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By L. F. Mondolfo, B. E. Sundquist

The crystallographic orientation relationships resulting when lead is nucleated from the liquid by Ni, Cu, Ag, and Ge were determined. For each nucleating agent several definite orientatioz relationships were found. These relationships seemed to be controlled by good symmetry relations and low crystallographic disregistry between mating planes. For any given nucleating agent the under colling for nucleation was found fairly constant and independent of the orientation relationship and consequent disregistry. It was also found that, upon re melting and refreezing the Pb, the orientation relationship was changed. These findings prove that crystallographic disregistry is not the controlling factor in heterogeneous nucleation from the liquid. The results of this investigation tend to confirm the theory presented in a preceding paper that heterogeneous nucleation starts with the formation of an adsorbed layer of nucleated metal on the nucleat-ing impurity. Evidence is given that cavities in the nucleating agent act as centers of nucleation. IT has long been known' that solid extraneous particles are active in catalyzing phase transformations that occur in a system, particularly condensation and crystallization. It is well established that these heterogeneities act as catalysts by providing surfaces upon which nuclei of the precipitating phase can form with activation energies smaller than those required for homogeneous nucleation. Numerous investigations have shown that in this process of heterogeneous nucleation: a) the nucleus forms with one, or several, definite crystallographic orientation relationships with the nucleating phase2-4 and b) that there is a small range of undercoolings or super saturations characteristic of the nucleation of a given solid on a given Substrate.5-10 Turnbull and vonnegut11 have developed a theory based on theories developed by Volmer12 and Turn-bull and Fisher1= for heterogeneous nucleation from gases and liquids, that relates the super saturation or undercooling required for nucleation to the dis-registry between the lattices of the nucleus and the nucleating agent. This theory predicts that nucleation should occur with the orientation relationship between the nucleus and nucleating agent that minimizes the disregistry. Further, it predicts that the undercooling or super saturation necessary for nucleation should be a function of the disregistry. Numerous investigations have dealt with the orientation relationships resulting from the condensation of vapors onto crystalline solid substrates2,3 and a few with the nucleation of one phase by a second phase in solidification4,14. Others have dealt with the supersaturation8-10 and undercooling5-7 associated with nucleation in condensation and solidification respectively. However, there is virtually no report that gives both of these factors for the same system. In this investigation a study was made of the undercoolings and orientation relationships resulting when Pb is nucleated from the liquid by Ni, Cu, Ag, and Ge. It was the purpose of this investigation to check the Turnbull-Vonnegut theory, i.e., the importance of crystallographic disregistry between nucleating catalyst and nucleated metal. The results indicate that disregistry is not an important factor in nucleation and that the nucleation process is probably somewhat more complex than current theories suggest. EXPERMENTAL PROCEDURE Small single crystals of nickel, copper, silver, and germanium were prepared from materials of four to five nines purity, and the Pb used was also 99.999+ pet pure. Cu and Ag single crystals were prepared by sealing small chips of Cu or Ag in an evacuated quartz capsule and heating the capsule at 2000°F for 1 hr before cooling. Nickel crystals of 200 diam were also prepared in evacuated quartz capsules, but melting was done by heating the capsules in an oxy-acetylene flame for a few minutes. These spheres were invariably polycrystalline so

