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By Edward Pesout

The McGill smelter started operations in the year 1907. The smelter furnaces were fired with run-of-mine coal on grates until April 1911, when oil firing was introduced. Oil firing continued until April 1918, when the initial coal-pulverizing plant was started.' Early Pulverizing Plant Various alterations were made to that plant during its operation, one of the more important being in connection with the system for delivering pulverized coal. In order to minimize coal-dust explosions and fires, the return portion of the main delivery line was eliminated in the year 1928. Thereafter coal-dust explosions and fires were greatly reduced. Pulverized coal was prepared at this plant primarily for the reverberatory furnaces, but for several years it was also delivered to the converting plant, roasters and power-plant boilers by a system of auxiliary fans and delivery lines. During the period March 29 to April 8, 1929, one reverberatory furnace was fired with pulverized coal produced by an Aero, type J, unit coal pulverizer with a rated capacity of 5 tons per hour. This machine actually pulverized its rated capacity but the product was too coarse. After certain regulations, a her product was obtained but the pulverizer capacity decreased and this resulted in insufficient coal for efficient furnace operation. Table I gives a comparison of the average screen analyses of the pulverized-coal products from the impact-type unit pulverizer and the regular coal-plant installation. It was definitely proved that this size and type of unit pulverizer could not furnish sufficient coal of proper fineness to give smelting results comparable to that obtained with the regular coal-pulverizing plant. The coal from this unit pulverizer was so coarse that it did not ignite or burn properly and thus did not produce the proper heat for efficient smelting. During the latter part of 1929 and the early part of 1930, experimental work was conducted with a 7-ft. o-in. by 48-in. Hardinge conical ball-mill coal-grinding unit, which was installed alongside a furnace in the reverberatory building. Results obtained from the test run indicated that this unit would furnish sufficient coal of proper fineness for good smelting.

Jan 1, 1947

By Edward Pesout

The McGill smelter started operations in the year 1907. The smelter furnaces were fired with run-of-mine coal on grates until April 1911, when oil firing was introduced. Oil firing continued until April 1918, when the initial coal-pulverizing plant was started.' Early Pulverizing Plant Various alterations were made to that plant during its operation, one of the more important being in connection with the system for delivering pulverized coal. In order to minimize coal-dust explosions and fires, the return portion of the main delivery line was eliminated in the year 1928. Thereafter coal-dust explosions and fires were greatly reduced. Pulverized coal was prepared at this plant primarily for the reverberatory furnaces, but for several years it was also delivered to the converting plant, roasters and power-plant boilers by a system of auxiliary fans and delivery lines. During the period March 29 to April 8, 1929, one reverberatory furnace was fired with pulverized coal produced by an Aero, type J, unit coal pulverizer with a rated capacity of 5 tons per hour. This machine actually pulverized its rated capacity but the product was too coarse. After certain regulations, a her product was obtained but the pulverizer capacity decreased and this resulted in insufficient coal for efficient furnace operation. Table I gives a comparison of the average screen analyses of the pulverized-coal products from the impact-type unit pulverizer and the regular coal-plant installation. It was definitely proved that this size and type of unit pulverizer could not furnish sufficient coal of proper fineness to give smelting results comparable to that obtained with the regular coal-pulverizing plant. The coal from this unit pulverizer was so coarse that it did not ignite or burn properly and thus did not produce the proper heat for efficient smelting. During the latter part of 1929 and the early part of 1930, experimental work was conducted with a 7-ft. o-in. by 48-in. Hardinge conical ball-mill coal-grinding unit, which was installed alongside a furnace in the reverberatory building. Results obtained from the test run indicated that this unit would furnish sufficient coal of proper fineness for good smelting.

Jan 1, 1947

By B. L. Cusack, N. W. Stump

Selected technological developments applicable to lead and zinc mineral processing and changes in Australian concentration practices made since 1770 are reviewed. Laboratory and pilot plant studies of two new ores have been conducted since 1770. These have resulted in final flowsheet proposals which are described. New production capacity since IT0 has been based on plant expansion or the retreatment of oxidised tailings from plants operating pre-1940ts. Major developments in existing plants have come from the application of computer control to crushing, grinding and flotation and the installation of on-stream analysis systems. Flowsheet configurations have been altered in a number of plants. Selected research topics applicable to lead and zinc processing are also reviewed.

