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CONTENTS KANSAS-H. S. BRYANT 3 TEXAS, EXCEPT GULF COAST-M. C. CHENEY 14 GULF COAST-L. P. TEAS 21 TEXAS PANHANDLE-W. E. HUBBARD 29 LOUISIANA, ARKANSAS AND MISSISSIPPI L H. K. SHEARER 37 ROCKY MOUNTAINS-R. C. COFFIN 43 CALIFORNIA-V. H. WILHELM 51 MICHIGAN AND THE TRENTON FIELDS OF OHIO AND INDIANA-M. G. GULLEY 65 ILLINOIS, WESTERN KENTUCKY AND WESTERN INDIANA-A. H. BELL . . . 73

Jan 1, 1932

By G. M. Crosby

Seven mines with important production records in the Coeur d'Alene lie adjacent to the Gem stocks —the Frisco (Gem), Hercules, Interstate, Rex (Sixteen to One), Success (Granite), Sunset, and Tamarack. Old records are incomplete, but available data given in Table I show these mines have produced 10.550,721 tons of ore containing more than 50 million oz of silver, more than 1.5 billion lb of lead, and about 1 billion lb of zinc (approximately 1.25 million tons of lead and zinc combined). Average ore grade is 4.8 oz of silver per ton, 7.2 pct Pb, and 4.6 pct Zn. This impressive production represents about 12 pct of the District's yield. At present metal prices, with modern beneficiation, the gross value would be more than $400 million. THE GEM STOCKS The Gem stocks, considered to be outliers of the Idaho batholith of Late Cretaceous age, are located in the northern half of the Mullan quadrangle, and extend from the town of Gem, Idaho, along a strike of N30°E for a distance of approximately five miles. They occur as two major masses of monzonitic rocks commonly referred to as the North stock, which covers an area of 1.1 sq miles, and the South stock, which covers 2.6 sq miles. The areal pattern is roughly club-shaped, the North stock representing the handle and the South stock the head of the club. Two and a half miles west and five miles northeast are two groups of smaller stocks, isolated from the main masses but of the same general rock type. This discussion is limited for the most part to the North and South stocks. At the north end, where the intrusion is about 3200 ft wide, the walls are about parallel and dip very steeply west. At the south end, where the mass is about 7000 ft wide at surface, the walls dip away from each other at moderately steep angles. An aeromagnetic survey' detects and outlines with surprising accuracy the two main stocks. as illustrated on the magnetic contour map (Fig. 2). Of particular interest is the location and shape of the magnetic anomaly representing the South stock. The anomaly is centered over the south end of the outcrop, and a westerly extension joins it with a smaller anomaly over the Dago Peak stocks. The latter anomaly, likewise, is located over the south end of the isolated stocks. This pattern suggests the intrusion has greater extent at depth to the south and west. Though correlation between the Dago Peak stocks and the larger masses is suggested, the controversial aspects of the Dobson Pass fault, which separates the two areas, casts doubt on a correlation. Topographically the monzonite stocks are ignored by the drainage pattern indicating these rocks, and the invaded rocks of the Lower Belt Series react similarly to erosion. The drainage patterns of Nine Mile and Canyon creeks cut indiscriminately across the monzonite-Belt contact, resulting in both valleys and ridges in the southern end of the intrusion. Nine Mile Creek traverses diagonally the entire five-mile length of the stocks. The monzonite rocks of the intrusion are referred to locally as granite, but granite is rare and the rocks comprise a wide variety of types. Their characteristics, described in detail by F. L. Ransome and F. C. Calkins,' are summarized by P. J. Shenon.' The principal rock type is coarse-grained, light gray, porphoritic monzonite containing black crystals of hornblende. Pyroxene, epidote, and titanite

Jan 1, 1960

[NORTH AMERICA UNITED STATES ALABAMA AUBURN Sturm & O'Brien, Consult. Engrs. °Sturm, Rolland G. BESSEMER Granger, W. C. BIRMINGHAM Air Reduction Sales Crockett, John M. Amer. Cast Iron Pipe Co. Carter, Sam F., Jr. Donoho, C. K. Anderson Elec. Corp. Davis, Moss V. J. B. Clow & Sons Neptune, Maurice D. Connors Steel Div. °Sandelin, Robert W. Hayes Aircraft Corp. Ricketts, W. E., Jr. Willhelm, A. Clyde, Jr. McWaine Cast Iron King, O. H. Worthington, B. W. Shook & Fletcher Sup. Co. Gearhart, Thomas A. Southern Res. Inst. Dismukes, Edward B., Wheelahan, Edmund J. Thomas Foys Miller, Ralph M. Union Carbide Metals, Co. Brandler, Edgar A. U. S. Pipe & Fdry. Co. Clay, Donald H. Unaffiliated Berg, H. A. Caldwell, H. A. Gilmer, H. U. Harris, Thomas H. Templeton, J. B.]

