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By Carl Scholz

DURING November And December, 1907, Four Serious Mine-explosions Occurred In The Appalachian Coal-Field, Which Resulted In The Loss Of Nearly A Thousand Lives And Caused An Enormous . Damage To Property. These Accidents Attracted More Than The Usual Attention; Coal-Trade And Engineering Papers Contained Many Comments And Suggestions On The Cause And Prevention Of Accidents; The Daily Press In Many Instances Condemned The Coal-Operators And Charged These Accidents To Their Negligence, Or Their Anxiety To Make Money Without Adopting Precautionary Measures. Immediately After Each Accident The Respective State ..Authorities Ordered Close Investigations To Be Made, With The View Of Establishing The Cause And Suggesting Remedies To Prevent Recurrence. Representatives Of The Technologic Branch Of The U. S. Geological Survey, To Whom The Investigation Of Mine-Accidents Had Recently Been Delegated By The Secretary Of The Interior,. Visited The Mines And Co-Operated With The Local Authorities In Their Determinations. It May Be Safe To Say Here That An Investigation Of A Mine After An Explosion Has Occurred Discloses But Little, Because. The Causes Have Been Removed And Conditions Have Been Entirely Changed. On Jan. 8, 1905, The Coal-Operators Of West Virginia Organized An Association At Washington For The Purpose Of Making Extensive Investigations, And Sufficient Funds Were Pledged To Carry Out This Work. At This Organization Meeting, The Representatives Of The Geological Survey Present Had No Suggestions To Offer As To The Cause Of These Accidents. An Examination Of The Various Reports Concerning These Accidents Indicates That The Explosions Were Caused By The Ignition Of Gas Or Dust; They Show The Point Of Origin And The Direction In Which The Force Was Expended, And Give A Detailed Description Of The Damage Done. Very Little Has Been Said As To What

Jan 7, 1908

By Thomas A. Steven

Most mineralized areas in the central San Juan Mountains, Colorado, are associated with the youngest subsidence structures in a large volcanic cauldron complex that formed concurrently with eruption of the surrounding ash-flow field. Two local types have been recognized: (1) fissure-vein deposits along faults characterized by relatively late movement, and (2) hydrothermally altered and mineralized areas associated with postsubsidence Fisher Quartz Latite centers. The first type has provided most production in the past; the potential of the second type has yet to be adequately tested.

Jan 1, 1968

By F. R. Milliken

EXPERIMENTS, in what has come to be known as flash roasting began some ten years ago. The principle underlying the operation was not a new one, but the experimental work started at that time was the first that was carried through to a logical conclusion, followed by construction and operation of a pilot plant, and then full-scale production. For a short working definition, flash roasting may he considered the instantaneous and complete oxidation of finely ground sulphide particles, partially suspended in air or gas, the oxidation reaction evolving enough heat to make the reaction self-sustaining, or nearly so.

Jan 1, 1937

THE National Coal Association held its annual meeting at Cleveland on Nov. 14-16, 1928, having changed the time from the spring to the autumn to avoid conflict with the great number of meetings ordinarily held in the spring. Institute members were \\yell to the fore in its activities, the president, E. C. Mahan (who was reelected for another term!, C. E. Bockus, treasurer, and the secretary, H. L. Gancly, being A. I. M. E. members, as are many of the directors. At the first session, our past president, S. A. Taylor, presented a 1;aper which is reprinted in part herewith. At the Thurs- day session W. D. Brennan presided, Walter Barllum led the discussion on membership, and Otis Mouser led the discussion on taxation. In the afternoon, J. P. Williams, Jr., led the discussion on research. Rembrandt Peale presided at the annual dinner in the evening. At the concluding session on Friday resolutions were adopted, among them one in which the Association "reaffirms its attitude toward proposed Federal legislation affecting the bituminous coal industry by saying that it opposes legislation which would seek to single out this industry for regulatory action. This particularly applies to such bills as S4490."

Jan 1, 1928

By ANTON GRAY

In considering the possibilities and costs of discovering minerals by exploration. mineral occurrences may be classified roughly according to the size of the target they offer to the various methods that have been used to search them out. This classification is advantageous because the methods of search which might be expected to give results in one case may be totally inapplicable in others. Mineral deposits for the most part have been found in groups, or districts, in which the individual deposits occur under the same general geological conditions and usually contain more or less the same metals. There are, also, what are apparently isolated de- posits, although if the truth were fully known many of these probably would not be isolated. These districts, such as the Belgian Congo copper fields, the California Mother Lode, and the Linares lead district of Spain, form the first division of my classification. The second division is formed of the individual deposits of these districts, for example, Kambove mine in the Congo, the Kennedy-Argonaut vein in California, and the Cruz vein at Linares. The third division consists of the separate ore bodies that make up the deposits

Jan 1, 1949

By W. D. BRENNAN

FOR a considerable number of years past, there has been a shortage of experienced coal miners at the coal mine of the Phelps-Dodge Corp. This is probably due, to some extent, to the mines being so far south of the main western coal producing regions, so that experienced men secure employment before reaching this point. These mines are at Dawson, New Mexico, which is in Colfax County, near the Colorado line. The district is known as the Raton field, and the seam being worked is known as the Raton or Blossburg seam. The mines operated are Nos. 1 to 6, 8 and 9. The daily out- put at the present time, with restricted operations, is about 4000 tons, but the daily capacity is about 5500 tons. The mines are so grouped that the coal is dumped over four tipples. The mines are about twenty-five years old and extend as much as three miles under ground; they are all drift openings, with trolley, storage battery, and mule haulage. At the same time that the shortage of miners existed there was a surplus of common labor seeking employment. We learned that the Copper Queen. Branch of Phelps Dodge Corp. conducted a training school in one of its mines which had worked out very satisfactorily, and thus gained the idea of attempting such a school in the coal mines at Dawson.

