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By Alan D. Hoagland

The Flat Gap mine, are important zinc deposit of the Appalachian type, is located in the Copper Ridge Belt in the Valley of Tennessee approximately 30 miles northeast of the Mascot-Jefferson City zinc district (Fig. 1). The ore is found in large stratigraphically linked deposits in solution and collapse breccias of the Kingsport, Longview and, to a minor extent, Mascot formations of Lower Ordovician age. The principal ore mineral is sphalerite and the principal gangue minerals are dolonmite and accessory pyrite. There is local minor galena and very rare barite and fluorite.

Jan 10, 1962

By P. H. Turnock, R. D. Pehlke

The effects of mutual interactions between elements on the solubility of nitrogen in liquid iron alloys containing chrormium, columbium, molybdenurn, nickel, or silicon have been determined. The equilibrium nitrogen solubilities in the liquid iron alloys were measured by the Sieverts method. The second-order effects caused by the presence of chrormium, columbium , or silicon in the melt were found to be significant. The solubility of nitrogen in liquid iron alloys containing several alloying elements has also been measured as a function of melt temperature and nitrogen pressure. The heat of solution of nitrogen in microcomponent iron alloys has been found to be a function of the logarithnz of the activity coefficient of nitrogen, irrvespectilje of the composition of the melt. The heat of solution of nitrogen in pure liquid iron was determined to be 1265 ± 450 cal per g-atom of N over the temperatxue range 1600° to 1800°. Sieverts ' law was obeyed for all melt compositions studied in the pressure interval 0.4 to 1.0 atm. The solubility of nitrogen in liquid pure iron and in many dilute binary liquid-iron alloys has been the subject of many investigations. Pehlke and Elliott' made a comprehensive investigation on this subject in which they summarized and compared previous researches. However, the practical application of these solubility studies requires prediction of the nitrogen solubility in the multicomponent alloys encountered in operating practice. The interaction parameter as defined by wagner2 has been used to predict the behavior of a solute in a complex alloy, and a modification of this approach has met with reasonable success in several instances.'1"5 The necessity for extending the nitrogen solubility data on binary alloys is caused by the lack of direct measurements of the solubility of nitrogen in molten alloy steels. A direct comparison between measured solubilities and those predicted for multicomponent alloys based on data in binary systems has been made in only a few instances, and most of these were reviewed by Langenberg,6 who developed a graphical technique for predicting nitrogen solubilities in multicomponent iron alloys. The solubility of nitrogen has also been studied over the entire Fe-Cr-Ni ternary system by Humbert and Elliott.? Both studies compared the solubilities computed from binary iron alloy data with those measured in ternary alloys in the liquid state at 1600°C. Most of the nitrogen solubility measurements referred to above were for iron alloys at 1600°C; thus, the ability to predict nitrogen solubilities in molten iron alloys has been restricted primarily to alloys at 1600°C. Recently, Nelsson8 devised an approximate method for calculating the change in nitrogen solubility in molten iron alloys as a function of temperature, but an assumption of regular solution behavior limits the applicability of the method. Chipman and Corrigan9,10 have developed an empirical correlation. based on the activity coefficient of nitrogen in the iron alloy at 1600°C, which facilitates the estimation of nitrogen solubilities at higher temperatures. This method also has limitations, due to the necessity of calculating the activity coefficient for nitrogen in a multicomponent iron alloy at 1600°C from the nitrogen solubility data for binary iron alloys. The shortcoming of such a straightforward approach to the problem of predicting nitrogen solubilities is the disregard of mutual interactions between elements in a complex iron melt. This investigation was conducted in an attempt to provide a more reliable method of predicting nitrogen solubilities in multicomponent iron alloys. The effects of the mutual interactions between chromium, nickel, silicon, molybdenum, or columbium in iron were studied, using the Sieverts' technique1,7 to measure the effects of alloy composition, temperature, and pressure on the solubility of nitrogen in ternary liquid iron alloys.

