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By J. Ostachowicz, B. Holynska, M. Lankosz

The paper presents an analyzer and the method for the continuous determination of weight percentage of ore grains with diameter smaller than 75 µm in mineral slurries. The method is based upon the measurement of characteristic x-rays of copper excited by primary radiation of two different energies 16.5 keV and 60 keV from Pu238 and Am241 sources respectively. Additionally the backscattered primary radiation is measured in order to correct the variations of the solids content in the slurry. Since the particle size distribution of slurry can be described by the Rosin-Rammler formula, some calculations have been carried out in order to evaluate the influence of distribution parameters upon the results of the measurements of weight percentage U75 of particles smaller than 75 µm. The influence of solids content and of the copper concentration variation on the results has been also evaluated.1 It resulted from the calculations that the ratio rl/rz, where rl and r2 are the relative intensities of copper characteristic x-rays excited with 16.5 keV and 60 keV photons respectively does not depend on the copper content within the range 1 % to 4% of copper and is slightly dependent on the solids weight fraction and its chemical composition. The change of the dispersion parameter of the Rosin- Rammler distribution from 0.5 to 0.9 results in a change of value of U75 of approximately 3.0%. The results of calculations have been confirmed by the results of laboratory experiments. Therefore, a prototype of industrial analyzer for continuous determination of weight percentage of particles smaller than 75 µm has been designed and made. Its schematic drawing is shown in [Fig. 1]. Slurry is flowing down through steel flow-cell of the length equal to approx. 2 m. In the center, two XRF measuring heads (1) and (2) are located. Each of the heads comprises a rigid waterproof cover (3) with the mylar window (4), in which a proportional counter of resolution 15% for 6.4 keV is mounted with a preamplifier (5). The low- energy isotope source (6) is centrally located above the detector

Jan 1, 1980

By E. M. Norris

In the summer of 1917 it was decided to fireproof the main Tramway hoisting shaft of the Anaconda Copper Mining Co. at Butte, Mont. The shaft has three hoisting compartments and one pump compartment; it is timbered with 12 by 12-in. (30.5 by 30.5-cm.) fir timber, and is 2475 ft. (754 m.) deep. Subsidence and displacement of the surrounding country rock had produced exceedingly heavy ground, and had carried the shaft out of line, in several places, by as much as 2 ft. (0.6 m.) displacement. Constant repairing and realigning of the timbers had been necessary in order to maintain clearance for the cages. The most feasible method of fireproofing, therefore, seemed to be to cover the timbers with a coat of concrete applied with the cement gun. The cement gun, which is operated by compressed air at ordinary mine pressures, feeds a mixture of sand and cement through a hose to a nozzle having a water connection. The mortar in fluid form is thus sprayed upon the prepared surface in thin layers, which can be built up to any desired thickness. The cement gun can be set up at any convenient point; satisfactory results have been obtained with the nozzle a distance of 500 ft. (152 m.) from the gun. The shaft was thoroughly overhauled and the timbers put in the best possible state of repair. Between the 1000 and the 1400 levels, much loose ground lay against the shaft timbers on the north side; this was breast-boarded back and a 30-in. (76-cm.) reinforced-concrete retaining wall was erected, leaving a space of 12 in. (30.5 cm.) outside the shaft timbers to allow for future movements of the ground. For convenience in handling men and materials, it was arranged to concrete the auxiliary hoisting-cage compartment and the pump compartment first, using the cages of the main hoist to serve the cementing crews. The auxiliary cage was then available while the remainder of the shaft was being concreted. A tight partition of 2-in. (5.08-cm.) plank was erected between the auxiliary and the adjoining hoisting compartments, for better protection of men riding on the cages. The application of concrete made this

Jan 1, 1920

By AIME AIME

FOLLOWING careful study of the relations of the Institute to students and the younger members of the profession, the Membership Committee recommended to the Board a change of plans abolishing the Junior Associate class of membership, substituting a -Junior membership and providing for Student Associates. The Board adopted this report at its meeting on Nov. 23, and asked Counsel to draft the necessary amendments to the By-laws, and gave formal notice of intentions to amend as provided in Section I, Article XI1 of the existing By-laws. The By-laws as it is proposed to amend Article I, 11, 111, IV, X, and XI follow. The new plan requires no changes in the other Articles. The matter will come before the Board for vote on Jan. 25.