Jan 1, 1929

By F. B. Plummer

PRODUCING operations abroad during 1940 were shrouded in the fog of war. Little, if any, concrete information is available, and the data that issue from the belligerent countries are too frequently distorted for military purposes, for the volume of supply of gasoline and fuel oil has become an important strategic secret. Despite this lack of information signs indicate the spread of a slow paralysis which is gripping producing operations in foreign countries. Only in the Caribbean area are developments proceeding normally and even there the destruction of the Western European market is being seriously felt. This creeping paralysis is being brought about partly by the serious shortage of materials so necessary for drilling and other producing operations such as steel, machinery, and the like-together with a scarcity of that prime munition of war-money. Markets too have been curtailed by the operation of exchange control as all exchange is needed to support war efforts. As a result, gasoline is tightly rationed in all belligerent countries. The growing casualties in shipping are fast restricting the water-borne trade in petroleum, but have had a local stimulating effect in some areas where the risk is less or where water-borne transport can be efficiently used as for instance Trinidad and Egypt. The type of product needed for war effort, particularly the great demand for aviation gasoline, has changed the schedules of .refinery operations. As a result of all these influences the world oil picture outside the United States- has vastly changed during the year.

Jan 1, 1941

By R. A. Vandermeer, J. C. Ogle

The preferred crystallographic orientations (texture) developed in randomly oriented, poly crystalline niobium during rolling were studied by means of X-ray diflraction techniques. The evolution of texture at both the surface and center regions of the rolled strip was carefully examined as a function of increasing defamation throughout the range 43 to 99.5 pct reduction in thickness. Certain aspects of the center texture development in niobium are in agreement with the predictions of a theory by Dillamore and Roberts, but others cannot be explained by the theory in its present form. Above 87 pct reduction by rolling, a distinctly different texture appeared in the surface layers which was unlike the center texture. The present results are compared with previous results obtained from other bcc metals and alloys. RANDOMLY oriented, poly crystalline metal aggregates when plastically deformed to a sufficiently large extent develop preferred orientations or textures. In a recent review article, Dillamore and Roberts1 pointed out that the nature of the developed texture may be influenced by a large number of variables. These include both material variables such as crystal structure and composition and treatment variables such as stress system, amount of deformation, deformation temperature, strain rate, prior thermal-mechanical history, and so forth. From a practical point of view, the control of preferred orientation may often be important for the successful fabrication of metals into usable components. During the past few decades many experiments have been devoted to the study of deformation textures. This work, however, has been confined in large part to metals and alloys that have an fcc crystal lattice. By comparison, bcc metals and alloys have received much less attention, and consequently our understanding of preferred orientations in these materials is only shallow. This state of affairs worsens when it is realized that almost all of our present howledge about this class of materials derives from studies on irons and steels.' The bcc refractory metals, which are relative newcomers to the industrial world, have, on the other hand, been given at best only passing glances in the area of texture development. Our understanding of the evolution of preferred orientations in bcc metals can only remain fairly limited until systematic studies of metals and alloys other than the irons and steels have been carried out and the influence of the many variables has been determined. To that end a program was initiated to investigate in detail texture development in niobium. The present paper reports some of the results of this study. Textures were determined at both the center and surface of strips rolled variously to as much as 99.5 pct reduction in thickness at subzero temperatures. Emphasis in this paper is on texture description and on texture evolution during rolling to progressively heavier deformation. EXPERIMENTAL PROCEDURE The niobium was purchased from the Wah Chang Corp. as a 3-in.-diam electron-beam-melted billet. Chemical analysis indicated the impurities to be less than 300 ppm Ta, 40 ppm C, 10 ppm H, 170 ppm 0, and 110 ppm N. All other impurities were below the limits of detection by spectrochemical analysis. This large-grained billet was fabricated into specimen stock so that a fine-grained randomly oriented grain structure resulted. This was accomplished in three deformation steps alternated with recrystalli-zation anneals of 1 hr at 1200°C in a vacuum of low 10"6 Torr range after each deformation step. The first step was to alternately compress the billet 10 to 20 pct in each of three orthogonal directions. The second step was to compress in only two directions 90 deg apart to produce a 2-in.-sq bar. The final step was to roll this bar 50 pct to give a 1-in. by 2-in. cross section. After the final anneal, metallo-graphic examination showed the material to have an average grain size equivalent to ASTM No. 5 at 100 times (i.e., 0.065 in. diam). Specimens cut from the center and edges of this bar gave no indication of detectable preferred orientation when examined by X-ray diffraction. Samples 1.5 in. long, either 0.625 or 0.750 in. wide, and approximately 0.400 in. thick were machined from this fabricated ingot. The surfaces corresponding to the rolling planes were ground so as to be parallel. The samples were chemically polished in a solution of 60 pct nitric acid and 40 pct hydrofluoric acid (48 pct solution) prior to rolling to remove any cold work introduced in the machining operations. Rolling was accomplished with a 2-high hand-operated laboratory rolling mill that had 2.72-in.-diam rolls. Prior to operation, the rolls were polished with 600 grit paper, cleaned with acetone, and then soaked in a container of liquid nitrogen for several hours. The samples were also soaked in liquid nitrogen prior to rolling and were recooled between each pass. While some slight heating of the samples occurred during rolling, this procedure maintained the sample temperature well below 0°C at all times. The samples were rolled unidirectionally, and the rolling plane surfaces were not inverted during any phase of the operation. The draft per pass averaged between 0.010 to 0.012 in. After 96 or 97 pct reduction the draft was reduced to 0.001 to 0.002 in. per pass. Samples were rolled to various reductions in thickness between 43 and 99.5 pct.

