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By Paul M. Tyler

Fully a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite12 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines. It is largely a matter of markets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal," mining engineers may go too far; on the other hand, they should not let

Jan 1, 1942

By Paul M. Tyler

Fully a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite12 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines. It is largely a matter of markets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal," mining engineers may go too far; on the other hand, they should not let

Jan 1, 1942

By L. D. Frink

Those actively interested in mining are fully aware of the ever-increasing difficulty of making conditions such that efficient work can be done in underground openings, especially as higher rock temperatures are encountered in depth. This is also true where an effort is being made to cut down the burden of overhead expense by working headings 24 hr. in a day if blasting is done as often as is possible in that time. That the conditions resulting from both these causes have driven the native-born Americans from the mines and that their places have been taken by less efficient foreigners is a fact that we must all admit. The great war now being fought in Europe and the educational qualification clause written into our immigration law by the last Congress will probably limit very materially the supply of labor, such as we are now using in our mines, and will force upon mine operators the necessity of making this work appeal again to Americans. Metal tubing, with blower or exhaust fans, has long been used in supplying air to dead ends where natural ventilation is impossible, or in driving the smoke from such places, or in doing both, as the need might be. Here in Butte we have now come to use canvas tubing very extensively and find that it has many advantages not possessed by the metal. The use of flexible tubing is not new, but it has not been generally used in mining operations. Recent improvements, however, in the canvas itself and in the jointing of sections and manner of suspension have so increased its usefulness that it promises to add much to the efficiency of mining. There is now on the market a product that is impervious to air, is fireproof, and has a system of jointing which permits it to be put up or taken down in a few seconds. In this article an effort will be made to explain the manner in which canvas tubing is being used in the North Butte company's operations at Butte, Mont. The accompanying photographs will, I hope, help make clear what may be done with this material.

Jan 1, 1918

By A. L. Labbe

IT Is well known that the Cottrell process is more easily applied to certain kinds of smoke than to others. The successful Cottrell installations are those treating smokes that carry dust of a mechanical nature; also smoke carrying fume dust that contains an excess of sulfuric acid over that required to combine with the oxides in the dust. But up to the present time the process has not reached a satisfactory economical basis of operation, in the treatment of smoke' containing basic dust. It is not impossible to make a smoke containing basic dust suitable for the process by. humidifying or acidifying. A number of Cottrell plants use these two methods of conditioning smoke previous to Cottrell treatment, which are quite successful, but the use of either results in expensive operation and a substantial loss in metals.. For these reasons, I would say that the baghouse process has not been replaced by the Cottrell process in the treatment of smelter basic smoke. Basic smoke must be given a. preliminary conditioning treatment because the dust is not a conductor of electricity; the water or acid treatment imparts some conductivity to the dust.. The rate at which dust is recovered depends on the proportional amount of power transmitted to the, treater and on the rate at which the smoke passes through; therefore to maintain a maximum constant amount of power across the electrodes of the treater, the same degree of conductivity should prevail, at all times between the surface of the electrodes. For all practical purposes, in the application of this process to lead and copper-smelter smoke, we can consider that the conductivity of the gases is a .constant. The variations in temperature of the smoke have a much greater effect on the solids than on the gases; the only instance where the temperature of the gases plays an important part in the process is at plants using humidifying: The temperature does not affect the conductivity of mechanical dust because such dust has natural conductive properties. However, in the case of smoke carrying acid-fume dust, where the conductivity is imparted to the dust particles by coming into contact with the acid fumes, the temperature is of importance.

