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By E. A. Gulbransen, J. W. Hickman

Recent work by the authors1 on the oxide films formed on alloys of titanium and zirconium with nickel and copper indicated that an investigation of the oxides which form on alloys of copper and nickel might permit the relative rates of formation and diffusion of the ions of these metals to be determined. This binary system is of further interest since the alloys which form are of the solid solution type over the entire range. In addition nickel is much more oxidation resistant than copper. A comparison of the free energies of formation of the simple oxides which may occur on these alloys indicates that nickel oxide should be observed over the entire time and temperature ranges of oxidation for all alloy compositions~i In order for nickel oxide to predominate on the surface, it is necessary that nickel ions form and diffuse to the surface. Two factors which may influence the formation of nickel oxide may be the ionic sizes, where cu+ is o.,,6-,4 and ~i++ is o.,oh;, and the charges on the ions. On the basis of size, Ni++ should diffuse more readily than Cu+ while on the basis of charge, Cu+ should form more readily than Ni++. According to Uhlig2 passivity to corrosion in an alloy appears at a critical composition which for copper-nickel alloys is related to the tendency of the d band of electronic energy states to fill with elec-trans. This in in the copper- nickel alloys corresponds to 40 at. pct nickel at which composition Uhlig2 (quoting La Que's data) states that the alloy system becomes passive. Magnetic and specific heat data indicate that the d band of copper-nickel alloys is flied at 60 at. Pet Or or 4O at. pct nickel. Matt and Jones3 have shown that if, on alloying nickel with copper, one considers a copper atom to be identical with a nickel atom except for an extra electron (nickel has the configuration: 3ds 4s2 and copper: 3 dl0 4s) then at 60 at. pct copper or 40 at. pct nickel enough electrons are contributed by copper to fill the d band of the alloy. At this composition the magnetic susceptibility approximates zero according to Grew.4 Although the electron diffraction data will not determine the rates of the several reactions which may occur during oxidation, yet a determination of the structures of the surface oxides may yield information concerning the relationships, if any, which may exist between the oxide structures which form and that composition where the magnetic susceptibility approximates zero. It is quite possible, of course, that the mechanisms of the oxidation and corrosion reactions may be so widely different that no correlations between them may be possible. Survey OF Literature The metals, copper and nickel, which are face-centered cubic, form solid solution alloys which are face-centered cubic with no superstructure for all compositions. Three oxides of nickel have been investigated structurally by X ray diffraction. Of

Jan 1, 1949

By P. P. Scott, George C. Howard

A field remedial procedure utilizing a kerosene-cement slurry as a water plug-off agent in fractured formations was evaluated both in the laboratory and in the field. This procedure has proved to be capable of effectively shutting off water without causing permanent impairment of the oil production. Success was attributed to the fact that an immobile cement slurry, when placed in a water-producing strata, will set and form an impermeable barrier; whereas when placed in an oil-producing section the cement will retain a relatively high permeability and may be removed by acidizing. INTRODUCTION One of the most perplexing problems facing the oil industry is the selective exclusion of water production from oil or gas-producing wells. This problem has been studied by many investigators in an attempt to develop a material that is not only capable of reducing water production but is also capable of being selective in that it will not impair oil production in either fractured or intergranular type reservoirs. A study of these two types of formations indicated that two distinct types of materials for controlling water production might be required — a completely liquid plugging agent for intergranular formations and a semi-liquid or slurry type plugging agent for fractured formations. This paper is limited to the control of water production from fractured formations. A common source of water in the vicinity of oil bearing rock reservoirs is water which previously has entered and, because of its higher density, generally lies near the bottom of the formation. When the deepest point of penetration of a well into such an oil and water-bearing formation is above the level of the water, and the dynamical gradients due to the flow of oil overbalance the difference in densities between oil and water, water production becomes a problem. Then the water level rises in the shape of a cone and is produced from the lower depths. Other investigators1,2,3,4 have developed theories which define the pressure gradients and contours of this cone in a homogeneous formation and have shown that the placement of a plug in the bottom of a well is only slightly effective in temporarily reducing the flow of water. Assuming that the manner of flow of bottom water from fractured formations to a well is generally similar to the flow in homogeneous formations, then it would be expected that some form of coning, perhaps of less symmetry, would also occur. Then, because of the similarity of the manner of flow of water, placement of a vertical plug in a fractured formation would also probably be ineffectual for controlling water production. However, as has been shown by electric model flow study,' the placing of a plug in a well and an impermeable horizontal streak in the formation might prove to be a means for materially reducing or even eliminating water production in a fractured formation. An indication of the difference in effectiveness between horizontal and vertical plugs based on theory developed from study of the flow of water and oil in rock reservoirs is depicted in Fig. 1. These curves show the expected

Jan 1, 1955

By H. Stuart, L. Zwell, N. Ridley

specimen that was subjected to 700°C for 250 hr is shown in Fig. 2(c). The precipitates in this foil appear round and exhibit only very faint strain contrast. From this evidence, along with that described above for the symmetry of the strain field, it may be concluded that this coherent precipitate is spherical, which is generally the favored shape for coherent precipitates when the lattice parameter mismatch is small.12 These observations are consistent with the assumption that this precipitate is the y' (Ni3Al, Ti) phase. y' is known to be spherical in the early stages of precipitation. It is fcc and is similar in composition to the matrix and thus would have contrast similar to that of the matrix as do these precipitates. Direct identification of the spherical precipitate did not prove possible because of its low volume fraction and small size. The results of this investigation suggest that the increases in yield strength and the decreases in elongation observed in 45-Fe 30-Ni 20-Cr alloys containing about 0.4 pct A1 and 0.4 pct Ti on prolonged aging at 550" to 700°C are very likely due to the presence of a coherent, spherical precipitate, thought to be y'. Mi-crohardness measurements indicated that the precipitation of semicoherent M23C6 resulted in some matrix hardening. However, this precipitation process occurs much more rapidly than the changes in mechanical properties at these temperatures. 1C. L. Clark, J. J. B. Rutherford, A. B. Wilder, and M. A. Cordovi: J. Eng. Power, 1962, vol. 84, p. 258. 2 F. A. Comprelli and U. E. Wolff: USAEC Report GEAP-4745, General Electric Company November, 1964. 3C. N. Spalaris: A Monograph, USAEC Report GEAP-4633, General Electric Company, July, 1964. THERE have been many X-ray investigations of the room temperature lattice parameters of austenite which has been retained in quenched steels of various carbon contents. The results of these investigations have been collected by Wrazej,1 Wever et al.,2 and by Roberts3 and are included in Fig. 1 due to Pearson.4 The dashed line in Fig. 1 was considered by Roberts3 to most reliably describe the variation with carbon content of the lattice parameter of retained austenite. This line is given by the equation: a (Å) = 3.555 + 0.044 wt % C and recent unpublished measurements by one of the authors (LZ) support this relationship. The object of this communication is to draw attention to a relationship which describes the variation of the room temperature lattice parameter of 'equilibrium' austenite with carbon content, and which is different from that for retained austenite. The relationship a(Å) = 3.573 + 0.033 wt % C has been obtained from lattice parameter measurements made on equilibrium Fe-C austenites at elevated temperatures, which have been extrapolated to room temperature. The room temperature lattice parameter of 3.555Å which the Roberts' relationship gives for pure y-Fe is no: in agreement with the value of 3.573Å obtained when the high temperature lattice parameter data of Basinski et aL.5 and of Goldschmidt6 is extrapolated to room temperature. A linear extrapolation was

