Search Documents

By Warren K. Kourt

Many important discoveries of mineral deposits have been made as a result of routine exploration for oil and gas. Through the presentation of three hypothetical case histories, including cost data, the author shows how mineral evaluation can be performed during routine petroleum drilling operations and how mining companies and oil companies or oil operators can cooperate in such endeavors.

Jan 1, 1972

Planning for a surface coal mine includes selecting the best means and equipment for uncovering the coal, loading it, and transporting it to the preparation plant. The machines and methods that will ensure optimum production will depend upon the location and characteristics of the seam to be mined. Stripping Techniques The choice of stripping units is influenced primarily by the system of mining, such as contour or out-crop mining as contrasted to mining in a region of rolling terrain with relatively flat upland surfaces. Factors such as the life of the mining operations production requirements, types of overburden, local and regional dip of coal, and land reclamation are other important considerations.

Jan 10, 1967

By Colin C. Harris, Nathaniel Arbiter

Current scale-up procedures are discussed critically, including: constant specific energy criterion; determination of mill size and power for a given ore, throughput and mesh of grind; specification of operating speed and loading. A major dynamic and kinetic factor now recognized is that the ratio of media rotational flow to ore axial flow, and the number of mill revolutions that ore is subjected to during residence, both diminish as mill diameter increases. These factors can lead to capacity limitations when mill diameters reach a critical range, especially regarding coarse sizes. Experience at the Bougainville and Pinto Valley operations is contrasted. Corrective measures suggested are to reduce loading and increase speed towards the Davis best operating speed.

Jan 1, 1982

By Rizzi Homestake Mining Co.

Geophysical methods of discovering new mineral deposits have long been routine with both the petroleum and mining industries. Experience has shown that most subsurface structures and mineral deposits can be located, provided that detectable differences in physical properties exist. The main properties exhibited by the more common rocks and formations are: density, magnetism, electricity, electrical conductivity, and radioactivity. This entails five major geophysical methods: gravitational, magnetic, seismic, electrical, and radiation. Applications of radioactivity measurements in geophysical exploration are concerned with location of concentrations of radioactive rocks and materials, such as uranium. The search for uranium ores and minerals has been carried on for more than 50 years, ever since the first atomic breakdown from uranium to radium was discovered. However, the comprehensive search now being made throughout the world for radioactive materials is a direct result of the first atomic explosion and the subsequent development of new and more sensitive portable equipment to detect radiation.

Mar 1, 1956

JOHN H. NELSON, Worcester, Mass.-At our plant we have done considerable work on notch-bar testing and are farther at sea now than when we started. So far, we have been unable to get the notch-bar test to be consistent with any other known test. Lately, I have been investi-gating the effect of the position of the notch-bar specimen in a, bar. To do this I took a 3, ½ in. square bar and quartered it, then heat treated the four quarters. Each of these pieces was again quartered and a specimen machined and notched. "In this way we would have notch-bar tests from the exterior to the interior of the bar. These were made of such lengths that it was possible to make four impact tests on each speci-men. Extreme care was taken in marking the position of these test speci-mens in the original bar. The notches were then cut with relation to position of the specimen in the original bar. The second notch was cut 90° from the first, and so on around the specimen. In this way, we have found that, with a 3 ½ in. bar of 0.4 or 0.5. per cent. carbon steel when properly heat treated, we could get impact values ranging from 15 to 100 ft.-lb. Just why this is the case we are unable to state; but it does appear to be a fact that along the outside of the original bar the notch-bar test seems to be low and increases toward the center, but it is not always consistent. For instance, we may have, on a single specimen; one notch-bar test giving us 15 ft.-lb. and another 100 ft.-lb. We have not found such inconsistencies in alloy steels. Alloy steel is consistently good or consistently bad. If it. is good, you cannot readily destroy the impact value, no matter what you do; if it is bad-that is, if it is a poor notch-bar steel-and you have sufficient latitude in your draw, you may correct it. In other words, if the hardness you are working to will allow you to draw to about 1050° F.(561° C.) or over and then quench this steel from the draw heat, you. can raise the im-pact value of the steel from about 4 or 10 ft.-lb. up to-40-or 50 ft.-lb: Just what occurs I do not know. There is evidently a critical-point in steels that have poor impact value, in the neighborhood of 1000 F. to 1050° F. (536° to 561° C.).

