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By J. Poijärvi, J. Rastas

Recently, when increasing attention has been paid to mercury for environmental reasons, the interest of several plants is directed to the removal of mercury from roaster and smelter gases. When Outokumpu Oy built its zinc plant at Kokkola in 1969, intensive development work was started to find an efficient and economic method for mercury removal from roaster gases. A process was developed, after laboratory research and pilot plant tests, to eliminate and completely recover mercury from the roaster gases. The process was commissioned in 1970. The behaviour of mercury in the roasting process and several possible methods of removing it from gases are discussed in this paper. Theoretical investigations and empirical tests show that the removal of elemental mercury from gases by sulphatization is very efficient. Further, it is stated how the technical process was built on this idea. The zinc sulphide concentrates contain small quantities of selenium, chlorine and fluorine. The role of selenium in the process is described. Similarly, the behaviour of chlorine and fluorine in the roasting, sulphatizing and scrubbing units has been discussed. Finally, the recovery of purified mercury and selenium from the precipitates is described.

Jan 1, 1973

By Robert L. Bates

An industrial mineral, says the Glossary of Geologic Terms, is "any rock, mineral, or other naturally occurring substance of economic value, exclusive of metallic ores, mineral fuels, and gemstones; one of the nonmetallics." Probably most geologists and engineers would accept this simple and straightforward definition, at least as a general statement. On analysis, however, certain anomalies crop up. For example, it may be considered arbitrary to include industrial diamond and corundum, but to exclude their precious varieties, gem diamond and sapphire. So the present volume has a section on gems and gem materials, in spite of the definition. Another problem arises when we try to define precisely what is metallic and what is nonmetallic. Bauxite and ilmenite certainly qualify as metallic ores, but both are also raw materials of important nonmetallic substances; hence they are included in the book. A third anomaly is that, by common consent of geologists, engineers, mineral economists, and others concerned, the term industrial minerals may include not only rocks and minerals but also certain manufactured products like cement and lime, and even mixed groups of natural and artificial products, such as abrasives and refractories. Thus the central realm of the industrial minerals is clear enough, but its boundaries tend to be indefinable. Since a definition that allowed for every irregularity in the outer fringes would be excessively un- wieldy, the one quoted above may be considered satisfactory. The expression industrial minerals is commonly equated with nonmetallics, and with the somewhat more precise phrase industrial minerals and rocks as in the title of this book.

Jan 1, 1975

The phosphate pebble-bearing matrix in the Florida Phosphate Pebble Field has physical properties which make it readily adaptable to hydraulic transportation methods employing solids-handling pumps and pipelines. The abundance of water available, a practically flat terrain, low costs per ton-mile, and beneficiation of the matrix by agitation while being pumped have contributed to the popular choice of hydraulic transportation. Phosphate pebble mining in Florida, begun in the 1860's, first used high pressure water and solids-handling pumps for overburden removal about 1900. Removal of the average 25 ft of overburden was followed by hydraulic mining of the matrix, with 6-in. and 8-in. pumps handling 50 to 100 cu yds per hour being moved along the floor of the pit as they were advanced toward the face being undercut and slurried by hydraulic guns.

Jan 3, 1961

By Walter Mueller

Transition in the underground coal industry, begun with the passage of the Federal Coal Mine Health and Safety Act of 1969, should be completed midway in the 1972-80 period. Surprisingly, many of the far reaching effects of this act have been, for the most part, beneficial to the industry from the standpoint of health, safety and basic operating standards. Production has dwindled, but the next few years will see production declines level out. Average declines of approximately 27% have been recorded since passage of the 1969 act, with costs increasing an average of $1.50 per ton throughout the industry. Nationwide averages presently are in the range of 14 tons per man-shift, and by 1980 this may be further reduced to a 10-ton per man-shift average for the industry. But in spite of the many temporary set-backs affecting the industry, the marketing opportunities are clearly visible. Due primarily to the energy squeeze facing the U.S. over the near term, the 'underground coal operator is and will be enjoying unusual leverage in selling his product.

