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By R. L. Wiegel

The National Science Foundation, Erie Mining Co., and University of Minnesota Mineral Resources Research Center jointly sponsored a project to demonstrate the use of a small computer in the control of cyclone overflow size on one line in the Erie Mining Co. concentrator. The Erie circuit, similar to most taconite circuits, uses magnetic separators to reject tailings following each stage of grinding, resulting in additional variations in the demands made on the grinding circuit because of weight rejection fluctuation. Mathematical models were developed for rod milling, ball milling, hydrocycloning, fine screening, and five stages of magnetic separation. These models were used in concert to simulate the operation of Erie's circuit from rod milling through finisher magnetic separation.

Jan 1, 1980

By George W. Healy, Ko Yamaguchi

In typical calorimetry the energy given off by a material under study is transferred to a water bath, whose temperature is sensed by a thermometer; for correct measurement the water bath must attain a uniform temperature to which the thermometer must respond. This introduces two sources of error, non-uniformity of the heat sink and a time lag until its temperature is registered. These errors may become important where a rapid process such as solidification of metals and alloys is being studied by means of Oelsen'sl quantitative thermal analysis. To overcome this difficulty, a calorimeter sink was conceived in which the water bath is replaced by a copper coil, which serves simultaneously as heat

Jan 1, 1967

By Bain, Edgar C.

THE results are presented of an investigation to discover the fundamental atomic conditions existing in Corson's high-copper alloys hardenable by means of silicide solution and reprecipitation. The study attracted the writer because it offered a very convenient example of the general type of hardenable alloys exemplified by duralumin. Sykes' iron-tungsten and iron-molybdenum alloys and the hardenable lead-antimony. SUMMARY OF RESULTS AND CONCLUSIONS In brief, the investigation shows that very perfect crystallinity exists in the solid solutions prepared at high temperature to contain as much dissolved silicide as possible. The lattice parameter of copper is altered very little by the amount of cobalt, nickel or chromium, and silicon dissolved. The hardening by drawing at a temperature to initiate precipitation of excess silicon and metal produces a remarkable change in the atomistics of the solid solution. The old perfection of crystallinity in the solid solution is destroyed and the new atomic spacings are of variable magnitude even in one grain, and a condition in a measure resembling that found in martensite is observed. Were no particles whatever precipitated by the drawing action, still ample causes for hardness would be in evidence in the solid solution alone. The lack of plane continuity in the crystal grains would oppose slip in a very effective manner. Complete annealing restores the crystalline perfection in large measure. In these alloys even the most sensitive methods failed to reveal the characteristic pattern of the silicide precipitated by the anneal, but this was largely to be expected as the amount is relatively small.

Jan 1, 1927

By M. Cohen, R. J. Teitel

There is considerable interest in beryllium because of its low density (1.84 g per cu cm), high modulus of elasticity (40 X 106 psi), high melting point (1280°C), and special nuclear characteristics. Moreover, it has fair resistance to corrosion and oxidation. However, the purest beryllium known to the authors is relatively brittle at room temperature, and cannot be fabricated readily. The search for improved properties leads naturally to investigations of beryllium alloys and the phase relationships upon which they are based. The present paper is concerned with the alloys of beryllium and iron, primarily from the standpoint of the equilibrium diagram. Iron was selected (1) because of its all-round importance in metallurgy, and (2) because the beryllium-iron system is known to be quite complex. The most recent diagram in the literature is that of Gaev and Sokolov,' and covers only the iron-rich end up to 16 wt pct beryllium. Beryllium markedly restricts the austenitic field, closing the gamma loop at about 0.4 wt pct (3 at. pct). On the other hand, beryllium is soluble in a-ferrite up to a maximum of 7.5 wt pct (34 at. pct) at the eutectic temperature of 1160"C. The eutectic composition lies at 10 wt pct beryllium (42 at. pct) and corresponds to a mixture of or and FeBez (called j3 in the present paper). The solid solubility of beryllium in the a phase decreases with decreasing temperature, and makes precipitation-hardening possible. These findings substantiate the earlier work of Oester-held,2 Wever and Mueller3 and Laissus.4 In addition to the FeBe2 (ß) mentioned above, Misch6 has reported on FeBes, and indicated evidence for another compound containing still more beryllium. A preliminary diagram by Gordon,5 not hitherto published, is given in Fig 1. Besides the phases previously named, there are shown a solid solution of extended range (e), a compound of limited solubility (t), and a high temperature phase (7). Beryllium is designated as 8. The t field contains the compound composition FeBea, and the f phase undoubtedly corresponds to the beryllium-rich compound found by Misch.6 The region around the { phase was proposed by R. J. Teitel based on Gordon's data. The details of the diagram are self-explanatory. It was the unusual complexity of this system that prompted the authors to undertake the present studies. By the same token, more emphasis was placed on the beryllium-rich than the iron-rich end of the diagram. Exprimental Details RAW MATERIALS The beryllium employed in this investigation was one of the purest grades available. Its chemical analysis after vacuum melting is given in Table 1. The metal assayed 99.4 wt pct beryllium. Vacuum melted electrolytic iron of purity shown in Table 1 was the source of iron.

