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By R. E. Somers

I. Introduction...........................604 1. Location, Topography, and Climate...............604 2. Scope of Work and Acknowledgments...............606 3. History and Mining......................606 11. General Geology.........................609 1. Introduction...........................609 2. Granite. :..........................610 3. Quartz Porphyry......................... 612 4. Monzonite........................... 614 5. Volcanic Breccia........,................ 618 6. Gravels............................. 619 111. Economic Geology......................... 619 1. Introduction........................... 619 2. Mineralogy........................... 619 3. Occurrence of the Ores...................... 622 4. Oxidation and Downward Enrichment............... 630 5. Rock Alteration........................639 6. Genesis of the Ores........................ 643 I. Introduction 1. Location, Topography, and Climate The Burro Mountains are located in the southwestern part of New Mexico, in Grant county. The group is made up of two distinct mountain masses, known as the Little Burros and the Big Burros, the former lying about 6 miles southwest of Silver City, and the latter about 9 miles farther in the same direction. They are separated by the valley of the Mangas River, a tributary of the Gila, and a stream only in name, except after a heavy downpour of rain. The Little Burros attain an elevation of 6,625 ft. above sea level, and the Big Burros 8,054 ft., with the surrounding country averaging about 6,000 ft. To the south of these mountains stretches the desert plain, while to the north are the more frequent elevations of the mountainous country.

Jan 1, 1916

By L. VOGELSTEIN

OUTSTANDING among the year's events in copper has been the reimposition of an import duty of 4r. per pound in this country which became effective June 21. In consequence of this action by Congress, the Ottawa Empire conference recommended a duty of 2d. per pound equivalent at normal rate of exchange to our 4c. duty, on all copper originating outside of the Empire. Lip to the middle of this year only Russia and Japan had a closed market; the import duty on copper in Russia is 30 per cent ad valoremm and in Japan about 2c. Russia's consumption has always been in excess of production and she has imported from 2(1,000 to 40,000 ton, of copper per annum. Japan, with a production of 6,000 to 7,000 tons per month, has absorbed, in normal times, its production, but during recent: sears has exported varyiug quantities in 1929. 2,200 ton-: in 1930, 2,700 tons, and in 1931. 3,600 ton-. Aside from the-e two countries, the international market has heretofore been free. It and when the British Empire duty become, effective the world's markets will be divided into four unit: 1. Russia and Japan, 2. United States. 3. British Empire. 4. Rest of the world. The world's production at present is rennin it the rate of 930.000 tons per annum. This year's production will be over 1,000,000 tons because the several curtailment did not become effective until the second quarter. consumption will be slightly in excess. Deducting from 30,000 tons Russia's and Japan's production of 121.000 tons, 806,000 tons is left divided a, follows:

Jan 1, 1932

By Lawrence P. Bonicatto

The steel industry's increased demand for higher grade pellets has caused the pellet producers to investigate methods of upgrading their product and the Hanna Mining Co.'s Groveland plant on the Upper Peninsula of Michigan is no exception. The low grade iron deposit is a complex mixture of magnetite and hematite with chert, quartz, jasper and various iron silicates.1 Beneficiation is by Humphrey spirals and anionic flotation of the iron minerals.2 Flotation of the spiral tailings makes up about 75% of the concentrate, while a minor amount of concentrate (less than 3%) is produced in magnetic circuits. The concentrate is pelletized at the rate of 1.6 million tpy. The initial concentrating facilities were constructed in 1958 and the concentrate was marketed as sinter feed until a pelletizing plant was added early in 1963. Grade improvement soon became a high priority research project, and several methods of concentration were investigated.

