Search Documents

By Sylvain J. Pirson

The number of seismograph field crews employed in the active survey of potential oil territories is still on the increase, owing to the ever pending threat of a shortage in the supply of crude oil. It is to be expected that for years to come the seismograph will be responsible for discovering many new oil fields, both in wildcat territories and in deeper formations, and that the seismographic campaign will go on unabated. Yet improvements in instrumental design, in the field and interpretative techniques, are brought about year after year, and lead to the reshooting of areas many times surveyed previously. Notwithstanding the experience gained by the past eight years of active work in reflection seismographic surveys, the results given by this method of mapping deep formations have in many instances been at variance with the information subsequently obtained by the drill. To overcome this shortcoming, geophysicists have used closer spacing of the shot points and closer control of the depth points. The method discussed here is being used actively in the Mid-Continent region and endeavors to reduce the interpretation work to a mere mechanical technique, leaving as little as possible to the opinion of the interpreter. The New Method Field Technique.—In sectionized territory where country roads are available every mile, shot points are preferably located every 1/4 mile when six detectors are available or every % mile when eight detectors are at hand. The disposition of individual spreads is represented on Fig. I; in each case a shot point is located at the section corners. Fig. 2a represents the layout of a spread between shot points, the vibration detectors being preferably equidistantly located. Normally in the 1/4-mile control, the distance between shot points is 1320 ft. and the distance between detectors 220 ft. When shooting from shot point S.P. I, detectors 1 to 6 are connected to the recording galvanometers and detector 0 (which indicates the vertical travel time of the wave corre-

Jan 1, 1940

By Sylvain J. Pirson

The number of seismograph field crews employed in the active survey of potential oil territories is still on the increase, owing to the ever pending threat of a shortage in the supply of crude oil. It is to be expected that for years to come the seismograph will be responsible for discovering many new oil fields, both in wildcat territories and in deeper formations, and that the seismographic campaign will go on unabated. Yet improvements in instrumental design, in the field and interpretative techniques, are brought about year after year, and lead to the reshooting of areas many times surveyed previously. Notwithstanding the experience gained by the past eight years of active work in reflection seismographic surveys, the results given by this method of mapping deep formations have in many instances been at variance with the information subsequently obtained by the drill. To overcome this shortcoming, geophysicists have used closer spacing of the shot points and closer control of the depth points. The method discussed here is being used actively in the Mid-Continent region and endeavors to reduce the interpretation work to a mere mechanical technique, leaving as little as possible to the opinion of the interpreter. The New Method Field Technique.—In sectionized territory where country roads are available every mile, shot points are preferably located every 1/4 mile when six detectors are available or every % mile when eight detectors are at hand. The disposition of individual spreads is represented on Fig. I; in each case a shot point is located at the section corners. Fig. 2a represents the layout of a spread between shot points, the vibration detectors being preferably equidistantly located. Normally in the 1/4-mile control, the distance between shot points is 1320 ft. and the distance between detectors 220 ft. When shooting from shot point S.P. I, detectors 1 to 6 are connected to the recording galvanometers and detector 0 (which indicates the vertical travel time of the wave corre-

Jan 1, 1940

By D. M. Thayer, P. B. Linkson

High intensity wet magnetic separation methods have received much attention in the search for alternative and effective methods to treat weakly magnetic minerals. This paper examines the incorporation of such techniques in the beneficiation of a non-sliming specular Michigan Hematite. The dependence of separation efficiency and beneficiation of specular hematite on various parameters controlling the operation of such a device is investigated experimentally. Particular attention is focused on particle size limitations imposed in these separations. In light of these data, metallurgical balances are presented and an attempt made to rationalize the various models suggested in the literature.

