Search Documents

RECENTLY seven Boy Scouts were chosen from all the troops in the United States for their all-around ability, excellence in' scouting, and special ability as writers. Two of the members of this selected group were sons of In-stitute members. In the accompanying illustration, Ber-nard Queneau, son of A. L. J. Queneau, of the U. S. Steel. Corp., can be seen at the extreme left, just behind Theo-dore Roosevelt, who is shaking hands with the boy next to. Carl Zapffe (standing in the middle with his hands behind him), the son of Carl Zapffe, manager of the iron ore prop-erties of the Northern Pacific Railroad.

Jan 6, 1928

MISCELLANEOUS U.S. 0,029,598 - Extraction of vanadium values from vanadiferous iron oxide ore. A pelletized mixture of ore, limestone and bentonite is roasted in an oxidizing atmosphere to form calcium vanadates, the calcine ground, the ground material leached with aqueous ammonium carbonate or sodium carbonate to produce a vanadium-rich solution while leaving an insoluble residue of calcium carbonate and/or calcium bicarbonate along with undissolved iron values, and the solution separated and treated for its vanadium content. This patent is a reissue of U.S. Patent No. 3,853,982, dated Dec. 10, 1974. C. B. Bare and J. W. Pasquali, assigned to Bethlehem Steel Corp. Mar. 28, 1978. 7 pp. (423-68). Filed: 3-3 1-77 (783,352).

Jan 1, 1979

"The Southern Cross mining district was discovered during the early rush of gold seekers over Montana following the discovery of gold in 1861. Placers were worked near the Atlantic Cable mine in 1866, and soon attention was turned to quartz lode mining. High grade ores were discovered in the North Atlantic claim, adjoining the present Southern Cross group. The early metallurgical treat¬ment of these ores was by means of arrastres, a crude form of amalgamating mill, illustrated on the page opposite. This old arrastre located by the roadside on Warm Springs creek, was built by Barker Bros. in 1879. Further discoveries overtaxed the capacity of this plant, and in 1875 Thomas' Stuart employed a contractor named Jeptha J. Corner to convert the old Wilson & Fifer sawmill located at the Big Spring into an up-to-date gold quartz mill. 'For this trans¬formation Corner received the sum of $1,400.00. The illustrations give a good idea of the nature of its construction. Practically no iron was used in the mill, excepting for the stamps, dies and cams and cam shafts. Whether or not the saving attained reached the limits of present day perfection is not known. There being no steam boilers available, the early prospectors believed in the principle of conservation of fire wood, water power was therefore used, generated by a ""direct-connected"" over-shot wheel. Water for power purposes was supplied by the nearby spring. History fails to record the tonnage treated in this relic of early Montana milling practice.The ores of the Southern Cross district have not proved readily amenable to mill treatment, but being largely composed of iron oxides, they are most desirable fluxing ores for smelter operations. The B. A. & P. Ry. extends into the district. Electric power is furnished by the Flint Creek 'station, three miles distant."

Jan 1, 1913

By William I. Gardner

Optimum design of a structure obviously requires a thorough knowledge of the materials to be utilized in its construction. When the structure is a tunnel, a most important element in its design and construction is the geology. As a tunnel may be many miles in length and at depths of hundreds or thousands of feet, we face a real problem to meet the needs of the designer and builder. How can we determine the properties of our construction materials in this situation? Engineering geology has had a formidable challenge to meet the requirements of conventional excavation methods; the advent of machine methods for rapid excavation compounds the requirements for more detailed and more precise geological knowledge of the tunnel site. This chapter will discuss the means now at our disposal to meet the challenge to produce the required data on the tunnel site in the preconstruction stage. Our considerations will be directed towards construction of a free-flow tunnel, primarily in fractured rock formations, without any requirements for the rock mechanics type of in-situ tests that might be made for a pressure tunnel or for a large opening for an underground power plant. In essence the investigation must determine: (1) The geologic conditions affecting the type of construction equipment and excavation method of the rock to be broken and removed. (2) The quantities of water and gas to be encountered. (3) The strength and stability of the material surrounding the bore and its need for support and lining. GEOLOGICAL FACTORS AFFECTING TUNNEL DESIGN AND CONSTRUCTION The engineer or contractor may classify the rock as either competent or incompetent or more pointedly as "good" or "bad" ground. The geologist may bestow a precise petrographic name upon the rock, such as granodiorite or indurated tuff breccia or name the formation, as Mancos shale, for