Jan 1, 1961

By R. S. Kinasevich, D. D. Crabtree, D. W. Fuerstenau, T. P. Meloy, A. L. Mular

The effect of such variables as feed size, particle shape, cleavage, and hardness on the relative proportion of impact, abrasion, and chipping events in a tumbling mill is demonstrated. The concept of an average event, which is a combination of the three comminution mechanisms, is introduced. It is postulated that the average event in a particular mill determines not only the size distribution but also the energy-size reduction relationship for the comminution process. Fragmentation of particles in tumbling mills appears to result from a combination of impact, abrasion, and chipping grinding.' The relative rates of size reduction attributable to any of the basic grinding mechanisms must depend upon a number of variables, such as feed size, particle shape, hardness, and the number and kind of particles in the mill. The purpose of this paper is to show experimentally how these variables in the properties of materials affect the size distributions obtained by grinding the material's in a laboratory tumbling mill. The resulting size distributions will be intetpreted in terms of a combination of three comminution mechanisms. METHODS AND MATERIALS In this study, minerals of widely differing properties were ground either separately or as mixtures in laboratory mills using rods or balls for grinding media. The materials used include quartz, Tuolomne, limestone (99.8% CaCO3), barite, corundum, galena, pyrite, glass beads, and crushed glass. The mill used was 8 in. in diam. and 9-1/4 in. long. For the ball milling tests, 17.6 kg of steel balls (36: 7/8 in. balls, 178: 1 in. balls, and 44: 1-1/8 to 1-1/4 in. balls) were used. For the rod milling experiments, 17.6 kg of steel rods 9-1/16 in. long (25: 5/8 in., 10: 3/4 in., and 5: 7/8 in. in diam.) were used. In each test, 1 kg of solids were ground wet at 60% solids at 77 rpm. In all cases except where otherwise specified, the feed to the mill was 4 x 8 mesh material. Size distributions of the ground products were determined by a wet-dry sieving procedure with Tyler series sieves. Size distributions of mixed products containing limestone were determined by dissolving the limestone with acid and sizing the residue. EXPERIMENTAL RESULTS AND DISCUSSION If the size distribution of the product from a tumbling mill depends upon the relative proportion of impact and attrition (abrasion and chipping) events, altering the grinding conditions may change these proportions and consequently alter the size distribution of the product. Data to illustrate this point can be taken from Gaudin's classic 1926 paper.2 In one series of experiments, Gaudin ground quartz of different initial sizes for four hours in a laboratory ball mill with 7/8-in. balls. In Fig. 1, his data are reproduced as the cumulative fraction finer than the stated size for the following initial feed sizes: 13.3 x 9.4 mm, 6.7 x 4.7 mm, 2.6 x 1.6 mm, and 0.83 x 0.59 mm. As the feed size was decreased, a dramatic change in the shape of the size distribution curves took place, even though the amount of minus 100-mesh

Jan 1, 1964

By W. C. PAGE

ALL mine ore here must be concentrated before shipment, which involves selective flotation. Three products are made: lead, zinc, and pyrite concentrates. The equipment and practice are so well outlined in the accompanying flow sheet that only a few amplifying remarks are necessary. After crushing at the mine to approximately 4 in., the ore is carried by aerial tram about 4 1/2, mi. to the mill. From 1800 to 2000 metric tons per day, excluding Sundays, is thus transported. At the mill, the buckets are hand-tipped into the bins. After crushing to pass a ¼ -in. square opening, the ore may be stored in reserve crushed-ore bins or ball-mill feed bins as desired. Total bin capacity at the mill is about 4000 metric tons. The concentrator is arranged in three independent grinding sections, each fed from its own storage bin. Grinding operations follow standard practice, with ball mills in single-stage closed circuit with classifiers, the overflow from which is delivered to the lead circuit rougher flotation machines,

