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By Forrest F. Craig

Both early and more recent1 laboratory measurements of gas-oil relative permeabilities were made by subjecting oil-saturated cores to external gas drives. In these runs it was generally assumed that the flowing gas/oil ratio was constant at every point throughout the core. Using this assumption, the resulting equation for the gas-oil relative permeability ratio becomes A where Q is the flow rate at the producing end of the system. This relative permeability was then specified for the average saturation of the core. The assumption and resulting equation fail to recognize that in an external drive, the oil flow rate varies from zero at the injection end to a maximum at the producing end. The assumption also fails to consider the existence of a saturation gradient during an external drive. This saturation gradient is due solely to non-steady-state flow. Some authors2,3,4 have used this erroneous method of calculating relative permeability ratios from external drives. Other authors5,6,7 have used relative permeability ratios in calculating expected field performance by external drive, using Equation (1) and making the incorrect assumption that the saturation is uniform within the driven portion of the reservoir. To find the correct relation between the relative permeability. ratio at the average saturation and the produced gas/oil ratio, the insertion in Equation (1) of a factor, F, to adjust it for oil velocity gradient has been considered. The equation then takes the form Assuming that the oil velocity is directly proportional to the distance from the injection point leads to the conclusion that, for a linear system, the average oil velocity is one-half that at the producing end. Thus, the average gas/oil ratio is twice the produced gas/oil ratio, and Equation (2) is transformed into However, here again the existence of a saturation gradient is not recognized. The produced gas/oil ratio is related to the relative permeability ratio at the saturation of the outlet end of the system. It can be shown quite readily that, if the true log k,/k, saturation relationship is linear over small ranges of saturation, then d log kjko Where aaxv and u2 are the average and outlet saturations, respectively. Examination of Equation (3) shows that the factor F cannot have a single value over the whole saturation range. Another method of dealing with external drives is that of Buckley and Leverett.' Their method, which assumes no gas expansion and outlet end effects, considers fully the saturation gradient present due solely to the displacement mechanism during an external drive, and applies Equation (1) to each point along this gradient. The calculation of production history using relative permeability ratio is straightforward. However, the calculation of relative permeability ratios from production history by this method is impractical. In a recent paper, Welge,1 using an approach similar to that of Buckley and Leverett, presents a simplified method for determining the saturation at the producing end of the system. At thi; saturation, the relative permeability ratio calculated by Equation (1) applies exactly, after breakthrough of the stabilizej front. By this method, relative permeability ratios or production history may be calculated with equal ease. Use of this method as a laboratory tool in determination of relative permeability ratios by external drive requires the knowledge of the total injected fluid volume; in addition to the average saturation and producing ratio. As a preliminary test of this method of calculation, laborntory external gas drives were run on a 3% in. diameter, 11 in. long sample of Nellie Bly consolidated sandstone. This core sample had a permeability of 824 md and a porosity of 28.1 per cent. The driving fluid was air. Three different oils were used, having viscosities of 1.4, 9.8, and 125 cp, respectively. The runs were made under identical pressure differentials,

Jan 1, 1952

By Charles Janin

(San Francisco Meeting, October, 1911.) THE first successful bucket-elevator dredge to operate in California was put in commission at Oroville in March, 1898. There had been numerous previous attempts at dredging, but none of the earlier boats proved a success. The gold-miners in California early conceived the idea of a machine to dig gravel from the beds and bars of auriferous streams that were inaccessible by the methods then employed, and it was only a few months after the discovery of gold in California that such a machine was. shipped around Cape Horn from New York to San Francisco. This was, however, but the forerunner of many failures in gold-dredging, and was soon at the bottom of the Sacramento river. During succeeding years many other unsuccessful attempts were made, and it was not until 1897 that a dredge of the single-lift bucket-elevator type was floated on the Yuba river. This dredge was built by the Risdon Iron Works for R. H. Postlethwaite, and would probably have been a success if it had been operated on some of the rich Oroville ground instead of in a turbulent stream, where the dredge was wrecked during a flood, and was not repaired. Fig. 1 is a sketch-map of California, showing gold-dredging areas. It is not my intention to narrate in detail the history of the early failures in gold-dredging, and the various steps in the development of the modern boat, but merely to touch upon this in a general way, and to call attention to the wide difference in capacity and operating-cost between the first successful dredge, with an actual capacity of 600 cu. yd. per day-though its rated capacity was in excess of this-and the present modern dredge with 15-cu. ft. buckets, and an average capacity of 250,000 cu. .yd. per month. Even this enormous capacity has several times been exceeded on monthly runs. The first successful dredges

