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By Michael J. Messel

The critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. Examination of Deposits In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesium-silicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1948

By C. H. Hitchcock

A brief resiclence in Virginia hasenabled me to examine some of its crystalline strata, and a few hints, concerning their correspondence with similar rocks elsewhere, may be of service to those who are studying them. In comparing the crystalline rocks of Virginin and New England, we may first recall the similarity of their geographical position. They constitute a continuous belt, being traceable through the Highlands of New York and yew Jersey, Southeastern Pennsylvania, in the counties of Bucks, Montgomery, Philadelphia, Delaware, and Chester, and Marylund. Thus the Green Mountains of Vermont and the White Mountains of New Hampshire seen] to be topographically continuous with the Blue Ridge and Midland districts of Virginia. This tract of country has been termed the Atlantic area in distinction from the Appalachian territory, whose eastern limit is the great, Lower Silurian limestone valley extending from the St. Lawrence and Champlain valleys to Alabama. The Appalachian formations were studied by the brothers Rogers, forty years since, and found to refit, unconformably upon the western flank of the Blue Ridge, the oldest of the series adjoining the gneisses, followed westerly by the other Palseozoic members in a regular ascending order, to which numercial designations were applied—Number 1 being the Cambrian, Number 2 the Lower Silurian Iimeqtones, etc?. In Vermont the same conclusion Was presented in the State reports: the Green Mountains were said to possess the anticlinal structure, and to underlie the quartzites and limestones. Inasmuch as this Atlantic area is' topgraphically continuous from the Middle to the Northern States, and is unconformably overlaid upon the west side by the same succession of strata, the presumption ii very strong that the history of bath sections has been the same, and that the entire area is of Eozoic age. Cross sections, in both districts, illustrate the existence of gigantic overturns, causing the strata of 'the Appalachian region to dip to wards the Atlantic gneisses. To the beginner it would appearthat tile Silurian group must dip beneath the crystallines, and hence many of the geologists in the beginning of the study of the stratigraphy of this easters border of the continent believed that

Jan 1, 1882

By Theodore P. Holt

The Mines Operating Co.'s plant at Park City, Utah, was designed to treat the low-grade fillings in the old stopes of the Ontario mine. These fillings carry 6 to 14 oz. of silver, 1 to 2 lb. of copper, 0.01 to 0.015 oz. of gold, and a small percentage of lead and zinc. The treatment consists in mixing the crushed ore with coal dust and salt and then roasting in a new type of furnace by combustion of the contained fuel. The roasted ore is leached with an acid salt solution to dissolve the silver, gold, copper, and lead. At present these metals are precipitated together on scrap iron and the product sold to a refinery. The only new feature of importance in this scheme of treatment is the roasting process, which makes possible the chloridizing of ores without any loss of the valuable metals, and at a very low cost. History of the Development of the Process The roasting process- had its beginning in connection with research work at the Utah State School of Mines. N. C. Christensen, Jr., who held one of the School of Mines' fellowships, was engaged in some experimental work on blast roasting. At the same time I was doing some work on the insoluble gold in Mercur base ores. Mr. Christensen roasted some of this base gold ore in his pot furnace, and found that when he mixed a sufficiently low percentage of fuel with the ore, it did not sinter but roasted to a leachable product. We considered this a new application of blast roasting, and proceeded to test out a large number of ores in several different types of small roasters which we constructed.. This experimental work continued well into the summer of 1911. In August, 1911, the Consolidated Mercur Gold Mines Co. installed a small roaster of our design, which we proposed to operate on the counter-current principle, feeding mixed ore continuously on top, and at the same time drawing off the roasted ore from the bottom. By proper adjustment we hoped to maintain a permanent roasting zone near the center of the column, the ore moving downward as roasted. However, we

