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By William B. Plank

ENROLMENT data given in this report of the seventh study of the schools by the Mineral Industry Education Division reveals the critical situation in the mineral engineering schools of the United States. Complete figures for the year 1942-43 show that at that time, about one year after Pearl Harbor, the enrollment of mineral engineers was 6385 or 30 per cent less than in 199441. By October 1943, however, enrollment had dropped to 2050, as reported in the Journal of Engineering Education of January 1944. This was a further reduction of 68 per cent in one year, or 77 per cent in three years. With accelerated programs in effect during the current year, with many graduations since last October, and with the military forces taking practically all the high school graduates, the present enrollment is, of course, much lower than the 2050 above given. There are no late data on the exact situation. In Canada, the same situation exists in the mineral engineering schools, only

Jan 1, 1944

US 4,152,143-Continuous precipitation of cement copper from an aqueous ore leach solution mixed with pieces of iron as the precipitant Copper depositing on the pieces of iron is loosened and removed therefrom by means of constant but regulated oscillating movement of the pieces of iron in a horizontal elongated chamber, and the loosened copper is separated and collected from the mixture E Kausel and R Nissen, assigned to Klockner-Humboldt-Deutz A G May 1, 1979 8 pp (75-100) Filed 1-12-78 (868,981) (Drawings below) [ ] US 4,156,711-Removal of metal impurities from an acidic zinc or cadmium solution prior to electrolysis. Impurities such as manganese, cobalt, nickel, and thallium are selectively precipitated by contacting the solution with persulfuric acid or an ammonium or alkali metal salt thereof while maintaining a pH value of from 1 5 to 4 5 This patent is a continuation-in-

Jan 1, 1980

By A. J. Williams

THE province of Saskatchewan, situated in the center of the Great Plains region of Canada, has, like most prairie areas, an essentially agricultural economy. Most of its population of about 860,000 is located in the southern half of the province in the farming and ranching areas. To the north of the prairie is a broad forested belt supporting a considerable timbering industry, and the northern one third of the province is glaciated pre-Cambrian rock formation. This latter area is, relatively barren of vegetation, but the presence within it of a considerable variety of radioactive, noble and base metals, and industrial minerals has been shown by prospecting in recent years.1 Glacial Geology The Keewatin ice sheet, considered to have accumulated in the country to the west of Hudson Bay in Pleistocene time, covered at its maximum advancement almost all of Saskatchewan and extended south of the international boundary. Only in the Cypress Hills in the southwest and around Wood Mountain in the south central portion of the province did the preglacial formations escape the action for this glacial period. The bedrock of the plains and forest areas therefore is overlain by moraines and modified glacial drift, which vary in thickness from a few feet to 400 or 500 ft.2 Glacial action in the pre-Cambrian area of the province was largely erosional, most of the more recent formations and some of the pre-Cambrian rock being transported out of the area to the south and west. It has been estimated that about 13 pct of this area is composed of lakes and rivers not too adaptable to rail or water transportation, so that until the use of aviation for exploration purposes became general; development of the area was slow. To the south, the heavy. mantle of glacial drift has to some extent deterred the discovery of industrial minerals in the bedrock underlying the forest and prairie regions.3 At the same time, this drift contains numerous deposits of those most elementary and necessary industrial minerals, sand and gravel. Sedimentary Basin The major feature of the sedimentary deposits underlying the plains regions is the basinal structure known as the Moose Jaw syncline, which runs from the southeast corner of the province in a northwesterly direction. To the west. of this syncline the formations curve upward, then have been faulted and further upthrust to appear at the surface in the foothills of-the Rockies in Alberta; to the east and north they curve upward into Manitoba and northern Saskatchewan, but the surface contacts are covered mostly with glacial drift.2,3 The axis of the syncline dips to thee southeast, so that there is also an upward trend of the formations along the axis to the northwest. In illustration of the regional structure underlying the province, the pre-Cambrian basement has been logged in drillholes at the following depths in several locations: Ogema (south central), 9390 ft; Gronlid (northeast), 2599 ft; Vera (northwest), 4422 ft; Big River (north northwest), 2348 ft. Fig. 1 indicates the general surface geology of the province, ignoring such glacial overburden as may overlie many of the bedrock formations. Also indicated is the approximate location of the axis of the Moose Jaw syncline.4 Industrial Minerals Clays: The province is fortunate in possessing a widespread distribution of clays of ceramic value, ranging from those used for heavy structural products to the high grade pottery and china clays. Shales suitable for brick and tile production are found in the Upper Cretaceous and Tertiary formations across the south of the province where the glacial drift is thin or nonexistent. Many deposits of glacial lake clays suitable for such wares are found scattered over the rest of the province south of the pre-Cambrian area. The Whitemud formation of the Upper Cretaceous is a narrow sedimentary, band of secondary clays found intermittently, at points, across the, south of the province where glacial action did not disturb or remove them.8 In the southwest corner of the province, around Eastend in the Frenchman River valley, the refractory clays of this formation are contaminated somewhat with iron compounds or other alteration products of basaltic rocks. This eliminates the use of those clays in true whitewares, as they fire to creamy buff shades at the lower temperatures and to a blue-specked grey at cone 8 to 12, (2280°F to. 2390°F), the range commonly used in firing whiteware. However, for use in the production of colored artware, caneware, stoneware or crockery, and sewerpipe, this type of clay makes an excellent body that requires little or no addition of flint, feldspar, or other fluxing materials such as are required in the higher class of ware.9 It is not a grade of clay that can be shipped great distances to the manufacturing centers, but a market for considerable tonnages has developed at nearby Medicine Hat, where cheap natural gas is available for the firing of the ware. Farther east in the south central portion of the province, the clays of the Whitemud formation are generally more refractory and white burning. The formation is divided into three zones, consisting of white clays, brown shale, and white sandy clays.

