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By A. A. Burr, D. Caplan

IN carrying out experiments in metal-gas systems, it is often difficult to estimate how long a reaction period must be allowed for equilibration. This is especially true in systems for which the diffusion coefficient is not known. In an investigation of the Cr-O system, the necessary information was obtained in the way described subsequently. Two pieces of chromium sheet of different thicknesses were packed in mixed powders of chromium and Cr2O3 and sealed into an evacuated metal capsule by welding. Austenitic stainless steel proved suitable as a capsule material up to 1350°C and molybdenum at higher temperatures. The capsule then was heated at a specific temperature for a time sufficient to saturate with oxygen the thinner but not the thicker specimen. The time is readily estimated from a preliminary experiment if a sufficient thickness differential is chosen. Under these experimental conditions, the metal sheet is exposed to a partial pressure of oxygen equal to that of the dissociation pressure of the oxide and hence can become saturated with oxygen without developing any second phase. After cooling, both samples were analyzed for oxygen by the vacuum fusion technique. Assuming that the surface of the specimens is kept saturated with oxygen throughout the experiment, the diffusivity can be calculated by application of the appropriate solution to Fick's second law. This is most conveniently accomplished by use of a plot of mean fractional saturation (Cm-Co) / (Cs-Co) vs (Dt) ½/L as given by Darken,' where t is time, L the half-thickness of the sheet, and D the diffusion coefficient. Cm, the mean concentration at time t, is given by the oxygen percentage in the thicker specimen; Cs, the constant surface concentration, is the oxygen percentage in the thinner specimen; Co is the oxygen content of the original chromium sheet. (Cm-Co) / (Cs-Co) is calculated and the corresponding (Dt) ½/L is read from the graph and D thereby calculated. By performing the experiment at two temperatures and plotting log D vs 1/T, the D for any temperature is established. (The activation energy for diffusion may be obtained from the slope of the line.) Once D is known as a function of temperature, it is a simple matter to estimate the correct reaction time for experiments with single specimens at other temperatures by equating (Dt) ½/L to its value for effective saturation. Darken' points out that this is approximately unity. The solubility of oxygen in chromium, as determined from the thin samples at each temperature, proved to be approximately 0.03 pct at 1350°C and less at lower temperatures. Due to low solubility and to the known difficulties of the vacuum fusion method in this low range, the values obtained for D (5x10-0 sq cm per sec at 1350°C) are estimated to be correct only within an order of magnitude. Nevertheless, the method has proved useful in estimating reaction times. Its usefulness will be greater in metal-gas systems where the solubility is appreciable. A second function of the method is to permit the determination of diffusion coefficients in systems for which the conventional techniques are experimentally difficult or impossible.

Jan 1, 1956

By E. G. Leonardon, C. Schlumberger, M. Schlumberger

The authors give a definition of the various types of corrosion that may affect a metallic conductor buried in the ground, namely: 1. The metallic conductor may be attacked by the surrounding soil. This phenomenon is purely local and is called by them soil corrosiveness. 2. The metallic conductor may connect two regions of the ground when the electrolytes have a different composition. An electrical current will then be generated and certain zones of the conductor will be oxidized. This is autogalvanic corrosion. 3. Stray current may flow in the ground and enter the conductor in certain sections and leave it in others, thus causing oxidization in certain zones; this is electrolytic corrosion. The soil corrosiveness has been studied extensively by the United States Bureau of Standards and the authors give a summary of the work carried out and results obtained along this line. In autogalvanic corrosion it has been shown, by the investigation of buried pipes, that the zones of corrosion are associated with the zones of egress of the electric current (anodic zones). The location of these zones can be determined by measuring at the surface of the ground the difference of potential that exists along the path of the pipe. This work is performed easily and quickly with the apparatus invented by the authors for the exploration of conductive orebodies. The problem of electrolytic corrosion is a difficult one because it is a question of stray current which may vary in direction and intemsity at every instant. Therefore the components of the electrical field must be known at a given station and compared with the components of the clectrical field at another station, at the same moment. This is achieved by a rccording apparatus that will register the variations of the intensity of the electrlc current along two rectangular directions, during several minutes

