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By S. F. Emmons

Introductoy.—In view of the fact that an opportunity is to be offered to the members of the Institute present to inspect the recent developments of gold-deposits in the immediate vicinity of Washington it has seemed appropriate that some preliminary description of them should be given which may facilitate that inspection. It would have been a matter of much satisfaction to me to be able to present some general description of the gold-deposits of the Appalachian system ; but I have as yet had no opportunity of personally examining any others than those of Montgomery county, and these are still in their infancy. It is, moreover, a slower and more difficult operation to make geological observations in this region than in the more northern States; for whereas in the latter region the

Jan 1, 1890

By R. M. Schuller, J. J. Suloway, W. F. Childers, R. A. Griffin, S. J. Russell

Seven solid wastes from coal conversion processes were characterized chemically and mineralogically. The wastes included three Lurgi gasification ashes, two liquefaction residues (SRC and H-coal), a fly ash, and a water-quenched slag. Leachates generated from the solid wastes at various pH levels over the range 2.5 to 11.0 were analyzed for over 40 constituents. Results of the leachate analyses demonstrate the wide variation in constituent solubility for the solid wastes. To help assess the environmental impact of the disposal of these wastes, the leachates were also employed in soil attenuation studies and acute 96-hr static bioassays using young fathead minnows.

Jan 1, 1981

By David M. Parkes, Junie Lindsay

A review of the movement of coal in water is undertaken from a practical rather than a theoretical view point. Installations are described in which coal is transported on gradients down to 2.5' and others which move coal at a water-coal ratio of 1:l by weight. The water cycle of the hydraulic mining system is discussed. In many applications this can be a closed circuit. The coal dewatering system is illustrated, making particular reference to the problems of storage of coal-water mixtures between the mine and the plant. Water treatment is done in thickeners down to 100 ppm which is normally sufficient for re-circulating through high pressure pumps and monitors.

Jan 1, 1978

By C. K. McArthur

The subject of classification is so broad that this discussion is confined to what the author believes is of prime importance in connection with proper grinding and classification. The years past have witnessed many noteworthy changes in fine grinding and classification, which have been accompanied by a readjustment of ore-dressing flowsheets for the preparation of better ground and/or sized products at an expenditure of less power, steel and maintenance than formerly. Nowhere in the industry is more being done in the way of experimental work to lower costs than in grinding circuits, because, at best, grinding costs are high. Recent years have indicated that, on the average, finer grinding has a real application. Without careful preparation of the process feed, no operation can be highly efficient or successful. In an earlier paper, the findings of an extensive survey at representative concentrators were presented1. Also, in the year of 1935, a technical discussion was given by Dr. J. V. N. Dorr (Some Notes on Classification Trends in America) before the Chemical, Metallurgical and Mining Society of South Africa In both papers mentioned, much has been said regarding flowsheets, grinding and classification. The author is very familiar with these papers, having had considerable to do with the actual operation of the flowsheets, as well as large mills and classifiers in the work described. Some data from the second paper have been included in the following discussion. Circulating Load In this particular paper it seems advisable to deal with the classification phases of the work that to a major extent govern the success of any closed-circuit grinding unit. The question has often been asked in connection with a closed circuit: "What circulating-load ratio should be carried?" This is really an

Jan 1, 1939

By C. B. Foster, S. I. Freedman, E. M. Jamgochian

Coal-oil mixture (COM) combustion technology is regarded by the US Department of Energy (DOE) as near term and Potentially applicable to existing utility and industrial steam generators and for injection into blast furnaces. From work done previously, it has been established that COM can be burned in existing boilers and blast furnaces. Therefore, the issues being addressed by the current DOE program are: (1) determination of best available technology to achieve environmentally acceptable long-term reliable operation and (2) determination of applications for which COM can be utilized economically. Some of the technological options have begun to be determined by projects already under way. However, many projects are still in the early stages of development.

