Search Documents

By James P. Kimball

Jan 1, 1885

By Faustino Roel

AMONG the problems confronting the mining engineer in Mexico in recent years, labor conflicts have come to occupy s prominent place. Each day they have become more serious and frequently have caused- the ruin of companies. It is therefore necessary for the engineer to understand the Federal Labor Law, the rights and obligations of companies and of their workmen, and the reasons for conflicts; to keep in mind the expense which may be caused companies; and to endeavor to avoid difficulties as far as possible. Our labor legislation is primarily to protect the workman and the constant tendency of the tribunals, including the Supreme Court of Justice, is to support the work- man in his demands against employer$, even at times granting him more than he asks, with no limit other than the economic capacity of the company to com-

Jan 1, 1937

By Charles H. Moore

In the study of the properties of rutile pigments it became apparent several years ago that certain physical and optical properties could not be determined on particles of pigmentary size. Since reflected light is the dominant type which reaches the eye from small particles, the true color of pure rutile was not known. Most rutile pigments are acicular in habit, elongated parallel to the "c" axis. It was considered important to know the nature and tone of light transmitted, for example, by a basal plate. Further, as shown by spectrophotometric curves, there is a very strong absorption of light of 4000 k as measured on particles with random orientation. It would be interesting to see whether this absorption position varied with predetermined and selected orientations. Also, since the behavior of titanium pigments in a vehicle is important, a knowledge of the surface wettability of single crystals by various media should prove very fruitful. Finally, the optical properties of rutile are such that it should show, in a single pure crystal, greater fire and brilliance than the diamond. Mineralogists had long speculated that this would be the case and curiosity was strong to produce a single crystal large enough to cut.

Jan 1, 1949

By F. S. McNicholas, R. L. Healy

NOTEWORTHY because of the amount of explosives used, the tonnage broken, and the wide range involved both vertically and laterally, was a large underground blast fired last November at the Hidden Creek mine, Anyox, B. C. Stoping methods and mining prac¬tices at the Hidden Creek mine have previously been described in the technical press. Earlier mining methods employed included shrinkage stoping, glory-holing, and "spiral" stoping. The latter especially has been a practice peculiar to the Granby company, having been used for years at its Phoenix mines and later at the Anyox property where conditions as to size of orebodies and strength of ground both in the ore and walls were similar. These methods all leave tremendous excavations supported at key points by pillars and braces that may only be safely mined by big blasts.

Jan 1, 1935

By Eugene Guccione

Australia could eventually become a major world supplier of uranium oxide-but how quickly that happens depends on the outcome of a highly complex and emotional battle among different special interests.

Jan 1, 1977

By Theodore Simons

The rapid and comparatively recent development of flotation has opened so fascinating a field for study and research that the older processes of gravity concentration no longer receive the attention they deserve. The early work of Munroe1 and Richards,2 and the more recent contributions by Clevenger and Coe,3 Laist and Wiggin,4 Ammon,5 Bardwell,6 Crowfoot,7 and Hayden8 to mention only some which have appeared in our own Transactions-and by Schulz,9 have furnished so much data that to offer something new seems a difficult task. It is still possible, however, to present known facts from a different point of view, and, with this in mind, the writer has undertaken to express basic principles of gravity concentration in terms of simple mathematics and mechanics; the conclusions thus reached will be found to correspond, in general, with those obtained by experimental methods. Rittinger, in his classic Aufbereitungskunde (1867), reached analogous conclusions by way of intricate higher mathematics, for which reason his interesting investigations have remained a sealed book to most of us. The writer hopes that a more elementary treatment of the subject, based in part on Rittinger's methods, may, arouse new interest in the study of basic principles.

