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By W. J. Feuerstein

STRUCTURAL imperfections in crystals, in recent years, have received the attention of metallurgists concerned with single-crystal properties. Certain etching solutions cause local variations in the rate of etching at dislocations.' Dislocations are expected to be preferred segregation sites for impurities' and Dash" has shown that precipitation of copper occurs preferentially at edge-type dislocations in silicon. Diffusion rates along dislocations are probably higher than rates through more perfect crystalline regions.' These and other phenomena which may be influenced by dislocations may be studied by revealing dislocations as etch pits. This study was undertaken to develop an etch solution for silicon crystals to reveal low-angle grain boundaries associated with dislocation arrays and also etch pits with good contour definition. Additional etches have been reported by Dash," Vogel and Lovell.T rystals were sectioned on crystal lographic planes at various angles from the growth direction for microscopic examination of the etch pits. Experimental Crystals of 75-100 g mass and 3 cm diam were oriented and cut on crystallographic planes. Crystals were grown by Czochralski technique from a quartz crucible. Lapped wafers were chemically polished in a modified CP-4 etch for 1 min (bromine was deleted from the etch solution). The polished wafer was then etched* at room temperature for 5 min. The use of larger amounts of H2O and/or CH2COOH slows the reaction. The Cu(NO3),.3H2O was added to increase the reaction rate and give more definition to the etch pits developed. Some pertinent features concerning the attack of this etch on silicon can be summarized as follows:

Jan 1, 1959

The United States Coast and Geodetic Survey has announced the completion of a new outline map of the United States on the Lambert conformal conic projection, scale 1-5,000,000. This map is intended merely as a base to which may he added any kind of special information desired. The shore line is compiled from the most recent Coast and Geodetic Survey charts, state names and boundaries, principal rivers, capitals, and the largest cities in the different states are also embodied. The value of the new outline map on the Lambert projection can best be realized when it is stated that it shows that throughout the largest and most important part of the United States, that is, between latitudes 30 ½ and 49°, the maximum scale error is only 0.5 per cent. This amount of scale error of 0.5 per cent. is frequently less than the distortion due to the method of printing and to changes from the humidity of the air. Only in southernmost Florida and Texas does this projection attain its maximum error of 233 per cent. The map measures 25 inches by 39 inches and will be sold by the Government at 25 cents.

Jan 7, 1919

Mills Day left a journal of his travel to Ohio and return by way of Pittsburgh in 1810. He left this comment about western Pennsylvania: "June 19. As I proceeded toward Pittsburg, (From Washington and Canonsburg) the country grew more populous. The hills appeared to consist of strata of freestone, iron, coal, and slate. June 20. Its (Pittsburg's) water communication with a vast extent of country and the immense beds of coal in its immediate vicinity render it a place peculiarly adapted to manufactures. Coal may be obtained of a good quality, ready delivered at 5 cents a bushel."1 Until within a year or so of this period, coal was used for domestic purposes, brick-making, by blacksmiths, etc.; now the industry entered a period of rapid growth caused by the introduction of the steam engine. As manufacturing was increasing due to the settlement of the western country, the additional facilities created by mechanical power were welcome. Apparently the first engine was installed in Pittsburgh, in a steam grist mill, in 1808; it is described in the Navigator of 1811: "The water of the boilers are heated by large fires made of stone coal, which is introduced at one end into a grated fire place as long as the cylinders themselves; the quantity of coal consumed daily by these boilers is said to be about twenty bushels, which cost one dollar." Later it mentions the effect of burning coal:

Jan 1, 1942

By J. Paces, E. Miller, K. L. Komarek

The resistivity was determined as a function of temperature over the composition range from pure cadmium to 40 at. pct Cd. Melts with cadmium contents less than 85 at. pct had negative temperature coefficients of resistinity. On cooling below a transition temperature close to the liquidus temperature, the slope of the resistivity-temperature curve changed sharply. The activation energy calculated from the slope was 0.07 ev above the transition temperature and 0.14 ev below. The resistivity vs composition curve shows two maxima corresponding in composition approximately to CdSb and Cd3Sb2. THE relationship between the structure of a liquid and that of the crystal formed on solidification is at present not well-under stood. Various experimental determinations of the properties of liquids indicate that deviations from random atomic arrangements in liquids occur and that the properties of a solid and of its melt are closely related. Thermody-namic activities of liquids usually show negative deviations in systems where compound formation occurs in the solid,' and X-ray data indicate that close-packed solids and their melts frequently have nearly the same coordination number. Electrical resistivities and viscosities of liquids frequently exhibit maxima at compositions corresponding to compounds in the solid state. It should be of interest to study systems which have both stable and metastable compounds in the solid, and to determine if the short-range order in the liquid is affected by the existence of the metastable solid phase. The Cd-Sb system exhibits such a metastable phase. The phase diagram is shown in Fig. 1.3 The stable system has one intermetallic compound, CdSb, crystallizing in the orthorhombic crystal structure, with a melting point of 456°C. The metastable system also has one compound, Cd3Sb2, melting at 420°C and crystallizing in the monoclinic structure. Metastable alloys transform to the stable crystal structure in the temperature range from 250o to 350°C. Several distinct indications of very strong short-range order in the liquid phase have been reported in this system, with a close relation between the ordering in the liquid and the existence of both the stable and metastable solid phases. Scheil and Baach4 have observed distinctly different vapor pressures for liquid Cd-Sb alloys depending on whether the liquid solidified to the metastable- or stable-phase configuration. They observed an unusually sharp increase of the activity in a limited temperature interval immediately above the liquidus temperature of stable alloys, followed by a sudden decrease in slope to what they considered normal values. On cooling, the activity data reproduced the values in the normal range but then deviated from the values obtained on heating. They also observed that specimens of the stable phase upon melting and resolidifying always crystallized in the stable crystal structure as long as the melt was not heated to more than 485° to 525°C; otherwise solidification to the metastable phase occurred. However, in a later investigation, these results were not reproduced (13). The resistivity of liquid Cd-Sb alloys has been investigated by Matuyama 5, Oleari and Fioram, 8 and Belaschenko (141, but only above 500°C, the temperature region where Scheil and Baach observed no vapor-pressure anomalies. The data of Matuyama and of Oleari and Fiorani are reproduced in Fig. 5 and show a maximum in resistivity at 50 at. pct Cd. The data of Oleari and Fiorani, however, show the maximum as being rounded, and their values in general are slightly higher than those of Matuyama.

Jan 1, 1964

By J. Suiter, H. F. Ryan

H. F. Ryan and J. Suiter (CSIRO)—In this paper the authors have presented "a physical model which has as its central hypothesis the solution strengthening of regions along grain boundaries in the order of tens of angstroms thick", and their calculations have used 40Å as the zhalf-width of this boundary region. Selection of this value by the authors suggests that they were unaware of a number of recent field-ion microscope observations of grain boundary structures (e.g., Refs. 29 and 30). The accompanying figure, Fig. 9, shows a portion of an ion micrograph of a tungsten specimen containing a grain boundary, and the regular arrangement of atoms in various crystal planes in each grain can be seen, except in the boundary zone which is not more than two atom diameters in width. Since it is expected that solute atoms will segregate only to the region where the lattice is disturbed, it would seem that a value of 4Å for the half-width of the boundary region would be more appropriate than the value of 40Å assumed by the authors. If the former value is used in Eq. [8] of their paper to obtain curves showing solute concentration in the grain boundary as a function of temperature, the resulting curves differ significantly from those obtained by the authors. Although there are only relatively slight changes in the regions corresponding to higher temperatures (i.e., grain boundary concentrations of approximately 1 at. pet), at lower temperatures the curves are no longer realistic. For example, the curve corresponding to u = 7000 cal per mole gives a solute grain boundary concentration in excess of 100 pet at a temperature of approximately 360°K, and "flattens out" at a grain boundary concentration of about 300 pet! Similar results are obtained with each of the other curves. Ion microscopy of dilute solid-solution alloys has shown that solute atoms give rise to image points which in most cases are of higher intensity than those of the solvent atoms.31 If the same behavior occurs when the solute atoms are present in much lower concentrations then ion microscopy should provide a sensitive tool for studying the segregation of impurities to the grain boundary regions. Although many grain boundaries in tungsten have been examined after different thermal and mechanical treatments, there has not been, as yet, any systematic study of such segregation. In general the micrographs show no clear indications of marked grain boundary segregation, but occasionally areas are found where the grain boundary contains an appreciable number of image points of high intensity in a very narrow zone, see Fig. 9. If it is assumed that these correspond to impurity atoms then it is possible to estimate the impurity concentration both in the grain boundary and within the body of the grains. Application of this method (to a larger area