Jan 1, 1950

By H. P. Stuwe

It is investigated whether a model of sphere packing permits the computation of the lattice parameters and their variation with concentration in various a phases; it does, except in phases containing silicon. Several observations indicate that a particular role is played by the "E-atoms" in the lattice. THE phase is formed by many alloys of the transition elements.'-' Its structure has been described by Bergman and Shoemaker,5,8 Dickins, Douglas, and Taylor,7 and Kasper, Decker, and elanger.' There are five kinds of crystallographically equivalent positions for the 30 atoms in the unit cell which have been designated by these authors I, 11, 111, IV, and V or, in the same sequence, A, B, C,D, and E, as shown in Fig, 1. For the purposes of the present paper two elements of the lattice will be discussed separately: The lattice planes perpendicular to the c-axis which are made up by the atoms A, B, C, and D and which determine the a-parameter; and the close-packed "vertical rows" of E-atoms which determine the c-parameter. asper,9 and Frank and kasper10 described the a phase and other complex structures as sphere packings. In these papers particular attention is paid to the coordination polyhedra. Lattice positions with an equal number of nearest neighbors are considered equivalent regardless of their crystallo-graphic description. This seems to work very well for the explanation of ordering phenomena in the a phase as far as information on this is available." If the description of the phase as a sphere packing is valid it should be possible to draw two further conclusions: 1) It should be possible to calculate the lattice parameters from the atomic radii of the components, and 2) It should be possible to predict the variation of the lattice parameters with concentration within one phase field. Both points are discussed in this paper. PROCEDURE Measurements of lattice constants were done with a symmetrical back-reflection X-ray camera. With Cr-radiation, about a dozen a1 lines could be observed with most samples. From the (550/710)- and 720-lines the a-value was computed. With this value the c-parameter was calculated from the (333)- and (413)-lines. Finally, the position of all the other lines was computed from the lattice parameters thus obtained. In this way the validity of the indexing could be checked and, at the same time, this proce- dure gave an estimate of the accuracy of the lattice parameters. A correction was made for film shrinkage. The atomic radii used in the computations are the Goldschmidt radii for coordination number 12. Actually, some of the atoms have a coordination number of 14 or 15, but the error thereby introduced is small. * For the computation of lattice constants from the atomic radii an "average atomic radius" of all components was used, i.e., complete disorder was assumed. Although this seems to be true for some systems like OS-Cr,4 it is not true in others.11,13,14 The ordering model, however, which has been suggested by Kasper on the basis of extensive research lets both kinds of atoms contribute to both the ''vertical rows" and the lattice planes perpendicular to them, so that even with ordering of this kind the assumption of complete disorder cannot introduce a very serious error in calculating lattice parameters. RESULTS Bergman and shoemaker6 gave a table of the interatomic distances in the Fe-Cr phase. If we disre-

