who called on Mayor Charles A. Fleming, President John F. Davies for the Chamber of Commerce, and E. R. Hannibal, president of the Associated Engineers, each of whom heartily welcomed the visitors. Philip N. Moore, former president, and special representative of President Samuel A. Taylor, replied for the A.I.M.E., and Lewis Stockett, president, and Charles A. Banks, chairman, British Columbia Division, Canadian Institute of Mining and Metallurgy, and Henry M. Parks for the visiting A.I.M.E. sections, made appropriate responses on behalf of those they represented. The members and ladies had luncheon with the Associated Engineers. Philip N. Moore addressed the assembly on "The Opportunity of the Engineer"; an excerpt from his address appears on another page. At the afternoon meeting, with Lewis Stockett in the chair, Frank M. Smith was asked to make a brief statement of the proceedings of the Silver Producers Association in Denver. Supplementing his talk by placing a well-prepared statement on "Silver and the Plan of the Royal Commission on Indian Currency and Finance" in the hands of those present, he narrated what had been undertaken by the Silver Producers Association and what they hoped to accomplish.

Jan 1, 1926

By R. F. Hehemann, S. T. Zegler

The w phase in zirconium alloys containing more than G pct Nb can form in a difjUsionless manner during quenching or with composition change during aging at temperatures below 550°C. The latter treatment establishes a metastable equilibrium between an w phase containing 5 pct Nb and a ß phase containing 45 pct Nb. The superconducting transition temperat~ire of quenched Z?-10 pct Nb and Zr-15 pct Nb alloys is increased by aging at 375°C and both alloys exhibit the same Tc after prolonged aging. The superconducting transition both in the quenched and in the aged alloys is relatively sharp (occurring ovev a temperature range of <0.5°K), and is interpreted in terms of the microstructure that characterizes the ß-w) mixture and proximity effects postulated for thin-film superconductors. At elevated temperatures alloys of the transition elements from groups 4 to 6 in the periodic table exhibit wide ranges of mutual solubility in the bcc structure. Except for compositions that are high in a group 4 element? the bcc structure can be retained at room temperature by quenching and several systematic studies of the influence of composition on superconductivity in bcc alloys have been reported.&apos;&apos;2 The high-temperature bcc form (ß) of the group 4 elements—titanium, zirconium, hafnium—is not retained upon quenching but instead transforms marten-sitically to the hcp structure (a). The Ms temperature can be lowered by alloying the group 4 metals with a solute from a higher group and with a critical amount of solute the martensitic transformation can be suppressed. The 3 phase, however, is not retained without modification. Rather, a metastable phase, w (in particular in titanium- and zirconium-base alloys), occurs over a fairly wide range of compositions above that required for suppression of the martensitic transformation.3,4 As in the formation of a, the transformation of ß to w occurs in a diffusionless manner during quenching and the temperature for its initiation (ws) is lowered by increasing solute content. The ws temperature can be well below room temperature and reversibility of the transformation allows w that forms on cooling to low temperatures to disappear again when the sample is returned to room temperature.5 In Zr-Nb alloys the w phase can also be formed during aging at temperatures below 550°c.5 In this treatment, a metastable equilibrium is established between a niobium-rich ß phase and a zirconium-rich w phase. The present study of Zr-Nb alloys was undertaken to examine the influence of microstructure: as controlled by composition and heat treatment, on the superconducting transition temperature, Tc. MATERIALS AND PROCEDURE The alloys were prepared from zirconium crystal bar that was spectrochemically pure except for 30 ppm of Al, 40 ppm of Cu, 100 ppm of Fe, and 1 ppm of each B and Pb. The niobium used was 99.5+ pct pure containing according to the suppliers&apos; (Stauffer Chemical Co.) analysis a maximum of 50 ppmO, 60 ppm of N, 30 ppm of C, 5 ppm of H, 200 ppm of Ta, 50 ppm of Mo, and 15 ppm each of Fe, Co, and Ni. The alloys were prepared in the form of buttons weighing approximately 4 g by arc melting on a water-cooled copper hearth in an inert-gas atmosphere. All alloys were heat-treated in the ß-phase region for 3 days at 1000°C and water-quenched. For heat treatment, the specimens, 0.5 cm in diam by 1.0 cm long, were wrapped in zirconium foil and sealed in an inert-gas atmosphere inside quartz capsules. Quenching was done by breaking the capsules under water. Subsequent aging treatments of Zr-10 pct Nb and Zr-15 pct Nb alloys were done by placing the specimens in a lead bath at 375°C and quenching in chilled brine. The phases present in the quenched and aged alloys were identified by optical and X-ray metallography. X-ray powder patterns were taken at room temperature with a 114.6-mm-diam Debye-Scherrer camera and CuK-a radiation. Superconducting transition temperatures were determined from magnetic-permeability measurements6 in a 10 oe field. The superconducting transition temperature was determined from a plot of galvanometric deflection as a function of temperature by extrapolation of the linear portion of the curve to zero deflection. In Figs. 1 and 3 the arrows indicate the temperature range of the transitions. RESULTS AND DISCUSSION Superconductivity in Quenched Alloys. In Fig. 1 Tc for alloys quenched from 1000°C is plotted against nominal composition. Indicated also in Fig. 1 are results of metallographic studies. Alloys containing less than 5 pct Nb transform martensitically to a during quenching from 1000°C and Fig. 1 demonstrates that Tc increases significantly as the niobium concentration in a is increased. On the basis of the Bardeen-Cooper-Schreiffer theory of superconductivity7 it seems most likely that this increase in Tc results from an increase in the density of electronic states as zirconium is alloyed with niobium. This increased density of states has been revealed clearly in low-temperature specific-heat measurements.8 The martensitic transformation to a is suppressed when the alloy content exceeds 5 pct Nb. In the range from approximately 6 to 30 pct Nb, quenched alloys consist of a mixture of B and w phases and the amount

