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(Butte Meeting, August, 1913.) IN metallurgical circle it is. known widely, but somewhat vaguely, that the ease of reduction of metallic .oxides. depends largely on the way they have been prepared. It is likewise known that. different forms of carbon have different and greatly varying reducing powers. It is the purpose of, this paper to show somewhat more definitely and scientifically these facts. Sonic years ago the writer published an account of pyrometric determinations of the reduction temperature of zinc oxides variously prepared and of several kinds.1 In said paper it was shown that the temperature at which zinc oxide evolves zinc according to the equation, ZnO+C? Zn+CO depends upon the nature of -the two reacting bodies. The determinations bad a range of accuracy of from 2°to 6°C.,whereas differences were found to, amount to an extreme of 90° C. So the differences are real ones and must have a definite cause. The equation of boiling water, (H2 O)4 = 4 (H20) has a fixed temperature for? equilibrium of 100° C. at 760 mm. pressure. In general, all equations reacting in the liquid or the gaseous phase have well-defined constant physical conditions which govern the equilibrium point and reaction velocities.

Jan 7, 1913

In situ mining techniques have become prominent in recent years due to declining ore grades, rising costs, and increasing concern for miners' health and safety. Current practices depend heavily on the effective and uniform fragmentation of the ore zone of interest, which not only provides for proper media flow but also exposes additional surface areas to react with the processing system. Specifically, current applications have focused on blasting to a mined-out opening or, in the case of shallow de- posits, blasting to the surface void. In the former case, several obstacles are encountered, including proper initiation, uniform fragmentation, and a lack of swell space for the blast, which tend to produce less desirable results in the zone of' interest.

Jan 3, 1979

By Teh-Yu Kao, Don J. Wood

With the increasing industrial use of the method of transporting solids by fluids through pipes, a better understanding of the basic mechanics of a solid-liquid pipe flow system is essential. In this study the phenomenon of incipient motion of solid particles resting in a sediment bed on the bottom of a pipe is investigated. Since a system would fail to operate at the designed solid-liquid flow condition if it was not capable of operating through the transient initial flow phase, information concerning the starting transient is of great interest. An objective definition of incipient particle motion, derived from energy considerations, is first proposed. Using this the critical state is defined to describe the flow condition during which a solid particle can at least temporarily escape the sediment bed and move in the liquid. Postulated also in this study is that the condition of incipient motion can be reasonably well predicted by a consideration of particle equilibrium in a direction normal to the pipe axis. The incipient condition is considered to occur at the instant the force between the bed and the particle, normal to the pipe axis, is zero. Experimental measurements of incipient conditions are obtained for water flowing through a horizontal pipe with sand sediment beds of different thickness. These are compared to predicted values with good agreement.

Jan 1, 1975

By R. F. Sheldon

Largest uranium deposit in the Northwest is Dawn Mining Co.'s Midnite mine on the Spokane Indian Reservation. The orebodies lie along the contact of granite and metamorphosed sedimentary rock and are controlled by faults and shear zones near the granite contact. In the oxidized zone the deposits consist mainly of the secondary uranium mineral meta-autunite; sooty uraninite and primary uranium minerals are known to occur at greater depths. Elevations in the mine area range from 2500 to 3500 ft. The rolling hills and low, rounded mountains are covered with grass and evergreen trees. HISTORY AND DEVELOPMENT Original showings were discovered with a geiger counter in the spring of 1954 by prospectors Jim and John LeBret. High radioactivity in several schist outcrops was found due to scaly coatings of a greenish-yellow, fluorescent mineral, later identified as meta-autunite. Prior to this time autunite was not known to occur in the state of Washington, and no significant uranium deposits had been found in the Pacific Northwest. Outcrops in the area were few, and most of the ground was mantled with 2 to 10 ft of overburden, but three other radioactive zones were discovered by prospecting the ridge southward along the strike of the schist near its contact with granite for three quarters of a mile. Midnite Mines Inc. was formed