Jan 1, 1936

By R. A. Deju, R. B. Bhappu

Further information on the surface characteristics of the silicate minerals was obtained by experimentally correlating the oxygen-silicon ratio of the silicates with their electrokinetic properties. Specifically, the behavior of the minerals in an electric field was investigated using zero point of charge as a parameter. A modified electrophoresis cell was used for the determination of electrophoretic mobilities. It was shown that there is an increase in the zero point of charge with increasing oxygen-silicon ratio in the silicates. Finally, a chemical interpretation was presented to describe the surface phenomena observed in the experiments. In recent years great interest in surface chemistry has produced a number of methods to study the surfaces of minerals and to observe the phenomena occurring at their interfaces. One such method is discussed in this paper. A rather complete review of the surface characteristics of the oxide minerals has been undertaken by parks,' but, a similar study has not been made for the silicate minerals. Two previous papers by the authors2'3 attempted to remedy this situation. In these papers it was demonstrated that the reaction between the silicate mineral particles and acidic water involves mainly an exchange of metal ions for hydrogen ions on the surface of the solid, leading to an increase in pH of the aqueous phase. Also, the degree of reaction was found to depend on the oxygen-silicon ratio of the silicate structure, being least for the quartz and greatest for the olivines. A hypothesis was then set forth explaining that upon the fracturing of a silicate mineral, the oxygen-metal bond (which is almost entirely ionic in character) will break more easily than the stronger oxygen-silicon bond. This results in the exposure of unsatisfied oxygen sites on one hand and active, exchangeable cations on the other. These active sites on the fractured surfaces are then available for reaction with the hydrogen ions in acidified aqueous solution. Thus, an increase in degree of adsorption of hydrogen ions occurs as the oxygen-silicon ratio increases due to the presence of a larger number of active sites on such minerals. A correlation between oxygen-silicon ratio and electrokinetic properties will be further pursued in this paper from both the theoretical and experimental points of view. Efforts will then be made to present a chemical interpretation of surface phenomena observed in the experiments. It is believed that this study may supply pertinent information on the behavior of silicate minerals in froth flotation systems. ELECTROKINETIC STUDIES Equipment: In a previous paper,2 Deju and Bhappu described a simple method for determing the zero point of charge using a potential across a cata-phoresis cell and observing particle movement by means of a Rayoscope* optical system. This setup is simple in design and operation and extremely reliable. With care, reproducible results within 1.5% accuracy may be obtained. A new setup has been developed, based partly on the design by Zeta-Meter Corp.4 and partly on previous cells used at the New Mexico Bureau of Mines. This new, modified cell is shown in Fig. 1. Although

Jan 1, 1967

By AIME AIME

COMPLETION of the Rainbow Bridge across the Niagara River and Gorge this fall marks a new page of achievement in the annals of bridge- building. Symbolic of the amity between two great nations, the new bridge provides an additional gateway across the most peaceful border in the world. Ground was broken for the project May 16. 1940, at a site close to that formally occupied by the Falls View Bridge which was destroyed by a record ice jam in 1938. At this point, about 2000 ft. deep and 1000 ft. downstream from the American Falls, the gorge is about 200 ft. deep and 1000 ft. wide. The great steel arch of the bridge has a span of 950 ft. and rises from its supporting abutments on the American and Canadian sides of the river to the level of the top of the gorge. This is said to be the longest hingeless arch in the world.

Jan 1, 1941

1938 ABERNATHY, G E Feb 6, 1948 Min & Met Apr 1948 1937 ADAMS, ARMY Aug 20, 1949 Min Eng Dec 1949 1946 ADDY, GEORGE E Sept 24, 1950 Min Eng July 1951 1920 ALDERSON, WILTON P Feb 1951 Min Eng Sept 1952 1896 ALDRICH, T H , JR May 24, 1950 Min Eng Aug 1950 1942 ALDRIDGE, LEONARD June 8, 1952Jrn Met Sept 1952 1919 ALLEN, ROLLAND C July 18, 1948 Min &Met Sept 1948 1950 ANDERSON, C P Unknown Min Eng Feb 1951 1937 ANDERSON, JOHN H May 10, 1950 Min Eng Aug 1950 1914 ANDERSON, L DOUGLASS Unknown Min Eng Nov 1951 1948 ANDRAU, E W K Oct 20, 1951 1936 ANDREWS, CHARLES B Apr 19, 1950 Min Eng June 1950 1918 ARMITAGE, PAUL June 28, 1949 Min Eng Oct 1949 1924 ARMSTRONG, PERCY A E Jan 23, 1949 Min Eng May 1949 1906 ARNOLD, CHARLES LE NEVE Aug 7, 1949 Min Eng Oct 1949 1945 ARNOLD, HAROLD S Aug 7, 1950 Min Eng Oct 1950 1936 ASH, JAMES E Dec 17. 1949 Min Eng Apr 1950

