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By G. A. Hellstrand

IN 1915, H. A. Guess, Vice President of American Smelting & Refining Co., in charge of its Mining Department, learned that the Anglo-New-foundland Development Co., Ltd., a pulpwood and paper-mill enterprise, had found upon its large concession in Newfoundland, and had opened up by shaft to the third level and some drifting, a lenticular orebody indicat-ing about 100,000 tons, as an extremely fine-grained sulfide ore, averaging about 0.05 oz. Au, 4 oz. Ag, 1.5 per cent Cu, 10 per cent Pb, 18 per cent Zn; and that having sent parcels of this ore to Minerals Separation, Ltd., and various other metallurgical testing concerns without obtaining any success in commercial separations thereon, had discontinued work thereon and let the workings fill. Mr. Guess wrote to the general manager of that company and obtained a few hundred pounds of the typical ore, which he sent to his company's metallurgical testing laboratory at Flat River, Mo., outlining various flotation tests desired thereon, in an endeavor to obtain separation into a commercial lead concentrate and a zinc concentrate. But the art of flotation had not then progressed far enough to treat such ore, the galena and zinc blende being so fine grained that grinding to about 300 mesh was required to release the mineral particles in their gangue. Mr. Guess had flotation and other tests continued upon this ore from time to time with whatever new reagents and flotation devices were evolved as time went on, and finally, in 1925, he succeeded in effecting in his company's testing plant, then at Wallace, Idaho, separations into lead concentrates and zinc concentrates of satisfactory commercial grade. Mr. Guess then proceeded to unwater, examine and sample the property and made with the owners a partnership operating agreement upon the mine itself and a considerable area surrounding it, and in the early summer of 1926 began to prospect for additional orebodies, utilizing for such prospecting geophysical methods, under the direction of Hans Lundberg, methods which up to that time had been little used in mining in the western hemisphere.. This geophysical work found two large flat-lying orebodies of a type precisely similar to the smaller body of the original discovery. The larger orebody, some 3500 ft. west of the original

Jan 1, 1934

The Institute is custodian of funds for support of numerous gold medals and prizes and has representatives on boards awarding still others. Details regarding the Institute Awards are given be- low. The Institute is represented on the boards of the John Fritz Medal, the Hoover Medal and the Washington Award, in connection with the three national societies of Civil, Mechanical and Electrical engineering; and, also, in the case of the Washington Award, with the Western Society of Engineers. The Institute is represented with these four societies on the committee in charge of the Alfred Noble Prize.

Jan 1, 1934

By Charles R. Wraith

The property of the Roan Antelope Copper Mines, Ltd., is situated at Luanshya, north central part of Northern Rhodesia, and is connected with the main line of the Rhodesia Railways, Ltd., by a 24-mile branch line from N'dola. Most of the material and supplies that are not available in Africa are shipped into the country via Beira, on the East Coast of Africa, a distance of 1473 miles from Luanshya and the nearest ocean port. The output of copper is shipped by rail to Beira and thence by boat to the market. Passenger travel is mostly via Cape Town, a distance of 2162 miles from Luanshya. Excellent passenger trains operate on regular schedules between Cape Town and Northern Rhodesia. Luanshya is 13" south of the equator at an elevation of 4000 ft. above sea level, and has a mild healthful climate. During the rainy season, from October to March, the rainfall averages 53 in. The area is profusely covered with vegetation. An ample supply of water for industrial and domestic purposes is available throughout the year. The more important supplies for smelting purposcs, such as wood, coal, limestone, silica, quartzite, and clay for "dolly" mud, are conveniently available. Excellent grades of coal, coke and firebrick are obtained from the Wankie Colliery Co., Ltd., Southern Rhodesia. The Wankie colliery has just completed the erection of equipment for the manufacture of silica brick. An ample supply of quartzite of good grade is available for this purpose. Silica brick is also obtained from the Belgian Congo and from India. Limestone is quarried from a large deposit a few miles from Bwana Mkubwa, which is 30 miles by rail from the smelter. An abundant supply of clay for " dolly " mud and for lining launders is available within a short distance of the smelter. Metallurgy Copper is contained in the ore as chalcocite, chalcopyrite and bornite. Chalcocite predominates in the eastern end of the orebody almost to the exclusion of other copper minerals. The amount of chalcocite decreases with a corresponding increase of chalcopyrite and bornite toward the western extension, where the latter predominate.