Jan 1, 1970

By Douglas R. Shaw

Normal dodecyl mercaptan was evaluated as a collector for flotation of sulfide minerals and precious metals. The reagent is from the class of normal mercaptoalkanes (n-alkyl thiols), and is commercially available in the form of a mixture of n-dodecyl mercaptan, the primary constituent, and a water-soluble dispersant, under the trade name Pennfloat™ 3. * Reported are results of bench-scale flotation experiments on many commercially treated base metal and precious metal sulfide ores. Dosages, points of addition, and flotation pH were among the variables studied. Most notable results were increased copper, molybdenum, and precious metals recoveries. Dosages of dodecyl mercaptan on some ores were considerably lower than required for conventional collectors. The reagent was shown to be a highly effective and versatile collector on virtually all of the more than 30 sulfide ore types examined.

Jan 1, 1982

By Sherwin F. Kelly

The Geophysics Education Committee was organized in 1938 and presented its first report at the A.I.M.E. annual meeting in February, 1939, at a session held jointly with the Committee on Geophysical Methods of Exploration. REPORT OF 1939 The first task the Committee set itself was to find out in which universities the subject of geophysics was being taught, and the manner in which such instruction was given. A questionnaire was drawn up and sent out to 147 universities in the United States, Canada, and abroad. Of these 100 replied. Their answers were then tabulated and analyzed, yielding the information summarized in the following pages. Two universities, Colorado School of Mines and St. Louis University, actually maintain departments of geophysics, while 3 Canadian and 31 American universities give courses on the subject. In other institutions, 45 in the United States and 5 in Canada, more or less extended reference is made to geophysics in lectures on other subjects. Altogether, there are at least 86 universities in the United States and Canada at which students may obtain instruction of some kind in geophysics. To enter the courses in geophysics given by 33 American universities, certain prerequisites are demanded, varying with the level at which the subject matter is treated. In analyzing the prerequisites, some assumptions had to be made: one year of college mathematics was taken to mean up to, but not including, calculus, while three years was presumed to embrace a course in differential equations. On this basis, 16 per cent require only elementary college mathematics, 40 per cent require differential and integral calculus, and 31 per cent require differential equations. A few demand even more advanced mathematics, while some list no prerequisite mathematics beyond high school. Evidently a student contemplating the study of geophysics should ground himself in calculus and differential equations. In physics, similar assumptions have been made as to time required in the subject. All of the universities giving geophysics require their students to take physics first, and 34 per cent require a standing in

Jan 1, 1940

By Sherwin F. Kelly

The Geophysics Education Committee was organized in 1938 and presented its first report at the A.I.M.E. annual meeting in February, 1939, at a session held jointly with the Committee on Geophysical Methods of Exploration. REPORT OF 1939 The first task the Committee set itself was to find out in which universities the subject of geophysics was being taught, and the manner in which such instruction was given. A questionnaire was drawn up and sent out to 147 universities in the United States, Canada, and abroad. Of these 100 replied. Their answers were then tabulated and analyzed, yielding the information summarized in the following pages. Two universities, Colorado School of Mines and St. Louis University, actually maintain departments of geophysics, while 3 Canadian and 31 American universities give courses on the subject. In other institutions, 45 in the United States and 5 in Canada, more or less extended reference is made to geophysics in lectures on other subjects. Altogether, there are at least 86 universities in the United States and Canada at which students may obtain instruction of some kind in geophysics. To enter the courses in geophysics given by 33 American universities, certain prerequisites are demanded, varying with the level at which the subject matter is treated. In analyzing the prerequisites, some assumptions had to be made: one year of college mathematics was taken to mean up to, but not including, calculus, while three years was presumed to embrace a course in differential equations. On this basis, 16 per cent require only elementary college mathematics, 40 per cent require differential and integral calculus, and 31 per cent require differential equations. A few demand even more advanced mathematics, while some list no prerequisite mathematics beyond high school. Evidently a student contemplating the study of geophysics should ground himself in calculus and differential equations. In physics, similar assumptions have been made as to time required in the subject. All of the universities giving geophysics require their students to take physics first, and 34 per cent require a standing in

