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By Keith E. Robinson, Brian Stimpson

INTRODUCTION In inclined sedimentary strata slope failure may occur by sliding along bedding and along a discontinuity or weak zone, as illustrated in Fig. 1. This mode of failure may be called 'bi-linear', as the failure surface is comprised of two linear or approximately linear segments. This type of failure has been suggested for the famous Frank Slide, Alberta, Canada (Cruder and Krahn, 1973) in which an estimated 90 M 5 tons (8.97 x 10 MN) of rock separated from Turtle Mountain and buried the town of Frank. Also, with the increasing depth of open pits and the construction of highways through inclined sedimentary strata this mode of failure is of major concern to the rock slope stability engineer. A computer program for calculating factors of safety for this slope failure mode is provided and includes the ability to vary shear strengths of potential slide surfaces, ground water elevations and wedge geometry. LIMITING EQUILIBRIUM MODEL The simple limiting equilibrium model used in the analysis is shown in Fig. 2. It is assumed that jointing is orthogonal to bed- ding and that the interface between the upper and lower wedges there- fore corresponds to a joint plane or planes. No shear strength is attributed to the interface so that the resultant force, P, from the upper wedge acts normally across the interface. The normal loads

Jan 1, 1983

By D. C. Reynolds

Recent experiments with II-VI compounds have shown that they hazle considerable potential for laser applications over a broad region of the optical spectrum. It may be possible to cover the spectrum continuously from 3200A (ZnS) to the far infrared (CdHg:Te) since HgTe is a semimetal. At this writing laser action has been observed in ZnS, Zn0, CdS, CdSe, CdS:Se, CdTe, and some of the CdHg:Te alloys. Of particular interest are those lasers operating in the zlisible and near ultraciolet regzons of the spectrum where detectors of high sensitivity are available. The lasing transitions in II-VI compounds are bound exciton transitions some of which have been identified in auxiliary experiments. High efficiencies and low thresholds for lasing hare been achieved almost exc1usively in plutelet-type crystals. The greater crystalline quality exhibited by the phtelet-type material is shown to result from the crystal growth habit. Phonon scattering- of conduction electrons to the ground-state exciton is discussed ill relution to Lou thresholds and high efficiencies for lasing- observed in the CdS:Se solid solutions. The first successful semiconductor laser operation was achieved in the III-V compounds. It is possible to choose a material in this group that will operate between approximately 0.65 and 8.5 . There are at least two reasons why one would like to have a laser operating at shorter wavelengths. First, it would be easier to experiment with a laser operating in the visible region of the spectrum, and also more desirable to have high-in tensity visible light sources. Second, the most sensitive photomul-tiplier detectors are available in the visible and near ultraviolet regions of the spectrum. It is known that II-VI compounds are direct-band-gap semiconductors and as such offer the potential of operating at any specified wavelength between 3200 (ZnS) and 7772A (CdTe). Light emission from II-VI compounds has been the subject of numerous investigations for many years. These investigations were all primarily concerned with noncoherent emission. It has been only recently that coherent emission from these compounds has been observed. To date, laser operation has been demonstrated in CdS, CdSe, and the solid solutions of CdS:Se, ZnS, ZnO, and CdTe. These compounds cover an appreciable portion of the optical spectrum from the ultraviolet to the near infrared. In considering laser applications, the use of lasers in communication's systems offers many desirable features. In any operation of this type one must consider the losses in transmitting the radiation from the source to the detector. Atmospheric absorption in the visible and near ultraviolet is variable and greater than in certain regions of the infrared. It might be concluded that for long-range communication systems an infrared laser operating in a spectral region that is coincident with a transmission window in the atmosphere would be preferable. However, one cannot overlook the possibility of operating a system in the sensitive region of a highly sensitive photomultiplier detector or other light-amplifying system. LASER CONSIDERATIONS To produce a source of coherent radiation it is necessary to achieve a population inversion. In the case of semiconducting materials it is necessary to raise the electrons from one energy state to a higher-energy state relative to it. In semiconductors, this population inversion can be achieved by three different techniques: 1) Current Injection. This technique uses a p-n junction biased in the forward direction. Large numbers of electrons are injected from the n region into the p region, and recombination occurs close to the junction. An inverted population is obtained in this region and the recombination radiation propagates parallel to the junction. This type of pumping has been used in the GaAs junction-type lasers but has not been successfully employed in the II-VI compounds. 2) Optical Pumping. In this case, one uses photons to obtain a population inversion by exciting electrons to higher-energy states. The pump sources are flash lamps or arc lamps and, occasionally, other laser sources when such sources have the appropriate energy for exciting the electrons. The disadvantage of this type of pumping is that flash lamps put out a rather broad spectrum of radiation, whereas the laser material has a rather narrow region of absorption. This results in an inefficient process. Laser sources provide efficient pump sources but the number of usable wavelengths is limited. 3) Electron Beam Pumping. In this technique, the laser sample cavity is bombarded with electrons having energies in the range from approximately 10 to a few hundred kv. The bombarding radiation excites electrons from valence to conduction band states in the semiconductor, giving rise to an inverted population. This type of pumping has been used successfully in several 11-VI compounds.