Jan 1, 1934

Noranda Mines, of Quebec, signed a contract for construction of a $20 million copper refinery at Gaspe, P.Q. The plant is expected to have a 65500-ton daily capacity for both concentrator and smelter. Extensive drilling. around Gaspe has revealed more than 65 million tons of 1 to 2 pct copper in several deposits. Cerro de Pasco Corp. has called a special stockholders meeting for August 19 to obtain permission to engage in the oil and natural. gas business, in addition to its present production of zinc, lead, copper, silver and other metals. St. Joseph Lead Co. recently entered the oil development field. The United States, Canada and Great Britain have agreed to establish a permanent organization to work on unification of engineering standards. General accord has been reached on drafting standards and practices, screw threads, fittings for gas cylinders, and fits and tolerances. Permanent committees will study these fields. Reconstruction Finance Corn approved the largest sum in its history. for a mining enterprise when it loaned $94 million to San Manuel Copper. Corp., of Pinal County, Ariz. The loan will be used to increase production of copper and molybdenum, in what was described as-the biggest copper deposits in the country. Three large gold mining concerns operating in the Philippines told the Philippine Wage Board that they would be forced to close if they had to boost miners' wages 500 to $2 per day. The companies are Mindanao Mother Lodes, Benguet Consolidated, and Balatoc Mining Co.

Jan 1, 1952

By J. W. Marx, R. H. Langenheim

The authors are to he complimented for a timely presentation of useful information concerning application of heat to oil reservoirs to increase the rate and ultimate recovery of oil. The solution for heated area resulting from constant rate injection of a hot fluid, presented by the authors, and the fluid-flow analogy, solved by Carter,' are particularly interesting in that 110 restriction is placed on the direction of development of the heated area. It is not necessary that the heated area grow radially. Thus the solution could provide useful information for heat injection in any type of well pattern with any specified swept area data. However, it was assumed in the development that the heated region would remain at a constant clevatcd temperature. Vertical heat losses were computed on this basis. Physically. the assumption that the heated region will remain at a constant temperature (independent of distance from the injection point) appears to require that the heat injection medium be stcam, or other condensible gases near the boding point at injection pressure. If a hot liquid below the boiling point or a hot gas considerably above saturation temperature were used, the temperature of the heated region would decrease with distance from the injection well. Lauwerier2 has discussed this problem for a linear system. (See also Jenkins and Aronolsky; and McNiel and Nelson.') Thus, the authors' solution applies more nearly to steam injection than to hot water injection or hot, non-condensable gas injection. Assuming steam as the injection medium, it appears that steam would pass through the constant-temperature heated region and condense upon contact with the unheated sand. The tempcrature in the condensing region would probably be governed by the release of heat of vaporization required for phase equilibrium at the existing pressure distribution. Temperatures in the region would also be influenced by vaporization of hydrocarbon. Thus, it is doubtful that an expression for radial temperature distribution based on heat conduction only (such as the authors' Eq. 9) would have practical significance. As pointed out by Marx and Langenheim, the growth of the heated area under constant rate steam drive will eventually be limited economically by vertical heat loss. The possibility of continuing to move heat economically by cold water injection or by increasing the steam injection rate appears to be a very important consideration. (Movement of liquids away from the injection well should increase injectivity.) Fortunately, the solution presented by the authors may be generalized to thc case of a variable heat injection rate. The general solution is:

By S. B. Flagg

Advancement in the art of burning fuels for steam generation has been so marked and so rapid in the last 10 or 15 years that one may well hesitate to classify as unsuitable for stationary steam boiler firing any material having a fuel value. This statement should not be interpreted to mean that any existing boiler plant can successfully utilize any fuel with which it might be supplied. It does mean, however, that almost without exception it is possible to design and construct stationary boiler plants so that they can be operated with whatever coal is the economic supply therefor. In considering the subject of the use classification of coals, it must be recognized, first, that the suitability or unsuitability of a coal for certain uses or conditions may be largely a matter of opinion and, second, that as advancement in the art of burning fuels continues, fuels that may have been considered unsuitable may later be regarded as entirely suitable. This is well illustrated in the creation of a market for slack bituminous coal and for the finer sizes of anthracite that resulted from the development of mechanical stokers adapted thereto. Coke breeze is another fuel of which large tonnages were formerly wasted, that has now been found suitable for use in properly designed furnaces. Again, results that would have been thought quite impossible a generation ago are being obtained in steam boiler plants today with lignites of high moisture content and with coals of excessive ash content. It must, however, be admitted that oftentimes an existing boiler plant can be successfully operated with only a limited number of the coals that are available as possible supplies. We may briefly consider some of the more important factors that may affect the suitability of coals for such a plant. Insufficient or barely sufficient draft to meet peak steam demands is often a limiting factor, and the permissible frequency of fire-cleaning periods is another. In some cases, the action of the molten coal ash on refractory furnace linings prohibits or makes inadvisable the use of certain coals. Again, clinker conditions in the fuel bed or slag conditions on the boiler-heating surface may be much worse with some coals than with

Jan 1, 1930

By P. Pietrokowsky

RECENTLY a comprehensive investigation of the various sigma binary alloys was published by Duwez and Baen.1 It was shown that the following conditions are necessary for the formation of the sigma phase: (1) the difference in atomic diameters of the two alloying metals must not be more than about 8 pct; (2) of the two elements which form sigma, one must exhibit a body-centered cubic structure while the second metal must be face-centered cubic, at least in one of its allotropic forms. In addition, a tetragonal unit cell was proposed and powder patterns of six sigma phases were indexed for d spacings greater than 1.640 kx. Since the indexing, based on tetragonal symmetry, led to only fair agreement, the possibility of sigma being orthorhombic was investigated. Various methods for indexing orthorhombic powder patterns are de- scribed in the literature.' The method used in this investigation was a graphical examination of the differences in values of sin' 9 for the adjacent lines of the powder diffraction pattern. This method led to a complete indexing of the Cr-Co (60-40) pattern. Because of the strong similarity between the various sigma alloys, it was then possible to assign indexes to the patterns of Fe-Cr (50-50), Fe-Cr-Mo (30-30-40), Fe-V (50-50), Co-V (50-50), and Ni-V (50-50). The values of sin' 9 and indexes of the six sigma alloys, together with visually estimated intensities, are presented in table 1. In general, the similitude between the six patterns is quite good. For spacings greater than 1.75 kx a few differences are noticeable. In the Ni-V pattern, no (320) exists and the two strong lines (030) and (031) are separated by only two lines of lower intensity, unlike any of the other sigma patterns. However, very little is known about the Ni-V phase diagram and it is possible that the equal atomic percentage composition in this system lies in a two-phase region. At lower spacings there is a close analogy between the patterns. The planes

Jan 1, 1951

ON JUNE 7 the German Government handed to the French and Belgians a new proposal for reparations, which offered 1,200,000,000 gold marks annually, to be guaranteed as to 500,000,000 by a mortgage on the national railways, as to another 500,000,000 by a mortgage on industry, commerce, land and factories, and as to 200,000,000 by a luxury tax. The number of years for which this payment should run to be left to settlement by an international conference. This offer was taken under consideration by the French and Belgians, who instituted conversa-tions with the British in the hope of arriving, at some joint action with respect to the Germans. Up to the end of June nothing had been determined. In the meanwhile, the continued French and Belgian occupation of the Ruhr seemed to develop a condition of guerilla warfare, considerable bloodshed occurring throughout the region. The second Lausanne Conference dragged on, the Allies being apparently unable to take any firm, joint stand, while the Turks increased their importunities and managed to get concession after concession. Early in June a revolution occurred in Bulgaria, the previous Government under Premier Stambulisky, based on the agrarian party, being forcibly thrown out by a bourgeois and military combination. This pro-duced considerable disorder in Bulgaria, outside of which country the nature and purpose of the revolution does not appear to be well understood. Stambulisky's partisans offered feeble, isolated resistance to the revolu-tion; in connection with which there was some blood-shed and Stambulisky himself was reported killed, although this was later contradicted. Professor Zan-kof, the new Premier, issued a statement, that the change of the Government was the result of discontent, that the foreign policy of the new Government would be peaceful, and that Bulgaria would continue to fulfill her international obligations, particularly the treaty of Neuilly. It was the opinion of London that the immu-nity from taxation enjoyed by the farmers under the agrarian regime is likely to he superseded by more equi-table taxation, and in general that the bourgeoisie will be better administrators of the public affairs In domestic affairs industrial activity continued at a high rate, but there was distinct relaxation in the demand for raw materials, and also in some manufac-tured goods. During June there were reductions of prices by many of the automobile tire manufacturers. There seemed to be also further contraction in the demand for automobiles.