Jan 1, 1952

The separate outputs of Burma and India in 1937 were 274,664,365 gal. valued at £4,474,147 and 75,657,857 gal. valued at £1,030,591, respectively. The corresponding figures for the year 1938 were 263,823,-265 gal. valued at £3,766,810 and 87,082,371 gal. valued at £1,234,563, respectively, which is a slight increase in total quantities but a fall in value for the combined outputs of Burma and India. The appreciable increase from India in 1938 is due to an increase of over 11 million gallons from Attock and a little from Digboi, while the decrease from Burma is due to a fall of nearly 9 million gallons from Yenangyaung, over 3 million gallons from Yenangyat (and Lanywa) and half a million gallons from Minbu (Table 1). The 'amount' of gasoline produced from natural gas during the year 1938 was 10,587,291 gal. in Burma and 496,163 gal. in the Punjab.

Jan 1, 1940

The separate outputs of Burma and India in 1937 were 274,664,365 gal. valued at £4,474,147 and 75,657,857 gal. valued at £1,030,591, respectively. The corresponding figures for the year 1938 were 263,823,-265 gal. valued at £3,766,810 and 87,082,371 gal. valued at £1,234,563, respectively, which is a slight increase in total quantities but a fall in value for the combined outputs of Burma and India. The appreciable increase from India in 1938 is due to an increase of over 11 million gallons from Attock and a little from Digboi, while the decrease from Burma is due to a fall of nearly 9 million gallons from Yenangyaung, over 3 million gallons from Yenangyat (and Lanywa) and half a million gallons from Minbu (Table 1). The 'amount' of gasoline produced from natural gas during the year 1938 was 10,587,291 gal. in Burma and 496,163 gal. in the Punjab.

Jan 1, 1940

By Frank A. Crossley

The work described has one serious shortcoming: grain size was not monitored during heat up to the temperature (1675°F) of isothermal anneal. The chief obstacles to p grain growth in titanium a-ß structures are the a grains. Heating a structure such as that shown in Fig. 1 to a temperature close to ß transus causes dissolution of a grains in order to adjust the a/ß ratio, compare Figs. 1 and 2. During this process there is a concomitant growth of the ß grains—otherwise ß grains would have to be nucleated in order to adjust the a/ß ratio. When the annealing temperature is reached the a/ß ratio stabilizes and this initial phase of ß grain growth ceases. After an incubation period growth resumes as described. Some 0 grain boundaries can be clearly seen in Fig. 1. (Skilled metallography commonly produces photomicrographs which show more structural detail than direct observation.) These boundaries suggest that the average ß grain size is approximately 0.002