Jan 8, 1925

By PROCEEDINGS OF MEETINGS

THE opening session of the Institute was held at Hazle Hall, Tuesday evening, October 27th, with a large attendance of members. President Raymond called the Institute to order, and after a few introductory remarks, introduced Mr. I. Lowthian Bell, President of the Iron and Steel Institute of Great Britain, and Honorary Member of the American Institute of Mining Engineers. Mr. Bell was received with great applause, and made his acknowledgments in a brief speech, of which the following is the substance: He desired to thank the Institute personally for the honor conferred upon him in his election to membership, and also for the invitation extended last year to the body of which he was President. The difficulty felt by many members of the Iron and Steel Institute, of leaving for a long journey the works of which they had charge, aggravated by special industrial troubles at the time of the invitation, had obliged them to conclude that it could not then be accepted in a fitting manner. The iron manufacture of this country is a subject of great interest to Englishmen, who look with pride upon the achievements on this side the water of the descendants of a common ancestry. His own reception in this country had far surpassed in cordiality even the well-grounded anticipations he had formed from the assurances of the President and other friends. Notwithstanding the flattering manner in which his friend, in introducing him to the Institute, had spoken of his contributions to the science of iron metallurgy, he could not take to himself alone the significance of this welcome. He knew it was a recognition of the services rendered by the body which he had the honor to represent; and he was glad to see present a member of that body, Mr. Thomas Whitwell, who had fortunately been able to make the journey at this time, and whom he had had the pleasure of meeting on the shores of Lake Champlain. He had been requested to say something of his impressions of the American iron industry. It was not easy to digest so soon the vast

Jan 1, 1875

By T. D. Yensen

It is safe to say that of all the different materials that go to make up electrical machinery, iron is the most important. Upon its magnetic and electrical quality depends not only the efficiency of the machine but, to a very large extent, the cost. Aside from the mechanical strength, there are three characteristics of iron that are of importance in this connection, viz., magnetic hysteresis, electrical resistance, and magnetic permeability. In the homopolar machine, where the magnetic flux is unidirectional, permeability is the only important factor, but in all other machines the flux is reversed in one or more parts and causes losses due to hysteresis and eddy currents. The eddy-current loss depends largely upon the electrical resistance of the iron; the higher the resistance the lower the loss, under otherwise identical conditions. These hysteresis and eddy-current losses cause heating of the machine, and as they depend upon the magnetic density in the iron, this density must be regulated so that the heating shall not be excessive. If the hysteresis and eddy-current losses and the permeability of the magnetic circuit will permit an increase in the magnetic density, or, in other words, a decrease in the amount of iron, this in turn will mean a decrease in the amount of copper needed, with a consequent decrease in the copper loss. It is thus seen that, indirectly as well as directly, the above characteristics have an important bearing on both the efficiency and the cost of electrical machinery. In general, it may be said that iron for electrical machinery should have the following characteristics: (1) low hysteresis loss, (2) high electrical resistance, and (3) high permeability. These are the characteristics that investigators have been striving to attain since electrical machinery first came into use. Until the beginning of the present century, Swedish charcoal iron was regarded as the best grade of iron for magnetic purposes, and even now it ranks high among the various grades used. About that time Sir Robert Hadfield1 produced a number of iron alloys that revolution-

Jan 1, 1916

By John Hays Hammond

The following notes are descriptive of a country as yet in its infancy as regards the advancement made in mining operations. Its inaccessibility and other militating circumstances have retarded progress in that direction. With the completion of the railroad, now under construction, having the city of Cali as its objective point, with the concomitant civilizing and developing consequences, it is certain that the slopes of the Cordilleras will prove to be a South American Eldorado. Deposits of coal, copper, and minerals other than those of the precious metals are known to exist in quantities which, under more favorable conditions of accessibility, etc., could be profitably mined. The Government of the United States of Colombia, I think, is disposed to encourage and foster mining enterprises. Articles designed for mining are admitted free of duty; the permanency of the government is, at least, as well assured as that of Mexico (which is not noted for its immutability), and a more sincerely friendly sentitment towards Americans prevails in the United States of Colombia than in Mexico. This paper is confined to a description of the property of the Cauca company's mines, and is intended rather as a preliminary notice than as an exhaustive report. The Cauca mining district is reached by the following route: New York to Aspinwall; to Panama; to Buenaventura, a port on the west coast of the United States of Colombia, distant thirty-six hours from Panama by steamer; to Cali in the State of Cauca. The State of Cauca is bounded on the north by the Atlantic Ocean, on the northwest by the State of Panama, on the northeast by the States of Bolivar and Antioquia, on the east by Brazil and Venzuela, on the south by the Republic of Ecuador, and on the west by the Pacific. Ocean. It has a territory of 41,443 square miles, which is about one-tenth of the entire territory of the United States of Colombia. Its population, including the 50,000 savage Indians of the Caqueta (some of whom are cannibals), is nearly 450,000 souls, or about one-sixth of the population of the Colombian republic. Of these, one-fifth are whites (Spanish' South Amer-

