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By H. l. Burghoff, C. H. Mathewson

THE study of the creep of metals under conditions of prolonged loading has received the attention of many investigators for several years and almost innumerable papers have been published on the various aspects of the subject. As it appeared that much could still be learned from a study of single crystals, the present work was carried out to study the effects of temperature and conditions of loading upon the properties and deformation in tension of single crystals of alpha brass containing about 70 per cent copper and 30 per cent zinc. In particular, it was hoped to obtain information from tests below and above the recrystallization temperature of the material, so that properties such as elastic limit, yield point or critical stress, and manner of deformation might be compared for tensile tests at an ordinary loading rate and for prolonged. loading. Accordingly, short-time tensile tests and creep tests were made at room temperature, 300º, 500° and 700°F. The two latter temperatures are above the lowest possible recrystallization temperature of polycrystalline 70-30 brass. PREVIOUS WORK Clarke and White1 have made creep tests of some copper-zinc alloys, including 70-30 brass, and copper-zinc-tin alloys at temperatures both below and above the recrystallization temperature of the materials considered. Hanson and Wheeler have studied the flow and fracture of single crystals of aluminum for short-time and prolonged tensile loading over a range of temperature extending from room temperature to 400°F., their experiments being made without consideration of the orientations of the test specimens. Extensive creep and fracture tests on single crystals of lead at room temperature have been made by Betty3 and by Baker, Betty & Moore.4 Results of the last-named investigation were published while the present work was in progress. Millers examined the elastic limit of zinc single crystals at and above room temperature by means of creep tests, while Miller and Milligan6 reported the results of tests designed to show the influence of temperature on elastic limit of single crystals of aluminum, silver and zinc. The behavior, of iron crystals under static tensile loading at room temperature was reported by Gensamer and Mehl7 while the present investigation was in progress. Their specimens exhibited a well-defined yield point, below which no appreciable creep could be detected. The manner of yielding proved interesting, as the shape of the creep-time curve for the iron crystals differed from the common type of creep curves. Elongation did not begin immediately, or at least was initially very slow. The rate of elongation then increased continuously and finally decreased to zero. This S-shaped type of elongation-time

Jan 1, 1941

By Will Mitchell, T. G. Kirkland, C. L. Sollenberger

R. S. Handy (Santa Rosa, Calif.)—It would be interesting to learn the comparative results of treating the Korean scheelite ore described in this paper according to the following procedure: I—Follow the procedure described in the paper to the recovery of the sulphides by flotation. 2—Dilute the residue from the sulphide flotation strongly with water and disperse the contained colloids by adding a mixture of 75 pct sodium silicate and 25 pct quebracho to dispersion point. 3— Settle the dispersed pulp and decant the supernatant colloids. 4—-Dilute, settle, and decant the pulp until the settled residue is crystalline. Not over 10 pct of the tungsten minerals should follow the colloids. 5—Treat the settled residue by flotation, having established the proper pH. Oleic acid homogenized with cresylic acid or kerosene is more selective for scheelite than is oleic acid alone. (The recovery of the contained tungsten minerals should be practically complete in this operation.) 6—Deflocculate the tungsten concentrate from step 5 with the same dispersion agents as in step 2 and treat the deflocculated pulp by gravity. The minerals that tend to float with scheelite are generally of low specific gravity and the separation is efficient. The heavier contaminants, such as pyrrhotite and magnetite can be removed magnetically, leaving a practically pure scheelite. E. J. Pryor (Imperial College of Science and Technology, London)—It occurred to me that instead of using temperature as a differentiating control, more precision might be obtained with a reagent of a type we developed here for the flotation of high grade fluorspar in cold pulps. This reagent, which is manufactured on a modest scale in England, is based on oleic acid, which has been modified by our patented process to ensure complete stable dispersion at any desired concentration in water. It thus becomes possible to utilise unimolecular layers with good selectivity. In the fluorspar flotation for which we developed it, it is possible to hold a tight control on depressing quebracho for the calcite without substantial loss of flu-orite, and recovery exceeding 99 pct is not uncommon in the mill where it is in use, even under wintry conditions. No attempt has been made yet to extend the use of the reagent, as we have not completely overcome

Jan 1, 1952

By E. G. Davis, G. V. Sullivan, J. P. Hansen

As part of its overall goal to maintain an adequate supply of minerals to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, investigated the feasibility of producing subsieve-size material by an attrition grinding method. The Bureau-patented technique employed intense agitation of a mixture of the material to be ground, a granular grinding media, and a suspending fluid. A variety of materials were successfully ground to extremely fine particle sizes. Studies were made to determine the method's efficiency in grinding industrial minerals and metals to minus 2 micrometers and ceramic powders to an average particle size of 500 angstroms. Transfer of this technology to a commercial scale has been achieved. Commercial-scale units are currently being used in the paper-coating clay and titania pigment industries.

