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By Henry Howe

(New York Meeting, February, 1913.) THE transformation which steel undergoes in glow cooling, from the condition of austenite when above the transformation range into that of pearlite plus either ferrite or cementite below that range, is subject to great lag. This transformation is essentially the pearlitizing of the austenite. Indeed the hardening of steel is due to this lag, which is made so great by extremely rapid cooling that a very large part of the transformation itself is restrained, so that the rapid cooling catches the metal in an only partly transformed state, that of martensite, and under favorable conditions even in an almost wholly untransformed state, as in the cases of Maurer's austenitic manganese steel. Hadfield's austenitic manganese steel, 25 per cent. nickel steel, and other austenitic alloy steels, are austenitic even after slow cooling. It has long been known that this- lag increases (1) with the rapidity of cooling, (2) with the presence of certain retarding elements, notably manganese and nickel, and (3) with the temperature from which cooling starts. The present inquiry touches the last. of these influences, but incidentally it throws light on the first also. This influence of higher heating in increasing lag manifests itself in different ways which, though they may at first seem unrelated, are in fact but different, aspects of one and the same thing. Thus, among heatings to different high temperatures, all of them above the transformation range, the higher the temperature to which the steel is heated (1) the lower is the temperature it which the transformation occurs in cooling slowly down, (2) the shorter is the time occupied in the actual cooling from above the transformation range to the room temperature under given external conditions, whether of slow or

Jan 3, 1913

By O. H. Eschholz

THE electrostatic process of fume precipitation is an excellent example of the successful application of scientific knowledge to an industrial operation. Originally proposed for the precipitation of sulphuric acid mists, it has been extended until at present there is practically no fume carrying gas to which the method cannot be applied. Among the more common applications are: the recovery of non-ferrous smelter flue-dust, iron blast-furnace dust, cement dust, and potash fume. It should be borne in mind that the process is restricted to the precipitation of suspended particles, either liquid or solid, and does not separate gaseous constituents. However, -by proper temperature control, mixtures of vapors having different temperatures of condensation to either solids or liquids may he selectively precipitated. The process consists essentially of subjecting suspended particles, including those too minute to be effectively acted upon by centrifugal or gravitational forces, to such an electrical force that they are driven from the gas stream, acting as a conveyer, and deposited upon a suitable receiving surface. This directional impulse is obtained front the interaction of charged particles and an electrostatic field of definite intensity gradient existing between two dissimilar electrodes, known as discharge and receiving electrodes. In principle, the equipment is equally simple. As shown diagrammatically in Fig. 1, it consists of: (1) A source of high-potential direct current, requiring: (a.) Source of alternating-current energy. (b) Means of transforming from tow voltage to high voltage. (c) Means of converting alternating to direct current. (2) Precipitation chamber having: (a) Transmission tubes for fume-laden gases. (b) Suitably designed and disposed electrodes. (c) Means for affecting removal of deposited solids.

