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Illinois State Geological Survey, 305 Ceramics bldg, University of Illinois, Urbana, Ill M M Leighton, Chief A catalogue of the publications on the geology and mines of Illinois has recently been issued and will be sent upon request This index is a complete reference on the coal, coal fields and geology of the state and lists (with prices) the great number of Bulletins, Reports of Investigations, Press Bulletins, Monographs and the Educational Series of the state Geological Survey as well as publications of other agencies pertaining to the same subjects Of the several series offered by the state Geological Survey, probably the Bulletins are of most general interest A number of those available deal with the geology and geography or mineral

Jan 1, 1933

By I. R. Kramer

In his technical note entitled "Specimen Temperature During Electropolishing of Aluminum Crystals" Dr. Nakada 1 reported that the temperature of his aluminum specimen increased 65°C when it was polished electrolytically; he therefore concluded that the temperature of the specimens used in our work (Nakada's Refs. 4 and 5) similarly increased by this amount. From this he further concluded that the change in plastic-flow characteristics associated with the removal of the surface by electropolishing during deformation were due solely to a temperature effect. We believe that these conclusions are not justified. It is, of course, realized that the amount of the temperature increase is associated with the total heat transfer of the entire system, including the efficiency of the stirring action, heat flow through the grip on the specimen, and so forth. Of great importance is the type of electrolyte used for polishing. For example, in Dr. Nakada's experiment a methanol-perchloric acid solution was used. This solution has a relatively low conductivity and for the current densities of 0.3 amp per sq cm the electrical input appears to be 30 to 40 w. In our research a methanol-nitric acid solution was employed and for the size of specimen employed by Dr. Nakada the power never exceeded 7 w. There are major differences in his test apparatus which also appear to affect the temperature rise. In our case a steel specimen holder was used in order to provide a good heat sink and conduction path. The cathode was a coiled aluminum tube through which a coolant was passed to provide additional cooling capacity near the specimen. The stirrer was placed in a position to obtain maximum cooling efficiency. On the other hand Dr. Nakada used a teflon grip to support the specimen at one end only and a flat copper cathode, thus providing a much less efficient heat sink as compared with the metal grips used in our studies. The relationship between current density and the temperature increase for two sizes of aluminum crystals tested in our tensile apparatus is shown in Fig. 1. The temperature measurements were determined from a thermocouple spot-welded to the surface of the specimen. The thermocouple was protected from the acid by means of a thin film of stop-off lacquer which covered just the outer surface of the thermocouple junction. Whereas Dr. Nakada reported a time delay of 8 min to obtain thermal equilibrium, our temperature change occurred in less than 15 sec. This emphasizes the importance of the heat transfer in the entire system. However, readings were taken over a period in excess of 5 min to assure thermal equilibrium. The data given in Fig. 1 were also confirmed by determining the thermal expansion of the specimen in a sensitive creep apparatus. As may be seen, for the smaller specimen the increase in temperature is 8°C for a current density of 1.5 amp per sq in. The majority of our data on the effects of surface removal on the plastic behavior of aluminum were obtained at current-density values at or below this value. Above 1.5 amp per sq in. the temperature rise is uncertain; for under certain conditions, especially in the vicinity of 2 amp per sq in., the anode can become polarized and the current flow is erratic. This condition is easily recognized because wide fluctuations in the creep and stress-strain data make it virtually impossible to obtain reliable results, a condition which was always avoided in our work. The temperature increase for the larger specimen is less than that of the smaller specimens below a current density of 1.5 amp per sq in. At a current density of 2 amp per sq in. the temperature increased 13°C. The above temperature data are in accord with observations made during creep experiments. Using a transducer capable of detecting strain in the order of 10 -6, temperature changes in excess of 8°C were not detected when the current density was increased to as high a value as 1.5 amp per sq in. Finally we wish to point out that our experimental data cannot be explained solely in terms of a heat effect. For example in Fig. 1 of Ref. 2, the change in slope of Stage II as a function of the rate of re-