Jan 1, 1929

By G. G. Luther, C.E. Jackson

The relationship between hardenability and weldability has been mentioned many times. The ease of making a hardness survey has led to its wide use as a criterion of weldability and with a given class or series of steels for which the ductility under weld heat-treatment is known the test is entirely suitable. However, in studying a new steel the hardness survey is of less value, since it is based on the assumption that there is a correlation between hardness and ductility. Several attempts have been made to derive indices for weldabilityl and hardenability from the chemical analysis. In most of these proposals the effects of the different elements were considered to be additive, but recently Grossmann2 proposed a novel method of calculating the hardenability of a steel from its chemical composition. In the method proposed, a steel is considered as having a base hardenability due to its car- bon content and grain size, and this base hardenability is multiplied by a factor for each chemical element present. The final product is the hartlenability. The purpose of the present study is to point out the possible relationship between hardenability and the effect of welding on hardness and ductility for a number of plain carbon and low-alloy steels. The composition of the 25 steels reported in this paper as determined by chemical analysis is given in Table I. To eliminate the effect of variations in finishing temperatures, the 1/2-in. plates were normalized after heating for one hour at 1650°F. in a con-trolled-atmosphere furnace. In making comparative tests, it is essential to hold conditions as Constant as possible; hence full automatic weltling control was used. The electrodes, all supplied by

Jan 1, 1943

By W. F. Boericke

THE character of the Wisconsin orebodies must be clearly understood to appreciate the difficulties encountered in sampling and estimating them. Unlike the western vein deposits, they do not lie between regular walls, but form large, often highly irregular bodies, on a single floor in the so-called Galena limestone. The bottom of the ore is nearly always on the clay bed, a flat generally well-defined clay seam a few inches thick, which marks the junction of the base of the Galena lime and the top of the next formation, the Trenton lime. Above the clay bed, the orebodies make the unique pitch and flat formation described by Chamberlin.1 Theoretically, we should find two pitches, one on either side of the top crevice, diverging as they go down, with the final flats a considerable distance apart on the clay bed. The area between, known locally as core ground, should thus constitute a single defined orebody, with the richer portions near the pitches and the leaner portion in the center of the core. Practically, we find few examples of this perfect orebody. Almost invariably one pitch is better defined than the other, and often the opposite pitch is marked only by a faint line of fracture showing stronger mineralization than the wall rock, or it may be totally lacking. But with an orebody of any size or richness, at least one strong pitch usually tends to follow an east-west trend, or a quartering course. Late mining developments in the rich New Diggings field indicate that these pitches often assume a horseshoe or crescent shape, the richer ore being in the heart of the crescent and the pitches showing less mineralization as they extend outwards. In the northern end of the field, on the contrary, the pitches maintain generally a consistent direction, and have been mined for thousands of feet from the shaft. The length of the orebody may be several thousand feet, the height varying from 10 to 60 ft. and the width from 60 to 250 ft. In fact, on the core side, there is no definite end to the ore. The mineralization simply gets thinner and thinner, and the limit of working depends on the cost sheet and the profit from the recovery.