Jan 1, 1965

By Charles Allen

THE Athens mine is in the city of Negaunee, Mich. It is one of the larger producers of soft hematite ore on the Marquette iron range. The property is held under lease by the Athens Iron Mining Co., and is operated by the Cleveland-Cliffs Iron Co., which is a partner with Pickands, Mather & Co. in the Athens company. The mine was opened in 1913, and shipments of ore commenced in 1918, the total reaching 3,063,711 tons up to Jan. 1, 1932. Diamond-drilling from surface, together with a knowledge of geological conditions in neighboring properties, gave a comprehensive picture of the location, size and shape of the orebody before shaft-sinking started. Striking east and west, the orebody entered the east boundary of the property at a depth of about 1500 ft. below surface. A pitch of 15° to the west carried it down to about 2500 ft. on the west boundary, about double the depth of that of any soft-ore property heretofore worked on the Marquette Range. The width of ore averaged close to 500 ft., and the thickness 300 feet. The depth of the deposit and its size, together with an overburden of quicksand, which in places reached a thickness of 150 ft., presented unusual mining problems. The use of a caving system made surface drainage into the orebody inevitable, because the north boundary of the deposit was a vertical diorite dike 200 ft. wide, and the south boundary a northward-dipping impervious slate. S. R. Elliott, manager of the mining department of the Cleveland-Cliffs Iron Co., who was super-intendent of the mine at that time, conceived the idea of starting at the bottom of the orebody and working upward, reversing the usual mining procedure. This innovation divided the Athens orebody into a series of steps, or blocks, the first of which was adjacent to the western boundary, and therefore in the lowest portion of the deposit. Top-slicing was to start under the capping in this first block by raising from the bottom level, and development and mining were to progress upward in successive blocks to the east. A complete description of the Athens system of mining was

Jan 1, 1933

By Charles W. Allen

The Athens mine is in the city of Negaunee, Mich. It is one of the larger producers of soft hematite ore on the Marquette iron range. The property is held under lease by the Athens Iron Mining Co., and is operated by the Cleveland-Cliffs Iron Co., which is a partner with Pickands, Mather & Co. in the Athens company. The mine was opened in 1913, and shipments of ore commenced in 1918, the total reaching 3,063,711 tons up to Jan. 1, 1932. Diamond-drilling from surface, together with a knowledge of geological conditions in neighboring properties, gave a comprehensive picture of the location, size and shape of the orebody before shaft-sinking started. Striking east and west, the orebody entered the east boundary of the property at a depth of about 1500 ft. below surface. A pitch of 15" to the west carried it down to about 2500 ft. on the west boundary, about double the depth of that of any soft-ore property heretofore worked on the Marquette Range. The width of ore averaged close to 500 ft., and the thickness 300 feet. The depth of the deposit and its size, together with an overburden of quicksand, which in places reached a thickness of 150 ft., presented unusual mining problems. The use of a caving system made surface drainage into the orebody inevitable, because the north boundary of the deposit was a vertical diorite dike 200 ft. wide, and the south boundary a northward-dipping impervious slate. S. R. Elliott, manager of the mining department of the Cleveland-Cliffs Iron Co., who was superintendent of the mine at that time, conceived the idea of starting at the bottom of the orebody and working upward, reversing the usual mining procedure. This innovation divided the Athens orebody into a series of steps, or blocks, the first of which was adjacent to the western boundary, and therefore in the lowest portion of the deposit. Top-slicing was to start under the capping in this first block by raising from the bottom level, and development and mining were to progress upward in successive blocks to the east. A complete description of the Athens system of mining was