Jan 12, 1919

By James Harding

THE usual method of sampling mineral deposits is to drill holes and assay the sludge or core. Though the results thus obtained may not represent the true average value of the deposit, it is on these results that estimates of practically all large orebodies are made. In a large number of cases, the results of exploitation fall far short of the estimated value of the orebody. The standard method of making these estimates is to find the cubic contents of triangular prisms, in the apexes of which the drill holes are placed, .by multiplying the surface area by the average depth of the ore in the three drill holes and then multiplying the cubic contents by the specific gravity of the ore or rock to find the tonnage. The assay value is found by dividing the sum of the products of the depth of ore in each hole and the corresponding assay value by the sum of the depths of the ore in the three holes. As the latter part of this method is subject to many mathematical errors, it should not be depended on.. Some engineers, therefore, use a discount factor, but as this factor is either arbitrarily selected or is obtained by obscure methods, the results are no better than guesswork. The standard method is correct when the drill holes are so laid out that the triangular prisms are equilateral in cross-section. But as ore deposits cannot always be drilled into at regular intervals and because of the human factor, if many holes are drilled, triangular prisms of all degrees of angularity are produced. In such cases, it is necessary to assume that the influence of the different holes is not the same in all directions, which assumption of course is absurd.

Jan 1, 1921

By John McCaslin

ONE of the most common technical terms in the U. S. today is automation-a word not listed in the 1946 dictionary. The influence of automation on the national economy has been tremendous. It has even been the subject of congressional investigations. Automation, writes Aronson, substitutes mechanical, hydraulic, pneumatic, electric, and electronic devices for human effort and decision? Automatic devices and instruments are used extensively in some industries, but many others have yet to take full advantage of these great discoveries. The petroleum industry has been a leader in using automatic controls-some refineries are almost completely controlled by automatic devices. The field of geophysics is entirely dependent on instruments and has progressed at almost exactly the same rate as improvements in instrumentation. In metallurgy and mineral dressing use of instrumentation is increasing very rapidly. Mining engineers throughout the country are beginning to think in terms of instruments and controls.

Jan 3, 1958

By Donald F. Saunders

Means and relative standard deviations were calculated for eU, eTh, K, and their ratios for aerial gamma-ray spectral data in 29 quadrangles at 1:250,000 scale. Known or suspected uraniferous provinces were characterized by: 1) Higher eU, eTh, and K means (due to generally higher radioelement concentrations); 2) Higher relative standard deviations for eU, eU/eTh, and eU/K (reflecting the presence of local uranium enrichments); and lower mean eU/eTh and eU/K values (showing uranium loss from "average" rocks to form local enrichments). "Uranium favorability indexes," i.e., combinations of the sensitive variables, show an excellent qualitative relationship to known occurences and geologic favorability. Results appear to confirm the existence of long-term crustal uranium provinces formed at the time of emplacement of the oldest known rocks.

Jan 1, 1980

By R. V. Wheeler, W. Francis

Of the methods that have been used for studying the chemical composition of coal, attack by reagents has not, in general, yielded much information. Most of the reagents used have been strong oxidants such as nitric acid or Schulze's solution. The use of a milder oxidizing agent, such as air at low temperatures, enables progressive changes in the character af the coal substance to be studied and thus helps toward an understanding of its constitution. British bituminous coals frequently have a banded structure. These bands (of four types) can be separated one from another and have been found to possess markedly different chemical characteristics, even when taken from contiguous portions of the same lump coal. It has been found convenient to give each of the ingredients of banded coal a distinctive name, more or less descriptive of its appearance, and the study of the chemistry of bituminous "coal" in England has resolved itself into a study of each ingredient separately. The coal chosen for this work was taken from the Top Hard seam at East Kirkby colliery, Nottinghamshire, a detailed chemical analysis of which has been recorded by Baranov and Francis.' The banded structure was well marked and the bands could readily be separated. The research was confined to the brilliant vitreous bands (vitrain), the dull hard bands (durain) and the "sooty partings" main); for previous work had shown that the fourth type, to which the name clarain has been given, is intermediate in character, chemically, between vitrain and durain. The method of experiment was, briefly, to draw a slow current of moist air through weighed samples (50 gm.) of the three ingredients, vitrain, durain, and fusain, in the form of powder (through a 60-mesh and on a 90-mesh sieve) contained in glass tubes which could be maintained at a constant temperature during prolonged periods. After passing through the coal, the air bubbled into a measured volume of