Mar 1, 1912

By Wing L. Lew

LEAD, silver, and zinc, in quantities of economic importance are found in the Aguilar ore. The lead occurs as galena and the zinc as sphalerite and marmatite. The silver occurrence is more complex. Pyrargyrite and proustite have been identified only occasionally. Galena is silver-bearing and so are the various other sulphides, though to a lesser degree. The principal nonsulphide gangue minerals include calcite, quartz, wollastonite, rhodonite, and various calcium, aluminum, and iron silicates. A typical analysis of, the ore is: Pb, 11.2; Zn, 12.3; Fe, 4.4; Mn, 2.2; Cu, 0.15; S, 11.2; CaO. 7.6; "Insoluble," 50.1 percent; and Ag 263 g per ton. Crushing is done in three stages. The primary crusher at the mine is set to deliver about a 5-in. product. The crushed ore is then transported to the secondary crushing plant by a 3-km cableway where the general practice is to hold the product of the first Symons to about 1 in., and of the second Symons to about 1/2 in. When the ore is soft and rich the product of the first Symons is by-passed directly to the ball-mill bins. Dust control in the secondary crushing plant is effected by enclosing the dust-emanating sources and exhausting the enclosures with a Clarage No. 18 fan driven at 1300 rpm by a 20-hp motor. Use is also made of spray water at one or two critical places. Every effort is made to keep the air free from visible dust. Dust counts taken at the working places show dust concentrations of less than six million particles ner cu ft. The composition

Jan 1, 1947

By Milton E. Jennings

On May 11, 1977, the SAMARCO 508-mm (20-in.), 396-km pipeline was placed in service. This system represents the latest thinking in slurry pipeline design and is one of the main contributors to the viability of the SAMARCO project. This paper presents the background, description, and latest information on the system's operation. Special attention is given to the handling limitations of the slurry and to the unique hardware requirements.

Jan 1, 1982

By Irving Cadoff, Kurt Komarek, Edward Miller

Barium can be purified by equilibration with titanium. The melting point of barium was found to be 726.2° i 0.5 °C. The room-temperature lattice parameters of BaTe and Bask are 7.004 * 0.002A and 6.600 * 0.002A. Melting points for BaTe and Base were found to be 1510° * 30°C and 1830° ± 50°C, respectively. HIGH-purity barium and its compounds are difficult to prepare because of the reactivity of barium with the atmosphere and the large heats of formation of the compounds. Purification of barium by vacuum distillation,' and the preparation and properties of barium oxide2 and barium sulfide3 have been reported. However, little has been done on the homologous compounds barium selenide and telluride. PURIFICATION OF BARIUM Distilled barium obtained from King Laboratories was used as the starting material. The analysis supplied with the metal showed the presence of: 0.4 wt pct Sr, 0.001 pct Mg, 0.02 pct F, 0.003 pct Cu, 0.005 pct Na and less than 5 x 10-3 wt pct of any other metallic impurity. Analyses for oxygen and nitrogen were not available. Since there is evidence4 that any barium nitride present in the starting material may decompose on distillation producing nitrogen which can contaminate the distillate, further purification was performed. At elevated temperatures, any nitrogen and oxygen present in barium should be removed by reaction with titanium. Assuming that the solubility of oxygen in liquid barium is negligible near the melting point of barium, any oxygen present will be in the form of BaO. Removal of oxygen from molten barium is expressed by the equation: BaO(S)+ TixOy(S) = Ba(l)+ TixO(y+1)(s) where Ti,Oy and TixO(y+1) are solid solutions of oxygen in titanium. At 1000°C, the change in free energy for this reaction is negative for (y+1)/x +y+1) x (100) 17.5 at. pct O.5 Since reaction with commercially pure titanium (containing 0.07 wt pct oxygen) results in a free energy change for the reaction of -19 kcal per g-atom, slight solubility of oxygen in barium would not hinder the oxygen removal. Since comparable thermodynamic data are not available to permit calculation of the partition of nitrogen between liquid barium and titanium, a similar quantitative relationship cannot be obtained. However, on the basis of work by Kubaschewski and Dench,5 complete removal of nitrogen from liquid barium can be expected. Since the melting point of barium is depressed markedly by small additions of nitrogen,' the change in melting point during reaction of barium with titanium was used to follow the purification reaction. MELTING POINT OF BARIUM A 50-g sample of barium was sealed by arc welding under argon into an all titanium crucible provided with a thermocouple well. The melting point of the sample was determined by thermal analysis, using a Pt/Pt-10 pct Rh thermocouple which was calibrated according to National Bureau of Standards specification6. The crucible was then heated for 48 hr at 950°C in vacuum and the melting point redetermined. This procedure was repeated until three successive thermal analyses agreed within ±0.5oC, the limits of error of the analysis. The melting point increased from an initial value of 720.0°C to a final value of 726.2°C. Analysis on samples quenched from 950°C gave a solubility value of 0.004 wt. pct Ti. Assuming that the titanium-barium phase diagram is similar to those of titanium-magnesium7 and titanium-calcium,8 the solubility of titanium in liquid barium decreases with decreasing temperature. Therefore, the solubility of titanium in liquid barium should be less than 0.004 wt. pctat the melting point (726oC), and the effect of dissolved titanium on the melting point would be negligible. Addition of up to 3 wt pct Sr does not significantly change the melting point of barium,7 so that the effect of the 0.4 wt pct Sr in the starting material will also be negligible. The value of 726.2" ± 0.5C obtained for the melting point of barium can be compared .with a determination carried out by Keller and coworkers in low-carbon steel crucibles,' who obtained a value of 725± 1C, using barium purified by fractional distillation. The higher value obtained in the present investigation is indicative of the effectiveness of titanium in removing traces of nitrogen. PREPARATION OF BaTe AND Base The compounds were prepared by direct reaction

