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The curve of Fig. 3 for pyrite requires modification. There 11% a range of pH values from 6.2 to 7.8 for which no cyanide is required to prevent contact. From 7.8 to 11.3 a small amount of cyanide is required, with a sharp maximum of 20 mg. per liter at pH=9.6. The mistake arose from considering too few solution compositions (17 were considered) in constructing the curve. Subsequent work with other collectors indicates that the corrected curve is typical for such systems; it illustrates the further development of the dip in the pyrite curve of Fig. 5.

Jan 1, 1938

By Klaus Detert

Fifteen and 18 pct Ni maraging steel and several binavy and ternary alloys of the iron-rich corner of the Fe-Co-Ni system have been studied. After annealing in the austenite range, these alloys were deformed slightly by cold rolling and subsequently aged. Compavison of experimental measurements at various processing stages indicates that small degrees of deforn~ation (5 to 10 pct reduction in thickness) do not influence hardness and strength or the aging kinetics. Electrical resistivity and ductility are somewhat redu]ced and the coercive force is substantially lower when compared to identical samples which were not deformed. The results are explained in terms of retained austenite which transforms into martensite with the small amount of deformation. RECENTLY there has been increasing interest in maraging steel for applications in electric power generators requiring a high ratio of power to weight.' Fifteen pct Ni maraging steel has been investigated to evaluate its properties and performance for application as high-strength magnetic rotor steel,' and a thorough investigation of the precipitation and transformation processes in this alloy has been conducted in this laboratory.3 The influence of deformation, which preceded the aging treatment, was also studied. It was found that a small deformation in the order of 5 pct has a rather striking effect in reducing the coercive force. Other interesting effects on the properties caused by such deformation have led to the more detailed studies reported herein. EXPERIMENTAL METHOD The methods used to produce the samples from 15 pct Ni maraging steel have been described elsewhere.3 The general procedure of hot forging and cold rolling to sheet has been followed. The composition is included in Table I which also contains the composition of the 18 pct Ni maraging steel grade 250 studied. More data about the material and the processing of the 18 pct Ni maraging steel have been recently reported.4 The experimental alloys of binary and ternary Fe-Ni-Co alloys were made by levitation melting in an argon atmosphere and casting into rod-shaped ingots 7 mm thick weighing 20 g. From these ingots 25-mm-long rods were machined to study the phase transformation by a dilatometer. These rods were then cold-rolled to strips, 2.4 mm thick. Annealing for austenitizing was done in tube furnaces in an argon or helium atmosphere followed by cooling in the water-cooled portion of the tube. Aging was done in a salt bath containing a neutral blend of Alkali nitrates and nitrites. Vickers hardness was measured using a load of 50 kg for 15 sec. Tensile tests were carried out on a hard beam tensile tester at a strain rate of 5 X lo-' per sec using flat samples with a gage length of 37.5 mm and a cross section of 1.25 by 6.25 mm. Estimated sensitivity was 5 K x strain and 0.35 kg per sq mm stress. Magnetic saturation was determined on small cylindrical samples, 2.5 mm in length and diameter, by measuring the force exerted by the gradient of a magnetic field of 1000 oe per cm in a mean field of 11,500 oe. The measured values could be reproduced within *1 pct. Coercive force was measured by a precision-type magnetic field probe in a magnetic coil as described by Foerster.5 The magnetizing field was 1300 oe. The samples were 5 cm long, 1 cm wide, and 2.4 mm thick. he coercive force was measured to within +0.1 oe. Electrical resistivity was measured by using a potentiometer on flat strips with a gage length of 100 mm and a cross section of 2.5 by 0.5 mm. The accuracy of the measurement was 0.1 pct but the reproducibility of the measured specific resistivity among different samples was in the order of 1 pct. The method used to prepare the samples for electron transmission has been reported elsewhere.3 RESULTS Fig. 1 shows the influence of deformation after annealing on the resistivity, hardness, and coercivity. The samples were annealed for 30 min at 1000"C,

Jan 1, 1968

By Charles R. Cavanaugh, John F. Elliott

The activity of nickel in liquid Pb-iVi alloys which are rich in lead was measured in the temperature region of 700° to 1100°C by means of the galvanic cell: The electrolyte used was stabilized zirconia. Tlze data were correlated using the a function, and a plot of the temperature coefficient aE/aT All subsequent calculations of the thermodynamic properties are based on these two functions. The activity, activity coefficient, and molar properties of mixing of nickel are reported. Nicke1 shows extreme positive deviations frorn ideality while lead shows a very slight positive deviation in the composition range studied The study of the activity of nickel in liquid Pb-Ni alloys reported herein was undertaken to explore the use of stabilized zirconia, an oxygen-ion electrolyte, with liquid-metal electrodes, and to obtain further information on the thermodynamic properties of the liquid binary Pb-Ni system. The cell The reversible electromotive force of the cell results from the difference in the chemical potential of the oxygen at the two electrodes: po, (left) - p~ (right) = -4E5 [I] The chemical potential of oxygen on the right is fixed by the activity of nickel in the solution and pure solid nickel oxide. That on the left is set by pure solid nickel in equilibrium with pure solid NiO. By definition: Since the chemical potential of nickel is related to the chemical potential of oxygen through the equilibrium constant for the formation of NiO from nickel and oxygen gas, the electromotive force of the cell is also expressed In this case, n is 2, E is the reversible potential of the cell, and 5 is Faraday's constant. The work of Kuikkola and wagnerl and Schmalz-reid2 has shown that the stabilized zirconia electrolyte is essentially an ionic conductor at the oxygen levels encountered in the experimental arrangement of the work, i .e., PG > 10-l7 atm. THE EXPERIMENTS The advantage of this type of reversible cell over those using a liquid electrolyte is the simplicity arising because the electrolyte also functions as one of the containing crucibles. A further simplification was the choice of the Ni (sat.)-NiO electrode as the standard. This permitted a ready check on the behavior of the electrolyte, as the potential of the cell must become zero when the right electrode becomes saturated with nickel, either because of a change of temperature or because of the addition of nickel to the electrode. It also permitted the potentials being measured to lie in the most satisfactory experimental range of 0 to 100 mv. Although it was not theoretically necessary, lead was included in the standard electrode as it assured good contact between the electrode and electrolyte. Cell Design. The general arrangement of the experimental cell assembly is shown in Fig. l(a) and the details of the cell itself are contained in Fig. l(b). The anode lead wire on the interior of the cell was connected to a coil of perforated sheet nickel. Within this coil were nickel oxide pellets which were held beneath the surface of the liquid Pb-Ni alloy. A disc of nickel oxide was held at the bottom of the external crucible (alumina) by means of the thermocouple protection tube. The nickel oxide disc and pellets were compressed dry at 10,000 psi and sintered at approximately 1000°C for an hour in air. A major experimental difficulty of reversible electromotive force cells with liquid electrodes is the selection of suitable materials for connecting