Jan 1, 1970

By D. C. Porterfield

ProUuction of crude oil in Venezuela increased from 186,134,000 bbl. in 1940 to 2~8,131,ooo bbl. in 1941, or 22.6 per cent, to establish a new all-time high for the country. While the average production for the year was 625,000 bbl. per day, production during the month of December 1941 averaged 751,000 bbl. per day, and during the last week of the year, 766,000 bbl. per day. Production from the Lake Maracaibo basin averaged 454,000 bbl. per day during the year, or 72 per cent of the total for the country, compared with 73 per cent of the total produced in 1940. Drilling during the year was approximately on the same scale as in 1940, with 438 wells completed in 1941 as compared with 429 the year before. Exploratory completions decreased from 18 in 1940 to 6 in 1941. Of the drilling operations in 1941, 56 per cent was concentrated in the Lake Maracaibo basin and 44 per cent in eastern Venezuela, success being 98 per cent in the Lake basin and 83 per cent in the east. Successful completions for the country as a whole amounted to 92 per cent of the total wells drilled. Exploratory drilling in 1941 resulted in the discovery of three new fields, all in eastern Venezuela; viz., Guara, about II km. to the northeast of the Oficina field but on a separate structure; Santa Rosa, which is east of El Roble field on a structure forming a part of the major Santa -Ana- San Joaquin-El Roble uplift; and Santa Barbara, which is southwest of the Jusepin field on an extension of the main Jusepin anticline. At the close of the year three wildcats were drilling, all of which showed prospects of obtaining production; that is, Mercedes No, 2 in central Guarico, Las Ollas No. I on the Anzoategui-Guarico border near the town of Zaraza, and Quiamare No. I in Anzoategui northeast of the town of San Mateo. In spite of heavy withdrawals and the resultant natural decline in the potentials of older producing areas, new drilling during the year increased the potential production of the country from an estimated 780,000 bbl. per day at the end of 1940 to an estimated 810,000 bbl. per day at the end of 1941, or approximately 4 per cent. Since domestic consumption of petroleum products is insignificant compared with total production, exports of crude and products during the year increased in line with production. Crude exports totaled 196,800,000 bbl., compared with 158,400,-000 bbl. in 1940, and exports of products were 26,100,000 bbl., compared with 21,900,000 bbl. the year before. Exports of crude from Venezuela to the United States amounted to 36,500,000 bbl. In addition, about 2,200,000 bbl. was imported in bond into the United States for transfer to Canada. Total refining capacity of the country in 1941 was approximately 125,000 bbl. per day, including a crude-conversion plant with a capacity of 32,000 bbl. per day, capable of making fuel oil only. Three plants with a capacity of 121,000 bbl. Per

Jan 1, 1945

By M. R. Geer, H. F. Yancey

Coal washing assumed an important role in the mining industry of the Pacific Northwest long before washing practice became firmly established in the Appalachian field. A Scaife washer was operated in the state of Washington in 1887; and by 1927, the fist year for which complete statistics were compiled, nearly a third of the state's coal production was washed, in comparison with only about 5 pct for the country as a whole. Mechanical preparation was adopted in Alaska in 1922 in a plant constructed by the United States Navy at Chickaloon to provide bunker coal for naval forces operating in northern waters. Many of the coal beds mined in Washington and Alaska contained more impurities than those mined elsewhere, and this circumstance contributed to the early interest in mechanical cleaning. A much more important factor, however, was the inclination of the coal beds. With steeply pitching beds, hand sorting by the miner at the face is impossible; consequently, all material must be loaded and dealt with on the surface, just as is now proving the case with mechanical mining of flat beds. Thus "full-seam" mining afforded the same stimulus to the early development of coal washing in the Northwest that it is providing under mechanization in the rest of the country today. Objeet and Scope ' This report is intended to provide a general summary of the status of coal-washing practice in Washington, Oregon, and Alaska—an area in which some of the coals mined are more difficult to wash than those mined elsewhere in the country. Detailed flowsheets of plants, statistical data on production, and cost figures have been omitted, largely for the sake of brevity but also because such information is principally of only local interest. On the other hand, considerable washability data have been included because they are Washington At present Washington leads all other states in the percentage of its total production that is cleaned mechanically, 82.1 pct in comparison with the national average of 25.6 pct in 1945.' The washing problems encountered in this state are highly variable because the mountain-building forces that created the Cascade Range caused such intense folding and faulting of the beds in some fields that the rank of the coal was increased to anthracitic, while in other fields more distant from the mountains the beds were relatively undisturbed, and the rank of the coal ranges down through subbituminous to lignitic. The complicated and burdensome schedule of sizes prepared in most coal fields has never been required by the Washington market. With but few exceptions, lump is prepared on a round-hole screen of about 3 in. size, egg is about 3 to 1 5/8 or 1½ in., and nut is 1 5/8 or 1½ in. to either 1 or ¾ in. Some mines screen no finer than ¾ in. and market a slack coal of that top size, but generally the coal is screened at about ¼ in. to give a stoker coal of ¾ or 1 to ¼ in., and a ¼ in. to 0 "buckwheat." During recent years the market for lump coal has largely disappeared, and lump is crushed to supplement the pro-