Jan 1, 1952

By J. B. Knaebel, M. W. Von Bernewitz

OUTSTANDING FACTORS that have largely induced the current great interest in the reopening of old mines and the search for new deposits are the increased relative value of gold, the certainty of a market for it, and the decreased activity and poor profits in other lines of endeavor. It is easy to understand why a miner out of a job and unable to find any other means of livelihood would naturally take to the hills with his pan, pick, and shovel; but never before have inexperienced, would-be prospectors and placer miners materialized from the factories and farms, the haberdasheries, and the oil and gasoline supply stations, in such numbers as the last couple of years have witnessed, except when rich strikes of the proportions of a Klondike have been made. What, may one ask, has occasioned this condition? Unemployment has put these men in a receptive frame of mind, and newspaper and magazine articles have done the rest-- The Gold Miner of Los Angeles (a new weekly), The Mid- Week Pictorial (New York) for Sept. 3, 1932, and Popular Science Monthly for August, 1932, for instance. Even the Saturday Evening Post had an article on a promising part of Colorado. Stories that good wages may be had for the panning in nearly every western state have been featured by daily papers, popular "scientific" magazines, and quasi- technical journals. These tales have been eagerly grasped by thousands of people whose ignorance of mining has only served to increase their enthusiasm.

Jan 1, 1932

By M. E. Fine, A. A. Hendrickson

The critical resolved shear stress and the strain rate dependence of the .flow stress are reported for Ag base A1 single crystals up to 6 at. pct A1 over a temperature ralzge of 4.1° to 470°K. At room temperature the solid solution strengthening is attributed brinciballv to an increase in the dislocation density on alloying. At 42°K the alloys are relatively stronger because the dislocations widen on alloying and are more difficult to cut. In a previous paper, the authors reported the characteristics of strain aging in Ag base A1 alloys.' The variation of the magnitude of the strain-aging yield drops on aging time, aluminum content, and testing temperature strongly indicated that the phenomenon is due to the Suzuki mechanism. In the present paper, the critical resolved shear stress (CRSS) and the strain rate dependence of the flow stress are reported for Ag base A1 single crystals as functions of testing temperature (4.2" to 470") and A1 content (0 to 6 at. pct). Observations on the substructure and measurements of the effect of crystal growth rate are also given. The experimental re- sults appear explainable considering that aluminum additions increase the dislocation density and dislocation width. EXPERIMENTAL METHOD The methods of specimen preparation and tensile testing were described previously.' Briefly, single crystals were grown from the melt in a vacuum (1 x lom5 mm Hg), shaped into tensile samples by a combination of abrading and acid etching, annealed at 850°C in a vacuum (1 x 10" mm &Z) for several days, and furnace cooled to 200'. The testing was done on a model TM Instron using friction grips and a strain rate of about 5 x 106 per sec unless otherwise noted. The various testing temperatures were obtained by immersing the specimens in the following media: 1) 4.2': liquid helium using the apparatus of G. Byrne;' 2) 77°K: liquid nitrogen; 3) 200"K: dry ice and acetone; 4) 415' K: ethylene glycol; 5) 460' \ to 480' : molten Stanalax. In the determination of the CRSS above 296' K, a ratio method was used; the crystals were strained initially at the higher temperature, 0.1 pct shear strain, and then tested at 296' . The ratio of the flow stress between the two temperatures was then multiplied by the average CRSS at 296' K to obtain the value of the CRSS at the high temperature. (The test at 296' showed a yield point resulting from strain aging; the flow stress at 296' K was taken as the lower yield stress.) The ratio method, we believe, is more accurate than using different crystals since