Jan 1, 1960

By E. S. Machlin, C. W. Chen

RECENTLY Chen and Machlin' proposed a mechanism for intercrystalline cracking in metals during high-temperature stressing. According to this mechanism the formation of voids at grain boundaries is primarily responsible for intercrystalline cracking. A model has been provided to demonstrate the initiation of submicroscopic cracks and voids at jogs of grain boundaries where grain boundary sliding is inhibited. Submicroscopic cracks can grow as a result of either further grain boundary sliding or localized tensile stress. In the former case, it is believed that grain boundary sliding produces more voids which link together to produce macroscopic cracks and which may lead to the eventual failure of the metal. Concurrently, Nield and Quarrell2 reported their interesting results obtained in a systematic investigation of intercrystalline cracking in two aluminum alloys under various creep conditions. Their observations are generally in agreement with the above mechanism, especially the conclusion that voids are formed as a direct consequence of grain boundary sliding. On the basis of the volume fraction occupied by voids, they could find no confirmation of vacancy condensation as the mechanism for void growth. Furthermore, an important feature of intercrystalline cracking has been likewise pointed out by them that the majority of cracks are not formed at grain corners. Nield and Quarrel1 meanwhile emphasized the importance of grain boundary migration by designating it as one of two main processes operative in the mechanism of crack formation during creep. The designation seems unnecessary because overemphasis of grain boundary migration only complicates the mechanism of void formation. There are two reasons which militate against the inclusion of grain boundary migration in the mechanism of void formation. In the first place, the formation of intercrystalline voids per se does not require grain boundary migration. Secondly, in addition to grain boundary migration, void formation may be minimized by any other process such as plastic deformation which is capable of relieving localized stresses around jogs. Chang and Grant3 have shown that intercrystalline cracking is prevented in aluminum by lattice bending in high stress regions. The influential role played by grain boundary migration in creep has also been realized in our studies. In several cases, voids did not appear at all in grain boundaries whenever grain boundary migration took place prominently during creep. The purpose of this paper is to discuss the effect of grain boundary migration on the formation of intercrystalline voids and other related rupture properties. Experimental evidence indicates that in an unstable grain structure void formation may be markedly modified by structural changes. The abnormally high ductility and the transcrystalline mode of fracture observed in copper at elevated temperatures reveals that effective grain boundary migration minimizes void formation. Grain boundary migration has long been known as a common high-temperature phenomenon in metals with the grain configuration in a nonequilibrium state. Its effect on ductility and mode of fracture has not been recognized until recently.4 Since the introduction of the term "Equicohesive Temperature," the conventional belief has been that below the equicohesive temperature the ductility of metals increases moderately with decreasing temperature until the ductile-to-brittle transition temperature of fracture is reached. In this temperature range, metals fracture in a ductile mode with a "cup-and-cone" fracture surface. Above the equicohesive temperature, ductility remains invariably low and decreases slightly with increasing temperature. The mode of fracture is strictly brittle and intercrystalline. Typical examples have been shown for a brass and copper in Fig. 1 and 9, respectively, in the paper by Greenwood, Miller, and Suiter.5 The observation in the upper temperature range that ductility of metals is low and insensitive to temperature may be explained in terms of void formation at grain boundaries. It is also in accordance with the findings of McLean6 and Fazen, Sherby, and Dorn7

Jan 1, 1961

By D. E. Furman

The thermal coefficients of linear expansion for several stainless steels have been determined over the temperature range from —300° to 1000°F. The steels studied include types 301, 304, 316, 347, 310 and 330. This wide selection of compositions allows an insight into the effects of austenite stability and alloy content on the expansion characteristics. THE recent increased use of materials in low temperature applications has created a field for which the properties of austenitic iron, chromium, nickel alloys are particularly suited. Tensile and impact values of stainless steels at subzero temperatures have been made available in the technical literature but, as yet, little information has been published with respect to expansion characteristics. In order to supply this need, a study was made of several of the more common compositions. Those selected were types 301, 304, 316, 347, 310 and 330 stainless steel. Both the mean and instantaneous coefficients of linear expansion were determined over the temperature range from —300°F to 1000°F. Procedure The materials used were commercial grades with the exception of type 301 which was made in a 10# high frequency furnace. The compositions are listed in table I. All steels were given an anneal at 1950°F for 30 min and water quenched prior to machining the expansion specimens. Expansion readings were taken on specimens 0.250 in. in diam by 4.000 in. long with a fused quartz tube expansion apparatus similar to that described by Hidnert and Souder.1 Temperature measurements were made with a chromel-alurnel thermocouple calibrated for use at subzero temperatures. A bath of propane was used for temperatures from —300° to —100°F and one of alcohol from —100°F to room temperature. These baths were contained in large mouthed Dewar flasks and cooled to the desired temperature levels by passing liquid nitrogen through glass cooling coils placed in the flasks. The baths were stirred constantly for temperature equalization and were heated by immersing metal rods which were replaced frequently enough to give a heating rate of approximately 150°F per hr. A resistance wound furnace was used for heating from room temperature to 1000°F and throughout this range rates of about 450°F per hr were maintained. The furnace was designed so that the temperature gradient over the specimen was within 5°F. In most instances, the expansion readings were taken during heating from —300° to +300°F at