Jan 1, 1977

New Members The following list comprises the names of those persons who became members during the period June 10, 1916, to July 10, 1916: ADAMS, WILLIAM S., Filtration Engr., Anaconda Copper Min. Co., 701 Cherry, Anaconda, Mont. ALLEY, JAMES E., Shift-boss.. .......... Belmont Milling Co., Tonopah, Nev. BADGLEY, CHARLES WELLING, Research Chemist, El Paso Smelting Works, El Paso. Tex. BALLENBERG, ADOLB G., Engr., porcupine Exploration Co., Ontonagon Co., Mich. BARKER, RALPH FEINER, Met.. ................ Garfield Smelt. Co., Garfield, Utah. BLOSSOM, EDWARD LUDLAM, Staff of Research Corpn., 63 Wall St., New York, N. Y. BROUGHTON, EUGENE HARDING, Experimental Engr., Copper Queen Cons. Min. Co., . - -. -- - Bisbee, Ariz. BURFORD, SAMUEL W., Genl. Mgr., Cleveland Mining Co., 223 West Third St., Joplin, Mo.

Jan 8, 1916

By Richard Moldenke

ONE of the little-known characteristics of cast' iron, which neverthe-less has an important bearing on results where accuracy in machining-is essential, is the ability of this material to ease up internal strains when. .allowed to remain quiescent for a more or less extended period of time. At seems as if the molecules in such a casting, by virtue of their "mobility,? can adjust their relative positions to an extent sufficient to overcome some of the existing stresses. The following instance will perhaps give a fair idea of the condition a casting may he in when just shaken out of the sand. A very large sheave-wheel, after shaking out, was taken' outdoors to be, cleaned and made ready for turning up. It was leaned against the side of the building, but before much could be done an arm tore apart with a loud report. Investigation showed that the sun had been shining on the upper rim, this adding a slight strain to those already existing within the arm and thus overbalancing the strength of the metal in tension. Had this sheave been kept under cover for a while, or at least until machined, the-strains., would have eased off sufficiently to allow the sun to look upon it without disaster. It will not be necessary to multiply examples. Every engineer knows the danger of water-hammer in pipe lines, particularly if the latter are of cast iron. Every mechanic knows, or should know, that it is not good to strike a fitting that is under steam pressure. It will be necessary to say a few words on the "internal- strains" in castings-the so-called "casting strains" we hear so much about. We all know that to get a casting reasonably true to the dimensions wanted requires a slightly larger pattern. The usual allowance for gray iron is 1/8 in. to the foot (1 cm. per meter) and ¼ in. to the foot (2 cm. per meter) for white iron (all dimensions). This reduction in length, breadth and thickness in a casting is erroneously called "shrinkage." It should be called "contraction," as for practical purposes. it is simply the difference .in dimensions of the casting red-hot and cold.

Jan 2, 1917

By Henry A. Pohs

It is a rare work of art that attains the proportions of a major construction project. One instance of such a phenomenon is Bartholdi's Miss Liberty, which was designed and built section by section in Paris and then erected in New York Harbor. Another is Borglum's massive presidential quartet hewn from the granite of Mount Rushmore. Now, however, there is a new monument in the making which will completely dwarf all others. The sculptor of this supercolossus is Korczak Ziolkowski, a colorful, bearded genius who assisted Borglum on Mount Rushmore and is now carving his own granite masterpiece from Thunderhead Mountain near Custer, S. D., just ten crow-flight miles away from Rushmore.