Jan 10, 1972

On Wednesday evening, Jan. 27, 1915, were held in the auditorium of the Engineering Societies Building the inaugural exercises of The Engineering Foundation, established by the United Engineering Society. The initial gift to the Foundation of $200,000, made by Ambrose Swasey, Past President of the American Society of Mechanical Engineers, was formally accepted at this time. So far as known this is the first instance of a foundation devoted to engineering purposes. This meeting con-stituted also an appropriate tribute to the generous gift made to the Foundation and gave opportunity for expression of the satisfaction and approval which are felt by engineers everywhere at the establishment of a means of promoting the good of mankind through the work of the engineer along the broadest lines. Gano Dunn, President of the United Engineering Society and Past President of the American Institute of Electrical Engineers, acted as presiding officer, and on the platform were seated representatives of the three societies constituting the United Engineering Society, and of the American Society of Civil Engineers. Members of the four societies and many other friends interested in the profession composed the audience.

Jan 3, 1915

By W. B. Mather

GEOLOGICAL studies have revealed the occurrence of hundreds of pegmatite dikes in north- east Brazil, Fig. 1, in the three states of Rio Grande do Norte, Paraiba, and Ceara. Heretofore data have not been available on the possible production of lithium minerals from these areas, and in March, April, and May 1953 the author undertook a reconnaissance survey covering a cross-section of the pegmatites. Sixty-one pegmatites were examined. The pegmatites of Rio Grande do Norte and Paraiba are located in an arid region (Seratao), and except in the most southerly portion there is a mini- mum of vegetation and overburden. The region is easily prospected and relatively accessible by jeep or truck. The pegmatites examined in Ceara are in an area of lush vegetation along the flanks of the Jaqueribe River valley. It is therefore more difficult to prospect, and the dirt roads, as a means of access, leave much to be desired. For all practical purposes rail transportation, except in Ceara, is not available. The rocks of the area1-4 are composed of Pre-Cambrian schist, gneiss, quartzite, and marbles. They have been intruded by granites, monzonites, and diorites and cut by quartz veins and pegmatites.

Jan 9, 1954

By E. N. Cameron

Graphite has been included in U. S. lists of strategic minerals since the problem of mineral deficiencies was revealed during World War I. Since 1918 the domestic graphite industry has led a precarious existence, and there has been much uncertainty as to the amounts of usable graphite of various grades that would be available from domestic sources in time of emergency. In 1950-1951 therefore, the writer, assisted by Paul L. Weis, undertook a review of domestic graphite sources for the U. S. Geological Survey. The conclusions of this study are presented here, with a discussion of some technologic and politico-economic factors bearing upon the problem. Uses of Graphite: Natural graphite as marketed exhibits a wide range of properties, which determine the uses to which it is put. The most essential uses are in the manufacture of crucibles and related refractory articles, in lubricants and packing materials, and in the manufacture of batteries, foundry facings, pencils, and carbon brushes. Numerous specifications covering the mineral in its various applications must be met by producers and processors of graphite. The problem of supply is therefore not simply one of procuring a sufficient total tonnage, but the more difficult problem of procuring enough of each different grade to meet foreseeable needs.

Oct 1, 1956

By Otto F. Pfordte

The great advance of the last twenty years in the specialization, delicacy and efficiency of ore-concentrating apparatus calls for a finer system of testing both the qualities of ores and the operations of machines in this department. In amalgamation, lixiviation and smelting, the daily employment of physical and chemical tests has been recognized as necessary, and the cost of the necessary laboratories and employees is cheerfully paid. But while much progress has been made in concentration (due, in a large degree, to the study of the subject in our technical schools), it is still too common in actual practice to follow the loose old method of roughly estimating, once for all, that a given ore " concentrates x tons into one," and resting on this assumption so long as that ore continues to be treated, while assays of the tailings from concentration are made from time to time, without exact determination of their quantity. The first step toward accuracy of control must be a more frequent and precise measurement of the quantity of concentrates from a given operation. This should be expressed in pounds per unit of one ton; and the variations shown in frequent determinations will furnish a constant check upon the character of the ore and the performance of the apparatus. But this is only a part of what should be constantly and systematically done to insure the best work upon a material which must vary continually, even though it come from one mine only. If, in any mill, appropriate laboratory-tests were made at least once a week, the labor and expense involved would be amply repaid by increased knowledge and control of the current operations. A small testing-laboratory, provided with a few gold-pans;