Jan 1, 1980

By C. H. Mathewson, H. l. Burghoff

The study of the creep of metals under conditions of prolonged loading has received the attention of many investigators for several years and almost innumerable papers have been published on the various aspects of the subject. As it appeared that much could still be learned from a study of single crystals, the present work was carried out to study the effects of temperature and conditions of loading upon the properties and deformation in tension of single crystals of alpha brass containing about 70 per cent copper and go per cent zinc. In particular, it was hoped to obtain information from tests below and above the recrys-tallization temperature of the material, so that properties such as elastic limit, yield point or critical stress, and manner of deformation might be compared for tensile tests at an ordinary loading rate and for prolonged loading. Accordingly, short-time tensile tests and creep tests were made at room temperature, 300°, 500° and 700°F. The two latter temperatures are above the lowest possible recrystallization temperature of polycrys-talline 70-30 brass. Previous Work Clarke and White1 have made creep tests of some copper-zinc alloys, including 70-30 brass, and copper-zinc-tin alloys at temperatures both below and above the recrystallization temperature of the materials considered. Hanson and Wheeler2 have studied the flow and fracture of single crystals of aluminum for short-time and prolonged tensile loading over a range of temperature extending from room temperature to 400°F., their experiments being made without consideration of the orientations of the test specimens. Extensive creep and fracture tests on single crystals of lead at room temperature have been made by Betty3 and by Baker, Betty and Moore." Results of the last-named investigation were published while the present work was in progress. Miller5 examined the elastic limit of zinc single crystals at and above room temperature by means of creep tests, while Miller and Milligan6 reported the results of tests designed to show the influence of temperature on elastic limit of single crystals of aluminum, silver and zinc. The behavior of iron crystals under static tensile loading at room temperature was reported by Gensamer and Meh17 while the present investigation was in progress. Their specimens exhibited a well-defined yield point, below which no appreciable creep could be detected. The manner of yielding proved interesting, as the shape of the creep-time curve for the iron crystals differed from the common type of crcep curves. Elongation did not begin immediately, or at least was initially very slow. The rate of elongation then increased continuously and finally decreased to zero. This S-shaped type of elongation-time

Jan 1, 1941

By H. l. Burghoff, C. H. Mathewson

The study of the creep of metals under conditions of prolonged loading has received the attention of many investigators for several years and almost innumerable papers have been published on the various aspects of the subject. As it appeared that much could still be learned from a study of single crystals, the present work was carried out to study the effects of temperature and conditions of loading upon the properties and deformation in tension of single crystals of alpha brass containing about 70 per cent copper and go per cent zinc. In particular, it was hoped to obtain information from tests below and above the recrys-tallization temperature of the material, so that properties such as elastic limit, yield point or critical stress, and manner of deformation might be compared for tensile tests at an ordinary loading rate and for prolonged loading. Accordingly, short-time tensile tests and creep tests were made at room temperature, 300°, 500° and 700°F. The two latter temperatures are above the lowest possible recrystallization temperature of polycrys-talline 70-30 brass. Previous Work Clarke and White1 have made creep tests of some copper-zinc alloys, including 70-30 brass, and copper-zinc-tin alloys at temperatures both below and above the recrystallization temperature of the materials considered. Hanson and Wheeler2 have studied the flow and fracture of single crystals of aluminum for short-time and prolonged tensile loading over a range of temperature extending from room temperature to 400°F., their experiments being made without consideration of the orientations of the test specimens. Extensive creep and fracture tests on single crystals of lead at room temperature have been made by Betty3 and by Baker, Betty and Moore." Results of the last-named investigation were published while the present work was in progress. Miller5 examined the elastic limit of zinc single crystals at and above room temperature by means of creep tests, while Miller and Milligan6 reported the results of tests designed to show the influence of temperature on elastic limit of single crystals of aluminum, silver and zinc. The behavior of iron crystals under static tensile loading at room temperature was reported by Gensamer and Meh17 while the present investigation was in progress. Their specimens exhibited a well-defined yield point, below which no appreciable creep could be detected. The manner of yielding proved interesting, as the shape of the creep-time curve for the iron crystals differed from the common type of crcep curves. Elongation did not begin immediately, or at least was initially very slow. The rate of elongation then increased continuously and finally decreased to zero. This S-shaped type of elongation-time

