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By Hallet R. Robbins

KOREA, the ancient " Hermit Kingdom," is a peninsula jutting out from the coast of eastern Asia. By the natives it is called " Chosen," which, translated, means " Land of the Morning Calm." It lies between the Yellow sea and the Sea of Japan. On the north it is separated from Manchuria and the Russian province of Primorsk by the Yalu and Tiumen rivers ; on the south the Korean straits interpose a rough voyage of 120 miles to the nearest point in Japan. The entire country is situated between the parallels of 34° and 42° N. latitude. The surface of the country is made up of successive ranges of unglaciated mountains, separated by narrow, fertile, and more or less densely populated, valleys. Through all the obscure centuries of its history, Korea has succeeded in maintaining a monastic seclusion, over which, from time immemorial until the late Chino-Japanese war in 1894, China exercised a shadowy sovereignty. Although Korea had been forced into slight foreign contact previously, her first foreign treaty was signed with Japan in 1876. Under the restraining guardianship of China, the Japanese treaty bore but insignificant innovations for Korea; but when, in 1883, a treaty was made with the United States, the first of the western nations, a decade after the American gunboats, under Commodore Rodgers and Lieutenant Schley, forced their way up the Salee river, shooting daylight through the ancient walls and fastnesses, Korea awoke from her sleep of 4,000 years. The Korean peninsula suddenly became the arena where rival nations' enterprises and individuals met in fiercest conflict. Out of this struggle grew two singularly successful American

Jan 7, 1908

By Y. Nakahiro

The removal of heavy metal compounds from a synthesized waste cyanide solution is achievable by a precipitation-flotation method. However, the differential separation of constituting metals by this method was thought to be very difficult. The present author found that addition of ferrous salt to the synthesized waste cyanide solution of cadmium and copper can modify the separation characteristics of these metals. In this paper, the separation of cadmium from copper in the synthesized waste cyanide water by the precipitation-flotation method is discussed. This differential flotation uses ferrous salt as a precipitant and sodium oleate as a collector. Based on a series of fundamental flotation tests, actual differential flotation tests were made. The separation of cadmium from copper in the synthesized waste cyanide water was found to be satisfactory. This method can be effective for the removal of difficult-to- separate colloidal precipitates from liquids by the sedimentation method, provided the applicability of this method to the separation of the other metals is promising. This consists of the intensive studies which have been conducted at author's laboratory.

Jan 1, 1980

By R. Kossowsky

In the course of a study concerned with structural stability of precipitation hardening nickel base super -alloys after exposures to elevated temperatures, some interesting effects of hydrostatic pressure treatment on Rene were observed. The evidence presented below suggests that hydrostatic pressure treatment of the solution heat-treated alloy can affect the dispersion of the y' (Ni3Al) phase upon subsequent precipitation heat treatment and long time aging. Rene 41 alloy has the following nominal weight percent composition: Al B C Co Cr Fe Mn Mo Ti Ni 1.4 0.006 0.7 11.3 19.2 1.0 0.05 9.4 3.3 balance The effect of successive pressure, precipitation heat treatment, and long time aging on the microstructure of this alloy was determined by subjecting a number of alloy buttons to five different thermopressure treatments. Pressure and precipitation heat-treatment parameters are listed in Table I. Fig. 1 shows y' morphology* of specimens in groups I and 11. The treatment results in a fine dispersion with particle size on the order of 950 and 1350A, respectively, see Table I. Fig. 2 shows the morphology of y' precipitate in

Jan 1, 1967

By Bieniawski, Z. T.

The importance of understanding the phenomena associated with rock fracture has long been fully appreciated in rock mechanics. This is clearly apparent from the special attention paid to rock fracture in the comprehensive papers published within the past four years. These papers present a picture of how the knowledge of brittle fracture of rock was gradually enriched and also show that what was often taken for granted three or four years ago is no longer considered as valid today.

