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THE record of the development of physical metallurgy since the founding of this Institute embraces by far the greater part of physical metallurgy as this subject is recognized today. Yet it is not to be supposed that the metallurgist interested in the properties and behavior of solid metals at the beginning of this period was without important and even fundamental information. He had an empirical knowledge of the behavior of solid metals which extended backward into prehistoric times and he had the early beginnings of many of the chapters in the science of metals. Industry was burgeoning in many directions, for methods had been developed, especially in the manufacture of steel that provided materials in extremely large tonnages, permitting applications of metallic materials on a very widespread scale. These multitudinous new uses of metals created an increased interest in the behavior of metals, and provided the basis for the rapid development of a science of metals. Indeed, the development of science generally that accompanied the industrial revolution reached a flood tide toward the end of the century, furnishing the metallurgist basic principles in chemistry, physics, mechanics, and crystallography that would shortly be extensively applied to metallic behavior. In this account, the early developments in the wide metallurgical field will be traced, in order that the status of physical metallurgy in 1871, when this Institute was founded, may be clearly seen. The subject of metallurgy in antiquity has been written upon frequently and at length. We shall here no more than indicate the main features that we need to define the position in 1871 and to provide a proper background for discussing subsequent developments. The writings of Pliny,1 23-79 A.D., to which Robex-ts-Austen3 fre-

Jan 1, 1948

By G. Derge

The chemical and physical propertties of slag systems are of special interest to metallurgists, for nearly all metals are in contact with molten slags during the primary reduction from their ores and then during the subsequent refining and alloying processes that determine their ultimate use. These processes are carried out at high temperatures and involve such complex chemical systems that funda-mental scientific knowledge of the Properties and behavior of these slags is inadequate. Various hypotheses have been Proposed to explain known slag characteristics. The commonest of these regard the molten slag as constituted of compounds that are dissociated in varying degrees into their constituent oxides, as illustrated by Schenckl and the recent Papers of Chipman and co-authors. Another proposal is that these compounds dissociate by com-plete6 or partial ionization, the evidence for which has been reviewed by Martin and Derge.? whatever hypothesis is favored, the exact formulation of these compounds is incomplete. It is based on three principal types of information: 1. Studies of solidified 51% samples by X ray diffraction, petrography, and similar methods that can be used at room temperature. The correlation of this information with the high-temperature properties of the molten slag is uncertain. 2. Studies of slag-metal equilibria, which have the advantage of providing observations on the molten slag at high temperature. However, even these data present problems of interpretation because they require a complete knowledge of the metal phase. 3. Direct measurements of properties of molten slag at the temperature of greatest metallurgical interest. Viscosity, electrical conductivity, specific heats, and similar properties have been measured, but the data of this type are widely scattered and frequently difficult to interpret. Additional direct measurements of properties of molten slag that can be interpreted in terms of chemical behavior are required, and this paper shows that the standard physical-chemical measurement of reversible electrode potentials, which measure the activity of specific constituents, is a fruitful source of such information. The purpose of this investigation, therefore, was to find an electrode combination that would yield reversible electromotive force measurements when dipped into the molten slag to be studied. Slags of the systems cao-sio2 and cao-120,-SiO2 were chosen for study because graphite containers could be used and the data could be correlated with those for viscosity, conductivity, and other proper-

