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By Clemens Jones

A FORM of apparatus for volumetric determinations which shall possess the features requisite for the constant use of potassium permanganate, is a very desirable fixture in a well-appointed laboratory. Expedients to economize time and insure accuracy are generously employed for various other reagents, while the permanganate seems to have been consigned to the use of an ordinary burette, and a black bottle of the standardized solution. But the introduction of new, methods dependent on the permanganate, and the urgency of technical requirements where it has long been indispensable, require a revision of practice more scientific and convenient. The apparatus designed by the writer for the laboratory of the Thomas Iron Company at Hokendauqua, Pa., is so simply contrived and works with such entire satisfaction that a description of it may be of use. It may be prefaced that the characteristics of a suitable device offer some mechanical difficulties when combined in a continuous appliance. The burette, B (50 C.C. to 1/10 c.c.), shown in Fig. 1, consists of the graduated tube proper and an arm, E, fused to it below the 50 c.c. mark. At its top are rubber connections with the blast-aspirator, shown in the cut (Fig. 2) of the front view. By means of an extra stopcock, D, connection through E is established with the reservoir F. The burette is clamped Securely to a slide, C, which is counterpoised and moves freely on guides between two parallel sides, L, suitably

Jan 1, 1887

D. EPPELSHEIMER, * Middletown, Ohio.-The housing of employees has so many and so varied aspects that in order to reach even an approximately correct solution it is necessary to have in mind a few fundamental principles; but it is not possible as yet to write these housing principles in the clear and correct form that is possible with many of our natural laws. Manifestly, the problem depends first on the kind of people it is necessary to house. What is suitable for the Southern unattached negro is not suitable for the married skilled American. The influx of colored labor has affected quite a number of what were satisfactorily housed communities. The second important factor is the relative proportion of the number of employees to the total employable population of the community in which the industry is located. The employer of a hundred men in. a large city has little responsibility in the matter of housing his employees. If he employs 75 per cent. of the employable population in a community of 27,000, as is the case of the company with which the writer is connected, it means a large responsibility. In the establishment of an entirely new plant in a more or less isolated place, the responsibility becomes greater. As engineers, we design and write the specifications for the machinery to accomplish a definite purpose, and proceed to house it, provide the necessary buildings with their accessories in the way of cranes, or heating systems, or sprinkling systems, as the case may be. There is no reason why the operating force should not be built up in very much the same way: design the organization, write its specifications so that the employment department can secure the proper men, and then house that organization with just as much thought and care as is given the plant. In the plant, the various machines will work along certain definite lines and accomplish certain results; but even if we start with the proper organization it takes considerable time to get that organization working together. One of the most important elements to this end is the proper housing of the organization. A man usually spends more time at home than at work. Proper surroundings and a comfortable, convenient house of good appearance exercise an influence that cannot be denied, and an employee situated in such surroundings is far more inclined to follow the policies of his employer and take an active part in furthering them

Jan 5, 1919

By E. P. Whelan

A recent investigation1 into the origin of "ghost boundaries" in dilute Cd-Mg alloys has indicated the persistence of a segregated solidification substructure in spite of a homogenizing treatment designed to remove such segregation. Although no grain growth experiments have been reported on these segregated alloys, the homogenizing treatment used in grain growth studies on other dilute alloys2-7 is similar in

Jan 1, 1968

By Leonard Larson

DURING several years immediately preceding the adoption of wet-charge smelting at McGill, various necessary conditions affecting this procedure, such as plant rearrangement and the metallurgical nature of the concentrate produced at the concentrator, were fully considered. Wet-charge smelting is not altogether novel to the recently reconstructed smelter at McGill. A number of years prior to this improvement, when flotation methods were initiated at the concentrator, large tonnages of wet and (at that time) sticky flotation concentrate were charged directly into the reverberatory furnaces, because of the difficulty in handling the entire tonnage in the roasters. The plant had excess reverberatory units and this surplus furnace capacity was utilized to smelt raw flotation concentrate. During the years 1927 and 1928, a number of actual operating furnace test runs were made to determine in principle the feasibility of wet-smelting operation. Results were encouraging, and in November 1932 the roasting plant was shut down. For some time thereafter the wet feed was delivered directly to the reverberatory side-charging calcine hoppers already in place. Feeding the wet material through the old calcine hoppers and charge holes into the furnace involved considerable labor, but under the conditions existing at that time it was desirable to continue wet smelting even under the handicap of this laborious procedure. The smelting plant during this period was on a curtailed production basis, operating only about 15 days per month. The alternate starting up and shutting down of the roasting plant presented a difficult problem and charging the wet material directly to the furnace entirely eliminated this difficulty. The roasting plant was never operated thereafter. EARLY PROCEDURE Fig. 1 shows the general layout of the smelting plant before the smelter was remodeled. Under this arrangement, all concentrates and fluxes except converter flux were delivered in cars to wooden storage bins, which paralleled the roaster building. The material to be roasted was dis-

