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By Eduardo J. Chibas

Location.—The principal manganese-deposits of the Department of Panama, Republic of Colombia, are located almost clue south of Viento Frio, a native village bordering on the Caribbean Sea, and about 45 miles northeast of Colon (Aspinwall). The mining-claims are the Viento Frio, the Carrano, the Nispero, and the Soledad. Each property is to the south of the preceding one in the order mentioned. The first one is about one mile from the coast, and the most southerly boundary of the Soledad is about five miles in a straight line from the same coast-line. I shall confine my remarks to the four properties mentioned and to La Guaca, west of the Carrano, because these are the only ones where mining has so far been done to more or less extent. Manganese has also been found, however, in the neighborhood of these deposits, and a large area adjoining them has been divided into sections and " denounced " as mining-claims. The relative position of the manganese-deposits and Nombre de Dios, the present terminal of the railroad and shipping-port, as well as Viento Frio and the adjacent coast, can

Jan 1, 1898

I. N. KNAPP, Ardmore, Pa. (written discussion*).-Captain Lucas has made an important contribution to our, knowledge of Belle Isle, especially as to the outline of the sulphur deposit, and the pronounced irregularity of the salt surface. I agree with his view, that the elevation or mound that constitutes Belle Isle may consist of several salt domes formed at different periods. It may be interesting to note the high gas pressure encountered in pockets in the salt by my No. 1 Belle-Isle well. While drilling a dry hole with cable tools, we sometimes struck. pockets of gas which would float the tools, so that drilling had to be suspended sometimes for several hours at a time, until the head of gas was exhausted, and this with a string of tools, 5-in. (127 mm.) stem 36 ft. (10.9 m.) long, that weighed complete about 3500 lb. (1587 kg.). At about 1800 ft. (548 m.), we struck the largest gas pocket and the string of tools was thrown up and nearly out of the hole. When it dropped back it made several loops

Jan 1, 1918

THE CHAIRMAN (H. W. MORSE, Los Angeles, Cal.).-I would like to open this meeting for a little while to the general subject of leaching. We ought not to hold back if we have any new schemes for the future. I know that those of us who are tangled up with this lei thing work will appreciate any suggestions that will make us work harder and, scheme, harder to pull through these past difficulties on leaching. F. S. SCHIMERKA, Clifton, Ariz.-Under the direction of J. W. Bennie, General Manager of the Shannon Copper Co., Clifton, Ariz., 'it has been my valued privilege to cooperate in the elaboration of a hydrometallurgical process aiming at the recovery of copper in mill tailing resulting from a gravity concentration of a low-grade semi-oxidized sulphide ore occurring in a porphyritic gangue. The experimental work which has been carried on with a 25-ton plant is completed, and the company is building at present a leaching plant on a larger scale, the first unit consisting of a 150-ton roasting furnace and accessories for leaching the calcine.

Jan 12, 1916

By A. D. Hughes

A relatively small area in Malaya, about 200 miles long by 40 miles wide, is the most important source of tin in the world. Some tin is recovered in other parts of the peninsula. Of the tin mined, 98 pct is recovered from alluvial deposits. From 1935 to 1941 the average annual world production of tin was 190,000 tons. The average annual production from Malaya during the same period was 62,000 tons or about one third of the total. Other producing countries, in order of importance, were the Netherlands East Indies 34,000 tons, Bolivia 30,000, Belgian Congo, Nigeria, Siam, Burma, China, and a few others with smaller amounts. The serious shortage of tin during the war period was due to the fact that the Japanese were occupying Malaya, Netherlands East Indies, Siam, Burma, and China which, together, formerly were producing 65 pct of the world supply.

Jan 1, 1949

By Williams, J. A.

THE Alaska Juneau mine has been developed through an adit driven at the elevation of the top of the mill and all mining is done above this main haulage level. As a result of wholesa1e"mining operations about 11,000 tons rock containing one dollar' per ton in gold is, hauled to the. concentrator during every 24 hr. Due to the method of mining, whereby a system of oreways delivers-the.ore direct from the stope to the bottom level of the mine, no tramming of ore is done on any of the upper levels. However, ;in doing exploratory drifting and crosscutting on the upper levels, the broken material is trammed by hand in 1-ton 18-in. gage cars to a nearby raise connecting with one of the several oreways. This constitutes the only tramming operation except that on the main level.