Jan 1, 1964

By H. G. Schneider

THE Smackover oil and gas field lies in Ouachita and Union Counties, Ark., in the south-central part of the state, in T.15 and 16S., R.15, 16, and 17W. It is 10 miles north of El Dorado, the principal business and railroad center in the south-central part of the state, and extends from the town of Smackover in all directions. Productive territory having an aggregate area of nearly 55 sq. mi. has been developed. It extends 6 miles from north to south and 12 miles from east to west. The field may be divided into two parts: the east district, which includes the area east of the town of Smackover, and the west district, which includes the area west of the town of Smackover. In relation to the neighboring productive fields of Arkansas, the Smackover field is 9 miles north of .the El Dorado oil and gas field, 8 miles slightly west of north of the East El Dorado oil and gas field, and 16 miles east of the Stephens oil field. Smackover was discovered in May, 1922, when the Oil Operators Trust drilled well No. 1 on the J. T. Murphy farm, in the southeast quarter of sec. 8, T. 16S., R.15W. This well is located almost, on the top of the Norphlet dome and was drilled to the Nacatoch sand. It had an initial open flow volume of 30,000,000 cu. ft. of dry gas per day, and a rock pressure of 950 lb. per sq. in. In July, 1922, the V. K. F. Co. completed the first oil well in sec. 29, T.15S., R.15W., on the north side of the Norphlet dome, and 3 miles north of the first gas well. This well started the active development of the north and northwest sides of the dome.1

Jan 3, 1924

By I. A. Goddard

INTRODUCTION This paper deals with the development of the sublevel open stoping (SLOS) method in lead orebodies at the Isa Mine of Mount Isa Mines Limited, during the last ten years. Open stoping in different forms has been used at the Isa Mine for many years. Prior to the period under review, stopes were small, pillars were not always recovered, and scrapers extracted the ore. By the end of the sixties, the use of load-haul-dump units was becoming more widespread. Wagner ST5's were the mucking units for the lead cut and fill stopes. Some of the open stopes in 5 orebody above 13 level had 100 kW slushers, but the more southerly stopes were the sites for the introduction of diesel front-end loaders for extraction. In the early seventies, new methods were used in the block of six stopes in 2 and 5 orebodies between 8 level and 13 level and a trial stoping project was undertaken in 7 orebody between 11 level and 13 level to determine possible stope dimensions for the extraction of the Racecourse orebodies below 13 level. By the mid-19701s, stoping was well underway in 5, 7 and 8 orebodies between 13 level and 15 level, using the 'triplet' system, incorporating cemented hydraulic fill to allow greater pillar recovery. As the eighties were entered, development of the Racecourse orebodies below 15 level commenced, as did preparations for 1 orebody in the upper levels of the north end of the mine. In both cases, the pillar recovery method has been changed to reduce the amount of cemented fill required for pillar recovery. GEOLOGY Most of the lead orebodies at Isa Mine lie chiefly to the north of the central shaft complex. They are bedded sulphide deposits in a host rock called Urquhart Shale, which dips at roughly 650 to the west. The main minerals are galena and sphalerite, with the silver mineral, freibergite, being contained in the galena. To the hangingwall of the sequence are the Black Star orebodies (1, 2 and 5) which are relatively wide, pyritic and with low to above average grade lead. The Racecourse orebodies (6 to 16) lie to the footwall, and have a large variation in width, low to high grade lead, and gradation in the lead to zinc ratio from north to south. Stope outlines are often determined by economic or engineering considerations rather than geological. The published extraction reserves are 56 million tonnes of primary ore, containing 150 grams of silver per tonne, 6.4% lead and 6.5% zinc. Traditionally, it has been regarded as lead ore, although the dominant revenue earner varies from time to time. In the Black Star orebodies, the ore and hangingwalls are more competent and open stoping has long been used. The major Racecourse orebodies which have been open stoped are 7 and 8 orebodies. This has been where the orebodies are wider (to the south) and where hangingwall conditions allow. This latter aspect has been greatly influenced by the presence of 'silica dolomite1. This tough, relatively homogeneous, non-bedded rock is, in fact, the host rock for the copper mineralisation at Mount Isa, and provides a competent hangingwall for some of the lead stopes. While the shale's bedding and jointing has a major influence on the ground conditions, there is a major fault system which causes local problems. The principal virgin stress direction is perpendicular to the bedding, but the local stress situation is complicated because of shielding by filled stopes in the hangingwall copper orebodies and because of the interaction between orebodies being extracted to the footwall. Most development on strike is mined with a 'shanty-back’, with the back being as close to normal to the bedding as possible. This is near parallel to most jointing and the principal stress direction. Figure 1 is a plan view of 14 level north, which provides a representative horizontal section through the orebodies. A typical cross section is shown in Figure 2. The narrow, parallel footwall orebodies can be seen to differ from the wider hangingwall orebodies.