Jan 1, 1940

By C. O. Brawner

FACTORS THAT INFLUENCE STABILITY AND STABILIZATION METHOD The most effective stabilization method and design can only be developed if the cause(s) and mechanics of the slide are known. Therefore, it is important that the stability be evaluated by an engineer who has had extensive rock stability experience. The most important factors that influence stability are structural geology, ground water, blasting and the mining method or methods. Structural Geology - The majority of failures in rock slopes occur along discontinuities in the rock (joints, bedding planes, shear or fault zones, etc.). Therefore, on all surface mining projects, the development and maintenance of a comprehensive structural geologic mapping program should be a first priority program that is considered a part of the operations function. This program should include mapping all major features - faults, shear zones and through going joints. All structural features which could influence stability should be mapped and presented in a structural domain format for the entire mine (Canmet, 1977). Where planes, wedges or blocks will be undercut by the mining excavation, shear strength and strain to failure tests should be performed on the joints, fault gouge and gouge-rock contact surfaces. These tests must be performed on the samples in the direction of potential slide movement and must determine the range of peak and residual shear strength values. A preliminary assessment of friction angle can be obtained from measurements of failed surfaces in the field (Figure 1) or from core sliding tests (Barton, 1981). An assessment must be made of the past geologic history of

Jan 1, 1983

By K. I. Savage, S. C. Sun

This paper describes a process developed to recover coal, clays and pyrite from coal wastes. The process consists of fine grinding followed by coal and pyrite flotation which leaves the clays in the flotation pulp. A bituminous coal refuse containing 10% sulfur and 30% carbonaceous material was treated by this method to yield a coal product containing 4% sulfur, 10% ash; a pyrite product containing 45% sulfur (84% FeS2), 1% carbonaceous material; and a clay product containing 2% sulfur (3.5% FeS2). The coal yield was about 89%. The pyrite yield was about 77%. The process steps may be entirely flotation, or gravity separation (hydrocycloning) may be used to increase the pyrite : coal ratio in the flotation feed. Cost estimates for the process show a profit of $2.28 per ton of low pyrite grade refuse, but these do not include labor, maintenance, overhead and plant depreciation. The development of this process consisted of three parts: (1) exploratory tests, (2) op-timazation tests and (3) confirmatory tests. The objectionable qualities that sulfur imparts to coal have been commented upon from early times, and they have become more objectionable as the uses of coal have grown. In whatever form coal takes — raw, carbonized or gasified —the sulfur content remains objectionable, and therefore its compounds are removed as completely as possible. It has long been known that sulfur occurs in coal in different forms. In 1861, sulfur was said to exist in the state of sulfuric acid in combination with a base; in combination with iron as iron pyrites; as bisulfides of iron; and in combination with the organic elements of coal.' Pyritic sulfur is a term loosely used to cover the sulfur associated with iron in its various forms. The mineralogically recognized forms are pyrite (FeS2), pyrrhotite (Fe 1-x S) and marcasite (FeS2). The particle sizes of pyrites vary widely. Isolated grains of marcasite smaller than 15 microns have been found disseminated through coal.2 Hair-like "veins" of pyrite filling cracks in vitrain have been found. At the other extreme, lumps or nodules of pyrites large enough for removal by hand picking have been encountered. Organic sulfur, unlike pyritic sulfur, does not exist as discrete particles, but is instead intimately associated with the coal structure and thus it is impossible to remove it or reduce its concentration by physical or mechanical means.2 In the preparation of coal for its various markets, the pyrite minerals (pyrites) are separated from the raw coal feed. This separation process concentrates the pyrites in the tailings or other waste products. It would be desirable to recover these pyrites for three reasons: (1) Pyrites are potential sources of sulfur and iron. In 1967, for the fifth consecutive year, Free World consumption of sulfur exceeded production.3 Propelled by the shortage, the domestic price of sulfur has risen from $24 to $38 per long ton (bright). (2) The refuse, when placed in piles, becomes ignited. The pyrites (FeS2) bum, giving off SO,. Thus, the pyrites are a cause of air pollution. (3) Also, the pyrites undergo chemical reaction when exposed to air. The refuse is leached by waters which result in stream pollution due to the water-soluble iron and acidic reaction products. Coal refuse also contains coal minerals and clay minerals. Therefore, any process for recovering the pyrites must successfully separate them from the coal and clay minerals. In the study discussed here, ten different bituminous coal refuse samples were successfully upgraded in pyrite content. These samples represented a wide variety of coal waste materials from Pennsylvania and other states. The variabilities of the sulfur and coal contents are shown in Table I. The extremes are Sample J, a high sulfur-low coal, and Sample B, a low sulfur-high coal. Definitions of some of the symbols or terms used in this report are given below: Mesh size—Tyler standard mesh screen sieves with an opening based on the square root of two. Fe —Indicates iron, as determined by a stannous reduction-dichromatic oxidation method. S—Indicates sulfur, as determined by the ASTM "Eschka" method for sulfur in coal.