Jan 1, 1950

By T. W. Healy, P. Somasundaran, D. W. Fuerstenau

The flotation behavior of quartz in the presence of alkyl ammonium acetates as a function of alkyl chain length has been interpreted in terms of hemi-micelle formation at the solid-liquid interface. The van der Waals cohesive free energy that is responsible for hemi-micelle formation has been found from these results to be 1.0 kT per CH2 group. This is in excellent agreement with literature values obtained from research on the properties of micelles in bulk systems. Collectors of the type CH3(CH2)n-2CH2-P, where P is a polar group and n is the number of carbon atoms in the straight alkyl chain, will induce flotation of an appropriate mineral at lower concentrations as n increases. This reduction in collector concentration with increasing n has been reported for such systems as xanthates on sulfides1,2 and amines on quartz.' The effect of chain length of alkyl surfactants on such solution properties as conductivity,' surface tension,' and solubility6 and such interfacial properties of solids as contact angle7 and electrokinetic potential8 have received considerable attention, but only limited quantitative descriptions of the effects have been given. The electrokinetic studies of alkyl amine salts on quartz indicated that the solution concentration of collector at which the marked change in electrokinetic potential of quartz occurs decreases systematically as the length of the alkyl chain increases. The aim of the present work was to obtain a quantitative description in terms of current theories of flotation of the effect of the hydrocarbon chain of alkyl ammonium acetates on the flotation behavior of quartz. BASIC PRINCIPLES The marked changes in electrokinetic potentials of quartz in dodecylammonium acetate (DAA) solutions were postulated to result from the association of adsorbed collector ions into two-dimensional aggregates, called hemi-micelles.9 Subsequently, the rapid increase in flotation rate of quartz was shown to coincide with hemi-micelle formation." We would like to discuss briefly the concept of hemi-micelles in terms of recent interpretations of micelles in bulk solution. Micelle hypothesis: In dilute solutions, alkyl ammonium and related salts behave as ordinary strong electrolytes, but at a certain concentration there is a marked change in physical properties of the solutions, e.g., in equivalent conductance, transport number, freezing point lowering and viscosity. To account for these phenomena, McBainl1 introduced the concept of micelles, which are aggregates of long-chain ions. It is believed that the ionic heads of the constituent ions of the micelle are in contact with water, whereas the nonpolar groups turn away from it and are in contact with each other. Work must be done to bring these charged polar groups together, but energy is gained (i.e., so called van der Waals cohesive energy) when hydrocarbon chains are expelled from the water and allowed to associate. For a given polar group, the tendency to form micelles will therefore strongly depend on the hydrocarbon chain length. Theoretical treatments of micelle formation by Shinoda12 and Phillips13 and others lead to the following expression for the concentration at which micelles form (the critical micelle concentration or cmc) in aqueous solutions of long- chain electrolytes

Jan 1, 1964

By W. C. Winegard, E. L. Holmes

The effects of the solute elements lead and bismuth on grain growth in zone -refined tin have been investigated. At low temperatures, viz. below 160°C. or at high concentrations, viz. greater than 0.03 at. pct, the temperature dependence of grain growth was found to be constant. A correlation was found to exist between the rates of grain growth in the presence of solute impurities and the factor [C Ir - 1]2 , where C is the solute concentration, r is the radius of solvent atom, and r' is radius of solute atom. It is shown that the Liicke and Detert theory does not give a satisfactory explanation of the results obtained. INVESTIGATIONS of grain growth in zone-refined lead and tin and some effects of solute elements on grain growth in these metals have been reported by Bolling and winegardly2 and Holmes and winegard? The present investigation is an extension of the previous work, and was undertaken to provide additional results which might make it possible to discover the mechanism whereby the rate of grain growth is affected by the presence of foreign solute atoms. The experimental procedure was exactly the same as that described previously.3'4 Figs. 1 and 2 show the results obtained with lead and bismuth additions over the same temperature range, viz. 167" to 220°C, as that used for the investigation of grain growth in zone-refined tin.3 Fig. 3 shows the results obtained for zone-refined tin and for this tin with lead solute additions over an extended temperature range. DISCUSSION OF RESULTS As mentioned previously,3 the character of grain growth in the particular zone-refined tin used in these experiments appears to change as the temperature of annealing falls below about 160°C. The grain growth became somewhat irregular and was characterized by a jaggedness of many of the grain boundaries. The reason for this change is not known, but may be due either to residual impurity effects or possibly an oxide precipitation. It was obvious that normal grain growth only occurred in the zone-refined tin through the high-temperature range 167" to 220°C, and so the effects of solute atoms on grai11 growth over the two temperature ranges will be discussed separately. a) Effect of Impurity on Grain Growth in the Temperature :Range Above 167°C. It is apparent from Figs. 1 and 2 that, for low concentrations of solute, the rates of grain growth tend towards a common value as the melting temperature of tin is approached. As the concentration of lead is increased, the rate of grain growth close to the melting temperature is also reduced, and at high concentrations the temperature dependence of the rate of grain growth appears approximately constant. It should be noteil that the effect of bismuth is greater than that of the same concentration of lead, but both these solutes have a smaller effect on the rate of grain growth than silver, as seen from an earlier investigation of Holmes and Winegard. It should

Jan 1, 1962

By T. D. Tiemann

The caustic extraction of silica from Wisconsin and Minnesota taconite was investigated by bomb digestion over the temperature range from 312 to 40S°F at caustic concentrations from 25 to 500 gpl. Residual concentrates containing as much as 65 pct iron were obtained. The high rate of silica extraction is related to a microcrystalline variety of quartz, since it is shown that the rate of extraction of silica from quartz is directly proportional to its surface area. Increasing dependence on foreign ore reserves makes the need for developing the technology necessary for treatment of our low grade ores even greater than it was at the time of World War 11, when much research was conducted on the extraction of alumina from clays. Representative of these were the studies carried on at the University of Illinois.' More recently, the U. S. Bureau of Mines investigated the production of alumina from anorthosite, and currently the aluminum industry is showing renewed research interest in this field. The studies reported here are part of a continuing research program based on the above concepts and aimed at the eventual development of processes for the treatment of low grade ores, particularly those of iron. The fact that large reserves 3 of low grade nonmagnetic taconite are contained in the iron formation of the Wisconsin Gogebic range have made this ore an important and attractive target for investigation. The idea of removing silica by caustic extraction is not new.495 The digestion in caustic solution of ground flint, diatomite, and other forms of chalcedonic silica is the basis for the production of soluble sodium silicates by the wet-process. Upgrading bauxites by the caustic extraction of silica has been investigated6 and is the subject of a German patent.7 Although mention is made by Roe' of the caustic extraction of silica from low grade Michigan and Wisconsin iron ores, and he lists a number of patents and references on the subject, recent work in the field does not appear to be extensive. As far as the author knows, there has been no work in this field on these particular ores. It is hoped that this paper will stimulate further investigation which will eventually lead to an econclmic means of processing these large low grade reserbes. TACONITES The taconites investigated in this study were from Minnesota and Wisconsin. That from Minnesota, a semi-taconite, Nas obtained from the Oliver Iron Mining Division, U. S. Steel Corporation, and represents a sample of an oxidized iron formation from their King Mine on the Mesabi range. The Wisconsin taconite came originally from the trench sampling of the U. S. Bureau of Mines, and represents a composite of the Norrie, Pabst, Yale, Plymouth, and Pence members of the Gogebic iron formation. Assays on these samples are given in Table I. A typical calcu1atr:d average analysis of the Wisconsin taconite is given in Table 11. Chemically, the Minnesota semi-taconite sample contains about 39 pct iron and 39 pct silica, while the Wisconsin taconite contains 30 pct iron and 53 pct silica, both on the dry basis.