Jan 1, 1885

By R. D. Pehlke, J. V. Gluck

A study was made of' the effects of up to five additional solutes on the thermodynamic activity of zinc in dilute solution with molten bismuth in the range 450" to 650°C. The experimental measurements were made in a multielectrode galvanic cell apparatus employing fused LiCl-KCl as the electrolyte. The solute additions included indium, lead, tin, cadmium, copper, silver, antimony, or gold. A range of positice and negative interactiotls with zinc was covered. The experinzer~tal observations were cowlpared with the activity coefficients calculated usitlg either Wagner's first-order Taylor series rnodel or a proposed second-order solution itrteraction model. hi general, the truncated first-order Taylor series proposed by Wagner gaue good results for "dilute" solutions (XBi > 0.90) contaitzing up to six solutes. The second-order model, which includes a second-order cross-interaction term, produced a slight improvement in predictions for solutions with XZn = 0.015 and a significant improvement for solutions with XZn = 0.050 hear the limit of Henry's law region). Seveval of the quaternary solutions studied contained a total solute content of 0.215 mole fraction, and fairly good success was achieved in predicting the activity coefficient 01- zinc. ThE study of thermodynamic interactions between dilute solutes in liquid metallic solutions has occasioned much recent interest. It is useful to recall in this respect that Wagner's well-known expression for the activity coefficient' is a practical application of the problem of representing a given function, i .e., In ?, by means of a sequence of polynomials. No specific physical model of a solution is involved in its use. As suggested by Wagner, a Taylor Series is used to expand In ? about a point of infinite dilution with respect to all solutes. The partial differential coefficients of the series have been termed "interaction parameters". Various authors'-6 have proposed formalisms for parameters, the definitions being designed to meet some specific experimental or physical condition. A usual assumption is that terms above first-order in the Taylor Series may be neglected. In that case, the logarithm of the activity coefficient is expressed as a linear function of solute concentrations. The resulting expression is presumed valid for any number of additional solutes as long as the solution can be regarded as "dilute". This assumption can be termed "the hypothesis of additivity". However, experimental tests of that hypothesis for quaternary or higher-order solutions have been extremely limited. Primarily such tests have been confined to studies of effects of added metallic elements on either the activity of carbon or the solubility of gases in liquid iron.7-13 The only known previous study of an all-metal system is the limited work of Okajima and pehlke14 on the effects of multiple solute additions on the activity of cadmium in liquid lead. The present investigation is a portion of the work to determine the effects of various solute additions on the activity of zinc in dilute solution with molten bismuth in the range 450" to 650C It was shown for such ternary solutions that second-order Taylor Series terms could be evaluated at the same time as first-order terms, with no additional experimentation required. A second-order solution model was described which, under certain conditions, is a rigorous representation of solute activity in a ternary solution. (In the sense employed in this paper, the term "model", as distinguished from "equation", is taken to mean an empirical correlation or formalism, but not a hypothetical physical system per se.) Presumably such a model could be extended to produce a better representation of In ? in solutions of even higher order. The feasibility of a generalized Taylor Series approach to solution interactions and inclusion of second-order terms also has been discussed recently by Lupis and Elliott in independent work concurrent with the present investigation. In addition, they discussed empirical means of estimating certain second -order coefficients.17 The utility of such solution models rests on the ability of a truncated series to represent adequately the experimental facts in multicomponent solutions. Questions that arise include: Do the second-order terms really make a significant contribution? How far away from "dilute" solution may such models be applied? Are the types and varieties of the additional solutes important? among others. In order to provide some answers to these questions, an experimental study was made of the effects of two or more additional solutes on the activity of zinc in dilute solution with molten bismuth. Comparisons were then made with calculated activity coefficients obtained using the previously determined ternary interaction parameters. INTERACTION MODELS As an example of the approach to defining activities in multicomponent solutions, consider the Taylor Series expansion for a quaternary system, i.e., three dilute solutes. Writing terms through second order, the result is:''