Jan 11, 1966

By D. E. Trout, W. R. Hibbard

Previous investigations have shown that the cold rolling textures1n2 and the drawn wire textures3 of copper change their secondary components after the addition of about 1 pct aluminum and 5 pct zinc, but do not change after the addition of as much as 30 pct nickel. However, few data are available on compression textures. Barrett4 reports from unpublished work with E. L. Layland that compression rolled copper develops a texture which is predominately (110) in the compression plane with a secondary spread to (113) and weaker spread to (100) as shown in Fig 1. However, 70-30 alpha brass similarly treated develops a texture again predominately (110) in the compression plane and with a weak secondary spread to {113} but with moderate (111) secondary intensities illustrated in Fig 2. Experimental Procedure Specimens of the compositions shown in Table 1 remaining from a previous investigation3 were annealed to a grain size of 0.090 mm average diam and machined to cylinders 0.20 in. diam and 0.20 in. high. Cylinders were compressed 90 pct reduction in height between lubricated steel blocks in a tensile machine. Glancing X ray photo-grams using copper K-alpha radiation were taken at an angle of 0 degrees to the compression surface. (111), (002) and (220) rings were analyzed to define the textures shown in Table 1. The results are in agreement with Barrett4 as to types of textures and are essentially in agreement with previous work1,2,3 as to the effects of composition. In the wire study3 it was reported that the 4.99 pct zinc alloy had a brass-type texture, while the data in Table 1 indicate a copper-type texture for compression. The wire specimen of the 4.99 pct zinc alloy was re-examined by X rays and it was established that the [loo] component still exists in the wire axis. Therefore, Table 2 of Ref. 3 is in error and should indicate a double [ill], [loo] copper-type texture for this alloy. This correction results in complete consistency with regard to compositional effects, namely that copper and its alloys containing up to approximately 1 pet aluminum, 5 pct zinc and at least 30 pct nickels develop a copper-type texture and more concentrated copper-aluminum and copper-zinc solid solution alloys will form a brass-type texture. Summary Compression textures developed in copper and its alpha solid solution alloys of aluminum, nickel and zinc are essentially the same types as those re- ported by Barrett4 with compositional effects occurring at approximately the same percent additions as previously reported for rolled sheet182 and drawn wire.3 The Scovill Manufacturing Co., Waterbury, Conn., furnished the copper and brass alloys, performed certain chemical analyses and supplied laboratory facilities where needed. References 1. Brick, Martin and Angier: Tram. A.S.M. (1943) 31, 675. 2. Dahl and Pawlek: Zlsch. Melall. (1936) 28, 266. 3. Hibbard and Yen: Trans. AIME 175, 126. Melals Tech.. Feb. 1948, TP 2334. 4. Barrett: Structure of Metals, mc- Graw-Hill (19421, 386.

Jan 1, 1950

NEW MEMBERS The following list comprises the names of those persons who became members during the period Nov. 10 to Dec. 10, 1914: Members ABBOTT, Louis BENJAMIN, Chief Engr., Consolidation Coal Co., Elkhorn Div., Jenkins, Ky. ANDERSON, THORVALD J 542 S. Seventh Ave., Mt. Vernon, N. Y. BALFOUR, A. M P. 0. Box 301, Republic, Wash. BOUDWIN, WALKER J., Mech. Engr 159 Pierpont Ave., Salt Lake City, Utah. BRADLEY, LINN, Engr Research Corpn., 63 Wall St., New York, N. Y. BROKAW, ALBERT DUDLEY, Asst. Prof., Min. and Econ. Geol., Univ. of Chicago, Chicago, Ill. BUTLER, PERCIVAL PACE, Asst. Supt., Copper Queen Reduction Wks., Douglas, Ariz. CAJANDER, SVEN G., Mech. Engr Braden Copper .Co., Rancagua, Chile.

