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By Thomas T., Read

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 1852, 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 1856-57. 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 E. P. Pfleider

Important economic planning by industries, companies, financial firms and governments is predicated on estimates of future growth potential. Prior to the passage of the Taconite Amendment by the people of the State in November 1964, various admittedly conservative forecasts were made of the future of Minnesota's iron ore industry. Since that date, 3 new taconite plants are under construction, 2 are being expanded, one has just gone "on stream," and a seventh is in the design stage. These plants have a total capacity of about 35 million tons of pellets annually. The pessimism of 1964 today is being replaced by unbounded optimism. In the light of such recent developments, it becomes essential to update forecasts related to production, employment and capital investments. New projections show 50 to 58 million tons of pellet production from Minnesota by 1975. This tonnage, together with some 6 to 8 million of natural ores, should provide an annual full-time employment of 15,000 by the mining companies, plus 700 in related railroad and power producing activities and 1000 in plant construction. Total capital investment in new plants should reach $1.5 billion by 1975 and $2 billion by 1990. These current estimates indicate that the conservative goals as set in 1964 for the year 1990 should actually be achieved by 1975 or 1980. BACKGROUND Various forecasts1,2,3 have been made of the future consumption and production of iron ores within the United States. The most recent of these is by Harrison,1 delivered at the American Mining Congress meeting in Las Vegas in October. His estimates reflect the latest iron ore developments on a world wide front as well as the accelerating trend toward pellets. Minnesota's Natural Resources council prepared a detailed report in 1964 outlining the various factors that affect the future of Minnesota's iron ore industry. It presented estimates predicated on the

Jan 1, 1967

By G. R. Speich

The age-hardening of Fe-18 to 21 pct Ni marten-sites containing small amounts of titanium, aluminum, copper, or molybdenum has been studied by hardness measurements, transmission electron microscopy, extraction replicas, and X-ray and electron diffraction. Electyon-probe microanaly-sis of the extracted precipitates was also performed. The effects of temperature and composition on the aging kinetics have been studied in detail for Fe-20 pctNi-Ti martensites. All the martensites hardened on aging at 400" to 500 "C with a single aging peak. In the Fe-20 pct Ni-Ti martensites hardening was associated with the formation of a fine dispersion of NisTi. No precipitation was observed in an Fe-21 pct Ni-2.6 pct A1 alloy, although the hardness increased from 327 to 545 Dph during aging at 500°C. Copper was precgitated from an Fe-20 pct Ni-10.7pct Cu alloy, at least during the later stages of age-hardening. Hardening in an Fe-18 pctNi-5pct Mo alloy was associated with the precipitation of an intemzetallic compound tentatively identified as NisMo. The formation of austenite and the recovery of the defect structure of the martensite occur simultaneously with the normal precipitation processes &ring aging of these alloys. THE age-hardening of substitutional iron-base martensites is an important subject for study since age-hardening is one of the principal means of strengthening the substitutional iron-base martensites in precipitation-hardening stainless steels1 and maraging steels.a~4 In contrast to Fe-C martensites, these martensites are relatively soft and ductile in the as-quenched condition, due to the low solid-solution hardening effect of the substitutional elements as compared to carbon. Also, these martensites are hardened by aging at low temperatures in contrast to Fe-C martensites which generally soften on tempering. Titanium and aluminum, singly or in combination, as well as copper and molybdenum, have been the principal alloying additions to stainless steels to obtain an age-hardening reaction.' Ti-A1 or Co-Mo-Ti combinations have been used in the case of maraging steels.3"4 The present work has been confined to a study of the age-hardening characteristics of an Fe-18 to 21 pct Ni martensite to which small amounts of titanium, aluminum, copper, and molybdenum were added in order to study the effects of each alloying element separately. The age-hardening characteristics of these alloys were studied by hardness measurements, transmission electron microscopy, extraction replicas, and X-ray and electron diffraction. Electron-probe micro-analysis of the extracted precipitates was also performed. The types and dispersion of precipitates, the formation of austenite, and the recovery of the defect structure of the martensite all were studied. EXPERIMENTAL PROCEDURE Alloys. The compositions of the alloys studied are listed in Table I. The level of 18 to 21 pct Ni was chosen to assure complete transformation to martensite on quenching and is the same nickel level used in maraging steels. The concentrations of titanium, aluminum, copper, and molybdenum were chosen after a study of the and Fe-Ni-MO' ternary diagrams indicated how much of each alloying element could be dissolved in austenite. Alloys with 2 and 4 pct Cu were also studied, but these did not show precipitation hardening at the nickel levels studied and will not be discussed further. The alloys were prepared from electrolytic iron and high-purity* nickel, titanium, aluminum, copper, and molybdenum by vacuum melting of 20-lb heats. These were vacuum-cast into two 8-lb ingots. The ingots were hot-rolled at 1100°C to 1/2-in. plate and subsequently cut into 3/8-in. cubes. The cubes were sealed in evacuated quartz capsules and solution-treated for 16 hr at 1100°C, except for the Fe-20 pct Ni-10.7 pct Cu alloy and Fe-21 pct Ni-2.6 pct A1 alloys which were solution-treated for 16 hr at 1300" and at 1250"C, respectively. Metallographic examina-

