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By LOWELL LAWRENCE

MAGNETITE minim and milling in the Eastern States continued at a low rate of production during 1934. The year's output was 50 per cent greater than in 1933, but when one considers that the 1934 output was only 1.5 per cent of the combined plant capacities of the eastern iron ore producers, the far-reaching effect of unrestricted importation of foreign ores and pig iron is apparent. The Chateaugay Ore and Iron Co., at Lyon Mountain, N. Y., produced 1.00,136 gross tons of concentrated and sintered ore up to Nov.1, when operations were closed clown. At Mineville, the Witherbee, Sherman Corp. confined its productivity to part-time operation of its Old Bed and Harmony mines front May 1 Lo Oct. 27. This period of activity was brought about by the use of Mineville ores in the recent blast made by the Green Island furnace at Troy, N. Y. The Forest of Dean property at Fort Montgomery, N, Y., has continued closed down during the year.

Jan 1, 1935

Discussion of the paper of N. V. Hansell, presented at the Cleveland Meeting, October, 1912, and published in Bulletin No. 72, December, 1912, pp. 1497 to 1,517. C. Q. PAYNE, New York (communication to the Secretary*) :-Mr. Hansell has presented in his paper a very interesting and valuable summary of the various methods of enriching iron-ores which have been developed during recent years. Particularly striking in this connection is the high degree of enrichment of the concentrates from magnetic iron-ores which is now commercially feasible. Magnetic concentrates containing from 6 7 to 139 per cent. of metallic iron, showing an efficiency of 90 and even 95 per cent. in. their separation, are not now uncommon. Such results exceed those obtained by gravity methods of treatment of all copper-, lead-, and zinc-ores, and are only equaled in the cyaniding of gold-ores and in the flotation treatment of certain copper-ores. It is of interest to note that the-type of magnetic field which is employed in securing these results, in the Gröndal (wet) and the Ball & Norton (dry) systems of treatment is the same in each case : viz., a field of alternating north and south poles. The credit for developing this simple and useful field, which has found so wide an application both in this country and abroad, is due to two American inventors and engineers, Clinton M. Ball and Sheldon Norton. At the same time, it should be noted that part of the improvement in the grade of the magnetic concentrates, especially in the case of the wet treatment of finely mineralized ores, is due to a well-devised scheme of mill-treatment, whereby a rough concentrate is usually obtained as an intermediate product, which is then recrushed and reseparated in obtaining final clean products.

Jan 3, 1913

By Society of Mining Engineers of AIME

An error has been noticed in one of the figures in the 1974 Jackling Lecture "The Henderson Ore Body-Elements of Discovery, Reflections" by Stewart R. Wallace, published in SME Transactions, Vol. 256, No. 3, September 1974, pp. 216-227. The horizontal scale shown on Fig. 5 of this article is incorrect. The horizontal and vertical scales should be equal, i.e., the horizontal distance shown as 1000 ft should be 2000 ft.