Jan 1, 1967

By A. G. H. Anderson, A. W. Kingsbury

Silicon bronzes containing ken are used to a considerable extent in industry, under the trade name of P.M.G. alloys. Various classes of wrought alloys fall in the composition range 1.5 to 3.5 per cent silicon, and 0.5 to 2.5 per cent iron. Castings may contain as much as 6 per cent silicon and 3 per cent iron at present. The constitutional diagrams of these alloys are thus of considerable practical importance. Copper-silicon-binary alloys have been thoroughly investigated by a number of workers, the latest reports being those of C. S. Smith1 and of A. G. H. Andersen.2 Although much work has been done on iron-copper alloys,3 recorded investigations on the copper-rich copper-iron binary constitutional diagram are not numerous. Tammann and Oelsen4 etermined the solubility limits of iron in copper by means of magnetic measurements, and found that the solubility of iron in copper amounts to a fraction of one per cent at 400°C., increasing slowly to one per cent at 800°C. From 800°C., the solubility increases rapidly and attains 4 per cent at iioo°C. Hanson and Ford,5 using electrical resistivity measurements and the microscope, determined a somewhat different solubility limit. of earlier X-ray works on the copper-iron system, very little has been published. The work by Bradley and Goldschmidt6 on copper-iron-aluminum alloys includes some information on the copper-iron binary. These investigators conclude that substitution of iron in the copper lattice decreases the spacings, which is contrary to the evidence of the present work. Hanson and West? have investigated the ternary alloys of copper with iron and silicon. Although their diagrams are valuable contributions to the understanding of these alloys, they did not recognize the kappa phase,l,2,7,8 and their diagrams do not everywhere conform to the phase rule. The present work contains a check by means of X-rays of the solid solubility limit of iron in copper, and an X-ray investigation of the ternary-phase diagram, which, owing to present conditions, it became necessary to curtail considerably. Preparation of Samples Castings weighing about 75 grams were melted under vacuum. The charges were made up of ingot iron, copper cathodes from Laurel Hill, and refined silicon supplied by the Electrometallurgical Co. Alundum crucibles were generally used. The exceptions were alloys 77 and 78, which were melted in graphite crucibles. The ingots were annealed at 800°C. for one week, then samples were cut for chemical analysis. Longitudinal sections of the binary alloy ingots were hammered into plates 1/8 in. thick. Wherever possible, these plates were homogenized at temperatures ensuring