Jan 1, 1965

By W. A. Gibson, Zay Jeffries

It has been known for a number of years that certain aluminum alloys could be hardened by quenching from a temperature of about 500' C. Immediately after quenching the total increase in hardness is not marked, but the hardness increases gradually so that after about 4 days, it has reached a maximum. The actual increase in hardness probably continues for weeks or even months, but in order to detect the differences after 4 days, it is necessary to make tests at rather long intervals. So far as is known to the authors, Alfred Wilm was the first to discover these properties in aluminum alloys.' The aluminum-copper alloys are amenable to this treatment and the addition of magnesium makes the heat-treatment effect more pronounced. Until recently heat treatment of aluminum alloys has been confined to the worked alloys in the form of sheet or extruded products. The alloy that has been most used in this connection is known commercially as duralumin and has about the following composition: copper not exceeding, 6 per cent.; magnesium not exceeding, 2 per cent.; manganese not exceeding, 1 per cent.; commercial aluminum,2 balance. A typically good alloy in this range consists of: copper, 4 per cent.; magnesium, 0.5 per cent.; manganese, 1 per cent.; commercial aluminum, balance. This alloy can be rolled into sheets or extruded; and in this condition it can be heated in the ordinary furnace atmosphere to a temperature near 500° C. and quenched in water. After about 4 days it will have the following physical properties: tensile strength 55,000 to 60,000 1b. per sq. in. (3866 to 4218 kg. per sq. cm.); elongation in 2 in., 15 to 20 per cent. No harmful effects of the furnace gases or even the air, if the heating is effected in an electric furnace in an air atmospherc.

Jan 1, 1921

By E. R. Smith

ANALYSIS of the requirements for gun perforation equipment suitable for penetrating casing and cement showed that these points would be involved: (1) Powder charges electrically detonated under high fluid lieads and at remote distances. (2) Selective firing of sliots in sequence. (3) Sufficient velocity for the bullet to penetrate at least two strings of seamless casing and all cement beyond the strings. (4) Heat-treatment of steels to withstand great pressures and penetration. (5) Esclusiorl of fluid under extremely high hydrostatic pressure. (6) Stranded steel wire line acting as weight - suspending and current - carrying medium. (7) Firing controls operated above the surface. (8) Determining gun depth and suspended weight by means of the wire line. (9) Portability for field use.

Jan 1, 1936

By R. W. Raymond

FOUR portraits have recently been hung in the rooms of the Institute, in recognition of four illustrious men with whom we, as mining engineers and metallurgists, may claim fellowship. LUTHER. Martin Luther is often spoken of as a miner's son; but it is less generally known that John Luther, his father, was, in a small way, a metallurgist as well as a miner, and that Martin Luther himself, in his youth, worked in a forge or bloomary established by his father at Mansfeld, Saxony. Since this is the only manual occupation on his part of which we have any record, it is fair to assume that the great scholar and reformer derived from his work in this department the practical familiarity with the conditions of human labor so abundantly evinced in the homely illustrations which accompany even his serious arguments, and in the witty apothegms of his famous "table-talk." At the same time, I must confess that 1 have not been able to find in any of the works of Luther distinct allusions to mining or metallurgy. KÖRNER. Theodor Körner, a student at the Mining Academy of Freiberg, Saxony, threw himself into the German War of Freedom in the first decade of the 19th Century. He was a poet of no mean rank ; and his " Song of the Sword " is one of the great lyrics of literature. This poem was written but a few days before he died in battle. In many respects, Körner may be compared with our American hero Theodore Winthrop, who similarly met a glorious fate, and left behind him prophetic indications of genius, of which his premature death prevented the complete fulfillment. I am informed by a member of the Institute that Körner's admirable collection of minerals is still preserved at Dresden.

