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By Robert Adams

Secondary or scrap materials appear at all stages in the industrial process and in a bewildering variety of forms, grades, and values. It is useful to begin analyzing them by dividing the broad concept of "Secondary Supply" into three parts First, the concept must encompass the stock, or pool, of secondary materials. In the process of satisfying his wants, man produces desired products from the materials and natural resources found around him. As long as the rate of production is greater than the rate of obsolescence of a given product, the total stock or pool of materials embodied in that product will increase in size This stock concept relating to secondary materials is directly analogous to the "resource" concept used for primary raw materials in the preceding chapter, and includes all materials embodied in existing products (Obviously, this excludes those materials which are destroyed in the consumption process, viz , fuel oil burned to provide heat.) Consumption of a primary material in a productive process tends to reduce the resource base of that primary material In direct contrast, however, the production or use of products increases the resource base of the secondary material. Thus, we find that a country which has no resource of a primary material can, by importing products that contain the material, build up a large enough stock to provide a basis for secondary recovery. The estimated growth of the pool of copper in use in the United States through 1967 is shown in Table 5.B.1.a The estimate of 39 3 million tons at the end of 1967 includes only technologically recoverable copper and is, therefore, somewhat less than the stock concept described previously, which does not distinguish between recoverable and unrecoverable material. Nevertheless, Table 5 B.1 does give an idea of how a nation's secondary resource of a material can grow over the years. A second aspect of the concept of secondary supply is the generation of secondary materials. This includes materials generated as scrap in production as well as the movement of a material out of the stock of existing products via wear, damage, or obsolescence The quantity of materials generated is usually either nearly or completely independent of the technologic capabilities and economic forces which prevail in the secondary recovery market.b The justifications for and the qualifications to this statement are considered later. The final aspect of the concept of secondary supply consists in the secondary recovery process It is at this point that the technologic and economic forces of the secondary recovery market become the controlling fac-

Jan 1, 1976

By C. H. Li, R. J. Stokes, T. L. Johnson

The effect of alumina particles on the nucleation and growth of cracks through a silver- chloride matrzx has been investigated. It has been found possible to promote fibrous cracking in dispersion-strengthened silver, chloride under notch-impact conditions at temperatures at which silver chloride alone cleaves brittlely The modification) of fracture beIzavzor is thought to be due to the relaxation of hydrostatrc stress beneath a notch by the nucleation of cavities near alumina particles. In recent years, composite or dispersion-strengthened materials have been studied primarily to understand their high resistance to plastic flow particularly at elevated temperatures. Dislocation models have been developed with which it is possible to deduce with fair success the effects of interparticle distance, particle size, temperature, upon yielding and creep behavior.l-4 Much less attention has been paid to the fracture behavior of these materials (with the notable exception of common structural steels) and little is known experimentally about the manner in which inclusions affect the nucleation and growth of cracks through a matrix. Nevertheless a beginning has been made in connection with fibrous cracking in ductile matrices where inclusions appear to play an essential ro1e.5-7 During the severe localized plastic deformation which accompanies necking in a tensile test, cavities are believed to develop at inclusions; these cavities subsequently grow and coalesce by plastic flow until separation is complete. It is of interest to consider whether inclusions can affect fracture behavior under loading conditions which restrict the plasticity of the matrix itself (for example, cleavage under conditions of a high imposed strain rate at low temperatures). It is particularly interesting to study these effects in a solid which shows a spectrum of behavior ranging from fully ductile to semi-brittle behavior. Such a solid is silver chloride whose mechanical behavior depends sensitively upon temperature and strain rate.'," The present paper is concerned with a study of the influence of inclusions (in the form of alumina particles) on the fracture behavior of silver chloride loaded uniaxially at low strain rates at room temper- ature and also under notch impact conditions over a wide range of temperature. In particular, it will be shown that the alumina particles can exert a startling effect on the ductile-brittle transition temperature of notched silver chloride and that the magnitude and nature of the effect depends upon both the quantity of alumina and the shape of the alumina particles. 1. EXPERIMENTAL PROCEDURE 1.1 Materials Used. Silver chloride powder of analytical reagent (AR) quality having an average particle size 6 was supplied by the Mallinckrodt Chemical Works (st. Louis, MO.). Acid washed 900 mesh alumina powder, designated A38-900, was supplied by the Norton Co. (Cambridge, Mass.). This powder was added to silver chloride in two forms: a) the as-received condition in which the individual particles were of random irregular shape; their statistical average size was 7; b) in a condition in which each particle was spherically shaped by a fusion technique. In this case, the statistical average particle size determined with the optical microscope was approximately the same (about 5p) but electron micrographic evidence indicated that many ultra fine particles were present in the spheroidized powder. 1.2 Preparation of Composite Materials. Silver chloride-alumina composites containing 2.5, 5, and 15 pct by volume of alumina were produced by the extrusion of mechanically mixed powders blended in a ball mill for 24 hr at room temperature. The mixtures were compacted at 50,000 psi at room temperature in the form of billets 3/4 in. in diameter and 1 in. long which were then extruded with a 16:l reduction ratio at 370°C through a radius-type steel die having a 5 deg lead-in angle. An extrusion temperature of 370°C was selected to ensure that all composites had sufficient plasticity to be extruded. Apart from this general requirement, the choice was arbitrary. 1.3 Microstructure of Composites. Attempts were made to check the distribution of alumina metallo-graphically by polishing transverse and longitudinal sections of the extruded rod. Specimens were wet-ground to 600 emery paper and lapped successively with 5 and 0.25-p grades of diamond paste. They were etched for 10 sec in 10 pct sodium thiosulfate solution and lightly polished in concentrated ammonium hydroxide. The most effective way to render the alumina particles and grain boundaries visible was to radiate the surface with intense white light to decorate the grain boundaries and the particle-matrix interfaces photolytically.

