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By Sidney Powers

INTRODUCTION THIS paper aims to present the results of an investigation concerning gravitative differentiation in lava flows, based on a quantitative microscopic and chemical study of a Triassic basalt from Nova Scotia, and confirmed by data secured from a study of certain Keweenawan ophites. At Cape d'Or, Nova Scotia, near the head of the Bay of Fundy, marine erosion has exposed a series of Triassic basalt flows in which copper has been sought for a number of years. Studies of the thickest flow of the series with regard to volumetric composition, specific gravity, and grain have been made by the junior author, and measurements by students at Tufts College, together with confirmatory observations of the same nature on this and other flows by the senior writer, and chemical analyses made by the Division of Mines, Mines Branch, Ottawa,1 all show differentiation in lava flows comparable to that in intrusive bodies. The work was made possible by the availability of the drill-cores, the property of Tufts College, and emphasizes the desirability of the study of drill-cores from other localities. Measurements of the specific gravities of certain Keweenawan lava flows of -Michigan by the senior author, from material collected in 1915, will be given as a comparison to those of the Cape d'Or flow. It has been found that the specific gravity of drill-cores, or volume per cubic foot, can be readily obtained by measuring their dimensions. This can be done to an accuracy of within 1 per cent. in pieces of core over 100 min. in length by using a micrometer gage for the diameter, and taking the average of six measurements of the diameter; and the average of four measurements of the length made with a finely graduated ruler. Then, after weighing them, the weight in grains per cubic centimeter, or what is practically the same thing, ounces per cubic foot, is obtained. System-

Jan 2, 1916

By Peter N. Blakey, Thiann R. Yu, Douglas O. Tansey

A flexible, efficient, and relatively low-cost drilling and blasting operation has evolved at Texasgulf Canada, Ltd.'s Kidd Creek underground mine. Located 32 km (20 miles) north of historic Timmins, Ontario, the underground operation utilizes a sublevel open stoping method developed with large-diameter blastholes. Over the years, Kidd Creek engineers have experimented with various drill-and-blast techniques, leading to the present-day practice. Continuing work is being conducted to further mechanize the blasting operation.

Jan 6, 1976

By Layson, W. C.

ACCORDING to the records, Phelps Dodge made its original entry into the production of copper in the oldest copper mines of Arizona at Morenci in 1881. The ore body now being mined as the Morenci open-pit, as outlined by churn-drill holes, diamond-drill holes, and underground workings, is estimated to yield 230,000,000 tons of ore averaging 1.06 per cent copper. This development will add 2,500,000 tons of copper to the 900,000 tons already produced in the district. Some five years ago preliminary development of the ore body began, with big-scale production planned including the erection of a new treatment plant to be built near the mine. Inasmuch as the Morenci open-pit was an entirely new project this required the grading of roads, establishment of mining benches, construction of railroad grades, building of railroad tracks, erection of shops, as well as the purchase of the necessary equipment to satisfactorily and economically maintain the schedules of production forecast. Along with the preparation of the main ore body it was also desirable to mine and deliver to an experimental mill a relatively small daily tonnage of typical ore.