Jan 1, 1982

ON presenting the medalist, J.. V. W. Reynders said, in part: "Far the greatest progress in the art of steel-nuking has occurred in the production of lighter forms such as tool steels and steels entering into the moving parts of machinery generally, and particularly into the con-struction of automobiles and airplanes. In this highly specialized field in which the study of alloys and heat treatment has brought about such fundamental changes of design and practice, Dr. Mathews has achieved a ranking position. "As the technical head of the largest producer of special steels, his laboratory conclusions are frequently but a few steps removed from practical exploitation. The experimental determinations of yesterday must be sufficiently conclusive to form the basis for the specific plans of today, and to warrant commercial production tomorrow. His is not the complacent atmosphere of theoretical speculation, but one in which practice fol-lows close upon the heels of scientific research.

Jan 3, 1928

By R. Pakalnis, J. P. Savely, R. D. Call

A simple and inexpensive clay imprint core orienting device has been developed by Dr. R. D. Call. It has a minimum of moving parts, is durable and easily used by drillers, and adds only 15 minutes to a core run. Conventional wire-line drilling and a drill hole inclined 30° to 60° from the horizontal plane are required. The device will not operate in a vertical hole. The orientor is an eccentrically weighted downhole device which can be constructed in a mine shop from an old inner core barrel and lead. Modeling clay is packed in the core lifter case, which is screwed on the downhole end of the orientor. A clay imprint of the bottom of the hole is taken after each coring run. This imprint is matched to the top of the succeeding core run, the drill core is pieced together, and a reference line representing the drill hole is scribed on each core. Fracture attitudes are measured relative to the reference line and the core axis. On recent drilling projects, tests for imprint reproducibility were conducted. The results of these tests show an average variation of f3" in location of the scribed reference line between imprints. Comparisons of surface mapping data with oriented core data are good. It is rare that the entire length of drill core in intensely fractured zones can be oriented because it is impossible to piece the core together. However, if a triple tube set-up is used, a modification in the scribing procedure can result in a good statistical sampling of the fracture population. Attitudes of major structures have been oriented with this technique.

Jan 1, 1983

By S. F. Emmons

" The obscurity which still veils from us the true nature of veins will become more and more cleared up when they can be considered in connection with the geological structure of the regions in which they occur."* These words, according to Lossen, the biographer of the late Dr. A. von Groddeck, of Clausthal, were the last received by him from that eminent man, perhaps the most far-sighted and carefully progressive of recent writers on ore-deposits. They seem to me to form a fitting text for what I am about to say; since I find that many of the conclusions at which I have arrived by my own study of the structural relations of ore-deposits, or, in other words, of the structural and dynamic geology of the regions in which they occur in this country, have been similarly determined by him within recent years in Europe, and especially in his home field of work, the Hartz. I shall not enter upon a detailed account of how far other workers may have arrived at similar conclusions with myself, since these questions of priority are of little interest, except to those immediately concerned; but will briefly present the methods by which, in my work in this country, I have arrived at certain generalizations, and will point out the practical bearing which they may have upon the work of mining engineers. In my first thorough and systematic examination of an important group of ore-deposits, viz., that of Leadville, Colorado, I was enabled, through the generous facilities afforded me by the then Director of the Geological Survey, Mr. Clarence King, to make a most elaborate and detailed study of the geology, not only of the immediate vicinity of the mines, but of the adjacent mountain regions, based upon accurate topographical and underground maps, and

Jan 1, 1888

By Earl Oliver

Dean Roscoe Pound, of Harvard Law School, in addressing the A.I.M.E. Petroleum Division on Feb. 22, 1934, said, "When you are able to work out a program that is mechanically feasible, that is economicaIly advisable, and which seems in your judgment, which is just as good as that of anyone, to be politically wise, you will not have very much trouble in the end in inducing the courts of today to find that it is legally sound." The purpose of this paper is to show: first, legal conditions necessary to promote conservation and stabilization; and second, to suggest operating procedure when those legal conditions are established. The proposal is mechanically feasible and economically advisable. A growing public understanding should make it politically wise. The disappointing progress in the development of conservation and stabilization can be attributed to the lack of two legal concepts as integral parts of oil and gas law; i.e., (1) a practical substitute for the capture rule, (2) collective ownership control for the individual oil and gas pool. When these two concepts are established on an equitable basis, conservation and stabilization procedure will become a comparatively simple process, more or less automatic in its adaptation and operation. Establishing these concepts is the function of the law-making agencies and might well be left to them for discussion except that the mechanical processes that give them form and substance must first be developed by the engineer. A Substitute for the Capture Rule Much has been written on these subjects, but the most concrete statement that has come to the attention of this writer is the following from an article by Charles G. Haglund in the Kentucky Law Journal of May, 1934: The Oxford1 case is not only authority for the proposition that it is competent for the legislature to modify the old property law of capture with respect to oil and gas but that it may also delegate such authority to a subordinate body.