Jan 1, 1915

The following is an incomplete list of members and guests who called at Institute headquarters during the period Feb. 10, 1919, to Mar. 10, 1919. R. H. Allport, Cleveland, Ohio. R. R. Landon, Philippine Islands. I. H. Bergstein, New York. Alfred 0. Law, Cambridge, Mass. Capt. R. S. Burdette, San Antonio, Tex. James M. Little, Towanda, Pa. William R. Chedsey, State College, Pa. F. E. Marcy, Salt Lake City, Utah. L. R. Clapp, Philadelphia, Pa. H. F. Nash, Bartlesville, Okla. J. Murray Clark. L. S. Panyity, Columbus, Ohio. E. H. Claussen, San Francisco, Calif. W. C. Ralston, Reno, Nev. George E. Collins, -Denver, Colo. T. A. Rickard, San Francisco, Calif. George L. Collord, Sharpsville, Pa.. W. A. Rigby, Mt, Vernon, Iowa. William M. Corse, Mansfield, Ohio. H. H. Rowatt, Ottawa. Frank R. Crampton, Los Angeles, Calif. P. H. Royster, Pittsburgh, Pa. Capt. E. 0. Daue. Alan B. Sanger, Dorchester, Mass. A. E. Eddy, Butte, Mont. J. S. Shaw, Pittsburgh, Pa. N. H. Emmons, 2d, Lynchburg, Va. S. B. Shutts, Lynchburg, Va. E. W. Engelmann, Hayden, Ariz. Henry B. Smith, New Britain, Conn. F. A. Fahrenwald, Cleveland, Ohio. W. C. Smith, Roselle, N. J. 0. S. Finnie, Ottawa. Harry M. Spoor. John T. Fuller, Honesdale, Pa. D. M. Stackhouse, Johnstown, Pa. Major C. C. Griggs, Eureka, Utah. F. D. Stay,. Cleveland, Ohio. H. F. E. Gamm, Rutherford, N. J. D. B. Sterrett, St. Cyr, Que. A. W. Hackwood, Butte, Mont. R. H. Thayer, Yonkers, N. Y. C. L. Horne, Roanoke, Va. Kirby Thomas,. New York. B. B. Hood, Chrome, N. J. Henry Traphagen, Toledo, Ohio. R. E. Hore, Toronto Ont. H. D. Trounce, San Diego, Calif. Ross B. Hoffmann, Oakland, Calif. Henry J. Volkin, Ossining, N. Y. G. A. Joslin, Salt Lake City, Utah.. A. T. Ward, Bellefonte, Pa. John Johnston, Washington, D. C. Major L. W. Wickes. Paul S. King, Wilmington, Del. Horace V. Winchell, Minneapolis, Minn. E. William Kohl, Jr., Philadelphia, Pa. Fred L. Wolf, Mansfield, Ohio. W. H. Landers, San Francisco; Calif. J. Carson Adkerson, of the Stockwood Realty Corpn., Inc., of Woodstock, Va., writes that they are discontinuing their operations in Virginia on account of the conditions in the manganese market following the end of the war.

Jan 4, 1919

By E. B. Branson

Introduction to Geology, by E. B. Branson, W. A. Tarr, and W. D. Keller, revised-by Carl C. Branson. McGraw-Hill, 1952. $5.50.-Dealing with physical and historical geology, the book has been revised from an earlier edition. An attempt has been made to eliminate unnecessary detail in discussing processes and history. Revisions bring technical and statistical data up-to-date, and follow suggestions by teachers who used earlier editions. The book carries an eye witness account of the severe earthquake in Assam, India, in 1950 and the story of Paricutin and other major examples of volcanism. Charts summarize chemical weathering, and the results of metamorphisms. The book also contains many new illustrations, including aerial photographs. A History of Phelps Dodge 1834-1950, by Robert Glass Cleland. Alfred A. Knopf, 1952. $4.00.-The book traces the growth of Phelps Dodge from the day Anson Greene Phelps opened a small saddle shop in Hartford, Conn., to the present day. As the country grew, so did Phelps Dodge. The company took part in large affairs from its very beginning. It bought and sold, exported and imported, built factories and railroads, and widened its scope of operations economically and geographically. Entrance of Phelps Dodge into copper mining and the gradual giving up of other interests in favor of the new venture is traced.