Jan 1, 1961

By J. G. Bradley

On February 1, 1971, United States Steel Corporation, Lorain Works began operation of its first BOP facility equipped with a partial combustion gas cleaning system.- This shop consists of two 220 ton vessels. Figure I schematically describes this partial combustion gas cleaning system and highlights the necessary features for it-s safe and efficient operation. Waste gases are drawn into the membrane hood by a 2250 H.P. induced draft fan and are first quenched by the six inch bull nozzle at the top of the hood. Larger solid particles are separated from the gas in the quencher venturi and final scrubbing takes place in the P-A high energy venturi scrubber before the cleaned waste gas is burned in the flare stack. Scrubbing water is routed through a cyclone separator and then cycled into one of two 100' diameter thickeners. Underflow sludge which averages 20% solids is dewatered by 100 H.P. centrifuges. The clear overflow from the thickeners is recycled first to the P-A venturi and then to the quencher before returning to the thickeners.

Jan 1, 1972

By R. W. Nelson

Methods for determining permeability presented by W. D. Kruger3 in a paper entitled "Determining Areal Permeability Distribution by Calculation" have considerable merit. They can be expected to contribute significantly to analysis of flow in heterogeneous systems. Some rather subtle yet important conditions must be met, however, to assure that the computed permeabilities are correct. The conditions which insure a unique permeability distribution may have been overlooked in the method as proposed and presented in the subject paper. The subtlety of the special requirements may permit good agreement between computed and measured pressures in the reservoir; but the computed permeability may still be in error. The general theory and discussion of the requirements for a unique determination of the permeability distribution are presented elsewhere in more detail.7'8 Accordingly, only major features will be presented here in the notation of Kruger. GENERAL DESCRIPTION OF REQUIREMENTS A brief mention of the route to be followed in showing the special requirements may be helpful. The equation to be solved is a quasilinear, first-order, partial differential equation in the unknown permeability. This equation can be solved through an extension of Lagrange's method by reduction to a system of subsidiary ordinary differential equations. Through consideration of the identity of one of the Lagrange subsidiary differential equations with the stream function, a special interrelationship can be shown. The interrelationship has special significance with respect to the boundary condition. If the boundary function satisfies part of the subsidiary differential equation, no unique solution for the permeability distribution exists. In the physical problem this requirement for uniqueness indicates that the permeability measurements used as a boundary condition can not be along a stream tube. The boundary condition must be along a line, or series of lines, which completely traverse the region and pass through every stream tube.

By John Garcia

IN some districts of the bituminous coal field the problem of construct-ing bulkheads to seal off water under pressure is becoming increasingly important. Recently this matter has been brought very much to the front by the loss of a large. Illinois mine due to failure of a bulkhead that separated it from several old, flooded mines. As this great misfortune has provoked much inquiry about proper bulkhead design, it is felt that a description of the successful and extensive water-sealing practice at three mines that have different natural conditions will be of considerable interest to those connected with properties having a present or future water problem and to engineers that may have to design safe bulkheads of economical construction. These three mines are the Saxton acid Dresser, near Terre Haute, Ind., and the Hegeler, near Danville, 111. All three have water conditions that make it necessary to regularly seal off till worked-out sections of the mine, and there are considerably over a hundred bulkheads in each. As far as the writers know, these three mines are the only ones in the bitu-minous coal fields of the United States with anything like so large a number of water seals and experience, although a number of other mines are known to have a few bulkheads. More detail will he included herein on the Saxton mine than on the others, as the writers are more familiar with it.