Jan 1, 1925

Discussion of the paper of W. C. PHALEN, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 93, September, 1914, pp. 2249 to 2265. DAVID T. DAY, Washington, D. C.-Consider the United States broadly and the distribution of the salt industry. Think of the old solar-evaporation process up in New York State, then of the more recent processes in Michigan and Kansas and Louisiana, where the rock salt furnishes a large industry, then of the solar-evaporation process at Salt Lake, then turn to the crucial place in the United States, where there is an embarrassment of salt, and that is California. I am not forgetting' the immense body of salt east of that in the Virgin River country of Utah; but in California the situation is interesting. There are very large quantities of salt in the Searles Marsh region; again, in Southern California, at the southern end of Death Valley, there are two or three mountains of salt which have been explored recently, where the salt is sufficiently pure to be used at once. There is also a large deposit of gypsum, and it would be possible there, by extremely cheap means, to produce an amount of salt sufficient to furnish the United States' greatest needs. The principal reason that capital has been deterred from developing such a large mass is not the fact that solar evaporation produces a great deal of salt around San Francisco, but the fact that if potash salt is to be produced in connection with the salt in the borax region a, great deal of ordinary salt must be disposed of. It cannot be dumped, for it would get back into the brine again; the first rains would bring that salt back into solution again. It must be sold, given away, or hauled to a distance, which would mean a considerable freight charge. The salt will be going begging. E. G. SPILSBURY, New York, N. Y.-The remark of Dr. Day's regarding the likelihood of the production of a large amount of waste salt brings to my mind the condition that obtains in Germany in all of the potash fields. In Germany salt is a government monopoly. In the development of the potash deposits, it becomes a grave question as to how much salt they may be allowed to extract and bring to the surface.

Jan 4, 1915

By Max Y. Seaton

The scope of this paper will be limited to finished materials that contain a large preponderance (around 80 per cent or more) of magnesium oxide. The large and commercially important production of refractory dolomite and modified dolomites is not discussed here, and the production of magnesium basic carbonate for use as a heat insulator is barely mentioned. The discussion is confined mainly to magnesias produced in comparatively great quantity by direct processing of naturally occurring raw materials and hence excludes secondary or highly purified products such as pharmaceutical products or U.S.P. light and heavy calcined magnesias of commerce. Nomenclature The nomenclature of the magnesia products that will be discussed is somewhat confusing, in that it is customary in the trade to designate as "calcined magnesite" the materials that result from the calcining of magnesite to temperatures that remove the contained carbon dioxide. The finished product, therefore, is not magnesite at ali but simply a more or less pure magnesium oxide or magnesia. Furthermore, partly for statistical .and partly for commercial reasons, it has been customary, during recent years, to classify as "calcined magnesite" products that result from the heat-treatmerit of magnesium hydroxide precipitated from magnesium-containing brines; prod- ucts that, obviously, have no relationship whatever to magnesite. In the listing of magnesia-containing materials, tonnages of which are regularly reported by the Bureau of Mines, reports ordinarily are made under two headings: "caustic calcined" magnesite, in which all of the varieties of products treated at relatively low temperatures are lumped; and "dead-burned" magnesite, in which are included both high-purity and low-purity, and particularly both high-iron and irow-iron, materials that have been so heat-treated that the magnesium oxide occurs predominantly as crystalline periclase— materials used almost entirely for refractory purposes. In 1940 the apparent domestic consumption of "caustic calcined" magnesite was approximatcly 17,000 tons, "bout 95 Per cent of which was produced in this country. The apparent consumption of "dead-burned" magnesite was approximately 172,000 tons, some 82 per cent of which was domestically produced. In both total quantity and percentage of material produced within the United States, these figures are record highs for manY Years past. Utilization As indicated by these figures, the major tonnage outlet for magnesia is the refractories industry, in which magnesia is employed principally in three ways: (1) as dead-burned grain magnesite for the construction and maintenance of the hearths Or bottomS of basic open-hearth furnaces; (2) in the form of refractory magnesite bricks and shapes; and (3) as a chemical

