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By R. W. Armstrong, D. H. Feisel

Self-diffusion in pure crystalline solids has been described through extension of the Cohen and Tum-hull volume -fluctuation model originally proposed for diffusion in simple liquids. It is shown, for a number of crystalline solids, that the self-diffusion coefficient, D, obeys the relationship where a is the lattice spacing, v the Debye frequency, Z' the lattice-volume fluctuation per atom required for a diffusion jump, and (?V/Vo) the relative increase in the lattice volume resulting from thermal expansion between O°K and the temperature under consideration. The calculated value of Z' is dependent upon the difiusion mechanism and the lattice geometry. ThE need for an increased understanding of mass-transport processes in crystalline solids has resulted in much research to determine rates of self-diffusion.' For several metals (e.g., copper, silver, and iron), the experimental values of the self-diffusion coefficient, D, have been determined over a large interval of temperature and the accuracy of D has been investigated through repeated experiments. Also, a number of empirical and theoretical diffusion studies have established a rational basis for understanding the D values for the different elements.2"6 The empirical diffusion analysis by Sherby and simnad6 supplied the main stimulus for the present study. Sherby and Simnad, reviewing the self-diffusion data for a substantial number of pure crystalline solids, suggested that sufficient data were available to establish with some certainty the apparent intrinsic material properties which influence D. Without explicit regard for any mechanism of diffusion, these investigators obtained an empirical relationship for D which correlated the self- diffusion coefficient for each element with the melting temperature, crystal structure, and valence of the particular element. Their analysis is only unsatisfactory in that the effect on D of crystal structure is not very clear and the valence to be assigned to an element is not always straightforward. The present study is an attempt, from a very different viewpoint from that of Sherby and Simnad, to establish a basis for understanding the self-diffusion coefficients for crystalline solids. This analysis was undertaken for the purpose of developing a general expression for D which would explicitly depend on the mechanism of diffusion. The main result of the study is that diffusion in crystalline solids may be described in terms of a volume-fluctuation model which was originally proposed by Cohen and Turnbull7 to describe diffusion in simple liquids. The model appears to be useful for predicting self-diffusion coefficients in crystals. The following sections describe the volume-fluctuation model for diffusion, the application of this model to crystals, and the resultant agreement with experimental data. 1) THE VOLUME-FLUCTUATION MODEL FOR DIFFUSION Cohen and Turnbull7'8 developed their model for liquid self-diffusivity for the purpose of describing certain properties of liquids, glasses, and the liquid-glass transition. A hard-sphere model for the liquid structure is used. In this model, the size of a spherical molecule or atom is fixed for all temperatures by the interatomic spacing at the absolute zero of temperature. At any temperature above O°K, the atom is viewed as being contained within a larger spherical cage defined by the interatomic spacing of the atoms at that temperature. A random distribution of varying cage sizes is assumed to exist in the liquid. An individual diffusion jump occurs when the free volume of an atom (the volume of the cage containing the atom minus the volume of the atom) is large enough for the atom to jump out of its cage. With this physical picture of diffusion in liquids, Cohen and Turnbull derive the following equation for self-diffusivity: D=Doe-yv*/vf [1] where Do is the product of three factors which are the diffusion-path geometry, the diffusion-jump distance, and the velocity of the diffusing atom, v*

Jan 1, 1964

By John Hall

THE Fremont test for measuring the energy consumed in breaking a notched bar of steel is not so well known in this country as it deserves to be. The test specimen used in this test is about 3/8 by 1/4 by about 1 1/4 in., notched with a hack saw on the lower side to cause the piece to break at a fixed point. A weight of 10 kg. falling 4 m., and provided with a knife or chisel which strikes the specimen, breaks the test piece by impact. The residual force in the falling weight after it has broken the specimen is recorded by a suitable device, and the difference between the total energy and the residual energy of the weight (in kilogrammeters) is the force consumed in breaking the specimen. An experience of several years with the Fremont testing machine has shown its great value in readily detecting brittleness not revealed by tensile testing or slow bending testing. I this paper it is proposed to discuss (1) the supersensitiveness of the test as applied to cast steel and (2) its value in revealing the effect of heat treatment under certain conditions. .