Jan 8, 1918

By J. C. Bokros

At temperatures above 950°F, zirconium which has been strained a critical amount will experience critical recrystalli-zation. The large grain size thus formed can result in a reduction in the fatigue life by a factor of 2 to a factor of 9 at both high and low temperatures. The critical strains for zirconium vary from 15 pct at 900°F to about 2 pct at 1125°F, while those for zircaloy III vary from 15 pct at 1050°F to 5 pct at 1200°F. Zircaloy II ,experiences no critical recrystallization up to 1200°F. ZIRCONIUM has become increasingly important for nuclear applications and is being employed in reactors at temperatures where recrystallization can occur. Recent work' on the fatigue properties of zirconium has shown that coarse-grained structures developed in zirconium during recrystallization have much lower fatigue lives than fine-grained material. The development of these large grain sizes under such conditions is well known to be the result of critical recrystallization.2-4 Briefly, critical recrystallization occurs when a metal is strained a critical amount and annealed in the recrystallization range. The critical strain is defined as that minimum strain necessary to promote nucleation in the time unit and temperature considered. The maximum grain size occurs at the critical strain, since at this strain the fewest stable nuclei per unit volume grow into new grains. Recrystallization is not evident below this; strain since the nucleation rate is vanishingly lolw, and metal strained more than the critical amount has a higher nucleation rate per unit volume which results in a finer grained structure. This paper describes the critical recrystallization observed in reactor-grade zirconium, zircaloy 11, and zircaloy I11 as a function of annealing temperature and temperature of strain. EXPERIMENTAL The zirconium used was hafnium-free, double arc-melted sponge obtained from the Bureau of Mines. The ingots were forged and hot reduced to 0.08 to 0.10-in. sheet and subsequently cold reduced to 0.035-in. sheet with intermediate and final anneals at 1200 OF for 15 min. The zircaloy II and zircaloy III used were 0.035-in. sheets in the annealed condition. Compositions of these materials as tested are given in Table I. To determine the critical strain at a given temperature, tensile specimens having a0.065-in. taper in a 2-in. gage length were machined from the sheets parallel to the rolling direction. The specimens were polished, etched, and examined metallographically to ensure that all of them were strain-free, initially. Tukon indentations were made every half millimeter along the gage length of each specimen. These served as fiducial marks enabling the plastic strain to be measured with a microscope and micrometer stage. The specimens were pulled to failure at a rate of 0.002 in. per min in an Instron tensile-testing machine. Three temperatures were used for straining: room temperature, 500 ºF, and 900 ºF. The 500º and 900 ºF tests were run in an argon atmosphere. Since the rate of work hardening changes with temperature, a different critical strain was obtained for each temperature of strain. Specimens, prepared in the manner described, were annealed in vacuunl at various temperatures ranging from 900" to 1200 F for up to 1000 hr, after which they were examined metallographically. The critical strain and the recrystallized grain size as a function of strain were determined for each specimen. Results for the same temperature and time indicated that the critical strain measured was reproducible to within 5 pct of each other. RESULTS AND DISCUSSION Since increasing the time of anneal increases the probability of the nucleation of a new grain, the critical strain decreases with time at a decreasing

Jan 1, 1961

GEORGE F. KUNZ, New York, N. Y. (written discussion*).-We have been informed that the nickeliferous ores of Sudbury could furnish more palladium than the whole of the present world supply, together with a large amount of platinum. As the quantity of ore melted in Sudbury in 1916 totaled 1,521,689 tons, giving 80,010 tons of matte, and as the average of 3 years, up to 1915, are stated to show an average of 0.10 oz. of platinum and 0.15 oz. of palladium per ton of matte, this would indicate the presence of 12,000 oz. of palladium and 8000 oz. of platinum in the ore mined in 1916.1 Interest in the platinum situation is now more intense than it has ever been, and the great importance of this metal for many special uses is being increasingly appreciated. For munition manufacture, for chemical apparatus, in dentistry, and for jewelry, it has been and continues to be in great demand in spite of the phenomenal rise in its value. It is true that this has necessarily led to a search for substitutes, especially for dentistry and chemical uses, but while some of these have been found to answer the needs fairly well, for many 'other purposes platinum is still employed in spite of its great cost. As to the jewelry industry, the most public-spirited efforts have been made to restrict its use, and its employment in the manufacture of watchcases, purses, bracelets, and catches has been abandoned, gold being used in its place. The prime cause of the present shortage is, of course, the elimination of 'the Russian supply which, in normal times, constituted probably more than 90 per cent. of the world's production. This makes an intensive