Jan 1, 1962

By G. Sachs

THE iron-rich iron-nickel alloys have at-tracted considerable academic interest in recent years. The carbon-free alloys are of minor practical importance, but they are Atomic per cent nickel FIG. I. FIG. 2. FIG, I.-HONDA'S AND MERICA's IRON-NICKEL DIAGRAM, FIG. 2.-MARSH'S IRON-NICKEL CONSTITU-TIONAL DIAGRAM. the base of many alloys with various out-standing properties. The iron-nickel alloys, therefore, have been investigated exten-sively regarding both their structures and their properties. The researches on these alloys up to 1938 have been collected and critically reviewed by J. S. Marsh,1 and will be discussed in some detail in the sec-tions of this paper dealing with specific subjects. These numerous investigations have not succeeded in establishing the equilibrium conditions in this system. Alloys containing more than a certain amount of nickel (8 to10 per cent Ni) undergo the allotropic transformation extremely sluggishly, both on heating and cooling, showing a large hysteresis,2 which is not dependent upon

Jan 1, 1940

By S. Maemura

Miike Colliery of Mitsui Coal Mining Company, the biggest and oldest coal mine in Japan, is producing a quarter of the national coal production, about 5.2 million tons of clean coal annually and almost a half of which is now being mined under the "slicing Mining System". The slicing system is a mining method to mine a thick coal seam dividing it into two faces, upper and lower. Its history started nearly 20 years ago. However, the all-around modernization of this system has made little progress up to recent years, while mining methods for single longwall faces has made a remarkable progress together with the improvements in mining machineries, self advancing supports and so on. The reason was that the tremendous difference in adaptabilities of mechanized face equipments existing between the upper and lower faces has made it very difficult to increase the total production capacity of slicing system. After our persistent study for seventeen years, we have recently realized successfully the quite satisfactory slicing system, applying the combination of shield type self advancing supports and double ranging drum cutter at both faces. We are now fully convinced of that the high efficient, quite safe and improved slicing system has been basically established for the present. This paper intends to brief the transition on the combination of self advancing supports and mining machines, its results and further to detail the development of shield type self advancing support for upper face and artificial roof material which shall be the key point to be successful in full mechanization of slicing faces.