Jan 1, 1915

By Carl Henrich

While the size of the blast-furnaces used for smelting leadand copper-ores has constantly increased, during late years, the manner of removing the slag from the furnace to the slag-dump has (until quite recently, at least) practically remained the same. The only appliance in practical use has been the two-wheeled slag-pot, holding about 300 to 400 pounds of slag, or as much as one man could manage to pull or push on a smooth, hard surface. When these slag-pots on wheels were first introduced, the daily capacity of a lead or copper blast-furnace hardly reached 30 tons of smelting-charge. With furnaces of this size, and even when the capacity had been doubled, this kind of slag-pot answered well enough. All the improvements made were in the construction of these pots and not in an increase of their size, which was limited by the weight which one man could handle. But the size of the furnace went on increasing. The daily consumption of one furnace rose gradually to 75 tons, 100 tons, and even more. The writer had occasion to construct some of these furnaces, which, in their day, were among the largest, if not the largest, of the water-jacketed kind then in existence. A water-jacketed furnace will always smelt more in the same time than a furnace with brick walls. Already, in those days, the slag-removal from these enlarged furnaces received due attention by the writer. The removal of 60 tons of slag in 24 hours, in pots holding only 300 pounds each, will require 400 pots to be filled in 24 hours; and when the amount.of slag increases to 90 tons, 600 pots will be required. That is to say, in the last case, 25 pots in each hour, or 1 pot each 24 minutes, will have to be put under the slagspout, filled, pulled away, and replaced with another. This will involve too much hurry for any degree of comfort, convenience

Jan 1, 1896

By AIME AIME

MEMBERS of the Engineering Education Committee held two meetings at Joplin preliminary to the opening of the main meeting there. The first was held on Sunday afternoon. It was attended by all who had arrived early enough and as among the dozen or' fifteen who were present the heads of a half dozen schools of mines were included it was a representative gathering. C: H. Fulton, chairman of the Committee presided and T. T. Read acted as secretary of the meeting. The chair., man reminded those present that last year there had been some discussion as to the advisability of the proposal, made by Edward Steidle, that a, separate society, devoted to education in the mineral industry, he organized. Many .people had felt that there are already so many societies in existence to demand one's time and attention, that it would be a mistake to add to their number and the counter suggestion had been made that the work of this committee could be so reorganized as to meet all the needs that a separate society could fill. He therefore presented for discussion these four' questions: (1) Shall a subcommittee .be appointed to study, and report in February, 1932, the possibility of the reorganization of the work of the Engineering Education Committee into the equivalent of an' Institute division; (2) if the work is so reorganized what shall be the relation of the work of the Committee (division) to the work of the-Society for the Promotion of Engineering Education; (3.): what are the, cardinal objectives of education for the mineral industry; and (4) what should be done as regards the movement in some institutions to plan their work-in the light of that being done in other institutions, for example, in geophysics?

Jan 1, 1931

By K. P. Gupta

The Cb-rich boundary of the (Cb,Al) a phase field at 1250OC is near 41 pct Al. The Al atoms tend to occupy the C. N. 12 sites in this structure. A homologous (Ta,Al)a phase was identified. No a phase was found in the Mo-Al system at 1200°C. The first binary o-phase with a non-transition element as a major component was found1,2 in the Cb-Al system. The composition of this phase was reported2 as approximately 34 at. pct Al, based on X-ray diffraction patterns taken of alloys in the as-cast condition. Further study of the composition of this o-phase, therefore, appeared desirable. Since Si was previously found3,4 to occupy preferentially the lowest C.N. sites (I and IV) in the a phase, and preliminary resultsa indicated that Al may show similar ordering, one of the aims of the present work was to obtain more complete information on ordering in (Cb, Al) o. Among the binary systems of Al with Ti-, V-, and Cr-group elements, the Ti-Al, Zr-Al, V-Al, and Cr-Al systems are known to comprise no o-phase. In the present work a Ta-Al and a Mo-Al alloy were studied in an effort to find additional o phases with Al as a major component. EXPERIMENTAL PROCEDURES AND RESULTS An alloy with the intended composition of Ta + 40 at. pct Al was prepared by arc melting in He atmosphere. In both the as-cast condition and after annealing for 10 days at 1250°C and quenching in cold water this alloy consisted of two phases, as seen in the X-ray pattern and the microstructure. One of these phases was identified as the o-phase; the observed and calculated d-spacings are shown in Table I. The lattice parameters of this o-phase are a = 9.972 A, c = 5.214 A and c/a =0.5228, as determined from a Debye-Scherrer pattern using Fe K a radiation. The d-spacings for the unknown second phase are given in Table 11. The alloy contained approximately 25 pct of the unknown phase after annealing, as estimated on the basis of microscopic examination. A Mo-Al alloy was prepared by arc melting, with an intended Al-content of 35 at. pct. The alloy button was annealed for 7 days at 1200°C and water quenched. The X-ray pattern of the alloy in both the as-cast and the annealed state showed the reflections of Mo3Al (Cr30 type structure) and an unknown phase different from a. Six Cb-Al alloys were prepared in the composition range 30 to 50 pct Al. All alloys were arc melted in He atmosphere. After annealing for three days at 1175oC in evacuated silica capsules and quenching in water, the alloys with 30 to 40 pct Al contained three phases, namely the o-phase, Cb3Al (Cr3O-type structure) and an unknown phase. The alloys with more than 40 pct Al contained two phases, namely, what appeared metallographically, the o-phase and the same unknown phase. In the alloys containing less that 38 pct Al, the unknown phase was not present after annealing for 4 days at 1250°c,