Jan 7, 1913

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. P. Blake

One of the most remarkable iron-ore districts of the world is found in Southern Utah, in Iron County, about 270 miles south of Salt Lake City, and 10 miles west of Cedar City. This region has long been known in a general way; but, being at present somewhat difficult of access, it has been rarely visited by 'any of our members. Professor Newberry has published somewhere a short description. Last year, by the invitation of J. R. Walker, Esq., of Salt Lake City, one of our associate members, I formed one of a party, including Professor G. W. Maynard and W. S. Keyes, to visit and inspect the region. A special car was placed at our disposal by the courtesy of Hon. John Sharp, Superintendent of the Utah Central Railway. From the present southern terminus of the road at Milford, a drive of 55 miles took us to Cedar City, about 10 miles east of the iron region. The ores outcrop in a low range of hills or mountains, and stand out in such bold relief from the general surface, and are so massive and jet black, that they may be seen for miles before they are reached. These outcrops extend in long lines over the hills, and mark very . clearly the course of the beds, conforming generally to the inclosing stratified formations, probably of Palaeozoic age. These rocks are somewhat obscure, but there are large outcrops of limestone without much alteration. This, in places, appears to be the adjoining rock, at others the wall-rocks are porphyry, and at others apparently a quartzite and a fine-grained felsite. The beds of iron-ore are from 10 to 100 feet and more in thick ness, and some of the outcrops extend unbroken continuously for 1000 feet and more. It consists chiefly of magnetite and hematite,

Jan 1, 1886

By Richard D. Call

Predicting the performance of a waste embankment requires an estimate of the properties of the waste and foundation materials. The performance characteristics and the associated material properties are: [ ] Methods for obtaining estimates of the material properties include: laboratory and field testing, back analysis, and indirect estimates from other material properties. The most critical technical need is the development of indirect methods for use in feasibility studies and mine planning, prior to production when actual samples of waste material are not available. Material properties are not unique, single values; they are probability distributions. There are two components to these distributions: the uncertainties in testing and the inherent variability of the material. The objectives of a material properties evaluation should be to obtain an unbiased estimate of the property distributions rather than the average or the minimum value. Whether the current trend to a probability design analysis is followed or a simple sensitivity analysis is conducted, the unbiased probability distribution is preferable to single values.

Jan 1, 1985

By J. R. Ross, J. B. Rosenbaum

Bureau of Mines research has resulted in the development of fluid- bed ion-exchange columns for recovering uranium from slime pulps. In pilot plant tests, slime slurries containing up to 6 percent solids were processed at flow rates of 10 gallons per square foot per minute with high uranium recoveries and efficient resin loadings. Uranium was effectively eluted in a laboratory fluid-bed elution column at eluate-to-resin ratios of less than 5:1 and eluate flow rates of 3 gallons per square foot per minute. Construction costs of mills using these improved ion exchange techniques are estimated to be 25 percent less than for mills using solvent extraction of clear solutions. For mills having a capacity of 2,000 to 2,500 tons of ore per day, the saving would be in the range of $2.5 million. In addition, a saving of about $0.80 per ton of ore in total operating costs is indicated.

Jan 1, 1973

Underground Transitmen.-Two transitmen with experience in shaft mines; need not be full grown engineers but entirely capable of doing accurate instrument work. Location Middle West coal mines. R-419. Draftsman.-Kentucky. $150 per month.. Extensive experience in map work and construction work, such as is found in and about coal-mining operations. Send sample f work and state whether or not married. R-606. Mine Transitman.-Kentucky. $140 per month. Considerable experience in and about coal mines; must also be a fair draftsman. Send sample of work and state whether or not married. R-607. Draftsman.-West Virginia. Experience on mine 'mapping and construction work, for position with coal and coke company. R-609. Civil Engineer.-China. Salary depends upon man. Technical education and training in general engineering and building construction. Man about 30 .years of age desired, preferably unmarried. The various engineering construction in which this firm is engaged are as follows: Investigations, inspections, reports and valuations, design and supervising of construction for industrial plants and bldgs., power plants, difficult foundations, bridges and steel structures, wharf and deck construction, river and harbor works, investigating and development

Jan 6, 1919

By Herbert Hoover

YOUR committee asks that I speak today on the relations of the engineering profession to public affairs. That takes in a lot of ground. This being a cheerful occasion, I will assume that I should exclude the engineer's function as a taxpayer. This being a nonpartisan occasion, I will assume that I should not refer to his voting emotions in 1940. Perhaps what was in the minds of your committee was the application of engineering thought to the confusions of the times. That is also a lot of ground. I fear, however, its boundaries disappear in mirages and rainbows on all sides. Now any entry of the engineer into public affairs involves his breaking into the fields of the sociologists, the economists, and the politicians. However I don't know why, seeing the difficulties these professions are having, they should not welcome a little help.

