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By F. R. Zacher

Unmined blocks in the Sewickley seam, surrounded by worked out areas, have been found to transmit overburden oads through the interval strata to the Pittsburgh seam workings 90 ft below. Operating experiences under these conditions are described in this paper. IT has always been understood, in northern West Virginia where both the Pittsburgh and Sewickley seams are mined, that pillaring or splitting in the lower Pittsburgh seam could break the interval strata and make mining in the overlying Sewickley difficult or impossible. In some instances, however, mining methods practiced in the overlying Sewickley have reversed the problem, resulting in a shifting of the intermediate layer and destroying valuable acreages of the Pittsburgh seam below. The Pittsburgh seam in this area is, on the average, 102 in. thick. About 18 in. of low-quality head coal are left for roof protection as it is mined. Immediately over the coal are two draw slates, two rider seams, and a good hard black shale, locally called black rock, which serves as a permanent roof where draw slates and riders are taken down on certain main haulroads. In most areas mined in this seam in the past the bottom has been satisfactory but soft. However, in areas now being mined by the Christopher Coal Co. in Monongalia County the bottom is very hard and unyielding. The Sewickley seam, lying 85 ft above the Pittsburgh, will average nearly 70 in. in thickness and is overlain by massive shales and sandstones. Much of the seam is mined only down to the "sheep skin," a hard band about 4 in. above the bottom, which is composed of relatively hard shale. Fig. 1 shows a typical cross-section through the Pittsburgh and Sewickley seams in the area being discussed. The thin Redstone seam is not deep-mined but is stripped in some locations where it outcrops. Most of the Sewickley seam in the Morgantown areas has been mined out from 10 to 30 years. There are at present only two large mines and five or six others of small production operating in that seam. Mining systems in the past were generally of the room and pillar type with some full pillar extraction. This seam in the Scott's Run area was operated by as many as thirty or forty different companies at one time, during an era beset with strikes, market failures, and depressions. Most of the barrier pillars along the many main haulroads were abandoned, and blocks of Sewickley coal that would be fully recovered with today's machinery were left unmined when conditions became anything less than favorable. Consequently the mined-out Sewickley is spotted throughout with solid blocks varying in size from 100x100 ft to 200x400 ft and larger. It is these unmined Sewickley blocks surrounded by worked-out portions that have caused transmissions of roof stresses to underlying Pittsburgh mining areas, see Fig. 2, resulting in untold difficulty. As the Christopher Coal Co. operates both the Pittsburgh and Sewickley seams, accurate maps of workings in both seams are readily available and are regularly consulted. The first Pittsburgh squeeze attributed to overlying Sewickley blocks occurred in the Arkwright mine, where a shuttle car crew was developing a section consisting of seven panel headings. These entries were being driven in solid coal 3400 ft from the nearest worked-out Pittsburgh area. As mining advanced it was noticed that certain ribs began to slough and certain areas to show signs

Jan 1, 1953

The annual report f the Secretary of the Navy for the fiscal year, ending June 30, 1917, but including operations and recommendations up to Dec. 1 of that year, contains the following remark about the activities of the Naval Consulting Board. The members of the Institute who are members f this Board are William L. Saunders, Benjamin B. Thayer, Thomas A. Edison, Thomas Robins, Lawrence Addicks, Joseph W. Richards, W. R. Whitney, assisted by 47 other members f the Institute, in the capacity of associate members of the Naval Consulting Board. During the year, the work of this board, organized and approved by Congress in 1915, has increased very materially in importance and volume, its meetings have been frequent and the work of its individual members has been such in some cases as to occupy almost their entire time in the service of the Government. Some time before the active entry of this country into war the board called a special meeting to which were invited some 50 of the leading scientists and industrial managers, whose special study fitted them to advise on the methods of meeting the