Jan 4, 1918

By Arne Bergholm

Australian rutile was chlorinated in the presence of CO or carbon. The chlorination velocity in CO was found to be strongly influenced by temperature and proportional to the CO concentration, but independent of the Cl, concentration. In the presence of carbon, the reaction velocity is much higher. The reactivity of the carbon and the distance between the carbon and the rutile surfaces are important variables. The reaction velocity is approximately proportional to the Cl, concentration and independent of the CO concentration of the surrounding atmosphere. Experiments with fluidized-bed chlorination of carbon-rutile mixtures indicate that the motion of the bed has little influence on the reaction velocity. At low temperatures, the chlorination velocity of dense tablets is much greater than that of TiO, coke mixtures suitable for fluidization. The reaction mechanism is discussed. In the industrial production of TiCl, rutile is chlorinated in the presence of carbon. Disregarding intermediate steps, the reaction may be expressed by the following equations: The ultimate object of this study was to find out whether the reaction velocity was higher in fluidized bed operation compared with chlorination of pelle-tized carbon-rutile mixtures. From a literature survey and preliminary experiments it was learned that some basic knowledge about the reaction mechanism was needed for a good experimental design. Therefore the following sets of experiments were carried out: 1) Studies on the reaction velocity in the chlorination of rutile with CO as the only reducing agent. 2) Chlorination of separate rutile-carbon tablets. 3) Chlorination of rutile-carbon tablets at different temperatures with various kinds of carbon, various grain sizes, and various tablet-making techniques. This series of experiments was carried out not only with pure chlorine but also with mixtures of chlorine with argon, CO and CO,. 4) Chlorination of rutile-carbon tablets made in a strictly standardized manner. 5) Chlorination of static-bed rutile-carbon mixtures. 6) Fluidized-bed chlorination of the same mixture. The experiments 4 to 6 formed the final and direct test of the main question: Static bed vs fluidized bedo. Although there are many patents and papers dealing with the general aspects of chlorination, only few experiments from which detailed information can be obtained have been reported in the literature. Pamfilov and coworkersl3 have studied chlorination of TiO, with CO or carbon as the reducing agent. They found that the weight decrease per hour at 600o to 800°C amounted to 11 to 14 pct with CO and 45 to 51 pct with carbon. They suggest that phosgene might be an intermediate in the chlorination of TiO,. Takimoto and Hattori have chlorinated reduced titanium oxide (TiO) and found a very high rate of TiC1, -production. They proved that the composition of the gas from the chlorination of rutile-carbon mixtures contained mainly CO. They reported for instance 74.7 pct CO, and 5.6 pct CO at 800°C at which temperature the Boudouard equilibrium composition is 12 pct CO and 88 pct CO. Seligman and Segerchano6 have studied the chlorination of TiO. They proved that Ti0 and chlorine react rather rapidly at temperatures as low as 300°C. Above 400°C, the reaction was complete. At 500°C the velocity of this reaction was much higher than was chlorination of TiO, + C. McTaggart,7 Nishimura, et al. and Wilskam have chlorinated mixtures of carbon and various kinds of rutile or beneficated ilmenite. Nishimura, et al. also report the results from reduction of TiO, with H2, CO, or carbon. At 900°C only 1 pct Ti O is formed in 2 hrs. At 1100°C 23.1 pct Ti, 0, was formed if elementary carbon was present. No carbide formation occurred below 1400°C. McIntosh and Cofferll have observed that the CO, content of the exit gases from chlorination of rutile and calcined petroleum coke is appreciably higher than found in the Boudouard equilibrium. At 900°C the ratio (CO, /CO + CO) is about 80 pct, whereas the equilibrium value is about 2 pct. W. E. Dunn12 has studied the chlorination rates of several TiO,-bearing minerals with CO + Cl, or COCl . Chlorinations were carried out either in a fluidized reactor or a fixed-bed reactor, both having a 30-mm diameter. The results obtained in both reactors were comparable. It was proved that benefi-ciated ilmenite (i.e., ilmenite from which the iron oxide had been removed by chlorination) was chlorinated 10 times faster thanrutile. Sore1 slag showed an intermediate rate. When phosgene is used, the