Jan 1, 1968

By L. A. Wright

Union Carbide Corp.'s Pine Creek mine in California is the largest known tungsten deposit in the West, and the producer of well over five million tons or ore to date. Located 21 miles northwest of Bishop on the eastern slope of the Sierra Nevadas, the mine is also a source of molybdenum and copper and it was the quest for the molybdenum which caused the mine management to undertake a pillar recovery program. GEOLOGY For a full discussion on the geology of the Bishop tungsten district and the Pine Creek mine, reference is made to Special Report 47, Calif. Div. of Mines. The deposit lies along a 3000 ft segment of the contact between quartz monzonite and the marble that flanks the west side of the north portion of the Pine Creek pendant. All the components of a typical contact metamorphic tungsten deposit are developed; these consist of tactite, light colored calc-silicate rock and quartzose rock.

Jan 5, 1964

By H. Ries

Introduction BODIES of pyritic ore in schistose rocks have long been known in different parts of the world. The several occurrences resemble each other in being usually of more or less lenticular shape, inclosed in walls of schist or gneiss, and carrying pyrite, chalcopyrite, and pyrrhotite in varying proportions, as the chief ore minerals. The deposits differ, however, in that sometimes one, sometimes another, of the three sulphides mentioned may predominate. The orebodies in general are more or less closely conformable with the schistosity of the wall rocks, although in cases this may not hold true. The boundaries may or may not be sharp, but in general are fairly distinct. The lenses vary in size, may occur singly, or in groups; in the latter case they may be in line, overlapping, or occasionally parallel. Pinching and swelling of individual lenses is not uncommon. The genesis of these pyritic bodies has provoked much discussion, and they have been variously classed as sedimentary, igneous intrusions, hydrothermal replacements or impregnations, etc. Indeed, in some cases different geologists have most positively assigned widely diverse origins to the same deposit, as in the case of Rio Tinto 1 and Rammelsberg.2 It is true that in the light of modern criteria, we have been able in a few cases to decipher clearly the process of origin and so there seems no doubt now regarding the genesis of the deposits at Rio Tinto, Spain;3 Rammelsberg, Germany ;4 Ducktown, Tenn.;5 southwestern Virginia;6

Jan 8, 1917

By Subhas G. Malghan

The response of feldspar flotation to tallow diamine dioleate collector in the presence of sulfuric acid is studied using batch flotation experiments. Application of this nonhydrofluoric acid (non-HF) reagent system in the flotation of mineralogically and chemically different feldspar ores is compared with that of the conventional hydrofluoric acid system. The dependence of flotation recovery and concentrate grade on feed particle size distribution, conditioning time, pulp density, and pH, combined variation of collector and acid addition rates, sodium hydroxide concentration in the collector solution, and initial pulp pH Prior to conditioning is studied. The results have been discussed in relation to applicability of the non-HF system to plant trials, and the nature of the collector adsorption in the selective flotation of feldspar.

