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By J. F. Wolff, Anson A. Betts

The following correspondence relating to a paper bearing the above title, presented by J. F. Wolff, at the New York meeting in February, 1917, and published in the Transactions, Volume LVI, page 142, has passed between the author of the paper, and Mr. Anson G. Betts, and is interesting, although it was received much too late for incorporation in its proper place in Volume LVI. Anson G. Betts, Asheville, N. C.—1. I should like to ask Mr. Wolff if he finds from analysis of the iron formation and of the iron ore, and from the relative amounts of each in each unit area of the formation, unleached and after leaching, that the iron remains entirely insoluble and the total quantity still remains present; or whether he finds that some of the iron is removed, or possibly even added by deposition from the water passing through the formation. 2. The water that passed into the iron formation had to go somewhere; was it absorbed by underlying formations through hydration, or, after passing through the ore formation, did it come to the surface in springs at a lower elevation, or how did it escape from the ground? 3. I should like to ask Mr. Wolff whether he finds that the iron formation in the sedimentary series does not come next to the quartzites and generally between the quartzites and slates. J. I?. Wolff, Duluth, Minn.—1. In common with others, you appear to have some hesitancy in accepting the fact of the removal, by solution, of the enormous quantity of silica which has been leached out of portions of the Biwabik iron formation, thus forming orebodies of merchantable iron ore. I believe that even Dr. Waldemar Lindgren once hesitated to accept this fact. However, the evidence is so simple and absolutely conclusive that the fact is established beyond all question. At the contact of orebodies with their rock walls, the bands of iron ore in the orebody can be seen in contact with the corresponding bands of original iron oxide in the rock wall, and the chert layers in the rock wall can be seen to give place to fine granular material (fine silica and iron oxide) and pore space. This is especially noticeable where slumping at the rock walls has not been so great as to displace the layers in the orebody from their contact with their corresponding layers in the rock wall. Although complete analyses of the entire original rocks in the iron series have not been made in any place, to my knowledge, from the best data at hand as to the average analysis of the Biwabik series and the

Jan 1, 1920

By William A. Longacre

IN a previous paper1 the author discussed the problem described by the title of this paper, outlining and reviewing the Gish-Rooney method, with comparison and brief analysis of the interpretation techniques of Roman2 and Tagg.3 Some aspects of the simple type of two-layer system were reviewed from various sources.4,5,6 THE TWO-LAYER PROBLEM For the configuration shown in Fig. I, and for any electrode separation A, the apparent resistivity is a function of the relative depth [HA], the overburden resistivity pi, and a factor K defined by the equation [ ] where p2 is the resistivity of the lower bed, Thus, by the known theory of electrical images, [ ] THE MULTILAYER PROBLEM As the number of isotropic, homogeneous, horizontal layers increases, the difficulties of interpretation multiply. The theory becomes much more involved, and in view of the state of our knowledge, the general problem is virtually impossible of exact solution. However, certain types of [ ] multilayer problems can be worked out in terms of two-layer theory. Hummel,7 Pirson,8 Tagg,3 Watson,9 and others have pointed out the possibility of building up approximations of multilayer resistivity curves with suitable combinations of two-layer curves. Many three-layer curves can be constructed in this way to a good degree of accuracy, and special types of four-layer curves can be approximated. It is very likely that as the number of layers increases, the method of combination will not give good approximations except in very special cases, In the analysis of actual field data, the author has found that many obviously multilayer curves can be solved partially with a good degree of accuracy, using the theory that thin adjacent beds may be considered as one layer or zone, and applying two-layer theory to the extremities of the field curve. MODIFIED TAGG METHOD OF INTERPRETATION Tagg's second method, though superior to his first, necessitates a large number