Jan 1, 1941

By A. B. Dyes, P. H. Braun, B. E. Cole

This paper presents a reservoir engineering analysis of the performance data for a waterflooding project in the Johnson Lease, South Ward field. This type of engineering analysis adds to the knowledge of the mechanics of water flooding. This study reveals that in general (a) high ultimate areal sweep-out efficiencies (95 to 100 per cent) can be expected, and (b) cross-flow among strata of different permeabilities during the fill-up phase can have an important influence on the behavior and should be dealt with in studying reservoirs for water flooding. The analysis further showed that the recovery predictions based on what was considered a consistent interpretation of core data and logs were low because little contribution was assumed from the low permeability, oil-bearing sand sections which have apparently yielded considerable waterflood oil. This project has yielded in excess of 2 1/2 times as much oil by water flooding as by primary depletion. These very favorable results were achieved without the use of any special injection well completion techniques. However, all of the low permeability material war included in the section open to injection despite its poor estimated primary yield. LEASE PERFORMANCE HISTORY The South Ward field lies in the southeast corner of Ward County near the southern tip of the tremendous Yates trend. Deposition of sand bodies along the seashore reefs during the latter part of the Permian period established what have turned out to be ideal conditions to form a great number of independent productive sands. Probably, these reservoirs in Ward and Winkler counties are providing operators with some of the nation's richest sources of secondary oil reserves through the use of waterflooding techniques. In South Ward field water has been very successfully used to flood oil from the Bennett sand occurring at a depth of about 2,300 to 2,400 ft. About 150 ft above the Bennett sand reservoir, the Grand Falls sand produced gas from a large cap extending over most of the field. The Atlantic Refining Co.'s 320-acre W. D. Johnson lease (Fig. 1) is on the northwest edge of the structure with only gas cap apparently present in the Grand Falls sand. The Bennett sand under this lease is oil productive, however, having a gross sand thickness averaging about 80 ft with a net of 18 ft of fairly clean, highly permeable sand, and about 36 ft of oil-bearing sand with low permeability and high water saturation. The lower permeability sand is interbedded with numerous layers of lime, shale, and anhydrite. Radioactivity logs from 12 wells and cores from two, examples of which are shown in Fig. 2, reveal that the total Bennett sand pore volume is about 71,000 bbl/acre. The estimated initial water saturation averages 41 per cent in the 54 ft of sand considered to contain oil; thus, also considering an estimated 18 per cent oil shrinkage, the lease originally contained about 34,000 bbl of oil per acre. Original pressure was probably about 1,400 psig. PVT correlations indicate that the reservoir fluid was originally saturated with gas. After discovery of the field in 1930, Atlantic completed the first well on the Johnson lease in March,