Jan 7, 1922

By A. S. Appleton, M. B. Bever

The stored and expended energies of an Au-Ag alloy deformed in torsion were investigated as functions of strain, strain rate, and temperature. At room temperature, the stored energy, measured by tin solution calorimetry, increased linearly up to an intermediate strain, above which it was nearly constant; at 78 °K the relation was linear up to fracture. Approximate values of the energy stored at 4 OK indicate a rapid increase below 78 OK. The energy stored by specimens deformed successively at 4o and 78oK changed slowly with increasing second strain from the curve for energy stored at 4 OK (measured after annealing at 78oK) to that for deformation at 78°K. The ratios of the stored to the expended energy at room temperature and 78 oK were unusually large. The additional amount of energy stored at the lower temperature is attributed mainly to an increase in the number and energy of dislocations. The stored energy as a function of strain rate at 4oK (measured after annealing at 78oK) increased to a sharp maximum over a narrow range of strain rates, whereas the expended energy changed only slightly. These effects are explained by the generation of point defects resulting from the enforced nonconservative movement of jogs in fast moving screw dislocations. The effect of straining successively at two strain rates at 4oK was also investigated. Stress-strain curves for 4o, 78oK, and room temperature and the results of micro examination of specimens deformed at these temperatures are also reported. THIS investigation is a continuation of a research program primarily concerned with the effects of variables on the energy relations involved in the deformation of metals. The variables investigated in earlier work have included strain, strain rate, temperature of deformation (room temperature and 78oK), and the type of deformation process. Most of this work has been carried out with Au-Ag alloys. In the investigation reported here, the deformation process was torsion, which had not been used previously in the program. The stored and expended energies involved in the deformation process were measured as functions of strain, strain rate and the temperature of deformation in the range 4" to 373" K. The microhardness and microstructure of deformed specimens were also investigated. The relation between stored energy and strain differs for different deformation processes.1,2 In general, the stored energy increases with strain and may attain a nearly constant value at large strains. This value and the rate at which it is reached, however, depend on the process of deformation. This dependence has been attributed, at least in part, to differences in the effective strain rate and rise in temperature of the specimen during deformation. The effects of the temperature of deformation on both the stored energy and the energy expended in the working process have been the subject of only a few investigations.3-6 Values of these quantities at low temperatures are of special interest as they yield information on point defects which, for many metals, is not obtainable at higher temperatures. The effect of the strain rate on the stored and expended energies has received little attention The strain rate has usually been measured only in relative terms, and hence the interpretation of its effect on the stored energy has been mainly comparative.

Jan 1, 1963

By J. J. Mike

During the past few years the combination of continuous billet casting with in-line reduction has been studied and several machines have been built with this capability included in the design parameters. (1,2,3,4,5) In-line reduction and continuous casting in combination are obvious and attractive. As pinch rolls are already in place for the continuous casting operation, it can be readily seen that a redesign of the mechanical and electrical equipment of the pinch rolls is all that is necessary to have in-line rolling. There have been numerous in-line reduction experiments conducted by simply increasing the pinch roll pressure on existing machines. (6,7,8,9) These generally failed to produce quality billets and often resulted in internal metallurgical defects (Figure 1).

Jan 1, 1972

By W. L. Zeigler

During the middle 1880's, shortly after the discovery of silver-lead ores in the Coeur d'Alene district of northern Idaho, it became apparent that concentration of the ores would be necessary to obtain a profitable product. Too much siliceous material was present for direct smelting, and the majority of the ores found at depth were too low in metallic content for economic smelting processes at the time. As the ores occurred in quartzite shear zones with siderite and quartz gangue, a large quantity of waste material was present in all the mines. As the galena was not finely disseminated, this made possible relatively good extraction of the argentiferous galena by coarse concentration. The first concentrators consisted mainly of coarse crushing, screening and jigging, principally by Harz jigs, the slimes being treated on buddles. Later Wilfley tables took the place of sand jigs and vanners superseded the buddles. Because of the marketing conditions, no attempt was made until 1900 to effect a recovery on the zinc minerals present, which were found associated in varying amounts with the galena. All through this period, the greater part of the production was obtained from mines containing ore assaying high in lead and low in zinc. Parts of some ore bodies would be reversed in this respect, so that ores high in zinc were left intact. During the decade after 1910, several important mines, The Success and The Interstate Callahan, containing ores high in zinc, were put into operation and were a material aid in the needed zinc production during World War I. Gravity concentration by jigs and tables was used during this period, with bulk flotation increasing in popularity for the treatment of the fine material that had already been treated by ordinary slime concentrating machinery. No extra fine grinding for flotation concentration was thought profitable at the time. Tailings Discharged into Streams From the start of mining and milling operations in this district until 1904, no attempt was made by the various mills in the upper district to impound or stack their tailings. They discharged them directly into the adjacent creeks or streams, to be carried away by high water. The Bunker Hill and Sullivan and the Last Chance mines, both in the relatively flat valley of the district, stacked huge piles of the coarse jig tailings on the near-by river bottom. Rain and snowfall are heavy in the Coeur d'Alene district, as it is on the heavily timbered Pacific slope of the Bitter Root Mountains. A heavy runoff occurs every spring and there is an occasional flood of disastrous proportions when warm "Chinook" winds accompanied by rain