Jan 1, 1941

By E. C. Harder, E. W. Greig

Bauxite is known mainly as the ore from which aluminum is smelted but it has large use also in the manufacture of artificial abrasives and in the production of a number of useful chemicals as well as of aluminous cement "ciment fondu." An important and growing use is in the manufacture of refractory products. Composition Dana and earlier mineralogists gave the mineral formula of bauxite as A1203.21120 and the composition as A1202, 73.9 pct; H2O, 26.1 pct. A specific mineral of this composition has, however, never been identified by either microscopic, chemical or X ray examination, and therefore it is concluded that bauxite is a rock consisting of one or more aluminum minerals together with impurities. The term is now used synonymously with aluminum ore and it embraces gibbsite (hydrargillite or alpha trihydrate), A1203. 3H20 (A1203, 65.4 pct; H2O, 34.6 pct); boehmite (alpha monohydrate), A1203•H20 (A1202, 85 pct; H2O, 15 pct) ; diaspore (beta monohydrate), A1203•H20 (A1203, 85 pct; H2O, 15 pct), and mixtures in various proportions of any two of them. Bauxite of the Mediterranean region in Europe is predominantly boehmite, as in France and Istria, subordinately a mixture of gibbsite and boehmite, as in Dalmatia, or of boehmite (or gibbsite) and diaspore, as in Greece. The bauxite of North and South America, tropical Africa, Asia, and Australasia consists largely of gibbsite, but boehmite in appreciable amount occurs in many places. Corundum (A1202) is not included un¬der bauxite, although gradations from bauxite to emery or corundum exist. All bauxite, irrespective of the aluminum minerals composing it, contains certain impurities in variable amount, including silica in the form of clay minerals (kaolinite, halloy site, and others) or quartz, iron oxide (as hematite or goethite), titania (as leucoxene or rutile), iron sulfide (as pyrite or marcasite), iron carbonate (siderite), and calcium carbonate (as calcite); the last three mentioned in minor amount and of local occurrence only. Bauxite belongs to a group of partly consolidated materials called laterites, formed by surface weathering. This group includes also impure siliceous, ferruginous, and phosphatic bauxite and siliceous and aluminous iron ores and manganese ores and nickel and chrome laterites. Phosphorus and manganese minerals locally form important impurities in bauxite deposits. Properties Gibbsite is white or light shades of gray, cream or pink. Its hardness is 2.5 to 3.5; specific gravity, 2.3 to 2.4; crystal system, monoclinic, crystals tabular parallel to 001, often fibrous, concretionary, stalactitic; luster, vitreous to pearly; generally translucent; cleavage, parallel to 001; disassociation temperature, approximately 300°C. Boehmite, a relatively new and important mineral described by J. Boehm15 in 1925, confirmed and named by J. de Lapparen64 in 1930, has some properties not yet definitely determined. It occurs in grayish, brownish, and reddish shades. Its hardness is between that of gibbsite and diaspore; specific gravity, 3.01 to

Jan 1, 1960

By Edwin F. Brush, John Chipman

Published data on the activity of carbon in binary and ternary austenite at 1000°C are reviewed. The composition variables are . The coefficient, Vj, has the value for substitutional elements but may be assigned a ualue -1 for silicon to effect a simplification on the mathematical treatment. The activity coefficient PC = is obtained from gas equilibrium data. For the ternary systems studied the Henrian activity coefficient is given by the expression: The principle advantage in cornparison with the analogous expression in terms of atom fractions is found in the fact that for most systems the final term and in many the last two terms are zero. Values of the interaction parameters are tabulated and the graphical comparison of the equation with experirt~ental data is sho,wn in several figures. The thermodynamic properties of the solid solution, austenite, are of considerable importance in the heat-treatment of alloy steels and in other aspects of ferrous metallurgy. Early studies embodied in the Fe-C diagram have been extended to include other binary and some ternary diagrams. Our best hope of obtaining a useful thermodynamic treatment of reactions in complex alloy steels will not be found in quaternary and quinternary phase diagrams but in determinations of activities and interaction relations among the several solute elements. The foundation for such a development was laid by smith' in his early studies of the activity of carbon in Fe-C alloys and his subsequent work on Fe-C-Si, Fe-C-Mn, Fe-C-Ni, and Fe-C-Co solid solutions.2"4 Other observers have also made noteworthy contributions and these will be discussed and correlated here in the light of a somewhat simplified mathematical treatment of solute interactions. Fe-C AT 1000°C In a recent review of the thermodynamic properties of binary Fe-C austenite it was shown that the simple mathematical treatment employed by smith' was capable of describing all the published results on this solution. The treatment utilizes the atom ratio, yc = nC/nF,, rather than the atom fraction. The activity of carbon is proportional to the equilibrium gas ratio, either measured on a scalk in which the activity of graphite is taken as unity or, alternatively, aC may be set equal to yc at infinite dilution. In either case the ratio aC/y = (PC, the activity coefficient. It was found that the experimental data of smith1 and those of Diin-wald and wagner; Bungardt, Preisendanz, and Lehn-ert,' and Scheil, Schmidt, and Wiinnings at temperatures of 800" to 1200° C as well as reliable data on the solubilities of graphite and cementite could be represented by the equation for which graphite is the standard state: The data on alloyed austenite have been obtained at 1000°C. For this temperature, the "Henrian" activity coefficient (which is unity at infinite dilution) is: FOr an interstitial solute such as carbon in austenite it has been shown by statistical mechanicsg that the activity in the infinitely dilute solution is proportional to the ratio of the number of lattice sites occupied by carbon to the number of yet unfilled lattice sites. A variable zz proportional to this ratio serves as a useful measure of concentration:" in which b is the number of lattice sites provided by each atom of solvent; in austenite b = 1. The Henrian activity approaches zz at infinite dilution and the ratio a is the activity coefficient. The effect of a change in concentration is then given by: It has been shown further that in some systems the derivative in Eq. [4] remains constant over a wide range of concentrations. In such a case second-order terms become negligible and the Henrian activity coefficients is:

Jan 1, 1969

By C. S. Smith, K. K. Ikeuye

In an earlier paper1 one of the authors called attention to the significance of the relative free energies of grain boundaries and interphase boundaries in alloys in determining the shape and distribution of micro-constituents. The ratio of the interphase and inter-crystalline boundary energies (that is, —?12, where ?12 is the energy of the interface between a crystal of phase 1 and a crystal of phase 2, and ?11 is the energy of the boundary between two crystals of phase 1) will be denoted by F. It is this ratio that determines, by the simple triangle of forces relation, the dihedral angle, ?, of phase 2 where it adjoins a boundary between two grains of phase 1. On a metallographic sample various angles are actually obtained because of the random orientation of the plane of observation, but the statistically most frequent angle is the true one. These basic principles were discussed in detail in the earlier paper. The experiments described below show the effect of both composition and temperature on ? and T for some alloys containing a liquid phase, and provide data on the rate of approach to the equilibrium angles in both solid and liquid phases. All the alloys were melted in a graphite crucible and cast into ingots 3/4 by 11/8 in. cross-section. Some of the aluminum alloys consisted of two immiscible liquids from which uniform castings could not be obtained. The amount of liquid phase varied locally to a considerable extent and the analyses were meaningless. Nevertheless, the composition of the liquid would not differ from that in an alloy of the intended gross composition, and the synthetic composition of the alloys was therefore used in considering the surface energy results. The ingots were given initial deformation by cold-rolling to 50 pct reduction, annealed, and given a second 50 pct reduction prior to cutting into small samples for heat treatment at the times and temperatures subsequently reported. The resulting micro-samples were carefully prepared metallographically and examined at magnifications of 650, 1280, or 2500. The objectives used were 21X, 0.40 NA (dry); 41X, 0.65 NA (dry); and 80X, 1.40 NA (oil emulsion). The appropriate angles were measured by rotation of the stage of a Bausch and Lomb metallograph to align the appropriate boundaries successively with a cross-hair in a micrometer eyepiece. About 250 angles were measured on each phase. Though the angles were read to 1°, the accuracy is probably not above 3°, because of uncertainty in setting the cross-hair tangent to the sometimes curved boundary. The corners of very small particles, particularly in early stages of adjustment after cold-rolling, were difficult to measure and the results were slightly dependent on the magnification used (compare Fig 1-C and 1-D). With particles of larger size and more nearly equilibrium shape, magnification made no difference (vide Fig 1-F and 1-G). The measured angles were grouped in 10° intervals (5° if ? was less than 20°) and plotted in bar

Jan 1, 1950

Flaubert, as we know, laid stress on the selection of the right word, le mot juste, the precise epithet, the word that belongs to the thing. A sentence, or even a paragraph, may be spoiled. by the use of a word that is not proper, that does not fit or is foreign to the meaning intended. An Australian mining expert is reported to have said: You have a property of considerable value, and what I saw warrants s good development of very rich cubicular galena, with gossan intermixed. 'Cubicular' means 'belonging to a small bedroom', a 'cubicle' being a sleeping compartment. He meant 'cubic', of course. This is a malapropism, and reminds me of the lady from Chicago that, on her return from Europe, said how much she had enjoyed the rural parts of France, because, among other things, it was "so delightful to hear the French pheasants singing the mayonnaise to the tune of the Los Angelus". It is impossible to amalgamate coal-tar thoroughly with the pulp in the agitating-tank. In metallurgy, 'amalgamate' refers to the combination of mercury with one or both of the precious metals, forming an amalgam, which is an alloy of mercury with another metal. It differs from other alloys, such as brass or bronze, in being made without the aid of heat, inasmuch as mercury is molten at the ordinary temperature. The word comes to us from the Greek through Old French and means 'something soft'. It is a mistake to use technical terms, having a specific meaning, for purposes that are foreign to that meaning. The writer of the quotation is not discussing any combination of metals; he is dealing with the physical process of mixing and is using 'amal-