Jan 1, 1963

By J. Chupak, D. J. Salley, G. L. Simard

Radiotracers were demonstrated to be of considerable value in a study of the interaction of dithiophosphate with galena. The interaction had characteristics of both chemisorption and chemical reaction, being complex because of the nature of the galena surface. Sorption was rapid and markedly reversible, and flotation occurred at relatively small amounts of dithiophosphate sorbed.

Jan 1, 1950

By C. W. Allen, L. C. Moore

The Mather mine, of the Negaunee Mine Co., is within the limits of the City of Ishpeming. on the Marquette iron range in Michigan's Upper Peninsula. It is named for William G. Mather, who has served as President, and Chairman of the Board, of The Cleveland-Cliffs Iron Co. for well over 50 years. The property comprises nearly the square mile of section 2, T.47 N. R.27 W., which, except for 20 acres in the northeast corner, was leased by The Cleve-land-cliffs Iron Co. to the Negaunee company. The latter is a partnership of Cleveland-Cliffs and the Bethlehem Steel Co., organized to equip the property, retaining Cliffs in charge as operator. Shipments of ore from this area are mainly through Marquette, which is 16 miles to the northeast on Lake Superior, or through Escanaba, a Lake Michigan port, 65 miles to the south. Cleveland-Cliffs, in 1943, operated 12 mines in the Lake Superior district, with shipments of 6,635,576 tons for the year. Geology The north footwall of the Marquette Range synclinorium outcrops near the north line of set. 2, the iron formation dipping to the south at an angle of about 40. The south side of the trough reappears at a distance of 4J5 miles on sec. 26 and the surface geology between shows iron forma- tion or intrusive diorites. The latter are harder than most phases of the iron formation and, as a result of glacial action, appear as buttes or low-lying hills. The general elevation of sec. 2 is about 1450 ft. above sea level, or 850 ft. above Lake Superior, and the higher diorite outcroppings about 1600 ft. above sea level. The geological structure has been complicated by a series of major and minor faults, one of which may be illustrated by the diorite sheet, which tilts south with the iron formation in the north half of the section and then reappears near the center to repeat this sequence. Sectionally the geological series includes a nearly eroded capping of Goodrich quartzite followed by the considerable thickness of Negaunee iron formation, which is cut by intrusive dikes or diorite sheets, and underlain by the Siamo slates grading into quartzites. The ore deposits occur mainly in troughs formed by the intersection of impervious dikes and the footwall slate, but include locally enriched lenses or bands in the iron formation and also interbedded with the Siamo slate. The ore is a soft red hematite with an indicated dried analysis from the surface drilling to date of 61.50 per cent Fe, 0.134 Per cent P, 5.40 per cent Si, 2-87 Per cent A1 and 0.015 per cent S. Exploration A diamond-drilling campaign started in 1937 actually had its inception in 1917, when a number of shallow test holes were put down for the purpose of locating ore that might be quickly developed and mined