Jan 1, 1902

By F. C. von der Weid

The mining district of Sao Fidelis, in the northern part of the State of Rio de Janeiro, is situated on the Paraiba River, where it crosses the Serra do Mar (Mountain of the Sea), in the center of a mountainous country having numerous graphitic outcrops. For a long time, these outcrops were irregularly explored by local people, who had little means and no technical advice. A few years ago, the Cia. Brasileira de Minerasgo de Grafite took over the control of some of the more important outcrops and entrusted to me the task of studying the ores and establishing a flowsheet for a pilot plant to be situated in São Fidelis—the ore to be concentrated being mostly of a very high grade. Mineralization and Ores The rocks of the district are mostly gneiss and crystalline schists, with occasional interstratification of dolomitic limestone belonging to the Archean Brazilian Fundamental Complex. The general direction of the beds is roughly between 60" and 80°E., with variable dip, generally nearly vertical. Mostly, direction and dip of the graphitic outcrops is concordant with the embanking gneisses or schists. These outcrops seem to be aligned in two or three parallel zones (Pádua, São Fidelis, Mac- abu), the Sao Fidelis zone being the best known and the most important to date. Two outcrops of the São Fidelis zone, Saudade and Sao Benedito, are now being exploited. Mining has been carried out, so far, on a small scale. The mineralization consists of a vein of nearly massive graphite in a very compact, partially granitized gneiss, with vertical dip. The vein is most irregular, with nests and lenses irregularly distributed along the fracture plane. The ore consists chiefly (particularly in Sao Benedito) of massive graphite appearing and disappearing along the main direction of the vein, forming a succession of irregular lenses in a sort of rosary design. The average width is more or less one foot, with variations from zero to 6 feet. The lode minerals are quartz, a little feldspar and garnet (the latter having its origin perhaps in the embedding gneisses), with rare ferruginous clays on the outcrops. In Saudade a little pyrite, pyrrhotite and chalcopyrite is found occasionally, as well as a carbonaceous mineral, very light, black and shiny, with conchoidal fracture, looking like a sort of jet. The composition of this mineral has not yet been established, but it seems to be very complex. The mineralization seems to be hydro-thermal at a rather low temperature, perhaps mesothermal. The paragenesis, according to samples from Saudade, seems to be as follows, the earlier minerals being listed first: pyrrhotite, pyrite, chalcopyrite, with quartz concomitant to the three and graphite formed later. Age of the mineralization is still uncertain, owing to the very in-

Jan 1, 1948

By W. T. Isbell, Carleton C. Long

Zinc recovery from lead blast-furnace slags has heretofore been an indirect process, involving, first, the fuming off and collecting of an impure zinc oxide, and second, the reduction of the zinc portion of this oxide to metal either by electrolytic or pyrolytic means. (In a variation of this process, blue powder is the intermediate product rather than zinc oxide fume.) In 1940, W. T. Isbell proposed that molten slag from the lead blast furnace or stock-pile slag melted down in a blast or cupola-type furnace be charged directly into an airtight container (i.e., furnace) provided with means to heat further the slag by passage of electric current and means to introduce the carbon (coke) necessary to reduce the ZnO constituent of the slag to zinc as a zinc vapor and CO. He also proposed that the zinc vapors so obtained be condensed in a Weaton-Najariant internal condenser directly connected to the proposed furnace. It was thought that the Weaton-Najarian condenser could liquefy zinc vapor from lean mixtures of vapor and noncondensable gases. Such condensers have been in commercial use! since 1936 at Josephtown smelter, where the source of zinc vapor is a column of coke and zinc-bearing sinter electrically heated (charge resistor). Condenser output when supplied with vapor-gas mixtures containing approximately 45 per cent zinc and 55 per cent noncondensable gases, varies from 18 to 30 tons of slab zinc per day per condenser, depending upon the heat-transfer area (length) of the condenser and the volume of vapor (furnace size) fed to it. Lead-smelting operations at the St. Joseph Lead Company's plant at Hercu-laneum, Mo., produce a slag containing 12 to 16 per cent zinc. For several years this slag has been stock-piled with the object of recovering the zinc values if and when a commercial method was invented. Evaluation of the possibilities of the proposed method was made by pilot-plant operation at Josephtown. The first plant, designed in 1940 and operated in early 1941, consisted of a single-phase, two-electrode furnace. The evolved vapors were burned. Electrical characteiistics of the molten slag, power requirements, coke requirements, and extent of zinc elimination indicated the feasibility of the proposed method. In the latter part of 1941 a second pilot furnace was constructed, to which "was attached a small (6 ft. long) Weaton-Najarian condenser in order to develop an over-all picture of zinc-in-slag to zinc-in-slabs. This furnace was operated in the early part of 1942 and yielded such promising results that a decision was made to design- and construct a commercial furnace. Feed for the pilot-plant furnaces was granulated slag. A suitable deduction (300 to 350 kw-hr. per ton slag) was calculated in estimating power require-