Jan 1, 1981

By AIME AIME

HONORARY COMMITTEE. HON. C. D. WALCOTT (Chairman.), Director U. S. Geological Surrey. HON. FREDERICK I. ALLEN, Commissioner of Patents. DR. FRANK BAKER, Superintendent National Zoological Park. MR. CHARLES A. BELL, President American Security and Trust Co. MAJOR JOHN BIDDLE, Engineer Commissioner of District of Columbia. ADMIRAL C. M. CHESTER, Superintendent U.S. Naval Observatory. GENERAL WILLIAM CROZIER, Chief of Ordnance, U. S. A. ADMIRAL GEORGE DEWEY, Admiral of the Navy. COLONEL CLARENCE R. EDWARDS, Chief Bureau. of Insular Affairs. MR. WILLIAM C. FOX, Director Bureau of American Republics. MR. CHARLES C. GLOVER, President The Riggs National Bank. GENERAL A. W. GREELY, Chief Signal Officer, U. S. A. MR. BERNARD R. GREEN, Superintendent Library Building. GEN. G. H. HARRIES, Vice-President Washington Electric Railway Co. HON. E. A. HITCHCOCK, Secretary of the Interior. COMMANDER H. M. HODGES, Chief Hydrographer, U. S. N. PROF. W. H. HOLMES, Chief Bureau of American. Ethnology. PROF. S. P. LANGLEY, Secretary Smithsonian Institution. GENERAL ALEXANDER MACKENZIE, Chief of Engineers, U. S. A. ADMIRAL N. E. MASON, Chief Bureau of Ordnance, U. S. HON. WM. M. MEREDITH, Director Bureau of Engraving and Printing. HON. V. H. METCALF, Secretary Department of Commerce and Labor. HON. WILLIS L. MOORE, Chief -U. S. Weather Bureau. HON. PAUL MORTON, Secretary of the Navy. MR. F. H. NEWELL, Chief Reclamation Service, U. S. Geological Survey. HON. S. N. D. NORTH, Director Census Office. CAPT. E. C. PENDLETON, Superintendent Naval Gun Factory. MR. GIFFORD PINCHOT, Chief Forester, Department of Agriculture. MR. HERBERT PUTNAM, Librarian of Congress. ADMIRAL CHAS. W. RAE, Chief Bureau of Steam Engineering, U. S. A: MR. RICHARD RATHBUN, Assistant Secretary Smithsonian. Institution. HON. W. T. RICHARDS, Commissioner General Land Office.

Jul 1, 1905

By T. J. Fabiniak, R. A. Dodd, R. Balow

ALTHOUGH the (111) slip direction in pure bcc metals is well established, the information on operative slip planes is less unambiguously interpreted. So far, (110) {112), and (123) slip planes have been identified, but it is not certain whether glide on (112) and (123) really occurs or if it is composite slip on non-parallel (110) planes. The second of these possibilities is supported by the work of Chen and Maddin on niobium and molybdenum, and a subsequent analysis by these same workers of slip in bcc metals generally.3 The alternative possibility is exemplified by the work of Opinsky and smoluchowsky4 who concluded that slip in Fe-Si crystals can occur on any one of the systems {110}(111), {112}(111), and {123)(111), depending on which system the resolved shear stress is highest. Allen et alS5 also found that glide in ar iron could occur on any of these three systems, the operative system being determined principally by orientation. By an analysis of crystal rotation, slip lines, and X-ray asterism Harris6 concluded that niobium also deforms on these same systems, but if one of these glide planes does not coincide with the plane of maximum resolved shear stress, composite slip on nonparallel (110) planes may occur giving a macroscopic high indices slip plane. Earlier work on iron by Vogel and Brick reached the same conclusion.7 The analysis of slip in bcc metals is made more difficult by the fact that the slip lines may be quite wavy. In fact, the generality of wavy slip lines suggests that screw dislocations slip readily from one plane to another in the (111) zone ("pencil glide") although, as noted, it is not certain whether planes other than (110) really contribute to the slip. If planes of higher indices than {110} do operate, there is a possibility they may do so more readily at higher temperature Argon and Maloof9 observed {100}{211}(111) slip in tungsten single crystals plastically strained at low temperatures, but the results were interpreted in terms of an orientation-dependence rather than temperature-dependence. Therefore, at the present time corroborative evidence for the operation of higher indices slip planes at higher temperatures is lacking. The present results were obtained during the course of an investigation into the effect of cathode and anode surface crystallography on the prebreakdown currents of vacuum insulated devices. In the experiment of particular interest, the 1/8-in.-diam anode and the in.-diam cathode were tungsten crystals (total impurities -230 ppm) with (110) and (100) faces respectively. The faces were electrolytically planed and examined for initial perfection by plastic/carbon replicas and a study of Kikuchi lines in reflection electron diffraction patterns. They were aligned precisely parallel in an insulating holder incorporated into the electron microscope, the measured microscope vacuum being 2 x 10-5 torr, and the electrode spacing 0.01524 cm. The anode structure shown in Fig. 1 was obtained

Jan 1, 1970

By C. R. Simcoe, T. J. Koppenaal

The effect of direct and alternating currents on the quench aging behavior in an Al-4 pct Cu alloy has been investigated by use of resistivity measurements. The reaction rate increases with direct current density in the investigated range of 1000 to 3000 amps per sq cm. Alternating current of a specific frequency is observed to decrease the reaction rate by a factor of about two. ErDMANN-JESNITZER et al.,1,2 investigated the effect of direct and alternating current on the quench and strain aging behavior of low-carbon iron. In both cases they observed that direct current accelerates the aging reaction and that an alternating current can completely inhibit the aging process. The purpose of the present research was to investigate these phenomena in the quench aging behavior of an Al-4 pct Cu alloy and to determine the correlation, if any, between the increase in the observed reaction rate and possible heating effects accompanying the aging with direct current. EXPERIMENTAL PROCEDURE The aluminum-base alloy used in this investigation contained 3.98 wt pct Cu (1.72 at. pct) with impurities of 0.003 pct Si, 0.002 pct Fe, and 0.001 pct Mg. The alloy was rolled into a ribbon about 0.36 mm thick and 3.7 mm wide. The ribbon was split end from end with the ends being used as electrical contacts and the central unsplit section, about 5.3 cm in length, serving as the specimen. Solution treatment was accomplished by quenching from a salt bath at 520° ± 2°C into water at 25° ±0.5°C; the specimen was immediately transferred to a liquid nitrogen bath. All aging was done at 75° ± 0.2°C in a rapidly stirred ethylene glycol bath. Resistivity measurements were made by the double potentio-metric method employing a standard resistor; for purposes of convenience, the resistance measurements were made at 77°K. The transfer of the specimen from the aging bath to a liquid nitrogen dewar was accomplished in less than 1 sec. The aging kinteics were studied with the specimen being aged under the influence of direct current, alternating current, and without any type of current. The amount of heating caused by direct currents was investigated by soldering a thermocouple on the specimen surface and measuring the temperature change after applying various current densities. The temperature was observed to increase (from 75°C, the aging temperature) about 0.8°, 3.0°, and 8.5°C with direct currents of 1000, 2000, and 3000 amp per sq cm, respectively. When employing alternating current, the circuit was monitored with an oscilloscope and adjustments made to produce a normal sine-wave pattern. RESULTS Prior investigations3'4 in the aging characteristics of A1-4 wt pct Cu have shown that the resistivity initially increases, reaches a maximum, and then decreases to values significantly lower than the as-quenched resistivity. This type of behavior is seen in Fig. 1 which shows the resistivity at 77°K as a function of aging time at 75°C observed in this investigation. At this aging temperature, the resistivity maximum is seen to occur in about 1 to 1-1/2 min and it further decreases to the as-quenched value in about 24 min. The behavior observed with the application of direct currents of 1000, 2000, and 3000 amp per sq cm during aging is shown in Fig. 2. With increasing current densities, (+) ?pmax decreases and the rate of the aging process increases. The time necessary to reach the as-quenched resistivity value decreases from 24 min for aging without current to about 16, 10, and 7 min for aging with 1000, 2000, and 3000 amp per sq cm direct current, respectively. Fig. 3 shows the results obtained when two changes were made during the aging with 2000 amp per sq cm