Jan 1, 1960

By Harlowe Hardinge

THE sound made by ball, pebble and rod mills has long been used by the operator as the "telltale " of their operation. The nature of this sound depends upon local conditions and the type of mill used. By experience an operator can tell whether the mill is running properly or not. Some operators are able to detect the difference in sound much better than others and get better results running the same mill under the same conditions. The automatic operation of a mill using sound as the fundamental means for maintaining control presents many problems. The satisfactory solution of these problems requires, for given operating conditions, a greater average output, with improved product for subsequent processing, than can be obtained by manual control. RELATION OF SOUND TO USEFUL GRINDING ENERGY Experience has taught us that there is a difference in character as well as in intensity of sound between a mill grinding wet and one grinding dry, in open or closed circuit, to obtain a coarse or fine product, on the same material, to say nothing of the effect with a variety of different materials. Broadly speaking, a wet-grinding mill operates best at a lower sound level than the same mill grinding dry, with other conditions the same. Several reasons for this variation in sound intensity under these conditions can be advanced, but the important point is that there is a difference, based upon practical results. Since these reasons may be more or less involved, and may be subject to much discussion, only one will be considered here. It is apparent that two balls hitting together or a ball striking the lining, if there is no intervening material, will produce the maximum sound. If a complete cushion of material is placed between the balls or ball and liner, so that the energy is dissipated without doing useful work, the balls will be unable to create enough pressure or force to fracture the particles, and the sound will be at a minimum. At some point in between-that is, where there is sufficient material between the balls or ball and liner so that the ball will fracture the particles without mashing them unduly-the sound

Jan 1, 1939

By C. B. Gillson, Henry Fay

For several years past, investigations on the chemistry of tellurium have been carried on in the laboratory of this institution. The methods of preparation of pure telluriumf and the estimation of tellurium‡ have been studied, and an attempt to determine the atomic weight of tellurium is now in progress. All these problems had been investigated, however, along purely theoretical lines; and it was thought desirable to study the more practical application of the metal, which can now be had in considerable quantities as a waste product in the refining of copper-ores. In its physical and chemical properties tellurium is very similar to antimony, and it was thought

Jan 1, 1902

By C. H. Li, R. J. Stokes, S. H. Bendel, J. A. Sartell, T. L. Johnston

The mechanism of the oxidation of high-purity copper has been studied at temperatures from 500° to 981°C employing gravimetric, high-temperature microscopic and inert marker techniques. An investigation of the adhesion of copper oxides was also made. The oxidation of copper is found to be parabolic at all temperatures. It is concluded that the controlling mechanism is the outward diffusion of CU+ ions through the Cu2O layer, but the mechanism of diffusion is modified by the state of compressive stress in the oxide layer at the oxidation temperature. At temperatures below the transition from elastic to plastic behavior of Cu2O the growth stresses reach a value sufficiently high to cause CuO whiskers to be extruded. The extrusion of whiskers results in the injection of a large number of vacancies into the CuO. The Cu20 layer grows by the advance of the CuzO/CuO interface into vacancy-rich CuO. Since there is an adequate supply of non -thermally created vacancies, the activation energy for oxidation is that required to move the Cu+ ion through the appropriate saddle point to a neighboring vacancy, which has been determined to be 20,000 cal per mole. At temperatures at which the Cu20 can deform plastically the stresses are never high enough to cause whiskers to form. thus vacancies must be supplied by themal activation and as a result the activation energy increases to 40.000 cal per mole. ALTHOUGH extensive studies of the oxidation kinetics of pure copper have been made in the past. the mechanism has received relatively little attention. As a result, certain features of the kinetic data have not been satisfactorily explained' For example, several workers1,2 have reported that the activation energy for oxidation in the range from 500° to 700° C was about 20,000 cal per mole whereas that above

Jan 1, 1960

By H. H. Uhlig

In our study of the mechanism of and the prevention of corrosion in stainless steels, it was considered of fundamental importance to obtain knowledge of the surface structure of such alloys. If corrosion resistance is due to a self-healing oxide layer, which like a paint film protects the underlying metal, it would be obviously relevant were the effort made to make the film less permeable and more adherent; for example, the surface might be expected to respond to an anodizing process, which is found successful in increasing the film thickness and corrosion resistance of aluminum. However, if passivity and corrosion resistance of stainless steels are due to another cause, the attack of the problem would follow another path. One of the most effective techniques for studying passivity and corrosion tendency is the measurement of the electrochemical potential. Not only can one determine by potential measurements whether a metal is active or passive, but also one can determine the degree of passivity and rate of transformation of passivity with time. Chemical media that build up or destroy passivity when in contact with the steel can also be classified by potential measurements. Something can be learned, too, of the effect of alloy additions such as molybdenum to 18-8, known to decrease corrosion of the alloy in chloride solutions. A study of alloys in previous investigations has sometimes included data on the electrochemical potentials. Tammann and Sotterl measured the electrochenlical potentials of alloys of iron-molybdenum and iron-chromium and reperted the critical concentration of molybdenum or chromium at which passivity initiates. Strauss2 made similar measurements for the iron-chromium system. The electrochemical potential3 has also been used to indicate carbide precipitated 18-8. In 18-8, heat-treated to precipitate carbide, active metal exists at the region of the grain boundaries, contrasted with passive metal within the grains, the active metal accounting for a resultant active potential. Several

