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By Michael Hoch

The phase diagrams of binary systems of some of the transition elements of Groups IV, V, and VI were used to compute the partial free energies of these elements and the free energy of formation of their Laves-type compounds. From these data, isothermal sections of ternary phase diagrams were calculated and compared with experimental results. DURING the investigation of ternary and quaternary high temperature systems formed by the transition elements of Groups IV, V and VI, the binary phase diagrams for these elements available in the literature were studied. In this study, the free energies of formation of the compounds formed in these binary systems were calculated; these values were then used to determine the general shape of the ternary and quaternary phase diagrams. Above 900°C, the transition elements of Groups IV, V, and VI are all bcc and form only Laves-type compounds in binary systems. The investigation was based on the binary phase diagrams published by Hansen.1 The Cr-Nb system was constructed from the data of Elyutin and Funke.' Several unpublished phase diagrams were taken from Schmidt'sLo and English'sl1 compilations. THE BINARY SYSTEMS valuations of the Thermodynamic Functions. Rostokers evaluated the boundaries of the (a + b) field in Ti-base alloys with a two-constant equation. The authors' interest is mainly in the center of the diagrams; therefore the miscibility gaps in the Zr-Nb, W-Cr, Ta-Zr, Ta-Hf, and Ti-W systems were used to evaluate the thermodynamic behavior of the binary systems. Lumsden's4 Equations 29.2, 32.1, and 33.1, page 287, were used for the excess integral free energy FeX, and for the excess partial free energies Fx and replaces b and b replacesP in Lumsden's notation):

Jan 1, 1962

By Alexandre Pourcel

The phenomena of liquation in steel or iron ingots of all sizes, but naturally to greatest extent in the heaviest ingots, have been noticed ever since the commencement on a large scale of the Besse mer and open-hearth manufactures; but they have been studied with care during the last few years only. The English and the Ameri cans were the first to publish the results of investigation upon phe nomena of this clam, to which they have given the name of segregation. Historical. Passing by that which has been written concerning the segregation observed in gray pig-iron, of which instances were given by Karsten, we shall confine ourselves here to that which is known of this subject with exclusive reference to ingot steel and iron. Mr. H. M. Howe, of Boston, in his Metallurgy of Steel, the most complete and well-arranged treatise upon steel, gives a resume of observations, with the results of numerous analyses, bearing upon the phenomena of segregation. According to Tchernoff (with whom we discussed this question at length in 1878, in connection with the cast-steel plates of large dimensions designed for the Italian fleet, which we showed him at Terre-Noire), Kalakoutsky called attention in 1866 to the lack of homogeneity in Bessemer ingots, especially when cast in sand. Our own attention had been called to the phenomena of liquation in 1868 by a somewhat surprising fact which appeared in almost every one of a number of steel-rail ingots coming from the works of Messrs. Pierre and Emile Martin at Sireuil, to be rolled at TerreNoire. In the heating or in the first groove of the rolls, a slice of from 6 to 10 centimeters (2.4 to 3.9 inches) separated itself from the head of each ingot. As a general consequence, the section of

Jan 1, 1894

By Charles P. Williams

BY PROFESSOR CHARLES P. WILLIAMS, ROLLA, MISSOURI. During the fall of the year 1873, attention was redirected to the occurrence of lead ores in Southwestern Arkansas (chiefly in Sevier County), and somewhat extensive explorations of the deposits have since been made in the hope of finding the ores sufficiently argentiferous to be profitably worked. How far the expectations have been realized I am not authentically advised, but samples of the galena ore, yielding 62.09 per cent. of lead, gave on assay at the rate of 15 3-10 ounces of silver to the ton of ore. This was the highest result obtained by myself, though I am informed that higher yields have been obtained by others. Among the samples of ores from this locality, forwarded to me in January last, was one specimen which I at once recognized as stibnite, and, on notification, other specimens of the same from Sevier County were forwarded me. The first specimen of the several received contained 11.51 per cent. of gangue, 57.62 per cent. antimony, 4.57 of bismuth, with small amounts of arsenic and iron. The latest result from a portion of another hand specimen I append in full, with duplicate estimations of the arsenic, bismuth, and gangue. The analyses were all conducted by Mr. C. R. Winters, under my direction, and in the case of those given below the ore mas separated as closely as possible from the gangue before analysis. The results are for the mineral freed from hygroscopic moisture, and are as follows: I. 11. Mean. Sulphur,.. 28.618 .. . 28.518 Antimony,.68.576 .. . 68.676 Arsenic,..6 47 .474 .497 Bismuth,..521 .498 .509 Iron,.......762 .. ..762 Gangue,..944 .948 .946 99.868 99.808 This result indicates that the ore is stibnite.

