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By M. Gensamer, B. Lustman

A recent paper described, by means of stereographic pole figures, the preferred orientations produced by cold-rolling low-carbon steel of automobile-body grade. It was found that the surface of the sheet exhibited a deformation texture significantly different from the texture possessed by the inside of the sheet. Efforts to produce the surface texture by buffing a sample exhibiting the normal or inside texture, using a copper lap, have not been successful. In view of the data collected by Kurdjumow and Sachs2, it was suggested that the surface texture might be the result of partial recrystallization of the normal or inside texture. The recrystallization texture of cold-rolled mild steel was studied by Goss3, but he did not use the pole-figure method, so that his conclusions were in need of verification. For these reasons the work reported in here was undertaken. It had two objectives: (1) to study the general behavior of cold-rolled mild steel on recrystallization below the critical temperature Al, and (2) to attempt experimentally a demonstaration of the genesis suggested above for the surface texture in cold-rolled steel. The material was that used by Gensamer and Mehl, cold-rolled to 97.5 per cent reduction in thickness. Fig. 1 is an X-ray pinhole photo-gram of this material, taken with the beam transmitted perpendicular to the plane of the sheet, using a molybdenum target at 35 kv. with no filter. It is typical of the inside texture, but in it the deformation texture is better developed than in the samples that showed a well developed difference between the inside and surface samples. Specimens from this sheet, which was 0.005 in. thick, were annealed for 5 min. at various temperatures in a lead bath. After about 0.0005 in. had been etched from both surfaces, X-ray photograms were prepared, using the technique described in the earlier paper1. Figs. 2 to 6 are photograms of the annealed sheet, at 566, 571, 577, 580 and 650" C. (1050' to 1202" F.), in order. Fig. 2 shows that 5 min.

Jan 1, 1937

By John Vanderwilt

THE value of molybdenum as a ferroalloy has been known for many years. For a long time, however, the metal was used only on a small scale in the iron industries, because the known source of supply appeared inadequate and the cost to the consumer was not stabilized. The world's production of molybdenum prior to 1914 was only a few thousand pounds per year and even during the war period annual production was only about 800,000 lb. Production during 1929 and 1930, however, was over 4,000,000 lb. per year and that of 1931 promises to be of the same order of magnitude. This remarkable increase in production is due primarily to the development of a large molybdenite deposit at Climax, Lake County, Colo., which has accounted for 80 per cent of the world's production of molybdenum during the past two years. Based on conservative esti-mates, the deposit at Climax has the capacity to maintain its 1929 and 1930 rate of production for 100 years or more. The production of molybdenum ores has been established on a new basis-in recent years as compared with the period during and before the world war. During the earlier period, production came from small deposits and the cost to the consumer fluctuated. At present, production comes from a few large deposits and the price is not only lower but also fairly constant. In recent years the price of molybdenum has consistently dropped as consumption increased. The present price is $0.95 per pound of molybdenum in ferromolybdenum and $0.80 for molybdenum in calcium molybdate. Before and during most of the war, Australia, Norway, and a few other foreign countries were the chief producers, while at present the United States is producing over 90 per cent of the world's production. With molybdenum available at a moderate cost, the steel industry has been adopting more and more the use of molybdenum as an alloy addition. A relatively small demand for molybdenum exists in the chemical and electrical industries, but the recent large increase in con-sumption has in large part been by the iron and steel industries, which

Jan 1, 1932

By R. M. Brick, M. A. Williamson

Certain features of the response of copper and brass to deformation and recrystallization remain obscure. The textures obtained on rolled sheet are listed by Schmid and Boas1 as: No adequate explanation has been advanced for the presence of the secondary deformation texture of copper and its absence in brass or for the origin of the cubic recrystallization texture of copper.2 A recent publication3 attempted to rationalize the above empirically described annealing texture of brass on the basis of retention of the (110) [112] rolling orientation plus twinning about the central octahedral poles of the usual secondary (110) [115] orientation. The difierence in the textures of annealed copper as compared to 70-30 brass is also shown by the difference in the position of ears for drawn copper, at o° and go", as compared with drawn brasses, at 45o, for all compositions between oo-10 and 70-30.4 Data on indi- vidual crystals are as yet too few to permit of an analysis of these textures comparable to that of mild steel as made by Barrett and Levenson.5 Experimental Methods The materials studied included copper specimens cut from the central, equiaxed crystal portion of a tough-pitch wirebar; brass made from this copper and high-purity (99.99 per cent) zinc including alloys of 7 per cent, 15 per cent, 24 per cent, 29 per cent and 36 per cent Zn and large single crystals of 70-30 bras. Sections 1/4 in. thick of the cast polycrystalline copper and brasses were reduced 40 per cent by rolling, recrystallized to a common grain size of 0.045 mm. and then rolled directly to foil 0.002 in. thick. Hardness readings employing both the Vickers and Rockwell machines were taken at intervals during the reduction. For comparison, similar specimens were cross-rolled—i.e., turned through 90° for each pass—and comparable hardness data were secured. Finally sections from the single crystals of brass were cut to obtain the following initial orientations; these sections were rolled, hardness data secured and a complete micrographic record of structural changes obtained.