Nov 1, 1908

By R. R. Hoffman

The name L'brush,l as applied to the parts to be briefly considered in this paper, is not clearly descriptive of the design and function of those parts when the usual definition of the word is applied. In a general way, the brushes to be considered here are the parts employed on certain types of electrical equipment to facilitate the transfer of electrical current between a rotating or moving element and a stationary element. These machines are generally motors and generators of both the slip-ring and commutator types, rotary converters, battery charges, etc. Parts that serve a similar purpose on relatively slow or intermittently moving devices such as rheostats, switches, controllers, etc., are generally referred to as contacts. A few special applications involve the use of current-carrying washers, rollers, bushings, etc. As may be inferred, therefore, the design of these brushes and allied parts is dictated by both electrical and mechanical considerations. In most cases these factors are closely interrelated, and unfortunately many of them are not subject to exact scientific or mathematical analysis. Special Advantages Since brushes operating on direct-current machines must carry the load current, resist destructive action from voltage induced in imperfectly compensated armature coils, and in addition act as a bearing material, maintaining intimate contact with the commutator at peripheral speed, which may be as high as 70 miles per hour it is difficult to obtain in one brush the ideal properties necessary for perfect functioning under all operating conditions. The engineer-designer, therefore, when selecting a brush for a specific application, must choose a grade that possesses the characteristics most adequate to meet the conditions involved. In many cases a characteristic that makes a specific grade of brush the ideal selection for one type of machine may be of secondary importance to some other property when the brush is applied on another machine. Frequently different grades of brushes must be applied to the same type of machines when they operate under different or unusual atmospheric conditions. Completely satisfactory brush operation depends on freedom from appreciable sparking, minimum electrical and mechanical losses, negligible commutator or slip-ring wear, uniform film over the commutator or slip ring, quiet operation and good brush life. The ability to produce special structures, and to combine in widely varying proportions materials that are incompatible, through conventional melting and alloying procedures has been the basic contribution of powder metallurgy to the solution of problems involving brushes and allied parts. This is especially true where current-carrying capacity is a major factor, owing to the limitations of all carbon or all graphite brushes in that respect. Metal-graphite Brushes With very few exceptions, friction between moving elements. across which

Jan 1, 1945

By E. C. W. Perryman

On electropolishing, high-purity Cu-Sn and Cu-Sn-P alloys with more than 5 to 9 pct Sn were found to contain many grain boundaries with a ridge-and-furrow profile. The effect was not eliminated by solution treatment and was present at the new boundaries in recrystallized material. It could be produced by diffusing tin into the 3 pct Sn alloy and it is concluded that the effect is due to enrichment of certain boundaries in tin, or possibly in an impurity present in the tin, in solid solution. IN the hot working of tin bronzes, especially those with moderately high tin contents, considerable difficulty is frequently encountered from intercrystal-line weakness, which results in cracking at the edges in sheet on strip rolling and in the unsupported regions of the rod in rod rolling.' These difficulties are not at all pronounced with up to 3 pct Sn, but at 5 pct Sn impose serious limitations and at higher tin contents, especially if the phosphorus content is also high, they may become very severe. In some work carried out at the laboratories of The British Non-Ferrous Metals Research Association it was found that a notable lack of ductility in tension at elevated temperatures, associated with intercrystal-line failure, was characteristic of tin bronzes even of relatively high purity. That the intercrystalline fracture is not due to a brittle or molten impurity phase at the grain boundaries was shown by the fact that the temperature at which intercrystalline fracture first occurred decreased with decrease of rate of straining. Tensile tests on some commercial tin bronzes, reported by Goetzel,² show a similar fall in ductility with increasing temperature. As no visual evidence had been obtained showing that the grain boundaries of the tin bronzes were different from those in copper, a more detailed microscopical examination was carried out, and the results of this are given in the present report. Several workers"' have observed that electrolytic polishing is a powerful tool for detecting small amounts of a second phase and in particular for detecting high solute concentrations, "equilibrium segregation," at grain boundaries. Since it had been found that the suggested solutions for electropolishing bronze and the standard solutions for brass and copper did not give satisfactory results it was first necessary to find a suitable electropolishing solution.' Experimental Procedure Materials Used: The cast and wrought materials used for this work were the same as those used for the mechanical tests referred to above. They comprised 3, 6, and 9 pct Sn alloys without phosphorus and the same three basic alloys with 0.03 and 0.4 pct P. A 5 pct Sn alloy without phosphorus, of similar purity, was also examined. The basis materials were Chempur tin, high purity 15 pct phosphor-copper and cathode copper, and spectrographic analyses are given in Table I. Treatment: The cathode copper was first melted under charcoal, degassed by plunging marble chips beneath the surface, and cast through a coal gas flame into sand molds to produce a number of small ingots which after machining were of a suitable size for subsequent vacuum melting. Chill cast bars of the alloys, approximately 1¼ in. in diameter, were then made by melting and casting in vacuo, the tern-

