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By AIME AIME

THE revised program for the San Francisco meeting, with assignment of the various papers to the several sessions is now available and is printed below : MONDAY, OCT. 7 . General Meeting, 11-12 A.M. Chairmen: Frederick W. Bradley and E. A. Hersam. Opening of the session by the Chairman of the San Francisco Section-E. A. Heraam. Address of welcome by the President of the Institute- Frederick W. Bradley. Address: The Mining problems of the West--Charles W. Merrill.

Jan 1, 1929

By AIME AIME

THE second blast furnace of the Azov steel mill was blown in on Feb. 17, says the Economic Review of the Soviet Union. This furnace, the 111th in the U. S. S. R., has a volume of 930 cubic meters, and a daily output of 775 tons of pig iron. The 1934 program at the Azov plant includes three 250-ton-open-hearth furnaces, two coke-oven batteries, a repair shop, mine and agglomeration plant at Gamysh-Burum, and two ports, one at the latter town and one at Mariupol. On Feb. 21 the sixth open-hearth furnace of the Stalinsk (Kuznetsk) mill started operations; on Feb. 12 the fourth open-hearth furnace at the Liebknecht mill at Dniepropetrovsk, produced its, first steel, 47 tons of high-grade boring steel. The fourth open-hearth furnace

Jan 1, 1934

By D. A. Dukelow

By using the U. S. Steel oxygen sensor to measure the oxygen content of the steel, deoxidation practices have been developed for silicon-killed fine-grain steel produced by the basic oxygen process. Measurements of oxygen content taken at final turndown are related to the amount of the aluminum addition to the ladle necessary to obtain the desired aluminum analysis for proper grain refinement. In comparison with heats deoxidized by the standard approach, which is based on carbon content, the heats deoxidized according to the oxygen-sensor-based schedule showed a 25 percent decrease in variability from the desired aluminum content. As more heats of a particular grade are made, it is expected that improved quality will result in decreased rejections and better analysis control. Sensor-based deoxidation schedules are also being developed for semikilled, rimmed, and capped steels.

Jan 1, 1972

By C. M. Fellman

AVAILABLE data for the first nine months of the Year indicate that accident occurrence in metal mining was well on its way to an all-time low for 1939. However, the relatively rapid pickup in mining production in the fall will be likely to boost both accident occurrence and also accident rates. Results of the National Safety Competition for 1938, the fourteenth of its kind conducted by the U. S. Bureau of Mines, were published in August, 1939. W. W. Adams, statistician of the bureau, states that "with 345 mines and quarries competing, more than in any previous year except 1931, the contest revealed low accident rates at many of the enrolled plants and, which is even more remarkable, it revealed 113 mines and quarries at which no lost- time accidents occurred during the con- test year." The National Safety Competition provides a means whereby mines and quarries may engage in active competition to stimulate their safety programs. Companies in the contest can compare their records with those of similar plants operating elsewhere and thereby determine to what extent their safety programs are successful. The Joseph A. Holmes Safety Association gave over 150 awards for safety performance in the mineral industries in 1939 and a remarkable phase of these awards was the considerable number given to individual miners who had worked fifty or more years without sustaining a lost-time accident.