Jan 1, 1962

By N. A. Warner

Dense cylindrical specimens of artificial hematite were reduced in hydrogen over a range 0-f total pressures between 0.1 and 1.0 atm and temperatures between 650" and 950°C. Hydrogen reduction at a total pressure of 1.0 atm in the presence of a chemically inert diluent and reduction in hydrogen/water mixtures were also studied Znter.face movement during reduction was followed using metallographic techniques. Substantiu1 partial-pressure gradients are shown to exist in both the gas film and the reduced iron layer. The results are consistent with a mixed-control mechanism involving an interaction of gaseous-difusion effects with a first-order reversible chemical reaction at the iron/wüstite interface. Over the hydrogen-pressure range of 0.1 to 1.0 atm, the rate is not directly proportional to the hydrogen pressure in the bulk gas stream. Nitrogen dilution of the reducing gas masks the true effect of hydrogen partial pressure by influencing the effective molecular dif-fusivity and gives an apparent first-order relationship. The transport of hydrogen and water vapor across the iron layer is consistent with molecular gaseous diffusion rather than a Knudsen diffusion mechanism. ALTHOUGH the literature on the reduction of iron oxides is very extensive, it is only comparatively recently that a definite quantitative model for the reduction of hematite has been proposed. This development has been largely due to the work of McKewan. An extensive literature review of previous work has recently been compiled by Themelis and Gauvin. Exclusive control by gaseous diffusion in the reduction of hematite has been recently advocated by Kawasaki and coworkers.' Although the results of the latter workers are of considerable practical significance, the extreme porosity (approximately 30 pct) of their specimens precludes their application to a kinetic evaluation of the reduction of dense polycrystalline hematite. The salient features of the kinetic model used by McKewan for the gaseous reduction of dense hematite at temperatures in excess of 560°C (when FeO is stable) are: 1) The reduction is a topochemical reaction taking place through 'the series FeO/FesO4/FeO/ Fe; 2) The gas-solid type of reaction takes place only at the FeO/Fe interface and the internal reduction: FeO proceeds by solid state diffusion; 3) The iron layer formed is quite porous and offers negligible impedance to gaseous diffusion; 4) The rate-controlling step in the reduction is a chemical process occurring at the Fe/FeO interface. In view of the relatively fast reaction rates involved when hematite is reduced in a stream of hydrogen, it seemed possible that the simplifying assumptions of negligible diffusional resistance in both the bulk gas phase and the reduced iron layer could introduce serious errors in the interpretation of experimental reduction data. The present work was initiated to elucidate the effect of gaseous diffusion on the reduction rate and to determine its possible influence in the formulation of the reaction mechanism at the metal/oxide interface. EXPERIMENTAL Procedure and Apparatus. Dense cylindrical compacts of artificial hematite were prepared by sintering pressed compacts of reagent-grade ferric oxide, containing 99.6 pct FezO, in air at 1200°C for 80 hr. The resulting compacts had a final porosity of less than 2 pct and a height and diameter of approximately 1 cm. Variations in sintering atmosphere from air to pure oxygen, in sintering time from 20 to 80 hr, and temperature from 1150" to 1250°C had no effect on the subsequent reduction behavior. The reduction of the samples took place in a vertical tube furnace in which was placed a 1-in. transparent silica tube. The 24-in. heated length

Jan 1, 1964

By J. R. Thoenek S. L. Windes

The amplitudes and frequencies of vibratiolls of a four-story stucco building were measured by specially developed electrocapacitive seismometers. Records were made on three floor levels with as many as 10 seismometers recording simultancously. Sources of vibration were: (1) an electric motor with unbalanced pulley, maximum speed 1800 r.p.m., maximum centrifugal force 90 lb., (2) truck traffic (both solid and pneumatic tires) moving over inequalities in the street in front of the house, (3) falling weights dropped on the street pavement from different heights, (4) miscellaneous sources, including a man jumping on the floor of the house and slamming doors. Tests were made to determine the natural frequencies of floor and wall panels by varying the speed of the unbalanced motor and by exciting the panels with a single impulse. The vibrations recorded were compared to records of vibrations from quarry blasts and it was observed that the vibrations from truck traffic were comparable to those recorded from quarry blasts and in no instance was there any damage to the building. As the tests were all of a negative character as far as damage was concerned, no index of destruction is formulated. Instead, the records are presented simply as vibration measurements obtained in an ordinary house under typical conditions.