Jan 1, 1934

By Earl A. Gulbransen, Kenneth F. Andrew

DRY oxidation of zirconium has been studied by several groups.'" The present work extends our early study1 to the high-temperature studies of Cubicciotti2 and Belle and Mallett.8 ulbransen and Andrew1 showed that the parabolic rate law fitted the 2-hr experiments between 200" and 425°C after an initial deviation. An energy of activation of 18,200 cal per mol was calculated. Cubicciotti,' in a study between 593" and 880°C, showed that the parabolic rate law fitted the data and an energy of activation of 32,000 cal per mol was calculated. In contrast to these studies on sheet specimens, Belle and Mallett3 studied the oxidation reaction on rod specimens and found a cubic rate law to fit the data.

Jan 1, 1958

This discussion of the paper of Chester W. Washburne should have been printed following the remarks of H. A. Wheeler, in Bulletin No. 100, April, 1915, pp. 835 and 836, but was inadvertently omitted. ROSWELL H. JOHNSON:-There is one reason why the hydrostatic interpretation of gas pressure is not wholly acceptable. As we go clown in the sands we seem to get excesses of gas. Particularly in this field it becomes excessive in quantity relative to the amount of water in the sand. If this holds in other fields as well it must mean that there has been an ascension of water, because these sedimentaries when laid down, were filled with connate water. If we do get an ascension of connate water, produced by some such phenomena as its expansion by heat or by the formation of new gas by pressure upon organic materials at great depth, we can hardly expect the pressure to be controlled merely hydrostatically. * In reply to Mr. Wheeler's inquiry as to gas wells with pressure higher than hydrostatic pressure, I would cite the original wells given by Orton on which he based the hydrostatic theory. He used in his calculation a head of 600 ft. above tide, assuming the outcrop of the Manitoulin Islands to be in Lake Superior, whereas the Trenton does not outcrop at Lake Superior. The Manitoulin Islands are in Lake Huron, the level of which is 580 ft. above tide. No allowance is made for the lower density of the fresher water near the outcrop, the weight taken for the whole column being the water of high density found at the wells.

Jan 5, 1915

By Frank B. Gilbreth

The problem of the crippled soldier in industry is not a problem of war work only; it is a problem of industrial development. As individuals, each one of you is seeking to provide our maimed heroes with such teaching as will render them, in the shortest possible amount of time, productive and satisfied members of the community. As individuals you are interested in the organizations that are preparing to receive these men, to train them and to place them at that work for which they are best fitted. As an organization, it is now your duty to take up the industrial end of the problem, to investigate existing conditions in the industries, to discover where the opportunities for employment lie, and so readjust industrial practice that the cripples may be utilized to their own and the community's good with the least shock to themselves or to the industries, and with the greatest amount of permanent benefit to all concerned. We have divided industrial opportunities suitable for cripples, roughly, into three classes. First, such as already exist in the industries, which can be set aside for cripples only, present occupants being transferred to other work for which they can be fitted but which is not suitable for cripple work; second, opportunities in the industrial world that, through changes in the working equipment or tools, or through appliances attached to the cripple himself, can make the cripple a competitor of the sound worker; third, opportunities not existing at present in the industries, but which could be introduced for the good of the community without placing the cripples into competition with any existing class of workers. As typical of the first type of occupations for cripples, we have mentioned that of store-keeper, of the second type that of typist,2 and of the third type that of dental nurse.3 The last occupation can be so arranged as to take from the overworked dentist the work of cleaning teeth; and