Jan 1, 1940

By V. A. Phillips

Transmission-electron micrographs of electro-thinned samples of bulk-aged Cu-3.1 pet Co alloy show an aging sequence, supersaturated solid solution — coherent particles — quasi -coherent particles — noncoherent particles. Hardening is due to precipitation of coherent spherical fee coball-rich particles showing coherency strain fields, which are resolved at between 15 and 30A diameter. Loss of- full coherency did not occur until well into the overaged region, even with the assistance of deformation after aging. Different average particle diameters of 123, 92, and 149 ± 10Å were observed in samples aged to peak yield strength at 600°, 650°, and 700°C, respectively, indicating that there is no critical size for peak hardening. Noncoherent particles tended to develop (111) faces and became octahedral in shape. Dislocations tended to nucleate spherical coherent particles which eventually grew together forming large elongated particles. The surface energy of a noncoherent (low-angle) inter-phase boundary is estimated to he about 50 ergs per sq cm. A number of particle lining-up phenomena were observed. Overaging is principally attributed to increase in particle spacing, progressive loss of coherency, and increase in amount of discontinzdous precipitation. COPPER dissolves about 5.6 at. pet (5.2 wt pet) of cobalt at 1110oC1 and the solubility decreases to 0.75 at. petl (0.54 at. pet)2 at 650°C and to 0.1 at. pet or less at lower temperature.' It has been known for many years3-5 that Cu-Co alloys are capable of age hardening. Since cobalt is fee above 417°C and its atom size is only about 2 pet smaller than that of copper, precipitation of coherent particles would be expected. The equilibrium phase precipitated at 700°C and below contains about 10 pet Cu in solution which tends to stabilize the fee structure, lowering the transformation temperature to 340oc.l The alloy is known to undergo discontinuous precipitation in addition to general precipitation; while the former can be seen with an optical microscope, the latter precipitates are not visible except in the grosly overaged condition.5, 6 Extensive use has therefore been made of the ferromagnetic properties of the precipitate in order to follow the course of aging, and it has proved possible to measure the average particle size, spacing, approximate shape, and volume fraction and to determine that the particles are coherent without ever seeing a particle (see for example Refs. 2, 7, and 8). The magnetic measurements of particle size are limited to diameters below about 120Å.7 The present study was undertaken using the techniques of transmission-electron microscopy in order to check the above conclusions, to extend the previous magnetic work to larger particle sizes, and to attempt a more detailed correlation of properties and structure. A portion of this work has already been published.9-11 The present paper is concerned with the metallographic features of precipitation in relation to aging curves. Bonar and Kelly12'13 have published preliminary results of a similar study on single crystals of Cu-2 at. pet Co. EXPERIMENTAL Preparation of Alloy. A Cu-Co alloy, containing 3.12 wt pet (3.36 at. pet) Co by analysis, was prepared from 99.999 pet purity oxygen-free copper and electrolytic-grade cobalt. The alloy was melted and cast in vacuo in a high-frequency furnace using a graphite crucible and mold: Analysis showed chat 0.004 pet C was picked up during melting. The 1-1/2-lb ingot was homogenized in hydrogen for 24 hr at 1000°C. Slices were cold-rolled to 0.005 or 0.003 in. thickness, with an intermediate 650°C anneal in hydrogen at 0.080 in. thickness. Batches of six to ten strips were solution-treated in sealed-off quartz tubes in high vacuum in a vertical furnace and quenched by dropping into iced brine containing a device which snapped off the nose of the tube. Solution treatment consisted of 1 hr at 990°C or 2 hr at 965°C. The latter was employed for all mechanical-property studies, since a tendency was noted for the higher temperature to give porous material. Strips were usually aged individually in a horizontal vacuum furnace, inserting into the hot zone and withdrawing into a cold zone without breaking the vacuum. This method gave a rapid heating rate, permitting the use of short aging times. In some cases, particularly for the longer aging times at the higher temperatures, samples were sealed individually in quartz tubes in high

Jan 1, 1964

By William M. Huang, T. Carl Shelton

There are undoubtedly many factors that affect the emission of gas from coal but the permeability of coal to gas flow would seem to be fundamental. However, there is very little information on coal permeability to gas flow available in the U.S. at the present time, despite the fact that such knowledge would appear to be significant in any degasification effort. Studies made recently in the mining engineering laboratories at Virginia Polytechnic Institute have determined values of permeability on one-inch cubes of selected coals. COAL PERMEABILITY The permeability values given in this paper are based on adaptations of Darcy's Law formulated by Henry Darcy in 1856 from experiments with fluid flow in porous media.' Using air as the gaseous fiuid, they were obtained by employing similar methods as are used to determine the permeability of petroleum and gas reservoir rock specimens.