Jan 1, 1968

By Clarence A. Seyler

The object of all classification is to group together things which are alike, and separate those which are unlike. This object is essentially a practical one, enabling us to apply past experience to new conditions. Many costly large-scale experiments lose half their importance for want of proper description of the coal used, and the consequent impossibility of predicting that other coals will behave in the same way. I do not, therefore, make a fundamental distinction between "scientific'' and "use" classifications, except in so far as use depends on conditions, such as size or impurities which are not related to the nature of the coal substance itself. The characters chosen to define the classes of coal must be such as are accompanied by as many other properties as possible. It is not to be expected that any system of classification will enable us to predict every property of coal, since all specimens have an individuality of their own. But specimens can be grouped by a number of resemblances into species. Further, species which resemble each other can be grouped into genera. Elementary Composition as a Basis of Classification There can be little doubt that the ultimate or elementary composition of "pure coal" is the best basis of classification. It was soon after the perfection of the method of elementary analysis of organic substances by Liebig that Regnault, the distinguished chemist and physicist, laid down the principle that coals of the same kind vary only between narrow limits of elementary composition. This is still the widest generalization that can be made about coal. Upon it the metallurgist Gruner based his classification. In some quarters the value of the ultimate composition was denied, Stein going so far as to say that it teaches us nothing of importance about coal. One still hears statements that it is like crushing a work of art in a mortar and analyzing the powder, or like counting the number of times a given letter occurs in a sentence. Such comparisons are misleading, and the criticism might be applied to organic chemistry as a whole. Nor is the existence of isomerism, or of entirely different substances which

Jan 1, 1928

By Y. C. Liu, R. H. Richman

Deformation and recrystallization textures of the a solid solutions of Cu-P, Cu-As, and Cu-Sb alloys are examined as a function of composition. It is found that the deformation texture of copper is unckanged up to a composition of 0.43, 0.41, and 0.24 at. pct of phosphorus, arsenic, and antimony, respectzvely, and then the transition to the 70 : 30 brass type of deformation texture proceeds linearly as the logarithm of the solute content. Recrystallization textures consist of strong, new components that do not all bear the usual<111> rotational relation to the deformation components. The dependence of the deformation texture transitions and the recrystallization orientations upon composition and solute-element type is discussed. A systematic evolution of individual recrystallization components in the annealing texture of copper was portrayed as a function of germanium or tin content in a previous study.&apos; Similar patterns of tex-tural change have been observed with copper-zinc alloys,2 and in less detailed studies of other systems.3,4 In fact, most of the literature dealing with preferred orientations in copper alloys indicates that the influence of solute elements upon textures in copper is of one general type. As the alloy content of copper is increased, the deformation texture changes from the copper type to the 70:30 brass type, and the annealing texture undergoes a comparable change from the (001) [ loo] orientation of unalloyed copper to the {113} <211> type of 70:30 brass, with the notable exception of copper alloyed with Periodic Subgroup V-B elements.4-8 In almost every case it is possible to describe the reorientations after annealing as 30 to 40 deg rotations about <1ll> poles of the deformation components. Since there is apparently not much difference in the final textures of the copper binary systems already investigated, only a limited variety of preferred orientations has served as the basis for current theories of the origin of annealing textures. In order to test the validity of the proposed theories, and the possibility that the <111> rotations are not unique, it would be most desirable to study the reorientation relationships of additional, and heretofore unanalyzed, recrystallization components if such components exist. Examination of the literature reveals a good deal of uncertainty concerning preferred orientations in copper alloyed with elements in Subgroup V-B of the Periodic Table. Phosphorus is known to inhibit the cube texture in copper when present in amounts as low as 0.01 wt pct,8 but the recrystallized matrix that occurs instead of the cube orientation was reported as either random or weakly textured, with orientations not observed in Cu-Zn, Cu-Ge, or Cu-Sn alloys.4-9 A Cu-0.75 at. pct As alloy apparently contained, along with the (001)[100] and (113) <211> type of recrystallization components, {110} <112> and (110) <001> components, whereas an almost random distribution of orientations was found in alloys of higher arsenic content.4 A {110} <001> component also appeared in rolledand annealed Cu-Sb alloys, but otherwise the recrystallization textures of Cu-Sb alloys seem to con-