Jan 1, 1972

By John Birkinbine

(New Haven 'Meeting, February, 1909.) AWAKENED public interest in efforts to conserve natural resources will certainly be appreciated by the members of the American Institute of Mining Engineers, and a discussion upon conservation may well form a part of one of the Institute meetings, for the records of papers and discussions which appear in the 38 volumes of its Transactions are replete with evidence of effort's in this direction. Every process which reduces the fuel consumed or the power applied per unit of product; every utilization of waste material, or employment of that formerly rejected, to obtain something of value ; every feature of construction or operation which lessens the labor required or increases the output per employee, is an advance in the direction of true conservation. This may not appear from the records of late conferences or from published articles, in which the effort seems to be concentrated upon reducing the consumption and presenting to the people of the country estimates of exhaustion of natural resources. I rejoice in the awakening of public interest in a matter so important for the present and future welfare of our nation; I appreciate the possibility of much good following conferences of the Governors and delegates from various States and from national societies; and I recognize the interdependence, not only of different States, but of contiguous nations. In fact, the marvelous development of transportation by land and by water, and the decreasing rates at which commodities can be moved great distances, have in many cases practically obliterated geographical boundaries, and nearly every country on the globe can either market its product in other lands or draw upon them for raw or manufactured materials ; hence, conservation is an international subject.

Apr 1, 1909

By G. V. Raymor, James T. Waber, I. Rex Harris

The lattice parameters of a series of fcc alloys of cerium and thorium were measured at 93 " and 298OK. Lattice parameters were also estimated for 171OK. Substantial deviations, y, from Vegard's law were observed. Although y was negative at the two higher temperatures, it was positive and large at the lowest temperature. A variety of models, which have been proposed in the past, were considered, and the calculated values of y were compared with the observed values. The best agreement was achieved with values computed with Friedel's equation. THE purpose of this investigation was to determine the effect of temperature on the lattice parameter and on deviations from Vegard's law of Ce-Th alloys. A large negative deviation from Vegard's law was first observed independently by Weiner, Freeth, and Raynor' and Van vucht2 in the room-temperature lattice parameters of Ce-Th alloys that form a continuous series of solid solutions. This observation was confirmed by Evans and Raynor. The allotropy of unalloyed cerium was reviewed recently by Gschneidner, Elliott, and McDonald. In two subsequent papers,5" these authors reported the influence of various alloying additions on the y= transformation, which occurs below room temperature. Although other rare earths tend to stabilize the double-hexagonal phase, thorium, plutonium, and scandium as solutes tend to stabilize the normal fcc phase. With addition of sufficient thorium as a solute, there is evidence that the formation of is suppressed and it becomes possible to pass continuously with decreasing temperature from the room-temperature phase to the fcc a phase. Thus there is a closed loop which is similar in many ways to the y loop well-known in ferrous alloys. A closed field also occurs in the pressure-temperature "equilibrium" diagram of unalloyed cerium. Because of interest in the effect of thorium additions and their influence on the a and phases, lattice-parameter measurements were made at low temperatures on the fcc phase for a series of alloys ranging from 10 to 90 at. pct Th. The results obtained at three temperatures are shown in Fig. 1. Evans and Raynors analyzed the deviations from Vegard's law in Ce-Th alloys in terms of changes in the occupancy of the 4f electron level in cerium,

Jan 1, 1964

By R. Malmstrom, H. Heden, K. Likin

Sublevel caving techniques at Luossavaara-Kiirunavaara AB (LKAB) in Sweden have undergone significant modification over the years as management strives to maintain mine viability amidst rising costs and erratic iron ore prices. LKAB, which is 96% state-owned, is Sweden's principal iron ore producer and operates three iron mines north of the Arctic Circle. By far, the largest of LKAB operations is the Kiirunavaara (Kiruna) underground iron mine which extracts an estimated 30 million t/y of ore, Other iron mines include the Malmberget underground nine, rated at 12 million t/y of ore, and the Svappavaara open-pit mine, rated at about 4.5 million t/y. Mined ores from Kiirunavaara and Svappavaara are shipped by rail to the northwestern harbor of Narvik, while Malmberget ores are sent to Lulea, located to the southeast. LKAB iron ores are marketed by Malmexport AB, which is owned jointly by LKAB and Granges, Sweden's base metal producer.