Jan 1, 1969

ZAY JEFFRIES, who has been awarded the Douglas medal, established in 1922 by a group of the friends of the late James Douglas for distin-guished achievement in non-ferrous metallurgy, is one of the most notable graduates of the South Dakota School of Mines where he took his B. S. degree in 1910. The following year he was manager of the Ideal Mining Co., at Custer, and in 1911 he became instructor in metallurgy at the Case School of Applied Science, Cleve-land, where he remained until 1917, and in 1918 he took his D. Sc. degree at Harvard. During all this period he was engaged in experi-mental and consulting work for the Electric Railway Improvement Co., t h e Cleveland Steel Tool Co., the W. S. Tyler Co., the Lincoln Electric Co., the Aluminum Castings Co., and the Cleveland wire di-vision of the General Elec-tric Co. He is now en-gaged in general consulting work, especially for the Aluminum Co. of America, the General Electric Co., and the National Tube Co. He has contributed to the Transactions papers on the determination of grain size in metals (with A. H. Kline and E. B. Zimmer) LIV, 594; grain growth phenomena in metals, LVI, 571; the tungsten-molyb-denum equilibrium diagram and system of crystalliza-tion, LVI, 600; grain size inheritance in iron and carbon steel, LVIII, - 669; effect of temperature, de-formation and grain size on the mechanical properties of metals, LX, 474; metallography of tungsten, LX, 588; physical changes in iron and steel below the thermal critical range, LXIII, and LXVII, 56; and the trend in the science of metals, LXX, 303. In addition to participating freely in the discussion of other papers before the Institute he has found time to contribute notable papers to the Institute of Metals (Great Brit-ain), the principal technical journals, and to write a book on "The Science of Metals" in collaboration with R. S. Archer.