Jan 1, 1962

By Ward W. Minkler

Since 1978, the titanium metals industry, throughout the non-socialist world, has experienced a period of growth and prosperity unparalleled since the late 1950s. Sponge producers, melters and mill product manufacturers have operated at capacity, record shipments have been attained, new producers have entered the industry and established producers have implemented expansion plans. However, there is now mounting evidence that the underlying elements which generated this vigorous surge have abated, at least temporarily. It now appears that in 1982, the industry will encounter overcapacity, excessive inventory accumulations and the probability of declining prices. Therefore, it does seem appropriate that we now take inventory of the present and future markets for titanium with the hope we can identify both near term opportunities as well as challenges the industry now faces. If we view the development of titanium markets as a function of time, they fit rather neatly into three sectors.

Jan 1, 1982

By Robert Leach

THIS paper gives a brief summary of the process of manufacture of sterling silver, and some of its more important physical properties, as observed in commercial production of rolled sheet and wire. Although papers have been published by Turner and Smith,1 Rose,2 Sperry3 and Jordan,4 there are few technical data available, and unfortunately the time allowed for the preparation of this paper has not been sufficient to make it as comprehensive as the title might indicate. ANALYSIS OF STERLING SILVER Fine or pure silver is too soft for coinage and the manufacture of articles in which strength and resistance to wear are desired. From the earliest times of which we have record, copper has been the metal generally used to harden silver. Analyses of coins and silver articles from ancient tombs show varying amounts of copper, and old Roman silver objects in the British Museum have approximately the same analysis as our sterling. The first authentic record of the establishment of a standard alloy is during the reign of Henry II in England. During the twelfth and thirteenth centuries, the people in the Eastern Provinces of Germany had a reputation for the standard and purity of their silver coinage, and it is said that Henry II employed some of these Easterlings, as they were called, to improve and standardize the English coinage, which had become debased. The peculiar standard adopted is probably accounted for by the system of weights used. A troy pound contains

Jan 1, 1928

By D. Roberts

SUMMARY In order to accommodate a new plant in a limestone quarry in the Mendip Hills, it became necessary to excavate a potentially unstable disused face of the quarry. A simple two-dimensional graphical method was used to analyse a failure, which occurred during a period of exceptionally heavy rain in 1968, and the results of this analysis were used in estimating the stability of the proposed excavation. The presence of water in vertical fissures and tension cracks was found to be a dominant factor in determining the stability of these faces. The results of this approximate analysis were used as a guide in deciding upon the final slope design and the purpose of presenting this example is to illustrate how the various factors involved in arriving at this design were weighed to arrive at a compromise between theoretical recommendations and practical considerations. INTRODUCTION The successful outcome of a geological and geochemical survey to prove adequate re- serves of high quality limestone, suitable for producing burnt lime, led to planning for the installation of the necessary plant at Amalgamated Roadstone Corporation&apos;s Batts Combe Quarry at Cheddar in Somerset. Topographic and property boundary limits added to restrictions which were likely to be imposed by any forthcoming planning consents and restricted the choice of plant location to one site. The particular site is, in fact, the main floor area of the original quarry which, like many hillside quarries, had been worked with just one face. Before a benching scheme had been introduced on higher ground, the original face had attained a height of 230 ft. and sloped at angles of 58º to 64º. Fig. I shows the present configuration of the disused quarry face and the present working area above. The floor area below the disused face accommodates the existing crushing, conveying, and screening plant. The new facilities for lime burning are to be in addition to the existing main line business of producing roadstone and concrete aggregates and, although a new aggregate production plant would be included in the new installation, no disturbance of current production was to be contemplated.