Jan 6, 1923

By J. B. Austin

IT is now well established, chiefly through the work of Davenport and Bain,1 that the influence of temperature upon the rate of transformation of austenite to ferrite at constant temperature is represented by a curve of the type shown in Fig. 5 of Tech. Pub. 589; and the reasons for this general shape have been discussed by them in a qualitative way. Thus, the upper part, or nose, of the curve is the resultant of two factors of which the rate of change with temperature is not the same, and by analogy with other like cases it is almost certain that these factors are: (1) the chemical potential, or driving force, of the transformation, which is zero at the equilibrium temperature and increases rapidly as the temperature falls below this point; and (2) a factor analogous to viscosity, or resistance of the crystal lattice to a change in structure, which also increases as the temperature is lowered. Just below the equilibrium temperature this virtual "viscosity" of the metal is relatively low-that is, the metal offers little resistance to a change in lattice-but the driving force is also small, and the net result is that the reaction proceeds slowly. As the temperature is lowered the magnitude of both factors increases; but at first the driving force increases more rapidly than the resistance and the reaction is observed to proceed more rapidly. At lower temperatures, however, the resistance begins to increase faster than the driving force, and eventually, at the nose of the curve, overbalances it, causing the reaction to proceed more and more slowly thereafter. This concept is somewhat, though not completely, analogous to that employed in certain electrical cases where the precise factors are known and are separately measurable. The current I (in amperes or coulombs per second) flowing through a given wire is proportional to the impressed potential, or driving force E, and is inversely proportional to the resistance R of the wire; that is, I = E/R. Stated in a slightly different way,

Jan 1, 1935

By R. H. Johnson

The Manual of the Oil and Gas Industry, under the Revenue Act of 1918, published by the Treasury Department for the guidance of oil companies in preparing their estimates of future recoverable oil for the purpose of calculating depletion, gives the first large public collection of comparative decline curves for the whole country. It is a matter of both scientific and practical interest to so arrange these data that the pools can be readily compared. There are certain difficulties in such a comparison, however: (1) The economic limit varies from 50 to 2000 bbl. a year in different pools taken. (2) Because of this variation in economic limit, the range of data shown makes comparison possible only for wells of intermediate size. In order to be as inclusive as possible, I have taken as an expression of the rate of decline the amount of oil produced in the period during which a well drops from 3000 to 2000 bbl. a year. No period of smaller production could be used because of the high economic limit in California; and no period of larger production and yet include the small well areas of the Appalachian. As it is, the Lima-Indiana wells are excluded. In a few instances, curves were extrapolated to obtain the reading, where the curve seemed regular enough to warrant it. In general, the amount of oil, in barrels, produced while a well declined from 3000 bbl. to 2000 bbl. a year is shown in Table 1.

