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By H. Guyod

The response of the Guard Electrode sonde (LL3) and the Laterolog (LL7) can be mathematically computed only for cases that do not represent realistic conditions. A resistance network analogue that simulates a number of typical—although idealized—formations was used instead to obtain, for both devices, a large number of resistivity logs and current distribution maps. From these data, charts were prepared for estimating true resistivities under a number of conditions. Some of these charts and current distribution maps are presented. INTRODUCTION Two main benefits are expected from a resistivity log: (1) obtaining geological information for mapping and other purposes, and (2) obtaining petrophysical data, based on true rock resistivity. The geological information can be derived from any resistivity curve having sufficient vertical detail, but true rock resistivities frequently are difficult to determine with desired accuracy because we do not have sufficient interpretation data. This is particularly true for the records given by the Laterolog tools. The object of this paper is to throw some light on the factors affecting the responses of these tools so that better resistivity data can be obtained from Laterologs. LATEROLOGS Laterolog measuring systems are of two types: the LL3 sonde, frequently called "Guard", and the LL7 sonde. Both measure the resistance between a single exploring electrode placed in the borehole and a faraway return electrode whose influence will be assumed here to be negligible. Although the principles of these tools have already been outlined,1-3 it is desirable to review them briefly in this article. LL3 Fig. 1, left side, represents a long cylindrical, vertical current electrode placed in a medium of uniform resistivity. The current leaving the center section of the electrode flows essentially along horizontal lines, delineating a surface having the shape of a biconcave lens. It is the elec- trical resistance offered to this particular group of current lines that is measured by the Guard tool. This is done in practice by having a long cylindrical electrode consisting of three sections physically and electrically separated by thin insulating washers, as shown in the center of the figure, and keeping the three sections at the same potential. It is obvious, for all practical purposes, that the current and potential distributions about this electrode are the same, as if we had a continuous electrode of same dimensions. Because the three sections are electrically separated, the resistance seen by the center section E can be independently measured. This section will be called the exploring electrbde, or E electrode. Its height generally is from a few inches to 1 ft. The outer sections are the guards G, which are several feet long. The combined length of the three sections is from 10 to 12 ft for the tools currently used in the petroleum industry. Let V denote the potential difference between E and the faraway return electrode, and I be the current flowing between these two electrodes. The resistance (Re) seen by the exploring electrode is VII, and the corresponding apparent resistivity is Ra = k(Re),............(1) where k is the tool calibration factor. The previous description establishes that the Guard tool uses that central portion of the sonde from which, in a uniform medium, the current follows essentially horizontal paths. When the formation being logged is fairly uniform, and when its resistivity is of the same order as

Jan 1, 1965

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Jan 1, 1938

By George W. Lower, Robert B. Booth

The use of cyanides in the extraction of gold and silver is well known1 Such extractions employ concentrations of cyanide in the range of 0.02-0.25% sodium cyanide equivalent in leaching cycles of 24-48 hr and frequently longer. Copper minerals, even though minor components of precious metal ores, dissolve in these cyanide leaching solutions, consume cyanide, cause fouling of mill solutions, and thus interfere with the precipitation and recovery of gold.2,3,4 This paper presents a summary of laboratory investigations on the use of cyanide solutions as extractants for copper from various copper-bearing ore fractions. In view of the metal contents involved, it will be apparent that larger quantities of cyanide are required to extract copper than for the extraction of precious metals. In cyanide solutions of concentrations generally favorable to copper extraction, sulfide and oxide copper minerals were found to dissolve rapidly at room temperature and atmospheric pressure.