Jan 1, 1934

By W. A. Selvig

BY plotting fixed carbon against British thermal units of coals free from mineral matter, and ranging in rank from anthracite to lignite, it is found that the coals of higher rank, from anthracite to the higher rank of the high-volatile bituminous coals, inclusive, can be separated into groups according to their degree of metamorphism by reference to their fixed carbon. Such charts show also that the coals lower in rank can be best separated into groups with respect to B.t.u., especially when plotted on the moist basis, that is, coal containing its natural bed moisture. A tentative scheme for coal classification was presented at the October, 1932, meeting of the Technical Committee on Scientific Classification, of the American Standards Association Sectional Com-mittee on Coal Classification. This scheme was sponsored by Sub-committee IV on Tentative Classification of Coals, under the chairmanship of W. T. Thom, Jr. It proposed the grouping of coals according to rank by reference to fixed carbon and B.t.u., on the basis of coal containing its natural bed moisture but free from mineral matter. This scheme proposed classifying coals into four broad classes: (1) anthracitic, (2) bituminous, (3) subbituminous, (4) lignitic.. The anthracitic class was divided into three groups designated as meta-anthracite, normal anthracite, and semianthracite. The bituminous class also was divided into three groups, low volatile, medium volatile, and high volatile. The high-volatile group was further subdivided into four subgroups according to moisture content, as follows: (1) less than 5 per cent, (2) 5 to 10 per cent, (3) 10 to 15 per cent, and (4) 15 per cent and more. The subbituminous class was divided into two groups, group, 1 including subbituminous coals having calorific values of 10,500 B.t.u. or more, and group 2 including those with less than 10,500 B.t.u. , The lignitic class of coal was divided into two groups both below 8,000.B.t.u., the one group consisting of consolidated and the other of unconsolidated

Jan 1, 1934

By C. E. Mills

STUDIES of ground movement and subsidence resulting from mining operations cover a broad field. It is also a very important consideration and one that eventually affects nearly every mining operation of any extent. The damage to surface buildings, removal of mine surface plants and replacements of main hoisting shafts must reach an astounding expenditure were these cost figures available over a period of years. Were the subject one of mathematical formula and dependent only on the angle of draw of the walls or country rocks, the problem would be relatively simple. Consideration must be given to depth and extent of workings; structural conditions of the orebodies and enclosing country rock; physical properties of these same rocks, including schistosity, bedding, jointing, slips, dikes, faults, and other structural weaknesses. The method of mining, extent of openings, supporting pillars, and amount of moisture or water underground are other pertinent factors. With such a large number of variable factors, it is apparent that the subject of subsidence is one that must be based largely on experience and results at other mines where conditions are somewhat comparable. In presenting this paper, it is the intent to describe the progressive results of past ground movements at the United Verde, to bring out physical conditions largely responsible for this movement, but to refrain from theorizing on the ultimate extent of subsidence resulting from future mining operations.

Jan 1, 1934

By Charles W. Allen

The Athens mine is in the city of Negaunee, Mich. It is one of the larger producers of soft hematite ore on the Marquette iron range. The property is held under lease by the Athens Iron Mining Co., and is operated by the Cleveland-Cliffs Iron Co., which is a partner with Pickands, Mather & Co. in the Athens company. The mine was opened in 1913, and shipments of ore commenced in 1918, the total reaching 3,063,711 tons up to Jan. 1, 1932. Diamond-drilling from surface, together with a knowledge of geological conditions in neighboring properties, gave a comprehensive picture of the location, size and shape of the orebody before shaft-sinking started. Striking east and west, the orebody entered the east boundary of the property at a depth of about 1500 ft. below surface. A pitch of 15" to the west carried it down to about 2500 ft. on the west boundary, about double the depth of that of any soft-ore property heretofore worked on the Marquette Range. The width of ore averaged close to 500 ft., and the thickness 300 feet. The depth of the deposit and its size, together with an overburden of quicksand, which in places reached a thickness of 150 ft., presented unusual mining problems. The use of a caving system made surface drainage into the orebody inevitable, because the north boundary of the deposit was a vertical diorite dike 200 ft. wide, and the south boundary a northward-dipping impervious slate. S. R. Elliott, manager of the mining department of the Cleveland-Cliffs Iron Co., who was superintendent of the mine at that time, conceived the idea of starting at the bottom of the orebody and working upward, reversing the usual mining procedure. This innovation divided the Athens orebody into a series of steps, or blocks, the first of which was adjacent to the western boundary, and therefore in the lowest portion of the deposit. Top-slicing was to start under the capping in this first block by raising from the bottom level, and development and mining were to progress upward in successive blocks to the east. A complete description of the Athens system of mining was