Jan 1, 1940

By K. C. Gilbart, Edgar Stansfield

One of the most striking features of the coal series passing from peat through brown coal, lignite, etc., up to anthracite is the gradual reduction of moisture content with the increased coalification of the original plant material. Thus drained peat from a bog may contain 90 per cent water, brown coal contain 50 per cent, lignite 30 per cent, while a bituminous coal may contain only 1 per cent moisture. Moisture, therefore, is one of the important factors to be considered in coal classification, especially with the lower rank coals. With bituminous and higher rank coals the moisture content is less satisfactory for classification; it may even pass a minimum value and then increase with increasing rank to anthracite and superanthracite. Coal in an undisturbed seam contains moisture which is an integral part of the coal, but it may also be wet with free, underground water percolating through the seam. Only the former must be considered in evaluating the moisture content of the coal for classification purposes; this will be called the "true moisture" of the coal. When the seam is mined and sampled the sample taken may show the true moisture; on the contrary, it may contain in addition free mine water or, especially in dry, well ventilated mines, it may contain less than the true moisture. Coal contains unstable organic compounds which may decompose, with the production of moisture, when the coal is exposed to air at ordinary temperatures, or is heated with or without exposure to air. The potential moisture of a coal therefore is higher than its actual moisture. The lower the rank of the coal, the greater its instability, as a rule, and the greater the care necessary to avoid oxidation or decomposition in any investigation of moisture content. The majority of coal workers have preferred, on account of the difficulty in evaluating the true moisture of a coal, and for other reasons, to classify coals by analyses calculated to the dry-coal basis. A number of workers familiar with lower rank coals have recently insisted that the classification of such coals can be satisfactory only if analyses on the moist-coal basis are employed. The moisture-holding capacity of coal is therefore intimately connected with coal classification, and in this paper a procedure is outlined for determining the true moisture of a coal,

Jan 1, 1932

By H. H. Uhlig

In our study of the mechanism of and the prevention of corrosion in stainless steels, it was considered of fundamental importance to obtain knowledge of the surface structure of such alloys. If corrosion resistance is due to a self-healing oxide layer, which like a paint film protects the underlying metal, it would be obviously relevant were the effort made to make the film less permeable and more adherent; for example, the surface might be expected to respond to an anodizing process, which is found successful in increasing the film thickness and corrosion resistance of aluminum. However, if passivity and corrosion resistance of stainless steels are due to another cause, the attack of the problem would follow another path. One of the most effective techniques for studying passivity and corrosion tendency is the measurement of the electrochemical potential. Not only can one determine by potential measurements whether a metal is active or passive, but also one can determine the degree of passivity and rate of transformation of passivity with time. Chemical media that build up or destroy passivity when in contact with the steel can also be classified by potential measurements. Something can be learned, too, of the effect of alloy additions such as molybdenum to 18-8, known to decrease corrosion of the alloy in chloride solutions. A study of alloys in previous investigations has sometimes included data on the electrochemical potentials. Tammann and Sotterl measured the electrochenlical potentials of alloys of iron-molybdenum and iron-chromium and reperted the critical concentration of molybdenum or chromium at which passivity initiates. Strauss2 made similar measurements for the iron-chromium system. The electrochemical potential3 has also been used to indicate carbide precipitated 18-8. In 18-8, heat-treated to precipitate carbide, active metal exists at the region of the grain boundaries, contrasted with passive metal within the grains, the active metal accounting for a resultant active potential. Several