Jan 1, 1972

By J. C. Bayles

THE most unsatisfactory occurrences in the experience of a manufacturer are those from which he suffers damage and learns nothing useful. That there are such incidents, and that they occur with annoying frequency, is unfortunately true. An accident which can be understood and explained always carries some consolation with it. However bad the copnsequencee, one finds comfort in reflecting that they might have been worse, and that the knowledge of how to avert a more disastrous calamity from the same cause is worth what it cost. But when an accident occurs, which remains unexplained after anxious days of investigation and sleepless nights of reflection, and which is as liable to occur twice or twenty times, as once, very little satisfaction of any kind can be extracted from it by the most philosophical victim. Three such incidents have come under my notice in one establishment. Fortunately none of them were attended with very serious consequences, as no one was hurt, and the damage to property was slight; but in each instance, loss of life and great destruction were escaped by so narrow a margin as to make them extremely disquieting. I have recorded them in the hope, that from the experience of others maybe gained what my own careful investigations have failed to reach-—satisfactory explanations. The first of these curious occurrences was the bunting of a 16-inch pipe carrying air under a compression of about 1 pound. The pipe was made of light galvanized iron with soldered seams. Into it a rotary fan-blower delivered air, and from it smaller pipes were carried to the furnaces. The blower was run continuously. Neither the main pipe nor its branches had any connection with the gas conduits. Both air- and gas-pipes delivered into the furnaces; but although the gas was under much higher compression than the air, there appeared to be no good reason why, having free escape in case of leakage, it should ever make its way back into the air-pipe. One warm afternoon in June the main air-pipe exploded with great vio-

Jan 1, 1891

By M. Gensamer

IT has been suggested by a number of people that it would be worth while for some one to attempt to summarize or condense the proceedings of this symposium. This task has fallen to me as organizer and co-chairman. Its difficulty will be appreciated by anyone who attempts to read the whole proceedings. It is therefore with trepidation that I offer the following digest. In recent years there has been a renewal of interest in America on this subject of the cohesive strength of materials, and a growing appreciation of the need for a better theory of cohesion failure. The theories of elastic action and plastic action are well developed, particularly the former. The theory of plastic action is still in the course of development, but it is well along. Plastic action is terminated by cohesion failure and what is needed is a theory that will tell us when to expect the cohesion failure. In the past it has generally been assumed that cohesion failure will occur when a critical value of the maximum tensile stress has been reached. Many experiments have shown that this is not strictly true, and this symposium concerns itself with the failures of this simple hypothesis, and with the efforts that have been made to devise a more satisfactory theory. The most active contributor in recent years to knowledge in this field is Dr. McAdam, and he was asked to open the symposium with a summary or condensation of his papers and views. Undoubtedly it is presumptuous to attempt a still greater condensation, but perhaps it will be useful, because even his contribution to this symposium contains no summary, no concise statement of just what his contribution has bees. Dr. McAdam makes two main points. The first is that the cohesive strength is not a single valued quantity, but that it is a function of all three principal stresses and hence must be represented diagrammatically by a surface in a three-dimensional figure. Dr. McAdam has attempted so to delineate the cohesion limit, basing his

Jan 1, 1944

By A. A. Blow

The productive area of the Leadville mining district immediately adjoining the city of Leadville, which, by its wonderful richness, has attracted the attention of the mining world for the past twelve years, may, with a few exceptions, he considered as divided into seven local mining centers, separated one from another by the topographical features of the country, and designated by common consent as Fryer Hill, Yankee Hill, Breece Hill, Rock Mill, Printer-Boy Hill, Iron Hill, and Carbonate Hill. Of these seven distinot mining localities, or groups of mines, the central one, Iron Hill, is the one of greatest importance and interest. It was the scene of the earliest discovery of carbonates, as far back as 1875, and since that time has always maintained its position

