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By M. R. J. Wyllie, F. Morgan, P. F. Fulton

The importance of formation factor, F, not only in electric logging but as a fundamental rock parameter has recently been stressed.',: The desirability of investigating the range of variation of the resistivity index exponent, n, in the relationship I = S ;", where I is the resistivity index and Sw the water saturation as a fraction of the void volume of a porous medium, has also been urged.3 The magnitude and variation of n with saturation and rock texture is a subject not only of theoretical interest but also one of prime importance in the interpretation of electric logs. A simple technique has recently been developed which enables both F and u to he measured with high accuracy and which may also find acceptance as a convenient method for the determination of irreducible saturation attainment in the restored state method of core analysis. Experience has taught that reproducible measurements of F are possible only if the resistance measuring electrodes are so arranged with respect to a plane face on a porous medium that they are able to make electrical contact with substantially all entry pores in that plane. In practice this may be achieved by using a platinized-platinum gauze electrode backed by some absorbent material (such as felt) which has been saturated with a fluid identical with that used to saturate the porous medium. Applicatiorl of pressure to the electrode and absorbent material then forces the gauze against the plane face of the porous medium and simultaneously squeezes saline solution through the meshes of the gauze. By this means the electrode is in continuous aqueous contact with all pores and satisfactory and reproducible low resistance contact with the porous medium is achieved. Clearly this method, although satisfactory for measurements of F, cannot be applied to the making of continuous resistance measurements on a porous medium while capillary pressure desaturation is being carried out. However, accepting the principle that for satisfactory results electrical contact must be made between a measuring electrode and all pores adja- cent to that electrude, methods of bringing electrodes into intimate contact with the surfaces of porous media were investigated. Two methods were ultimately found to be satisfactory: in the one, the metal electrode is formed on the required portion of the porous medium by the use of a metal spray gun, while in the second the electrode is painted on with an ordinary camel's hair brush. The first method has the advantage of permitting the use of any metal which can be sprayed, but has the disadvantage of requiring rather elaborate and expensive equipment. The second method is presently limited to silver electrodes although in principle other metals, e.g. platinum or gold, could be used. Moreover, the method is so simple and cheap, and has been found to be so satisfactory that it will be described in some detail. The core being investigated is cut into a right circular cylinder and is extracted and dried in the usual manner. The ends are then lightly painted with silver conducting paint* of the type used in printed electrical circuits. The quantity of paint used is not critical but the recommended, minimum compatible with entirely coating the core ends is recommended, particularly on the end that contacts the barrier. The core is then dried at atmospheric temperature for one hour or for shorter periods at any suitable elevated temperature up to about 110°C. It will be found that silver coatings so prepared are not only strongly adherent but also permeable and the core may be the core may be desaturated by the ordinary capillary pressure technique through one of the coated faces. The same permeability is characteristic also of thin metal coatings formed using the spray-gun technique. An ordinary Lucite capillary pressure desaturation cell has been adapted to a form suitable for measuring the resistivity of the saturated silver faced cores both at 100 per cent saturation (i.e., F) and at intermediate saturations down to the irreducible minimum. This has been achieved as follows: A Coors porcelain barrier, having a displacement pressure of c 30 psi was grooved across a diameter. Dimensions of this groove were c 1 mm deep and 1 mm wide at the top. The groove was then painted thickly with silver conducting paint, the paint in the groove being extended lightly over the edges of the groove for a distance of c 1 mm on each side. A 30 gauge silver wire was then arranged in the groove in a form of a spring bow, each end of the silver being held at diamet~ically opposite ends of the groove by means of plastic cement. The arc of the bow at its highest point was arranged to be a millimeter or so above the face of the barrier, while one end of the bow wire was led by means of a pressure-tight connection through the wall of the capillary pressure cell. The groove in the barrier was then Surrounded by suitably cut portions of Kleenex in the conventional manner so as to ensure capillary continuity from core to barrier, and the core placed on the barrier. The weight of the core distorted the silver spring bow and good electrical contact was thereby made between the outside of the cell and the lower painted silver electrode. Electrical connection to tile top painted silver