Jan 1, 1941

By R. M. Brick, M. A. Williamson

Certain features of the response of copper and brass to deformation and recrystallization remain obscure. The textures obtained on rolled sheet are listed by Schmid and Boas1 as: No adequate explanation has been advanced for the presence of the secondary deformation texture of copper and its absence in brass or for the origin of the cubic recrystallization texture of copper.2 A recent publication3 attempted to rationalize the above empirically described annealing texture of brass on the basis of retention of the (110) [112] rolling orientation plus twinning about the central octahedral poles of the usual secondary (110) [115] orientation. The difierence in the textures of annealed copper as compared to 70-30 brass is also shown by the difference in the position of ears for drawn copper, at o° and go", as compared with drawn brasses, at 45o, for all compositions between oo-10 and 70-30.4 Data on indi- vidual crystals are as yet too few to permit of an analysis of these textures comparable to that of mild steel as made by Barrett and Levenson.5 Experimental Methods The materials studied included copper specimens cut from the central, equiaxed crystal portion of a tough-pitch wirebar; brass made from this copper and high-purity (99.99 per cent) zinc including alloys of 7 per cent, 15 per cent, 24 per cent, 29 per cent and 36 per cent Zn and large single crystals of 70-30 bras. Sections 1/4 in. thick of the cast polycrystalline copper and brasses were reduced 40 per cent by rolling, recrystallized to a common grain size of 0.045 mm. and then rolled directly to foil 0.002 in. thick. Hardness readings employing both the Vickers and Rockwell machines were taken at intervals during the reduction. For comparison, similar specimens were cross-rolled—i.e., turned through 90° for each pass—and comparable hardness data were secured. Finally sections from the single crystals of brass were cut to obtain the following initial orientations; these sections were rolled, hardness data secured and a complete micrographic record of structural changes obtained.

Jan 1, 1941

By M. Gensamer

ONLY recently has it been realized that preferred orientations are common in hot-rolled steels. In a recent paper, N. P. Goss1 stated that hot-rolled mild steel exhibits a texture different from that charac-teristic of cold-rolled steel. No complete study of these hot-rolling textures has been reported using the pole-figure method of Wever. The material used in the work reported in this paper was the same material used by Gensamer and Mehl2 in a recent study of preferred orientations in cold-rolled steel, to which reference may be made for the composition and thermal history of the steel. Automobile-body sheet bar, 4 in. thick was hot-rolled at two temperatures, 780° and 910° C. (1436° and 1669° F.). (These temperatures refer to the tempera-ture of the furnace in which the steel was heated.) After each pass the steel was returned to the furnace and held there long enough to return to temperature. Although no accurate method was used to measure the temperature after each pass, it was estimated by color that only a slight drop in temperature occurred. In order to determine the effect of any preferred orientation that might have persisted through the normalizing treatment, one specimen at each temperature was rolled in the same direction as the original working direction and the other at right angles to it. The total reduction in each case was 85 per cent, the specimens having been reduced from 0.250 to 0.0375 in. in five passes. Final cooling was in air. Pinhole reflection photograms were taken of all four specimens, with the rolling direction vertical and the X-ray beam at an angle of 7° with the transverse direction (the transverse direction is defined as that direction in the rolling plane perpendicular to the rolling direction). These photograms, taken with a Me target at 35 kv., are reproduced in Figs. 1, 2, 3 and 4. They show that a more pronounced texture was developed by the low-temperature rolling (780° C.), and that of the two