Jan 1, 1954

By C. W. Chen

MARTENSITE transformations in ß Cu-Al alloys have been studied by Greninger1 and other investigators. According to Greninger, the parent phase ß1 an ordered body-centered-cubic structure obtained from ß phase by suppressing the eutectoid decomposition, transforms into an ordered hexagonal-close-packed phase in composition containing 12.9 to 14.7 pct Al. The M, temperature decreases with increasing aluminum content; for the alloy containing 14.5 pct Al, for example, the ß1??' transformation occurs below room temperature. More recently, Kurjumow2 studied the transformation in ß Cu-Al alloys with the addition of nickel. His report stimulated new interest in the subject due to the observation of completely reversible transformation without hysteresis in the transformation temperature ranging from 10° to —10°C. In the present paper some characteristics are described of the transformation of Cu-Al-Ni alloys that were partly studied by Kurjumow. Experimental Procedure High purity copper (99.999 pct) and aluminum (99.99 pct) and electrolytic nickel were used in the preparation, by the Bridgman technique, of single crystal specimens which contained aluminum and nickel of 14.5 and 0.5 to 3.0 pct, respectively. Polished surfaces were prepared mechanically. Specimens were then chemically etched to remove distorted material, homogenized at 1000°C for several hours, and quenched drastically to room temperature in a 10 pct NaOH bath to produce the parent phase ß1. The transformation was studied under a microscope and, in some cases, recorded by means of motion pictures. A device similar to that designed by Greninger and Mooradian3 was used to cool and reheat the specimens. Results and Discussion When the specimens were cooled below room temperature, the ß1 to ?' transformation began at 10°C with the appearance of ?' crystals In relief, Fig. la. As the specimen temperature dropped further, the transformation continued, either by the growth of the ?' crystals, with the ß1 — ?' interface moving into the ß1 phase, Fig. 1c and 1d, or by the formation of new ?' crystals, Fig. 1b. As a consequence of the former process, banded structure is observed as a common feature of the low temperature phase. According to the theory of the formation of martensite by Wechsler, Lieberman, and Read,' the bands of ?' phase are probably twin-related, as is the case in the diffusionless phase change of In-T1 alloys,5 but this was not revealed by X-ray tech- niques. New ?' crystals, in needle form, often emerged suddenly across the ?' bands during the transformation. These acicular crystals then grew, both in length and in width, see Fig. 2a through 2d. The transformation on cooling is completed at about -35°C. Upon heating, the reverse transformation started at —10° C, in a manner nearly opposite to the transformation on cooling, and completed at 35°C. There was no noticeable change in the transformation temperature when the nickel content was varied within the limits previously mentioned. Through control of the specimen temperature, the transformation can be started, stopped, or reversed at will. This phenomenon has frequently been observed in the martensite transformation of many nonferrous alloy systems. Other systems are Au-Cd6 and In-Tl.5 ow-- ever, in the latter systems, the transformation is accomplished by single interface motion if the specimen composition is homogeneous and the temperature gradient in the specimen is uniform and sharp, whereas in the Cu-Al-Ni specimens, only multiple interface transformation is observed. The speed of the interface motion appears to be a functionof the rate of temperature change and the temperature gradient across the specimen length. In one case, in which the temperature increased at the rate of 10°C per min and there was no temperature gradient along the specimen axis, the speed of the disappearance of a ?' plate was determined, by the study of the motion pictures made, to be 26 µ per sec. Quench markings were observed on the polished surfaces of specimens. The markings were grouped into one or more sets of different orientations, and were parallel in each set. The ?' plates formed in subsequent transformation were parallel to the markings, indicating that the ?' plates and the quench markings had the same geometric relation-ship to the ß1 matrix. The quench markings on two intersecting surfaces of a specimen were therefore used in the determination of the habit plane of transformation, by the trace method suggested by Barrett.' Results obtained from five sets of markings in three specimens indicate that the habit plane is an irrational plane about 2" from one of the {221} planes. This is very close to the habit plane (3" from 221 planes) of ß Cu-Al alloys containing more than 13.0 pct Al.1 The martensite transformation of Cu-Al-Ni alloys is reproducible. No sluggishness was found between consecutive transformation cycles, although a slight difference in the distribution pattern of the ?' plates was observed, compare Figs. Id and 2d. The transformation can be strain-induced. This characteristic has been tested by a simple method. When a specimen was elastically strained slowly in a vise, ?' plates were gradually produced in the same fashion as during transformation on cooling, This test was done at room temperature, and thus above the M,