Jan 2, 1922

By E. Hornbogen, R. C. Glenn

Copper precipitates from a iron as fcc E phase without formation of intermediate compounds. In the first stage of the precipitation, spherical particles with diameters < 100A are formed at a high rate. During the second stage, the particles grow at a rate given by Zener&apos;s equation for growth of a spherical precipitate. In the third stage, growth is slower. Rod-shaped particles form after long aging times at 700°C. Maximum strengthenzng was observed at the beginning of the second step of precipitation. During plastic deformation of the aggregate, particles appear to deform initially by twinning. THE work discussed herein was part of a study of precipitation of substitutional elements from a iron. Copper was chosen as one of these substitutional elements because it has about the same atomic size as a iron, and does not form an intermetallic compound with iron. The data on the iron-copper system then available were summarized by Daniloff1 several years ago. The solubility of copper in a iron has been determined by electrical conductivity measurements,2 lattice parameter measurements,3 and by saturating thin iron foils with copper and determining the copper content.4 The results of the three investigations do not agree very well, but the value of 2.4 wt pct for the maximum solubility at 840°C seems to be the most reliable,4 Fig. 1. An alloy containing 1.23 wt pct Cu was used in our work to assure starting with a completely homogeneous material. On the copper-rich side of the diagram, there is a maximum solubility of about 4 wt pct Fe in copper at 1094°C ( phase). The precipitation of

Jan 1, 1961

By Samuel Wyer

Over 8,000,000 people in the United States depend on natural gas for their cooking, heating and lighting service. This service has been made possible only by the investment of large amounts of capital in transportation lines connecting the gas wells to the various communities, thus combining a hazardous mining operation with a public utility service. The effect that making these lines " common carriers" will have on the present and future service to these 8,000,000 or more people is of far reaching ethical and economic importance, and deserves careful consideration. As an introduction, it must be conceded that: 1. Natural gas, although a mineral and obtained by a mining operation-with more uncontrollable and uncertain features to cope with than exist in the mining of coal or other minerals-when served to the public becomes a public utility service. 2. The governmental power to regulate all public utilities in the interests of the public cannot be successfully disputed. 3. Mere suggestion of inconvenience to the utility is wholly irrelevant, as it cannot be considered or allowed to influence in making a defense against governmental regulation. Unfortunately it is not generally appreciated that: 1. Legislative enactments are not necessarily laws, and cannot abrogate economic laws or alter engineering facts. 2. There is a clear distinction between "common carrier" and "public utility," although the terms are frequently confused. &apos; "A common carrier is one who undertakes for hire to transport persons or goods, or both, from place to place for all persons indifferently, the term implying indifference as to whom shall be served, and an equal readiness to serve all who apply, in the order of their application." On the other hand, property becomes a "public utility" only "when for a particular purpose the public have a right to resort to the premises and make use of them."

Jan 5, 1914

By H. M. Howe

It is a grave objection to the present system (or rather lack of system) of mineralogical nomenclature that, in the very great majority of cases, the name of a mineral gives no hint of its chemical composition, one might almost say no suggestion, however faint, of anything connected with it or characteristic of it, chemical, physical, historical, geographical, geological, or lithological. In becoming acquainted with a mineral, in addition to learning its composition and important characteristics, one must also learn a name wholly unconnected with any of them. It has occurred to me that a system might be devised in which the name of each mineral should express at least an approximation to its ultimate composition. It is far easier to learn the names of most minerals than their compositions. Most of us are familiar with the names and appearance of many minerals, especially among the silicates, of whose compositions we have but a rough notion. It would be the aim of such a system to enable us, in making the one slight effort of learning the name of a mineral, by that same effort and involuntarily to learn its composition, which now requires an additional and a much greater effort. I have worked out a system designed to meet this requirement, and its description occupies the remainder of this article. Doubtless there are many devices on which could be based other systems fulfilling the requirement above set forth better than that about to be described does, and at the same time furnishing names