Jan 1, 1951

By Craig S. Hartley

An approximate expression is obtained for the energy of a closed dislocation loop in equi1ibriu)n with a constant net stress. The result obtained is valid for loops in isotropic or anisotropzc materials provided that they are suJficiently large that the energy per unit length of a segment of the loop can be approximated by that of an infinite straight dislocation tangent to the loop. It is shown that this approximation leads to very close agreement with a more rigorous calculation of the elastic energy of a circular glide loop. The Gibbs-Wulff Form, GWF, of a dislocation is the closed planar loop which has the smallest elastic self-energy of all possible loops having the same Burgers vector and enclosing a fixed area, A.' The energy of such a loop is related to the net resolved shear stress* required to expand the loop and to the stress required to activate a Frank-Read source.223 In the following sectiorls the problem of determining the form of the GWF is discussed and an approximate method for calculating its elastic self-energy is presented. It is demonstrated that the approximations employed lead to no serious errors when applied to a calculation of the elastic energy of a circular glide loop. This method is then used to obtain a closed form expression for the energy of GWFs in isotropic and anisotropic materials. THEORY Burton, Frank, and cabrera4 have proved that the relationship of the equilibrium shape of a two-dimensional array of atoms under the influence of the Gibbs free energy associated with unit length of its boundary, G(O), is that the polar plot of G(0) vs 0 is proportional to the pedal of the GWF.* The angle 0 is measured "The pedal of the polar graph ofG(0) vs0 is the envelope of tangents to the eraph.relative to some crystallographic reference direction. The difficulty in applying this result to a closed dislocation loop arises from the self-interaction of the loop. For a dislocation the energy analogous to G(0) is a function of the total configurati~n.~ Consequently the relation which determines the GWF is an integro-differential equation rather than the simple differen- tial equation which results when G(8) is a function of 0 alone. Mitchell and smialek3 and Brown~ have used the self-stress concept introduced by ~rown' to calculate the shapes of dislocations in equilibrium with an applied stress. In this approach the glide force on an element of the dislocation loop due to the interaction of the element with the rest of the loop is equated to the glide force exerted by the local applied stress. The shape of the loop is then adjusted so that the two forces above are equal at all points on the loop. It is possible to calculate the energies of such loops by noting that, for equilibrium with an applied stress, the energy is equal to pijbiAj (summation convention) where bi is the Burgers vector, p.. is the local net stress tensor, and Ai is a vector directed perpendicular to the plane of thd loop with magnitude equal to the area of the loop. Also Brown' has calculated the energy of a hypothetical polygonal GWF using the above technique and anisotropic elasticity. However, his indicated solution for the energy in the general case of an arbitrary GWF is only slightly less involved than an iterative solution of the integrodifferential equation referred to earlier. In the present work the approximation employed by DeWit and Koehler' is used to calculate the energy of a closed loop in equilibrium with an applied stress. That is, the energy of a loop segment, ds, is approximated by the product of ds and the energy per unit length of an infinite, straight dislocation in a cylinder coaxial with the tangent to the loop at the angular position of the segment. This is known as the "line tension" approximation. The inner cutoff radius of the elastic solution defines the core radius, while the outer cutoff radius is determined by some characteristic dimension of the loop. Actually, both of these radii vary with the edge-screw character of the segment. The effective core radius changes because of the orientation dependence of the Peierls width of a dislocation,8 and the outer radius should be the radial distance from the circumference of the loop to the center of symmetry of the area enclosed by the loop.g However, since the energy varies logarithmically with the ratio of these radii while depending directly on the effective elastic constants, only the effect of the latter is considered. This approximation also neglects the self-interaction of the loop segments. For small loops this will doubtless be extremely important, but for large glide loops produced by plastic deformation the self-interaction is not nearly so important in determining the energy of the loop. This point is illustrated by the following calculation of the energy of a circular loop. Consider a circular loop of radius R which lies in the XI - x, plane of an infinite isotropic continuum and whose Burgers vector makes an angle $ with xs. The first-order solution for the elastic self-energy is:'

Jan 1, 1970

By BERNARD PLANNER

PRODUCTION COSTS, profits, and quality are the primary factors in the peacetime production of iron and steel. In a war emergency, as high production rates and as complete utilization of readily available raw materials as possible, consistent with securing passable quality, become the most important factors. In this connection a discussion of some of the recent developments in the German iron and steel industry, where the problem of scarcity has naturally always been more acute than in the U.S.A., maybe of interest. To get more pig iron out of the existing blast furnaces it was necessary to obtain the maximum efficiency from the iron-bearing raw materials. This was achieved by eliminating all "excess baggage," chiefly by beneficiating the ore. The preparatory work for this was done by various methods which are effective when the ore either is too poor or contains too many impurities or too much gangue. Some of the beneficiation methods are well known, some are combinations of wet-mechanical, magnetic, roasting, sintering, and other treatments.