Jan 1, 1938

By Waldemar Dyrssen

BEFORE discussing the relation between air pre-heaters and waste-heat boilers in conjunction with the open-hearth furnace, it is necessary to have a clear idea about what a preheater can accomplish and what effect it has on the open-hearth furnace, especially from a thermal point of view. It is generally recognized now that the heating of the combustion air in the checker chambers of the open-hearth furnaces is not as efficient as it is-desirable to make it. It is also generally recognized that heating of the air in checker chambers of ordinary construction has its limitations. These limitations are mostly the .space occupied and the cost that would be involved if checker chambers were made larger than according to present practice. There are, however, other. reasons why checker chambers cannot give the highest possible air temperatures. Checker chambers are capable of heating air to very 'high temperatures by using waste gases of extremely high temperatures and, in fact, higher temperatures can be reached with checker chambers than with any other means available. The temperature to which we can heat, air, however, is limited very materially by -the temperature at which the air enters the checkers, be-cause of the fact that checker chambers, as at present constructed, are not efficient in heating air through a wide range of temperatures. In other words, if air in-stead of entering the checker chambers at atmospheric temperatures could enter at about 1000 to 1200 deg. F., the resultant air temperature at the top of the checker chambers would be materially increased. There are now on the market metallic air preheaters which are ex-tremely efficient for preheating air to about 1200 deg. F. Such heaters occupy very little space and can usually be installed at a relatively low cost.

Jan 1, 1928

By W. J. Reagan

Many factors enter into the manufacture of basic open-hearth steel of high quality. Perhaps the two most important are temperature and the iron oxide content of the metal. If we can control these two factors we can essentially control basic open-hearth practice. SOURCE AND EFFECT OF IRON OXIDE Earlier investigators, especially Herty and his associates, have shown that iron oxide is introduced into the open-hearth furnace in four ways:' 1. By oxidation of the scrap by furnace gases. 2. By decomposition of the limestone. 3. By oxidation of the iron oxide in the slag by furnace gases. 4. By direct addition of iron ore to the charge. We also know that the speed of operation of an open-hearth furnace depends, for a given charge and given combustion conditions, on the rate at which iron oxide will diffuse from the slag into the metal. The rate of diffusion depends upon a number of variables, such as iron oxide content of the slag, slag viscosity, etc., which also depend upon the amount of iron oxide in the metal, amount of carbon present, temperature, and so forth. For a given carbon and a given temperature, the iron oxide content of the metal is in proportion to the iron oxide content of the slag. This fact can be easily verified by analysis of slag samples taken as described by Herty.2 It is preferable to take these samples just before deoxidetion. In killing the steel samples with aluminum it is desirable to use aluminum rod of 99 per cent purity; ordinary commercial aluminum rod with a purity of approximately 92 per cent is not satisfactory. In drilling these samples it is also essential to take the largest amount of drillings possible. This gives more accurate results because it eliminates spotty segregation of A12O3.

Jan 1, 1932

By Clarence E. Killebrew

The key to the successful use of any tool, more than anything else, depends upon proper application assignment. To achieve this, the individual having such machine responsibility must maintain fresh knowledge of technical improvements that broaden machine uses. 8.3-1. Tractor Shovel. This type machine is available in a wide range of sizes mounted either on crawler tracks or rubber-tired wheels, with both two-wheel and four-wheel drive. The original concept in both crawler and rubber mounting was that of an attachment to be added to a tractor already in existence. This served as an important expedient for the introduction of the tool, but the basic tractor proved to be inadequately designed for the additional loads. In spite of these structural inadequencies, customer acceptance generated sufficient revenue that further development could be financed for product improvement. The evolution of the product is continuing in many ways-including engines, drive line components, tires, hydraulic pumps, hydraulic valves, structural steel, etc. With each improvement, the operating capability of the machine is extended. This is resulting in the rubber-tired, four-wheel-drive concept making an invasion of the job applications that were formerly considered suitable only for crawler-track mounted machines. Both rubber- and crawler-mounted tractor shovels have invaded the market of small excavator shovels. Larger tractor shovels are challenging the larger size excavators. It is important that each job application be carefully considered so that the proper machine is put in operation. The performance varies widely in operating cost, production efficiency, and job flexibility. Factors to be considered in equipment selection are: 1. Nature of material to be moved 3. Distance material must be moved 2. Surface over which material must be moved 4. Quantity to be moved 5. Secondary or alternate use capability