Jan 1, 1939

By J. C. Motz

Introduction The variations in crushing plant design seen during the past 30 years provide a valuable source of information and experience from which one can select the optimum arrangement for a specific requirement. The purpose of this paper is to examine some specific equipment configurations as they relate to operating efficiency, plant availability and final product size in the form of mill feed. Due to the varied ore properties, physical space limitations, size of ore body and financial resources, there is no single crushing or grinding flowsheet that is best. Since energy costs have risen dramatically during the recent past, it became obvious that significant savings are possible by selecting equipment and a circuit which offers low power requirements balanced with low wear metal and installed equipment costs. Relatively clear and measurable are the metal and maintenance costs and the ever increasing cost of energy. Metal costs in the form of crusher liners have not quite doubled in the last 20 years, while power costs have increased by a factor of four or five, depending on the region considered. Estimates made only a few years ago on the increased cost of energy are obsolete in view of the recent unstable conditions. Since power is therefore becoming the largest cost area, it behooves us to investigate potential cost saving methods in the form of lowering the KWH/Ton of crude. Crushing To reduce run-of-mine to mill feed requires reduction in a series of stages. The physical size and power requirements of a crusher capable of reducing hard rock vary depending on the application. Extended experience in most crushing plants show that a minus 19MM (3/4 in.) rod mill feed can be and is being produced in three stages of crushing. In the majority of cases, the last crushing stage is closed circuited using anywhere from 19MM (3/4 in.) to 14MM (9/16 in.) slotted openings on the sizing deck. In some copper concentrators, the mill feed is all passing 13MM (1/2 in.) using three stages of crushing and 14MM (9/16 in.) square openings on the closed circuit screens. It was felt by some that crushing to this fine size is only possible if the ore is friable and is relatively soft in comparison to the harder ores. Our results show that some of the copper ores are as hard as taconite and are crush-

Jan 1, 1982

By Ming-Kao Yen

S. E. MADDIGAN*—I think Mr. Yen should be complimented on doing a very excellent and a very comprehensive piece of work. I was particularly pleased to note the use of X rays in a somewhat less tedious technique than pole figures. In the past I think many workers have been diverted away from the use of X rays in such investigations because of the large amount of work involved in pole figures if one is dealing with a great number of specimens. The same thing, I think, applies to the determination of orientations by counting of twins which is also a very tedious procedure; as a result several papers which have otherwise been of excellent quality have depended upon etching techniques for determination of orientation. The present paper indicates that the results reported in those previous papers were correct, but I think the use of etching techniques alone is a rather shaky basis for setting up theories in the literature. W. M. BALDWIN, JR.*—This discussion will be a short note of correction and apology. In my discussion of Brick, Martin and Angier's paper I incorrectly reported the orientation of phosphorus deoxidized copper annealed at temperatures. When I learned that Mr. Yen was preparing the present paper I asked that he correct this previous error, which he most graciously consented to do. However, through my ambiguity the correction noted on p. 59 of Mr. Yen's paper is still not the proper one. For this I take full responsibility. The orientation which I observed in phosphorus deoxidized copper at high temperatures is the (112) [111] which agrees with the pole figure given in Fig 8a, on p. 65 of Mr. Yen's paper. Our observations were made on the basis of twin counts rather than X ray determinations and therefore serve as an independent confirmation of Mr. Yen's data. M. K. YEN (author's reply)—The author wishes to thank Dr. Maddigan for his comments in regard to the application of glancing technique to textures. As a matter of fact, considerable work has been done recently in connection with

