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Discussion of the paper of C. W. Goodale and J. H. Klepinger, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 50, August, 1913, pp. 1935 to 2010. PROF. JOSEPH W. RICHARDS, South Bethlehem, Pa.:-Mr. Chairman, I would like to call attention to one valuable feature of the paper which may interest some: I have worked a good deal with the Pitot tube, and have always had difficulty with what is called the static end of that apparatus, so much so that I became almost hopeless of securing good results with it. I find here, however, what is stated to be a perfectly satisfactory static end for the Pitot tube, satis factory under probably all conditions. I congratulate Mr. Klepinger on the design of that tube and the consequent improvement he has made in the technical measurement of the volumes of gases. I would also like to ask if the total volume coming out of the chimney per day could not be computed by chemical analyses of the SO and SO2 in the gases, and calculation on the basis of the known weight of.. sulphur going out in a day; so that the Pitot tube measurements . could be checked by a method independent of measurements in the flues. J. H. KLEPINGER :-I think the volume of gases could be determined in that way. Those of a chemical turn of mind would go. about it so, but I am not enough of a chemist to follow that method, and consequently I always look at the mechanical way to obtain the results.

Jan 11, 1913

By L. F. Reinartz

The furnace in which rimming steel is made has an important bearing on the quality of the steel produced. Furnace.—Particularly in the manufacture of low-carbon rimming steels, it is necessary to have an efficient, easily regulated furnace, because of the relatively high finishing temperature requirements. In recent years, the most important development in design of open-hearth furnaces has been the sealing and insulation of the greater part of the furnace to prevent air infiltration and loss of heat. Efficient, straight-line valves insure proper draft. Combustion controls guarantee correct gas-air ratios. Furnaces of all sizes ranging from 20 to 200 tons have been used successfully in the manufacture of rimming steels. Metal bath is varied from 20 to 40 in. in depth without appreciable variation in quality. Charging.—A normal open-hearth charge consists of pig iron (hot or cold), scrap of miscellaneous nature, and slag-making additions, such as limestone and burnt lime. Because of local conditions, some plants find it necessary to discard the use of pig iron and use some carbonaceolis substances with varying percentages of cast iron to replace the pig iron. It is questionable whether such practice will consistently produce the quality of rimming steel required for auto stampings and other severe drawing requirements. Pig Iron.—An open-hearth furnace under proper control should melt 150 tons of low-carbon rimming steel on about 35 to 38 per cent pig-iron charge basis. In some practices, best results are obtained when the total charge contains from 0.40 to' 0.50 per cent silicon. If reasonably low-

Jan 1, 1935

The Institute conducts jointly with the American Society of Civil Engineers, American Society of Mechanical Engineers and American Institute of Electrical Engineers, certain activities as listed below, and is joint owner with them of certain properties. United Engineering Trustees, Inc. When Mr. Carnegie made his gift which made possible a home for the engineering societies, a separate corporation was organized to act as a holding company and to manage the common property. This was long known as the United Engineering Society, but the name has now been changed to one which more nearly reflects the real function of the corporation. It holds title to . the Engineering Societies Building and to various funds placed in its charge and is managed by a Board of Trustees, of which three are chosen by each of the four societies, American Institute of Mining and Metallurgical Engineers, American Society of Mechanical Engineers, American Institute of Electrical Engineers and American Society of Civil Engineers, which have equal and undivided interests in the property. The land and building cost two million dollars. During the year 1934, the Constitution and Bylaws of The United Engineering Trustees, Inc., were thoroughly revised and a better organization of its functions was affected: The Engineering Foundation and the Engineering Societies Library were made "departments" of the United Engineering Trustees. The Founders Societies share in the property which it holds, and estimated at the present time, as follows: Real estate, $1,987,793; Depreciation and Renewal Fund, $336,992. The U.E.T. has endowment funds-' amounting to $1,107,677. The A.I.M.E. trustees are W. D. B. Motter, Jr., A. L. .Queneau and Albert Roberts.