By Thomas Fraser, H. F. Yancey

The jig may be termed the standard coal-washing machine. Although exact figures on the relative tonnages of coal treated by the various coal-cleaning processes are not available, it is known that a large part of all the coal given special cleaning treatment is handled by jigs. This wide use of the jig warrants a special study of its performance. In this paper are presented the results of an analysis of work done by a three-compartment jig in treating bituminous coal from the Thick Freeport bed in Allegheny County, Pa. Certain systems of washing coal require sizing before washing, while others treat unsized coal. The prevailing practice, however, for the preparation of coking coal from the more easily washed coal is to treat an unsized or natural feed of about — 1 in. size and smaller. Under such conditions, the minimum size of particle that is beneficiated has long been and is still a matter of discussion and conjecture. In a careful laboratory investigation J?ngstl concluded that the practical limit of settling of fine coal is reached at from 0.02 to 0.008 in. On the other hand, Hancock2 has found that single-compartment jigs, used in preparing coal for the domestic market, usually allow most of the heavy (refuse) particles smaller than 1/4 in. to go into the washed coal. He also states that it is impossible with the ordinary coal jig to make any noticeable improvement in the quality of the coal finer than 20 mesh (about 1/30 in.). Because of its importance in coal cleaning, the work described in this paper was undertaken for the purpose of obtaining information on this subject, as a part of the general coal beneficiation program being carried out by the Bureau of Mines.

Jan 1, 1925

By Dorsey Hager

THE information given in the accompanying table is submitted as evidence confirming the application of the anticlinal theory and the value of geology in the Kansas and Oklahoma oil fields. The term anticline has been used to define a particular type of arched fold. The anticlinal theory of oil accumulation should, however, be broadened to include any structural fold of an arched type even if not a distinct anticline. A terrace may very properly come under the heading of the anticlinal theory of accumulation, as the folding is closely related to that of the anticline; in fact, in many cases is an arrested anticline, though not completely closed in all directions. Stratigraphic forms due to lensing or irregular cementation of the sands certainly cannot be considered to fall within the anticlinal theory, though the laws of accumulation may be similar. A dome is similar to an anticline and belongs to the same class. A dome is broader in proportion to its length than an anticline. Many anticlines undulate along their axes to form domes. The anticlinal theory in this discussion will then be applied to anticlines, domes and terraces. In the following list, the writer has tabulated the main oil fields of Oklahoma, and a few recently discovered fields in Kansas. The fields discovered within the past 4 years are listed with the date of their discovery. Under "How found," the writer puts "Wildcat" where a geologist has not been employed, "Geology" where it has been used, and "?" where there is doubt. In some places the geologists have claimed pools that may rightly belong to them, but their claims have been questioned, so that they belong in an unsettled category.

Jan 2, 1917

Statistics compiled by the United States Geological Survey show that the iron ore mined in the United States in 1917 reached a total of 75,288,851 gross tons, exceeding the former record output of 1916 by 121,179 tons. The shipments from the mines in 1917 were 75, 573,181 gross tons, valued at $238,260,333, a decrease in quantity of 2,297,372 tons, or 2.95 per cent., and an increase in value of $56,358,056, or 30.98 per cent., over the shipments in 1916. The average value per ton at the mines for all grades of ore in 1917 was $3.15 as against $2.34 in 1916. Stocks of iron ore at mines, mainly in Minnesota and Michigan, amounted at the close of 1917 to 10,628,908 gross tons, compared with 10,876,352 gross tons in 1916. The quantity of pig iron, exclusive of ferro-alloys, sold or used in 1917, according to reports of producers to the United States Geological Survey, amounted to 38,612,546 gross tons, valued at $1,053,785,975; compared with 39,126,324 gross tons, valued at $663,478,118 in 1916, a decrease of 1.32 per cent. in quantity and an increase of 59 per cent. in value. The average price per ton at furnaces in 1917, as reported to the Survey, was $27.29, compared with $16.96 in 1916, an increase of 61 per cent. The production of pig iron, including ferro-alloys, was 38,647,397 gross tons in 1917, compared with 39,434,797 gross tons in 1916, a decrease of 4.5 per cent., according to figures published by the American Iron and Steel Institute, March 18, 1918.