Jan 1, 1937

By L. F. Bryant, J. P. Hirth, R. Speiser

The surface, gain boundary, and twin boundary energies, as well as the surface diffusion coefficient, of cobalt were determined from tests at 1354°C in pure hydrogen. A value of 1970 ergs per sq cm was calculated for the surface energy, using the zero creep method. It was possible to measure the creep strains at room temperature because the phase transformation was accompanied by negligible irreversible strain and no kinking. Established techniques based on interference microscopy were used to obtain values for the other three properties. The gain boundary and twin boundary energies were 650 ad 12.7 ergs per sq cm, respectively, while a value of 2.75 x l0 sq cm per sec was determined for the surface dufusion coefficient. In the course of a general study of cobalt and cobalt-base alloys, information was required about the surface energy of cobalt. Hence, the present program was undertaken to measure the interfacial free energy, or, briefly, the surface energy, of the solid-vapor interface of cobalt. The microcreep method was selected for this measurement because other surface properties could also be determined from the accompanying thermal grooving at grain boundaries and twin boundaries. A brief summary of the methods for determining the various surface properties follows. At very high temperatures and under applied stresses too small to initiate slip, small-diameter wires will change in length by the process of diffu-sional creep described by Herring.1 The wires acquire the familiar bamboo structure and increase or decrease in length in direct proportion to the net force on the specimen. For a specimen experiencing a zero creep rate, the applied load, wo, necessary to offset the effects of the surface energy, y,, and grain boundary energy, y b, is given by the relation: where r is the wire radius and n is the number of grains per unit length of wire. The first results obtained from wire specimens were reported by Udin, Shaler, and Wulff.' udin3 later corrected these results for the effect of grain boundary energy. The grain boundary energy is determined from measurements of the dihedral angle 8 of the groove which develops by thermal etching at the grain boundary-free surface junction. For an equilibrium configuration: Measurements of the angle 8 can be made on the creep specimens4'5 or on sheet material, as was done in this investigation by a method employing interference microscopy.= If the vapor pressure is low, the rate at which grain boundary grooves widen is determined primarily by surface diffusion and, to a lesser extent, by bulk diffusion. The surface diffusion coefficient, D,, is obtained from interferometric measurements of the groove width as a function of the annealing time, t. As predicted by Mullins~ and verified by experiment, the distance, w,, between the maxima of the humps formed on either side of the grain boundary increases in proportion to if grooving proceeds by surface diffusion alone. For this case: where fl is the atomic volume and n is the number of atoms per square centimeter of surface. When volume diffusion also contributes to the widening, the surface diffusion contribution can be extracted from the data by the method described by Mullins and shewmon.8 Where a pair of twin boundaries intersects a free surface, a groove with an included angle of A + B (using the groove figure and notations of Robertson and shewmong) forms by thermal etching at one twin boundary-free surface junction. If the "torque terms", i.e., the terms in the Herring10 equations describing the orientation dependence of the surface energy, are sufficiently large, an "inverted groove" with an included angle of 360 deg-A'-B' develops at the other intersection. The angles A + B and A' + B' are measured interferometrically. When the angle, , between the twinning plane and the macroscopic surface plane is near 90 deg, the twin boundary energy is calculated from the relation: 1) EXPERIMENTAL TECHNIQUES Five-mil-diam wire containing 56 parts per million impurities was used for making ten creep specimens. These specimens had about 15 mm gage lengths with appended loops of wire and carried loads (the specimen weight below the midpoint of the gage length) ranging from 3.7 to 149.8 mg. The wires were hung inside a can made from 99.6 pct pure cobalt sheet. Beneath the wires were placed small specimens of 20-mil-thick, 99.9982 pct pure cobalt sheet from which the relative twin boundary and grain boundary energies and the surface diffusion coefficient were measured. All the specimens were annealed at a temperature of 1354" i 3°C which is 92 pct of the absolute melting point of cobalt. The furnace atmosphere was 99.9 pct pure hydrogen that was purified further by a Deoxo catalytic unit, magnesium perchlorate, and a liquid-nitrogen cold trap. As a precautionary measure the gas was then passed through titanium alloy turnings which were heated to 280" to 420°C and replaced after every test period. The hydrogen was maintained at a

Jan 1, 1969

By John D. Kalasky

The success in providing adequate ventilation to the active faces of a coal mine for all methods of mining depends upon good face control and the air distribution and control system. A good system provides overcasts, air locks, regulators and bleeders so that an adequate flow of air will be confined to the working places with least opportunity for interruption, and that a flow of air is maintained, however small, across the worked out area to the bleeder and away from men and equipment at all times. In gaseous mines, it is just as important to satisfy effective bleeding as it is to satisfy the air volume requirements in the operating splits. The two requirements go hand in hand. Although not complicated, ventilation and methane drainage in longwall mining in a gaseous mine require careful forethought and adequate facilities to make them safe.

Jan 8, 1966

By F. B. Plummer

PROGRESS during 1940 in oil-production technology has been confined largely to a steady advancement in practices inaugurated in previous years, rather than the introduction of any new startling process or technique. The usual changes, improvements and additions in production equipment have been introduced. An increased attention to, and interest in, research has been noteworthy, resulting in improved efficiency in operation of oil wells. control, utilization of reservoir energies and reduction of production costs.

Jan 1, 1941

By R. S. Dean. J. R. Long T. R. Graham, Roberson A. H., Armantrout C. E.