Jan 1, 1949

For the past several years the policy of a large section of our mining industry in relation to our present bureaucratic form of government has become increasingly amusing, if not a little disgusting. In the past, mining men have always featured themselves the self-announced champions of free enterprise, and, generally, this conviction, was substantiated by their deeds. In recent years, however, a large group of the industry, while still expounding, from the front porch, the principles of free enterprise and a sound economy based upon the law of supply and demand, have gone around to the back door with palm extended, to join labor, farmers, bureaucrats, and other pressure groups to get their share of the take. The procurement of subsidies, bonuses, increased metal prices, and government assistance in a multitude of forms seems to have obscured from their thinking the welfare of the country as a whole and the sounder economic principles of a balanced budget and lower taxes. At the recent Colorado Mining Association convention in Denver, I. was alarmed to see just how far this specialinterest type of thinking has progressed within the mining industry. Government assistance to mining. was generally considered inadequate, and a flat bonus for any new mineral discovery was proposed. It was disquieting, too, to learn how far the federal alphabet agencies have entered into the mining industry and of the thousands of highly paid technical. men on the federal payroll required to man these numerous overlapping agencies and bureaus. Now all this is very fine, and some aspects of the federal give-away program can be very appealing to the unsuspecting in the mining industry as they have been to those in other groups. Some of these expensive programs may bring about a few dividends or even several new mines. But to this whole line of pump-priming reasoning there is one big disastrous fallacy.

Jan 1, 1952

By Herbert Hoover

THE Federation of Engineering Societies has been created for the sole purpose of public service. This initial meeting surely warrants some discussion of a few of the problems to which this organization, for expression of the --. engineering mind, can quite well give consideration. Some of the greatest of the problems before the country and, in fact, before the world, are those growing out of our industrial development. The enormous industrial expansion of the last fifty' years has lifted the standard of living and comfort beyond any dream of our forefathers. Our economic system under which it has been accomplished has given stimulation to invention, to enterprise, to individual improvement of the highest order, yet it presents a series of human and social difficulties for the solution of which we are groping. The congestion of population is producing subnormal conditions of life. The vast repetitive operations are dulling the human mind. The intermittency bf employment due to the bad coordination of industry, the great waves of unemployment in the ebb and flow of economic tides, produce infinite wastes and great suffering. Our business enterprises have become so large and complex that the old personal relationship between employer and worker has to a great extent disappeared. The aggregation of great wealth, with its power of economic domination, presents social, economic ills which we are constantly struggling to remedy.