Jan 1, 1962

By A. T. Aldred

HIS note reports the existence of several new scandium intermetallic compounds of the A2B and AB stoichiometries where the A element is scandium and the B element is from group VIII or IB of the periodic table. Alloys were arc melted from high-purity materials using 2-g charges. Typical lot analyses for the materials used are given in Table I. Chemical analyses were not made on the alloys as there was little or no weight loss on melting. After annealing the specimens for 14 days at 600°C and water quenching, metallographic and X-ray techniques were used to determine the occurrence of the various phases. Table II lists the relevant data for the A2B phases. The Ti2Ni structure,2 has ninety-six atoms in a face-centered cubic cell, whilst the Al2Cu structure is body-centered tetragonal.3 The occurrence and stability of the various A2B type phases in transition metal alloy systems has recently been considered by Nevitt.4 The Ti2 Ni-type phases occur over a relatively narrow range of radius ratios from 1.14-1.26 with A partners mainly from the titanium group and B partners predominantly from the cobalt group. This suggests that both a favorable relative size of the atoms and a favorable electron concentration are necessary conditions for the existence of this structure type. A12Cu-type phases involving Ti group elements as A partners are formed with B partners from the cobalt and nickel groups, predominantly the latter, and have a higher radius ratio (1.27-1.29) than the Ti2Ni-type phases. The occurrence of both Sc2Pd and Sc2Co can be rationalized in terms of these considerations but SczNi is anomalous because of its high radius ratio. The radius ratios are calculated from the Goldschmidt CN12 radii and it might be postulated that the scandium atom is reduced in size in the compound. Unfortunately the apparent atomic size of scandium in the compound cannot be calculated from a knowledge of the structure and lattice dimensions. The crystal structure of the Sc2Au compound could not be identified from the powder diffraction pattern, but it is interesting to note that it is isostructural with a series of A2Au phases where A is a rare earth element.5 Pertinent information concerning the AB phases found in this investigation is given in Table 111. All the phases have the ordered bcc CsCl structure. The occurrence and stability of CsC1-type phases have recently been discussed by Dwight,7 who concludes that the relative sizes of the atoms do not appear to be a controlling factor (the radius ratios of all the known phases vary between 0.985 and 1.439) but that the occurrence of the phase is predominantly dependent on the relative positions of the A and B partners in the periodic table. As a measure of the stability of a given CsCl phase it has been customary to define a lattice contraction on alloying, DAB — dAB, where DAB is the AB interatomic spacing as calculated from the Goldschmidt CN8 radii and dAB is the AB interatomic distance in the compound (= v3/2 ao). Values of the parameter DscB -dScB for the compounds found in this investigation are given in column 5 of Table III and are plotted in Fig. 1. If the lattice contraction does in fact reflect the stability of a phase then Fig. 1 shows two very interesting trends when the position of the B partner in the periodic table is considered. Firstly, within any given group the stability increases in order on going from the first to third long period. Secondly, within any given period the stability increases in order as the B partner is taken from the copper, nickel, and cobalt groups. In the case of the second long period, the lattice contraction reaches a maximum at ScRh and then decreases to ScRu. The same trend could