Jan 1, 1958

By H. B. Menardi

THE history, geology, ore deposits and current mining operations of the Huitzuco district have been described by C. W. Vaupell1 and the current mill operations by David Segura.2 This paper completes the story of Huitzuco with a description of the reduction of the flotation concentrates. The predominant ore mineral in the Huitzuco deposit is livingstonite, a rare, mercury-antimony sulphide (HgS.2Sb2S3). Other associated minerals include cinnabar, stibnite and elemental sulphur. The gangue is largely limestone and gypsum. Former operators mined a selected grade of ore, from which the mercury was recovered by an expensive, inefficient operation. A consid-erable tonnage of rejects and fills, carrying mercury and antimony, was left in the mine. In order to recover both mercury and antimony from these fills and also from newly developed ore, a combination method has been developed, by means of which the livingstonite is concentrated by flotation and the flotation concentrates subsequently reduced to metallic mercury and antimony. An essential part of the flotation treatment, as developed by Segura, is the use of copper sulphate as an activating agent. A typical analysis of concentrates now being produced at the property is as follows: Hg, 7.73 per cent; Sb, 26.40; Fe, 1.20; S, 29.68; CaO, 11.50; MgO, 7.25; Si02, 1.63; A1203, 0.65.

Jan 1, 1939

By S. F. Shaw

IT IS generally recognized that the natural gas absorbed in petroleum plays the leading r6le in moving the oil through the sands to the well and supplies the energy that delivers the oil to the surface when the wells are flowing. It is the purpose of this paper to note the amount of oil that could be lifted by this gas if 100 per cent. efficiency were obtained and the efficiencies actually obtained in the use of this gas. An article in MINING AND METALLURGY,' stated that in a Wyoming field, with a pressure of 300 lb. per sq. in., there would be absorbed 65 cu. ft. of gas per barrel, or 1.55 cu. ft. per gal. of oil. The writer does not know if data have been obtained, by experiment, for pressures beyond those indicated in this article, therefore, for the purpose of illustration, he has projected this curve to obtain figures for pressures greater than 300 lb., although probably experiment will show that the extended line is not quite correct.

Jan 1, 1926

By H. O. Hoffman, C. D. Demond

There are two methods of determining the fusibility or refractoriness of fire-clays, the theoretical and the experimental. In the former, conclusions are drawn from the chemical composition; in the latter, from the changes which the clay undergoes when subjeoted to intense heat. It is well to use both methods, beginning with the actual heat-test and explaining the results obtained from this by the help of the chemical analysis. In discussing the subject, however, it is better to reverse this order. I. The Theoretical Method.* Leaving out the hygroscopic and combined waters and any organic matter, as not directly affecting the fire-resisting property, the refractory constituents of fire-clay are alumina and silica, and the fluxing constituents magnesia, lime, soda, potash and ferric oxide. According to Bischof,† alumina is the least fusible component, and silica follows close upon it. If, however, a mixture of the two be heated, it will be found that its melting-point is much lower than that of alumina, as a silicate will then have been formed. The way in which silica affects the refractoriness of alumina has been strikingly presented by Seger 1 in a diagram reproduced in Fig. 1. The abscissæ represent the melting-points of Seger cones Nos. 26 to 36 (see p. 55); the ordinates, the relative amounts of alumina and

Jan 1, 1895

By Thomas A. Steven

Most mineralized areas in the central San Juan Mountains, Colorado, are associated with the youngest subsidence structures in a large volcanic cauldron complex that formed concurrently with eruption of the surrounding ash-flow field. Two local types have been recognized: (1) fissure-vein deposits along faults characterized by relatively late movement, and (2) hydrothermally altered and mineralized areas associated with postsubsidence Fisher Quartz Latite centers. The first type has provided most production in the past; the potential of the second type has yet to be adequately tested.