Jan 1, 1884

By G. G. Luther, C. E. Jackson

The relationship between hardenability and weldability has been mentioned many times. The ease of making a hardness survey has led to its wide use as a criterion of weldability and with a given class or series of steels for which the ductility under weld heat-treatment is known the test is entirely suitable. However, in studying a new steel the hardness survey is of less value, since it is based on the assumption that there is a correlation between hardness and ductility. Several attempts have been made to derive indices for weldabilityl and hardenability from the chemical analysis. In most of these proposals the effects of the different elements were considered to be additive, but recently Grossmann2 proposed a novel method of calculating the hardenability of a steel from its chemical composition. In the method proposed, a steel is considered as having a base hardenability due to its car- bon content and grain size, and this base hardenability is multiplied by a factor for each chemical element present. The final product is the hartlenability. The purpose of the present study is to point out the possible relationship between hardenability and the effect of welding on hardness and ductility for a number of plain carbon and low-alloy steels. The composition of the 25 steels reported in this paper as determined by chemical analysis is given in Table I. To eliminate the effect of variations in finishing temperatures, the 1/2-in. plates were normalized after heating for one hour at 1650°F. in a con-trolled-atmosphere furnace. In making comparative tests, it is essential to hold conditions as Constant as possible; hence full automatic weltling control was used. The electrodes, all supplied by

Jan 1, 1943

By G. B. Pryde, R. M. Magraw

In laying out a new mine, provision should be made for the ultimate recovery of as much coal in any given bed as is consistent with safety and economic mining. Though each mining district, if not each individual mine, has problems that make the adoption of any hard and fast rule impossible, certain basic principles are adapted to practically all conditions. One of the most vital is the provision for barrier pillars of ample dimensions to protect all haulage and permanent airways during the life of the property. Where conditions permit, room or butt entries should be driven on the strike or slightly to the rise, and rooms turned at right angles to these entries. The width of rooms and room pillars is governed by conditions prevailing in the mines under consideration. A safe rule is: In advancing, extract not more than 25 to 35 per cent. of the entire seam; in exceptionally thick seams, considerably less than 25 per cent. should be taken. Rooms usually vary in length from 250 to 350 ft. (76 to 106 m.) with a barrier pillar of not less than 80 ft. between the last crosscut. in rooms and the back entry of the level above. All entries, rooms, and entry-and-room crosscuts should be driven .on sights and room crosscuts should be driven at, right angles to the direction of the rooms. In mines under excessively heavy cover or where roof conditions are bad, rooms should be driven narrow and a barrier pillar left at every fifth to tenth room. This barrier should be of such dimensions that one or more rooms, with pillars of usual dimensions, may be turned through it when the barrier is no longer required. Two of the advantages of such a barrier are the protection of the panel against peaking of roof load during pillar extraction and the easy closing of the entry in case of fire. Where economic conditions permit, it is preferable to follow the retreating panel system of mining. In the case of coal that outcrops, and even in cases where no outcrop is exposed, it is preferable to commence pillar extracting on the high side of the mine. Where the retreating

Jan 1, 1922

By T. C. Atchison, W. I. Duvall, D. E. Fogelson

Dr. Clark has given an excellent resum6 of the recent theoretical re- search work that has been done on the generation and propagation of stress waves in various types of media.1 Unfortunately the dynamic properties of rock do not fit the assumed properties of the idealized media. As a result, none of the theoretical solutions for the generation of stress waves by applied pressures to interior boundaries of the spherical or cylindrical cavity appear to be completely satisfactory to explain experimental data. This fact does not mean that the theoretical work is in error. It simply means that the appropriate dynamic properties of rock have not been taken into account in the present theoretical derivations. Because of the difficulty of theoretically accounting for the crushing and cracking that takes place when explosives are detonated in spherical or cylindrical cavities, it seems advisable that future theoretical studies should attempt to separate the generation of stress waves from the propagation of stress waves. Perhaps if these two problems are separated, we may be able to solve one of them satisfactorily so that theory and experimental data agree. Dr. Clark&apos;s resumé of the research work on scaling and crater formation by point charges is aimed at obtaining a basic understanding of the physical theory of rock breakage, wave generation, and wave propagation. A cursory reading of Dr. Clark&apos;s paper shows that there is very little information summarized that can be used by the practicing engineer in the field of blasting. When problems become too difficult to solve theoretically it is always helpful to take the empirical approach and collect experi-