Jan 1, 1980

By Robert Longyear

IN, diamond-drill work, a true sample consists of all the material cut by the bit-both core and cuttings. As the recovery of this sample is the object of diamond drilling, the utmost care should be taken to secure it. Speed of drilling and low costs are of little value if an inaccurate sample is obtained. The engineer in charge must study his material and lay out the plan of sampling, and then see that the drill runner follows his instructions; for the runner may be more interested in obtaining a large footage than in developing accurate methods of sampling. FIG. 1.-CORE BOX. When the core has been removed from the core barrel, it should be placed in a core box in the exact order in which it is taken from the ground. This box, Fig. 1, is usually a shallow tray 4 or 5 ft. (1.2 or 1.5 m.) long, with partitions running lengthwise between which the core

Jan 12, 1921

By John H. Bassarear, Harold W. Sorstokke

The fourth expansion within 10 years was completed at Pima Mining Co. during late 1971. The first three expansions increased capacity from 3000 to over 40,000 tpd. Conventional crushing and grinding practices were used in the original 10-section mill. Total capacity is now approximately 54,000 tpd. Expansion IV includes a new primary crusher and a radial stacker conveyor that feeds stockpiles for both concentrators. The -8-in. primary product is fed from the reclaim stockpile to the new mill by two pairs of pan feeders, each pair feeding a separate conveyor. The reclaim conveyors each feed 28 X 12-ft semiautogenous mills operating with an 8% charge of 4-in. balls. Autogenous discharge is screened, oversize recycling by conveyors, with -%-in. undersize feeding two conventional 161/2 X 19-ft ball mills in closed circuit with cyclones. Cyclone overflow is pumped to three parallel rows of 300-400 cu ft flotation cells. Rougher and scavenger concentrates produced are sent to the original mill for regrind, cleaning, and filtering.

Jan 1, 1974

ROBERT E. TALLY,* Jerome, Ariz. (written discussion ?).-Mr. Sherman's paper, entitled "Measures for Controlling Fires at the Copper Queen Mine," embodies two new and very important features: First, automatic closing of doors communicating with the dangerous area; second, the use of a portable storage-battery fan. His other procedures, such as giving a general fire alarm, getting workmen to the surface, etc., are equally important, but have long been in use in other places. Fire and ventilating doors in connections leading to shafts, air raises, and other large timbered areas, have been in use at other mines; but the method described by Mr. Sherman for operating these doors by compressed air, through a valve on the surface, is, so far as I know, original, and should be installed in every mine where there is danger of fire. Nearly all large mines are now using artificial ventilation, with the result that there are strong air currents in the shafts and other important workings. The most important feature in mine fires is a quick and positive control of the ventilation, for it takes but a few moments for smoke to travel over a large area, with the usual results of suffocation, and destruction of property. A strong air current in an upcast shaft acts as a draft in case of fire, and unless quickly cut off the fire would soon get beyond control. An upcast shaft usually changes to a downcast when large amounts of water are used. Human lives are in more danger from downcast currents, as the smoke travels into the workings.