Jan 1, 1940

By R. E. Delavault, H. V. Warren

In normal soils there are usually 10 to 50 parts of copper in every million parts of .soil. Only 0.2 to .5 pct of this copper can be found by any simple cold chemical attack. Now, with rubeanic mid reagent paper, a prospector or field geologist can detect as little us 4 ppm of readily available copper ill soil. This degree, of sensiticity is enough to determine the presence. of copper anamalous an as and, ecentually, to discouer copper mineralization. Circumstances determine whether it is better to make analyses in the field or in a permanent laboratory. The rubeanic acid test described in this article has been designed primarily for field use: it is simple and virtually foolproof, and it requires a minimum of field kit." It is sensitive, easily de- • Ed. Note: Persons Interested in purchasing kits suitable for rubeanic acid prospecting can obtain information by writing Eldrico Geophysical Sales Ltd., 633 Hornby Street. Vancouver 1, B.C. The University of British Columbia does not produce these kits for sale and has no financial interest in their production tecting 4 ppm of readily extractable copper in a soil. This is by no means a quantitative test, but it is accurate enough to provide a valuable indicator of copper anomalous areas for both prospectors and field geologists. The easiest method for detecting metal deposits that do not produce visible float or stains is to make a simple chemical test for the metal in overlying soil, or in the silt of a stream that may have picked up metal farther upstream. In Brief: Testing for copper may be done easily by shaking a soil sample with strong acetic solution in a small test tube and pouring the mud into a small filter, the tip of which rests upon a strip of reagent paper impregnated with rubeanic acid (di-thio-oxamide). When copper is present—and only when it is—a blue spot develops. The more copper, the darker the spot. If the copper content is merely the small amount present everywhere, there is a pale blue or hardly visible spot; if it is abnormally high, the spot will be dark. There are, of course, intermediate cases where the experienced geochemist cannot tell offhand whether a medium-strength spot represents rich agricultural soil, weak copper mineralization, or distant rich copper mineralization. Reagents and material are inexpensive; the test may be readily done on the spot with a simple kit easy to pack and handle. Anyone interested in general problems of soil sampling as applied to prospecting may refer to an article recently presented to the AIME. In exploration work it is the contrast between the metal content of anomalous and background areas that is important; absolute values become of greater interest when an anomalous area is being investigated in detail. With specific reference to copper, it has been the authors' experience that the amounts of metal extracted from anomalous and normal soils with buffer solutions of decreasing pH show better contrast if an acid reagent is used. This contrast tends to increase with increasing acidity until 3 to 4 pH is reached. Using a short cold attack on unheated soil, it has been found that further increases in acidity do not produce better results, and only increase the hazards involved in carrying strong acids. An acidity of about pH 4 is satisfactory for direct determination of copper by dithizone. But dithizone itself introduces some problems: it must be made up fresh at frequent intervals, and with some soils, notably those with much ferric iron, oxidation mag take place before all the copper has reacted with the dithizone. Rubeanic acid keeps its strength unimpaired for long periods, is unaffected by oxidation, and is practically specific for copper at pH 4. Consequently it seems an ideal reagent to use in prospecting for copper. History and Background: Rubeanic acid (systematic name: dithio-oxamide (SC-NH2) has long been known as a spot test reagent for some heavy metals with which it gives a number of compounds. Only copper and some metals of the platinum family are believed capable of providing any ru-beanate compounds under conditions of moderate

Jan 1, 1959

By Wllliam D. Davis

C OMMERCIAL production of oil in northeastern Oklahoma began in 1897 and in the next two decades this area became one of the greatest oil districts of the time. Its importance is now secondary, but thousands of wells in this area have produced uninterruptedly for more than thirty years. They are now classified as stripper wells. By means of what is known as water flooding their L. production can be considerably in- creased. This practice consists in injecting water under pressure into the sand surrounding an oil well, thus displacing the oil in the pores of the sand and forcing it into the oil well.

Jan 1, 1940

[Aalde, Kaare, ('40) New Mexico School of Mines, Socorro, N. M. Abadesco, Enrique A., ('39) Univ. of the Philippines, Manila, P. I. Abdul-Ahad, A., ('39) Montana School of Mines, Residence Hall, Butte, Mont. Abreu, Ovidio M., ('38) Univ. of Nevada, Reno, Nev. Acker, Voscoe, . ('39) Agricultural & Mech. College of Texas, College Station, Tex. Acosta S., Gonzalo, ('40) Univ. of Texas, Univ. Sta., Box 1785, Austin, Tex. Adams, Albert, ('38) New Mexico School of Mines, Socorro, N. M. Adams, Charles W.,' ('39) Michigan College of Min. & Tech., Houghton, Mich. Adams, Hugh T., Jr., ('39) Univ. of Oklahoma, Norman, Okla. Adams, Jack L., ('39) Univ. of Oklahoma, Norman Okla.]