Jan 1, 1931

By P. B. Knuckey, D. Littleford

The Kalengwa mine, situated in a remote area of Zambia in Central Africa, has presented some unique problems to the planners engaged in developing the deposit. This small, high grade copper deposit contains some 1,688,000 tons of ore at a grade of 9.3% contained copper. Of this 362,000 tons is classified as high grade ore at 27.2% Cu, the coarse fraction of which can be fed directly to converters; 733,000 is classed as intermediate grade ore averaging 6.3% Cu, and 593,000 tons classed as low grade ore containing 2.1% Cu. The geology of the deposit and the establishment of the mining operation is fully described. A concentrator is being built at Kalengwa to treat the high grade fine product, intermediate, and low grade ore, whilst the coarse high grade ore will be trucked to the Copperbelt smelters for direct smelting. Details of metallurgical processing are given. The decision to truck the coarse high grade ore to the smelters on the Copperbelt necessitated the construction of a new 200-mile road, the setting up of a fleet of heavy ore transport trucks and associated equipment. The remoteness of the area from established communication facilities on the Copperbelt necessitated the provision of radio communications between Kalengwa and the head office at Kalulushi, and the establishment of a regular mine air service. The paper also describes the training of an unsophisticated local population in the operation of heavy plant and machinery, the establishment of the township, and the provision of health services.

Jan 1, 1972

(Members are urged to send in for this column, any notes. of interest concerning themselves or their fellow-members.) The following members registered at Institute headquarters during the month of May: Emil Gathmann, Baltimore, Md. Philip Argall, Denver, Colo. Albert H. Fay, Washington, D. C. A. C. Hodge, F.R.G.S., St. Austell, Eng. Alfred E. Barlow, Montreal, Canada. S. M. Marshall, Johnstown, Pa. B. C. Yates, Lead, S. D. Miltiades Armas, Paris, France. Leonard S. Austin, Salt Lake City. Albert Sauveur, Cambridge, Mass. Henry A. Wentworth, Boston, Mass. G. A. Reinhardt, Cambridge, Mass. Frank M. Leland, Mackay, Idaho. Fred Crabtree, Pittsburg, Pa. W. N. Crafts, Cleveland, Ohio. T. A. Rickard, London, England. Louis Hasbrouck, Kingston, N. Y. F. Lynwood Garrison, Philadelphia, Pa. F. V. Desloge, Desloge, Mo. S. B. Christy, Berkeley, Cal. E. C. Templeton, Palo Alto, Cal. H. A. Buehler, Rolla, Mo. L. D. Ricketts, Warren, Ariz. F. W. DeWolf, Urbana, Ill. J. E. Johnson, Jr., Ashland, Wis. Howland Bancroft, Denver, Colo. A. O. Granger, Cartersyille, Ga.

Jan 6, 1913

By T. B. Brooks

THE iron ores of the Marquette region are mostly extracted in open excavations ; hence the process is more properly quarrying. Several attempts at underground work have been made, which have not, on the whole, been successful. The Edwards mine has been almost entirely wrought by candle-light. The slate ore pit, No. 1, of the New England mine, is now worked in the same way, as is also the Pioneer furnace pit of the Jackson mine. The Champion mine was opened systematically for underground work, with two levels, 60 feet apart, and three shafts at distances apart along the bed. of 200 feet; but this idea has been practically abandoned, the greater part of the ore in that mine being now taken out in open pits. Several other mines have occasionally worked underground stopes, but only temporarily; if such stopes could not be opened out to day-light, they have usually been abandoned. In brief, it may be said that no considerable amount of ore has as yet (1870).been extracted underground in the region, and of that so mined very little has been taken out at a profit; and I may add that it seems to be the belief of the most experienced mining men that this state of things will hold for some time to come for reasons which will appear. Nearly the same remarks may be applied to the mines of the Iron Mountain region, Missouri, the ores of which are very similar in character to those of Marquette. Some of the New York and New Jersey magnetic deposits are wrought open, but this is the exception, underground mining there being the rule. The following brief sketch of the geological structure of the Marquette deposits will indicate some advantages of the method of mining employed. The iron-bearing (Huronian) series of rocks, are stratified beds, the principal ore formation being overlaid by a quartzite, and underlaid by a diorite, or greenstone. This ore formation is made up, first, of pure ore ; second, of a mixed ore" (i. e., banded * A second part of this paper was read before the American Society of Civil Engineers. Both papers are embraced in Chapter IX, Part I, Vol. II, Geological Survey of Michigan.

Jan 1, 1873

By P. Duwez, L. Zwell

L. S. BUSCH—We have had presented two methods of measuring these variations in powder compacts. E. OROWAN—Tn connection with the rolling mill research work carried out at. the Cavendish Laboratory, Cambridge, with the help of the British Iron and Steel Research Association. Dr. E. A. W. Hoff, Mr. J. Los, and myself, have determined coefficients of friction at ex- treme pressures for a number of liquid and solid lubricants, both by direct measurement, and by calculation from measured values of the roll force. The most efficient lubricants at these high pressures (for the small amounts of sliding that, occur in rolling) were camphor and. in particular, borneol (Borneo-camphor). Perhaps such lubricants could be used with advantage in the kind of work described by Dr. Wulff. L. S. BUSCH—1 think Dr. Wulff has in the past mentioned experiments which have been performed in the extrusion and rolling of metals and which led to conclusions which can be applied to the compacting of metal powder. A. SQUIRE*—There have been some recent developments in the field of high pressure lubricants which indicate that boron nitride might be a very desirable material to employ as a die lubricant. At the present time its cost is prohibitive, but as the need arises for the material it will undoubtedly come down in price. The present price is $200. a pound. It is my understanding that one of the reasons for vacuum pressing both in ceramics and metal powders, is to prevent