Jan 1, 1942

By W. Rostoker

IN the course of the development of the phase equilibrium diagram for the system Zr-Cr,' the structure of an as-cast allov having the composition ZrCr2 was analyzed and established to be isomorphous with MgZn2 (C14, hexagonal lattice, 12 atoms per unit cell). In a recent paper on the same system, Hayes, Roberson, and Davies' report for the ZrCr2 phase an isomorphy with MgCu2 (C15, cubic lattice, 24 atoms per unit cell). It appeared that this conflict might be resolved by assuming a high and low temperature modification for ZrCr2. That this was the case with the phase TiCr2 has recently been demonstrated by Levinger." Specimens of ZrCr2 annealed at 1200°, 1100°, 994", 900°, 834", 800°, and 700°C, respectively, and subsequently quenched were examined by X-ray diffraction analysis. It was successfully demonstrated that a transition from the MgZn, structure at lower temperatures to the MgCu, structure did occur at some temperature between 900" and 994°C. Table I lists the observed structures at the various annealing temperatures. In Table II, a summary of line spacings and intensities is given for each of the allotropic modifications. The first six lines of the MgCu2 structures have been located in the table to illustrate the close similarity between the patterns. Lattice parameters of the two modifications were calculated by a least squares solution of equations for interplanar spacings for a series of high angle lines. The results are as follows: MgZn2 type - c = 8.262 kX, A = 5.079 kX. MgCu2 type — a = 7.195 kX. It is interesting to note that TiCr2 behaves in reverse fashion yn that the MgCu, structure is the low temperature modification and the MgZn2 structure is the high temperature modification. References lR. F. Domagala, D. J. McPherson, and M. Hansen: This issue p. 279. 'E. T. Hayes, A. H. Roberson, M. H. Davies: Trans. AIME (1952) 194, p. 304; Journal of Metals (March 1952). 3B. W. Levinger: Trans. AIME (1953) 197, pp. 195-196; Journal of Metals (February 1953).

Jan 1, 1954

By J. F. K. Brown

ANTHRACITE in 1943, in common with the coal industry as a whole, passed through a year of wage negotiations that seemed endless. In the early months discussion of the United Mine Workers' demands was taken up and carried on continuously until May, finally reaching an impasse when the Union refused to continue at work, while submitting their demands to the War Labor Board. Thus a strike threatened, averted by the Federal Government taking over the industry, effective May 1, by order of the President. An office of the Bureau of Mines was established in Wilkes-Barre under the direction of J. J. Forbes, Mineral Production Security Division, as regional manager, who conducted operations until September, 1943, when the collieries were turned back to the operators. But the miners did not agree with the War Labor Board's award rendered in the fall, resulting in a recurrence of the previously threatened strike. again averted by Government control. In addition to the major upsets, a number of individual suspensions occurred at various mines. In spite of these drawbacks, to which might be added the difficulty of obtaining equipment and the scarcity of man power, the industry by November was only little less than a million tons short of the previous year. and in all probability, finally produced but little less than in 1942. This little less. however, was greatly missed in the market.

