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By Joe N. Magee

As part of the important program of promoting conservation and efficient utilization of petroleum, Bureau of Mines engineers are making studies of secondary oil-recovery projects throughout the United states and publishing reports setting forth the pertinent facts so that others may profit by the experience gained. This report presents the results of a study by engineers of the Bureau of Mines, stationed at Franklin, Pa., of secondary oil recovery in a part of the Cabin Creek field, Kanawha and Boone Counties, W. Va., where natural gas is injected into the reservoir to stimulate oil production. Most oil produced in the Appalachian region at present is obtained from stripper fields in which almost all natural energy has been dissipated. Secondary-recovery methods are used extensively in many oil-producing areas of New York, Pennsylvania, West Virginia, Ohio, and Kentucky for recovering oil not produced by primary-production methods. The part of the Cabin Creek field reported in this study is shown in figure 1 and has been designated by the operator as project 4. In 1944 the developed area of the entire field was approximately 4,200 acres, and the area of project 4 was about 600 acres. In the developed area of the project the oil reservoir is in the Berea sandstone and occurs at 2,914 to 3,410 feet.

Jan 1, 1952

By A Allen, J. A. Garcia

The large increase in the wages of mine workers makes it imperative that all factors tending to limit production per miner be eliminated, if possible. The trolley and storage-battery locomotive, mining machine, hoisting engine, mining system, etc., have increased the possible output per man. But this output is still limited by the capacity of the hoisting engine and cable and by the size of the mine car. The superiority of skip hoisting in metal mining is shown by its almost universal adoption. By varying the size of skip and the rope speed, any desired tonnage can be secured and, since frequently only one kind of material is handled and breakage is unimportant, the loading of the skips can be easily and cheaply effected from bins into which the cars are dumped. The cars may then be designed to fit the conditions in the mine instead of being a compromise between hoisting and mining conditions, very likely suiting neither. In coal mines, the usual practice has been to hoist the car to the surface, either on platform or self-dumping cages. Of late years the number of skip-hoisting plants in coal mines has been rapidly increasing, but there is more or less inertia to overcome in establishing so radical a change in practice; also the earlier skip operations were not uniformly successful. As a result, it became evident that metal-mining practice would require radical modification before skip hoisting could be successfully used in coal mining. Objections to Skip Hoisting Breakage Except where coal is used for coking, or for other purposes whcre breakage is unimportant, breakage of the coal is vitally important all the way from the face to the railroad car. The average selling price is seriously reduced when the percentage of screenings is increased. Following metal-mining practice exactly, the coal would be dumped into a deep pocket, cut off into a skip load by a measuring hopper or other means, dumped into a deep, narrow skip, and dropped into a bin at the top, all of which would contribute to excessive breakage.

Jan 1, 1922

By George H. Ashley

Character The bituminous coals of Pennsylvania range from low volatile to high volatile, but are all low moisture coals The coals are of three types caking of coking, noncaking or splint, and cannel The percentage of volatile matter in all kinds changes from low at the east to high at the west This change is thought to be due to the pies sure and folding to which the coals along with the other rocks have been subjected In the Broad Top field, and in Somerset, Cambric, Clearfield, Centre, and other counties to the northeast, most coals contain from 3 to 5 times as much fixed carbon as volatile matter, the fixed carbon ranging from 67 to 75 per cent, and the volatile mattes from 16 to 24 per cent These coals are classed as lovol coals In the line of counties just west of those listed the coals are of the medium volatile class (midvols) This includes the famous Connellsville coking coal Still farther west, covering most of Washing ton and Westmoreland counties, and the counties to the north of them are high volatile coals of gas coals (hivols) This is discussed in Part I on the geology of the coals of Pennsylvania, where is given in isocaib map Cannel coals ale found in many par is of the bituminous coal field of Pennsylvania, but in particular in Beaver Butler, Armstrong, Indiana, and Clear field counties The cannels of Beaver and Butler. counties are typical high volatile cannels, many of which have been used in times past for oil distillation The cannels of Armstrong and Indiana counties are medium volatile cannels, and while main taming the physical character of cannels, have no more volatile neat ten than the coals around them The cannels of Clearfield County tie low volatile Splint coals of noncakmg coals are not abundant in Pennsylvania. The Sharon coal, formerly mined in Mercer County, was a noncaking or splint or block coal, and was formerly used in the raw state in non smelting Uses STEAM COAL Practically all of the coals of Pennsylvania are steam coals, though many coals in the Commonwealth, because of high ash, are not good steam coals The coal of the Pittsburgh district has long been famous