Jan 1, 1976

By C. A. Zapffe

BOTH the foundryman and the theoretical metallurgist are now generally agreed that the anomalous "rising" or "bleeding" of certain ferrous castings of killed metal is primarily attributable to hydrogen. How and why the phenomenon occurs, however, have not been made clear. The following discussion is intended to harmonize foundry experience with metallurgical theory so that the foundryman may possibly improve his ability to prognosticate whether a certain casting may bleed or not. BLEEDING, RISING, AND PIPING The "rising" to be discussed here is not to be confused with the action in rimming ingots as a result of the carbon-oxygen reaction, although a conclusion will be drawn that may apply to the art of controlling the rimming action. Only killed metal is considered, which includes both steels and irons. In Fig. I, three killed, chill-cast ingots are shown: a porous ingot whose evolution of gas during late stages of solidification has ejected metal through the top; an ingot in which moderate gas evolution during solidification has lifted the mushy central metal, i.e., it has "risen"; and, third, a sound ingot with good piping characteristics. The first type is referred to as "bleeding," and generally infers that a solid skin had first formed through which the liquid metal later erupted. There is no fundamental distinction between bleeding and rising in reference to killed metal.* POROSITY Hydrogen appears as a cause of bleeding because the gas evolution simultaneously leaves a porosity of a type traceable to hydrogen. Twenty years ago, Melmoth1 noted that killed steel that rose unexpectedly in the mold, if returned while liquid to the furnace and heated further under a reducing lime slag, would again rise in the mold; but that if the ingot were allowed to solidify and was then remelted no rising occurred. A critical quantity of the responsible gas is therefore removed by the rising action. Melmoth associated rising with high silicon (0.7 to 0.9 per cent) and concluded that silicon increased gas absorption. Because silicon is a strong deoxidizer, oxygen must, therefore, be eliminated from consideration of the three common gases in steel-oxygen, nitrogen, and hydrogen. Butterworth2 later decided that pinhole porosity was caused by gases dissolved in the metal and that hydrogen was obtained from steam in the mold. Allen's classical work on copper castings,3 soon followed by

Jan 1, 1942

Jan 1, 1929

By George A. Laird

THIs old and once famous district played, through its enormous production of silver and gold, an important part in the history of the State of San Luis Potosi. According to a pamphlet prepared under the direction of the Governor of the State, Sr. Don Blas Escontria, and presented to the visiting members of the Institute during the Mexican meeting of 1901, this district is situated 20 km. east of the city of San Luis Potosi, in a range of mountains of moderate height, extending 135 km. N. and S., and 16 km. E. and W.; and the mineralized area hitherto developed is about 600,000 sq. m. The history of the district, as given by the record dated 1778, and formerly kept in the Sail Francisco convent, says that it was discovered in 1575 by Sr. Don Pedro Irarte, and adds that the city of San Luis Rey de Francisco de1 Potosi received its name (in allusion to the famous Potosi mines in Bolivia) by reason of the remarkable productiveness of its gold- and silver-mines in the first period of their exploration, during which they paid to the Crown, as quintos (the fifth part of the product), $97,000,000, as appears from the accounts of the royal treasury. The amount of the quintos paid during the " bonanza period " of 80 years was $72,000,000. The larger sum first mentioned probably represents a longer series of years. But either will suffice to indicate the great wealth of the mines. In 1663, the decadence of the industry began with the caving-in of several mines, concerning which the record of 1778, already cited, says, in substance, that on Good Friday one of the owners in the enterprise, in view of the unfavorable prospect of a lawsuit in which he was engaged, set fire to the timbers supporting the underground galleries and workings of the Sail

Jan 1, 1905

By Otto H. Henry, J. J. Cordiano

THOUGH powder metallurgy is one of the oldest of metallurgical processes, it is in its infancy as a branch of the modern field of metallurgy. As early as 3000 B.C., the ancients produced implements and weapons of iron by reducing iron ore in a charcoal fire and forging the resultant sponge while still hot into the desired shape. Melting and casting soon superseded the powder metallurgy practice, and it was not until the turn of the twentieth century that powder metallurgy was applied to the commercial manufacture of tungsten lamp filaments. From this beginning, the use of the powder metallurgy process spread to the manufacture of porous oil-impregnated bearings, cemented carbide tools, contact points, diamond grinding wheels, clutch facings, starter brushes, resin-bonded radio cores, magnets, metallic filters, and other parts. More recently, and particularly during the present war, there has been a definite trend toward the manufacture of machine parts by this process in competition with the more conventional fabricating methods. Notwithstanding these many developments, scientific progress has been slow. While many articles on powder metallurgy have appeared in the press and various publications, there have been too few contributions to our technical societies, with the result that there is a dearth of the type of information necessary for the full development of this science. It is of primary importance that the results of research and development be freely disseminated if powder metallurgy is to realize its fullest potentialities. PURPOSE OF INVESTIGATION Excluding the refractory metal field, all commercial powder metallurgical products made by a cold compressing and sintering operation contain voids. These voids can be substantially eliminated by subsequent severe working and heat-treatment, but such practice has not proved economical in most applications. By applying heat during the compressing operation, plastic deformation of the powder particles is substantially increased, and the resultant compact or briquette is practically free of voids. However, hot-pressing has many attendant problems, which at present preclude its use in the manufacture of precision parts. The more important of these are to devise: I. A die steel capable of withstanding high pressures at elevated temperatures. 2. A high-temperature lubricant capable of preventing excessive die wear and welding of the compact to the die walls. 3. A method of retaining a neutral or reducing atmosphere in the compacting zone of the die assembly. 4. A means of ejecting the hot-pressed specimen into a neutral atmosphere until reasonably cold.