Jan 1, 1969

By J. Nagy, D. W. Mitchell, E. M. Murphy

In 1957 research was initiated in the U.S. Bureau of Mines experimental coal mine near Pittsburgh, Pa., to study factors affecting foam generation and transport, to evaluate the effectiveness of high-expansion foam for controlling mine fires, and to develop techniques for applying the method under U.S. mining conditions. These investigations showed that high-expansion foam containing at least 0.2 oz of water per cu ft of foam is effective in controlling experimental underground fires burning coal, wood, and oil. Sometimes the fire was completely extinguished, but more often, it was brought under sufficient control to permit either a direct attack on the fire with a stream of water or loading of the hot material into cars. A progress report' prepared in July 1958 summarized the initial achievements of the USBM experiments. Since then other phases of the foam-plug method for attacking fires have been studied in the laboratory and in the mine. Previous studies by British engineers' of the foam-plug method for fighting mine fires indicated that high-expansion foam was effective in controlling experimental timber fires in an underground passageway. Their subsequent workx-1 pertained to the practical aspects of fighting large fires within a mining area with a foam-plug. CONTROLLING EXPERIMENTAL FIRES In the USBM tests foam was formed by spraying a dilute solution of a foaming agent on a metal or cotton net of 1/8 to 1/4-in. mesh. Air passing through the continuously wetted net forms bubbles of 1/2 to 11/2-in. diam and produces a honeycomb of foam that fills the passageway. Under the ventilating-air pressure, this light-weight plug moves forward through the passageways, around sharp corners, and over obstacles. as illustrated in Fig. 1. High-expansion foam was transported to a wood fire, an oil fire, and 13 coal fires. Figs. 3 and 4 show a typical coal fire before and after attack with foam. In 12 of the 15 experiments the fire was brought under control when the water content of foam was 0.2 oz or more per cu ft. A fire was considered controlled when the flames were quenched and observers could cross the area without wearing breathing apparatus or protective clothing. In the other three experiments, conducted when the water content was less than 0.2 oz per cu ft of foam, the flames were retarded but the fire was not controlled. Coal fires have been attacked successfully by foam introduced at points varying from 155 to 1010 ft from the fire. The time of burning in coal beds 10 in. thick ranged from 11/2 to 5 hrs or more. Most of the experimental fire beds were 15 ft in length. However, in one experiment a floor fire 25 ft long and 5 ft wide was constructed $5 upwind from another fire 15 ft in length; in another instance, the fire was 100 ft long and 5 ft wide. Foam was applied to the fires for periods ranging from 7 to 36 min. The time required for foam application depends on the extent of the fire, time of burning, water content of foam, foam velocity, and degree of fire control desired. In addition to the coal fires, foam was transported to a fire covering 45 sq ft, produced by 15 gal of oil burning in metal trays on the floor. The foam extinguished the oil fire in about 1 min. In one other test, the burning of 1100 lb of dry sawmill slabs stacked in open cribs 4 ft high and 16 ft long was brought under control by foam in 2 min. Composition of Gases in Return Air: In several of the experiments samples of the return air from fire zones were collected; composition of the atmosphere before, during, and after foam application was then determined. Because of condensation in the relatively cool sampling tube, the amount of water vapor was not determined. Analyses showed that concentration of carbon dioxide and combustible gases increased as the foam began passing over the fire. This resulted from the decrease in the volume of air when foam generation started and from the formation of gases when water reached the fire.* The quantity of gases generated would not be greater than that from an equivalent amount of water applied directly to the fire. The highest total concentration of combustibles (CO, CH1, and H2 mixture) obtained during the experiment was about 2 pct; this occurred 6 min after foam reached the fire. This atmosphere was nonex-plosive, but calculations show that if the air flow were reduced to about 5 fpm and if the rate of gas liberation from the fire remained constant, the mixture would be explosive. The use of foam on a fire in all probability would affect the normal ventilation of a mine. If the mine is gassy, this factor must be carefully considered before the foam is applied. APPLICATION OF THE FOAM-PLUG TECHNIQUE IN MINES Equipment and procedures for applying the foam-plug methods must be adapted to the prevailing conditions at a particular mine. Some factors to be considered in developing equipment are: size or extent of the mine, dimensions and number of entries, ventilation system, mining methods, haulage facilities, availability of water, amount of methane liberated, and existing fire-control apparatus. • In most experiments the initial air velocity of 200 fpm decreased to 50 to 100 fpm as the foam plug increased In length.