Jan 3, 1968

By M. K. Yen, W. R. Hibbard

Previous studies of plastic deformation of metals have emphasized the important role of bending and constraints during strain under relatively pure stresses.1"5 Some new phenomena such as early conjugate slip6 and polygonization7 are intimately concerned with the relief of bending stresses, the former by slip and the latter by a process analogous to re-crystallization. However, few analyses of the bending deformation of single crystals were found in the literature, and those8,9 are sufficiently previous to the modern interpretations of slip to invite further investigation in this area. The transverse bending mode of testing, using the two-point loading method, was selected because the center portion of the specimen may be considered as under a theoretically pure bending stress with a uniform bending moment. Considerable attention was given to both the lattice distortion and flow characteristics of the crystals during deformation. Experimental Proeedare A specimen under the action of equal and opposite couples at both ends is said to undergo pure bending. The shear and moment diagrams of a specimen under the two-point loading method of transverse bending are shown in Fig 1. The moment over the middle-third of the span is equal to PL/6, and the vertical shear is zero. Fig 2 (A) illustrates the stress distribution in the elastic range on a plane across the middle of the specimen. It can be seen that the normal stress has a maximum value at the extreme surfaces on the tension and compression sides, and decreases proportionately to zero as it approaches the neutral plane. However, when the plastic range is reached, the stress distribution is no longer a straight line relation, but changes in a manner which can be best illustrated as shown in Fig 2(B). The following calculation and stress analysis are mainly in accordance with the works reported by Timoshenkol0 and Kochendörfer.9 From the simple beam formula, the maximum normal stress will occur at the surface of the specimen. For a round specimen with a radius r and for a rectangular specimen with a height 2h and width 2b, the maximum normal stress, Sp, will be given by the following formulas: For round specimen: 2PL Sp = 3pr3 [1] For rectangular specimen: Sn = 8bh2 [2] Since it is reasonable to consider that slip takes place under the same conditions as in uniaxial loading, the resolved shear stress S?, along the operative slip direction will be as follows: For round specimen: 2PL sin x cos ? Sp = 3pr3 sin x cos ? [3] For rectangular specimen: PL S8 = 8bh2 sin x cos ? [4] where X is the angle between the specimen axis and the slip direction and X, the angle between the specimen axis and the major axis of the glide ellipse. It was also reported by Kochenclorfer9 that the critical bending moment, that is, the bending moment exerted on the specimen to initiate slip, should be higher than the value given by the equations stated above. Based

Jan 1, 1950

By AIME

WE got our chance to talk with Arthur J. Blair at the Annual Meeting at the Pennsylvania Hotel. By two o'clock Wednesday afternoon things had quieted down enough so we had our interview in the foyer to the Ball Room. There were the usual questions. Where were you born? In La Salle County, Ill., on March 26, 1885. Where did you go to school? Northwestern University, B.S. degree in 1906. Where did you start work? For E. J. Longyear right after leaving school. One's ability as a geologist was measured by one's ability to wield a brush hook and ax. He stayed on the job as geologist for three years and then got to thinking about the advantages of a warmer climate. The advantages stacked up favorably, so off he went to Birmingham, Ala., just about the time U.S. Steel took over the Tennessee Coal, Iron and Railroad Co.

Jan 1, 1948

By Reginald E. Hore

I. INTRODUCTION. SINCE the discovery of silver at Cobalt, Ontario, in 1903 more than 100,000,000 oz. of silver have been produced b: the mines in the Nipissing district, and there is reason to believe that at least as much more will be produced in the next five years. The estimated value of the aggregate output o ore to the end of 1910 is $48,327,280. The ore yielded 93,977,833, oz. of silver and was mined at a net profit of about $26,000,000. For 1910 the production was 30,558,825 oz. valued at $15,436,894, and yielding a profit of about $9,000',000 The details of the production of the Cobalt district for the years 1904 to 1909, inclusive, are given in Table I. TABLE I.-Silver-Production of the Cobalt District, 1904 to 1909 SMELTING-ORE. Production. Value. Silver-Content. Value Per Ton Ounces. Oz. Per Ton. 1904 206,875 $111,887 1,309 $708 1905.:.... 2,451,356 1,360,503 1,143 634 1906 5,401,766 3,667,551 1,013 687 1907 10,023,311 6,155,391 677 416 1908 18,022,480 8,468,293 736 363 1909 22,436,355 10,809,872 809 389 CONCENTRATES. 1908 1,415,395 $665,085 1,240 585 1909 3,461,470 1,651,704 1,174 559 The shipments from Cobalt are in the form of smelting-ore, concentrates from milling-ore, and bullion. The smelting-or( is largely high grade, averaging about 3,000 oz. per ton- A