Jan 2, 1918

By R. J. Schaefer, M. E. Glicksman

Direct, in situ observation of metallic alloys during solidification reveals that in some systems crystal multiplication occurs by means of a dendrite remelt-ing process, without the necessity of independent nu-cleation events. The solidification is observed on optically clean surfaces of supercooled molten alloys. In one system (Sn-3 wt pct Bi) , a fine-grained equi-axed structure is produced by the complete disintegration, via remelting, of transient initial dendrites. In contrast, several other metallic systems show little or no evidence of remelting activity. The behavior of these metallic systems is consistent with that expected on the basis of published observations of dendrite remelting in transparent organic alloy systems. It is concluded that dendrite remelting is an important crystal multiplication process in some metallic alloys, but is velatively unimportant in some other alloys. The detachment of dendrite branches from the primary stem by a remelting process has been observed by Jackson, Hunt, Uhlmann, and seward1 during the solidification of some transparent organic alloy systems. The branches released by this remelting process can drift free of the primary stem and serve as seeds for the formation of numerous independent crystals. This proliferation of new crystals does not require repeated independent nucleation events, but only modification of the initial solidification structure. The mechanism of dendrite remelting, as described by Jackson et a1.1 and by Tiller and O''Hara,2 is dependent on the transport of both heat and solute and is, therefore, expected to operate only in alloys, and not in pure substances. It was found in the transparent organic alloy systems that remelting occurred primarily in the constricted regions near the base of dendrite branches, where the branches had grown through the solute-rich liquid layer surrounding the primary dendrite stem. It was suggested that impure solid had formed in these constricted regions at a relatively low temperature and had later become unstable as further solidification of purer material raised the temperature. Jackson et al. proposed that the equiaxed zone of metal alloy castings originates from a similar remelting process, and they demonstrated the operation of this mechanism in "ingots" poured from saturated salt solutions. Although these substances were especially selected to show solidification behavior similar to that of metals,3 the remelting mechanism has, until now, been subject to the objection that its operation has not been directly observed in a metallic system. Considering the fact that thermal properties such as diffusivity may differ by as much as two or three orders of magnitude between metals and organic compounds, this objection was considered to be possibly serious. A method has now been developed by which it is possible to make direct optical observations of metals during solidification. This method has revealed transient solidification processes which would not be detected by metallographic examination of totally solidified specimens. In particular, a grain-refinement process in a metallic alloy has been observed to be a direct consequence of the total disintegration of an initial dendritic structure. The influence of an initial, transient solidification structure on the final solidification structure is demonstrated here for the first time in a metallic system. I) EXPERIMENTAL The technique of using a transparent flux to maintain an optically clean metal surface during solidification has been described by us elsewhere.* The