Jan 1, 1935

By J. A. Solomon, H. E. Shafer

As a result of the great demand for metallic aluminum and the scarcity of domestic bauxite, numerous processes have been proposed and developed to extract the oxide of this metal (Al2o3) from clays, shales, and other low-grade raw materials.1-4 An exploratory study was made to extract alumina with sulfuric acid from relatively impure coal-associated draw-slate and to establish an optimum calcination temperature for maximum recovery. Draw-slate is the term used to describe the hard, slaty material directly overlying many coal seams and may range from a few inches to a few feet in thickness. Alumina content of these draw-slates may range from as low as 15% to over 35%. Although the following results are limited in scope, some of the data should prove beneficial for further work. Coal-associated clay, shale, and gob heretofore have been considered nuisance products; any successful alumina extraction process would greatly enhance the worth of these almost limitless resources. This research demonstrated that an optimum calcination temperature for alumina extraction could be established for a coal-associated draw-slate and that this temperature was lower than those suggested in previous work with unspecified clay types. It should be noted that slightly higher acid concentrations and somewhat finer particle sizes were used in this series of tests as compared to previous work. EXPERIMENTAL WORK Essentially, alumina extraction proceeded in four steps: 1) grinding, 2) calcining, 3) acid leaching, and 4) precipitating of aluminum sulfate. An initial series of reference tests to determine the optimum temperature of solubility for alumina was run using relatively pure kaolin. Kaolin forming clays are hydrous aluminum silicates of the approximate composition 2H2O A12O3 2SiO and kaolinite is the mineral that predominates in most kaolins. 5 The kaolin was ground to -30 mesh and subsequently calcined at temperatures ranging from 100°C to 700°C. Each sample was calcined for 1 hr in a muffle furnace and in turn subjected to sulfuric-acid leaching (H2SO4, 9 molar) for a 2-hr period. The filtrates were analyzed for the amount of dissolved alumina recovered.637 Also, each sample of leached or barren residue was

Jan 1, 1968

By R. S. Schechter, T. R. Guilinger, P. Bobeck, J. G. Price, L. W. Lake

This paper presents the results of an experimental study on the rate of uranium and molybdenum extraction from a flow reactor. Specific variables tested are fluid throughput and flow rate, lixiviant cation, and injected pH and carbonate concentration. The ore tested was from the Felder mine in southern Texas. It contained substantial quantities of marcasite and molybdenum disulfide that competed with the uranium ore for oxidant. Flow studies showed the oxidation of molybdenum disulfide under field conditions is mass transfer controlled, whereas the uranium oxidation is limited by surface reaction rate. The rate of uranium oxidation decreased with decreasing pH. The total carbonate levels, on the other hand, were unimportant. Ammonium carbonate appears to greatly decrease, if not completely halt, the reaction of marcasite with the oxygen. This effect was not found using either sodium or potassium carbonate.