Jan 1, 1961

By R. A. Vandermeer, J. C. Ogle

Two distinct types of depth-dependent variations in texture have been observed in niobium cold-rolled various amounts up to 99.5 pct reduction in thickness. These nonuniformities are thought to be the results of nonhomogeneous plastic dewmation during rolling. The first type is characterized by a zone at intermediate depths that tends to lack certain strong orientations which are present in the surface and center layers of the rolled stock. This type of texture modification seemed to be associuted with "high" body rolling and may be related to the shape of the zone of deformation in rolling. The second type of texture inhomogeneity found involved the formation of a unique texture in the surface layers of heavily rolled strip. High fiiction forces between work piece and rolls appear to be needed to generate and maintain this texture. We believe that this unique surface texture results from a shear mode of deformation in the surface layers. THE evolution of texture in both the surface and center regions of cold-rolled niobium as a function of increasing deformation from 43 to 99.5 pct reduction in thickness was reported in a previous paper.' It was noted that for strips rolled between 95 and 98 pct reduction a distinctly different texture appeared in the surface layers which was unlike the center texture. Certain other layer to layer textural variations were also detected during the experimental phase of that work but were not described in the paper. Surface textures have been reported previously for the bcc materials iron and Steel2-4 and are well known in the fcc metals.5 It is usually stated that these are shear textures which arise under conditions of high friction between specimen and rolls. Work by Mayer-Rosa and Haessner5 n niobium rolled under conditions presumed to be high roll friction gave no indication, however, of a surface texture in that material. This is indeed puzzling in view of our results.' Thus we undertook additional experiments designed to study the stability of the surface texture for certain rolling variables. The variables investigated were the presence or absence of lubrication, amount of reduction per pass, and reverse vs unidirectional rolling. It is the purpose of the present paper to describe the kinds of depth-dependent textural inhomogeneities that we have observed in rolled niobium as well as to present the results of our recent experiments on the stability of the surface texture. Possible explanations for the depth-dependent texture variations will be discussed in terms of nonhomogeneous plastic deformation during rolling. EXPERIMENTAL Specimens cut from the niobium rolled to different reductions in the previous study1 were examined at various layer levels throughout the strip thickness for textural inhomogeneity. The specimen surfaces were either etched or machine ground and etched to remove material to a specific depth. Textures were determined by means of the Schulz X-ray reflection pole figure method with a Siemens texture goniometer and Cum X radiation. Since the important intensity peaks of the textures in niobium are usually located on the normal direction (N.D.) to rolling direction (R.D.) radius of the (110) pole figures, it was sufficient in many cases to scan only along this radius. At selected depths or where additional information was required the entire (110) pole figure was also obtained. In studying the stability and formation of the surface texture, experiments were conducted on 0.400-in.-thick, fine-grained, randomly oriented niobium specimens extracted from the same starting stock as that used in the earlier study.' Two of these specimens were rolled at room temperature to a total reduction of 96.4 pct. One was rolled between cleaned and degreased rolls with no lubrication. The other was lubricated between passes with Welch Duo Seal vacuum pump oil. The rolling schedules of each were kept as nearly identical as possible. Drafts were of the order of 0.006 to 0.012 in. per pass. Other experiments consisted of rolling specimens at constant fractional reduction per pass, i.e., (ta- tb)/ta equals a constant where ta and tb are the entrance and exit thickness of the rolled stock, rather than at a constant draft, i.e., ta- tb equals a constant. Ten specimens were rolled at room temperature on a two-high, motor-driven rolling mill with 8-in.-diam rolls. These specimens were rolled to thicknesses of between 0.041 and 0.073 in. (82 to 90 pct total reduction) at approximately constant reductions per pass ranging from 9 to 45 pct. Kerosene was used as a lubricant. Half of the specimens were always rolled in the same direction while the other half were reversed end to end at each pass. The texture in the surface regions was determined with the X-ray technique described above. RESULTS The textural inhomogeneities noted in niobium rolled from fine-grained, randomly oriented stock 1.5 in. long by 0.75 in. wide by 0.40 in. thick can be classified into two types. The first may be discussed with the aid of Figs. 1 to 3. Fig. 1 is a three-dimensional plot of the X-ray intensity in units of times random vs f , the angle from the N.D. to any point along the N.D. to R.D. radius of the (110) pole figure, and depth, given as percent of the thickness (?t/to X 100, where at is the thickness of material removed and to is the as-rolled