Jan 1, 1967

By H. J. Wasson, L. W. Mayer

The existing large stocks of raw materials have induced misgivings in the minds of many as to near-view prospects for a return to higher commodity price levels. Until stocks are materially reduced—and this operation will probably extend over a protracted period—a buyers&apos; market will continue. Meanwhile the matter of production cost becomes more and more a factor of consequence to industrial management, finance and the investing public. With many commodities a general level of costs exists with which the public has been made familiar. Certain conditions surround these industries which, at the outset, determine whether there is a basis for sound commercial results. In other words, it can generally be determined in advance whether or not the cost of production is sufficiently below the normal average price to return a reasonable profit over the years. With all domestic agricultural products there are available exhaustive Government studies in the field of production costs. Such figures as the average cost of wheat, cotton, sugar, etc., are reiterated constantly. There are many products of foreign origin such as coffee, rubber, raw silk, etc., the production costs of which are to most of us matters of deep mystery. Forest products also are so diversified that few but specialists know what a thousand feet of lumber really cost at the mill, especially where remotely located. However, with respect to products of mines, production cost information has been widely disseminated. The literature is replete with such data. Here we find that without any special help from outside agencies the industry itself has given publicity to a large variety of cost figures. For example, we know, or know where we can ascertain, the cost of producing a pound of copper from Chile, Arizona or the Lake Superior district. In many cases we can secure from the company reports a vast amount of detail leading up to the cost per ton of ore and the cost per unit of the metal yield. These records are of great assistance to the mining industry as a means of estimating on new exploitations. This industry has been production-cost-minded almost from the beginning.

Jan 1, 1931

By Russell W. Mumford

LITHIA compounds have a place in pharmaceutical and other chemical industries and lithium minerals in glassmaking and ceramics. The metal, although rare, is used to a minor extent in alloys. During the nearly 50 years of production of lithium minerals in the United States, the silicate mineral spodumene has continued as the chief source of raw material for the manufacture of lithium salts. Although twice as much lepidolite, a lithium mica, has been mined, most of it has been used in the making of certain types of glass. Amblygonite has been an additional but minor source of lithium compounds. Triphylite, petalite, and zinnwaldite have also been utilized in the past. All of these commercial lithium minerals contain low percentages of lithium (Table 1). In 1938, a new raw material for manufacture of lithium compounds made its appearance. This product was crude dilithium sodium phosphate (Li2NaPO4), obtained as a by-product of manufacture of potash and soda chemicals from the brine of Searles Lake, California. Searles Lake, which is now dry, lies in the extreme northwest corner of San Bernardino County, California, and consists of a large mass of salts. It was estimated by the United States Geological Survey that the crystal body contained about 25 pct voids, which are filled with a saturated brine. The brine consists mainly of the sulphates, chlorides, carbonates, and borates of sodium and potassium. Several other acid radicals, including phosphates, are present. Lithium is present in the brine in an amount corresponding to 0.01 15 pct Li2O. In the course of evaporation of water from the brine, during the process of manufacture of sodium and potassium chemicals, dilithium sodium phosphate crystallizes out and is recovered by a flotation operation. The lithium concentrate is filtered and dried and is then ready for shipment. It analyzes from 19 to 21 pct Li2O and now constitutes the highest known grade of crude lithium material. It is and will continue to be a major source of lithium for manufacture of lithium products. The variation in lithia content of the commercial minerals as mined is due to replacement of the lithia by soda and potash, to partial alter-

Jan 1, 1949

By AIME AIME

DONALD K. CRAMPTON, present Chairman of the Institute of Metals Division, A.I.M..E., is well known by nonferrous metallurgists in all countries for his research work on the fabrication and properties of copper and its alloys including investigation of season- and stress- corrosion cracking. He is also well known, at least by many metallurgists in the United States for the proficiency with which be carries on his hobbies, in i:lrlditlg photography. gardening, and golf