Jan 1, 1962

By Yoichi Ishida, Ching-Yao Cheng, John E. Dorn

Tile creep behavior of a iron was investigated over the range of temperatures from 375° to 1150°K. Apparent activation energies for creep, obtained by the effect of sudden changes in temperature on the creep rate, revealed the presence of- four distinguishable regions. The creep behavior of a iron in Regions II (480° to 774°K) and 111 (775° to 1045°K) was found to correlate well with a model where the creep rate is controlled by the nonconsevualive motion. of jogged screw dislocations. An anomalous increase in the apparent activation energy fur creep in Region III was found to be in harmony with the known decrease in the free activation energy for self-diffusion over the Curie transformation range. Furthermore, the creep rates in Regions II and III were found to increase with stress due not only to the effect of stress on the activation energy but also to an increase in density of mobile dislocations. The evidence suggests that pipe diffusion along moving dislocations could be a significant factor over the lower temperatures of Region II. ALTHOUGH the creep properties of iron and steel have been of interest to metallurgists for some time and an extensive literature is now available, most of the published information has not produced much toward understanding the fundamental dislocation processes controlling the creep behavior of these materials. Whereas the activation energy for high-temperature creep of metals usually agrees well with that for self-diffusion, Sherby, Orr, and Dorn1 deduced from the data of Tapsell -and c1enshaw2 that the activation energy for creep of Armco iron is about 78,000 cal per mole and more recently Lytton and sherby3 reviewed the data of Jenkins and Mellor4 and found an activation energy for creep of a iron of 80,000 cal per mole. Both values are substantially greater than the activation energy for self-diffusion in a iron. Because of the limited data suitable for purposes of identifying the controlling dislocation mechanisms of creep and the unusually high activation energies for creep quoted above, it was considered desirable to reinvestigate in detail the creep of a iron by more reliable techniques which would provide sufficient data for determination of the creep mechanisms. EXPERIMENTAL TECHNIQUE Creep specimens were prepared from 3/8 by 4 in. iron bar stock of the following composition by weight percent: 0.001 C, 0.0120 0, 0.001 N, 0.004 S, and 0.003 P. The as-received bars were cold-rolled to a thickness of 0.100 in., annealed under argon for 30 min at 1113°K, cold-rolled to a final thickness of 0.063 in., and machined into tensile specimens having gage section 0.250 in. wide and 1.70 in. long. Finally they were recrystallized under argon at 1113°K. Specimens to be crept above 1060°K were recrystallized at 1173°K. Both recrystallization treatments gave the same reproducible equiaxed ASTM No. 4 grain size. Creep testing was conducted in machines fitted with Andrade-Chalmers arms that maintained a constant stress to within ±0.2 pct of the reported values. Deformation over the specimen gage section was sensed with a linear differential transformer and recorded auto-graphically as a function of time. The strains deduced from these measurements were sensitive to ±5 x 10-5. During creep the specimens were contained in an argon-filled chamber which was immersed in a temperature-controlled molten tin bath. Creep temperatures, as measured by thermocouples attached to the specimen, were maintained to within ±10.25°K of the reported values. For activation-energy determinations rapid changes in temperature of about 12°K were obtained within 30 sec by direct resistance heating of the creep specimen, and maintained to ±1°K of the reported values. Observations of structural details of specimens before and after creep tests were made by electrolytic polishing and etching in acqueous ammonium persulfate. EXPERIMENTAL RESULTS A typical example of the determination of apparent activation energies, Q, by the effect of small changes in temperature is illustrated in Fig. 1. Q is defined by

Jan 1, 1967

By LUIS EAIYLNN SALAS

IF the ordinary wet method be attempted for silver-bullion containing tin, much trouble is experienced, varying with the amount of tin present. Even with a percentage as low as 0.05, the end-point is masked by a persistent turbidity, while with amounts ranging from 0.5 per cent. upward, the determination of the exact end-point is impossible, owing to the finely divided or colloidal metastannic acid resisting all efforts to cause it to settle, or to give a clear supernatant liquid. The object of the following experiments was to seek a remedy for these difficulties, and to find the conditions whereby the Gay Lussac method might be applied directly to these bullions. Material containing tin is met with frequently in bullion from Mexico or Bolivia; and tin is carried (sometimes in large quantities) in jewelers' sweeps. 1. A bullion was prepared containing Ag, 74; Cu, 25; and Sn, 1 per cent. A weighed amount was treated by the humid assay-method as if it were an ordinary bullion free from tin. Ten cc. of HNO3 (1.21) was added, and the bottle was heated until all traces of red fumes had been expelled. Before heating, the solutions were moderately turbid; and after heating, the turbidity greatly increased. One hundred cc. of normal NaCl solution was added and the bottle was shaken vigorously at intervals during 30 min. The turbidity persisted. The bottle was allowed to stand over

Mar 1, 1912

"The Washoe Smelter is situated about two miles east of the City of Anaconda. The smelter site includes about 240 acres and peculiarly adapts itself in topography to the efficient handling of material. By reason of its being on a hill side it is possible to make the level of delivery of the product of one building the level of the charge floor of the next succeeding one.THE ORES: The ore treated comes principally from the Butte district and is hauled by the Butte, Anaconda & Pacific railway, a distance of twenty-eight miles, in trains of fifty 50-ton bottom-dump cars to the railroad yards at East Anaconda. At this point these trains are• split up according to their destination,—that is, as to whether they go to the concentrator and sampling mill ore bins, or to the storage bins. In each case they are made up into trains of eight or sixteen cars, according to the size of engine to be used, and are carefully weighed before delivery to their respective bills.Some idea of the magnitude of the works may be obtained from the following figures:Amount of ore that can be treated in 24 hours…12,000 tonsLime rock from adjacent quarries…2,300 tonsCoke used…500 tonsCoal for reverberatory use…500 tonsCoal for power use…50 tonsWater, per minute, 35,000 gallons.Men employed in and around Anaconda, 3,000. Monthly payroll for above, $300,000.00."

