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Jan 1, 1948

By S. G. Lasky

EVENTS during and since the war indicate that the nations of the world are trying to initiate an era of international co-operation. Definitions and objectives include social, economic, and human considerations no less than political considerations. The mineral resources of the world and the absolute and relative position of each nation enter into this situation. The possible use of armed might, the application of sanctions, the international flow of commerce, the ways in which this flow may encourage or hamper international well-being, and the influence of international and domestic well-being upon one another are all matters that must take mineral resources into account. If the United States is to act wisely and forthrightly in such matters we must be thoroughly informed as to our position with respect to mineral resources. What is the mineral position of the United States? A variety of widely conflicting opinions are held in authoritative and intelligent quarters: (1) For practical purposes our mineral resources are already exhausted.

Jan 1, 1946

Jan 1, 1955

Discussion of the paper of Robert H. Richards, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 81, September, 1913, pp. 2299 to 2303. C. D. DEMOND, Anaconda, Mont. (communication to the Secretary*) :-Any one who has observed the increased efficiency of the Wilfley tables in a mill when fed from a reasonably good hydraulic classifier, as compared with tables fed from a spitzkasten., which is a very poor classifier, will agree to the advantage of ? better classification." It must be gratifying to Dr. Richards to know that, directly or indirectly, maim mill men are responding to his persistent advocacy of correct principles of ore dressing and are accepting the results of his investigations. As he says, these principles mean much for both the conservation of resources and the profit of operators. When Dr. Richards gives us accurate figures as to the maximum size of free mineral grains in the tailings of the Wilfley table and of the vanner, they will be of a good deal of practical value in delimiting the proper fields for the Wilfley, the vanner, and the round table. He has coined the terms ? free settling" and "hindered settling."' The series may be completed by adding "crowded settling," the main principle of action on both the vanner and the Wilfley table, which is the principle of separation in a mass of grains crowded as closely together as they can be and yet continue free to move between one another; and the occurrence of larger mineral particles in the Wilfley tailing than in that from the vanner is apparently caused by the more violent agitation, due chiefly to the purposely sudden reversal of the stroke. It seems likely that the agitation caused by the wash water dropping directly upon the concentrate on the vanner is more harmful than that due to the shake. For the very finest material that can be concentrated by usual methods, the round table is superior to the vanner because it does not, have even, the gentle agitation of the latter. The action on round tables is, not crowded settling," but "film sizing," 2 but agitation is harmful in the latter action. George Gates proved this harm 20 years ago : in slaking the first successful large-scale application of canvas tables in California gold mills he abandoned all shaking motion, although he had patented canvas tables to which such motion was applied.

Jan 11, 1913

The Government has for disposal a large stock of horse-drawn vehicles that were produced during the war to transport and handle all kinds of army supplies. These vehicles consist of escort wagons, also the axles and wheels; ambulances, model 1909; sprinkler, wagons, buckboards, combat wagons, hand carts, water carts, ration carts, and medical carts. These vehicles are adapted to numerous commercial purposes. All were produced under the strictest Government rules, specifications, and supervision and are first class in every way.

Jan 6, 1919

By H. Foster Bain

This is the third volume of the collective index of the Transactions Each volume is indexed and the indices of Volumes I to XXXV have been collected into a single index volume, similarly the indices of Volumes XXXVI to LV are collected in a single volume This index covers Vol¬umes LVI to LXXII, and the three index volumes together cover all the volumes of Transactions published from the organization of the American Institute of Mining and Metallurgical Engineers in 1871 until the end of 1925.

Jan 1, 1926

Jan 1, 1901

By BION J. ARNOLD

WE can, I think, rightfully claim, irrespective of our faults, that engineers must, in order to last as engineers, possess the qualifications of integrity, stead- fastness of purpose, ability to think straight, and to apply these qualities consistently and continually in their everyday work. All engineers know this, most of them conform, and in order to drive it home I might, if 'clothed with proper authority, preach to you at length, but I shall not take the chance. So I only want to make a suggestion or two to the young engineers. Have an ideal and work toward it. You will have your disappointments and your temptations but keep your record clean, and if anyone says you are foolish or ugly, or homely, or that you need a guardian, take the criticism with a smile, for he may be able to prove his contention; but if he attacks your integrity, strike at once and fight hard, for he has assailed not only your character but your principal asset as an engineer.