Jan 1, 1986

By D. C. Hilty

It has long been known that in melting high-chromium steels, some of the carbon might be oxidized out of the melt without excessive simultaneous oxidation of chromium, and that higher temperatures favor retention of chromium. The advent of oxygen injection as a tool for rapid decarburization of a steel bath permits significantly higher bath temperatures, and it was quickly recognized that the use of oxygen injection facilitated the oxidation of carbon to low levels in the presence of relatively high residual chromium contents. Up to the present time, however, specific data pertaining to the chro-mium-carbon-temperature relations in chromium steel refining have not been available. Individual steelmakers have evolved practices more or less empirically, but there has been very little real basis for predicting how effective any given practice can be in permitting maximum oxidation of carbon with minimum loss of chromium. The current investigation, therefore, was undertaken in an effort to establish the fundamental carbon-chromium relationship in molten iron under oxidizing conditions. As reported below, the equilibrium constant and the influence of temperature on that constant have been derived for the iron-chromium-carbon-oxygen reaction in the range of chromium steel compositions with what appears to be a fair degree of precision. The practical application of the result will be obvious. Experimental Procedure The laboratory investigation was carried out on chromium steel heats melted in a magnesia crucible in a 100-lb capacity induction furnace at the Union Carbide and Carbon Re- search Laboratories. The charges for the heats consisted of Armco iron, low-carbon chromium metal, and high-carbon chromium metal, the relative proportions of which were calculated so that the various heats would contain from approximately 0.06 pct carbon and 8 pct chromium to 0.40 pct carbon and 30 pct chromium at melt-down. When the charges were melted, the bath temperatures were raised to the desired level, and the heats were then decarburized by successive injections of oxygen at the slag-metal interface through a ½-in. diam silica tube at a pressure of 30 psi. The duration of the oxygen injections was from 30 sec to 2 min. at intervals of approximately 5 to 30 min. It did not appear that length or frequency of the injection periods had any significant effect on the results; cansequently, no effort was made to hold them constant and they were controlled only as was expedient to the general working of the heats. Between successive injections, the heats were sampled by means of a copper suction-tube sampler that yields a sound, rapidly-solidified sample representative of the composition of the molten metal at the temperature of sampling. This sampling device is a modification of the one described by Taylor and Chipman.1 An attempt was made to vary bath temperatures between samples, but it quickly became evident that, unless the variations were small or unless the new temperature was maintained for a minimum of 15 min. during which an injection of oxygen was made in order to accelerate the reactions, a very wide departure from equilibrium resulted. For most of the runs, therefore, temperature was maintained relatively constant at approximately 1750 or 1820°C. A few reliable observations at other temperatures, however, were obtained. Temperature Measurement The high temperatures involved in this investigation were measured by the radiation method, utilizing a Ray-O-Tube focused on the closed end of a refractory tube immersed in the metal bath. The immersion tubes employed were high-purity alumina tubes specially prepared by the Tona-wanda Laboratory of The Linde Air Products Co. These tubes were quite sturdy under reasonable mechanical stress at high temperature. They were unusually resistant to thermal shock, and chemical attack on them by the melts was slow. With care, it was found possible to keep these tubes continuously immersed in a heat for as long as 5 hr at temperatures up to 1850°C, before failure by fluxing occurred. The Ray-O-Tube—alumina tube assemblage was similar to those supplied commercially for lower temperature applications. In operation, the alumina tube was slowly immersed in the molten metal to a depth of approximately 5 in., and the device was then clamped solidly to a supporting jig where it remained for the duration of the run. A photograph of the equipment, in operation with Ray-O-Tube in place and oxygen injection in progress, is shown in Fig 1. When in position in a heat, the instrument was calibrated by means of an immersion thermocouple and an optical pyrometer. For calibration through the range of temperatures from 1500 to 1650°C, a platinum -platinum + 10 pct rhodium thermocouple in a silica tube was immersed alongside the alumina tube. Output of the Ray-O-Tube in millivolts and the