Jan 1, 1968

By J. S. Aronofsky, A. S. Lee

Results and experimental procedures are presented covering a preliminary laboratory investigation of the compaction of reservoir rocks and its effect on porosity and permeability. "Egective" compressibility was measured by subjecting core material to an overburden load and reducing pore pressure. Preliminary results showed relatively high effective compressibilities which varied from 1.8 X 10-' pore volume/pore volume /lb / in.~ for limestones to 7.7 X 10-6 pore volume/pore volume/lb/in.' and even higher for sandstone reservoirs conmining large amounts of fine clay material. It appeared from the initiol results that the effective compressibility of the material could not be correlated directly with porosity and that other factors, such as the amount of clay material present might have to be taken into account. The work to date has indicated that effective compressibility factors will have to be measured for the particular reservoirs heing studied. Oil permeability of core materid was measured under various effective overburden loads from 0 to 8,000 psi. It has been found than reduction of permeability in clean sands was relatively small and the results agreed with published data. For sandstones containing large amounts of clay, preliminary tests indicated very large reductions in permeability with increasing effective overburden pressures. It is planned to continue laboratory work on this phase because of its importance in low-permeability reservoirs. INTRODUCTION During the past few years increasing interest has been shown in the differences obtained between conventional laboratory measurements on cores at atmospheric pressure and those when reservoir conditions are simulated. Since these data are used as the basis for calculations and the prediction of reservoir behavior, their evaluation under reservoir conditions is most important. The effect of the compressibility of the rock upon the reservoir behavior, as fluid pressure declines, is an important subject which has been insufficiently studied. The total pressure on any plane through a reservoir is the result of the grain-to-grain rock pressure due to the overburden and the pressure of the interstitial fluid on the plane. As reservoir fluid pressure declines, the net load on the rock phase must increase, and the result is the compaction of the rock structure which produces a decrease in pore volume. Simultaneously, the rock grains expand into the pore space as the fluid pressure declines. The result of these two effects is defined as the effective compressibility of the rock and is expressed in units of pore volume/original pore volume/psi. Work was started by Imperial in 1954 on the effects of pressure on the porosity of reservoir rock. These studies established effective compressibility factors for some limestones and dolomites. Since that time effective compressibilities have been obtained for other Canadian and some U. S. reservoir rocks. In conjunction with the study of porosity, an investigation has also been initiated to determine the effects of pressure on permeability. One outcrop and several reservoir sandstone cores have been tested to date. ROCK COMPRESSIBILITY Apparatus anD Procedure A diagram of the apparatus used in these studies is shown in Fig. 1. The equipment was constructed so that a uniform pressure, equivalent to the reservoir overburden, could be applied by the oil pump and transmitted on all sides of the core through the Lucite sheath. The sample was completely saturated by circulating brine through the mounted core. Pressure in