Jan 11, 1965

By C. C. CONCANNON

POTASH is an essential. It is necessary as an ingredient in fertilizers or as a plant food, and certainly one of the great problems, and one of increasing gravity, is the maintenance of agricultural fertility that we may have adequate food supplies. When one thinks of potash one thinks of Germany. The first and most important deposits of soluble potash salts were found in Germany, and it was through Ger- man research and the application of a highly developed knowledge of chemistry that the value of these deposits was recognized and appreciated in the field of agricultural fertilization. The Germans knew that they had something of great value in their potash resources, not only because of the advantage derived from the extensive use of it in their own intensive farming operations at home, but also because of the pressing need for it on the part of other countries. Appreciating the economic value of this in international trade, they fostered the industry to the fullest extent and devoted much attention to well organized propaganda designed to bring out the essential need for potash of German origin throughout the world. Thus every one came to believe that potash was an essential commodity of only German origin and as such it held an extraordinary position in world trade prior to 1914.

Jan 1, 1926

C. Edward Stafford, Chester, Pa.:—Doring all my business life, I have been engaged in the manufacture of Bessemer and open-hearth steels, but, during my long connection with the Shoenberger Steel Co. of Pittsburg, I had some experience in the manufacture of high-grade puddled iron for horseshoes, and in making, by Dr. Otto Wuth's process, extremely pure, low-phosphorus puddled blooms (analyzing from 0.005 to 0.01 per cent. of phosphorus and sulphur), which were melted with low-phosphorus pig-iron in acid open-hearth furnaces, to make extra locomotive fire-box steel. I have also seen the Danks puddlers in operation at different times and places, notably where they were most successful, at the Otis Steel Works, Cleveland, Ohio; then under the management of our friend, Mr. S. T. Wellman. These Danks blooms were made solely for open-hearth melting-stock, to which they were well adapted. (The unavoidable presence of bits of ore-fix imbedded in the mass of the metal always prevents the profitable manufacture of merchant iron from Danks' blooms.) With the experience just described, I was to some degree in position to value fairly the means, methods and results of Mr. Roe's mechanical puddling from the metallurgical or technical and economic points of view, when given an opportunity by Mr. Roe to see his puddling-furnace or machine in operation in Pottstown, Pa. Briefly, the furnace, with water-cooled bottom, is rectangular in plan, about 20 by 8 ft. in the clear, suspended by trunnions at the middle of the long sides, at a height of 17 or 18 ft. above the general level. The oscillation (65" each way from the vertical) is accomplished by geared segments (attached to the downward-projecting side or trunnion-plates) with which engage pinions driven by a reversing engine. The whole section

Jan 1, 1906

By K. Sassa, I. Ito

The dynamic principal stresses induced within rock by an explosion under con fined conditions are analyzed for the case of blasting with one free face by applying the values of measured radial displacement, particle velocity and so on to equations derived from the theory of elasticity. The dynamic stresses on the free face are also calculated from the strain measured by wire strain gauges affixed on the free face. Some results obtained are briefly: 1) The maximum stress on the free face appeared at the intersection between the free face and the burden, and its magnitude was about twice as large as the magnitude of the tangential tensile stress imparted by the incident stress wave within the range related to the breakage by blasting. 2) The maximum value of the compressive stress near the free face was decreased due to the existence of the free face, while that of the tensile stress was increased. 3) At any point near the free face, the directions of the principal stresses in the r? plane using spherical coordinates with the origin at the center of the spherical charge, changed with time except in the direction of the burden. However, at another point near the explosion point where the principal stresses were mainly those stresses caused by the initial longitudinal wave, the directions of the principal stresses coincided with those of the coordinate used. 4) The maximum value of the tensile stress in the F direction was larger than those in the re plane at and near the free face. 5) The tensile stress caused by the Hopkinson effect appeared only near the burden. 6) It is presumed from the results of stress analysis that radial cracks will be produced in the rock mass near an explosion point, but with the approach of the free face, the directions of cracks curve towards a direction parallel to the free face. INTRODUCTION In order to investigate the mechanism of rock breakage by blasting, it is considered to be very im- portant to know how the stresses are generated and distributed within the rock by explosion of a confined charge. As part of a research program concerning the mechanism of rock breakage by blasting, the authors have already published papers on the detonation pressure produced at the inner surface of the charge hole1 and on the behavior of the dynamic stresses within rock caused by an explosion in the case where no free face existed.' In this study the dynamic stresses on and near the free face have been investigated for the case of blasting with one free face. The mechanism of rock breakage in blasting is discussed in the light of these studies.