Jan 1, 1936

By Ionel I. Gardescu

In connection with some of the experiments carried out by the writer on the behavior of gas and oil in a sand reservoir,' an interesting phenomenon was observed which may throw some new light on the problem of recovery of oil from a natural reservoir. The experiments are intended to show the effect of the surface area of the occluded gas masses, originally present in a reservoir, on the further evolution of gas from the oil and its consequent effect upon the rate of production of oil. The apparatus used in the experimental work is shown in Fig. 1. It consists primarily of a sand reservoir R and a displacement chamber D, which is used to induce small variations in volume. The reservoir and displacement chamber form a unit, and a lowering of the plunger D is equivalent to increasing the volume occupied by the oil and gas in the reservoir. The reservoir was first filled with dead oil and maintained under pressure until it was ascertained that most of the free gas had gone into solution. The volume of free gas present in the reservoir was computed from the coefficient of compressibility of the fluids by means of the displacement chamber D, reading to 0.005 c.c. and a special gage J reading to 0.02 lb. per sq. in. The oil was saturated with gas under pressure in reservoir S by circulating the oil for a long period of time through the gear pump B. Subsequently, the saturated oil was circulated through the sand reservoir following the circuit S6, B, S6, R4, the sand reservoir R, R1, R², F4, F1, back to reservoir S. In the following experiments the sand reservoir R was filled with gas-saturated oil at a pressure of 415Ib. per sq. in. with no free gas present. This was ascertained by closing off all the outlet valves and determining the coefficient of compressibility of the system by means of the displacement chamber D. Much difficulty was encountered in eliminating all of the free gas masses from the oil reservoir. The dead oil originally present in the

Jan 1, 1932

By Theodore P. Holt

The Mines Operating Co.'s plant at Park City, Utah, was designed to treat the low-grade fillings in the old stopes of the Ontario mine. These fillings carry 6 to 14 oz. of silver, 1 to 2 lb. of copper, 0.01 to 0.015 oz. of gold, and a small percentage of lead and zinc. The treatment consists in mixing the crushed ore with coal dust and salt and then roasting in a new type of furnace by combustion of the contained fuel. The roasted ore is leached with an acid salt solution to dissolve the silver, gold, copper, and lead. At present these metals are precipitated together on scrap iron and the product sold to a refinery. The only new feature of importance in this scheme of treatment is the roasting process, which makes possible the chloridizing of ores without any loss of the valuable metals, and at a very low cost. History of the Development of the Process The roasting process- had its beginning in connection with research work at the Utah State School of Mines. N. C. Christensen, Jr., who held one of the School of Mines' fellowships, was engaged in some experimental work on blast roasting. At the same time I was doing some work on the insoluble gold in Mercur base ores. Mr. Christensen roasted some of this base gold ore in his pot furnace, and found that when he mixed a sufficiently low percentage of fuel with the ore, it did not sinter but roasted to a leachable product. We considered this a new application of blast roasting, and proceeded to test out a large number of ores in several different types of small roasters which we constructed.. This experimental work continued well into the summer of 1911. In August, 1911, the Consolidated Mercur Gold Mines Co. installed a small roaster of our design, which we proposed to operate on the counter-current principle, feeding mixed ore continuously on top, and at the same time drawing off the roasted ore from the bottom. By proper adjustment we hoped to maintain a permanent roasting zone near the center of the column, the ore moving downward as roasted. However, we

Jan 1, 1915

By M. T. Hepworth, R. Schuhmann

Hydrogen solubility measurements were made on a series of Ti-O alloys, and a portion of the 800°C isotherm for the Ti-O-H system was determined. Activities of oxygen and titanium were calculated from the experimentally measured activities of hydrogen, using ternary Gibbs-Duhem integrations. The data were extrapolated to obtain thermo-dynamic properties of binary Ti-O solutions. The thermodynamic properties of a Ti-0 solid solutions thus determined were compared with properties predicted from interstitial models. The Gibbs-Duhem equation, long used to calculate activities in binary systems, has been extended. recently to ternary systems.1"3 When the activity of one component in a ternary system is known as a function of composition, the activities of the other two components can be calculated from that of the first by an integration procedure, provided certain restrictions are observed on the path of integration. Often the activity of one component in a ternary system can be measured readily, while the activities of the other two components are difficult to measure. Gibbs-Duhem calculations are especially applicable to such systems. The further possibility arises of developing a new and indirect approach to activity measurement in binary systems. The proposed new method for binary systems consists of adding varying amounts of a third component whose thermodynamic behavior is easily measured. The activity of this added component is determined experimentally as a function of composition. Then the activities of the two components of the original binary system are calculated by Gibbs-Duhem integrations and extrapolations. For the work to be described in this paper, the Ti-0-H system was selected as a promising system for evaluating this approach. Investigations of the Ti-H system have shown that the activity of hydrogen can be measured precisely with little difficulty. Pure titanium transforms from a low-temperature a form (hcp) to a higher-temperature /3 firm (bcc) at 882.5"~ The phase transformation occurs in a temperature range where hydrogen pressures are easily measured. Also, the diffusivity of hydrogen at temperatures above 600" or 700"~ is large enough that equilibrium can be reached within a reasonable time.