Jan 1, 1963

The Arizona Committee, consisting of GERALD F. G. SHERMAN, Chairman, ARTHUR NOTMAN, Secretary, NORMAN CARMICHAEL, B. BRITTON GOTTSBERGER, W. L. CLARK, J. C. GREENWAY, W. G. MCBRIDE, FOREST RUTHERFORD, has arranged the following program for the Arizona Meeting, which has been approved by the President of the 'Institute and by the Executive Committee. It is printed herewith for the information of members, and probably will not be changed in any material respect. Monday, September 18, 1916.-Arrive at El Paso, Texas,, 6.30 A.M. Arrive at Deming, N. Mex., 9.30 A.M. Arrive at Chino, Ariz., 11.30 A.M., where luncheon will be served, after which there will be a visit to the Chino mines. From there the train will proceed to Hurley, N. Mex., where a visit will be made to the mill of the Chino Copper Co. Tuesday, September 19, 1916.-Arrive at Douglas, Ariz., at 8.00 A.M. The morning will be spent at the reduction works of the Copper Queen Consolidated Mining Co. "and of the Calumet & Arizona Mining Co. After luncheon a technical session will be held, with "Smelting" as a special subject for discussion. There will be a banquet in the evening, followed by another technical session or-a business meeting.

Jan 6, 1916

By R. G. Charles, E. A. Gulbransen, S. Barnartt

KINETICS of the reaction of zirconium with pure oxygen at elevated temperatures have been studied by several workers for periods of time up to 6 hr.1-1 In two cases,3-4 . the experimental values of oxygen uptake, w, as a function of time, t, were best fitted to the parabolic rate law w2 = kPt + constant. In others,3,4 the cubic rate law w3 = kot + constant, showed better agreement. The most recent data of Gulbransen and Andrew4 indicate that the choice between the parabolic and cubic laws for empirical representation of the data will often be arbitrary. This is particularly true if the first few minutes of the reaction with a clean zirconium surface is attributed to a different oxidation mechanism, for deviations from either rate law were found primarily during the initial period. Thus, the kinetics of this reaction have been too uncertain to permit safe extrapolation to oxidation periods of practical interest (many hundreds of hours). The data to be described are of interest, for they indicate that the cubic rate law applies over long oxidation times. The reaction of zirconium with oxygen at 1 atm pressure was followed at 350" and 450°C for 500 and 200 hr, respectively. Abraded test specimens of pure zirconium sheet' 3.0 X 2.0 X 0.012 cm in size were oxidized by the procedure previously described,3 which included periodic cooling to room temperature for weighing. The surfaces were polished to a 4/0 finish using polishing paper wet with kerosene, then wiped with petroleum ether and washed in redistilled acetone. Fig. 1 shows plots of log ? vs log t. Each curve represents the average of duplicate measurements, and deviations from the average were generally less than 3 pet. The cubic rate law (slope = 1/3) is closely followed. The rate constants, 5.2, x 10 -6 and 2.4, X 10- (mg cm-2)3 per hr at 350" and 450 oC, respectively, are plotted as log k, vs 1/T in Fig. 2, together with cubic constants calculated from the data of Gulbransen and Andrew4 for abraded specimens from the same lot of zirconium. Their data refer to runs of 6-hr duration at a pressure of 0.1 atm 0 and under conditions of uninterrupted heating. In spite of these differences, the latter data yield a straight line which appears to apply equally well to the new extended time data. The energy of activation for the oxidation process, calculated from the slope of this line, i.s 38 keal per mole. This may be compared with the value of 47 keal per mole found by Belle and Mallett3 at higher temperatures. It may be concluded tentatively that extrapolation of short-term oxidation data for zirconium to obtain the long-term behavior is best done through the cubic equation ?3 = kpt + constant. References ' E. A. Gulbransen and K. F. Andrew: AIME Trans., 1949, vol. 185, p. A.515; JouRNal OF Metals, August 1949. 'D.p. Cubicciotti Journal Amer Chemical August1949.Soc., 1950, Vol. 72, P. 3 V. Belle and M. W. Mallett: Joulnal Electro chemical Soc., 1954, ' E. A. Gulbransen 339.and K. F. Andrew: Oxidation of Zirconium Between 400" Gulbransenand 800'C.and AIME Trarzs.. 1957, vol. 209, p. 394; JOUR-Nal of Metals, April 1957. IS Barnartt, B G. Charles, and E. A. Gulbransen: Oxidation of 50 weight pet uranium-zirconium alloy, Journul Electrochemical SOC., 1957, vol. 104, p. 218.