Jan 1, 1962

By J. B. Clemmer

PRODUCTION of magnesium metal in the United States during the past decade has increased from less than 600,000 lb. in 1928 to more than 4,800,000 lb. in 1938.1 The growing industry has stimulated interest in methods of production and in sources of raw material. All of the present domestic production is from brines. However, the availability of large tonnages of magnesite in the state of Washington, together with the possibility of cheap power, have created interest in the utilization of magnesite for the production of magnesium metal as well as for other purposes. Magnesite, the carbonate of magnesium (MgC03), usually is associated with lime-stone (CaCO3) and dolomite (MgC03 CaCO3). It occurs in crystalline and microcrystalline (sometimes termed amor-phous) forms.2 The more common crystal-line mineral is found in various shades of white, gray, yellow and brown, the colors being due to impurities, chiefly iron. Magnesite has a hardness of 3.5 to 4.5 and a specific gravity of 3.0 to 3.1. It forms rhombohedral crystals in the hexagonal system, having a vitreous, pearly luster. The quarries and mines of the Northwest Magnesite Co. near Chewelah, Wash., are large producers of magnesite for refractories.

Jan 1, 1940

US 4,190,434 - In the thermal production of magnesium metal, a mixture of calcined dolomite, an iron- silicon-aluminum alloy as a reductant, and residual slag from the production of ferrochromium is smelted to evolve magnesium vapor, which is then condensed. The use of bauxite is lessened or eliminated because of the relatively high alumina content of the residual slag. R. Bonfils, A. Mena, C. Payn, and L. Septier, assigned to Ste. Francaise d’Electrometallurgie (SOFREM). Feb. 26, 1980. 6 pp. (75-10R). Filed: 6-14-78 (915,387). Priority: France, 6-24-77 (77/20,227).

Jan 1, 1982

By J. C. Miller

In offshore oil drilling as it is done today, accidental blowouts cause considerable damage lo the environment. Public alarm over such accidents has already resulted in a number of legislative proposals which appear to favor the cessation of all drilling on the Federally owned continental shelf. Present concern for the environment and the increasing water depths associated with offshore drilling suggest the desirability of applying underground mining technology to offshore petroleum exploration. If offshore drilling were to proceed from underground accesses to the continental shelf, accidental damage to surface waters would be avoided, and so would the difficulties of exploring in deep or ice-filled waters. The specific approach proposed here is intended as a preliminary to offshore oil exploration in a known field or geologic structure. The end result of this method would be an on-shore vertical or inclined shaft terminating in an operating tunnel or haulageway as shown in the illustrations. From the haulageway, branching access tunnels would lead to drilling compartments. With this arrangement, it appears likely that one operating tunnel could serve all lessees ill a particular unit operation. Although an inclined shaft is not illustrated, this would probably be more practical than a vertical shaft owing to the length of the casings and the character of other equipment used in oil producing operations.

Jan 1, 1971

By James M. Hodge

The Cumberland Gap extension of the Louisville and Nashville railroad, recently completed from Cumberland Gap to Norton, 71 miles, connects at the latter point with the Norfolk and Western, making a direct through line from Louisville to Norfolk. The whole of this connecting link skirts the southern boundary of the southwest Virginia coal region, but for the first 57 miles of its course it is separated from the coal by a mountain range (Cumberland mountain and its extension, Stone mountain), which bars entrance to the field from that direction, excepting at Pennington Gap, where access may he had to a small area only, which has not yet developed any very satisfactory coal. The railroad passes through the range at Big Stone Gap, and for the last 14 miles of its course to Norton is in direct contact with that part of the coal region known as the Big Stone Gap coal-field. By this road a western and southwestern outlet from the field is secured; the Clinch valley extension of the Norfolk and Western railroad gives exit eastward from Norton, and the South Atlantic and Ohio railroad, built through Big Stone Gap simultaneously with the L. & N. R. R., delivers the coal to points south and southeast. Besides these lines already built, an early connection with the East Tennessee, Virginia and Georgia railroad, via its Rogersville branch, is probable, and connections with the railroads of eastern Kentucky are projected. The Charleston, Cincinnati and Chicago railroad has already done some grading on one of the latter, but the rugged country intervening will prevent its construction till the demand for it becomes urgent. The coal-field embraces in Virginia about 120 square miles, to which should be added some 30 square miles in Kentucky, also tributary to Big Stone Gap, the whole of it underlaid by coal, probably of workable thickness, and much of it by two or more such beds. The determination of the boundaries of the field, however (except on the south, where Stone mountain forms a natural limit beyond which only a small, isolated tract of coal is found), is involved in much