Jan 1, 1921

By H. F. McCullough

MECHANICAL loading and conveying equipment has been available for the coal-mining industry for more than twenty years. The earlier equip-ment-was admittedly crude and ill-fitted to perform its intended functions, but there are available today a variety of mechanical loaders and conveyors which may be said to be almost on a par with coal-cutting machines. Despite the fact that such equipment is available and that better and other types of equipment are continually being developed, mechanical loading of coal cannot yet be said to be economically successful, except in a few special cases. It is not an accomplished fact in the sense that machine cutting of coal and electric haulage are accomplished facts and a part of accepted practice. There are two general opinions why we have failed to obtain better results with mechanical loading and con-veying equipment. The equipment manufacturers will say that coal-mine operators have generally failed to establish and maintain the conditions required for suc-cess. The coal-mine operator says that the equipment is not adapted to cope with his specific conditions to the extent required for economically successful results. Just what is the objective of this movement toward mechanical loading? We speak of mechanical loading in such a way as to lead one to believe that we are mere-ly seeking a mechanical equivalent of the human loader and his shovel. Really, we are impressed with the fact that the coal-mining industry has not advanced toward greater productive efficiency to anything like the degree achieved by practically all of the other productive in-dustries, and we are seeking the means to remedy this. We have seen the advantages which follow the intro-duction of coal-cutters and electric haulage-locomotives. The loading of coal is the one major operation in coal mining which has not been mechanized. We believe that a satisfactory, mechanical substitute for the man with the shovel will help us increase our productive efficiency to the same degree as has been accomplished in the other productive industries.

Jan 3, 1927

By J. F. Myers, F. M. Lewis

The purpose of the mill tests reported herein, was to determine the relative power efficiency of fast and slow rod mill speeds on the ores of the Tennessee Copper Co. The tests were carried out at the Isabella Mill of the Tennessee Copper Co. under normal operating conditions. Every effort was made to keep the ore supply and other conditions constant, but it will be noted that some slight variation did occur. The open circuit 6 by 9 rod mill, and ore, used in these tests have been previously described.' Four motor drive pinions were available and the tests were performed in the following manner: each pinion was used to drive the mill for a period of one week. Constant sampling prevailed during the test run, and a composite sample for each speed test was made. Realizing that some slight liner wear took place during the four-week test-run, and that some slight variation of the ore may have taken place, a second and then a third series of four-week test-runs were made with the four different pinions. The screen analysis of each of the three-week run samples at the various speeds were composited and the results are shown in Table 2. The authors feel that the 22 weeks of operation consumed during these test-runs would represent fairly the effect of each mil1 speed. The data of line 37 show that within the error of sampling and plant operation, the tons of minus 65-mesh material generated per horsepower hour was the same at all four speeds. Obviously, rod and liner consumption could not be determined for each mill speed in so short a time. The rod load was maintained at a uniform level throughout the series of tests. The authors have operated rod mills at various speeds over the past several years, and it is their observation that rod consumption is directly proportional to the mill speed. Likewise, that the rod consumption per unit of work performed is a constant, providing that all other operating factors remain the same. It is a well known fact that the efficiency increases in a ball mill as the speed decreases. This is due to lateral segregation of the large and

Jan 1, 1950

By E. I. Salkovitz, F. W. von Batchelder

AS Slawson1 and others have already shown, from a geometrical view twinning in the diamond structure may be considered as a reflection across a (111) plane or as a reflection across a (112) plane. An analysis by Ellis and Treuting2 showed that the twinning plane must be the (111) plane, but that a twin might have lateral boundaries along (112) planes. Earlier Slawson1 and Ellis3 had shown that only (111) twinning was present in diamond and germanium respectively. Since an ingot of silicon, 1 in. in diam and 1 1/2 in. long, prepared from Dupont silicon to which 0.2 pct Be had been added was available, it was examined for twinning. The ingot had been cooled slowly from the bottom. A section 1/16 in. thick was ground off from the bottom and then the ingot was sliced vertically through the center. Spectrographic analysis indicated only faint traces of iron and silver, in addition to the beryllium. The sample was first etched with a hot solution of 10 pct NaOH in water.and photographed. Back-reflection Laue patterns were made of the vertical and horizontal sections in the regions designated in Fig. 1. Orientations were obtained for each twin using the Greninger technique. Several regions of the same orientation were found; thus regions A and K were identical, similarly N and P, and C, G, J, and L. Knowing the angles between the traces of the twinning plane on the surface and the specimen axis, the indices of the twinning plane were deduced. In all cases the twinning plane was found to be (111); lateral boundaries, however, were found which were (112) such as the one indicated in Fig. 1. Therefore, as in the case of diamond1 and germanium' only (111) twinning occurs in silicon. We wish to thank Mr. Hino for the use of the ingot as well as for its metallographic preparation. References 1C. B. Slawson: American Mineralogist (1950) 35, p. 193. 2 W. C. Ellis and R. C. Treuting: Trans. AIME (1951) 191, p. 53; Journal of Metals (January 1951). 3W. C. Ellis: Trans. AIME (1950) 188, p. 886; Journal of Metals (June 1950).