Jan 2, 1927

By Harold M. Mooney

WHEN apparent resistivity data are taken with the symmetrical Wenner 4-electrode spread, a fixed center position is used and readings are taken for values of electrode separation. Basic data consist of apparent resistivity plotted against separation of adjacent electrodes . The interpreter attempts to infer geologic structure, such as the depth to discontinuities and the nature of subsurface earth materials. An earlier paper' described methods for interpreting resistivity data. All of these involve a severe assumption, namely that the earth in the region of interest consists of horizontal layers, electrically homogeneous and isotropic. The actual earth never satisfies this assumption exactly and may deviate from it so much that none of the above methods can be applied. Attempts in three directions have been made to modify the assumption so that it approaches known geologic complexity more closely. First, curves have been calculated for dipping discontinuities. Stern' and Aldredge hose a few widely separated dip angles. Trudu confined his attention to small dips. Berel'kovskiy and Zubanov computed gradient curves for widely separated dip angles. Unz as given the most complete solution, with a brief attempt to treat the three-layer case. Second, anisotropy can be taken into account. It seems geologically probable that layered materials have different vertical and horizontal conductivities. Cagniard, Maillet, and Pirson et up methods for finding an equivalent hypothetical isotropic medium. Standard interpretation methods can be applied to this, and the actual medium can then be deduced. Belluigi'" discounts the practical importance of anisotropy; Geneslay and Rouget do not agree with his conclusion. Third, the effect of variable resistivity in a layer can be considered. Keck and Colby" examine the mathematics of an exponential increase in a surface layer. Several authors, for example, Stevenson,'' consider a continuous variation of resistivity with depth. The present paper deals with a linear variation of resistivity in a surface layer. Geologically, surface variations should be expected. Unconsolidated materials such as glacial drift show marked irregularities over short distances. The effects of weathering change with depth. The moisture content of material above the water table may vary from a dry sand to a saturated clay, and both of these will be changed by rainfall. Figs. 1 to 6 present apparent resistivity curves to show the effect of a variable surface layer. In all cases resistivity varies linearly with depth down to a depth of one unit. Material beneath this depth has constant resistivity. Electrode separation is plotted in depth units. Insets on each figure show the corresponding cross-sections, plotting true resistivity against depth. To illustrate, consider curve A of Fig. 1. The true resistivity of material at the surface of the earth is taken as 0.4 units. Resistivity increases with depth, reaching a value of 1.0 at 0.5 depth units and 1.6 at 1.0 depth units. Below a depth of 1.0, all the material has very low resistivity (zero, for purposes of calculation). Curve A in the main part of Fig. 1 shows how apparent resistivity varies for this case as the electrode spacing is increased. To illustrate further, curve E of Fig. 4 corresponds to true resistivity of 1.2 units at the surface, 1.0 at a depth of 0.5 units, 0.8 at a depth of 1.0, and 1.5 for all depths greater than 1.0. Apparent resistivity curves have been plotted logarithmically so that the shape of the curves becomes independent of the units, giving the curves wide validity. A certain drift-covered area, for example, shows a gradual decrease of resistivity from 230 ohm-meters at the surface to 150 ohm-meters at the bedrock surface, 275 ft down; bedrock resistivity is 800 ohm-meters. Curve E of Fig. 5 indicates that true resistivity decreases from 1.2 units at the surface to 0.8 at a depth of 1.0, then increases abruptly to a constant value of 4.0 units. Since resistivity and depth ratios are the same, this can be used to predict the field curve. For Fig. 5, multiply true resistivity and apparent resistivity by

Jan 1, 1955

By Albert D. Brokaw

The accompanying charts are presented to extend and improve a chart published under the title "A Chart to Provide Approximate Correction for Temperature and Deviation from Boyle's Law."' The applicability of this earlier chart was limited by the fact that it was based on the work of Burke and Keyes² and Kvalnes and Gaddy3 whose experiments were conducted with pure methane, the adjustments suggested for natural gases of higher specific gravity were unsatisfactory except within limited ranges of temperatures and pressures, and precise interpolation was difficult. The extensive work of G. G. Brown, D. L. Katz and their associates on the heavier natural gases has provided better bases for the needed corrections, and the present charts. which are based largely on their work, are intended to simplify the computations involved. The design of the charts has been changed by plotting temperatures as a function of pressure and correction factor, on a semilogarithmic or "ratio" grid, which gives fairly even spacing of the graphs and simplifies interpolation. Charts have been prepared for natural gas with specific gravities of .60, .65, .70, .75 and .80. The standard computation for use in estimating the quantity of gas in a reservoir may be expressed as follows: _ PA X 520 X VR ZT where: Q is the volume of gas at 60°F and one atmosphere pressure PA is the absolute formation pressure in atmospheres

Jan 1, 1949

By Albert D. Brokaw

The accompanying charts are presented to extend and improve a chart published under the title "A Chart to Provide Approximate Correction for Temperature and Deviation from Boyle's Law."' The applicability of this earlier chart was limited by the fact that it was based on the work of Burke and Keyes² and Kvalnes and Gaddy3 whose experiments were conducted with pure methane, the adjustments suggested for natural gases of higher specific gravity were unsatisfactory except within limited ranges of temperatures and pressures, and precise interpolation was difficult. The extensive work of G. G. Brown, D. L. Katz and their associates on the heavier natural gases has provided better bases for the needed corrections, and the present charts. which are based largely on their work, are intended to simplify the computations involved. The design of the charts has been changed by plotting temperatures as a function of pressure and correction factor, on a semilogarithmic or "ratio" grid, which gives fairly even spacing of the graphs and simplifies interpolation. Charts have been prepared for natural gas with specific gravities of .60, .65, .70, .75 and .80. The standard computation for use in estimating the quantity of gas in a reservoir may be expressed as follows: _ PA X 520 X VR ZT where: Q is the volume of gas at 60°F and one atmosphere pressure PA is the absolute formation pressure in atmospheres