Jan 1, 1967

Joseph K. Stone, Jr. (Kaiser Engineers, Oakland, Calif.)—I would like to compliment the authors on their clear presentation of the results of their study of the pneumatic processes. We hope that the Inland Management decision to make this information available to all will induce others to release additional valuable fundamental data which they have accumulated in the field. There are two points upon which we would like to comment. In the discussion of Table VII it was indicated that the "oxygen consumptions were about the same as has been reported for other oxygen steelmaking processes". This conclusion is apparently based upon the consumption of 2100 cu ft per ton shown in Table VII. The data in Table IV also permits calculation of 2520, 2280, 2250 and 2700 cu ft per ton in heats 1 to 4, respectively. These figures are in the same general range as those reported for the Kal-Do and Rotor Processes using Thomas iron, but considerably above the following figures for four of the operating L-D Process Plants while using iron which is similar to American basic iron: Donawitz 1760 cu ft per ton Adapted from Cuscoleca' LinZ 1900 cu ft per ton Trenkler & Hauttmann2 Dofasco 1850 cu ft per ton D. O. Davis:3 In addition to the differences between the consumption of gaseous oxygen in the Inland operation and in the L-D Process, there is another closely related difference. The L-D plants for which data are cited are using approximately 1 pct ore while the authors' process used about 7 pct of sinter. Assuming 65 pct Fe in the sinter, the difference amounts to 400 to 500 cu ft

Jan 1, 1959

By C. W. MacGregor

IN the testing of materials there exist various methods of recording graphically the behavior of a material subjected to tensile stress. Prob-ably the most common method is to plot the tensile stress So, obtained by dividing the load P by the original area of cross section AO at the start of the test, as a function of the strain ?o, which is obtained by dividing the ?Lo or the change in the gauge length by the original gauge length Lo. A list of the symbols used here is given in Table 1. This method, while it has proved useful in the routine testing and comparison of various materials, does not have a very sound physical basis, as was first pointed out by P. Ludwik1, and consequently does not afford a very deep insight into the true physical behavior of the material under stress. Among the objections to this method may be mentioned: (1) that by dividing the load P at any stage of the test by the original area Ao a fictitious stress is obtained, which does not actually exist; (2) that the strain ?o = ?Lo /Lo is not an exact expression for the true strain for large values of ?Lo in per cent of Lo; (3) that when necking starts the strain varies considerably along the gauge length and the above expression no longer gives the true strain existing at any point on the outside of the bar; and (4) that the axial strain varies over the cross section of the necked portion and ?o does not represent an average of these strains over the cross section. Stresses taken from such a diagram would be only approximate and, if used to compare results of a test on a given material under simple tension with results obtained under combined stresses, certain errors would he thus introduced. In order to overcome some of these objections, various methods have been suggested, both as to the quantities to be measured and as to their graphical representation. In some cases the so-called "true stress," obtained by dividing the load P by the actual area of cross section A existing when the load P was applied, is plotted as a function of the strain

Jan 1, 1937

By T. Carl Shelton

The coal industry of the United States in 1967 had reasons to be both exuberant and concerned about its present and future role in the economy of the country. Continuing a momentum that began in the early 1960's, the industry has moved ahead in providing competitive customized products to strengthen its long-term domestic and foreign commitments, and has maintained with steady progress its position as a major supplier of energy. On the other hand, the industry must overcome air- water pollution and conservation-reclamation problems that have been identified by 1967 legislation. Throughout the year, the industry was characterized as "progressive," "healthy" and "dynamic." To have been termed a "growth industry" in 1967, is an accolade the coal industry can accept with pride. Culminating its efforts throughout the decade, the industry has emerged with a competitive image that is representative of its future strength.