Jan 1, 1968

By Ellsworth Daggett

THE system of pitwork used with the Cornish pumping engine, and which, for want of a better name, we may call the Cornish system of pitwork, consists essentially of a series of plunger-pumps, situated one below the other, in a shaft or incline, the plungers being operated by a rod called the pitman or pump-rod, which must, therefore, extend from the motor at the surface to the lowest pump. The subject will be best understood by reference to Fig. 1, in which k may be taken as typical of the ordinary plunger-pump, in which S is the suction pipe, u, the lower valve situated in the H piece T; v, the upper valve situated in the valve-box O; I, the mounting-pipe or column through which the water is carried to the surface; L, the plunger-barrel, and P, the plunger working through the stuffing-box, and actuated by the branch rod r, which is attached to the main pump-rod, R. The action of the pump is as follows : On the ascent of the plunger, acting now by suction, the water flows from the reservoir through the valve u, into the barrel, L. On the descent of the plunger, the water is forced up through the valve, v, which acts merely as a check valve, into the pipe, I, through which it is, at each successive down-stroke of the plunger, forced upward until it reaches the next reservoir, from which it is taken by another similar pump, and so on until it reaches the surface or drain-tunnel. The pump is obviously only single-acting, i. e., it acts only during one-half of its entire stroke. The weight of water raised during the up-stroke of the plunger is equal to the weight of a column of water whose base is the area of the plunger and whose height is the mean distance between the plunger-face and the surface of water in the lower reservoir, a distance not usually exceeding 12 or 15 feet, and which obviously cannot under the most favorable circumstances, exceed 25 or 30 feet. The water forced up during the down-stroke is equal to the weight of a column of water whose base equals the area of the plunger and whose height equals the length of the mounting column above the mean position of the plunger-face, say from 150 to 300 feet. Almost all of the useful work, therefore, is done on the de-

Jan 1, 1879

By Strathmore R. B. Cooke, Emert W. Lindroos, Norman F. Schulz

DURING the course of an investigation of the effects of various starch products on hematite and quartz in regard to their separation by' flotation, it was found that whereas most starches flocculated suspensions of hematite in water, they did not flocculate similar suspensions of quartz. However, a derivative of whole corn starch containing approximately one tenth aminoethyl group (--CH2CH2NH2) per glucose unit proved to be an exception. This aminoethyl starch was a very good flocculant for both hematite and quartz, and also possessed the property of depressing both minerals in cationic flotation tests. In view of the widespread use of starch as a flocculating agent of solids in tailing water, pulps, and for coal slimes, ore and various other purposes in sulphide and nonsulphide flotation, attention is called to the effective surface activity of aminoethyl starch in flocculating suspensions of the two minerals investigated. Test Materials The starch products employed included Globe Pearl starch No. 144 and fresh aminoethyl starch, both supplied by the Corn Products Refining Co. Dr. A. L. Elder[4] has kindly furnished a description The minerals used in the various tests are listed in Table I. Their specific surfaces were determined by the air permeability method, which gave results reproducible to within plus or minus 3 pct. Surface areas obtained by krypton adsorption were greater than the air permeability values by a factor of 2.0 for quartz and 62.4 for hematite. Starch Adsorption on Mineral Surfaces Starch adsorption data were obtained by agitating for 1 hr measured volumes of neutral starch solutions of known concentrations with weighed quantities of finely divided mineral of measured specific surface. The mineral then was separated from the pulp liquor by centrifugation and the residual starch content determined by chemical analysis. The analytical procedure consisted of oxidizing the starch with an excess of dichromate in acid medium at elevated temperature and titrating the excess dichromate by the ferrous ammonium sulphate-potassium permanganate method. Analytical results were reproducible to within less than 1 pct. Adsorption data obtained in unbuffered solutions near the neutral point are plotted in Fig. 1. The adsorption on either mineral was far greater for the aminoethyl starch than for the Pearl starch. Flocculation The degree of flocculation was determined for a given pulp by measuring the time required for the supernatant liquid to reach a certain degree of clarity. This was accomplished by passing a standard light beam through the pulp, contained in a glass settling tube, and measuring the time required after agitation ceased for the intensity of the transmitted beam to reach a predetermined value. Starch reagent was added to each pulp in small uniform increments, and the settling time was determined after each such addition. Increase in pulp liquor volume due to the added starch reagent was ignored in these tests. Pulps were maintained at or near neutrality.