Jan 1, 1918

By Herman Dykstra, R. L. Parsons

A numerical method for solving partial differential equations in steady state fluid flow is described. This method, known as the "relaxation method," has two advantages over analytical methods: (1) practically any problem can be solved, and (2) a solution can be obtained quickly. A disadvautage is that the solution is not general. The method is applied to core analysis and relative permeability measurement to calculate constriction effects and to calculate the true pressure drop measured by a center tap in a Hassler type relative permeability apparatus. Further applications are suggested. INTRODUCTION Many problems in fluid flow cannot be solved analytically because of the nature of the boundary conditions. For many problems, however. an exact answer is not necessary because boundary conditions are not exactly defined or the parameters describing the porous medium are not accurately known. The relaxation method can be used to obtain an approximate answer easily and quickly for the flow of incompressible fluids in porous media. The method can also be used for other types of problems, such as determining the stress in a shaft under load. or the temperature distribution during steady state heat flow. In this discussion only calculations concerned with the flow of fluids in porous media will be considered. The method was introduced by R. V. Southwell in 1935.' THEORY The treatment given here follows that given by Enimons.2 Consider a porous medium to be replaced entirely by a net of tubes of equal length and uniform cross-sectional area as shown in part in Fig. 1. Assume that the net of tubes behaves exactly like the porous medium which it replaces; that is, the net can be made fine enough to reproduce exactly the porous medium. Assume also that Darcy's Law can be used to calculate the flow from one point to another point through these tubes. The flow from point 1 to point 0 is KA . ------ P-P) .......(11 where a is the distance between points: K is the "permeability" of a tube; A is the cross-sectional area of a tube; is the viscosity of the liquid in the porous medium; and (P1 — P0) is the pressure difference between point 1 and point 0. In like manner the flow can be calculated from points 2, 3, and 4 to point 0. The net flow into point 0 is Qo = KA/µa (P1 + P2 + P33 + P4-4P0) . . (2) MB For an incompressible fluid the net flow into point 0 will be zero or, Q. = 0. This says that at point 0 fluid is neither being accumulated nor depleted. 'Therefore. P1 + P2 + P3 + P4 - 4P0 = 0 .... (3) . If. now. with specified boundary conditions. the pressure i.; known at a finite number of points in a given region, as at the points shown in Fig. 1, Equation (3) will be satisfied at every point. If, on the other hand, the pressure is not known, the pressure can be guessed at these points. Then. unless the guess is perfect. Equation (3) will not be satisfied at all of the points. When Equatiol~ (3,) is not satisfietl. let d = P1 + I?, + P, + P, - If' .,....(4) where 6 is an apparent error and is called the residual at point 0. Equation (4) shows how much the pressure guess is in error at point 0 with respect to the surrounding points. A positive residual means that the pressure is too low, and a negative residual means that the pressure is too high. To bring the residual, 6. to zero in order to satisfy Equation (3). it is necessary to make changes in the pressure guesses. Equation (4) shows that a +1 change in Po will change the residual at point 0 by -4. A +1 change in the pressure at any of the four surrounding points will change the residual at point 0 by +l. Thus it can be seen that a change at any point will affect the residual at that point and the four surrounding points. By changing the pressure from point to point, all of the residuals can eventually be brought nearly to zero and the problem will be solved. This procedure is the essence of relaxation methods and is used to relax the residuals so that Equation (3) is satisfied at every point. The procedure can be most easily explained in detail by solving a simple problem. as Southwell says, "To explain every detail of a practical technique is to risk an appearance of complexity and difficulty which may repel the reader. A

