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By S. Yukawa, M. J. Sinott

The low solubility of bismuth in copper and its segregation at copper grain boundaries with resulting embrittlement is well known.1-3 The heterogeneous diffusion of liquid bismuth into polycrystalline copper has also been studied.4 This work presents some further observations on these phenomena using high-resolution auto radiography to detect the presence of bismuth in copper polycrystalline and bicrystal specimens. The auto radiographs were made by the stripping film technique which produces an autoradiograph that is intact with specimen surface and can be examined simultaneously with the under-lying microstructure. The details of the technique have been described previously.3 In one series of experiments, high-purity copper was alloyed with 0.02 to 0.03 wt pct radioactive bismuth obtained from the Oak Ridge National Laboratory. Melting and casting was done under a

Jan 1, 1960

By Erwin S. Sperry

The oxidation of metals melted in contact with air takes place with dissimilar results. Tin, lead or zinc are examples of a class, the oxides of which float on the surface of the melted metal. First a film is produced, which covers the surface; then, if agitation from any cause exposes new metal to the action of the air, additional oxidation takes place, and the film is increased in volume. This change goes on until a considerable quantity of oxide (or " dross," as it is technically called) is formed; depending, of course, upon the duration of the exposure of the metal to the atmosphere. When such metals are poured, the dross may be skimmed off; and clean metal will be left underneath. The removal of such oxides is, therefore, merely a mechanical process. In the case of copper, however, the result is quite different. The sub-oxide of copper (Cu2O) is readily soluble in molten copper; and therefore, instead of the formation of a film of oxide, to be finally removed as dross, the surface of the metal remains bright and clear, because the oxide has been dissolved as soon as it was produced. It is customary in the process of copper-refining to leave a small quantity of oxide in the metal, in order to oxidize any traces of bismuth, arsenic or antimony which have not been entirely removed. As a result, these metals exist in the commercial product as oxides, and not as metals, which would form an

Jan 1, 1901

By Milton H. Ward

INTRODUCTION Historically, planning a mine involved the economic decision of whether to mine by open-pit methods or underground methods. The method selected was influenced by a number of factors, including size, tenor, and location of the deposit. If the project could not be justified by either underground or open-pit practices, it remained in fallow until economic conditions changed or technology advanced. Technology has advanced and the mining industry now has another option, that of in situ leaching. This method is on the threshold of becoming a commonly used alternative for production in many types of metal and mineral deposits. It will be utilized as the primary method for developing an ore body or as an adjunct to open-pit or underground operations. The following considers application of the technique to a deposit that had been partially exploited by open-pit methods. HISTORY The Big Mike Copper Mine is located approximately 30 miles south of Winnemucca, in Pershing County, Nevada. Interest in the property dates from the turn of the century, but little exploration was undertaken until the mid '60s. In 1967 Cerro Corporation acquired the property and initiated a major drilling effort. Ranchers Exploration obtained the property after this exploration program in late 1969 and confirmation drilling was undertaken. The deposit was delineated and it was determined that reserves amounted to about 100,000 tons of 10.0% massive copper sulfide ore and 700,000 tons of 2 .O% mixed oxide-sulfide ore. The ore body was a lenticular deposit, dipping at 50°. The massive sulfide mineralization was chalcocite and

Jan 1, 1974

By E. C. Reed

Ninety wells were completed in Nebraska during 1941, of which 42 were producers. One of them was the discovery well of a new field. All of the production to date is in Richardson County. At the close of the year 14 wells were drilling and three more were shut down for orders, hoping for future development of production. Most of the drilling activity was in Richardson County, which had 68 operations; 10 wells were drilled in Nemaha County, 5 drilled or drilling in Gage County, 3 each in Otoe and Furnas Counties, 2 each in Cass, Harlan, Johnson and Sarpy Counties, and 10 wells were completed or drilling over the remainder of the state. The most important development of the year was the discovery in October of the Barada field, sec. 36, T. 3 N., R. 16 E.,