Jan 1, 1950

By J. W. Gabelman

A study of spatial relations between uranium and other metal deposits and hydro thermally altered rocks in western Colorado demonstrated districtwide and regional zoning. The pattern was later found repeated elsewhere in the Western Hemisphere Cordillera. District mineralization centers are pipelike bodies of pervasively altered rock from which intensity-temperature-pressure gradients decreased outwardly. Uranium occurs in several zonal environments but usually is economic only in outermost zones. The general similarity of zones throughout the tectoni-cally and metallogenically uniform Cordillera may reflect a consistent hydrothermal process involving zoning. By determining positions of zones it should be possible to select for examination the most favorable small portions of districts or provinces. Mineralogical zoning has been discussed by Lindgren,l3 Graton,lo Emmons,' Blanchard,' Park and many others. It is commonly found to some extent in most mineralized areas. The existence of nonmetallic alteration envelopes around lode metal deposits and their relation to metallization were first emphasized by Lovering,l4 Burbank, Sales and Meyer," Sales,2o McKinstry,I7 Lovering and others15 and Schmitt. Also, large areas of nonmetallic alteration containing porphyry-type replacement metal disseminations have long been recognized and are described by Schwartz,25-28 Kerr and others" and Gilully. In some districts, e. g., Bingham Canyon, Utah, and Santa Rita, N.M., base metal lode deposits and their alteration envelopes are zoned around large altered areas which contain porphyry copper replacement disseminations; however, the spatial and genetic relations between lodes and replacement disseminations and their associated alterations do not seem to have received sufficient attention. Bodies of altered rock containing porphyry-type replacement disseminations are many times larger than the alteration envelopes containing lode deposits. The two types are rarely superimposed. They occur adjacent to or independent of one another, but they are believed to be related through the mechanism of zoning as suggested by Gabelman and Boyer. 5'6 Most of the significant lode metal deposits are distributed around central pipelike bodies of strong, pervasive, nonmetallic alteration which may or may

Jan 1, 1962

By Leo H. Glanville

Until 1934, natural ventilation was depended upon in the mine of the Climax Molybdenum Co. at Climax, Colorado. In that year a 7-ft. axial-flow, low-pressure fan was installed as an exhausting unit. In 1936, three more fans of the same kind were installed, all as exhausting units, with a total capacity of 115 000 cu, ft. per min., and since then fans and sprays have been added as required. Atmospheric Conditions Adverse atmospheric conditions at this elevation of 11,500 ft. account in part for difficulty in maintaining adequate ventilation throughout the mine. Barometric pressures range from 18.99 to 20.01 in. of mercury; the norma1 average being 19.70 in. Air weight is 0.051 lb. per cu. ft., and humidity is low—about a 30 per cent yearly average. This makes the use of mechanical humidity aids mandatory the Year around to prevent excessive dryness of the mine workings and the resultant dust hazard. The yearly temperature range is from minus 24" to 75°F.; typically, in February 1942 the mean low was minus 3.25°F. and the mean high, 21.3°F. In August the mean low was 34.8°F.; the mean high, 64.26°F. Even during the summer month air filtration through the openings of the cave area is 32°F., owing to accumulation of snow in the glory hole and in Part to glacial ice, which, combined with a rock temperature of 39°F. on the upper levels (elevation 11,945 ft.) and 42°F. on the main haulage level (elevation 11,470 ft.], makes it difficult to maintain a comfortable working temperature. The one advantage in ventilation of mine workings at the altitude of the Climax mine is that the power required to circulate a given air volume is 32 per cent less than would be required at sea level. Problems since 1936 the mine management has studied intensively plans for providing adequate ventilation for the entire mine for its expected life. As the ore breaks into large pieces, much secondary blasting is necessary, therefore there is a considerable amount of smoke, gas and dust, which requires circulation of a large amount of air to remove the contamination, It is undesirable to use haulage drifts and manways as air passages because some would be passageways for contaminated air also, and there would be undesirable high velocities in some drifts. High velocities and large volumes of subfreezing air dry out the passageways through which they pass, and thus increase the amount of dust. Regulating doors in haulage drifts are difficult of upkeep and interfere with production. It was decided as a general principle to distribute fresh air to each working place at low velocities and low pressures and to remove contaminated air as soon as possible with a minimum of travel through working places.