By H. E. Cline

Mechanical properties of the eutectic between CoAl and cobalt were measured over a range of- temnperatures and strain rates for a variety of microstructures produced by directional solidification and by thermo-mechanical processing. Directional solidification led to rodlike, lamellar, and irregular microstructures. The unusually high volume fraction of the cobalt-rich rods and the lurge spacing of the rods were explained by the phase diagram. The hot-worked structure consisted of fibers of COAL in a cobalt-rich matrix. The roonl- tevlperature strength of the uvrought material increased with decreasing grain size but the 1000°C strength decreased with decreasing pain size. At high temperatures the directionally solidified tnaterial was stronger and less strain-rate-sensitice than the hot-rolled material. The fine-grained hot-worked ma-terial became superplastic at high temperatures, with tensile elongations greater than 850 pct, while at root temperature this material was ductile and impact-resistant because of the ductile matrix. Fracture occurred in the directionally solidified material at elevated temperatures by inter phase separation and at roorn temperature by cracks in the intermetallic phase. Growth of these cracks was impeded by the ductile cobalt-rich phase. It was found that the CoAl intermetallic remains ordered at elevated temperatures. DIRECTIONAL solidification of eutectic alloys has been used to produce structures consisting of parallel rods or lamellae. Although the spacing of the phases depends on the growth rate, it has been observed to be of the order of 1 µ in many eutectics. A strong intermetallic phase has been used to reinforce a ductile matrix in the rod eutectic A1-Al3Ni and the lamellar eutectic Al-Al2cu.1 The microstructure of the eutectics A1-A13Ni and A1-A12Cu remained aligned after samples of these alloys were exposed to temperatures just below their melting points for long times. Stability of the microstructure at elevated temperatures makes directionally solidified eutectics a candidate for high-temperature applications. Recently Thompson4 has developed the Ni-NiMo eutectic containing 40 pct NiMo lamellae, giving a tensile strength superior to nickel-base superalloys. Unfortunately, this eutectic oxidizes rapidly at elevated temperatures. By mechanically processing a two-phase structure, one may reach strengths as high as 700,000 psi, as demonstrated by drawn pearlite.5 In this case the strengthening mechanism was thought to be related to the fine substructure formed during deformation.5 However, a heavily worked structure may recrystallize and coarsen at elevated temperatures. Some worked eutectics such as Al-Al2Cu,6 Pb-Sn,7 and Sn-Bi7 have shown unusually large elongations in tension when tested at elevated temperatures. This phenomenon of large extension, called "superplasticity", was related to the fine grain size of wrought two-phase alloys at elevated temperatures. A mode of deformation of "superplastic" material has been shown to be grain boundary sliding,' which has also been observed during creep of polycrystalline materials.9 The Co-A1 system was chosen for this investigation after examining the phase diagrams of binary eutectics." The high melting point of 1400°C, the aluminum content which was expected to give oxidation resistance, and the properties of the intermetallic CoAl were the chief factors influencing this choice. This eutectic consists of a mixture of the intermetallic CoAl and a cobalt-rich solid solution. The intermetallic CoAl has a large range of solubility and a CsCl structure." From the similarity between CoAl and NiAl one would expect CoAl to be ordered at elevated temperatures; however, specific heat measurements" show a transition at 800°C. West-brookL2 has measured the hot hardness of CoAl and found a rapid decrease in hardness above 600°C. The tensile properties and stress rupture properties of as-cast CoAl-Co eutectic were measured by Ashbrook and wallace13 who report a room-temperature tensile elongation of less than 1 pct. I) EXPERIMENTAL A) Sample Preparation. Experimental materials were prepared by directional solidification, by hot working, and by powder processing. The starting materials were electrolytic 99.9 pct pure cobalt and 99.99 pct pure aluminum. 1) Directional Solidification. A vertical Bridgman apparatus heated by induction was used to directionally solidify cylindrical ingots $ in. in diam and 5 in. long. The apparatus was first evacuated and then an argon atmosphere was introduced to retard evaporation. The ingots were contained in an alumina crucible inside a graphite susceptor that rested on a movable water-cooled base. The base was lowered out of the induction coil at a constant rate. Eight of the ingots were solidified using a drive rate of 2.5 cm per hr, two of the ingots at 1.2 cm per hr, and one ingot at 10 cm per hr. The eutectic composition Co 10 wt pct A1 was used in all but one ingot which had the composition of the stoichiometric CoAl intermetallic, Co 32 wt pct Al. 2) Mechanical Processing. At 1000°C the eutectic Co 10 wt pct A1 is a mixture of an intermetallic phase, Co 21 wt pct Al, and a cobalt-rich phase, Co 5 wt pct Al.10 These phases differ from the stoichiometric CO 32 wt pct A1 and pure cobalt because of the large solubility of this eutectic at elevated temperatures." Four rectangular slab ingots, 4 by 1 by 12 in. high, of Co 10 wt pct Al, Co 5 wt pct Al, Co 21 wt pct Al, and Co 32 wt pct A1 were cast for hot rolling. The cobalt was first vacuum-melted, H2-treated for 20 min,

Jan 1, 1968

THE following employment items are made available to AIME members on a nonprofit basis by the Engineering Societies Personnel Service, Inc , operating in cooperation with the Four Founder Societies Local offices of the Personnel Service are at 8 W 40th St , New York 18, 100 Farnsworth Ave, Detroit, 57 Post St , San Francisco, 84 E Randolph St , Chicago 1 Applicants should address all mail to the proper key numbers in care of the New York office and include 6c in stomps for forwarding and returning application The applicant agrees, if placed in a position by means of the Service, to pay the placement fee listed by the Service AIME members may secure a weekly bulletin of positions available for $3 50 a quarter, $12 a year MEN AVAILABLE Executive Engineer, 37, married, 3 children Now Resident Manager nonmetallic underground mine and processing plant Management and operational experience in gold, copper, zinc, limestone and lime products manufacture Mine plant design and construction, underground mines and quarries Excellent references Currently employed but available reasonable notice Prefer U S M-687-426-E-5-San Francisco Metallurgical Engineer, 29, married, one child, B S Metallurgical Engineering Five years' practical experience in milling and laboratory research Available thirty days Prefer West or Southwest U S A M-689¬522-E-1-San Francisco Experienced Mining Engineer, university graduate, 40, married Twenty years' experience all phases metal mining, past 13 years as manager, excellent cost and safety record Available short notice Best references and complete professional record available upon request M-690