Jan 1, 1958

By Samuel S. Adams

Potash, the generic term for a variety of potassium-bearing minerals, ores, and refined products (Table I), owes its importance as an industrial mineral to the potassium requirement of growing plants. The term "potash" originally referred to potassium carbonate produced by the leaching of wood ashes. This process, for which the first U.S. patent was issued in 1790, was the basis for the largest United States chemical industry in the early nineteenth century. The agricultural use of potash soon eclipsed the chemical applications following the German discovery in 1840 that potassium is essential to plant growth. The initial discoveries of large deposits of soluble potassium minerals, essential for agriculture applications, were made in 1857 in Germany and in 1914 in the United States. More than 90% of the 20.4 million short tons K2O produced in the world in 1970 (Eilertsen, 1971 ) was derived from marine evaporite deposits and approximately 90% was used in fertilizers. The potassium content of an ore, mineral, or product is customarily expressed as % K,O, a unit of measure which is neither a natural nor synthetic compound of potassium (1 .O% K is equivalent to 1.2046% K,O) . Geology Potassium, the seventh most abundant element in the earth's crust, is present in silicate minerals in igneous, sedimentary and meta- morphic rocks. Potassium is also a major constituent of many surface and subsurface brines (Table 2). Economic potash deposits are essentially restricted, however, to widespread, thick accumulations of marine chloride evaporite deposits. These deposits yield high grade, large tonnage ore bodies, many of which are amenable to low cost mining and beneficiation. The products from these deposits are, moreover, ideal for use in fertilizer because of the high relative solubility of the potassium chloride and sulfate evaporite minerals. World potash production and reserves for such de- posits so vastly overshadow other sources of potassium that the following discussion will be limited largely to potash deposits in marine evaporites with brief reference to certain potash-rich brines. Approximately 85% of current domestic production is from bedded salt deposits and much of the balance is from brines. Marine evaporite deposits are accumulations of salt minerals deposited in structural sedimentary basins through the evaporation of sea-water or mixtures of seawater and other brines. The salt minerals are precipitated in assemblages and sequences of assemblages as determined by the compositions of the brines and the solubility relations in the salt systems (D'Ans, 1933). The evaporation of seawater normally yields carbonate minerals as the first precipitates (Table 3). Further evaporation and concentration of the brine leads to the precipitation, in succession, of sulfate, chloride, and supersaline mineral assemblages including the salts of potassium and magnesium. The common minerals, ores, and products of potassium deposits are listed in [Table 1]. Many potash deposits contain accessory evaporite minerals together with a variety of detrital and authigenic silicates (Braitsch, 1971).

Jan 1, 1975

By Paul J. Bennett, James E. Castle

The kyanite minerals, including kyanite, silimanite, and andalusite, are anhydrous aluminum silicates with the formula Al2O3SiO2. lumortierite and topaz are also included in this group because they are closely allied in composition and thermal behavior. However, leither are mined commercially today. They ire typical metamorphic minerals which are found in metamorphic rocks on every continent. Kyanite minerals are prized chiefly for their refractoriness and are important components in a broad range of acid refractory products, especially in mortars and castables. World production of kyanite minerals is currently about 250,000 tpy and has been increasing at the rate of 3 to 8% a year for many {ears (Anon, 1972). While kyanite minerals lave widespread occurrence, the consumption of kyanite minerals is concentrated in the relatively few highly industrialized areas where refractories are manufactured, and which in turn are typically close to the major iron and steel producing regions of the world. Thus northern Europe, England, the United States, and Japan are the principal consumers of refractories and kyanite minerals. Of these countries only the U.S. is a significant producer. The largest use for domestic kyanite, both raw and calcined, is in the manufacture of refractory mortars, cements, castables, and plastic ramming mixes. In these applications kyanite constitutes from 10 to 40% of the mixture, the balance being refractory clays and coarser grog materials. A certain proportion of raw kyanite is used to offset the shrinking of the clay binder, whereas the calcined kyanite is used in the coarser sizes for body. Certain high grade refractory shapes and kiln furniture are composed chiefly of graded sizes of calcined kyanite bonded with a little ball clay. In most applications, however, kyanite is used only to fortify the mix or as a minor ingredient. Some manufacturers of mullite brick use domestic calcined kyanite for the fine-grained portion of the brick, but seldom in quantities exceeding 10% by weight. Kyanite is used by ceramic manufacturers of wall tile and sanitary ware to offset shrinkage and cracking after firing. Indian kyanite has traditionally been used to make the coarse grog sizes needed for the manufacture of mullite brick, and for the grog portions of mortar, cement, and castable mixes. It has been largely replaced, however, by synthetic mullite, high fired flint, and diaspore clay or calcined bauxite for other applications. Indian kyanite is available in lump as well as in granules and concentrates, as are sillimanite materials from India and South Africa. Andalusite is available as 8 mesh granules and as fines with chemical analyses not unlike those of domestic kyanites. From time to time and from place to place minor amounts of other aluminum silicate minerals such as dumortier- ite, topaz, and pyrophyllite have been made available at various prices and specifications, but have not been significant factors in the refractory industry. A mixture of kyanite and sillimanite of relatively fine grain-size and of low iron content was at one time offered to the molding sand industry by the Du Pont Co. as a byproduct from their deposits of heavy