Jan 1, 1940

By J. R. Thoenek S. L. Windes

The amplitudes and frequencies of vibratiolls of a four-story stucco building were measured by specially developed electrocapacitive seismometers. Records were made on three floor levels with as many as 10 seismometers recording simultancously. Sources of vibration were: (1) an electric motor with unbalanced pulley, maximum speed 1800 r.p.m., maximum centrifugal force 90 lb., (2) truck traffic (both solid and pneumatic tires) moving over inequalities in the street in front of the house, (3) falling weights dropped on the street pavement from different heights, (4) miscellaneous sources, including a man jumping on the floor of the house and slamming doors. Tests were made to determine the natural frequencies of floor and wall panels by varying the speed of the unbalanced motor and by exciting the panels with a single impulse. The vibrations recorded were compared to records of vibrations from quarry blasts and it was observed that the vibrations from truck traffic were comparable to those recorded from quarry blasts and in no instance was there any damage to the building. As the tests were all of a negative character as far as damage was concerned, no index of destruction is formulated. Instead, the records are presented simply as vibration measurements obtained in an ordinary house under typical conditions.

Jan 1, 1940

The Honor Roll includes the names of all members of the Institute whom we know to be on active military duty at the date of its compilation, February 7, 1918. We are aware that there are many others of whose activities we have not been informed, and we shall be grateful for information as to any such omissions from the Roll. 1. MEMBERS ON ACTIVE MILITARY SERVICE Mail addressed to members on the first division of the Roll and sent to the office of the Institute Will be forwarded according to the best of our knowledge at the time. AARONS, J. BOYD, Capt., 4th Reinforcements, 11th Infantry, Australian Imperial Force. '05 ADAMS, HENRY, Capt Asst. to Dept. Engr., Northeastern Department. '02 AGNEW, FRANK VANS '04 ARBE, FREDERICK R., Capt 33d Engineers. '97 ALDER, ALFRED Engineers' Reserve Corps. '17 ALFORD, NEWELL G., Sgt., Bureau of War Risk Insurance, Headquarters 84th Division. '14 ALLEN, HEMAN H., Private Co. D., 8th Reserve Engineers. '17 AMBLER, HARRY A., Lieut 30th Infantry. '16 ANDERSON, ALEXANDER, Lieut Royal Garrison Artillery. '07 ANDERSON, GEORGE K., JR., See. C, 1st Co., 3d Officers' Training Camp. '17 ANDREWS, CLARENCE W., 1st Infantry Co., Officers' Training Camp, 83d Division. '13

Jan 1, 1923

The word "engineering" should not be considered as all-inclusive. Perhaps it should be redefined at this time. Various fields of learning that are indispensable to the locating, beneficiating, processing and using of minerals cannot be classified properly as engineering. For example, in locating deposits, the sciences of paleontology, stratigraphy, mineralogy, petrology, petrography, geo- chemistry, economic geography, and mineral economics might be involved. Beneficiating, processing, and using go beyond the normal scope of engineering to include fuel technology, physical and organic chemistry, physical and atomic metallurgy, and ceramics. Fifty-eight institutions of higher learning in the United States offer curricula in one or more subject-matter fields of the mineral arts and sciences. Thirty-four curricula are offered in mining; 42 in metallurgy; 17 in petroleum and natural gas; 13 in ceramics; 1 in fuel technology; 23 in geological engineering; 8 in geology; 4 in geophysics; 2 in mineral preparation; and l in mineral economics.1 Under given conditions, some of these curricula probably could be eliminated without the slightest retardation in the rate of advancement of knowledge concerning the science of mineral discovery, extraction and utilization, but it is no credit to mineral industries colleges that five departments of mining per-

Jan 1, 1950

By W. B. Mather

GEOLOGICAL studies have revealed the occurrence of hundreds of pegmatite dikes in north- east Brazil, Fig. 1, in the three states of Rio Grande do Norte, Paraiba, and Ceara. Heretofore data have not been available on the possible production of lithium minerals from these areas, and in March, April, and May 1953 the author undertook a reconnaissance survey covering a cross-section of the pegmatites. Sixty-one pegmatites were examined. The pegmatites of Rio Grande do Norte and Paraiba are located in an arid region (Seratao), and except in the most southerly portion there is a mini- mum of vegetation and overburden. The region is easily prospected and relatively accessible by jeep or truck. The pegmatites examined in Ceara are in an area of lush vegetation along the flanks of the Jaqueribe River valley. It is therefore more difficult to prospect, and the dirt roads, as a means of access, leave much to be desired. For all practical purposes rail transportation, except in Ceara, is not available. The rocks of the area1-4 are composed of Pre-Cambrian schist, gneiss, quartzite, and marbles. They have been intruded by granites, monzonites, and diorites and cut by quartz veins and pegmatites.