The general program of the Federal Bureau of Mines on the study of alloys made with electrolytic manganese has been extended to copper-manganese-aluminum alloys. The initial results of the work are presented in this report and concern a determination of the mutual solubilities of these three metals to form the alpha solid solution. The principal studies of this system, reported in the literature, have been focused on the Heusler alloys containing ro to 30 per cent Mn with 9 to 15 per cent Al. These investigations concern the ferromagnetic properties and the determination of the crystallization contours, with little emphasis on the phases present in the solid state outside of this area. Heuslerl recognized a breakdown of the beta solid solution of the magnetic alloy, which he says decomposes into the alpha, beta, and gamma phases of the copper-aluminum system, somewhat modified by the presence of manganese. Rosenhain and Lantsberry2 examined alloys ranging up to 10 per cent Mn and 10 per cent A1 but were unable to reach definite conclusions concerning the phase boundaries in that area. Krings and Ostmann3 made magnetic studies and examined the system by thermal analysis. They present contours of the liquidus surface but do not place any of the phase boundaries. Corson4 has drawn a hypothetical boundary for the alpha field with few, data to support such construction. The binary systems involved have rcceived considerable attention by numerous investigators, and their general features are well established. The copper-ahminum system (Fig. I) has been thoroughly examined by Stockdale,5 who places the limit of solubility of aluminum in copper at 7.4 per cent at the liquidus and 9.5 per cent at room temperature. Smith6 established the eutectoid temperature at 570°C. by a study of isothermal decomposition of the beta phase. The copper-manganese system (Fig' ') has been recently reviewed by Dean and CO-WorkersS.7 Using high-purity alloys,

Jan 1, 1947

By Armantrout C. E., R. S. Dean. J. R. Long T. R. Graham, Roberson A. H.

The general program of the Federal Bureau of Mines on the study of alloys made with electrolytic manganese has been extended to copper-manganese-aluminum alloys. The initial results of the work are presented in this report and concern a determination of the mutual solubilities of these three metals to form the alpha solid solution. The principal studies of this system, reported in the literature, have been focused on the Heusler alloys containing ro to 30 per cent Mn with 9 to 15 per cent Al. These investigations concern the ferromagnetic properties and the determination of the crystallization contours, with little emphasis on the phases present in the solid state outside of this area. Heuslerl recognized a breakdown of the beta solid solution of the magnetic alloy, which he says decomposes into the alpha, beta, and gamma phases of the copper-aluminum system, somewhat modified by the presence of manganese. Rosenhain and Lantsberry2 examined alloys ranging up to 10 per cent Mn and 10 per cent A1 but were unable to reach definite conclusions concerning the phase boundaries in that area. Krings and Ostmann3 made magnetic studies and examined the system by thermal analysis. They present contours of the liquidus surface but do not place any of the phase boundaries. Corson4 has drawn a hypothetical boundary for the alpha field with few, data to support such construction. The binary systems involved have rcceived considerable attention by numerous investigators, and their general features are well established. The copper-ahminum system (Fig. I) has been thoroughly examined by Stockdale,5 who places the limit of solubility of aluminum in copper at 7.4 per cent at the liquidus and 9.5 per cent at room temperature. Smith6 established the eutectoid temperature at 570°C. by a study of isothermal decomposition of the beta phase. The copper-manganese system (Fig' ') has been recently reviewed by Dean and CO-WorkersS.7 Using high-purity alloys,

Jan 1, 1947

Prof. H. O. Hofman, Massachusetts Institute of Technology, Boston, Mass. (communication to the Secretary): When Mr. Stetefeldt quotes me as saying that " silver-assays are uniformly made by scorification," he has evidently not understood that I was referring solely to the practice of silver-lead smelting-works. Everybody knows that silver-mills do not employ the scorification-assay for regular work ; and it is equally certain that in very few, if any, silver-lead smelting-works will the crucible-assay be found in use for determining silver. The second part of the quotation, "as it is adapted to all kinds of ores and gives excellent results unless organic matter is present," although, of course, also intended in a restricted sense, might very well be extended to a general one. Mr. Furman, in his Manual of Practical Assaying,* says, on page 123: "We believe that the Colorado practice is preferable, as most ores will yield higher silver-results by scorification." The fact that the scorification-assay is the accepted one in Colorado is strong presumptive evidence for its accuracy, as exactness would nowhere else be more jealously demanded. Mr. Stetefeldt cites Albert Arents- as a supporter of his preference for the crucible-assay, although I had already done so in favor of scorification. Looking up again the reference, I find that I was justified in quoting him, as, while Mr. Arents advocates the crucibleassay for low-grade gold ores, not on account of the greater accuracy of its results, but because it is quicker and less expensive, he condemns it§ for the assay of silver-ores, and prefers the scorifier for rich goldores, and for coppery ores, and in general for ores containing both silver and gold. As I, like Mr. Stetefeldt, have kept no detailed