Jan 1, 1945

By J. A. Herrick Nashua

IN this country steel made in a Siemens furnace or Bessemer converter, is generally tapped into a ladle or shoe, and then drawn through an aperture in its base into the various moulds. In order to regulate the flow of the molten mass a refractory valve is arranged at the aperture. A plumbago nozzle is fixed firmly in this aperture, and a stopper of like material is fitted to it, making a socket valve. In order to raise and depress this stopper at will, a rod is fastened-to it, extending through, the metal and over the brim of the ladle, where it is bent back in a half circle and secured in a slide. This slide plays vertically in a frame, permanently fastened to the outside of the ladle, and is moved by a lever having as a fulcrum a pin fixed in this frame, one end, of the lever being temporarily fixed to the slide, and the other end being moved by hand. Reference being had to the drawing (see Plate 1, Fig. 1), E is the nozzle, D is the stopper, A is the rod, protected as hereinafter described, C is the cast-iron framework, B is the wrought-iron slide, B' is the offset into which the rod, A, enters, and is secured in the usual manner by a key, a. Section J, K, shows the manner of hanging the lever. J is a pin attached to the slide by which the end of the lever raises the slide, B. J is the fulcrum fastened to the frame, C. K (Fig. 1) is a hand-nut fastening the slide, B, to the frame, C, at will. Fig. 2 is a side elevation of ladle, showing the outside working of the parts above described. It is the common practice to protect the rod, A, by a coating of clay and fire-sand, kneaded to the right consistency and applied to the rod, and then thoroughly dried. Just before casting, the plumbago stopper, D, is heated at its extremity to redness separate from the ladle and, at the moment of pouring, is placed in the ladle and slide, and adjusted as well as practicable. Some very serious defects ensue, causing much trouble and vexation as well as actual loss. The fire-clay coating in drying becomes cracked and seamy, and at its best is more or less loose on the rod. The hot metal sometimes cuts

Jan 1, 1879

By Hugh O?Neill

IN PREVIOUS papers,1 the author has reported the results of experiments on the straining in tension of a single crystal test piece, about 0.6 in. long, of vacuum-melted electrolytic iron containing 1.8 per cent. of silicon. The crystal was originally in the "as cast" condition, and was stressed slowly along a tetragonal axis so that slipping along conjugate gliding planes finally transformed the original cylindrical portion into a pair of fracture wedges. One of these fracture wedges was sectioned along the stress axis in a plane at right angles to the edge of the wedge. A metallographic study of this plane of -section led to the conclusion that slip had taken place in the (111) direction along (112) planes making a V shape with the stress axis. The present paper describes the results of scratch-hardness tests conducted on the same section, in order to determine the distribution of strain hardness therein, followed by annealing, and considers the resulting variations in hardness. These observations supplement those made by Krivobok2 on similar material reduced 25 per cent. by hammering (i. e., by impact) in the cold. In order to investigate ageing effects, two small crystals of the same alloy were also tested.