Jan 9, 1954

By S. E. Haszko

Fused alumina or silica crucibles were used as the containing vessel. X-ray powder photographs were taken with CrKa radiation and the use of Straumanis type Norelco cameras of 114.6 mm diam. Crystallographic data for these compounds are shown in Table I. These results are in agreement with others of this series reported previousiy by Wernick and Geller.l The abnormally large atomic volume of Eu and Yb metal3 is manifested in EuA12 and YbAl2, when one compares them with the compounds reported in Ref. 1. However, the behavior of Yb in the Ni compound is the same as that observed in Ni5Yb having the Cu5Ca structure.4 Thus, it appears that Yb has a valence closer to 3 only in the Ni compounds; i.e.. the 2s and Id electrons are lost to the conduction band. 1,4 Europium in EuAl2, appears to have a valence closer to 2. In previous work.' X-ray patterns of ingots of NdCo2 indicated a multiphase material with faint indication of the presence of a phase having the MgCu2 structure. It was thought that NdCo2 formed peri-tectically from the melt, resulting in a multiphase system when cooled under nonequilibrium conditions. An X-ray pattern of a sample from a melt cooled more slowly than in past work showed that the major phase was NdCo2. The lattice constant, Table 1, is in excellent agreement with the value one can predict from the data of Ref 1. One of the other phases was identified as Co,Nd. The author wishes to thank J. H. Wernick for his guidance in this work, and D. Dorsi for the preparation of these compounds. 'J. H. Wernick and S. Geller: AIME Trans., in press. 'J. H. Wernick and S. E. Haszko: to be published. 'F. H. Spedding and A. II. Daane: Progress in Nuclear Energy, Series 5, Eds.: H. M. Finniston and J. P. Howe, McGraw-Hill Book Co., 1956. 'S. E. Haszko: to be published. 'J. H. Wernick and S. Geller: unpublished work. 6J. 11. Wernick and S. Geller: Acla Cryst., 1959, vol. 12, p. '162. The Influence of Hydrogen on the Lattice Parameters of Ti-Sn Alloys A. Coucoulas and H. Margolin A reinvestigation of the lattice parameters of Ti-Sn alloys by the present authors has revealed consistently higher c and a values than those obtained by Worrier. The difference is most pronounced in the c-parameters which are, therefore, used as a basis of comparison. This discrepancy was not due to air contamination, since precautions were taken to exclude this possibility. Specimens for Debye-Scherrer photograms were prepared by arc-melting 15-g buttons of Bureau of Mines titanium and 99.99 pct Sn, with compositions of 6, 8, 10, and 12 at. pct Sn. These buttons were forged under an oxygen-acetylene torch to 1/8-in. sq rods to produce relatively fine grained material. Scale and some surface were ground off, and the rods, after wrapping in molybdenum and titanium sheet, were vacuum annealed 15 min at 800 °C to remove hydrogen. Heat treatment of one of the samples at 875°C to produce ß and reveal a at the surface showed no surface contamination. Following the vacuum treatment, the specimens were wrapped in molybdenum and annealed for 1week at 800°C under two atmospheres of argon. After water-quenching, the rods were ground so that the thickness tapered to 0.1 mm at the tips. The ground specimens were then recapsuled as previously and reannealed 1 hr at 800°C to remove cold work. The