Jan 1, 1967

By J. H. Bain, D. C. Haigh, L. C. Parsons

Jan 1, 1964

By Cyril Smith

SEVERAL investigators, mainly concerned with the mechanical proper-ties of the alloys, have studied the so-called aluminum bronzes after various quenching and reheating treatments. Of these works, perhaps the most complete is that of Bouldoires,1 who studied changes of length, electrical conductivity, thermoelectric force, hardness and micro-structure oh tempering quenched alloys containing 5 to 20 per cent of aluminum, although the work of Carpenter and Edwards,2 Curry,3 Greenwood,4 Braesco,5 Matsuda;6,7 Grard8 and others has added much to our knowledge of the changes occurring during tempering. The so-called acicular ß decomposes on tempering at temperatures between 350° C. and the eutectoid, giving rise to a Widmanstätten structure of a needles in a matrix of d or fine a + d, associated with an increase in hardness and almost complete loss of ductility. Matsuda, studied the' eutectoid transformation by means of dilatation and electrical "conductivity measurements during cooling at different rates. He found that on cooling at the rate of 10° C. per minute there was a decrease in electrical resistance and in length instead of the usual increase which occurred with slow rates of cooling. On tempering the rapidly cooled samples, the increase commenced at about 400° C. and at 520° C. the resistance and length had reached the equilibrium values. These peculiarities he accounted for as being due to a transitional phase ß' being formed, ß having an electrical resistance and volume less than either ß or a + d.

Jan 1, 1933

By Donivan L. Gordon, Fred H. Dorheim

Often, as viewed by the public and many in the mining industry, abandoned limestone and gypsum quarries offer a simple, economic solution to the twofold problem of solid-waste disposal and land reclamation. In a state where about 75% of the existing quarries are in hydrologic connection with carbonate aquifiers the rationale for considering the storage of solid waste in them must be critically examined. Consistent with the requirements of water resources protection, criteria are suggested to evaluate the potentiality of using abandoned limestone and gypsum quarries as sanitary landfill sites.

Jan 1, 1975

By R. W. Raymond

I have the pleasure of exhibiting samples of the rock in which the South African diamonds are said to occur, for which I am indebted to Mr. Franz Groeger, of Vienna, formerly an assistant of the Royal Imperial Geological Institution, whose account of the general geology of Southern Africa was contained in a recent number of the proceedings of that Institution. The rock is apparently a sort. of tufa, evidently of volcanic origin. Mr. Groeger assured me that it could be seen in situ, bounded by uplifted stratified rocks; and that diamonds had been mined from it, by means of shafts, some distance below the surface. Groeger calls it " greenstone-tufa," and says of it, in the proceedings of the Geological Institution, " it breaks through the younger members of Group III [lower Trias and Jura], .... and crops out in oval masses, filling fissures.....The occurrence of this tufa is not locally limited, but has been traced and proved already over a large territory." Dr. Hunt remarked that the material looked like the trass of the Rhine region. He thought it a new occurrence for diamonds. He believed diamonds to belong to ancient crystalline rocks, although these materials might be brought up by volcanic agency, and the diamonds remain unaltered. In the volcanic rooks of Auvergne, crystals of sapphire, zircon, and spinel are found; and yet no one supposes that these minerals have been generated by volcanic agency. He had had a conversation with Bertrand de Lorn on this subject, who agreed with him that these minerals, being hard and resistant,

By S. Whinery

In these times of sharp rivalry, both as to price and quality, among the makers and venders of engineering explosives, it is often desirable to be able to determine the relative energy or value of the various explosives offered for sale, in order to purchase intelligently ; or, having contracted for a large amount of an explosive of a certain standard quality, to be able to ascertain if the manufacturer keeps his product up to the specified standard. The simple and inexpensive apparatus described below was devised by the writer while engaged on the improvement of the Tennessee River, at MuscleShoals, under the direction of' Major W. R. King, U. S. Engineers, in the summer of 1879. It answered the purpose so well that it is thought that a brief account of it may be of interest to other engineers. It consisted, essentially, of an old blacksmith's anvil and a common striking hammer, such as is used for driving rock-drills. The anvil was placed face downward on solid, level ground. In what was then the top of it, a vertical hole, one and one-fourth inch in diameter and about one arid three-fourths inch deep, was made with a ratchetdrill. The surface of the anvil immediately around the drill-hole was made as true and smooth as possible with a file. Next, a new striking-hammer, weighing nine pounds, with a turned and true face, was selected ; and a handle, eleven feet long and about one and a half inches in diameter, was fitted into it so that it