Jan 1, 1968

By L. T. Sanchez, W. T. Rogers

This paper presents the results of a production experiment evaluating the effect of the use of oxygen in the bessemer converter with respect to its relation to blowing time, amount of steel scrap or cold pig iron which can be melted and teeming temperatures of the molten steel. THE simplest and probably the most efficient and economical means for producing steel from molten pig iron is the bessemer converter. This process is essentially a mechanism for bringing oxygen into contact with the molten metal thereby oxidizing the elements silicon, manganese, and carbon. The source of oxygen is that contained in the air and is limited by that amount. In theory, there is an intermediate chemical reaction due to the mass action of iron and air which is represented by the equation: 2Fe + O2- = 2Fe0 The FeO then becomes the oxidizing agent and reacts with the silicon, manganese, and carbon to produce silicon dioxide (SiO,), manganese oxide (MnO), and carbon monoxide (CO), in the order mentioned. The balancing of the various chemical reactions shows that in the ordinary bessemer process more than sufficient oxygen is delivered to satisfy these reactions, which indicates that a further increase in the oxygen content of the air would serve no useful purpose. In spite of this reasoning, however, it will be demonstrated that when melting stelel scrap, commercially pure industrial oxygen introduced into the normal air blast will permit the melting of a larger proportion of steel scrap than is possible with air alone and also will increase the production rate by a substantial reduction in blowing time. It will also be shown that when melting cold pig iron, it is possible to melt up to twice as much pig iron with the use of oxygen as can be melted without added oxygen with a nominal increase in blowing time. At the plant where this study was made, oxygen is purchased from a nearby supplier and piped directly into the plant. It is supplied to the bessemer converter by being introduced directly into the blast line through an automatic control system which may be adjusted by the bessemer operator or "blower." Normally, iron is supplied by five blast furnaces to an open hearth shop containing twelve 165-ton capacity stationary furnaces and a bessemer converting shop having three 30-ton converters. The molten metal from the blast furnaces is allocated to one shop or the other in a manner to best provide for maximum production. At various times, it is desirable to direct the maximum amount of available blast furnace production to the open hearth shop. This has the effect of reducing the production of the bessemer shop. When this condition exists, it is desirable to supplement the reduced iron charge at the bessemer with steel scrap or cold pig iron to the maximum possible extent in order to maintain high total ingot production. This condition becomes aggravated when one of the blast furnaces is taken out of production for any repair job and particularly for extended periods such as when relining is necessary. The purpose of the investigation and experimentation with oxygen was to determine whether or not it would contribute to increased flexibility in the use of the raw materials, molten iron, steel scrap, and cold pig iron. In addition to the effect of oxygen on flexibility of operation, it was also necessary to determine the relation of its use to production rate or "blowing time," final finishing temperature of the steel or "teeming temperature," and steel quality.

Jan 1, 1953

By John Kafritsas

INTRODUCTION Deformations and failure of rock masses in elopes, foundations or tunnels can be caused by water pressures. On the other hand, deformations of a rock mass affect the flow of water (and hence water pressures) by changing joint apertures. Including the coupling between flow and deformation effects is therefore important both in assessing the stability and deformation of a rock mass and in determining the amount of seepage taking place through it. The model that will be presented hare treats the coupling of the flow and deformation behavior of a rock mass. Deformations are modeled using the Rigid Block Method (Distinct Element Method) (Cundall, 19741, that is by assuming that the rock mass is composed of rigid blocks with deformable contact points. Flow is modeled by recognizing its discontinuous features, as occuring in a system of interconnected conduits formed by the joints. The program can also deal with problems involving free-surface flow. Example problems involving representations of rock masses are presented. Coupled flow modeling of interconnected conduits should be contrasted to equivalent-continuum models on the one hand and to pipe network models on the other hand. Continuous models substitute an anisotropically permeable continuum for the discrete flow that occurs in rock joints. Pipe or parallel plates represent the other extreme of existing models; they account for the discontinuous character of the flow problem, but cannot model rock mass deformation and failure. The coupled rigid block-flow model can eliminate most of these restrictions. The coupling between water flow and deformation is most pronounced in rock masses which, because of the arrangement of their