Jan 1, 1975

By Charles H. Behre

This paper discusses education and training for economic geologists other than petroleum geologists. Candidates enter economic geology through liberal arts colleges, engineering schools and university graduate study. Whatever their backgrounds, rigorous courses are desirable—now conceded in theory, but not adequately recognized in practice. Besides basic sciences (each studied long enough to give a fair comprehension of its basic tenets), a functional command of English and two modern foreign languages is needed, as well as a broad understanding of mining, milling and metallurgy. A year of economics and finance is recommended. Surveying and drafting are essential skills. Yet geology should be represented in each term; otherwise the initial enthusiasm for the science, once contact is broken, may never be regained. A five-year curriculum is thus designed to take care of all major requirements and culminate in the M. S. degree. This curriculum reduces "cultural" courses below the average liberal arts requirements, but this is regarded as necessary. The pursuit of "culture" is assigned, as in most engineering and medical curricula, to extra college years or extracurricular time. To avoid the danger of over-crowding the schooling, the Doctorate in geology is preferred wherever possible. Its two added years should permit wider professional education; more browsing in "cultural" pastures; due attention to broader social implications; and some training in the research now increasingly required of the mineral industry. "In-course" training through cooperation between school and industry is especially advo- cated. The Institute should take the initiative in stimulating this practice. Introduction Training a student in geology for a career in the mineral industry is still a moot question, one that is likely to be looked at from many different angles, each of which will reflect the background of the individual considering it. From what follows, the training of petroleum geologists is omitted since, although theirs is an equally important phase of economic geology, it is based upon different essentials. The general subject was recently effectively discussed, but from a somewhat different viewpoint, by Professor McKinstry.' The practical problems that confront the young mining geologist are highly varied and in the eyes of his employer apparently almost any demands seem justified. The mining executive wants from the mining geologist results related mainly to overall operations, reports or forecasts that are largely recordable on paper and chiefly in terms of "discovery thinking." The local mining engineer may have many specific questions of his own, chiefly relating to details of geology that apply to mining practice, which he will address to the mining geologist; these usually deal with production quantities; frequently also they necessitate the immediate handling of pressing but apparently minor matters: shall the drill be moved; how soon will we encounter the watercourse which made so much trouble for us above? The client employing a consultant often wants advice or good judg-

Jan 1, 1949

By Charles H. Behre

This paper discusses education and training for economic geologists other than petroleum geologists. Candidates enter economic geology through liberal arts colleges, engineering schools and university graduate study. Whatever their backgrounds, rigorous courses are desirable—now conceded in theory, but not adequately recognized in practice. Besides basic sciences (each studied long enough to give a fair comprehension of its basic tenets), a functional command of English and two modern foreign languages is needed, as well as a broad understanding of mining, milling and metallurgy. A year of economics and finance is recommended. Surveying and drafting are essential skills. Yet geology should be represented in each term; otherwise the initial enthusiasm for the science, once contact is broken, may never be regained. A five-year curriculum is thus designed to take care of all major requirements and culminate in the M. S. degree. This curriculum reduces "cultural" courses below the average liberal arts requirements, but this is regarded as necessary. The pursuit of "culture" is assigned, as in most engineering and medical curricula, to extra college years or extracurricular time. To avoid the danger of over-crowding the schooling, the Doctorate in geology is preferred wherever possible. Its two added years should permit wider professional education; more browsing in "cultural" pastures; due attention to broader social implications; and some training in the research now increasingly required of the mineral industry. "In-course" training through cooperation between school and industry is especially advo- cated. The Institute should take the initiative in stimulating this practice. Introduction Training a student in geology for a career in the mineral industry is still a moot question, one that is likely to be looked at from many different angles, each of which will reflect the background of the individual considering it. From what follows, the training of petroleum geologists is omitted since, although theirs is an equally important phase of economic geology, it is based upon different essentials. The general subject was recently effectively discussed, but from a somewhat different viewpoint, by Professor McKinstry.' The practical problems that confront the young mining geologist are highly varied and in the eyes of his employer apparently almost any demands seem justified. The mining executive wants from the mining geologist results related mainly to overall operations, reports or forecasts that are largely recordable on paper and chiefly in terms of "discovery thinking." The local mining engineer may have many specific questions of his own, chiefly relating to details of geology that apply to mining practice, which he will address to the mining geologist; these usually deal with production quantities; frequently also they necessitate the immediate handling of pressing but apparently minor matters: shall the drill be moved; how soon will we encounter the watercourse which made so much trouble for us above? The client employing a consultant often wants advice or good judg-