Jan 1, 1920

By Robert Ammon

THE purpose of this paper is to present a brief sketch of the development of this hindered-settling classifier, but primarily to show the actual results obtained in practice with the classifier working on the Butte copper ores at the Boston & Montana Concentrator, at Great Falls and the Washoe Concentrator at Anaconda. The writer has endeavored to be as brief as possible, giving only the essential figures showing the efficiency of the classifier and leaving considerable interesting information to be derived by the reader from the statistics given. The paper deals with the practical work of the classifier under the following heads: 1. Desliming 4.0-mm. primary feed, overflow from 0.07 to 0.0 mm. 2. Desliming 1.25-mm. secondary feed, overflow from 0.07 to 0.0 nun. 3. Desliming Huntington Mill discharge, overflow from 0.07 to 0.0 mm. 4. Classifying 2.5-mm. deslimed secondary feed, overflow from 1.00 to 0.07 mm. 5. Classifying 2.5-mm. deslimed primary feed, overflow from 0.75 to 0.07 mm. 6. Classifying 4.0-mm. deslimed primary feed, overflow from 0.75 to 0.07 mm. 7. Classifying middling-tailing product from roughing tables, overflow coarse tailing. 8. Classifying 2.5-mm. trommel undersize, not deslimed, overflow from 0.75 to 0.0mm. 9. Remarks on the inner feel cone. In the following pages all overflows, are given in quartz dimensions; i.e., by a 0.75-mm. overflow 'is meant an overflow whose maximum particle is a 0.75-mm. quartz grain. By the term "slime" is meant all material which will pass through a 200-mesh screen whose average opening is 0.07 mm.

Jan 8, 1913

By Cleland N. Conwell

Intermittent coal mining has been conducted in Alaska for over a century. The first report of coal in Alaska was by the Veechy expedition of 1826 and 1827. Whaling ships used coal from Corwin Bluff near Cape Beaufort during the early and latter parts of the 19th century. The first coal mine in Alaska-and probably the oldest in the Pacific coast of North America-was opened by the Russians at Port Graham on the southwest tip of the Kenai Peninsula. The mine was operated from 1855 until 1867 when the United States took possession of Alaska. From 1880 to 1915 coal mining was carried on intermittently at several localities including Unga Island, Herendeen Bay, Chignik Bay, Kachemak Bay, and several points along the Yukon River. Small coal mines along the Yukon River provided fuel for the river steamers traveling from St. Michaels to Whitehorse. The area of sustained coal production began with the completion of the Alaskan Railroad from Anchorage to the Matanuska coal field in 1916 and to the Nenana field in 1918. Coal production continued to increase until 1953, at which time the oil and gas fields in Cook Inlet were developed. Oil and gas eventually replaced the Matanuska coal as a means of providing heat and power. The military in the Anchorage area shifted from coal to oil in 1967 causing a decrease in production. The increased demand for electric power in the Fairbanks area offset the decline and coal production started to increase. In 1969-1970 the Golden Valley Electric Assn. (GVEA) constructed a mine-mouth power plant 70 miles southwest of Fairbanks near Healy and a power line to Fairbanks. Location of Coals in Alaska Coals are found in all geographical subdivisions of Alaska. Coal in Alaska ranges in age from Carboniferous to Tertiary, and grade from lignite through anthracite. Fig. 1 shows the locations of Alaskan coal fields. The only fields that have been developed extensively are the Matanuska and Nenana. Fig. 2 illustrates the annual production of coal in Alaska and the ratio of underground to strip mining.