Jan 4, 1918

By F. V. Lenel, G. S. Ansell, J. A. Dromsky

The growth of aluminum oxide particles in a nickel matrix was studied eve?. the temperature vange of 2140° to 2470°F. The instability of the dispersed alumina was shown to be independent of the crystal structure of the alumina. The activation energy for the growth of the dispersed alumina was found to be 84.7 1 2.0 kcal. The particle radius increased as a function of time. These results indicate that the growth is not diffusion controlled. It is believed that the rate controlling mechanism is the dissolution of the aluminum and oxygen atoms into the nickel lattice. THE strength properties of alloys which consist of a finely dispersed second phase in a metallic matrix depend upon the spacing between the second phase particles. It is therefore desirable to achieve very fine dispersions in these alloys. Furthermore, to retain the properties these very fine dispersions must be stable during fabrication and service of the alloys. The best known of the dispersion strengthened materials, the SAP type alloys, which consist of a dispersion of aluminurn oxide in aluminum, have exceptionally good stability up to the melting point of aluminum. There is evidence, however, that other dispersion strengthened alloys, even those consisting of refractory oxides in a metal matrix, may be less stable. This investigation is concerned with the stability of Ni-Al2O3 alloys in the temperature range in which these alloys are usually fabricated. The mechanical properties of Ni-Al2O3 alloys at elevated temperatures have been previously investigated by Crelnens and rant,' and Gregory and Goetzel.2 The behavior of these alloys in stress rupture tests appears to indicate that at temperatures below 1800°F they are highly stable. There is some doubt, however, as to their stability at the higher temperatures used during the conventional fabrication. Cremens and Grant, in preparing their test alloys, cousolidated, by powder metallurgical techniques, nickel powders as fine as 0.13 µ diam and alumina powders as fine as 0.018 µ. Metallo- graphic examination of the alloys following fabrication revealed that none had interparticle spacings of less than 2 µ. Considering the size of the original component powder particles, it is likely that the dispersions coarsened during fabrication. Gregory and Goetzel, in their studies of extruded alloys of 80 pct Ni—-20 pct Cr matrixes with nonmetallic dispersion, observed a definite coarsening of the alumina dispersions in alloys sintered at 2280°F as cantrasted to those sintered at 2000oF. Similar observations on the spheroidization and growth of thoria particles finely dispersed in a nickel matrix were made by D. K. Worn and S. F. Marton.3 As a result of such coarsening, much of the effort expended in the preparation of very fine powder mixtures would be lost. The mechanical properties of the alloys which had experienced coarsening would be expected to be poorer than if the original dispersions had been retained. EXPERIMENTAL PROCEDURE Ni-Al2O3 alloys were produced from powder prepared by a coprecipitation technique. Aluminum hydroxide and nickel hydroxide were coprecipitated from chloride solutions of the metals. The mixed hydroxides were calcined to form metal oxides and the nickel oxide in the mixture was selectively reduced to nickel by treating it in hydrogen. Specimens were compacted from the resultant powder which consisted of a fine, uniform mixture of aluminum oxide and nickel particles. The compacts were sintered by resistance hot pressing4, a densification technique which requires exposure times of the order of only a second or less at elevated temperatures. A conventional sintering process was not used, since the temperature required for densification would have to be in the region in which the stability of the dispersion was to be studied. A series of hot pressed specimens were treated in hydrogen at temperatures from 2140o to 2470°F (1171o to 1355oC, for times up to 120 hr. Changes in the microstructures were studied by electron microscopy using the two-stage preshadowed carbon replica method.5 In performing a lineal analysis on a series of micrographs from each specimen it was found more convenient to determine the mean free path between alumina particles rather than particle radii as the parameter of growth. Although these quantities are directly proportional for only spherical particles, the alumina particles in these alloys

Jan 1, 1962

By C. E. Sims, C. A. Zapffe

Many hundreds of publications have appeared during the past 78 years that treat the subject of hydrogen in iron and steel.l05 but conclusions regarding the functions of hydrogen in causing some important defects in steel are still unsatisfactory to many; and other hydrogen-caused phenomena yet remain to be identified with this gas. The most widely discussed of these defects is hydrogen embrittlement, but the conception, perhaps the popular one, that embrittlelnent is due to hydride formation aoes not conform to the known facts.l04 The true identity of hydrogen embrittlement seems instead to lie in a mosaic nature of metal crystals, which is a concept not Yet accepted by most metallurgists. A study of hydrogen embrittlement therefore provides new viewpoints in regard to the crystalline substructure of steel.

Jan 1, 1941

By Hamilton Wingate

In his paper on the hydraulic mining of a low-grade gravel in California,* Mr. W. H. Radford expresses the hope that other members of the Institute will contribute, for the benefit of all, their experience in similar lines. In these notes 1 shall describe the conditions and results of the operation of the Gold Bug Mining Co., of Cleveland, O., at Georgetown, Eldorado county, Cal.

Jan 1, 1903

By A. J. Lanza

IN view of the immense amount of attention that silicosis has received in this country in the past few years, it is timely to review the status of the silicosis problem at present. Who gets silicosis? The individual exposed to the inhalation of free silica dust. The effects upon the individual depend upon the amount of silica inhaled or, in other words, the severity of exposure, rather than upon any special variation or susceptibility among those exposed. A considerable amount of study has been given to determine what may be the role of predisposing causes in the development of silicosis. To mention one instance, at the Picher Clinic careful records were kept of all previous illnesses of the men examined as well as abnormalities present at the time of examination. Examinations of over 27,000 miners were made during the years the clinic was conducted under governmental auspices-a very fair sized sample. The general conclusions from all this work were that the incidence of silicosis is not appreciably influenced by racial, structural, or other inherent qualities; it is influenced by acquired defects-particularly as these affect the lungs. That is to say, the average run of human beings respond similarly to similar exposures to silica dust and those whose lungs are already impaired by tuberculosis or other pulmonary disease acquire silicosis more readily than those with healthy lungs. It may well be, and there is some clinical evidence in support, that negroes acquire silicosis more readily than do whites, but the infection factor has not been so carefully studied among negroes exposed to silica as it has among whites. We know that tubercle infection is more prevalent among negroes than among whites. There may be other factors concerned in the development of silicosis in negroes as compared to whites, but there is not available information upon which to base positive statements. INFECTION AND COMPENSATION Our first ideas about silicosis in this country were derived from early studies in the mining industry where the silica exposure was severe and