Jan 1, 1948

By F. W. Gray

Summarized Foreword This paper is one of a series arranged by Institute Divisional Committees for the Fiftieth Anniversary Meeting, reviewing the experience of the major mining and metallurgical industries during the life of the Institute. The viewpoint is national and broadly technical. Geology is stressed on a continental scale without regard for provincial boundaries. The boundary between Canada and the United States is, however, so decisive a factor in our coal-mining economics and our political evolution that mention of its implications cannot be avoided. The Laurentian Shield in Canada makes the occurrence of coal deposits a geological impossibility between the St. Lawrence Lowlands and the Great Plains. All but five per cent of Canadian coal resources occur west of Winnipeg. The utilization of this ninety-five per cent of our coal wealth has to date been a consequence of transcontinental railways' development, and the small fuel needs of thinly populated wheat farming and cattle-raising territory, in what- to judge from the development of mixed farming and greater population density of Manitoba- is merely an initial stage of agricultural intensification and accordant population growth. There is no useful purpose in measuring coal resource against consumption rate in the West as a whole, because the resource is but partially known, and it is difficult to believe that industrialism based upon coal utilization is in any but its infant stage of growth. Canada west of Winnipeg possesses, moreover resources of petroleum and natural gas, which, together with the power-potential in the long watershed of the eastern slope of the Rocky mountains, give to population centres such as Calgary and Edmonton a choice of energy resources that is almost an embarrass des riches.

Jan 1, 1948

By Yves Dardel

INTRODUCTION SINCE the first determination of Dumas1 in 1880, many authors have tried to measure the solubility of hydrogen in solid aluminum, or at least the amount of dissolved gas in it. However, the interpretation of the results which have been obtained is still difficult. Sieverts,2 then Baukloh and Oesterlen,3 during their gassing experiments could not determine any solubility of hydrogen in solid aluminum. On the other hand, Portevin, Chaudron and Moreau,4 leaving the determination of the hydrogen solubility beyond the scope of their experiments, measured only the amount of gas that they could extract by high voltage positive ion bombardment and found up to 151 cm3 of gas per 100 g of metal. Winterhager,5 by repeated vacuum extraction during severe cold rolling, extracted up to 161 cm3 per 100 g. In both series of experiments, the extracted gas contained chiefly hydrogen with a small amount of nitrogen, carbon monoxide, carbon dioxide and methan. Later, Schmidt and von Schweinitz6 as well as Chaudron and Moreau7 showed the importance of the adsorbed layer of hydrogen, the extracted quantities being proportional to the surface and not to the weight of the sample, when its cleaning was not perfect. In earlier experiments, Steinhauser8 extracted from more massive samples nothing but a little amount (< 0. 5 cm3 per 100 g) of hydrogen, carbon monoxide and methane. Thus, according to these experiments the quantity of dissolved gas is probably very small and the effect of the surface could falsify the results of the extraction. However, owing to the care taken by Chaudron and his coworkers, it was clear that all the hydrogen extracted could not come from the superficial layer, or that the links which bound hydrogen to the surface were so strong that the usual method of cleaning could not destroy them. After the main parts of the experiments reported here had already been carried out, Eborall and Ransley9 published the results which they obtained with an analysor having an accuracy of 0.03 cm3 per 100 g, while that of the usual apparatus was only about 0.2 cm3 per 100 g. During all their experiments the adsorbed layer would have been a difficulty, for the value of the adsorbed hydrogen was approximately equal to that of the dissolved amount. [ ] Since always keeping the same adsorbed layer is very difficult, an error in the correction for the adsorption can be made when using the apparatus of Eborall and Ransley, as well as the earlier apparatus,

Jan 1, 1948

By Clarence E. Sims, Donald W. Williams, George A. Moore

INTRODUCTION DURING the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders&apos; Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity. In order that these investigations might proceed on a quantitative basis, hydrogen analyses of a precision considerably higher than any previously reported in the literature were necessary. The method chosen was selected entirely on the basis that it had the highest probability of freedom from uncontrollable errors and will be described in detail in another publication.1 Briefly, the method used consisted of the hot extraction of solid pieces of steel weighing from 45 to 50 g in a highly evacuated quartz tube maintained at 1050°C (1925°F) for a period 0f approximately 40 hr. The greatest precautions were taken to eliminate blanks and insure a sound gas-collection system. Vacuum and temperature conditions were maintained automatically. Mercury-filled risers were used for the introduction of samples in order that the system could be degassed thoroughly in