Jan 1, 1942

By R. R. Harvey

Recent evidence has indicated that the films forming at crude oil-water interfaces are the result of naturally occurring su,rface-active components in the crude oil rather than oxidation products resulting from exposure of the oil to air. Since the presence of such films may strongly affect the displacement of oil from porous media, a knowledge of their composition and formatiorz is of fundamental importance. In this study, without the assumption of a specific mechanism, film formation is considered to involve the transfer of a weakly surface-active species in solution in the oil to the oil-water interface. The film gas law and the Gibbs adsorption equation may thus he applied to the system. The rigid films which form upon decrease of the oil-water interfacial area are considered a result of the very slow rate of re-solution of the film material into the oil. When the shrinkage of the interface is very rapid, the amount of film material leaving the interface is negligible, and the system may then be treated in the same manner as an insoluble film. The combination of these treatments leads to a new concept of the film factor in which it may he quantitatively related to the concentration of film-forming material at the interface. Suitable experiments can then yield the following information. 1. Original concentration of surface-active species in the oil. 2. The change of concentration with time. 3. Concentration of surface active species at the interface. 4. The change of this concentration with time. 5. Interfacial tension of the system at any time and its variation with time. 6. Equilibriunz concentrations for a given set of conditions. 7. Concentration requirements for solid film formation. 8. Molecular diameter of the adrorbed species. These calculations may be made solely from data taken from measurements on the original oil. While using the pendant drop method of interfacial tension measurement of crude oil-water systems, Bartell and Niederhauser' remarked on the thin, transparent, pliable, solid films or membranes which were often formed at the interface between crude oil and water. As a result of their observations of these films, Bar-tell and Niederhauser concluded: 1. The films are formed by material from the oil adsorbed at the interface rather than by a reaction at the interface. 2. The adsorption of the film-forming material is a rather slow process. 3. There are good indications that the process is reversible; i.e., the film constituents may re-dissolve into the oil. 4. The film will spontaneously spread over any new surface formed. 5. The process of adsorption at the interface is accompanied by a decrease in the interfacial tension of the system. Although they had proved that film formation was not due to a reaction at the interface, Bartell and Niederhauser were unable to demonstrate conclusively whether these film-forming constituents were present in the original reservoir oil or whether they were formed as oxidation products after exposure of the oil to air. Recent evidence seems to point to their presence in the original oil. Although the true nature of the film-forming constituents is still uncertain, these conditions would be fulfilled by the assumption of the presence of a slightly soluble surface-active component in the original oil. This component would migrate to a freshly formed interface because it would thereby lower the free energy of the system. The component at the surface constitutes an expanded monolayer which would become compressed, upon retraction of drop, due to the slow rate of re-solution of the film components into the bulk of the oil. It is possible, by involved extraction processes, to separate or at least concentrate this film-forming fraction. However, using the assumptions made above, the technique of monolayer film study may be applied to reveal much of the nature of the adsorbing material without resorting to an actual separation of the film-forming constituents.

By C. S. Smith, E. W. Palmer

For several years an investigation has been in progress in the research laboratory of The American Brass Co. to determine the thermal and electrical conductivities of most copper alloys of commercial importance and several of scientific interest. This paper contains such data on the binary alloys of copper with silicon, aluminum, manganese and nickel, and on a large number of ternary or more complex alloys. Some interesting general relationships between the thermal and electrical conductivities for all copper alloys at all temperatures are pointed out. The data for the copper-zinc, copper-phosphorus and copper-tin binary systems have already been published1,2 † except for the electrical conductivity at 200" C., which is given in the appendix of this paper. Literature on Thermal Conductivity of Copper Alloys The papers referred to above contained a summary of the figures available in 1929 for the thermal conductivity of copper alloys. There is given in Table 1 herewith a selection of the data that have appeared since that time. The measurements of Hanson and Rogers3 are particularly interesting since they cover a series of alloys in the alpha solid solution range and show the effect of heat-treatment. Their alloys were tested as annealed castings, and are not therefore directly comparable to the worked alloys measured in the present investigation, although the difference is small. Bailey's determinations4 were carried out on the alloys used by Lees6 in 1906, and extend his results to higher temperatures. It is most unfortunate that the alloys were not analyzed, for the approximate compositions given are hardly sufficient identification of the material. It is equally to be regretted that neither Hanson and Rogers nor Bailey give data for the electrical conductivities of their samples. Sager6, using the heat-wave method of King, determined the thermal conductivity of copper, nickel and four alloys of the two metals. His results are included in Table 1.

Jan 1, 1935

By C. S. Smith, E. W. Palmer

For several years an investigation has been in progress in the research laboratory of The American Brass Co. to determine the thermal and electrical conductivities of most copper alloys of commercial importance and several of scientific interest. This paper contains such data on the binary alloys of copper with silicon, aluminum, manganese and nickel, and on a large number of ternary or more complex alloys. Some interesting general relationships between the thermal and electrical conductivities for all copper alloys at all temperatures are pointed out. The data for the copper-zinc, copper-phosphorus and copper-tin binary systems have already been published1,2 † except for the electrical conductivity at 200" C., which is given in the appendix of this paper. Literature on Thermal Conductivity of Copper Alloys The papers referred to above contained a summary of the figures available in 1929 for the thermal conductivity of copper alloys. There is given in Table 1 herewith a selection of the data that have appeared since that time. The measurements of Hanson and Rogers3 are particularly interesting since they cover a series of alloys in the alpha solid solution range and show the effect of heat-treatment. Their alloys were tested as annealed castings, and are not therefore directly comparable to the worked alloys measured in the present investigation, although the difference is small. Bailey's determinations4 were carried out on the alloys used by Lees6 in 1906, and extend his results to higher temperatures. It is most unfortunate that the alloys were not analyzed, for the approximate compositions given are hardly sufficient identification of the material. It is equally to be regretted that neither Hanson and Rogers nor Bailey give data for the electrical conductivities of their samples. Sager6, using the heat-wave method of King, determined the thermal conductivity of copper, nickel and four alloys of the two metals. His results are included in Table 1.