Jan 1, 1944

By G. Derge, Ling Yang, G. M. Pound

The specific conductance and its temperature dependence were measured over the entire composition range of the molten Cu2S-CuCI system. At a typical temperature of 1200°C, 10 rnol pet of the ionically conducting CuCl reduced the specific conductance from about 77 ohm-lcm-l for pure Cu2S to about 32 ohm -1cm -1, and 50 mol pet CuCl reduced the conductance to that for pure CuCI—about 5 ohm 1cm1. The nature of electrical conduction in molten Cu2S, FeS, CuCI, and mixtures was studied by measuring the current efficiency of electrolysis at about 1100°C. The Cu2S, FeS, and mattes were found to conduct exclusively by electrons, but addition of 1 5 wt pet CUS to Cu2S produces a small amount of electrolysis. Addition of CuCl to Cu2S suppresses electronic conduction, and ionic conduction reaches almost 100 pet at a CuCl concentration of about 50 mol pet. These facts are interpreted in terms of electron energy level diagrams by analogy to the situation in solids. RESULTS of electrical conductivity studies on molten Cu-FeS mattes as a function of composition and temperature have been reported.' The specific conductances ranged from about 100 ohm-' cm-' for pure Cu2S to 1500 ohm-' cm-1 for pure FeS. This is in sharp contrast with the low specific conductance of molten ionic salts for which the transfer of electricity is by migration of ions in the field. In general, these ionically conducting molten salts, such as NaC1, KC1, CuC1, etc., have a specific conductance of the order of magnitude of 5 ohm-' cm-'. It was concluded on the basis of this evidence that molten FeS and Cu,S exhibit electronic conduction. Pure molten FeS has a small negative temperature coefficient of specific conductance, resembling metallic conduction, while pure molten Cu2S has a small positive temperature coefficient, resembling semi-conduction. The molten Cu2S-FeS mattes follow a roughly additive rule of mixtures, both with respect to specific conductance and temperature coefficient. Savelsberg2 has studied the electrolysis of molten Cu2S and Cu2S + FeS. He concluded that while molten Cu2S is an electronic conductor, there is some ionic conduction in molten Cu2S + FeS3 owing to the formation of the molecular compound 2Cu2S.FeS and its dissociation into Cu1 and FeS2-1 ions. The present work does not verify his results. Chipman, Inouye, and Tomlinson" have studied the specific conductance of molten FeO and report a high specific conductance, about 200 ohm-1 cm-1 of the same order of magnitude as that found for molten mattes, and a positive temperature coefficient. They interpret these results in terms of p-type semiconduction in the ionic liquid by analogy to the situation in solid FeO.1 imnad and Derne' detected appreciable ionization in molten FeO by means of electrolytic cell efficiency measurements. In order to verify the conclusion that electrical conduction in molten Cu2S and mattes is electronic, and to gain further insight into the structure of molten sulfides, the following investigations were carried out in the present work: 1) The specific conductance, s of the molten system Cu2S-CuC1 was measured as a function of temperature over the entire composition range. As discussed later, molten CuCl is an ionic substance. It was thought that if molten Cu2S were simply ionic in nature, addition of small amounts of CuCl might not have a catastrophic effect in lowering the high conductance of the Cu2S. On the other hand, if much electronic conduction occurs, addition of the ionic CuCl should have a large effect in destroying the electronic conduction. 2) The electrolytic cell efficiency of the following molten systems was measured at about 1100°C in specially designed cells: Cu3; Cu2S + FeS, 50:50 by wt; FeS; Cu2S + CuS, 15 wt pet; Cu2S + CuC1, 5.9 to 46.4 mol pet; and CuC1. This gives a direct measure of the fraction of current carried by ions in these melts. Further, the cell efficiency, extrapolated to zero ionic current, is given by cell efficiency = (s leasile + s elexstronic). [1] s lucile for molten CulS would be expected to be no greater than that for molten CuC1, whose s lonle is about 5 ohm-' cm-1, as will be seen in the following. u,.,,.,.,.......for molten Cu,S is of the order of 100 ohm-' cm-'.' Thus, a large increase in cell efficiency from 0 to values of 10 to 100 pet upon addition of CuCl to Cu2S would indicate destruction of the electronic conductance. Conductance Measurements Experimental Procedure—The apparatus and experimental method were the same as those described in detail in connection with the study of electrical conduction in molten Cu,S-FeS mattes.' A four terminal conductivity cell and an ac poten-

Jan 1, 1957

By Meguru Nagamori

DURING the smelting of the sulfide ores of copper, nickel, and certain other metals, a matte phase is formed. For a better understanding of the physico-chemical properties of mattes, binary systems such as Cu-S, Ni-S, Fe-S, and so forth, should be studied, especially in the vicinity of liquid compounds such as Cu2S, Ni3S2, FeS, and so forth. These compounds are relatively stable in the solid state although they can exhibit appreciable deviations from stoichiometry. With small deviations from stoichiometry there are large changes in the activity of both sulfur and metal this is a characteristic of both solid and liquid sul-fides near the stoichiometric compositions. In the vicinityof molten Cu2S,1 for instance, the activity of sulfur increases about 100 times for a 0.012 increase in the mole fraction of sulfur and, correspondingly, the activity of copper decreases greatly. In this sens the minor deviations from stoichiometry should be carefully taken into account in studies of such metal-sulfur melts. Metal-sulfur melts may be considered to have properties intermediate between metallic solutions and molten salts, i.e., neither entirely metallic nor entirely ionic. The radius of the ion sZ- is 1.84 as compared with 1.04? for a single bond covalent s.2 It is therefore inferred that when the sulfur is more ionic its partial molar volume is larger, although metal-metal, metal-sulfur, and sulfur-sulfur interactions may bring about further complexities. Thus, it is to be expected that the molar volumes, which are derived from density-composition relations, will help in resolving the structure of the melts. In this study the maximum bubble pressure method with bubbling gases of H2, H2S, and Ar, .was employed to measure the density. EXPERIMENTAL Materials. Silver of 99.95 pct purity was melted in an alumina crucible and hydrogen gas was then bubbled through the liquid for the deoxidation. In preparation of Cu2S, electrolytic copper powder (>99.9 pct Cu) was mixed with precipitated sulfur and heated to 1200°C in an alumina crucible under a hydrogen atmosphere. Mixtures having the approximate compositions FeS and Ni3S2 were prepared by heating reagent grade electrolytic iron or reduced nickel powder with precipitated sulfur under a hydrogen atmosphere. The H2S gas was of 98.5 pct purity, the impurities being mostly CO2 and CS2 which hardly contaminate the melts. Apparatus. The crucible system is shown schematically in Fig. 1. To minimize the variation of melt composition during a density measurement, the apparatus was designed in such a way that either Ar, H2, H2S, or mixtures of these gases could be used as the bubbling gas. When the melt had a high partial pressure of sulfur, H2S gas was used. When the partial pressure of sulfur was so low that oxygen might dissolve in the melt, the use of H2 was preferred. In intermediate cases, argon or mixtures of H2-H2S were used. Density of Dibutylphtalate. Dibutylphtalate was used as the manometer fluid. Relative to distilled water, the density of the dibutylphtalate, pdib g per cc, was measured and found to be: pdib (25°C) = 1.046 i 0.002. With the use of the temperature coefficient reported by Kemppinen and Gokcen,3 the following value was