Jan 1, 1982

By M. P. Boss

Of the two methods of mechanical reduction—that of percussion and that of abrasion—it is not easy to say which was first employed by primeval man. The stone hammer and the flat or hollowed stone used for grinding are found together in the remains of prehistoric periods. But the use of the maray, or bucking-stone, developed from the hammer, was probably introduced later than that of crude millstones. Diodorus Siculus, the Roman historian of the first century B. c., mentions such millstones as used in the mines of Egypt to pulverize material which had been previously broken in a mortar. The invention of the arrastra for fine grinding is declared by some authorities to have been made by Bartolomeo de Medina, at Pachuca, Mexico, about A. D. 1557—which is quite probable. Being the first to amalgamate silver on anything like a business scale, he must have felt the necessity for oregrinding apparatus of greater capacity than the old primitive millstones; and the arrastra was thus the natural successor of the millstone. It is very unfortunate that the archives of Pachuca, which has made so much history in ore-treatment, were destroyed in some one of the many insurrections for which, also, the place is renowned. The first application of the stamp to the crushing of rock is asserted by some writers to have been the invention of a Saxon nobleman named Von Maltitz, about the year 1505. Better authenticated reference, however, is made to one Paul Gronstetter, a native of Schwarz, and called an ingenious worker, who, in the year 1519, established at Joachimsthal a process of wet stamping and sifting. Two years later, a larger plant was established at the came place. It is said that he had previously introduced the same device at Schneeberg. How much of the invention was due to Gronstetter is not certain;

Jan 1, 1902

By E. H. Lovitt, A. C. Skerl

After nine years of continuous operation it is a good idea to take stock of the geological concepts that guide the working of a mine. This is a welcome opportunity to discuss the Lovitt gold mine, which has been a challenge in both the geological and operational fields. The occurrence belongs to the extensive group of epithermal gold-silver deposits once worked so vigorously in the western states, Hungary, and New Zealand and still producing in Central America and the Philippines. These deposits are characterized by a relatively shallow vertical range up to 2000 ft, and often much less, and by bonanza orebodies of even more limited range. The area in which they occur is frequently widespread, so that exploration must be directed along and across the strike of known favorable structures in search of repetitions.

Jan 9, 1958

By T. L. McCall

THE late Walter Herd1 in 1929 gave a full description of past and present conditions in No. 2 mine, Springhill, Nova Scotia, developed theories regarding the cause of these bumps and made certain suggestions regarding possible methods of future development. Recapitulating briefly from Mr. Herd's paper, the seam is bituminous coal, averages 9 ft. in thickness and has a well defined parting containing fusain about 14 in. from the roof. This roof coal is somewhat stronger than the rest of the seam and has a tendency to cling to the roof. The pitch of the seam where it is now being worked is about 20°. The first manifestations of bumps began when the room and pillar workings had reached a depth of cover of 1900 ft. and under continuously increasing depth of cover these bumps increased to such an extent, both in number and severity, that in the year 1924 it became apparent that some change in the system of extraction was necessary. After closely studying all the factors involved and benefiting largely by valuable out-side advice obtained by the Provincial Department of Mines of Nova Scotia,2 the system of working was changed from room and pillar to longwall retreating. Mr. Herd's paper described in detail three remarkable bumps in the year 1928 in April, July and October that affected the 5700-ft. and 5900-ft. East levels, the last bump being so severe both in intensity and in extent of damage done that this district was abandoned. The longwall workings to the west of the slope had been stopped in the year 1926 owing to an inbreak of water, coming from the flooded waste of No. 3 seam lying some 400 ft. vertically overhead. This inflow was not excessive, but a large quantity of water being impounded in the old workings it was considered advisable to take the prudent course and not incur the risk of possibly increasing the flow by further working. This district has remained idle ever since.