Jan 1, 1948

By W. H. Echols

An oil-emulsion mud, consisting of a mixture of oil-base mud and bentonitic water-base mud, has been used experimentally in drilling 8 of the 35 wells in the Sivells Bend field, Cooke County, Texas. Experience indicates the oil-emulsion mud can be controlled in much the same manner as a water-base mud, and the "drilling" functions of the two types of mud are comparable. The average water-loss for the oil-emulsion mud was 3.8 cu cm per well. When using oil-emulsion mud to drill the last 2000 ft of 7000 ft wells, the mud costs were approximately 2½ times that of water-base mud. There is nothing to indicate well productivities have been affected through the use of oil-emulsion mud. However, drilling time and bit footages were increased and the holes were maintained more closely to bit guage. The apparent advantages gained through the use of oil-emulsion mud in the Sivells Bend field do not appear to justify the increase in mud costs. Introduction until a comparatively few years ago most of the development of drilling mud was directed toward improving the functions of the mud as related to actual drilling operations. The industry has long recognized that one disadvantage of rotary drilling over cable-tool drilling is the possibility of injury to producing zones through the blocking effect resulting from the infiltration of water or mud into the sands. Recognizing this disadvantage, considerable attention has been diverted toward the development of muds that will improve the quality of well com-pletions through the reduction or elimination of water into the sands, but without sacrificing too many of their "drilling" functions and at a cost commensurate with the benefits derived from their use. This phase of mud research has already found practical application, for example, in the development of the Rangely field, Colorado, it appears the use of oil-base mud during drilling-in operations will contribute appreciably toward making this exploitation more profitable. Much of the discussion to follow will be better understood if a brief sketch of the Sivells Bend field is given. The Sivells Bend field, discovered by The Texas Co. in 1944 and still in the process of development, is in a large bend on the Texas side of the Red River about 85 miles north of Dallas. Geologically, the structure is an unsymmetrical anticline, with faulting having contributed to its development. The productive sands are of the Strawn series of Pennsylvanian age, the sands being lenticular in character and varying considerably in development from well to well. At Present there are 35 producing wells in the field, producing from seven different sand lenses. The productive sand lenses vary from 15 to 50 ft in thickness and the individual sands have average permeabilities of from 75 to 375 md. The presently productive sands are encountered at depths of from 6300 to 7300 ft, but testing has indicated that commercial production might be obtained from other sands as high as 5200 ft. Histories of older Strawn

Jan 1, 1948

By W. A. Koehler, M. E. Hinkle

INTRODUCTION THE oxidation of pyrites and marcasite in coal-mine strata to produce discolored acid mine drainage has long been explained by chemical reactions occurring in three stages: I. The iron sulphide minerals are oxidized by air in the presence of water to produce a nearly colorless solution of fer¬rous (iron) sulphate and some sulphuric acid. 2. The ferrous sulphate and part of the sulphuric acid combine with additional oxygen to form ferric (iron) sulphate. 3. The ferric sulphate hydrolyzes to form a reddish-brown precipitate and additional sulphuric acid. Nevertheless, chemical data alone are not sufficient to explain all observed facts. The first stage seems to proceed more slowly in the chemical laboratory than in nature. The second and third stages nor¬mally occur to a marked extent within a few days with raw mine water. However, the visible discoloration that characterizes these latter stages will not develop for months if the mine water is sterilized. By means of bacteriological techniques, two organisms have been isolated from acid coal-mine drainage. These are believed to have a part in promoting the chemical reactions summarized above. One organism is considered to be Thio¬bacillus thiooxidans, which is known to be able to convert elementary sulphur or sodium thiosulphate to sulphuric acid. Its relation to the formation of acid mine drainage has not yet been established. Apparently it does not promote the oxida¬tion of ferrous iron compounds in mine, drainage to the ferric state. The second organism has not been identi¬fied by name but is described as "Gram negative, non-spore-forming rods approxi¬mately 0.4 micron wide by o.8 to 1.0 micron long." A pure culture of this when added to sterile mine water will cause the latter to become amber and develop the typical rusty precipitate. However, it has not been found to convert sulphur com¬pounds to sulphuric acid. Further research is planned to determine whether or not these microorganisms play a significant part in the first stage of oxidation whereby pyrites and marcasite minerals go into solution. Some of the conditions found in abandoned sections of coal mines, such as a reduced percentage of oxygen and increased percentage of carbon dioxide in the air, as well as the existing temperature and acidity ranges, will be tolerated by and may even be favorable to these organisms. ACID COAL MINE DRAINAGE Acid coal mine drainage has been the concern of coal mine operators, industrial¬ists, sportsmen and public officials for many years. The amount of acid flowing into our streams in the coal-producing areas varies considerably from mine to mine and from