Jan 1, 1950

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during the period Nov. 10 to Dec. 10, 1915: F. Lynwood Garrison, Philadelphia, Pa. E. Fleming l'engle, Costa Rico, C. A. William J. Lakeland, Burma, India. Fred Maccoy, El Oro, Mexico. Dwight E. Woodbridge, Duluth, Minn. 0. N. Scott, Toronto, Ont., Canada. Chester A. Fulton, Yonkers, N. Y. K. P. Swenson, Tokyo, Japan. Willet G. Miller, Toronto, Canada. - H. L. Mead, New York, N. Y. L. G. Huntley, Pittsburgh, Pa. E. DeGolyer, Norman, Okla. L. E. Howard, Lockport, N. Y. J. S. Lane, New York, N. Y. H. W. DuBois, Philadelphia, Pa. T. V. Nonactre, Argentina. Howard R. Stewart, London, England. N. H. Darton, of the U. S. Geological Survey, has returned to Washington after a long season of field work in New Mexico investigating the prospects of finding potash deposits in the Red beds.

Jan 1, 1916

By Mack H. Shumate

1 Raw coal from Truax-Traer Coal Co.'s Burning Star Slope mine, Jackson County, Ill., is brought to the surface by the new 42-in. slope belt haulage conveyor at the rate of 850 tph. The loading system shown above employs four storage tracks, two tail tracks for loading, and four 25-hp hoists, operating in pairs, and coupled to two dolly cars to move the trains of cars through the tipple. The system has a capacity for loading 1800 tph. One operator is needed to load on each of two shifts. A third man working for a few hours on night shift sets up for the morning cycle. Railroad crews bring in empties placing them in the storage yard, twenty cars to the track. Trains of empties are pulled through to the tail track and loaded on the return; hoists at opposite ends pull the trains in each direction. [ ] 2 Pairs of hoist drums are interconnected electric- ally by a Trench lay cable buried between the tracks. When one hoist operates moving the cars, the tail hoist idles with brake released. The operator, situated in the tipple over the cars, views the storage yard at the end of the first shift (left). When returning loaded cars to yard, four or five cars are held on the dolly to couple the next string of empties. Empties are ready for loading on the tail track (right). Differing from a gravity system in which empty and load tracks are on a slight grade, this system is designed for 80 railroad cars for a two-shift operation and one rail service per day.

Jan 6, 1962

By Nick Turner, E Walker, George C. Bowser

A fully field tested mine-wide data/communications system is presented which integrates total data acquisition, control, and instrumentation into a single system. Installations at Kitt #1 and Amonate Mines (W.Va.1 use an LSI-11 series computer which communicates with easily installed field data stations over a single twisted wire pair. Complete field test data are presented, identifying the problems and successes experienced in the development, installation, operation and maintenance of the system, and the training of mine personnel. Of particular interest is the system installed at Kitt #1 which has been in continuous use since February 1982. The paper will also deal with the application of a computer-based carbon monoxide monitoring system installed at the Amanate mine in September 1982. The purpose of that system is to monitor air quality and to provide early fire detection in the belt entry to permit the use of belt air for face ventilation.