Jan 1, 1934

By Newell G. Alford

The data in this paper were collected to show both the volume and speed with which bituminous mines have indefinitely suspended operation while economic advantage in the industry has so gravely declined. The study was limited to the bituminous coal-mining states east of the Mississippi River, wherein conditions affecting production and demand are more common respectively to all of the mining districts included and represent about 95 per cent of the nation's coal mining. Data for the compilation of these statistics and for the construction of these graphs have been obtained in all cases from state mine department reports, except from those of Ohio and Virginia. In Virginia essential individual mine data were secured from an authentic source, but no individual Ohio mine information is obtainable, because all Ohio fact-gathering agencies are prohibited by law from revealing such data. In other states the facts were tabulated and later checked with the cooperation of Chief Mine Inspectors. In all, excluding Ohio, over 17,000 individual annual mine returns were examined. Special information was secured from each state mine department about suspensions in 1932. Accurate information was not available from all states about nine abandonment due to exhaustion of coal reserves, and while these were completed for several states, it has not been shown because it was not perfected for all states. However, the total observed sample mas comprehensive enough to show that exhaustion accounts for a very limited part of the suspended production. Wherever mention is made of '(suspended productionJ' the largest annual output of the mine in the five years prior to suspension has been taken as the measure of its probable production had it continued to operate. A mine is not regarded in this category, as having suspended, when it merely ceases to produce. The word "suspension" is used only where there is a complete abandonment of activity for an indefinite period, as evidenced by the fact that both ventilation and pumping are discontinued.

Jan 1, 1934

By Carl Samans

THE attention of physicists and metallurgists has been directed toward the study and explanation of the deformation textures in metals for the past 15 years. In 1920 N. Uspenski and S. Konobejewski1 were first able to show that the symmetrical X-ray diffraction effects that had been previously reported by E. Hupka2 and others in metal foils were caused by a directed arrangement of the crystallites. Since then, the systematic study of textures resulting from the application of the pure forces of tension or compression to polycrystalline materials hag been supple-mented by many investigations on deformed single crystals, which have greatly added to our knowledge of deformation. However, despite the valuable information secured from these comparative studies only four investigations upon cold-rolled single crystals of any of the face-centered cubic metals have been reported in the literature. This lack of quantita-tive data is especially unfortunate because of the much greater practical significance of rolling textures and their effects in both cold-rolled and annealed materials. This investigation was undertaken for the purpose of specifying the deformation of rolled single crystals in the hope that such information might later facilitate the explanation of polycrystal-line textures.

Jan 1, 1934

Alder, John W., Student, Mass. Inst. of Tech Cambridge, Mass. '38 Allen, Charles F Mines McFarland, Cal. '34 Anderson, Norman John, Student, South Dakota School of Mines Rapid. City, S. D. '32 Ansel, Gerhard, Student, Mass. Inst. of Tech Cambridge, Mass. '34 Arakelian, Haig Mark, Student, Inst. of Tech Cambridge, Mass. '34 Archer, George K., Student, Colorado School of Mines Golden, Colo. '34 Arnot, Paul H. 608 S. Acacia St., Compton, Cal. '31 Asel, Philip R., Student, Colorado School of Mines Golden, Colo. '32 Augenthaler, Robert L., Student, New Mexico School of Mines Socorro, N. M. '32 Augustine, Robert W. Address Wanted. '32. Austin, Robert B., Student, Univ. of Idaho Moscow, Idaho. '34