Jan 2, 1968

By G. W. Sheary

At Bethlehem's Grace mine's 6000-tpd pelletizing plant a cascade control system is utilized to approach a constant magnetite filter cake moisture, a critical factor in obtaining quality green pellets. Variables being controlled by instrumentation are filter feed solids, filter tub level, first and second stage pump sump levels and thickener sludge level, all at varying feed rates. Startup difficulties, modifications and contemplated additions to obtain closer control of the moisture are discussed. Situated 45 miles west of Philadelphia and 50 miles southwest of Bethlehem Steel Co. 's Beth-lehem plant, the integrated Grace mine facilities produce 4000 tpd of high-quality iron ore pellets. Startup of the Grace mill was in November 1958, and iron concentrates were shipped until March 1960, when the pellet plant went into operation. The underground mine, when fully developed, will hoist about 9000 tpd, including development rock. The crude ore, which has an iron content of approximately 42%, is magnetically cobbed and crushed in closed circuit with %-in. slotted vibrating screens. The ore is washed and screened in the mill and the 1/4-in. screen product is again cobbed prior to feeding to the rod mills. Grinding is done in rod mills, and in ball mills that are in closed circuit with 30-in. cyclones, to 1% on 100 mesh and 65% -325 mesh. The ground ore is magnetically concentrated by three-drum permanent-type finisher magnets to 67% Fe. The magnetite concentrate is pumped from the mill to a 50-ft thickener in the pellet plant. The thickened magnetite concentrate is relayed to the filters through a two-stage pump arrangement. The filter cake is fed by belt from filter concentrate bins to mixer-muller belts where it is intimately mixed with bentonite and a slight amount of water for moisture control. The fluffed concentrate then drops into balling cones. The green pellets from the balling cones are fed in a prescribed feed pattern to shaft furnaces through the use of shuttle car mechanisms. The green pellets are dried, heated to 2500°F and cooled to 1200°F as they descend through the furnace and into pellet coolers where the pellets are further reduced in temperature to 250°F. Heat is recovered in the cooling process through the use of air-to-air heat exchangers. The cooled pellets discharge on a rubber conveyor belt and are transferred to 6000-ton pellet railroad loading bin. The final pellet product consists of 90% +'1/4 in. material (after tumble testing1) and contains 66% Fe plus 3% silica. It has been the usual practice to maintain constant filter tank level by pumping an excess constant volume and using a moveable fishtail splitter to divert the desired amount of slurry to the filter tank. The excess from the fishtail and from the filter overflow pipe, which maintains a constant level, is returned to the source. At the Grace mill, tremolite builds up in the pipelines when pumping heavy magnetite concentrate slurries, making it necessary to use polyvinyl

Jan 1, 1962

By B. M. Loring, I. R. Kramer, F. M. Walters

No observations on the mechanical properties of iron-manganese alloys have been published since pure manganese became readily available, either distilled manganese or electrolytic manganese. The purpose of this investigation was to determine whether iron-manganese alloys are essentially brittle, as reported by Hadfield,1 or whether the lack of ductility observed was due to impurities in the alloys that he studied. EXPERIMENTAL METHODS The alloys were melted in a 100-lb. high-frequency induction furnace with a magnesia crucible, using ingot iron and electrolytic manganese. The heats were split, the first giving six 18-lb. ingots and the second three. Each successive heat was higher in manganese and about 0.3 per cent silicon [ ] was added as ferrosilicon. The alloys forged without difficulty-and were given a 90 percent reduction to 3/4-in. rounds. The chemical analysis of the alloys is given in Table I. The forged rods were homogenized for [ ] 24 hr. at 1150°C. (2100°F.) and air-cooled. The alloys were tested in two conditions of heat-treatment: (I) as normalized from 870°C. (1600°F.) and (2) normalized from 870°C. and tempered for z hr. at 540°C. (1000°F.) and air-cooled. The tensile specimens were 0.505 in. in diameter with a 2-in. gauge length, and the impact specimens were V-notch Charpy. The proportional limit and yield strength were taken from the stress-strain diagrams drawn by a Peters recorder. The data obtained from the tensile test and the hardness measurements are given in Table 2. Specimens that were normalized are designated by N; those that were normalized and tempered by T. Alloy G was tempered after forging (D).