Jan 1, 1937

By A. M. Talbot

THERE is still considerable controversy as to the exact nature of the mechanism of the age-hardening process, in spite of the many experi-ments already performed. For this reason, a considerable number of typical systems should be examined in detail and their results correlated. Furthermore, the methods of studying the changes that take place during the progress of this phenomenon should be carefully scrutinized and the different methods applied to the same samples, preferably at the same time. The experiments described in this paper are presented to supply information on one age-hardening system and to show how the various methods of investigation compare in their indication of what has hap-pened. In brief, the progress of aging in magnesium alloys containing about 10 per cent by weight of aluminum at different temperatures was followed by measurements of hardness, electrical resistivity, dilation and lattice parameter, and by microscopic observation.

Jan 1, 1936

By Arthur C. Spencer

Having suggested magmatic waters as the probable agents of vein- and ore-deposition in Southeastern Alaska in a paper entitled, The Geology of the Treadwell Ore-Deposits,' it is with particular interest that I note Mr. W. Lindgren's application of the hypothesis of igneous emanations to the gold-quartz veins of Victoria and of California. After describing the similarities of the veins and of the changes in the wall-rock due to the action of vein-waters in the two regions considered by him, Mr. Lindgren formulates the hypothesie that the veins of this type " have been deposited chiefly by ' eruptive after-effects ;' in other words, chiefly by hot ascending waters originally contained in the granitic magma and relased from it by decreasing pressure, due to its irruption into the upper parts of the litho-sphere. It is quite possible that atmospheric waters may have played a certain part by aiding the precipitation and by effecting certain forms of concentration in the deposits." There are many reasons for extending this hypothesis to southeastern Alaska. This region and the Sierra Nevada belt of California are undoubtedly parts of one geologic province, throughout which the main events of geologic time are evidenced by identical or closely similar records in the rocks. Our knowledge of the former region is still fragmentary, to be sure; but the origin-dates of the most prominent features of geology have been located in the time-scale, and found to correspond completely with the red-letter dates in the Californian record. In both there are: (1) intense folding and meta-

Jan 1, 1906

By hydrometamorphism is meant the alteration of rocks, ores and minerals by atmospheric waters. In its broadest sense, it includes the varied processes of weathering, oxidation, hydration, the leaching of rocks and ores, and the solution, migration and enrichment of metals. Rain water, as it strikes the earth, is practically pure water, except for small quantities of dissolved atmospheric gases; upon coming in contact with ore minerals, especially sulphides, however, it is transformed into solutions of great chemical activity, which attack, transform and rearrange the minerals of ore- bodies, and so effect enrichments of the greatest economic importance. Primary deposits so low in grade as to be without commercial value are frequently thus transformed into deposits of commercial importance. It is necessary in the examination of any orebody, therefore, to determine whether the valuable ore is of primary or of secondary origin; if primary, its value may be expected to continue indefinitely in depth to the zone of primary impoverishment; if secondary, the ore deposition is known to be controlled by surface agencies, and the valuable ore may be expected to continue to such depths only as have been reached by surface waters. The decomposition and weathering of rocks, unlike the changes undergone by orebodies, are accomplished by water carrying as dissolved constituents chiefly atmospheric oxygen and carbon dioxide, together with vegetable acids. The chemical changes wrought are principally hydration, oxidation and the formation of carbonates. The tendency is toward the solution of the more easily dissolved minerals, which is attended by the formation and a surface concentration of the more resistant minerals,