Jan 12, 1918

By James A. Barr

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By James A. Barr

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By C. K. Leith

THE questions as to what grades of ore it pays to conserve for the future, and the valuation of low-grade reserves, are becoming immediate and definite as applied to individual ore deposits, and seem to call for some sort of quantitative answer. Both opinion and practice involving these questions differ widely. The number of variables in this problem is so large that final solution will perhaps never be agreed upon, yet there seem to me to be certain controlling factors which can be placed in quantitative relation and serve to reduce the number of variables which it is necessary to consider in a given instance. I assume that it will not pay either for the individual or for the State to conserve any ore when the present cost of conservation (by stock piling or otherwise), when compounded at 6 per cent. interest for the number of years which would elapse before this ore is used, will exceed the profit which the ore will yield when it is used. It may be urged that any loss to the individual may be made up in gain to the State. This might be true if there was any definite limit to the amount of iron ore, but when we remember that iron makes up .4 per cent. of all the rocks of the earth and the amount of rock carrying iron in excess of 20 per cent. is for practical purposes, unlimited, it is apparent that posterity is assured of its iron ore. The changes will be mainly in methods and cost of extracting the ore. Therefore, any expenditure of money or effort now, which when compounded will exceed the worth of the effort or money needed in the future to utilize the iron, is a net loss both to the individual and to the community.

Jan 2, 1914

By F. M. d’Heurle

Films of molybdenum have been prepared by sputtering onto oxidized silicon substrates. The resistivity. lattice parameter, orientation, and grain size were studied as a function of substrate temperature and substrate bias. Under normal sputtering conditions, the resistivity of the films was found to be quite high (600 x 10 ohm-crn). However, with the use of the negative substrate bias of 100 v and a substrate temperature of 350°C, films weve produced with a resistivity of ahout twice that of bulk molybdenum. The lattice parameters measured in a direction nornzal to the surface of the films weve found to be gveatev than the bulk value. This was interpreted as being at least partly due to the presence of compressive stresses. The effects of annealing in an Ar-H atmosphere were studied in terms of diffraction line width, lattice parameter, and resistivity. BECAUSE of its relatively low bulk resistivity (5.6 x 106 ohm-cm)' molybdenum is potentially interesting as a thin-film conductor in integrated circuits. An additional feature which makes it attractive for this purpose is its low coefficient of expansion (5.6 x KT6 per "c),' which is fairly well matched to that of silicon (3.2 x 10 per c). It is possible to deposit molybdenum films by evaporation but generally films produced in this manner have a high resistivity. In order to achieve resistivities close to bulk value, Holmwood and Glang found it necessary to operate in a vacuum of about 107 Torr and to maintain the substrates at 600 C during film deposition. Sputtered molybdenum films have been examined by Belser et a1.7 and, recently, by Glang et al.' This paper describes the results of an attempt to extend some of that work and examine the effects of annealing and getter sputtering on the physical and structural properties of the films produced. SPUTTERING APPARATUS AND PROCEDURE The apparatus used for most of the film sputtering work described here consisted of two "fingers" serving as anode and cathode, respectively, which were mounted within an 18-in.-diam glass chamber. A liquid nitrogen-trapped 6-in. diffusion-pump system was used to achieve a vacuum of about 1 x 107 Torr within the chamber prior to sputtering. The essential features of the equipment are shown in Fig. 1. Cathode and anode fingers are stainless-steel tubes isolated from the top and bottom plates by Teflon collars. In order to limit the discharge to the space between anode and cathode, each finger is surrounded by an aluminum hield, at ground potential, having an internal diameter 18 in. larger than the outside diameter of the finger. The cathode and anode fingers are 6 and 4 in. in diam, respectively. A 116-in.-thick sheet of molybdenum is brazed with a 10 pct Pd, 58 pct Ag, 32 pct Cu alloy to a copper disc which is mounted by means of screws and a large 0 ring onto the lower end of the cathode finger. The disc is cooled during sputtering by water circulation inside the finger. The use of several feet of plastic tubing for the water input and outputg reduces leakage to ground to less than 1 ma when the cathode potential is raised to 5 kv. The upper end of the anode finger is terminated by a brazed-on copper block. A variety of specimen holders can be easily mounted on the upper face of this block. Substrate heating or cooling is achieved by use of an appropriate unit attached to the lower face of the same block. Heating is achieved by means of cartridge-type heaters and cooling by copper coils fed with forming gas under pressure. The inner chamber of the specimen finger constitutes a small vacuum chamber of its own which is evacuated by an auxiliary mechanical pump in order to limit heating element oxidation and heat transfer by convection currents. An advantage of the finger arrangement is the absence of cooling and heating coils and wires within the main chamber. The stain less-steel shutter is useful to establish a discharge for cleaning the cathode at the beginning of each sputtering run. Water cooling of the shutter reduces heating and the out-gassing of impurities which might condense on the nearby substrates. Unless otherwise specified, the substrates used in these experiments were 1-in.-diam oxidized silicon wafe:s, 0.007 in. thick, having an oxide thickness of 6000A. The substrate holders were large copper discs onto the surface of which a number of molybdenum discs, 116 in. thick and 78 in. in diam, were brazed. The wafers were clamped to the molybdenum discs