Jan 1, 1931

By C. A. Stetefeldt

In my paper on "The Consumption of Fuel in the Taylor Gas-Producer Plants at the Aspen and Marsac Mills" (Trans., xxiii., 134), I mentioned that in the plant which I had designed for the Ontario mill, the gas-tubes were to be covered with thin, corrugated sheet-iron, over which a coating of asbestos-magnesia would be spread in order to effect a good insulation and keep the gas as hot as possible. At the Ontario mill, two Stetefeldt furnaces and two revolving driers are fired with gas. One furnace is connected with a Taylor producer of 5 feet diameter, and the other furnace and the two driers are heated by the gas from a Taylor producer of 7 feet diameter. In the latter case the gas-tubes are necessarily somewhat long, and the cleaning of them takes time. In order to prevent overheating of the tubes during that operation, it has been found advantageous not to provide them with an insulating covering. If a tube becomes red-hot at any place by the burning of soot, this is at once observed, and the tube is closed until it cools down. The tubes con-

Jan 1, 1895

By Willard S. Morse

In my paper on "The Lixiviation of Silver-Ores by the Russell Process at Aspen, Colorado" (page 137 of the present volume), attention was called to the decrease in "chlorination " during the washing of the roasted ore with water, to remove soluble salts, before leaching with hyposulphite and Russell solutions. This decrease in " chlorination," which is due to conversion of the silver chloride to some other form not soluble in hyposulphite solutions, and which, for the sake of brevity, will be termed the "going-back" of chlorination, has been a serious obstacle to the successful operation of several leaching-works, and was at Aspen the only difficulty encountered. I have never seen any explanation of the cause of this failure to extract, in actual practice in the mill, the amount of silver chloride shown by laboratory-leachings to be present in the roasted ore; and the purpose of this paper is to record the conclusions arrived at concerning the cause of the phenomenon, and the data upon which they are based. The average decrease in chlorination by washing with water in the Aspen ores for a period of fourteen months was as follows:

Jan 1, 1896

By Fred P. Dewey

The iron ores of Canada have attracted more or less attention in this country for a number of years ; and having had an opportunity this past summer to examine some of them, especially the magnetic ores, I have thought it might be of sufficient interest to the members of the Institute to put on record some of my observations. The region examined contains, for the most part, only the rocks of the Laurentian system. Much of it was originally covered with a dense growth of pine, which interfered with successful prospecting for ores. However, after the best of the timber had been cut off, fire generally got into the bush and cleared it up pretty well. This, besides making travelling about easier, exposed large surfaces of rock, and rendered the work of the prospector far more liable to be rewarded with success, while removing many of its hardships. The general appearance and productiveness of the land have, however, been far from improved by this process. It would be difficult to find a more desolate-appearing country than some of these pine woods after fire has been through them. The country examined may be, for convenience, divided into two