Jan 1, 1952

By G. C. RIDDELL

THE metallurgist, chemist, and physicist are blazing trails that lead far afield. Pushing on into an "Alloy Age" they see a non-ferrous era over- taking iron and steel. Delving into the nature of the physical world, they break down a supposedly indivisible element, hydrogen. Not content with terrestrial problems, they peer back along the cosmic ray into iaterstellar space, glimpsing forces that are, apparently, still busy with the task of atom-making. Mastering and organizing the material and physical, they advance steadily toward that borderland of science where the concept of matter itself seems abandoned, and force is the substance left.

Jan 1, 1930

By C. D. Stahl, E. E. Templeton, R. F. Nielsen

It has been customary, in predicting saturation changes, to use the Leverett fractional flow formula", obtained by eliminating the unknown pressure gradient from the generalized Darcy equations for the separate phases. The formula presents difficulties in the case of counterflow, since the "fractional" flow may be negative, greater than unity, or, in the case of a closed system, infinite. Recently, it has been shown by several authors that the corresponding equations (with capillary pressure and gravity terms) for actual flow of the phase may be used just as well. These equations are in agreement with Pirson's1 statement that, if the two mobilities differ considerably from each other in a closed system, the flow is largely governed by the lower value. The present study was undertaken because of an apparent lack of experimental data on gravity counter-/low with which to test the theory. A 4-ft sand-packed tube in a vertical position was employed. Electrodes for determining saturations by resistivity were spaced along the tube, one phase being always an aqueous salt solution. Air, heptane, naphtha, or Bradford crude oil was used for the other phase. A reasonably uniform initial saturation was set up by pumping the phases through the system, alter which the tube was shut in and saturation profiles obtained at definite intervals. Cumulative flows over certain horizontal levels were obtained by integration of the distributions; hence, differentiation of the cumulative flows with respect to time gave instantaneous flow rates. To compare experimental and theoretical flow values, capillary pressures were assumed given by the final saturation-distribution curve. The upper part corresponds to the "drainage" region and the lower part to the "imbibition" region, where trapping of the nonwetting phase occurred. While calculations indicated that the capillary pressure saturation function and, probably, the relative permeability saturation functions changed during the segregation, the relation of the measured rates to saturation distributions are in general accord with the frontal-advance equation. It appears that the Darcy equations, as modified for the separate phases, are generally valid for counterflow due to density differences. The usual method of predicting saturation changes, which involves a continuity equation and the elimination of the unknown pressure gradient from the flow equations, should therefore be applicable. However, the need for advance knowledge of drainage and and imbibition "capillary pressures" and relative permeabilities during various stages presents difficulties. INTRODUCTION The present study was undertaken because of a seeming lack of experimental data relating to vertical counterflow of fluids of different densities in porous media. In particular, it was desired to determine whether data obtained from these laboratory tests were in accordance with certain mathematical treatments of counterflow which have been proposed. The gravity "correction" has been incorporated into the flow equations (and, hence, into displacement theory) nearly as long as both have been used. field4 and laboratory5 data have generally borne out the validity of the theory as applied, for instance, to downward displacement by gas, with all fluids moving downward. However, the modifications for counterflow have only recently been pointed out. 2-3 It has been customary to use fractional flow rates instead of actual flow rates in displacement calcuIations. In the case of counterflow, this results in negative values, values greater than unity and, when rates are equal and opposite, in infinite values. As pointed out by Sheldon, et a1,3 and by Fayers and sheldon,2 actual flow rates may be used just as well. The fact that these may be of opposite signs for the two fluids does not present any difficulty.