Jan 1, 1943

By Leo H. Glanville

Until 1934, natural ventilation was depended upon in the mine of the Climax Molybdenum Co. at Climax, Colorado. In that year a 7-ft. axial-flow, low-pressure fan was installed as an exhausting unit. In 1936, three more fans of the same kind were installed, all as exhausting units, with a total capacity of 115 000 cu, ft. per min., and since then fans and sprays have been added as required. Atmospheric Conditions Adverse atmospheric conditions at this elevation of 11,500 ft. account in part for difficulty in maintaining adequate ventilation throughout the mine. Barometric pressures range from 18.99 to 20.01 in. of mercury; the norma1 average being 19.70 in. Air weight is 0.051 lb. per cu. ft., and humidity is low—about a 30 per cent yearly average. This makes the use of mechanical humidity aids mandatory the Year around to prevent excessive dryness of the mine workings and the resultant dust hazard. The yearly temperature range is from minus 24" to 75°F.; typically, in February 1942 the mean low was minus 3.25°F. and the mean high, 21.3°F. In August the mean low was 34.8°F.; the mean high, 64.26°F. Even during the summer month air filtration through the openings of the cave area is 32°F., owing to accumulation of snow in the glory hole and in Part to glacial ice, which, combined with a rock temperature of 39°F. on the upper levels (elevation 11,945 ft.) and 42°F. on the main haulage level (elevation 11,470 ft.], makes it difficult to maintain a comfortable working temperature. The one advantage in ventilation of mine workings at the altitude of the Climax mine is that the power required to circulate a given air volume is 32 per cent less than would be required at sea level. Problems since 1936 the mine management has studied intensively plans for providing adequate ventilation for the entire mine for its expected life. As the ore breaks into large pieces, much secondary blasting is necessary, therefore there is a considerable amount of smoke, gas and dust, which requires circulation of a large amount of air to remove the contamination, It is undesirable to use haulage drifts and manways as air passages because some would be passageways for contaminated air also, and there would be undesirable high velocities in some drifts. High velocities and large volumes of subfreezing air dry out the passageways through which they pass, and thus increase the amount of dust. Regulating doors in haulage drifts are difficult of upkeep and interfere with production. It was decided as a general principle to distribute fresh air to each working place at low velocities and low pressures and to remove contaminated air as soon as possible with a minimum of travel through working places.

Jan 1, 1943

Feb. 18 to. 21, 1918 Committee on Arrangements J. E. JOHNSON, JR., Chairman BRADLEY STOUGHTON, Vice-Chairman A. R. LEDOUX RALPH W. DEACON F. T. RUBIDGE L. W. FRANCIS E. M. SHIPP MRS. S J. JENNINGS J. V. N. DORR A. L. WALKER G. D. VAN ARSDALE R. M. RAYMOND Finance Committee ALBERT R. LEDOUX, Chairman WALTER H. ALDRIDGE J. H. JANEWAY GEORGE D. BARRON CHARLES F. RAND WALTER DOUGLAS BENJAMIN B. THAYER

Jan 4, 1918

By R. E. Collins, Paul B. Crawford

Mathematical equations have been derived to show the effect of the slippage phenomomenon (Klinkenberg effect) on unsteady-state gas flow through porous media. The assumption is made that the slippage may be represented by an equation of the type It is pointed out that most of the existing data on unsteady gas flow may be corrected for slippage by a simple change in definition of the dimen-sionless groups. INTRODUCTION Several solutions to the various problems associated with the unsteady-state flow of gas through porous media have been recently presented in the literature.','" The cited publications have resented solutions for flow under ideal conditjons. The principal assumptions involved include: (a) the density of the gas obeys the perfect gas law; (b) the viscosity of the gas is constant; and (c) the gas permeability is constant. Few, if any, actual gases under reservoir conditions are believed to conform with the above, but the ideal solutions do provide the basis for making improved estimates on the performance of gas reservoirs. The purpose of this paper is to show the performance characteristics when assumption (c) is corrected for the slippage phenomenon or the Klinkenberg effect. This is believed to be a step nearer to reality. MATHEMATICAL DEVELOPMENT Case 1. Gas Flow — Ideal Conditions The equations describing the flow of gas under ideal conditions have been clearly presented in the cited literature; however, for completeness of this work they are repeated here. The basic differential equation describing the flow of gas is Equation (6). It may be derived as follows: The continuity equation, the perfect gas law and Darcy's law are combined to give: Manuscript received in the Petroleum Branch office Aug. 3, 1963 or If — is constant, Equation (5) is rewritten to form the basic Equation (6). or for the linear case A dimensionless equation is obtained by dividing through by (pl)z and making the substitutions shown below: The resulting equation is A similar procedure for the radial case leads to the following equations: where and Equations (11), (12), and (13) are those used by Bruce, et al., and Jenkins and Aronofsky for their computational work.