Jan 1, 1937

By John W. Weeton, Max Quatinetz, Robert J. Schafer

Nickel powders of 1-, 0.4-, and 0.2- average particle size were combined with 0.05- p MgO powder. Oxide was added in quantities of 4, 12, and 20 vol pct. The mixtures were vacuum hot pressed and extruded at 2100°F. In spite of a general tendency to growth of oxide particles during processing, dispersions of fineness comparable to those of Sintered Aluminum Powder, SAP, were achieved. A small amount of oxide considerably improved 1800°F stress-rupture strength, but further oxide addition resulted in a decrease of strength. RECENTLY there has been much speculation concerning the requisites for strong and stable dispersion-strengthened alloys. The nature of the dispersed phase, the stability of the alloys, and variables influencing the mechanical properties of alloys have been given consideration. Such topics have been reviewed by Bunshah and Goetzel. Of the many parameters related to the mechanical properties of dispersion alloys, mean free path between dispersed particles (a measure of the fineness of the dispersion), particle size, and vol pct of the dispersed phase have been shown to be very important. Generally, strength increases with decreasing mean free path, and there is an optimum vol pct of dispersed phase. Just how fine a dispersion ought to be is somewhat open to debate, but Irmann, Lenel, Backensto, and Rose, Gregory and Grant,4 and others have shown in the original SAP-type alloys, aluminum plus aluminum oxide alloys, that better strength is generally obtained with finer dispersions and the best strengths were obtained when the mean free path was less than . Further, Cremens, and rant' showed that in nickel plus aluminum oxide alloys, stress-rupture strength at 1500°F was definitely increasing with decreasing mean free path. In their investigation, however, the finest dispersions that were produced were about 2.0 mean free path. To determine the potential of the nickel plus oxide type of product, it would be neces- sary to obtain dispersions analogous to those of SAP alloys; namely, ones where the mean free path between oxides is less than . Unfortunately, however, it is very difficult to produce extremely fine dispersions of oxides in metals other than those which naturally form refractory oxide skins. There are several approaches to this problem including such procedures as mechanical mixing, internal oxidation, reduction of mixed oxides, and metal deposition from solution. Work at the Lewis Research Center has shown that metal powders 0.1p or finer could be produced by ball milling, when selected grinding aids were utilized.' Because these unusually fine powders were available, it was an initial objective of this study to determine if by mixing of these fine Ni powders with various amounts of MgO (0.05) a fine dispersion of MgO in Ni comparable to those in Al-Al203 might be achieved. A second objective was then to attempt to relate the parameters of structure to 1800°F stress-rupture strength of the alloys. Nickel powders of 1-, 0.4-, and 0.2-p average particle size were combined with 0.05- average particle size MgO powder. This oxide was added in quantities of 4, 12, and 20 vol pct. The mixtures were hot pressed and extruded at 2100°F.

Jan 1, 1962

By T. A. Rickard

The mountains of the picturesque Dauphine, in southeastern France, have long been known to collectors as the source of many minerals of rare occurrence; but. they contain also several mines, which, though less known, date from the time of the Saracens, many centuries back, to that of the graduate from the Ecole des Mines. In the department of the Isere, upon the cliffs of Villard Ey-

