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By F. M. Lewis, J. F. Myers

W. I. Garms-—The authors state that when they added 11 tons of balls to the 45 pct volume ball load, the power needle did not budge. The question arises as to whether any increase in capacity accompanied the 11-ton addition. It is hardly conceivable that all of the balls making up the 11-ton addition were sterile. However, as the work done in the ball mill is not by kilo-watthours per se or balls per se but by kilowatthour-balls, it is possible that the kilowatthourballs in the mill before the 11-ton addition had a different amperage, voltage or robustage than those in the mill after the addition and that the overall outcome was that equal work was done before and after the addition. The authors can keep the efficiency that they got with the 45 pct volume 1-in. ball charge and get additional capacity by putting more kilowatthourballs to work in the form of the addition of 11 tons of 2-in. balls to the present ball charge, and subsequent makeup additions by weight of 20 pct 2-in. balls and 80 pct 1-in. balls. J. F. Myers (authors' reply)-—Mr. Garms points his finger at the 11 tons of "sterile" balls added to the Tri-cone mill. A fact so interesting to us that we felt it should be reported. Clearly, ball slippage at the existing mill speed prevented any further transfer of power from the shell to the ball mass. We agree that the kilowatthourballs would increase, were we charging rough 2-in. balls as suggested by Mr. Garms. The assumption is, of course, that we would get a corresponding increase in work done. Our reported data (CIME meeting, Vancouver, 1946) shows a gain of work accomplished of 7.6 pct as we decreased the ball size from 2 in. to 11/2 in. and a further gain of work accomplished of 2.1 pct when we went from 11/2 in. to 1 in. The small ball results reported by H. R. Banks at Chapman Camp are also very convincing. In the case of 2-in. balls they would take the conventional ball path and start cascading. They would thus destroy the classifying pool over the "foot" of the

Jan 1, 1951

By J. F. Myers, F. M. Lewis

W. I. Garms-—The authors state that when they added 11 tons of balls to the 45 pct volume ball load, the power needle did not budge. The question arises as to whether any increase in capacity accompanied the 11-ton addition. It is hardly conceivable that all of the balls making up the 11-ton addition were sterile. However, as the work done in the ball mill is not by kilo-watthours per se or balls per se but by kilowatthour-balls, it is possible that the kilowatthourballs in the mill before the 11-ton addition had a different amperage, voltage or robustage than those in the mill after the addition and that the overall outcome was that equal work was done before and after the addition. The authors can keep the efficiency that they got with the 45 pct volume 1-in. ball charge and get additional capacity by putting more kilowatthourballs to work in the form of the addition of 11 tons of 2-in. balls to the present ball charge, and subsequent makeup additions by weight of 20 pct 2-in. balls and 80 pct 1-in. balls. J. F. Myers (authors' reply)-—Mr. Garms points his finger at the 11 tons of "sterile" balls added to the Tri-cone mill. A fact so interesting to us that we felt it should be reported. Clearly, ball slippage at the existing mill speed prevented any further transfer of power from the shell to the ball mass. We agree that the kilowatthourballs would increase, were we charging rough 2-in. balls as suggested by Mr. Garms. The assumption is, of course, that we would get a corresponding increase in work done. Our reported data (CIME meeting, Vancouver, 1946) shows a gain of work accomplished of 7.6 pct as we decreased the ball size from 2 in. to 11/2 in. and a further gain of work accomplished of 2.1 pct when we went from 11/2 in. to 1 in. The small ball results reported by H. R. Banks at Chapman Camp are also very convincing. In the case of 2-in. balls they would take the conventional ball path and start cascading. They would thus destroy the classifying pool over the "foot" of the