Jan 1, 1976

By T. E. Seidel, A. U. MacRae

The dependence of the electrical and crystalline properties of silicon containing ion implanted boron atoms have been studied as a function of the incident dose, substrate temperature, and annealing tempera-ture. Hall effect studies show that the compensation due to defects is negligible after annealing at and above 500°C for a dose of 1013 ions per sq cm. Steps occur in the isochronal annealing curve for the sheet resistance at 300°C and 800°C and the mechanisms responsible for these steps are discussed. The range of the ions at 150 kev is 3500 * 5001. Electron diffraction studies on samples implanted with 150 ker ions show the existence of damaged (polycrystalline) silicon closer to the surface than the range of the ions. Etching and subsequent annealing of etched and unetched specimens suggest that the poly crystalline silicon is closer to the surface than the bulk of the distribution of ions. THE purpose of this study is to investigate some electrical and crystalline properties of ion implanted boron in silicon. Sheet resistance, Hall measurement, depth distribution by chemical staining, thermal probe and electron diffraction have been used to study the properties of samples implanted in a random direction with ions having energy up to 150 kev. The boron-silicon system has been the subject of considerable study'-7 due to its possible application in the fabrication of electronic devices. The implanted ions produce considerable crystalline damage to the substrate crystal before they lose most of their primary energy and come to rest. Fortunately, most, if not all, of this damage can be removed by subsequent annealing or by holding the substrate at an elevated temperature during the implantation process. Sheet resistivity measurements of the p-type layers produced by boron implantation into room-temperature silicon, reveal that the annealing occurs in a two-step process: the first occurring at -300°C and the second at -800°C.' Electron-microscope and low-angle electron diffraction studies of this damaged material indicate that the bombarding ions produce an amorphous silicon region about the trajectory of each ion.' At high doses, these damaged regions overlap and an amorphous surface layer results. Furthermore, the 800°C annealing step, appears to be associated with the elimination of this gross damage. The depth distribution of the as-implanted and also the annealed samples have been studied by an angle lap and staining technique as well as by Hall measurements.3-7 We find the experimentally determined ranges of the boron are less than those calculated by the Lindhard-Scharff-Schiott theorys (hereafter referred to as the LSS theory). Our results are in essential agreement with pre- vious results. In addition, we have made Hall measurements on samples bombarded with a low dose (2 x 1013 ions per sq cm) to minimize impurity banding effects, and find that deep ionized levels influence the carrier concentration and room-temperature hole mobility until the sample is annealed at temperatures above 500°C. Above this temperature, the data corresponds to that obtained when silicon is doped with boron by conventional techniques. We have also made a depth distribution determination of the crystalline damage due to the implanted boron by using glancing angle electron diffraction techniques. It was found that the gross damage depth distribution of heavily implanted samples is closer to the surface than the depth distribution of the electrically active boron. By removing this gross damage, without affecting the distribution of the implanted boron, we have determined that the 800°C annealing stage is not exclusively due to the improvement in the crystalline perfection of the amorphous material but also appears to be associated with the annealing of some point defects. These results and their relation to previous results are discussed in the following sections. IMPLANTATIONS Boron ions were implanted into silicon samples using an accelerator capable of operating from 10 to 150

Jan 1, 1970

By C. S. Smith

It is the policy of The Metallurgical Society to provide, in the TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME, a prompt and accurate medium for publication of reports of significant new research in both the scientific and engineering aspects of metallurgy. Papers submitted to the Society are judged by competent reviewers according to established criteria for technical merit, accuracy, originality, and presentation. STAFF: Editor, Dr. Gerhard Derge; Editorial Assistant, M. A. Redmyrski; Staff Coordinator, James J. Burke. THE METALLURGICAL SOCIETY: W. R. Hibbard, Jr., President; J. C. Kinnear, Jr., Post-President; John Chipman, Vice President; T. D. Jones, Treasurer; R. W. Shearman, Secretory. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: A. W. Thornton, Chairman- Dennis Carney John Chipman J. C. Fulton J. H. Hollomon H. H. Kellogg, A. E. Lee, R. Moddin, J. D. sullivan, and D.' Swan. Review and selection of manuscripts is under the supervision of the following Publications Committees: Extractive Metallurgy Division: T. B. King, Chairman; S. J. Dickenson, R. P. Hermsdorf, R. Schuhmann, Jr., and P. T. Stroup. lnstitute of Metals DM lion: Robert Maddin, Chairman. F. Lincoln Vogel, Jr.. Vice chairman. W. A. Backofen R. W. Boliuffi J. H. Bechtold' M. B. Bever R: S. Busk C 6. Goetzel poul Gordon C. D. Grobom, Jr., Robert F. Hehe-mann R. I. Joffee F. i. Joumot Jr. lrvin R. Kromer, A. J. Leno. Horold Morgolfn, C. J. McHargue, Russell A. Meussner, J. B. Newkirk, H. W. Paxton, G. E. Pellissier, I. S. Servi, Alon U. Seybolt, A. J. Shaler, and Jack Washburn. Iron and Steel Division: J. C. Fulton, Chairman. T. B. King, F. C. Laogenberg, W. O. Philbrook, and T. 0. Winkler. Publishod bimonthl by the American Institute of Mining Metollurgicol and Petroleum Engineers Inc., 29 West 39th Street, New York 16, N. Y. Telephone: PEonylvanie 6-9220. Subscription $20 par yew for non-AIME members in United States and North, South and Control Americo $25 foreign; $5 for AIME members. Single copies, $4.00, single copios foreign $5,00. The AIME is 1958 by the Amarican mode or opinion axpressed in it* publications ... Copyright by the Amarican lnstitute of Mining, MataIlurgicol, and Petrolum Engineers, Inc,. . . Reg. istered cable address AIME New Yark ... Indexed in Engineering Inderx, Industrial Arts ...Index and Chemicol Number5. Absrtracis . . . Second class postage paid at New York,Indor. N. Y., Industrialond Ann Arbor, Mich.