Jan 1, 1962

By Eric Sinkinson

MANY of the magnesite ores of the western part of the United States contain such large amounts of silica and hydrous silicate minerals that the value of the ores is either low or nominal. Expensive and carefully controlled mining methods are necessary to prevent excessive dilution of the higher grade ores by introduction in mining' of small pieces of the hanging walls or footwalls of the deposit. This difficulty is further complicated by the various states of decomposition of the country rock of the deposits in which many of the ores occur. The problem the authors attempted to solve arose from a request to float an impure magnesite containing varying proportions of siliceous gangue with calcium carbonate. The ore is normally. enclosed in serpen-tine masses, somewhat decomposed, and in mining it wall rock is inci-dentally added, so that variable amounts of siliceous material occur in the samples. The silica, alumina, and iron oxide are so closely associated with the magnesium carbonate in the magnesite that ordinary mechanical separation at coarse mesh sizes is of no avail. It is well known that calcium carbonate can be floated by suitable reagents, therefore it seemed reasonable to suppose that magnesium carbonate minerals would behave in a similar manner, but experimental trial proved that this supposition was unfounded. Therefore the first step in the problem was to find out what differences of behavior there were between magnesium and calcium carbonates under flotation conditions, or when suspended in water. In water at 18° C. magnesium carbonate is slightly more soluble than calcium carbonate; in fact, MgCO3 is soluble to the extent of 0.0106 grams in 100 c.c. of water at 18° C. and CaCO3 to the extent of 0.0013 grams. However, magnesium carbonate in water gradually changes to the basic carbonates of a composition (3MgCO3.Mg(OH)23H20) or (4MgCO3.Mg(OH)25H20), depending upon conditions, and calcium carbonate to calcium hydroxide, Ca(OH)2, The relative solubilities of these hydroxides in water are the reverse of the solubilities of magnesium and calcium carbonates.. The range in published figures for solubility

Jan 1, 1936

By C. R. Fischrupp, M. D. Helfrick, W. A. Straw

In the manufacture of telephone apparatus a number of nonferrous sheet metals arc blanked and formed to produce a wide variety of parts, which are generally small in size because of space and weight requirements. Many are given sharp bends in forming, so that they may be assembled into compact units. This study covered sheet metal of the alloys of brass, phosphor bronze and nickel silver that are most extensively used by our company. In general, the sheets range from 0.005 to 0.100 in. in thickness and from 1/4 hard to extra spring temper in hardness. As many parts function as flat springs, and others require the maximum stiffness for structural reasons, a large percentage of the metal is used in the hard and spring tempers. So, because of the necessity for the minimum radius of bend consistent with the maximum in hardness, there has been a need for information as to the forming characteristics of these sheet metals in the various alloys, tempers and thicknesses. The literature yields relatively little regarding such forming characteristics, so that designers of apparatus and tools have been largely dependent upon past experience or tool tryouts for guidance. In presenting tabular data intended as a basis for selecting the temper of the metal and radius of the bend, we recognize the influence of many other factors which are not covered in this study. For example, the angle of the bend and conditions of the metal, such as grain size and presence of impurities, as well as conditions of the fabricating process, such as rate of forming and adjustment of the tools, may all affect the result. In addition, a bumping operation subsequent to forming, which is frequently used to set the bend, increases the strain on the metal. We wish to emphasize the fact that this is not considered a scientific investigation of the formability of materials or an attempt to correlate forming characteristics with various other properties of the metals, except in so far as such properties are controlled by commercial limits on composition and temper. It is expected, however, that the data presented may serve some useful purpose in estimating the relative formability of different thicknesses