Jan 1, 1944

By F. C. von der Weid

The mining district of Sao Fidelis, in the northern part of the State of Rio de Janeiro, is situated on the Paraiba River, where it crosses the Serra do Mar (Mountain of the Sea), in the center of a mountainous country having numerous graphitic outcrops. For a long time, these outcrops were irregularly explored by local people, who had little means and no technical advice. A few years ago, the Cia. Brasileira de Minerasgo de Grafite took over the control of some of the more important outcrops and entrusted to me the task of studying the ores and establishing a flowsheet for a pilot plant to be situated in São Fidelis—the ore to be concentrated being mostly of a very high grade. Mineralization and Ores The rocks of the district are mostly gneiss and crystalline schists, with occasional interstratification of dolomitic limestone belonging to the Archean Brazilian Fundamental Complex. The general direction of the beds is roughly between 60" and 80°E., with variable dip, generally nearly vertical. Mostly, direction and dip of the graphitic outcrops is concordant with the embanking gneisses or schists. These outcrops seem to be aligned in two or three parallel zones (Pádua, São Fidelis, Mac- abu), the Sao Fidelis zone being the best known and the most important to date. Two outcrops of the São Fidelis zone, Saudade and Sao Benedito, are now being exploited. Mining has been carried out, so far, on a small scale. The mineralization consists of a vein of nearly massive graphite in a very compact, partially granitized gneiss, with vertical dip. The vein is most irregular, with nests and lenses irregularly distributed along the fracture plane. The ore consists chiefly (particularly in Sao Benedito) of massive graphite appearing and disappearing along the main direction of the vein, forming a succession of irregular lenses in a sort of rosary design. The average width is more or less one foot, with variations from zero to 6 feet. The lode minerals are quartz, a little feldspar and garnet (the latter having its origin perhaps in the embedding gneisses), with rare ferruginous clays on the outcrops. In Saudade a little pyrite, pyrrhotite and chalcopyrite is found occasionally, as well as a carbonaceous mineral, very light, black and shiny, with conchoidal fracture, looking like a sort of jet. The composition of this mineral has not yet been established, but it seems to be very complex. The mineralization seems to be hydro-thermal at a rather low temperature, perhaps mesothermal. The paragenesis, according to samples from Saudade, seems to be as follows, the earlier minerals being listed first: pyrrhotite, pyrite, chalcopyrite, with quartz concomitant to the three and graphite formed later. Age of the mineralization is still uncertain, owing to the very in-

Jan 1, 1948

By Otto F. Pfordte

Although the subject has no practical bearing on the metallurgy of the present day, it may not be entirely uninteresting to note how the art of silver-lead smelting has been, and in a few remote districts of Peru is still practiced by an old method, and under conditions widely different from our own. The subject will be considered under the following subdivisions,. viz.: The general conditions; construction and plan of furnaces;, fuels and ores; method of working; furnace products and slags. The mineral region of Peru varies in altitude from 10,000 to 16,000 feet above sea-level, comparatively few mines being locatedh above or below these limits. The timber-line in the valleys is at about 12,000 feet altitude on the western slope of the mountains, and even there the supply of wood is not sufficient to be utilized as fuel for furnaces. The sides of the mountains are either bare or covered with a hard bushy grass, which is most luxuriant during the latter part of the rainy season, from February to April. Agriculture on the western slope rarely reaches above 12,000 feet, while on the eastern slope its limit is at 14,000 feet; and in either case the height named is reached only in sheltered places. Transportation is slow, being carried on mainly by llamas, donkeys and mules; the former (taking 100 pounds at a load) are almost