Jan 1, 1951

By H. H. Rachford, D. W. Peaceman

A system of partial differential equations describing miscible displacement of fluids in porous media is derived The system takes into account the influence of gravity, the spatial distribution of permeability, diffusion, and fluid viscosities and densities. A numerical procedure for approximating solutions to the differential systems has been tested for a horizontal two-dimensional geometry. In end-to-end displacements of oil with less-viscous solvents, the numerical solutions exhibited fingering qualitatively similar to that observed in laboratory models. Small random spatial variations in permeability about the mean value are sufficient to initiate fingering. Quantitative comparisons of computed results with laboratory data show good agreement. INTRODUCTION Miscible flooding of oil by solvent is receiving increasing consideration for field use.1-4 Unfortunately, such floods potentially present severe problems in loss of recovery through the by-passing of oil by expensive solvent. Consequently, their economic evaluation requires sound techniques for predicting recovery. The purposes of this work are to present a finite-difference method for calculating the multidimensional displacement of oil by solvent and to investigate the validity of the method by comparing results of calculations with data from displacements in laboratory models.5 The formulation of the method to simulate the model experiments treats a case of limited scope in the description of solvent flooding in the reservoir. The model experiments were carried out with fluids that were assumed to form an incompressible, ideal, two-component system with constant diffusivity. Establishing the validity of the method even in its present form provides a major step toward the goal of quantitatively evaluating individual solvent flooding projects. First, it demonstrates the fea- sibility of calculating the course of displacements which are dominated by an inherent macroscopic instability, i.e., viscous fingering. In addition, the method provides almost the only practical means of examining the effect of the size and extent of reservoir inhomogeneities on the development and propagation of the fingers, taking into account the important influences of diffusion and gravitational segregation. It might be inferred that such studies cannot yield results of practical value because in displacements dominated by macroscopic instability the pattern of finger development and the resulting performance should depend critically on small variations in the geometric distribution of reservoir inhomogeneities. The present method offers the capability inherent in computational techniques of predicting performance reproducibly with any arbitrary distribution of reservoir properties and, as such, provides a means of evaluating the sensitivity of behavior to uncertainties in reservoir definition and, thus, assessing the reliability of prediction of performance. THE PHYSICAL PROBLEM DATA USED FOR QUANTITATIVE TESTS OF CALCULATIONS In this work, a calculation for treating the miscible-displacement process is tested by comparing calculated results with experimental data. The experiments chosen for comparison have been described in detail,5 and the quantitative features are summarized in a later section. Briefly, oil was flooded by solvent of equal density from a thin rectangular channel in Lucite packed with uniform Ottawa sand. Under these conditions, two-dimensional geometry is considered adequate to represent the process. Inasmuch as the present work is concerned with testing of the method by comparison with specific two-dimensional data, the system of equations presented in the succeeding section will be oriented to defining the physical system specifically. THE DIFFERENTIAL EQUATIONS Suppose x, y to be a Cartesian co-ordinate system and define h(x, y) to be the height of a point above a horizontal reference plane. It will be assumed

By Henry Souther

It is generally admitted that a god, practical and commercial set of specifications for the use of the many purchasers of cast-iron does not exist. A few good sets are in the hands of large buyers, but even these are very different, contradictory, and not intended to cover a wide range of product. Furthermore, most of them have been prepared to cover but one branch of the industry. It is strange that purchasers of cast-iron have not looked into this question long ago and demanded good, uniform cast-irou. Probably cast-iron has been discarded from many uses because of its failure in a few instances, even though the failure was due to ignorance of the quality of the iron, or perhaps to abnormally bad iron. Some foundrymen seem to consider all gray iron from a given foundry as uniform, especially if they know that it has been made from certain well-known brands of pig. It is likely that with standard specifications and the increase of knowledge necessary for their intelligent employ-

Jan 1, 1905

By Richard W. Lodge

Mr. H. R. Batcheller, of the class of 1894, Massachusetts Institute of Technology, while experimenting with chlorine gas on a certain lot of roasted concentrates, met with the following difficulties: 1. A poor extraction of the gold. 2. A very large consumption of chlorine gas. 3. Inability to precipitate all of the gold from the solutioil containing the AuC1,. 4. The bullion obtained was very base. These difficulties were the same whether the chlorine was generated from H2SO47 MnO29 and salt, or whether H2SO, and bleaching powder were used. They may be accounted for partly by the presence of some arsenic left in the roasted ore, and partly by the presence of copper in the solution containing the AuCI3. It was therefore suggested to try the effect of bromine on a similar lot of ore. The use of this element is, of course, nothing new, but in the following experiments it seemed to present many advantages over chlorine. The material worked upon consisted of some concentrates containing 2.31 ounces of gold per ton, and 34.26 per cent. of arsenic, which would correspoild to about 74.4 per cent. Of

Jan 1, 1896

The Institute's stock of Volumes XXXI, LI, and LII has become much reduced by sales: If members have copies of these volumes which they can spare, the price of $3 per volume will be paid for them, if in good condition. If desired, a copy of the Index for Volumes XXXVI to LV will he given for one of these volumes of the Transactions and one dollar additional. For two volumes of the Transactions, a copy of the Index will be sent and the balance will be credited to the payment of clues.