Jan 1, 1953

By C. J. Hicks

The labor policy of the Standard Oil Co. (New Jersey) is founded first of all on paying at least the prevailing scale of wages for similar work in the community; on the eight-hour day at the refinery, with time and one-half for overtime; one day's rest in seven; sanitary and up-to-date working conditions; just treatment assured each employee; opportunity for training and advancement; payment of accident benefits beyond the amount prescribed by the State compensation law; health supervision by a competent medical staff; payment of sickness benefits after one year's service; coöperation with employees in promoting thrift and better social and housing. conditions; and assurance of a generous annuity at the age of 65, guaranteed for life after 20 years of service. Most of these features have been a part of the company's policy for many years, but it is only during the past two years that the cooperation of employees in determining these matters has been definitely assured through industrial representation. Industrial representation, in the Standard Oil Co. (N. J.), is a principle rather than a procedure. It is built upon the belief that personal association of those interested in any problem leads to a mutual understanding and a fair decision as to what is right. Fully believing in this principle, representatives of employees and representatives of management evolved a simple plan, the basis of which is that it gives every individual employee representation at joint conferences on problems and fundamental principles affecting all those interested in the industry. It is based on cooperation, not antagonism; its operation makes perfectly clear both to management and to employees that their interests are identical, and not at variance with the interests of the stockholders, and that mutual understanding and cooperation insure progress and success for all. Furthermore, experience has definitely shown that representatives of the employees are not only alert for the employees' interests but are as keen as the representatives of the management in determining and insisting upon fairness to the employer. Though the plan has been in operation nearly two years, it is an experiment, in that, being based on a principle rather than on cut-and-

Jan 1, 1921

By Roland W. Rammler

With oil consumption increasing more rapidly than known reserves in industrial countries, there has been a growing interest in the production of synthetic crude oil. The main starting materials for such production are coal, oil shale and tar sand, all of which occur in enormous quantities in North America. A process sequence suitable for all three of these starting materials incorporates a preliminary retorting step to produce oils for subsequent hydrotreating. For this retorting step, a technique known as the Lurgi-Ruhrgas process has proven highly efficient. The process has been commercially used for the flash carbonization of coal and has also been tested in pilot- plant experiments with oil shale and tar sand.

Jan 1, 1970

EARLY in November attention was focused on the interchange of views between Paris and Wash- ington with respect to the proposed examination of Germany's capacity to pay. It appeared finally that the limits imposed by the French were too narrow and consequently the conversations were discontinued. In Germany there were stirring events. Hitler, with Ludendorf in the open, attempted a coup d'etat in Bavaria, but failed quickly and ignominiously. The former crown prince re-entered Germany, with the sanction of the republic, and took up his abode at his castle in Silesia. On Nov. 13 Chancellor Stresemann informed repre-sentatives of the Rhineland and the Ruhr that those territories thenceforth must shift for themselves politically, economically and financially, the federal treasury being no longer capable of caring for unem-ployment in the occupied territory. This was equiva-lent to putting the burden of supporting the people of that region upon. France and Belgium. There have been negotiations toward the creation of a Rhenish-Westphalian state, independent of Prussia, but under the sovereignty of the Reich. Failing to receive a vote of confidence at the end of this month, the Stresemann Ministry resigned. President Ebert considers it may be necessary to create a government independent of Parliamentary authority. The Ruhr Industrialists have signed an agreement with France until April 15, 1924 by which they have agreed to pay back coal taxes for the first ten months of this year, and deliver 18 per cent. of their production as reparations until the expiration of the agreement. The British government found itself in a precarious position with respect to support and a dissolution of Parliament was announced, with a general election to occur early in December.