Jan 1, 1929

By T. Sterry Hunt

At the meeting of the Institute in Easton, October, 1873,I made a communication on the Ore Knob copper mine, in Ashe County, North Carolina (Transactions, vol. ii, p. 123), in which I called attention to the chemical decomposition alike of the pyritous lode and the inclosing gneiss rock to a depth of 60 feet, by which the feldspar of the latter had been converted into clay, and the whole rock very much softened. Such a decomposition is well known to be almost universal in the crystalline rocks of the Appalachians south of the Potomac; and if it is only seen in rare and exceptional cases farther to the northward, this, as I have elsewhere pointed out, is due to the fact that the decomposition began and ended in the ages anterior to the drift period, and that the decayed portions which still remained were at that time removed from the surface, except in some localities which were protected from the emding agency. I have lately had an opportunity of studying a remarkable instance of this kind in an examination made last month for the corporators of the Hoosac Tunnel.* The locality is at the western base of Hoosac Mountain, the western slope of which rises rapidly 1300 feet above the town of North Adams, in Berkshire County, Massachusetts, itself 700 feet above the sea level. Through this mountain, as is well known, a tunnel for the Troy and Boston Railroad has lately been opened, a distance of 25,081 feet from east to west. The rock of the mountain consists of mica schist and micaceous gneiss, including in its western half a great mass of harder feldspathic and quartzose strata in part a granitoid gneiss, the strata for the most part dipping to the eastward with variable angles, but with occasional western dips, apparently due to inversion. The crystalline strata of the mountain crest and sides are in many places exposed, and present rounded surfaces, often deeply grooved and striated, but with no appearance of decay. At the western base of the mountain, however, the gneissic rock is in a state of complete decomposition, which was well displayed in opening the tunnel, which, for a distance of several hundred feet, was driven through highly inclined strata so much decomposed that they were excavated with pick and shovel, and without the aid of blast-

By Charles W. Merrill

IF we follow the threads of the mining problems, upon which I have touched, we find them all leading to one great fundamental desideratum. The people of this State, of this Nation, and of this world must be brought to a better understanding of the basic nature of our industry-must be made more mineral-minded. It is my belief 'that there is not a man present among this earnest gathering of those interested in the mining industry, who has not a deep-seated and heartfelt desire that the existing unprecedented welfare and prosperity of the whole mass of American people be maintained not merely through our own generation but through the generations of our children and their children. In the decades to come there can be no question of the keenness of the foreign competition which we are doomed to meet, and in this great international contest that Nation which has the best balanced program of development and that broadness of vision in its governmental direction, which recognizes the necessity of a sympathetic attitude toward the upbuilding of such a broad pro- gram will be the Nation which will maintain and pre- serve that welfare of all of its people.

Jan 1, 1929

ONE of the perplexing problems that face the translator of an old technical treatise is the question of terms for units of weight and measure. We have used an English word only when it is linguistically equivalent to the Italian one and is a unit of approximately the same size. Libbra and oncia thus become pound and ounce, for the actual weights were within 10 per cent of the modem Troy weights. On, the other hand, the length measures braccio, palmo, and dito, which could be rendered literally as arm, palm, and finger or digit, respectively, have no good English metrological equivalents and it has seemed best to retain the Italian words. The exact transfer of Biringuccio's weights and measures into modern terms is impossible because of the uncertainty as to his standards. Even as late as 1803, when the metric system was first introduced into Italy, practically every city had its own standards. There were, for example, at least eight different palmi, varying from 22.3 to 29.2 centimeters. The values listed below for the various units mentioned by Biringuccio are the Florentine ones, which were also used in Siena and Tuscany: [ ]