Jan 12, 1918

The Institute's stock of Volumes XXXI, LI, and LII has become much reduced by sales. If members have copies of these volumes which they can spare, the price of $3 per volume will he paid for them, if in good condition. If desired, a copy of the Index for Volumes XXXVI to LV will be given for one of these volumes of the Transactions and one dollar additional. For two volumes of the Transactions, a copy of the Index will he sent and the balance will be credited to the payment of dues.

Jan 1, 1919

By N. V. Peterson, R. S. Mason

The violent explosion of Mount St. Helens in the state of Washington on May 18, 1980 showered volcanic ash over vast areas of the Northwest. It was another eruptive episode in a long history of similar occurrences in the region, which extends from Canada to California and reaches several hundred miles inland from the Pacific Ocean. Pumice, pumicite, and cinders are products of explosive volcanic eruptions. Pumice and pumicite are produced by the violent expansion of dissolved gases in a viscous silicic lava such as rhyolite or dacite. Scoria is the mafic counterpart of pumice. Pumice is a light-colored, cellular, almost frothy rock made up of glass-walled bubble casts. It may occur as coherent, massive blocks composed of highly vesicular glassy lava in either a flow or vent filling, or it may be more or less fragmented by violent eruption. Pumicite, the diminutive of pumice, has the same origin, chemical composition, and glassy structure, differing only in particle size. Particles less than 0.16 in. in diam are designated pumicite. Pumice usually is found relatively close to the vent from which it was expelled, while pumicite may be carried by winds for great distances before settling as an accumulation of fine-grained ash or tuffaceous sediment. Mount St. Helens lofted an estimated 5 billion cu yd of ash and pumicite. The volcano, unlike most of the High Cascade peaks, is composed largely of dacitic material with only minor amounts of andesite and basalt. Volcanic cinders are the reddish to black vesicular fragments which pile up during explosive eruptions of volcanoes of basaltic composition. Most cinder deposits occur as cones or mounds of stratified fragments ranging from a fraction of an inch to several inches in diameter. Individual cones or mounds may be several hundred feet in diameter and up to 500 ft high. Properties and Uses Low bulk density, good heat and sound insulating properties, and excellent abrasive capabilities make pumice and pumicite useful in industrial applications. Cinders, though less cellular and somewhat heavier, also have a variety of industrial uses. The main use of pumice and cinders continues to be in the construction industry as road-surfacing material, railroad ballast, and building block aggregate. Pumicite is used in sizable quantities as a pozzolanic additive to monolithic concrete where it increases workability, strength, and durability of the concrete and reduces the heat of hydration. Volcanic cinders generally are denser and more coarsely cellular than most pumice. Markets for cinders include aggregate for road construction and surfacing and use in lightweight concretes, particularly blocks. Some producers having access to both pumice and cinders offer a variety of blends of the two materials to block manufacturers. Table I lists the principal applications of industrial pumice. Tables 2 and 3 show US sales and uses of volcanic products. Most pumice deposits are unconsolidated and usually have a minimum of overburden. Mining is by open pit and can be easily carried out with conventional loading equipment. Sometimes air drying precedes hauling to a crushing and screening plant which yields the size product desired. Multiple bins at railroad hauling facilities permit blending if desired. Pumice for abrasive use may require more sophisticated processing by fine grinding and air classification before being bagged for market.