Jan 1, 1949

By H. Gisser

Recent experimental work has demonstrated (1)2 that ammonia and oxides of nitrogen are formed during the aging of smokeless powder. This is significant in connection with the problem of "season cracking," or stress corrosion of brass cartridge cases in view of other work(1) indicating that stressed and "stress- relieved" cases stored with small quantities of added ammonium nitrate crack on firing. The deterioration of stressed brass by ammonia has been known for some time(z) and it appears therefore that stress- corrosion cracking of brass cartridge cases is intimately associated with the so-called "powder volatiles," ammonia and oxides of nitrogen, both of which are decomposition products of smokeless powder. Working on the hypothesis that any barrier which prevents the powder volatiles from reaching the brass surface will reduce the incidence of stress-corrosion cracking, it was considered desirable to investigate the use of organic resin films to accomplish this purpose. The possibility of formation of ammonia within the nitrocellulose powder charge and by reduction of nitrogen oxides on the surface of the brass case requires that the barrier film be resistant both to ammonia and oxides of nitrogen. The film must also be impermeable to ammonium salts, either solid or in solution, since these salts and water necessarily appear within the powder charge. The usefulness of the

Jan 1, 1945

By John W. Cloud

The delivery of blows upon roadway structures by the locomotive engine at high speed, althongh long recognized, has, perhaps, not been as generally understood in severity, relation to speed, and cause as is desirable in matters of such importance. Some points of explanation, with illustrative disgrams, are, therefore, submitted to your attention, preparatory to a note 011 " Steel for Bridges," also submitted. In order that a locomotive may run at high rates of speed with-

Jan 1, 1881

THREE-QUARTERS of the amount needed to defray the cost of the Louvain memorial clock and carillon has been subscribed by one-thirtieth of the total number of mem- bers of the engineering societies that are indorsing this memorial to the engineers who gave their lives in the Great War. Gifts of materials and services have been made, but about $20,000 is still needed to meet the total expense involved. Small contributions from the twenty-nine-thir- tieths of the total membership who have not yet subscribed should promptly provide this sum. The accompanying illus-tration shows the 48 gold stars made by the American Brass Co. for the four faces of the clock, being boxed for shipment at the works of the Dwight & Lloyd Co. at Netcong, N. J. The actual material of the stars is, of course, an aluminum bronze, which retains its gold color without tarnishing.