Jan 1, 1953

By J. A. Fellows, Earnshaw Cook, Howard S. Avery

HEAT-RESISTANT alloys of the higher nickel and chromium ranges have been empirically developed through the practical experience of the past two decades to a position of significant industrial importance. Few quantitative metallurgical data have been published, however, that could be related directly to engineering specifications and design. Inadequate information led to the inauguration, in 1934, of a research directed toward a better understanding of the properties and performance of these steels at temperatures between 1400° and 2000°F. Investigation was concentrated upon the 26 per cent Cr:12 per cent Ni type, which owes its extensive application to an excellent combination of economy, strength and surface stability at elevated temperatures. The requirements of the oil-refining industry have been prominent in influencing the scope and evolution of the program. Creep strength at the maximum allowable deformation ranges has been employed to evaluate the merits of these alloys. Permissible elongation rates vary from 1.0 per cent in one million hours for turbine blades to 1.o per cent in ten thousand hours for tube supports and heating-furnace equipment. Throughout this paper, the limiting creep stress (L.C.S.) for a given temperature has been defined as the stress that will produce a uniform elongation rate (stage II) of one per cent in ten thousand hours as extrapolated from rates per hour or tests of less than two thousand hours duration. Certain current specifications require a minimum L.C.S. of 1600 lb. per sq. in. at 1800°F., of 3600 lb. per sq. in. at 1400°F., and include a tensile acceptance test at room temperature, after aging for 24 hr. at 1400°F., as a measure of embrittlement in service. An elongation of 4 per cent is considered satisfactory for general use, while a minimum of 9 per cent is prescribed on occasion. Many differences of opinion concerning the properties and performance of these alloys appear to result from their sensitivity to unappreciated variations of chemical analyses which, for example, may change their L.C.S. from 3500 to 350 lb. per sq. in. at 1800°F. Within broad chemical limits, it is possible to balance the six or more important elements present to attain desirable properties with a number of different combinations. One method for adjusting the composition has been described under the sponsorship of the Alloy Casting Institute,1 in which, by maintaining a substantially austenitic* alloy, optimum creep strength and minimum tendency to embrittle after aging are expected. Unless, however, the limits are undesirably dose, it has not been possible to ensure a moderate range of strength and of ductility by any chemical specification alone. There is a definite need

Jan 1, 1942

By Earnshaw Cook, J. A. Fellows, Howard S. Avery

Heat-resistant alloys of the higher nickel and chromium ranges have been empirically developed through the practical experience of the past two decades to a position of significant industrial importance. Few quantitative metallurgical data have been published, however, that could be related directly to engineering specifications and design. Inadequate information led to the inauguration, in 1934, of a research directed toward a better understanding of the properties and performance of these steels at temperatures between 1400° and 2000°F. Investigation was concentrated upon the 26 per cent Cr:I2 per cent Ni type, which owes its extensive application to an excellent combination of economy, strength and surface stability at elevated temperatures. The requirements of the oil-refining industry have been prominent in influencing the scope and evolution of the program. Creep strength at the maximum allowable deformation ranges has been employed to evaluate the merits of these alloys. Permissible elongation rates vary from 1.0 per cent in one million hours for turbine blades to I .o per cent in ten thousand hours for tube supports and heating-furnace equipment. Throughout this paper, the limiting creep stress (L.C.S.) for a given temperature has been defined as the stress that will produce a uniform elongation rate (stage 11) of one per cent in ten thousand hours as extrapolated from rates per hour for tests of less than two thousand hours duration. Certain current specifications require a minimum L.C.S. of 1600 lb. per sq. in. at I800°F., of 3600 lb. per sq. in. at 1400°F., and include a tensile acceptance test at room temperature, after aging for 24 hr. at 1400°F., as a measure of embrittlement in service. An elongation of 4 per cent is considered satisfactory for general use, while a minimum of 9 per cent is prescribed on occasion. Many differences of opinion concerning the properties and performance of these alloys appear to result from their sensitivity to unappreciated variations of chemical analyses which, for example, may change their L.C.S. from 3500 to 350 lb. per sq. in. at 1800°F. Within broad chemical limits, it is possible to balance the six or more important elements present to attain desirable properties with a number of different combinations. One method for adjusting the composition has been described under the sponsorship of the Alloy Casting Institute,' in which, by maintaining a substantially austenitic* alloy, optimum creep strength and minimum tendency to embrittle after aging are expected. Unless, however, the limits are undesirably close, it has not been possible to ensure a moderate range of strength and of ductility by any chemical specification alone. There is a definite need