Jan 1, 1941

By S. J. Rothman, L. T. Lloyd

S. J. Rothman and L. T. Lloyd (Argonne National Laboratory)— Hagel's paperz0 discusses the question of the mechanism for self-diffusion in bcc transition metals. Recent work21"23 has led us to agree with him in reabandoning the ring mechanism in favor of a defect mechanism, most likely vacancies. On the other hand, we think that Hagel's attempt to group together all self-diffusion in bcc transition metals is wrong. We prefer the scheme of Peart, Graham, and omlin," who separate them into two groups. One group contains the anomalously behaved metals P titanium,', y uranium, and perhaps zirconim.' The other group contains a iron," this alloy was held at 1800°C for 2 hr before quenching, its structure was all a. B. C. Giessen, I. Rump, and N. J. Grant (Authors' reply)—We very much appreciate the discussion by Deardorff and Kato regarding the a to /3 transformation temperature of hafnium. In the W-Hf program, as well as in a current study of the system Cr-Hf, standard precautions were exercised against contamination, including vacua of less than 10"5 mm Hg and a weight control check of all specimens to insure an impurity rise of less than 100 ppm. Following receipt of the above discussion, a revision was made in the annealing process. Arc-cast specimens were etched with a 10 pct HF-90 pct HNO solution until 1 mm of surface, including a possible oxide film, was removed. Annealing was done in a hafnium container which provided a long diffusion path for gaseous contaminants. Finally, the heat treating time was shortened. Structural changes were noted to occur quite slowly. A 99.5 at. pct Hf alloy showed 70 pct /3 after 30 min at 1700°C and was 100 pct /3 after 10 min at 1715°C. After 24 hr at 1740C, the alloy was found to be 10 pct/3. This change is due to contamination; it was estimated that it corresponds to an increase of 60°C in the transformation temperature over a 24 hr period. The corresponding change in 30 rnin would be slight. Using the same hafnium as in the above publication, and three new alloys at 98, 99, and 99.5 at. pct Hf, the transformation temperature was indicated to be 1715" 15°C. Since this hafnium contained 4.4 at. pct Zr, a correction of 40 5C, based on an assumed approximately linear transformation temperature curve, must be made for pure hafnium. This yields a value of 1755 20°C in good agreement with Deardorff and Kato's value. Because the slope of the boundary is small, this permits a good extrapolation, and we regard the W-Hf alloys as well suited to check the Hf transformation temperature. niobirn,'' and molybdenum,22 whose activation energies correlate with the melting temperature and whose Do values follow Zener's predictions.28 We have no quarrel with Hagel's placing chromium into the second group; we disagree with his interpreting our data to make uranium fit into that group. Hagel considers that the measurements of self-diffusion in uranium below about 950°C represent combined volume and grain boundary diffusion. This contention is based on the curvature of the penetration plot for our 891°C run,4 which also has a nearly straight line plot of log c vs x. Hagel has extrapolated these characteristics to our 803.5C run and fitted his Arrhenius plot for self-diffusion in y uranium to our four highest temperature points only. We think this is wrong for the following reasons.