Jan 1, 1951

By C. S. Smith

The partial persistence of grain size and grain shape on melting and resolidifying crystalline substances, as well as the general effects of pre-solidifi-cation and of superheating on nuclea-tion rate, have been attributed to the presence in the liquid of crystalline impurities bearing some structural relation to the principal solid and hence capable of serving as nuclei for its crystallization. That such lattice matching does sometimes occur is well established, but it is surely improbable that a compound possessing both high-temperature stability and the requisite structural similarity should be naturally available in almost every system. It is now suggested that a mechanism for producing appropriate nuclei exists in the crystallization of all but absolutely pure substances. Impurities can he of many kinds. Some will give rise to compounds that are less soluble in the solid crystal than in the liquid. A . crystal forming from a melt or solution containing these will be supersaturated in some degree, and the foreign atoms will commence to segregate during or after solidification. They do not necessarily form pure, unstrained, crystals of the precipitating compound with its normal composition and structure. Generally—at least in the metallurgical examples that have been most studied —the first recognizable nuclei have lattice coherency with the surrounding matrix and have practically the same crystal structure and lattice spacing as the material in which they form, differ- ing only in composition. An extremely thin oxide layer formed under appropriate conditions on or in a solid metal will tend to be coherent with the metal lattice, and the first few atom layers of the oxide in contact with the metal will differ in both composition and structure from massive crystalliue oxide. It will resemble the metal more closely than the oxide. If it did not subsequently change on melting, such an oxide film would constitute an almost perfect "template" or two-dimensional matrix to hold a few atoms of the primary metal in the exact array needed to form a nucleus for solidification. Any precipitating material will adopt the correct spacing over a few atom diameters, and with appropriate substitution of other atoms of the correct sizes a precipitate can match the parent lattice over large areas of cohererlce without excessive strain. In metals, the componentsof a host of oxides, silicides, borides, nitrides, carbides, sulphides, and other compounds are always present in minute amounts. Some of these will be eliminated because of extreme insolubility in the liquid, while others will remain soluble in the solid; occasionally, however, particles will be formed in the solid by coherent precipitation—not of pure substances, but of whatever assortment of atoms best satisfies the joint requirements of availability, affinity, and appropriate average atom size. Of these, many will disappear on melting, but a few will persist unmelted as little rafts of complex composition, maintaining in the liquid a surface of the exact geometry needed to nucleate the solid on subsequent cooling. Their number and size distribution will determine the resulting grain size; the dimensions of the largest will determine the degree of undercooling that can occur before solidification commences. A similar process may operate in the case of phase transformations in solids. The coherent precipitation of supersaturated minor constituents in a low-temperature phase should facilitate the nucleation of this phase on subsequent cooling after transforming into another phase at higher temperatures. At first sight this hypothesis may seem little different from the older ones. It should therefore be emphasized that it does not depend on chance to provide the right compound to form a nucleus, but postulates that every crystal, containing minute amourlts of any of a wide range of impurities, automatically engenders particles having the correct surface structure to serve as nuclei for subsequent solidification. It could operate in any system, metallic, organic, or inorganic. The suggested mechanism is closely analogous to the production of antibodies from antigens in living organisms—indeed, it was a description of the matrix theory of this process that suggested to the writer its crystalline analogue.

Jan 1, 1950

By M. R. J. Wyllie, H. W. Patnode

In the quantitative interpretation of electric log data it is essential to know the formation factor, defined as the ratio of the resistivity of the formation 100 per cent saturated with brine to the resistivity of the brine.' This concept implies that the formation factor for any given rock is constant irrespective of the resistivity of the brine or solution with which it is saturated. It is apparent that this can be true only when the rock matrix is wholly non-conductive. As reservoir rocks may contain clay or shale having an appreciable conductance one may expect these constituents to influence the determination of true formation factor. The formation factor may be theoretically derived from log data by dividing the resistivity of the mud filtrate invaded formation by the resistivity of the mud filtrate. Such a method of calculntion has implicit in it the assumption that the fluids in the invaded formation are wholly replaced by mud filtrate. that the solid matrix is non-conducting, and that the formation factor of the invaded zone is identical with the formation factor of the uninvaded zone. Since the validity of the first two basic assumptions regarding the insulating character of porous matrices and the displacement of the interstitial fluids in porous media do not appear to be fully established, the formation factors of a number of cores and clay slurries have been measured under conditions suitable for verifying the assumptions and the extent of any errors inherent in them. CORE STUDIES Apparatus and Procedure Resistivity measurements were made on short cylindrical permeable cores which had been previously mounted in lucite.2 The cores were clamped by means of insulated bolts between brass plates about 5 cm square and 1 cm in thickness. The plates were provided with a ring seal to prevent leakage between them and the core mount, and had a centrally located orifice so that fluids could be flowed through the mounted core. The brass mounting plates were used as electrodes and any current flow between them necessarily passed only through the constituents of the intervening core. Fluid saturation of the core, and fluid flow through the core, were effected by a centrifugal pump connected to the outflow end of the core, thus providing a differential pressure across the core of approximately one atmosphere. The procedure used was first to evacuate each core by means of the pump and then to saturate the core with an aqueous sodium chloride solution of known resistivity. The resistance of the core was measured and flow of the solution through the core continued for sufficient time to establish a constant resistance reading. After equilibrium had been reached with one solution, another sodium chloride solution of a different resistivity was flowed through the core and the flow continued until a constant resistance reading was again obtained. This procedure was continued until resistance measurements of the core had been made with a series of solutions within a salinity range from 1.0N NaCl to distilled water. The data obtained enabled the apparent formation factor of given porous rocks when saturated with fluids of different resistivity to be computed and also provided information regarding the ability of an invading fluid to displace interstitial water from a core. Results Berea Sandstone — The first core examined was a specimen of Berea sandstone." This core had been cut essentially parallel to the bedding for permeability studies. The core was clamped in the core holder and saturated with 1.0N NaCl solution and the resistance determined. It was subsequently flushed and the resistance measured when saturated in turn with 0.1N, 0.025N, 0.01N, .005N sodium chloride solutions and finally with distilled water. In flushing the core with each