Jan 1, 1984

By A. J. Lynch, N. W. Johnson, D. J. McKee

The behavior of nonsulfide gangue in chalcopyrite flotation circuits has been investigated. Plant and laboratory tests were conducted on five different ores. Linear relationships between the recovery rates of free nonsulfide gangue and water were observed. From pilot plant tests, there was evidence that the linear relationship was actually a linear approximation to a parabolic relationship. There was evidence that free nonsulfide gangue is transported from the pulp to the froth in the water and that the gangue is subjected to hydraulic classification in the froth column. A classification matrix has been proposed to define this behavior. This matrix is suitable for inclusion in a mathematical model of the process.

Jan 1, 1975

By James R. Russell

Rock bolts are commonly used to support and stabilize the rock around excavated openings. The assumption is made that the less competent rock near the surface can be supported by bolting it to more competent rock away from the surface. Naturally, a rock bolt can be no more effective than its anchoring mechanism which induces a stress field into the surrounding rock. Details of various types of bolts have been described e1sewhere.l The purpose of the present investigation is to study the stress distribution around an expansion-type rock bolt anchor, using the theory of elasticity. The elastic stress distribution provides some insight into the behavior of rock bolt anchors which may eventually lead to improved designs. Very little information is available on the induced stress field which is rather complex; consequently, photoelastic techniques have been used to obtain a qualitative picture of the stress ditribution.2 The present work provides quantitative information on the stress field induced by an idealized distribution of surface tractions, provided that the assumptions of the linear theory of elasticity are approximately satisfied. FORMULATION OF THE PROBLEM Consider an elastic region which extends to infinity and contains a circular cylindrical hole as shown in Fig. 1. The hole is assumed to be the bolt hole and the surface tractions shown are assumed to be caused by an idealized rock bolt anchor. The relationship between the idealized

Jan 1, 1972

By S. Usui, I. Matsuoka, H. Sasaki, J. Shimoiizaka

Depression of galena by sulfite or chromate ion in xanthate flotation was investigated by means of adsorption measurements, electron diffraction and flotation tests. Flotation of galena was depressed by sulfite ion only when galena had been oxidized; no depression took place with unoxidized clean galena. A similar behavior was found when chromate ion was used as a depressant, with the exception that the chromate ion depressed unoxidized clean galena around neutral pH. Depression was attained with galena on which xanthate still remained in appreciable amounts, indicating that the depression is not due to a decrease in xanthate adsorption. The galena surface produced sparingly soluble films under conditions in which depression of galena took place. These films were identified by electron diffraction as lead sulfite and lead chromate on oxidized galena and as chromic oxide on unoxidized clean galena. These observations in conjunction with contact angle measurements, indicate that the depressing action of sulfite or chromate ion arises primarily from film deposition resulting from the reaction between depressants and the galena surface. The thickness of the film was analyzed by means of electrochemical polarization.

Jan 1, 1976

By J. D. Lubahn, R. P. Carreker, J. G. Leschen

THE formation of slip bands in crystalline solids undergoing plastic deformation has recently been treated as a problem of nucleation and growth.1 A simplified theory was developed and shown to be qualitatively consistent with certain experimental observations reported in the literature, such as the frequent failure of slip bands to traverse the entire crystal, the effect of specimen diameter and temperature on the yield stress, and the occurrence of incubation periods in the deformation of suddenly loaded crystals. The theory further predicts the appearance of transients in the rate of strain of a crystal when the applied stress is suddenly changed from one constant value to another. A transient consists of a discontinuous change in the strain rate followed by a gradual approach to a steady-state value. Such transient behavior apparently has not been recognized in previous experimental work. The preliminary experiments reported in the present paper were undertaken to confirm the existence of the predicted transients and thus to determine whether a more detailed treatment of the nucleation theory of slip might be theoretically and experimentally fruitful. EXPERIMENTAL PROCEDURE A simple creep apparatus was assembled as shown in Fig 1. Very little insulation was used on the furnace in order to facilitate rapid changes of temperature. Temperature was measured with a thermometer placed in the center of the furnace and was [ ] controlled by adjusting the Variac setting. The specimens were cold-headed in split-cylinder grips. The strain was measured as total elongation by a dial gauge sensitive to 1/10,000-in. movement of the weight pan. Since the specimen gauge lengths were