Jan 1, 1886

By Robert Linton

The Sierra Consolidated Mines Co., organized in 1909, owns, together with other holdings, practically all of the productive mineral area in the Ocampo district. Lying within this area are 15 mines, large and small, that hid previously been worked and appear to have yielded, since the discovery of the camp, about 100 years ago, bullion of a total value of over $50,000,000. The deepest mine, the Santa Juliana, had been worked to 1,100 ft. below the outcrop. The reopening of the mines involved, first, extensive and thorough development to open up the known ore shoots at greater depth and explore the ledges for additional shoots, and, second, a revision of existing equipment and methods, so as to increase output and reduce cost of production. This paper will give some account of the metallurgical treatment and a description of the new mill to be built at El Salto. The Ore The ore is practically all argentite, Ag2S, with some associated gold, and carried in a siliceous gangue. The typical ledge matter is an ande-sitic breccia cemented with quartz, or quartz stockwork in andesite.l The proportion by weight of silver to gold averages about 60 to 1. The silver sulphides occur ordinarily in rather fine. dissemination, sometimes not being easily discernible with the naked eye, even in ores of very good grade. The ledges also contain considerable pyrites, which as a rule is barren. "Bronce" is the local term applied to such barren pyrites, and "Pasta" to such as carries values.

Jan 1, 1915

By Fred P. Dewey

IN preparing material for the exhibit of the National Museum at the New Orleans Exposition in 1881, it was decided to attempt to photograph the interior of a coal-mine, in order to get a strictly truthful representation of a thick coal-seam, and to show incidentally the methods of mining. While we have many drawings, both mechanical and artistic, illustrating the subject, they are not satisfactory for these purposes, simply because they are drawings. Aside from this, much interest attaches to pictures of inaccessible places, and the enlarged copies (30 inches by 40 inches) of the photographs we succeeded in obtaining, have attracted a large amount of attention from the visitors to the Museum. The Kohinoor colliery, Shenandoah City, Pa., was selected as most suitable for the attempt, principally on account of the fine exposure of the Mammoth bed, and the comparatively level character of the workings, in that colliery. This is one of the many anthracite-mines of the Philadelphia and Reading Coal and Iron Company. A detailed section of the fiftyfoot or Mammoth bed in this colliery is as follows: Feet. Inches. 1 0 Clod. 1 7 0 Coal. 1 0 Slate. Top Split. 8 0 Coal. 1 6 Slate divider.* 6 0 Coal. 1 0 6 Slate. 2 6 Coal. 0 5 Slate. 1 8 Coal. 1 2 Charcoal. 5 0 coal. 1 0 Bone and Coal. „ „ Coal. [ Bottom Split. 0 6 Bone and Slate. 3 0 Coal. 0 10 Bone and coal. 1 2 Coal. 0 2 Bone. 4 4 Coal. 0 1 Bone. 0 8 Coal.

Jan 1, 1888

By J. E. Hilliard, H. E. Cook

It is shown that for systems having a miscibility gap the spinodal composition (c,) in the vicinity of the critical temperature (Tc) is related to the equilibrium composition (c,) by where cc is the critical composition. This expression is exart for the limit T — Tc and is a good approximation down to (T/Tc) - 0.9. If the miscibility gap meets the composition of the pure components THE recent theoretical treatment by cahn1,2 on spinodal decomposition of solid solutions has revived interest in methods of estimating the chemical spinodal, * i.e., the locus on a binary phase By use of the appropriate expression, the spinodal can be drawn on the Phase diagram almost by inspection with an accuracy comparable to that of lengthy calculations in which a free-energy function is fitted to the phase diagram. Satisfactory agveemenf is also obtained with spinodals comPuted from experimental free-energy curves. where G is the Gibbs free energy of the homogeneous solution and c the atomic fraction of component 2, the derivative being evaluated at constant temperature (T) and pressure (P). (These subscripts will hereafter be omitted from the partial derivatives.) If experimental measurements of G as a function of c and T are available in a single-phase region above the spinodal, then these can be extrapolated to obtain a series of metastable free-energy isotherms in the two-phase region, and from these isotherms a series of spinodal compositions can be calculated. Because the value of is very sensitive to experimental errors, an elaborate analytic procedure is required for