Jan 1, 1895

By E. I. Larsen, E. F. Swazy, F. R. Hensel

Experience has indicated that hard bronzes are not suitable for bearing applications where high bearing loads and speeds are involved. It is the general practice to utilize softer materials for these purposes, such as copper, lead, silver, babbitt, lead-base alloys, and more recently aluminum-base alloys, preferably supported by a steel backing. It was the objective of the present investigation to study a new material produced by powder metallurgical methods susceptible to precipitation-hardening. Test MAteriaIs Preliminary tests were made with compacts containing copper, nickel and silicon in quantities sufficient to form 3 to 5 per cent nickel silicide. It mas found that this type of alloy was susceptible to the formation of a soft surface shell when sintered in tank hydrogen. The depth of the shell depended On the length of sintering time and sintering temperature, and varied in thickness from a few thousandths to as much as One eighth inch. This soft shell resulted from the preferential oxidation of silicon, thereby reducing the efficiency of age-hardening by the nickel silicide compound. The body of the sintered compacts below the soft shell could be precipitation-hardened to a hardness of 70 to 85 Rockwell B, by quenching from goo°C. and age-hardening at 450°C. A series of tests was made with various addition agents, in order to decrease the rate of preferential oxidation, and it was found that phosphorus was most beneficial in this respect. After considerable experimentation, the following nominal com-position was accepted as standard: 2.4 per cent nickel; 0.8 silicon; 0.3 phosphorus; balance copper. The physical propertties and certain bearing properties of this alloy are described in the present paper Preparation of Compacts Several methods of incorporating the hardening ingredient (nickel silicide) were studied. Compacts formed from copper, nickel and silicon powders were found to be inferior to those fabricated from prealloyed nickel silicide master alloys, because of the rapid oxidation of pure silicon during sintering. The use of a prealloyed nickel silicide hardener containing 25 per cent silicon and 75 per cent nickel could be further improved by preparing a master alloy, incorporating nickel, silicon, phosphorus and copper, having the following nominal composition~ 25 per cent nickel; 7 silicon; 3 phosphorus 64 copper. This alloy is brittle in the cast condition and can be readily powdered. Sintering Procedure The blended powders were pressed at '5 to 40 tons per sq' in., the pressure depending on the size and shape of the compacts. Sintering was carried out in hydrogen or cracked ammonia atmospheres at

Jan 1, 1946

By E. I. Larsen, E. F. Swazy, F. R. Hensel

Experience has indicated that hard bronzes are not suitable for bearing applications where high bearing loads and speeds are involved. It is the general practice to utilize softer materials for these purposes, such as copper, lead, silver, babbitt, lead-base alloys, and more recently aluminum-base alloys, preferably supported by a steel backing. It was the objective of the present investigation to study a new material produced by powder metallurgical methods susceptible to precipitation-hardening. Test MAteriaIs Preliminary tests were made with compacts containing copper, nickel and silicon in quantities sufficient to form 3 to 5 per cent nickel silicide. It mas found that this type of alloy was susceptible to the formation of a soft surface shell when sintered in tank hydrogen. The depth of the shell depended On the length of sintering time and sintering temperature, and varied in thickness from a few thousandths to as much as One eighth inch. This soft shell resulted from the preferential oxidation of silicon, thereby reducing the efficiency of age-hardening by the nickel silicide compound. The body of the sintered compacts below the soft shell could be precipitation-hardened to a hardness of 70 to 85 Rockwell B, by quenching from goo°C. and age-hardening at 450°C. A series of tests was made with various addition agents, in order to decrease the rate of preferential oxidation, and it was found that phosphorus was most beneficial in this respect. After considerable experimentation, the following nominal com-position was accepted as standard: 2.4 per cent nickel; 0.8 silicon; 0.3 phosphorus; balance copper. The physical propertties and certain bearing properties of this alloy are described in the present paper Preparation of Compacts Several methods of incorporating the hardening ingredient (nickel silicide) were studied. Compacts formed from copper, nickel and silicon powders were found to be inferior to those fabricated from prealloyed nickel silicide master alloys, because of the rapid oxidation of pure silicon during sintering. The use of a prealloyed nickel silicide hardener containing 25 per cent silicon and 75 per cent nickel could be further improved by preparing a master alloy, incorporating nickel, silicon, phosphorus and copper, having the following nominal composition~ 25 per cent nickel; 7 silicon; 3 phosphorus 64 copper. This alloy is brittle in the cast condition and can be readily powdered. Sintering Procedure The blended powders were pressed at '5 to 40 tons per sq' in., the pressure depending on the size and shape of the compacts. Sintering was carried out in hydrogen or cracked ammonia atmospheres at