May 1, 1911

By H. Pew, J. H. Field

To alleviate pollution more restrictive legislation is being enacted, either limiting emission of pollutants or the type of fuel that can be utilized. The nature and magnitude of air pollution problems affecting the mining, preparation, coking and combustion of coal are described. Methods for combatting particulate emissions by use of mechanical separators and electrostatic pre-cipitors are discussed. Proposed methods to meet the problem of gaseous emissions currently receiving considerable attention are described, with special emphasis on methods to decrease pollution by sulfur oxides. Concern about air pollution goes back several centuries, but until very recently most effort has been aimed at coal smoke and other visible pollutants. The classic example of a 'successful' campaign for smoke abatement and control is the fruitful combined effort of the city of Pittsburgh and its surrounding Allegheny County, which eventually led to the reconstruction of downtown Pittsburgh at an estimated cost of one billion dollars. Historically, the city's downtown Golden Triangle district had been afflicted by pollutants evolving from steel mills, from a variety of other industries, and from railroad locomotives. Efforts to alleviate the situation prior to 1943 were virtually ineffective. In 1945, however, a comprehensive redevelopment plan was prepared and backed by state authority. Within a few years a clean, modern metropolis has evolved where once stood America's famous 'smoky city.' But the victory in Pittsburgh, as in various other American cities, has not solved the national problem. Current estimates indicate that 133 million tons annually of air pollutants from all sources still are emitted annually into the atmosphere above the United States. About 10% of this annual effluent is particulate matter so that most of the remaining pollution problems will be solved only when other effluents are reduced. Essentially, these are sulfur oxides, nitro- gen oxides, hydrocarbons, and carbon monoxide. Over the years, both states and local communities have tended to increase the restrictions on smoke and fly ash — problems mostly of concern in the combustion of coal. Prior to the middle 1950's, ordinances sometimes permitted emissions of smoke equivalent to as much as No. 3 on the Ringlemann scale. Since 1956, no ordinance has been passed which allows smoke of greater than No. 2. Under today's conditions of improved fuels, equipment and practice, a few communities have passed laws prohibiting emission of smoke of any density darker than Ringlemann No. 1. The majority of existing laws on fly ash emission in the U.S. limit emissions equivalent to 0.85 lb of fly ash per 1000 Ib of flue gas. In recent years, however, regulations which have been adopted give cognizance to the higher level of performance now obtainable with improved equipment. A comparison of the restrictions of five codes adopted since 1960 is given in Table I. The most stringent of these is the one for New York City which provides for a maximum emission of 0.6 lb fly ash per million Btu heat release (equivalent to roughly 0.51 lb/1000 lb of flue gas). The first comprehensive effort to restrict the emission of SO2 resulted from the passage of a 1937 law in St. Louis. This regulation stipulated that coal containing in excess of 23% volatile matter and 2% sulfur must be washed, thereby presumably producing some effective reduction in the input sulfur content. This was followed in 1949 by a Los Angeles County law which prohibited the emission of SO2 in concentrations greater than 0.2%. Most SO2-restrictive legislation passed since that date has been based on this limiting 0.2% SO2 by volume, although modifications are occasionally permitted under selected conditions, sometimes based on the fact that certain limiting ground concentrations are not exceeded — such as in the rules adopted by the San Francisco Bay area. To date, no legislation has been passed in the U.S. to limit the generation of nitrogen oxides from the combustion of fossil fuels. However, such oxides are considered to be of potential importance in air pollution control because of their possible detrimental effects on health and their reported role in the formation of photochemical smog. Interest in reducing oxides of nitrogen from powerplant and auto exhausts is increasing and regulations limiting their quantity can be expected in the future.