Jan 1, 1928

By Henry Louis

IN the discussion on the paper on subsidence by R. V. Norris and H. W. Montz (Teohnical Publication No. 153), H. N. Eavenson has been good enough to quote some of my views regarding the phenomena of subsidence; he has, of course, only mentioned these briefly, and as he has not represented them quite correctly, it is evident that I have failed to make them clear. Seeing that he, and apparently some of the others who took part in the discussion, appear to hold views different from my own, I think it advisable to put my opinions down as definitely and as clearly as possible, because it appears to me at least possible that some of the differences above referred to may be differences of language and definition rather than of fact. The statements I propose to submit refer to the simplest cases, namely where an area in a practically horizontal bed has been entirely worked out. My experience has been confined to beds of bituminous coal and of ironstone, but D I do not at the moment see why there should be any difference in principle between the working of a bed of anthracite and one of bituminous coal, provided that the other conditions are the same. I wish to emphasize that I am considering the conditions of complete working out of the mineral bed with the roof allowed to come down and form goaf in accordance with the general British practice; 1 am excluding, therefore, methods of hydraulic, pneumatic, and hand stowage where extraneous material is brought in to hold up the roof. I am also excluding the case of bord and pillar working where pillars of small size are deliberately left in, apparently with the idea that these will subsequently crush and let the roof down gradually. Such a method of mining has long been discontinued in this country, indeed in Europe generally, and I venture to predict that the time will come when such a recklessly wasteful method will no longer be tolerated even in the United States. Further, I am referring entirely td static conditions after the mineral bed has been worked out and the ground has come to rest; the phenomena that occur during the course of extraction are much more complicated, and these I am not discussing here. Under these conditions, I have

Jan 1, 1929

By HARRISON W. CRAVER

LIBRARIES are universally recognized as essential to modern civilization. In a world that gets most of its learning through the printed word, storehouses of print are a vital necessity. In this regard engineering differs in no way from the other learned professions, but until recent times the library needs of engineers have received rather scant attention. When the engineering profession was more of an art and less of a science than it is today, when each problem was solved more through the results of experience than by applying scientific principles, literature was less helpful. The engineer of today, however, is aware that his activities rest upon a scientific foundation and consequently comprehensive books dealing with more limited fields are now being published. Another difficulty for the operating engineer in the past was that the published works on engineering were written chiefly for use as college texts. A third obstacle to the development of engineering libraries has been the lack of librarians with experience in engineering.

Jan 1, 1938

By E. A. Jones

THE Southeast Missouri division of the St. Joseph Lead Co. normally hauls and hoists over 5 million tons of lead ore each year. This ore is mined in the stopes and headings of 20 mines, hauled to a main line system, see above, and transported up to 6.4 miles to ore-hoisting shafts. Average haulage distance is 2.16 miles. A few years ago a distinguished mining engineer visiting this area for the first time remarked, "You do not have a mining problem; yours is a haulage problem." Its relative importance may be gaged by the fact that mine haulage represents about 25 pct of the total cost of mining ore, the most costly single underground operation. The Southeast Missouri lead belt is a mining district located about 65 miles south of St. Louis. This district is roughly 6 miles wide and 10 miles long. The ore horizon lies about 400 ft below the surface where most of the ore is mined from flat-lying beds of dolomitic limestone. This paper deals with the central part of the district, namely, that portion which contains a group of interconnected mines all in a central haulage system, serving four hoisting shafts. The two major hoisting operations are carried out at Federal No. 17 shaft and Leadwood No. 12 shaft. No. 17 accounted for about 70 pct of the ore hoisted in the district during 1950, averaging about 14,000 tons per operating day. The underground dumping and skip-pocket system at this shaft is similar to those of the other shafts except that it has two rotary dumps. The other ore-hoisting shafts have only one. It might be mentioned that waste rock is hoisted at still other shafts, hauled off, and dumped on the surface by trucks. The hoisting shafts are on a connected system of about 200 miles of underground 24-in. gage main line railroad. There is also the Bonne Terre system, with its own ore-hoisting shaft, which consists of 13.5 miles of 24-in. gage main line, located in the extreme north portion of the lead belt area. Smaller outlying mines such as Doe Run No. 12 and Hayden Creek operate on trackless or shuttle car haulage. In addition to the system of main line haulage, each contributing mine group has its own extensive system of stope or heading railroad. Trackless mining is making considerable headway in the Lead-wood and Desloge mines. Here the shovel loads into a shuttle car which in turn dumps into mine cars spotted on the main line track system. When the merits of underground haulage and surface transportation are compared, it must be remembered that in early days there were many individual