Jan 1, 1940

By J. M. Boutwell

PAGE I. Introduction,.......541 II. General Geography,......542 III. General Geology,......544 1. Sedimentary Rocks,..... 544 2. Igneous Rocks,...... 545 3. Areal Geology,.......546 4. Structural Geology......547 IV. General Character of Ore-Deposits,...548 V. Genesis of the Disseminated Ore in Monzonite,.... 549 1. General,........549 2. Character and Occurrence,... 649 3. Genesis,....... 550 4. Superficial Alteration.....553 5. Conclusion......553 VI. Genesis of the Ore in Fissures,...553 1. Character........... 553 2 Occurrence......554 3. Deposition...... 556 4. Transporting Agent....555 6. Immediate Causes of Deposition..556 6. Superficial Alteration....564 7. Conclusionl ..... 565 VII. Genesis of the Copper-Ore in Limestone...... 566 1. Character......566 2. Occurrencel .....566 3. Deposition......567 4. Relation of Fissures.....569 5. Relation of Intrusives,...571 6. Superficial Alteration....575 7. Conclusion......578 VIII. Periods of Ore-Deposition....578 IX. Dates of Mineralization.....579 X. General Conclusions.....580 I. Introduction. The object of this paper is to present a concise statement on the genesis of the copper- and lead-deposits of the Bingham

Jan 1, 1906

By A. R. Anderson

UNTIL recently all discussions directed at justify-ing the use of mechanical-loading equipment and conveyors have referred chiefly to tons per man and cost per ton. But there is another consideration that ? will speed the adoption of mechanical loading in mines even though tons per man on present day stand-ards were not increased nor the cost per ton decreased. With restricted immigration, improved facilities for education in our mining communities, and increased opportunities for recreation, the type of man who can or will throw 20 tons of coal per day over the side of a mine car is disappearing. Whether we will it or not provision must be made to replace muscular effort by mechanical means. Fortunately, indications are that the process will be accompanied by increased output per man and lower production cost, and though the outlook may now be a bit clouded in spots, all should profit by the change. The operator should enjoy a more stable business with more assured profit, the miners should get a better livelihood with less arduous effort and under safer and pleasanter working conditions, and the consumer should gain the assurance of a supply of coal always available at reasonable prices. That sounds like the millennium in the coal business perhaps. Of course, it is not, but there is just enough of that millennium stuff in it to encourage those of us who are working with today's problems of applying loading and conveying equipment to underground opera-tions. If we discern clearly that there can be no back-sliding, and that all will share in whatever advantages accrue, we will carry on more vigorously, and may right-fully expect to have the necessary cooperation of all the elements within the industry. As nature does not seem to have followed a definite plan in the formation of coal deposits it is not likely that any one standard method or type of equipment can be evolved for mining the coal. The method of mining that maybe most advantageously employed with load-ing machines and conveyors depends on the character of the strata overlying the coal as much as anything else.

Jan 4, 1927

By Bruce A. Kennedy, Richard M. Stewart

Slope stability has now become a practical tool in the design and operation of open pits. The selection of slope angles is a critical decision that can have far-reaching effects on the accumulated cash flow and the overall profitability of a mining project. Slope failures can now be dealt with in a number of ways. Two methods - the total removal and the partial unloading of a failing zone-have been practiced for many years. However, with the refinement of monitoring techniques, open pits can now learn to live with a slide and even turn a potential loss into a gain. There are various techniques, such as presplit blasting, drainage systems, and artificial stabilization, which can be applied immediately in an existing open pit to improve the stability of the pit slopes. The technology of slope stability will play an important part in the future mining of low grade, previously marginal orebodies, which will have to be exploited if the mineral needs of the world are to be met.