Jan 1, 1950

By M. J. Pool, C. E. Lundin

THE relative partial molar enthalpies of aluminum, gallium, and indium in liquid tin have been measured at 750°K by liquid-metal solution calorimetry. The measured heat effects and the calculated relative partial molar heats of solutions at infinite dilution are listed in Table I along with the relative heat contents of the solutes calculated from the data of Kelley. All of the values are referred to 750°K even though the calorimeter temperature fluctuated by +1°K during the entire series of experiments. The effect of this small temperature variation on the experimental values should be less than the experimental error. The limits of error given in Table I represent the standard deviations of all values from the mean. In no case was the experimental deviation greater than the listed error limits. The reported error estimates only apply to the estimated precision of experimental values and not to their accuracy. Systematic errors could be present in the calorimeter which would affect the absolute values given. Moreover the heat-content data used could also be in error and this would affect the end results. The relative enthalpies used were listed in Table I so that future corrections could be made if necessary. The relative partial molar heats of solutions of aluminum in liquid tin and dilute A1-Sn liquid solutions are large and positive. The value at infinite dilution is given in Table I. In the dilute-solution region investigated the relative partial molar heat of solution was a linear function of composition. A least-squares analysis of the data gave the following expression at 750°K: Atf^ = 6195 - 12,160 A:A1(cal/g-atom) where XA1 is the mole fraction of aluminum in the alloy. This can be compared with the data of Cohen, Howlett, and ever' who obtained the expression: 1SM = 6075 - 10,750 XM at 573°K Apparently both the partial molar heat of solution at infinite dilution and the concentration dependence increase with increasing temperature. This same

Jan 1, 1964

By W. C. McClain

In the design of underground excavations, rock mechanics considerations are nearly always based on an elastic behavior of rock. Most rocks do exhibit a certain amount of elasticity, and the application of principles and concepts of elasticity to rock mechanics problems has been largely responsible for progress in the field over the past 10 or 15 years. NO doubt the theory of elasticity will remain the most useful analytical tool available for both the design of underground openings and the interpretation of phenomenological data. Dr. Cook's analysis of rock behavior based on energy considerations represents a significant new approach to mining rock mechanics problems. Although the foundations of this analysis are somewhat broader and more general than elastic analysis, the development and applications are grounded almost entirely in the theory of elasticity. It has long been known1,2 that all rocks, even granites and dense limestones, exhibit nonlinear time-dependent strain properties to a greater or lesser degree. Creep strain (that is, deformation under constant stress) in salt, potash, and trona can be several orders of magnitude greater than instantaneous elastic strain. Design of underground workings in these materials must incorporate provisions for these strains and must therefore go considerably beyond elastic analysis. Some of the principles of underground design in highly plastic materials will be discussed in this paper. Since all rocks, especially when highly fractured, exhibit a certain amount of creep-type strain, these concepts should be at least recognized in any rock mechanics problem. The discussion will be illustrated largely, but not entirely, by examples drawn from

Jan 1, 1967

By Theron Wasson

Michigan reports another record year. Its production of 18,605,000 bbl. exceeds any previous year's total and is 2,000,000 bbl. over 1937, the previous record year. Production in 1938 brings the accumulated total for the state to a little over 100,000,000 bbl. It has taken 14 years to reach this accumulative figure, which would meet the needs of our country for about one month. Twelve new oil and gas fields were opened in 1938 and 978 tests for oil and gas were completed, of which 566 were oil wells, 25 gas wells and 387 dry holes. The new oil discovered is probably about equal to the oil produced during the year. Activities in 1938 The Temple field, Clare County, was the discovery of the year. Since July, 46 wells have been completed, and although not yet outlined it appears that more than 2000 acres have been proved for production from the Monroe of Devonian age, at a depth of 3900 ft. This discovery is the result of a wildcat test along a trend northwestward from the older fields of the central basin. The Edenville pool, Midland County, ranks second among the new fields. Thirty-five producing wells have been drilled to the Dundee at 3800 feet. The surprise development was in southwestern Alichigan, Allegan and Van Buren Counties, where six new Traverse lime pools were opened with a daily production of about 8000 bbl. at the end of the year. This is the first consistent Traverse production in the state and is about 100 miles southwest of the producing areas of the central basin. These fields have had a rapid development because of the shallow depths, which range from 900 to 1500 ft. Bloomingdale, Van Buren County, had a town-lot boom, and 72 wells have been drilled there since August 1938. Small operators from many states have been attracted to this shallow territory, and the coming year will see much drilling in these and surrounding counties. The Buckeye field, Gladwin County, led the state in amount of oil produced. Its total of over 7,000,000 bbl. was far ahead of that of any other pool.