Jan 1, 1893

By Charles Schwab

WHEN I leave this life, as an employer of labor there is no one thing that I want so much to be engraven upon my monument as the fact that I have been one of the men who have worked, whether with my brains or my hands, for the advance-ment of industry in the United States, and to be regarded, as I should like to be regarded by labor with love and kindly remembrance for our years of association. In my relationship with my employees, I have always contended that every man should be paid for what he does. I will not employ or be associated with any kind of labor of which the organization insists that a man shall receive a fixed sum of money for his day's wages, however poor or good his day's labor may be. What applies to the common laborer applies equally well to the management, the brains of an industrial establishment. I have always thought of industry as a three-legged stool, with capital, management and labor as the legs. All three legs of that stool must be there before that stool can stand up. If you take any one of those legs away, it is going to topple over. The. three must stand together for successful business accomplishment. I believe that a man who has his labor to sell, to put it plainly, has just as good a right to bargain for the best price for that labor as those who employ him. It is a perfect right for him to do so. If the government of our United States is right, our method of handling labor in our Bethlehem plants is right because it is representative and democratic. We have our labor elect delegates; elect representa-tives from their own ranks, who shall meet frequently. That constitutes, as. it were, the House of our great Congress in Washington, the industrial house. We have our management, who represent the Senate, who meet independently. Working men have learned to express their views freely as to whether they are treated fairly and whether conditions are right or wrong.

Jan 12, 1922

By H. E. Gross

A plausrsle method of drilling beyond the continental shelves is set forth with limitations of the method. The continental shelves comprise the water-covered portions of land masses out to 600 ft. of water, or roo fathoms. The problems and possibilities of drilling beyond this depth are discussed in this paper. Introduction Much attention is being given the problem of developing petroleum beneath the open sea. Geophysical surveys have been made 26 miles offshore1 from the continental United States, and onco offshore ownership is established it is likely that there will be drilling for oil on the continental shelves. More than two years ago the author presented the means for drilling in deep water.2 at the fall meeting of the Petroleum Division of the AIME at Los Angeles. His concepts then were based on the use of rigid foundations suitable for drilling in water up to 600 ft. deep. The present paper suggests a method for drilling in deeper water. Possibilities and Problems of Drilling beyond the continental shelves It being conceded that because restricted deep-water portions of the hydrosphere might contain oil in commercial quantities, and that at any rate it is pertinent to know more of the nature of the lithosphere beneath the hydrosphere, the possibilities and problems of drilling beyond the continental shelves should be set forth. Drilling in open water would offer few if any advantages over drilling on land. These are: 1. The ocean transportation is available to deep-water drilling sites, and extensive pipe lines and roads are unnecessary. 2. Refinery facilities and markets perhaps are established on the near-by shore where adjacent fields on land are nearing depletion. 3. There is freedom from jungle pests and tropical diseases. 4. Competitive drilling is less likely. 5. Extensive areas attractive for development arc not yet under lease or concession. Disadvantages are great and numerous: 1. Storm hazards from wind and wave. 2. Expensive foundations, either rigid or floating. 3. Shutdown times because of weather. 4. Marine Regulations of Federal Bureaus in addition to customary regulations on land. 5. Frequent difficulty in moving men and materials to and from drilling platforms. 6. Extra precautions required in open sea. For drilling in water more than 500 or 600 ft. deep, rigid foundations2 become too costly, and floating foundations must be used, and they must meet the following requirements:

Jan 1, 1947

By H. E. Gross

A plausrsle method of drilling beyond the continental shelves is set forth with limitations of the method. The continental shelves comprise the water-covered portions of land masses out to 600 ft. of water, or roo fathoms. The problems and possibilities of drilling beyond this depth are discussed in this paper. Introduction Much attention is being given the problem of developing petroleum beneath the open sea. Geophysical surveys have been made 26 miles offshore1 from the continental United States, and onco offshore ownership is established it is likely that there will be drilling for oil on the continental shelves. More than two years ago the author presented the means for drilling in deep water.2 at the fall meeting of the Petroleum Division of the AIME at Los Angeles. His concepts then were based on the use of rigid foundations suitable for drilling in water up to 600 ft. deep. The present paper suggests a method for drilling in deeper water. Possibilities and Problems of Drilling beyond the continental shelves It being conceded that because restricted deep-water portions of the hydrosphere might contain oil in commercial quantities, and that at any rate it is pertinent to know more of the nature of the lithosphere beneath the hydrosphere, the possibilities and problems of drilling beyond the continental shelves should be set forth. Drilling in open water would offer few if any advantages over drilling on land. These are: 1. The ocean transportation is available to deep-water drilling sites, and extensive pipe lines and roads are unnecessary. 2. Refinery facilities and markets perhaps are established on the near-by shore where adjacent fields on land are nearing depletion. 3. There is freedom from jungle pests and tropical diseases. 4. Competitive drilling is less likely. 5. Extensive areas attractive for development arc not yet under lease or concession. Disadvantages are great and numerous: 1. Storm hazards from wind and wave. 2. Expensive foundations, either rigid or floating. 3. Shutdown times because of weather. 4. Marine Regulations of Federal Bureaus in addition to customary regulations on land. 5. Frequent difficulty in moving men and materials to and from drilling platforms. 6. Extra precautions required in open sea. For drilling in water more than 500 or 600 ft. deep, rigid foundations2 become too costly, and floating foundations must be used, and they must meet the following requirements:

Jan 1, 1947

THERE is probably no phase of basic open-hearth steelmaking that is more of an art and less of a science than mold and pouring practice. It varies widely from plant to plant; consequently it is obviously impossible to set down in detail in this chapter the many ramifications of practice that are now used. The discussion that follows therefore attempts only to give an outline of the more common methods, with examples sufficient to indicate some of the variations in procedure, and to emphasize a few of the many underlying problems that face the open-hearth operator at the pouring platform. MOLD DESIGN Ingot molds are hollow castings of considerable wall thickness. Despite this, non-uniformity in wall thickness should be strictly avoided to prevent the setting up of unnecessary stresses. Molds are cast in various forms, sizes, and shapes depending on the type of steel, and on whether the ingot is to be withdrawn from the mold or the mold from the ingot. The selection of ingot-mold material, which is usually cupola or blast-furnace iron containing approximately 3.5 per cent carbon, 1 per cent silicon, 0.9 per cent manganese, 0.2 per cent phosphorus, and 0.07 per cent sulphur, is governed by numerous considerations that affect mold life. (1) Factors in addition to wall thickness that should be given primary consideration at the foundry are casting skin, shrinkage stresses, and casting temperature. Factors in Mold Design. In use, mold thickness is of greatest importance, for it must be heavy enough to freeze the molten metal rising in the mold and to reduce the temperature of the steel below that of the melting point of cast iron to prevent the inner surface of the mold from melting, which would result in the welding of the ingot to the mold. The skin of an ingot, which solidities immediately upon contact with the relatively cold walls of the mold, must soon become thick enough to contract on the fluid mass and pull away slightly from the sides of the mold. The separation of the ingot from the mold depends entirely on the heat taken up by the mold from the steel.