Jan 1, 1948

By John Wulff, Robert Kamm, M. A. Steinberg

IN a previous paper1 from this laboratory, the development of a lead grid method for exploring the distribution of strain and density within metal powder compacts was described, In that work thin lead foil with rectangular holes cut at regular intervals was inserted with the powder fill, the arrangement pressed and then radiographed to permit measurement of the deformation of the lead grid. Densities at each grid element obtained in this manner were plotted as a function of the die dimensions. From such plots it was, found that the densest part of a compact pressed from one side (the top) is at the top outer region and the least dense at the bottom outer region -of the specimen. The axial density maximum occurs more often nearer the bottom than at the top. As a result of such exploratory measurements, it appeared reasonable to conclude that variations in density could be attributed in the main to die wall friction. Thus compacts of large diameter appeared relatively uniform in density except where the die fill had been uneven. Finally it was found that lubrication of the finely finished die cavity contributed more to magnitude and uniformity of density within the compact than interparticle lubrication. Since publication of the above results, it was found that circular-hole grids could be more accurately made and, when deformed within the powder, more readily measured and analyzed. Much of the former work was repeated and new results which include the effect of lubrication, compact height, pressure, speed of pressing and vacuum pressing are reported in the present paper. CIRCULAR-HOLE GRIDS AND ANALYSES OF RADIOGRAPHS Commercial lead sheet 0.008 in. in thickness was used in all the work reported. The 0.0938-in. diam holes were punched in the sheet on 1/8-in, centers to an accuracy of 0.001 in. The finished grid used contained eight or more holes in a row and from I to 24 rows. The lead sheet was clamped between two pairs of brass strips bolted to a small milling machine table which was itself bolted to a bench in correct position near a vise which held the punch. Travel of the lead grid in two dimensions was controlled by two steel lead screws calibrated in 0.001-in. divisions. A stripper plate was used on the punch to avoid distortion of the lead foil. A high carbon-high chromium (chrocar) one-piece steel die was used throughout the work. The die cavity was 1,125 in. in diam and the clearance between plungers and die wall was 0.001 in, The die was also used for pressing from both ends with two long plungers. Finally, lapping of die and plungers gave a surface whose rms value on an Abbot profilometer was 5 micro-in. The die walls and plungers were, except where otherwise noted, lubricated with a stearic acid suspension in benzene. This was put on in multiple layers and allowed to dry before filling the die.

Jan 1, 1948

By Edward Saibel

The object of this study is to investigate the effect of prior tensile strain on the fracture stress of a metal. This is done in a theoretical manner starting from the point of view developed by the author in his thermodynamic theory of the fracture of metals. The results are compared with experimental findings and a rational interpretation is given to work that shows the variation of fracture stress with prior tensile strain. Theory op Fracture In the thermodynamic theory of the fracture of metals developed earlier,&apos; it was shown that a critical strain energy per unit volume exists. This is characteristic of the material and may be calculated from basic thermodynamic data. When the area under the flow curve reaches this characteristic value, fracture occurs. The general criterion for fracture is expressed in the form « ± u. = JLJW/V [r] where L, is the latent heat of melting of the unit volume, AV/V is the ratio of the change in volume of the unit volume to the original unit volume on passing from the solid to the liquid state, uo is an initial energy density, and J is a conversion factor, which changes energy from heat to mechanical units. As a first approximation, it will he assumed that the stress-strain curve is the straight line that extends from the point of maximum load onward, extrapolated back to the axis of zero strain, for example, line AC of Fig. I. If the point of intersection of the straight line with the axis of zero strain is represented by v., and the slope of the straight line is p, the analytic form of the flow curve is a = (To + pd [2] and the strain energy per unit volume evaluated from Jud6 becomes (u,6 + pa2/2). When this latter term reaches the critical value JLbVIV (designated hereafter by M), it is assumed that fracture occurs. This leads to the following expression for the fracture stress: a; = V«r.2 + iMp [3] The strain at fracture may be calculated from Eqs 2 and 3. It is assumed in this paper that the initial energy density is either zero or that it may be neglected. Furthermore, the complicated states of stress and of strain existing in the necked region of the tensile specimen after "necking" has occurred will also be neglected for the present, so that average conditions will be assumed to prevail. Flow and Fracture Curves LudwigZ attributed to materials two fundamental properties: (I) a resistance to flow and (2) a resistance to fracture. He reasoned that at each instant the