Jan 1, 1970

By E. H. Mohr

At the McGill concentrator of the Nevada Consolidated Copper Co., all flotation operations have been carried out in Forrester cells since November, 1926. In respect to cost of operation, the new cell has proved to be superior to the Callow, which it supplanted, and its incorporation in the flow sheet has resulted in a marked improvement in the metallurgy. Before citing the advantages of the new machine over the old, it should be explained that the Forrester has not only replaced the Callow, but it has made possible the elimination of a number of tables as well. When Callow cells were in use, table concentration preceded flotation. The ball mill pulp was elevated, by means of air lifts, to roughing Wilfley tables situated two floors directly above the flotation floor. On an intermediate floor were additional tables which cleaned the concentrate from those above. The finished table concentrate constituted approximately 60 per cent. of the total mill production, and contained about 40 per cent, of the recovered copper. The table tailings were returned to the classifiers, the overflow from which went to the flotation cells and the oversize to the ball mills. As soon as the Forrester cells were installed, this tabling operation was discontinued. The ball mill pulp now discharges into the classifiers direct, without the intermediate tabling. It was impracticable to ernploy the present flow sheet when Callow cells were in use, for the reason that unless the great,er part of the heavy mineral was first removed, it accumulated on the mats and adversely affected the flotation operation. By tabling ahead of flotation, it was practicable to maintain the concentrator at 10 to 20 per cent. greater capacity (depending up on the pyrite contnt of the ore) than was possible by flotation alone. This was due to the necessity for finer grinding in the latter case. Even though the table conecntrates contained only 6 to 8 per cent'. copper content, the low smelting costs made it advantageous to operate at high mill capacity, at the cost of low grade of product. Standard Section equipment With the old flow sheet, a standard section consisted of four ball mills and classifiers, one air. lift, 20 roughing tables, 10 cleaner tables, 12 primary

Jan 1, 1928

By C. G. Dunn, F. W. Daniels, M. J. Bolton

IN recent papers on interface energies in metals¹,² the concept of an equilibrium of forces has been used in the measurement of interfacial tensions. Mathematically the equilibrium of three forces is given by the relations: where the 2's are the interfacial tensions (interface energies per unit area of interface) of three phases or grains meeting at angles 21 22 and 23 (212 relates to the 1-2 boundary formed by grains 1 and 2;223 to the 2-3 boundary, etc.). If these relationships are valid, one can calculate relative values of the interface energies from measured boundary angles on specimens which have been brought to equilibrium. Since Eq 1 may be derived through a mathematical process of minimizing the grain boundary energy under the restriction that the ?'s be independent of boundary orientation: the concepts of surface tensions and equilibrium of forces are not particularly essential. To deal with the general case involving dependence of boundary energy on boundary orientation, it becomes desirable to drop certain concepts formerly held (namely that energy per unit area is identical with force per unit length or surface tension) and to use the energy concept alone. It is appropriate, therefore, to use E in place of ? in deriving and using the more general equations that express the anisotropic nature of the grain boundary energy. Herring3# ' recently has derived the required general equations using the principle of minimization of energy. Specifying the boundary orientations in terms of angles (4) measured with reference to crystal axes within the grains, Herring's equations take the form E23 + E21 cos?8 + E12 cos?2 — sin ?12 + sin?2-?E12/?12 =O [2] where the partial derivatives are measured in the direction of counterclockwise rotation of the boundaries. Eq 2 implies that an infinitesimal displacement of the triple point along the 2-3 boundary produces no change in the boundary energy. Similar equations apply for infinitesimal displacements along each of the other two boundaries. From such equations Herring obtains the following general relationship (1 + E1 E2) sin?8 + (E2 — E1) cos?3 ________ E38______________ = (1+ E2 E8) sin ?1+ (E3— E2) cos ?1 __________^5____________[3] (1 + E sin ?2, + (E1 — E8,) COS ?2 1 E28 where E1 = 1/E23- E25 and PC and c8 have similar expressions. It is apparent that Eq 3 reduces to Eq 1 when the c's vanish. Eq 3 also reduces to Eq 1 when the E'S are all equal. Shockley and Read' have pointed out one limitation to these equations. When E plotted versus 4 appears as an energy cusp, as their theory requires, for example, for the energy near a twin boundary position, then Eq 3 (and therefore Eq 1 also) no longer applies if one boundary is in the minimum energy position. One of the equations of form Eq 2, however, applies if the infinitesimal displacement is along the boundary associated with the energy cusp. From the foregoing treatment it will be apparent that equilibrium angles alone are not sufficient in general for calculating relative interface energies.