Jan 1, 1935

By S. K. Nicol, A. R. Swanson, J. C. Day

Addition of oil to a suspension of hydrophobic coal particles can influence its dewatering characteristics. An agglomeration process occurs in which coal particles are held together by negative capillary pressure at particle/oil/water contacts. Consequently, the units round which flow can occur are enlarged and this improves dewatering parameters such as drainage rate, solids recovery, and equilibrium moisture content. This paper discusses processes which attempt to use this principle, in terms of metallurgical and economic efficiency. The discussion is augmented by results of recent experiments on the effect of oil addition to centrifuges and vacuum filters.

Jan 1, 1980

By H. W. Paxton, C. C. Busby

IT has been shown previously' that strain aging can markedly improve the tensile properties of low carbon martensites, especially the yield-tensile ratio, without seriously affecting the ductility. In view of interest in high strength steels, an investigation has been made of the effect of strain aging following tension or rolling on the tensile properties of A1S1 4340 in an attempt to obtain a tensile

Jan 1, 1957

By Haakon Styri

In discussion of Dr. Fitterer's paper on electrolytic separation of slag inclusions, some results from experiments on electrolyzing high-carbon steels at the SKF Research Laboratory were given. l We had been working for a number of years on chemical methods of separating the inclusions but could not find any solvent that would dissolve the steel without attacking some of the inclusions, particularly the sulfides in which we were mostly interested at the time, nor any that would dissolve all sulfide or silica in filings as fine as 300 mesh without attacking the iron. Electrolytic methods had also been tried without any real progress until we learned from the Bureau of Mines about the use of the collodion membrane around the anode. Our early difficulties were to some extent different from those of the Bureau of Mines, perhaps because of experimenting on steels of higher carbon content, but most of our difficulties were of the same nature as those of the Bureau. Formation of large quantities of basic hydroxides was traced to the use of impure and oxidized ferrous sulfate. To protect from oxidation from the atmosphere during electrolysis, after purer chemicals were obtained, a thin layer, 54 in. or less, of molten paraffin was poured over the surface of the cathode liquid, where it solidified. It was found desirable also to hold the cathode chamber slightly acid by initial addition of 0.1 per cent acid (sulfuric or hydrochloric) to prevent precipitation of the hydroxide. This acidity would decrease gradually and the cathode chamber would become neutral before the end of the electrolyzing. The increase in acidity in the anode chamber during our early experiments had appeared to cause attack of the precipitated sulfides in the residue, which originally was analyzed by volumetric method for sulfur, and for this reason a 10 per cent sodium citrate solution was substituted for the sulfate in the anode chamber. With the use of the more reliable Eschka method for sulfur determination (as in coke), there was however no serious attack on the sulfides in the anode chamber with a variety of different liquids, as shown in Tables 2 and 4. The Eschka method gives a higher sulfur value than

Jan 1, 1933

By S. W. Zehr, G. S. Murty, W. A. Backofen

AN observation by Squires, Weiner, and phillipsl has stimulated interest in a mechanism of deformation at high temperature (above -0.5 of the absolute melting point) that is not usually thought to be involved in the creep of metals. They found precipitate-free or "denuded" zones along grain boundaries normal to the stress axis in tensile specimens of a hydrided Mg-1/2 wt pct Zr alloy after slow straining at 450° and 500°C. Their suggestion that the zones were a result of directional diffusion of magnesium atoms was supported with calculations from Harris and Jones2 which also tended to identify the process as Nabarro-Herring (N-H) creep3,4—a process that is characterized by Newtonian viscosity, with stress (o) directly proportional to strain rate (C), and one that proceeds by lattice diffusion. Material transport by diffusion along grain boundaries is an alternative basis for Newtonian viscosity, as demonstrated by Coble,5 and is favored over N-H creep for fine grain size and lower temperature.6 In either case, the strain rate sensitivity of flow stress, defined as m = d log o/d log E (which commonly appears in the empirical a = KEW), is unity. The experiments to be described here gave metallo-graphic indications of diffusional creep which were no less clear than those just cited, but the associated m (as measured by the method of Ref. 7) was much more like that of a Bingham material. For true Bingham behavior, (a — ao) E, where oo is an initial yield stress. Therefore, even if flow after yielding should occur by diffusional transport, m must increase from 0 as < is raised to reach unity only in the limit as One result is that the resistance to tensile necking conferred by Newtonian viscosity is lost, which would become increasingly apparent through the formation of more sharply defined necks as 6 is lowered. That trend appeared in these experiments. Most of the work was done on an extremely finegrained alloy of magnesium with -6 wt pct Zn and ½ wt pct Zr (Mg ZK60); the initial mean-intercept grain diameter, L, was 0.55 µ. Shown in Fig. l(a) is a germanium-shadowed carbon replica of the surface of a specimen that was coated with silicone oil,* heated to 270°C under a helium atmosphere, and then stretched locally -200 pct at an initial E = 3.3 x 10-5 sec-1. Under