Jan 1, 1884

By P. G. Meikle, C. T. Holland

The effect of the condition of friction upon the ultimate unit compressive strength as determined between the compressed faces of precisely machined coal specimens and specially prepared testing platens has been examined. Reductions of 30 to 40% in the ultimate unit compressive strength of these model coal pillars have been verified when lubricants areused between the faces as compared to non-lubricated faces. Increase in unit compressive strength due to confinement at each of three levels of friction appears to follow generally the widely accepted "1/2 power law", i.e. S - C (L/T)1/2 where S is the unit ultimate strength, C is a constant dependent on the coal being tested and the coefficient of friction acting at the compression surfaces and L and T are the least width and thickness of the specimen, respectively. Results suggest that the surface condition of both the specimen and platens should be mentioned in detail in conjunction with compression testing, for although the term (L/T)1/2 is adequate for all practical purposes, the coefficient C is directly dependent on the condition of interfacial friction, all else remaining constant. One phase of the investigation of the confining effect of friction on the ultimate unit compressive strength of small coal specimens has recently been completed at the School of Mines of West Virginia University. The efficient control of ground is of fundamental importance to successful mining operations and the design of support pillars has always presented the mining engineer with a difficult and intriguing engineering problem. Since about the turn of the century, many investigators have performed extensive laboratory tests on small coal specimens in efforts to solve some of the perplexing problems of strata control and pillar action in coal mines. A detailed review of this work would serve no purpose here, but a brief mention of the more significant contributions is in order. Muller16 was perhaps the first to illustrate the effect of confining pressure on the strength of coal specimens in compression. His work has recently been more carefully expanded by the experiments of Murrell17 in Great Britain. Rice and Enzian l9 observed that as the size of cubical test specimens increased, the unit compressive strength decreased. These observations were later supplemented by Lawall and Holland, 13 by Greenwald4,5 et a1 at the U. S. Bureau of Mines, by Gaddy3 as well as by Steart,22 Millard15 et a1 and Evans2 et al. Gaddy3 seems to have been first to quantify this relationship with his equation: S = K/vd , where S - ultimate unit compressive strength (psi), K = a constant dependent on the coal, and D =edge dimension (in inches). Holland7 concluded that the strength of coal as affected by lateral dimensions and thickness could be expressed as where K = a coefficient dependent upon the coal, L = least width of pillar (in.) and T = thickness of pillar (in.). Data supplied by this formula have been compared to the estimated stresses in pillars that had been standing for long periods in coal mines and in the cases so far studied the results indicate that the formula predictions are sufficiently accurate for engineering purposes (Holland11 ). This equation therefore is believed to be the simplest and most accurate tool available at the present time for approximating the strength of a coal pillar (over a specified range of L/T) in situ. However, Holland7,9 has indicated that friction between the coal pillars and the top and bottom rock