Jan 1, 1950

By F. R. Wadleigh

It is generally realized and very often admitted by both producers and consumers of coal that there is great need for a revision of existing commercial classifications, and this will involve, of course, determination of a standard classification and a constant revision of marketing practices as they are affected by coal classification. I recently sent out some 200 letters to producers and consumers with a request for their views on the subject of commercial classification. Nearly all of the replies from both sides were that there was needed some change in the present method. There were three or four dissenting voices but the great majority of opinion was in favor of the formulation of some standard commercial classification. The classifications in commercial use today can best be described as a hodgepodge. They are made upon different bases, have different names and have different ways. There are, for instance, about 11 single bases of classifications as used commercially and some 17 or 18 combination bases. Then there were the Tidewater Pool Exchanges. The classification which they put in force is still used in the tidewater markets and has several different bases of its own. It will be considerable of an undertaking to bring about a change in marketing methods as affected by coal classification but it is well worth doing and I think the committee which has been appointed under the auspices of the American Society for Testing Materials realizes the importance of the subject and is on the way to at least bring about some provision for adjusting matters. By way of starting, each member of the Committee on Commercial Classification has been assigned to a general market district and each member is now engaged in collecting the commercial market practice data for submission at the next meeting of the Committee. About a year ago I made up a list of the commercial classifications in the different markets and the total was 171. The 11 single bases I found used in commercial practice were:

Jan 1, 1930

By L. S. Castleman, R. K. Hotzler

We are currently studying the effects on recrys-tallization of impurities diffused into dispersion-hardened alloys. Our interest in this phenomenon was originally aroused by the observation that the recrystallization temperature range of tungsten "doped" with alumina and silica, or with thoria, is lowered drastically if nickel is plated onto the tungsten prior to heat treatment.' In this note, we report a similar effect that sulfur has on the recrystallization behavior of thoriated nickel. The experimental procedure for this exploratory phase of the investigation has consisted simply in heating commercially obtained stress-relieved samples of thoriated nickel for varying temperatures and times in sealed capsules containing air and small quantities of sulfur. The samples contain 2.4 vol pct thoria and initially less than 18 ppm S by weight; they are prepared either from 0.5-in.-ciiam rod stock or from 0.092-in. sheet and are in the "as-received" (stress-relieved) condition prior to exposure. In an atmosphere free of sulfur, such samples do not show evidence of recrystallization after being annealed for 1 hr at a temperature of 2500°F (1372C).2 The photomicrograph in Fig. 1 shows the microstructure of one of our samples annealed for 75 hr at 1000° C (1832°F) in a sulfur-free capsule. The grain structure is hardly evident (if at all) at 465 times magnification. In contrast, the photomicrograph of Fig. 2 shows the recrystallization that has taken place in a sample exposed to sulfur for 5 hr at 1000°C (1832°F). A nickel sulfide phase is visible at the grain boundaries of the light-appearing grains. We have also observed recrystallization to occur in a sample annealed at 600°C (1112°F) for 25 hr. This temperature is below the 637°C (1178°F) eutectic in the Ni-S system. In the latter case, no nickel sulfide phase is evident in the microstructure. Moreover, we have noticed the occur-