Jan 1, 1942

By E. C. Reed

Ninety wells were completed in Nebraska during 1941, of which 42 were producers. One of them was the discovery well of a new field. All of the production to date is in Richardson County. At the close of the year 14 wells were drilling and three more were shut down for orders, hoping for future development of production. Most of the drilling activity was in Richardson County, which had 68 operations; 10 wells were drilled in Nemaha County, 5 drilled or drilling in Gage County, 3 each in Otoe and Furnas Counties, 2 each in Cass, Harlan, Johnson and Sarpy Counties, and 10 wells were completed or drilling over the remainder of the state. The most important development of the year was the discovery in October of the Barada field, sec. 36, T. 3 N., R. 16 E.,

Jan 1, 1942

By V. Runolinna, R. T. Hukki

Preliminary separation of precious metals by flotation can offer a simplification of the conventional method of treatment of anode slimes. Laboratory flotation experiments show that rich gold and silver concentrate can be obtained with excellent recoveries. THE purpose of this paper is to present the results of an investigation into the possibilities of separating precious metals from anode slimes by selective flotation. The work was carried out at the State Research Institute in Helsinki, Finland. The sample of anode slimes tested was submitted by the Outo-kumpu Co. in Finland. In 1947 the average assay of filtered and dried anode slimes in the Outokumpu refinery in Pori was as follows: Au, 0.50 pct; Ag, 9.38 pct; Cu, 11.02 pct; Ni, 45.21 pct; Pb, 2.62 pct; Fe, 0.60 pct; Sn, 1.00 pct; Sb, 0.04 pct; As, 0.70 pct; Se, 4.33 pct; S, 2.32 pct; SO,, 2.17 pct; SiO2, 2.25 pct. The daily assay naturally varies considerably from the figures presented above. The present conventional method of treatment of anode slimes consists of the steps shown in the flowsheet in fig. 1. As seen from this simplified flowsheet, the present method of treatment involves many steps by which the components of the anode slimes are removed one after another until the main products, gold and silver, may be separated. Due to the small scale of operations, the above procedure is carried out in small batches requiring considerable amount of manual labor. If, however, the anode slimes could be treated in

Jan 1, 1951

By V. Runolinna, R. T. Hukki

Preliminary separation of precious metals by flotation can offer a simplification of the conventional method of treatment of anode slimes. Laboratory flotation experiments show that rich gold and silver concentrate can be obtained with excellent recoveries. THE purpose of this paper is to present the results of an investigation into the possibilities of separating precious metals from anode slimes by selective flotation. The work was carried out at the State Research Institute in Helsinki, Finland. The sample of anode slimes tested was submitted by the Outo-kumpu Co. in Finland. In 1947 the average assay of filtered and dried anode slimes in the Outokumpu refinery in Pori was as follows: Au, 0.50 pct; Ag, 9.38 pct; Cu, 11.02 pct; Ni, 45.21 pct; Pb, 2.62 pct; Fe, 0.60 pct; Sn, 1.00 pct; Sb, 0.04 pct; As, 0.70 pct; Se, 4.33 pct; S, 2.32 pct; SO,, 2.17 pct; SiO2, 2.25 pct. The daily assay naturally varies considerably from the figures presented above. The present conventional method of treatment of anode slimes consists of the steps shown in the flowsheet in fig. 1. As seen from this simplified flowsheet, the present method of treatment involves many steps by which the components of the anode slimes are removed one after another until the main products, gold and silver, may be separated. Due to the small scale of operations, the above procedure is carried out in small batches requiring considerable amount of manual labor. If, however, the anode slimes could be treated in