Jan 1, 1952

By M. E. Lombardi

The cost of maintaining the production of an operating oil company is one of the most important, as well as one of the most difficult to estimate, of the various items which go to make up the total cost of producing oil. In the opinion of many operators the cost of drilling and developing new wells, whose, production takes the place of the loss in production through decreased yield of the old wells, is considered an operating expense, for the reason that the total income-producing power of the property is not increased. The cost of these new wells may be added directly to production expense, or it may be charged to capital account, and this account depreciated to the same extent. In either case, after an oil company is on a satisfactory income-producing basis, the money for drilling new wells to maintain production must be taken from the income of the company. Three factors determine the cost of maintaining production: First, the rate of decline in yield of the wells; second, the cost of drilling and equipping new wells in terms of their production; third, the decrease in initial production of new wells as the property is drilled and gas pressure taken off the sands, etc. In order to check theoretical figures for the cost of maintaining production the writer, with the assistance of Reed Bush and Fred Tough, has compiled the following figures. It is necessary first of all to choose a' period of time during which production for the field or territory studied remains fairly constant. The longer the period of time over which this condition prevails, the better. It is also necessary to eliminate or allow for any extraneous condition which may have affected the production returns, such as the shutting down of a large number of wells, the bringing in of a well of exceptionally large yield, the opening up of virgin territory where the flush yield is greater than will be had from new wells in after years, etc. All these conditions are exemplified most simply in the case of the Coalinga field, and perhaps these figures are more truly prophetic than the two other cases given. In applying these figures to the future it is well to assume that the average yield of new wells will constantly de-

Jan 1, 1916

By W. H. Gunniss

When the copper smelters were built, in Montana, all of the refractory products which were used in their construction were shipped in from Eastern factories. It was apparent that if a material suitable for the manufacture of these products could be found within the State, a saving of freight could be effected and a new industry built up. Prospecting for such materials was started and experiments were made with samples from numerous deposits. Considerable effort and funds were expended in an attempt to manufacture silica brick from Dillon quartz, a light colored sandstone that is found near Dillon, Mont., on the Oregon Shortline railroad. As a brick material the Dillon quartz was a failure, but it has proved very satisfactory as a silica cement. It is now being used in laying silica brick and for reverberatory furnace bottoms. A bed of quartzite that is particularly suited to the manufacture of high-grade silica brick was finally discovered at Browns Spur, 6 miles west of Anaconda. The material from this deposit is now being used in the manufacture of the Anaconda silica brick, which have gained a wide reputation for heat-resisting and lasting qualities. The analysis of an average sample of this quartz is: SiO2, 96.7; Fe2O3, 0.3; Al208, 2.5; CaO, 0.3 per cent. The very low percentage of fluxing ingredients makes this a most refractory material. All of the Anaconda silica brick are hand molded. Various types of brick machines have been tried, but the hand-mold process proved the best suited to the manufacture of silica brick from this material. The silica is first put through a jaw crusher and is then dumped into wet pans, where 4 per cent. of lime paste is added, to produce a bond. Without the lime the material would not be plastic enough to mold. After a few minutes' grinding in the wet pans the material is conveyed to the molder, who forces it into the molds by hand. The brick are then dumped on pallets and placed in the drier, where they are left. until dry enough to be set in the kilns. Some of the brick are re-pressed before being dried. They are burned about five days, in round down-draft kilns. It is not necessary to have as much heat in the kilns as the brick will be subjected to when in use in the furnaces. Montana refractories are used in smelters throughout the West. Prospecting for fire clays was also carried on. After experimenting with clays from several different deposits, it was found that a mixture of

Jan 1, 1914

By H. G. Dwyer

CONSIDERATION for future expansion influenced the design of the new smelter at Chuquicamata. The section of the smelter now going into operation, while large, represents only little more than half of the ultimate plant. Equipment for the direct smelting of raw concentrates has been arranged in the conventional manner although needless details have been eliminated wherever possible while mechanical and electrical features not usually found in copper smelters have been incorporated. Access is afforded to all equipment but platforms and walkways have been held to a minimum. The poling and other platforms in the converter aisle, normally subjected to battering by ladles and other heavy equipment in transit, are of concrete construction with steel grid armor embedded in the exposed surfaces. Noticeably absent are the many platforms formerly required for the handling of converter flux since this material is charged to the converters through the side walls of the converter uptake hoods. Clear space with ample headroom is provided under each converter and converter puncher's platform to permit clean-up by small bulldozers. Remote controls have been introduced at many points. Electrical control rooms and control centers have been conveniently located. An electrical tunnel with cross tunnels and escapeways is situated under the entire length of the converter aisle for power feed lines. Skull breaking facilities are in a separate building near the smelter. A silica-slurry building with brick storage area is adjacent to the smelter building so that elevator service is available to both buildings. A smelter office, a change house and lunchroom are provided in convenient locations. Units of the smelter as presently constructed are shown in the plan and table on page 1194. The ultimate smelter will house 7 reverberatory furnaces, 14 waste-heat boilers, 9 Peirce Smith converters, 4 casting furnaces serving 2 casting wheels, and one holding furnace serving a straightline casting machine. Additional crane requirements in the converter aisle will necessitate the installation of special hoisting equipment in space already provided in a raised section of the roof over the casting end of the aisle. Thus a complete crane may be lifted high enough above the crane rails to permit the passing of another crane underneath thereby giving all cranes full use of repair facilities already installed. For the collection of gases, 2 dust chambers, each with separate stacks, will collect converter gases and 2 balloon flues with separate stacks will collect reverberatory furnace gases. Extensions necessary to complete the ultimate plant will be possible with little interruption to normal operations since the future converters and reverberatory furnaces will be added at the east end while additional casting facilities will be added at the west end of the present plant. The future units may be added singly or all at one time depending on requirements.