Jan 1, 1942

By J. A. Fellows, Earnshaw Cook, Howard S. Avery

Heat-resistant alloys of the higher nickel and chromium ranges have been empirically developed through the practical experience of the past two decades to a position of significant industrial importance. Few quantitative metallurgical data have been published, however, that could be related directly to engineering specifications and design. Inadequate information led to the inauguration, in 1934, of a research directed toward a better understanding of the properties and performance of these steels at temperatures between 1400° and 2000°F. Investigation was concentrated upon the 26 per cent Cr:I2 per cent Ni type, which owes its extensive application to an excellent combination of economy, strength and surface stability at elevated temperatures. The requirements of the oil-refining industry have been prominent in influencing the scope and evolution of the program. Creep strength at the maximum allowable deformation ranges has been employed to evaluate the merits of these alloys. Permissible elongation rates vary from 1.0 per cent in one million hours for turbine blades to I .o per cent in ten thousand hours for tube supports and heating-furnace equipment. Throughout this paper, the limiting creep stress (L.C.S.) for a given temperature has been defined as the stress that will produce a uniform elongation rate (stage 11) of one per cent in ten thousand hours as extrapolated from rates per hour for tests of less than two thousand hours duration. Certain current specifications require a minimum L.C.S. of 1600 lb. per sq. in. at I800°F., of 3600 lb. per sq. in. at 1400°F., and include a tensile acceptance test at room temperature, after aging for 24 hr. at 1400°F., as a measure of embrittlement in service. An elongation of 4 per cent is considered satisfactory for general use, while a minimum of 9 per cent is prescribed on occasion. Many differences of opinion concerning the properties and performance of these alloys appear to result from their sensitivity to unappreciated variations of chemical analyses which, for example, may change their L.C.S. from 3500 to 350 lb. per sq. in. at 1800°F. Within broad chemical limits, it is possible to balance the six or more important elements present to attain desirable properties with a number of different combinations. One method for adjusting the composition has been described under the sponsorship of the Alloy Casting Institute,' in which, by maintaining a substantially austenitic* alloy, optimum creep strength and minimum tendency to embrittle after aging are expected. Unless, however, the limits are undesirably close, it has not been possible to ensure a moderate range of strength and of ductility by any chemical specification alone. There is a definite need

Jan 1, 1942

By Thomas Read

SUMMARY THE cost of labor turnover in industry is so large as to justify the adoption of almost any means to bring about its reduction. Intensive study has shown that faulty methods of hiring and discharging men is the most important factor in labor turnover. Complete control over hiring and discharging by the foreman is a relic of outgrown industrial conditions; centralized hiring permits this work to be put on a scientific basis and also does away with many serious evils that cannot otherwise be reached. Centralized hiring does not impair the authority of the foreman; he hires his men from the employment office and discharges them back to it, instead of from and to the street. The employment manager, being a direct representative of the employer, tends to restore the former relation of direct intercourse between employee and employer that was helpful in avoiding friction between them. Being a specialist, he is able to bring special knowledge and skill to bear upon the task of selling employment in his concern to desirable workmen; lie is also able to give the foreign workman the special attention he requires. Employment managers have been used for the past few years by a number of large organizations, a few of which are engaged in the mining and metallurgical industries. They have invariably reduced labor turnover, in some cases to as little as one-tenth of what it had been. So great a reduction is due in part to other changes made in the light of the data made available by scientific study of the labor problem. In my former paper on personnel work1 I advocated the more general use of the employment manager in mining and metallurgical enterprises as a means of reducing labor turnover. The form of organization recommended seems not be to understood by all, and I have requested the privilege of explaining it at greater length, since it is perhaps the most important factor of all in personnel work, and has a vital influence on the cost sheet of every industrial enterprise.

Jan 2, 1918

By H. l. Burghoff

DURING the course of preparation of crystals of alpha brass for an investigation of their creep characteristics, a number of critically oriented crystals were produced. In each of these specimens, P0, the specimen axis, lay near some important crystallographic direction or on or near the border of two possible slip systems. Because of the unusual nature of their orientations, it was considered of interest to deform these speci-mens in simple tension and to study orientation changes and any unusual occurrences, different from what would be expected for specimens in which only one slip system had distinctly the highest maximum resolved shear stress. Choice of actual operating slip system in a crystal offering an immedi-ate possibility of two slip systems would be expected to be due to chance, defect, or some inhomogeneity. Even in an ideally perfect crystal so oriented, the natural oscillations of the atoms about their lattice positions would give rise to a condition wherein one slip system would be favored over the other at the critical shear stress. In the large, nonperfect crystals of the present investigation, slip on both systems, but in different portions of the specimen, might occasionally be expected.

Jan 1, 1940