Jan 1, 1948

By V. H. Gottschalk

Sponge iron is a product resulting from the reduction of an iron oxide below the temperature at which the product melts. Commercial grades usually contain 80 to 95 percent metallic iron, 2 to 5 percent unreduced iron oxide, and an amount of siliceous gangue material depending on the pur.ity of the are used for reduction. The reducing agent may be gaseous or solid, and a large variety of procedures have been proposed for bringing the reducing agent into reaction with the iron oxide. Of the proposed procedures, the one that has the distinction of having been in continuous commercial operation for the longest time, from 1911 to date, was developed at a ceramic plant in Hoeganaes, Sweden, and yields? a product that has an enviable reputation as furnace feed wherever special, high-quality steels are made.

Jan 1, 1948

By R. E. Ricksecker, W. M. Baldwin, R. McC. Baker

INTRODUCTION THE development of residual stress in strip during rolling has not been systematically studied. A few scattered papers1-3 mention the existence of residual stresses in rolled strip or touch upon some of their consequences,4 but there is no report of experimental studies in the literature describing the effect of roll diameter, strip thickness, reduction per pass, metal or metal temper on the magnitude of residual stresses developed in strip. A knowledge of the effect of these factors is of utmost importance since the present trend in some mills to roll thicker castings brings the rolling operation directly into that set of conditions which, as will be brought out in the present paper, can develop residual stresses of a high order of magnitude. Fundamentally, residual stresses are developed when a metal is inhomogeneously unloaded from a plastic stress state. A quantitative treatment of the problem requires a reasonably complete understanding of both the plastic stress state existing in the metal during deformation and the elastic stress state that would exist in the metal if the metal deformed as a perfectly elastic body. Our knowledge of either state during rolling is so meager that we can make no more than certain limited predictions. The external stress state* operating between the roll and the metal consists of compressive stresses acting almost perpendicularly to the strip surface but vary [ ] ing in intensity both across the width of the strip and along the length of contact between the roll and the strip. An example of such a stress distribution is shown in Fig I. The nature of the internal stress state, produced by this distribution, is not known. Various investigators,5-7 however, have felt that a qualitative similarity must exist between the internal stress state so produced and that produced in a wide strip that is compressed between two flat-nosed punches. In the latter case the external stress state is represented by a uniformly distributed compressive stress acting perpendicularly over the face of the tool. The elastic internal stress state in this case is complex-the principal stresses showing

Jan 1, 1948

By Louis C. Brichta

The Capital Mine is one of, the more important zinc mines in Lawrence County, Mo. Owing to the urgent need for additional zinc during the war and the available facilities for the treatment of zinc-lead ores at the property, the Bureau of Mines examined the mine during July and August 1942 and selected it for further investigation by churn drilling, which was accomplished in the fall of 1943 and spring of 1944. At the conclusion of the drilling on the Capital holdings, the Greenland property, immediately south, was investigated by drilling two additional holes. Results of the investigation are presented in this report.