Jan 1, 1948

By Howard Scott

The great advances made in mechanical engineering during recent years through the use of alloy steels, as illustrated by the development of the airplane and automobile, may be ascribed primarily to the application of nickel as an alloying element. The ternary system iron-carbon-nickel has a wide industrial application and forms, further, thefundamental basis of the even greater class of the widely used quarternary steels such as nickel-chromium, nickel-silicon, and nickel-vanadium. As is not uncommon with such cases of virile growth in an industry, the application of the alloy steel in a largely empirical manner has outstripped its scientific development so that a fertile field for metallographic research still remains. In this field, the basic nickel steels require first consideration and are the subject of the present investigation, which is offered as a preliminary to the study of the more complex alloys of industrial importance Of the principal tools of metallography—microscopic examination, determination of mechanical properties, and thermal analysis—the last has developed much more slowly in its application to industrial needs so that the situation often exists that heat treatment operations are based on empirically determined temperatures; that is, temperatures deterrnincd without regard to the actual transformation characteristics of the alloy. This situation is undesirable as there is no uniform standard for comparison of results. It is due, outside the usual difficulties involved in temperature measurements, to the pioneer character of much of the published work; to the lack of definiteness of the Ac, transformation,1 particularly in low-carbon steels; to the failure to define operating conditions completely; and to the paucity of information correlating thermal characteristics with results of heat treatment.

Jan 1, 1922

By Howard Scott

The great advances made in mechanical engineering during recent years through the use of alloy steels, as illustrated by the development of the airplane and automobile, may be ascribed primarily to the application of nickel as an alloying element. The ternary system iron-carbon-nickel has a wide industrial application and forms, further, thefundamental basis of the even greater class of the widely used quarternary steels such as nickel-chromium, nickel-silicon, and nickel-vanadium. As is not uncommon with such cases of virile growth in an industry, the application of the alloy steel in a largely empirical manner has outstripped its scientific development so that a fertile field for metallographic research still remains. In this field, the basic nickel steels require first consideration and are the subject of the present investigation, which is offered as a preliminary to the study of the more complex alloys of industrial importance Of the principal tools of metallography—microscopic examination, determination of mechanical properties, and thermal analysis—the last has developed much more slowly in its application to industrial needs so that the situation often exists that heat treatment operations are based on empirically determined temperatures; that is, temperatures deterrnincd without regard to the actual transformation characteristics of the alloy. This situation is undesirable as there is no uniform standard for comparison of results. It is due, outside the usual difficulties involved in temperature measurements, to the pioneer character of much of the published work; to the lack of definiteness of the Ac, transformation,1 particularly in low-carbon steels; to the failure to define operating conditions completely; and to the paucity of information correlating thermal characteristics with results of heat treatment.

Jan 1, 1922

By Chi-shing Wang

The late Professor P. B. Bucky of Columbia University introduced the principles and techniques of barodynamic experimentation in early 1931 by the application of centrifugal loading to achieve dynamic similitude between models and prototypes of mine structures.1 Later, he and his associates introduced the combined experimental technique of photo- elasticity and the centrifuge to determine the stress distribution in civil engineering structures and mine workings by the use of transparent bakelite models.2,3 The photostress technique, also known as the birefringent-coating method of photoelastic stress analysis, dates back to 1930, when Mesnager published its principles.4 Since then it has been widely applied to experimental stress analyses in many industries. A practical method of observing the dynamic behavior of opaque mine models, which are made of prototype materials, by means of a combination of the centrifugal and the photostress techniques is a new experimental approach under development at the Henry Krumb School of Mines, Columbia University.5 This paper summarizes the development of the barodynamic photostress technique and presents the information obtained from a recent series of experiments in the study of the behavior of rock beams loaded by their own weight. THEORETICAL BACKGROUND Theory of Pure Bending In the general theory of strength of materials, the flexure stress at any point in a beam of any type of cross section which has a longitudinal

Jan 1, 1968

By L. K. Smith, E. M. de Kock, J. van der Walt

A unique and systematic approach for analysing alternative methods of ventilating and cooling large hot mines is presented. The important factors that have a bearing on ventilation and cooling requirements and practices, such as air flow through the mine, geographical distribution of heat loads, micro ventilation considerations etc., are dealt with. Analysis of these leads to the definitive ventilation and cooling strategies, air and water process design, detail specifications and design of associated plant and equipment.