Jan 1, 1932

By E. Topuz, G. Faulkner, M. Karmis, C. Haycocks

The Appalachian coal region of Virginia, southern West Virginia and Kentucky and the extreme eastern portion of Tennessee constitutes a unique area of surface coal mining activities. The area contains a number of contiguously placed coal seams, up to a total of fourteen in some places, which vary in thickness from a few centimeters to 2,5 meters. Much of this coal is of high quality, some being the highest grade metallurgical coal found anywhere in the world. The region may be broadly characterized physiologically as a dissected plateau with a relief above the valley floors of up to 500 meters and a dendritic drainage pattern. Up to six seams may outcrop in the hillsides above drainage, many of which have been subjected to contour stripping operations. Prior to the passage of the surface mining reclamation act, little effort was made to reclaim stripped areas. The passage of the strip mining act, including the controversial requirement for returning the land to its approximate original contour, has forced intensive recla¬mation efforts from the mining industry. The wisdom of this original contour requirement has been the subject of considerable debate and litigation, mainly because of its cost, inconvenience, and value of the land after it has been reclaimed. Regardless of whether recla¬mation is carried out, under current practices slope failures do occur. This in effect circumvents the intent of the law and can expose large unvegetated spoil areas, and contribute to hillside erosion and stream silting. Such failures must be eliminated if further costly reclamation efforts are to be avoided.

Jan 1, 1983

By F. Paredes, W. R. Holman, R. W. Crawford

The diffusion coefficient for hydrogen in the ß titanium alloy containing 13 pct V, 11 pct CY, and 3 pct A1 was measured over the temperature range 20° to 500°C. Results fit the expression: D= 1.58 x lgs exp-------==-----) cm2,sec THE diffusion coefficient for hydrogen in the metastable ß-phase titanium alloy containing 13 pct V, 11 pct Cr, and 3 pct A1 was measured as part of an investigation of the effects of hydrogen on the mechanical properties of titanium alloys. Several theories on the mechanisms of hydrogen embrittle-ment include diffusion of hydrogen at ambient temperature as an important step in the embrittling process.'-5 In hydrogen-contaminated a-ß titanium alloys, it has been postulated that the rate-controlling step may be the rate at which hydrogen diffuses from the ß phase to stress- or strain-nucleated brittle hydride platelets at the a-ß interface.' However, embrittlement of the all-ß alloy investigated in this work may proceed by a different mechanism, since this alloy can be embrittled without the formation of detectable hydride platelets.6 Troiano has suggested that in this case the mechanism of delayed failure or embrittlement is similar to that proposed for high-strength steel, i.e., repeated crack initiation caused by a decrease in bonding energy as hydrogen diffuses to points of high tri-axial stress at the root of a notch. In both types of alloy the rate of embrittlement is believed to be controlled by diffusion of hydrogen in the ß phase. Accurate hydrogen-diffusion data in the vicinity of room temperature should therefore be of some assistance in understanding the mechanisms of embrittlement in these two classes of titanium alloys. Diffusion of hydrogen in pure titanium has been studied by Wasilewski and Kehl7 at temperatures above 500°C. Their measurements on diffusion in the ß phase were extended below the ß-a transformation temperature (882°C) to approximately 600°C. This was possible because of the 8 stabilizing effect of hydrogen. No results at lower temperatures have been published and there are no data in the literature on hydrogen diffusion in the ß -phase alloy used in this program. Hydrogen diffusion in metals is generally investigated by measuring the rate of transport of hydrogen past a solid-gas interface, i.e., by absorption, permeation, or degassing-rate measurements. These methods produce accurate diffusion data when bulk diffusion is the rate-determining step in the over-all process. However, at the lower temperatures of interest in hydrogen-embrittlement studies or under conditions where surface films are present, the measured rates may be surface-controlled and the calculated diffusion coefficients will be in error. Surface effects were eliminated in the present work by using a modification of the common welded-couple technique m which two bars with uniform but different compositions are joined before the diffusion anneal." The same type of step change in the initial concentration vs distance curve was produced by electrolytically hydrogenating thin-strip specimens which had been electrically insulated over half of their length. Concentration vs distance curves were determined, after appropriate diffusion-annealing treatments, by vacuum-extraction analyses of transverse samples sheared from the strips. Diffusion coefficients were calculated by the methods of Grube.M This technique was feasible because of the large concentrations of hydrogen which can be charged into p -phase alloys without the formation of hydrides15'16 and because of the extremely low degassing rates observed when hydrogenated titanium alloys are heated in air. EXPERIMENTAL WORK The diffusion couples were cut from a 0.022-in.-thick mi ll-annealed sheet.* Strips 8 in. long by 1/2