Jan 1, 1961

By H. Margolin, A. Coucoulas

Fused alumina or silica crucibles were used as the containing vessel. X-ray powder photographs were taken with CrKcll radiation and the use of Straumanis type Norelco cameras of 114.6 mm diam. Crystallographic data for these compounds are shown in Table I. These results are in agreement with others of this series reported previousiy by Wernick and Geller.l The abnormally large atomic volume of Eu and Yb metal3 is manifested in EuAl2, and YbAl2, when one compares them with the compounds reported in Ref. 1. However, the behavior of Yb in the Ni compound is the same as that observed in Ni5Yb having the Cu5Ca structure.4 Thus, it appears that Yb has a valence closer to 3 only in the Ni compounds; i.e.. the 2s and Id electrons are lost to the conduction band.1,4 Europium in EuAl2 appears to have a valence closer to 2. In previous work.' X-ray patterns of ingots of NdCo2 indicated a multiphase material with faint indication of the presence of a phase having the MgCu2 structure. It was thought that NdCo2 formed peri-tectically from the melt, resulting in a multiphase system when cooled under nonequilibrium conditions. An X-ray pattern of a sample from a melt cooled more slowly than in past work showed that the major phase was NdCo2. The lattice constant, Table 1, is in excellent agreement with the value one can predict from the data of Ref. 1. One of the other phases was identified as Co5Nd. The author wishes to thank J. H. Wernick for his guidance in this work, and D. Dorsi for the preparation of these compounds. 'J. H. Wernick and S. Geller: AIME Trans., in press. 'J. H. Wernick and S. E. Haszko: to be published. 'F. H. Spedding and A. II. Daane: Progress in Nuclear Energy, Series 5, Eds.: H. M. Finniston and J. P. Howe, McGraw-Hill Book Co., 1956. 'S. E. Haszko: to be published. 'J. H. Wernick and S. Geller: unpublished work. 6J. 11. Wernick and S. Geller: Acia Cryst., 1959, vol. 12, p. '162. A reinvestigation of the lattice parameters of Ti-Sn alloys by the present authors has revealed consistently hiher c and a values than those obtained by Worrier. The difference is most pronounced in the c-parameters which are, therefore, used as a basis of comparison. This discrepancy was not due to air contamination, since precautions were taken to exclude this possibility. Specimens for Debye-Scherrer photograms were prepared by arc-melting 15-g buttons of Bureau of Mines titanium and 99.99 pct Sn, with compositions of 6, 8, 10, and 12 at. pct Sn. These buttons were forged under an oxygen-acetylene torch to 1/8-in. sq rods to produce relatively fine grained material. Scale and some surface were ground off, and the rods, after wrapping in molybdenum and titanium sheet, were vacuum annealed 15 min at 800 °C to remove hydrogen. Heat treatment of one of the samples at 875°C to produce ß and reveal a at the surface showed no surface contamination. Following the vacuum treatment, the specimens were wrapped in molybdenum and annealed for 1 week at 800°C under two atmospheres of argon. After water-quenching, the rods were ground so that the thickness tapered to 0.1 mm at the tips. The ground specimens were then recapsuled as previously and reannealed 1 hr at 800°C to remove cold work. The

Jan 1, 1961

By M. Muskat, H. H. Evinger

A METHOD has been developed whereby one may calculate the productivity factors of producing formations from a knowledge of the reservoir conditions. Account is taken not only of the heterogeneous character of the gas-oil flow system but also of the detailed variations with pressure of the shrinkage and viscosity of the oil, the solubility of the gas in the oil, and even the variability of the gas viscosity and the deviation of the gas from ideal behavior. Curves are shown giving the results of numerical calculations on the production rate as a function of the pressure differential for a high-pressure and a low-pressure system, three values of gas-oil ratio being treated in each case. Curves are also given showing the variation with distance from the well of the pressure, oil saturation, and permeability. The effect of connate water is briefly discussed in relation to the apparently large discrepancies between the calculated and observed productivity-factor values. INTRODUCTION The significance of the productivity factor as a measure of the capacity of an oil-bearing formation to produce is well recognized; for it is the composite and integrated resultant of the physical properties of both the porous medium and the fluid stream passing through it with respect to the ease with which the particular petroleum fluids present in the formation can flow through it and into producing wells. The most direct method of determining the productivity factor of a well consists, as is well known, in the simultaneous measurement of reservoir-pressure differentials and rates of production and the expression of the data in terms of rate of flow per unit pressure drop.1 Actual measurements carried out in this manner on producing wells have given factors that generally lie in the range of 0 to 100 bbl. per day per pound pressure drop. This wide range arises not only from variations in permeability but also from the varying sand thickness of producing formations. One of the aims of developing a theory of the mechanics of oil production obviously is that of predicting what the productivity factor should be from a knowledge of the individual characteristics of the producing formation and the fluids produced. For homogeneous fluid systems passing through a porous medium into a producing well, it has been known for some time that the steady-state rate of liquid flow Q is given by the formula:* [ ] where k is the sand permeability, h its thickness, µ the liquid viscosity, [Ap] the pressure drop between the well and the distant parts of the reservoir, in particular that at a radius [ro ]and [r ] is the well radius. This gives the productivity factor: [ ] which will have a numerical value for a liquid of I centipoise viscosity of 0.9316 or