Jan 1, 1967

Executive HOWARD N. EAVENSON, Chairman FREDERICK M. BECKET EDGAR RICKARD ERLE V. DAVELER WILLIAM WRAITH Finance HENRY KRUMB, Chairman PAUL I). MERICA J. V. W. REYNDERS H. G. MOULTON, Consultant Admissions JOHN M. LOVEJOY, Chairman GEORGE D. BARRON DONALD M. LIDDELL ELI T. CONNER WILLIAM W. LYNCH Alternates WM. H. BASSETT, JR. L. B. LINDEMUTH W. A. SINSHEIMER

Jan 1, 1934

Mining headlines in 1952 dealt mainly with expansion as the industry aimed for an ever increasing production to meet the nation's needs. Huge sums were expended for equipment, research, and development. Headlines told part of the story. Negotiations between San Manuel Copper Co. and the RFC finally resolved in a $94 million loan for the development of low grade Arizona ores. Magma Copper, parent firm was to supply an additional 8 million. Kennecott Copper Co., deepening its Deep Ruth Shaft of its Ruth, Neyy mine, announced that the shaft would be in full production in 1953.

Jan 2, 1953

YEAR OF ELECTION 1913. FRANK DAWSON ADAMS, Montreal, Canada. 1933. KARL EIKERS New York, N. Y. 1922. FEDERICO GIOLITTI Torino, Italy. 1906. SIR ROBERT A. HADFIELD London, England. 1921. FRANK WILLIAM HARBORD London, England. 1917. HERBERT HOOVER Washington, D. C. 1941. DANIEL COWAN JACKLING San Francisco, Calif. 1939. HENRY KRUMB New York, N. Y. 1921. C. McDERMID London, England. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1935. ROBERT PEELE New York, N. Y. 1938. A.M. PORTEVIN Paris France 1937. JOHN V.W. REYNDERS, New York, N. Y. 1937. GEORGE S. RICE Washington, D. C. 1911. ROBERT H. RICHARDS Cambridge, Mass. 1934. T.A. RICKARD Victoria, B.C., Canada

Jan 1, 1941

By Philip E. LaMoreaux

Fluoride, generally less than 0.5 ppm, is present in ground water from rocks of Paleozoic age and older, in northern and eastern Alabama. Some of the water-bearing formations in the Coastal Plain area of the State yield water with as much as 6.8 ppm fluoride.

Jan 8, 1950

By John W. Vanderwilt

THE unpredictable behavior of ground movement and subsidence has complicated the problems that attend the extraction of large quantities of ore. Special studies, particularly relating to coal mining, have yielded such a voluminous literature and so many involved controversial theories that a partial review would be difficult. Limited space makes any kind of a review impractical. The features to be considered cover only a relatively small part of the broad problems of ground movement and subsidence, but it is believed that this small part is critical. The practical aspects are important, since they bear directly on safety of mine workings, on recovery of ore and on dilution of ore in block caving and related systems for extracting large quantities of rock. The ground movement to be described occurs outside the vertical boundaries of a caved block in the area that is commonly referred to as being in the "zone of draw." "Draw" is a term that originated in the subsidence problems related to coal mining, and it is defined by a line drawn from the margin of the area caved underground to the most distant fracture at surface on the same side of the caved area as shown in Fig. I.1 " A line thus drawn is called the cave line, and its angle with respect to the horizontal is the cave angle or angle of draw. It is understood that the line is taken normal to the limit of mining, and in a vertical plane. The prevailing theories as to draw and angle of draw assume that appreciable movement occurred along the cave line, which has been described as a fracture resulting from the shearing action brought about by the weight of the overlying load. Fig. 2 shows diagrammatically the mechanics of ground movement adjacent to an area of subsidence according to the prevailing theory of draw (A, from Royce2) and, for comparison, ground movement observed in the Climax mine (B). The text in Peele's Handbook2 referring to Fig. 2 does not state the meaning of the "original position of top of workable ore" in the rectangular space above "ore in place," and the arrows are not explained. However, this presentation is most concerned with the zones outside the rectangle. According to the prevailing theory, as shown at the extreme left under A, Fig. 2, the vertical tension cracks at surface change at a shallow depth to shear fractures forming the cave line, and it is assumed that appreciable movement takes place along the cave line toward and into the subsiding caved block. The mechanics of ground movement observed in the Climax mine, as shown under B, Fig. 2, does not accord with the prevailing theory, particularly as regards the cave angle and draw. The vertical