Jan 1, 1952

By D. H. Newland

During the year 1907 an investigation of the Clinton formation in New York has been carried out under the direction of the State Geologist, and a full account of the results has been prepared for publication.' The more important economic features of the report are summarized in the present paper. Previous knowledge of this, the type, section of the Clinton has been contributed mostly by Hall and Vanuxem in their reports for the Natural History Survey of New York, which were issued in their final form in 1842-43. Brief accounts of the ore-occurrences have been given by 13. T. Putnam? J. C. Smock: A. H. Chester: and E. C. Eckel.5 Prof. C. H. Smyth, Jr.,6 has discussed the origin of the Clinton ores in two papers, which, so far as the local occurrences are concerned, have removed all doubt that may have existed on that subject. Distribution of the Clinton Formation. The Clinton strata in New York State are restricted to a single belt, which extends from the eastern central part to the Niagara river, which it crosses, and thence continues for some distance into the province of Ontario. The New York

Jan 1, 1910

Cyanidation and Concentration of Gold and Silver Ores. By J. V. N. Dorr and Francis L. Bosqui. Second edition, completely revised. Mc-Graw-Hill Book Co., New York. $8.50.-First issued 13 years ago, this book has become a milestone in the literature of mining and metallurgy. Mr. Dorr, with the assistance of F. L. Bosqui, has completely revised the book. Its comprehensive picture of ore dressing and hydrometallurgical methods are of importance to mining engineers and operators throughout the entire field. Operating data and methods, flowsheets, testing procedures, and many miscellaneous methods of extracting bullion are given. The book is divided into two sections, the first discussing principal unit processes involved in gold and silver recovery, and the second describing with flow diagrams a number of typical treatment plants selected from the more important gold and silver mining areas in various parts of the world. International Conference on Coal Preparation in Paris. English Language edition of transactions.-The transactions of the recent conference in Paris will be presented in the form of 6 issues of the revue de l'Industrie Minerale, and may be purchased for 3000 francs per set. About 60 papers were presented at the meeting, covering a wide range of interesting subjects. Ad- dress subscriptions to: Secretariat de la Societe de l'Industrie Minerale, 19 rue du Grand-Moulin, Saint-Etienne (Loire) France.

Jan 1, 1951

By John Charles

The Engineering Method. By John Charles Lou11sbul.y Fish. Stanford University Press. 1950. 186 P. $3.-This book is about the "professional habit often referred to . . . . as 'the scientific method' . . ." It formulates for students the system of logic and reasoning that is the mark of the practicing engineer. The three chapters are, "The Method of Engineering", "Application of the Engineering Method" and "Uncertainties in Engineering." They cover logic and reasoning, terms, nontechnical problems, practical conditions controlling the engineering method, inescapable uncertainties and the method of coping with them. The author is emeritus professor of civil engineering at Stanford. The material presented here formed chapters 9, 10, and 11 of The Engineering Profession, by Hoover and Fish, second edition 1950. Elements of Ore Dressing. By Arthur F. Taggart. John Wiley & Sons, Inc., New York, 1950. $10.- A modern and practical introduction to the subject by the noted author of the Handbook of Mineral Dressing. The philosophy that a mill and all its parts comprise a single treatment process is a continuing theme in the book. Professor Taggart covers hand picking, screening, filtration, and electrical concentration. After introducing sedimentation, he takes up acceleration in free-settling, hindered-settling, sink-float, jigging, film and trough concentrators and shaking concentrators. A discussion of organic chemicals in flotation is followed by a detailed treatment of flotation. Final chapters deal with primary crushing, secondary crushing, grinding, transport, and controls and flowsheets.