Jan 1, 1970

By R. S. Handy

The No. 2 unit of the West Mill of the Bunker Hill & Sullivan Mining & Concentrating Co., which went into commission Apr. 17, 1912, is structurally a twin of the No. 1 unit, which was started Nov. 9, 1909. Up to the point where the ore enters the concentrating-de-partment, it follows precisely the process described by G. Cae-tani in his article entitled, Milling of Lead-Silver Ores,' under the heading, Preparation of the Mill-Ore. The process from this point forward, in the No. 2 section, is outlined on the accompanying flow-sheet. In describing it I shall attempt to analyze the products of each separate process. The constancy of the tonnage and the uniformity of the quality of the feed render this practicable. No. 1.—550 tons of feed, all having passed 30 mm., is washed into two 15-mm. trommels, 4 ft, in diameter, 60 in. long, 17 rev. per min., 1 in. slope, 3/8-in. gauge steel.

Jan 1, 1913

By C. H. Benedict

Largest and most important of the milling plants under construction during the year is the Morenci plant of the Phelps Dodge Corp., in Arizona, where plans are being rushed for production in 1942. Grate mills will be used for fine-grinding, and in the pilot plant, classifiers of the spiral type have the preference for the closed- circuit work. The flotation units will be chiefly of the pneumatic type, with some mechanical units as auxiliaries. The Fagergren, Pan American, and Agitair machines were left in the competition as the year closed. If the absence of European markets for finished products has dislocated the mining industry, fortunately the lack of raw materials required in the beneficiation of ores has not been serious. except possibly as to the inability to import flint grinding pebbles. Some of the less important gold mines still use pebbles for grinding as is also the practice in the comminution of nonmetallics used in various industries. T the Calumet & Hecla in the Lake A Superior copper district pebbles have been used exclusively in open- circuit grinding in the Hardinge mills treating the

Jan 1, 1941

By E. H. Sellards

ON Oct. 9, 1929, a sink formed in the Sour Lake salt dome oil field in Texas, and on Oct. 12 a second smaller sink formed at the north margin of the first. The purpose of this paper is to give such observations as it has been possible to make on the earth movement incident to this subsidence. Sour Lake salt dome is typical of the salt domes of the Gulf Coastal Plain of Texas. Structurally the dome is a plug of salt which rises to within 900 ft. or less of the surface. Above the salt is a cap rock consisting of anhydrite with more or less calcium carbonate. The salt plug, as contoured on the cap rock, is circular in outline with, however, some appreciable irregularities. Overlying the cap rock are relatively uncompacted sediments consisting of sand, clay and gumbo.. At the crest of the dome these deposits are no more than 700 or 800 ft. thick. However, the sides of the dome are steep, and the sediments thicken rapidly away from the crest. The sink formed about 1500 ft. northeast of the crest of the dome where the sediments overlying the cap rock are from 1000 to 1200 ft. thick. The cavity permitting the subsidence was quite certainly either in the cap rock or in the salt below the cap rock, so that the sink was formed by the caving of as much as 1000 or 1200 ft. of earth.

Jan 1, 1930

By L. D. Ricketts

AN older man looks back, perhaps wistfully, on a long and rather active experience, and possibly a popular and brief glimpse of some contrast between past and present may hold your attention for a few brief moments and prove useful. In the late nineties an engineer was .called on to de- sign and build two copper ore concentrating mills of 400 tons average daily capacity. There were larger mills than this at Washoe and elsewhere, but a 400 ton' mill was a large one as mills went over thirty years ago, and one might say a large mill of those days could crush a ton of copper ore in 216 seconds. In the mills I refer to steel construction and the conveying belts were introduced into the copper industry and rein- forced concrete came shortly after. Since then we in the West have ever been faced with a constantly de- creasing tenor in the grade of our copper ores and a constantly increasing demand for our product, and we have therefore been obliged to call for far larger castings and finished machines than were formerly used. The mechanical engineer has also enabled us to accomplish notable economies in power generation and distribution. Ore handling and crushing have been simplified and through the introduction of reagents to induce physical or chemical reactions, or both, our older methods have been vastly improved or even supplanted by new and better ones and our recoveries greatly improved.