Jan 1, 1942

By Max Y. Seaton

The scope of this paper will be limited to finished materials that contain a large preponderance (around 80 per cent or more) of magnesium oxide. The large and commercially important production of refractory dolomite and modified dolomites is not discussed here, and the production of magnesium basic carbonate for use as a heat insulator is barely mentioned. The discussion is confined mainly to magnesias produced in comparatively great quantity by direct processing of naturally occurring raw materials and hence excludes secondary or highly purified products such as pharmaceutical products or U.S.P. light and heavy calcined magnesias of commerce. Nomenclature The nomenclature of the magnesia products that will be discussed is somewhat confusing, in that it is customary in the trade to designate as "calcined magnesite" the materials that result from the calcining of magnesite to temperatures that remove the contained carbon dioxide. The finished product, therefore, is not magnesite at ali but simply a more or less pure magnesium oxide or magnesia. Furthermore, partly for statistical .and partly for commercial reasons, it has been customary, during recent years, to classify as "calcined magnesite" products that result from the heat-treatmerit of magnesium hydroxide precipitated from magnesium-containing brines; prod- ucts that, obviously, have no relationship whatever to magnesite. In the listing of magnesia-containing materials, tonnages of which are regularly reported by the Bureau of Mines, reports ordinarily are made under two headings: "caustic calcined" magnesite, in which all of the varieties of products treated at relatively low temperatures are lumped; and "dead-burned" magnesite, in which are included both high-purity and low-purity, and particularly both high-iron and irow-iron, materials that have been so heat-treated that the magnesium oxide occurs predominantly as crystalline periclase— materials used almost entirely for refractory purposes. In 1940 the apparent domestic consumption of "caustic calcined" magnesite was approximatcly 17,000 tons, "bout 95 Per cent of which was produced in this country. The apparent consumption of "dead-burned" magnesite was approximately 172,000 tons, some 82 per cent of which was domestically produced. In both total quantity and percentage of material produced within the United States, these figures are record highs for manY Years past. Utilization As indicated by these figures, the major tonnage outlet for magnesia is the refractories industry, in which magnesia is employed principally in three ways: (1) as dead-burned grain magnesite for the construction and maintenance of the hearths Or bottomS of basic open-hearth furnaces; (2) in the form of refractory magnesite bricks and shapes; and (3) as a chemical

Jan 1, 1942

By W. C. Coffin

The refractory linings of open-hearth steel furnaces above the bath line are subject to severe wear not only from the heat caused by the combustion of the fuel and the reactions of the bath, but also from the melting action of the gases when not controlled and directed, and from the scouring of the oxides, etc. with which the products of combustion are charged. The framework that encases or binds the furnace is made up primarily of an iron or steel pan in which the furnace proper is built, side and end buckstays, and tie-rods. The expansion and contraction are so great and variable that the bindings may be subjected to severe stresses unless the tie-rods are carefully adjusted in heating up the furnace, but they are most affected by direct heat and usually become deformed from that cause when the lining is worn thin and, sometimes, when sections of the lining fall in and expose some of the framework. A deformed framework displaces the skewback of the roof arch and tends to distort or crush the roof. Bent buckstays deform the front wall, causing the door frames to stand away from the lining so that the gases burn between the lining and the frames, destroying both of them. Frequently the frames are attached to the buckstays; then when the latter bend the frames usually break. Preventing the distortion of the framework and maintaining the economy of the refractories are real factors in the cost of steel making. Nat only does the cost of general repairs and reconstruction add directly to the cost of steel produced, but the time lost in making repairs cuts down the steel production and increases the overhead expense of both the furnace shop and its allied foundry or mills. Many years ago water-cooled equipment applied to iron blast furnaces made it possible to increase greatly not only the size and production of the furnaces but also the life of the lining. It also cut down the loss from frequent repairs. The open-hearth furnace is a much later invention, especially as a commercial factor; for though it dates from the Fred Siemens patent of 1856, much more progress was made in the Bessemer process until the latter eighties and most of the development