Jan 1, 1962

By E. E. Donath

THE coal hydrogenation process is well known as a means for the production of liquid fuels -from coal. In this paper the possibilities of the coal hydrogenation process as a source of chemical raw materials will be discussed. The recovery of chemicals from coal hydrogenation products necessitates some modifications and additions to the equipment used for the production of fuels. The conversion of coal into liquid fuels such as gasoline requires two steps: liquid phase and vapor phase hydrogenation. Intermediate oils obtained in the liquid phase contain oxygen and nitrogen compounds, especially aromatic compounds, since the coal itself is composed mainly of cyclic compounds. These oils are the raw material for the separation of high molecular weight aromatics and of tar acids and tar bases. The relative amounts of heavy and middle oil-boiling above and below, e.g., 325°C-can be influenced by temperature, residence time, and catalyst of the liquid phase hydrogenation. In the vapor phase hydrogenation a solid bed catalyst is used to convert the intermediate oil from the liquid phase operation into hydrocarbons of the gasoline boiling range. Essentially pure hydrocarbons with a low content of sulphur, oxygen, nitrogen, and olefines are obtained. Depending mainly on the catalyst, the high ring compound content of the liquid phase oil can be preserved and gasoline rich in aromatics obtained. However, with other catalysts, these ring compounds can be split into gasoline with a high content of isoparaffins.1 Again, depending on the operating conditions, products of varying boiling range can be obtained. Selection of catalyst and operating conditions therefore makes possible the production of different grades of motor fuel and also variations in the relative amounts of benzene, toluene, and xylene when aromatic hydrocarbons are produced. The schematic flowsheet, Fig. 1, shows the main steps of the coal hydrogenation process, and the product streams used for the recovery of chemicals are indicated. In the liquid phase hydrogenation stage, coal is made into a paste with recycle heavy oil. The coal paste is mixed with hydrogen and preheated at a pressure of 300 to 700 atm in heat exchangers and preheaters. The coal paste and hydro¬gen enter high pressure converters where the liquefaction of coal, conversion of the high boiling liquid materials initially obtained, into intermediate oils is performed at a temperature around 470°C. The reaction products enter the hot catchpot in which lower boiling oil vapors are separated from the residue containing unreacted coal, ash, and heavy oil. This residue, usually called H.O.L.D. (heavy oil let down), is processed to separate solid and liquid material. By thermal treatment of the residue, e.g., a coking process, distillate oil is obtained, which can be recycled as part of the pasting oil. This stream is rich in polynuclear aromatics and can be, and has been, used for the recovery of such material. The oil vapors and hydrogen from the hot catch-pot are cooled in heat exchangers and a cooler, and the condensed oil is separated from the recycle hy-

Jan 1, 1952

By H. Buttner, F. H. Udin, J. Wulff

GRAIN boundaries, the interface between adjacent crystals differing only in respective orientation, have been the object of much experimental and moderate theoretical attention for many years. The earlier experimental work was primarily concerned with the effect that grain boundaries have on the physical behavior of metals, while the basic nature of the boundaries themselves drew only secondary attention. A complete turnabout has been witnessed in more recent years, however, as researchers are now undertaking investigations bearing as directly as possible on the character and physical properties of the grain boundary. Quite comprehensive reviews of the past literature on the subject of grain boundaries have been reported on numerous occasions by various authors, and together these references represent a thorough coverage.'-? It becomes evident in these reviews and other papers"" that the properties of grain boundaries can be explained by regarding a grain boundary as a crystalline region of transition between two unmatched grains. Studies show that grain boundaries have a definite interfacial energy. By measuring the geometry about a point where three interfaces meet in equilibrium, the energy of any two boundaries can be measured with respect to the third. If the absolute interfacial energy of one boundary is known, the absolute energy of the other two boundaries can be calculated. This apparently holds true for any system of phases and interfaces.""25 Most studies have been carried out on solid-solid or liquid-solid systems, or systems of both. However, if about the point of intersection one phase is vapor and the other two are disoriented grains, then two interfaces are surfaces, and one is a grain boundary. Investigations leading to relative grain boundary energy for this particular system have been made by Fullman,23 Greenough and King," and Bailey and Watkins." Herring" treats the system mathematically and arrives at an equation, which appears as Eq. 1, in a form consistent with the reference angles indicated in Fig. 1, ( d?1 ?n = x sina + cosa ( ------- 2 ?2 Sinß da + C0Sß (d?2/d As the system of interfaces comes to equilibrium, a groove of angle appears at the intersection of the grain boundary with the surface, an effect first observed by Rosenhain and Humfrey." Eq. 1 is essentially a summation of the vertical components in Fig. 1 set equal to zero, where ?1 and ?2 are surface tension vectors lying along the side of the groove at point 0 in the groove root. The differential vectors represent the forces tending to rotate the surface into a position that will expose a crystal cleavage surface of lowest energy. Chalmers, King, and Shuttleworth- simplify Eq. 1 by assuming the differential vectors equal to zero, ?1 = ?2= ?Surface and arrive at the following equation: ?B = 2?s cos [2] Greenough and King24 use Eq. 2 for determining the grain boundary energy of silver using prepared bi-crystals of known orientation. Bailey and Watkins25 have done the same for copper, as did Chalmers and others on lead. These authors report the grain boundary values as ratios relative to the surface energy. In the above work, the orientation of grains forming the grain boundary in all cases was controlled so