Jan 1, 1962

By R. Steven Maxwell, Ulrich Petersen

Most minerals have experienced a slow hut perceptible decline in their annual primary production growth over the past hundred years. This decline is due to a combination of factors: (1) increased recycling; (2) exhaustion of the more accessible or higher grade ores; (3) partial substitution; (4) the more efficient use of materials; (5) progressive saturation of markets as living standards rise. Therefore, future demand for new mineral resources will probably be lower than anticipated. As the world population stabilizes, this slowdown in production growth will become even more pronounced.

Jan 1, 1979

By George P. Chapman

Mica is a platy mineral occurring in a variety of complex hydrous aluminosilicate forms with differing chemical composition and physical properties. Principal minerals in the mica group include: Muscovite-potassium mica (colorless or pale green/ ruby) Phlogopite-magnesium mica (dark brown or amber) Biotite-magnesium-iron mica (black or dark green) Lepidolite-lithium mica (lilac) Selected properties are given in Table 1. Muscovite is most important commercially with phlogopite of lesser use. The laminated structure of mica enables it to be split into very thin films which are transparent and tough as well as having outstanding dielectric and insulating properties. Commercially, mica is used in a number of forms (Chowdbury, 1941; Rajgarhia, 1951; Skow, 1962). Sheet mica consists of flat sheets mined from naturally occurring books of mica, free from defects and capable of being punched or stamped into required shapes. Sheet mica is separately classified into blocks, films, or splittings according to thickness. Built-up mica, or micanite, is made by arranging overlapping splittings in layers , cemented with a binder and pressed together at high temperature. Reconstituted mica, or mica paper, is made by depositing fine flakes of high-quality scrap mica in a continuous film impregnated with binder. Scrap and flake mica are normally unsuitable in quality or size for making sheet mica. Originally the term scrap mica referred to the waste byproduct of mining and fabricating sheet mica, and distinct uses were developed for this material. Subsequently it became economically feasible to mine lower quality mica for these uses, and the term flake mica was introduced. Although the two terms are still used somewhat synonymously, it is considered better, at least in the United States, to use the term flake mica in referring to mica mined for uses other than as sheet mica; and to restrict the term scrap mica to mica mined for or with sheet mica, but which will not meet the specifications. Synthetic mica, such as fluorophlogopite, is produced by slow crystallization of a melted blend of pure raw materials. Mineralogy In the true sense the term mica does not relate to, a particular mineral, but to a group or family of minerals of similar chemical composition and to some extent similar physical properties. These minerals are predominantly potassium aluminum silicates with varying amounts of magnesium, iron, and lithium. The precise formulas and isomorphic relationships of the various group members have been studied, but general agreement has not been reached (Grimshaw, 1971; Hurlbut, 1952; Skow, 1962). The general formula describing the chemical composition of micas is [X2Y4-6Z8020(OH, F)4, where X is mainly K, Na, or Ca; Y is mainly Al, Mg, or Fe; Z is mainly Si or Al (Deer, et al., 1962).] These minerals have an internal structure of the layered lattice type where the silicon atoms are in the center of a tetrahedral grouping of oxygen atoms. The groups are linked together in a single plane by three oxygen atoms that lie within the common plane. Each of these oxygen atoms is shared by two tetrahedra. These linked tetrahedral groups, when continually extended, produce a hexagonal network within the plane. This internal structure of the mica has been used to explain the ex-