Jan 10, 1979

By Samuel B. Christy

At the last meeting of the Institute, several contributions were made to the subject of miners' aid funds. Such matters will always form important factors in the administration of large industrial enterprises. From the frequently remote and isolated position of mining properties, it is a subject that often forces itself upon the attention of the mining engineer. Local conditions are usually so variable that no single method can be found equally well adapted to all localities. At the same time, a study of different types is often suggestive and valuable, and it is with this in view that these notes are presented. The Miners' Fund of New Almaden is a remarkably successful example of what may be done for miners by a wise and at the same time firm management, by simply directing their own efforts and without incurring any great expense to the stockholders,—a practical consideration not without importance in most cases. The quicksilver mines of New Almaden are situated at a distance

Jan 1, 1885

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during the period April 1 to 15. William B. McKinley, New York, N. Y Collier Cobb, Chapel Hill, N. C. C. W. Goodale, Butte, Mont. E. P. Fleming, Guayacan, Chile. D. C. Brown, San Luis Potosi, Mex. Albert Sauveur, Cambridge, Mass. W. H. Rettie, Yonkers, N. Y. H. M. La Follette, La Follette, Tenn. Mark B. Kerr, San Francisco, Cal. E. Fleming L'Engle, New York, N. Y. H. W. Turner, San Francisco, Cal. H. Garlichs, St. Louis, Mo. Frank M. Leland, Mackay, Idaho. Henry Hay, London, England. Sir Robert Hadfield, London, Eng. Edward J. Way announces that his agreement as consulting engineer in South Africa for the Anglo-French Exploration Co., Ltd., having terminated, he will engage in professional consulting work with headquarters at 135 Cullinan Buildings, Simmonds St., Johannesburg, South Africa.

Jan 5, 1914

By A. O. Dady

PRODUCERS of both bituminous and anthracite coal have for many years been worrying about the gradually decreasing consumption of their product in the United States. Twenty years ago production had climbed to a peak of 569,000,000 tons of bituminous and around 90,000,000 tons of anthracite. In 1939 it was about 393,000,000 tons of bituminous and 51,000,000 tons of anthracite. This does not mean that the country is using less polver than it did twenty years ago, or that we are living in colder buildings. As a matter of fact, about three times as much electric power is now being consumed as in 1920. In general two factors are responsible for the drop in coal consumption: (1) greater efficiency in the use of coal, and (2) increased competition from hydro power, internal-combustion engines, and substitution of oil and gas for coal in conventional furnaces. As to the first factor, it took 3 Ib. of coal to generate a kilowatt-hour of electricity in central stations in 1920 and it takes 1.4 Ib. now; it took about 175 Ib. of coal in railroad locomotives to haul 1000 long tons a mile in 1920 where it talces about 120 lb. now: and marked economies have also been made in the use of coal in steel plants: in by-product coke ovens, and in other large uses. As to the second factor, three times as much electricity is produced from water power now as was produced in 1920; three times as much oil is being consumed in various ways; and likewise, the consumption of natural gas has tripled- whereas coal consumption in the same period has dropped by 40 per cent