Jan 1, 1890

By V.F. Marsters

Seepages of oil in Ecuador have been known for many years. The locality first to receive attention, and still worked in a modest way, lies on the north shore of the Santa Elena peninsula, between La Puntilla and Salinas. Operations mere first conducted largely by local cdpital. Later, foreign companies acquired large blocks of land, where they have done considerable drilling. For details concerning present drilling activities in Ecuador, we are indebted to Leon Price, an Ame~ican resident engineer of Ecuador. The information solicited came to the author through the office of the American Consulatell with permission to use it. The coastal plain bordering the Province of Tumbes, Peru, continues to the northeast, but narrow on passing the Zarumilla River. From this point northward it widens toward Santa Rosa. In fact, the pampas, as shown on the official Wolf map, correspond fairly well to the areal extent of tbe coastal plain as far as Guayaquil. This is shown in a general way on the accompanying map. The author understands that the Guayaquil enlbayment is bordered on all sides by the coastal plain, as recognized at Tumbes and farther southwest, and that it can be followed without a break as far north as Palmar. This view is supported by the mapped area regarded by Mr. Price as favorable or possible oil territory. Moreover the islands in the Gulf of Guayaquil are the same geologically as the coastal edge, being composed of Tertiary sediments. The author understands also that Tertiary formations occur north of Palmar. According to a report by Mr. Cardon, of Guayaquil, Tertiary sediments are exposed in the region of San Francisco and extend to and beyond Pta. Calera. There is also reason to believe that at least the lower part of the valley of the Santiago River is occupied by Tertiary sediments, ~~hich probably border the const line and extend into the River Mini l)nsin, and into Colombia. On the south coast there are many seepages, most of them near the inner edge of the coastal plain, between Zarumilla and Santa Rosa and also between Santa Rosa and Machala. I11 the latter region are

Jan 1, 1923

By V. F. Marsters

Seepages of oil in Ecuador have been known for many years. The locality first to receive attention, and still worked in a modest way, lies on the north shore of the Santa Elena peninsula, between La Puntilla and Salinas. Operations mere first conducted largely by local cdpital. Later, foreign companies acquired large blocks of land, where they have done considerable drilling. For details concerning present drilling activities in Ecuador, we are indebted to Leon Price, an Ame~ican resident engineer of Ecuador. The information solicited came to the author through the office of the American Consulatell with permission to use it. The coastal plain bordering the Province of Tumbes, Peru, continues to the northeast, but narrow on passing the Zarumilla River. From this point northward it widens toward Santa Rosa. In fact, the pampas, as shown on the official Wolf map, correspond fairly well to the areal extent of tbe coastal plain as far as Guayaquil. This is shown in a general way on the accompanying map. The author understands that the Guayaquil enlbayment is bordered on all sides by the coastal plain, as recognized at Tumbes and farther southwest, and that it can be followed without a break as far north as Palmar. This view is supported by the mapped area regarded by Mr. Price as favorable or possible oil territory. Moreover the islands in the Gulf of Guayaquil are the same geologically as the coastal edge, being composed of Tertiary sediments. The author understands also that Tertiary formations occur north of Palmar. According to a report by Mr. Cardon, of Guayaquil, Tertiary sediments are exposed in the region of San Francisco and extend to and beyond Pta. Calera. There is also reason to believe that at least the lower part of the valley of the Santiago River is occupied by Tertiary sediments, ~~hich probably border the const line and extend into the River Mini l)nsin, and into Colombia. On the south coast there are many seepages, most of them near the inner edge of the coastal plain, between Zarumilla and Santa Rosa and also between Santa Rosa and Machala. I11 the latter region are

Jan 1, 1923

Jan 1, 1902

By T. G. Fulmor, William Wraith

What impelled The Anaconda Company to dismantle and move a concentrator 25 miles that was already operating at a rate of 35,000 ton per day? The answer to that question takes in almost exactly 49 years and perhaps 10 complete cycles of the metallurgical wheel in the Anaconda, Mont., mill. One could say with truth that the move is a logical next-step in the development of metallurgy in The Anaconda Co. In the old concentrator at Anaconda, the background story is unfolded: - Gravity separation by jigs, later supplemented with gravity tables, 1905. - Separate sand and slime froth flotation, 1915. - Acid bulk froth flotation, 1917. - Bulk alkaline flotation, 1926. - Alkaline flotation of total ore without sand- slime separation due to change in ore type. 1939.

Jan 5, 1964