Jan 1, 1970

By H. H. Hausner, H. S. Kalish

M. Hansen—This paper certainly is an interesting study. Although I have not had too much experience in the powder metallurgical methods of studying phase equilibria, I would like to say the following concerning the interpretations of the results obtained: 1. The existence of a zirconium-rich eutectic having a melting point close to 950°C and containing approximately 5 pct beryllium is well established. 2. Undoubtedly sintering of the original compacts (i.e., without repressing and resintering at 1350°C) resulted in a condition being far from equilibrium, even in the low-melting point zircon-rich region where undissolved zirconium particles have been observed. This means that only partial reaction between the component powders has taken place. 3. In preparing and handling powder mixtures for pressing and sintering, we have found that with powders differing considerably in density, and also in particle size, separation in layers of different composition may occur. This means that a concentration gradient would exist within such samples. This phenomenon may, at least to some extent, account for the difference in microstructure of the top and bottom regions of some of the sintered samples. If this is the case, density figures for some of the nominal compositions would not represent actual densities of those mixtures. 4. Fig. 1 shows that the low densities of mixtures with 40 and 60 pct beryllium sintered at 1350°C are changed to much higher densities if the products sintered at 1100°C are repressed and resintered at 1350°C, whereby an approach toward equilibrium takes place. This would mean that the low density and growth in volume is due to nonequilibrium conditions. If this is true, would it be justified, then, to conclude that "the remarkable growth of the alloys in the vicinity of 40 to 60 pct Be indicates the formation of a high-melting point phase, probably accompanied by a considerable change in volume due to a large alteration of the crystal structure from that of the original compounds"? If some compound formation has taken place already during the first sintering at 950" to 1350°C, more compound would be formed by repressing and re-sintering of the 1100" samples. This treatment, however, results in higher, rather than lower, densities. In general, the density-composition curve of alloy systems containing one or more intermediate phases is characterized by a more or less defined contraction (decrease in specific volume, increase in density) over the "theoretical" density. Does not discrepancy exist between the two statements that "growth of the alloy indicates the formation of a high-melting phase . . ." and "even at 1350°C, no indications of sintering have been observed"? 5. I am not sure that the explanation given for the fact that fig. 4 did not reveal as much eutectic as the top portions of the mixture with 2 pct Be, is correct. The density of the melt containing only 5 pct Be or even perhaps less, is not too much different from that of the nominal composition. The reason might be also that there was already some separation of the components in the pressed compact. 6. I do not understand why the microstructure of the bottom regions of the compact with 5 pct Be (fig. 6) is so different from that of the top regions (fig. 5). The compact was melted on sintering at 1100°C. Its composition lies close to the eutectic point. There should be at least some lamellar structure in the bottom regions too; otherwise, the composition of top and bottom must have been very different after sintering, because the eutectic is said to extend as far as the composition ZrBe2. In case the white and gray areas of fig. 6 are both gamma, and the black areas undissolved zirconium, this composition would be close to the phase coexisting with zirconium, that is, ZrBe2, according to the hypothetical diagram, or a compound richer in zirconium. 7. Figs. 9 and 10 are not mentioned in the text. 8. The great difference in microstructure of the composition 20 pct Be of figs. 8 and 14 on one side and fig. 15 on the other side proves that sintering at 950" and 1100°C results only in partial reaction of the powers. 9. The mixture with 60 pct Be (fig. 19) seems to consist of two phases, rather than one phase, one interspersed in a matrix of another. 10. The statement that the eta phase "may be an intermetallic compound or the product of a peritectic or monotectic reaction" seems to be misleading, because the product of a peritectic or monotectic reaction in this region of the system must be an intermetallic compound. 11. If there is some solid solubility of Be in alpha and beta-Zr, it would be expected to be higher in beta-Zr (b.c.c.) than in alpha-Zr (h.c.p.). The temperature of the polymorphic transformation of zirconium then would be lowered, rather than increased. In accordance with this, Battelle has found that the transformation point of titanium is decreased by beryllium. 12. In case the phases present in alloys with 80, 90, and 95 pct Be are identical (which appears to be correct), it is striking that the relative amounts of both phases (eta and beryllium) are not too different within this wide range of composition. With 60 to 65 pct Be