Jan 1, 1951

By Reed W. Hyde

SOME information has been published on the sulphur dioxide concentration of gases from Dwight-Lloyd machines sintering lead ores but most of this relates to the customary practice in which the charge is relatively high in lead and is sintered in two passes over the machine. It is thought, therefore, that the following observations on sintering in one pass a low-lead, low-sulphur charge may be of interest. The data were obtained in sintering lead sulphide flotation concentrates mixed with minus 20-mesh oxide ore, the mixture carrying 16.8 per cent Pb and 5.3 per cent S. No returns were used because of the limited amount of sulphur available as fuel, but the mixture pelletized readily to make a satisfactorily permeable bed on the sintering machine. As there was a possibility that the SO2 might be utilized, a series of runs was made to determine the concentration of SO2 in the gases at different points along the wind box, and the effect on this concentration of changes in the wind-box vacuum. Several runs each were made with vacuums (as measured in inches of water at the wind box) of (1) 2 to 1 3/4 in., (2) 4 to 3 1/2 in. and (3) 6 to 5 1/8 in. The averages of the determinations from each series are platted on the graph (Fig. I). The vertical scale shows the percentage by volume of SO2 (as determined by the Reich method), and the horizontal scale shows the time expressed as percentage of the total sintering time. Sintering was considered to be complete when no SO2 could be detected in the gases. In all cases the depth of bed was 4 1/2 in. and the weight of dry charge per square foot of hearth area was 45.2 lb. Other data are given in the table. The volume of gases corresponding to the several points along the wind box at which SO2 determinations were made could not be measured, but has been calculated from the SO2 content and sulphur elimination on the assumption that the volume is uniform throughout the sintering period. This is not strictly true, as with a given vacuum the volume will usually drop slightly toward the middle of the period and increase toward the end. However, this assumption is a reasonable approximation. Several interesting features are brought out by these data. In general, the published data on SO2 concentration in sintering under ordinary conditions show a high SO2 concentration in the early stages followed by a rapid decrease in concentration and with relatively little SO2 in the gases from the last half or third of the operation. In other words, the greater part of the sulphur elimination is obtained in the first third or half of the period. In these runs, the 6-in. vacuum, which approximates the usual operating condition, gives a curve that follows this customary pattern. Maximum SO2 concentration is obtained 2 ½ min. after

Jan 1, 1942

By T. Egleston

AT the Dover meeting of the Institute, Mr. F. A. Canfield showed some of the members a machine which he had invented for dressing mineralogical and geological specimens, which he has since modified and brought to such a high state of perfection, that after having used it for several months in preparing specimens for the cabinet of the

Jan 1, 1876

J. Lainson Wills, Ottawa, Can. (Communication to the Secretary) : The localities of the Quebec and Ontario apatite deposits, and the nature of their occurrence haye been often described in the Transactions and in other publications that are readily available, and I do not, therefore, intend to discuss the many details advanced in Mr. Small's paper beyond the following two points:

Jan 1, 1893

Theo. B. ComstocK, Los Angeles, Cal. (communication to the Secretary*):—Mr. Blake's recent paper upon this topic undoubtedly partly explains the rationale of a part of the known facts bearing upon discolorat'ion and encrustation of rocks. His quotation from Humboldt, with reference to certain South American examples, may be questioned in the light of further facts, which do not appear to bear out the great traveler's theory of causation. There is no available evidence that the waters of the tropical rivers referred to by Professor Blake contain dissolved organic matter in the varying proportions required to demonstrate Humboldt's guess, nor do the concomitant facts in any manner bear out the hypothesis that the blackening in one case and its absence in the other may, perhaps, be traced to differences in the chemical reactions of the respective waters. Careful consideration of Professor Blake's illustrations, in connection with numerous personal observations extending over widely-scattered areas, convinces me that elements of

Jan 1, 1905

By T. Egleston

At the Dover meeting of the Institute, Mr. F. A. Canfield showed some of the members a machine which he had invented for dressing mineralogical and geological specimens, which he has since modified and brought to such a high state of perfection, that after having used it for several months in preparing specimens for the cabinet of the

By Duane N. Goens, Clifford R. Porter

A 91 kg/h (200 lb per hr) pilot plant was constructed according to "Magnex" design. A non-compliance eastern coal which would generate more than 0.85 kg of S02 per GJ (2.0 lb of SO2 per million Btu.) upon burning was brought into compliance less than 0.52 kg of SO2 per GJ (1.2 lb SO2 per million Btu) during continuous operation of the pilot plant. Approximately 85% of the pyritic sulfur was removed while recovering 90% of the Btu of the feed coal. Pilot plant operation is summarized and preliminary economics presented. Present status of the Magnex design program is reviewed.