Jan 1, 1963

By L. C. Brown, E. B. Hawbolt

The formation of grain boundary precipitates has been studied in Ag-5.64 wt pcl Al alloys at 688°C. Large-grain specinzerzs were used and the boundary misorientation measured by X-ray diffraction. At low-angle grain boundrrries Primary sideplates form. u)hile abore a 17-deg misorientation lenticular precipitates predominate. Growth of the lenticular precipitates was studied on individual grain boundaries using a statistical technique. The thickening and lengthening rates appeared to be independent of &apos;pain boundary misorientation, indicating that grain boundary diffusion was not significant in this system. The precipitates grew urith constant shape, with both the length and thickness increasing parabolically with time. The parabolic lengthening rates were unexpected since previous theory and experimerztal results had indicated linear growth. By approximating the shape of the precipitate to that of an oblate spheroid grouling with constant shape an equivalent diffusion coefficienl was calculated. The zlalue obtained was in good agreement with nleasurements obtained fron, diffusiorz couples. IF a single-phase alloy is heated or cooled to a temperature such that the phase becomes supersaturated, there is a tendency for a second phase to precipitate from it in order to remove the supersaturation. Precipitation takes place initially on grain boundaries due to preferred heterogeneous nucleation, but subsequently Widmans kitten plates may form in the grain interiors if the grain size and supersaturation are sufficient. The type of grain boundary precipitate formed depends on the nature of the boundary. Aaronson1 and clark2 have shown that grain boundary misorientation can be characterized by the simple parameter R, where and X, Y, and Z represent the minimum rotations about three orthogonal axes required to bring the two lattices forming the grain boundary into coincidence. The maximum value for R is 60 deg. In using this parameter the orientation of the grain boundary itself is, of course, neglected. However it was found in both Fe-si3 and A1-Ag2 that the precipitate shape depended only on the parameter R. Clark found that the vast majority of precipitates formed were allo-triomorphs— lens-shaped precipitates that grew along the grain boundaries. At low-angle boundaries, however, (R < 15 deg) Widmanstatten sideplates nucleated at the grain boundaries and grew into the adjacent grains. It has been reported that the rate of growth of grain boundary precipitates is controlled by diffusion within the supersaturated phase.&apos; The theories which have been developed for growth rates have assumed the diffusion coefficient constant over the composition range of the supersaturated phase. This is a fairly good approximation if the composition range involved is not large. Thickening rates have been calculated using the theory developed by Zener4 and by Frank5 for the growth of planar precipitates. A parabolic growth law

Jan 1, 1968

By F. J. Smit

The Tintic Division of Kennecott Copper Corporation operates the Burgin Mine in the East Tintic District near Eureka, Utah, approximately 75 miles south of Salt Lake City. The Division was organized in 1963 to develop concealed replacement orebodies in the area located by Bear Creek Mining Company, Kennecott&apos;s domestic exploration subsidiary. Several accounts of the discovery of these orebodies and the general geology of the area have been given (1, 2). The ore is very complex and of varying degrees of oxidation and alteration. The principal metal values are lead, zinc, silver, and cadmium. The Burgin No. 2 shaft was sunk in 1963 to provide access for mining the orebodies. Much of the ore mined after this shaft was sunk was high grade and shipped directly to smelters, but concurrently it was recognized that concentration would be required to upgrade the lower grade ore in the deposits. Accordingly, in January 1967, authorization was received to construct a 500 tpd concentrator. From the beginning it was expected that the characteristics of the mill feed would vary widely and unpredictably as mining progressed. This paper summarizes the characteristics of the ore, the test work upon which the plant design was based, the engineering and construction, and the present operation of the facility eighteen months after startup. ORE CHARACTERISTICS The Burgin ore is a complex assemblage of minerals from replacement of limestone. The replacement and alteration occurred in at

Jan 1, 1970

By F. W. Willard

VIEWING with alarm is a preoccupation not exclusively the habit of the political spellbinder. In good faith many of our mineral technologists have been and are genuinely alarmed over the prodigal consumption of our mineral reserves. Most competent observers are cautiously pessimistic. There are sound technical reasons for such caution. It is the purpose of this paper to discuss some of those reasons without benefit of a gift of prophecy. Perhaps the outstanding reason for caution is ignorance of accessible but undiscovered mineral reserves. The petroleum technologists have an edge on their metallurgical brothers for they have better tools for exploration. This is not to say that the mining geologist has to depend on hunches or the divining rod. The outstanding work on orogenesis by Lindgren and others has provided the mining geologist with some sound scientific knowledge as to where accessible metallic minerals are most likely to be found, As Clinton H. Crane has recently observed, most of the accessible areas of the earth have been combed for easily identified outcrops, and those have been or are being actively exploited. To find ore bodies hidden below the surface is still a costly speculation.