Jan 3, 1951

By Henry S. Burnholz, Charles Y. Clayton, Francis B. Foley

This work was first undertaken for the U. S. Bureau of Mines, in 1919-20, by C. E. Julihn, superintendent of the station at Minneapolis. Learning of the interest, in this subject, of B. F. Tillson, of the New Jersey Zinc Co., Mr. Julihn and Mr. Foley went to Franklin, N. J., and discussed the matter with him. A conference in Chicago, in November, 1920, was attended by Dr. F. G. Cottrell, who was then Director of the Bureau of Mines, and representatives of the Bureau of Mines and of the hlissouri School of Mines and Metallurgy; at this time a cooperative plan of work was agreed upon by the Bureau of Mines and the Missouri School of Mines. In February, 1921, Mr. 'Tillson arranged a conference on this subject at the time of the annual meeting of the American Institute of Mining and Metallurgical Engineers, at which several technical papers were presented. In a paper, the Breakage and Heat Treatment of Hock Drill Stcels, he suggested a program that might be carried out in connection with the investigation of the problem. At this conference Mr. Manning, former Director of the Bureau of Mines, suggested the formation of an advisory committee to the Bureaus of Mines and of Standards for prosecution of this investigation. On Feb. 20, 1922, a secoud conference in New York, at the time of the annual meeting of the American Institute of mlining and Metallurgical Engineers, was attended by representatives of various technical societies. At this meeting, the report of Nov. 20, 1921, of the Chiefs of Divisions of Metallurgy of the Bureaus of Mines and of Standards, was discussed and it was agreed: 1. That the survey recommended by the two bureaus should be undertaken, which survey would have for its object the ascertaining of the present status of the practice of the heat treatment of drill steels, the extent to which the breakage occurs, etc.; and 2. That a report should be presented, of the findings of those who made the survey, to the Advisory Board to the Bureaus of Mines and of Standards. The Bureau of Standards assigned $4000 to the prosecution 01 a three-months' survey, which was carried out in April, May, and June, 1922, of about sixty mines

Jan 1, 1923

By Charles Y. Clayton, Henry S. Burnholz, Francis B. Foley

This work was first undertaken for the U. S. Bureau of Mines, in 1919-20, by C. E. Julihn, superintendent of the station at Minneapolis. Learning of the interest, in this subject, of B. F. Tillson, of the New Jersey Zinc Co., Mr. Julihn and Mr. Foley went to Franklin, N. J., and discussed the matter with him. A conference in Chicago, in November, 1920, was attended by Dr. F. G. Cottrell, who was then Director of the Bureau of Mines, and representatives of the Bureau of Mines and of the hlissouri School of Mines and Metallurgy; at this time a cooperative plan of work was agreed upon by the Bureau of Mines and the Missouri School of Mines. In February, 1921, Mr. 'Tillson arranged a conference on this subject at the time of the annual meeting of the American Institute of Mining and Metallurgical Engineers, at which several technical papers were presented. In a paper, the Breakage and Heat Treatment of Hock Drill Stcels, he suggested a program that might be carried out in connection with the investigation of the problem. At this conference Mr. Manning, former Director of the Bureau of Mines, suggested the formation of an advisory committee to the Bureaus of Mines and of Standards for prosecution of this investigation. On Feb. 20, 1922, a secoud conference in New York, at the time of the annual meeting of the American Institute of mlining and Metallurgical Engineers, was attended by representatives of various technical societies. At this meeting, the report of Nov. 20, 1921, of the Chiefs of Divisions of Metallurgy of the Bureaus of Mines and of Standards, was discussed and it was agreed: 1. That the survey recommended by the two bureaus should be undertaken, which survey would have for its object the ascertaining of the present status of the practice of the heat treatment of drill steels, the extent to which the breakage occurs, etc.; and 2. That a report should be presented, of the findings of those who made the survey, to the Advisory Board to the Bureaus of Mines and of Standards. The Bureau of Standards assigned $4000 to the prosecution 01 a three-months' survey, which was carried out in April, May, and June, 1922, of about sixty mines