Jan 1, 1959

By R. T. Hukki

This paper presents a series of equations for mechanical ball wear, relating parameters of ball size, mill speed, and mill diameter. The fundamental equation, Eq. 12, presented here is introduced to correlate these basic parameters and thus define and clarify the concept of ball wear. This equation is offered as a general rule, which may be modified to apply to individual problems of grinding. BALL wear as observed in grinding installations is the combined result of mechanical wear and corrosion. Corrosion should be a linear function of the ball surface available. Ball corrosion, however, has been studied so little that its effect, although of great importance, cannot be included in the analyses given here. In a separate paper' it is shown that 1 n = 0.7663 np----=— rpm [1] vD P = c, np D kw [2] T=c²(np)n De tph [3] In these equations n — actual mill speed, rpm np = calculated percentage critical speed D = ID of mill in feet P = power required to operate a mill, kw T = capacity of a mill, tph C¹ and c² - appropriate constants in = exponent of numerical value of 1 5 m 1.5 Exponent m is the slope of a straight line on logarithmic paper relating mill speed (on the abscissa) and mill capacity (on the ordinate). It is generally accepted, although not sharply defined, that ball wear in mills running at low (cascading) speeds is a function of the ball surface available. Accordingly, the wear of a single ball may be considered to be a homogeneous, linear function of its surface and of the distance traveled. Thus dw = f¹(d2) . f2(ds) [4] where dw is the wear of a single ball in time dt, d the diameter of the average ball in ball charge, and ds the distance traveled by the ball in time dt. Indicating that ds - a D n dt, the wear of the average ball in time dt becomes dw = f¹(d2) . f2(Dn dt) 1 --- f¹ (d1) f² (D c3 np-----— dt) \/D = c,d² n, D dt The rate of wear of the average ball is given by dw/dt. dw/dt = c, d² np D lb per hr [5] The weight of the ball charge per unit of mill length is a function of D The number of balls of size d in the ball charge is = f³(D2)/f4(d³). The rate of wear of the total ball charge equals the number of balls times rate of wear of the average ball. Thus rate of total ball wear = — . (dw/dt) w. c, . (l/d) . n,, D lb per hr [6] which is the equation of ball wear in low speed mills. In a mill running at a low speed, grinding is the result of rubbing action within the ball mass and between the ball mass and mill liners. When the speed of the mill is gradually increased toward the critical, the impacting effect of freely falling balls becomes increasingly prominent in comparison with the rubbing action. Reduction of ore takes place partly by rubbing, partly by impact. The share of the freely falling balls in the reduction of ore reaches its practical maximum at a speed somewhat less than the critical; at that speed grinding by rubbing has decreased to a low value. It may be reasonable to think that size reduction by freely falling balls should reach its theoretical maximum at the critical speed, if the fall of the balls were not hindered by the shell of the mill beyond the top point; grinding by rubbing would cease at the critical speed. As a first approximation, wear of freely falling balls may be considered to be a homogeneous, linear function of the force at which they strike pieces of rock and other balls at the toe of the ball charge. The force equals mass times acceleration. The mass of a ball is a function of d3 and its acceleration is a function of the peripheral speed of the mill. The wear of a single ball of size d representing the average ball in a ball charge will therefore be w¹ = f3(F) = f (d3) f7 (v). [7] Indicating that v = D n, and n = c³ np 1/vD, Eq. 7 becomes W1 = cn d3 np Do.5 lb per hr. [8] Total wear of the ball charge equals number of balls times the wear of the average ball. Number of

Jan 1, 1955

By John C. Bilello

The brittle fracture behavior of cold-worked sintered tungsten was studied over the temperature range 4.2° to 298°K using a high-sensitivity strain measuring system and electronfractography. Similar observations were made on a swaged electron beam zone-refined monocrystal. In sintered tungsten irreversible plastic deformation was observed during cyclic load-unload tests at stress levels well below the fracture stress for all temperatures, but general microyielding could be detected only down to 202°K. For the zone-refined samples macroyielding occurred at all test temperatures with evidence for twinning below -202°K. The fracture stress of the sintered tmgsten was virtually independent of temperature, while the zone-refined crystal showed a 2.3 times increase over the same temperature range. Electronfractography confirmed the presence of numerous rod-shaped and spherical submicroscopic voids which ranged in diameter from 1400 to 4300A in the sintered tungsten; no voids could be found in the zone-refined tungsten. Contrast effects observed on the replicas in the vicinity of certain voids indicated that plastic deformation could be induced by the local stress concentration. It has been suggested that the presence of these voids may be responsible for the low-temperature brittle failure of sintered tungsten. Based m this suggestim und on the evidence obtained here, a dislocatim model is presented to account for the brittle behavior of sintered tungsten. In this model slip, which is induced by the local high stress concentration in the region at the edge of a favorably oriented void, could cause the void to grow to a microcrack of critical size. STUDIES of brittle fracture in bcc metals have led to the well-known experimental relationships between grain size, yield stress, fracture stress, and temperature which have formed the basis for the various dislocation pile-up1-3 or interaction4'= models for slip-induced microcrack nucleation. While microcracks can be nucleated by deformation twins,6,7 there has been no direct evidence furnished by transmission electron microscopy to support conclusively either the Zener pile-up or Cottrell dislocation reaction models for producing micro-cracks in all "brittle" materials. In addition to the "inverse" grain size relationship for yield and fracture stresses the cottrel14 theory predicts that the fracture stress below the transition temperature should behave in a fashion similar to that of the yield stress above this temperature. Such behavior has been verified for several bcc metals.8-10 With reference to both grain size effects and the tem- perature dependence of the fracture stress below the transition temperature, the behavior of sintered tungsten appears anomalous. Early work by Bechtold and Shewrnon 11 showed no apparent temperature dependence of the fracture stress below the ductile-brittle transition temperature (DBTT). They attributed this result to the intergranular nature of the fractures observed. More recent work by Wronski and Four-deux12'13 on considerably purer material did not show any systematic relationship between the fracture stress and temperature below DBTT. The dependence of flow and fracture stresses on grain size is also not clearly established for sintered tungsten. Koo, for example, has shown that the DBTT for sintered tungsten depended chiefly on the annealing temperature and was relatively insensitive to the actual grain size achieved. Using electrofractography and transmission electron microscopy, Wronski and Fourdeuxl3 showed that numerous spherical and rod-shaped submicroscopic voids could be found in sintered tungsten but not in melted tungsten of nominally the same purity. They suggested that these voids could be responsible for the temperature insensitivity of the fracture stress below the DBTT. In the present work the temperature dependence of the fracture stress for high-purity commercially sintered tungsten has been determined. The presence of submicroscopic voids in sintered materials was confirmed, and these were studied in detail to examine the role they could play in nucleating brittle fracture. A dislocation model is suggested which could cause an inherent spherical void to lengthen into a Griffith crack of critical size. EXPERIMENTAL PROCEDURE Commercially sintered tungsten rod was obtained in the as-swaged condition from Sylvania. A zone-refined crystal was obtained from the same source. This crystal was grown by giving three zone passes (at 25.4 cm per hr) to a sintered rod of high-purity tungsten. The rod axis prior to cold working was -15 deg from the [110] direction. Originally the zone-refined rod was -6 mm in diam; it was reduced to -3 mm by eight swaging passes, at high temperatures, with each step having about the same reduction of area. The final swaging step gave a 7.5 pct reduction of area at 1050°C. All swaging operations were performed in a hydrogen atmosphere. For the sintered rod a similar working schedule was employed. Metal-lographic examination of the sintered material revealed that the cold-worked structure had an apparent grain diameter of -25 u transverse to the swaging direction (obtained by the intercept method). In the longitudinal direction cold-worked grains were approximately 1.5 to 2 times their diameter. No distinct fiber structure could be observed optically for the zone-refined rod. The cold-worked structure in the