Jan 1, 1941

By J. B. Dilworth

OUTCROPS of coal have bees discovered is many localities is the Philippine archipelago, and practically all of the larger islands contain deposits of this mineral. Very little prospecting has been done to determine the value of the various coal-bearing areas, but so far as known, the largest and most promising fields are found : (1) is northern Cebu; (2) is the small island of Batan, a part of the province of Albay is southeasten Luzon; (3) is the somewhat larger island of Polillo, off the east coast of Luzon, and (4) is southern Mindoro, sear the small coast tows of Bulalacao. Northern Panay, south-central Cebu, and various localities is southern Luzon, Masbate, Negros, and Mindanao also afford evidences of the existence of coal-beds, the extent and value of which have not yet bees proved. The general position of these islands and districts is shows on the map of a portion of the Philippine Islands, Fig. 1. Some of these coal-fields have been known for many years (coal was discovered is Cebu 1827 and is Batas is 1842),1 and several futile attempts were made by the Spaniards to operate mines is these districts. But owing to many circumstances, chief among which were indifferent management, the political unrest of the islands, natural difficulties of transportation, and those inherent in the mining of steeply-inclined and somewhat irregular seams, no considerable output was ever obtained from any of these mines, and the fuel required is the many departments of industrial and political life has continued to be drawn largely from Australia and Japan. These conditions exist to a great degree at present, and though much interest is the coal-deposits of the Philippines

Jan 1, 1909

YEAR OF ELECTION 1913. FRANK DAWSON ADAMS, Montreal, Canada. 1921. WILLIAM CUTHBERT BLACKETT Sacriston, Durham, England. 1920. HENRY STURGIS DRINKER Merion Station, Pa. 1933. KARL EIKERS NEW YORK, N. Y. 1922. FEDERICO GIOLITTI Torino, Italy. 1906. SIR ROBERT A. HADFIELD London, England. 1928. JOHN HAYS HAMMOND New York, N. Y. 1921. FRANK WILLIAM HARBORD London, England. 1917. HERBERT HOOVER Washington, D. C. 1905. HENRI LECHATELIER Paris, France. 1931. WALDEMAR LINDGREN Cambridge, Mass. 1921. C. McDERMID London, England. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1911. ROBERT H. RICHARDS Cambridge, Mass. 1934. T.A. RICKARD Victoria, B.C., Canada 1933. ALBERT SAUVER Cambridge, Mass.

Jan 1, 1934

By W. C. Elli, M. E. Fine

YOUNG'S modulus of elasticity in metals ordinarily decreases with rising temperature. The range of the thermoelastic coefficient at room tem- 1/E dE/dT perature (temperature coefficient of modulus, is illustrated1 by the values for tungsten and hard-drawn aluminum, —95 and —1220x10-6 eg C-1. However, a nearly zero thermoelastic coefficient is observed in some ferromagnetic alloys over a limited temperature range. In these alloys, as the temperature is raised, an increase in modulus arising from loss of ferromagnetism compensates the normal decrease. Iron-nickel alloys containing 36 to 52 pct Ni behave in this manner. In the present investiga- tion, the dependence of the modulus and thermo-elastic coefficient on cold working and annealing were studied in iron-nickel alloys in this range of nickel. Although these alloys, when fully annealed, have a coefficient near zero over a very small temperature interval, the temperature range of low coefficient can be extended greatly by straining and then stress-relief annealing. The modulus of face-centered cubic iron-nickel alloys annealed at 1000°C does not vary linearly with composition at room temperature but, as shown by the solid line of fig. 1, from Koster,' is minimum at 40 pct Ni and maximum at 87 pct Ni. The modulus increases with applied magnetic field but retains the minimum near 40 pct Ni. Schematic change of modulus with temperature for three compositions is shown in fig. 2.'. ' With increasing temperature, the slope becomes less negative, goes through zero (temperature of minimum modulus for the alloy), becomes positive, and resumes its normal negative value above the Curie

Jan 1, 1951

By F. E. Bedale

STUDY of several severe mine explosions that occurred during the winter of 1907 led to the belief that coal dust was a definite explosion hazard. The Consolidation Coal Co. was a pioneer in the early work to' eliminate this hazard and to combat the dangers incident to poor ventilation and the presence of methane. Maintenance of high humidity throughout the mines was one of the first measures adopted, later to be superseded by rock-dusting. In the twenty years from 1907 on, many safety measures were developed and adopted, and several prizes were won, though the practice was crude by present-day standards. But in 1927, the company went to work in earnest, and organized a Department of Safety with adequate personnel and with authority to enforce all approved rules for the prevention of accidents and the preservation of company property. All plans for new construction work, changes in mining systems, and proposals for the purchase of new mining equipment had to receive the approval of this Department. A set of operating- and safety standards was written to govern the activities of all employees, and physical examinations for them were required.