Jan 1, 1949

By H. Wilton Clark

VARYING in thickness and in number from place to place, coal seams in the Canadian Rockies also range in pitch from nearly horizontal to vertical, sometimes with overturns. Over the entire coal-bearing area there are considerable differences of rank in coals of the same geological age, and there are marked differences in ash content and wash-ability characteristics. Correlation of seams at mining operations within a few miles of each other has often proved impossible. These factors influence mining methods, and, of course, production results. The oldest coal formations of western Canada are of Lower Cretaceous age, as the carboniferous sediments are marine and contain no coal. Coal is also present in formations of Upper Cretaceous and Tertiary ages. The rank of coal varies from semi-anthracite in some operations in the Kootenay and Luscar formations of the Lower Cretaceous in the Rockies to lignite in the Tertiary fields of the Saskatchewan prairies. Fig. 1 shows the general extent of the formations. The pitching seams, chiefly Lower Cretaceous, occur in the western belt of the Rocky Mountain foothills and the eastern slopes of the Rockies themselves. (The road to Tent Mt. strip pit, elevation 7000 ft, is shown on p. 832.) Formations extend from the U. S.-Canadian boundary for several bundred miles in Alberta and continue for a similar distance in British Columbia. Present geological estimates show a probable reserve of the order of 25,000 million tons of coal ranging from high volatile bituminous to semi-anthracite, with a large percentage of coking coal, constituting one of the major world reserves of that type. It should be noted that although the quoted estimate probably errs on the conservative side, the question of access to the seams in a mountainous terrain will always be a problem; a wide divergence may exist between actual reserves and the quantities of coal economically recoverable. An excerpt from the Canadian government Report of the Royal Commission on Coal 1946 states that conditions favorable to coal formation were intermittent and these intervals relatively brief in comparison with periods in which no coal was formed. Conditions were favorable to the growth or accumulation of vegetation in one area, while fresh water sediments and marine shales were being deposited in other areas. During periods of emergence the coal deposits were subjected to erosion or were covered by coarse sands and gravels from the mountains, whereas during submergence they were covered by fine clays deposited in embayments of the sea. During some of the periods of coal formation, volcanic activity deposited beds of fine volcanic ash and dust with the coal-forming vegetation. Coal deposits reach their greatest development in the mountains and thin rapidly to the east into the plains area, where they are deeply buried beneath younger sediments. For example, in the Fernie area of southeastern British Columbia there are in places 22 seams having an aggregate thickness of 150 ft in a stratigraphic interval of 3500 ft, whereas at Cole-man in the Alberta Crowsnest area the measures are only 800 ft in thickness and contain a maximum of five seams aggregating about 47 ft of coal. At Belle-vue, 10 miles further east, the measures are reduced to 430 ft with only three seams aggregating about 37 ft of coal. Subsequently the tremendous forces involved in the upthrust of the Rocky Mountains produced great displacement of the coal-bearing formations and at the same time a change in geologically young coals from low to high rank. The floor or footwall of most seams consists of carbonaceous shales, which are almost as adaptable to bending as the coal seams themselves. The seams show very few cleats or cleavage planes and have been so weakened structurally that as mined 50 pct or more will pass through a ¼-in. screen, seldom

Jan 1, 1955

By Earl H. Miller, Henry H. Bruhn

COMMERCIAL beds of sylvite ore were discovered by the Snowden & McSweeney Co. while drilling a wildcat oil well some 25 miles northeast of Carlsbad, N. NI., in 1925. After a preliminary core drilling program the U. S. Potash Co. sank a 1060-ft shaft within 4 miles of the original discovery. This shaft was in an isolated location in a sand desert area with only the roughest of dirt roads connecting it with the neigh- boring town of Carlsbad some 21 ½ miles west.