Jan 1, 1928

By J. S. Becker

Technology developed and first implemented in the United Kingdom enables very low grade aluminum scraps containing oils, organics, plastics and ferrous metals to be directly charged, without pretreatment, into a unique melting furnace. The system has been in full scale production for four years. The oxy-fuel-based furnace design incorporates internal afterburning in the furnace's hot zone, producing excellent thermal efficiency and very low emissions. The furnace is inherently low in NOx. This paper will provide both theoretical background and extensive operating results for this new melting concept. Applications describing both purpose built new furnaces and retrofits of existing reverberatory furnaces will be presented. Extensive operating emissions data will be presented.

Jan 1, 1997

By Albert Sauveur

(Winces-Barre Meeting, June, 1911.) THE instrument about to be described meets so perfectly the special needs of the metal microscopist that there seems to be little doubt but its merits must be readily appreciated by those who have had any experience in the microscopical examination of metals. The Microscope-Stand.-The microscope-stand proper, Fig. 1, consists of a microscope-tube, provided with both coarse and fine adjustments of the best construction, and with a draw-tube, rigidly mounted on a bar supported at both ends on substantial and firm cast-iron legs. The height between the table and the under side of the supporting bar is 5 in. and the distance between the supporting legs 12 inches. This arrangement' affords free space below the objective for the examination of large specimens of metals, such as full rail-sections, without detracting in the least from the value of the instrument when applied to the examination of the usual small specimen, as explained later. Many metal microscopists frequently have to examine bulky specimens, and this is altogether impossible with the ordinary microscopes as well as with the special metallurgical microscopes which have been designed and described from time to time. Recourse must be had to all sorts of makeshifts for the proper support of large specimens, or, more often, the microscopist gives up the attempt altogether, or else resigns himself to the cutting of the bulky samples into small pieces to -be laboriously polished and separately examined. It is believed that an instrument permitting the examination of large as well as of small specimens with equal ease and accu-

Dec 1, 1911

By George Watkin Evans

The need for mechanization in coal mining wherever it can be successfully introduced is evident when we take into account the fact that during recent years the coal-mine employee's wages have increased and his hours have been shortened. Coal is no longer King, and a brief study of statistics covering the production of coal, petroleum and natural gas and the development of water power will convince anyone that coal has had very powerful competitors during the past 10 years. Petroleum production in the United States between 1918 and 1936 increased from 100 per cent to 309 per cent. Water power increased from 100 per cent in 1918 to 270 per cent in 1936. Bituminous coal slipped from 100 per cent in 1918 to 75 per cent in 1936. The anthracite industry slipped from 100 per cent in 1918 to 50 per cent in 1932, but climbed to 55 per cent in 1936. In 1918, the State of Washington produced a little over four million tons of coal and the production of California oil, at that time, was a little less than one hundred million barrels per year. By 1929 the production of California oil had increased to a little over 292,000,000 bbl. or nearly 300 per cent as compared with 1918. By 1934 the production of coal in the state of Washington had dropped to about 1 1/3 millions of tons per year. Our neighbors in British Columbia had their coal production reduced from a little over 2 1/2 million tons in 1920 to less than 1 1/3 million in 1933. The North western Improvement Co., a subsidiary of the Northern Pacific Railroad Co., owns coal properties in various parts of Washington and Montana. The Northern Pacific is one of the very few railroads using any considerable quantity of coal in its operations. Practically all of the American railroads in the Pacific Northwest, except the Northern Pacific, are using cheap California fuel oil or electricity. This problem, of course, is not a new one in coal mining, and all of the progressive coal companies in the country have tried to meet competition from an overproduction of petroleum and an overproduction of natural gas as well as enlarged developments of hydroelectric plants.