Jan 1, 1934

Discussion of the paper of PAUL BILLINGSLEY, presented at the New York meeting February, 1915, and printed in Bulletin No. 97, January, 1915, pp. 31 to 47. JAMES F. KEMP, New York, N. Y.-Mr. Billingsley has spoken so concisely that we may not realize the many important topics which he has passed in review and upon which lie has thrown much illumination. The exact determination of the age of the granite, itself, is one. If we were to look over a geological map containing the region of Butte and 25 years old, we would find this coarsely crystalline mass assigned, as were others of its kind, to the pre-Cambrian, or as we used to say, to the Archean. In the course of time it was found to be later. The Butte Special Folio, 1907, described it as post-Carboniferous and possibly post-Laramie. Mr. Weed in Professional Paper No. 74 of the U. S. Geological Survey (1912) placed it as probably Niocene because of its relations with the andesite, which was believed to be Eocene. Mr. Billingsley now by a very neat demonstration circumscribes it more definitely and we recognize that it must be latest Cretaceous or earliest Eocene. We see, however, that extensive field observations, ably correlated, were necessary to establish the conclusion. For some years all familiar with Butte have known that there was a central area the veins of which carried copper ores in a quartz gangue; and that outside this area there were veins carrying silver ores in a gangue of manganese minerals. Mr. Sales's able and detailed paper, read at the Montana meeting, August, 1913, not only corroborated these relations, but emphasized the transitional character of the intermediate or passage zone. Mr. Billingsley is now able to show from observations at increasing depths, the tendency of the copper ores to appear deep down in the veins

Jan 5, 1915

By V. G. Mooradian

THE diffusion of metal atoms into the crystal lattice of another metal and the assumption of regular positions to form a homogeneous alloy are some of the most fundamental phenomena of structural metallurgy. The mechanism of this process has been the subject of a great deal of study from many viewpoints, but the picture is still far from complete. It is generally believed that if one metal is to diffuse into another, the first must have some solubility in the second1. This means that the solvent must be able to accommodate the stranger atoms, either on points of its own lattice or in the interstices between, without losing its own crystal-lographic identity. It is also a general observation that cold-working is a distinct aid in the diffusion process, causing it to take place with greater rapidity at the same temperature or with the same speed at a lower temperature. There is considerable doubt, however, as to the real significance of the deformation in its effect on the diffusion mechanism. Several factors associated with the cold-working may be responsible for the increased diffusion rate. The plastic deformation causes a distor-tion of the solvent lattice, which may be an aid in the assimulation of atoms of another kind. There are many references2 in the literature that suggest that some distortion or "loosening" of the lattice is necessary for atomic migration and that diffusion cannot take place in the undis-

Jan 1, 1935

By Willis Burns

I. INTRODUCTION. These notes are submitted, not as a discussion of the modern practice of electrolytic-copper refining, but as the record of a refinery that was among the pioneers in the field and that is to-day, and has been for 17 years, operating under conditions not to be found in any similar plant in the country. I refer to the current density, which is at least 60 per cent. higher than that regularly employed elsewhere, and to the fact that the anodes treated are the direct product of the converter rather than of the reverberatory furnace. The writer has no knowledge of any other refinery treating anodes of this character.