Jan 1, 1939

By Theron Wasson

Michigan reports another record year. Its production of 18,605,000 bbl. exceeds any previous year's total and is 2,000,000 bbl. over 1937, the previous record year. Production in 1938 brings the accumulated total for the state to a little over 100,000,000 bbl. It has taken 14 years to reach this accumulative figure, which would meet the needs of our country for about one month. Twelve new oil and gas fields were opened in 1938 and 978 tests for oil and gas were completed, of which 566 were oil wells, 25 gas wells and 387 dry holes. The new oil discovered is probably about equal to the oil produced during the year. Activities in 1938 The Temple field, Clare County, was the discovery of the year. Since July, 46 wells have been completed, and although not yet outlined it appears that more than 2000 acres have been proved for production from the Monroe of Devonian age, at a depth of 3900 ft. This discovery is the result of a wildcat test along a trend northwestward from the older fields of the central basin. The Edenville pool, Midland County, ranks second among the new fields. Thirty-five producing wells have been drilled to the Dundee at 3800 feet. The surprise development was in southwestern Alichigan, Allegan and Van Buren Counties, where six new Traverse lime pools were opened with a daily production of about 8000 bbl. at the end of the year. This is the first consistent Traverse production in the state and is about 100 miles southwest of the producing areas of the central basin. These fields have had a rapid development because of the shallow depths, which range from 900 to 1500 ft. Bloomingdale, Van Buren County, had a town-lot boom, and 72 wells have been drilled there since August 1938. Small operators from many states have been attracted to this shallow territory, and the coming year will see much drilling in these and surrounding counties. The Buckeye field, Gladwin County, led the state in amount of oil produced. Its total of over 7,000,000 bbl. was far ahead of that of any other pool.

Jan 1, 1939

By A. D. S. Gillies

The effectiveness of coal mine face ventilation and the ability of airflow to maintain satisfactory methane and respirable dust levels in the working face area has been studied through the use of scale modeling techniques and underground testing procedures. In particular, consideration has been given to examination of the effects of operation of a high airflow, machine mounted dust scrubber unit on face air patterns. Results obtained through a cooperative study with the Peabody Coal Co. demonstrate that new mining cycles can be considered that increase production efficiency while maintaining satisfactory ventilation conditions.

Jan 1, 1986

By S. L. Couling, D. J-P. Adenis

i2) twinning in poly crystalline magnesium does not usually occur homogeneously but is concentrated in localized regions or bands inclined at about 45 deg to the stress axis. These bands of twinning are in many ways similar to the Luders bands seen in mild steel alzd Al-Mg alloys. Within a hand the percentage of the volume twinned may approach 100 with no twinning outside the band. Bands are not produced in specimens of grain size a3 x 10-= in. or in samples deformed at temperatures 300°F. Annealing of heavily twinned regions leads to re crystallization textures markedly different from those found in the starting material. The exact preferred orientation appears to depend on the starting grain size, the amount of compres-sive strain and the manner in which it is introduced. MAGNESIUM, with its hexagonal crystal structure, deforms plastically at room temperature by a variety of deformation mechanisms, one of the most important of which is (1012) twinning. In single crystals such twinning occurs on compression parallel to the basal plane or tension perpendicular to it. In wrought polycrystalline magnesium, such as rolled sheet, the preferred orientation is such that almost all the grains have their basal planes nearly parallel to the sheet surface. Therefore, if sheet material is deformed by cold rolling or by tension in the plane of the sheet, deformation of the grains by (1012) twinning is not favored. On the other hand, twins form readily on compression parallel to the plane of the sheet as in a compression test, on the compression side of a bent sample, or at the outer rim of a drawn cup. The first part of this paper deals with the morphology of (1012) twinning in polycrystalline magnesium. Some aspects of this subject were covered by Barrett and ~aller.' Of direct bearing on the work to be reported here are the comments of Jetter' in discussion to Ref. 1. He shows that Mg + 1.5 pct Mn alloy sheet when bent about a transverse axis develops a pattern of transverse bands on the surface of compression. A longitudinal section through the sheet shows that the bands are wedge-shaped and inclined to the rolling direction. The bands were identified as "outcrops of regions in which deformation is localized as the result of the reorientation brought about by (1012) twinning". The second part of the paper treats the recrys-tallization texture of the specimens twinned by compression. Magnesium deformed and then annealed generally recrystallizes with no change in orientation.1'3'4 This statement is true provided that the amount of (1012) twinning occurring during deformation is small. In an isolated observation, Anse15 has shown that, when deformation produces much (1072) twinning, annealing causes new maxima to appear in the pole figure. The second part of the paper elaborates on this point. I) MATERIALS AND PROCEDURES All of the experimental work to be reported was done using the commercial sheet and plate alloy AZ31B (nominal composition: 3 pct Al, 1 pct Zn, 0.4 pct Mn, balance magnesium). This alloy is available commercially in two tempers, -0 (fully annealed) and -H24 (partially annealed), and specimens of both tempers were used in various experiments. The average grain. diameter (AGD) for -0 temper 0.125-in. sheet is about 0.5 x 10- in.; where material of larger grain size was desired, anneals at elevated temperature were used to grow the grains. compression tests were made on a screw-driven "hard" machine. The specimens were clamped in a