Jan 1, 1969

By H. J. Rose

In a paper1 presented before this Institute in 1926,I briefly discussed the evaluation of coking coals by means of ultimate analysis. The paper contained several graphic studies in which coal analyses calculated free of moisture, ash, sulfur and nitrogen were plotted on triaxial diagrams in which carbon + hydrogen + oxygen = 100 per cent. From a study of such data for 600 coking coals of the United States, and 150 coking coals of Wales, France and Germany, it was concluded that it was usually possible to predict coking properties and by-product yields with fair success from ultimate analysis. The coals which have proved exceptions to the general rules were found to have physical peculiarities. Run-of-mine Coal It must not be forgotten that run-of-mine coal is a composite material consisting of many constituents differing in physical properties and chemical analysis. A coal sample usually contains: 1. Glossy black coal known as anthraxylon or vitrain. This constituent usually has the strongest coking properties, and the lowest ash content. 2. Dull black coal consisting of attritus containing thin layers of anthraxylon. It is also known as clarain. This constituent, in a coking coal, usually has good to excellent coking properties. 3. Mineral charcoal or fusain. This is a porous black material which is soft and crumbly (unless impregnated with mineral matter) and which has absolutely no coking properties. It is different in every respect from the other constituents in coal. The volatile matter content of mineral charcoal is less than 20 per cent. even when it is associated with high-volatile coals. As would be expected the hydrogen content is low, and the carbon content is high. 4. A coal sample may contain tough gray canneloid material which has a high-volatile matter and a high hydrogen content, but is poor in coking qualities.

Jan 1, 1930

By V. Lessels, D. J. Buckwalter, D. H. Rose

A cyanide leaching process developed at Michigan Technological University was tested in a 12 to 24 tpd pilot plant. Flowsheet layout and equipment are described. Cyclic operation of leaching, copper precipitation by acidification, and regeneration of the cyanide leaching solution are discussed. Copper extraction and reagent consumption were as predicted by laboratory tests, and the process was proven to be technically feasible. The White Pine Copper Co., a wholly-owned subsidiary of the Copper Range Co., produces copper in the Upper Peninsula of Michigan. Production in 1965 amounted to 138 million pounds of metal. An expansion program now under way will increase this by approximately one half. The highly mechanized room and pillar mine produces 18,000 tons of ore per day, which is treated in a flotation plant. The concentrate is smelted in a reverberatory furnace, the matte is blown in converters to blister copper, and the blister copper is further refined to a uniformly high-quality Lake copper, which is 100% conductive and has a silver content of 25 to 40 oz per ton. The run of the mine ore averages 22.5 lbs of copper per ton with the ore mineral occurring in the form of chalcocite. The nature of the mineralization is such that the sand tailings average a little over 4 lbs of copper per ton. Intensive research has improved copper recovery in the flotation operation to some extent, but at the scale of present operation about 12,000 tons of sands containing over 48,000 lbs of copper go to the tailings pond daily. When the plant expansion is completed, the loss of copper will be somewhat greater. In 1959, the White Pine Copper CO, initiated a study of the recovery of copper in the sand tailings. Inasmuch as the flotation operation was considered to be optimized, a logical approach seemed to be leaching. For various reasons ammonia, ferric chloride, acid, and biological leaching were ruled out as impracticable. This led to a consideration of cyanide leach-

Jan 1, 1968

By Edgar Newhouse

THE lead smeltery at East Helena, Mont., controlled by the American Smelting & Refining Co. since 1899, has been in continuous operation for the past 25 years. Most of the old smelting and roasting practices have been superseded by newer and more modern methods, but on account of the difficulties involved in changing the original construction, some of the methods in use of handling materials are not the most modern. This plant, however, is particularly interesting as being one of the few essentially lead smelteries in the United States. At Federal, Ill., Collinsville, Herculaneum, and possibly other places, similar work is being done, but it is doubtful whether any of them produces as' much lead as the East Helena plant, whose monthly production averages 6,500 tons. The situation, 5 miles east of Helena, is convenient to both the Great Northern and Northern Pacific railroads, while the electric power is obtained from Canyon Ferry, 12 miles east on the Missouri river. Local quarries supply the requisite amount of lime rock, Which the contracts require to be crushed to 5 in. Of the 450 men on the monthly pay roll, a census showed 200 Austrians, 110 Americans, and 30 Italians, the balance being made up of miscellaneous nationalities. The ore supply is mainly derived from the Coeur d'Alêne mines in Idaho, and consists of crude ore, coarse and fine concentrates, middlings, and slimes. About one-half of the total output of the Coeur d'Alêne camp is sent to East Helena. An average analysis of these ores gives approximately 40 per cent. lead and 11 per cent. sulphur. Local shipments, varying, from month to month, are mostly highly siliceous gold and silver ores carrying little lead. Small shippers, leasers of old mines, and prospectors are very numerous throughout Montana, and it is the policy of the company to encourage these men by every possible means, including the free sampling and analysis of their ores and aid in the development of their mines and prospects whenever their results show promise.