Jan 5, 1928

By R. G. Ward, D. R. Gaskell

Using the maximum bubble pressure technique, the densities of iron silicates at 1410°C have been measured blowing helium, nitrogen, and argon. By ensuring equilibrium between the melt and the blowing gas with respect to oxygen potential and by minimizing tempcrature cycling of the furnace, iron precipitation in the melt has been prevented. Thus the previously reported effect of blowing-gas composition on the densities of the melts has been eliminated. Consideration of the oxygen densities of the melts gives an indication of the structural changes accompanying composition change. The density-composition relationship of iron oxide-silica melts in contact with solid iron has been the subject of several investigations1-7 and considerable disparities exist among the various results obtained. Of these investigations, all except one5 have employed the maximum bubble pressure method. In the most recently reported of these investigations1 the density-composition relationship obtained blowing nitrogen differed from that obtained blowing argon. The measured densities obtained under nitrogen were greater than those obtained under argon, the difference being a maximum at the pure liquid iron oxide composition and decreasing with increasing silica content. This observation rationalized the disparities existing among the results of the earlier investigations, showing that two lines, one for nitrogen and the other for argon, could be drawn to fit all the earlier results. No explanation for this phenomenon could be offered. Chemical analysis of rapidly quenched samples of melt for dissolved nitrogen, and direct weighing measurements, excluded solution of nitrogen in the melt from being the cause of the increase in density. The range of blowing gases was extended by Ward and Hendersons who measured the density of liquid iron oxide bubbling helium, nitrogen, neon, argon, and krypton. The measured density was found to decrease smoothly with increasing atomic number of the bubbling gas. The work reported here is a continuation of the program initiated by Ward and Sachdev7 to study the densities in multicomponent melts in which the iron oxide-silica system is the solvent. As such it is necessary to explain or eliminate the anomalous densities of iron silicates under different atmospheres, and the present rede termination was carried out towards this end. EXPERIMENTAL The maximum bubble pressure method of density determination was again employed and the experimen- tal apparatus used was essentially the same as that used by Ward and Sachdev.7 A molybdenum-wound resistance furnace heated an ingot iron crucible of internal diameter 1 in. containing a 2-in. depth of melt. The bubbling gas was blown through a 1/4 -in.-diam mild steel tube onto the end of which was welded a 2-in. extension of 1/4 -in.-diam ingot iron rod, drilled out to 5/32 in., and chamfered to an angle of 45 deg. The blowing tube was introduced to the furnace through a sliding seal and its position was controlled by a vertically mounted micrometer screw which allowed the depth of immersion to be determined with an accuracy of ± 0.01 cm. A Pt/Pt-10 pct Rh thermocouple was located below the crucible and temperature control was effected initially by means of an on-off controller and later by a saturable core reactor. The bubble pressure was determined by measurement of a dibutyl phthalate manometer using a cathetometer. PREPARATION OF MATERIALS Iron oxide was produced by melting ferric oxide in an inductively heated iron crucible in air. The liquid was quenched by pouring onto an iron plate. Silica was prepared by dehydrating silicic acid at 650°C for 12 hr. RESULTS Before any measurements of the density of a melt were made, the density of distilled water at room temperature was measured bubbling helium and argon. Both gases gave the density as 1.00 ± 0.01 g per cu cm which showed that the density of the manometric fluid (dibutyl phthalate) was not affected by contact with the blowing gas. With the furnace controlled by an on-off temperature controller an attempt was made to measure the density of pure liquid iron oxide by bubbling argon. The furnace atmosphere gas and bubbling gas were dried over magnesium perchlorate and deoxidized over copper turnings at 600°C. It was found that the pressure required to blow a bubble at a given depth increased slowly with time, and thus it was impossible to obtain a unique value for the density of the melt. Inspection of the blowing tube after removal from the furnace showed that rings of dendritic iron had precipitated from the melt onto the immersed part of the tube. This is shown in Fig. l(a) where the various "steps" correspond to different depths of immersion. The precipitation of iron was considered to be due to one or both of two possible causes: i) The composition of the liquid iron oxide is that of the liquidus at the temperature under consideration and can be expressed by the equilibrium

Jan 1, 1968

By L. F. Mashburn, T. J. Ferree

A Reichert cone concentrator was installed in an aggregate plant circuit to recover the extremely fine "flour gold" known to exist in the deposit. The gold content of the bank- run gravels averages about 0.1 g/t-about $1.29/t, based upon $12.86/g ($400 per oz) gold. The fineness of the gold averages between 950 and 960. The Reichert cone, in conjunction with a conventional shaking table, recovers in excess of 85% of the gold. A screen analysis of the gold particles shows 44.1 % is - 74pm (-200 mesh) in size. The plant operates with a two-man crew.

Jan 1, 1983

Unitization—in some form from simple agreements among operators to complete consolidation of ownerships—is a means of obviating the wastes of unrestrained competition among owners in extracting oil and gas from a common reservoir, as well as of adjusting its output to the current needs of its owners. It offers opportunity for application of improved production methods which are expected to increase recovery, decrease developing and operating costs, and assist in stabilizing output.

Jan 1, 1930

By John W. Cloud

THE delivery of blows upon roadway structures by the locomotive engine at high speed, although long recognized, has, perhaps, not been a generally understood in severity, relation to speed, and cause as is desirable in matters of such importance. Some points of explanation, with illustrative diagrams, are, therefore, submitted to your attention, preparatory to a note on "Steel for Bridges," also submitted. In order that a locomotive may run at high rates of speed with-

Jan 1, 1881