Jan 11, 1923

By A. F. Crawley

The densities of some liquid Pb-Sb alloys up to 11 wt pct Sb and Pb-Sb-& alloys up to 10 pct Sb/10 pct Sh have been determined by a pycnometric technique over a temperature range of about 130°C above their melting points. The data given are accurate within 0.05 pct. Density is shown to vary linearly with temperature , and equations relating these quantities have been formulated. Molar volumes calculated from the density data indicate that volumetric deviations from ideal mixing are undetectable within the limits of experimental error. A continuing research program into some fundamental physical properties of liquid metals is being pursued at the Mines Branch, Department of Energy, Mines and Resources, Ottawa, Canada. This work has received support from the Canadian Zinc and Lead Research Committee in cooperation with the International Lead and Zinc Research Organization. This paper, which reports some density data for Pb-Sb and Pb-Sb-Sn alloys, follows previous work from this laboratory on lead, tin, and Pb-Sn alloys.' Of previous data from others, Greenaway2 and Sato and Munakata3 have reported results on Pb-Sb alloys. No previous work has been published on the ternary Pb-Sb-Sn alloys, reported here. EXPERIMENTAL METHOD Densities were measured by a pycnometric technique which has been described in detail and appraised for accuracy in earlier Mines Branch reports.475 Fig. 1 shows the densitometer with the pycnometer in position for a run. The pycnometer is also shown in some detail. The pycnometer of dense, high-purity graphite, about 14 cu cm in volume, was carefully machined to a uniform, smooth finish. The height was measured by a depth micrometer and the diameter by fitting precision gage blocks between steel balls.' In each case several readings were taken, and the final results were considered accurate within 0.01 pct. The resulting volumetric uncertainty together with small inaccuracies in the coefficients of linear expansion of graphite lead to a maximum systematic uncertainty in the method of ±0.03 pct. As shown in Fig. 1, the pycnometer lid is a threaded cap. Thus, the charge, a cylinder of the alloy, can easily be inserted and the solidified metal can readily be removed after a run. The dimensions of the cylindrical charge are chosen to ensure that, once molten, the metal will not only fill the pycnometer completely but will discharge an excess into the excess-metal float chamber. AS the temperature is increased above the melting point, the volume of metal in the excess chamber increases until the system has equilibrated at the desired temperature. At this point, the excess chamber is moved to one side by twisting the shaft F, leaving a fixed volume of liquid metal in the pycnometer. This volume of fluid is readily calculated using measured coefficients of linear expansion of the graphite which expands anisotropically. The associated weight of fluid is determined as the weight of the solidified metal removed after the furnace has cooled down. Alloys were prepared from 99.997 pct Pb, 99.999 pct Sn, and 99.999 pct Sb, being melted by an electric furnace in a graphite crucible and poured into graphite molds. Several density specimens of the same nominal size were machined from each ingot, and, by comparing specimen weights, relative differences in specimen composition resulting from segregation in the ingots could be detected. In this way, segregation was found to have occurred in Pb-Sb alloys at compositions beyond the eutectic (11.2 pct Sb) and this