Jan 1, 1965

By S. Kobayashi, A. E. Armenákas, C. Mylonas

Earlier work1-4 has shown that commercial mild steels under static loading at the lowest natural operating temperatures fracture in a brittle manner only when damaged by a suitable history of straining. Notched and then compressed plates have fractured in subsequent tension at loads as low as 10 pct of the limit load and precompressed smooth bars at a subsequent extensional strain as low as 0.01. The comparison of the average net fracture stress with the flow limit stress was shown to be an excellent criterion of brittle or ductile behavior of mild steel structures when only loads and general stress levels are known. The present investigation shows that the deformation at fracture is a far more sensitive measure of brittleness than the fracture stress. Both criteria, deformation and stress, are used to determine the amount of uniform precompression of two mild steels, ABS-B and Project E-steel, resulting in brittle fracture under the strong constraint of a subsequently machined severe circumferential groove. The fracture stress equaled or exceeded the theoretical flow limit Ól = 2.680., ('based on the elevated yield stress at each prestrain) up to prestrains of about 0.20 and then fell off to about 1 at prestrains of 0.60. Yet a prestrain of only 0.05 reduced the elongation at the shoulders by a factor of about 4. The total plastic elongation of a region surrounding a sharp notch in prestrained steel deternines whether or not fracture will be initiated in large structures, hence is a direct and realistic measure of the remaining ductility and provides an excellent test of the material's resistance to embrittlement. ALMOST all engineering structures of mild steel which failed in service in a so-called "brittle" manner exhibited appreciable local plastic deformation (more than 1 pct) and a mixture of "cleavage" and "shear" fracture surfaces. Furthermore, the peak local stress in an advancing crack is always high. Such simple criteria as pure cleavage, absence of plasticity, or fracture stress, so useful in other fields, are insufficient to characterize brittleness in engineering structures at ordnary temperatures. The "brittle)' behavior of engineering structures is caused by the limited ductility at cracks or notch regions, as shown by recent work at Brown University summarized and extended in Refs. 1 to 4. It was also shown that the local ductility of mild steel may be catastrophically reduced by a suitable strain and temperature history similar to those which may occur in real structures. Localized yielding begins at the notch roots at low loads but is contained by surrounding elastic regions. The plastic strains are hence small. They increase slowly with the load up to the flow limit or limit load for an ideally plastic material. Unrestricted plastic flow then occurs. At such strains the real material locally st rain-hardens and fractures. With work-hardening materials no flow limit exists, and the transition from low to high plastic strains is gradual but increases more rapidly at loads close to the flow limit of an equivalent perfectly plastic material. When the available ductility is sufficient for reaching the limit load, the behavior is normal or "ductile". With insufficient ductility, fracture will occur at a low load and will be defined as "brittle". Accordingly the sufficiency or not of the ductility at a notch is reflected in the magnitude of the fracture load or average net stress as compared with the limit load or flow limit. The application of this criterion gave surprising results. Service failures under semistatic loading occurred mostly below the limit load, hence were "brittle". On the contrary all static tests with undamaged commercial mild steels reached the limit load in spite of the deepest notches and temperatures below Charpy impact transition (say about -30°F or higher). Notched bars showed no brittleness even under fully dynamic axial loading up to 1.5 x107 psi per sec at -23°F and about 2.5 x l06 psi per sec at -ll0°F, but broke in a brittle manner at -200°F and l03 psi per sec.' To propagate a fracture at low load, experimenters had to trigger it by superimposing a strong dynamic impact at a notch cooled by liquid nitrogen as in the Robertson5 or Esso tests.' Once started the cracks would run through warmer regions of smaller stress. Obviously the ductility of the apparently undamaged commercial steels was "sufficient" in the laboratory tests but not in the service fracture, where it must have been reduced by some embrittling procedure of fabrication or service. These conclusions were confirmed by the achievement of low static stress (brittle) fracture initiation in unwelded steel after a local reduction of ductility by simple prestraining. Symmetrically notched plates of undamaged mild steel cooled below the Charpy V-notch transition range were tested in central static tension: Undamaged plates withstood loads of limit intensity, but when subjected to prior in-plane com-pressive prestraining perpendicular to the notch axis and to accelerated aging, the plates fractured completely or partially at very low static loads, as low as one-tenth of the flow limit.2-4 However, damage could not be easily related to the strongly variable prestrain around a sharp notch. To obtain easier strain measurements, it was decided to use axially precom-pressed bars and bent bars. Final testing was done by

Jan 1, 1970

By ANTON GRAY

In considering the possibilities and costs of discovering minerals by exploration. mineral occurrences may be classified roughly according to the size of the target they offer to the various methods that have been used to search them out. This classification is advantageous because the methods of search which might be expected to give results in one case may be totally inapplicable in others. Mineral deposits for the most part have been found in groups, or districts, in which the individual deposits occur under the same general geological conditions and usually contain more or less the same metals. There are, also, what are apparently isolated de- posits, although if the truth were fully known many of these probably would not be isolated. These districts, such as the Belgian Congo copper fields, the California Mother Lode, and the Linares lead district of Spain, form the first division of my classification. The second division is formed of the individual deposits of these districts, for example, Kambove mine in the Congo, the Kennedy-Argonaut vein in California, and the Cruz vein at Linares. The third division consists of the separate ore bodies that make up the deposits

Jan 1, 1949

By John V. Beall

On weekends things get pretty interesting out our way because the fleet is usually in. Our No. 2 son is now based at New London, which Isn't far from here, and he brings his friends home. No. 1 son is a re- cent Navy veteran, and he lives at home. It is just as well that the Pentagon can't hear what is said. This is all aside from the point except that last Friday evening, Dave Meinhard, a redheaded nukie (nuclear sub crewman) from Indiana, commented on our late arrival home In obvious need of a pick-me-up. "Just like my dad; but he has it rougher than you. We live in La Porte, Ind., and every day he drives 35 minutes to work at Bridgeman, Mich., and loses an hour on the time zone. It's really exhausting. You should see him." We feel very sympathetic. He should receive extra pay. However, extra pay benefits are hard to come by although the reverse comes relatively easy. For example Grass Valley, Calif., was such a nice place to live 25 years ago that they compensated for it by making an appropriate deduction for the s