Jan 1, 1951

By W. E. Quist, R. Taggart, D. H. Polonis, C. J. van der Wekken

An intermediate compound that has been identified as Niab is observed to form as a decomposition product from supersaturaled Ni-Nb solid solutions during aging at temperatures between approximately 300" and 500°C. On the basis of data from electron microscopy and selected-area diffraction, the structure of this compound has been determined as fct with a = b - 3a0 and c = a, wlzere a,, is the lattice parameter of the parent solid solution. The compound consists of close-packed layers with triangular ordering, where the niobiutrl atoms are separated by two nickel atoms ([long- close?-packed directions. A nine layer stacking sequence is required to describe the proposed structure. STUDIES of the Ni-Nb binary system have been limited primarily to phase diagram determinations,'-4 investigations of high-temperature equilibrium phases,5"1 and the determination of the influence of deformation on the structure of the equilibrium compound.8 The nickel-rich portion of the binary system is reported to be of the simple eutectic type in which the maximum solubility of 12.7 at. pct Nb occurs at 1282"c.' The two-phase field below the eutectic temperature is bounded by the a fcc solid solution and an orthorhombic Ni3Nb compound. No metastable phases have been reported in previous investigations. In transformation studies of certain nickel-base commercial alloys that contain niobium, two ordered metastable compounds containing niobium have been shown to precipitate from the solid solution, both of which have been identified as y' and have the composition NisNb or Ni,Nb. One compound has been reported to have the bct DOz2 type Al3Ti structure" and the other the cubic LI2 type Cu3Au structure.9,11 In the present work on Ni-Nb binary alloys a metastable y' compound has not been detected after conventional quenching and aging treatments. An anomalous behavior was noted in electrical resistivity measurements. in alloys containing between 7 to 12 at. pct Nb when aging treatments were performed below 500°C after fast quenching from 1250°C. Transmission electron microscopy has shown that this behavior is caused by the formation of a low-temperature precipitate of unreported structure type and composition. EXPERIMENTAL METHODS Several Ni-Nb alloys, containing up to 11.5 at. pct Nb. were prepared by either levitation melting and casting in copper molds or by induction melting in alumina crucibles; both techniques employed purified helium gas as a protective atmosphere. The purity of the nickel and niobium used to make the alloys was 99.98 wt pct Ni and 99.9 wt pct Nb. The composition and homogeneity of the alloys were checked by weight measurements and by electron microprobe analysis. The induction-melted alloys were homogenized for 100 hr at 1100°C. The resistivity specimens were prepared from rods swaged to 2.5 mm and the electron microscopy specimens were cut from sheet that was rolled to 0.4 mm and thinned using a modified Bollmann technique." The elevated-temperature solution treatments were carried out in a purified helium atmosphere followed by direct quenching into a 10 pct NaCl solution at 23°C. Additional protection against oxidation of the samples during solution treatment was accomplished by using tantalum foil as a "getter" in the furnace. The specimens were aged at various temperatures in salt baths controlled to +2oC. A Leeds and Northrup K5 potentiometer was used to make electrical resistivity measurements on specimens immersed in liquid nitrogen. Electron microscopy and diffraction studies were carried out with JEM-7 and Philips EM-200 microscopes operating at 100 kv. RESULTS AND DISCUSSION Ni-Nb alloys containing between 7 and 11.5 at. pct Nb that have been solution-treated in the range 1220" to 1280°C and quenched to 23°C undergo a precipitation reaction when aged in the temperature range 300" to 500°C. Precipitation was detected by selected-area electron diffraction after aging a specimen for as little as 30 sec at 350°C) whereas the reaction was well-advanced after aging for 150 hr at 475°C. Electrical resistivity measurements were used to monitor the progress of the precipitation reaction. In the present experiments the nucleation process for precipitation required a high solution temperature and a rapid quench into brine. The presence of aluminum, iron? and carbon in amounts totaling less than 1 wt pct was found by electron diffraction to completely suppress the formation of the low-temperature precipitate that has been detected in the binary alloy. Electron diffraction techniques were used to determine the structure of the precipitates that formed during the decomposition of the Ni-Nb supersaturated solid solutions. Figs. l(a) through l(d) show electron diffraction patterns oriented to the [loo], [110], [lll], and [I031 zone axes of the matrix. Areas of reciprocal space between these sections were investigated by slowly varying the orientations of the crystal under study; this procedure revealed no reflections other than those depicted in Fig. 1. The presence of super-lattice reflections at points coincident with the matrix reflections was confirmed by the examination of an almost completely transformed structure. On the basis of the accumulated diffraction data, the reciprocal lat-