Jan 1, 1923

By H. H. Uhlig

A study of passivity in chromium-iron alloys holds considerable interest, both because of the present-clay practical importance of the stainless steels, and because of the scientific importance attached to the mechanism of their corrosion resistance. Upon the discovery of the passive chromium-iron alloys in 1912, it seemed logical to attribute the observed phenomenal corrosion resistance to a thin, continuous, protective reaction product on the surface. The product was thought to be Cr2O3 or a similar oxide containing both chromium and iron. This mechanism seemed likely in view of Michael Faraday's conjecture that passive iron is not reactive in concentrated nitric acid because of an oxide on the metal surf ace. Since 1912, data have accumulated that permit a further exploration into the nature of passivity and provide a new approach to the problem. A summary of the facts lends considerable weight to a mechanism based not on physical protection of an oxide or similar compound, although such compounds may be present on the surface, but to a change in tendency of surface metal atoms to react chemically. This change in reaction tendency is ascribed to chemisorbed films that effectively satisfy residual valence forces of the metal surface, but do not appreciably disturb the positions of metal atoms in the lattice. In other words, formation of a new lattice such as that of an oxide is not a necessary condition for this type of passivity. The decreased reaction tendency of the metal by reason of chemisorbed films can thereby account for low reaction rates of the stainless steels in many media, as well as a noble galvanic potential as is observed. Substances capable of adsorbing on the stainless steels, and hence accompanying the property of passivity, are typically oxygen, nitrites or chromates, but are not in any sense limited to these. Other elements and compounds can also chemisorb, and therefore may also play a major part in the mechanism of passivity in specific media. The mechanism of passivity based on chemisorption or activated adsorption begins with the interpretation Langmuir proposed for his experiments concerning adsorbed oxygen on tungsten.' He found that adsorbed oxygen was tightly bound, remaining on the tungsten surface above temperatures at which WO3 rapidly volatilizes. The oxygen in such a state did not readily react with hydrogen even at

Jan 1, 1949

By Herbert H. Uhlig

A STUDY of passivity in chromium-iron alloys holds considerable interest, both because of the present-day practical importance of the stainless steels, and because of the scientific importance attached to the mechanism of their corrosion resistance. Upon the discovery of the passive chromium-iron alloys in 1912, it seemed logical to attribute the observed phenomenal corrosion resistance to a thin, continuous, protective reaction product on the surface. The product was thought to be Cr2O3 or a similar oxide containing both chromium and iron. This mechanism seemed likely in view of Michael Faraday's conjecture that passive iron is not reactive in concentrated nitric acid because of an oxide on the metal surface.† Since 1912, data have accumulated that permit a further exploration into the nature of passivity and provide a new approach to the problem. A summary of the facts lends considerable weight to a mechanism based not on physical protection of an oxide or similar compound, although such compounds may be present on the surface, but to a change in tendency of surface metal atoms to react chemically. This change in reaction tendency is ascribed to chemisorbed films that effectively satisfy residual valence forces of the metal surface, but do not appreciably disturb the positions of metal atoms in the lattice. In other words, formation of a new lattice such as that of an oxide is not a necessary condition for this type of passivity. The decreased reaction tendency of the metal by reason of chemisorbed films can thereby account for low reaction rates of the stainless steels in many media, as well as a noble galvanic potential as is observed. Substances capable of adsorbing on the stainless steels, and hence accompanying the property of passivity, are typically oxygen, nitrites or chromates, but are not in any sense limited to these. Other elements and compounds can also chemisorb, and therefore may also play a major part in the mechanism of passivity in specific media. The mechanism of passivity based on chemisorption or activated adsorption begins with the interpretation Langmuir proposed for his experiments concerning adsorbed oxygen on tungsten.1 He found that adsorbed oxygen was tightly bound, remaining on the tungsten surface above temperatures at which WO3 rapidly volatilizes. The oxygen in such a state did not readily react with hydrogen even at