Jan 1, 1965

Dr. Wadsworth's discussion of leaching is straightforward and certainly points out some of the critical areas in regards to the fundamental aspects of leaching. I will address myself to the more practical aspects of leaching. As a couple of general comments, very fine particles are often dealt with only when necessary. In many processing applications the sands and slimes are separated with the sand portion being treated by common metallurgical techniques and the slime portion being treated essentially by any technology that will recover some of the values. Ore treatment techniques such as leach/precipitate/float (LPF) have been used in the copper industry to take advantage of leachable copper preferentially reporting to the fine fraction. The second advantage, of course, is the improved metallurgy associated with the treatment of the sand fraction. Cases can be made for sand/slime separations in the aluminum and uranium industry where most of the value reports to the slime fraction and the sand fraction is rejected In the agitated leach systems, fine particles are often the most readily attacked and leached. In dump, vat and in-situ leaching, fine particles cause considerable problems. The fines will tend to restrict the solution flow from portions of the leach feed. This either causes a significantly reduced solution flow or, more probably, the solution will channel, by-passing much of the ore. In either case the result is a decreased metal recovery from ore. The fine particles of principal concern are clays of a flat plate-like shape which can very effectively compact, swell and cause a decreased solution flow. Discrete silica grains or sulfide grains due to their shape, even though they may be very fine, will not cause nearly the problems clays and secondary precipitates can cause.

Jan 1, 1979

By V. Rajaram

The oil shales of the Green River Formation in the United States have been considered as a source of liquid hydrocarbons since 1908, with the first retort constructed in Colorado in 1917. However, it was not until 1944 that the mining characteristics of oil shale were investigated in a systematic manner. During the period 1944 through 1956, the Selective Mine and the Demonstration Mine (also referred to as the Anvil Points Mine) were operated by the U. S. Bureau of Mines (USBM) near Rifle, Colorado. Significant progress was made in developing a room and pillar mining method by which oil shale could be mined safely at a very low cost per ton. Mechanical properties of oil shale were determined, safe room spans and roof support techniques were established, and drilling and blasting methods for oil shale were developed. As a follow-on to this USBM effort, a consortium of six oil companies with Mobil Oil Company as project manager carried out a research program during the period 1964-68 at the Mobil mine, located in the vicinity of the Anvil Points mine. Rock mechanics investigations were conducted as a part of this research program, and consisted of laboratory studies, in-situ stress determinations, and roof and pillar instrumentation. This paper will discuss the findings at the Anvil Points mine and Mobil mine to illustrate the stability considerations in underground oil shale mining.

Jan 1, 1983

By T. T. Read

In discussing the taxation of mining enterprises, it is desirable to place limits of both time and space on the field of discussion. For our present purposes it seems best to limit consideration to taxation of mining enterprises in the United States, and to further limit the subject to taxation under approximately current conditions. Even with such limitations the field is large enough, since in this country we have, in most regions, a number of taxing powers; so that state, county and village tax systems must ordinarily be considered, in addition to our national or federal taxes. Nor is it possible, in discussing United States mineral taxes of today, altogether to pass by similar taxation in earlier periods, or related systems in other countries. It is perhaps hardly necessary to remind you, at the outset, that each age in the history of the world displays its own system of public revenues, and that the taxation systems of today are everywhere different from those of older times. Theories as to taxation have varied according to the economic basis of the society in which they were formulated, and our ideas as to justice in taxation fluctuate with changes in social conditions. The word taxation is used in a fairly definite sense today, but you have only to glance into the history of taxation to find that the paragenesis of ore deposits is a fairly simple subject as compared to the paragenesis of taxation systems.