Jan 8, 1913

By P. V. Roundy, G. R. Mansfield

PUBLIC lands in Florida were first withdrawn from entry by President Taft on July 2, 1910, as a conservation measure because of their possible phosphate content. The reserve thus established was subsequently modified by further withdrawals and by restorations, so that on Jan. 1, 1934, it contained 66,796 acres, of which only a small part had been definitely classified. The reserved land was in scattered parcels, ranging from less than 40 acres to 320 or more, distributed in many counties. For administrative purposes and for final disposal of any of the numerous parcels, mineral classification of the land is legally necessary. In 1934 and 1935 the United States Geological Survey, under two successive grants from the Public Works Administration, prospected some 83 tracts of these lands in Polk County, comprising in all about 3300 acres, and six tracts comprising 240 acres in Citrus and Marion Counties. The tracts in Polk County were all in the so-called land-pebble field and the others in the hard-rock field. The Survey field party was under the direction of P. V. Roundy, from whose unpublished report the material in this paper is largely taken. The foreman of the prospecting crew was J. H. Wingate of Zephyrhills, Fla. The individual tracts were identified through the cooperation of the General Land Office, by transitman Hugh B. Crawford. This prospecting work fitted well the classification adopted for Public Works projects in general: it could not be done on any considerable scale under the Survey's usual appropriations; it gave employment to unemployed labor; and it may be expected ultimately to repay the Government in royalties more than the cost of the exploration. COMMERCIAL PROSPECTING METHODS Commercial methods of prospecting for phosphate in Florida have been briefly described by Mansfield.1 In the hard-rock field, where the floor of the phosphate deposit is extremely irregular, it is customary to drill as

Jan 1, 1937

By J. P. Hirth, C. S. Hartley

A simple graphical technique is presented for rapidly determining the ratio of resolved shear stress on slip systems in single crystals to the applied stress (Schmid factor) for various simple states of stress. Master plots are presented which, when used in conjunction with an appropriate stereo-graphic projection, allow one to determine the Schmid factor for all slip systems in a crystal of given orientation. It is shown that one such plot suffices for simple tension or compression, flex-ural bending, and biaxial compression, while a combination of two different plots must be used for torsion and simple shear. STUDIES of the deformation behavior of single crystals are most valuable when the applied stresses are resolved onto the various slip systems of the crystal. A careful study of the available slip systems and proper selection of the state of stress used and the specimen orientation can then yield quantitative information about the probability of specific dislocation reactions, the strength of barriers to plastic flow, and the mechanisms of yielding and flow in general. It is the purpose of this work to analyze some common states of stress used in deformation studies and to present a simplified way of determining for these cases the ratio of the resolved shear stress on the slip systems to the applied stress (Schmid factor). I) CALCULATIONS We first define two orthogonal coordinate systems: one based on the specimen geometry (a right circular cylinder of radius, R, is considered here) and one based on the particular slip system of interest. The unit vectors and angles specifying the two coordinate systems and the relationship between them are listed in Table I. The relationships among the various angles and unit vectors are shown on a stereographic projection in Fig. 1. The transformation matrix between the (XI X2 X3) and (x'1 x'2 x'3) system is x1 x2 x3 X'1 a11 al2 a13 x'2 a21 a22 a23 x'9 a31 a32 a33 where in this case the direction cosines aij are given by a11 a12 a13 aij = a21 a22 a23 a31 a32 a33 sin 0 cos F cos 0 sin F cos 9 = -cos 0 cos F sin 0 sin F sin 6 [1] 0 -sin F cos (p In terms of Eq. [I.], the stresses sij, referred to the slip system, are determined from oij, referred to the specimen axes, by1,2