Jan 1, 1954

By E. P. Abrahamson

The effect of transition element binary solid solution additions upon the re crystallization temperature of nickel has been investigated. All additions raised the re crystallization temperature. Both the rate of change of re crystallization temperature with at. pet solute and the limit of initial linearity are found to correlate with the free atom ground state outer electron configuration of the solute element. A comparison of all of the correlations for the transition elements studied has yielded a set of empirical relations, which allows the prediction of the effect of dilute binary transition elements on the recrystallization temperature of other transition elements. The work of Abrahamson, et al.1-7 on dilute binary solution alloys indicated a correlation between the free atom ground state electron configuration of the solute and both the brittle-ductile transition and re-crystallization temperature. Further, it has been shown3,4 that the limit of initial linearity may also be correlated with the solute electron configuration. Since previous studies have dealt with bee and hexagonal base elements, this study is made to note what effect, if any, the fee base structure might have. Nickel also serves to give a solvent configuration which will allow the comparison of all of the transition element solvents. Olsen8 has studied the effect of some trace elements upon the recrystallization of nickel. He included only Ti, Zr, W, Mn, and Co of the transition elements. The differences in change of recrystallization temperature were attributed to the solute atom size and to the solubility of the solute in nickel. PROCEDURE All alloys were made using 99.9 + pet Ni with 0.003 C, 0.015 Fe, 0.007 0, and 0.0007 H. The solute elements were 99.9 + pet pure. According to the published binary phase diagrams9 and metallo-graphic examinations at X750, all solute elements were in solid solution. The alloys were arc melted and remelted four times in the form of cubic 200-g buttons under an argon atmosphere. They were then hot forged at 800oC to 0.750 in. diam, machined to 0.60 in., vacuum annealed for 1 hr at 700°c, swaged to 0.40 in. and annealed at 700oC for 1 hr in vacuum. The grain size was checked and found to be 77 * 20 grains per sq mm. The specimens were then swaged to 0.187 in., yielding 76 ± 1 pet cold work. All alloys were then chemically analyzed for the solute addition. The interstitial contents remained at the values of the starting material when checked on random alloy specimens. The swaged rod was cut into 8.25 in. lengths and heat treated in a gradient furnace for 1 hr. The gradient was maintained at 250" to 850°C over an eight inch length, recorded by twelve thermocouples. Control was ± 3oC, accomplished at the hot end. The recrystallization was determined metallo-graphically over the entire specimen. The criterion chosen was that point on the specimen showing the first recrystallized grain at a constant magnification, X200. Specimens were repeated, and the agreement was found to be generally ± 3oC.

Jan 1, 1962

By C. E. Morris, S. R. Pollack

Current -vo1tage -temperature characteristics were studied for Al-A12O3-Al, Au structures. The oxide film was grown by gaseous oxidation in an 0, glow discharge. The electron-transfer mechanism was identified as tunneling and the barrier heights and thickness were determined. It was found that the barrier height at the parent aluminum-oxide interface is 1.5 ev and the built-in vloltage with an aluminum counter electrode is 0.35 v. The growth mechanism of the oxide is also discussed and it is suggested that Mott&apos;s theory is not applicable in describing the growth. Discrepancies were observed in the detailed comparison of tunneling theory, based on a trapezoidal model, with the data, and several possible explanations are discussed. THEORETICAL analyses of electron tunneling from one nonsuperconducting metal to another through an extremely thin insulating film have been presented.1-6 These calculations relate the current density, J, to the voltage, V, between the two metals, and to the temperature, T. The results of these calculations indicate that the magnitude of J and the detailed shape of the J-V characteristic will in general depend most strongly upon such properties of the insulating film as the thickness, the dielectric constant, and the structure of the electron energy barrier profile. The experimental results of many7-11 workers have corroborated the main features of these calcu- lations and have in fact been used to determine properties of the thin insulating film. It has been demonstrated, for example, that the tunneling current formulation of simmons4 is adequate to describe the observed J-V characteristic over approximately 10 orders of magnitude of current. Furthermore, from these observations and analyses, insight into the nature of the A1-A12O3 (thermally grown) interface region has been obtained.&apos;&apos; The temperature dependence of the tunnel current has also been studied and, although a self-consistent set of tunneling parameters can be chosen to describe these data at low voltages (i.e., <0.5 v), the tunneling parameters are different from those obtained from higher voltage (i.e., of the order of 1 to 5 v) measurements." We have measured the effect of temperature and voltage upon the tunnel current at higher applied voltages and find that the theory is inadequate to describe all of the effects reported here. A discussion of the origin of this inadequacy is presented following a description of the samples used for these experiments, and the experimental results. SAMPLE PREPARATION Metal-insulator-metal structures were fabricated in the following way. A 99.999 pct A1 charge was used to deposit, in vacuo, thirty films, 2000Å thick, onto a 1 by 2 in. glass substrate (7059 Corning glass). Prior to deposition the substrate was glow-discharged for final cleanup and then baked at 200°C for 2 hr at a pressure of 5 x 10-7 torr. The pressure during deposition of the metal films was 2 X 10-6 torr and the deposition rate was 50 to 100Å per

Jan 1, 1965

By W. Seymour

Uranium was cold rolled to a reduction in thickness of 90 pct and the preferred orientation of the grains was determined from X-ray intensity data. Complete pole figures for a large number of atom planes were plotted, and the preferred orientation was found to be duplex (102) [0101 + (012) [021]. These preferred orientations are compared with those reported for many of the hexagonal-close-packed metals. THE preferred orientation of a highly reduced cold-rolled uranium strip was determined in order to obtain additional experimental data which would be useful in further understanding the deformation mechanisms of uranium. The preferred orientations reported herein are not in agreement with those theoretically predicted by Calnan and Clews&apos; for cold-rolled uranium sheets, and differ somewhat from those reported from experiments by Fisher, and Burke and Turkalo. Such variations might be accounted for by differences in the fabrication temperature and the reductions. Experimental Procedure The uranium used in this investigation had been hot rolled to 0.060 in. at 575°C from 0.393 in., and from a 0.060 to 0.020 in. thick sheet at 275°C. From this point the sheet was cold reduced 90 pct to 0.002 in. at room temperature. Three specimens were used to obtain complete pole-figure data. The first was a 1/2 in. square section illuminated by the X-ray beam on the rolling surface. The other two were l/2 in. square longitudinal and transverse sections each made as follows: Approximately 200 1/2 in. square sections of the foil were piled one on top of the other, so that the rolling direction for each piece was kept coincident. A 1/2 in. square by 1/8 in. thick steel section was placed on the top and bottom of a pile and the entire assembly was then bolted tightly together through a 1/8 in. diam hole drilled down through the center. Each pile was then surface-ground from the two proper sides to sections 1/2 in. square by 3/16 in. thick. These specimens were then polished flat and electro-polished to remove 0.005 in. of the surfaces to be examined. It can be shown that uranium is so opaque to a Cu Ka X-ray beam that only a small percentage would be transmitted by one micron of uranium. Therefore, a method of measuring the X-ray intensities diffracted from specimen surfaces was used. The specimens were mounted in a modified Schulz reflection holder&apos; which automatically changed the position of the specimen at a constant rate. The holder, in turn, was mounted on a General Electric XRD-3 Spectro-Goniometer and an automatic record made of the diffracted X-ray intensity vs specimen position. While a specimen moved automatically through 10" inclination, at a rate of l° per min, it simultaneously rotated 360" about a normal to the illuminated surface. (The inclination and rotation angles are referred to as F and a, respectively.) The data were then plotted along the resulting spiral path on a stereographic projection, Fig. 1. Because of defocusing effects on the diffracted beam which occur when diffracting surfaces are in-