Jan 1, 1951

By Walter E. Lewis

Myriad problems face all of us in the next decade. Vietnam, poverty, and pollution are perhaps the most pres- sing. A lesser one but still vital to us as a Nation is the slow hut apparently relentless extinction of the mining, metallurgical. geological and petroleum engineer. Are we doomed to take our place in the crossword puzzle with the moa. to be defined like it as an "extinct bird"? Or can we reverse the trend perhaps, in the next decade? The plain fact is we are an endangered species, and must resign ourselves to virtual extinction in the 1970's unless the trend is reversed. Probably, many of us have felt the problem will solve itself if left in the in-basket long enough, believing, that the trend will reverse solely on the basis of demand for these disciplines. This approach has not worked up to now, it gives no promise of working in the future, and furthermore, the problem has been in the in-basket much too long. The point is simply this: What can each of us do as an individual, or as part of a company, a State agency, a Federal agency, a university, or an organization such as AIME?

Jan 1, 1970

Meeting of May 22, 1914.-President Thayer. announced the appointment of the following Committee on Arrangements for the San Francisco meeting of 1915: Charles W. Merrill, Chairman; F. W. Bradley, Abbot A. Hanks, S. B. Christy, and H. C. Hoover. President Thayer announced the appointment of the following Committee on Organization for the Utah-Nevada Local Section: R. C. Gemmell, Chairman; C. D. Blood, Lafayette Hanchett, Ernest Gayford; Duncan MacVichie, and George W. Riter. The President of the Institute offered $100, to be known as the "President's Prize," to be used as prizes for the best papers submitted by members of the Affiliated Student Societies, to be divided as follows: First Prize, $50; Second Prize, $30; Third Prize, $20. A committee, consisting of J. F. Kemp, Chairman; W. L. Saunders, and T. T. Read, was appointed to report on the conditions to govern the award. The President announced the appointment of the Committee on Mining and Milling Methods, the personnel of which is shown on a subsequent page of this Bulletin. The following were appointed on the Advisory Committee to the U. S. Bureau of Standards, to represent the manufacture of the various non-ferrous metals as indicated: Copper, F. L. Antisell; Nickel, David H. Browne; Lead, H. O. Hofman; Aluminum, J. W. Richards; Zinc, G. C. Stone. It was voted to hold a meeting of the Institute under the auspices of, the Iron and Steel Committee, the Committee on Petroleum and Gas, and the Committee on Coal and Coke, in Pittsburg, Pa., Oct. 8, 9, and. 10, 1914.

Jan 7, 1914

[Paragraph No. PREFACE ON ASSAYING I BALANCES AND WEIGHTS 2 Balances required for Assaying 13 How assay Weights are made 3 Assay Weights based on the Centner 18]

Jan 1, 1949

ADVANTAGES OF LIFE MEMBERSHIP The Institute calls the attention of members to the following advantages of obtaining life membership: 1. One payment avoids the trouble of future payments. 2. The interest on $150 is less than the annual dues. 3. Provision is thus made early in life for the less productive years. 4. In case of in increase of clues at any time in the future life members are exempt from increased payments. Excerpt from, By-Laws. Article III. Section 3 Any Member or Associate not in arrears may become, by the payment of one hundred and fifty dollars at one time, a Life Member or Life Associate, and shall not be liable thereafter to pay annual dues. The money thus received shall be invested and only the income thereof used for current expenses of the Institute.

Jan 1, 1916

1. List of Manuscripts Seen in America 2. List of Manuscripts Seen in England 3. List of Maps Examined 4. List of Newspapers Examined 5. General Bibliography - Numbered Reference List