By D. B. Crouch, D. A. Poulter

The engineering and metallurgical assessment of the McLaughlin Project ore body concluded that an open-pit mine and cyanide leach mill process would be feasible, producing both waste rock and residual mill tailings. As a part of the planning and permitting process, site selection studies were conducted for the tailings and waste rock disposal. The site selection process began with a regional identification of potential disposal sites and proceeded through 1) regional screening, 2) elimination of sites with obvious fatal flaws, 3) qualitative ranking of site evaluation criteria, 4) quantitative ranking of sites, 5) field investigation, 6) evaluations of field data, and 7) selection of preferred sites. Based on this approach of site rankings and field evaluations, tailings and waste rock disposal sites were selected and recommended for the preliminary design phase of the permitting and project development process. The site selection study provided the documentation necessary to justify the use of these sites for waste disposal and enabled Homestake Mining Co. to anticipate and integrate environmental concerns with agency requirements into the planning process.

Jan 1, 1986

By Robert H. Palmer

Sacuranao Field.—Bacuranao field is about 12 miles east of Havana, along the contact between Cretaceous sediments and a serpentine intrusion. The zone lies within an extensive anticlinorium. The field had no developments during the year 1939. The production of 9½ bbl. per day is distilled and the gasoline and kerosene are extracted. The asphalt residue. is sold for road construction. The gas is compressed and

Jan 1, 1940

By Robert H. Palmer

Sacuranao Field.—Bacuranao field is about 12 miles east of Havana, along the contact between Cretaceous sediments and a serpentine intrusion. The zone lies within an extensive anticlinorium. The field had no developments during the year 1939. The production of 9½ bbl. per day is distilled and the gasoline and kerosene are extracted. The asphalt residue. is sold for road construction. The gas is compressed and

Jan 1, 1940

Jan 1, 1934

By E. F. La Vigne

On Aug. 10, 1884, the Retsof Mining Co. began the sinking of an 18 by 12-ft. shaft at Retsof, N. Y. Rock salt was reached in 1885, in September, at 1008 ft. below the surface. The first salt was shipped in the fall of 1885. A timber breaker was built in 1886. In July, 1895, there was a consolidation of the Retsof Mining Co., the Greigsville Salt & Mining Co., the Livonia Salt Co., and the Lehigh Salt & Mining Co. These consolidated salt companies are now known as the Retsof Mining Co., a subsidiary of the International Salt Go. Eventually all of the mines were closed except the mine of the Retsof Mining Co., at Retsof, Livingston County, New York. On July 6, 1921, about 1/2 mile south of the original shaft arid plant of the Retsof Mining Co., a new 9 by 28-ft. concrete-liried shaft was started. The shaft is 1063 ft. deep from the top of the shaft collar to the bottom of the salt bed. At the same time a reinforced-concrete breaker and other buildings were erccted. This new plant began operations on Dee. 15, 1923. It was designed for a capacity of 3000 tons in 8 hours. Geology The workable rock-salt bed is 1063 ft. below the surface and 326 ft. below sea level, and varies in thickness from 9 to 10 ft. The total thickness is greater than that but is contaminated with shale above and below the pure mineral. The characteristics of the formation are shown in Tables 1 and 2. The bed dips uniformly 0.87 per cent to the south. Prospecting As the salt deposil in New York State is known, very little prospecting has been necessary. Before the sinking of the Retsof No. 1 shaft, a well was drilled to prove the existence of salt. No. 1 shaft was sunk where the well was located. The several salt wells drilled in Livingston Courlty proved generally the existence of salt throughout the county. (See U. S. Geol. Survey Bull. 669: Salt Resources of the U. S.)