Jan 1, 1983

By A. Lubinski, J. E. Hansford

Rotating drill pipe passing through dog-legs suffers fatigue damage due to cyclic bending stresses. Curves of the cumulative fatigue damage incurred in either steel or aluminum drill pipe going through Such dog-legs are presented. These curves provide means for properly planning the rate of angle build-up in directionally drilled wells and allow discarding of drill pipe which has been fatigue-damaged in dog-legs. INTRODUCTION Drill pipe which is subjected to bending as it rotates, experiences a cyclically varying bending stress. If this bending stress is sufficiently large, the drill pipe is fatigue-damaged by each revolution, and ages as fatigue damage accumulates. Drill pipe can be bent intentionally, as in the case of directionally drilled holes, or unintentionally due to unde-sired changes in hole direction caused by variations in formation properties, weight on bit, etc. These changes in hole direction, whether intentional or unintentional, are called dog-legs. The theoretical limits of dog-legs which are permissible before the drill pipe begins to fatigue can be calculated.' However, in wells where the maximum permissible dogleg is exceeded, the concept of cumulative fatigue damage can be used to estimate damage suffered by the drill pipe. This concept has already been used to estimate the cumulative fatigue damage of drill pipe due to drilling vessel roll.' The purpose of this paper is to extend the usage of the cumulative fatigue damage concept to drill pipe in doglegs, and to draw conclusions which may be beneficial in preventing numerous frustrating and expensive drill pipe failures. FATIGUE OF STEEL DRILL PIPE IN IDEALIZED GRADUAL AND LONG DOG-LEGS It is taken for granted that, if necessary, the reader will become familiar with the definitions and concepts which follow by examining the reference cited in each case. For Ref. 1, it will suffce to read only through the section Abrupt Dog-Legs. 1. Concept of the two extreme kinds of idealized doglegs: gradual and long dog-legs and abrupt dog-legs,' 2. Concept of why the bending moment in drill pipe un- der tension is the largest in the vicinity of the tool joint,' 3. Concept of why dog-leg severity which drill pipe can withstand decreases with an increase in tension,' and 4. Definition of the rate of change of over-all hole angle (dog-leg severity)." Figs. 1 and 2 indicate the aging (fraction of life expended) of steel drill pipe passing through a gradual and long dog-leg. Both figures have a left-hand ordinate scale labled Length of Drill Pipe Below Dog-Legs. This scale can be used for cases in which the drill collar weight is applied to the bit and does not contribute to the tension in the drill pipe. It can be used for either 3 1/2-, 4 1/2- or 5-in. drill pipe. This is due to the fact that, if the drill collars do not contribute to the drill pipe tension, then the effect of pipe tension on bending due to a change in pipe size is nearly compensated for by a corresponding change in pipe rigidity. On the other hand, if drill pipe is rotated off bottom, then drill collars contribute to the tension in the drill pipe and this increase in tension is not compensated for. In this case, one of the three right-hand ordinates must be used (the one which corresponds to the correct drill pipe size). In the right-hand ordinates, tension should be understood as the weight in mud of the portion of the drilling string below the dog-leg, minus the weight on bit.

Jan 1, 1967

By R. E. Goodman, M. A. Mahtab

The, state of stress around a vertical wellbore in rock following nonlinear stress-strain laws is examined by means of finite element analysis. The wellbore, is considered an axisymmetrier body with axisymmetric loading. The initial vertcal and borizontal stresses are "locked" in the rock elements around the wellbore and a new state of stress is generated by the displacements which occur around the borehole. A point-uise variation of the elastic moduli is made on the basis of the new stress state and the triaxial data. The initial stresses tire now reintroduced along with tile changed moduli and original boundary constraints. This procedure is repeatrd until convergent stresses are reached. The effect of nonlinearity on streases is examined for a 6,000-ft wellbore in a scbistose gnezss and Berea sandstone using results of laborratory triaxial compression tests. The results sbou that the effect is restrited to one well radius from the bottom periphery of the bole. Beyond a distance of one-quarter radius, the elfect of nonlinearity on stresscs IS almost always less than percent for the cases conszdered, The consideration of a static pressure inside the well does not magnify the effect of monlinearity on borehole stresscs. INTRODUCTION The terms " wellbore" and "borehole" here designate cylindrical openings in the ground with vertical axis and a circular cross-section. A knowledge of the stress redistribution that occurs on excavating a wellbore is important in understanding (1) the behavior of the lined or unlined hole, (2) hydraulic fracture response, and (3) the effect of stress redistribution on drillability; also it is important in predicting initial stresses in the virgin ground, and in analyzing the response of measuring instruments placed in the borehole. Our knowledge of the state of stress around a wellbore has been restricted to homogeneous, isotropic, elastic material and derives chiefly from the analysis by Miles and Toppingl and the photoelastic work of Galle and Wilhoit2 and Word and Wilhoit.3 In this investigation the state of stress is examined for a nonlinear elastic material by means of finite element analysis. Many rocks possess stress-strain curves that depart notably from straight lines in their initial or final portions. While the literature contains abundant stress-strain data from triaxial tests (axisymmetric loading) on cylindrical rock specimens, there is little information on rock deformability under nonaxisymmetric loading conditions such as occur at each point around the bottom of a wellbore. Although there is some knowledge of the effect of intermediate principal stress on rock strength, there is virtually nothing known about its effect on rock deformability; therefore, we have assumed here that the effect of intermediate principal stress can be ignored. A schistose gneiss4 and Berea sandstone5 were selected as representative rocks for this analysis. The traditional graphs of deviator stress (ol -o3) vs axial strain were reworked to give the tangent modulus as a function of the deviator stress for varying values of the minor principal stress. The result is a nesting family of skewed, bell-shaped curves for tile gneiss (Fig. 1A) and the sandstone (Fig. 2A). A similar replotting of the lateral strain data defines the variation of Poisson's ratio (v) with the deviator stress and confining pressure. These curves, shown in Fig. 1B for the gneiss and in Fig. 2B for the sandstone, are not so well ordered as the tangent modulus curves. However, all of these display an increase of v with deviator stress application, but the rate of increase diminishes with confinement. The ET and v curves for the two rock types are tabulated in Tables 1A and 1A for use in a digital computer so that material properties corresponding to a given state of stress can be assigned by interpolation. STATEMENT OF THE PROBLEM Given a state of stress in the ground prior to drilling a hole (initial stresses), we assume that