Jan 1, 1946

By L. C. Brown, S. K. Behera

The diffusion rate in Ag-Sb couples is sensitive to con~pressive load with the width of Ag3Sb, the only phase present in the diffusion zone, increasing with stress up to 800 psi and remaining constant above this. Kirkendall marker experiments show silver to diffuse much faster than antimony in Ag3Sb and incipient porosity may therefore develop at the Ag/Ag3Sb interfnce restricting the transfer of atoms from the silver into the diflusion zone. Application of compressive stress reduces the tendency for porosity to develop and so increases the growth rate. In a recent paper Brown et al.1 observed a significant increase in the thickness of Cu2Te in Cu-Te diffusion couples on application of a compressive stress as low as 20 psi. Similar stress effects have also been observed in the Fe-A1,2 Al-u,3 arid cu-sb4,5 systems. It has been suggested that the increase in growth rates of intermetallic phases in these systems is due to a decrease in the amount of Kirkendall porosity with applied stress. In the present paper, results are presented of the effect of compressive stress on diffusion in Ag-Sb, together with a detailed examination of the Kirkendall effect. The Ag-Sb phase diagram6 shows that antimony has a moderate degree of solid solubility in silver, 5.7 at. pct at 350°C, but that there is essentially no solubility of silver in antimony. There are two intermediate phases— (hcp7) from 8.8 to 15.7 at. pct Sb and Ag3Sb (orthorhombic8) from 21.8 to 25.9 at. pct Sb. EXPERIMENTAL Diffusion couples were prepared from fine silver of 99.95 pct purity and from antimony of 99.7 pct purity. Both the silver and antimony were produced in the form of discs 1/2 in. in diam by approximately $ in. thick, with surfaces ground flat to 3/0 emery paper. Diffusion anneals were carried out in the apparatus previously described.1 A compressive load was applied to the diffusion couple through a lever arm system, with a reproducibility estimated to be ±10 psi. All runs were carried out in a protective hydrogen atmosphere. Following the diffusion anneal specimens were sectioned and polished and the width of the diffusion zone was measured metallographically. Composition profiles were measured using an electrostatically focused electron probe with a spot size of 10 , counting on Sb L radiation. Corrections for matrix absorptiori and fluorescent enhancement9 were not required. S. K. BEHERA, formerly Graducate Student, Department of Metallurgy, University of British Columbia, is now Postdoctoral Fellow, Whiteshell Nuclear Laboratories, Atomic Energy of Canada Ltd., Pinawa, Manitoba. L. C. BROWN, Junior Member AIME, is Associate Professor, Department of Metallurgy, University of British Columbia, Vancouver, B.C., Canada. Manuscript submitted June 14, 1968. IMD RESULTS Fig. 1 shows an electron probe traverse of a typical diffusion zone. In all couples examined only one intermediate phase was observed and the composition of this phase, 23 wt pct Sb, was in good agreement with the composition of Ag3Sb, 23 to 28 wt pct Sb. The presence of this phase was confirmed by X-ray diffraction of filings taken from the diffusion zone. The probe traverses showed no detectable solid solubility in either the silver or the antimony although the phase diagram indicates that some antimony, up to 6.5 wt pct pct Sb, should be in solid solution in the silver. However the width of this portion of the diffusion zone would be expected to be very small in view of the low diffusion coefficient in the silver, 4 x 10-l6 sq cm per sec at 350°C, 10 compared with that in the Ag,Sb, estimated as 3 x 10-8 sq cm per sec in the present work, and this region would therefore not be expected to be seen in the probe traverse. Application of stress resulted in a significant increase in the width of the diffusion zone, Fig. 2. At 350°C, the thickness of Ag3Sb increased from 250 at 0 psi to 400 p at the limiting stress of 800 psi, indicating an apparent 150 pct increase in the diffusion coefficient. Similar behavior was also observed at 400°C, indicating that the stress effect is not characteristic of just one temperature. The growth of Ag3Sb at 350°C and at various stresses is shown in Fig. 3. In every case the growth rate was parabolic indicating diffusion control. The kinetic curves all passed through the origin showing that delayed nucleation of Ag3Sb was not responsible for the stress effect and that it was a real growth effect. A series of tests were carried out in which diffusion was allowed to take place at a lower stress following an initial high stress diffusion anneal. Speci-