Jan 1, 1971

By A. Eilers

In a former paper on Western Smelting Works, I mentioned the great difficulty of obtaining accurate information in regard to the economy of the processes in practice; and to-day, although nearly two years have elapsed since my former paper was written, I am sorry to say that very little improvement has taken place in the keeping of accounts, and in the direction of a more systematic management in the majority of these works. But I am quite certain that by this time even the most sanguine furnace managers must have become convinced, from the experience of the last year, that somewhere in their processes there are enormous losses. Rates for the purchase of ores in 1873 were not as high as they were in former years in certain parts of the country ; labor was no 'higher than formerly; the demand for unparted lead was good throughout the year, with the only exception of the time of the panic, in the fall of 1873; yet there are, of between 40 and 50 works, not more than two or three in Utah and Nevada to-day, that have paid a reasonable interest on the capital invested.

By A. Filers

IN a former paper on Western Smelting Works, I mentioned the great difficulty of obtaining accurate information in regard to the economy of the processes in practice ; and to-day, although nearly two years have elapsed since my former paper was written, I am sorry to say that very little improvement has taken place in the keeping of accounts, and in the direction of a more systematic management in the majority of these works. But I am quite certain that by this time even the most sanguine furnace managers must have become convinced, from the experience of the last year, that somewhere in their processes there are enormous losses. Rates for the purchase of ores in 1873 were not as high as they were in former years in certain parts of the country ; labor was no higher than formerly ; the demand for unparted lead was good throughout the year, with the only exception of the time of the panic, in the fall of 1873; yet there are, of between 40 and 50 works, not more than two or three in Utah and Nevada to-day, that have paid a reasonable interest on the capital invested.

Jan 1, 1875

By G. E. Pralle

INTRODUCTION The decade from 1969 to 1979 saw the crest of a wave of investments by companies and investors, primarily from the major industrial nations, in the metals and minerals industries of the so-called lesser developed countries. This was brought about by two major considerations: 1). The higher ore grades and therefore the higher profit potential of the mineral deposits in the third world countries, and 2). The desire, particularly by the European countries and by Japan, to ensure a safe supply of raw materials not available in their own countries. The decade began with the start of the Toquepala mine in Peru and the major investments in the Bougainville mine in Papua New Guinea and the Ertsberg mine in Indonesia. It ended with the start-up of Southern Peru Copper Company (SPCC) Cuajone mine in Peru and Inco's Soroako mine in Indonesia and the investments in several major alumina or aluminum projects in Australia and Brazil. Concurrent with this huge flow of funds into the mineral resources industry of the developing world was the build-up of a psychological fear in the host countries of exploitation/domination by the foreign investors. This resulted in an increasing trend towards: 1). Nationalization of existing mineral ventures, and 2). Tougher legal/fiscal frameworks for new ones. NATIONALIZATION Nationalization appeared in its earliest form as "Mexicanization" of the petroleum industry in Mexico in the 1930's, followed later by Mexicanization of the mining industry in general. This was enacted with the Mexican Mining Law of 1961 which required that 51% of the equity be owned by Mexican nationals. Later in the decade the equity share for foreign investors was reduced to 33 1/3% for the developers of the Frasch sulphur operations in the Isthumus of Tehuantepec. However, the law was not fully implemented in the copper industry until late 1970 with the purchase of 51% of the ownership in the Cananea Mining Company. The trend toward nationalization of the copper industry progressed to Chile where in 1967 under the Government of Eduardo Frei the major North American copper companies were induced to sell a one-half interest in their Chilean mines to the State. Likewise, in 1970, "Zambianization" took place, when the two major operating companies Roan Selection Trust (Amax) and Zamanglo (Anglo American) were restructured into Roan Consolidated Mines (RCM) and Nchanga Consolidated Mines (NCCM) providing the government with 51% of the equity ownership. Whilst the earlier forms of nationalization in general constituted a fairly priced buy-out (El Teniente, Chile for US$80 million, RCM for US$117.8 million, NCCM for US$178.7 million), the total nationalization of the Chilean mining companies in 1970 under Salvador Allende did not. Later, "Western" countries joined this trend and on October 29, 1973, Mr. Gough Whitlam proclaimed that "overseas capital must continue... in partnership with Australian capital" and "in some special energy cases we have an objective of 100% Australian ownership". In 1974 Mr. Pierre Trudeau stated: "The Liberal Party of Canada sets as an objective that new resources projects in the natural resource field should have at least 50% and preferably 60% Canadian equity ownership". FOREIGN INVESTMENT The situation for the foreign investor in the worldwide resource industry rapidly deteriorated from then on. New features appeared in mineral exploitation and operating agreements, centering not only on local government/local companies ownership but also on increased taxation. The new tax rate (mineral tax, royalty, and income tax) for the semi-government companies NCCM and RCM in Zambia became an effective 73%. Likewise the much publicized and discussed renegotiated Bougainville agreement brought dramatic increases in the total "take" by the PNG Government. More innovative forms of indirect taxation made their appearance and were added to the normal tax burdens of the mineral industry which already