Jan 1, 1983

By J. Iannicelli

Availability of large-scale high field/high gradient magnetic separators during the past five years allows applications of magnetic separation to feebly paramagnetic materials which have been considered nonmagnetic in the past. Technology is now available for magnetically attracting not only feebly magnetic compounds of iron such as hematite and pyrite, but also hundreds of compounds of nonferromagnetic elements such as copper, tin, uranium, vanadium. Besides enabling novel separation of industrial minerals, metallic ores, and coal, the new technology also can be used in effluent treatment, catalyst cleanup, and purification of chemicals.

Jan 1, 1979

By A. L. Hornbaker, S. D. Schwochow

Industrial minerals are becoming increasingly important in Colorado's mining industry, not only in production value but also in the variety available and in their potential development for both conventional and new uses. Fluorspar, building stone, fire clay, and pegmatite minerals have been historically important but are not now extensively mined. Aggregates (sand, gravel, and crushed stone), cement materials, metallurgical limestone, and common clays currently are the highest valued commodities. Those offering the greatest future potential include diamonds, nahcolite and dawsonite associated with oil shale, alunite, potash, zeolites, and rare earths.

Jan 1, 1982

By Evan Just

Government aid, regulation, and participation in the mineral industry are not new; they date back to the time when man first adopted communal living. Even in primitive tribal life, the obtaining of arrowhead or ceramic materials, washing of gold, or mining of copper were specialized activities, under tribal sponsorship. Later, when kingdoms, dynasties, and hierarchies developed, titles to mining properties were held by the sovereign or the state, work usually being done by slaves. Title acquisition through denouncement developed in Europe in the late Middle Ages and spread to the Western Hemisphere with the Spanish and Portuguese empires. Denouncements still recognized the rights of the sovereign in the requirement to pay royalties, which practice continues in many places today. Thus, anyone who views government participation in mineral activity as "encroachment" has no historical perspective. Only in a few countries and for a few generations have private interests enjoyed the right to exploit mineral deposits without the specific consent of the sovereign or without payment-of-royalty. Governments and the mineral industry have been linked together by other factors. Governments have had special interest in metals and minerals as stores of value and for armaments. Spanish conquests in the New World were energized by the lure of gold and silver. Pursuit of gold led to the American seizure of California in the days of the Forty-niners. The strategic importance of minerals in our own times has called for special steps to stimulate production in national emergencies and to prevent the enemy from acquiring mineral supplies. Our export controls to deny certain minerals to unfriendly countries, purchases for Government stockpile, and subsidies for domestic production are examples. Production regulation by state governments of oil and gas has become a well established routine. In brief, the mineral industry has never lacked aid, regulation, and participation by governments. The entrepreneur who wishes to explore for or develop minerals must deal with governments in most areas before he can begin, because mineral rights are reserved by them. He can proceed through discovery and de-

Jan 1, 1959

By John A. Wolfe, James A. Niederjohn

Applications of mathematical statistics to the field of exploration are still relatively new. There are two primary reasons why little has been published in this field. First, if one discovers an effective technique for exploration, he does not like to disclose it. Second, the geologist needs to work closely with a mathematical statistician, and the communications barrier between the disciplines is formidable. The authors, one a geologist and the other a statistician, were interested in the economic benefit which appeared to be possible in the inter-disciplinary area they call "geostatistics."