Jan 1, 1929

By Warren T. Smith

The Phelps Dodge Corp. Lavender pit is located in the Bisbee mining district near the town of Lowell, Ariz. A quartz monzonite porphyry exists as an intrusive stock and was the source of mineralization for the limestone replacement orebodies being mined by underground methods. Leaching of the upper portion of the stock, and precipitation of the copper as chalcocite on the finely dispersed un- oxidized pyrite in the monzonite porphyry, formed a low grade ore zone below a leached capping varying from 50 to 300 ft thick. Churn drilling starting in 1916 and supplemental churn drilling begun early in 1950 indicated a mineable area about 3100 ft long by 2400 ft wide. In general drilling was on 100-ft centers. The pit was planned with 50-ft benches and wall slopes varying from 1 to 1 to a flatter slope of 1 1/3 to 1 dependent on the character of the ground. Materials within the pit limits, using a 0.6 pct minimum grade cutoff, were estimated at 41 million tons of 1.14 pct copper ore, 31 million tons of low grade sulfides suitable for leaching with an average grade of 0.42 pct, and 70 million tons of waste.

May 1, 1956

By GUY C. RIDDELL

THE recent purchase by an American investment trust of a substantial block of shares in a British owned Venezuelan copper operation directs attention to mining activities that have been quietly gaining momentum in that country for a number of years. We hear so much of oil work in Venezuela that attention to its metal-mining activities is in most quarters casual. In gold and copper the country has made some interesting mining records, and two of the old districts are ,digging in for a come-back. Copper Copper production centers in the state of Yaracuy. The Aroa-Cumaragua mining region has had a long and eventful history. The Aroa mine itself, 50 miles from the coast in West-Central Venezuela, was discovered in 1605. First mined in 1632, owned at one time by Simon Bolivar, it has been reopened many times and is now , the basis of substantial operations by the South American Copper Syndicate, Ltd. of London. The latter has operated the property profitably, off and on, for a number of years, paying heavy dividends on a small investment-at times over 300 per cent annually.

Jan 1, 1929

By W. Armstrong Price

INVESTIGATION by German chemists during the World War showed that particles of iron oxide form rapidly in iron pipes carrying hydrogen gas under pressure when the gas contains small amounts of water. Under these conditions, the gas frequently exploded when expanding into a dirigible. The explanation of the explosions lies in the building up of a charge of static electricity in the flow just beyond the orifice and the ignition of the gas by a spark accompanying discharge of the electricity. Friction between the moving particles and the pipe generated the electric charge, which was manifested by a pale blue glow formed in the flow at pressures above two atmospheres. In one experiment, this glow, at eighty atmospheres, extended for a distance of forty to fifty centimetres, but did not ignite hydrogen and air mixtures until the charge was col-lected by a conductor and discharged across a gap between electrodes placed at the side of the column of gas. Autoignition did not occur when this discharge was effected at a distance from the gas column, nor if the gas used was thoroughly dried and free from impurities. The electric charge has been studied by placing various wire and screen conductors in the outcoming stream of gas, Guest having summarized these experiments. The application of these conclusions to fires in petroleum and natural gas issuing uncontrolled from wells is made in the following paper, citing the ignition of a wild gas well in Texas.

Jan 1, 1936

By AIME AIME

AT A meeting of the Boston Local Section of the Institute, on Oct. 3, approval was voted to the work done by its representatives on the Committee opposing the passage of a bill by the, Massachusetts Legislature to license engineers. The report is as follows: The Joint Committee on Licensing of Engineers, which included a Committee of the Boston Society of Civil Engineers and representatives of seven other societies,* submitted to the members of the respective societies, on Jan. 8, 1921, a report in which it was stated that on Jan. 4, 1921, a petition was filed in the Legislature of Massachusetts by the Boston Chapter of the American Association of Engineers accompanied by a bill to provide for the registration of professional engineers and land surveyors. This report also stated that at a meeting of this committee, held on Jan. 7, 1921, it was voted:

Jan 1, 1921

By R. M. N. Pelloux

This study of aluminum-copper alloys had two aims: 1) To determine the effect of the amount and distribution of a second phase, CuAl2, on the creep-rupture strength, ductility, and fracture characteristics of the alloys. The work of Gemmell and grant' on single-phase aluminum-copper alloys provided a basis for the present study. 2) To attempt to provide a relation between the microstructure and strength of two-phase alloys deformed at comparatively high temperatures (greater than 0.45 T,). The creep behavior of the two-phase magnesium alloys Mg;Ce and Mg-A1, has been treated by Roberts. 9 In work reported by Sully and Hardy4 and by Underwood, Marsh, and Manning~ on A1-Cu two-phase alloys, and also in a portion of the work of Gemmell and grant,' aging took place during the creep tests. 'In the present work, overaged aluminum-copper alloys were subjected to creep deformation at two temperatures, 500 and 700OF. The overaging treatments to produce the precipitate dispersions were performed prior to the test, at temperatures which were the same as the ultimate respective test temperatures. Hence, the present study is concerned with the creep behavior of stable (in contrast to "underaged") two-phase A1-Cu alloys, i.e., alloys in which no depletion of the solid-solution matrix occurred during: creep. MATERIALS AND PROCEDURE A 2 and a 3 pct Cu alloy, supplied by Alcoa, were studied; Table I shows the compositions. The grain size of the specimens, 0.9 to 1.0 mm, was achieved by annealing the machined test bars for 2 hr at 1000°F, followed by furnace-cooling to 900°F, and homogenizing for 4 hr. Both compositions are in the single-phase condition at 900°F. Two types of overaged dispersions, termed "over-aged I" and "overaged 11" were prepared after the grain size and the homogenization anneals. The overaged I alloys were prepared by quenching to room temperature after homogenization, aging at either 500' or 700°F for 72 hr, and air-cooling to room temperature. The overaged I1 alloys were prepared by furnace-cooling after homogenization, to either 500' or 700°F, and holding at the necessary temperature for 72 hr. The times for furnace-cooling from 900°F to 700° and 500°F were, respectively, about 2 and 3.5 hr. The structures of the A1-2 pct Cu alloys are shown in Fig. 1 (overaged I) and in Fig. 2 (overaged 11). A comparison of Figs. 1 and 2 shows that in the overaged I alloys the precipitate particles along the grain boundaries are much more closely spaced and the grain boundaries are straighter than they are in the overaged I1 alloys. Further, the particle size and spacing in the grains are smaller than in the overaged I1 alloys. Microstructures of the A1-3 pct Cu alloys have not been shown; the structures of these alloys differed from those of the A1-2 pct Cu alloys only in that the distribution density of the particles was greater. The creep specimens had a gage section 1 in. long with a diameter of 0.155 to 0.195 in. Before testing, specimens were electropolished in a solution of 100 cc glacial acetic acid, and 30 cc of 60 pct perchloric acid, at 40' to 50°F, at 24 v. The specimens were kept refrigerated prior to testing to avoid precipitation at room temperature. Constant stress creep tests were conducted; the load was applied 75 min after heating of the specimens to test temperature had begun. EXPERIMENTAL RESULTS Creep-Rupture—Fig. 3 shows the log stress-log rupture life plotfor the overaged alloys studied, and also for the underaged A1-2 pct Cu alloy.' At 700°F, the stress-rupture life relationship is nearly independent of both the amount of precipitate (i.e., composition) and of the type of overaging treatment (i.e., precipitate dispersion). At 500°F it is apparent that the increase in rupture life that was ex-

Jan 1, 1960

By Joseph E. Pogue

NEW economic forces are at work in the petroleum industry.. In order to visualize these forces and clearly see their bearing on the producer, refiner and marketer, it is necessary to see in perspective the economic evolution of the business. For several decades prior to 1913 the outstanding feature of the petroleum industry was a trend toward integration, culminating in a huge combine, the Standard Oil Co. An important aspect of this integrative trend, however, was its concentration on the combination aid control of refining and marketing, leaving crude oil production, for the most part, to the exigencies. of small-unit competition. It is a noteworthy coincidence that during this era the law of oil and gas was formulated and applied, whereby these substances had to be reduced to possession to establish ownership; and the forces of competition in crude oil production were thereby intensified. It was to the interest of an industry, safeguarded in its control of manufacturing and markets, to have supply stimulated by legal convention as well as by individual initiative in order that the growing demand could be met without interruption. And so over-production of crude oil during this era was no handicap, but rather an aid, to the progress of the industry.