Jan 1, 1969

By E. C. Burke, W. R. Hibbard

G. B. Craig (University of Toronto, Toronto, O,nt., Canada)—The advent of pyramidal slip at room temperatures in a magnesium crystal (M2,) and the very low value reported for the critical shear stress are puzzling. Table I1 shows the calculated values (approximate) for sin x cos I in this specimen if all the (10l) planes are considered. If So is the shear stress resolved in the direction of glide, on the glide plane, and U, is the stress operative in yield point tests, then: S,, — 325 (0.169) 55gpersqmm (approximately) for 1101: S,, = 325 (0.465) = 151 gpersqmm (approximately) for (0001): S,, — 325 (0.101) - 32.8 gpersqmm (approximately) Thus, we see the pyramidal plane in which the minimum shearing component operated. Barrett"' stated: "Experiments have repeatedly shown that, when there are several crystallographically equivalent slip systems in a crystal, the one having the greatest resolved shear stress will become active. ..." It does not appear to me that the measurements given are conclusive proof that pyramidal slip operated. E. C. Burke and W. R. Hibbard, Jr. (authors' reply) —Although the low value for the critical resolved shear stress for pyramidal slip may be puzzling, there does not appear to be any basis for questioning the validity of the measurements. Under the influence of constraints, slip systems having decidedly lower shearing components may become operative, e.g., "cross-slip" or the "forced glide" in magnesium reported by Bakarian. Since we believe that pyramidal slip occurred in the specimen because basal slip was inhibited, it is not too surprising to find an operative plane with a lower shear stress. -7 C. S. Barrett: Structure of Metals U94jl p. 2J6. New York. McGraw-Hill Book Co.

Jan 1, 1953

By R. E. Hummel, J. W. Koger

IT is generally accepted that the martensitic start temperature (Ms) can be determined by resistivity measurements and is that temperature where the resistivity vs temperature curve on cooling first deviates from a straight line.1-4 Both Titchener and ever' and pops5 have used resistivity measurements to follow the martensitic transformation in b1 Cu-Zn and ternary Cu-Zn-based b-phase alloys, respectively. Actually because of the nature of their measurements the temperature of minimum resistivity (M) was used by these authors to determine "Ms" . Also, due to experimental difficulties in detecting M, with resistivity measurements, Pops and Massalski 8 determined M, by optical microscopy. The present communication is concerned with high-precision, low-temperature resistivity measurements which reveal a definite M, temperature which differs from the temperature of minimum resistivity (M). It is also shown that M is merely the result of the geometry of the percent-transformation curve and the temperature coefficient of resistivity of the alloy. In other words, it will be demonstrated that M has no apparent significance (except that it denotes a temperature at which some percent of martensite can be detected in a given alloy). Alloy specimens were made by melting 99.999 pct Cu and 99.9999 pct Zn in sealed and evacuated quartz tubes and homogenizing them at 601PC for 300 hr. After the alloy was cold-rolled into foils suitable for resistivity measurements, it was quenched in ice water from 871PC. The chemical analysis showed a zinc content of 38.8 wt pct. The cooling rate during the martensite transformation was 1°C per min and was controlled with a thermistor. Electrical resistivity measurements were made using a K-3 type potentiometer; the reproducibility of the resistivity values was better than 0.03 pct. Temperatures were measured with a thermocouple to an accuracy of better than 0.2° C. Fig. 1 shows the resistivity vs temperature curves of the martensitic transformation in B1 Cu-Zn for both cooling and heating. The starting point of the martensitic transformation (M,) was taken as that

Jan 1, 1968

JOHN W. BELL, *Montreal, Quebec, Canada (communication to the Secretary?). The test results in Mr. Taggart's paper will, I am sure, be recognized as a notable contribution, and of great assistance in the study of the performance of the Hardinge mill. I regret, however, being obliged to note that Mr. Taggart still retains. such confidence in the Kick-Stadler method of computing the ?relative mechanical efficiency" of crushing machines. The Rittinger-Kick graph submitted by Mr. Gates and the tests made at McGill University disclosed precisely the same fundamental defect in the Kick-Stadler theory. Consequently, I have been obliged to recalculate in terms of Rittinger surface units the results obtained in the 28 rock-crushing tests cited by Mr. Taggart, in order to find- out what the relative efficiencies really were. In order to show the large discrepancies between the Stadler and Rittinger R. M. R's, the most, efficient result disclosed by each method is represented by the number 100, and the R.. M. E.'s for the other tests have been recalculated on this basis. The results will be found in Table 1. Personally, I look forward to the time when we shall cease to talk about "relative mechanical efficiency" and merely refer to the "efficiency" of a crusher. All that is required to accomplish this is to agree on a standard method for determining the "crushing constant" of a given rock and a standard method for calculating the efficiency. The figures in the fourth column of Table 1 have been derived by assuming a constant of 2,000 for the quartzite crushed in the Yale tests. The Stadler method sometimes indicates changes in efficiency produced by, changes in operating conditions, as I pointed out in a paper describing rock-crushing tests made at McGill University. It is, however, not enough to determine that certain changes increase or decrease efficiency; surely it is equally important to determine the magnitude of these variations. By examination of Mr. Taggart's results, I have been obliged to conclude that the size of feed and amount of reduction greatly influence the Stadler R. M. E. figures, that they are positively misleading. It should be mentioned that since the majority of the tests have been made at the least efficient feed rates, and since, moreover, it is one of the evidently very important factors affecting efficiency, it is possible that different results might be obtained by a high-tonnage feed series, and that