Jan 1, 1959

By J. B. Dilworth

OUTCROPS of coal have bees discovered is many localities is the Philippine archipelago, and practically all of the larger islands contain deposits of this mineral. Very little prospecting has been done to determine the value of the various coal-bearing areas, but so far as known, the largest and most promising fields are found : (1) is northern Cebu; (2) is the small island of Batan, a part of the province of Albay is southeasten Luzon; (3) is the somewhat larger island of Polillo, off the east coast of Luzon, and (4) is southern Mindoro, sear the small coast tows of Bulalacao. Northern Panay, south-central Cebu, and various localities is southern Luzon, Masbate, Negros, and Mindanao also afford evidences of the existence of coal-beds, the extent and value of which have not yet bees proved. The general position of these islands and districts is shows on the map of a portion of the Philippine Islands, Fig. 1. Some of these coal-fields have been known for many years (coal was discovered is Cebu 1827 and is Batas is 1842),1 and several futile attempts were made by the Spaniards to operate mines is these districts. But owing to many circumstances, chief among which were indifferent management, the political unrest of the islands, natural difficulties of transportation, and those inherent in the mining of steeply-inclined and somewhat irregular seams, no considerable output was ever obtained from any of these mines, and the fuel required is the many departments of industrial and political life has continued to be drawn largely from Australia and Japan. These conditions exist to a great degree at present, and though much interest is the coal-deposits of the Philippines

Jan 1, 1909

By Hallet R. Robbins

KOREA, the ancient " Hermit Kingdom," is a peninsula jutting out from the coast of eastern Asia. By the natives it is called " Chosen," which, translated, means " Land of the Morning Calm." It lies between the Yellow sea and the Sea of Japan. On the north it is separated from Manchuria and the Russian province of Primorsk by the Yalu and Tiumen rivers ; on the south the Korean straits interpose a rough voyage of 120 miles to the nearest point in Japan. The entire country is situated between the parallels of 34° and 42° N. latitude. The surface of the country is made up of successive ranges of unglaciated mountains, separated by narrow, fertile, and more or less densely populated, valleys. Through all the obscure centuries of its history, Korea has succeeded in maintaining a monastic seclusion, over which, from time immemorial until the late Chino-Japanese war in 1894, China exercised a shadowy sovereignty. Although Korea had been forced into slight foreign contact previously, her first foreign treaty was signed with Japan in 1876. Under the restraining guardianship of China, the Japanese treaty bore but insignificant innovations for Korea; but when, in 1883, a treaty was made with the United States, the first of the western nations, a decade after the American gunboats, under Commodore Rodgers and Lieutenant Schley, forced their way up the Salee river, shooting daylight through the ancient walls and fastnesses, Korea awoke from her sleep of 4,000 years. The Korean peninsula suddenly became the arena where rival nations' enterprises and individuals met in fiercest conflict. Out of this struggle grew two singularly successful American

Jan 7, 1908

By C. W. Dunham

DESIGN of the structures for the Morenci Reduction Works involved many interesting problems. Naturally, the chief purpose of these structures is to house and support the equipment and other things necessary for or incidental to the conduct of production. hence most of the features of the design were developed to suit these particular conditions; however, several are so generally applicable as to warrant description.