Jan 1, 1929

By Charles E. Hughes

HERBERT HOOVER had to sit through an hour and a half of eulogy of himself at Carnegie Hall last night, said the Sun and New York Herald of Feb. 19. When his turn to answer came he remarked that, although one of the speakers had referred to him as a modest man, he would never, in view of this experience, be able to prove it. The occasion was the presentation by the Civic Forum to Mr. Hoover of its medal of honor for distinguished service, the only recipients in past years having been General Goethals, Thomas A. Edison, and Alexander Graham Bell. Only by distortion of intent could there be said to be anything political in the affair, which was carefully described by the chairman, Charles E. Hughes, as non-partisan. Nevertheless, the praise bestowed on the former Food Administrator by the former Republican candidate for President, proved specially interesting to a much applauding audience which filled the hall to the uppermost gallery. A piece of real news was supplied by Horace V. Winchell, whom Mr. Hoover succeeded on Tuesday as President of the American Institute of Mining and Metallurgical Engineers. He said that Mr. Hoover, when in Europe after the . armistice, caused to be collected the literature of the war in all Europe.

Jan 1, 1920

"Butte originated as a placer mining camp. The first gold discovery was made in the year 1864, near what is now Main Street. Placer mining was vigorously prosecuted along Silver Bow Creek and in Missoula, Buffalo, Town and Parrot gulches for a period of five years, at the end of which time, in 1870, the camp was practically deserted. In the meantime, the quartz veins so prominently traceable over the hillsides were located, the first location being made by W. L. Farlin and called the Black Chief claim, and later restaked as the Travona. Reasoning from the presence of the gold placers, free-milling gold ores were eagerly looked for by the early prospectors. Claims covering the great Rainbow and other silver lodes were located in the sixties. The presence of valuable silver ores in these veins caused the staking out of many claims, believed to be valuable only for silver, but which later proved to be enormous copper producers.Treatment of these early discovered rich ores was first attempted in arrastres. Later, stamp mills were built. The Centennial dropping 10 stamps, was the first, and in 1875 Mr. Farlin built the Dexter 10-stamp mill, intro¬ducing chloridizing-roasting. More successful processes were soon introduced and several large mills built, among which were the Alice, Lexington, Silver Bow, Moulton and Bluebird, in all representing a total of 290 stamps. The silver mining industry reached its zenith in 1887 and declined rapidly in the early nineties, following the sudden drop in the price of silver in 1892.During this period of silver mining activity the business of copper mining was making rapid strides. Development of the veins, located as silver veins, had uncovered copper ore in many instances. There was great activity in ""claim staking'' in the years from 1871 to 1879, during which period most of the claims covering the present productive copper area were located."

Jan 1, 1913

By G. M. BUTLER

TWENTY-ONE of the states in the Union, the Territory of Hawaii, and seven provinces of Canada now have in operation laws requiring that professional engineers be registered or licensed. In addition, two states require that civil engineers be registered, and one other state demands registration of structural engineers. Moreover, nearly every year sees additions made to the list. The registration movement, fostered by the American Association of Engineers, now has the powerful, energetic backing of the An1,erican Society of Civil Engineers, which is itself now fostering registration legislation, and there is a strong sentiment in favor of registration in the American Institute of Electrical Engineers and the American Society of Mechanical Engineers. Only in the American Institute of Mining and Metallurgical Engineers is anti-registration sentiment, strongly dominant, but many members of this organization are enthusiastic advocates of registration.

Jan 1, 1930

By AIME AIME

THE meeting" of the Rare Minerals and Metals Committee was held Monday afternoon, Feb. 17; Donald M. Lidclell, chairman, presiding. The first paper (T. P. 279), "Progress in the Use of Tantalum," by George W. Sears, was read by Mr. Smyth. Dr. Sears' paper contains an interesting summary of the uses, alloys and ores of tantalum and a resume of present method of reduction. The uses of tantalum is based on its extreme rise to the reaction of even the strong mineral acids, its great avidity for the common gases and its capacity for transforming alternating to direct current. Tantalum, as an alloy material, has received considerable study and many alloys have been reported. Among them three types appear to .be most prominent, alloys of high melting point, hard alloys and acid rising alloys. As the estimated quantity of tantalum in the earth's crust is less than that of gold, it must be looked upon as n rare metal. Australia is the greatest producer and the Black Hills of South Dakota produce minor amounts. As the one type of mineral available contains both tantalum and columbium, the extracting and metallurgy of tantalum are difficult chemical processes. Greater simplicity in this and the development of a market for columbium would undoubtedly be of great benefit to the tantalum industry, andl make for a greater use of tantalum produced.

Jan 1, 1930