Jan 1, 1983

By W. K. Godfrey

The highest compressive strength cement has the highest bond strength in tests in which the cement is subjected to a confining pressure. After perforating, the bond strength is reduced to nearly zero when the pipe is supported by weak cement. Perforating does not affect the bond strength, however, when the pipe is supported by strong cement. Pipe supported by weak cement is damaged by perforating with expendable capsule jets, but is not damaged by perforating with the hollow carrier gun. High strength cements are recommended for oil wells that are to be perforated. Introduction The purpose of this work is to determine the effect of jet perforating on the bonding strength of oilwell cement at simulated down-hole conditions. Bond strength is a good criterion for determining the effectiveness of cement in performing its main function, i.e., that of isolating zones. According to the literature on the subject, the optimum cement strength for perforating is low and should not exceed 2,000 psi compressive strength. This conclusion was based on the appearance of bullet and jet perforations in neat and gel cements largely done in the absence of a confining pressure more than 15 years ago. Discussion Literature A relatively weak cement has been recommended in the literature as having optimum properties for perforating. In 1947, Oliphant and Farris tested bullet perforating of neat cements at various curing times.' Some of the tests were made at down-hole conditions. They reported that the optimum cement strength for perforating was about 2,000 psi compressive strength. Enlarged holes occurred when strength was too low, and the cement shattered and cracked when the strength was too high. In 1951, Morgan and Dumbauld tested bullet and jet perforating of neat and gel cements at surface conditions.' They reported that optimum cement has a compressive strength less than 2,000 psi. In their tests at atmospheric pressure, high strength cement shattered and cracked when perforated. Thus, the optimum cement strength was based on the appearance of neat and gel cement after perforating. In 1953, Clark showed a relation between cement strength and fluid shutoff.' He concluded that a 500 psi compressive strength is required for good fluid shutoff and that maximum bonding ability is developed at approximately 1,000 psi compressive strength. In 1964, Bell and Shore invalidated most of the conclu sions by the previous authors when they demonstrated that atmospheric pressure tests cannot be used to determine casing deformation and damage that will result from perforating under down-hole conditions.' They showed that the higher the hydrostatic pressure, the more restricted will be the expansion of gases generated by the charge. Less casing deformation and damage occurs under down-hole conditions than at atmospheric pressure. In recent work, Bearden et al. reported that jet perforating at surface pressure with the hollow carrier gun caused the cement sheath to shatter and crack.' The perforating, however, did not seriously affect the pressure required to leak past the casing cement bond. Only three cementing mixtures were tested, and presumably they had strengths in excess of 2.000 psi. Bearden et al. also reported that the hydraulic bonding strength increased as the compressive strength increased. Their hydraulic test showed that approximately 1,000 psi pressure is sufficient to break the casing cement bond for a well aged neat Portland cement sheath. Unfortunately, the tests were not run with a confining pressure, so Bearden et al. were merely measuring the strength of their outer 8%-in. casing. In our investigation, we measured the hydraulic bond strength of cement to pipe under a confining pressure and found that the bond strength was not limited to 1,000 psi. Cement Bond The bond strength is a good criterion for measuring the effectiveness of cement in performing its main function, that of preventing interzonal communication of fluids behind the casing. Measuring bond strength after perforating should be a good quantitative method of determining optimum cement properties, and should be a better method than that used by previous investigators,11 ' who simply observed the appearance of the cement after perforating.

Jan 1, 1969

By G. Derge, W. Peifer, J. H. Richards

INTRODUCTION A WIDE variety of metallurgical defects in steel have commonly been attributed to the presence of excessive amounts of hydrogen. These defects include flakes in rails and forgings, cracks in welds, and blisters in enameled ware. They have been related to hydrogen largely by circumstantial evidence because the proper sampling and analysis of steel for hydrogen has been known to be difficult and because no general agreement has existed with regard to the relative suitability and accuracy of available methods. The need for a direct approach to these problems has been widely recognized. This general situation has been well described in the publications of the British Committee on the Heterogeneity of Steel Ingots,1 and current approaches to the problem were reviewed in a recent symposium of the AIME.12 The plans described by the present authors at that meeting have now matured satisfactorily and will form the basis of this paper. The principle object of this paper will be to describe the methods of sampling and analysis which have been developed and to illustrate the usefulness and limitations of these methods by citing their application to a specific problem. The first problem selected for investigation was the behavior of hydrogen in rail steel. This was chosen because the occurrence of shatter cracks in rails has received a great deal of study over a long period of time. The defect can be controlled by the expensive procedure of slow cooling. However, it may be hoped that a better understanding of the factors influencing the hydrogen content of rails will lead to a more efficient control of this problem. Rails provide a good starting point for a more general study of hydrogen in steel because they provide a cross section large enough to develop cracks, yet small enough for convenient handling and sampling. Rails were also selected because they are made from plain carbon steel and it was felt that the initial work should not be complicated by the effects introduced by alloying elements. The considerations which determined the original planning of this study should be reviewed. The inherently complex nature of most hydrogen problems requires that a large amount of data must be collected for any particular case. This in turn means that any analytical procedure should be as rapid and simple as possible. The same objective of speed is indicated by the fact that it may finally become desirable to use hydrogen analysis in process control. It is also known that hydrogen is highly fugitive and that any procedure which facilitates early analysis of the sample without prolonged or irregular storage has distinct advantages. The most important previously reported methods of analysis may be classified into three general groups: (I) Vacuum fusion. (2) Vacuum extraction (without melting). (3) Total combustion.