Jan 1, 1941

Jan 1, 1930

By AIME AIME

CORROSION of tanks, pipes and other equipment in the oil fields is becoming worse as the production of high- sulfur crudes in the Texas panhandle and west Texas areas increases. It has been estimated that .in certain fields of that State one tank out of every five has to be replaced every year because of the high sulfur content of the crude. One suggested method for combating tank corrosion is the use of .materials which have a high resistance to the corrosive action of hydrogen sulfide and high-sulfur crudes; aluminum is one of these materials. As a result, the United

Jan 1, 1929

By R. L. Wiegel

The generation of operating information for mineral beneficiation processes has become more sophisticated as a result of the use of improved laboratory analytical techniques, some of which provide multiple component assays, as well as the introduction and gradual industrial acceptance of process sensors for the measurement of flow, density, size, and chemical composition. In general, however, the mineral processing engineer's ability to tie together this wealth of information has not kept pace with these developments. In fact, in almost all existing plants, the metallurgical inflow-output balance, wed to indicate current process performance, is still being calculated from only a small portion of the information routinely available. There is substantial activity in the development of techniques for using all available process information to significantly improve the reliability of the metallurgical balance. While the use of these improved techniques does require access to computing facilities and a slight change in perspective on the part of the mineral processing engineer regarding the inviolability of process information, there are numerous practical benefits to be derived from their application. In addition to summarizing some of the concepts basic to these techniques, this paper describes the experience of the author in applying one of these advanced metallurgical balance techniques to a variety of pilot plant and commercial plant flowsheets during the past eight years.

Jan 1, 1983

By F. H. Rhines, A. H. Grobe

The constitution of the indium-zinc alloy series has been investigated by Wilson and Peretti,1 who determined the liquidus and eutectic temperatures by the conven-tional method of cooling curves and the eutectic composition by analyzing eutectic exudations. Recent developments affecting the availability of indium and consequent increased interest in its applications make a more complete knowledge of the constitu- tion of its alloys desirable. As a part of a program far the reexamination of the constitution of indium alloys by precision methods, the indium-zinc phase diagram (Figs. I and 2) has been redetermined in its entirety. The eutectic temperature (I43. 5°C.) reported by Wilson and Peretti has been confirmed exactly, but their value of the zinc concentration at the eutectic, 4 per cent, was found to be high; the new value is 2.8 per cent of zinc. There is also a rather large difference between the forms of the liquidus curves of Wilson and Peretti and those found in the present studies. The solidus curves herein have been located for the first time and the limits of solid solubility have been tenta-

Jan 1, 1944

By A. H. Grobe, F. H. Rhines

The constitution of the indium-zinc alloy series has been investigated by Wilson and Peretti,1 who determined the liquidus and eutectic temperatures by the conven-tional method of cooling curves and the eutectic composition by analyzing eutectic exudations. Recent developments affecting the availability of indium and consequent increased interest in its applications make a more complete knowledge of the constitu- tion of its alloys desirable. As a part of a program far the reexamination of the constitution of indium alloys by precision methods, the indium-zinc phase diagram (Figs. I and 2) has been redetermined in its entirety. The eutectic temperature (I43. 5°C.) reported by Wilson and Peretti has been confirmed exactly, but their value of the zinc concentration at the eutectic, 4 per cent, was found to be high; the new value is 2.8 per cent of zinc. There is also a rather large difference between the forms of the liquidus curves of Wilson and Peretti and those found in the present studies. The solidus curves herein have been located for the first time and the limits of solid solubility have been tenta-