Jan 1, 1965

By Edward C. Morse

The metallurgical history of Republic has been completely reviewed in a paper presented at a previous meeting of the Spokane Local Section by Professor Thomson;' therefore, the present paper will be confined to matters directly pertaining to the San Poil mill: When I came to Republic last fall to look over the situation there was a plant in operation successfully treating the tailings from one of the earlier mills in the camp. I refer to the mill of the Rathfon Reduction Co. This mill was operating in accordance with modern cyaniding practice, and I was given to understand that the work was very satisfactory and profitable, else it would not have been continued as long as it was. At that time I obtained much metallurgical information of value from Harry W. Newton, Superintendent of the mill of the North Washington Power & Reduction Co. I took a number of samples from the San Poil mine, with the view of determining if Mr. Newton's experience with the ores from the other mines applied to the San Poil ores. I made a large number of tests under a variety of conditions, and found that it was possible to extract as high as 98 per cent, of the values from San Poil ore by the laboratory-tests when the ore was pulverized to 200-mesh and treated with a solution of a strength of 5 Ib. of KCN to the ton. A fairly strong solution was required because of the proportion of silver in the ore, which makes it, from a metallurgical point of view, practically

Jan 1, 1913

By A. M. Ross

DEURING the past year the uranium milling industry has seen the installation and initial operation of solvent extraction circuits in the Climax Uranium Co. mill at Grand Junction, Colo.; the Kerr-McGee Oil Industries mill at Shiprock, N. M.; and the AEC pilot plant at Grand Junction, operated by National Lead Co. Inc. The Vitro Uranium Co. mill in Salt Lake City is converting to solvent extraction, and the new Union Carbide Nuclear Co. mill to be constructed at Rifle, Colo., will also employ this method. Solvent extraction circuits will be incorporated in two mills now under construction -the Texas Zinc Minerals Co. mill at Mexican Hat, Utah, and the Gunnison Mining Co. mill at Gunnison, Colo. In Canada the expansion of the Eldorado mill at Port Radium includes installation of a solvent extraction circuit. Solvent Extraction Process: In simplest terms, the organic solvent is mixed with leach liquor and then the organic and aqueous phases are allowed to separate. By this contact the solvent selectively extracts uranium from the liquor, leaving a raffinate, or barren leach liquor, which may be discarded. The pregnant solvent is stripped of its uranium by con- tact with a stripping solution, such as aqueous sodium carbonate, which has a greater affinity for uranium than the solvent does. The barren solvent from the stripping step is available for further leach liquor extraction, and the pregnant stripping solution, which usually contains 30 to 60 g U3O8 per liter, is ready for precipitation of a final product, or uranium concentrate.

Jan 9, 1957

By Cyril Smith

A COMPLETE discussion of the literature on the subject of the influence of copper on iron and steel will be published elsewhere.1 The present paper is concerned especially with the precipitation-hardening of copper steels, and brief mention will be made here only of the work of Kin-near,2,3 Nehl4 and Buchholtz and Koster,5 who alone have studied this phase of the subject. Kinnear found that normalized low-carbon steel castings containing about 1.0 per cent copper on drawing at temperatures in the neighbor-hood of 530° C. (1000° F.) increased in tensile strength and yield point, with little decrease in ductility. The maximum effect was obtained with about 0.9 to 1.0 per cent copper, and when the copper exceeded 3 per. cent no improvement occurred on reheating. Kinnear did not study the effect of time of reheating-an all important factor where precipitation is concerned. Nehl,6 who apparently was unaware of Kinnear's work, recognized the change as due to precipitation and studied the interdependence of time and temperature of reheating, the temperature of the initial solution heat treatment, and the speed of cooling necessary to retain the bulk of the copper in supersaturated solu-tion and to give an increase in hardness and tensile strength on reheating. Nehl found that if the final rolling or forging temperatures exceeded 700° C. (1300° F.) it was not necessary even to normalize the steel, but full precipitation occurred on merely reheating the forged or rolled shapes at 500° C. (930° F.).