Jan 1, 1965

By W. S. Gatley, F. C. Appl

This paper presents a combined analytical and experimental study of chisel penetration vs time during chisel impact on rock, a problem of fundamental importance in improving the performance of roller-cone bits or percussion drilling toots. For a given force-time relationship between chisel and rock, the problem of determining the penetration (displacement) vs time of the chisel is formidable. This is so because the rock is a nonlinear system with distributed mass and distributed damping (friction, dissipation of energy due to rupture, etc.). Since the literature does not contain adaptable solutions, the rock behavior to impact was simulated approximately by an "equivalent" lumped system, that is, an "equivalent" mass, spring, dashpot system. With this assumption, an analytical solution was found for chisel penetration vs time due to a sinusoidal load between chisel and rock. From this solution were found curves, in terms of dimension-less variables, for the maximum depth of penetration vs the frequency of the sinusoidal loading and for the energy transfer vs frequency. The results of this analysis were used to predict the penetration rate of rotary rock bits us rotary speed. The curve indicated that an optimum speed exists. To verify this analysis, an experimental apparatus was constructed and used to apply a sinusoidal pulse to a chisel penetrating a rock specimen under atmospheric conditions. Strain gauges were mounted on the chisel shank and a velocity transducer was mounted between the chisel and the rock surface. The velocity was integrated electrically and picked up simultaneously with the strain gauge signal on an oscilloscope. Permanent records were made photographically to provide simultaneous records of force us time and penetration us time. In comparing the experimental results for limestone and dolomite with the theoretical results, good agreement was found in the frequency range of the experiments. Unfortunately, the inertia effect (peak penetration) indicated by the theory occurs at a frequency much higher than could be obtained experimentally with the apparatus constructed. A "rate-of-loading" effect is indicated theoretically, but has not yet been verified experimentally. INTRODUCTION The process of drilling with percussion tools or rotary rock bits is basically related to the transient response of rock to surface impact. Each time a bit tooth contacts the rock, high stresses are developed which result in penetration and rock removal. As the tooth moves on, stresses are relieved and a new cycle begins as the next tooth contacts the rock. Thus the drilling process, which consists of an endless succession of these cycles, can be studied in terms of a single cycle. It is apparent, therefore, that the study of single-chisel impact on rock is fundamentally important in improving the performance of roller-cone and percussive-type drills. Previous studies in this area have been conducted by Simon1 and Hartman2 by means of drop tests. In these tests a chisel was attached to a weight and allowed to fall, due to the force of gravity, so that the chisel was driven into a rock specimen upon impact. Strain gauges were attached to the chisel shank and the resulting force-vs-time curves were recorded photographically from an oscilloscope screen. The depth of penetration and crater dimensions were also measured. These tests have provided much valuable information but, as mentioned by the investigators, have not provided complete information on the effect of "rate of loading'! This is partly due to the fact that the chisel motion during drop tests is not a controlled motion which can be varied in form and frequency. Therefore, it seemed that additional information could be obtained by studying chisel impact under conditions where both the motion and the frequency of loading could be controlled. This paper presents a combined analytical and exper-

By William J. Millard

The Island of Trinidad has much the same geological history as the continent of South America. There are present in this area Cretaceous, Tertiary and Quaternary rocks, which were deposited in a basin covering eastern Venezuela and Trinidad, very much as rocks of the same age were deposited in the Maracaibo Basin in western Venezuela. Along the north coast there are metamorphosed and semimetamorphosed Cretaceous rocks which are found as semicrystalline limestone, schists and quartzites, etc. Both the Cretaceous and Tertiary rocks are petroliferous and are responsible for the production of oil in Trinidad and eastern Venezuela. The geological column in the oil-bearing region of Trinidad is shown below.

Jan 1, 1931

By W. L. Remick

THE hydrotator coal-cleaning process was developed as an economic necessity to meet the ever-increasing demand for an inexpensive method of cleaning coal down to the sizes ordinarily referred to as "dust." As the most urgent demand seemed to be in the anthracite field, all experimental work has been conducted in that territory during the past 2 years, with the exception of a few months during the strike of 1925-26, when some experiments were performed in the Alabama bituminous fields. The first commercial plant was constructed at the Middle Creek Colliery of the Philadelphia & Reading Coal & Iron Co., Pottsville, Pa. This plant is now operating. APPLICATION The field of application of the process is: 1. Cleaning anthracite fines, ordinarily described as "slush" or "silt." Slush contains all sizes from %2 in. down to and including "dust." (Anthracite passing a 32-in. mesh is also referred to as No. 2 Barley and No. 4 Buckwheat.) 2. Cleaning sizes too fine for recovery by other methods. 3. Removal of coal from sand circulated in the Chance sand-flotation process. 4. Cleaning of bituminous sizes. from 3/8 in. down to "dust. 5. As equipment for the performance of the froth flotation process. 6. Other separating, extraction and _washing. processes which may be considered outside the realm of coal cleaning. PRINCIPLE OF OPERATION Fig. 1 shows the method of classification practised under the Hydrotator patent:1 In coal cleaning the machines are operated as "hindered settling" classifiers, the flow of solids and liquids being so controlled that the units may be combined in series.