Jan 1, 1913

By Donald C. Barton

The theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A = KMRm2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations,in regard to gravity, that other body usually is taken as a unit of mass: in the C:. C:. S. system, a body of one gram in mass. Gravity and Level Surfaces Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm. /sec.2) and less commonly lrierely as centimeter-gram-second units (c. g. s). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. In most cases, it is very nearly, but not quite, perpendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as ('the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it comrrlonly is very nearly, but not quite, a straight line.

Jan 1, 1929

By ROBERT R. RICHARDS

My. first paper, read at the Cobalt Meeting of the Institute,1 July, 1907, dealt with the behavior of a small Wilfley table when concentrating galena from quartz, the table being fed with natural products, with sized products; and with classified products. Since galena, having a specific gravity of 7.5, is among the heaviest minerals ordinarily concentrated by Wilfley table, it was desirable that a similar set of tests upon a mineral of, lighter weight should be made. Chalcopyrite, of a specific gravity of 4, would have been the best mineral for this purpose, on account of its great importance as an economic mineral, but in carrying out the test, however, I was obliged to content myself with a cupriferous pyrite, the specific gravity of which was 4.68 and the contents in copper 8.80 per cent. Through the kindness of Mr. H. 0. Cummins, this material was obtained from Shasta, Cal.,in very pure, clean, homogeneous condition. It was broken by rolls to 2 mm. in size, taking care to make a minimum of slimes. The quartz used to mix with it was pure, white, New England quartz, broken in the same way to the same size. In studying the accompanying tables, it should be borne in mind that the material concentrated was of low copper-content, and in many cases the quantity fed to the machine was 1 kg: or less.. As a consequence of the smallness of the 'quantity treated it was very difficult to adjust the table and get it in condition to do its best work before the feed became exhausted, and for this reason many results were obtained which appear irregular.

Sep 1, 1908

By William E. Ford, Edward Salisbury Dana

34. Axial Ratio, Axial Plane. - The crystallographic axes have been defined (Art. 22) as certain lines, usually determined by the symmetry, which are used in the description of the faces of crystals, and in the determination of their position and angular inclination. . With these objects in view, certain lengths of these axes are assumed as units to which the occurring faces are referred.

Jan 1, 1922

By Harvey Brooks

Jan 1, 1963

By Mark R. Lamb

THE various methods of treating pulp in air-agitation tanks offer problems for experiment and study which are fascinating as well as practical. The usual method heretofore has been to fill each tank in turn, agitate the mixture the required period and then discharge the treated pulp into a storage-tank, from which it. is drawn to the filter as required. A later method is to run the pulp from the tube-mill, classifier, thickener, or settler into the first of a set of tanks, and thence continuously or in series through the remaining tanks, finally drawing off the pulp to a continuous filter, or to a pulp-storage tank if the filter is of the intermittent type. It is this method which I propose to discuss here in a preliminary way, with the idea of going exhaustively into the examination of the results of a series of experiments in a later paper. It may be of interest to note that the design of a cyanide-plant has recently been completed in which the estimated cost of the agitation-tanks, storage-tanks, and pumps was 30 per cent higher for the charge-agitation arrangement than for the series plan. The first question in studying the series method is, "What is the actual period of treatment undergone by the pulp?? One first supposes that by chance some of the pulp may get through with little or no treatment, while other portions may stay in the tanks a needlessly long period. The former is not probable or even possible, and the latter is, practically, true to only a limited extent. The greater the number of tanks the greater is the percentage of chance that all the pulp will be treated equally. Without going into the mathematical analysis of the problem (which is of little value, since it is based on problematical premises), its important terms may be clearly grasped by thinking of, or " visualizing," the conditions when,

Jan 1, 1910