Jan 1, 1942

Jan 1, 1933

By E. C. Roberts

TO facilitate some recent microscopic investigations it was necessary to devise special mounting techniques for the polishing of two quite different metallographic specimens. These techniques are extremely simple and are submitted for whatever value they may be to other investigators. The first specimen mount proved very satisfactory for the study of untempered martensite. Since it was undesirable to heat the specimen, lucite or bakelite mounting materials could not be used in the conventional manner. A cold mount was made by drilling a hole of the same diameter as the specimen in a cylindrical piece of polystyrene then press- ing the steel specimen into the hole on an ordinary vise. A prefabricated disk of lucite should work equally well. The only precautions necessary are that the hole be drilled out cleanly and the piece of steel be pressed into the plastic uniformly, otherwise the mount will crack. The second type of mount was required for the study of slag specimens by reflected light. Mounting these specimens in bakelite and then attempting to rough finish the surfaces on graded emery papers resulted in a considerable amount of chipping and breaking out of the slag particles. This made further satisfactory polishing almost impossible. It was found, however, that if the bakelite-mounted specimen was first rough finished to a point where a good specimen surface became visible, the interstices in the specimen surface could be filled and the polishing completed. This filling was accomplished by placing a small amount of lucite powder in the bottom of the steel specimen mold then reinserting the bakelite-mounted specimen on top of the lucite powder. Reheating the mold to the proper temperature and applying the required pressure resulted in the formation of a thin disk of lucite on the bottom of the bakelite specimen. By carefully grinding the lucite away a uniform surface including the slag specimen was obtained and further polishing was unhampered by slag disintegration.

Jan 1, 1951

By Robert B. McCormick

World War II has developed a use for the nonmetal mineral quartz crystal that was unknown in World War I. During the interim period of peace, experimental work in the radio field with the piezoelectric properties of quartz crystal resulted in the almost universal adoption of quartz-crystal radio oscillator plates to control frequency in radio broadcasting, police, commercial and amateur communications equipment. Telephone resonators and filters made from quartz crystal also were developed, which vastly improved the frequency control of long distance telephone circuits. Expansion of the Industry The sudden war demands of the armed services for radio equipment using quartz crystal for frequency control led to an unprecedented expansion of the manufacturing industry. It is estimated that the 1940 peacetime volume amounted to approximately $1,500,000, while today a vast new quartz-crystal industry supplies more than $150,000,000 worth of quartz oscillator plates to the Army and Navy each year. This demand has caused an enormous expansion not only of American manufacturing facilities but also of Brazilian mining output, virtually our only source of raw quartz crystal. Actual figures of imports and consumption cannot be cited, for security reasons, but certain comparisons have been made, which indicate the transformation of quartz crystal from a minor to a major nonmetal. Lundl has shown that the value of quartz-crystal exports from Brazil is now about equal to that of phosphate rock produced domestically in 1941 and actually exceeds the combined value of crude feldspar, gypsum and fluorspar production in the United States in the same year. This great expansion under wartime pressure was not accomplished without some anxious moments, but all the demands of industry have been met and the Government has been able also to accumulate a substantial stock pile of material against future contingencies. Inspection and Grading of Quartz Crystal The swift growth of the quartz-oscillator industry necessitated the simultaneous evolution of methods and criteria for inspecting and grading quartz crystal. It has been found that, generally speaking, it is economically feasible to cut only crystals that are at least 30 per cent by volume free from major defects such as optical and electrical twinning, cracks and fractures. Blue needles, bubbles, "chuva" and other minor imperfections can be tolerated in the usable portion unless present in great excess. The present marketing system in use in both Brazil and the United States, as far as quality is concerned, depends solely on the "usability" of a crystal, which is defined in the Brazilian-American agreement2