Jan 1, 1973

By V. I. Purcell, S. C. Sun. R. E. Snow

A study including effects of 7) pH value, 2) fatty acid collector, 3) fuel oil, 4) interfering ion, 5) particle size, and 6) operational variables. Test results indicate feasibility of fatty acid flotation under certain restrictive conditions. FATTY acids have been used as standard collectors for floating the matrix1-8 but not the leached zone phosphate ores. After a series of investigations, Davenport9 and Tarbutton10 concluded that the Florida leached zone ores tested were unamenable to fatty acid flotation and must be upgraded by floating the siliceous gangue with Armac-T as collector. The cationic flotation was estimated11 to cost almost ten times as much as a fatty acid process that would ideally give the same flotation grades and recoveries of phosphates. Mineralization: Extensive deposits of leached zone aluminiferous phosphate occur in Florida."= The ore sample used for this work was obtained from the Virginia-Carolina Chemical Corp., Clear Springs area, Florida. The ore is a potential source of uranium and aluminum as well as phosphorus. Since the uranium and the recoverable aluminum are contained in some of the phosphate minerals, an upgrading of phosphate results in a corresponding enrichment of both uranium and aluminum. The phosphate minerals in the ore are primarily pseudo-wavellite, millisite, and carbonate fluorapatite, with a minor amount of wavellite. Quartz and clay are the common gangue minerals, quartz being predominant. Others present in small amounts are ilmenite, hydrated iron oxides, staurolite, monazite, and zircon. Experimental Procedures: After being dried to less than 1 pct surface moisture the material was dry-ground in a Hardinge conical ball mill to —6 mesh. The ground product was classified into 6/20, 20/200, and —200 mesh size fractions. On the basis of Table I, the coarse and fine size fractions were considered as phosphate concentrates, because of their high phosphorus contents. In contrast, the 20/200 mesh fraction, which was low in phosphorus, was used as the flotation feed. All the flotation tests, unless otherwise stated, were performed in a laboratory Fagergren machine under the following conditions: 1) 400 g of solid feed for each test, 2) 2000 rpm impeller speed, 3) 8.9 pH and 4-min conditioning, and 4) 3-min flotation. The procedure used for the quantitative bubble pick-up tests has been described previously.18

Jan 1, 1958

By THOMAS G. FEAR

THE COAL DIVISION started its share of the annual meeting Monday morning with a study of coal classi fication. A. C. Fieldner was in the chair. The report of the tellers of the ballot for division chairman, stating that Thomas G. Fear had been elected to that office, was read by M. D. Cooper. Mr. Fear acknowledged the honor in a few words. In reviewing the history of the Coal Classification Committee the chairman pointed out that this was its third symposium, the last previous one having been held at the 1930 Annual Meeting. Throughout its work the com¬mittee has had the active cooperation of the Canadian workers who are interested in the subject which should result in a uniform scheme of classification in Canada and the United States. F. E. Lathe, of the National Research Council, Ottawa, abstracted the first two papers of the session entitled "Determination of the Alkali-Soluble Ulmins in Coal," by Edgar Stansfield and K. C. Gilbart, and "Moisture Determination for Coal Classification," by the same authors. The third paper "Condition of Water in Coals of Various Ranks"' was presented by its author, A. W. Gauger. Written discussions of these papers were presented by H. C. Porter and Gilbert H. Cady. In the oral discussion which followed, W. T. Thom, Jr., brought out the advisability of considering age as a factor in classification. Mr. Fieldner favored retaining bed moisture as a partial classification basis, stating that a review of many coal analyses revealed a remarkable consistency in this item in samples from a given mine particularly where the moisture content was not high. Mr. Porter pointed out that the structure and porosity of coal often have much to do with its moisture content and that these vary in different parts of a seam, particularly in anthracite. Mr. Gauger expressed doubt as to whether the Stansfield method gives the true moisture content of coal, which is needed for classification purposes.

Jan 1, 1932

By G. R. Fritterer

Investigators in the field of temperature measurement have long sought a thermoelectric couple fulfilling the following requirements: 1. It should be useful up to and including high industrial temperatures; i. e., 1000 to 1800 C. 2. Its thermoelectric variation with temperature should be linear and be maintained after heating to high temperatures for long periods of time. 3. It should be reproducible; i. e., different couples of the same elements should have similar calibration curves. 4. Its thermoelectric power should be large so as to allow the industrial use of rugged recording instruments. 5. Chemical reactions with, and physical changes within the elements of the couple should not alter its calibration. No thermocouple proposed to date exhibits simultaneously all of these characteristics, whereas the couple about to be described fulfills all requirements to a satisfactory degree. New Thermoelectric Materials A thorough survey of the literature on thermoelectricity revealed that present-day thermocouples could not meet the specifications mentioned above because their thermoelements are metallic. Metals have a marked tendency to deteriorate chemically and their melting points limit their use to low temperatures. Refractory substances, however, are usually resistant to chemical attack and are quite stable at high temperatures. Hence a survey of refractory substances having thermoelectric possibilities was made. One class of thermocouples considered was that in which carbon and a carbide of some metal or nonmetal were the thermoelements. Previous investigators neglected to study this field but certain recommendations were made by them for the use of couples in which carbon served as one element. These proposals are listed in Table 1. The couples suggested are unsatisfactory because of their low thermoelectric powers, the low melting points of their metallic elements, etc. The