Jan 5, 1962

By A. V. Henry

THE kaolins of the southeastern United States were known to civiliza-tion as early as the latter part of the eighteenth century-and yet the GEORGIA PRODUCTION UNITED STATES PRODUCTION IMPORTS Fig. 1.-KAOLIN PRODUCTION AND IMPORTS. commercial history of Georgia kaolins may be said to begin in the year 1900. The U. S. Bureau of Mines reported for that year a production of 6885 tons of "miscellaneous" clays in Georgia. A comparison of these figures with those of 1934, when the production rose to 284,556 tons (65 per cent of the domestic production), indicates the growing economic and technologic importance of this raw material. Fig. 1 clearly shows that a part of the increase is due to a normal growth in the use of kaolinitic clays and a part is due to replacement of clays formerly imported.

Jan 1, 1937

By Ernest Lilley

WHILE American scientific literature contains much information upon geologic conditions controlling the production of oil in Rumania, copper in Chile, and other fuel and metallic resources in many foreign countries, it is singularly lacking in data about the nonmetallics outside of the United States. Thus, though the United States is the outstanding market for European high-quality refined kaolin, and for the chinaware, porcelain, and other products of the European ceramics industries, Amer-ican literature contains only the briefest references to the deposits from which the raw kaolin utilized is obtained. To the writer, to whom has come in the past year .the opportunity of visiting a number of these deposits personally, they have proved of extreme interest both com-mercially and geologically. It is the latter phase that is discussed in this paper. The older and now largely crystalline rock areas of France, Germany, ;end other parts of western Europe contain numerous pegmatite dikes of which the upper portions have been subjected to surface weathering and kaolinization in much the same way as those of the eastern portion of the United States. Like the latter, the European pegmatite kaolins have long been known for their freedom from iron and other impurities offensive to the china and porcelain manufacturer. Unfortunately, they are also, like the American deposits, individually of small size and noted for their high costs of production. Deposits of sedimentary clay similar in many respects to the high-quality sedimentary kaolins of Georgia and South Carolina are known and worked, notably in southern Germany and in the Newton Abbott district of Devon and Dorset. in England. In general, their relationship to the parent rock from which they were derived is more evident than in the United States and the individual deposits are of smaller areal extent and less regular in outline.

Jan 1, 1932

By Martti E. Maliniemi

The Svappavaara mine is located 47 km southeast of Kiruna C. The ore deposit now being worked, Leveäniemi, belongs to Luossavaara- Kiirunavaara AB (LKAB) and is the company's, and also Sweden's, third biggest mine after Kiirunavaara and Malmberget. The distance by rail to the Norwegian port of Narvik is 214 km and to Lulei on the Gulf of Bothnia 340 km (Fig. 1). The village of Svappavaara has about 800 inhabitants. The climate is arctic in character. The temperature during the months of December to February is about -20º to -35ºC, and the ground is covered by a blanket of snow for about eight months of the year. The brief, intensive summer often arrives with startling speed, bringing both sunshine and warmth. HISTORICAL BACKGROUND Mining operations took place in Svappavaara as far back as 300 years ago. During the period 1655-1684, copper ore was taken from the deposit called Gruvberget in the vicinity of the village. The total production of raw copper was probably about 1,045 tons. During the 18th and 19th centuries, several attempts were made to extract iron ore from the numerous deposits found within the district. These brave attempts, however, were foiled by the high phosphorus contents and the enormous transport difficulties. The present-day mine fields in Leveäniemi were discovered in 1897. At that time, it was difficult to determine the size and value of the deposit because of the thickness of the soil cover (3 to 15 m) and the