Jan 1, 1944

By E. Gilpin

The Nova Scotian gold fields have yielded so little in comparison with those of the United States, that a lengthy description of them would almost appear unnecessary. However, not only are they interesting from a geological point of view, but experience has shown

Jan 1, 1886

The materials used for pump construction vary according to the nature of the solution handled. The pump materials in use are the result of extended experiment and are all giving satisfactory results. Research is still in progress, particularly with stainless steel and rubber lining, both of which show considerable promise. Following are the materials used: For tank-room acid, carrying about 100 grams per liter free sulphuric acid, hard lead is used. Stainless steel is under investigation. Duriron is satisfactory, but requires very careful handling to prevent mechanical breakage. For pulps containing low acid (10 grams per liter), abrasive solids, ferric iron, copper, etc. pumps are made of hard lead. Stainless steel is satisfactory. For pulps containing no acid but carrying abrasive materials and copper, bronze is used. Pulps containing acid (10 grams per liter), copper, iron and nonabra-sive solids require lead pumps. Rubber linings are under investigation. Clear neutral solutions containing copper are handled in bronze pumps; neutral solutions free of copper, acid, abrasive material, etc., in iron or bronze. The hard lead used contains 13 per cent antimony. The stainless steel has the following analysis: Cr, 20.0 per cent; Ni, 7.0; C, 0.25; W, 4.0; Cu, 2.0.

Jan 1, 1937

By D. E. Etter, J. E. Selle

The Pu-Ce phase diagram was determined by differential thermal analysis, metallography, and elechm-nricroprobe analysis. The dingram is chararterized by a eutectic with extensive solid solubility in the cubic Phases of both cerium and plutonium. No intermediate phases were found. Cerium is soluble in e plutonium to 16.0 at. pet Ce at 626OC nnd in d plcltoniurn to 23.0 at. pet at 613 "C, decreasing to 17.5 at. pet at room temperature. No solubility in the a, ß, or ? phases was jound, and the mininum cerium required to stabilize 5 plutonium to room temperature is 3.2 at. pet. The maximum solubility of plutonium in 6 cerium is 19.5 at. pet at 721OC, and the maximum soluhility of plutonium in ? cerium is 34.5 at. pet. Invariant points in the system are: a) eutectic at 626oC, L16.5 = E Pu16.0 + y Ce65.5; b) peritectoid at613oC, e Pu13.5 -y Ce65.5- d Pu23.0. AS part of a program aimed at the determination of the phase equilibria in the Pu-Ce-Cu ternary system, preliminary investigations were made of the three binary systems. A survey of the Pu-Ce binary system by differential therma1 analysis indi- cated several areas of disagreement with the published diagram,' primarily in the shape of the liquidus surface. Consequently, a thorough investigation of the system was undertaken, and this report presents the results of the study. EXPERIMENTAL PROCEDURE Three methods of investigation were used: differential thermal analysis (DTA), metallography, and analysis with electron-microprobe X-ray analyzer (EMX). The EMX analysis was particularly useful for the determination of solvus lines. The DTA method was most useful for the determination of the liquidus curves. Metallography complemented both of these techniques. Materials. The cerium metal used for most of this work had a freezing point of 805°C. This material showed 15°C premelting, and was found metallographically to contain some unidentified in~lusions.2 The temperature of premelting is defined as the point at which the DTA curve breaks away from the base line, analogous to a curve obtained from a solid-solution alloy. Several compositions were prepared near the cerium end of the diagram with higher-purity material which had a freezing point of 800°C. etallographic analysis showed this material to be relatively free of inclusions and only 8°C premelting was observed. Major impurities were found by spectrographic

Jan 1, 1964

By H. H. Evinger, M. Muskat

Although the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.' In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was measured and an attempt was made to determine the effectiveness if sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to deter-mine the effect of tamping were performed by Snelling and IIalL2 Small charges (zo grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.~ The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.6 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941