Jan 8, 1914

By D. W. Rudd, D. W. Vose, S. Johnson

The permeability of Mo-0.5 pel Ti to hydrogen was investigated over a limited range of temperature and pressuire (709° to 1100°C, 1.i and 2.0 atm). The resulting permeability, p, is found to obey the The experimental data justifies the permeation mechanism as a diffusion contl-olled pnssage of Ilvdrogen atoms through the metal barrier. 1 HE permeability of metals to hydrogen has been investigated by a number of workers and their published results have been tabulated by Barrer' up to 1951. Since most of the work on the permeability has been accomplished prior to this date, the compilation is fairly complete. Mathematical discussion of the permeability process has been reported by Barrer, smithells, and more recently by zener. From these efforts several facts are observed. First, the permeability of metals to diatomic gases involves the passage through the metal of individual atoms of the permeating gas. This is evidenced by the fact that the rate of permeation is directly proportional to the square root of the gas pressure. Second, the gas permeates the lattice of the metal and not along grain boundaries. It was shown by Smithells and Ransley that the rate of permeation through single-crystal iron was the same after the iron had been recrystallized into several smaller crystals. Third, it has been observed that the rate of permeation is inversely proportional to the thickness of the metal membrane. Johnson and Larose5 verified these phenomena by measurirlg the permeation of oxygen through silver foils of various thicknesses. Similar findings were noted by Lombard6 for the system H-Ni and by Lewkonja and Baukloh7 for H-Fe. Finally, it has been determined that for a gas to permeate a metal, activated adsorption of the gas on the metal must take place. Rare gases are not adsorbed by metals, and attempts to measure permeabilities of these gases have proved futile. ~~der' found negative results on the permeability of iron to argon. Also, Baukloh and Kayser found nickel impervious to helium, neon, argon, and krypton. From what was stated above concerning the dependence of the rate on the reciprocal thickness of the metal barrier, it is seen that although adsorption is a very important process, at least in determining whether permeation will or will not ensue, it is not the rate determining process for the common metals. A case in which adsorption is of sufficient inlportance to cause abnormal behavior has been noted in the case of Inconel-hydrogen and various stainless steels.'' APPARATUS The apparatus used in this study is shown in Fig. 1. The membrane is a thin disc (A), but is an integral part of an entire membrane assembly. The entire unit is one piece, being machined from a solid ingot of metal stock. When finished, the membrane assembly is about 5 in. long. Two membrane assemblies were made; the dimensions of the membranes are given in Table I. The wall thickness is large compared to the thickness of the membrane, being on the average in the ratio of 13 to 1. There exists in this design the possibility that some gas may diffuse around the corner section of the membrane where it joins the walls of the membrane assembly, If such an effect is present, it is of a small order of magnitude, as evidenced by the agreement of the values of permeability between the two membranes under the same temperature and pressure. A thermocouple well (B) is drilled to the vicinity of the membrane. The entire membrane assembly is then encased in an Inconel jacket and mounted in a resistance furnace. The interior of the jacket is connected to an auxiliary vacuum pump and is always kept evacuated so that the membrane assembly will suffer no oxidation at the temperatures at which measurements are taken. The advantages of this configuration are: 1) there are no welds about the membrane itself, so that the chance of welding material diffusing into the membrane at elevated temperatures is remote. 2) It is possible to maintain the membrane at a constant temperature. Since the resulting permeation rate is very dependent upon temperature, it is advisable to be as free as possible from all temperature gradients. 3) It is possible to obtain reproducible results using different specimens. The only disadvantage to this configuration is the welds (at C) in the hot zone. The welding of molybdenum to the degree of per-