Jan 1, 1969

By R. W. Raymond

(Pittsburg Meeting, March,1910.) THE Giroux Consolidated Mines Co. is equipping a five-compartment shaft at Kimberly, Nev., which will serve the Alpha mice. The depth of this shaft, January, 1910, is 963 ft., and of this depth 948 ft. was opened by raising, 15 ft. of sinking was done so that the bearers, collar-set, and three shaft-sets might be installed and concreted, and with this done it was possible to erect the necessary surface-equipment for resuming shaft-timbering on the completion of the raise. The arrangement of the shaft-timbering is shown in Fig. 1. At the 1,000-ft. level of the Alpha, and 750 ft. SW. from the Alpha shaft, a 14- by 18-ft. station was cut, and a 25-h-p. air-hoist *as installed. From here the raising commenced on July 5, 1909. The raise was cut approximately 13 by 21. ft. in area, and supported by timbering with square sets, illustrated in Fig. 2, which shows the division into four compartments. The end compartments, which were used as chutes, had the center girts heavier than in the others on account of the wear from falling rock. The chute-lining was braced by inserting 8- by 8-in. stiffeners parallel to and half way between successive caps. Similarly, the lagging on the wall sides of the cage-way and the compartment for pipes and ladder was stiffened with 4- by 6-in. timbers. In the pipe-and-ladder compartment the chute-stiffeners were reinforced with 8- by 8-in, struts, and as the cage-way was partitioned off by braced lining, there was practically no chance of rock entering the ladder-way in case a chute burst into the cage-way. Over the two center compartments the last two, sets were always bulkheaded with 8- by 12-in. timbers, shown in Fig. 3, and from the lower bulkhead the cage sheave-wheel was suspended. After a round of holes had been blasted and the loose

Jun 1, 1910

THE Joint Committee appointed to consider a Code of Ethics for Engineers recommends, after delib-erate consideration, that each participating Insti-tute or Society adopt the short simple Code of Ethics following this report. The Committee further recommends that the following method of interpreting and administering the Code be adopted by each participating Institute or Society after any necessary provisions have been, made in the Constitution and By-laws of the Organization. The President of each Society or Institute shall appoint a Standing Committee on Professional. Conduct, to administer the Code of Ethics. The duties of such a Committee shall be to interpret the Code and to render opinions on any cases of ques-tionable conduct on the part of members that may be submitted to the Committee. These interpretations shall be reported to the Executive Board of the Institute or Society who may approve these interpretations, or take such other action as may seem just and necessary. The reports of the Committee on Professional Conduct, when approved by the Executive Board, shall be printed in abstract and in anonymous form in the Institute's or Society's monthly journal for the instruction and guidance of fellow members. This Committee on Professional Conduct shall be appointed in each Institute or Society by the President holding office at the time of the adoption of this Code and shall consist of five member one appointed for five years, one for four years, a third for three years, a fourth for two years and a fifth member for one year only. Thereafter, the President then holding office shall appoint one member annually to serve for five years, and shall also fill any vacancies that may occur for the unexpired term of the member who has withdrawn. These appointments shall he made from among the older members of the Institute or. Society, so that advantage may be taken of their mature experi-ence and judgment. The Committee after appointment shall elect its own chairman and secretary. The Committee shall have power to secure evidence or other information in any particular case not only from the organization's own members, but if it should seem desirable, from men in other professions. The Committee may also appoint sub-committees to consider certain cases when deemed necessary.