Jan 1, 1948

By O. W. Terry

The Skene mine, in the Elizabeth District, Illinois, produced lead are from 1901 to 1907. Three exploratory holes drilled just north of the mine were said to have penetrated 40 feet of good zinc are. During the summer of 1944, the Bureau of Mines drilled check holes close to what appeared to be two of the three old holes. They also drilled two holes to the south of the mine and one into the core of the deposit. Results of the investigation are given in this report.

Jan 1, 1948

By George Langford

Introduction The fiftieth anniversary is, for an individual or a society, an appropriate time for a review of the past so that events and experiences may be viewed m perspective, and thereby serve as a useful guide to the future. In this review of mining geology it is proposed to set forth the situation as it was when the Institute was founded, and then trace the developments during three appropriate periods-the first from 1898 to 1918 the second from 1919 to 1939 and the third from 1939 to 1948. Mining activities were widespread in Canada in 1898 and some of the operations were considered large for their day. The total value of the metals produced in that year was $21,705,854, and in the case of five metals the output had a value in excess of one million dollars. In order of importance these were gold, silver, copper, nickel, and lead. The important producing areas were ova Scotia, Quebec, Ontario British Columbia, and Yukon. This diversification of the mining areas and the metals produced created an interest in mining throughout Canada, and was an important factor in making Canadians conscious of their mining industry. In the year 1898 geology was a recognized science. The principles of physical geology were well known, but the same cannot be said of economic geology and structural geology. Ore deposits and their occurrence had been studied chiefly in Europe. A great many important observations had been made but the theories linking these facts together were still m a formative stage. The same condition was true of structural geology. These two branches of geological science which are so important in what is now called &apos;mining geology&apos;, had not progressed far enough to be of practical assistance mining operations. For this reason, geologists were regarded as dreamers in ivory towers-a concept chat still lingers in the minds of those who have not kept abreast of the growth of the science.

Jan 1, 1948

By George D. Dub

Owens Lake is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.-2H2O) and borax, (Na2B4O7.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. Closed Basins Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride, brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I. Chloride type; largely sodium chloride (NaC1) and of oceanic type, such as Great Salt Lake. Related is -the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. a. Sulphate type; largely sodium sulphate (Na2SO4) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate—chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate—Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1948

Recovery of gold by smelting zinc dust concentrate has been carried on at Lake View and Star, Ltd., since July, 1930, when the Merrill-Crowe precipitation plant was first put into operation.Part I describes the development of current gold-room practice, commencing with the clean-up of the MerrillCrowe plant, a procedure that has not materially changed since its inception, and then shows how modifications to straight roasting and smelting became necessary, following a gradual increase in the copper content of the ore treated by the mill.Present smelting practice converts most of the copper into a mixed copper-lead matte, thE sulphur being supplied by the addition of flotation concentrates containing about 35% sulphur as pyrite. The process yields gold bullion of a sufficiently high grade to send to the Royal Mint, but until 1943, suffered from the disadvantage of giving matte and slag by-products high in gold and silver, that were not recovered directly but had to be sent to a smelter.Part Il gives details, of experimental work cnrried out since 1943 which led .to a process for the satisfactory and economic recovery of not only the gold and silver, but also the copper from these, hitherto, troublesome by-products. Nevertheless, incidence of matte in a smelt has always been considered undesirable, and it is hoped that eventually it will be obviated by removing most of the copper from the zinc slime before smelting.Part III indicates the methods by which this might be achieved, and outlines the experimental work that has been done up to the present.