Jan 1, 1962

By B. D. Cullity, K. S. Sree Harsha

When a copper or aluminum single crystal is swaged into wire, the resulting deformation texture depends on the original orientation of the crystal. The<100> and <111>orientations me essentially stable, while <110> is unstable. The greater the <100> content of the deformation texture, the stronger the wire is in torsion. the greater the<111>content, the stvonger it is in tenszotz. The preferred orientation (texture) of fcc wires, either after deformation or recrystallization, is usually a double fiber texture in which some grains have <100> parallel to the wire axis and others have <111>. The relative amounts of these two texture components, as reported by different investigators for the same metal, vary considerably. Previous work in this laboratory&apos; has shown that the starting texture of a wire, i.e., the texture which it has before deformation, can have a decided influence on the texture produced by deformation. In particular, it was found that the deformation texture of copper wire is essentially a single <100> texture, if the wire before deformation contains only a <100> component. This is true even when the deformation is carried to more than 98 pct reduction in area. This paper reports on further studies of the role played by the starting texture. Copper and aluminum single crystals of various orientations have been cold swaged into wire, and quantitative measurements of the resulting deformation textures have been made. The tensile and torsional properties of the deformed wires have also been measured, and the relation between these properties has been correlated with the texture of the wire. These measurements were made in order to demonstrate that a cold-worked wire can be made relatively strong in torsion and weak in tension, or vice versa, by proper selection of the texture before deformation. MATERIALS The copper was of the tough-pitch variety, containing, by weight, 99.962 pct Cu, 0.003 pct Fe, 0.025 pct 0, and 0.0021 pct Si. The aluminum contained more than 99.99 pct .&apos;41; the only reported impurities were 0.001 pct Fe, 0.001 pct Si, and 0.003 pct Zn, by weight. Large single crystals of these metals were grown by the Bridgman method in graphite crucibles and a helium atmospliere. Cylindrical specimens of predetermined orientation, about 1.5 in. long and 0.36 in. in diameter, were machined from the as-grown crystals and then etched to 0.25 in. to remove the effects of machining. Their orientations were checked by back-reflection Laue photographs, and they were then swaged to a diameter of 0.050 in. (96 pct reduction in area). 111 order to study the "inside texture" of the deformed wires, they were etched, after swaging, to a diameter of 0.040 in. before the texture measurements were made. TEXTURE MEASUREMENTS The fiber texture which exists in wire or rod can be represented by a curve showing the relation between the pole density I, for some selected crystal-lographic plane, and the angle $ between the pole of that plane and the wire axis (fiber axis). Such a curve will show maxima at particular values of , and these values disclose the texture components which are present. The relative amounts of these components can be determined2&apos;3 from the areas under the maxima on a curve of I sin F vs F. It is seldom necesszlry to measure I over the whole range of F from 0 to 90 deg, since the existence of maxima in the low-F relgion can be inferred from measurements confined to the high-F region. The X-ray measurements were made with a General Electric XRD-5 diffractometer and filtered copper radiation, according to one or the other of the following procedures: 1) A method developed in this laboratory,4 involving diffraction from a single piece of wire. 2) A modification of the Field and Merchant method.5 This method was originally devised for the examination of sheet specimens, but it can easily be adapted to the measurement of fiber texture. Three or four short lengths of wire are held in grooves machined in the flat face of a special lucite specimen holder. The axes of the wires are parallel to the plane defined by the incident and diffracted X-ray beams, and the holder to which the wires are attached can be rotated step-wise about the diffractometer axis for measurements at various angles 9.

Jan 1, 1962

By R. W. Raymond

The death of Mr. Stetefeldt, which occurred at Oakland, Cal., March 17, 1896, was a surprise, as well as a sorrow, to many of his friends and professional colleagues. In the Engineering and Mining Journal of March 28th, I published an obituary article, the substance of which, modified and enlarged by later information, forms the basis of the present biographical notice. I am indebted to Mr. Albert Arents, Alameda, Cal., and Mr. 0. H. Hahn, Monterey, Mex., life-long friends, and to Miss Pauline Anacker, of Gotha, Germany, a cousin of the deceased, for details which I could not have obtained elsewhere. Carl August Stetefeldt was born September 28, 1838, in the village of Holzhausen, in the duchy of Gotha, Germany, where his father was a Lutheran pastor. He was an only son, and (after the early death of a sister) an only child. In his boyhood he is reported to have been physically delicate, but mentally precocious. In 1847 his father was transferred to Hörselgau, near Waltershausen, where, besides discharging his pastoral duties, he kept a select private boarding-school, in which a few pupils received a training preliminary to the " gymnasial" course. Among these pupils (one of whom was the now famous Dr. Knorr, the discoverer of antipyrine) he included his own son, who, thus carefully prepared, entered in 1852, at the age of fourteen, the gymnasium at Gotha. The records of the gymnasium bear witness that his conduct in and out of school was " blameless," and his attention to study good." But his career as a "gymnasiast" was marked by an act of rebellion probably more startling then than it would be now. Being much more strongly attracted by the natural sciences than by the dead languages, he conceived a special aversion to Hebrew, and engaged in a conflict with the professor in that department, out of which he seems to have come victorious. At all events, he was not obliged to pursue further

Jan 1, 1897

By Henry Emmett Gross

Two types of decline curves are considered and their applications are discussed. The first is the well-known semilogarithmic decline curve having the rate of production plotted on the logarithmic scale and the time on the horizontal scale. The other curve is the percentage of oil in the fluid versus cumulative production, and it is plotted on Cartesian coordinate paper. These curves are illustrated by carefully and adequately labeled graphs. Where conditions permit application of both types of curves for rationally determining the reserves of a well, both should be applied and the most conservative reserve should be chosen. Formulas are given for determining the economic limits. For a semi-l~~arithmic~decline curve the formula is: A = B X C X D X E X F or B = A/C ? D X E X F A = total monthly operating cost (average of past year), B = economic limit in barrels of oil per day, C = days in an average month = 30.4, D = market price of crude per barrel, E = 1-royalty, F = 1-gross production tax, G = water production in barrels per day at the economic limit, H =per cent oil in fluid at economic limit. The economic limit for a per cent oil in the fluid curve is: H = B/B+G X 100 The semilogarithmic decline curve is treated first. Straight-line extrapolations on semilogarithmic paper follow the compound interest compound discount law, hence the ensuing formulas derived from this law may be used in computing reserves for such extrapolations: [1___1/(1+Y)]