Jan 1, 1893

E. T. DUMBLE, Houston, Tex.-This paper is a continuation of one that was published by Mr. Garfias, I believe, in the Journal of Geology, 1912, in which he gave the results of his investigations in Mexico, showing that the basalt extrusions frequently did not come up as cones. but reached the surface as a small neck and then mushroomed out into a sill, penetrating the beds both in limestones and in shales. He has continued his investigations to show that as these basalt protrusions came up they forced the strata into a funnel shape at the top instead of throwing them out altogether. While this may be true concerning these particular beds, there are other places at which the basalt does appear clearly as cones and dories, and there the funnel structure does not exist. We know that the sills are there, because we find them in the wells. In one well that I know of. we found a 2-ft. sill of basalt at about 1600 ft. and oil below it at about 2100 ft.; others have gone through similar beds. We also know that there. are cones, because north of the Ranuco River one well struck basalt at about 800 ft. and continued in it for several hundred feet-did not pass through it at all. This paper of Mr. Garfias will give us considerable help in that oil field. W. E. WRATHER, Wichita Falls, Tex.-I would like to ask for information as to the temperatures of Mexican oils. I have heard a number of conflicting reports about the high temperatures of the water and oil, and the relationship between them.

Jan 1, 1918

By John Gill

THE purpose of this paper is to invite attention away from the obvious, direct monetary costs of oil-field overdevelopment (as dis-tinguished from "social costs") to a consideration of the role played by the exercise of freedom to create even allegedly excessive1 plant facilities in contributing to the maintenance of equilibrium in the whole economy and in promoting material progress. The obvious and most commonly discussed effect of overdevelop-ment of oil fields is illustrated by the allegation that already the excessive development of the East Texas field has cost upward of $162,000,000;2 in other words, the drilling of 12,500 wells more than the number esti-mated as the requirement for economical recovery of the reserve has unnecessarily raised the total cost of development that amount. Many other illustrations of so-called excessive development of oil pools could be presented. Some of them, like Cushing, Powell and Long Beach, might be drawn from the era antedating widespread discussion in the trade of such matters as optimum well spacing, reservoir energy, the conservation rate of depletion of reserves, etc. Numerous other cases can be found in the records of the current era, which began with the introduction of rationalized restriction of production. Besides East Texas, there may be mentioned Oklahoma City, Centralia and, more recently, the town-lot development of Bloomingdale, Michigan.

Jan 1, 1939

By L. W. Kempf

THE thermal conductivity of aluminum alloys is of considerable indus-trial importance. This is particularly true in such applications as inter-nal-combustion engines where one of the principal reasons for the use of these alloys is their relatively higher thermal conductivity. In spite of this, relatively few data are available on this property of aluminum alloys. The reason is quite apparent to anyone concerned with the experimental determination of coefficients of thermal conductivity. This determina-tion, in theory so simple, is extraordinarily difficult if any high degree of precision is desired. Fortunately, some knowledge of the relationship between thermal and electrical conductivity has permitted the use of the latter physical property in deducing the relative approximate-values of the thermal conductivities of metals. This fundamental relationship, first enunciated by Wiedemann and Franz1 as applying to metallic elements and later shown by Lorenz to be applicable to alloys within a single metallic system, has been of service in the industrial application of metals. The electrical conductivity of metals is easily determined with a high degree of precision. It is, therefore, quite desirable that the relationship between electrical and thermal characteristics be determined with the greatest possible precision. This paper presents data on the electrical and thermal conductivities of a number of aluminum alloys of industrial importance.