Jan 1, 1933

By William Campbell

In the olden days the making of alloys was an art, and the secrete of the craft were jealously guarded. To-day it has become a science, though the old ideas in regard to the secrets and formulæ are dying hard. Modern progress may be attributed to scientific research and testing of materials, and the substitution of chemical analytical control for " cook-book " methods. We know to-day a great deal about the constitution of alloys, the reasons of the change in structure and physical properties by heat and mechanical treatment; and this new knowledge is due for the most part to the physical chemist and metallographist, who have shown us that alloys are simply solutions, and as such obey definite laws. The application of the theories of solutions and of the phase rule tells us what ought to happen when our alloys are in a state of equilibrium. The working-out of the temperature-composition diagram (thermal diagram) for numerous alloys has thrown a light on the structure and constitution which has dispelled most of the darkness in which we labored before the advent of metallography. The work began with the determination of the freezing-point curves, and here the research of Le Chatelier,' Gautier,2 Roberts-Austen,3 and the other pioneers broke the ground. Next the physical chemists, Tammann,4 Rooseboom,5 Bancroft,6 and their colleagues, showed us the complete thermal diagram and its meaning. Then the researches of Heycock and Neville7 on the Cu-Sn series and of Shepherd 8 on the

Jan 1, 1913

By J. F. Butler

Boron nitride, BN, has been identified in boron low-carbon steels by means of light microscopy, electron microscopy and diffraction, and chemical analysis. This boron nitride is responsible for strain aging suppression in these steels through the removal of nitrogen from solution; however, small oxidizing potentials which result in deboronization In the austenitic temperature range also result in boron nitride decomposition and the subsequent occurrence of nitrogen strain aging. THE addition of boron to low-carbon steels is an effective means of eliminating the detrimental effects of strain aging;',' however, the mechanism by which boron suppresses strain aging has not been established. In studying the effect of heat treatment on the strain aging of boron low-carbon steels, Butler3 found that no detectable nitrogen was present in the ferrite solid solution after various heat treatments even though the total nitrogen analyses of the steels were 0.003 pct N. Apparently the function of boron in suppressing strain aging is the removal of nitrogen from solution to form a relatively stable second phase. A clue to the identity of this phase was found by Speight4 who extracted from an aluminum-killed boron steel an acid insoluble residue which contained boron and nitrogen in proportions corresponding to the compound, BN. Shyne and Morgan5 found that the addition of nitrogen to a hardenable boron steel lowered its hardenability in a manner which suggest-d the presence of nucleating particles (presumably BN) even at high austenitizing temperatures. Although this indirect evidence for the presence of boron nitride in boron steels has been found, the compound was not identified metallographically as a separate phase in these steels. Because boron has an affinity for oxygen comparable to that of silicon,5 boron steels must be thoroughly killed with aluminum in order to prevent the reaction of boron with oxygen.7 The affinity of boron for oxygen also is demonstrated through the ease of deboronization of a boron steel in an oxidizing atmosphere. Digges, Irish, and Carwile8 found that a mixture of wet natural gas and air caused both deboronixation and decarburization of a boron steel at 1900°F. The boron content rose at the surface of the steel due to the formation of boron oxide. Shyne and Morgan9 encountered deboronization at much lower oxygen potentials; loss of boron occurred in steels treated at 1750o F under argon purified to 0.0014 pct 0, even though decarburization did not occur. Boron oxide, B2O3, is much more stable than the nitride, BN, as is indicated by the standard free energies of formation at 980oC: -235 kcal per mol of B2O3 (liquid) and -28 kcal per mol of BN (crystal). It is evident that the oxygen potential must be kept low in the presence of BN in order to prevent its decomposition and the subsequent formation of B2O3' The purpose of the work described in this paper was to identify the nitride phase responsible for the removal of nitrogen from solution and to study its stability under oxidizing conditions. IDENTIFICATION OF BN In order to identify the phase containing boron and nitrogen, several alloys high in boron and nitrogen were made up in a small vacuum furnace. In alloys 3 and 4, Table I, electrolytic iron was used as a charge material. Boron additions were made in the form of 18 pct B ferro-boron after the iron was molten. In the case of alloy 3, the charge was solidified at this point; for alloy 4, nitrogen at 1 atm pressure was admitted over the melt before it was