Jan 1, 1948

By J. B. Cunningham

Lithium in the form of metal, salts, and alloys is particularly important because of increasing industrial uses resulting partly from wartime developments. Lithium carbonate and lithium strontium nitrate, which impart a brilliant red color to a flame, are used in pyrotechnics. Lithium chloride and fluoride are used in fluxes for welding aluminum to dissolve the oxide coating on the aluminum and prevent oxidation of the molten metal. Lithium carbonate is used in ceramics in raw alkaline glazes because of its unusual fluxing properties. The use of 9 to 12 percent lithium carbonate permits a marked increase in the amounts of alumina, calcium, and silica that may be Used and results in a more stable glaze with sufficient alkalinity to produce vivid copper blues and other typically alkaline colors. Lithium stearate is used as a grease in airplane engines because of its ability to withstand wide changes in temperature. In view of its great affinity for nitrogen, hydrogen, oxygen, sulfur, phosphorus, carbon, and silicon, lithium has an excellent scavenging action on molten metals. It forms stable nonmetallic compounds of low specific gravity or gases that are eliminated at pouring temperatures. Lithium is generally added to the melt in the form of a lithium-calcium alloy consisting of 50 percent of each ingredient or as an alloy of 98 percent copper and 2 percent lithium. The lithium-calcium alloy added to cast iron before pouring, acts as a scavenger and increases the fluidity of the melt. This alloy also is said to increase the corrosion-resistant properties of stainless steel alloys and to improve their polishing qualities.

Jan 1, 1948

By Richard M. Foose

Five miles southwest of Mt. Holly Springs, Cumberland County, Pennsylvania, the Philadelphia Clay Co. has been mining and milling a white clay since 1896; for use in white cement, as a filler in rubber, pigment and paper, in the manufacture of insecticides, and for other minor purposes. Until late in 1942, when the mine was abandoned because of labor shortage, combined underground mining and surface stripping produced approximately 30,000 tons of clay a year, of which 10,000 tons were refined in the mill. Geology Lower Cambrian Antietam quartzite and the Rilontalto quartzite, stratigraphi-cally older, trend N.55°E. and make a sharp 1600-ft. anticlinal ridge of the South Mountains. The Tomstown dolomite overlies the Antietam quartzite on the southeast flank of the anticline, which is displaced near its crest by a steeply dipping oblique fault. Erosion of the less resistant Tomstown formation has resulted in a narrow valley at an elevation of 700 ft. Directly on top of the Antietam quartzite and at the base of the Tomstown formation is a zone of sandy white clay, lenticular along the strike of the formations, ranging in thickness from 10 to 300 ft. within a mile. All of the formations dip steeply to the southeast, from 65" to vertical. The clay crops out at an elevation of about 1000 feet. Origin and Character The uppermost part of the Antietam formation is sericitic and schistose at many places, and at all these places weathering is in an advanced stage. The clay is the residual product of weathering of this sericitic quartzite or sandy schist. The crude clay has the physical aspect of a sandy kaolin, but there Are large areas in the clay formation that are low in free silica, and commonly the 30 ft. adjacent to the Antietam quartzite is notably free of silica. The overlying Tomstown dolomite has been weathered almost completely to a mixed yellow and brown clay, which carries a zone of nodular and chunky limonite and manganese ore, 4 to 12 ft. thick, about loo ft. from the contact with the white clay. In mining, this zone is an important "marker," indicating where the white clay may be expected in an advancing tunnel. The contact of the white clay formation with the yellow and brown clay of the Tomstown formation is relatively sharp, although the line of contact is irregular and therefore responsible for the lenticular character of the white clay formation. Following is an analysis of the refined clay containing less than one per cent of moisture when dried at 212°F.: SiO2, 67.05 per cent; Al2O3, 22.27; Fe2O3, 0.40; CaO, 0.00; TiO2, 1.05; MgO, 0.52; Na20, 0.04; K2O, 0.88; ignition loss, 7.65; total, 99.86.