Jan 1, 1985

By Charles Catlett

Much has been done of late years to facilitate preliminary stratigraphical investigations, and for examination at considerable depths and in a certain character of material the diamonddrill, in its general forms, certainly stands pre-eminent among the tools for such work. But there are large classes of deposits —indeed, I may say the larger proportion in which ordinary. prospecting is done—which lie near the surface and are interbedded with soft and fine material. The method usually employed for prospecting these is by means of small shafts. These are sunk with considerable slowness and at considerable expense, depending largely upon the character of the material encountered, and are greatly interfered with by water. In this region the smallest are 3 by 4 feet, but they are usually considerably larger. Having had occasion during the past year to do a large amount of prospecting work, I have found the use of a hand-auger and drill of immense value in this respect, and in my practice it has largely superseded, and always preceded, the other forms of investigation. I believe that the information desired mas

Jan 1, 1898

By R. W. Raymond

Most of US, in this hurrying age, take little pains to preserve such records of our doings as will make the work of' our biographers easy. Now and then there is an exception, and Dr. Trippel was one. Methodical in all his habits, he kept diaries and journals comprising his own personal experiences, the details and results of his numerous scientific investigations, and his impressions concerning men and events; and also copies of all his technical essays, published by various societies or periodicals. It is a striking instance of " the irony of fate," that these carefully-preserved materials, which would now have a real historical, as well as biographical value, were totally destroyed by an accidental fire a few years ago. In addition to my own recollections of an acquaintance covering more than thirty years, I am indebted, for the fads upon which this sketch is based, chiefly to Mr. Engene J. Trippel, a son of the deceased, and now Register of the United States Land Office at Tucson, Arizona. Mr. Trippel, however, frankly confesses that his own knowledge of his father's work is, in the absence of written records, imperfect.