Jan 1, 1893

By W. C. Maurer

A study of the mechanics of shear failure of rock under pressure has been made. The transition from brittle to ductile failure occurs when the friction along the fracture surfaces exceeds the shear strength of the rock. A machine has been developed for measuring both the shear strength of rock and the friction along rock fracture surfaces. In this shear machine, the fractures are forced along definite planes; as a result, the rock is stronger than in compression tests where the fractures choose the weakest paths through the specimens. Friction is composed of several forces: (1) the forces to slide irregulurities on surfaces over each other; (2) forces to shear some of these irregularities; (3) molecular attractions across the fractures; and (4) forces required to break bonds resulting from melting and welding at the tips of irregularities on the surfaces. Friction along rock fracture surfaces is not proportional to contact pressure as usually assumed; instead, it increases as the contact pressure raised to the 0.4 to 0.8 power. INTRODUCTION It is difficult to produce tensile stresses under the high compressive stresses present in the earth; therefore, in deep drilling and geological faulting, shear failure predominates. This shear failure mechanism is complicated because rock is a heterogeneous material containing pore spaces, microfractures, elastic discontinuities and other imperfections. A study of shear failure of rock under pressure has been made to obtain a better understanding of this complex mechanism. A machine has been developed and used to measure the shear strength of rock and friction along sheared surfaces. This machine has certain advantages over the compression test — shear properties can be measured under low normal stresses and shear stress and normal stress can be varied independently. The first part of this paper is a description of shear failure of rock under pressure. The role of shear strength and friction along fracture surfaces in the shear failure mechanism will be discussed. The second part consists of a description of the shear machine and a discussion of the shear strength and friction data obtained using this machine. It will be shown that shear strength depends upon the size of the stressed zone, and that friction does not increase linearly with contact pressure as usually assumed. Attempts are made to relate some of the new concepts to tectonic failure and to dril ling. SHEAR FAILURE IN ROCK TRIAXIAL TESTS The shear failure mechanism is illustrated by the triaxial test shown in Fig. 1. In this test, a cylindrical rock specimen is subjected to a confining pressure, PC, and an axial pressure, pa. These external pressures produce normal a and shear T stresses on inclined planes within the specimen equal to1 where 0 is the angle between the specimen axis and a normal to the inclined plane. Fig. 2 shows how triaxial specimens deform as the axial pressure is increased. The pressure is

Jan 1, 1966

By Robert Sisselman

If we are lucky," says Hollis M. Dole, Assistant Secretary of the Interior, "coal, uranium and hydropower will provide us with maybe a third of the energy we require in 1985. The other two- thirds will have to be made available in liquid and gaseous form." Luck, however, may have run out, for if the facts and figures relating to supply and demand of natural gas over the next 20 years prove accurate, the United States may fall short in its attempts to bring the energy crisis under control. By the year 1990 the world will need to consume a minimum 150 quadrillion Btu of energy with gas requirements running as high as 42-43 trillion cu ft. By 1990, the U.S. alone will require 45-46 trillion cu ft. To meet anticipated demand, this country will have to overcome a deficiency of about 20 trillion cu ft since, by all pragmatic estimates, it will produce only 15-20 trillion cu ft of gas. The importation of natural gas into the U.S. will help but will not solve the problem. Adequate gas supplies will have to be supplied domestically. The Arctic, with its predicted huge reserves of gas, combined with imports of liquid natural gas (LNG) may provide as much as 15% of the 45-46 trillion figure, however, such reserves will not come into play as quickly as originally thought. The Alaskan gas fields, for instance, will provide a substantial supplement to domestic gas needs, but only after 1976.

Jan 10, 1972

By Gilbert P. Moore

Bolivia does not yet have any production which is being marketed. It does have a potential production, however, from wells which have been completed by the Standard Oil Co. of Bolivia, a subsidiary of the Standard Oil Co. of New Jersey. No other company is active in drilling and development work to date. The total potential production from wells now completed is about 6000 bbl, daily. Wells Completed Completions during 1928 and their initial daily productions. if any, were as follows: Camatindi No. 1, 350 to 1000 bbl.: Camiri No. 1, 500 bbl.; Sanandita No. 3, 100 bbl.; Tatarenda No. 1, dry hole, and Bermejo No. 2, deepened 50 ft. made 1000 barrels. The most striking development of the year was the Camiri No. 1 well which, after just entering the sand, made 500 bbl. per day of 52" B. oil. This well is the northernmost good producer which the Standard has brought in to date. Oil from this well is used without refining in the tractors and trucks of the company. A small topping plant has been installed from which high-grade gasoline is obtained for use in motor cars and some is being produced for the use of air plants stationed at Villa Montes. The results for Sanandita No. 13 were somewhat disappointing since Sanandita No. 2 was rated at about 3000 bbl. Tatarenda NO. 1, located on a large unbroken structure, was drilled to 4000 ft. and abandoned as a dry hole. Bermejo No. 2 was deepened 50 ft. to 2085 ft.. and on a 10-day test averaged 1000 bbl. per day. This well is on the border between Bolivia and the Argentine. Wells Drilling The wells drilling are Camiri No. 2, Sanandita No. 5, Machareti No. I and Bermejo No. 5. This is the smallest number of drilling wells which the Standard has had for several years but is principally due to

Jan 1, 1929

By M. F. Williams, L. G. Hendrickson

In classification of pulps bearing magnetized ferro-magnetic particles, depolarizing is of great importance. If size separation is to be effective, particles must be individual rather than in flocs. Depolarizing is also practiced in heavy medium separations in which ferrosilicon or magnetite is the medium. When particles of ferromagnetic material have been removed from a magnetic field, residual magnetism causes agglomeration. The term depolarizing refers to the operation of reducing or eliminating this residual magnetism and may thus be considered magnetic deflocculation. The terms demagnetizing and randomizing are also used.