Jan 6, 1954

Discussion of the paper of H! M. CHANCE, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 91, July, 1914, pp. 1461 to 1466. R. V. Norris, Wilkes-Barre, Pa.-In his resume of coal-taxation methods Mr. Chance has apparently confined his investigation to bituminous coal, so a summary of the anthracite situation as to coal assessment should be of interest. The anthracite region of Pennsylvania in its 484 square miles of measures lies in the counties of Wayne, Lackawanna, Luzerne, Carbon, Schuylkill, Northumberland, and Dauphin, and in each of these different methods of assessment have been adopted. The assessments for taxation in Pennsylvania are made under Acts of the Legislatures of 1841 and 1842, under which the assessors are re¬quired to "assess rate and value every subject of taxation according to the actual value thereof, and at such rates and prices as the same would bring at a bona fide sale after due notice." Under this general law coal land has been assessed as such, but up to about 25 years ago the coal was assessed at rates so low as to be unimportant, though the rates in each township and municipality, even in the same county, showed no agreement or ascertainable basis. In the late '80s, the need for greater revenue drew attention to the possibilities of collecting much larger taxes from the coal lands and, spurred by public demand, the assessing authorities in some counties undertook a reassessment of coal. The method pursued was to demand from each owner a statement of the area and average remaining thickness of coal on his lands. On this return, made in some cases under oath, an assessment based on foot-acreage was levied, with a resulting great increase in valuation, but the valuation per foot-acre was low and no serious objection was made. This assessment with occasional increases of rate remained in force until 1907, when, in the triennial assessment of that year, a complete revision of the valuation was again attempted, engineers were employed by the counties to check the accuracy of the returns from the owners, and, based on the foot-acreage thus obtained, an enormous increase, to $65 per foot-acre, was made in the valuation. This assessment was resisted in the courts by appeals resulting in very extensive litigation, and a final determination of the validity of the 1907 and all subsequent assessments has not yet been obtained. In the first appeals tried the rate calculated on a foot-acre valuation was reduced by the Luzerne County court to about $45, while the. Lackawanna County courts reduced a larger rate to $67. The county authorities were, how-

Jan 4, 1915

By A. M. Starfield

The study of strain waves in rock over the past decade has, for the most part, been an investigation related, but not applied, to rock blasting; the design of rock blasts has proceeded on a basis that is independent of strain wave research. This duality is reflected in the paper by Dr. Clark.1 While the greater part of the paper is devoted to a discussion of spherical waves in elastic and visco-elastic media, it is in an entirely unrelated section, the section on scaling and cratering, that the practical approach to rock blasting is found. Work done by the U. S. Bureau of Mines, as described in the paper by Duvall, Atchison, and Fogelson,2 has established a correlation between crater dimensions and the peak compressive strain in the rock. Strain wave measurements have thus been used to compare explosives but have not, as yet, been applied to the planning of a production round once an explosive has been selected. The optimum burden, for instance, is still determined either by experience, empirical formulae (e.g. that of Langefors 3), or a cratering experiment and the theory that has been developed around that proposed by Livingston.4 Even then there is some ambiguity in applying deductions from short, concentrated explosive charges to the long charges often used in practice (although Bauer 5 reports doing this with considerable success) and wave theory has until recently thrown no light on this problem, being confined, with only a few exceptions, to spherical charges. The hesitation in applying strain wave theory has probably been due to two questions that have not been answered satisfactorily: just how important is the strain wave in rock breakage, and if it is important, under what conditions will the wave break rock? This paper is an attempt to answer the first question, to avoid the second question by an admittedly oversimplified assumption, and then to investigate the implications of this assumption for blasting with long cylindrical charges.

Jan 1, 1967

For the third year in a row total value of the Nation's mineral production broke all previous records. A new peak of $20.4 billion was reached in 1964. So says the U. S. Bureau of Mines. The Bureau's preliminary estimate for 1964 is $800 million higher than the value reported for 1963, and $1.6 billion greater than the 1962 figure. The unprecedented demand for minerals, has stimulated development of new mines and expansion of processing capacity in many parts of the country.