Jan 1, 1969

By G. R. Lehman

The Inspiration Consolidated Copper Co. had an orebody at Miami, Ariz., of close to 100,000,000 tons of low-grade copper ore, and the method of mining this ore most profitably was of great importance. The selection of a method was practically limited to a "top-slicing," a "shrinkage-stope" or a "caving" method. The "top-slicing" method would give a high extraction of the developed ore, at a high mining cost, and the "shrinkage-stope" or "caving" methods a lower extraction of the developed ore, at a lower mining cost. Ore-Drawing Tests To decide on the method to be used it was necessary to know about what extraction of the ore could be obtained by the "shrinkage-stope" or " caving " methods. As no definite information regarding the,question was available at the time, C. E. Mills, the general manager, thought that some information could be obtained by experimenting in drawing ore, covered with capping, from an experimental box. Some work had already been done along these lines by W. C. Browning for the Inspiration Copper Co. and by myself for the Live Oak Development Co. The idea was to represent as nearly as possible, in the experimental box, the conditions within an area of caved stopes of caved ore all ready for drawing. That is, the area was supposed to represent a semibroken mass with the capping above it in the same condition and ready to follow the ore downward as it was drawn out of the chutes under the ore. To represent the above condition, in the experimental box, crushed ore from the mine was placed in it to a given height, and red barren capping from the mine was placed on top of the ore. The Experimental Box The experimental box shown in Fig. 1 was made of wood and glass. The glass was used for the sides so that the drawing action of the outside row of chutes could be seen and noted, the latter being cut in the center by the glass sides. The length of the box was 30 in., width 20 in. and the

Jan 1, 1917

PRESIDENTS DAVID THOMAS 1871 R W RAYMOND 1872-1874 A L HOLLEY1875 ABRAM S HEWITT 1876 T STERRY HUNT 1877 ECKLEY B COXE 1878 - 1879 WILLIAM P SHINN 1880 WILLIAM METCALF 1881 RICHARD P ROTHWELL 1882 RICHARD W HUNT 1883

Jan 1, 1917

By E. M. Norris

THE Western phosphate deposits extend over a large area in the Rocky Mountain region, comprising portions of south central Montana, southeastern Idaho, northeastern Utah, and southwestern Wyoming. A limited acreage of these deposits passed into private ownership prior to Dec. 9, 1908, at which time 7000 sq. mi. of land in these phosphate fields was withdrawn from public entry by direction of the Secretary of the Interior. Under the Act of Feb. 25, 1920 (41 Stat. 437) title to all phosphate lands in the public domain was reserved to the United States with provisions for leasing portions to citizens, corporations, states, etc. The above act, in effect, created by law a Western phosphate reserve of approximately 2,269,055 acres.