Jan 1, 1948

By C. S. Barrett, O. R. Trautz

PREVIOUS investigations have shown that lithium is body-centered cubic from near its melting point to the temperature of liquid air1,2,3 Nevertheless there was an incentive to search again for a transformation at low temperatures: C. Zener4,5 has remarked that the low value of the elastic modulus (11 - C12)/2 of body-centered cubic metals and alloys implies a rapid increase in free energy with decreasing temperature, which would favor the occurrence of a transformation; also the shear movement to which this modulus applies is one that can transform a body-centered cubic structure into a slightly distorted face-centered cubic structure. It was confirmed that lithium does not transform spontaneously at liquid nitrogen temperature, but it was found that a transformation can be induced at this temperature by cold working the metal,6 and at slightly lower temperatures a different transformation occurs spontaneously. Transformations were also found in solid solutions of magnesium in lithium. THE NATURE OF THE TRANSFORMATIONS Before presenting a detailed treatment of the technique used and the specific data obtained, it would be well to give a brief survey of the general characteristics of the transformations. A new crystal structure begins to form spontaneously in a specimen when it is cooled below a critical temperature. In lithium the structure appears to be close-packed hexagonal; in the Li-Mg alloys most of the diffraction lines (but not all) are near those for hexagonal lithium. The transformation proceeds as the temperature is lowered and soon stops if the temperature is held constant or raised. The course of the transformation on cooling is indicated by the curve at the lower left of Fig I. This curve is drawn in stepped fashion because the transformation goes by discrete steps with audible clicks. Because of the similarity to the decomposition of austenite into martensite in steels, it seems appropriate to designate the beginning of the spontaneous transformation on cooling as the Ms point. On heating to room temperature after the low temperature treatment only the usual BCC structure is found. On heating, the low temperature modification begins to disappear at a temperature which will be designated as Ac. The transformation on heating is halted when the rise in temperature is halted. The temperature must be raised 40 to 50°C above Ac before the reversion is complete-an interval which is sensitive to the rate of heating and to the time of holding at temperatures above Ac. This behavior on heating thus has similarities also to the formation of martensite in the cooling of steels.

Jan 1, 1948

By William D. Manly, John Towers, Paul A. Beck

RECENT work on grain growth in high purity aluminum and in a solid solution type alloy of aluminum and magnesium&apos; showed that the isothermal increase of the average grain diameter D with time follows the equation [D = K(to + A)-Eq I] Here [to] is that portion of the total annealing time [t], which is available for grain growth, i.e. the annealing time less the time necessary for complete recrystallization. The parameters A and n depend only on the temperature. A has the dimension of time, and is usually of the same order of magnitude as the time for recrystallization: R. In some instances R may be substituted for A in Eq I. This is the case for example at long periods of annealing or at high temperatures, where both A and R become small in comparison with t. In such instances Eq I is simplified to [D-K-tnEq2] For high purity aluminum the exponent n increases in the ratio of about 1 to 5 in the temperature range of 350° to 600°C. 70-30 brass has been long known to exhibit grain growth of the continuous type, such as occurs in pure metals. For this reason, it was of interest to determine whether grain growth in brass also follows Eq I and 2 as it does in aluminum. Isothermal grain growth data for 70-30 brass were published in recent years by R. S. French2 and by H. L. Walker3 Fig I shows a log D vs. log t plot of French&apos;s data, together with the 500, 600 and 100°C data by Walker for 42.8 pct reduction by rolling. In such a log D vs. log t plot Eq 2 corresponds to a straight line with a slope of n. As seen in Fig I, the data of French and the 600°C data of Walker can be represented by straight lines. However, the 500 and 700°C data of Walker give curved lines and the average slope of his 500°C line is very different from the slope of the line representing French&apos;s data for the same temperature. Furthermore the curvature of the 700°C line suggests a tendency for grain growth to stop after 8 hr. If confirmed, this would constitute a definite deviation from Eq 2, not explainable on the basis of the specimen thickness effect found in high purity aluminum.1 Walker&apos;s specimens were 0.125 in., i.e. 3.18 mm thick, while the deviation occurs at a grain size of approximately 0.4 mm. A further point of divergence arose recently, when J. E. Burke suggested4 on the basis of Walker&apos;s data, that, instead of Eq 2, grain growth in 70-30 brass follows the equation [D-D. =K• t,Eq3] Here D, is the grain size as recrystallized at the temperature in question. Although it was possible to show5 that, for pure aluminum, for which isothermal grain growth has been carefully investigated, Eq 3 is incompatible with the experimental facts, the situation remained somewhat obscure with respect to 70-30 brass. In view of the discrepancies between the

Jan 1, 1948