Jan 1, 1962

By Denton R. Wieland, Harvey T. Kennedy

The frequency of bubble formation is measured for oils from the East Texas field and the Slaughter field in cores from these fields. East Texas oil was also tested in a Slaughter core. The data checked previous results in that a definite supersatrtration may exist without the formation of bubb1es in periods of observation totaling 158 hours. Measured frequencies varied from zero at supersaturations below 14 psi to 3.1 bubbles/sec/ cu ft of rock at 40 psi supersaturation INTRODUCTION The formation of bubbles is essential in a solution gas-drive reservoir in the displacement of oil. In formations where the basic pore structure consists of fine pores or fractures connected to larger pores or crevices, bubble formation in the fine pores may be the most effective means by which the oil may be displaced, even if secondary methods are applied. The most efficient oil displacement would occur where at least one bubble would form in every pore. As the pressure decreased, the bubbles would expand, due to the gas diffusing into the bubbles, and displace the oil toward the lower pressure area around the wellbore. Kennedy and Olson' have shown that the total number of bubbles formed in a reservoir is primarily dependent upon the rate of pressure drop, the rate of diffusion of gas through oil, and surface area of the rock. The surface tension of the liquid and other characteristics of the rock may also exert an important effect, which would give a different frequency to different rocks and oils and various combinations of different rocks and oils. The purpose of this paper is to present frequency measurements on two rocks and two oils. A hydrocarbon liquid is at equilibrium with gas when it contains the maximum volume of gas in solution that it can have at the prevailing temperature and pressure. If the temperature is maintained constant and the pressure is reduced below the equilibrium pressure, the liquid is supersaturated to the extent of the difference in the two pressures until the gas comes out of solution as a free phase. As shown by previous work, and confirmed in the present investigation, the number of bubbles formed per second increases with an increase in supersaturation. Kennedy and Olson showed that a tenfold increase in the rate of pressure decline resulted in a tenfold increase in the number of bubbles formed per cubic foot of reservoir rock, e.g., for decline rates of 0.1, 1, and 10 psi/day, the number of bubbles formed per cubic foot would be 40, 400, and 4,000, respectively. For another hypothetical system, Stewart, Hunt, and Berry' estimated that for pressure declines of 0.1, 1, and 10 psi/day, the number of bubbles formed would be approximately 10, 100, and 1,000 cu ft of reservoir rock. Their value of bubbles formed is lower than given by Kennedy and Olson; however, the order of magnitude agreed satisfactorily. The rate of diffusion will also affect the number of bubbles formed. If the diffusion coefficient is high, the gas in solution in the oil surrounding a single bubble will tend to diffuse into the bubble rather than forming other bubbles. On the other hand, the formation of more bubbles will tend to occur if the diffusion coefficient is very low. In his thesis dated Aug., 1953, Wood" reports on the frequency of bubble formation in a system consisting of oil and rock from the Rangely field. In the present work, the apparatus of Wood was redesigned to allow greater precision, especially at low supersaturations, where bubble growth is slower, and detection is more difficult.

Jan 1, 1958

By D. W. Levinson, L. F. Mondolfo, N. A. Gjostein

MANY investigations are reported in the literature on the age hardening of Al-Mg-Zn alloys but most of them are concerned mainly with mechanical property changes. The present investigation was started to determine the structural changes in an AlMgZn alloy. The alloy composition was chosen in the existing phase diagram" so as to lie on the quasi-binary section Al-(AlZn)Mg Actually, it was found that the diagram as published was inexact at the lower temperatures and that the phase in equilibrium with aluminum at the lower temperatures is not the ternary compound. Technique The alloy used for the investigation was prepared from high purity materials and the resulting composition as determined by chemical and spectro-graphic analysis was: Zn, 6.17 pct; Mg, 2.13 pct; CU, 0.03 pct; Si, 0.009 pct; Fe, 0.005 pct; and the remainder, aluminum. An ingot -in. thick was cast, homogenized, hot and cold-rolled to strip 0.064-in. thick for dilato-metric and powder work, and to foil 0.005-in. thick for single crystal work. Solution treatment temperature for all specimens was 475°±5°C for periods of at least 1 hr, either in air furnaces or lead baths. Aging was done in oil or Pb-Bi baths controlled to within ±3°C. The aging was investigated at the following temperatures: room (30°), 130°, ZOO0, 260°, and 300°C. For the dilatometric study, the length changes were measured continuously, at temperature, using strips of alloy 10 in. long, shaped as channels to eliminate undesirable deflection due to bending. To compensate for thermal expansion and contraction due to the variations in the temperature of the aging baths, the dilatometers were built of the same alloy as the one being tested, with the same shape and size, but with material fully annealed. Gages on which 0.0005 in. could be read and 0.0001 in. estimated were used to measure the dilation. Length changes were also measured at room temperature. Strips approximately 10 in. long were solution-treated, quenched, and measured in a supermicrome-ter in which 0.0001 in. could be read and 0.00001 in. estimated. The specimens were immediately aged for a given time, remeasured, and then the cycle was repeated, including the solution treatment. The error of measurement with this technique was somewhat larger, but the results confirmed those obtained by continuous measurements. The sheet used for the dilatometric work was checked to determine grain orientation. Both X-rays and etching methods revealed a rather coarse grain size but only a negligible amount of preferred orientation. Thus, volume changes calculated from length changes are not invalidated by preferential orientation effects. Pieces of the sheet used for the dilatometric work were also used for the metal -lographic work. Filings for the powder X-ray study were produced from a homogenized piece of sheet. These filings were magnetically purged of iron, screened to 200 mesh, sealed in a Pyrex tube containing an argon atmosphere, and solution-treated. When quenching, the glass tube was broken, so that the powder dropped directly into cold water. After drying with alcohol, the powder was sealed into capillary tubes containing an argon atmosphere and then aged for the required times. In spite of all these precautions the three strongest lines of a( Al2o) appeared in all patterns, and were used as internal standards. By the use of these standards, accurate corrections for film shrinkage were obtained. For the back reflection patterns, annealed nickel powder was mixed with the specimen to act as internal standard. A preliminary investigation was made in small (57.3 mm diam) powder cameras. From these patterns the changes which took place in the solid-