Jan 3, 1922

By J. Alfred Berger, O. M. Katz

The Zv-Hf-H ternary system was studied between 500° and 900°C at pressures less than 1 atm of hydrogen gas between 1 and 60 at. pct H. A new and unique microgravimentric apparatus was used. Cizanges of slope on pressure-hydrogen composition isothernis delineated phase boundaries. These boundaries separatecl the three regions, a, 0, and y—so designated to correspond to the regions of the Zr-H binary system—from the multiphased areas between them. A eutectoidal decomposition was found with the ß region phase or phases decornposing into a lamellar product on quenching to rool ter,zperatuve. Reproducible decomposition-pressure hysteresis occilrved lnainly at lower hydrogen cornpositions and at lower temperatures across multiplzase vegions between a and 0 and a and y. Tire effects of hqfniur7z on the hydriding charactevistics of zirconiurrz weYe as follows: 1) stabilization of the a and y vegions while destabilizing the 0 region; 2) a/?preciable elevation of the decomposition pressrkres in the multiphase region between the a and /3 field; 3) ~nouenzent of the eutectoid reaction to high te~nperatures; 4) reduction in the total qiiantity of hydrogen absorbed under one atmospheve of Hz p7-essure; and 5) introduction of a split deconzposilion at the eiitectoiclal poinl in pa?? of the ternavy. Assuru~ptions based on an ir-2terstitial vandonl-solulion rtioclel 0.f hydrogen in metals slzowed that the bindit~g energy between solute sites prednnzinatecl at low /i?!dvogen concentrations. However, at high hydrogen contents the entropy was the predorninatlt factor in determining the stability of the Zr-Hf-H al1o.s. This was interpreted to mean a scarcity of filrtlzer itltevslilinl solute sites caused by hydrogen-hydvogen intet-actions in the metal lattice. INTEREST in the reaction of hydrogen with metals has increased in the past few years for the following reasons: 1) the formation or use of high hydrogen potential environments in nuclear reactors; 2) the reaction of hydrogen with alloys in nuclear reactors with the accompanying deleterious effects on the mechanical and corrosion properties; 3) the theoretical implications of thermodynamic data on the theory and rules of alloy formation in the metal-hydrogen systems; 4) the use of hydrogen-containing fuels in rocket engines; 5) the need for a process of making fine metal powders of high-melting reactive metals; and 6) the beneficial impregnation of superconducting alloys with hydrogen. In nuclear pressurized-water reactors, the problem exists of limiting the hydrogen pickup of zirconium alloys which are utilized as fuel cladding, heat shields, and support members. In general, zirconium alloys have good mechanical and corrosion-resistant properties in high-temperature water. However, hydrogen is absorbed from the corrosion reaction between metal and water, greatly accelerating the formation of the corrosion product ZrOz as well as mechanically embrittling the underlying metal. In addition, recent observations1 at zirconium to hafnium welds showed that secondary elements in zirconium can have an appreciable, and somewhat unexpected, effect on hydrogen absorption. This paper lists the thermochemical data in the range 500" to 900°C for the equilibrium reaction of four high-purity Zr-Hf alloys with hydrogen. Phase boundaries and thermodynamic functions are determined while the structural data will be presented in a future paper. In general, the Zr-Hf-H system approximates the well-known, eutectoidal, Zr-H diagram2,3 with modifications introduced through the behavior of hafnium.4,5 The Hf-H system,' published while this work was in progress, provided a consistent trend with the Zr-Hf-H data. PREPARATION OF Zr-Hf ALLOYS Table I presents a complete flow chart of the preparation procedure. The zirconium and hafnium crystal bars were completely immersed in high-purity kerosene and slowly cut into thin wafers. Wafers were then cold-sheared into approximately 1-g pieces, thoroughly cleaned, weighed, and inserted into the furnace. The alloys, B-2, B-4, B-6, and B-8, were then nonconsumable arc-melted under 500 mm of purified argon. Additional purification of the argon was accomplished by melting a large titanium button each time an alloy was re-melted or a different alloy melted. Each alloy button, which weighed 25 g, was remelted four times in an approach to complete homogeneity. Material losses were less than 0.02 wt pct. Alloy buttons were alternately cold-rolled and vacuum-annealed into 10- and 20-mil sheets. Table I1 gives the composition of the four alloys used. Very little elemental segregation existed be-

Jan 1, 1965

By G. E. Mellor, R. E. Lippoth, T. B. Faddies

The Trixie mine is located in the East Tintic Mining District. Since production began in 1970 over 450 000 tonnes of ore grading 239 grams of silver, 6.9 grams of gold, and 1.2% Cu have been mined from veins in Cambrian Tintic Quartzite. Detailed geologic mapping and extensive sampling are essential for compiling the data base required for efficiently developing and mining known reserves as well as planning exploration and development work. Although the basic techniques used by the geology group at the Trixie were developed many years ago, the reduced activity in underground precious metal mining in the U.S. have made these techniques less familiar to many presently active geologists. The increased activity in precious metals search and exploration again offer cause for the application of these techniques as a prerequisite to efficient exploration, development and production.