Jan 1, 1968

By James Gayley

(Wilkes-Barre Meeting, June, 1911.) THE paper presented to the Institute in 1910, by H. 0. Hofman, on Recent Progress in Blast Roasting,1 has called the attention of the iron industry to the adaptability of these processes to the reclamation of by-products such as flue-dust and blue billy, and the better preparation of concentrates and fine ores for use in blast-furnaces. The waste of valuable iron-ore through the production of flue-dust has increased at an enormous rate, and much of it has in reality been wasted as far as future recovery is concerned. Only in recent years has a possible future value been recognized, and the material stored. The increased use of Mesabi ores, which carry considerable fine ore, is principally responsible for the great increase in the production of flue-dust. The amount of fine material that is carried over depends on the fineness of the material and the velocity of the gases, and also to a very great extent on the regularity or irregularity of the working of the furnace. Attempts to recover a part of this loss have been made by recharging a portion of the production into the furnace, but as this material has been once carried out from the furnace, it is naturally in good shape to be carried out again. A recent practice at some works, is to soak the flue-dust thoroughly with water to give it more cohesiveness, but by many this is considered of doubtful advantage in the furnace, and the gases are in consequence heavily laden with moisture. There are vast deposits of magnetic iron-ores in the United States and Canada that are too low in iron for use at the present time, but which can be economically concentrated into very rich material ; in many cases the fineness of crushing necessary to secure proper concentration has prevented their

Aug 1, 1911

By Lyden, Joseph P.

THE Picher Mining Field, fig. 1, which lies between Baxter Springs, Kansas, and Commerce, Okla., is the most intensely mineralized and the largest zinc-lead ore producing area in the Tri-State District of Missouri, Kansas, and Oklahoma. It has a vast lateral extent of underground workings that is unequaled for the observation of the geology of zinc-lead ore bodies in sedimentary horizons; and thousands of churn drill holes in the unmined areas supplement the underground observations with useful data for the interpretation of the geology. This paper is confined to the ore deposits of the Picher mining field. The reader is referred to the bibliography for the general geology of the Tri-State district which has been ably covered by many geologists. The writer was co-author of several publications on the Tri-State district.- This paper is necessarily a repetition of parts of those publications but contains a few changes and additions on the deposition of the minerals. The parts of this paper concerning mineralization maps and pipe slump-structures are not covered in the above publications.

Jan 1, 1950

By P. L. Lavery

A numerical method to derive approximate solutions for stress intensity factors for rectilinearly anisotropic bodies without resolving to complex variable approach is presented. The method is based on the assumption that the crack opening profile can be simulated by a simple curve such as an elliptic function and a relationship is found for the stress intensity factor in terms of near tip displacements. An example solution is derived for a transversely isotropic body and the results are verified with Westergaard's stress function approach. The proposed model has a great potential for the applications to fracture mechanics of anisotropic rock materials.

Jan 1, 1984

By Edwin Ludlow

T HE OPEN FORUM on this subject called by Mr. Hoover at the recent meeting of the Institute' brought out a large number of very able papers, and a very full discussion of all the problems involved. The criticisms of the bituminous industry were: 1. That it was over-developed with the possible output nearly 50 per cent. in excess of the present requirements; that during the summer there were plenty of cars and no orders, and during the winter there were plenty of orders but no cars. 2. That the mines were not properly developed from an engineering standpoint, and that the recovery of the coal varies from 50 per cent. to 95 per cent. 3. That this industry, employing over 600,000 men, could, if running full time, release 100,000 men for other work. 4. That the studies made by the engineers of the Fuel Administration showed that the cost of production increased with a loss of time and that with a 50 per cent. operation the increase in cost was about 40 per cent.