Jan 1, 1938

By E. F. La Vigne

On Aug. 10, 1884, the Retsof Mining Co. began the sinking of an 18 by 12-ft. shaft at Retsof, N. Y. Rock salt was reached in 1885, in September, at 1008 ft. below the surface. The first salt was shipped in the fall of 1885. A timber breaker was built in 1886. In July, 1895, there was a consolidation of the Retsof Mining Co., the Greigsville Salt & Mining Co., the Livonia Salt Co., and the Lehigh Salt & Mining Co. These consolidated salt companies are now known as the Retsof Mining Co., a subsidiary of the International Salt Go. Eventually all of the mines were closed except the mine of the Retsof Mining Co., at Retsof, Livingston County, New York. On July 6, 1921, about 1/2 mile south of the original shaft arid plant of the Retsof Mining Co., a new 9 by 28-ft. concrete-liried shaft was started. The shaft is 1063 ft. deep from the top of the shaft collar to the bottom of the salt bed. At the same time a reinforced-concrete breaker and other buildings were erccted. This new plant began operations on Dee. 15, 1923. It was designed for a capacity of 3000 tons in 8 hours. Geology The workable rock-salt bed is 1063 ft. below the surface and 326 ft. below sea level, and varies in thickness from 9 to 10 ft. The total thickness is greater than that but is contaminated with shale above and below the pure mineral. The characteristics of the formation are shown in Tables 1 and 2. The bed dips uniformly 0.87 per cent to the south. Prospecting As the salt deposil in New York State is known, very little prospecting has been necessary. Before the sinking of the Retsof No. 1 shaft, a well was drilled to prove the existence of salt. No. 1 shaft was sunk where the well was located. The several salt wells drilled in Livingston Courlty proved generally the existence of salt throughout the county. (See U. S. Geol. Survey Bull. 669: Salt Resources of the U. S.)

Jan 1, 1938

By I. R. Kramer

The stress associated with the surface layer was deter-minedfor iron and molybdcnum. These measurements show that the surface layer plays a very important role in the plastic deformation of bcc metals. From the relationship between strain arui the surface layer stress and the back stress imposed by the internal obstacles, it is Proposed that the term of of the Hall-Petch equation is related only THE large number of studies on plastic flow of bcc metals have failed to delineate clearly the nature of the obstacles influencing dislocation movement. Since there have been numerous articles which have reviewed the mechanisms proposed to explain various aspects of plastic flow of bcc metals (for example, conrad1 and Keh and weissmann2), no attempt will be made here to discuss their conclusions. However, it should be to the surface stress while the term Kfd is the stress required to move dislocations through internal obstacles. Further, it was possible to derive the well-known empirical equation C = , and it is shown that the terprz a is comprised of two terms: a term Cs associated with the surface layer stress and Ci related to internal dislocation obstacles. pointed out that in all of these publications it has been tacitly assumed that plastic flow occurred uniformly throughout the cross section of the specimen (except, of course, for the Luders band region), It has generally been further assumed that the nature and distribution of the obstacles opposing the motion of dislocations are of the same type throughout. The role of the surface layer in bcc metals has not, as yet, been considered even though its role in fcc metals has been shown clearly to be of primary importance.3-5 Investigations on fcc metals have shown that at the onset of plastic deformation a surface layer acts to

Jan 1, 1968

By W. F. Baldwin

The timing circuit generally employed in Carter Reservoir Behavior Analyzers consists of a synchronous motor driven cam which actuates a microswitch. A mechanically actuated timer of this type has several inherent disadvantages, among which are the following: 1. The first time interval may not be of uniform length, depending on the exact position of the cam at the conclusion of a previous run. 2. The positioning adjustments on the microswitch lever arms are critical and require periodic readjustment. 3. The mechanical system is subject to wear which will ultimately impair its accuracy. It was therefore considered desirable to devise an alternate method which would eliminate these difficulties without introducing others that would be equally troublesome. This note describes the design of an electronic timing device which has been incorporated in the analyzer constructed by the Field Research Laboratories of Magnolia Petroleum Co. The electronic timer circuit is built around a simple neon glow tube relaxation oscillator, the complete circuit diagram of which is shown in Fig. l. The operation of the circuit is as follows: Condenser C, is charged to the critical firing voltage of the neon glow tube VR-75 by battery B1 through resistors R1 and R2. When the neon glow tube fires, the condenser C, is discharged, The charging cycle then repeats itself,