Jan 1, 1955

By Morris Muskat

It is pointed out that the application of capillary pressure curves obtained by drainage or desaturation processes to the calculation of the fluid distribution in interphase transition zones involves a number of difficulties; namely: (I) the development of very low nonwetting phase saturations appears to be in contradiction with the lack of mobility of such distributions indicated by permeability-saturation curves, (2) dispersed nonwetting phases are thermodynamically unstable, and (3) discontinuous phases should not be subject to hydrostatic equilibrium requirements. While these difficulties could be obviated by assuming that the capillary pressure drainage curve has an initial horizontal segment, they are automatically circumvented by application of the imbibition capillary pressure curve to the lower part of the water-oil transition zone. These generally show zero displacement pressure at only partial wetting-phase saturations. The countercurrent upward flow of oil into the main oil-saturated pay and downward drainage of water also suggests that wetting phase imbibition processes will control the saturation distribution immediately above the water-saturated section. Similar considerations, with a generalized interpretation of the apparent wetting-phase behavior of the oil and gas phases, provides a basis for constructing the curve for fluid distribution in the oil-gas transition zone. In the transition zones so derived, the oil begins with a nonvanishing saturation at the water-oil contact and terminates with a similar saturation at the top of the gas-oil contact. The gas-oil transition zone begins with an equivalent nonvanishing gas saturation. Introduction It has been a common assumption for some years that the nature of the fluid dis- tribution in virgin reservoirs, and in particular that in the transition zones between the oil and water and between the oil and gas sections, can be computed by a simple application of capillary pressure data. The results of such calculations appear to have been first reported by Leverett.&apos; The latter, however, indicated only the numerical values of the parameters used in the computations, without explicitly describing the procedure. Leverett&apos;s illustrative calculated transition zones are reproduced in Fig I. Although no critical study of the apparently obvious method of calculation has been published, one cannot proceed very far in the computation without encountering some rather fundamental questions not yet answered in the literature. This paper is not written under the pretense that the whole transition-zone problem has been fully and satisfactorily solved. Its purpose, rather, is to discuss suggestions for its treatment, much of it admittedly hypothetical, and emphasize the nature of the uncertainties arising therein; for the literature, as now available, gives little indication that there are any problems still outstanding. The Transition-zone Equation The basic equation, which presumably gives directly the fluid distribution without recourse to any further consideration, is: Ap = (r1 - r2)gh [1] where r1, y2 are the densities of the two contiguous fluids, h is the height above the "capillary-free" zone of complete saturation with fluid I, g the acceleration of gravity, and Ap is the capillary pressure across the average interface at the height

Jan 1, 1949

By Harvey Cline, Donald P. Ferriss

THE violent outgassing of commercial tungsten and other refractory metals when melted in an electron beam zone refining apparatus1"3 is dealt with experimentally by one or both of two approaches. One is to provide a suitable emission current control1,2 the other is to purify the metal in the solid state before melting.4 The first of these is usually sufficient, but the authors chose also to investigate the source of the troublesome gases and to devise means of solid-state purification. Some further insights into the use of tungsten as a structural material at temperatures near its melting point were also revealed in the course of the work. One may speculate on the causes of gas formation in tungsten at high temperature by inferences from the literature and an examination of the impurities in commercial wire. Davenport5 observed microporosity in both tungsten and molybdenum filaments heated to several hundred degrees below their melting points. Studying the function of oxygen in molybdenum welds, Perry, Spacil, and wulff8 attributed similar porosity to the disproportionation of Moo2 to molybdenum metal and Moo3. Tungsten dioxide also disproportionates7 above 2000oC to yield WO3 vapor at considerable pressure. Commercial tungsten contains some 5 to 20 wt ppm O and a similar concentration of carbon depending on the details and precautions of processing. Therefore, evolution of CO is also a strong possibility as a source of gas at high temperatures. Furthermore, even for activities in the order of 0.01, it may be calculated that the pressure of CO at 3000°C would be over 4000 psi, which is in excess of the tensile strength of tungsten at this temperature.9,10 Powder metallurgy tungsten contains some 0.02 pet Fe and 0.002 to 0.005 pet of the elements Ni, Si, Al, Ca, Mn, Mg, and Mo; at temperatures over 2800°c, therefore, these elements will exhibit appreciable vapor pressure, though small compared to that of WO3 and CO. Some of these impurities may react to form high-pressure monoxides such as SiO and A10. Finally, dissolved and occluded nitrogen is an ever-present source of high-pressure gas. Commercial Type 218, General Electric filament wires, 0.025 in. diam, were heated by resistance in 10 -4 mm of Hg and in argon or hydrogen at pressures from 50 µ to atmospheric. For temperature determinations in vacuo, the Jones - Langmuir8 current-temperature relationship was employed. For gaseous atmospheres, the burn-out temperature was assumed to be the same as in vacuo so that a small, constant correction could be made for temperatures below burn-out conditions (i.e., local heating to failure). Several dozen experiments may be summarized by pointing out some structural observations. At 3050oC in 1 atm of A, porosity is very evident after 30 min, as shown in Fig. 1. For the section in Fig. 2, failure occurred 200°C below the melting point and many voids have grown in the grain bound-