Jan 1, 1920

By H. Rosenthal, A. L. Jamieson

The action of mercury on stressed brass to produce cracks was known before Moore, Beckinsale and Mallinson1 showed that actual season cracking did not occur spontaneously but could be induced by ammonia. These investigators studied other substances, including diphenylamine, without finding that anything other than ammonia could cause season cracking Grimston2 reported season cracking in cartridge cases stored in wooden boxes wetted with dilute sulphuric acid pickling solution. Season cracking associated with sulphur dioxide, water vapor and air has been reported by Johnston,3 although he reported that trimethylamine and pyridine did not cause cracking. Jevons4 has ascribed season cracking of brass in certain instances to trimethylamine, "aldehyde amine," "ketone amine" and pyridine, but no experimental work was done evidently to prove this definitely. Pyridine was investigated by Morris,5 who found it to have considerable cracking power. In the present investigation, the object was a qualitative evaluation of a number of representative amines with respect to their ability to cause season cracking. Thus it was desired only that an appreciable vapor pressure of each amine be obtained in order to make the test as severe as possible, without attempting to test equivalent concentrations for comparative purposes. MEthods Specimens TWO types of specimen were used: 1. Unannealed 70-30 brass CUPs formed from 0.040-in. thick sheet. Height of cup Was 13/8 in. and diameter was 17/8 inches. 2. First draw pieces of caliber .50 cartridge cases in the unannealed condition (70-30 brass)- The cups were representative of a thin wall and thin base specimen, whereas the draw pieces have a thick base (1/4 in.) and a thick wall (approximately 3/32 in.). Both types of specimens contained high residual stress and cracked in less than one minute in a solution of I per cent mercurous nitrate and I per cent nitric acid provided that this was receded by a 30-sec. pickle in 40 per cent nitric acid. Specimens were prepared as follows: (1) degreased in trichlorethylene, (2) rinsed in H2O, (3) pickled 5 min. in 10 per cent by volume H2SO4 (1.84 SP. gr.), (4) rinsed in H2O, and (5) dried. Amirtes Tested In selecting the amines, representatives of the three series of amines, and one series of substituted amines were chosen. The aliphatic series was represented by the methyl and ethyl primary, secondary and tertiary amines. These are the simplest aliphatic amines. For the aromatic series, the phenyl primary, secondary and tertiary amines were selected as being the simplest. The heterocyclic series was represented by pyridine, which is a simple heterocyclic base (tertiary amine).

Jan 1, 1944

By Blake M. Caldwell, Thomas C. Poulter

A new approach to an old problem has made it possible to do in a a tively short period what has not been accomplished in the past three quarters of a century using strictly experimental methods. A theoretical study was made of the underlying principles whereby a jet is formed by a shaped charge and of the mechanism of the penetration of the target by that jet. It was found that there are more than 10, and perhaps as many as 15 variables affectin!? the performance of the shaped charge. Only a few calculations are necessary to show that it is physically impossible to investigate all of these variables experimentally. The shaped charge theory has been extended to include a previously little-understood mechanism in high explosive phenomena; namely, low order detonation. By superimposing a high order detonation on a zone already undergoing low order detonation, all appreciable improvement in performance is accomplished. The development of a design wherehy these phenomena are coordinated in such a way as to develop a jet which is tailored to meet the specific target requirement will be described in detail. The shortcomings or even impossibility of strictly experimental techniques will be illustrated by a discussion of the development of a special-purpose explosive charge. INTRODUCTION In an article appearing in the May, 1888 issue of Scribner's Magazine, Charles E. Monroe described his early experiments with gun cotton (Fig. 1) which led to his name being most fre-quently connected with our present-day shaped charge. Although the sunken letters or "cavities" in Mon- roe's gun cotton were not lined, they produced some penetration of an iron plate. The credit for the lined shaped charge, however, should rightfully go to Dr. R. W. Wood of the Physics Dept. of Johns Hopkins University, who was responsible for first discovering the fact that a metal liner in a cavity of explosive gave high velocity fragments and/or jets of metal. This discovery was made by Dr. Wood inadvertently while investigating an accidental death resulting from an electric blasting cap. He discovered that a jet of high velocity copper particles was ejected from the dimple