Jan 1, 1984

By Robert D. Thomson

Listed among strategic and critical minerals for stockpiling, mica is an important raw material in electronic and electrical equipment industries. Each year large quantities are consumed in the manufacture of television and radio tubes, radar sets, generators, transformers, electric toasters, and irons. Crude mica, which comes from the mine in crystals or in rough books of various shapes and sizes, is known as run-of-mine or book mica. Structural imperfections, impurities, rough edges, and defective laminae are removed by cobbing, rifting, and trimming to produce a marketable block mica or film mica. After the rough books have been hand-cobbed to remove adhering rock, dirt, and crushed or defective mica they are rifted, or split. In the U.S. a straight-bladed knife is generally used for rifting. Products of this operation are classed broadly as untrimmed sheet mica and scrap.

May 1, 1956

By Walter L. Maxson, Fred C. Bond

There is more information contained in a screen analysis than is ordinarily recognized, and there is an increasing need for methods of making this additional information easily available. As more comprehensive studies of crushing and grinding are made, and as the possibilities of decreased expense and increased extraction through a closer control of grinding are explored, methods of interpreting screen analyses assume an importance which they have not had heretofore. The information commonly desired, which can be determined from a complete and carefully made screen analysis, includes: (1) the size distribution of the material passing the finest screen, (2) the presence of a hard grinding fraction, (3) the location of natural grain sizes, (4) the presence of different materials with markedly different grinding characteristics, (5) the presence and amount of finely divided material such as clay, which is merely unlocked in grinding, and (6) the total surface area of the ground product. It is necessary to know the fundamental law of size distribution of a homogeneous material in order to correctly resolve a screen-analysis curve, and to understand the variations and anomalies that a sample may exhibit when compared with the ideal curve. This fundamental law was developed by Gaudin,1 who showed that when the logarithm of the per cent weight retained on any screen and passing the next larger screen in the Tyler standard screen scale was plotted against the logarithm of the screen aperture the resulting curve for the finer sizes of a homogeneous crusher or grinding-mill product would be a straight line. Gross and Zimmerley2 experimentally confirmed Rittinger's law, which states that the useful work done in crushing a homogeneous material is directly proportional to the new surface area produced; and showed that in the larger screen sizes resulting from impact crushing a

Jan 1, 1935

By D. M. Urich

New plant construction for pyrolysis and agglomeration during 1969 has been relatively quiet in the North American scene. U.S. pellet capacity approximates 52 million long tons and that of Canada 25.3 million tons. The foreign scene, however, has been extremely active during 1969, and this is expected to continue for the next several years. Changes in sinter practice have not been reported, other than a few changes towards increased bed depths and the increased use of screening facilities to size the product more closely. Interest in the field of briquetting in fields other than iron ore is high with a new fluorspar briquetting plant under construction at Brownsville, Texas. Considerable research appears to be pointed towards solving the problem of reclaiming steelmill waste products (flue dust, BOF dust, mill scale) by means other than sintering.

Jan 1, 1970

By J. L. Jernegan

In a former paper laid before the Institute, entitled Lead and Silver Smelting in Chicago, I endeavored to give a description of the manner in which argentiferous lead ores from the far West were treated in that city, and also described the method employed in the desilverization of the silver-lead produced from the ores. It will perhaps be remembered, that very siliceous ores, principally from the Emma mine, Utah, containing over 40 per cent. of silicic acid, were then being treated at the works of the Chicago Silver Smelting and Refining Company in the reverberatory furnace, with the use of metallic iron, in the form of borings, as a precipitating medium for the lead ; and that the extraction of the silver from the resulting bullion was effected by the Balbach process. The Swansea Works, also the works at Brighton, just outside of this city, and those of S. P. Lunt, were at that time treating ore of a similar character by the same method. The inadequacy of the process for the ores then under treatment was, in a manner, pointed out by me in the paper above referred to. Since the time of its writing, many and important improvements have been made in the metallurgical treatment of western ores in Chicago. Most ores are now roasted previous to reduction, and the latter operation is conducted in the shaftfurnace instead of the reverberatory. Such is the fact at least at the Swansea Works, the largest in the city, and here it was where the first steps were taken in this direction. In selecting these works as the subject of this paper, I am in hopes that the description given of the varions metallurgical operations, as they are there now conducted, will serve to give an idea of the improvements introduced