Jan 1, 1952

By William P. Blake

At the August meeting of the Geological Society of America, I presented a paper on the occurrence of alunogen and bauxite upon the Upper Gila river, about 40 miles north from Silver City, New Mexico, together with observations upon the geology of that region." Inasmuch as the subject is specially interesting to metallurgists and mining engineers, and as our Transactions contain recent important papers, by Dr. Hayes, M. Laur, of France and others, upon bauxite, I venture to offer to the Institute, in more condensed form, an account of the deposits described in the paper above referred to. The only other published account of the alunogen locality which I have been able to find is a prospectus-pamphlet, issued in a small

Jan 1, 1895

Dr. James Douglas, who is memorialized on another page of this Bulletin, who held a place in the affections and regard of Institute members second to that of no other living roan, left in his will the sum of $100,000 for the maintenance of the Library of the American Institute of Mining Engineers. This is in addition to the $100,000 which Dr. Douglas gave during his lifetime. We believe that it is Dr. Douglas' wish that the library, the great means by which the benefits of Institute membership may be extended to those distant from headquarters, should be maintained by the Institute at the highest possible level of efficiency and serviceability.

Jan 9, 1918

By Ellsworth Daggett

Jan 1, 1879

By B. C. Morrison

Because of U.S. Forest Service regulations and the consequent cost of leaving several diamond drill holes open at the same time, it was necessary to develop an electrical method that could be used in one hole at a time to extend known mineralization. This was achieved by balancing the surface current electrodes so that the two potential electrodes in the hole being surveyed were in the same equipotential surface. This condition eliminated stratigraphic response but enhanced any asymmetry due to ore between the hole and either current electrode. This method was successfully used in mineralized holes at West Fork, Reynolds County, Mo., to show the direction in which to extend the drilling into areas of better mineralization.

Jan 1, 1972

By Richard P. Gerwels

Minas de Matahambre, a copper mine located 100 miles southwest of Havana, Cuba, has produced 10 million tons of copper ore since it was first opened up in 1913. During the mid-1950's the mine was producing approximately 1000 tpd and had attained a depth of 3600 ft. As shown in Fig. 1, the property contains three shafts: the No. 1 shaft, 2100 ft deep and located 2000 ft south of the No. 2 shaft, provided service to the 2100 level; the vertical 3600-ft No. 2 shaft handled all production to the 3400 level; the No. 3 shaft on the northeasterly fringe of the mining area was in a semi-active status.

Jan 12, 1960

By H. I. NORTON, H. O. Hofman

ZINC smelters in the central western. States have established a very high standard of purity for blende-concentrates, viz., zinc 60, iron less than 3, and lead less than 1 per cent. The very low percentage of iron is made possible by the blende containing less than 0.5 percent of isomorphous iron sulphide and by the sparing occurrence of pyritic material in the large blende-deposits of southwestern Missouri and southeastern Kansas. The blende in these districts occurs in sub-Carboniferous limestone, and is associated with chert, residual clay, calcite, pyrite or rnarcasite and bitumen. The different minerals are coarse and therefore readily separated by mechanical washing from the blende, with the exception of pyrite and marcasite, as blende has a specific gravity of from 3.9 to 4.1, marcasite, from 4.85 to 4.90, and pyrite, from 4.95 to 5.10. The common procedure of dressing the ores is to crush in a breaker, size in a trommel with 0.5-in. holes, pass the over-size through roughing-rolls and then jig the ore, now reduced to 0.5 in. maximum size, in roughing multiple-sieve jigs. The products of these are waste-tailings, sine-discharge coarse concentrates, side-discharge coarse middlings and bottom-discharge fine middlings. The coarse concentrates are sent to the market. The coarse middlings are crushed in middlings-rolls and brought back into the system by feeding into the main trommel. The fine middlings are cleaned upon finishing-jigs. Any pyrite or marcasite present follows the blende and increases the percent-

Mar 1, 1905