Feb 1, 1956

By D. R. Skidmore, C. J. Konya

To quantify the effects of proper stemming on air-blast and flyrock reduction for a surface mining operation, a study was undertaken with funding from the Office of Surface Mining. Known weights of explosive charges were detonated in a simulated blasthole when confined with various types and size distributions of stemming. Results showed that proper selection of material type and size distribution can reduce necessary stemming length by 41 % and airblast levels by 23%. A relationship was obtained for minimum length of stemming for explosive confinement as a function of stemming size distribution and borehole diameter over a range of explosive pressures.

Jan 1, 1984

By F. V. Shallcross

Physical properties of thin films of CdS and CdSe formed by vacuum deposition onto glass sibstrates have been studied as a function of deposition and processing conditions. The crystallinity and surface features of CdS films were examined using electron microscopy and electron and X-ray diffraction techniques. The films were poly crystalline; the preferred orientation and crystallite size increased with film thickness, substrate temperature, and deposition time. The CdS films consisted primarily of hexagonal-phase material, in contrast to similarly prepared CdSe films which have previously been observed to contain mixtures of cubic and hexagonal phases. As-deposited CdS films showed no major dependence of Hall mobility on crystallite size or degree of preferred orientation. Hall mobility and carrier concentration in CdS and CdSe .films were measured at various temperatures; both parameters increased with temperature and yielded activation energies which depended on fabrication conditions. Surface-desorption phenomena and overcoating of the semiconductor with SiO affected the observed electrical properties significantly. THIN films of cadmium sulfide1,2 and cadmium sele-nide3,4 have been employed by various workers as semiconductors in the insulated-gate thin-film field-effect transistor, known as the TFT. These devices are most commonly made by vacuum deposition of all materials onto an amorphous substrate such as glass. A knowledge of the microstructure and electrical properties of semiconductor layers used in the thin-film transistor is essential in order to form a realistic model for the device and to improve its performance, reproducibility, and reliability. This paper will describe studies of the physical properties of vacuum-deposited CdS and CdSe films prepared under various conditions. Structural characteristics examined in- cluded phases present, crystallite size, nature of preferred orientation of crystallites, surface roughness, and structural homogeneity throughout the film thickness. Electrical properties measured were Hall mobility and conductivity and their dependence on temperature and ambient. Thin-film properties are affected by many fabrication parameters including purity and physical form of evaporant, deposition rate, film thickness, design and temperature of the evaporation crucible, geometry of the deposition chamber, nature of the residual atmosphere, composition and temperature of the substrate, and details of postdeposition processing. PREPARATION OF FILMS In this work the semiconductor films were deposited in a conventional oil-diffusion-pumped system with pressures in the 10-8 torr range. The CdS evaporant was obtained from the Eagle-Picher Co. as a high-purity coarse-grained crystalline powder; the CdSe was a high-purity sintered powder supplied by the Harshaw Chemical Co. The evaporation crucible was a resistance-heated molybdenum-wire basket coated with aluminum oxide and filled with a quartz wool plug at the top. The source to substrate distance was usually 10 cm. This region was enclosed by a Pyrex inner cylinder. The substrate was heated with an overlying Pyrex plate coated with tin oxide. The substrate temperature was controlled using a thermocouple attached to the lower side of the heater. This thermocouple was calibrated against another thermocouple attached to a dummy substrate and by observation of melting points of various metal films deposited in the system. The substrates were polished borosilicate glass plates and conventional glass microscope slides. Substrate preparation included cleaning with an ultrasonically agitated detergent bath followed by isopropanol-vapor de-greasing. Film thickness was measured interferomet-rically during and after deposition. STRUCTURE OF CdS FILMS Structural studies were performed on CdS films using electron diffraction, electron microscopy, and

Jan 1, 1967