Jan 1, 1942

By W. H. Bassett

IN the commercial annealing of cartridge brass there are four points regarding which definite data are essential. They have to do with the correct interpretation of grain count in its relation to annealing temperature and, incidentally, to Brinell hardness. These points are: 1. The comparison of the grain sizes of two cartridge-brass mixtures: 69 copper, 31 zinc, 0.376-in. (9.5-min.) gage; and 68 copper, 32 zinc, 0.130-in. (3.3-mm.) gage. 2. The comparison of the grain sizes of annealed metal that had previously been reduced by rolling varying amounts; for instance, 20.0, 36.6, 50.9, and 59.1 per cent. 3. The determination of standards for grain sizes on annealed brass of the composition 68 per cent. copper, 32 per cent. zinc and 69 copper, 31 zinc. 4. The comparison of grain size with Brinell hardness on identical samples of annealed metal. In their comprehensive and thorough investigation of the recrystallization of cold-worked alpha brass on annealing,1 Mathewson and Phillips have discussed the relations between temperature of anneal, degree of deformation, and structural alteration in alpha brass. They have also shown certain comparisons between the ordinary physical properties and the grain size of annealed brass. The purpose of the present investigation is mainly concerned with the grain size of cartridge brass, its relation to Brinell hardness, and the publication of sufficient data to enable those engaged in the inspection of such material to have a correct foundation upon which to work.

Jan 1, 1919

By M. E. Wadsworth, K. C. Bowles, H. E. Flanders, R. M. Nadkarni, C. E. Jelden

The kinetics of precipitation of copper on iron of various purity were carried out under controlled conditions. The rate of reduction has been correlated with such parameters as copper and hydrogen ion concentration, geometric factors, flow rate, and temperature. The character of the precipitated copper as a function of flow conditions and rate of PreciPitation has been observed under a variety of conditions. ThE precipitation of copper in solution by cementation on a more electropositive metal has been known for many years. Basile valentine' who wrote Currus Triumphalis Antimonii about 1500, refers to this method for extraction of copper. Paracelsus the Great2 who was born about 1493 cites the use of iron to prepare Venus (copper) by the "rustics of Hungary" in the "Book Concerning the Tincture of the Philosophers". Agricola3 in his work on minerals (1546) tells of a peculiar water which is drawn from a shaft near Schmölnitz in Hungary, that erodes iron and turns it into copper. In 1670, a concession is recorded4 as having been granted for the recovery of copper from the mine waters at Rio Tinto in Spain, presumably by precipitation with iron. Much has been published in recent literature on the recovery of copper by cementation, the majority of the articles being on plant practice.5-24 The rest include articles on investigation of the variables involved25-28 and a review of hydrometallurgical copper extraction methods." This literature has established: a) The three principal reactions in the cementation of copper are Cu + Fe — Fe+4 +Cu [ 11 One pound of copper is precipitated by 0.88 lb of iron stoichiometrically. In actual practice about 1.5 to 2.5 lb of iron are consumed. 2Fe+3 + Fe — 3Fe+2 [21 Fe +2H'-Fe+2 + H2 [3] Reactions [2] and [3] are responsible for the consumption of excess iron. Wartman and Roberson'28 have established that Reactions [ I] and [2] are concurrent and much faster than Reaction [3]. b) Acidity control is important in the control of hydrolysis and the excessive consumption of iron. he commercial workable range is approximately from pH = 1.8 to 3." c) Iron consumption is closely related to the amount of ferric iron in solution. Jacobi" reports that, by leaving the pregnant mine waters in contact wi th lump pyrrhotite (Fe7S8) for 3 hr, all the iron was reduced to the bivalent condition and scrap iron consumption was cut to 1.25 lb scrap per pound of copper precipitated. He also reported that SO2 has been used successfully to reduce ferric iron to the ferrous state. d) The ideal precipitant is one that offers a large exposed area and is relatively free of rust. e) High velocities and agitation show a beneficial effect upon the rate of precipitation, as it tends to displace the layer of barren solution adjacent to the iron and also dislodges hydrogen bubbles and precipitated copper to expose new surfaces. Little work, however, has been published on the reaction kinetics of copper precipitation on iron. Cent-nerszwer and Heller20 investigated the precipitation of metallic cations in solutions on zinc plates. They found the cementation reaction to be a first-order reaction. The rate constant was independent of stirring for high stirring rates and they concluded that the rate is governed by a diffusional process at low stirring speeds and by a "chemical" process at higher stirring speeds where the rate reaches a constant value. This conclusion has been challenged by King and Burger30 who could not find any region where the rate was independent of the stirring speed, although the rate constant they had obtained for high stirring speed was greater than the maximum value of the rate constant reported by Centnerszwer and Heller (by a factor of six). King and Burger, therefore, concluded that the rate of displacement of copper was controlled only by diffusion. Cementation of various cations on zinc has been summarized by Engfelder.31 APPARATUS A three-necked distillation flask of 2 000-mm capacity was used as a reaction vessel. A pipet of 10-mm capacity was introduced through one of- the side necks, the sample of sheet iron, mounted in a rigid sample holder, through the other, the stirrer being in the middle as shown in Fig. 1. The whole assembly was immersed in a constant-temperature bath. The stirrer was always placed at the same depth in the solution. EXPERIMENTAL PROCEDURE Reagent-grade cupric sulfate (J. T. Baker Chemical Co., N.J.) was used to make up a stock solution containing 10 g of copper per liter which was then diluted to various concentrations as required. Experimental data were obtained by measuring the amount of copper and iron ions in solution at successive time intervals. The initial volume of the solution was always 2000 ml, 10-ml aliquots being removed each time for chemical analysis. Because the total volume change of the solution was less than 10 pct, no correction was used for solution volume change. Nitrogen was bubbled through the solution before and