Jan 1, 1934

Jan 1, 1934

By W. K. Lewis

During the last decade the petroleum refinery engineer has made great progress in achieving a better understanding of the physical behavior of hydrocarbon mixtures, with particular reference to their pressure-temperature-volume relationships, the mechanism of the evaporation of liquids, the condensation of vapors, including the changes in composition, and the heat effects accompanying them. With the new insight into the mechanism of movement of oil and gas through the formations in which they occur, achieved by the production engineer, it is clear that the latter will need to utilize in the solution of his own problems much of the information outlined above. It is the purpose of this paper to outline the portions of that information that seem most certain to prove of importance in production work. Properties of Pure Hydrocarbons While it is true that petroleum always consists of highly complex mixtures of hydrocarbons, none the less understanding of the behavior of the mixture must be based upon a knowledge of the properties of the pure components. However, in view of the tremendous number of hydrocarbons existing in petroleum, the determination and formulation of the properties of all of them would seem a discouraging task. The difficulty of the situation is increased by the undoubted facts that the overwhelming majority of chemical individuals in petroleum have never been isolated as pure compounds, none of their physical properties have been determined and even their chemical constitution is unknown. The situation would be hopeless were it not for the fact that certain extraordinary correlations of important properties of various hydrocarbons have been discovered which make it possible to predict those properties for a given chemical individual on the basis of a very limited characterization of it. Thus one can predict the vapor-pressure curve of an unknown hydrocarbon over a considerable range from the knowledge of a

Jan 1, 1934

By M. Muskat, R. D. Wyckoff

The general problem of the simultaneous movement of water and oil in a connected sand is of considerable practical interest from two points of view. First, there is the situation usually described as "edge-water encroachment." Here the water in the sands contiguous to and flanking the oil sand begins to enter the latter as the oil is removed and the reservoir pressure declines. The physical questions involved concern an understanding of the mechanism of the advance of the water and its control, so as to aid the oil recovery rather than to hinder it. In so far as the entry of the water into the oil sand means at least the partial replacement of the oil from the region of the encroachment by the advancing water, it is quite appropriate to consider this type of situation as one of natural water-flooding. For the present discussion, however, we are primarily interested in the problem of artificial flooding. Here the water is deliberately injected into the oil sand with the intention of displacing the oil and removing it through prearranged output wells. For the practical development of such a procedure rather large areas are included in the flooding program and the injection and output wells are arranged in regular patterns or networks, which are felt to be most favorable for a high oil recovery. Although remarkable success has already been obtained in such flooding programs, especially in the Bradford field of Pennsylvania, essentially by the application of the lessons of practical engineering experience, a more thorough physical analysis of the problem appeared to offer promise of leading to results of some interest and value. Another phase of the problem, which stimulated both the experimental and mathematical analysis, is that it is susceptible in large measure to empirical field tests. It, is in itself but an example and illustration of the general theory of the flow of dead (gas-free) liquids through porous media, in which the authors have been interested for the last several years. From the point of view of its applicability to actual petroleum technology problems, however, water-flooding is a particularly favorable

Jan 1, 1934

By H. De Cizancourt

Peche1bronn.—So far Pechelbronn is the only producing district. Figures are given in Table 2 covering the main features of the field, but these figures call for the following remarks: First, Pechelbronn should not' be considered as a single unit, it appears, but as a succession of small oil fields, each of which is affected by very variable conditions. Consequently, certain figures concerning production per acre, production per acre-foot, pressure conditions and thicknesses of oil sands would be so misleading that they have been omitted here. Second, as regards production methods, attention is drawn especially to the fact that 42 per cent of the oil is extracted by the use of shafts and galleries and the remainder by pumping wells. Exploitation, formerly confined to Oligocene sands, has been extended recently to Jurassic and Triassic oil-bearing formations. Gabian.—This small oil field, discovered in 1924, is almost exhausted. Exploitation to date is restricted to three wells. There were no drilling activities in 1933. Exploration.—During 1933, two exploration holes have been started in France. The first, in the vicinity of Lavelanet (Ariége) on the Dreuille anticline, has reached the depth of 2400 ft,.; the second, in the Autun Permian Basin, is drilling at 1300 feet. Northern Africa Morocco.—Drilling operations have been on a large scale in Morocco. In the Gharb district (Souk el Arba area), the deepest well was abandoned in 1933 at 7014 ft. Small irregular productive horizons were encountered in the Miocene at shallow depth, oil and gas showing in the Eocene, but no commercial oil field has been discovered. In the Djebel Tselfat, near Petitjean, a small production of oil was obtained from a Jurassic horizon. In the meantime deeper formations are being explored and a new structure in the vicinity is being tested. In Eastern Morocco, a well is drilling near Taza. Production in Morocco, about 2400 bbl., has not been listed on Table 2, owing to its origin—exploration wells.