Jan 1, 1957

Meeting of Dec. 19, 1913.-The President reported the appointment of the Committee on Junior Members and Affiliated Student Societies, and the Committee on Coal and Coke, which .appointments were approved. The President was authorized to appoint the members of a Committee on Safety and Sanitation. The President appointed the Finance Committee of the Institute as a Committee to audit the accounts of the Treasurer (By-Law V). On the recommendation of the Executive Committee, Charles F. Rand was appointed a representative of this Institute on the Board of Trustees of the United Engineering Society for a term of three years (By-Law XIV of the Institute, By-Law XI of the U.E.S.). The Executive Committee reported that it had passed the following resolutions: That the next summer meeting of the Institute be held at Salt. Lake City during Aug. 10 to 14, 1914, inclusive; That an exchange of .the Bulletin and Transactions be made with the Canadian Bureau of Mines; That a sum of $50 be contributed for the year 1914 to the Commission publishing the Annual Tables of Physical and Chemical Constants; That the Secretary be given power to reduce at his discretion the number of exchanges between the Bulletin and other publications which are not retained as a permanent part of the Library; That the contract for binding Volume XLV of the Transactions be awarded to the Butler, Ward Co., in accordance with their bid of Nov. 21, 1913;

Jan 1, 1914

By Raymond Mancha

WHEN calculating the pressure-volume characteristics of projected mine-ventilat-ing circuits by orthodox methods, certain basic assumptions are required in order to employ the various available empirical data. It is assumed, for example, that the mine air is an incompressible fluid subjected to isothermal flow, an assumption suffi-ciently accurate for practical purposes since pressure and temperature differentials are small throughout the average circuit. A more erroneous assumption, however, is that all air is accounted for as it travels throughout the mine. No attempt is usually made to evaluate stopping leakage as it occurs; instead, the air volume required at the last crosscuts is assumed to enter the mine, travel the vari-ous intake air courses intact, sweep the workings and travel out by the return air courses to the point or points of exit from the mine. Actually, there is a leakage of air from intake to return at every stopping, the quantity of this leakage depending upon the tightness of the stopping and the pres-sure difference across the stopping. Unfortunately, a lack of empirical data and knowledge of the condition of individ-ual stoppings makes an exact analysis of underground stopping leakage impossible. Generally, leakage is most severe through the old stoppings outbye the circuit. These are also subjected to higher pressure differ-ences than the newer inbye stoppings. Therefore the circuit air volume diminishes at a decreasing rate progressing from out-bye to inbye the circuit.

Jan 1, 1940

WITH the present mobilization program in full swing and the enrollment in engineering colleges dropping off, many solutions are offered to relieve the shortage of trained men in the engineering profession. Industry can absorb about 30,000 engineers annually, according to the Engineers Joint Council, and forecasts indicate that the number graduating will have dropped from 38,000 in 1951 to about 12,000 in 1954. If this condition were to continue there would probably not be enough people with technical training to run industry in four or five years.

Jan 12, 1951