Jan 1, 1946

THE SECRETARY The year 1917 has been a notable one in Institute affairs. The usual activities, including meetings, publications, local section interests, library service, and so-forth, have been continued on at least the same scale as previously, and in addition the resources of the Institute have been placed without stint at the service of the Nation, not only for the active prosecution of the military side of the war, but even more especially in the industrial operations which form the very basis of modern warfare. The officers and directors of the Institute have labored both officially and individually, while the Institute as a body, through committees of, prominent members, and through many individual members, has given freely. Finally, Institute funds have been appropriated to an amount exceeding $5000 to accomplish the cooperation with Government bureaus, and provide committee expenses necessary for performing the services that have been given. The President of the Institute had a very large personal share in many of these activities, which will be described in the following pages, as well as in the President&apos;s own report. Many of the Institute&apos;s members are giving their whole time for. $1 a year, or less, and especial mention should be made of Herbert C. Hoover, Food Administrator, W. L. Honnold, Head of the Commission for Relief in Belgium, Mark L. Requa, Petroleum Administrator, Edgar Rickard and Charles W. Merrill of the Food Administration, S. A. Taylor of the Fuel Administration, W. L. Saunders, B. B. Thayer and Joseph W. Richards who .are giving a. large share of their time to the Naval Consulting Board, W. Y. Westervelt, W.0. Hotchkiss and Harvey S. Mud of the War Minerals Committee, David W. Brunton of the War Committee of Technical Societies, and hundreds of others whose names are mentioned in the Honor Roll of Members. It has also been a notable year in cooperation with sister-societies. The most important event under this head was the accession of the American Society of Civil Engineers into the fraternity of Founder Societies.

Jan 2, 1918

By R. F. Mehl, R. W. Parcel

THE rate of the decomposition of austenite in eutectoid steels, forming only pearlite, may be expressed fundamentally in terms of the rate of nucleation and the rate of growth of pearlite nodules. This matter has received much attention in recent years. (The basic references are listed in ref. 1; references of particular import to the present work will be given separately.) Systematic data have been developed for plain carbon eutectoid steels.:! Although the physical factors affecting the rate of nucleation, N, in case of plain carbon steels have presumably been identified, they cannot as yet be evaluated quantitatively.&apos; Several somewhat successful attempts, however, have been made to calculate the rate of growth, G. In the latter case the important factors determining the edgewise growth of pearlite have been assumed to be: 1—the interlamellar spacing; 2—the concentration extremes and concentration contours of carbon in austenite in front of the growing pearlite interface; and 3—the rate of diffusion of carbon in austenite.* The only systematic data on N and G for pearlite in alloy eutectoid steels are those for Co-steels;6 there are no data on alloy eutectoid steels in which the alloying element is known to decrease the rate of formation of pearlite, apart from a few scattering data reported earlier&apos; for steels containing manganese. This paper reports a systematic study of N and G for eutectoid alloy steels containing molybdenum and nickel, respectively. In order to provide information of help in understanding the results, new data are presented on the effect of molybdenum on the interlamellar spacing of pearlite, So; data on the effect of nickel on So have already been published.&apos; The alloys used were in five groups: 1—Pure Fe-C-Mo alloys (Table I) were supplied by the Climax Molybdenum Company of Michigan, Detroit. They were made from Armco ingot iron of standard analysis, Acheson graphite, and ferro-molybdenum, melted in silica-lined crucibles in a high frequency induction furnace. The ferromolyb-denum was added to the melted steel, followed in 5 min by 0.08 pct Al. The ingot as-cast measured 23/4x 31/4x10 in.; it was hot-forged at 1150°C to a bar 1 in. sq.