Jan 1, 1950

By Roussey Roussev

The use of chemical additives on grinding is of significant importance considering the high energy consumption of grinding processes. My research indicates that the dispersant approach explains the effects, in this particular case of wet grinding. Further, the dispersant approach combined with torque measurements give the possibility of clarifying the mechanisms involved when using grinding aids. I find the conclusions derived from the data obtained to be correct and useful for grinding. In general, I agree with the explanations. However, I would like to discuss several additional points that I consider to be important, and in the same time to mention some of my own results from investigations similar to those presented in the study under discussion. The "bed volume concept" and the change of slurry viscosity explain adequately the data plotted on [fig. 3], in conjunction with [Figs. 1 and 2]. However, the significant increase of the average torque in the case of 83% solid with XFS-4272 introduces the necessity of establishing the optimum of percent solid when dispersant is used. For example, the optimum percent of solid for different materials varies. One of the reasons is the material's mass density. On the other hand, it is necessary to determine the concentration of the chemical used. Because of this, it would be interesting to know how the cited concentration was selected.

Jan 1, 1983

By Robert W. Hunt

The memorable features of American history have been making fast during the last century, and notably so since 1860; and they are by no means confined to political or to any one branch of scientific development. Of all the industrial arts, none show a greater change or 'a mightier progress than the Bessemer manufacture. And this year, while we are celebrating the first centennial of our national life, we can also celebrate the first decennial of American Bessemer practice. While not forgetting or undervaluing what has been done in other countries, I have thought that a brief history of the introduction and development of the Pneumatic or Bessemer process in America would be of interest. In 1863 the Kelly Pneumatic Process Company was formed and an arrangement entered into with William Kelly, who had taken out letters-patent of the United States, Nos. 16,444; 17,628, reissued as 505; 18,910, dated January loth, 1857; June 23d, 1857; November 36, 1857; and December 22d, 1867, respectively. This association mas composed of the Cambria Iron Company, E. B. Ward, Park Brothers & Co., Lyon, Shorb & Co., Z. S. Durfee, and, later, Chouteau, Harrison & Valle joined the combination. Not satisfied with possessing the control of the Kelly patent, they sent Mr. 2. S. Durfee to England, to secure for this country Mushet's patent on recarburization, No. 17,389, dated May 26th, 1857, the same having been taken out in England on September 22d, 1856. In this Mr. Durfee was successful. Previous to the application of William Kelly for a patent, Henry Bessemer, of England, had taken out patents dated February 12th, 1856, and August 25th, 1856, in this country. Kelly claimed priority in the discovery of the principles of the process, and the Patent-office allowed his claim by granting him his patents. In the autumn of 1862 Mr. Alexander L. Holley, while in England, was impressed with the importance of Mr. Bessemer's invention, and so fully foresaw its future, that, upon his return to the United States, he induced Messrs. John A. Griswold and John F. Winslow, of Troy, New York, to join him in endeavoring to possess Bessemer's American patents. Mr. Holley returned to England in

By Howard S. Bryant

FROM the viewpoint of the oil producer, the oil refiner, the oil marketer, and the investor, in oil securities, a brief picture of the crude oil supply and demand in the present critical season of the year will be timely and interesting. Although crude oil production has been in a comparatively poor statistical position this year, increased sales and sustained refinery and crude oil prices have allowed increased profits for many oil companies. The large amount of crude oil going into storage during the present period of peak consumption, just previous to the major yearly fall decline in consumption, has caused oil producers to make plans to leave the oil in the ground for the present in several of the areas of large flush production. The present moment is looked on as the turning point in the current year.

Jan 1, 1929

By Frank J. Tolonen

BENEFICIATION of iron-bearing formations is one of the major problems of research at the Michigan College of Mining arid Technology. Funds for this purpose hate been supplied by the State of Michigan supplemented by contributions of labor and some supplies from the Federal Government during the depression. The iron-mining companies have cooperated in securing samples and have also furnished much valuable information relative to the various formations.

Jan 1, 1937