Jan 1, 1920

IN this survey of the progressive development of education for the mineral industries throughout the United States, the review of the history of each school has usually been completed wherever it is first mentioned, but the history of the schools in the cities of the eastern seaboard was not carried beyond 1870. It is necessary now to cover what happened during the period of approximately the last quarter of the nineteenth century in several of the schools in the east. PHILADELPHIA Of Philadelphia, it has been related in chapter 4 that the Polytechnic College of Pennsylvania began offering a curriculum leading to the B.S. in mining in 1853; that the school did not prosper, and finally closed about 1890. The establishment of a Department of Mining, Arts, and Manufactures at the University of Pennsylvania in 1855-56 was also mentioned, but its history was not carried beyond 1860. In 1859 J. Peter Lesley was appointed professor of mining in the University of Pennsylvania. The son of a cabinetmaker, born in Philadelphia Sept. 17, 1819, he had taken his A.B. degree at the University of Pennsylvania in 1838 and then secured a position on the Geological Survey of Pennsylvania under H. D. Rogers. When the Survey was discontinued, in 1841, he went to Princeton to study theology, was ordained a Presbyterian minister and followed that career until 1853, when the Pennsylvania Geological Survey was again started and he rejoined its staff. He published "A Manual of Coal and its Topography" in 1856, and studied at the École des Mines, Paris, in 1850-57. He published an 800-page "Iron Manufactures Guide" the year that he was appointed to the staff at the University of Pennsylvania. In 1863-64 a College of Agriculture, Mines, Arts and the Mechanic Arts was established, but it was not a separate school

Jan 1, 1941

By William Lodding

In leaching ores at atmospheric pressure it is often desirable to apply high reagent concentration, long exposure time, and elevated temperature. All of these conditions tend to increase the treatment cost. In conventional leaching, direct or countercurrent, the leaching fluid is needed to transport the solids through the process. This requires relatively large volumes of fluid and limits the reagent concentration economically feasible. The relatively high dilution also increases fuel cost if leaching is to be done above ambient temperature. Heating of water is expensive.

Jan 3, 1967

By Carl E. Swartz

In the course of a recent investigation1 to develop a more satisfactory white-metal bearing alloy, a number of alloy systems were studied. The cadmium-nickel system showed characteristics desirable in a bearing alloy, and the system was therefore studied in some detail. Experimental Method Alloying cadmium with nickel offered no serious difficulty. After melting the cadmium, clean sheet nickel was added while the temperature was maintained at 500" to 600" C. A few crystals of ammonium chloride2 served to clean the nickel when the latter did not "wet" readily. In preparing the individual alloys for thermal and microscopic investigation, a "hardener" containing about 10 per cent nickel was used. Thermal Experiments and Apparatus Time-temperature cooling curves were made by standard methods. Globe electrolytic cadmium was added to the hardener to make a melt of the desired composition weighing between 100 and 200 grams. This charge was placed in a Pyrex test tube, 1 by 10 in., closed with a rubber stopper carrying a thermocouple sheath and quartz stirring rod. The assembly was lowered to a depth of about 4½ in. into an electric resistance pot furnace containing a No. 0000 clay-graphite crucible (to catch the melt in case of a break in the test tube). After the tube was clamped in this position, an asbestos-magnesia mixture was loosely packed in the furnace around the tube and a "halved" cover of transite placed on top. This left at least 5 in. of the test tube protruding from the furnace. When the alloy had melted, the thermocouple was adjusted so that the hot junction was l! in. from the bottom of the test tube. The melt was stirred thoroughly for several minutes to insure composition homogeneity and absence of thermal gradients.

Jan 1, 1934

By Paul D. Merica, L. J. Gurevich

In connection with other investigations on the properties and characteristics of chilled-iron car wheels, the question as to the best range of annealing temperatures was raised. Chilled-iron wheels are cast with a chill against the tread and the inside of the flange, the remainder being in sand. The composition of the metal is so chosen that under these conditions the trcad and inside of the flange will show white iron to a depth of from 5/8 to in. (15 to 22 mm.), the remainder of the wheel becoming graph itized or gray. In order to relieve the stresses set up during cooling under such drastic conditions, the wheels are stripped from the mold, while still red hot, piled in a soaking pit, and allowed to cool very slowly from their temperature at stripping. Obviously the most suitable temperature for this annealing is the highest at which no formation of graphite occurs within the white tread and at which the wheels can be stripped from the molds. Inasmuch as no direct determinations have been made of the temperatures at which the formation of graphite takes place in white iron of compositions used in car wheels upon annealing, it was considered worth while to determine these temperatures as a means of establishing the maximum temperatures at which the annealing of the wheels may be carried out. In the course of this work, some incidental observations were made which are of interest in connection with the theory of graphitization in whitc iron. The literature on the subject of the formation of graphite both during cooling at casting and upon annealing is very extensive and can be best studied by reference to a comprehensive discussion of the subject by Hatfie1d.l Perhaps the most important contributions of previous investigation are the following: 1. Whether a given mass of molten iron becomes white, mottled, or gay upon casting, depends on its composition and its rate of cooling through the temperature range of solidification and immediately below. 2. The more rapid the rate of cooling, the less is the extent of graphitization.