Jan 1, 1946

By C. W. Allen, L. C. Moore

THE Mather mine, of the Negaunee Mine Co., is within the limits of the City of Ishpeming, on the Marquette iron- range in Michigan's Upper Peninsula. It is named for William G. Mather, who has served as President, and Chairman of the Board, of The Cleveland-Cliffs Iron Co. for well over 50 years. The property comprises nearly the square mile of section 2, T.47 N. R.27 W., which, except for 20 acres in the northeast corner, was leased by The Cleveland-Cliffs Iron Co. to the Negaunee company. The latter is a partnership of Cleveland-Cliffs and the Bethlehem Steel Co., organized to equip the property, retaining Cliffs in charge as operator. Shipments of ore from this area are mainly through Marquette, which is 16 miles to the northeast on Lake Superior, or through Escanaba, a Lake Michigan port, 65 miles to the south. Cleveland-Cliffs, in 1943, operated 12 mines in the Lake Superior district, with shipments of 6,635,576 tons for the year. GEOLOGY The north footwall of the Marquette Range synclinorium outcrops near the north line of sec. 2, the iron formation dipping to the south at an angle of about 40º. The south side of the trough reappears at a distance of 4 ½ miles on sec. 26 and the surface geology between shows iron formation or intrusive diorites. The latter are harder than most phases of the iron formation and, as a result of glacial action, appear as buttes or low-lying hills. The general elevation of sec. 2 is about 1450 ft. above sea level, or 850ft. above Lake Superior, and the higher diorite outcroppings about 1600 ft. above sea level. The geological structure has been complicated by a series of major and minor faults, one of which may be illustrated by the diorite sheet, which tilts south with the iron formation in the north half of the section and then reappears near the center to repeat this sequence. Sectionally the geological series includes a nearly eroded capping of Goodrich quartzite followed by the considerable thickness of Negaunee iron formation, which is cut by intrusive dikes or diorite sheets, and underlain by the Siamo slates grading into quartzites. The ore deposits occur mainly in troughs formed by the intersection of impervious dikes and the footwall slate, but include locally enriched lenses or bands in the iron formation and also interbedded with the Siamo slate. The ore is a soft red hematite with an indicated dried analysis from the surface drilling to date of 61.50 per cent Fe, 0.134 per cent P, 5.40 per cent Si, 2.87 per cent Al and 0.015 per cent S. EXPLORATION A diamond-drilling campaign started in 1937 actually had its inception in 1917, when a number of shallow test holes were put down for the purpose of locating ore that might be quickly developed and mined

Jan 1, 1945

By A. L. Mular

lnput energy-size modulus relation at small reduc-tion ratios is expressed by Et = (M, -Mt) k;. In some cases 13 is close to Schuhmann's distribution modulus a in value. Experimental results in conjunc-tion with the equation demonstrate the fact that energy input which produced fracture is not expended on unbroken starting material inside the mill at any time. Recently, schuhmann1 derived the Charles equation2 using the postulate that complex com-minution operations can be considered as a summa- tion of many comminution events. The fragments resulting from each event are assumed to follow the Gaudin-Schuhmamn distribution. In his derivation, Schuhmann implies that the size distribution of the total mass of a material is determined by the fraction of that mass actually subjected to comminution. Consider a feed to contain a volume, Vo, of uni- formly sized homogeneous material. After t seconds of grinding, let the volume of broken material be Vo - Vt where Vt is the volume of starting material not yet broken. The size distribution of the broken material is given by: where V is the cumulative volume less than size X, and k, is the size modulus of the broken material at time t. The distribution for the total volume at this

Jan 1, 1962

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared for these tests by high-temperature methods, especially by crystallization from borax melts.

Jan 1, 1950

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.' 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.' 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 regions3 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.238 The axis of the syncline dips to the 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.' 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.' 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.' 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, 1953

By Thomas T. Read

THE benefits derived from stabilization of industry that might possibly be attained through some scheme of centralized economic planning have been much discussed of recent months, and opinions on the subject range from those who believe that some agency like the War Industries Board would be practicable to create and wholly beneficial in effects, to those who are equally convinced that none of the suggestions so far advanced are at all practicable, or likely to be productive of more of good than of evil. The discussion has been on the general topic, but-many of those who have written or spoken on it have introduced economic problems of the pinera1 industry; for example, Newton D. Baker, who referred to the coal industry in his address on economic planning at the Williamstown Institute of Politics on July 31, and then went on to say, "Industrial progress is made by the development of new things, but new things upset the equilibrium of any plan. Who could have planned the industrial effects of the development of the railroads, or the economic changes which you have seen attend the development of the internal combustion engine. Obviously, unless we are prepared to put world economics in a strait-jacket and, like the encyclopedists, write its full history on the theory that further progress is impossible, no such plan could be made for nations which are forging ahead as is entirely rational for nations which are still catching up."