Jan 1, 1938

By F. C. Smyers, E. W. Merrick

ALTHOUGH the zinc and pyrite concentrates produced at Midvale go to other companies, the United States Smelting Refining and Mining Company smelts and refines its own lead. Refining is the first step of the process that is done at some distance from the mining operations, the plant being at East Chicago, Ind., an industrial center about 25 miles southeast of Chicago. For years it has been notable as being the only lead refinery in the country using the Betts electrolytic process. The original buildings, many of which are still in use, were erected in 1906 when the plant was known as the United States Metals Refining Co. In 1920 the parent company sold its copper refinery at Chrome, N. J., and since the copper refinery was also known as the U. S.

Jan 1, 1948

[Trans. No. Place Date Vol. Page 1. Wilkes-Barre, Pa.* May, '71.. 1 3 2. Bethlehem. Pa Aug., '71.. 1 10 8. Troy, N. Y Nov., '71.. 1 1S 4. Philadelphia, PaFeb., '72.. 117 5. New York, N. Y.*May: '78.. 120 5. Pittsburgh, PaOct., '72.. 125 7. Boston, MassFeb., '78.. 128 8. Philadelphia, Pa.* May, '78.. 2 3 9. Easton, POct., '78.. 27 10. New York. N. YFeb.. '74.. 2 11]

Jan 1, 1946

By A. J. Williams

THE province of Saskatchewan, situated in the center of the Great Plains region of Canada, has, like most prairie areas, an essentially agricultural economy. Most of its population of about 860,000 is located in the southern half of the province in the farming and ranching areas. To the north of the prairie is a broad forested belt supporting a considerable timbering industry, and the northern one third of the province is glaciated pre-Cambrian rock formation. This latter area is relatively barren of vegetation, but the presence within it of a considerable variety of radioactive, noble and base metals, and industrial minerals has been shown by prospecting in recent years.' Glacial Geology The Keewatin ice sheet, considered to have accumulated in the country to the west of Hudson Bay in Pleistocene time, covered at its maximum advancement almost all of Saskatchewan and extended south of the international boundary. Only in the Cypress Hills in the southwest and around Wood Mountain in the south central portion of the province did the preglacial formations escape the action for this glacial period. The bedrock of the plains and forest areas therefore is overlain by moraines and modified glacial drift, which vary in thickness from a few feet to 400 or 500 ft.' Glacial action in the pre-Cambrian area of the province was largely erosional, most of the more recent formations and some of the pre-Cambrian rock being transported out of the area to the south and west. It has been estimated that about 13 pct of this area is composed of lakes and rivers not too adaptable to rail or water transportation, so that until the use of aviation for exploration purposes became general, development of the area was slow. To the south, the heavy mantle of glacial drift has to some extent deterred the discovery of industrial minerals in the bedrock underlying the forest and prairie regions3 At the same time, this drift contains numerous deposits of those most elementary and necessary industrial minerals, sand and gravel. Sedimentary Basin The major feature of the sedimentary deposits underlying the plains regions is the basinal structure known as the Moose Jaw syncline, which runs from the southeast corner of the province in a northwesterly direction. To the west of this syncline the formations curve upward, then have been faulted and further upthrust to appear at the surface in the foothills of the Rockies in Alberta; to the east and north they curve upward into Manitoba and northern Saskatchewan, but the surface contacts are covered mostly with glacial drift.238 The axis of the syncline dips to the southeast, so that there is also an upward trend of the formations along the axis to the northwest. In illustration of the regional structure underlying the province, the pre-Cambrian basement has been logged in drillholes at the following depths in several locations: Ogema (south central), 9390 ft; Gronlid (northeast), 2599 ft; Vera (northwest), 4422 ft; Big River (north northwest), 2348 ft. Fig. 1 indicates the general surface geology of the province, ignoring such glacial overburden as may overlie many of the bedrock formations. Also indicated is the approximate location of the axis of the Moose Jaw syncline.' Industrial Minerals Clays: The province is fortunate in possessing a widespread distribution of clays of ceramic value, ranging from those used for heavy structural products to the high grade pottery and china clays. Shales suitable for brick and tile production are found in the Upper Cretaceous and Tertiary formations across the south of the province where the glacial drift is thin or nonexistent. Many deposits of glacial lake clays suitable for such wares are found scattered over the rest of the province south of the pre-Cambrian area. The Whitemud formation of the Upper Cretaceous is a narrow sedimentary band of secondary clays found intermittently at points across the south of the province where glacial action did not disturb or remove them.' In the southwest corner of the province, around Eastend in the Frenchman River valley, the refractory clays of this formation are contaminated somewhat with iron compounds or other alteration products of basaltic rocks. This eliminates the use of those clays in true whitewares, as they fire to creamy buff shades at the lower temperatures and to a blue-specked grey at cone 8 to 12, (2280°F to 2390°F), the range commonly used in firing whiteware. However, for use in the production of colored artware, caneware, stoneware or crockery, and sewerpipe, this type of clay makes an excellent body that requires little or no addition of flint, feldspar, or other fluxing materials such as are required in the higher class of ware.' It is not a grade of clay that can be shipped great distances to the manufacturing centers, but a market for considerable tonnages has developed at nearby Medicine Hat, where cheap natural gas is available for the firing of the ware. Farther east in the south central portion of the province, the clays of the Whitemud formation are generally more refractory and white burning. The formation is divided into three zones, consisting of white clays, brown shale, and white sandy clays.