Jan 1, 1969

TWO very interesting sessions on mine ventilation were held on Monday. George S. Rice, chairman of the Mine Ventilation Committee, presided at the morn-ing session. Formal reports from two subcommittees were presented, as well as two technical papers. Daniel Harrington, for the subcommittee on metal mining, gave a most interesting report, devoting most of it to a review of the literature that had appeared during the past year, to the cooling of mine air, and to a discussion of mine fires. In the absence of Dr. R. R. Sayers, chairman of the Physiological subcommittee, Mr. Harrington gave a resume of that report. The main points covered were in connection with silicosis but some attention was also paid to the associated prob-lems of air cooling and humidity. The paper by Prof. W. S. Weeks on the "Air-Current Regulator" was briefed by Prof. A. C. Callen. Pro-fessor Weeks brought out the fact that the common application of Murgue's equivalent-orifice formula to regulator problems was incorrect, inasmuch as the dis-charge from the regulator was not released into the open air but into a slow-moving current beyond the regulator. He applied the shock-loss theory of Bordoni to the problem and worked out a formula for solving regulator problems, giving coefficients of contraction he had determined experimentally.

Jan 3, 1928

I-Mine Ventilation A C. CALLEN, Chairman E A. HOLBROOK, Vice-chairman H I. SMITH, Secretary CLARENCE E. ABBOTT ALFRED W. HESSE FRANK H. PROBERT GRAHAM BRIGHT G R. JACKSON GEORGE S RICE THOMAS H. CLAGTETT JAMES F. MCCARTHY E. J RISTEDT OSCAR A GLAESER W. B. PLANK GERALD F. SBERMAN, Coal Mining M D COOPER, Chairman HOWARD N EAVENSON JOHN A GARCIA THOMAS D THOMAS CHARLES ENZIAN JAMES W PAUL C M YOUNG JOHN J. RUTLEDGE Physiological Studies R R. SAYERS, Chairman C. L. BERRIEN W. D. BRENNAN A. J. LANZA

Jan 1, 1923

By T. Sterry Hunt

SINCE: the date of my previous paper on this subject, presented at the Cincinnati Meeting, February, 1881, and published in our Transactions, vol. xii., p. 459, I have had occasion to revisit the Canadian apatite region, and to collect further data concerning its geognosy, which I hope to describe at a future time. At present, I shall put on record a few brief observations concerning the more recent operations in apatite-mining in the Lievre district, to the north of the Ottawa River, where the mines are as yet confined to a small area in the townships of Buckingham, Portland, Templeton, and Darry; the earlier workings having been along the Rideau Canal, to the south of the Ottawa. The large mining operations lately undertaken in the Lièvre district show that the crystalline phosphate of lime or apatite belongs to lodes of great size, which traverse the ancient gneiss of the region. These lodes include a granitoid feldspathic rock, and a pyroxene rock, with large masses of quartz, of carbonate of lime, of pyrites, and of apatite. All of these often show a banded structure, riot unlike that of the gneiss, to which they- are evidently posterior, arid of which they

Jan 1, 1886

This brief resume of events, transpiring in Mexico, culled front the daily New York newspapers, since the last Bulletin-went to press, does not indicate any degree of improvement in the situation. RECORDS OF 217 MEXICO KILLINGS SUBMITTED BY AMBASSADOR FLETCHER Henry P. Fletcher, the American Ambassador to Mexico, called as the first witness before the Rules Committee of the House which has begun a preliminary inquiry into conditions in Mexico, which, it, is believed, will lead to a thorough and far-reaching investigation by a joint Senate and House Committee of the entire Mexican problem, submitted a list of the names of Americans officially known to have been killed in Mexico, a majority of them murdered in cold blood, since the overthrow of Porfirio Diaz by Maderoin 1911. The list contains 217 names and in comparatively few instances do the records show that arrests were made by the particular Mexican faction that happened to be in power where the crime was committed. In only one instance, that of John B. McManus, who was killed in March, 1915, was reparation made. It is significant that McManus was killed by Zapatistas, and Zapata officials apologized for the crime and paid to Mrs. McManus a voluntary indemnity of $20,000 in gold. Of the 217 persons listed as victims of the Mexicans, .137 perished since Carranza came into power. The list, it was admitted, is not complete. It was evident, says the New York Times, that the Ambassador considered the situation very serious.

Jan 9, 1919