Jan 1, 1931

By AIME

THE history of the Mine La Motte area covers a greater period of time than any other mining operation west of the Mississippi, for it was almost exactly four centuries ago that the white man first visited the region. In May 1541 a few men from the party of Fernando de Soto traversed the place looking for silver which they understood the Indians had found in the vicinity. Some historians say that De Soto himself visited the place sometime later. No other white man came through again until the early 1700's. In 1712 King Louis XIV of France granted to Antoine Crozat a charter for transacting all business and government in the vast domain of the New Continent stretching from the Gulf of Mexico northward indefinitely. This

Jan 1, 1947

By William Campbell

(Cleveland Meeting, October, 1912.) [SECRETARY'S NOTE.-To avoid repetitions of foot-notes, references to authorities are made in the paper by means of figures, referring to a numbered list in the appendix.-J. S.] I. INTRODUCTION. IN the olden days the making of alloys was au art, and the secrets of the craft were jealously guarded. To-day it has become a science, though the old ideas in regard to the secrets and formula are dying hard. Modern progress may be attributed to scientific research and testing of materials, and the substitution of chemical analytical control for " cook-book " methods. We know to-day a great deal about the constitution of alloys, the reasons of the change in structure and physical properties by heat and mechanical treatment; and this new knowledge is due for the most part to the physical chemist and metallographist, who have shown us that alloys are simply solutions, and as such obey definite laws. The application of the theories of solutions and of the phase rule tells us what ought to happen when our alloys are in a state of equilibrium. The working-out of the temperature-composition diagram (thermal diagram) for numerous alloys has thrown a light on the structure and constitution which has dispelled most of the darkness in which we labored before the advent of metallography. The work began with the determination of the freezing-point curves, and here the research of Le Chatelier,1 Gautier,2 Roberts-Austen,3 and the other pioneers broke the ground. Next the physical chemists, Tammann,4 Rooseboom,5 Bancroft,6 and their colleagues, showed us the complete thermal diagram and its meaning. Then the researches of Heycock and Neville 7 on the Cu-Sn series and of Shepherd 8 on the * Associate Professor of Metallurgy, Columbia University in the City of New York.

Dec 1, 1912

By David C. Jonson, W. Bruce MacKenzie, Arthur A. Bookstrom, Vaughn E. Surface, Neil K. Muncaster, Stewart R. Wallace

In mid-Tertiary time a wet silici-alkalic magma penetrated the Precambrian rocks of what is now the Tenmile Range of Central Colorado and formed the Climax Stock. The stock is a composite one and was intruded in four separate irruptions, each giving rise to a major hydrothermal event. The first three of these produced large stockwork ore bodies that cap and flank the tops of their respective source intrusives; the fourth, and last, yielded almost no commercial mineralization. The ore bodies and their related zones of alteration are circular to ring-shaped in plan and arcuate in section. The different phases of the stock are so positioned with respect to each other that many of the circular and arcuate zones of mineralization and alteration overlap or are juxtaposed. Evidence of a time separation between the different ore bodies is found in certain dikes that were intruded between periods of mineralization and are well mineralized in one ore body but are barren in another. If it is assumed that the parent magma at Climax contained 10 per cent "water," that the "water" contained 0.1 grams per liter of molybdenum, and that the processes of extraction were 100 per cent efficient, then approximately 10 cubic miles of magma would be required for the formation of each ore body. The volume requirements, taken in conjunction with the cross-sectional areas of the different phases of the stock to explored depths, suggest to the authors that each magma chamber was columnar, extended to a depth of thousands of feet, and was connected with a much larger master reservoir. The repetition of similar intrusive, structural, and hydrothermal events, indicates periodic tapping of this reservoir. A regular chemical evolution of the parent magma is suggested by the systematic change in metal ratios and differences in the sites of deposition, relative to the source intrusive, in each of the four separate igneous hydrothermal stages. The preparation of ground was due to changes in magmatic and/ or hydrothermal pressures within the igneous-hydrothermal columns; small, repeated, up and down movements of the rock enclosing the tops of the columns formed the stockwork fractures into which the mineralizers penetrated. The forceful emplacement of each successive phase of the Climax Stock resulted in a slight doming and rotation to the westward of the earlier-formed geologic features. Postore normal displacement along the Mosquito fault is estimated at about 9000 feet. Part of one ore body was cut by the fault and lies at depth below the Paleozoic sedimentary strata on the hanging wall. On the footwall side of the fault, subaerial erosion and glaciation removed a large part of one ore body and uncovered the top of a second.