Jan 1, 1948

By C Gunther

In the examination of an undeveloped prospect a decision must be arrived at from an inspection of the outcrops and the exposures in a few shallow pits. Prospects that are offered for sale rarely expose any important quantity of good ore, work having usually been stopped when the immediate exploration no longer yielded favorable results. It should be borne in mind, furthermore, that a great majority of prospects have been examined many times, and if of conspicuous promise, would have been acquired for development. In most cases the problem for the engineer, therefore, is to discover the traces of a valuable mineralization that has disappeared through solution, or the conditions that indicate the possibility, or probability, of underlying secondary enrichments. The available data being meager, every feature should be the subject of careful study-the condition of the outcrop, the structural relationships, the associations of minerals, the alterations of wall rocks, the chances for underlying enrichments, and so forth, as well as the actual assay value of the material exposed. It is frequently advisable to spend the time and money necessary to have trenches dug at various significant points along a promising outcrop; such exposures, even if the depth attained is slight, often disclose conditions that are not apparent at the actual surface, as for example, the existence of soft minerals and the distribution of the various minerals through the mass of the deposit. Trenches also permit samples to be taken from points that were not accessible during former examinations. Strong, persistent outcrops of uniform width may be taken to indicate the probable size and character of the underlying vein,

Jan 1, 1932

By G. F. Sager, B. J. Nelson

Magnesium alloy forgings offer higher and more uniform mechanical properties than heat treated magnesium alloy castings and are used principally for light weight parts that may be stressed in fatigue or subject to impact loads, or where space limitations do not permit the use of the necessarily bulkier magnesium alloy castings. Compositions and Properties of Magnesium Forging Alloys The nominal compositions and properties of the principal commercial magnesium forging alloys are given in Table 1. The two that are most commonly used are AMC58S and AM65S. The former has the highest strength and is, therefore, employed for heavy duty applications. However, the forging of this alloy and of AMC57S ordinarily requires the use of slow speed hydraulic presses. The forging alloy AM65S combines good, although somewhat lower, mechanical properties with excellent forging characteristics. This alloy can be forged on hammers, upsetters, rolls, and mechanical presses, as well as on hydraulic presses. These characteristics make it particularly useful for many applications. Manganese Segregation in AM65S The alloy AM65S contains 5 pct tin, 3 1/2 pct aluminum, and a small amount of manganese, the manganese being added to insure satisfactory resistance to corrosion. Some manganese segregation was occasionally encountered in this alloy. In many applications, such segregation is of no particular consequence, but when forgings are acid dipped prior to the application of various chemical coatings, the segregated particles of manganese constituent may stand in relief. The resultant surface roughening may impair appearance and is undesirable in forgings employed in the textile industry, where very smooth surfaces are essential to avoid the catching and breaking of fine threads. An effort was therefore made to determine the cause of manganese segregation in this alloy and find a method for its elimination. Radiographic examination of a series of cast ingot sections and extruded samples of the AM65S type having manganese contents ranging from zero to about 0.7 pct revealed no appreciable manganese segregation when the manganese was less than about 0.4 pct. A small amount was observed with a manganese content of 0.46 pct and considerable with manganese contents of 0.6 pct or higher. Attempts to eliminate the manganese segregation by variations in the melting and casting conditions were unsuccessful and it soon became apparent that the trouble was attributable to the fact that the manganese contents that caused segregation were in excess of the amounts that would remain in solution at temperatures encountered in the melting and/or casting operations prior to the complete solidification of the ingots. A knowledge of the amounts of manganese that would be soluble in molten alloys of the AM65S type at various temperatures was obviously desirable. The liquid solubilities of manganese in binary Mg-Mn alloys and in Mg-Al-Mn and Mg-Zn-Mn alloys have been determined by Tiner and others,* but no data on the solubility of manganese in molten magnesium alloys containing tin and aluminum are given in the literature. For this reason, an investigation to determine the solubility of manganese in a magnesium alloy containing 5 pct tin and 3.5 pct aluminum (AM65S type) was undertaken.