Jan 1, 1941

By A. E. Bellis

THE CHAIRMAN (ALBERT SAUVEUR, Cambridge, Mass.).-Any information likely to throw light on the constitution and proper treatment of high-speed steel in order to obtain maximum results, should surely he welcomed. All users of high-speed steel, I believe, will agree with the authors that, in order to obtain satisfactory results, it is not sufficient to heat all brands of high-speed steel to one and the same temperature; apparently very slight differences of chemical composition seem to call for marked differences in temperature. I think that all of us agree that a properly treated piece of high-speed steel should have a fine austenitic or polyhedral structure and that an appreciable quantity of free carbide may be present in the case of very high tungsten steels. What we seem to lack is a satisfactory method, quick and reliable, of ascertaining when the proper structure has been obtained. I think Mr. Bellis&apos; paper is a step in the right direction. To the untrained eye, however, it is not an easy matter to select from some of his photomicrographs the one representing the best structure; for instance, in the case of steel A, we wonder why temperatures of 2,250 and 2,300 do not yield the same results, seeing that both structures are apparently alike, and the same might apply to some of the other samples. I have no doubt, however, that the experienced observer is capable of detecting structural differences that are not made plain here and by which he is able to select the proper quenching temperature. COLIN G. FINK, East Orange, N. J.-On page 68 the authors say that the use of a barium chloride bath to eliminate this difficulty has the disadvantage that the surface of the tool becomes decarbonized." I would like to ask whether they actually found that the surface was decarbonized, or whether they base this conclusion on softening alone? A. E. BELLIS, Springfield, Mass.-No, we have never demonstrated that it was a decarbonization, it is just the softening of the steel. The addition of ferrocyanide to the ferrochloride bath has been suggested. I think that is not altogether satisfactory, because the ferrocyanide bath changes composition very rapidly at these high temperatures, and it would be just a question of luck whether or not it had too much or too little ferrocyanide in the bath giving equilibrium with the carbon content.

Jan 4, 1917

INTRODUCTION It has been impossible for the student, the practicing engineer, and the geologist to find all of the essential elements of mineral appraisal and mineral economic analysis in a single text. Indeed, the most recent texts on mine evaluation are over 20 years old. Many of the basic principles of mine sampling and evaluation have not changed over the ensuing years, but with the advent of the digital computer the entire scope of mineral evaluation has been expanded to encompass superior techniques that heretofore were not possible when using manual methods. The old manual methods for ore reserve computations and the techniques for assignment of area of influence to drill-hole samples are now as antiquated as the Model-T Ford. With the computer making possible solutions that had not been practicable in terms of time and effort, it is important for the practicing explorationist and mining engineer to understand many of the new concepts and principles that can be applied with the resolving power of the computer. Many practicing mineral industry professionals have been disappointed by certain computer programs and thus have some reservations about computers being able to solve their very real problems. Often the gap between the practicing engineer and the ivory tower theoretician applying modern computer techniques is too broad to be bridged with scattered, fragmented publications. PURPOSE AND SCOPE OF TEXT It is the intent of this book to update and to unify a great many scattered reference works used in the mineral industry today. The ensuing pages are addressed both to the professional already working in the mineral industry who needs information on computerized methods as well as to the serious student seeking to grasp the fundamentals and modern techniques of mineral appraisal and feasibility. These techniques are based on sound mathematical principles and theory, with the computer as a tool-but a very essential tool-for the solution of the problems involved. The computer can be of value only if it is programmed by those having sufficient expertise to use its inherent problem-solving capability, and the output is interpreted by those who are sufficiently acquainted with its operation to understand the data it produces. In the pages that follow the author intends to outline in considerable detail all the essen-