Jan 1, 1931

By N. I. Fisher, J. Shepherd

Abstract-Statistical studies have been carried out on structural geological data collected across a large zone of roof failure 600 m (1968 ft) wide and at least 800 m (2642 ft) long in the Greta coal seam at Aberdare East Colliery. Two swarms of hundreds 2 of minor, normal faults with throws commonly between 3 and 300 mm in the room and pillar workings are broadly coincident with roof failure. The faults have been classified into dip slip and oblique and strike slip types. Roof conditions have been classified into good; troublesome with subclasses scaly, heavy, gutter falls and wide, flat-roofed falls; and severely failed with subclasses very heavy roof, gutter falls and dome falls. Troublesome conditions are defined as those in which the height of the fall is less than or equal to 0.3 m, and severely failed conditions as those in which the fall height is greater than 0.3 m. Comparison of faults, roof conditions and mining rate on a shift basis indicates that faults and roof failure are much more important than machine breakdowns in reducing mining rate. The effect of faults on roof conditions has been quantified using a concept called the "zone of influence, " a rectangular area around a fault in which the fault has potentially deleterious effects. The spatial comparison of fault "zones of influence" with areas of roof failure using Spearman's rank correlation coefficient shows that, while normal dip slip faults do not appear to be associated with roof failure, oblique slip and strike slip faults appear to be associated with roof classed as severely failed. The "zone of influence" of an oblique slip fault may extend up to 3 m on each side of it in the headings and up to 1.14 m in the cut-throughs. The fault "zone of influence" has geomechanical implications for the design of mine openings and possibly represents the maximum length of a cantilevered roof beam likely to fail during mining, owing to a fault. Roof conditions could possibly be predicted in blocks of virgin coal if the type of fault could be identified in oriented drill cores.

Jan 9, 1978

By Robert Parker

Measurements of the latent heat of transformation from a to 0 titanium were made using a pulse-heating technique. Rapid heating was accomplished electrically by discharging a low-inductance capci-tor hank through a thin-strip specimen. Both high-purity titanium and titanium containing 2700 ppm of 0 were studied. An electrical-resistivity technique and a plot of energy input us temperature rise were used to monitor the phase change. It was concluded that: 1) the latent heat of transformation is 800 i 48 cal per mole; 2) phase change occurred in less than 200 sec; and 3) the percentage phase change that occurs is linearly a function of the energy available for phase change. In addition, this experiment provides a simple and inexpensive method for determining specific heat of electrical conductors over large temperature ranges. The chief advantages of this technique over past pulse-heating experiments are: 1) static measurements of capacitor-bank voltage capacitance and specimen resistance can be made quickly and accurately to determine the energy supplied to the specimen; 2) the specimen is heated so rapidly (10 µ sec) that there is no appreciable heat loss during the heating. THE purpose of this paper is to illustrate the use of the capacitor bank as a tool for basic experimental investigations and to determine the rapid phase-change kinetics of titanium. The capacitor provides a number of unique properties: 1) rapid heating rates in the order of l09oC per sec can be obtained; heating rates as slow as l04oC per sec are available by merely adding a given amount of inductance to the circuit; 2) the energy input can be precisely determined and can be varied from several joules to millions of joules, depending on the bank capacitance and voltage; 3) the specimen can be heated uniformly through the thickness and length or non-uniformly, as desired; 4) the apparatus is simple and inexpensive and can be easily altered; 5) the form of the specimen can be wires, sheets, foils, rods, and cylinders; 6) there is great precision in the timing of events; 7) this technique may be readily used in conjunction with rapid cooling.

Jan 1, 1965

By R. W. Parsons

wben a displacement front encounters an isolated permeability heterogeneity, it will be perturbed. The details of this perturbation will depend on the beterogeneity size and shape, the Permeability contrast, and the mobility ratio. This paper deals with the displacement front behavior for one, simple, mathematically tractable model: a circular permeability discontinuity and unit mobility ratio. The progress of an initially planar front is shown for four permeability contrasts: k2/k1 = 0, 5/2, 2, m. The front distortion is more pronounced than streamline and isopotential distortion and it approaches a constant shape downstream from the discontinuity. INTRODUCTION The impact of reservoir heterogeneities on oil displacing processes depends upon the variation of the heterogeneous property (frequency distribution), its disposition (spatial distribution), and the inherent stability of the displacement mechanism.l The interplay of these factors plus the impracticability, if not impossibility, of describing a natural rock system in any detail makes exact displacement front movements difficult to determine. It is useful, however, to be able to qualitatively visualize what heterogeneities will do to a displacement front. In this respect certain simple models that can be treated analytically are of value. The following analysis will show the displacement front behavior for one such model. MODEL DESCRIPTION The flow field is two-dimensional and infinite in extent. The fluid flow is single phase, steady state and unidirectional at x, y = 2 m, or before insertion of the discontinuity. A circular permea- bility discontinuity is placed at the origin. Porosity and thickness are the same within and exterior to the heterogeneity. This is exactly the same model that was used by Greenkorn et al. to check analytically Streamlines as determined by Heie-Shaw flow models and finite difference computer techniques.2 FRONT POSITION CALCULATIONS The results of displacement front calculations are presented in Figs. 1 through 4 for four different permeability contrasts: k2/kl = O, %, 2, m. The times corresponding to the front locations are the Same for the 0 and cases! and for the 1/2 and 2 cases. The determination of front positions at various times is based on known analytical expressions for velocity potentials ().2 and stream functions ().2 These expressions are in terms of the x and y