Jan 1, 1968

By J. Ruben Velasco, Roland B. Mulchay

CANANEA has long been recognized as a remarkable field for geologic study. The copper deposits and rocks of the district have been described by many geologists and engineers, but only the most general correlations have been made between Cananea sedimentary rocks and other known sedimentary sections in the southwestern United States and northern Mexico. The present paper describes the Cananea sediments in greater detail than has been done before and attempts to fit the Cananea sedimentary section more closely into the geologic time table. The lack of well-preserved fossils has made it difficult to date the sediments accurately in geo- logic time, but it is possible to make tentative correlations between the Cananea sediments and the southeastern Arizona sections, based largely upon lithology and general position in the geologic column. It appears that sedimentation at Cananea and Bisbee may have been closely similar during Paleozoic time. Even such generalized correlations, however, may be subject to considerable modification in the future. The present study has led to the recognition of other problems of age and mineralization relationships in the Cananea district. Cananea is located in the north-central part of the state of Sonora, Mexico, at an elevation of 5270 ft. It is about 135 miles northeast of Hermosillo, the state capital, and 25 miles south of the international boundary. By road Cananea is 40 miles from the twin towns of Naco, Ariz., and Naco, Sonora, and about 50 miles from Bisbee, Ariz. It is served by the Nogales-Naco branch of the railroad, F.C. Pacifico, and is connected with Chihuahua and Mexico City by the Aeronaves airline.

Jan 6, 1954

By C. H. Li, R. D. Carnahan, R. J. Stokes, T. L. Johnston

When silver chloride deforms by pencil glide at temperatures of 26ºand 72°C, grain size has no effect upon the proportional limit and the material necks down to a knife edge under tension. At -196ºC, deformation takes place on fewer slip systems to produce straight slip traces, the flow stress becomes sensitive to grain size and fracture occurs by cleavage from an intergranular source without any reduction in area. THERE are significant differences between the appearance of the slip bands formed in silver chloride and in the alkali halides at room temperature. The bands in sodium chloride, e.g., are fine and geometrically straight, whereas in silver chloride they are coarse and wavy.' Such differences in the slip behavior prompted us to inquire what the effects of grain boundaries might be on the mechanical properties of these solids. As an introduction to a general study of ionic poly-crystal behavior, we have investigated the effect of grain size on the stress-strain relationships in silver chloride at different temperatures. We have chosen silver chloride chiefly because polycrystals can be easily prepared free from cracks and macroscopic voids by conventional techniques. Moreover, as we shall see, the slip behavior can be readily modified by changing the temperature. It will be shown that the effect of grain size on the yield stress of silver chloride is strikingly dependent upon the temperature of deformation and that this temperature effect comes about through a change in the number of slip systems which operate at the onset of plastic flow. EXPERIMENTAL PROCEDURES Polycrystalline tensile specimens were made by recrystallizing cold-rolled AgCl sheet. Thirty-gram quantities of AR grade silver chloride powder were melted in a low heat capacity furnace, cast into cylindrical forms 3/4 in. in dim and approximately 1 in. in length and then extruded with a 16:l reduction ratio into rods 3/16 in. in dim. Extrusion temperatures were varied from room temperature to 350°C. In order to impart various degrees of cold'work to the extruded rod. All extrusions were then cross rolled to sheet 0.040 in. in thickness at room temperature and machined to form tensile specimens having a gage length of 0.750 in. with a width of either 0.250 or 0.145 in.* Annealing was carried out in an air oven at 200°C for periods up to 20 hr. specimens having average grain diameters ranging from 0.024 to 0.40 mm were prepared by varying the extrusion temperature and annealing time in the conventional manner. To obtain specimens with grain sizes larger than 0.40mm, lightly deformed thin prisims of silver chloride single crystals (supplied by Harshaw Chemical Co.) were recrystallized. Grain size determinations were made by an intercept method and revealed that the grains were equi-axed. Laue back-reflection X-ray patterns showed little tendency to form a preferred orientation texture. Specimens which were to be used for the slip band studies were polished by immersion in fresh boiling concentrated NH,OH for 60 sec. They were then etch polished for 10 sec on each side by hand lapping on a stationary velveteen lap wetted with a dilute Hypo solution (5 g of Kodak Acid Fixer in 100 cc H20). Finally the specimens were rinsed in warm water and alcohol, blown dry and carefully mounted in the tensile machine for testing. Tensile tests were performed at three temperatures, namely, 26º, -72º, and -196°C. A screw-driven hard tensile machine was used at a constant strain rate of 0.006 in. per in. per min. Loads were determined with a light- proof ring fitted with A-18 strain gages and extensions were measured with a 0.0001 in. dial gage. Constant level baths of alcohol with dry ice and liquid nitrogen were used to maintain the two lower test temperatures. EXPERIMENTAL RESULTS Reproducibility—In view of the light sensitivity and reactive nature of silver chloride, it was necessary to determine whether reproducibility depended upon either exposure to light or to the condition of the surface. However, during the course of the work it became clear that variation of laboratory lighting