Jan 1, 1980

Operating Characteristics of Centrifugal Fans and Use of Fan Performance Curve Discussion of paper by. Louis W. HUBER, presented at the New York Meeting, 1926, .and issued, as Pamphlet No. 1542-A, with MINING AND METALLURGY, February, 1926. G. BRIGHT, Pittsburgh, Pa.-Apparently from the pressure curves for a forward-curved-blade fan, in Mr. Huber&apos;s paper, practically all ventilation-might be stopped with increased resistance. In order, to discuss the characteristics of a fan we need, some better way to measure the characteristics of a mine. You all know that. the average anemometer is not very-reliable. Sometimes two anemometers, supposed to be recently calibrated, will differ 50 per cent. Either this or some other committee should standardize measuring methods. The characteristic curves of fans, given by Mr. Huber, would indicate that the forward-curved-blade fan would cause trouble in attempting parallel operation, because two machines will not parallel unless they have dropping pressure characteristics. On the other hand, it is indicated that with the backward-curved blade, they could easily be paralleled. But few mines use more than one fan. Mr. Huber said that if the resistance of the mine was considerably more than contemplated, the quantity of air might be such that the efficiency of the backward-curved fan would be seriously affected, dropping say from 70 to 55 or 50 per cent. In such event, could a difference of speed be selected for the fan that would give the quantity desired at a higher efficiency? L. W. HUBER, Pittsburgh, Pa.-The backward-curved-blade fan responds to change in speed the same as any other fan; if&apos; the speed is doubled, the quantity of air is doubled, the pressure is increased four times and the horsepower eight times. One point not mentioned in the paper is that the backward-curved fan is more efficient than the forward-curved or any other type. If the latter were more efficient, it would pay to install that type and keep the resistance of the mine constant, which is hard to do but it can be done with care. But the total mechanical efficiency of a fan with backward-curved blades is from 10 to 20 per cent. higher.

Jan 1, 1927

J. A. MATHEWS, ? Syracuse, N. Y. (written discussion§).-This paper by Prof. Hoyt, together with the papers by Messrs. Jeffries, Clayton, Rawson, and Moore, submitted at this meeting, constitute a valuable symposium on what might be called the "mechanism of failures." Prof. Hoyt has not emphasized too strongly the importance of the notched-bar test, or the notch as a feature of a structural design. There has been a good deal of misunderstanding in reference to the value of the notched-bar test, and various vibratory tests such as the Wohler, White-Souther, Stanton, and Upton-Lewis have been devised. This form of testing has received more attention abroad than it has here, and has been the subject of a great many very careful investigations. I have heard many expressions of surprise at the apparent lack of agreement between the results of vibratory tests and the results of shock tests. It is not necessary that the values obviously should agree, because obviously different properties are being tested. In reference to the presence of notches or sharp corners in the construe tion of machines or parts, would say that these more frequently lead to fatigue failures than to typical notch-bar failures clue to sudden impact. I have seen a number of airplane crankshafts that had apparently failed due to a keyway that was left with fairly sharp angles at the bottom. The material satisfactorily responded to every test, including the notched-bar test, nevertheless the shafts failed, showing a fatigue break, usually spiral and sometimes making at least one complete turn around the shaft. The lack of concordance between supposedly duplicate notched-bar tests in my experience has been most often due to lack of care in the machining of the test piece itself. Prof. Hoyt draws attention to a report of Charpy in 1909, in which two steels of almost identical physical properties show very different results in the notched-bar test. He states that the microstructure at once showed that one steel was in poorer condition than the other. More recent experience has shown other cases of this kind where not even the microstructure serves to reveal any startling differences in structure.