Jan 1, 1953

By A. B. Parsons

AT the outset, the authors of this paper desire to file a disclaimer and an, explanation. They have no inside information from occult sources; neither of them feigns clairvoyant powers in the slightest degree. It is true that they have indicated on be graphs an approximate trend for the consumption of seven important mineral commodities up to the year 1954. At best this is a risky business; the figures do not pretend to be any- thing more than reasoned conjectures that are predicated on an attempt to evaluate some of the more obvious of the many factors that are likely to have a bearing on the future.

Jan 1, 1937

By E. D. Gardner

The Synthetic Liquid Fuels Act (58 Stat., 190; 30 U.S.C. Sup., Secs. 321- 325) was approved by Congress April 5, 1944; it directed the Bureau of Mines to build demonstration plants to produce synthetic liquid fuels from coal, oil shale, and agricultural products. The most important oil-shale de- posits in the United States are in the Green River formation of Colorado, Utah, and Wyoming. The oil shale of western Colorado generally is more amenable to exploitation, more persistent, and apparently richer than elsewhere in the Rocky Mountain Region. It occurs at the top of a high plateau surrounded by bold, nearly vertical escarpments 500 to 600 ft in height. The top 400 to 500 ft of these escarpments comprises an oil-shale measure that averages 15 gal of shale oil per ton; the bottom 70 to 100 ft of the measure, called the Mahogany Ledge, averages over 30 gal per ton. The full measure in a 1000-square-mile area is estimated to contain 300 billion barrels of shale oil;' the Mahogany Ledge is estimated to contain 100 billion barrels of oil. These estimates are based on numerous surface samples and on core-drill holes drilled by the Government and by private enterprise. The oil-shale beds are undisturbed and lie nearly horizontal. The name