Jan 1, 1942

By R. I. Jaffee, J. G. Dunleavy, W. Hodge, H. R. Ogden

Jan 1, 1949

By L. C. Graton

At the Tenth International Geological Congress, Mexico, 1906, Waldemar Lindgren presented "The Relation of Ore Deposition to Physical Conditions." Retrospect ranks it as the outstanding offering at that Session and as the most fundamental contribution up to that date on the philosophy of ore deposition. Elaborating thereon in his text-book "Mineral Deposits," Lindgren analyzed ore-forming processes under conditions prevailing from great depth up to surface; explained the nature of deposition in each environment; and developed a comprehensive genetic ore classification, which brought wide acceptance and enriching contributions by many. Since Lindgren's latest edition (1933), have come wealths of material relevant to ore genesis, particularly through amazing renaissance and proliferation throughout science. Current publication regarding ores now emanates largely from a generation caught in pressures of the breathless modern tempo, which tempts scant reflection upon earlier truths. Consequently, today's thrilling output contains not a few offerings that need challenge because supplanting interrelationship and system by what seems, collectively, an assemblage of strange, ad hoc and often self-contradictory concepts. From these latter some merit may eventuate but at the probable cost of present confusion and delayed progress. The following pages, naming numerous post-Lindgren advances, record the conviction, held by many, that Lindgren's philosophy, progressively improved, remains the soundest approach to understanding ore genesis.

Jan 1, 1968

By E. R. Kaiser

COAL research during 1941 had a marked increase in activity on problems bearing directly on furthering the increased and improved use of coal in homes and industry. Coal producers and fuel engineers expressed a greater interest in its practical possibilities and the coal laboratories have shown an increased interest in applied research, of value at once or in the near future to industry and the public. A large volume of accomplishment in mining, coal analysis, and the fundamentals of coal constitution and coal chemistry also continued to fill the storehouse from which applied research and fuel engineering of the future can draw valuable data.

Jan 1, 1942

By F. O. Garrabrant

Power is furnished to the Climax Molybdenum Co. by the Public Service Co. of Colorado over two 100,000-volt lines to a bank of three 3333-kva. transformers 100/13.8 kv. These transformers are so designed that with the addition of forced cooling their capacity may be increased 33? per cent at 12,000-ft. altitude. Under present conditions, these transformers are operated at 140 Per cent of their rating with forced air cooling. On the secondary side of this bank there is a 15-kv., 1200-amp. Westinghouse oil circuit breaker provided with automatic reclosing relays allowing three successive short circuits before lockout. From this breaker 13.8-kv. power is transmitted to a central switching station (Fig. I) where all circuits radiate to the different operations of the property. Each circuit is protected by a 23-kv., 600-amp. oil circuit breaker with by-pass and isolating disconnecting switches. Mine Power at 13.8 kv. enters the mine through a ventilation raise over a three-conductor, size 1-0 varnished cambric insulated, leaded, steel-wire armored cable, insulated from 17 kv. This power is received and distributed through one switching station and four underground substations, shown in Fig. 2. No. 370 substation (Fig. 3) contains three a 13,800/440-volt, single- phase Pyranol transformers protected on the high-voltage side by a 600-amp. manually operated oil circuit breaker. This station serves 20 slusher-hoist motors, a 45-kw., three-phase, 220-volt electric furnace, a Massco hot miller for tempering and milling Timken detachable bits and a hoist with 175-hp motor on the No, 3 development shaft. Also at this shaft are three pumps. One two-stage pump, 1200 gal, per min., 500-ft. head, 3600 r.p.m., driven by a 150-hp. motor, is at the bottom of the shaft, Two deep-well pumps, 500 gal. per min., 500-ft. head, are at the collar of the shaft. under normal operation the one pumping 1200 gal. per min, is controlled by a float switch to take care of the water. If this pump fails, or if its capacity is insufficient, the first 500-gal. pump is automatically started1 and if still more capacity is needed the second 500-gal. pump automatically starts. Time delay relays are provided on the deep-well pumps, so that if power fails the column will have time to drain before the Pumps restart. On failure of any Of these, an alarm is sounded in the train dispatcher's office, so that mechanics can be sent to ascertain the cause of failure and make repairs. The cable from No. 37' substation is run to the switching station, in which are four 15-kv., 600-amp. direct-current sole-noid-operated oil circuit breakers. The current for Operating and tripping is furnished by a 125-volt storage battery. All breakers are operated from the switchboard in the compressor room. One circuit from this switching station goes to the