Jan 2, 1965

By W. A. Backofen

THE texture of cold-drawn copper wire has been described most often as a composite of [Ill] and [loo] directions aligned parallel to the wire axis.' Hibbard2 suggested that sufficient reduction will result in a single [111] texture and reported that after a reduction in area of 96.4 pct, such a texture was nearly obtained. Other work3-4 has shown that recrystallization within the temperature range of 300" to 1000°C does not alter the texture established by cold-drawing. In general, however, the texture of cold-drawn end annealed copper wire is not as well defined as the deformation texture. In the work reported here it was found that the double-fiber, deformation texture persists even after a reduction in area of 97.3 pct, and after recrystallization the texture is practically all [l00]. The wire used in this work was prepared in the following way. A 3/4-in. diam length of annealed OFHC copper was cold-drawn to a diameter of 1/8 in., a reduction in area of 97.3 pct. Each step in the drawing operation brought about a reduction in area that varied from 6 to 10 pct. Short lengths of this wire were etched in a 50-pct solution of nitric acid to a diameter of approximately 0.01 in. The texture of the cold-drawn specimens was determined with the conventional X-ray transmission diffraction technique using filtered copper radiation. The X-ray beam was directed perpendicularly to the wire axis and the diffraction rings were recorded on a flat film. Fig. la is typical of the photo-grams obtained and reveals that the cold-drawing schedule described above introduces a distinct, double-fiber texture with both [Ill] and [l00] directions aligned parallel to the wire axis. Supplementary measurements with a Geiger-Mueller counter of the intensity of reflection from (111) planes showed that the [111] component was much more predominant than the [l00]. Additional specimens of the drawn and etched wire were annealed in a salt bath at temperatures from 300" to 450°C. The texture of the recrystal-lized wire was studied with the same technique applied to the cold-drawn wire. Fig. lb is an X-ray photogram of a specimen annealed for 1 ½ at 300°C and is typical of those obtained from re-crystallized specimens. The photogram shows that recrystallization of this material is accompanied by the almost complete elimination of the [111] component of the deformation texture. A pronounced strengthening of the [100] component was evident from intensity measurements with a Geiger-Mueller counter. In summary, the deformation texture of cold-drawn OFHC copper wire, after a reduction in area of 97.3 pct, may still be described as a composite of [Ill] and [loo] directions aligned parallel to the wire axis. Recrystallization of such wire at temperatures from 300" to 450°C introduces a texture which consists almost entirely of a [loo] alignment. Acknowledgment Sidney Rolle of the Scomet Engineering Co. generously supplied the OFHC copper used in this work. References 'C. S. Barrett: Structure of Metals. p. 382 (1943) New York. McGraw-Hill Book Co. 2 W. R. Hibbard, Jr.: Trans. AIME (1949) -185, p. 598; Journal of Metals (Sept. 1949) TN 19E. 3 P. 422 of ref. 1. 'E. Schmid and G. Wasserman: Ztsch. Physik (1926) 40, p. 451.

Jan 1, 1952

ALABAMA America.-Foreman, J. T. Ashland.-Sturdevant, J, C. Altalla; Henderson, R. M. Bessemer.-Ball, E. M. Maschmeyer, W. L. McKenzie, W. C., Jr. Birmingham.-Abbott, C, E. Aldrich, T. H. Aldrich, T. H., Jr. Aufderhaar, H. C. Berg, H. A. Blair, C. S. Bush, M. W. Clark. G. H.

Jan 1, 1929

America.-Foreman, J. T. Ashland.-Sturdevant, J. C. AItalIa. Henderson, R. M. Bessemer.-Ball, E. M. Maschmeyer, W. L. McKenzie, W. C., Jr. Birmingham.-Abbott, C. E. Aldrich, T. H. Aldrich, T. H., Jr Aufderhaar, H. C. Berg, H. A. Blair, C. S. Bush, M. W. Clark, G. H.

Jan 1, 1923

Discussion of the paper of Earl S. Bardwell, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 79, July, 1913, pp. .1429 to 1441. H. O. HOFMAN, Boston, Mass. (communication to the Secretary*) :-It is pleasing to the originators of the planimetric determination of oxygen in refined copper to see that the method has been taken up by a large smelting plant to be used in every-day work after it has been simplified to suit the new conditions. Several years ago Huntington and Desch 1 had improved our mode of working. They projected the developed negative on to a screen, traced the outlines of the picture with a pencil, drew a border, and measured one constituent with. the planimeter. In order to give the work greater precision, they divided the area into squares of 1 cm. side, shaded the

Jan 11, 1913

University of Alabama University, Alabama Mining and Metallurgical Society WILLIAM S. SPRINGER, President ROBERT E. MEAD, Secretary J. R. CUDWORTH, Faculty Sponsor MILTON H. FIES, Counselor University of Arizona Tucson, Arizona Miners' Society PERCY E. COE, President W. JAMES THOMAS, Secretary E. P. MATHEWSON, Faculty Sponsor B. R. HATCHER, Counselor

Jan 1, 1937