Jan 1, 1944

By E. W. Davis

The: mysterious Lake Erie price for iron ore, established each spring, determines the maximum price that will be paid during the following season for ore of Mesabi Non-Bessemer base grade. This price is important to the ore producers, hut since most of the ore in the Lake Superior district is owned or controlled by consuming interests, the really important question to them is not the price of ore but how much it will cost them to mine and transport their season&apos;s requirements to their furnace plants. However, a few million tons are actually sold each year, and considerable quantities are traded for mixing purposes, and the negotiations lor these sales and trades usually begin with some reference to the Lake Erie price. There is no difficulty with the Lake Erie price itself or with the manner in which it is established, but the system prescribed for determining the values of ores that are not exactly base grade is incomplete. The Lake Erie price takes into consideration only the iron and phosphorus contained in the ore, but when the ore producer is negotiating a sale or trade, he is confronted by the fact that his ore must he studied and the price adjusted, not only on the basis of the iron and phosphorus analyses, as specified by the Lake Erie price, but also on the basis of silica! alumina, manganese, structure, etc. The vague and unsatisfactory methods used in making these adjustments bear some relation to the manner in which the ore is supposed to act in the blast furnace. The ore producer may not understand all of the idiosyncrasies of the blast furnace, but if the smelting-plant operators have a system more accurate than the Lake Erie price method for determining the relative values of different ores, why not pass this information on to the ore producers, so that they can make use of it and perhaps modify their practice in such a manner as to benefit both themselves and their customers? There is a lack of understanding and appreciation between these two groups that may, to some extent, be unavoidable, but in the interests of efficiency and conservation rules that are more accurate and complete than the Lake Erie price method in use at the present time should be established for the guidance of the ore producers. Recently a paper was read before the Eastern States Blast Furnace and Coke Oven Association, by Mr. G. W. Hewitt, Manager Production, Blast Furnace and Coke Oven Department, Wheeling Steel Corporation, in which he explained how his company determines the relative values of different grades of Non-Bessemer ore. This is a very important paper, perhaps not so much on account of the actual calculation methods described as because of the fact that premiums and penalties are shown on Non-Bessemer ores for silica, alumina, phosphorus, and manganese. As pointed out by Mr. Hewitt, the premium and penalty system described may not apply without adjustments to other smelting plants. However, if the various ore

Jan 1, 1941

By E. W. Davis

The: mysterious Lake Erie price for iron ore, established each spring, determines the maximum price that will be paid during the following season for ore of Mesabi Non-Bessemer base grade. This price is important to the ore producers, hut since most of the ore in the Lake Superior district is owned or controlled by consuming interests, the really important question to them is not the price of ore but how much it will cost them to mine and transport their season&apos;s requirements to their furnace plants. However, a few million tons are actually sold each year, and considerable quantities are traded for mixing purposes, and the negotiations lor these sales and trades usually begin with some reference to the Lake Erie price. There is no difficulty with the Lake Erie price itself or with the manner in which it is established, but the system prescribed for determining the values of ores that are not exactly base grade is incomplete. The Lake Erie price takes into consideration only the iron and phosphorus contained in the ore, but when the ore producer is negotiating a sale or trade, he is confronted by the fact that his ore must he studied and the price adjusted, not only on the basis of the iron and phosphorus analyses, as specified by the Lake Erie price, but also on the basis of silica! alumina, manganese, structure, etc. The vague and unsatisfactory methods used in making these adjustments bear some relation to the manner in which the ore is supposed to act in the blast furnace. The ore producer may not understand all of the idiosyncrasies of the blast furnace, but if the smelting-plant operators have a system more accurate than the Lake Erie price method for determining the relative values of different ores, why not pass this information on to the ore producers, so that they can make use of it and perhaps modify their practice in such a manner as to benefit both themselves and their customers? There is a lack of understanding and appreciation between these two groups that may, to some extent, be unavoidable, but in the interests of efficiency and conservation rules that are more accurate and complete than the Lake Erie price method in use at the present time should be established for the guidance of the ore producers. Recently a paper was read before the Eastern States Blast Furnace and Coke Oven Association, by Mr. G. W. Hewitt, Manager Production, Blast Furnace and Coke Oven Department, Wheeling Steel Corporation, in which he explained how his company determines the relative values of different grades of Non-Bessemer ore. This is a very important paper, perhaps not so much on account of the actual calculation methods described as because of the fact that premiums and penalties are shown on Non-Bessemer ores for silica, alumina, phosphorus, and manganese. As pointed out by Mr. Hewitt, the premium and penalty system described may not apply without adjustments to other smelting plants. However, if the various ore