Jan 1, 1953

By Martin Coryell

EHRENBERG was the first to publish and direct attention to the peculiarities of the diatomaceous deposit of Richmond; but how and by whom he was supplied with the material for his microscopical investigations, is not generally known; but we may presume W. B. Rogers, formerly State Geologist of Virginia, furnished the material, and may have given the geological position or horizon. O£ these facts we have no available evidence, nor have we any estimate of the thickness of this stratum of diatomaceous or infusorial earth. At the request of a member of this Institute, I have investigated the subject, and offer the following facts as the result, derived principally from information supplied by Mr. John Ott, of the Southern Fertilizing Company, Dr. William Taylor, State Chemist, C. Peticolas, microscopist, Captain Robert H. Temple, civil engineer, Major C. M. Bolton and Mr. C. M. Smith, civil engineers, and formerly engaged in constructing the tunnel under Church Hill, in Richmond. The city of Richmond is generally described as being built on seven hills. This is not the fact, geologically speaking. Originally, there was an immense plateau of land, about two hundred feet above tide, in which a deep excavation was made from the west to east by the James River cutting down to the granite. Opening southward and meeting the valley of the James are various ravines and gullies, in the principal of which are Shockoe and Gillies Creeks. The formation is tertiary, subdivided into all the classified divisions, but at the present moment no one has been found to make this section a special study. Rogers&apos;s early classifications and diagrams, with all their imperfections, are the only published records, and the printed editions are long since exhausted. The city of Richmond is really situated in these ravines of the James, Shockoe, Gillies, and their connections. The profile marked A, Plate V, represents the section of the plateau

Jan 1, 1876

By Martin Coryell

Ehrenberg was the first to publish and direct attention to the peculiarities of the diatomaceous deposit of Richmond; but how and by whom he was supplied with the material for his microscopical investigations, is not generally known; but we may presume W. B. Rogers, formerly State Geologist of Virginia, furnished the material, and may have given the geological position or horizon. OF these facts we have no available evidence, nor have we any estimate of the thickness of this stratum of diatomaceous or infusorial earth. At the request of a member of this Institute, I have investigated the subject, and offer the following facts as the result, derived principally from information supplied by Mr. John Ott, of the Southern Fertilizing Company, Dr. William Taylor, State Chemist, C. Peticolas, microscopist, Captain Robert H. Temple, civil engineer, Major C. M. Bolton and Mr. C. M. Smith, civil engineers, and formerly engaged in constructing the tunnel under Church Hill, in Richmond. The city of Richmond is generally described as being built on seven hills. This is not the fact, geologically speaking. Originally, there was an immense plateau of land, about two hundred feet above tide, in which a deep excavation was made from the west to east by the James River cutting down to the granite. Opening southward and meeting the valley of the James are various ravines and gullies, in the principal of which are Shockoe and Gillies Creeks. The formation is tertiary, subdivided into all the classified divisions, but at the present moment no one has been found to make this section a special study. Rogers&apos;s early classifications and diagrams, with all their imperfections, are the only published records, and the printed editions are long since exhausted. The city of Richmond is really situated in these ravines of the James, Shockoe, Gillies, and their connections. The profile marked A, Plate V, represents the section of the plateau

By C. F. Riisness, E. R. Parker

THAT grain size has a great effect on the mechanical properties of metals has been recognized for a long time. Bassett and Davis1 in 1919 did excellent work in [ ] determining the effect of grain size on the hardness of brass. About the same time Jeffries2 and Sykes3 ascertained the effect of grain size on the strength and ductility of several metals at temperatures ranging from 80°K. to their melting points. When creep was recognized as an important property of metals, those engaged in the study of this property tried to determine the effect of grain size 4-9 on creep rates. Unfortunately, most of the investigations were conducted on only two grain sizes, often designated simply as "fine" and "coarse." It is well known that at high temperatures coarse-grained test bars creep less than fine-grained bars. The relation between grain size and size of test bar, [ ] however, has been frequently overlooked. In his early work, Jeffries2 showed that the number of grains in the cross section has a more important influence on the properties of the material than the actual grain size. More recently Hanson and Sandford10 and Pell-Walpole,11 in their measurements of the creep and tensile properties of tin, tested a wide range of grain sizes and correlated the grain size with the strength. Hanson9 later established the relation between the number of grains in the cross section and the. creep rate: At high temperatures, generally a coarse-grained structure is considered superior in creep to a fine-grained structure, but it is evident that for a given bar size continuously increasing the grain size will

Jan 1, 1944