Jan 1, 1932

By Carl Beal

Introduction. DURING the latter part of 1915 and the first half of 1916, the writer held the position of geologist in connection with the conservation work instituted by the U. S. Bureau of Mines, on oil and gas land belonging to the Indians of the Five Civilized Tribes in Oklahoma. The duty of the geologist was to correlate formations containing oil, gas,-and water, and to determine the relations of these substances in the different formations so that the conservation agents might carry on their work most intelligently. On account of the rapid development of the Cushing field, which lies in the western part of the Creek Nation, much work was clone there by the inspection force. In the course of the geologic studies a large amount of information was collected, which, on analysis, has disclosed some interesting facts worthy of publication. The report, of which the following remarks are an abstract, has been prepared and submitted to the U. S. Geological Survey for publication. This report is now (June, 1917) in the press and will doubtless be issued in a few weeks. Methods Used In addition to the structure maps showing the folding of the Pawhuska limestone, which crops out in several places in the Coshing field, separate structure maps of the three most important productive sands-the Layton (Fig. 2), Wheeler, and Bartlesville-have been prepared. These structure maps, were prepared by obtaining the logs of nearly all the wells

Jan 8, 1917

By F. E. Werner, B. L. Averbach, Morris Cohen

THAT bainite formed near the M, temperature bears a striking r esemblance to martensite tempered at the same temperature has been shown by the electron microscope.' By means of electron diffraction,' it has been established that carbide and cementite are present in bainite formed at 500°F (260°C); these carbides are also found in martensite tempered at 500°F (260°C).' The investigation reported here is concerned with an X-ray study of the matrix phases in lower bainite and tempered martensite. These phases have turned out to be dissimilar in structure; the matrix of bainite is body-centered-cubic while that of tempered martensite is body-centered-tetragonal. A vacuum-melted Fe-C alloy containing 1.43 pct C was studied. Specimens of 16 in. diam were sealed in evacuated silica tubing and austenitized at 2300°F (1260°C) for 24 hr. One specimen was quenched into a salt bath at 410°+7 °F (210°+4°C), held for 16 hr, and cooled to room temperature. The structure consisted of about 90 to 95 pct bainite, the re: mainder being martensite and retained austenite. A second specimen was quenched from the austen-itizing temperature into iced brine and then into liquid nitrogen. It consisted of about 90 pct martensite and 10 pct retained austenite. The latter specimen was tempered for 10 hr at 410°+2°F (210°+1°C). The specimens were then fractured along prior austenite grain boundaries (grain size about 2 mm diam) by light tapping with a hammer. Single aus-tenite grains, mostly transformed, were etched to about 0.5 mm diam and mounted in a Unicam single crystal goniometer, which allowed both rotation and oscillation of the sample. Lattice parameters were measured by the technique of Kurdjumov and Lyssak. This method takes advantage of the fact that martensite and lower bainite are related to austenite by the Kurdjumov-sachs orientation relationships Thus, the (002) and the (200) (020) reflections can be recorded separately, permitting the c and a parameters to be determined without interference from overlapping reflections. According to these findings, the matrix phase in bainite is body-centered-cubic and, within experimental error, has the same lattice parameter as ferrite (2.866A). On the other hand, martensite, tempered as above, retains some tetragonality, with a c/a ratio of 1.005t0.002. Most workers in the past have assumed that bainite is generated from austenite as a supersaturated phase, but the nature of this product has not been established. The question arises as to whether bainite initially has a tetragonal structure and then tempers to cubic, or if it forms directly as a cubic structure. If it forms with a tetragonal lattice, it might well be expected to temper to the cubic phase at about the same rate as tetragonal martensite. The martensitic specimen used here was given approximately the same tempering exposure, 10 hr at 410°F, as suffered by the greater part of the bainite during the isothermal transformation. About 50 pct bainite was formed in 6 hr at 410°F. On tempering at this temperature, martensite reduces its tetragonality within a few minutes to a value corresponding to 0.30 pct C.' Further decomposition proceeds slowly, and after 10 hr the c/a ratio is still appreciable, i.e., 1.005. Thus, even if the bainite were to form as a tetragonal phase with a tetragonality corresponding to only 0.30 pct C, which might be assumed to coexist with e carbide, it would not be expected to become cubic in this time. It seems very likely, therefore, that bainite forms irom austenite as a body-centered-cubic phase and does not pass through a tetragonal transition. The carbon content of the cubic phase has not been determined, but it could easily be as high as 0.1 pct, within the experimental uncertainty of the lattice-parameter measurements. It has been postulated that retained austenite decomposes on tempering into the same product as martensite tempered at the same temperature. There is now considerable doubt on this point. The isothermal transformation product of both primary and retained austenite at the temperature in question here is bainite," and the present findings show that bainite and tempered martensite do not have the same matrix. Acknowledgments The authors would like to acknowledge the financial support of the Instrumentation Laboratory, Massachusetts Institute of Technology, and the United States Air Force.