Jan 1, 1938

By George Watkin Evans

The need for mechanization in coal mining wherever it can be successfully introduced is evident when we take into account the fact that during recent years the coal-mine employee's wages have increased and his hours have been shortened. Coal is no longer King, and a brief study of statistics covering the production of coal, petroleum and natural gas and the development of water power will convince anyone that coal has had very powerful competitors during the past 10 years. Petroleum production in the United States between 1918 and 1936 increased from 100 per cent to 309 per cent. Water power increased from 100 per cent in 1918 to 270 per cent in 1936. Bituminous coal slipped from 100 per cent in 1918 to 75 per cent in 1936. The anthracite industry slipped from 100 per cent in 1918 to 50 per cent in 1932, but climbed to 55 per cent in 1936. In 1918, the State of Washington produced a little over four million tons of coal and the production of California oil, at that time, was a little less than one hundred million barrels per year. By 1929 the production of California oil had increased to a little over 292,000,000 bbl. or nearly 300 per cent as compared with 1918. By 1934 the production of coal in the state of Washington had dropped to about 1 1/3 millions of tons per year. Our neighbors in British Columbia had their coal production reduced from a little over 2 1/2 million tons in 1920 to less than 1 1/3 million in 1933. The North western Improvement Co., a subsidiary of the Northern Pacific Railroad Co., owns coal properties in various parts of Washington and Montana. The Northern Pacific is one of the very few railroads using any considerable quantity of coal in its operations. Practically all of the American railroads in the Pacific Northwest, except the Northern Pacific, are using cheap California fuel oil or electricity. This problem, of course, is not a new one in coal mining, and all of the progressive coal companies in the country have tried to meet competition from an overproduction of petroleum and an overproduction of natural gas as well as enlarged developments of hydroelectric plants.

Jan 1, 1938

By J. Sliwinski, J. Oliveira

"The application of geometallurgy and corresponding sample selection can take on several formats within industry. Current practice can range from a strictly geostatistical approach to one in which geological and metallurgical parameters are used in combination to create a representative sample selection strategy. The stage of a project and the level of information available at the time of sampling influences the methodology used to create a representative sample.A geometallurgical study of Carpathian Gold’s Rovina Valley Project in Romania is used to demonstrate a sample selection strategy that integrates geological, mineralogical and metallurgical data to maximize the relevance of the geometallurgical unit definitions. This approach, practiced by Xstrata Process Support for its’ clients, ensures that the results of the metallurgical program can be interpreted in the context of these units.INTRODUCTIONGeometallurgy is a cross disciplinary approach in which metallurgical performance of an ore is linked to intrinsic geological and mineralogical characteristics. The objective of a geometallurgical study is to characterize the range of metallurgical performance of an orebody. This allows the geoscientist or metallurgist to create a robust flowsheet able to treat the full range in variability and to develop production strategies to maximize financial performance. The standard approach is to individually sample and test a series of ore types or geometallurgical units. Several different approaches are used in industry to define what constitutes geometallurgical units and how to sample them.One current methodology is the use of multivariate statistics. Geochemical data along with available geological data are used to define multiple variability domains (Williams, 2004; Walters, 2009). There are risks associated with this methodology since the extent of the data set itself may not support a purely statistical approach at the time that metallurgical units need to be defined. The assay suite collected by exploration programs is often limited to pay metals while metallurgical performance is often affected by ore gangue components. Furthermore, in many cases metallurgical scoping and pre-feasibility studies take place prior to the availability of extensive geochemical data sets. Purely statistical methods can produce multiple populations which require extensive sampling, testing and validation prior to consolidation into a reasonable number of composites for metallurgical testing. Methodologies are therefore required that allow representative sampling and testing of consolidated geometallurgical composites to occur at various phases throughout the development of a mining project."

Jan 1, 2013

By A Jafari, N Khalili, M Vahab, P Broumand

This paper presents the implementation of the eXtended Finite Element Method (XFEM) in the general-purpose commercial software package COMSOL Multiphysics for multi-field thermo-hydromechanical problems in discontinuous porous media. To this end, an exclusive enrichment strategy is proposed in compliance with the COMSOL modelling structure. COMSOL modules and physics interfaces are adopted to take account of the relevant physical processes involved in thermo-hydromechanical coupling analysis, namely: the mechanical deformation, fluid flow in porous media and heat transfer. The model preprocessing, level-set-updates, coupling of the relevant physics and postprocessing procedures are performed adopting a coherent utilisation of the COMSOL’s built-in features along with the COMSOL’s LiveLink for MATLAB functions. The capabilities and performance of the proposed approach are investigated by examining several multi-field thermo-hydro-mechanical simulations with reference to the block caving process in mines.