Jan 1, 1962

By J. E. Brantly

In October 1939, a drilling program was commenced on the Atlantic seaboard of Brazil, with three steam rotary rigs of medium capacity. One of these was assigned to the State of Alagbas and the other two to the State of Bahia. During the remaining few months of 1939 and during the year 1940, some eight wells were drilled, two in Alagbas and six in Bahia. Two small producers were found in the latter state. In early 1941 three medium-weight Diesel rigs were added to the equipment, thus permitting the drilling of some 15 wells during the year 1941. The two small producers found in 1940 in the State of Rahia were near the city of Silo Salvador. In 1941 three additional small wells were brought in, in the same area, and a further producer on an isolated structure some 75 km. to the northwest of this production. No commercial production has been found in the State of Alagbas. Approximately 26 wells have been drilled or are drilling, six of which are producers— five in one area and one in another. The program for 1942 calls for the development of the two areas in which wells have been found and also the drilling of several wildcat structures located either by geophysics or surface geology. All production in the area of the several producing wells is somewhat less than 2000 ft. and in the other area about 3800 ft. The area of the several wells is known as the Lobato field, and is practically within the city limits of Sao Salvador. The area 75 km. northwest of the city will be known as the Candeias field.

Jan 1, 1942

IN speaking, on the subject, "Engineer-Citizens," at the Lehigh Valley Mineral Industries Conference dinner, on April 26, at Easton, Pa., George Otis Smith, Director of the United States Geological Survey and President of the American Institute of Mining and Metallurgical Engineers, said in part: "It would be carrying coke to Connellsville to bring to the Lehigh Valley the idea that mineral resources are the foundation of national prosperity. Unfortu-nately, however, this obvious, fact is not everywhere recognized. Too many of our economists, journalists, statesmen and other dopesters of present business con-ditions stress the human factor so strongly that they overlook the material with which men work out their destiny. To them the financial psychology of Wall Street and the political logic of Capitol Hill and the business commonplaces of Main Street all loom far larger than the geology of the Lehigh Valley or the engineering triumphs of Bethlehem, or, the creative thinking at Lehigh and Lafayette. "The present situation in the industrial and .business world is a complex of interacting causes and reacting effects not easily itemized and entered on our trial balance sheet. But, chief among the liabilities of today is the excess of production capacity in most branches of industry. The farmer has no. monopoly in his desire for relief. Whether your professional connections are with steel or cement, coal or oil, copper, or zinc, you; know too well that for, the moment America is over-engined, and you keenly realize the ever-present hazard of industry speeding up regardless of the curves or grades just around the corner.