Jan 1, 1948

By Robert B. McCormick

World War II has developed a use for the nonmetal mineral quartz crystal that was unknown in World War I. During the interim period of peace, experimental work in the radio field with the piezoelectric properties of quartz crystal resulted in the almost universal adoption of quartz-crystal radio oscillator plates to control frequency in radio broadcasting, police, commercial and amateur communications equipment. Telephone resonators and filters made from quartz crystal also were developed, which vastly improved the frequency control of long distance telephone circuits. Expansion of the Industry The sudden war demands of the armed services for radio equipment using quartz crystal for frequency control led to an unprecedented expansion of the manufacturing industry. It is estimated that the 1940 peacetime volume amounted to approximately $1,500,000, while today a vast new quartz-crystal industry supplies more than $150,000,000 worth of quartz oscillator plates to the Army and Navy each year. This demand has caused an enormous expansion not only of American manufacturing facilities but also of Brazilian mining output, virtually our only source of raw quartz crystal. Actual figures of imports and consumption cannot be cited, for security reasons, but certain comparisons have been made, which indicate the transformation of quartz crystal from a minor to a major nonmetal. Lundl has shown that the value of quartz-crystal exports from Brazil is now about equal to that of phosphate rock produced domestically in 1941 and actually exceeds the combined value of crude feldspar, gypsum and fluorspar production in the United States in the same year. This great expansion under wartime pressure was not accomplished without some anxious moments, but all the demands of industry have been met and the Government has been able also to accumulate a substantial stock pile of material against future contingencies. Inspection and Grading of Quartz Crystal The swift growth of the quartz-oscillator industry necessitated the simultaneous evolution of methods and criteria for inspecting and grading quartz crystal. It has been found that, generally speaking, it is economically feasible to cut only crystals that are at least 30 per cent by volume free from major defects such as optical and electrical twinning, cracks and fractures. Blue needles, bubbles, "chuva" and other minor imperfections can be tolerated in the usable portion unless present in great excess. The present marketing system in use in both Brazil and the United States, as far as quality is concerned, depends solely on the "usability" of a crystal, which is defined in the Brazilian-American agreement2

Jan 1, 1948

By George E. Roberts

The maintenance of the common gold standard is the most important cooperative undertaking in the world. The war broke up this relationship and brought about a state of great disorder in the currencies and exchanges. After the war the countries all began to grope their way back to the gold standard as the best means of establishing trade and financial relations with each other. With this movement began a general decline in commodity prices. The question has been raised whether the world's return to the gold standard was not forcing prices back to the prewar level. Also, the question is raised whether the world has not outgrown the supply of gold as the basis of credit. Because Europe readjusted its monetary units to conform to the higher level of prices there is no pressure on prices on this account. Furthermore, a large amount of gold formerly in hand-to-hand circulation passed out of circulation and has been added to the central bank reserves. The gold reserves of 36 countries increased approximately 100 per cent from the outbreak of the war to June 30,1930. The increase is much larger than the average increase of prices in any of the important countries, at any time since 192.5. As gold in the central banks of issue is far more effective for all business purposes than gold in circulation, the gold scarcity argument has little basis as applied to this time. The abnormal distribution due to the war was to the disadvantage of business everywhere. Credit was scarcer and dearer in some countries. The inflation in this country might have been greater had the production of gold been greater. The argument supporting the theory of a scarcity of gold assumes as fundamental that general price changes must be accounted for by changes in the price equation on the side of money. This is disproved in every period of business depression. A downward price movement is characteristic of every period of business recession. Important discoveries of gold must be made even to maintain present gold production, in the face of which the world's business is bound to continue increasing. It cannot be doubted that some way will be found

Jan 1, 1931

Jan 1, 1941

By G. K. Dumbauld, B. E. Morgan

A satisfactory well-cementing composition must retain its fluidity long enough to be pumped into Place; then it must develop within a reasonable length of time sufficient strength and impermeability to anchor the casing in position and to form an effective seal between the casing and the formations. These properties may be evaluated by pumpability, strength (compressive or tensile), and permeability tests. Laboratory test procedures for the determination of pumpability time and strength development have been outlined previously and are readily available,1 but a satisfactory and convenient laboratory procedure for the measurement of the permeability of set cement has not been developed heretofore. some permeability data have been obtained previously by passing air through dried cement specimens.2 such a procedure is unsatisfactory because the drying of set cement alters it physical and chemical properties and subjects it to conditions dissimilar to well conditions. A more realistic method would be one wherein the cement remains water-saturated durin

Jan 1, 1952

By J. G. LECKIE

During the first ten months of 1943 copper was produced at a higher rate than in 1947. However, on Oct. 24 one of the large mines was shut down due to a strike. As of Dec. 31 the strike was still in effect and had already resulted in a loss of production of 50,000 tons of copper. The demand for copper was considerably greater throughout the year than the supply. The price of electrolytic copper delivered at the Atlantic Seaboard refineries advanced from 21.20 to 23.20 cents per lb during the year. This sustained demand for copper, together with the increase in price, has had the natural effect of spurring interest in uncovering new deposits, and in re-examination of known low-grade deposits and old tailing clumps. This is in addition to the usual reevaluation activities which normally result from the constant improvements in efficiency of ore concentration.

Jan 1, 1949