Jan 1, 1920

AIME 1953 DIRECTORY SUPPLEMENT OFFICERS AND COMMITTEES OF LOCAL SECTION; COUNCIL OF SECTION DELEGATES Linwood Thiessen, Chairman H. D. Vaughan, Vice-Chairman John H. Melvin, Secretary EXECUTIVE COMMITTEE L. E. Thelin, Connecticut J. B. Cunningham, Arizona W. L. Penick, San Francisco G. L. Yates, Kansas DELEGATES Adirondack - C. DeWitt Smith '54 Alaska - Robert 11. Chapman, ?54 Arizona J. B. Cunningham, '53 Black Hills - Sidney M. Runke, '54 Boston -R'. Schuhmann, Jr. ?54 Carlsbad Potash - W. P. Wilson, '54 Central Appalachian - Charles T. Holland, '54 Chicago - H. A. White, '54 Cleveland - Milton Tilley, '54 Colorado - J. Paul Harrison '54 Columbia - Harold Kirkemo, '54 Connecticut - Lewis E. Thelin, ?53 Dallas - Kenneth F. Anderson, '54 Delta - Roy S. Sullins '54 Detroit - F. P. Bens, '53 East Texas - Joseph A. Morris, '54 El Paso Metals - E. M. Thomas, '54 Florida - W. O. McClintock '54 Fort Worth - Ray Elner, '51 Gulf Coast - H. E. Treichler, '53 Kansas - G. L. Yates, '53 Lehigh Valley - H. R. Gault '54 Lima, Peru - R. P. Koenig, ?54 Lou-Ark - A. H. Crawford. '53 Mexico - W. G. Kane, '54 Mid-Continent - J. H. Beesley, '53 Minnesota - J. R. Stuart, '54 Montana - F. W. Strandberg, '53 Nevada - Albert Silver,'53 New York - P. Malozemoff, '54 North Pacific - A. H. Mellish, '54 North Texas - K. F. Anderson, '54 Chio Valley - J. H. Melvin, ?53 Oklahoma City - Charles Miller, '53 Oregon - T. C. Matthews, '54 Penn. Anthracite - D. C. Helms, '54

Jan 1, 1953

By George E. Aiken

Subzero temperatures of the Arctic pose some critical engineering problems for the developer and operator of open pit mines. Undoubtedly, the single most troublesome manifestation of this climate is permafrost. Underlying about 20% of the world's land area and 85% of the state of Alaska, permafrost has not only made its impact on building construction and mine excavation, but has created a legitimate threat to the delicate balance of nature existing within the Arctic environment. The recognition of permafrost areas by geomorphology and an understanding of its other complex developmental factors are the basis for two major concepts in building construction. The active method involves the eventual thawing of the complete permafrost section and is only useful in shallow areas. However, in some areas of coarse, well-drained material, vegetation may be stripped well ahead of construction and shallow permafrost allowed to method, leaves the perenially frozen ground undisturbed and is to be preferred. In selecting construction sites aerial photos may clearly reveal typical permafrost features.

Jan 5, 1972

By D. K. Crampton

NEARLY everyone who has not had the benefit of study in the field of metallurgy subscribes to a persistent and enthusiastic belief in the legendary lost art of hardening copper. This of course supplies a perfect introduction to a chapter of information on copper and its alloys, since the dissipation of fallacies and superstitions affecting an art probably constitutes the best method of getting at its real substance. Metals are hardened, but also embrittled, by a plurality of impurities. In the modern technology of copper-base metal products, we are familiar with a great host of materials, passing from one extreme of dead soft copper better than 99.9 pct pure, which in the form of wire about as thick as a match will stand hundreds of full twists in a 12-in. length, to an alloy containing less than 3 pct of alloyed substance possessing the strength of pretty good steel and capable of manufacture into razor blades, should we suddenly be deprived of steel; certainly a much better material for this purpose. Every copper alloy known to primitive man lies in some inter- mediate position and the ancient bronzes that have been found all over the world wherever an early civilization existed are usually contaminated by such impurities as sulfur, oxygen, antimony, arsenic, iron, or other materials, so that they could not possibly conform to any modern intelligent specification insuring the best combination of useful properties in alloys of their type and would go

Jan 1, 1953