Jan 1, 1968

By C. A. Heiland, W. H. Courtier

The investigations described were made on a portion of Clear Creek basin near Golden, Colo. (-4 portion of the area under survey is shown in Fig. 1. The photograph was taken in the vicinity of station No. 2 of Line 11.) Three principal purposes were in the minds of the investigators: 1. To repeat with modern, more sensitive and more reliable instruments magnetometric placer investigations previously made. 2. To disprove the recently advanced theory that deposits of the glacial period have no pronounced magnetic effects. 3. To develop in detail the theory of the magnetic effects produced by placer deposits. Six years ago, the first magnetic observations were published, which proved that it is possible to locate gold-bearing channels with relatively crude instruments.' Two years ago, K. C. Laylander published results obtained with similar instruments.2 The measurements of the latter were discussed by the senior author of this paper.3 At that time, however, the material available for such a discussion was somewhat scarce and not made with the most modern magnetic instruments, although very brilliant results were obtained. Therefore, the senior author felt that magnetic investigations should be made on very clear geologic conditions with the most modern instruments. Comparison of Magnetometers The junior author undertook this work in the spring of 1928. The magnetic field balances, for vertical and horizontal intensities, designed by Schmidt were used (Figs. 2 and 3). The scale value of these instruments was approximately 257 and 157, respectively. The middle

Jan 1, 1929

By Sheldon P. Wirnpfen

AN extensive study of German underground manufacturing experience is being undertaken by the Air Materiel Command. Headquarters officials consider completely underground facilities one of the most effective means of protecting aircraft production against air attacks of the strength and type employed in World War II. Advantages accruing to underground manufacturing installations other than protection are, perhaps, a smaller maintenance problem and the possibility of using gravity flow on some production lines. Offsetting these advantages are the high cost of construction, problems of ventilation, and poor acoustics. Excavation costs might well be less than the cost of enclosing the same area on the surface, as new and better methods of rock drilling and transportation are developed. Certainly the amount of building materials used would be far less than in constructing a surface plant of the same dimensions. A fewer number of skilled workers would be required to perform the labor of excavation. Underground construction would

Jan 1, 1947

By AIME AIME

IN A STATEMENT summarizing general conditions in the Federated American Engineering Societies, the executive secretary, L. W. Wallace, expresses the belief that the Federation has made substantial progress. At the annual meeting of the American Engineering Council, to be held in Washington Jan. 5 and 6, this progress will be shown by reports covering activities in many fields. "Unquestionably," says Mr. Wallace, "the Federa¬tion has made favorable and permanent contacts in Washington. Through the, activities of Congress and of the new Federal administration. we have had the opportunity to render some really constructive service. We feel, however, that the great body of engineers are not adequately informed of the organization of the Federation, of its aims and purposes and of its activities.