Nov 29, 2022

By N. Sahin, K. Baris, A. Ozarslan

This paper aims to assess the current and future role of coal in energy strategy of Turkey and evaluates the compatibility of the policies to the EU energy policy and strategy. The Turkish government set targets to utilize more coal reserves of the country in next decades. However, the country is also in the process of becoming an EU Member State, hence, it is expected that the energy policies have to comply with the EU. Moreover, Turkey ratified Kyoto Protocol, thus the country should limit greenhouse gas emissions. Clean Coal, Carbon Capture and Storage (CCS) technologies are expected to become an important instrument for the mid-term reduction of CO2 emissions from coal-fired power plants. An alternative technique to the conventional CCS methods is CO2 sequestration by mineral carbonation. Turkey has significant resources of magnesium silicate minerals (olivine, serpentine) deposits which can be utilised in CO2 sequestration by mineral carbonation method.

Jan 1, 2011

By Diana Diaz, Rakshith Shetty, Vitaly Proschenko, Mike Mooney

Cohesive clay soil poses a significant risk to earth pressure balance tunnel boring machines (EPBM) due to unstable face pressure, clogging potential, high cutterhead torque, poor muck flow, low advance rate, etc. This paper details the performance measures desired when EPBM tunneling in clay soil, and the scientifically-supported conditioning methods to transform in-situ clay to a muck with such characteristics, giving particular attention to ground conditions. The paper then examines TBM data from multiple clay soil projects in the context of these performance measures to demonstrate the influence of cohesive soil conditioning on EPBM performance.

Jun 13, 2023

By Jesus Pascual, Benjamin Cebrian

A new Convention Center is going to be built in the millenary city of Toledo, right in the old city limits. The workings will need to excavate some 80.000 cubic meters of granite, which has, a trench-like structure already blasted for the construction (60 years ago) of a parking lot and a shopping area. Surrounding this trench, some few feet away, there are structures and buildings from the 16th century and remainings from previous times that need to be preserved from any damage caused by blasting. Because of this, a vibration analysis was designed according to the special characteristics of this work. Structures to monitor were located at several levels. It considered three different directions of study in order to evaluate the impact of vibrations of the structures located at three different heights of the granite trench. On top, the historical convent of Santa Fe, with some remaining from the 8th century (Muslim domination of the Iberian Peninsula), on the bottom, the Justice Hall of Toledo with 16th century walls, and, in the middle, a wall and a tower from times of the king Phillip II (16th century, the time of the Spanish Empire).

Jan 1, 2004

By G. W. Jones

The Bureau of Mines has advocated the use of stenches as warning agents in metal mines and in gas-distribution systems since 1920 A considerable amount of research has been conducted on ethyl mercaptan and other compounds to determine their effectiveness when used for this purpose.4/5/6/7/8/9/10/11/12/13/ Miners are warned of danger by a stench injected, in measured quantity, into a compressed-air line through which it is rapidly carried to the working faces, where it escapes from the compressed-air equipment and imparts a characteristic odor to the air. This method is not applicable to mines where only a limited number of com-pressed-air lines are used, as for example, many coal mines; the ventilation currents available in these mines may be too slow for warning purposes.14/

Jan 1, 1954

By A. Bauer, P. Katsabanis, M. Baker

The principal results from a previous paper presented at the Mine Accident Prevention Association of Ontario in 1987 (1) are summarized here. It is concluded that the selection of explosives in mines experiencing sulphide ignitions is important and that aluminized explosives should be avoided because of their high explosion temperatures and their detonation products. The duration of the blast is also critical and secondary blasts should not occur simultaneously with nearby priroa:ty blasts.

May 11, 1988

By T Seifert, P Krolop, K Niiranen, S Gilbricht

The Per Geijer iron oxide apatite deposits (IOA) display significant potential mineral resources for Luossavaara-Kiirunavaara AB (publ), known as LKAB. LKAB continuously mines magnetite/hematite ores in northern Sweden for almost 130 years. The Per Geijer deposits reveal a high phosphorus content and vary from magnetite-dominated to hematite-dominated ores, respectively. Furthermore, they show a large variation in texture, mineral composition, and relation to wall rocks. The high phosphorus concentration of these ores results from highly elevated content of apatite as gangue mineral. Reliable, robust, and qualitative characterisation of the mineralisation is required as these ores inherit complex mineralogical and textural features. For this purpose, comminution tests at laboratory scale in combination with scanning electron microscopy-mineral liberation analysis (SEMMLA) were carried out. Based on this work, significant information on the modal mineralogy and degree of liberation of minerals of economic interest (eg magnetite, hematite, and apatite) were obtained. Results show that there is a difference in the degree of liberation of magnetite and hematite between ore types. This seems to be dependent both on the size fractions and the dominance of each iron oxide in the individual ore type. The amount of gangue minerals seems to have no significant impact on the degree of liberation after comminution. Apatite is generally best liberated in ore types associated with silicates, regardless of magnetite or hematite dominance. Based on the results of this study it can be inferred that a high degree of liberation of the minerals of economic interest can be achieved. However, results need to be verified with further beneficiation steps such magnetic separation, apatite flotation and possibly reverse silicate flotation.