Jan 1, 1957

By E. J. Roberts

Prior to 1916, thickening was an art, and any accurate decision as to what size of machine to install to handle a given tonnage of a specific ore must have been one of those intuitive conclusions, based on both intimate and extensive acquaintance with thick-ners and ore pulps. Then in 1916 "knowledge of acquaintance," became "knowledge about" with the publication of the Coe and Clevenger paper.' The unit operation of thickening had graduated to the status of an engineering science. The fundamental similitude relationships for the two major phases of the operation were defined so clearly that batch tests on models as small as liter cylinders could serve to specify protypes as large as 325 ft in diameter. It is quite apparent from reading the literature that Coe and Clevenger's contribution is not generally appreciated. In so far as the basic engineering relationships are concerned, the only real advance which has occurred in the 30 odd years which have elapsed since the Coe and Clevenger paper is the recognition of the effect of the rakes on the thickening process. Bull and Darby2 noted this in 1926, and the extensive use of the "gluten type" thickener, in which the effect is magni-fied, bears witness to its importance. Comings3 further verified this effect of the rakes. As a matter of fact, a number of papers show an apparent regression from the Coe paper in that the area determinations are made on the basis of a single test from One concentration of solids. Coe and Clevenger amply demonstrated that this is unsafe, since the controlling zone may be one other than that of the feed dilution. Comings3 neatly demonstrated this without apparently realizing it. Of course there have been significant advances in the application of the operation to industry. Open tray thickeners were introduced to save area; balanced tray thickeners, washing thickeners, and multifeed clarifiers were developed with all of their special hydraulic and mechanical problems. Combinations of all kinds have been introduced, such as combination agitators and thickeners, combination flocculators and clarifiers, combination thickeners and filters. With the establishment of the operation on a firm engineering foundation, installation was facilitated and expansion proceeded. There are still problems, of course, functional as well as mechanical. Sometimes the moisture in the underflow obtained in practice is not as low as is expected on the basis of the test data. Sometimes the underflow is so "thick " that its discharge and subsequent handling requires special attention. Island formation plagues some operators. The use of the thickener as a surge basin and blending tank in the cement industry poses unusual problems. Design of rakes and the drive mechanism must be continually im-proved. Corrosion problems must he overcome. Power requirements for raking the settled solids occasionally is the controlling factor as it was in the case of the all American Canal desilting installation. Other similitude relationships and design problems come into the picture when we enter the field of clarification or nonline settlement. We have an energy dissipation problem in introducing the feed and any models must satisfy the Froude model relationships. Autoflocculation requires detention which involves the same similitude laws that we encounter in the compression zone. Approach to an Exact Science The next step beyond having control of the similitude relationships is to understand the why of these relationships right back up the line to first principles. The ultimate might be that, if given the mineralogical composition of the solids and their size distribution together with an analysis of the suspending liquid, we could calculate the entire thickening behavior of the system. Then we could say we had reduced the operation to an exact science. True it might be more trouble getting this basic analytical data than to make our empirical determinations for area and volume, and we would need an ENIAC to calculate the results, but that does not detract from the desirability of such understanding. Considerable work has been done by the chemical engineers with this end in view. Comings,3 Egolf,4 Work,5 Kam-mermeyer,6 Steinour,7 and others have studied the problem. The writer has no final answer to the thickening story but would like to propose a picture of the mechanics of the two phases of thickening which has been found useful in understanding the subject and which leads to some convenient relationship in treating the compression step and arriving at the compression depth.