Jan 1, 1982

By W. W. Mullins

The development, by the mechanism of volume diffusion, of a grain boundary groove on an interface separating a solid phase and a saturated fluid phase is calculated under the following assumptions: 1) isotropy of the interfacial free energy 's, 2) applicability of the Gibbs-Thompson formula relating curvature and chemical potential, 3) a nearly planar groove surface. The groove profile is found to have a .fixed shape and linear dimensions that are proportional to (time)1/3. The constant of proportionality is evaluated and involves ?s in such a way that the latter my be evaluated from grooving kinetics. A grain boundary that intersects an interphase interface will tend to produce a groove along the line of intersection (Fig. 1). The ultimate motivation for the formation of the groove is the reduction in interfacial free energ that occurs as the grain boundary contracts. Smith has discussed the way in which the free energy of the interfaces determines their dihedral angles at the groove root and has given a detailed analysis of the effect of the dihedral angles upon the nature the microstructures developed in polyphase alloys. Herring2 has extended the considerations to the case in which the free energy of an interface depends on its orientation and has thus added torque terms to the condition for interface equilibrium. Although the grain boundary and the interphase interface may quickly achieve the proper equilibrium angles where they intersect, as determined by the balance of equivalent tensions and torques,"2 the groove will generally continue to grow (though with decreasing speed). Thermodynamically, this continued growth reflects the fact that the lowest free energy cannot be achieved until the entire grain boundary has been eliminated; mechanistically, the growth occurs in response to inhomogeneities of chemical potential that are caused by the constraint of fixed dihedral angles at the groove root. The latter point is illustrated in Fig. 1, which shows that atoms* near the groove are on the convex side of a cylindrically curved surface and therefore have a higher chemical potential than atoms on the flat interface beyond. Thus atoms tend to leave the curved groove shoulders and force the groove to deepen. When both phases are solid additional chemical potential gradient may arise from whatever strain fields are necessary to insure continuity of material across the interface. In the discussion that follows, this complication due to strain will not occur since we always assume one phase to be a fluid and the other a solid. The transport processes that may operate to permit growth of the groove are surface (interface)* diffusion, volume diffusion in the phase on either side of the interface, and evaporation-condensation when one phase is gaseous. (Also a melting-freezing process is responsible for groove enlargement on a solid-melt interface as discussed in Sec. VI). The theory of grain boundary grooving has been discussed in detail for the processes of surface diffusion and of one type of evaporation-condensation.3'4 The theoretical predictions for the mechanism of surface diffusion have been confirmed in an experimental study of grooving kinetics in copper.5 In this paper, the theory of groove development by volume diffusion will be presented. Volume diffusion can occur either by atomic migration in the solid S or by diffusion of S atoms in the fluid phase, or solvent, adjacent to the groove surface. As discussed in Sec. V, volume diffusion in the solid should be less important than surface diffusion in forming a groove. Apart from verifying this statement then, the main interest of the present analysis centers on diffusion in an external solvent. The solvent may be either a liquid (e.g., water, or-

Jan 1, 1961

By Reginald S. Dean

THE commercial availability of electrolytic manganese has greatly changed the position of manganese as a nonferrous alloying metal. Manganese metal commercially available up to about ten years ago was reduced with either silicon or aluminum and contained substantial amounts of the oxides of these metals and other impurities. Manganese was accordingly not available as an alloy base and its addition to copper-base and nickel-base alloys was generally limited to a manganese content of a few per cent. Several special alloys like manganin contained up to 12 pct of manganese. A method for the production of electrolytic manganese was developed by the Bureau of Mines in 1936 and commercial production was begun in 1938. At the present time (June 1951), production is about 12 tons per day but appears likely to be substantially increased. Electrolytic manganese is deposited from an aqueous electrolyte containing manganese and ammonium sulphates and is marketed as cathode fragments about 1/8 in. thick. The impurities in its composition are as follows: iron, 0.0015 pct; copper, 0.001; arsenic, 0.0005; cobalt, 0.0025; lead, 0.0025; molybdenum, 0.001; sulfide sulfur, 0.017; sulfate sulfur, 0.014; insoluble, 0.002; carbon, 0.002; hydrogen, 0.015. These figures are from Bulletin 463, U. S. Bureau of Mines. From an alloying standpoint, the most important impurity is hydrogen. This can be removed by heating; 95 pct of the hydrogen can be removed in this way without introducing significant amounts of oxygen or nitrogen. Much of the commercial electrolytic manganese used in alloys is dehydrogenited by the producer, since the amount

Jan 1, 1953

The Library of the above-named Societies is open from 9 A.M. to 9 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining-maps and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining-reports, maps privately issued, and similar material, which will be classified; indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will he welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 12, 1913