Jan 1, 1971

Discussion Of the paper Of GEORGE K. BURGESS, J. J. CROWE, H. S. RAWDON, and R. G. WALTENBERG, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin NO. 93, September, 1914, pp. 2433 to 2437. ALBERT SAUVEUR, Cambridge, Mass.-The Bureau of Standards has once more rendered a public service. Manufacturers and consumers of steel rails alike should welcome the important results now laid before them by Dr. Burgess and his co-workers. Personally I welcome these results all the more that in the past, as some of the members may remember, I have never failed, when occasion arose, to call the attention of rail manufacturers to the importance of controlling the finishing temperature of their rails. The pioneer metallographic work conducted at the South Works of the Illinois Steel Co. in the early '90s clearly brought out the close relations existing between the manufacture, properties, and finishing temperature of steel rails and I think I may say without fear of being contradicted that the results of this early investigation had considerable influence in drawing the attention of manufacturers to the importance of finishing temperature and of heat treatment in general. The results now before us should be, it seems to me, of great value to rail manufacturers in their efforts to produce a better and, above all, a safer rail. It seems to be demonstrated in this paper that there is no difficulty in installing in rail mills pyrometric outfits, making it possible to record, without interfering in the mill operations, the temperature of the rails as they leave the finishing rolls, or of the ingots as they are withdrawn from the soaking pits, or at any intermediate point in the process of manufacture. The inference necessarily follows that manufacturers should see to it that such pyrometric installations are made, in order that they may actually know, instead of guessing at, the temperature of their rails;, and, for obvious reasons, rail consumers should insist upon such installations. In the rolling of heavy sections especially should care be taken to lower their finishing temperature, seeing that the present tendency is to finish them at higher temperature, whereas, owing to the slower cooling of their central portions, which makes for coarseness of grain, they should, if anything, be finished at a lower temperature than lighter rails.

Jan 4, 1915

By W. E. Forsythe

Different forms of optical pyrometers are discussed and the advantages and disadvantages of the different types for measuring high temperatures are pointed out. These advantages and disadvantages lead to the selection of the disappearing-filament type of optical pyrometer for most work. Attention is directed to the necessity for the use of a monochromatic screen with a pyrometer, which leads to a discussion of the meaning and use of the effective wave length of the screen. Methods of calibrating the optical pyrometer are outlined and it is shown that an optical pyrometer can be calibrated just as definitely as any other temperature-measuring device. Accuracy tests are included, in which it is shown that excellent results can be obtained by even untrained or slightly trained observers with this form of optical pyrometer. The various corrections that are necessary in this kind of work are indicated, including corrections for stray light, for absorption of windows, of smoke, and so forth. The troublesome problem of measuring the temperature of bodies that do not radiate like a black body is discussed and the corrections for reducing such readings to the true temperature are given for a number of different materials. Introduction The fundamental idea of temperature depends upon our temperature sense and bodies are said to be hot or cold depending upon the reaction of our hands or some other part of the body to the heat from the source investigated. For measuring the temperature some instrument must be devised, since the temperature of the source studied is apt to be so hot as to greatly injure any part of the body that comes near it, to say nothing about direct contact with it. Definition of Temperature.—The temperature scale is based upon two fixed points, the temperature of freezing water and the temperature of boiling water. This temperature interval, depending upon the scale

Jan 1, 1936

By W. E. Forsythe

Different forms of optical pyrometers are discussed and the advantages and disadvantages of the different types for measuring high temperatures are pointed out. These advantages and disadvantages lead to the selection of the disappearing-filament type of optical pyrometer for most work. Attention is directed to the necessity for the use of a monochromatic screen with a pyrometer, which leads to a discussion of the meaning and use of the effective wave length of the screen. Methods of calibrating the optical pyrometer are outlined and it is shown that an optical pyrometer can be calibrated just as definitely as any other temperature-measuring device. Accuracy tests are included, in which it is shown that excellent results can be obtained by even untrained or slightly trained observers with this form of optical pyrometer. The various corrections that are necessary in this kind of work are indicated, including corrections for stray light, for absorption of windows, of smoke, and so forth. The troublesome problem of measuring the temperature of bodies that do not radiate like a black body is discussed and the corrections for reducing such readings to the true temperature are given for a number of different materials. Introduction The fundamental idea of temperature depends upon our temperature sense and bodies are said to be hot or cold depending upon the reaction of our hands or some other part of the body to the heat from the source investigated. For measuring the temperature some instrument must be devised, since the temperature of the source studied is apt to be so hot as to greatly injure any part of the body that comes near it, to say nothing about direct contact with it. Definition of Temperature.—The temperature scale is based upon two fixed points, the temperature of freezing water and the temperature of boiling water. This temperature interval, depending upon the scale

Jan 1, 1936