Jan 1, 1950

By J. B. Hiskey

The hydrometallurgical application of thiourea in processing precious metal ores and concentrates has reached the development stage. This paper reviews recent technical literature covering the process development of thiourea leaching. In addition, recent fundamental contributions are discussed. Most of the interest in thiourea leaching has involved treating high grade concentrates that have sufficient value to just the use of thiourea as a reagent. An important development in thiourea technology is the addition of SO2 to the leaching solution. This procedure effectively reduces the decomposition of thiourea and eliminates the problems of passive surface layers that limit the leaching efficiency. Results for the thiourea leaching of a bulk sulfide concentrate and a residue from the autoclave leaching of a smelter flue dust are also reported. As determined by a standard bottle roll cyanidation test, the bulk concentrate was extremely resistive to cyanide leaching yielding only 16% gold and 2% silver extraction in 24 hours. Leaching with a relatively concentrated thiourea solution (1MCS (NH2)2) resulted in 83% gold and 75% silver extraction in four hours. With the treated flue dust residue, gold extraction was about 60%. Gold and silver extraction with cyanide was sensitive to both cyanide concentration and oxidizing conditions. Cyanidation resulted in 59% gold extraction and 77% silver extraction in 24 hours.

Jan 1, 1985

The Institute conducts jointly with the American Society of Civil Engineers, American Society of Mechanical Engineers and American Institute of Electrical Engineers, certain activities as listed below, and is joint owner with them of certain properties. United Engineering Trustees, Inc. When Mr. Carnegie made. his gift which made possible a home for the engineering societies, a separate corporation was organized to act as a holding company and to manage the common property. This was long known as the United Engineering Society, but the name has now been changed to one which more nearly reflects the real function of the corporation. It holds title to the Engineering Societies Building and to various funds placed in its charge and is managed by a Board of Trustees, of which three are chosen by each of the four societies, American Institute of Mining and Metallurgical Engineers, American Society of Mechanical Engineers, American Institute of Electrical Engineers and American Society of Civil Engineers, which have equal and undivided interests in the property. The land and building cost two million dollars. During the year 1934, the Constitution and Bylaws of The United Engineering Trustees, Inc., were thoroughly revised and a better organization of its functions was effected: The Engineering Foundation and the Engineering Societies Library were made "departments" of the United Engineering Trustees. The Founders Societies share in the property which it holds, and estimated at the present time, as follows: Real estate,. $1,993,793; Depreciation and Renewal Fund, $401,000. The U.E.T. has endowment funds amounting to $1,086,893. The A.I.M.E. trustees are W. D. B. Matter, Jr., A. L. Queneau and Albert Roberts.

Jan 1, 1939

R. S. Shoemaker: Our first question is, is there a need for a grizzly before a primary crusher? What is its effect on crusher capacity and crusher maintenance? Is it worth the extra capital cost in a crusher installation? Vincent: ASARCO has a grizzly at Mission. Utah Copper uses grizzlies ahead of their gyratories. There is some quite abrasive ore at Mission, an argillite type of rock, which has a work index of 16.5 to 20, which is getting up toward the taconite classification. We get a life of 12- 16 million tons per set of concaves or per mantle with the grizzly ahead of the crusher. At Duval Corp., some 6 miles to the south of Mission, their crusher installation on a good, hard rock does not have a grizzly, and the last information I had is they get a life of about 2 ½ -3 million tons on their mantle and concave. At Silver Bell, our other copper unit in Arizona, they do not have a grizzly ahead of the gyratory and there they get a life of about 5-6 million tons. At Utah Copper, which we all know is a fairly soft ore, relatively speaking, they get a life of 24-27 million tons with grizzlies ahead of the crushers. I think a grizzly has a very definite effect on the life of the mantle and the concaves. As far as a jaw crusher is concerned, I think that usually it is desirable to have a grizzly if it is properly designed, which means it is self- cleaning. Otherwise I would not like to see one in the circuit.