Nov 8, 2021

By William M. Kester

Finely sized Upper Freeport coals are beneficiated to reduce ash and sulfur using high-intensity magnetic separation to process both (1) raw, untreated coal as well as (2) raw coal which was pre-treated thermally with steam and air. Substantial, sulfur and ash reduction can be obtained using both approaches to magnetic beneficiation of coal fines, but evidence indicates that pre-treatment which would constitute a costly supplementary step is technically inferior to the direct beneficiation of raw, untreated coal. These bench-scale studies demonstrate that if high-intensity,; high capacity, dry, magnetic beneficiation equipment can be developed and' installed at coal burning power plants or at appropriate points in coal preparation plants substantial quantities of sulfur may be removable from coal after pulverization as a means' to reduce air pollution.

Jan 1, 1965

By A. B. Hooker

Many attempts have been made to develop methane detectors that will be safer and more accurate than the flame safety lamps used to detect methane in mines. The development has taken two general forms, namely: (1) Methane detectors, in which the evidence of methane depends entirely upon changes in the appearance of the detecting element, such as a flame or filament; (2) indicating methane detectors or those equipped with scales upon which the approximate percentage is definitely indicated. As an aid in the development of suitable detectors, the United States Bureau of Mines has assembled and published in its Schedule 8B a set of minimum requirements which tests and experience have shown desirable for methane detectors. Any manufacturer may submit his detector for inspection and tests leading to approval under this schedule.

Jan 1, 1930

By S J. Loach

Geological reconciliation is an indispensable part of BHP Billiton’s Western Australian Iron Ore (WAIO) operations. Since 2009 our reconciliations have been calculated in a single, centralised sequel-server database. This system draws data from across our operations and calculates a hierarchical sequence of reconciliation factors that span the company from the smallest grade control (GC) block to the whole of WAIO. It then presents the results using sophisticated graphical reporting tools.The initial motive for developing WAIO’s reconciliation system was to meet corporate compliance and public reporting requirements. The ability to validate our resource and reserve models by comparing their estimates of tonnes and grade with production figures remains the system’s principal function; however, as the system has matured, we have significantly developed its ability to support the improvement of various technical activities within the business. For example, the system can now calculate and report reconciliation factors for different resource classifications, short-term planning models and geometallurgical estimates.More recently, great emphasis has fallen on the system’s ability to detect and warn of possible geological issues that may pose a risk to either production schedules or product quality. We envisage a future where automated analysis of our large historical data set will enable high-risk conditions within future mine plans to be detected and highlighted.In all of these ways geological reconciliation plays an important role in contributing to this company’s financial and operational resilience.CITATION:Loach, S J, 2017. The development and future of BHP Billiton’s Western Australian iron ore geological reconciliation system, in Proceedings Iron Ore 2017, pp 415–422 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Louise Corriveau