Jan 2, 1979

By Charles Williams

BOYLE'S law states that the volume of a gas at B constant temperature varies inversely as its pressure, PV = C, or V = C/P Therefore, the volume of a gas at any pressure is to its corresponding pressure as the volume of the same gas at atmospheric pressure is to atmospheric pressure, V, = V° Also, P1 P0 the volume of the gas at any other pressure is to its corresponding pressure as the volume of the gas at atmospheric pressure is to atmospheric. pressure, V2/P1 V0/P0 V°P VA Solving for V1 and V2, V2 = and V2 =V0P2/P0

Jan 2, 1927

By R. B. Snow

This paper describes a technique of polishing and etching specimens of open-hearth furnace slags or hearth aggregates for identification of the crystalline constituents —lime (CaO), tricalcium silicate (3CaO.SiO2), dicalcium silicate (2CaO.-SiO2), rnonticellite (CaO.MgO.SiO2), or forsterile (2MgO.SiO2), with especial em-phasis on the mineral merwinite (3CaO.-MgO.2SiO2). With proper standardization, this identification does not require the use of the petrographic microscope. The composition of basic open-hearth slags and furnace bottoms falls, almost without exception, within systems containing CaO, MgO, 'IFeO,,, MnO and SiOz, in which the number of basic molecules so greatly exceeds the orthosilicate ratio (two molecules of base to one of silica) that free basic oxides, and combinations between them such as alumi-nates or ferrites, are present in cooled specimens. Orthosilicates of (CaO + NgO) are the most common in such specimens, since in nearly all cases, except premelt slags, the molecular ratio of (CaO + MgO) to SiO, is more than 2 to I. When sufficient lime is available it combines with the silica to form dicalcium silicate (2Ca0.Si02), which contains little, if any, IvfgO, FeO or MnO in solid solution whereas the latter oxides combine to form the oxide solid solution known as periclase. If the lime present is insufficient to form dicalcium silicate (2Ca0.Si02) it combines with Mgo to form either merwillite or moIlticellite (SiOz); these minerals take little if any FeO or MnO into solid solution and the remaining MgO, FeO and hInO combine as periclase. This generalization seems to be valid for basic slags and furnace bottoms, since minerals such as Ca0.MnOSi02 and CaO.FeO.SiOz are found only in slags in which the lime-silica ratio is less than 2 and are not observed in 'pecimens from furnace bottoms. The identification of crystalline constituents in such materials, especially of fine crystals in the groundmass, is difficult under the petrographic microscope. They are often masked by their neighbors because of their small size in relation to the thickness of the thin section and because of the presence of Opaque Or colored constituents. The indices of refraction and the optical sign of the mineral are sometimes difficult to determine because of the small size or because Of twinning or of inclusions within the crystal. Moreover, the positive identification of merwinite (3Ca0.Mg0.2Si02) from its optical properties is usually difficult in the presence of dicalcium silicate (zCaO.SiO2). CaO, MgO, jCa0.Si02 and 2Ca0.SiOz in open-hearth 'lags have been identified for a number of years in the U.S. Steel Corporation Laboratory by the usual

Jan 1, 1948

By R. B. Snow

This paper describes a technique of polishing and etching specimens of open-hearth furnace slags or hearth aggregates for identification of the crystalline constituents —lime (CaO), tricalcium silicate (3CaO.SiO2), dicalcium silicate (2CaO.-SiO2), rnonticellite (CaO.MgO.SiO2), or forsterile (2MgO.SiO2), with especial em-phasis on the mineral merwinite (3CaO.-MgO.2SiO2). With proper standardization, this identification does not require the use of the petrographic microscope. The composition of basic open-hearth slags and furnace bottoms falls, almost without exception, within systems containing CaO, MgO, 'IFeO,,, MnO and SiOz, in which the number of basic molecules so greatly exceeds the orthosilicate ratio (two molecules of base to one of silica) that free basic oxides, and combinations between them such as alumi-nates or ferrites, are present in cooled specimens. Orthosilicates of (CaO + NgO) are the most common in such specimens, since in nearly all cases, except premelt slags, the molecular ratio of (CaO + MgO) to SiO, is more than 2 to I. When sufficient lime is available it combines with the silica to form dicalcium silicate (2Ca0.Si02), which contains little, if any, IvfgO, FeO or MnO in solid solution whereas the latter oxides combine to form the oxide solid solution known as periclase. If the lime present is insufficient to form dicalcium silicate (2Ca0.Si02) it combines with Mgo to form either merwillite or moIlticellite (SiOz); these minerals take little if any FeO or MnO into solid solution and the remaining MgO, FeO and hInO combine as periclase. This generalization seems to be valid for basic slags and furnace bottoms, since minerals such as Ca0.MnOSi02 and CaO.FeO.SiOz are found only in slags in which the lime-silica ratio is less than 2 and are not observed in 'pecimens from furnace bottoms. The identification of crystalline constituents in such materials, especially of fine crystals in the groundmass, is difficult under the petrographic microscope. They are often masked by their neighbors because of their small size in relation to the thickness of the thin section and because of the presence of Opaque Or colored constituents. The indices of refraction and the optical sign of the mineral are sometimes difficult to determine because of the small size or because Of twinning or of inclusions within the crystal. Moreover, the positive identification of merwinite (3Ca0.Mg0.2Si02) from its optical properties is usually difficult in the presence of dicalcium silicate (zCaO.SiO2). CaO, MgO, jCa0.Si02 and 2Ca0.SiOz in open-hearth 'lags have been identified for a number of years in the U.S. Steel Corporation Laboratory by the usual