Jan 1, 1958

By W. B. Plank

RETURNS already received from a current survey of the enrolment of students in the mineral technology schools indicate a degree of activity and prosperity in those schools never before equalled. The returns are as yet too meager for accurate analysis, but those at hand point LO considerable increase in the metallurgical and petroleum engineering groups, and indicate that the total of 5011 two years ago in the United States schools will be substantially increased. Generally speaking, the enrolment is not only maximum in quantity but optimum in quality. Better income has sent the boys back to school, but the improved employment conditions have somewhat reduced the number of graduate students. Laboratories are commonly filled to capacity, in some instances overcrowded. Increased enrolment of foreign students from both Canada and South America is noticeable.

Jan 1, 1937

By John V. Beall

Hard as the Revett quartzite are conditions governing the deep mines of the Coeur d'Al6ne. In fourscore years of mining, heat and pressure have been the rewards of preseverance. Such obstacles are the natural concommitant to search for ore at depth. But high cost and shortage of miners is a creeping frustration of the decade. These grim observations were made on a trip to the mines of the Coeur d'Al6ne in the first week of May. But the bouncy optimism of competent mining engineers and geologists overrides by far the tough conditions. This is the story of what they are doing. I think they are setting the stage for the wonder mines of tomorrow. I didn't meet all the people or see all the mines, so there are unfortunate gaps in the story. Then too, sometimes the muck and water blotched my notes, or I couldn't write fast enough or I was too tired. No matter. There is much to tell and, because it is basically a human story, I am flouting the rules of technical journalism and couching it in the neglected "I" person. First then, a little history . . . .

Jan 7, 1966

By W. P. Sykes

ThiS investigation was undertaken primarily to establish the relations existing between temperature and mechanical properties in molybdenum, nickel, and an aluminum-copper alloy. Mlolybdenutn (m.p. 2500" C.) was chosen because it is partly similar to tungsten and partly similar to the common ductile metals. Also it is known to furnish, by proper treatment, a desirable material to use in studying relation of grain size and physical properties. The molybdenum used was of the quality that is drawn into wire 0.003 in. in diameter for use as filament supports in incandescent lamps; Chemical analysis shows less than 0.1 per cent. of impurities. Nickel belongs to the same class as iron. Its melting point is 1450" C. and an allotropic change at about 370" C. results in a loss of magnetism above that temperature. This feature made nickel doubly valuable for the purposes of these tests. The nickel used was obtained from the Driver-Harris Co. as 0.090 in. (2.3-mm.) wire, annealed; analysis showed 99.8 per cent. nickel and 0.150 per ccnt. iron. Aluminum is one of the low melting-point metals. Some tensile tests at clevated temperatures have been reported by Bengough but the possibility of learning more with the low temperature and sensitive apparatus available rccommendcd this metal. The samples marked A1 arc an aluminum-copper alloy that contains 3 per cent. copper, 0.42 per cent. iron, and 0.21 per cent. silicon. The presence of the copper somewhat coniplicates the analysis of the results; but the action of copper in aluminum has been studied so that its influence might have been foretold, in part at least. The material and analyses were furnished by the Aluminum Castings Co. The nickel wire, which was deformed at 400" C., was drawn under a bath of molten lead and through a die, which also was immersed in the bath. A thermocouple was suspended in the molten metal to indicate the temperature. Hot oil was uscd as the heating bath for drawing the