Jan 8, 1917

By H. L. Marcus, C. D. Turk

Titanium was physically vapor-deposited by electron beam high rate evaporation. Rates of 50,000 and 85,000Å per min at deposition temperatures of 480°, 535°, and 595°C were used. Deposited thickness ranged front 0.004 to 0.010 in. The evaporated titanium had a high degree of basal Plane texture. The specimens were tested in tension at temperatures ranging from 78° to 520°K. From the data, the yield stress, thermal component of the yield stress, and work hardening characteristics were found as a function of temperature, deposition rate, and deposition temperature. It was found that Taylor's equation, best fit the work hardening data with m = 1/2. MANY investigations have been made on the tensile deformation characteristics of commercial- and high-purity titanium.1"7 The data obtained from these experiments emphasize the fact that the mechanical properties are generally related to the method of production. The correlation of mechanical properties to production history arises from the dependence of impurity concentration on the extraction and melting technique used. Additional effects are derived from crystallographic texturing which can result from fabrication history. Lee and Backofen8 and other investigators9 have shown that crystallographic texturing in titanium sheet has a significant effect on the deformation characteristics. Bunshah and Juntz10 prepared high-purity titanium by high rate physical evaporation techniques. These authors found the deposited material to have a columnar structure with grain sizes ranging from 12 to 104 µ, depending upon the substrate temperature. The room-temperature strengths of the coarse-grained distillate were similar to arc-melted, rolled. and annealed crystal bar titanium. Commercial-purity titanium was also produced experimentally in our laboratory using high rate physical vapor deposition techniques. The commercially pure material has a finer structure than the high-purity distillate,10 and is highly textured. Since the method of preparation and degree of texturing affect the mechanical properties, a research program was initiated to determine the temperature dependence of the yield stress and work hardening characteristics as a function of high rate deposition parameters. This paper relates the results of the investigation. EXPERIMENTAL A) Material Preparation. The titanium was received in the form of commercial-grade 0.096-in.-diam wire which has a composition of 0.016 pct C, 0.0037 pct N, 0.110 pct 0, 0.011 pct H, 0.05 pct Mn, 0.051 pct Fe. balance Ti. The wire was continuously fed into a vacuum evaporation unit as shown schematically in Fig. 1. The deposition chamber was evacuated, purged with argon, and reevacuated to a pressure of 10-5 Torr which was maintained during deposition. A focused electron beam was used to evaporate the titanium from a water-cooled copper crucible. The titanium vapor was condensed onto a preheated titanium substrate. The temperature of the substrate was controlled within ±5°C for the deposition temperatures of 480°, 535°, and 595°C. Control of the input power enabled the use of two deposition rates. 50,000 and 85,000Å per min. The evaporated titanium had a final analysis similar to that of the input titanium, within experimental limits. B) Testing. The evaporated titanium was physically stripped from the titanium substrate and machined into tensile specimens with 1-in. gage lengths. In addition, tensile specimens of as received annealed 35-A titanium sheet with a 20 µ grain size and 45 pct cold-rolled 35-A were also prepared. All specimens were tested in tension in an Instron at a strain rate of 3.3 x 10"4 in. per in. per sec. Proportional limit has been used as a measure of yield strength. Tests were conducted at 78°, 220°, 300°, and 520°K. Metallography, X-ray diffraction, and electron microscopy were used to correlate structure with the deposition parameters and mechanical properties. Room-temperature X-ray measurements were made to determine the phases present. Pole figures and a scans were made to determine deposition texture. Because the vapor deposition was symmetrical about the normal to the substrate, there was no preferred di-

Jan 1, 1969

By R. P. Alger, C. A. Doh, M. P. Tixier

The principle, the equipment and field operation of sonic logging are described. The tfio-receiver system produces logs independent of hole size and mud. Field experience is given and forms the basis for the interpretation of the log. The derivaiion of porosity values from measured velocities is discussed, according to the type of formations (hard formations, compacted sands, and unconsolidated formations). The time-average equation proposed by M. R. J. Wyllie, A. R. Gregory and L. W. Gardner is uscd as a basis for the computation of porosity in limestones, cemented sandstones and compacted sands. Variations in the lithologic character of limestones do not seem to change the porosity calibration markedly. The compaction of sands is related to the compaction of shale adjacent to them; and, thus, the shale velocity is used for the establishtnent of empirical relations for the computation of porosity in un-consolidated formations. Various forrnu.las are tentatively presented to account for shale and fluid content. Field experience demonstrates that considerable attenuation of sonic energy takes place in unconsolidated formations, particularly when gas bearing, and in fractrured formations. Unusually large attenuation produces skipped cycles, a feature easily recognized. The application of sonic logging to structura1 studies is featured, showing its possible integration with the dipmeter. Correlation and its application to the irrterpretation of seisrmic surveys are reviewed. The paper is illustrated with field examples. Sonic logging is the recording of the time required for a sound wave to traverse a definite length of formation. Sonic travel-times are inversely proportional to the speed of sound in the various formations. The speed of sound in subsurface formations depends upon the elastic properties of the rock matrix, the porosity of the formations and their fluid content and pressure. Below the "weathered" or low-velocity layer extending from 50 to 100 ft or so below the surface, sound velocities may range from about 6,000 ft/sec in shallow shales to as much as 34,000 ft/sec in dolomites. In hard formations (well cemented and/or compacted), the sonic log reflects the amount of fluid in the formations; hence, it correlates well with their porosity. In unconsolidated formations, which are usually of fairly high porosity, the sonic log gives an approach to porosity determination, when its readings are corrected for lack of compaction, shaliness, and fluid content. In such formations the sonic log may also indicate the presence of gas and may distinguish between oil- and water-bearing beds. Field experience with the sonic log in soft formations is more limited than that in hard formations. As a result, interpretation in soft formations is not as well developed at the present time. In all types of formations the sonic log is of considerable value for correlation and for the more detailed and accurate interpretation of seismic data. EQUIPMENT AND PRINCIPLE FIELD OPERATION The basic features of the sonic log" are a two-receiver system and two available short spacings. The log is recorded on film using a standard field unit. An SP curve is run along with the sonic curve to give a more interpretable log and to establish absclute depth control for comparison with other logs run in the same well. If desired, a gamma-ray curve may be recorded simultaneously with the sonic curve. Fig. 1 shows the sonic-gamma ray combination sonde. The sonic portion consists of a sound transmitter and three receivers mounted 3, 4 and 6 ft from the transmitter. When the first and second receivers are used, a sonic log of I -ft spacing (distance between receivers) is obtainea. Use of the first and third receivers provides a 3-ft spacing. The transmitter emits pulses at the rate of l0/sec. After the transmission of a pulse the first arrival of sound energy at each receiver triggers its response system. The differ-