Jan 1, 1969

By Eric Sinkinson

MANY of the magnesite ores of the western part of the United States contain such large amounts of silica and hydrous silicate minerals that the value of the ores is either low or nominal. Expensive and carefully controlled mining methods are necessary to prevent excessive dilution of the higher grade ores by introduction in mining of small pieces of the hanging walls or footwalls of the deposit. This difficulty is further complicated by the various states of decomposition of the country rock of the deposits in which many of the ores occur. The problem the authors attempted to solve arose from a request to float an impure magnesite containing varying proportions of siliceous gangue with calcium carbonate. The ore is normally enclosed in-serpen-tine masses, somewhat decomposed, and in mining it wall rock is inci-dentally added, so that variable amounts of siliceous material occur in the samples. The silica, alumna, and iron oxide are so closely associated with the magnesium carbonate in the magnesite that ordinary mechanical separation at coarse mesh sizes is of no avail. It is well known that calcium carbonate can be floated by suitable reagents, therefore it seemed reasonable to suppose that magnesium carbonate minerals would behave in a similar manner, but experimental trial proved that this supposition was unfounded. Therefore the first step in the problem was to find out what differences of behavior there were between magnesium and calcium carbonates under flotation conditions, or when suspended in water. In water at 18° C. magnesium carbonate is slightly more soluble than calcium carbonate; in fact; MgCO3 is soluble to the extent of 0.0106 grams in 100 c.c. of water at 18° C. and CaCO3 to the extent of 0.0013 grams. However, magnesium carbonate in water gradually changes to the basic carbonates of a composition (3MgCO3.Mg(OH)23H20) or (4MgCO3.Mg(OH)25H20), depending upon conditions, and calcium carbonate to calcium hydroxide, Ca(OH)2. The relative solubilities of these hydroxides in water are the reverse of the solubilities of magnesium and calcium carbonates. The range in published figures for solubility

Jan 1, 1936

By C. Baldwin Sawyer

J. S. Vanick,* Washington, D. C. (written discussion).—To those who have been confronted with the study of the gas-metal reactions, this paper is a most welcome contribution. My personal interest in work bearing upon this general problem, stimulated by an appreciation of the difficulties inherent to problems of this type, prompts a few words of discussion. Table 2 of the paper shows a gradual increase in the nitrogen content with an increase in pressure, and an interpretation follows in which nitrogcn is used as the compressed medium when the conditions admit that cyanogen gas could be active as a contaminating ingredient. Fusions of electrolytic iron made in the induction furnace in an atmosphere of deoxidized nitrogen and out of contact with contaminating materials have shown no microscopic evidence of -a nitrogen increase; using a refractory-lined graphite crucible in the furnace under the same conditions or admitting air often resulted in the occurrence of nitride needles in the solidified melt. These results suggested that a nitrogenous compound served as a vehicle for the introduction of nitrogen and that such compound was not available when the pure gas and carbon-free refractory were used. The fusion of pure iron in pure nitrogen is perhaps a matter of theoretical interest. The author's work serves a more practical purpose when applied to steels rather than iron. Table 2 reports the absence of nitride needles in melts made under pressure of one atmosphere, although the quantity of nitrogen present would seem to exceed microscopically detectable percentages. In some recent work29 on carburized iron, nitride needles have been observed in areas analyzing as low as 0.015 per cent. nitrogen. This low percentage of nitrogen would indicate that the solubility limit is less than 0.030 per cent. for hypoeutectoid steels. There is the possibility that the areas of pearlite which exist in a hypoeutectoid steel restrict the distribution of nitrogen and limit its presence to the ferritie fields. In view of this work and the references quoted by the author, I am led to expect that the value for the solubility of nitrogen in solidified iron may approach