Jan 1, 1941

By executive order of the President, dated June 25, 1918, the investigation of matters relating to gas warfare, which had been initiated by the Director of the U. S. Bureau of Mines early in 1917, and had been continuously maintained and improved since, that time, was transferred to the recently created Division of Gas Warfare of the War Department. On the occasion of this transfer, both the President and the Secretary of War took occasion to speak most highly of the efficient service that had been rendered by the Bureau of Mines. It gives us great pleasure to reproduce here a letter from the President and from the Secretary of War, bearing on this subject and also to append a brief review of the work of the Bureau of Mines, prepared by its Director, Mr. Van H. Manning. The White House, Washington. June 26, 1918. MY DEAR MR. MANNING: I have had before me for some days the-question presented by the Secretary of War involving the transfer of the chemical section established by you at the American University from the Bureau of Mines to the newly organized Division-of Gas Warfare in which the War Department is now concentrating all the various facilities for offensive and defensive gas operations. I am satisfied that a more efficient organization can he effected by having these various activities under one direction and control, and my hesitation about acting in the matter has grown only out of a reluctance to take away from the Bureau of Mines a piece of work which thus far it has so effectively performed. The Secretary of War has assured me of his own recognition of the splendid work you have been able to do, and I am taking the liberty of enclosing a letter which I have received from him, in order that you may-see how fully the War Department recognizes the value of the services. I am to-day signing the order directing the transfer. I want, however, to express to you my own-appreciation of the fine and helpful piece of work which you-have-done, and to. say that this sort of team work by the bureaus outside of the direct war-making agency is one of the cheering and gratifying evidences of the way our official forces are inspired by the presence of a great national task. Cordially yours, Dr. Van. H. Manning, WOODROW WILSON. Chief, Bureau of Mines, Department of the Interior. War Department, Washington, June 25, 1918. MY DEAR MR. PRESIDENT: In connection with the proposed transfer of the chemical section at. American University from the Bureau of Mines to the newly constituted and consolidated Gas Service of the War Department, which you are considering, I am specially concerned to have you know how much the War Department appreciates the splendid services which have been rendered to the country and to the Army by the Department of the Interior, and especially by the Bureau of Mines under the direction of Dr. Manning. In the early days of preparation and organization, Dr. Manning&apos;s contact with scientific men throughout the country was indispensably valuable. He was able to summon from the universities and the technical laboratories of the country men of the highest quality and to inspire them with enthusiastic zeal in attacking new and difficult problems which had to be solved with the utmost speed. I do not see how the work could have been better done than he did it, and the present suggestion that the section now pass under the direction and control of the War Department grows out of the fact that the whole subject of gas warfare has assumed a fresh pressure and intensity, and the director of it must have the widest control so as to be able to use the resources at his command in the most effective way possible. The proposal does not involve the disruption of the fine group of scientific men Dr. Manning has brought together, but merely their transfer to General Sibert&apos;s direction. Respectfully yours, NEWTON D. BAKER.

Jan 9, 1918

By Paul Beck

IT is well known that the hardness of metallic single crystals, like that of polycrystalline metals, increases during deformation (hardening by cold-work). It is also known that, as a consequence of deformation, the metallic material acquires an evident thermodynamic instability, revealed, for example, by the fact that the increased hardness gradually decreases with time, especially at elevated temperatures (softening by annealing). The temperature at which the stabilizing process begins is different for various metals, and for any metal it depends on the amount of deformation. Such stabilization of deformed metals may proceed in two different ways: through recovery, and through recrystallization. The former process allows the unstable deformed metal body to approach stability gradually and without visible change in the grain structure; the latter process, like an allotropic transformation, yields directly the undeformed stable "phase" in the form of new undeformed crystals, which, starting out of a certain number of nuclei, grow into and&apos; consume&apos; the deformed hard material. The extent of stability attainable through recovery is limited, espe-cially if the deformation of the metal crystal or crystals involves not only the gliding along slip planes, but also the bending of the slip lamellae, or at any rate the bending of comparatively large parts of the crystal lattice. In such cases, for instance in bent single crystals or poly-crystalline metals subjected to any deformation, recovery will not as a rule be able to restore the "straight" undeformed lattice, and stability can be attained only by recrystallization; that is, by the consumption of the bent crystal lattice parts by new, undeformed crystals-a much more drastic process. It is evident that the part of the surplus free energy stored in deformed crystals, which is present in the form of the elastic energy of the bent lamellae, is in these instances not considerably involved

Jan 1, 1937

By H. P. Willard, Conrad Martin

SINCE the deposits were found in 1927 in the Paradise Range of western Nevada, more than 1 mil- lion tons of magnesite and half a million tons of brucite have been mined and processed into a variety of granular refractory materials used as furnace linings by the steel industry. An additional million tons of magnesite were used during World War II to produce magnesium metal, and some magnesium oxide from the area is going into magnesia cements. Located near Gabbs, Nev., on the west flank of the Paradise Range, the principal bodies occupy an area a mile long by half a mile wide, and lesser occurrences have been found in a belt more than four miles long and in places almost two miles wide. Magnesite reserves containing less than 5 pct lime are estimated at more than 25 million tons. Reserves of better grade material are considerably less.