Jan 1, 1946

The following is an incomplete list of members and guests who called at Institute headquarters during the period Dec. 10, 1918 to Jan. 10, 1919. P. G. Bandy, Mexico City. Wm. B. McKinley, Yonkers, N. Y. Bennett R. Bates, Berkeley, Cal. Captain C. E. McQuigg, Conn. William T. Bates, Mascot, Tenn. Lt. H. G. Mathews, Cal. Lt. Don C. Billick, Alturas, Cal. Lt. M. S. Mazany, Mich. L. E. Booth, Watertown, Mass. Ralph A. Meyer, Hill City, S. D. J. T. Boyd, Denver, Colo. C. F. Moore, Boston, Mass. J. R. Buchanan, Pasadena, Cal. H. W. Nichols, Chicago, Ill. Ensign G. M. Burke. R. B. Olsen, Mays Landing, N. J. Captain E. H. Clausen. M. L. O'Neale, Gouverneur, N. Y. F. L. Cole, Manila; P. I. F. W. Osborn, New York, N. Y. Joules Cousin. Lt. Fred S. Porter, Alaska. A. Faison Dixon, Washington, D. C. G. M. Richards, Palmerton, Pa. James T. Dixon, London, England. T. C. Roberts, E. Orange, N. J. Everett Drennen, Elkins, W. Va. W. E. Ruder, Schenectady, N. Y. F. Eichelberger, Helena, Mont. Ensign W. A. RuKeyser, Boston. R. B. Eldredge, Colorado Springs, Colo. A. H. Sawyer, Boston, Mass W. F. Ferrier, Ottawa. Lt. D. F. Schindler, New York. Martin Fishback, Benson, Ariz. L. G. Sparks, Greenshurg, Kan. T. E. Fisher, Dover, N. J. W. H. Staver, New York N. Y. D. C. Gilbert, Ft. Wayne, Ind. Douglas B. Sterrett, St. Cyr, Canada. Lt. Lauriston B. Herr, Cuba. Warren D. Thompson. G. S. Holmquist, Washington, D. C. Enrique Touceda, Albany, N. Y. Lt. E. Ross Housholder, Ohio. Mathew van Siclen. Hugh C. Ingle, Santa Rosa, Cal. Flying Cadet Christian Vrang, Cal. Lt. M. W. Kishman, Ariz. L. G. Weeks, Bisbee, Ariz. Hugo E. Koch, Watertown, Mass. C. E. Wheelock, Mogollon, N. M. H. M. LaFollette, LaFollette, Tenn. Major A. E. White, Washington, D. C. Clinton R. Lewis, Dawson, Y. T. Lt. J. L. White, Humboldt, Ariz. The Secretary of the Institute has received with sincere appreciation a Christmas card extending the season's greetings from the officers' mess of the 3d Tunnelling Company, Canadian Engineers, B. E. F., France, and takes this means of reciprocating to these officers and men of the company the best wishes of the members of the Board of Directors. Charles E. Addams has removed from Ray, Ariz., to Phoenix, Ariz., where he is chairman and director of the Arizona State Council of Defense.

Jan 2, 1919

By Roscoe C. Clark, Henry F. Coffer, J. J. Reynolds

A cement slurry lightweight additive has been adapted in the Conoco laboratories for use in oil well cements. This additive makes possible the use of air to lighten oil well cement slurries. Specifically, the additive consists of small clay bubbles of air having sufficient strength to resist crushing by bottom hole pressures. Clay bubble cement slurry weights can be safely reduced to 10 Ibs/gal. In addition, the clay bubbles tend to act as lost circulation materials and to provide a cement texture which should produce good perforating characteristics. Clay bubble cement is relatively impermeable. INTRODUCTION In many areas in Oklahoma, Texas, Wyoming, and California, difficulties are experienced during casing cementing operations with lost returns caused by the high density of the cement slurries. Wells in these areas are ordinarily drilled with 9 to 11 lbs/gal. drilling mud while neat cement slurries may range in densities from 14.5 to 17 lbs/gal. In these areas, cement slurry weights are at present being successfully reduced to around 12 lbs/gal. (under bottom-hole conditions) by the use of additives in the cement. Since the use of additives will decrease the strength which the cement will develop, the amount of additives which can be used must be based on the minimum cement strength which is acceptable; and thus the maximum slurry weight can be reduced. At present, the minimum tensile strength generally acceptable is 50 lbs/sq in. cured for 24 hours under bottom-hole temperature. This figure is based on laboratory tests1 and on a large number of cement jobs which have been conducted using cement which will not develop more than 50 psi tensile strength in 24 hours under bottom-hole conditions. Two additives are now in use for decreasing cement slurry weights. These are expanded perlite and/or bentonite. The density of both of these materials is greater than that of the cement slurry; however, large quantities of water may be added with these materials without producing a slurry which will settle out of suspension. It is these large quantities of water which contribute to the reduction in the slurry weight. The minimum slurry weight at present obtainable with expanded perlite and/or bentonite is approximately 12 lbs/gal. using a standard Portland cement slurry. In many areas, this weight reduction is insufficient; and returns are still lost during casing cementing operations. In many cases, the pay formation itself is fractured; and a considerable quantity of this cement is lost to the pay zone. It is therefore believed that if cement slurry weights can be reduced to as low as 10 lbs/gal., two advantages will accrue: 1. The lighter densities (10 to 12 lbs/gal.) should mitigate or eliminate lost returns during casing cementing operations. 2. Cement slurries above 12 Ibs/gal. (the present minimum limit ) should develop considerably more strength than is now being obtained. A tensile strength of 100 psi is desirable.' It is the object of this paper to describe a cement slurry having a weight of 10 lbs/gal. and capable of