Jan 1, 1933

By Harry Seltz, J. C. DeHaven

InteRmetallic compounds are formed in many binary metal systems. Some compounds are stable to their melting points, and others decompose at lower transition temperatures. Even those of the first class are dissociated in the liquid state, as indicated by the continuous form of their solubility curves at their melting points1. While the lattice structures of some of these compounds have been determined, their thermodynamic properties have not been investigated. In this paper is described the determination of the free energy and heat of formation of the compound CdSb, which is of the first class mentioned above, melting congruently at 455' C. This compound shows a rhombic structure, and the lengths of the edges of the elementary cell containing four molecules are: a = 6.52, b = 8.60, c = 4.16 A.' There are three possible methods of determining the free energy of formation of a compound of this type. The first method, applying the third law of thermodynamics, requires the measurement of its heat capacity preferably to liquid hydrogen temperatures, and a calorimetric determination of its heat of formation. The second method involves the study of the equilibrium of the compound in some gas reaction, such as: CdSb + CO² = CdO + CO + Sb From the known free energies of formation of CdO, CO² and CO the free energy of formation of CdSb could be calculated. The third method measures the electromotive force of a galvanic cell in which the cell reaction is the reversible formation of the compound from the elements. The first method is generally applicable, but requires elaborate experimental equipment. The second method can not be used for compounds melting at low temperatures, owing to the difficulty in establishing equilibrium. The electromotive force method, therefore, seemed to offer

Jan 1, 1935

By J. C. DeHaven, Harry Seltz

InteRmetallic compounds are formed in many binary metal systems. Some compounds are stable to their melting points, and others decompose at lower transition temperatures. Even those of the first class are dissociated in the liquid state, as indicated by the continuous form of their solubility curves at their melting points1. While the lattice structures of some of these compounds have been determined, their thermodynamic properties have not been investigated. In this paper is described the determination of the free energy and heat of formation of the compound CdSb, which is of the first class mentioned above, melting congruently at 455' C. This compound shows a rhombic structure, and the lengths of the edges of the elementary cell containing four molecules are: a = 6.52, b = 8.60, c = 4.16 A.' There are three possible methods of determining the free energy of formation of a compound of this type. The first method, applying the third law of thermodynamics, requires the measurement of its heat capacity preferably to liquid hydrogen temperatures, and a calorimetric determination of its heat of formation. The second method involves the study of the equilibrium of the compound in some gas reaction, such as: CdSb + CO² = CdO + CO + Sb From the known free energies of formation of CdO, CO² and CO the free energy of formation of CdSb could be calculated. The third method measures the electromotive force of a galvanic cell in which the cell reaction is the reversible formation of the compound from the elements. The first method is generally applicable, but requires elaborate experimental equipment. The second method can not be used for compounds melting at low temperatures, owing to the difficulty in establishing equilibrium. The electromotive force method, therefore, seemed to offer