Jan 1, 1954

Cooperation will be the keynote of the meeting of the Institute that will be held in New York on February 17 to 20. Arrangements are being made for two joint sessions with the Canadian Mining Institute, on the same day, which therefore will be known as Canadian Mining Institute Day. On the afternoon of Wednesday, February 19, there will be a joint session with the American Institute of Electrical Engineers. Besides, we will receive six or eight papers through the National Research Council, four of which will be presented at the National Research Council Session. In March, at the next meeting, of the Canadian Mining Institute, there will be an American Institute of Mining Engineers Day. The plan is to have the same subjects discussed at both meetings, but by different speakers. One speaker on each subject will represent the Canadian Mining Institute, and one speaker the American Institute of Mining Engineers. The Canadians and the Americans who will speak in Canada are expected to attend the discussion in New York. In addition the discussion at the New York meeting will be sent to Canada in printed form, so that the Canadian discussion will be a continuation of the former. At the joint session with the American Institute of Electrical Engineers, there will -be presented six very important papers on the subject of Electric Welding, one by the Chairman of the Electric Welding Research Committee of the National Research Council, another by the Chairman of the Metallurgical Sub-committee of that same Committee, and a third by Comfort A. Adams, President of the American Institute of Electrical Engineers and Chairman of the Welding Committee of the Emergency Fleet Corporation. We will receive six or eight papers through the National Research Council. These papers are results of recent investigations and represent the last word in their respective subjects. The excursion on Thursday, February 20, will be to Newark Bay to visit the Federal Shipyard where the first, electric-welded ship is being built. Philip W. Henry is chairman of the excursion committee of arrangements.

Jan 1, 1919

By J. J. Thomas, J. H. Nead

This investigation was undertaken to determine, if possible, the relation between static and dynamic tensile tests as measured by the work required to break test specimens slowly, in a tensile testing machine, and rapidly, by means of a falling weight. It was hoped that the investigation would throw some light on the role played by ductility under different rates of application of load. In problems of design, it is usually assumed that the moduli of elasticity of all steels are equal; viz., about 30,000,000. The stress-strain diagram within the elastic limit is a straight line, as shown in Fig. 1, where OA is the curve of a hard steel and OB that of a soft steel. If the modulus of elasticity is constant, as assumed, the slope of the line OC

Jan 1, 1922

By J. H. Nead, J. J. Thomas

This investigation was undertaken to determine, if possible, the relation between static and dynamic tensile tests as measured by the work required to break test specimens slowly, in a tensile testing machine, and rapidly, by means of a falling weight. It was hoped that the investigation would throw some light on the role played by ductility under different rates of application of load. In problems of design, it is usually assumed that the moduli of elasticity of all steels are equal; viz., about 30,000,000. The stress-strain diagram within the elastic limit is a straight line, as shown in Fig. 1, where OA is the curve of a hard steel and OB that of a soft steel. If the modulus of elasticity is constant, as assumed, the slope of the line OC

Jan 1, 1922

By Thomas Leonard Watson

Introduction,...... Historical Statement,....644 Geology of the District,....645 The Weisner Quartzite,....647 Topography,. .....653 Rock-Weathering,..... The OcheR-Deposits,.....655 Petrography of the Quartzite,..655 Associated Ore-Deposits,....657 Chemical Composition of the Ocher,. 658 Mode of Occurrence of the Ocher,..659 In the Fresh Rock,....660 In the Residual Clays,...661 Origin of the Ocher,....662 Economic Features,..... Methods of Mining,..... Preparation of the Ocher,...664 Uses,........ Introduction. Knowledge of the existence of yellow-ocher deposits in Bartow county, Georgia, dates back to the early mining of manganese- and iron-ores in the vicinity of Cartersville. Systematic mining of the ocher in this area really began, however, probably not longer than a decade back, although the date of its first working is as early as the year 1877. The district has been, for a number of years, one of the principal producers of yellow ocher in the United States; and at no period of its development have mining activities been greater and more successful than at present. Systematic field-study of the ocher- and manganese-deposits of Georgia was begun by me while I was a member of the