By Edward Ernst, Richard Runvik

AT the U. S. Gypsum Co. mine in Oakfield, N. Y., a flat-lying vein of rock gypsum is mined by the room and pillar method. Averaging only 4 ft thick, this vein is 1200 to 6000 ft in mineable width and many miles in length. Overlying the vein throughout the mine is a 2-ft thickness of distintegrated gypseous shale and fractured limestone which parts easily, falling with little or no warning. This shale, known as ash, varies in thickness from less than an inch to more than a foot. Small veinlets of selenite cut this shaley material, which breaks around timber props. The 18-in. limestone over-lying the ash is fractured vertically into blocks of varying size and will fail if any but the shortest unsupported spans are permitted. Above these two members is a thick layer of competent limestone.

Jan 6, 1957

By N. A. Gokcen

EQUILIBRIA in the reactions between gases and liquid metals have been the subject of many interesting investigations. The experimental realization of true equilibrium, however, is questionable in certain cases due to the lack of conclusive studies in reaction rates. It -will be shown here that a systematic interpretation of rate studies with the analysis of prevailing experimental conditions leads to valuable practical information. The reactions of particular interest are: H2(g) +S(inFe) - H2S(g) [1] H2(g) +O (inFe) =H2O(g) [21 2H2(g) + SiO2(s) = 2H2O(g) + - (inFe) [3] The usual and perhaps the most convenient method of investigation may be illustrated with reaction 1. A stream of gas mixture consisting of H2 + H2S is passed over or bubbled through the liquid metal at constant temperature. The ratio of H2S/H2 in the entrant mixture is fixed in each experimental run, and, therefore, the composition of melt varies until the establishment of equilibrium. The purpose of this paper is to derive a formula expressing the minimum time required for the establishment of equilibrium and to compare the calculated values from such a formula with the available data. Equations Reaction 1 is used for the purpose of illustrating the derivation. Let E represent the equilibrium and X the nonequilibrium sulphur in weight percent at any time t in minutes. For the sake of simplicity, it is first assumed that E > X although the results are of general applicability without restriction. It has been shown by Morris and Williams' that within a difference of 1 pct S or less, i.e., E-X5 1.00, the value of K'1 = Ph2s/Ph2.S% is very nearly constant. The maximum ratio of available Ph2s/Ph2 = H,S/H,, from which sulphur can be absorbed by metal, is equal to H2S/H2 in equilibrium with E (which equals H2S/H2 in the entrant gas), minus H,S/H, in equilibrium with X. Thus: Available H2S/H2 = EK'1 - XK'1 [4] Eq. 4 expresses that sulphur can be absorbed by metal from the H2S/H2 in the entrant gas until the gas leaving the metal assumes a value of H2S/H2 which is in equilibrium with the dissolved sulphur X at that time. H,S constitutes up to approximately 1 pct of the gas mixture. Its disassociation into H2 and SL is about 1 pct at 1600°C, hence, the H2S/H2 impinging on the surface of metal is very close to that in the entrant gas. The rate of flow of hydrogen entering the reaction chamber is kept constant experi-

Jan 1, 1954

(The following list contains the names of those members of the Institute of whose connection with military service we have only recently become acquainted; it also includes the names of a few who have recently been promoted or transferred, indicated by a *. A complete list was published in the Year Book, issued as a supplement of the Bulletin for March, 1915.) ADAMS, ARTHUR K., Lieut., Co. 2, E. 0. T. S., Camp Humphreys, Va. AMIDON, CLAUDE E., 11th Training Co., Casual Camp, Camp Cody, N. M *BARBOUR, P. E., Capt., Engineer Corps, U. S. A. *BENHAM, W. M., Master Engr., Headquarters Dept., 115th Engrs. A. E. F., Care Postmaster, N. Y. BICKNELL, H. L., Pvt., Co. D, 27th Engrs., Camp Leach, D. C. *BLANDY, S. H. B., Lieut., Royal Horse Artillery, B. E. F.

Jan 10, 1918