Jan 1, 1962

By Kefton H. Teague

Attempts to locate domestic supplies of sillimanite have been unsuccessful until recently. This paper describes recent discoveries of sil-limonite-bearing schists in the Southeastern States, with emphasis on geology of the deposits, mineral composition, origin, and reserves. Statements concerning possible methods of mining, milling, and utilization of sillimanite are given. Results from refractory tests on a laboratory scale are summarized. SINCE 1917, when synthetic mullite was first used in spark plug porcelains, there has been a continued search for natural sillimanite. During the recent war this search was intensified, not only for sillimanite but also for any materials which could be used satisfactorily as a substitute for the imported kyanite from India. The Indian massive kya-nite does not decrepitate during calcination as does our domestic bladed kyanite, thus a coarse grog can be obtained from it. Some of the most promising domestic materials suited for high temperatures are limited in quantity. Massive topaz from Chesterfield County, S. C., showed promise of possessing desirable refractory properties; but the action of combined fluorine, liberated during calcination, upon equipment and surroundings, as well as a limited supply of ore and the presence of impurities discouraged its use. Residual lumps and boulders of massive kyanite, similar to the material imported from India, occur in Georgia. This material, like the massive topaz, is of limited quantity. Andalusite from California and dumortierite from Nevada are satisfactory high-temperature refractory materials. Their uses have been restricted to specialized products since the location and character of the deposits are such that large production is impractical. Sillimanite, like kyanite and andalusite, has the theoretical chemical composition of Al2SiO5. It has a hardness of 6 to 7; vitreous, silky to subadamantine luster; specific gravity of 3.2 to 3.3; and is gray to bluish gray in color. Under the binocular microscope, the crystals are transparent. The mineral may occur as dense, fibrous mats (fibrolite) composed of fibrous, sometimes radiating hair-like crystals in schist which are associated with igneous intrusions. Deposits of this type have widespread distribution, but none discovered to date appears to have commercial possibilities. Sillimanite also occurs as bundles of crystals disseminated in biotite schist, as noted in the Hart-Elbert-Madison County, Ga., area and in some of the South Carolina and North Carolina deposits. This type of material has been called prismatic sillimanite by the U. S. Bureau of Mines. Deposits of this variety appear to offer commercial possibilities. When heated above 1650°C, sillimanite expands about 6.5 pct and is converted into a mixture of mullite (3Al2O3 . SiO2) and vitreous silica. This is a stable mixture which has a specific gravity of about 3.15. General Geology: Sillimanite (fibrolite) is a mineral common to the pre-Cambrian metasedi-ments of the Southeast. It occurs throughout the crystalline schists which lie between the Fall Line on the southeast and the established Paleozoic rocks on the northwest (fig. 1). In addition to the meta-sediments, this area contains pre-Cambrian igneous

Jan 1, 1951

By Robert C. Linares

Cubic zinc sulfide has been grown from molten salt solutions substantially below the hexagonal-cubic phase transition of 1020°C. Crystals free of birefringence have been grown from molten lead chloride at temperatures from 500° to 800°C. Factors affecting the optical transmission and the birefringence are discussed. CUBIC zinc sulfide is of interest for electrooptic devices and as an optical coating material. However, it cannot readily be produced as large crystals which are free of birefringence. The birefringence arises from the fact that the cubic ZnS is usually grown as the high-temperature hexagonal phase and is transformed to the lower cubic phase by annealing.&apos; This results in stacking faults, stress, and birefringence. A requirement for the growth of cubic ZnS is that it be grown below the phase transition of 1020°C.2 Crystals of cubic ZnS have been grown below 1020°C by the hydrothermal,3 flux,4 and vapor transport5 techniques. However, these all appear to have limitations in size or quality of material produced. It was felt that a new flux method might have a good chance of overcoming some of the previous problems. Mita6 reported the growth of hexagonal ZnS from molten NaCl and wilke7 reported the growth of iron sulfides from molten lead chloride solution, indicating that molten chlorides make good solvents for sulfides. An investigation of a number of possible molten chlorides as solvents showed that molten PbCl2 has an appreciable solubility for zinc sulfide and that crystals can be grown at temperatures from 500° to 800°C. EXPERIMENTAL Crystal growth was performed in open or sealed Vycor or fused silica tubes, in an argon atmosphere or vacuum. There were no deleterious effects due to using vacuum; however, a sealed essentially isothermal system must be used to prevent vapor transport mechanisms from dominating. This will be discussed later in detail. Noble metal containers were not usable as they were severely attacked by these melts. The materials used were: reagent-grade PbC12, reagent-grade ZnS, optical-coating-grade ZnS, and Irtran 2 (ZnS). Crystal growth was accomplished by both slow cooling techniques and gradient growth techniques. In the slow cooling techniques, 15 g of ZnS and 100 g of PbCl2 were used. The components were placed in the silica tube, heated at 800°C for 2 hr, and then slowly cooled (l° to 10° C per hr) to 500°C. The furnace was constructed so that the tube could be inverted, thus allowing the liquid to drain off the crystals at the end of the run. The gradient runs were made by placing the above mixtures in a silica tube at 550° to 600°c, Fig. 1. A temperature gradient was maintained such that the floating mass of undissolved sulfide was 10° to 50°C warmer than the bottom of the tube. Growth occurred on spontaneously nucleated sites at the cooler bottom. RESULTS When using high cooling rates (5° to 10°C per hr), crystals form in thin sheets perpendicular to the {111} face. Crystals 5 by 5 by 1.2 mm, Fig. 2, have been ob-