Jan 1, 1943

By A. G. H. Anderson, A. W. Kingsbury

Silicon bronzes containing ken are used to a considerable extent in industry, under the trade name of P.M.G. alloys. Various classes of wrought alloys fall in the composition range 1.5 to 3.5 per cent silicon, and 0.5 to 2.5 per cent iron. Castings may contain as much as 6 per cent silicon and 3 per cent iron at present. The constitutional diagrams of these alloys are thus of considerable practical importance. Copper-silicon-binary alloys have been thoroughly investigated by a number of workers, the latest reports being those of C. S. Smith1 and of A. G. H. Andersen.2 Although much work has been done on iron-copper alloys,3 recorded investigations on the copper-rich copper-iron binary constitutional diagram are not numerous. Tammann and Oelsen4 etermined the solubility limits of iron in copper by means of magnetic measurements, and found that the solubility of iron in copper amounts to a fraction of one per cent at 400°C., increasing slowly to one per cent at 800°C. From 800°C., the solubility increases rapidly and attains 4 per cent at iioo°C. Hanson and Ford,5 using electrical resistivity measurements and the microscope, determined a somewhat different solubility limit. of earlier X-ray works on the copper-iron system, very little has been published. The work by Bradley and Goldschmidt6 on copper-iron-aluminum alloys includes some information on the copper-iron binary. These investigators conclude that substitution of iron in the copper lattice decreases the spacings, which is contrary to the evidence of the present work. Hanson and West? have investigated the ternary alloys of copper with iron and silicon. Although their diagrams are valuable contributions to the understanding of these alloys, they did not recognize the kappa phase,l,2,7,8 and their diagrams do not everywhere conform to the phase rule. The present work contains a check by means of X-rays of the solid solubility limit of iron in copper, and an X-ray investigation of the ternary-phase diagram, which, owing to present conditions, it became necessary to curtail considerably. Preparation of Samples Castings weighing about 75 grams were melted under vacuum. The charges were made up of ingot iron, copper cathodes from Laurel Hill, and refined silicon supplied by the Electrometallurgical Co. Alundum crucibles were generally used. The exceptions were alloys 77 and 78, which were melted in graphite crucibles. The ingots were annealed at 800°C. for one week, then samples were cut for chemical analysis. Longitudinal sections of the binary alloy ingots were hammered into plates 1/8 in. thick. Wherever possible, these plates were homogenized at temperatures ensuring

Jan 1, 1943

By R. W. Raymond

FOUR portraits have recently been hung in the rooms of the Institute, in recognition of four illustrious men with whom we, as mining engineers and metallurgists, may claim fellowship. LUTHER. Martin Luther is often spoken of as a miner&apos;s son; but it is less generally known that John Luther, his father, was, in a small way, a metallurgist as well as a miner, and that Martin Luther himself, in his youth, worked in a forge or bloomary established by his father at Mansfeld, Saxony. Since this is the only manual occupation on his part of which we have any record, it is fair to assume that the great scholar and reformer derived from his work in this department the practical familiarity with the conditions of human labor so abundantly evinced in the homely illustrations which accompany even his serious arguments, and in the witty apothegms of his famous "table-talk." At the same time, I must confess that 1 have not been able to find in any of the works of Luther distinct allusions to mining or metallurgy. KÖRNER. Theodor Körner, a student at the Mining Academy of Freiberg, Saxony, threw himself into the German War of Freedom in the first decade of the 19th Century. He was a poet of no mean rank ; and his " Song of the Sword " is one of the great lyrics of literature. This poem was written but a few days before he died in battle. In many respects, Körner may be compared with our American hero Theodore Winthrop, who similarly met a glorious fate, and left behind him prophetic indications of genius, of which his premature death prevented the complete fulfillment. I am informed by a member of the Institute that Körner&apos;s admirable collection of minerals is still preserved at Dresden.