Jan 1, 1949

By Michel Dupuy, Daniel Calais

The study of self-diffusion of plutonium in E phase has been carried out by the welded couples method. The tracer used was puZ4O which is detected by its X-ray emission (conversion lines of uranium which are computed between 13 and 21 kev). Intensities were measured with a scintillation counter. Each layer was removed in a direction parallel to the original interface with a grinding machine and a thickness measured with a pneumatic comparator. The concentration-penetration curves obtained were corrected for the effect of heating time from room temperature to annealing temperature and for the expansion due to phase transformations of plutonium. They were analyzed by the generalized Gruzin method. Self-diffusion of plutonium in E Phase is very fast cm per sec between 500" and 620°C) and the diffusion zones are 2 to 3 mm wide for annealing times ranging from 30 min up to 10 hr. The Arrhenius law gives the temperature dependence in the form: From the point of view of self-dqfusion, PUE phase falls into the anomalous bcc metals category (Tip , Hfp, Zrp, Uy) with a low-frequency factor and an activation energy lower than those provided by standard correlations. No theory proposed hitherto to explain these anomalies (influence of dislocations, of extrinsic vacancies bonded to inlpurities, of bi-vacancies) can clearly explain the self-diffusion coeffzcients of plutonium. DIFFUSION in bcc metals is a present-day problem. A recent symposium (Gatlinburg, 1964), followed by a book,' has been devoted to it. A great many experiments seem to show that diffusion in certain bcc metals obeys unexpected laws. The activation energies measured are sometimes strangely low (B hafnium, y uranium). For certain metals (0 zirconium, p titanium) the curves of log D (D = diffusion coefficient) as a function of 1/T (T = absolute temperature) are not linear. The frequency factors Do, which are of the order of 1 sq cm sec-' in fcc metals, vary from 1 to 10~6 sq cm sec-'. Various theories have been put forward to explain these anomalies; none is yet satisfactory. We wished to introduce a new experimental result by studying the self-diffusion in c plutonium. This allotropic phase, stable from 475°C up to the melting point (640°C), is in fact bcc. Unfortunately, nothing is known of the characteristics of the point defects in this phase, which limits the scope of the hypothesis which can be made about the mechanism(s) of self-diffusion in plutonium. 1) EXPERIMENTAL METHODS 1) Principle. We used the welded couple method. The two pellets of the couple initially have different 240 isotope contents (X emitter). After diffusion, the concentration/penetration curves are drawn up by the generalized Gruzin method. 2) Gamma Spectrography. The metal used in our study is plutonium, either low in puZ4O (isotopic content 1 pct) or high in puZ4O (8 pct). The latter also contains plutonium 241 (-1 pct) and 300 ppm of ameri-cium produced by the reaction Pu2U-AmM1 + 8-. The emission spectra of these two plutoniums placed in leak-tight vinyl bags have been studied by y spectrograph~. The detector is a thin crystal of thallium-doped sodium iodide. The activity of the plutonium rich in 240 is about twice that of the plutonium low in 240 in the energy band of 17 kev (L conversion lines of uranium); this band was used in these measurements. 3) Preparation and Examination of the Diffusion Couples. Diffusion couples were made from plutonium with a high and low PU"' content. Pellets (6 6 mm. thickness 3 mm) mounted on a polishing disc with ground parallel faces were polished mechanically on both sides. In this way, pellets with two parallel faces were easily obtained. The polished pellets were joined by a 6 phase anneal (420°C, 1 hr) in a small screw press (pressure of 20 kg per sq mm cold); a centering ring enabled the two pellets to be pressed coaxially. The couples then were subjected to the diffusion treatment by annealing in the E phase in sealed silica ampules in argon at atmospheric pressure. The annealing temperatures and times are given in Table I. The couples were encased in a mild steel ring, the joint interface being thus parallel to the ground face of the ring. The diffusion couple/ring assembly underwent successive abrasions by means of a magnetic plate grinder. The thickness of the abraded layer was measured with a Solex pneumatic comparator when it was less than 0.1 mm (accuracy 0.2 p) or with a mechanical micrometer (accuracy 3 p) for passes of the order of 0.2 mm. All these operations were done in glove boxes, as plutonium is particularly toxic. After each abrasion we determined the emission spectrum of the ground face. The emissive surface is defined by means of a diaphragm 3 mm in diam. We noted more particularly the X activity in the 17-kev

Jan 1, 1969