Jan 1, 1921

By M. H. Waxman, L. J. M. Smits

A simple physical model was used to develop an equation that relates the electrical conductivity of a water-saturatedshaly sand to the water conductivity and the cation-exchange capacity per unit pore volume of the rock. This equation fits both the experimental data of Hill and Milburn and data obtained recently on selected shaly sands with a wide range of cation-exchange capacities. This model was extended to cases where both oil and water are present in the shaly sand. This results in an additional expression, relating the resistivity ratio to water saturation, water conductivity and cation-exchange capacity per unit pore volume. The effect of shale content on the resistivity index - water saturation function is demonstrated by several numerical examples. INTRODUCTION A principal aim of well logging is to provide quantitative information concerning porosity and oil saturation of the permeable formations penetrated by the borehole. For clean sands, the relationships between measured physical quantities and porosity or saturation are well known. However, the presence of clay minerals greatly complicates log interpretation, particularly the electrical resistivity and SP logs, and considerably affects evaluation of hydrocarbon-bearing formations. The conductance and electrochemical behavior of shaly sands and their relation to log interpretation have been studied by many workers. wylliel and Lunch2 reviewed this work in some detail. Virtually all laboratory measurements of electrical resistivity and electrochemical potential of shaly sands published to date are the work of Hill and Milburn.3 Their measurements were made on about 300 cores covering a large variety of sedimentary rocks, and a wide range of equilibrating NaCl solution concentrations. Hill and Milburn described their conductivity data by an empirical equation in which the shaly sand conductivity Co was expressed as a function of the solution conductivity C and two parameters b and F01 . The quantity b was shown to be a measure of the effective clay content of the rock, being approximately proportional to the cation-exchange capacity of the rock divided by its pore volume. The latter ratio is designated as 9, in this paper and has the dimensions meq/ml or equiv/liter. Qv is identical with the term representing the concentration of fixed charges in the Meyer-Sieved and Teorel15 theory of permselective membrane behavior. F01 is a formation resistivity factor referred to a hypothetical equilibrating solution resistivity of 0.01 ohm m at 25C,* where clay effects presumably are minimized. F01 was correlated to porosity by an Archie-type equation.6 The Hill-Milburn equation describes their data with a standard deviation of approximately 1 percent and a maximum deviation of + 10 percent. Shaly sands behave as permselective cation-exchange membranes, their electrochemical efficiencies increasing with increasing clay content. The electrochemical potential data of Hill and Milburn were expressed graphically, and demonstrate that the membrane efficiency (or cation transport number) of these sands is a function only of the b value (i.e., Qv) and the respective salt concentrations of the two solutions forming the liquid junction in the sand. The diffusion potentials are not dependent on F01 or any parameter relating to the porosity or pore geometry of the rock. The Hill-Milburn resistivity equation correctly predicts a decreasing sand conductivity Co with decreasing solution conductivity C?. However, at some low value of C,, the calculated Co-C, function goes through a minimum; with further decrease in C?, the predicted sand conductivity increases sharply. As pointed out by Hill and Milburn, an increasing value of Co with decreasing C, is physically meaningless. Since this occurs below the range of practical values of C,, the usefulness of the empirical equation is not affected when