Jan 5, 1928

By J. E. Brantly

In October 1939, a drilling program was commenced on the Atlantic seaboard of Brazil, with three steam rotary rigs of medium capacity. One of these was assigned to the State of Alagbas and the other two to the State of Bahia. During the remaining few months of 1939 and during the year 1940, some eight wells were drilled, two in Alagbas and six in Bahia. Two small producers were found in the latter state. In early 1941 three medium-weight Diesel rigs were added to the equipment, thus permitting the drilling of some 15 wells during the year 1941. The two small producers found in 1940 in the State of Rahia were near the city of Silo Salvador. In 1941 three additional small wells were brought in, in the same area, and a further producer on an isolated structure some 75 km. to the northwest of this production. No commercial production has been found in the State of Alagbas. Approximately 26 wells have been drilled or are drilling, six of which are producers— five in one area and one in another. The program for 1942 calls for the development of the two areas in which wells have been found and also the drilling of several wildcat structures located either by geophysics or surface geology. All production in the area of the several producing wells is somewhat less than 2000 ft. and in the other area about 3800 ft. The area of the several wells is known as the Lobato field, and is practically within the city limits of Sao Salvador. The area 75 km. northwest of the city will be known as the Candeias field.

Jan 1, 1942

THE LIFE and works of Alexander Agassiz, first president of the Calumet & Hecla Mining Co., were recalled to memory when a monument bearing his statue was unveiled in Agassiz Park, at Calumet, Mich., on Sept. 26, The statue is the work of Paul W. Bartlett, of New York, and was erected by George R. Agassiz, eldest son of Alexander Agassiz. We are indebted to Rodolphe L. Agassiz, now president of the Calumet & Hecla Consolidated, for the accompanying photograph of the statue. The principal address at the unveiling ceremony was delivered by Allen F. Rees, of Houghton, who said, in part: To the world at large Alexander Agassiz was preeminently the man of science. With all his devotion to the industrial life of this district, he found the time to devote to the con-tinuation of his work of scientific research which had been the life work of his fa-ther, Louis Agassiz. Not only did he acquire eminence for his scientific at-tainments and learn-ing, but he was recognized and hon-ored throughout the civilized world for his achievements and accomplishments in the realm of original research. His work in the fields of nat-ural science, in oceanography, in marine zoology, and in other similar lines of research, has added much to our knowledge of the world's mysteries. His life was one of accomplishment also in the industrial world. The union in one life of acknowledged achievement as a scientist and the accomplishment of great results in the prac-tical industrial world is a rare thing, and its possibility has never been exemplified in greater measure than in his life and its results.

Jan 11, 1923

By L. Bombardieri, H. F. Mills

Iron King mine, producing gold-silver-lead-zinc-ore, is 10 miles east of Prescott, Ariz. At present the 1806 level is being developed. The echelon pat tern of ore deposit continues at depth but is less pronounced, and the orebody is now more or less continuous over 2600 ft of strike length, with widths 5 ft to as high as 26 ft where overlapping of lenses occurs in one section of the mine. Better continuity of ore at depth has encouraged systematic mining and improved plant facilities to offset higher operating costs. With favorable persistence of ore at depth, the three-compartment No. 6 hoisting shaft appeared inadequate to handle increased tonnage from greater depths, and in 1952, a four-compartment steel and concrete shaft was started. This is now at a depth of 1906 ft, and shaft pockets and loading cartridges are being installed on the 1806 level. Ore from the new shaft, hoisted in 5 ½ -ton Jeto bottom dump skips, is dumped into a 500-ton shaft bin, from which it is fed to a 16x30-in. gyratory crusher and conveyed 415 ft through an undersurface concrete gallery to the secondary crusher and conveying system supplying the 900-ton mill. Lead, zinc, and pyrite concentrates are floated, and the flotation tailings are cyanided after desliming. Waste from the new shaft is dumped into a 250-ton surge bin, fed from this bin to a 24-in. conveyor, and discharged into the glory hole above the block cave. The new shaft is served by a double-drum 400-hp hoist used for ore and waste; the No. 6 shaft conveys men and material.

Jul 1, 1956