Jan 1, 1951

By R. L. Parsons, Herman Dykstra

A numerical method for solving partial differential equations in steady state fluid flow is described. This method, known as the "relaxation method," has two advantages over analytical methods: (1) practically any problem can be solved, and (2) a solution can be obtained quickly. A disadvautage is that the solution is not general. The method is applied to core analysis and relative permeability measurement to calculate constriction effects and to calculate the true pressure drop measured by a center tap in a Hassler type relative permeability apparatus. Further applications are suggested. INTRODUCTION Many problems in fluid flow cannot be solved analytically because of the nature of the boundary conditions. For many problems, however. an exact answer is not necessary because boundary conditions are not exactly defined or the parameters describing the porous medium are not accurately known. The relaxation method can be used to obtain an approximate answer easily and quickly for the flow of incompressible fluids in porous media. The method can also be used for other types of problems, such as determining the stress in a shaft under load. or the temperature distribution during steady state heat flow. In this discussion only calculations concerned with the flow of fluids in porous media will be considered. The method was introduced by R. V. Southwell in 1935.' THEORY The treatment given here follows that given by Enimons.2 Consider a porous medium to be replaced entirely by a net of tubes of equal length and uniform cross-sectional area as shown in part in Fig. 1. Assume that the net of tubes behaves exactly like the porous medium which it replaces; that is, the net can be made fine enough to reproduce exactly the porous medium. Assume also that Darcy's Law can be used to calculate the flow from one point to another point through these tubes. The flow from point 1 to point 0 is KA . ------ P-P) .......(11 where a is the distance between points: K is the "permeability" of a tube; A is the cross-sectional area of a tube; is the viscosity of the liquid in the porous medium; and (P1 — P0) is the pressure difference between point 1 and point 0. In like manner the flow can be calculated from points 2, 3, and 4 to point 0. The net flow into point 0 is Qo = KA/µa (P1 + P2 + P33 + P4-4P0) . . (2) MB For an incompressible fluid the net flow into point 0 will be zero or, Q. = 0. This says that at point 0 fluid is neither being accumulated nor depleted. 'Therefore. P1 + P2 + P3 + P4 - 4P0 = 0 .... (3) . If. now. with specified boundary conditions. the pressure i.; known at a finite number of points in a given region, as at the points shown in Fig. 1, Equation (3) will be satisfied at every point. If, on the other hand, the pressure is not known, the pressure can be guessed at these points. Then. unless the guess is perfect. Equation (3) will not be satisfied at all of the points. When Equatiol~ (3,) is not satisfietl. let d = P1 + I?, + P, + P, - If' .,....(4) where 6 is an apparent error and is called the residual at point 0. Equation (4) shows how much the pressure guess is in error at point 0 with respect to the surrounding points. A positive residual means that the pressure is too low, and a negative residual means that the pressure is too high. To bring the residual, 6. to zero in order to satisfy Equation (3). it is necessary to make changes in the pressure guesses. Equation (4) shows that a +1 change in Po will change the residual at point 0 by -4. A +1 change in the pressure at any of the four surrounding points will change the residual at point 0 by +l. Thus it can be seen that a change at any point will affect the residual at that point and the four surrounding points. By changing the pressure from point to point, all of the residuals can eventually be brought nearly to zero and the problem will be solved. This procedure is the essence of relaxation methods and is used to relax the residuals so that Equation (3) is satisfied at every point. The procedure can be most easily explained in detail by solving a simple problem. as Southwell says, "To explain every detail of a practical technique is to risk an appearance of complexity and difficulty which may repel the reader. A

Jan 1, 1951

By F. D. Rosenthal, F. J. Dunkerley, G. J. Mills

Activities, free energies, and heats and entropies of mixing of liquid Pb-Zn alloys have been obtained by the electrode-potential method between 400° and 650°C. The large positive deviations observed from Raoult's law are in agreement with the phase diagram, which indicates a wide immiscibility field. A vapor-pressure method was used to extend the activity measurements to 900°C, allowing the maximum of the immiscibility gap to be estimated by thermodynamic calculation. Data on the mono-tectic and eutectic points compare favorably with previously existing work. SEVERAL long-standing methods have been in use for the study of phase diagrams from measurement of the activities of the component metals.' The use of thermodynamic analysis for interpreting equilibria data is comparatively recent, however. Such analysis is usually undertaken by first evaluating the principal thermodynamic functions as, for example, the enthalpy, entropy, and free energy of the alloy constituents. These, in turn, quite often can be correlated with the interatomic potential energies and atomistics of the system, from which a clearer understanding of the causes leading to deviations from ideal behavior is gained. The present study of liquid Pb-Zn alloys is concerned with a determination of these quantities by electrode-potential and vapor-pressure measurements, using these values in calculations involving phase equilibria and to obtain a theoretical insight into an alloy system exhibiting strong positive deviations from ideal metallic solution. A considerable portion of the previously reported work is based on thermal analysis. Supplemented by optical studies of solid alloys, these techniques have revealed the essential nature of the immiscible mixtures that are formed. It is difficult, however, using the phase-