Jan 1, 1950

By Robert W. Hunt

When I had the honor of presenting to the Institute at the Buffalo meeting in October, 1888 (Trans., xvii., 226), my paper on " Steel Rails and Specifications for their Manufacture," I expressed my hesitancy in submitting my ideal rail-sections. Since then, continued residence in Chicago, perhaps, or greater intercourse with railroad officials, has either given me more courage or has taught me that so little is really known on the subject that one is safe in expressing one's views, let them be ever so erroneous. As a further personal excuse, I may remind you that " fools rush in," etc. At all events, I would now call attention to certain rail-sections which I believe to be good. I do not say they are the best, but I feel sure they have more merit than the majority of the adopted heavier-sectioned rails. In determining the proper form for a rail, the subject should be considered from two points; first, and most important, the duty required ; second, and of almost equal importance, the influence of existing details of manufacture upon the character of the finished product. It is perfectly proper that all the strains to which the rail will be subjected should be considered and calculated. But its ability to resist them will depend quite as much upon the character of the metal as upon the form of its section. That which would be the realization of the ideal with good steel would be disappointment with poorer metal. Therefore, the railroad engineer should always have in mind and pay due respect to what the metal worker may give him—the may being the factór of danger to be covered by his factor of safety, and possessing greater importance than any formula laid down by never so eminent authorities. It is well-known how positive is my conviction that high heat during manufacture and good rails cannot go together; hence, if we insist upon the avoidance of this evil by rail-makers, we must give them sections which can be made at low temperatures with commercial as well as technical success. The market-price for rails controls the practice of makers, and,

Jan 1, 1889

By Hans Lundberg

In order to comprehend the help and information that may be expected from electrical prospecting, it is necessary to have at least a general knowledge of the methods and principles involved in preparing and interpreting results obtained in the field. Electrical prospecting is rather complicated, both in theory and practice, and in order to make a brief description clear to the practical mining man it has been necessary to idealize and generalize the problems, at the risk of having such simplification criticized by the theoretical man. This simplification must not be misinterpreted as showing a lack of theoretical knowledge. For its operation, electrical prospecting mainly depends on the fact that most metallic ores conduct an electric current much more readily than barren rocks. If an electric current flows through a block of ground within which a body of chalcopyrite is enclosed in country rock of schist, the current will find less resistance to its passage through the chalcopyrite than through the schist, even though the passage through the latter be much shorter. This is because the longer path through the chalcopyrite offers less resistance, owing to the superior electrical conductivity of the chalcopyrite (Fig. 1). The good conductor, chalcopyrite, in the poor conductor, schist, thus attracts the current and deflects the normal flow far outside the conduct-

Jan 1, 1929

COUNCIL OF EDUCATION OF AIME (Formerly Mineral Industry Education Division) Established as a Division January 15, 1932 Established as a Council February 26, 1957 John C Calhoun, Jr, Chairman 0 Cutler Shepard, Vice-Chairman Thomas A Read, Secretary-Treasurer Dept of Mining & Metallurgical Engrg University of Illinois Urbana, Illinois COUNCIL OF ECONOMICS OF AIME (Formerly Mineral Economics Division) Established as a Division December 15, 1948 Established as a Council February 26, 1957 Louis C Raymond, Chairman Lorin A Cranson, Vice-Chairman Henry T Mudd, Vice-Chairman Adam K Stricker, Jr, Vice-Chairman Paul F Yopes, Secretary-Treasurer U S Bureau of Mines Albany, Oregon