Jan 1, 1969

By Ralph E. Esarey, George V. Cohee

In Indiana, 349 wells were drilled for oil and gas in the year 1942. Of this number, 125 oil wells and 21 gas wells were successfully completed and 203 were dry holes. Drilling activity declined 37 per cent as compared with that of the year 1941. This reduction was brought about largely by Federal Conservation Order M-68, restricting drilling to one well on 40 acres, in order to save steel. This Order was later supplemented to permit closer spacing of wells drilled to sandstone formations in southwestern Indiana. Most of the drilling in 1942 was in the southwestern part of the state. Posey County ranked first, with 94 completions and 44 producers; Gibson County, second, with 77 completions and 38 producing oil wells and 2 gas wells. There were 58 drilling operations in the state at the end of the year. During 1942 a total of 589,734 ft. of hole was drilled, of which 231,702 ft. was wildcat footage. The total initial production of the oil wells completed was 9974 bbl. and of the gas wells, 11,148,000 cu. ft. (Table 2). Of the 349 wells completed, 122 were wildcat wells (Table 3); 26 were completed as oil wells; 17 were extensions to proven fields and 9 discovered new pools. Posey County was foremost in wildcat drilling, with 37 wells completed (Table 6). Thirty-five per cent of the wells drilled in 1942 were wildcat, as compared with 25.5 per cent in 1941. It is anticipated that the percentage of wildcat wells drilled in 1943 will be greater, although the total number ol ,wells drilled in the state will probably be less. The new discoveries in Indiana in I942 were, for the most part, one-well pools in the southwestern part—in Posey, Gibson and Spencer Counties (Table 4). Most of the development in pools took place in the . Hazelton and Kirksville pools in Gibson County, Mr. Vernon pool in Posey County and the Vernon Heights pool in Vander-burgh County. Deeper production was obtained from the Osage limestone in the Hazelton pool at a depth of 2402 ft., 650 ft. below the productive McClosky limestone. The well had an initial production of 140 barrels. Extensions to 17 pools in the southwestern part of the state were successfully completed (Table 5). An interesting development during 1942 was new production from the Devonian limestone in the Dodds Bridge pool, Sullivan County. The Ohio Oil Co. deepened one of its wells, which had been producing from a shallow sand, to the,Devonian, and it was completed for an initial production of 77 bbl. Five other Devonian producing wells were completed in that area. Crude-oil production in Indiana in 1942 was 6,609,000 bbl. (Table I). The Griffin field, Gibson and Posey Counties, which produced approximately 3,550,000 bbl., accounted for more than half of the state&apos;s production. The Mt, Vernon and New Harmony fields were next in importance of production, with 684,000 and 523,000 bbl., respectively. The price of crude oil was $1.22 a barrel for the old

Jan 1, 1943

By H. T. Bowman

For more than 80 years the Bessemer process has depended upon the ability, skill, and judgment of the blower, although as early as the I860&apos;s it was recognized that the process would benefit by some type of instrumental contro1.l IIowever, instruments with sufficient recording speeds did not exist, so the end-point determination was always dependent upon the blower&apos;s eye. This placed an obstacle in the way of precise experimental work, because of the absence of the necessary records and reference points as reported by Work.2 The use of the photocell provided the instantaneous record of the blow that made this experimental work possible and provided more scientific control for the process as discussed by Graham,3 A brief description of the progress of the blow will illustrate the recording function of the instrument. The silicon in the iron is being oxidized during the first minutes of the blow, as pointed out by Henning4 in a table showing the order of metalloid elimination. The product of this oxidation is a solid that remains in the converter, so there is virtually no flame during this part of the blow. This low flame luminosity is illustrated by the flame recording shown in Fig. I, where the silicon blow is plainly marked. The dull flame of the silicon blow gradually gives way to the brilliant carbon flame as the increasing quantities of carbon monoxide formed inside the converter burn to dioxide upon contact with the atmosphere above the vessel. When the carbon reaches some low value under 0.20 per cent, there is insufficient menoxide formed to maintain the dioxide flame, so its intensity drops. Throughout the flame drop carbon continues to burn, until at some value around 0.05 per cent an arrest occurs in the recorded drop. This point has been designated as the end point. The period of time from this end point until the vessel is turned upon its side and blowing has stopped has been called the afterblow. This afterblow is used as a measure of the degree of metal oxidation, and uniformity demands that it be controlled within narrow limits. Iron and blowing conditions are likely to change several times during a turn, necessitating corresponding changes in end-point control. It is the purpose of this paper to discuss these changes, the factors that make them necessary, and their bearing upon the quality of steel. Carbon-FeO Relationship In the Bessemer process oxidation relationships are precise. Fig. 2 shows a graph of the carbon-FeO relationship. The familiar "bomb-test" method, described by Mccutcheon and Rautio,5 was used for obtaining these and all other dissolved FeO values herein reported, all tests being taken from the converter before deoxidation unless otherwise noted. All tests of 0.10 per. cent carbon and above were obtained from metal blown for duplexing. McGinley and Woodworth6 reported iron oxide values for blown metal, but their tests were obtained by a . different method than were those

Jan 1, 1942

By F. W. C. Boswell, R. L. Cunningham, H. M. Weld

Chemical analysis shows the partition of the magnesium addition between the metal and the graphite is independent of whether the graphite is in the form of nodules or flakes. The bright central spot observed in nodular graphite polished sections is shown to be due to the structure of the nodules. DURING the past few years numerous papers have been published on the production1-7 and heat treatment" of nodular cast irons. However, very little information is available on the structure of the nodules and the reason for their formation. It would appear that an explanation of the phenomenon of nodulation must await a detailed knowledge of the nature of the nodule. Disagreement exists among various workers on such a fundamental point as to whether or not a nodule actually contains a microscopically visible, nongraphitic nucleus.9-11 Work was initiated with a view to obtaining definite information on this and other aspects of the problem. Chemical Separation and Analysis Microscopic appearance had indicated9-11 that a nongraphitic core might exist in nodules (Fig. 1). It appeared that a chemical comparison of separated nodules and flake graphite would be profitable, for if the core is nongraphitic a relatively large amount of certain elements would be found in the nodules as compared to the flake. This comparison could best be made by obtaining nodules and flake from the same melt of cast iron, part of which had been in-noculated with a suitable addition reagent for the formation of nodules. A 300 lb melt was produced. About half of this was innoculated in the ladle with an Fe-Si-Mg alloy to produce nodules and cast into keel blocks; the remaining half of the melt had silicon added in an effort to compensate for the silicon in the innoculant used in the other half of the melt and this was cast into similar keel blocks. The analyses of the resultant irons are given in Table I. Nodules and flake were chemically extracted from 2 kg samples of metal as described in the appendix. While this method dissolved the iron and chromium carbides, it did not dissolve the titanium, vanadium, and molybdenum carbides. These latter carbides could have been removed by nitric acid, but in other experiments it was found that it attacked pools of metallic iron entrapped in the nodules which had, until the nitric acid treatment, been protected from the attack of the sulphuric, hydrochloric, and hydrofluoric acids. It will be shown in the next section that entrapped iron exists in nodules but not in flake. On microscopic examination many tiny irregular particles were observed to accompany both the nodules and the flake. These were identified by tabling a sample of nodules from which a sufficient fraction was obtained for X-ray analysis. A good pattern of titanium carbide was obtained indicating that this was the predominant compound present. Since it was not possible to determine how completely the carbides could be removed mechanically and since their removal from flake is much more difficult, it was decided not to resort to any separation as this would render further comparisons more difficult. The samples were ashed in a combustion

Jan 1, 1953