Jan 1, 1959

By H. Biloni, H. R. Bertorello

GruZLESKI and winegard1 have recently reported on the origin and development of the cellular substructure in Sn-Cd eutectic unidirectionally grown with different amounts of constitutional supercooling (CS). This communication deals with the results obtained in a parallel study on the instability of a plane interface in Al-Cu eutectic unidirectionally grown. Similarities as well as differences with the results of these authors1 will be presented. A1-Cu eutectic alloy ingots of 99.999 pct purity were grown unidirectionally under different G/R ratios where G = thermal gradient in the liquid, R = solidification rate. The ingots were cut in slices perpendicular to the solidification axes and the substructure studied on parallel sections following the sense of growth. It was generally found that the last part of the ingot to solidify presented a well developed colony substructure as a result of impurity build up and constitutional supercooling. The results obtained were: 1) When the structure was observed with low niagnification (of the order of 150 to 300 times) the first instabilities were observed at the grain boundaries and node-like structures formed at the junctions of the growth-induced boundaries, as reported by Gruz-leski and Winegard.1 Inside the grains the first signs of instability appear later and correspond to the type shown in Fig. 1; this is a two dimensional cell substructure. ' 2) Figs. 2 and 3 correspond to the evolution from a two dimensional substructure to a cellular type. In the A1-Cu eutectic the boundaries of the two dimensional cell are always perpendicular to the laniellaes instead of parallel as in the Sn-Cd eutectic. 1

Jan 1, 1970

By AIME AIME

The following persons have been proposed for election as members or associates of the Institute during March and April, 1908. Their names are published for the information of members and associates, from whom the Committee on Membership earnestly invites confidential communications, favorable or unfavorable, concerning these candidates. A sufficient period (varying in the discretion of the Committee, according to the residence of the candidate) will be allowed for the reception of such communications, before any action upon these names by the Committee. After the lapse of this period, the Committee will recommend action by the Council, which has the power of final election.

Jan 5, 1908

By John R. Edwards

Introductory.—There are many interesting and important events connected with the petroleum problem. The remarkable men who conceived 'the thought of transporting petroleum by pipe line, conserving the byproducts of the commodity, and conducting extended investigation and research whereby the flash point of the oil was raised, its cost reduced and its supply assured, are deserving of the gratitude of this nation. It was primarily the success attained by Captain Lucas, after his comprehensive search for oil in Texas and Louisiana, that was the impelling cause which prompted the Navy Department to conduct the extensive series of liquid fuel-oil tests that were made from 1901 to 1903. The sensational discovery of oil at Spindle top made a deep impression upon Rear Admiral George W. Melville, then Engineer-in-Chief of the Navy, and the discovery of the vast oil field in Texas convinced him that, within a generation, if not within a decade, crude petroleum was going to play a very important part in warfare, and that the commodity might possibly develop into a necessary munition of war. The United States' Commanding Position as a Petroleum Producer.— In the study of the various problems relating to the world's production of crude petroleum, the position of the United States is one of commanding importance, whether viewed from the industrial or the military aspect. The present yield of this country is practically double that of the rest of the world, and, in view of the productive and prospective fields possessed by various countries, together with the comprehensive and exhaustive search that has been made throughout the world for petroleum, it is extremely probable that this lead will be maintained for the next decade. As regards the character of the crude-oil yield of different countries, America possesses the greater part of the supply that contains a paraffine base, and therefore a considerable portion at least of the American product produces the best illuminant. Of all the crude-oil distillates, kerosene is in many respects thc most important, and the Appalachian product for this purpose is favored, particularly in the Far East, above that of any other petroleum yield of the world.