Jan 4, 1919

By James Terry Duce

The symposium on production for the year 1940 contains few papers on the foreign situation. It is probable that the foreign part of next year&apos;s symposium will be even shorter. This is due to rigid censorship in various countries, as the question of the volume of petroleum supplies has become one of great strategic importance. This is even more true than in the last war, owing to greater mechanization of armies. &apos;It has always been the policy of officers in charge of the symposium to refrain from publishing information that might possibly injure national or private interests. At the close of the war we hope again to publish full and accurate records of production abroad. Excerpts from Circular to Authors In order to facilitate interpretation of the data in this chapter, we print the following excerpts from the Circular to Authors. The field is the unit in this tabulation. In cases of fields extending across State boundaries, such as Rodessa, it is suggested that each State author treat the section of the field in his State as a unit, and by a footnote indicate that the field extends into an adjacent State. Each space in Table I may represent one of four possibilities; either it is not applicable to the particular field, or the proper entry is not determinable, or the proper entry may be determinable but is not determinable from data available to the author, or the proper entry is determinable. When spaces are not applicable, leave blank; in spaces where the proper entries are determinable but not de-terminable frod data available to the author, please inserty; in spaces where the proper entries are determinable by the author, make such entries. y implies a hope that in some future year a definite figure will be available. The entry of a zero is a positive declaration, and an important declaration where it is in order. Inability to determine precisely the correct entry for a particular space should not lead the author to insert merely y. Contributions of great value may be made by the author in many cases where entries are not subject to precise determination. In sucli cases the author should use his good judgment and make the best entry possible under the circumstances. For many spaces the correct entries represent the opinion of the author (for example, "Area Proved&apos;) and in such cases the entry need not be hedged to such extent as when the quantities are definite yet can be ascertained only approximately by the author. In cases under definite headings but where figures are only approximate, the author may use x. It is thought that the nearest whole numbers are sufficiently accurate for our purposes except as to percentage of sulphur in oil. If an author desires to report any other figures to tenths, he may do so. The quantity of gas produced should include, where possible, gas sold or otherwise marketed, and gas blown into the air, burned as flares or otherwise wasted. Segregation of these figures would be interesting if the authors can make such segregation. In any event, the figures should represent as nearly as possible the total quantity of gas removed from the reservoir. Under the columns on "Depth," the average depth to the top of the productive zones and to the bottom of the productive wells, when

Jan 1, 1941

By Henry Schaefer

Solution by electric analogy of performance problems of reservoirs containing oil and gas has heretofore depended upon a process of successive approximations based on material-balance calculations, because of variation in fluid compressibility. By the addition or subtraction of electric condenser capacity, the analogy network can be adjusted automatically for changing compressibility due to evolution of gas in the reservoir. The addition of a condenser is accomplished by an electronic circuit, which is described; subtracting a condenser is done by merely opening the electrical circuit by means of a relay. Introduction V. Paschkis and H. D. Baker1 first developed in this country a method of applying the analogy of flow of electric current in noninductive circuits to solution of heat-flow problems and suggested its application for certain other problems, such as flow of fluids or mass transfer and chemical diffusion. Necessary details for applying the analogy to flow of fluids in porous media were developed by IV. A. Bruce;= he classified3 the types of analysis and predictions that can be made by the analogy in class I, when the reservoir contains oil but no gas for the period under consideration; in Class 2, when both oil and gas exist in the free state in the reservoir sometime during the period under consideration. Duplication of bottom-hole pressure history and predictions for class I reservoirs can be obtained directly by electric analogy. Until now, the solution of problems pertaining to reservoirs in class 2 was obtained by successive approximations along with material-balance calculations. The object of this paper is to present a method for simplifying the application of electric analogy to class 2 reservoirs, resulting in a solution of these problems as direct as is possible for class I reservoirs. This is accomplished by an electronic control circuit, which adjusts the analogy network for changing compressibilities of fluids contained in the reservoirs. Analogy Network In electrical phenomena the analogy to two-dimensional fluid flow in a porous media is that of current flow through an ideal conducting sheet. This sheet, perfectly insulated on both sides, has resistance and capacitance uniformly distributed throughout its area but is of negligible inductance. The need for having the surface boundaries perfectly insulated is that good correspondence may be had with a permeable fluid-conducting stratum bounded above and below by impermeable media. 111 actual application the ideal conducting sheet, which has distributed parameters, is replaced by a network having lumped values of resistance and capacitance—the resistances are series elements and the capacitances are shunt elements. The larger the number of lumped

Jan 1, 1947