Jan 1, 1970

By L. T. Larson, M. L. Picklesimer

The relationship between the apparent angle of rotation of monochromatic plane polarized light and the tilt of the basal pole from the surface normal has been experimentally determined for zirconium over the wavelength range of 500 to 655 mp. This relationship allows the determination of the spatial orientation of the basal pole of an individual grain in a polycvystal-ling zivrconium specimen to within ±3 deg by three simple tneasurements with a polarized-light metallurgical microscope. The method of measurement is discussed in detail. THE optical anisotropy of materials having noncubic crystal structures has long been used to reveal features by polarized-light microscopy. Petrographers have used measurements of certain optical properties to identify and classify transparent or translucent minerals. More recent work (i.e., Cameron1) has extended such measurements to opaque minerals in reflected light. Few attempts have been made to make similar measurements on noncubic metals. Couling and pearsall2 have reported that a sensitive tint plate can be used in a polarized-light metallurgical microscope to determine the position of the basal-plane trace in a grain of polycrystalline magnesium. Reed-Hill3 has reported that the same technique can be used for zirconium. We have found that the precision of measurement can be increased to about ±0.5 deg by using a Nakamura plate4,5 to determine the exact extinction position after the sensitive tint plate has been used to locate approximately the basal-plane trace. This report describes a method for measurement of another optical property, the apparent angle of rotation. This measurement permits determination of the angle between the basal pole of a grain of a hcp metal and the normal to the surface of the specimen. When the two measurements are combined, the orientation of the basal pole in space can be determined from three simple measurements on a single surface. One to two hundred such determinations will permit plotting of a basal-pole figure for the polycrystalline material with reasonable accuracy. When normally incident, monochromatic, plane-polarized light is reflected from the surface of an optically anisotropic material, the light may be converted to elliptically polarized light, the plane of vibration may be rotated, or both may occur. The el- lipticity, the angle of rotation, and the reflectivity can be related to the indices of refraction and the absorption coefficients of the material.6,7 Ellipticity values can be determined with an elliptical compensator, but not with the ease and precision desirable for the present purposes. Measurement of the angle of rotation requires only the determination of the angle from the crossed position (90 deg to the polarizer) that the analyzer must be rotated to obtain extinction when the trace of the optical axis in the surface is at 45 deg to the vibration direction of the polarizer. The angle of rotation of the analyzer is approximately 6/5 that of the true angle of rotation of the light as reflected from the specimen because there is a small amount of additional rotation produced during the passage of the reflected light through the mirror of the microscope. Since we are presently interested only in determining the tilt of the basal pole, the angle of rotation of the analyzer (the apparent angle of rotation of the light, i.e., uncorrected) can be used. Precision of the measurement can be increased substantially by the use of a Nakamura plate4,5 in determining the extinction position. In an optically uniaxial material (hcp or tetragonal crystal structure) the angle of rotation depends only on the optical properties of the material and the orientation of the optical axis of the grain relative to the plane of incidence of the plane-polarized light.7,8 Thus, in a metal such as zirconium, the apparent angle of rotation at the 45-deg position in any given wavelength of light is a direct measure of the tilt of the basal pole from the normal to the surface. If the optical properties vary with wavelength, the apparent angle of rotation for any given tilt of the basal pole will vary. None of the required information exists in the literature for zirconium nor for any other non-cubic metal. MEASUREMENTS ON SINGLE-CRYSTAL ZIRCONIUM A single-crystal sphere of zirconium 9/16 in. in diam was spark-cut from a single-crystal rod grown from iodide bar by an electron-beam zone-melting process.9 The damaged surface was removed by chemical polishing in a 45/45/10 mixture (by vol) of water, concentrated HNO3, and HF (48 pct) and then electropolishing at 50 v in a bath1' of methyl alcohol and perchloric acid (95/5 by vol) at -70-C. The single-crystal sphere was mounted in a five-axis goniometer stage having a removable eucentric X-ray diffraction goniometer head for the two inner orientation axes. The basal pole of the single-crysta sphere was aligned parallel to a third axis of the goniometer stage by using the sensitive tint method to determine the basal-plane trace at several rotational positions of the sphere. The alignment was then checked by removing the sphere and eucentric gonio-

Jan 1, 1967

By P. M. Robinson, M. B. Bever

The heats oj formation at 273°K of the compounds CdTe, I)z2Te, InTe, In2Te3. In2Te5, SrzTe, and PbTe have been rleasrred in a liquid metal solutiotz caloritrete? 1.t1itlz bismuth as solvent. The?, are iterpretecl in yelation to tlze stability and bonding of the cott/pozltzds. Tile heats of fusion atzd the melting- points of tlze cotlzpounds InTe and Itzz,Te3 1lcti.e been measured in a cotrslant-temperature gradient calorimeter. The entropies of fusion are disc,ztssecl in YIIIS 01. the degree of order in the solid at the melting point. THE heats of formation of the tellurides of cadmium, indium, tin, and lead have been measured as a continuation of research on the thermodynamic properties of compounds of tellurim.' The tellurides of these metals were selected with a view to examining the relation between the heat of formation and the position of the metal in the periodic system. The elements cadmium, indium, and tin are in the same period and tin and lead are in the same group of the periodic system. The tellurides of indium are of special interest because four compounds, In2Te, InTe, In2Te3, and InzTe5, occur in this system. The available information on the heats of formation of the compounds investigated consists of values for CdTe, SnTe, and PbTe derived from electromotive-force measurements,J a value for CdTe obtained by tin solution alorimetr, and values for InTe and In2Te3 determined by combustion calorimetry.5 These values, however, refer to various temperatures ranging from 273' to 673°K and some of the reported error limits are large. Liquid metal solution calorime-try may be expected to yield more accurate values for the heats of formation than electromotive-force measurements or combustion calorimetry. The heats of fusion and the melting points of the compounds InTe and In,Te3 were determined in a constant-temperature gradient calorimeter. No published information appears to be available on the heat of fusion of these compounds. The results reported here give an indication of the degree of order in the solid compounds at the melting point. 1) MATERIALS AND EXPERIMENTAL PROCEDURE Materials. Samples of the compounds SnTe and PbTe were obtained from the Westinghouse Research Laboratories and samples of the compound InTe from Lincoln Laboratory, Massachusetts Institute of Tech- nology. Additional samples of the compounds InTe, SnTe, and PbTe and samples of CdTe, In2Te, In2Te3, and In,Tes were prepared from 99.995 pct Cd (Baker Chemical CO.), 99.999+ pct In (American Smelting and Refining Co.), 99.99 pct Sn (Baker Chemical Co.), 99.999+ pct Pb (Fisher Scientific Co.), and 99.999+ pct Te (American Smelting and Refining Co.). Stoichiometric amounts of the component elements were melted in sealed, evacuated Vycor tubes. The melts were held at approximately 100°C above the liquidus for about 16 hr and shaken repeatedly. The melts of the compounds In2Te and InzTe5, which form by peritectic reactions, were quenched into iced water. The melts of the other compounds, which have congruent melting points, were slowly cooled to room temperature. The samples were then annealed for 5 days at approximately 50°C below their respective solidus temperatures. Metallographic examination did not reveal any evidence of second phases or segregation. At least two batches of each compound were prepared. Samples from each batch were used in determining the heats of formation and, in the cases of InTe and In,Te3, the heats of fusion. The Heats of Formation. The heats of formation at 273°K of the compounds were measured by metal solution calorimetry with liquid bismuth at 623" as solvent. In this technique, the heat of formation is determined from the measured heat effects on dissolution of the compound and of a mechanical mixture of the component elements. The difference between these heat effects adjusted for changes in the composition of the bath gives the heat of formation at the temperature from which the samples are added to the bath (273°K). The experimental technique and method of calculation have been described in detail elsewhere.= It should be emphasized that the reported heats of formation depend on the thermodynamic data used in calculating the heat effects for the calibration additions. In the present investigation, the calorimeter was calibrated by adding pure bismuth at 273°K to the bismuth bath at 623°K. The reported heats of formation are based on a value of 4.96 kcal per g-atom for the difference in the heat contents of bismuth at 623" and 273". If a new value for this quantity becomes available, the reported results may be adjusted in direct proportion. The concentration of solute in the bath at the end of a calorimetric run did not exceed 1.7 at. pct and was usually less. In this range, the heat effect on dissolution of the solute was a linear function of the concentration of solute. In determining the heats of formation of the compounds in the system In-Te, a few runs were carried out in which two neighboring compounds such as InTe and In,Te3 and the corresponding mechanical mixtures of the components were added to the calorimeter. The