Jan 1, 1969

By O. D. Gonzalez, R. A. Oriani

The migration of hydrogen and of deuterium dissolved in a iron and in nickel induced by an applied electrical potential has been measured over a range of temperature. In all cases the intevstitial solute migrates to the cathode. The deduced charges of transport are positive, independent of or slightly dependent on temperature, and markedly larger for the beavier mass. These results are interpreted as showing predominating momenlum transfer between electron holes and the acticated complex of the elementary diffusion act. THE migration of components of a metallic system under the action of an applied electrical potential is called electromigration or electratransport. This phenomenon has been known since 1861 and is becoming of increasing interest to metal scientists because of the opportunity it offers to explore the connections between mass transport and electron transport. Until recently, reliable data have been very scarce because of the difficulties inherent in the measurements. In addition, theoretical understanding has been either nonexistent or rudimentary and at present this situation is only moderately improved. Whereas the prevalent notion had been (and is still widely held) that electromigration directly reflects the state of ionization of a component in its equilibrium state in the metal, it is now becoming clear that the major, if not the sole, factor is the momentum transfer between the charge carriers, themselves in motion because of the applied field, and the metallic components in their activated state. It becomes important therefore to obtain reliable data over a range of temperature on electrornigration in systems where only one component moves, that is, either in pure metals (vacancy motion) or in interstitial solid solutions. Our choice of systems was dictated by our measurements' of the Soret effect in solid solutions of hydrogen and deuterium in iron and nickel. Indeed, the main reason for making measurements on electromigration at all is that we suspected a mechanistic connection between thermal diffusion and electromigration. In our former paper' we proposed that what is common to both phenomena is the momentum transfer between the charge carriers in the metal and the atom as it jumps from one equilibrium position to another. In Soret diffusion, however, there is in addition the dissipation of the energy of the jumping atom via pho-nons. We have since found that similar ideas for this interconnection have been developed by Fiks.2 In the present paper we will discuss in more detail our understanding of the mechanism of electromigration itself, but we turn first to a presentation of the experiments and results. EXPERIMENTS AND RESULTS Let us consider a metallic system in which only one component, m , can diffuse at the temperature in question, and to which are applied simultaneously an electrical potential gradient, grad cp, and a chemical potential gradient, grad p,. One may write3 for the material flux Jm and the electronic charge flux Je by applying the condition, grad = 0, to Eq. [I] and evaluating grad(um/T) for the isothermal case and for activity coefficient independent of composition over the relevant composition range. ere, c is the concentration and D the diffusivity of the mobile component. The experimental technique that we have used to measure Z* for the isotopes of hydrogen individually dissolved in each of two transition metals has been developed from a method used by Wagner and Heller.4 (A somewhat similar method was also used by Herold.5) A wire or thin rod of the metal under study connects two volumes of gaseous hydrogen at identical pressures; hence grad um = 0. A direct current is made to pass through the specimen, serving to maintain the specimen at the desired temperature and also to produce the electromigration of the hydrogen dissolved in the metal in equilibrium with the gaseous hydrogen. Under these conditions, the flux of hydrogen from one volume to the other is given, from Eq. [I] for grad( um/T) =0by

Jan 1, 1968

lv. H. Blauvelt, Great Falls, Montana (communication to the Secretary): In his remarks on Mr. Stetefeldt's paper (Trans., xxiii., 587)) Mr. Goetz observes: " Trouble experienced with producers at Great Falls influenced me to try Taylor producers instead of those of Wellman. But recent reports show that the Wellman producers work better, besides coating nearly 50 per cent. less than Taylor producers of equal capacity. Indiana and Illinois coals cannot be used in the Taylor producers by reason of the large size and hardness of the clinkers which they form." I think that Mr. Goetz must have been misinformed regarding the work of this producer in Illinois. One of the large mauafacturing concerns in that State, the Illinois Zinc Company, situated at Peru, which uses a coal mined in the vicinity, tried one Taylor producer, some four years ago, in competition with those of an older type, which it had been using. As a result of this trial, the company has now thirteen Taylor producers, which have been in operation for about three years. A recent report from these works says that the Taylor producers have largely reduced the loss of coal through the grate, and have also improved the quality of the gas, as compared with that produced from the same coal in the producers of the older type. This Illinois coal is, perhaps, the worst in the country for making gas; since, besides containing from 20 to 40 per cent. of ash, it carries a large quantity of pyrites, so that the clinkers are large and extremely hard, and the capacity of the producer is most severely tested.

Jan 1, 1895