Jan 1, 1957

By E. O. Jones, E. Whitehead

During the heating of cold-worked nickel silver, the tendcncy of the material to crack is well known. The present research deals with this question, and may conveniently be divided into the following sections: Changes in these alloys during heating and cooling, determination of the temperature at which cracking occurs, effect of grain size, quenching cracks, methods of overcoming annealing cracking. The work is far from complete, in particular the influence of impurities on this tendency has not been investigated, but the results so far obtained lead to certain definite conclusions, which are of theoretical and practical importance. Changes in Alloys During Heating and Cooling During the annealing of many metals at a temperature just below that at which recrystallization sets in, there is evidence of some change, the effect of which is to harden and embrittle the material. This effect has been most clearly demonstrated in the cases of aluminum, copper, brass, and nickel silver, and appears to be a common property of cold-worked metals and alloys, or, at any rate, the non-ferrous ones. The effect would obviously offer an explanation for certain types of annealing cracking, but the trouble is so much more common in the nickel silvers than in the other alloys that some special cause should be looked for. There is, however, fairly good reason for believing that similar cracking may occur in some of the brasses; D. Bunting1 suggests that the a brasses toward the saturation limit are subject to a transformation closely allied in nature to that known to occur in the nickel silvers at around 320" C. Although the existence of this critical temperature range was known, it did not necessarily follow that this transformation was responsible for the trouble under investigation, so the first portion of this paper deals with the attempts made to determine whether other critical changes might not occur in these alloys. There were already reasons for the belief that such would prove to be the case, as the mechanical properties of the nickel

Jan 1, 1926

Discussion of the paper Of JAMES JOHNSTON, presented at the New York meeting, February, 1914, and printed in Bulletin No. 85, January, 1914, pp. 107 to 133. CHAIRMAN E. GIBBON SPILSBURY.-I would like to call attention to the fact shown in this paper that less than five years or perhaps seven years ago nobody had thought it possible to cyanide with success silver ores. The cyaniding of silver and gold ores was first of all started in Mexico, and gradually extended to this country in the case of the silver ores alone. The average extraction, I think, for the metals in Mexico, in the case of the silver ore, is less than 85 per cent., whereas here, in the case of a very complex ore, carrying a high percentage of sulphur and arsenic, and other objectionable elements, the ore has been treated so as to extract an average of 95 per cent. of the silver contents of the ore. It is really a phenomenal revolution in the metallurgy of silver ores which has been demonstrated and worked out at the Nipissing mines. GEORGE A. PACKARD, Boston, Mass.-I would like to suggest a slight modification, perhaps, of the statement which is made that no one considered cyaniding of silver ores up to five, or perhaps seven years ago, because in 1897, when I was at Mercur, Utah, one mill near there was operating on silver ores. It did not operate very successfully from a commercial standpoint, because they did not have a great deal of ore, but the extraction, I was told, was very satisfactory, and I am quite confident that it was, because, as suggested by the name, Chloride Point, the ores were silver chloride ores, and of course very easily soluble. Some years before that, in 1892, I made some tests myself. I spent three months making tests on more or less complex silver sulphide ores at Virginia City, Mont., and while our tests on the plain sulphide ores, finely ground, were quite successful, on account of the presence of a small amount of copper we did not work out a satisfactory solution of the problem at that time; although since then a cyanide plant has been erected and for at least eight years these ores have been treated by cyaniding at Virginia City, and the mill is still in operation. The period of five to seven years should, therefore, be modified considerably, in justice to the pioneers in the cyanide processes. REGINALD E. HORE, Toronto, Ont., Canada.-I hoped that there would be metallurgists from Cobalt here to present and discuss Mr. Johnston's paper. In their absence a few remarks from me may help to make clearer to you what they have accomplished.