Jan 1, 1935

By A. F. Witt, A. M. Gaudin, A. K. Biswas

Finite contact angles in the rutile-water-organic liquid system are traceable to contamination or are due to addition of a surface-active agent. Finite contact angles are invariably accompanied by hysteresis.1-7 Besides surfactant concentration and pH, the nature of the organic liquid is found to be a factor influencing the magnitude of contact angle hysteresis. In a recent paper the authors have reviewed principles and applications of measurement methods for contact angles and their hysteresis.22 In this paper, these methods are applied to a system consisting of rutile, an organic liquid (benzene, decane, or dode-cane) and water. Surfactant (dodecylamine hydro-chloride) was used at various concentrations and various pH values. MATERIALS A synthetic rutile crystal supplied by the Linde Co. was used. It is a cylinder 1/2 in. diam, with faces cut perpendicular to the c-axis. The crystal is stated to be alumina-free and to be 99.9% pure. Rutile is a high surface energy solid, its calculated average field strength being 2.7 x 105 e.s.u.,9 its dielectric constant10 is 114. The zero point of charge of rutile was measured11 and found to be at pH 6.0. The atomic distances and bond angles of the tetragonal crystal of rutile have been precisely determined.l2 The organic liquids were specially purified. Reagent grade benzene was repeatedly shaken with concentrated sulfuric acid to remove thiophene, then neutralized with sodium hydroxide solution, rinsed with distilled water, dried overnight over anhydrous calcium chloride and filtered. The refractive index of this chemically purified benzene was 1.4977 (at 25°C) - very close to that of pure benzene (n25 1.4979).13 Both n-decane and n-dodecane were washed with aqueous sodium hydroxide, concentrated sulfuric acid (repeatedly, until the acid layer was colorless) and again with alkali, to free the organic hydrocarbon from fatty acids and unsaturated hydrocarbons. The organic phases were subsequently washed with distilled water and dried over anhydrous sodium sulfate. The filtered hydrocarbons were then distilled under vacuum (9-10 mm pressure). Decane, thus purified, showed traces of unsaturated and of carboxylic compounds. On gas chromatographic analysis the purified n-dodecane showed the presence of two impurities. However, the relative retention times of these components did not change substantially when measured on a polar or a nonpolar column. This indicates that the compounds were probably in the same polarity class, i.e. the components were nonpolar like dodecane. Conductivity water has always been one of the liquids. Conductivity of the water used was 10-6 ohm-' cm". Dodecyl ammonium chloride was prepared from pure amine (supplied by Armour and Co., Chicago), by Li in the MIT Mineral Engineering Laboratory.14 The critical micelle concentration at 25°C is known, 0.0138 mol per liter15 or 3.06 gpl. All our experiments have been done at concentrations lower than the critical micelle concentration. The glass vessels, glass drop holder and the rutile crystal were all cleaned with hot chromic acid followed by distilled water, concentrated hydrochloric acid, and again distilled water, and conductivity water. During the experiments, a nitrogen atmosphere was maintained. For this purpose, commercially purified nitrogen was further purified by passing it over hot copper wire at 450°C, then through columns of acidic chromous chloride solution, concentrated alkali solution and distilled water. APPARATUS AND METHODS Hysteresis was produced by the "captive drop" or constant volume drop method as well as by the "expanding-contracting drop" or variable volume drop method. The image of the drop while it is expanding, contracting or moving is projected on a screen and photographed. The developed film is projected through an enlarger and the contact angles measured with a protractor.

Jan 1, 1964

By H. N. Lawrie

Introduction. THIS study was undertaken on account of the lack of definite knowledge concerning the influence of bismuth on wire-bar copper, and the small elimination of bismuth from copper-matte during the smelting-operations. The early workers who studied the influence of bismuth on copper confined their investigations to malleability and ductility-two physical properties which are related to the others so intimately that their determination is of primary importance. Karsten ' and Levol,2 using bending- and mealleability-tests, seem to have been the first to take up the subject, and while their results are incomplete, they agree in the main with the later work of Hampe.3 The bending-tests used by the first investigators consisted in bending the specimen until it failed. The malleabilitytests were made by beating the material to a knife-edge with a hammer. Hampe not only determined the percentage of bismuth which would cause red-shortness and cold-shortness of the alloy, together with other influences of bismuth on the malleability and ductility of copper, but also took up the influence of the bismuth protoxide, BiO, on copper, and of bismuth sesquioxide, Bi2O3, on the copper protoxide, CuO. Hampe's conclusions of the influences of these two latter compounds of bismuth on copper are as follows "If the protoxide of bismuth be alloyed with metallic copper, it is not changed to metallic bismuth, but remains mechanically distributed throughout the copper.

Sep 1, 1909