Jan 1, 1898

By Walter A. Backofen, Donald H. Avery

Intense primary and cross-slip traces were observed in easy glide on Cu: 6 pct-A1 single crystals deformed in tension. A mechanism of cooperative source operation is developed which recognizes that both the applied stress and that resolved from dislocation arrays contribute to the stress on a source. By considering the stress from arrays, the activation of secondary systems in easy glide and the difference in appearance of slip markings on pure and solid-solution crystals are explained. Furthermore the cross-slip system is predicted to be second favored during easy glide for a large range of orientations. FROM many studies of easy glide in fcc metal crystals, a pattern of observations has developed which still requires full explanation. In pure copper, aluminum, and silver, the easy-glide, slip traces are fine and uniform with steps 50 to 100A on the primary* system.1-4 Yet it has not been at all clear why slip in the pure materials should occur in this way. On the contrary, one might expect, with simple slip and a low hardening rate, that the weakest sources on the primary system would operate extensively to produce strong slip traces. In a brass, however, intense slip steps up to 0.5 are found on both primary and cross-slip system4,6-9 seeger10 has pointed out that in a material of low stacking-fault energy such as a brass, extensive easy-glide cross-slip could not be thermally activated, but rather must originate on the cross-slip plane. In further explanation, the wilsdorfs4 and seeger10 noted that only the cross-slip system would not harden differently than the primary, whatever the latent hardening tendencies of other systems; therefore, in brass, which exhibits high latent hardening, the cross-slip is the only secondary system which could be expected to operate extensively, once it became active. The explanation of how the cross-slip system, on which the applied stress is low, becomes activated has been related, in a nonspecific way, to pileups by Hirsch11 and Honeycombe.l2 In the work to be described, deformation traces on solid-solution Cu: 6 pct A1 single crvstals were studied with conventional light microscopy and a mechanism proposed to explain both the observed activation of secondary systems in easy glide and the difference in appearance of slip markings on pure and solid-solution crystals. EXPERIMENTAL In preparing the Cu-A1 single crystals, rectangular bars approximately 0.4 in. by 0.4 in. by 6 in. were first machined from ingots made by vacuum melting copper of 99.999 pct and aluminum of 99.99 pct purity. They were then packed in powdered graphite and the crystals grown in a modified Bridgman apparatus at a rate of 5 mm per hr under an atmosphere of purified nitrogen. Crystal perfection as indicated by Laue back-reflection spots was good except for the last inch to freeze, which was discarded. Orientations so determined are shown in Fig. 1. Tensile specimens with a reduced gage section were obtained by masking the ends with electrical tape and chemically polishing in a solution of 20 pct HNO3, 24 pct HAc, 52 pct H3PO4, 2 pct Hcl, and 2 pct H20 at room temperature.13 Finally, the specimens were electropolished in a 30 pct ortho-phosphoric acid bath at 12 v. Tensile deformation was performed in an Instron testing machine at a strain rate of approximately 1 pct per min. During easy glide, extensive cross-slip was observed with all crystals, in spite of the low Schmid factor on this system, and in no case was any other secondary trace encountered. A certain sequence of slip-line development was associated with the extension. At yielding, intense primary traces passing completely through the crystal developed at some point on the gage section, generally near the grips; weak cross-slip traces also appeared, extending from the primary traces into the adjacent undeformed crystal, Fig. 2. Further extension led to primary traces adjacent to the first-formed and connecting with those of the cross-

Jan 1, 1963

By Robert J. McKay, F. P. Huston, WILLIAM G. HUMPTON

THE manufacture of nickel-clad steel plate and the fabrication of articles from it has progressed far enough to permit a general description of the working methods used. The manufacture of sheets made up of layers of nickel and steel is not new as a sheet of this character was patented in Germany in 1893. Present development differs mainly in the size and finish of the product. The earlier light-gage highly finished products have been limited in their application due to their similarity, in certain respects, to electro-plated and highly finished alloy sheets. The new product is a relatively heavy plate 1/4 or 3/s in. thick and heavier, with one side coated with nickel, the weight of nickel being of the order of 10 per cent of the whole. The finish is that of hot-rolled steel plate.

Jan 1, 1931

A. K. McCosh, Coatbridge, Scotland (written discussion*).-It is well known in Great Britain that oven operators in the United States have been able to reduce the coking time much below European standards by the employment of higher temperatures. Our linings have always been the factor that has prevented our doing the same, and it would be of much interest to coke-oven operators here if Mr. Blauvelt would give a typical analysis of the bricks his company uses for the linings of its ovens, and if he could see his way to send me a sample so that I could have the texture examined, I should personally be very much obliged. The lining brick which my company has found most successful is of a ganister variety, and has the following analysis: Silica, 80.8 per cent.; alumina and iron oxide, .17.8 per cent.; lime, 0.8 per cent.; magnesia, 0.07 per cent.; but with this brick the least carelessness on the gas regulator's part may destroy the lining. It would also be of interest if Mr. Blauvelt could give the temperatures of the air leaving these generators and also of the oven flues.

Jan 10, 1918