Jan 1, 1939

By Henry Emmett Gross

Two types of decline curves are considered and their applications are discussed. The first is the well-known semilogarithmic decline curve having the rate of production plotted on the logarithmic scale and the time on the horizontal scale. The other curve is the percentage of oil in the fluid versus cumulative production, and it is plotted on Cartesian coordinate paper. These curves are illustrated by carefully and adequately labeled graphs. Where conditions permit application of both types of curves for rationally determining the reserves of a well, both should be applied and the most conservative reserve should be chosen. Formulas are given for determining the economic limits. For a semi-l~~arithmic~decline curve the formula is: A = B X C X D X E X F or B = A/C ? D X E X F A = total monthly operating cost (average of past year), B = economic limit in barrels of oil per day, C = days in an average month = 30.4, D = market price of crude per barrel, E = 1-royalty, F = 1-gross production tax, G = water production in barrels per day at the economic limit, H =per cent oil in fluid at economic limit. The economic limit for a per cent oil in the fluid curve is: H = B/B+G X 100 The semilogarithmic decline curve is treated first. Straight-line extrapolations on semilogarithmic paper follow the compound interest compound discount law, hence the ensuing formulas derived from this law may be used in computing reserves for such extrapolations: [1___1/(1+Y)]

Jan 1, 1939

By J. W. Cloud

years ago upon the effect of having the rails always rolled in the same direction, and also of having them rolled backwards and forwards, and showed that under the latter course there were of necesshy weak spots somewhere near the centre of the rail, yet in all this discussion the methods of rolling have been passed by almost in silence. Mr.. Sandberg in his paper mentions the idea of using a regietering dynamometer attached to the punching machines, and of det.erminit~g the quality of the metal by the resistance which is shown. I think the&apos; first idea of this kind was published by Professor Langley, then of Pittsburgh, who, while making some investigations for Mesrs. Miller, Metcalf and Parkin, announceti as tile result of a series of dynamometric experiments that abrasive resistance was the term which should be wed in regard to steels of different wearing qualities. I have had extremely delicate dynamometers attached to the instruments of precision with which I am making the iuvestigation on the fatigue of metals, and hope soon to communicate the results of the iovegtigation- made with them to the Institute. I wish again to call attention to the fact that we are wing the words " hardener " and " hardness " without any real idea of the meaning of these words. When we say hard and soft, as we have hen constantly doing during this discussion, is it quite sure that every one has exactly the same meaning in his mind ? Certainly, when hard is used in distinction from soft*, we mean not the capacity of wear, but the capacity of resistance to peuetration, to fracture, or some other resistance, and do not always meau the capacity of resistance to abrasion or crushing, which the discussion would sometimes seem to imply were the only qualitiw requisite to constitute a god rail. J. W. Cloud, Altoona, Pa. : I would call the attention of the Institute to the title of Dr. Dudley&apos;s interesting and valuable paper, —" The Wearing Capacity of Steel Rails in relation to their Chemical Composition and Physical Properties." Here are two separate and distinct questions: lst, The wearing capacity of steel rails in relation to their chemical content; and 2d, the wearing capacity of steel rails in relation to their physical properties. The discussion has been almost exclusively confined to the former question, on which there may be many differences of opinion in matters of detail without greatig affecting the result. The latter

Jan 1, 1881

By V. S. Swaminathan

This year, Great Britain is looking back over a century to August 14, 1850, the day when the first "Act for the Inspection of Coal Mines" was passed in that country, an act which signaled the end of over two hundred years of hitherto uncontrolled and dangerous mining practices. It was back in the time of Queen Elizabeth that . thousands of pounds were invested in mining, particularly coal mining in England and Scot- land. By 1640 there were collieries producing 10,000 to 25,000 tons of coal per year. In the seventeenth century the Tyne district coal industry was organized into powerful partnerships, and coal took an even larger part in industry, as a source of power and as fuel for the iron industry. In the early 19th century a "phenomenal, almost devastating expansion" characterized Britain&apos;s coal industry, and it was sparked by a 111 pct in- crease in the population of England and Wales in the first half of the century. Coal production for those 50 years increased 470 pct and pig iron production was up 946 pct for the period 1801-51.

Jan 1, 1950