Jan 1, 1904

By Joshua I. Tracey, Mackenzie Gordon

THE bauxite deposits in central Arkansas were formed by weather¬ing, in early Eocene time, of fresh or kaolinized nepheline syenite above the water table in a subtropical climate of fairly continuous moisture. Four types are recognized: (1) residual bauxite deposits on kaolinized nepheline syenite, (2) residual deposits on kaolin and bauxite detritus, (3) alluvial deposits of sorted pebbles and pisolites of early Wilcox age, and (4) rubble deposits of later Wilcox age. All were invaded by kaolin and siderite during subsequent burial by Eocene sediments. PART I-FIELD RELATIONS OF THE DEPOSITS The Arkansas bauxite region for years has produced about 95 pct of the domestic supply of bauxite of the United States and it contains today reserves of more than 40 million tons-nine tenths of the known domestic reserves. During World War II, the Arkansas bauxite deposits were explored jointly by the U. S. Geological Survey and the U. S. Bureau of Mines. Some 6000 holes were drilled by rotary rigs under contract to the Federal Govern¬ment, which resulted in the discovery and delimiting of approximately 20 million tons of ore in place. Detailed study of the many sections cored through the bauxite, of data from a much greater number of drill holes made available by all the operating companies, and of the extensive mine faces exposed in the strip pits, has yielded valuable geologic information about the origin of the deposits. It is now possible to piece together a paleotopographic picture of the deposits and the now-buried land surface on which they formed. The bauxite region in the center of Arkansas (Fig 1) contains two producing districts: one in Pulaski County, just south of Little Rock, and the other in Saline County, about 15 miles to the southwest. The deposits in both districts are associated with hills of nepheline syenite, bosses of a large batho¬lith that was intruded into Paleozoic rocks and later buried beneath coastal plain sediments deposited during Cenozoic time. The folded Paleozoic rocks are exposed in the northwest half of the state and are covered in the southeast half by the nearly flat-lying coastal plain sediments. The older rocks were intruded by nepheline syenite, probably in Late Cretaceous time, and sub¬sequently were eroded so as to expose the top of the batholith. In Paleocene time, marine limestone and laminated black silty clay of the Midway group were deposited in an advancing sea, and covered all but the most elevated parts of the batholith. Erosion of the islands of nepheline

Jan 1, 1952

The finding of gold, in enriching quantity, along the streams that issued from the western foothills of the Sierra Nevada was the prelude not only to the birth of an organized mining industry in California but to the intensive exploration of the entire Pacific slope; it presaged the feverish exploitation of the mineral resources that the ubiquitous prospector soon uncovered all over our western domain. At first when this migration began, as typified by the rush of 1849, there was no time to examine the signs of ore that were to be detected along the track of adventure, and, it must be added, not many in that motley crowd of gold-seekers were qualified to interpret the signs if they had lingered to look at them. Such intelligent curiosity as a few of them possessed was directed to the finding of gold chiefly, if not exclusively; and their good sense in this respect can not be impugned, because in a new and remote country the less valuable metals and minerals are unlikely to be worth the winning. Many of those that came to California crossed the alkaline wastes and sagebrush prairies that extend between the Great Sal? Lake and the ramparts of the snow-clad Sierra; when coming overland they found it convenient to halt on the eastern slope and to pitch their camp in the valley of the Car- son river before they began the tedious ascent of the mountains and the final entry into the land of gold. One of the trails most used by these immigrants followed the Carson river to the mountain meadows south of Lake Tahoe and then descended among the pine-woods of Placerville, where they went to work with pan and shovel in the gold-bearing streams

Jan 1, 1932

Carlisle: This is August 1960 and I am sitting across the table from Henry DeWitt Smith. We both took the mining course at Yale the same year; and here we are, over fifty years later, at Nantucket Island where we have spent quite a number of summers together. Now, let's start the questions with something about the center of your career. Let's say Tsumeb; not about the mine itself which people know, but some of the details on how you happened to take it over for Newmont. Mr. Smith: I first heard of Tsumeb, a famous German mine, through our own associates O'okiep Copper Co. From 1935 on, the local management at O'okiep, being reasonably close, kept the New York office informed. It served as a listening post for new mine development, as well as being a highly profitable copper mine in the northwest Cape Colony. We had all known of a famous German mine in South West Africa called Tsumeb. But it had a reputation for not welcoming visiting engineers. One engineer who went to this property for the Ministry of Supply in 1943, '44 and '45 was Arthur Storke. He was much impressed with possibilities of profitable operation. This mine had been operated by a German company since 1910. It was finally taken over by the Custodian of Enemy Property for the Union of South Africa.

Jan 11, 1963