Jan 1, 1946

By W. R. McMillan, E. A. Gulbransen, K. F. Andrew

Annealed and electrolytically polished pure iron was oxidized between 650° and 850°C at oxygen pressures of 0.1 to 2 microns Hg. Electron optical studies showed that oxidation occurs discontinuously over the surface and orients crystallographically with the substructure of the metal grains. IN previous papers', " the authors described the formation of oxide films on high purity iron at norrnal pressures and at temperatures below 300°C. Electron optical studies showed that the oxide film consisted of many individual oxide crystallites having nearly random orientation on each metal grain. The size of the oxide crystallites depended upon the temperature and upon the extent of oxidation. In these studies the crystallite size varied from 250 to 1800Å. Recently, Bardolle and Benard3 studied the crystal habit of the oxide crystallites formed on Armco iron between 650" and 850°C in what might be defined as a "poor vacuum" atmosphere in which the pressure could be varied between 10-1 to 10-3 mm of Hg. Their results showed that, at 850°C and a vacuum of l0-2 to 10-3 mm of Hg, a few well oriented nuclei of oxide were formed on the metal grains. At pressures between l0-1 to 10-2 mm of Hg, many oriented nuclei of oxide were formed. At 750°C the metal surface was bright although an oxide was present. Unfortunately, the extent of oxidation, the oxygen pressure, and the influence of carbon in the metal were not determined, and it was, therefore, impossible to give a theoretical interpretation to the very beautiful light micrographs. Bardolle and Benard used the light microscope to determine the crystal habit of the oxide and X-ray diffraction to determine the orientation relationships. It was believed that the use of controlled amounts of oxidation at high temperature is an important method for the study of the initial stages of oxidation of metals at high temperatures. This paper presents the first results of an electron optical study of this problem for iron. Since the electron microscope and electron-diffraction methods using stripped oxide films and surface replicas yielded finer details of the crystal habit and structure of oxide film, these methods were used in this study. Two types of iron having different carbon contents were used: Puron and Armco* iron. A com- parison of the results for these materials made possible a study of the influence of the surface oxide-carbon reaction on the initial stages of oxidation. Before discussing the experimental results, the thermodynamic equilibria of 1—the oxidation reaction, 2—the surface oxide-carbon reaction, and 3—the solubility of oxygen in iron, will be considered. In addition, it is important to consider the kinetic-theory predictions on the rate of collision of oxygen with the iron surface. Thermodynamic and Kinetic-Theory Calculations Only one type of reaction is usually considered in the oxidation of iron at normal pressures at high temperatures: Fe(a) + 1/2O2(g) = FeO(s) 3Fe(a) + 2O2(g) = Fe3O4(s) 2Fe(a) +3/2O2(g) = a-Fe2O3(s). [11 However, two other reactions may occur: FeO(s) + C (solid solution in Fe) + Fe(a) + CO(g) [2] and Fe(a) + O2(g) e Fe(a) (solid solution of 0,). [ 3 ] In addition, iron will react with the higher oxide at certain temperatures to form FeO. For a complete interpretation of the oxidation of iron at low pres-

Jan 1, 1955

By C. R. Hayward, H. O. Hofman

I. INTRODUCTION. THE aim of instruction in a metallurgical laboratory is to make real the principles on which metallurgical processes and operations are based, and to foster the spirit of investigation: The materials with which experiments are carried out are ores, metals, and metallic compounds. The method varies with the end sought. A class may work as a whole, each member contributing his share to the solution of a problem, or the students may carry on investigations independently; the former exemplifies class-research; the latter, individual research. It is with a branch of the former, with special reference to ore-treatment that the present paper intends to deal. In smelting an ore by a well-established process, the result is shown by analyzing the products to see whether their compositions correspond to those calculated in making up the charge; by taking account of stock to show the distribution of metal in the different products made and the losses from dust and volatilization, by casting a thermal balance to find the ,distribution and losses of heat; and by making a cost-sheet to ascertain, as far as possible, the necessary outlay of money. In, lixiviation and amalgamation, the mode of operating has to be varied to adapt a process to the individual ore. Here a number of tests become necessary. Each will consist of a series of experiments with one variable, in order to find the conditions under which the variable gives the best result; a. summary of several tests will give the best method of operating.. Working a number of charges with the best method will furnish the data desired for ascertaining the recovery of metal,