A Targeted Geoscience Initiative transect in the eastern Grenville Province reveals an extensive VHMS-style cupriferous hydrothermal system among rhyolitic pyroclastic rocks of the Wakeham Group at La Romaine, Québec. The volcanic rocks outcrop sporadically along a < 10 km-wide by about 100 km-long belt correlated with the south-eastern extension of the Wakeham Group. This belt occurs among voluminous, magnetite-bearing, granitic gneiss. At Lake Musquaro, 1.51 Ga metarhyolitic to dacitic lapillistones and flows, locally with aluminous nodules and veins, are intruded by 1.49 Ga feldspar porphyries. This volcanic package was deposited on typical Wakeham Group arenite (< 1.52 Ga) interbedded with nodular, muscovite- and fibrolite-bearing gneiss, and minor marble hosting finely layered garnetiferous hornblendite, garnetite and magnetite-bearing coticule. The latter are interpreted as meta-exhalite and with the associated albitite (sodic alteration), aluminous veins (hydrothermal leaching) and magnetite-rich granitoids, they are key elements in the search for concealed mineral deposits in this area. At La Romaine, to the south, 1.5 Ga lapillistones outcrop structurally above metasediments and below a composite amphibolite unit of uncertain origin (lava or sills) with magnetite-rich (BIF?) units. An extensive zone of aluminous gneiss, with lapilli textures, provide evidences for severe hydrothermal leaching of the volcanic rocks prior to metamorphism. An adjacent siliceous vein-textured unit likely represent a zone of intense silicification (74 wt.% SiO2), while aluminous, hematite to magnetite-bearing veins in adjacent felsic gneiss (tuff?) preserve evidences for the sequence of alteration events. Despite granulite-facies metamorphism, the main characteristics of the amphibolite unit persist along the entire belt. This competent unit likely served as a cap rock; the garnetite, diopsidite and hornblendite it hosts provide effective guides to the sites of fluid discharge and mineralization. A number of Cu showings, modest in size, were discovered in this unit. Their systematic occurrence, in a structural-stratigraphic sense, indicates that this setting is attractive for mineral exploration despite high-grade metamorphism and deformation. Late-stage veins laden with fluorite crosscut these alteration zones, and are themselves metamorphosed, indicating that hydrothermal activity was polyphased. SHRIMP U-Pb ages obtained on detrital zircons (1 arenite) and on igneous zircons (5 volcanic rocks, 1 porphyry and 6 granitoids), pervasive arc-type geochemical signatures and presence of in situ rafts of barium-rich garnetite in the granitoids indicate that sedimentation and volcanism occurred between 1.52 and 1.49 Ga coevally with hydrothermal activity and emplacement of a sub-volcanic 1.5 Ga granitic batholith with early, 1.53 Ga tonalite intrusion. Such a geological context can sustain large-scale hydrothermal cells and development of VHMS, Cu-Fe oxides or SEDEX deposits.

May 1, 2003

By R. D. Pehlke, J. V. Gluck, R. L. Louvet

A study has been made of the effect of small additions of bismuth on the activity of zinc in dilute solution in molten tin. Free-energy interactions have previously been determined between zinc and various third elements where the solvents were molten bismuth or molten lead.&apos;-4 In both of these solvents, the activity of zinc exhibits a strong positive deviation from ideal behavior (at 550°C y° for zinc in lead is 11.4 and for zinc in bismuth is 3.0). The present work, using tin as the solvent, is an extension to a case where the positive deviation is considerably diminished (y°Zn at 550°C is 1.63). Several previous investigators have studied the Zn-Sn binary system; however, little data is available in the range below 0.1 mole fraction zinc.5= Previous high-temperature galvanic cell studies in the Sn-Zn-Bi ternary system included the determination by Gluck and Pehlke of interactions in the bismuth-rich corner1 and separate investigations of the central region by Oleari and Fioriani6 and by Ptak and Moser.7 Yokokowa et al.8 conducted Knudsen effusion studies in the central region; however, their experiments at 625°K were conducted somewhat below the present experimental temperature range. Their results indicated an increase in zinc activity with the addition of bismuth. The present series of experiments was conducted in galvanic cells represented as follows: Zn Zn++ in LiCI-KC1 eutectic Zn + Bi in Sn (pure reference (fused salt electrolyte) (molten alloy) standard) The experimental apparatus. a multi-electrode system employing alumina crucibles and contained in a Vycor tube under a helium atmosphere, has been described previously, as have been the experimental procedures, precautions, and the methods of data reduction.1-4,- The experimental measurements were made over the range from 450° to 650°C. Between thirty and forty measurements were made in each run. The linearity of the electromotive force vs temperature relations was verified by linear regression techniques. The correlation coefficients exceeded 0.99. The experimental results summarized in Table I include the interpolated electromotive force at 550°C and the temperature dependence of electromotive force. Only results from stable and consistent cells containing more than 0.025 mole fraction zinc are reported. Attempts to run cells at 0.01 or 0.02 mole fraction zinc were not satisfactory. This is attributed to the closeness of the free energies of formation of the chlorides of tin and zinc. Calculations employing Wagner and Werner&apos;s criteria for displacement reactions10 indicated that reduction of the zinc content to 0.01 mole fraction places the cell near the borderline concentration for a 1 pct error in measured potential. The compositions shown in Table I are the actual weighed-in amounts. Previous experience has indicated that compositional changes during the running of a stable cell are negligible.&apos; Over the range of compositions studied for the binary alloys, the activity coefficient of zinc was essentially constant indicating that Henry&apos;s law is followed to 0.05 mole fraction zinc. The temperature, OK, de-

Jan 1, 1969