Jan 1, 1944

By W. K. Lewis, Lombard Squires, W. I. Thompson

The authors presented an article2† last year on colloidal properties of clay suspensions in which they attempted to sustain the position that the behavior of clay suspensions is due primarily to the mechanical interference of the platy particles, the nature and extent of the interference being profoundly influenced by the character of the surfaces of the particles, which in turn is determined primarily by the nature and amount of adsorbed foreign materials held on the surface of the particles by forces which are predominantly chemical in type. The following discussion is a continuation of that article to extend these same interpretative points of view to the behavior of clay gels. Insight into the mechanism of gelation is certainly of outstanding importance in the handling of drilling muds. In the former article it was suggested that the thin, flat plates that constitute the ultimate clay particles may build up aggregates by the overlapping of the ultimate plates face to face much longer and perhaps also much wider than the ultimate plates themselves, but not appreciably thicker. Exhaustive microscopic examinations of characteristic clays show no tendency for the larger particles, clearly visible under the microscope, to orient themselves in this way. It is true that the gelation of the clays is due primarily to the smallest particles, unresolvable other than by the ultramicroscope, so that the possibility of the deve1opment by them of an overlapping structure is not excluded. Furthermore, as one approaches the limit of resolving power of the microscope, the difficulty of observing accurately the shapes and relative positions of particles incresses excessively. However, in the absence of any observable tendency toward overlapping orientation of the large, visible particles, one hesitates to ascribe such a tendency to the smaller particles beyond the range of visibility. Should it develop that one must exclude the assumption of overlapping orientation, the explanations offered in the previous article are changed in only one respect; namely, one would now have to assume that the ultimate particles themselves have length, and probably also width, very large in comparison with their thickness.

Jan 1, 1936

By Lombard Squires, W. K. Lewis, W. I. Thompson

The authors presented an article2† last year on colloidal properties of clay suspensions in which they attempted to sustain the position that the behavior of clay suspensions is due primarily to the mechanical interference of the platy particles, the nature and extent of the interference being profoundly influenced by the character of the surfaces of the particles, which in turn is determined primarily by the nature and amount of adsorbed foreign materials held on the surface of the particles by forces which are predominantly chemical in type. The following discussion is a continuation of that article to extend these same interpretative points of view to the behavior of clay gels. Insight into the mechanism of gelation is certainly of outstanding importance in the handling of drilling muds. In the former article it was suggested that the thin, flat plates that constitute the ultimate clay particles may build up aggregates by the overlapping of the ultimate plates face to face much longer and perhaps also much wider than the ultimate plates themselves, but not appreciably thicker. Exhaustive microscopic examinations of characteristic clays show no tendency for the larger particles, clearly visible under the microscope, to orient themselves in this way. It is true that the gelation of the clays is due primarily to the smallest particles, unresolvable other than by the ultramicroscope, so that the possibility of the deve1opment by them of an overlapping structure is not excluded. Furthermore, as one approaches the limit of resolving power of the microscope, the difficulty of observing accurately the shapes and relative positions of particles incresses excessively. However, in the absence of any observable tendency toward overlapping orientation of the large, visible particles, one hesitates to ascribe such a tendency to the smaller particles beyond the range of visibility. Should it develop that one must exclude the assumption of overlapping orientation, the explanations offered in the previous article are changed in only one respect; namely, one would now have to assume that the ultimate particles themselves have length, and probably also width, very large in comparison with their thickness.