Jun 1, 1909

By E. F. Koch, J. L. Walter

oriented crystals of iron and iron with 3, 5, and 6.25 pct Si were rolled to reductions of 10 and 70 to 97 pct at room temperature. Similarly oriented crystals were deformed in tension. Dislocation substructures of the deformed crystals were observed by transmission electron microscopy to determine the effect of silicon on the formation of substructures. Pole figures were obtained to relate orientation changes to substructure. When rolled 10 pct, the iron crystals and the 3 pct Si-Fe crystals formed cells, 1 and 0.2 u in diameter, respecliuely. Cells were absent in the higher-silicon crystals. Extended dislocations and possible stacking faults were observed in the 6.25 pct Si-Fe crystal rolled 10 pct and annealed at 650°C. The stacking-fault energy was estimated to be 20 ergs per sq cm. Rolling to 70 pct resulted in the formation of sub-bands (0.9 µ wide) ill the iron crystals and transition bands (containing 0.2-µ-wide subbands) in the 3 pct Si crystals. No subbands formed in the 5 pct Si-Fe crystal until it was ankzealed. SliP occurred on (112) planes ill tension. The slip traces on the 3 pct Si crystal were wary while those on the 5 pct Si crystal wvere straight. The strain-hardening coefficient for the 5 pct Si crystal was nearly zero. Cells did not form, at least at elongations up to 10 pet. The results suggest that cross slip of iron is restricted by additions of silicon beyond about 3 pct possibly by formation of immobile extended dislocations. IN a previous paper' the authors described the substructures developed in (100)[001]-oriented crystals of 3 pct Si-Fe which were rolled to reductions of 10 to 90 pct at room temperature. At low reductions (10 to 20 pct) cells, approximately 0.2 to 0.3 ja in diameter, were formed. The cell walls consisted mainly of edge dislocations. With increasing reduction (up to 50 pct) the cells were seen to elongate in the rolling direction. In certain regions of the crystal there were significant reorientations which were characterized as rotations about an axis normal to the (100) or rolling plane. These regions were called "transition bands". The regions in which there were no reorientations were called ('deformation bands". At reductions of 60 to 70 pct the elongated cells in the transition bands became sub-bands separated by low-angle tilt boundaries with angles of disorientation of about 2 deg. The elongated cell structure in the deformation band was replaced by a general distribution of dislocations. It was noted that the width of the subbands in the transition bands remained 0.2 to 0.3 µ; i .e., the width of the subbands was the same as the initial cell diameter for reductions up to at least 70 pct. From this, and from considerations of the mechanism of formation of the transition bands,' it was concluded that the subbands evolved directly from the initial cells. In order to check this conclusion, it was decided to examine the relationship between initial cell diameter and width of subbands produced by large rolling reductions. Cell size is known to be dependent upon the temperature of deformation.2,3 However, preliminary experiments with 3 pct Si-Fe crystals indicated that the change in cell size with increasing temperature of deform,ation was not sufficient for the present purpose. On the other hand, cell diameters generally reported for iron deformed at room temperature2'3 range from 1 to 2 p, a factor of 3 to 10 larger than the cells in 3 pct Si-Fe rolled to 10 pct reduction,' indicating the possibility of a marked dependence of substructure (at least in terms of cell size) on the amount of silicon in iron. Thus, the investigation was enlarged to include the study of the effects of varying silicon content on substructure in lightly rolled as well as in heavily rolled crystals of iron and iron with 3, 5, and 6.25 pct Si. The crystals used in this study all had the same orientation, (100)[001], with respect to rolling plane and rolling direction. These were rolled to reductions of from 10 to 97 pct and the substructures determined by electron transmission microscopy in both the rolled state and after annealing. In addition, stress-strain curves were obtained from (100)[001]-oriented crystals of iron and 3 and 5 pct Si-Fe to determine the effect of silicon on tensile properties. The dislocation substructure of the tensile specimens was also determined for Samples pulled to 2 and 10 pct elongation at room temperature for comparison with the substructures produced by rolling. 1) EXPERIMENTAL PROCEDURE Crystals with 3, 5, and 6.25 pct Si were prepared by annealing 0.012-in.-thick sheets of high-purity Si-Fe in purified argon at 1200°C to effect growth

Jan 1, 1965

By HAROLD VINTON COES

MANAGEMENT has been tersely defined as getting things done through the efforts of other people; but before we proceed further, let us distinguish between administration, management, and organization. Oliver Sheldon in his book, "The Philosophy of Management," offers the following definitions: Administration is the function in industry concerned in the determination of the corporate policy, the co-ordination of finance, production, and distribution, the settlement of the compass of the organization, and the ultimate control of the executive.