Jan 1, 1947

By Shueling Woo, Charles S. Barrett, Robert F. Mehl

When one solid phase is generated from another, fixed and rational orientation relationships are observed to subsist between the parent and the new crystal. The principle has been proposed1 that the relationships obtaining between the same two phases are identical whatever the type of phase change involved, or whichever of the phases may act as parent. Many types of phase changes have been studied: allotropic transformations in pure metals, precipitation from solid solutions, eutectoid decompositions, peritectic reactions, the formation of oxide layers, and others2 Phase layers generated by diffusion of one metal into another constitute an additional type of reaction. This report provides new data on the orientation relationships occurring between phase layers formed by diffusion, in the Cu-Zn system,§ and furnishes further evidence in support of the principle. Materials and Methods The Cu-Zn system is especially suitable for these studies since the high vapor pres- sure of Zn provides an opportunity readily to create one phase poorer in Zn upon a parent phase richer in Zn by removing Zn by vaporization, or to reverse this process by adding Zn from Zn vapor; e.g., the beta phase can be found as a layer upon gamma by dezincing, or gamma can be found on beta by addition of Zn from Zn vapor. Since orientation relationships are to be sought, requiring crystals large enough for orientation determinations, it is convenient to prepare single crystals or large grains of the parent phase. The samples were prepared from oxygen-free high-conductivity copper and Horse Head zinc by melting under a borax flux in a graphite crucible. Large crystals of beta brass were grown by the strain-anneal method, in plates sectioned from the cast ingots, by the following procedure. Rockwell-hardness indents were made at I cm. intervals and with various loads, then the plates were annealed for 4 days at 700°C. in Nichrome boxes packed with beta-brass chips and graphite. Surface layers were removed by grinding and etching to a depth of about 1.0 mm., and individual grains were cut out. Crystals of alpha and gamma brass were prepared by freezing, by lowering a graphite crucible at speeds less than one inch per hour through a furnace held at a constant temperature above the melting point. Single crystals were cut out with a jeweler's saw, ground, polished and etched. Care was taken to remove cold-worked layers from the finished crystals

Jan 1, 1944

By Charles S. Barrett, Robert F. Mehl, Shueling Woo

When one solid phase is generated from another, fixed and rational orientation relationships are observed to subsist between the parent and the new crystal. The principle has been proposed1 that the relationships obtaining between the same two phases are identical whatever the type of phase change involved, or whichever of the phases may act as parent. Many types of phase changes have been studied: allotropic transformations in pure metals, precipitation from solid solutions, eutectoid decompositions, peritectic reactions, the formation of oxide layers, and others2 Phase layers generated by diffusion of one metal into another constitute an additional type of reaction. This report provides new data on the orientation relationships occurring between phase layers formed by diffusion, in the Cu-Zn system,§ and furnishes further evidence in support of the principle. Materials and Methods The Cu-Zn system is especially suitable for these studies since the high vapor pres- sure of Zn provides an opportunity readily to create one phase poorer in Zn upon a parent phase richer in Zn by removing Zn by vaporization, or to reverse this process by adding Zn from Zn vapor; e.g., the beta phase can be found as a layer upon gamma by dezincing, or gamma can be found on beta by addition of Zn from Zn vapor. Since orientation relationships are to be sought, requiring crystals large enough for orientation determinations, it is convenient to prepare single crystals or large grains of the parent phase. The samples were prepared from oxygen-free high-conductivity copper and Horse Head zinc by melting under a borax flux in a graphite crucible. Large crystals of beta brass were grown by the strain-anneal method, in plates sectioned from the cast ingots, by the following procedure. Rockwell-hardness indents were made at I cm. intervals and with various loads, then the plates were annealed for 4 days at 700°C. in Nichrome boxes packed with beta-brass chips and graphite. Surface layers were removed by grinding and etching to a depth of about 1.0 mm., and individual grains were cut out. Crystals of alpha and gamma brass were prepared by freezing, by lowering a graphite crucible at speeds less than one inch per hour through a furnace held at a constant temperature above the melting point. Single crystals were cut out with a jeweler's saw, ground, polished and etched. Care was taken to remove cold-worked layers from the finished crystals