Jan 1, 1937

By Brown, R. W., G. H. Neill, R. G. Loper

All facets of ball sealer behavior must be known and understood to design for their optimum use in well treatments. The down-hole factors including the inertial forces, drag forces and holding forces have been discussed. Equations have been developed and presented for these forces. The use of these equations in this process will contribute to the most efficient use of an economical and proven ball sealer process. The urocedure presented has been used to successfully analyze field results indicating problems involving the use of ball sealers. These problems have been isolated and corrected in future treatments by using the procedure presented to revise the perforating program, the injection rate, the design of ball sealer stages and/or the type and size of ball sealers. The procedure presented also indicates that dislodgement of ball sealers occurs primarily in ultra slim-hole completions. INTRODUCTION The perforation sealing process has been proven highly successful and economical since it was introduced to the oil and gas industry in early 1956.' Since it has proved so successful in multistage fracture treatments at a much lower cost than conventional packers, the ball sealer process has become a byword in well completions.' Not only has it changed the design of fracture treatments, it has changed the concepts of selectively perforating and has greatly aided the success of the single-point and limited-entry techniques." Yet with all the advantages, there are still facets of ball sealer behavior that are not widely recognized. These must be known and understood to better design and execute the optimum ball sealer treatment. The down-hole behavior of ball sealers is influenced by a number of factors including an "inertial force", a "drag force" and a "holding force". These are considered in two phases—the initial seating of the ball and the forces tending to unseat the ball after contact has been made (see Fig. 1). This paper presents a theoretical study of these factors and formulas for predicting their influence. The authors acknowledge the fact that the flow equations presented herein describe the behavior of Newtonian fluids and do not cover the so-called power-law fluids. The assumptions made, however, are reasonable and well within practical limitations of the conditions encountered during field application. For example, it is assumed that the perforations are round with a discharge coefficient of 0.82. While this may not be exactly true, it has been verified within practical field limitations.' The discharge coefficient would not vary significantly even if the perforation size or configuration varied pronouncedly. The approach of assuming uniform perforation size is not as strained as it might first appear. Normally, a perforator contains charges equally spaced with the same number in each vertical (or horizontal) plane. If the perforating gun is not centralized, the holes in one plane will be smaller than average, while the holes in opposing planes will tend to be larger than average. The net result is that the two effects tend to balance. FACTORS AFFECTING CONTACT WITH PERFORATlON Ball sealers are injected into well treating fluids for the purpose of contacting and sealing those perforations which are accepting the fluid flow. The efficiency of the sealers is primarily influenced by: (1) the velocity of the balls down the pipe, and (2) the fluid velocity through the perforations. To divert the sealer to the perforation, the inertial force of the ball must be overcome by the drag force created by the fluid velocity through the perforation. BALL VELOCITY The final, or stable, velocity of the ball is the sum of the actual fall velocity and the fluid velocity. This will be

By Franklin R. Carpenter

Pyritic smelting, so-called, as practiced in the Black Hills is pyritic smelting only in the sense that Dr. John Percy uses the expression in his " Metallurgy of Silver," where he describes a process for smelting dry silver-ores in connection with iron pyrites, to form a regulus. The ores treated by this process in the Black Hills are very siliceous, averaging about 74 per cent. of silica, from 10 to 20 of iron oxide, 4 or 5 of alumina, and from 2 to 4 of lime. In 1889, while Dean of the South Dakota School of Mines, I took up the question of their smelting. There were neither copper- nor lead-ores in the Hills; hence pyrite and pyrrhotite, of which there are large deposits, were employed to form a regulus. This mixture of pyrite and pyrrhotite, besides being absolutely barren of gold and silver, carried an average of 30 per cent. of silica. The only basic material available as a flux for the great excess of silica in the ores and in the pyrite was a dolomitic limestone. Moreover, the local coke gave 24 per cent. of ash, 60 per cent. of which was silica—as unpromising a set of conditions as can well be imagined. We had before us the examples of Mr. W. Lawrence Austin, of this Institute, who had experimented at Toston, Montana,"

Jan 1, 1901

By V. E. McKelvey

The Phosphoria formation of the northwestern states presents a stimulating challenge to workers in every field of mineral technology. In addition to its large reserves of phosphate, the formation has been found to contain important amounts of fluorine and several metals, such as vanadium, nickel, and molybdenum. Because these minor metals in the Phosphoria do not have their usual glitter, concentrations of them are not easily discovered nor appraised. Like the phosphate itself, production of these metals very likely can be achieved only through use of costly chemical methods, for their mineralogy precludes treatment by the usual methods. In addition, in much of the area the containing rocks lie in complexly folded and faulted structures, which complicate mining and increase its cost. Yet the chain of research necessary to establish what elements are present; their geographic and stratigraphic distribution and reserves; the most suitable methods for recovering them; the combination of beds which, when ruined and processed, will yield the greatest recovery of the most valuable elements; and the methods most adaptable to their profitable extraction may well lead to the development of an important mineral industry and may make possible a significaut reduction in the cost of fertilizer this in itself would be an achievement of momentous importance—and at the same time make the nation more self-sustaining in critical materials. Although this research has great

Jan 1, 1950

By Gerhard Derge

A series of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.' There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. Experimental Procedure The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938

By Gerhard Derge

A series of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.' There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. Experimental Procedure The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938