Jan 1, 1943

By Herbert Herman, M. E. Fine

THE first decomposition product of a supersaturated aluminum-rich A1-Ag alloy at low tempera- tures is Guinier-Preston zones.'-, The zones are ideal and each consists of a spherical shaped silver-rich cluster about 16 A in diam syrounded by a silver-poor shell approximately 72A in diam.' The composition of the two regions is not known with certainty., After quenching from the solution anneal, these zones form rapidly on aging at temperatures as low as -30°C.5 The rate of zone formation increases with aging temperature; the activation

Jan 1, 1961

By GEORGE L. CHRISTIAN

T HE Tonopah Extension assay office is a two- story, concrete structure on a solid foundation of andesite, situated about 100 yd. from the company's mill, so that it will not be affected by the stamps or the tube-mills; also it will not be affected by under- ground blasting. On the second floor are the mine superintendent's office and drafting and blueprint rooms. On the ground floor are the assayer's office,' mixing room, furnace room, crusher room, chemical laboratory, parting room, store room, and change and shower room for the mine superintendent, assayers, and engineers. The crusher room is outside of the main building, and has four concrete walls, thus eliminating the jar of the crusher; it is so situated that the least possible amount of dust spreads through the main building. An 8 by 10-in. jaw crusher, which crushes to ¼ in., was made by a local foundry. Attached to the top is a small galvanized-iron hopper covered with a ¼ in. screen, on to which the sample is dumped. The fines-pass through the screen into the hopper, while the oversize is dumped into the crusher. The crushed sample and fines from the screen drop down to a set .of splits suspended from an iron rod below the crusher jaws. The small sample is caught below in a small pulp pan. The rejects drop from the splits through a 2-in. pipe on to a bucket conveyor, which dumps into a galvanized-iron hopper in an upper corner of the room. The rejects drop through a 2-in. pipe to a reject bin outside the build- ing. This bin is constructed high enough for a truck to be loaded from it by means of a chute door on the side.

Jan 1, 1921

By William G., Pariseau

There are important phenomena in rock and soil mechanics that cannot be explained in terms of theories of homogeneous, isotropic materials. Subsidence of strata about mine openings is an example. In-situ stress measurements in nonisotropic sedimentary, and metamorphic rocks is another. Patterns of joints, faults, fractures, and similar geologic features impart directional mechanical properties to rock masses that are locally isotropic or anisotropic. On the geologic scale, the non-homogeneity of composite rock masses may, in certain instances, be dealt with as homogeneous anisotropy. The mechanics of large rock masses can, therefore, be expected to involve considerations of anisotropy. The source of the anisotropy is not relevant. Once the scale of observation is selected and the material is defined accordingly, the analysis of stress and deformation proceeds without regard to the numerical values of the material constants. There are also important phenomena in rock and soil mechanics that cannot be explained in terms of linear elasticity, theory. For the mechanical description of anisotropic geologic materials capable of de- forming beyond the limit of purely elastic strains, a plasticity theory is required.

Jan 1, 1972

By Phillip E. Butler

The Pennsylvania Dept. of Transportation is actively engaged in the utilization of coal mine refuse in the construction of highway embankments. Long-held objections for utilization are invalidated by research, laboratory data, and construction performance. Laboratory, engineering, construction, and environmental impact analyses are presented from the construction of the Cross Valley Expressway embankment at Forty Fort, Luzerne County, Pa. Comparisons of laboratory data and construction measurements are given. The refuse embankment is the first of its size in Pennsylvania, and possibly the U. S., covering 1.5 million cu yd.

Jan 1, 1977