Jan 1, 1944

By Charles S. Barrett, Robert F. Mehl, Shueling Woo

WHEN one solid phase is generated from another, fixed and rational orientation relationships are observed to subsist between the parent and the new crystal. The principle has been proposed' that the relationships obtaining between the same two phases are identical whatever the type of phase change involved, or whichever of the phases may act as parent. Many types of phase changes have been studied: allotropic transformations in pure metals, precipitation from solid solutions, eutectoid decompositions, peritectic reactions, the formation of oxide layers, and others.2 Phase layers generated by diffusion of one metal into another constitute an additional type of reaction. This report provides new data on the orientation relationships occurring between , phase layers formed by diffusion, in the Cu-Zn system, § and furnishes further evidence in support of the principle. MATERIALS AND METHODS The Cu-Zn system is especially suitable for these studies since the high vapor pressure of Zn provides an opportunity readily to create one phase poorer in Zn upon a parent phase richer in Zn by removing Zn by vaporization, or to reverse this process by adding Zn from Zn vapor; e.g., the beta phase can be found as a layer upon gamma by dezincing, or gamma can be found on beta by addition of Zn from Zn vapor. Since orientation relationships are to be sought, requiring crystals large enough for orientation determinations, it is convenient to prepare single crystals or large grains of the parent phase. The samples were prepared from oxygen-free high-conductivity copper and Horse Head zinc by melting under a borax flux in a graphite crucible. Large crystals of beta brass were grown by the strain-anneal method, in plates sectioned from the cast ingots, by the following procedure. Rockwell-hardness indents were made at I cm. intervals-and with various loads, then the plates were annealed for .4 days at 700°C. in Nichrome boxes packed with beta-brass chips and graphite. Surface layers were removed by grinding and etching to a depth of about 1.0 mm., and individual grains were cut out. Crystals of alpha and gamma brass were prepared by freezing, by lowering a graphite crucible at speeds less than one inch per hour through a furnace held at a constant temperature above the melting point. Single crystals were cut out with a jeweler's saw, ground, polished and etched. Care was taken to remove cold worked layers from the finished crystals

Jan 1, 1944

By J. E. Tobey

UNQUESTIONABLY, manufactured gas will stage a comeback of such huge proportions as to dwarf its previous history. Timing will depend on two things: the diminishing supply of natural gas and the perfecting of processes for large-scale production of high-Btu gas from, coal. What the timing will be, and how soon the new era will begin for manufactured gas, no one knows. It may be just around the corner and it may be several years, but it is certain to come. It will depend on economic changes, and any major world upheaval might accelerate it tremendously. Supplemental gas for pipelines will come no doubt from two sources at least: (1) synthetic-fuel plants of the coal-chemical group, which produce chemicals and liquid fuels with a tail gas high in methane as a by-product; and (2) large-scale gasification plants, which will produce high-Btu gas entirely or as a major product with chemicals and liquid fuels as by-products. There is important activity at the present time, in the development of new processes and the improvement of those now in existence. The first large-scale gasification plants of the second category probably will be strategically located in the coal fields on or near the long-distance transmission gas lines, and these plants probably will operate jointly with large natural gas storage fields. Inasmuch as virtually all the major gas-transmission lines cross one or more coal fields, such locations will not be difficult to find. It will be a practical necessity to produce a high-Btu gas -that is, 750 to 1000 Btu-in order to maintain the capacity of the main transmission lines and local city distribution systems and further to eliminate the problem of appliance changeovers in the cities. If gasification plants on a medium or smaller scale prove to be economical, local gas utilities no doubt will consider .the construction of such plants to supplement their supply of natural gas. If low-temperature distillation processes like those now being developed by the Pittsburgh Consolidation Coal Co. are successful, and there is reason to believe that they will be, utilities that supply both gas and electricity to communities would find this method particularly attractive, as they could burn the char product directly under power boilers, thereby minimizing thermal

Jan 1, 1953

By J. L. Bray

IT is well known that iron markedly improves the physical properties and casting characteristics of aluminum bronzes. The use of 1 to 4 per cent iron as the principal modifying addition has become common practice in many foundries melting aluminum bronzes. Although the beneficial effects of iron are unquestioned, there is some uncertainty regarding the structural changes caused by it in the basic copper-alumi-num system. It is agreed that a new constituent appears in abundance when the iron content reaches 2 to 4 per cent. This constituent, which frequently occurs in shapes resembling clover leaves, is sometimes assumed to be an aluminum-iron intermetallic compound. If this were correct we might expect a change in the structural relationships of the matrix in the direction of decreased aluminum content. On the other hand, it has been reported that iron has a negligible effect in altering the fundamental relationships of copper-aluminum alloys1. Others2,3 have reported an additive coefficient. Apparently it will be necessary to know the equilibrium relationships between the phases of the copper-aluminum-iron alloy system to establish any such theory as fact. When this has been done it may very well be that a further revision in the structural relationships may be necessary to describe the changes to be expected in commercial cast alloys. It was with this latter problem before them that the authors attempted to

Jan 1, 1936