Jan 1, 1934

By Frank Speller

WE are here to honor again the memory of Henry Marion Howe, one of the foremost metallurgists of his time, and it is indeed a great privilege to be called upon by the Board of Directors of .this Institute to give the memorial address this year. Professor Howe started active investigation of corrosion of iron from a metallurgical standpoint in 1887, and made several important contribu-tions to the subject from 1895 to 1908.(1) ? The papers named in the bibliography are only a few of his valuable papers, but in all his works he sets a high standard of scientific accuracy, together with a clearness and power of expression rarely equaled in engineering literature. There-fore it seems appropriate on this occasion to review the work on corrosion of this distinguished gentleman and then endeavor to make a brief inventory of what has been accomplished since his time. Howe saw the beginning of the steel industry in America and before he died (May 14, 1922) witnessed it develop to a production of 45,000,000 tons per year. He was naturally very much interested in the infant industry and was quick to see the importance of the question of corrosion. It was my privilege to discuss the subject of corrosion frequently with Professor Howe at various times from 1905 to 1908; in this, as in other metallurgical problems, he sought the truth without bias and always insisted on proving an opinion or conclusion before accepting it. We should remember that when Howe started his investigation of corrosion, in 1887, steel was rapidly supplanting wrought iron. Certain papers in the early eighties (now forgotten) claiming much greater durability for wrought iron than for steel aroused Howe's interest. He could not reconcile the statement that steel was intrinsically and incurably less durable than wrought iron with the continued and widening use of steel,

Jan 1, 1934

By Frank Foote, V. H. Nordstrom, Eric R. Jette, Bernard Queneau

The nickel-chromium alloys form the base for many industrial heating alloys, so that this system is of considerable practical importance. The literature on these alloys, however, contains much conflicting evidence, not only regarding the solubility limits of the terminal solid solutions at different temperatures but even regarding the number of phases existing in the system. Part of the difficulty undoubtedly arises from the fact that chromium of sufficiently high purity has been available only during the last few years. A second and possibly even more important difficulty arises from the ease with which chromium reacts with silicon and carbon compounds and the atmosphere to form silicides, carbides, nitrides and oxides. Pilling and Kihlgrenl in 1929 reviewed the existing scanty information. They did not consider the diagram by which they summarized the various bits of information to be entirely satisfactory. Matsunaga2 investigated the system by thermal analysis, microscopic examination and other means. Electrolytic nickel of 99.9 per cent purity and thermit chromium containing 0.30 per cent Al, 0.40 per cent Fe, 0.25 per cent Si and 0.04 per cent C were used. A Tammann furnace with hydrogen flowing through it was used for melting. Sekito and Matsunaga3 reported an X-ray investigation, presumably on these same alloys, which, as far as can be judged from the abstract, essentially confirmed the thermal and microscopic results. Nishigori and Hamasumi4 found compositions for the terminal solid solutions in equilibrium at the eutectic temperature which agreed fairly

Jan 1, 1934

By E. S. Shaw

Utah continues as a very unimportant factor in oil and gas production. During the year 1933 there were no developments of noteworthy significance. There were no completions of either producers or dry holes during the year. The only commercial production in Utah has been from the five fields listed in Table 1 and mentioned briefly in the following paragraphs. Virgin Field.—Oil was first discovered in 1907 in a well drilled in sec. 13, T.41S., R.12W. Of the first 15 wells drilled, all but three were failures. In 1920 production from four wells from 550 to 600 ft. deep was about 20 bbl. per day. San Juan Field.—The majority of drilling in this area was done during the years 1908 to 1911. Probably the first commercial well in the field was that drilled in NW.$i sec. 6, T.42S1 R.l9E., in 1909. Farnham Dome.—The discovery well was drilled by the Utah Oil Refining Co. in April, 1923. A number of years later a second well was drilled by The Carbon Dioxice a mica1 Co., the present operator, which markets the gas in the manufacture of "dry ice" and allied products. The eslimated production, as indicated in Table 1, includes 500 million cubic feet estimated to have been lost while drilling the discovery well. Cisco Dome.—The discovery well was drilled by The Utah Oil Refining Co. in November, 1924. The Crystal Carbon Co. markets the gas in the manufacture of carbon black. Ashley Valley Dome.—The discovery well was drilled by the Utah Oil Refining Co. in April, 1925. The Uintah Gas Co. markets the gas in Vernal, Utah, for fuel. Woodside Structure.—In February, 1924, gas was discovered in a well drilled by Utah Oil Refining Co. in sec. 12, T.l9S., R.l3N., on the Woodside structure. This gas is reported to contain an appreciable amount of helium. It is being held as a helium reserve by the United States Government. Salt Valley Structure.—The test of the Utah Southern Oil Co. in sec. 31, T.23S., R.21E., on the Salt Valley structure has been shut down for some time at 6120 ft. This test has passed through more than 5000 ft.