Nov 1, 1908

By T. F. Witherbee

IN the sections, Figures 1, 2, and 3, are shown three crucibles that have been applied to substantially the same furnace, all the conditions having been the same except a variation of one foot of bosh, and a slight variation in the angle of the same. The bosh of No. 3 was originally the same as No. 2, the additional foot in diameter being the result of three months&apos; cutting. Beginning with No. 1, which was 5 feet 6 inches diameter, with tuyeres 5 feet 4 inches high, and cinder-tap four feet from bottom, great trouble was found in holding iron a proper length of time, four hours being the outside limit when working well, and two hours or less if working badly. "Break-outs" through the iron

Jan 1, 1880

By T. F. Witherbee

In the sections, Figures 1, 2, and 3, are shown three crucibles that have been applied to substantially the same furnace, all the conditions having been the same except a variation of one foot of bosh, and a slight variation in the angle of the same. The bosh of No. 3 was originally the same as No. 2, the additional foot in diameter being the result of three months&apos; cutting. Beginning with No. 1, which mas 5 feet 6 inches diameter, with tuyeres 5 feet 4 inches high, and cinder-tap four feet from bottom, great trouble was found in holding iron a proper length of time, four hours being the outside limit when working well, and two hours or less if working badly. "Break-outs" through the iron

Jan 1, 1880

By T. Egleston

The importance of condensing the gases which escape from furnaces so as to save both the fine particles of ore carried off mechanically and those which are volatilized, has for a long time occupied the serious attention of metallurgists in all parts of the world. It was my good fortune during the last summer to visit the lead and silver works at Ems, near Coblentz on the Rhine, and through the politeness of Mr. Freudenberg, general director of the works, to study in detail their methods of condensation, and to receive from him the important results which have been obtained through a series of experiments lasting over a number of years. I have thought, that these results would be of great interest to the members of the Institute and to other metallurgists in the United States, and I have, therefore, with the assistance of Mr. Freudenberg, prepared a careful, detailed description of the construction of the flues, as well as an account of the various experiments which have been made with them, and the conclusions arrived at as the result of these experiments. It may be said, in general, that the reason why so little attention has been paid in the metallurgical works of the United States to the collection of flue-dust, is that we are not generally aware of the large amount of material carried off by the gases. This is owing partly to the fact that little or no attention is paid to the subject, and also to the fact that the assays, which are almost invariably made in the dry way, show a result so much below the real contents

Jan 1, 1883

By Paul A. Farrar, Louis P. Stone, Harold Margolin

The Ti-Mo-0 system was investigated in the region 0 to 45 wt pet Mo and 0 to 10 wt pet 0, from 600° to 1400°C. Solidus data are also presented. Isothermal sections at 700°, 900°, 1100°, and 1300°C, and vertical sections at 1 and 28 wt pet Mo, and 1 and 10 wt pet 0 are included. STUDY of the Ti-Mo-0 system has been carried out as part of a general study of titanium phase diagrams. The binary Ti-Mo system has been investigated in whole or in part by several investigators.1-8 It was found that molybdenum and ß-tita-nium form a complete series of solid solutions and that the ß/a + ß transus is depressed to below 600°C at approximately 30 pet Mo.* The Ti-O system has been investigated partially or fully in the range 0 to 30 pet 0 by several investigators." Extensive solubility of oxygen occurs in the field. While a is

Jan 1, 1957

By F. W. Robinson

THE temperature coefficient of electrical resistance of pure metals is high and therefore the resistance increases rapidly with rising temperature. In 1871, Siemens suggested the use of this property as an accurate means of temperature determination. Owing to practical difficulties, particularly the contamination of the metal and consequent permanent change in its resistance and its resistance-temperature relation, this method fell into disrepute as a practical standard until revived later by Callendar and Griffiths, and subsequently by Holborn and Wien, all of whom showed that the earlier difficulties were not inherent in the method but incident to the mode of protection of the resistance coils. Following .the work of these investigators, the problem of temperature measurement by this means has been the subject of careful study and has now assumed an importance second only in practical adoption to the thermo-electric method. It is generally recognized, both here and in Europe, that the standard temperature scale should be the thermodynamic as it permits the evaluation of high temperatures on the basis of the radiation laws of Stefan and Bolzmann, of Rayleigh, and of Wien and Planck, on a scale consistent with that obtained by means of the gas thermometer at low temperatures. Lord Kelvin showed that only. a very small correction, amounting to about +0.7° at 1000° C.-almost within the limits of experimental errors-is necessary to adjust the constant-volume nitrogen thermometer to the ideal thermodynamic scale.

Jan 9, 1919

Jan 1, 1947

Jan 1, 1947