Jan 1, 1924

By Walter S. Weeks

THE subject of the flow of air through a mine under the influence of natural ventilation has proved an elusive one. To my knowledge only cut and try algebraic solutions have been used where multiple paths are involved. The object of this paper is to present a method for the graphical determination of the flow induced by the natural ventilation pressure (N.V.P.) alone or in combination with a fan. The N.V.P., measured in pounds per square foot, induced by two columns of air between two horizontal planes at different elevations, is equal to the difference in weight of the two columns, assuming each to have a cross-sectional area of 1 sq. ft. Pressure in pounds per square foot is converted into inches of water by dividing by 5.19. Methods of calculating the N.V.P. have been discussed in the literature. In this paper, for simplification of exposition, the change in pressure due to the weight of superimposed air will be assumed directly proportional to the length of the column. The actual methods of calculating the N.V.P. do not affect the solutions to be presented. It must be realized that the precision to be obtained from the small- scale, inked diagrams presented is not as great as would be obtained from large-scale, penciled curves that would be used in practice. The accuracy of the curves does not warrant reading "volumes" closer than the nearest thousand cubic feet per minute. CASE I. DUCTS IN SERIES The simplest type of problem is to determine the flow when two shafts are connected by a crosscut, as shown in Fig. 1. In this example, the resistance of the shafts is to be taken as 0.0001 in. of water for a flow of 1000 cu. ft. per minute for a length of 1000 ft. The resistance of a crosscut is to be taken as 0.0005 in. of water for a flow of 1000 cu. ft. per minute. The small pressures necessary to cause changes in velocity will not be considered, because the accuracy of other obtainable data does not warrant their consideration.

Jan 1, 1938

By H. H. Lowry

SCIENCE attracts the attention and interest of an individual or an industry in general only in proportion to the apparent direct application to its immediate welfare or benefit. Engineering accomplishments, as applied science, therefore receive more recognition than the scientific discoveries on which they are based. Even self-evident truth needs endless repetition before recognition: engineering as applied science cannot advance beyond the science on which it is founded. Scientific research, and discovery, is sometimes forced by the limitations recognized by those active in its development for the use of society and industry and sometimes results from an apparently superficially illogical curiosity about natural phenomena. Research has received inadequate support except in industries born in the laboratory, the chemical and electrical industries, from which many lessons might well be drawn by their elder associates. The rapid growth of these industries has been largely due to close cooperation of scientists and engineers. Most rapid advance is made when the research worker and the engineer keep in close touch with each other's ideas and problems. Many of the developments of modern industry are based on dis-coveries buried for years in scientific journals because the "time was not ripe" at their discovery. The situation with regard to utilization of coal is quite the opposite. The fundamental facts in regard to the scientific aspects of the problem of developing the energy from coal are scarcely known. The engineer, without much scientific cooperation, has accom-plished much in increasing the number of kilowatt-hours per pound of coal from 0.31 in 1919 to 0.69 in 1934, in increasing the 1000 gross ton-miles of freight hauled from 6.1 to 8.3 per ton of coal in the same period, in fuel economy in production of coke, and in developing the production of motor fuel in Germany and England by hydrogenation of coal. This lack of scientific research on the utilization of our most important natural resource, coal, has been due undoubtedly in large part to the reluctance of investigators to study the interrelationships involved in, the complicated processes in which coal is used. These complexities are made

Jan 1, 1936

By N. O. Johnson

The Hog Mountain mine is a pyritic-gold property in the north central part of Tallapoosa County, Alabama, at an elevation of 800 ft. in the southern Appalachian region. It is 13 miles by a good secondary road from Alexander City, a station on the Central of Georgia Railroad. Since its discovery in 1839, the mine has been worked intermittently. The records of past operations are few and are scattered over a long period of time; however, available information indicates a production of approximately 12,000 oz. of gold prior to the present company's activities, which started in 1933. Additional 7844 oz. has been produced under the direction of the present management. The ore from stopes has averaged 0.200 oz. gold per ton; the ore from development, 0.136 oz. gold per ton. Silver, copper, iron and sulphur are also present but to date are of minor importance. The grade of ore in comparatively narrow veins makes necessary extreme vigilance in the methods of mining. Geology Wall Rock.—Hog Mountain consists of a quartz-diorite intrusion approximately 5000 ft. long by 1200 ft. wide. Its resistance to weathering, as compared to the surrounding schists, has led to the formation of a conspicuous ridge rising 400 ft. above the adjacent country. All the mining operations are confined within the limits of this quartz-diorite formation. Except where there is excessive shearing, either parallel or at flat angles to the quartz veins, all the walls of the stopes within the limits of the veins are strong enough to make timbering unnecessary. Where shearing exists, there may be a sloughing off of the walls, especially in the process of drawing the ore. When this occurs, stulls are placed in the stope, either while the stope is advancing, or while ore is being drawn from a completed stope. In general, very little timber is required. Veins.—The quartz veins have been deposited along fracture planes in the quartz diorite. There are 20 principal veins, all of which are roughly parallel and strike at right angles to the long axis of the formation.