Jan 1, 1934

Jan 1, 1934

By Scott, Turner

IN 1933, the monetary metals were produced in a ratio of 6.7 oz. of silver to 1 oz. of gold, the lowest relatively for silver since the period from 1851 to 1865. At the beginning of that period, the virgin placers of California -and Australia began producing almost simultaneously; in consequence, there was an abrupt fall in the high silver side of the ratio that had prevailed through the centuries after America was discovered. The output from the Comstock and other silver-bearing lodes, located a decade after this influx of new gold began, soon restored the production ratio to its former proportion, that is, a relatively large weight of silver compared to gold.

Jan 1, 1934

By V. C. Smith

Reliable and detailed statistical data available for Kentucky, Ohio and West Virginia are the most meager and unsatisfactory of any of the producing states. Detailed histories and statistics are available for only a few pools. The antiquity of these pools, loose nomenclature, particularly where several names are applied to the same pool or various parts of the pool or a new namsed when the pool was rediscovered, made the collection of accurat historical and statistical data almost impossible. So many of the data reported are unreliable that a breakdown by pools or even by counties, until more accurate information is available, would lead to gross errors. Rather than perpetuate inaccuracies, we have endeavored to go to original sources wherever possible, sift these and provide data that may serve as an incentive and basis for future work. The necessity for accurate information is thoroughly recognized by the operators, particularly because of the effect of recent government regulations and request? for data in connection with the preparation of the various codes a pending legislation. Producers, both major operating companies and individuals, . freely given their time and assistance in the compilation of these data. Valuable information was obtained from tax records, rate cases, statistics published by the oil and gas publications and the Bureau of Mines. So many individuals cooperated in the preparation of these data that individual credit cannot be given. Undoubtedly many errors will be found. Some of the data are open to controversy, and many have been omitted in the hope that new information of a more reliable character may become available. Other omissions are due to an inability to contact the proper individuals, many of whom are no longer connected with this industry. Pennsylvania grade crude sold in 1933 for the lowest price since 1895. Gas production could not find sufficient new markets to fill the void left by industrial stagnation. In the gas industry, where the market price is fixed by contract, uncertainty persisted because of impending legislative action affecting both taxes and utility rates. As a result of these factors and a lack of new money, drilling was restricted to a new low. The lifting of proration toward the end of the year in the Pennsylvania

Jan 1, 1934

By Alexander Gow

THE object of this paper is to discuss the fundamental principles of ball milling and to present some observations which have been made in laboratory and plant investigations. The discussion will be limited to wet grinding of ores in cylindrical mills, but doubtless many of the principles involved will be equally applicable in the other fields of fine grinding in which mills of the same type are used. In the concentrators of the United States there are about 650 ball, rod, or pebble mills, operating or ready to operate, and these have about 100,000 connected horsepower. For grinding in cement plants there is about three times this connected horsepower, and other industries have an unestimated amount, all used for the general type of grinding that is to be discussed here. It is true that these figures do not represent stupendous amounts of power, but when one considers that ball milling is often the "bottle neck" in a concentrator and that it often accounts for the largest single item in the cost sheet, the importance of a compre-hensive understanding of the principles of ball milling can be appreciated. Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses, or with the exclusive consideration of certain specific varia-bles, such as mill speed or circulating load, irrespective of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison, a new philosophy in the study of ball milling. Briefly, this "new philosophy" consists of using power as an index of the mill operation, and investigating grind-ing from the standpoint of set and induced variables, with emphasis on the latter.

Jan 1, 1934