Jan 1, 1927

By Russell W. Dayton

THE metallurgical polarization microscope has been utilized in several researches in the last few years, thus attaining a fair degree of prominence, but little has been written in a manner suitable to a metallurgist concerning the theory of this instrument. In this investigation the theory was carefully studied, and the results are presented here in a detailed manner, yet as simply as possible. The theory - is discussed with particular reference to the three chief functions of the instrument: (1) determination of anisotropy; (2) effect of strain; and (3) identification of inclusions. Each of these is investigated experimentally, with especial attention to the mechanism of producing any effect. Where possible, the discussion is supplemented by photomicrographs. The instrument used had numerous defects as a polarization microscope; these and their remedies are discussed. In the microscopic study of transparent mineral sections (chalcography) the use of polarized light has aided tremendously in the identification of a mineral. The determination of strain in transparent substances (photoelasticity) by the use of polarized light has lately become a commercial process, used in testing finished glass articles. The success of the use of polarized light with opaque materials has not been so great. The magnitude of the effects obtained is much less than that of the corresponding effects with transparent materials, and the mechanical difficulties are much greater. Königsberger, (1)‡ in 1909, was the first to apply polarized light to the microscopic study of

Jan 1, 1935

Gentlemen.-It is pleasant to be able to report that the year just closed has been a prosperous and successful one for the Institute. As is shown by the reports of the Treasurer and the Finance Committee, the business affairs of this organization are in excellent condition. With property valued at more than three-quarters of a million dollars, and with considerable sums in various funds and endowments, it is possible to spend on each member of whatever class $22.65 each year, more than the maxi- mum amount of dues received from any one, and substantially twice the average amount, $10.94, received from all. To do this has required close management and a strict regard for our limitations. In 1926, when the Budget was made up, the estimated expenditures for the work which it was felt the Institute must do exceeded the estimated receipts by some $14,000. At the close of the year, despite a number of unexpected decreases in receipts, it had proved possible to accomplish substantially all the work laid out and close the books with the usual transfer of initiation fees to the General Reserve, and still only reduce the cash balance $2,074.54. This was made possible by the hearty and loyal cooperation of the whole staff of employees and the extremely large amount of gratuitous service rendered by the officers, the members of the Divisions and technical Committees, and the membership generally. Even so it was impossible, because of limitations of funds, to undertake many things it is highly desirable for the Institute to do, and it was necessary to refuse the publication of important papers and committee studies, because of the lack of funds. PUBLICATIONS In an analysis of the income and expenses of the Institute published in the February issue of our Journal, MINING AND METALLURGY, it was pointed out that the largest item of expenditure is, as it should -be, for publications. Printing, binding, and distributing the various technical papers sent to the members cost in 1926 more than all the money received from dues, including the portion allocated as subscription to the magazine. Within the. year, the following volumes were printed and, with the exception of the second volume of TRANSACTIONS, which was mailed in January, were distributed : TRANSACTIONS, Volume 73, 1241 pages, covering papers on non-ferrous metallurgy, milling and concentration, non-metallic minerals, iron and steel, and the Institute of Metals Division papers read at the

Jan 1, 1928

By W. E. Keck

THERE is a considerable tonnage of iron ore in the Menominee Range Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a rela-tively large quantity of finished concentrate would be obtained (deleteri-ous sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal min-erals in a nearly puree state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,000'. Of this quantity and value, Michigan produced approxi-mately 19 per cent4. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1937

By W. E. Keck, Paul Jasberg

THERE is a considerable tonnage of iron ore in the Menominee Range of Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a relatively large quantity of finished concentrate would be obtained (deleterious sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beiieficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal minerals in a nearly pure state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,0001. Of this quantity and value, Michigan produced approximately 19 per cent4. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1937