Jan 1, 1969

By Denis Yeung, B. H. G. Brady

A hybrid finite element-boundary element code with eight noded isoparametric finite elements and three noded boundary elements is described for plane strain and linear isotropic elasticity. In the direct formulation of the Boundary Flement Method, quadratic variation of geometry and displacements, and linear variation of tractions with respect to the element intrinsic coordinates are used. The boundary element region is treated as a "super-element" in the finite element sense.

Jan 1, 1982

By Alexander N. Mitinsky

UP to a certain limit, the increase of pressure on the diamond-drill increases the rate of progress in drilling. That limit is set by the resistance of the diamonds to compression; and beyond it, the destruction of the stones will involve an. economic loss, both in time and in money. It is, therefore, important to all diamond-drillers to know what is the resistance mentioned. In Europe, operators usually follow an empirical rule, which directs the maintenance of a pressure, on the area-of the bottom of the drilling-tool, of 12 kg. per sq. 4m. For the tools in ordinary use, this is equivalent to 1 kg. per sq. mm. of the diamonds set in the tool So far as I know, American drillers are using pressures as high as 50 to 60 kg. per sq. cm. of the total area of the drill, and the consumption of diamonds (on Denny's authority, 0.2 carats per meter bored) is greater in America than in Europe. But the reason for this difference may be the comparatively larger size of the diamonds commonly used by American drillers. With the assistance of my friend, the late S. Woisslaw, who was the pioneer of diamond-drilling in Russia, I selected from his stock a number of black diamonds, which I subjected in my laboratory to compression-tests. To prepare regular cubes for such tests, as is generally done with other stones, would have been not only costly, but, what is more important, practically useless. I therefore determined, in order to assimilate as nearly as possible the conditions of actual use, to place each sample between a hard plate (corresponding to the rock) and a softer plate (corresponding to the bottom of the tool), into which it would be pressed during the test.

Jan 1, 1906

By William L. Lennemann

Chemistry of uranium with respect to its hydrometallurgical recovery from carnotite ores was investigated and well defined during the radium boom period between 1900 and 1920. Since that time, methods used to extract uranium from its ores have remained basically either acid leaching or sodium carbonate leaching. Until about 1950, the only practical methods known for achieving a better than 75 pct U2O3 concentrate from the leach liquors involved fundamental chemical techniques for either purifying a solution prior to the uranium precipitation, or refining a crude uranium concentrate that was produced by neutralizing a pregnant mill liquor.

Jun 1, 1956

By C. P. Parsons

During the past year considerable interest has been shown in cementing operations for shutting off bottom water, whipstocking, etc. A number of plug-back methods have been used, with various adaptations for special conditions, but those described in this paper are representative of the methods now in use. Conditioning the Well Various preliminary operations for improving the results from plug-back operations have been evolved. In one method, a nitroglycerin shot is discharged at the upper portion of the formation to be plugged off, the purpose being to make a wide place in the hole in order to give the cement a more secure anchor against thrust pressure of the water against the bottom of the cement plug after the well is again put on production. Another is intended to attain a similar result by under-reaming a wide place in the hole by means of a rotary wall scraper. In one well in which this device was used there was a water sand at the bottom of the well immediately below the cap rock above which the oil sand occurred. Before the plugging back operation, the water sand was underreamed in an attempt to get a square shoulder on the underside of the cap rock, in order to prevent the water from breaking in over the top of the cement plug after the well should be put on production, and also to get a more secure anchor for the cement plug against the thrust pressure of the water against it. As an aid in calculating the amount of cement required to fill a given amount of hole to be plugged back, a device has been developed for measuring and recording the irregularities and cavities in open holes, called an "open-hole recording caliper." If consists of a steel shell, 5 in. in diameter, which encloses a recording mechanism that receives impressions from four movable arms that make sliding contact with the wall of the hole. The arms operate a ratchet, which raises and lowers a recording stylus against a chart. Each arm registers its own radius. The device is run into a well on a steel measuring line. While the device is being lowered, the arms are folded inside the shell; they are

Jan 1, 1936