Jan 1, 1936

G. B. WATERHOUSE,* Buffalo, N. -Y. (written discussion?).-One of the most essential features of rail manufacture is the production of rails that will give good service and be free from failures. To this end rails are made to careful specifications and their manufacture is controlled by rigid inspection on the part of both the producing mill and the railroad or its representative, such as the Hunt special inspection referred to in the paper. Captain Hunt refers to the crescent-shape base failures and describes them as ruptures in the rail flanges extending from the outside inward toward the web. This is hardly correct and may be misleading. It has been shown, over and over again, that the base breaks originating in seams invariably start at the center of the rail base; and run longitudi-nally in varying lengths from 3 to 12 in. and sometimes longer. Most of them are from 5 to 8 in. long and then curve outward to the edge of the flange. The split at the center of the base may exist for an indefinite time and not be discovered until the break shows on top of the flange or the piece of flange breaks off. The. stresses that cause the break are explained in two ways: (1) by the eccentric bearing of the rail base, that is taking contact at one side or edge and bringing excessive strain at the center of the base which starts fracture in any seam that may he present at that point; (2) the split may be due to cross strain in the base where this member is thrown into. compression, as happens where a pair of trucks are on opposite sides of the cross tie or rail-base hearing, and the head is put in tension. A careful study of "split base breaks" shows that fully 95 per cent. occur on the tie bearing, which is further evidence that the above de-scribed causes for the initial break are probably correct. These split base breaks are almost invariably progressive, but always start at the center of the rail-base running longitudinally.

Jan 12, 1919

By David L. Pentz

This paper discusses exploration objectives and requirements for a nuclear repository in the U.S.A. The importance of designing the exploration program to meet the system performance objectives is emphasized and some examples of the extent of exploration required before the License Application for Construction Authorization is granted are also discussed.

Jan 1, 1984

By E. Tulcanaza

The practical significance of the in situ grade variability is usually neglected. Although recognized, often times it is either ignored or just considered as a vague guideline in many of the decisions dealing with exploration, reserve estimation, and mine planning. This paper stresses the significance of grade variability for exploration and mining, and illustrates its liaison to the structural features of the ore deposits, as well as to the mining parameters used for mine extraction. Some geostatistical results obtained from a silver mine, tungsten mine, and copper mine in South America are discussed.

Jan 1, 1985

By T. B. Counselman, T. B.

Continuous countercurrent decantation calculations have always been a headache to the cyanide man (and the chemical engineer) because of the simultaneous equations involved. These are tedious to solve, and there is considerable opportunity for mathematical error. This paper presents a shortcut method for making these calculations, which has been in successful use for twenty years by the author, and which is particularly valuable in selecting the best of several possible flowsheets, or evaluating the effect of various assumptions.

Jan 1, 1950

Discussion of the paper of Godfrey T. Vivian, presented at the Cleveland meeting, October, 1912, and published in Bulletin No. 76, October, 1912, pp. 1103 to 1109. COURTENAY DEKALB, Tucson, Ariz. (communication to the Secretary*) :--Mr. Vivian's paper is interesting as an evidence of renewed attempts to solve the problem of adapting the centrifugal machine to the uses of the metallurgist. It would not seem that the Gee machine has solved the problem, because it is manifestly of use only with quite high-grade material, since low-grade pulp could not stand the cost of treatment by a discontinuous process. The mechanism, however, would seen to accomplish grading more perfectly than the ordinary centrifugal basket. This is an entirely different thing from concentration, which is intended to yield a finished marketable product. The real problem is to design a successful continuous centrifugal machine. Ten years or snore ago a machine, which might be described as having an inverted step-basket, offered much promise, and was constructed and tested at considerable cost, but it presented insuperable difficulties. The construction of a successful continuous centrifugal would be welcomed by the whole industrial world, since its uses would be most extensive. Mr. Vivian suggests the utilization of the centrifugal machine as a substitute for slime filters in the cyanide process, but he, has apparently not tried the experiment. I tested the efficiency of centrifugal machines for this purpose in 1897-8, having to extract the cyanide solution from a highly argillaceous slime of the sticky kind which the Mexican call ?lama." Our filter-presses yielded cakes containing usually :30 per cent. of moisture, and so dense as to preclude washing. The centrifugal machine readily Brought the moisture content down to 9 per cent. and permitted fairly successful washing. Despite these advantages, the cost of power, labor, and repairs, and the loss of time in discharging the cake, exceeded the costs and

Jan 5, 1913