Jan 1, 1955

By C. J. Leith

A study of the effect of rock composition, rock structure and degree of weathering on the stability of cut slopes is being sponsored jointly by the U.S. Bureau of Public Roads and the North Carolina Highway Commission. In 58 mountain and piedmont counties of North Carolina the percentage of failed cut slopes is greatest in micaceous metasediments, gneisses, and schists, and in saprolite and soil derived from these rock types. Soil slope failures outnumber rock slope failures by two to one. Joints and similar planes of separation exert a strong influence on size and shape of the sliding mass. They may or may not act as failure surfaces, depending on their orientation with respect to the active forces. Climatological data, though indicative of weathering conditions, do not correlate well with slope failure frequency. Because of the presence of joints and similar planes of weakness in soil and rock materials, conventional methods for analyzing slope stabilities are not directly applicable. Empirically derived modifications of these methods are being investigated. A study of the stability of highway cut slopes, sponsored by the U. S. Bureau of Public Roads and the North Carolina State Highway Commission, began in 1962 at North Carolina State of the University of North Carolina at Raleigh. As part of this study all slides, rockfalls and other types of cut slope failures on Federal and State highways in the 58 mountain and piedmont counties in North Carolina were located and described, and the data catalogued in a punched card file system. A major objective of the project is to relate slope failures to properties and physical conditions of the geological units in which the slopes were constructed, and to correlate soil type and/or geological unit with type and frequency of slope failure. The complexities of the problem of slope stability and the limitations which these complexities impose on methods for analyzing slopes have been recognized for many years. A great variety of factors and processes may lead to slides, often making it almost impossible to analyze theoretically the conditions required for stability of slopes. One of the principal factors determining maximum safe slopes is the shear strength of the material in which the slopes are cut, but unfortunately there are very few data available concerning shear strengths of residual soils. Vargasl tested clay derived from gneiss and granite in southern Brazil; the properties of decomposed granite occurring near Hong Kong were determined by Lumb.2 These data are being used, when applicable, to supplement the test data obtained in the present study by Yorke.3 The locations of the North Carolina slope failures, more than 400 in number, are shown on Fig. 1. This map, adapted from the Geological Map of North Carolina,4 suggests the possibility of a relationship between frequency of slide occurrence and rock type. However, the evaluation of this possibility requires consideration not only of the type of rock, but also of its large and small scale structural features, its susceptibility to and degree of weathering, and the composition and structure of the weathering products. Soil slope failures in thoroughly weathered soil material and saprolite outnumber rock slope failures two to one. INFLUENCE OF ROCK TYPE The agricultural soil type involved in each soil slope failure was identified and each failure was catalogued in terms of the parent material from which the soil was derived. These data indicate that most of the slope failures, whether in the rock or in the derived soil, are associated with metamorphic rocks (see Fig. 2a). The data may be skewed somewhat because of the relative sizes of the total areas underlain by the various rock types, but Leith and Gupton5 have demonstrated that the preponderance of failures in metamorphic rocks is of much greater magnitude than could be accounted for by the areal factor alone. The dominance of metamorphic rocks is emphasized when soil slope failures are considered in terms of the specific rock types from which the soils were derived (see Fig. 2b). In particular, mica schists and mica gneisses account for more slides

Jan 1, 1965

By R. M. Wilhelm

HIGH-TEMPERATURE thermometry,, as treated in this paper, deals with the measurement of temperature in the range 100° to 550° C. The lower limit corresponds to the temperature of boiling water at normal atmospheric pressure, the upper limit is approximately the highest temperature to which mercury in a glass thermometer may be safely subjected.1 In this range., the domains of pyrometry and thermometry overlap somewhat, for high-temperature resistance thermometers and thermocouples generally classed as pyrometers are often used below 550° C. This paper will be confined to high-temperature mercurial thermometers, and indicating and recording thermometers of the vapor pressure, liquid or gas filled, and bimetallic or graphite-metal expansion types, a classification of which is as follows: CLASSIFICATION OF THERMOMETERS GENERAL CLASSIFICATION SUBDIVISIONS Mercury in glass Laboratory- Etched or engraved stems (mercurial) Enclosed scale (Einschlus) Industrial Vapor pressure Indicating and Pressure Liquid filled recording Gas filled Bimetallic Graphite-metal expansion

Jan 9, 1919