Jan 1, 1921

Jan 1, 1910

By M. N. Shetty

LARGE copper whiskers were grown from cuprous iodide by reduction with hydrogen at about 500°C. Carefully selected single-crystal whiskers of [loo], [110], and [Ill] orientations were used and the whisker shapes and cross sections are shown in Fig. 1. Spec-trographic analysis of a typical batch of whiskers showed that the composition was better than 99.9 pct with iron and silicon as the major impurities. The test specimens varied from about 70 to 400 u in diam and they did not show a conspicuous yield drop as observed in very fine whiskers (diam <25 u), tested by Brenner.1 The characteristics of the stress-strain curves were similar to those of bulk single crystals, even though the maximum flow stresses reached in some orientations were comparable to the yield stresses observed in fine whiskers. Mechanical properties of whiskers of different materials and copper whiskers up to about 100 u in diam have been reviewed,&apos; and a mechanism of slip band propagation in fine whiskers has been recently suggested.3 Whiskers in this work were tested in a floor-model Instron testing machine using low strain rates. (Details of the testing procedure, diameter dependence of the yield stress, and the characteristics of the load elongation and stress-strain curves have appeared esewhere.4) Due to the extensive deformation, >50

Jan 1, 1970

By H. S. Bell

IT SEEMS unnecessary to dwell upon the advantages of the modern pipe still as compared with the older type of distillation equipment used by oil refiners. The relatively low installation cost, coupled with remarkable operating efficiencies of pipe stills, precludes the consideration of other types except in rare instances where some peculiarity of product or plant may have an influence. The question of the actual heat required to distil petroleum is quite involved. We have extensive data on the latent heats of the various hydrocarbons under different conditions of pressure. We also have information regarding the specific heats of various oils and the effect of temperature thereon. Because of the complexity of petroleum and of each fraction, it seems impossible to theoretically analyze the partial-pressure effect of the great number of hydrocarbons upon one another during distillation. If a distillation curve and percentage analysis of any crude or product are available, it is possible to construct a curve with ordinates representing per cent. distilled and B. t. u. per pound or per gallon, or other desired unit. To do so the crude is split into fractions, of 5 or 10 per cent. The boiling point and gravity of each fraction being determined, it is possible to evaluate the heat required. As each fraction is removed, the residue must be raised to a higher temperature and latent heat supplied for the successive fraction. As the calculations progress, the latent heats decrease while the specific heats increase. Such a curve is illustrated by Fig. 1 for a typical 39.9 B° North Texas crude.

Jan 1, 1928

By E. C. Truesdale

A FEW years ago H. M. Cyr, working in the Research Laboratories of The New Jersey Zinc Co., produced a few pounds of zinc1 of such purity that no other elements were detected in it by spectrographic analysis, using the facilities then available. This zinc contained less than one ten-thousandth of one per cent of metallic impurities.2 During the decade that followed upon the laboratory production of this "spectro-graphically pure" zinc, commercial developments brought about the production of large tonnages of zinc of purity exceeding 99.99 per cent, and today zinc of 99.999 per cent purity is produced and marketed as "chemically pure" zinc. Typical analyses of present supplies of high-purity zinc are given in Table 1. TABLE 1.-Typical Analyses Percentage by Weight Sum of Zinc Pb, Fe, Pb Fe Cd Al Cd Special High Grades 0.007b 0.005b 0.0056 none 0.0106 C.P. (chemically pure) <0.0002 0.0005° 0.000052 S.P. (spectrographically pure).. <0.0002d <0.00005d a A.S.T.M. Standard Specification for Special High Grade Slab Zinc (A.S.T.M. Designation: B 6-37). b Maximum. c Fe chemically determined. Pb and Cd are spectrographically determined. d Differences between composition of C.P. and S.P. zinc are discussed later in this paper. The availability of commercial tonnages of special high-grade zinc has been the basis for the development of the zinc-base die-casting alloy industry which, in the year 1936, consumed one-eighth of the zinc used in the United States for all purposes. This and the C.P. and S.P. grades have given impetus to scientific investigations into the properties of pure

Jan 1, 1939