Jan 1, 1964

[Officers JOHN CHIPMAN, President W. R. HIBBARD, JR., Past President C. C. LONG, Vice President T. D. JONES, Treasurer R. W. SHEARMAN, Secretary D. C. JOHNSTON, Assistant Secretary]

Jan 1, 1961

By AIME AIME

THE twenty-second annual meeting of the Canadian Mining Institute was held at the King Edward Hotel, Toronto, on Mar. 8, 9, and 10, and was followed on the 11th by an all-day excursion to the International Nickel Refinery at Port Colborne. The meeting was very well attended and dealt with some of the most important matters, both technical and economic, that have ever come before the Canadian Institute. The question of licensing engineers is before the Canadian members as it is before our own in this country and the attitude of the mining engineers across the border is like that of the American mining engineers, opposed to the licensing of the mining. engineer, however they may feel toward the licensing of other branches of the engineering profession. It was well pointed out that such a law, had it been in existence in the last decade or two, would probably have prevented the rapid development of Canada's mines. Whereas one civil engineer can run a line of survey as well as another, perhaps, it is only a question in his case of whether he can or cannot survey. In the case of a mining engineer employed by a man with capital to invest in a development project, unless the man with the money has confidence in the judgment of his engineer the fact that he is a professional man would carry little weight in inducing a large investment toward the development of Canada's resources. It was also pointed out that although the Institute as a whole had not passed on the matter, it would probably be opposed to legislation aiming only for self-interest, but would be heartily in accord with legislation which could be shown to be for the service of the community at large.

Jan 1, 1920

By R. J. Wysor

MORE than two years ago, in making efficiency tests on our hot-blast stoves, I was surprised to discover a marked difference in temperature as indicated by a pyrometer inserted near a stove on blast, and the regular recording instrument situated near the bustle pipe. A special hole was then provided at the junction of the hot-blast main and the bustle pipe, and portable pyrometers with bare fire ends were used, both at this point and in the stove necks. I had occasion to make a number of such tests on various stoves on the same furnace, the difference in temperature as shown by the two pyrometers varying chiefly with the temperature of the blast, and the distance of the stove from the furnace. However, this difference was always great, often averaging above 100° F., for the entire period of a stove on blast. Later, experiments were made with similar results on another group of stoves. The pyrometers used were properly standardized and checked against each other before and after each test. However, there was still a slight doubt as to the accuracy of the results obtained, as subsequently explained. But I have obtained corroboration of the magnitude of heat losses from blast-furnace hot-blast mains from two independent sources. I have learned from H. A. Brassert, Superintendent of Blast Furnaces, South Works, Illinois Steel Co., that he has recently clone some experimental work similar to my own, and found temperature drops of the same order of magnitude. Also, C. R.. Lyle, of the Armstrong Cork Co., has made some interesting theoretical calculations, based oil the thermal conductivity of fire brick, for the particular conditions of several of our tests; and his theoretical interpolations, all facts being considered, check our actual observations fairly well. I understand that Mr. Lyle expects to publish the results of his investigations.

Jan 10, 1915

By P. E. Palmer, A. H. Daane, C. E. Habermann

Jan 1, 1965