Jan 9, 1967

By Frank Foote, Willard L. Bruner, Eric R. Jette, Y. New york

The alloys of gold and iron were investigated in 1907 by Isaac and Tammann,l who determined the thermal diagram for the entire system by thermal analysis and microscopic examination. They also reviewed the previous literature. Since that time the present authors have been able to find only two additional references. Guertler and Schulze2 examined the electrical resistance of iron alloys containing up to 40 per cent by weight of gold between 0" and 200" C.; the alloys were in the form of wires. The main result of this work was to confirm the solid solubility limit found by Isaac and Tammann; namely, about 20 per cent Au. More recently, Shih3 has examined the magnetic properties of gold alloys containing up to 10 weight per cent iron and particularly the range below 5 per cent. The alloys in the lower range were found to be paramagnetic; the 10 per cent alloy was ferromagnetic. The present investigation was undertaken to determine the solid solubility limits at various temperatures, particularly below the a-y transformation point of iron, since these solubilities are of some importance in connection with the working of the alloys in the manufacture of certain "grey" and "blue" golds. Materials and Methods The gold was obtained from the U. S. Metals Refining Co. and contained 99.99+ per cent Au. The electrolytic iron had been annealed in hydrogen and contained impurities as follows: P, 0.035; Si, 0.001; S, C, Mn, Cu, each 0.01 per cent. Weighed quantities of the two metals were placed in small crucibles lined with pure sintered MgO; a saturated solution of magnesium nitrate

Jan 1, 1934

R. B. BRINSMADE, Puebla, Puebla, Mexico (communication to the Secretary*) :-As I have previously considered the general equations for mine-valuation,1 I will here discuss only that part of Mr. Finlay's paper criticized by E. E. White, along with some of the general principles of mining taxation, under the following six topics: 1. Rate of interest earned by sinking-fund. 2. Rate of interest earned by investment. 3. Place of royalty item in valuation. 4. Place of taxation item in valuation. 5. Calculation of future ore-prices. 6. Valuation of undeveloped mining land. 1. Rate of Interest Earned by Sinking-Fund.-Mr. Denny's quoted opinion of a 3 per cent. rate is evidently based on English conditions before the Boer war. The great destruction of liquid capital by the great wars and catastrophes since 1897, along with the flood of gold and consequent rise in the average index of commodity prices, has undoubtedly increased the rate of interest at least one-half per cent. In the United States sound savings banks now allow 4 per cent. on deposits, while safe bonds are quoted at prices which yield even 5 per cent.. 2. Rate of interest Earned by Investment.-Gold-mines with uncertain and scanty ore reserves, the objects of Mr. Denny's quoted remarks, are quite different from iron,. copper, or coal mines with definite mineral reserves blocked out ahead by drilling or driving. While 10 per cent is often all inadequate yield from gold-mines, the latter class of mines are often, as safe as city real estate and resemble it as an investment in more ways than one.

Jan 10, 1913

By R. Fahn

Bentonites are best suited for the preparation of acid activated clays with efficient adsorption properties. They are weathering products of acid volcanic ashes and natural deposits are spread worldwide. The main constituent of bentonite is aluminum hydrosilicate montmorillonite with a high ability to swell. Physical and Chemical Properties of Montmorillonite The clay mineral montmorillonite is named after its place of discovery, near Montmorillon in southern France. The structure of this clay is shown in [Fig. 1]. The montmorillonite crystal consists of about 15-20 silicate plates. Each silicate plate is composed of three layers. The central one is formed by aluminum or by ferric hydrate octahedrons, the two outer ones consist of silicon dioxide tetrahedrons. In the presence of water, the montmorillonite crystal swells and water molecules become deposited between individual silicate layers. Two types of natural bentonites are known: the Western type, which is a natural sodium bentonite (high swelling grade), and the Southern type, an alkaline earth or calcium bentonite (low swelling grade). Southern bentonites have efficient adsorption properties of their own. They are called natural active earths or fullers earths. Acid Treatment of Bentonite Under the influence of a mineral acid, the exchangeable alkaline earth ions of bentonite are substituted by hydrogen ions. Moreover, depending on the acid concentration, temperature, pressure, and reaction time, a more or less pronounced leaching process takes place. Thereby Al-, Fe-, and Mg-ions are extracted from the octahedron layers. This results in a change in the crystalline structure of montmorillonite and in an increase of its specific surface area and porosity, as shown in [Fig. 2].

Jan 1, 1983