Jan 1, 1967

By J. C. Bayles

Jan 1, 1886

By Lyon F. Terry

ACCEPTED current practice for A the valuation of mineral property is based upon Hoskold's theory and valuation tables first published in 1877, and popularized by Herbert Hoover's "Principles of Mining" issued in 1909. In more recent years the procedure has been developed further in the course of the extensive valuation work required for Federal taxation purposes. The 1-aluation of oil and gas properties and of mines is based upon the same principle-the estimation of the present worth of future net revenues. However, in valuing oil and gas properties the method used for discounting future revenues differs somewhat from that adopted for mines, owing principally to the nature of the re- source. production from oil and gas properties usually declines from year to year, whereas coal and ore de- posits are adapted to a more uniform rate of output.

Jan 1, 1940

By E. H. Sellards

ON Oct. 9, 1929, a sink formed in the Sour Lake salt dome oil field in Texas, and on Oct. 12 a second smaller sink formed at the north margin of the first. The purpose of this paper is to give such observations as it has been possible to make on the earth movement incident to this subsidence. Sour Lake salt dome is typical of the salt domes of the Gulf Coastal Plain of Texas. Structurally the dome is a plug of salt which rises to within 900 ft. or less of the surface. Above the salt is a cap rock consisting of anhydrite with more or less calcium carbonate. The salt plug, as contoured on the cap rock, is circular in outline with, however, some appreciable irregularities. Overlying the cap rock are relatively uncompacted sediments consisting of sand, clay and gumbo.. At the crest of the dome these deposits are no more than 700 or 800 ft. thick. However, the sides of the dome are steep, and the sediments thicken rapidly away from the crest. The sink formed about 1500 ft. northeast of the crest of the dome where the sediments overlying the cap rock are from 1000 to 1200 ft. thick. The cavity permitting the subsidence was quite certainly either in the cap rock or in the salt below the cap rock, so that the sink was formed by the caving of as much as 1000 or 1200 ft. of earth.

Jan 1, 1930

By G. W. LAAiIBOURNE

FEW mines possess a history of more fascinating interest than the Ontario at Park City, Utah. The famous Bonanza's production record of over $50,000,000; the great extent of its workings; the remarkable character of its mineralization; the fact that recent discoveries have shattered preconceived theories of the geology of the camp practically assuring the half-century old property a future as active and as prosperous as the past make the Ontario one of the unique mines of the world. A mere accounting of the wealth created by this historic property not only exemplifies the great profits

Jan 1, 1925

By L. W. Casteel, E. A. Jones

MINING the lead deposits of Southeast east Missouri has reached a high stage of technical development dictated by the scattered occurrences of low-grade ore through favorable horizons in the Bonne Terre formation. The rock-breaking, handling, and related practices described here have evolved as the best way of mining these particular deposits. These methods are applied in the production of about 19,000 tons of lead ore per operating day from four mines in Southeast Missouri. Development drilling Drifts 10 ft wide and either 8 or 9 ft high are driven in this district on contract. Miners are guaranteed standard wages plus a bonus on the footage advanced, if earned. Labor, fuse, caps, wire, and dynamite used are charged against the contract. Normally the cycle of operations in drifting is performed by a two-man crew, a motor operator and a shovel operator who first load out the rock broken by the preceding shift. The drift crew then sets up two vertical column and mounts the drills. Cleveland HC-10's are used which have a steel lug integral with the cylinder for connection with the air feed. All drilling in drifts is wet. Air pressure is 85 to 100 lb at the face. From 28 to 32 holes are drilled per swing in a pyramid cut. Cut holes

Jan 1, 1947