Jan 1, 1915

By D. C. Hilty

C. E. SIMS*—This is a most interesting and important paper. It is important from two standpoints. First, it has as-spects of being highly accurate and therefore extremely useful to the operating man in showing how far he can go in oxidizing carbon from a steel bath while retaining chromium and the effect of temperature on this limit. Fig 5 is undoubtedly the highlight of the paper, and in checking it against available data, it seems capable of predicting actual results. The other important aspect is the apparently significant fact that reactions within a steel bath, such as between carbon and an oxide, are homogeneous reactions which do not require equilibrium with an external phase. In this case, it seems obvious that the reaction and the equilibrium established were between dissolved carbon (or carbide) and dissolved CrO. The classic reaction which requires equilibrium with solid Cr2O3, did not fit the data. It was recognition of this principle that made Fig 5 possible. G. R. FITTERER*—It might be in assuming the CrO is dissolved in the metal that you are actually approaching the correct factor for activity. If that is true and if the percentages that were used represent an equilibrium constant, this would mean, in effect, that the minimum temperature at which chromium would be reduced by an equivalent percentage of carbon would be about 2400°F from your equation. I believe that is in line with my experience particularly if you deal only with low percentages. J. CHIPMAN†—The author in discussing the equilibrium of the reaction offers two choices of explanation. One postulates an effect of chromium on the activity coefficient of carbon; it would require perhaps more data than are available to us at the present time to test this thoroughly. The other postulate which he offers is a reaction with CrO. This explanation is consistent with physical and chemical principles provided that a solid phase CrO is present, and that is essentially what he is postulating. If that oxide were present one would expect and, I think, almost require the kind of results that he obtained. The weakness of that postulate lies in the lack of confirmatory evidence regarding the presence of solid CrO as such. This should offer an interesting subject for further study. It seems a pity that the theoretical arguments revolving around CrO should have obscured for a moment the very real excellence of this paper. E. CARTER*—I think there is a problem that presents itself in practical application where the metal temperature is from 3200 to 3300 and the temperature desired in pouring is considerably less. B. M. LARSEN†—I get the impression from some of the work that was done earlier that there is probably a localized zone of high temperature at the slag metal interface which effects the removal of the carbon. Without that I wonder if the effect is possible to have a localized superheat and an equilibrium there favorable to low carbon content and

Jan 1, 1950

By Harlowe Hardinge

THE sound made by ball, pebble and rod mills has long been used by the operator as the "telltale" of their operation. The nature of this sound depends upon local conditions and the type of mill used. By experience an operator can tell whether the mill is running properly or not. Some operators are able to detect the difference in sound much better than others and get better results running the same mill tinder the same conditions. The automatic operation of a mill using sound as the fundamental means for maintaining control presents many problems. The satisfactory solution of these problems requires, for given operating conditions, a greater average output, with improved product for subsequent processing, than can be obtained by manual control.

Jan 1, 1939

By A. J. Hendron, D. U. Deere, F. D. Patton, E. J. Cording

In the design of structures founded in the near-surface rock, a distinction may be made between those problems that are related to the strength of the rock mass, and those that are related primarily to the compressibility of the rock mass. The mining engineer deals almost exclusively with problems involving strength in the design of open-pit slopes and underground openings. The civil engineer is similarly concerned with strength problems in the design of vehicular and water tunnels; underground power plants; cut slopes in rock for highways, canals, and spillways; and in the study of the sliding resistance of the foundations of gravity dams and the abutments of arch dams. Moreover, the civil engineer encounters problems in which the compressibility of the rock becomes the key element in the design. These problems include settlement of heavy structures supported on rock, deformation of the abutments of arch dams, and deflection of pressure tunnel linings. The design problems listed above are still solved largely on the basis of experience and rule-of-thumb. However, recent developments in rock mechanics give promise of providing more realistic approaches to certain aspects of the design. This paper, presents some of the more important recent developments which contribute to an understanding of rock behavior and which aid in design of rock structures. Typically, four steps are involved in the design of a structure, whether it be a machine element, a structural member of a building, or a structure in rock. These steps are listed below:

Jan 1, 1967

By AIME AIME

SOME 65 members of the Institute, including most of the Local Section delegates and several Directors and officers, were on hand for the Annual Business Meeting of the Institute held in the Engineering Societies Building on Monday, Feb. 21, at 4:30 p.m., immediately following the second session of the Local Section Delegates Conference. President Mathewson presided. The meeting was largely taken up with the presentation of committee re- ports, discussion of which was invited. F. E. Wormser presented the report of the Admissions Committee ; Philip Kraft, Papers and Publications Com-

Jan 1, 1944