Jan 1, 1948

By Ralph Arnold

Since 1915, when Elk Basin field was brought in, eight oil fields have been developed in Montana and the production has arisen from 50,000 bbl. in 1916 to 8,000,000 bbl. in 1926. The production for 1927 was 5,121,600 bbl. and the total up to the end of 1927 was 27,138,239 barrels. The eight fields, with their year of discovery are: Elk Basin, Carbon County (1915); Devil's Basin, Petroleum County (1919); Cat Creek, Petroleum County (1920); Soap Creek, Big Horn County (1921); Kevin-Sunburst, Toole County (1922); Lake Basin, Stillwater County (1924); Pondera, Pondera and Teton counties (1927); and Bannatyne, Pondera and Teton counties (1927). About 170 wildcat wells have been drilled in the state of which 8 were successful and 162 gas wells or dry. Hence, only one out of 21, or 5 per cent. of the wildcats have been successful. The average depth of the wells has been 1600 ft. and the average cost $32,000 apiece. • Up to Jan. 1, 1927, a total of 1376 wells have been drilled in the producing oil and gas fields of the state, of which 904, or 66 per cent., were successful oil wells; 82, or 6 per cent. were gas; and 390, or 28 per cent, were dry. The percentage of dry wells is excessive as compared to the wells in other states, due to the uncertainties of limestone reservoir rocks. The total production of oil to Jan. 1, 1927, has been 22,016,639 bbl. and of gas 7,265,330,000 cu. ft. The average price at the well for the oil has been $1.47 per bbl. and for gas about 4 c. per 1000 cu. ft. The value at the point of consumption has been about 23 c. per 1000 cu. ft. The total revenue derived from crude oil has been $32,277,119, and from gas 8350,613, or a total income to the producer of $32,727,832. Each well drilled in the state has already (to Jan. 1, 1927) averaged a return of over $21,000. The total number of domestic (Montana) oil and gas companies organized, since the first in 1885, has been 844, of which 702 are still alive and 142 dead. Oil and gas companies registered for operation within the state to Jan. 1, 1927, but with outside charters, are 143, of which 66 are alive and 77 are dead. Outside the few distributing companies, which are included in these figures, the grand total of 997 companies which have

Jan 1, 1928

By Paul E. Blackburn, Joan B. Berkowitz-Mattuck, Edward J. Felten

The oxidation behavior of MOSi2 has been studied between 450° and 650°C, the temperature region where "pesling" occurs. Disintegration ("pest-ing") of MoSi2 is shown to occur in the presence of oxygen, but not nitrogen, carbon dioxide, carbon monoxide. or argon. The rate of disintegration is extremely sensitive to oxygen pressure. The crack density of polycrystalline MoSi2 increases ivith lime at temperature. All kinds of cracks are observed: THE excellent oxidation resistance of MoSi, at temperatures of 1000 to 1700°C promises to have important technological benefits. However. the ap- Ihose which are confined within a single grain, those that ci'oss grain boundaries transversely, and those that follow grain boundaries. Laue photographs verify the existence of Iranscryslalline cleavage. Single crystals of MOSi2 do not "pest". Tlrcd solrlbility of oxygen in MoSi2 is extremely low, no lattice changes being observed as a result of exposure of MoSi2 to oxygen in the "pest" temperature range. plicability of MoSi2 is somewhat restricted by the occurrence of a completely destructive oxidation of the intermetallic phase at intermediate temperatures (300" to 6003C). This phenomena was ternled to be the "MoSi2 pest" by Fitzer who first observed it.' Molybdenum disilicide is a metallic material in both physical appearance and electrical properties.

Jan 1, 1965