Jan 6, 1914

By N. V. Peterson, R. S. Mason

Pumice, pumicite, and cinders are all products of explosive volcanic eruptions. Pumice and pumicite are produced by the violent expansion of dissolved gases in a viscous silicic lava such as rhyolite or dacite. Pumice is a light-colored, cellular, almost frothy rock made up of glass-walled bubble casts. It may occur as coherent, massive blocks composed of highly vesicular glassy lava in either a flow or vent filling, or it may be more or less fragmented by violent eruption. Pumicite has the same origin, chemical composition, and glassy structure as pumice differing only in particle size. Particles less than 4 mm in diam are designated pumicite. Pumice is usually found relatively close to the vent from which it was erupted while pumicite may be carried by winds for great distances before settling as an accumulation of fine-grained ash or tuffaceous sediment. Volcanic cinders are the reddish to black vesicular fragments that pile up during explosive eruptions of volcanoes of basaltic composition. Most deposits of cinders occur as cones or mounds of stratified fragments that range in size from a fraction of an inch to several inches in diameter. Individual cones or mounds of cinders may be several hundreds of feet in diameter and as much as 500 ft high. Properties The properties that make pumice and pumicite useful in industrial applications include: low-bulk density, good heat and sound insulating properties, and excellent abrasive capability. Cinders, even though less cellular and somewhat heavier, also have a variety of industrial uses. Uses The main use of pumice and cinders continues to be in the construction industry as road-surfacing material, railroad ballast, building block aggregate, in lightweight structural concrete, and as plaster aggregate. Both pumice and pumicite continue to be used as abrasives for polishing glass, metal, leather, stone, and wood. Some scouring powders and soaps also contain pumicite. Minor uses include fillers, absorbents, carriers for insecticides, catalyst carriers, filters, and soil conditioners. Pumicite is also used in sizable quantities as a pozzolanic additive in monolithic concrete where it increases the workability, strength, and durability of the concrete and reduces the heat of hydration. Volcanic cinders are generally denser and more coarsely cellular than most pumice. Markets for cinders include aggregate for road construction and surfacing and in lightweight concretes, particularly blocks. Some producers having access to both pumice and cinders offer a variety of blends of the two materials to block manufacturers. Most pumice deposits are unconsolidated and usually have a minimum of overburden. Mining is by open pit and can be easily carried out with conventional loading equipment. Sometimes air-drying precedes hauling to a crushing and screening plant which yields the size product desired. Multiple bins at railroad hauling facilities permit blending if desired. Pumice for abrasive use may require more sophisticated processing by fine grinding and air classification before being bagged for market. Block pumice in economic quantity and quality is limited to a few geologically young

Jan 1, 1975

GENTLEMEN : Herewith are submitted reports for the calendar year 1933 of your Treasurer and the Chairmen of the following standing committees: Finance, Admissions, Membership, Papers and Publications, Library, and MINING AND METALLURGY. TO these reports you are referred for additional details of the year's activity. Finances.-Income for 1933 from all sources totaled $121,690 com- pared with $138,331 in 1932. Incidentally, this exceeded the income as estimated in the budget by $7,190; the largest item being a "surplus" of $3,316 over the budget expectancy as to member dues. As compared with 1932 the most important items of shrinkage in income were $9,000 from dues and initiation fees; $5,500 from the magazine, MINING AND METALLURGY; and $2,500 from sales of publications other than the magazine.

Jan 1, 1934

By T. F. Witherbee

Discussion of Mr. Baker's paper, read at the Lake Superior Meeting, September, 1904. MR. T. F. WITHERBEE, Durango, Mexico (communication to the Secretary*) : Mr. Baker's paper is very instructive in that it shows how furnace-derangements sometimes originate from apparently slight causes. In 1896 a similar burning through of the lining occurred at the Mayville furnace of the Northwestern Iron Co., Mayville, Wis., in exactly 38 days from the time the furnace was blown in. At that time I attributed it to the fact that the bell was carried several inches to the front side of the furnace, the length of the versed side of the arc described by the lever, thus dumping a little more of the charge on the back side, which made the front side of the furnace-charge more open and consequently increased the circulation of the furnace gases through it. After reading Mr. Baker's description, I believe that possibly a little more ore was charged on the back side of the hopper, due to the fact that it was nearest to the elevator. This unequal charging, however, was unconsciously done, as the fillers were both honest and faithful. The illustration of the burned lining of Furnace No. 1, given in Fig. - of Mr. Baker's paper answers very well for the Mayville furnace. It shows that in both cases the destruction of the lining was largely due to faulty construction, in that there were no cooling-plates in the angle of the bosh and in one or two courses of brick above it, where I believe they are-more in demand than anywhere else in the furnace. The presence of these cooling-plates at the angle of the bosh would have obliged the current of the hot gases to turn the corner and would have prevented them from following the angle of the bosh com¬pletely through the lining and shell.

Mar 1, 1905