Jan 11, 1962

By P. Lees, N. Parkinson, K. Hartley, D. M. Donaldson

The reprocessing of advanced fuels such as carbides, oxides, and cermets, containing up to 30pct pu has been studied. Dissolution of uranium carbides in nitric acid produces appreciable quantities of mellitic acid which has undesirable effects in subsequent stages of the process. Mixed oxides containing up to about 40 pct Pu in solid solution with UO, are soluble in nitric acid and a leaching type process in nitric acid for a stainless steel/UO,. PuO, fuel containing 30 pct Pu appears to be feasible. It offers considerable economic advantages THE reprocessing of the U-Cr alloy core of the Dounreay Fast Reactor was described by Buck and others at the Second Geneva conference.' This paper described the flowsheet and plant for processing a relatively simple fuel of good dissolution charac- over total dissolution routes. A new oxidation-sub -limation process is described for metallic fuels containing up to 12 pct Mo. New data is presented on the solvent extraction of uranium and plutonium nitrates into tributyl phosphate -odorless kerosene and of the influence of radiolytically produced acid phosphates on this part of the process. It is concluded that there are no insuperable difficulties which will prevent the satisfactory reprocessing of high burn-up plutonium fuels by a solvent extraction route. teristics and of low-plutonium content after irradiation. However, it has been clear for some time that more satisfactory operation of the reactor can be obtained by the use of a core with better irradiation performance than U-Cr alloy and a U-Mo alloy will be used for the next charge. Recent modifications to the core mean that it is now possible to carry out irradiations of fuel element subassemblies similar to those which might be used in a fast power reactor and trials with plutonium-bearing fuel elements will be made in the relatively near future. These changes have meant that a considerable amount of reprocessing development work has had to be carried out for

Jan 1, 1963

By G. R. Kotler, W. A. Tiller, W. C. Johnston

Experiments carried out on 100 g samples of molten tin and Sn-Pb alloys showed that the magnitude of the field strength, H, does not effect the supercooling, aTn, at which the initial nucleus of solid forms. However, the nuwlber of nuclei forming per cc, n, is found to increase greatly with H for fixed ATN and to increase with ATN for fixed H. The value of n increases greatly with the presence of solute and is found to he indefiendent of the cooling rate of the simples. Further, the most effective time for stirring to enhance n is immediately following the initiation of recalescence. The effect of inducing nucleation with the aid of a mechanical impact both in the presence and absence of stirring has also been studied. All proposed mechanisms for the enhancement of n by physical means seem to be inadequate in accounting for these results. IN any real nucleation experiment there are two effects influencing the results that would not be predieted from classical homogeneous nucleation theory. These may be separated into chemical and mechanical effects. The chemical effects are twofold. 1) Nucleation catalysts are present which enhance the nucleation frequency of new grains over that predicted by classical homogeneous nucleation theory.' 2) Solute will restrain the growth of nuclei so that many others may form.2,3 The mechanical effects are also two-fold. 1) Vibration (sonic or ultrasonic) of the freezing liquid enhances the nucleation frequency of new grains over that given by the chemical effects alone.4-6 2) Macroscopic fluid-flow effects produce the same effect as l).'7' It is also possible to influence the nucleation experiment by certain physical effects such as the application of electric and magnetic fields.9 From classical homogeneous nucleation theory one would predict the following relationship between the nucleation rate, N1 (number of nuclei formed per unit volume per unit time), and bath supercooling, AT, for an isothermal experiment.

Jan 1, 1963

An Interstate Mining Commission organized in Raleigh, N. C., on April 27 still has no offices, no budget and only four members, but it could spell the beginning of the end for the state-to-state environmental control variations that have lately been con- founding the mining industry. Established by Kentucky, North Carolina, Oklahoma and Pennsylvania, the new organization is committed to protecting land, water and other resources through improved strip and other mining practices. In pursuit of this end, it has broad authority to study all mining activities affecting the environment and to recommend improvements in mining practices and in laws regulating the mining industry. The Startup The Commission was created under an interstate Mining Compact enacted in the 1960's by the legislatures of the four member states. According to the rules of this Compact, the Commissioners in the new organization are, ex officio, the governors of the member states-namely, Chairman Louie B. Nunn (Ky.), Vice Chairman Robert W. Scott (N.C.), David Hall (Okla.) and Milton J. Shapp (Pa.). Each Commissioner, however, must appoint an advisory body to counsel him in matters relating to Commission business and delegate one member of this body to act as his alternate. Each advisory body must include representatives of mining, conservation and other public and private interests.

Jan 1, 1971