Jan 4, 1957

By C. W. Davis, R. S. Dean

AMONG naturally occurring inorganic compounds, magnetite has many unusual and interesting properties, and it is the purpose of this paper to call attention to these properties and review possible uses of magnetite that might be based on them; in other words, to see what uses may be found for magnetite as a physical rather than as a chemical entity, as a mineral rather than as an iron ore. The Mineral Physics Studies initiated in the Metallurgical Division of the U. S. Bureau of Mines a few years ago gathered together much information on mineral properties, and they are therefore the principal source of material for this paper. Magnetic Properties Of Magnetite And Possible Uses As A Magnetic Material Magnetite is unique among minerals for its great magnetic susceptibility, approximately one-third that of soft iron, and some magnetites are permanent magnets, or lodestones. The literature contains many measurements of magnetic properties of individual magnetite crystals, but no systematic survey of the effect of mechanical preparation and heat-treatment was available until the recent investigations of the Bureau of which included not only susceptibility but coercive force and remanence as well. For the purpose of orientation, Table 1 gives the magnetic properties of several samples of magnetite and of a few other substances3. This table indicates that when ordinary magnetite is powdered it decreases in susceptibility and increases in coercive force and remanence, approaching the properties of lodestone. The properties of lodestone are in fact probably due to the development of very large internal surface on fine grain size4.

Jan 1, 1937

By W. L. Prehn, Adele Chambers, R. L. Slobod

The centrifuge has been found to be an extremely useful tool for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. The use of the centrifuge for determining the properties of small core plugs has been discussed in the literature,&apos;,&apos; but practically no experimental evidence has been presented justifying the use of this method in preference to other methods (mainly disc method) now in use. Data have been accumulated and are now presented demonstrating the advantages of the centrifugal method, some of which are: (1) rapid establishment of equilibrium, (2) excellent precision yielding very reproducible results, (3) availability of high pressure differences between phases, (4) simple operational procedure, and (5) ability to establish connate water, residual oil, or to obtain complete capillary pressure curve in one day or less. A commercially available centrifuge capable of speeds up to 3,800 rpm, and a high speed attachment providing a maximum rate of rotation of 18,000 rpm were used in this work in conjunction with core holding tubes designed specifically for this application. In view of the outstanding advantages associated with the use of the centrifuge the conclusion has been drawn that this method should be used in place of the more tedious, slower, and less reliable disc method for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. INTRODUCTION The need for accurate values of connate water, residual oil, and capillary pressure curves in reservoir engineering has been recognized for many years, and the extent of the effort devoted toward solving these problems is reflected in the large number of papers3-" which have appeared in the literature during the past decade. Most of the methods discussed in the recent literature employ a porous disc as a semi-permeable membrane to separate two immiscible phases and make pos-ible the application of an explicit difference in pressure between two phases in the core. Thus, in the determination of the capillary pressure curve the wetting phase (water) is displaced by the non-wetting phase (air or oil). Several investigators1,2 have used centrifugal forces to develop pressure differences between phases. As a result of the first work&apos; in this field the conclusion was reached that "the more rapid centrifugal method for measuring irreducible saturation may have equal value, (compared to use of discs) but more work is required to establish this point." This work was followed in 1945 by a more detailed study2 in which the concepts of this experimental work were more clearly enunciated. A method for calculating saturation for any given speed of rotation based on the observed volume of water displaced was developed and a wider application of the method was suggested. The absence of any subsequent pertinent literature on this subject is interpreted as indicating that no additional work has been completed to substantiate or deny the earlier claims and suggestions of promise contained in the original papers on this subject. One purpose of this report is to provide evidence designed to establish the practical value of centrifugal methods in determining core properties such as connate water and capillary pressure curves. It is also our purpose to suggest a broadening of the scope of this tool to include determinations of residual oil by gas or water drives. THEORY AND PRACTICE IN USE OF CENTRIFUGE Hassler and Brunner2 have clearly presented the basic concepts involved in the use of the centrifuge by relating the performance of a small core in a field of high acceleration to the

Jan 1, 1951