Jan 1, 1937

By Arthur Crowfoot

As a result of work done, on an operating scale, in its experimental mill during 1920 and 1921, the plan here given was proposed for crushing, grinding, and concentrating low-grade sulfide ores at the Morenci Branch of the Phelps Dodge Corpn. The flow sheet is designed to recover 85 per cent. of the total copper and 95 per cent. of the sulfide copper from ore assaying 2.0 per cent. total copper and 0.3 per cent. acid soluble copper. At present, 1400 tons are treated daily under the conditions of this flow sheet, two 700-ton units having been installed in the 4000-ton concentrator. The run-of-mine ore will be reduced, in the dry-crushing plant, to —6 mesh and then delivered to the concentrator feed bins. The crushing will be done in three stages: (I) Run-of-mine ore is reduced to —2 1/2-in. in a gyratory crusher; (2) the 3-in. ore is reduced to 1/2-in. in 72 by 24 in. rolls; (3) the 1/2-in. ore is reduced to — 6-mesh size in 54 by 24 in. rolls. The 54-in. rolls will operate in closed circuit with electrically vibrated screens, "Hum-mer" type, a conveyor circuit being used to carry the roll product to the screens. Sufficient screens will be installed to pass 1.5 tons undersize per hour per square foot. Fine-ore bin chutes will be piped for compressed air, which will be used intermittently to keep the ore feed in motion if it tends to arch or pipe in the bins. The Concentrator The concentration of the copper and iron sulfides in the ore will be effected in three stages: I. By direct treatment of the —6-mesh crushing-plant product on primary tables, which will recover about 35 per cent. of the original copper content of the ore in a clean granular concentrate. The table middling will be dewatered in Dorr rake classifiers and ground to — 48-mesh in ball mills operating in closed circuit with circulating classifiers.

Jan 1, 1923

By S. D. Michaelson, Eric Sinkinson

Many of the magnesite ores of the western part of the United States contain such large amounts of silica and hydrous silicate minerals that the value of the ores is either low or nominal. Expensive and carefully controlled mining methods are necessary to prevent excessive dilution of the higher grade ores by introduction in mining of small pieces of the hanging walls or footwalls of the deposit. This difficulty is further complicated by the various states of decomposition of the country rock of the deposits in which many of the ores occur. The problem the authors attempted to solve arose from a request to float an impure magnesite containing varying proportions of siliceous gangue with calcium carbonate. The ore is normally enclosed in serpentine masses, somewhat decomposed, and in mining it wall rock is incidentally added, so that variable amounts of siliceous material occur in the samples. The silica, alumina, and iron oxide are so closely associated with the magnesium carbonate in the magnesite that ordinary mechanical separation at coarse mesh sizes is of no avail. It is well known that calcium carbonate can be floated by suitable reagents, therefore it seemed reasonable to suppose that magnesium carbonate minerals would behave in a similar manner, but experimental trial proved that this supposition was unfounded. Therefore the first step in the problem was to find out what differences of behavior there were between magnesium and calcium carbonates under flotation conditions, or when suspended in water. In water at 18" C. magnesium carbonate is slightly more soluble than calcium carbonate; in fact, MgCO3 is soluble to the extent of 0.0106 grams in 100 c.c. of water at 18" C. and CaCO3 to the extent of 0.0013 grams. However, magnesium carbonate in water gradually changes to the basic carbonates of a composition (3MgCO3.Mg(OH)23H2O) or (4MgCO3.Mg(OH)25H2O), depending upon conditions, and calcium carbonate to calcium hydroxide, Ca(OH)2. The relative solubilities of these hydroxides in water are the reverse of the solubilities of magnesium and calcium carbonates. The range in published figures for solubility

Jan 1, 1938