By Gregory M. Dexter

Recent litigation in Pennsylvania between three coal-mining companies and a private water company resulted in the payment by the coal companies of the equivalent of about $500,000 to buy a new water supply to replace that which had been damaged by acid drainage from strip mining. An investigation of the relevant facts indicates that the water could have been treated by spending about $40,000 on equipment and $15,000 yearly for chemicals, labor, and power until the contarnination could be reduced about 80 pct. The water company's supply, furthermore, had deteriorated largely by reason of dry weather before stripping was begun by the coal companies. Payment to the water company should not have exceeded $300,000 and could have been as low as $100,000. Strip mining of coal is common in Pennsylvania. The most important objection to it in Pennsylvania is generally acid pollution of runoff water. An outline of the methods, therefore, that could be used to reduce such pollution, to compare acid-contaminated waters. and to treat such waters to make them satisfactory for public and industrial use is worth-while. The watershed of the West Penn Water Co. covers about 4.5 square miles, 20 miles west of Pittsburgh, and has two 90,000,000 gal reservoirs supplying about 1,300,000 gal daily for public and industrial use of which 450,000 gal daily are for two railroads. The pollution arises from weathered derivatives of typical'" Coal Measures"' rocks, the principal source being pyrite (and marcasite) in Pittsburgh and Rooster coals. Springs and seeps on hillsides issue from sandstone and limestone formations intersecting shale or clay land surfaces, or from perched water tables. The two reservoirs create an artificial permanent water table. Soap-hardness tests on three seepage samples taken in a dry summer ranged from 150 to 500 ppm. Water sampled came from aquifers above Pittsburgh and Rooster coals, obviating the possibility of contact with pyrite-containing coal. Since acid contamination of mine waters is the result of chemical reactions of oxygen and water with pyrite, it will be reduced by the exclusion of either air or water. The Sunnyhill Coal Co. has applied this principle in its "contouring" method of strip mining by burying contaminated coal-waste material under a compact, smoothed-up surface of top-soil, gravel, clay, and sand at a cost

Jan 1, 1950

By R. M. Waterstrat

The phases occurring in the V-Mn system were studied by means of X-yay diffraction and metallo-paphic techniques, using are-melted alloy specimens annealed in the temperature range 800° to 1150°C and quenched. The bcc solid solution extends at 1250°C all the way from vanadium to 6-manganese. Below 1050°C the a-phase is formed, and the terminal a-manganese phase is stabilized up to about 900°C by vanadium in solid solution. IN the only previous general survey of the V-Mn system Cornelius, Bungardt and Schiedtl reported the existence of three intermediate phases corresponding to the approximate compositions VMn,, VMn, and V5Mn. The phase VMn8 has recently been identified as a o phase2 but the alloy VMn was found to have a bcc structure2 corresponding apparently to the vanadium solid solution rather than to the large cubic unit cell reported by Cornelius et al. 1 Subsequent work by Rostoker and Yamamoto3 has shown that the vanadium-base bcc solid solution extends to at least 15 pct Mn at 900°C. An alloy corresponding to the composition VMn, was examined by Elliott,4 who reported that the as-cast sample as well as samples annealed at 1200o and 1300°C had bcc structures, but that annealing at 1000°, 800") and 600°C produced two phases. One of these phases was apparently the bcc solid solution and the other resembled the o phase structure. Hellawell and Hume-Rothery5 established the phase relationships in manganese-rich alloys above 1000°C, and showed that the o phase in this system is replaced by the 6 Mn (bcc) solid solution at temperatures above 1050°C. These results suggest that a continuous bcc solid solution may exist above 1050°C between vanadium and 6 Mn. The present investigation was undertaken in order to develop more complete information in regard to this system. EXPERIMENTAL METHODS The alloys used in the present work were prepared by arc-melting electrolytic manganese having a minimum purity of 99.9 pct and vanadium lumps with a purity of 99.7 pct. The major impurities present in these metals were carbon, nitrogen, and oxygen and this would account for the small percentage of nonmetallic inclusions observed metal-lographically. The arc-melting was at first performed under a helium atmosphere and it was necessary to keep the melting times as short as possible in order to minimize the loss of manganese by vaporization. It was later found that the evaporation of manganese was considerably reduced when the melting was done under argon atmosphere. The final composition of each alloy was calculated by assuming that the total weight loss during melting was due to evaporation of manganese. Compositions which were calculated in this manner agreed reasonably well with the results of chemical analysis, as shown in Table I. Spectrographic analysis revealed the presence of contamination by tungsten, but in no case was the percentage of tungsten greater then 0.4 at. pct. The specimens were in each case broken in half and the fractured section was examined visually and microscopically for evidence of inhomogeneity. Each specimen was homogenized at temperatures near l100°C, as shown in Table I. After this treatment most specimens consisted of large columnar grains of the bcc vanadium solid solution. The etchant used in most of the metallographic work consisted of 20 pct nitric acid, 20 pct hydro-flouric acid, and 60 pct glycerine. It was found that this etchant would clearly delineate the phases present in these alloys although it does not produce any striking contrast between the phases. For certain manganese-rich alloys, a 1 pct aqueous solution of nitric acid was used. This etchant gave a brown color to the a-manganese phase, whereas the o phase was virtually unattacked and appeared very light as shown in Fig. 1. The etchants used by Cornelius et a1.l were found to produce spurious effects in some of these alloys. In particular, the vanadium-rich alloys etched in hot sulfuric acid often appeared to consist of two phases when both X-ray diffraction and etching with the glycerine-acid mixture indicated the presence of single phase bcc solid solution. A few percent of what appears to be an oxide or nitride phase was found at the grain boundaries and in the interior of the grains, especially in the vanadium-rich alloys. All alloys were annealed in sealed silica tubes containing 1 atm of pure argon and these tubes were then quenched in cold water. Although some manganese loss occurred during annealing, the loss seemed to be confined to the surface of the speci-

Jan 1, 1962

CARL E. SWARTZ, Chairman D. K. CRAMPTON, Past-Chairman CYRIL S. SMITH, Vice-Chairman ARTHUR PHILLIPS, Vice-Chairman FRANK T. SISCO, Secretary 29 West 39th Street, New York, N. Y. H. A. MALONEY, Treasurer Executive Committee 1943 1944 ERIC R. JETTE WILLIAM C. ELLIS LOUIS W. KEMPF ALAN MORRIS GEORGE SACHS KENT R. VAN HORN

Jan 1, 1942