Jan 1, 1969

AVERY great profit is derived from removing the gilding and retrieving gold, without destroying the works of silver or other metal. If this method did not exist, the greater part of the gold that is put on certain works would be lost. Even though you might think to scrape it off patiently with a sharp scraper, if it had been drawn with draw-plates, or if it were at the bottom of objects where the scraper could not enter easily, it would be utterly in vain. Therefore, I find that to do this it is necessary to use one of three methods. The first is when it is found on a thin object. Take a large crucible, fill it with mercury, and heat it on a little furnace. When you see that it begins to boil and simmer, put your work in it and stir it around, shaking and rubbing it well in this, and finally rub it with a scratching tool until you see that the mercury has drunk up and absorbed all the gold. Then, having done this, take the said mercury and pass it through an untanned leather purse, and in the bottom of this you will find all the gold like sand. Put this in the bottom of a crucible or in something else over a charcoal fire and evaporate it. If the objects are of a thicker form the gilding is removed from them in another way, by covering them with powdered sulphur and lighting a fire on them. When you see them burning well with the fire all around, beat them in a clean bowl of wood or something else and collect everything that separates with the sulphur from the work; this will be gold in the form of a leaf wherever it has been touched by the fire. The gold is then extracted from this burned sulphur by purifying it in a cupeling hearth with lead. The third method is to touch the gold that you wish to take off the works with an aqua fortis made from saltpeter, rock alum, vitriol, sal ammoniac, and some verdigris.* This acid dissolves and eats the gold by virtue of its corrosive power. Having thus touched the gold with this acid and having saturated the latter with a quantity of gold, put it in a cucurbit and evaporate it over a little furnace as is done with silver, collecting the acid and the spirits if you wish.

Jan 1, 1942

By Hsun Hu, R. S. Cline

In an earlier publication1 it was shown that a single crystal of Cu-4 wt pct Al cold-rolled in the (110)[112] orientation was stable up to 95 pct reduction, although the orientation spread was considerable larger than in a similarly oriented and cold-rolled copper single crystal. When rolled to 99 pct reduction, the copper crystal retained its initial orientation and a high degree of sharpness of texture, whereas the Cu-4 pct

Jan 1, 1969

By P. Barnes

In a paper recently read before the Institute by Mr. W. A. Goodyear, a useful presentation was made of the subject of the production of' water-gas on a large scale, by the use of a regenerative form of apparatus. By way of supplement to that paper, a brief statement of the details of a plan which was carried out at the works of the Elgin National Watch Company at Elgin, Ill., may be of interest, 'although the ultimate result of the working of the producer was not successful or satisfactory. This company had decided to build a gas-works for the supply of illuminating gas to their factory, on a much larger scale than that of the petroleum-works which had very successfully supplied the smaller buildings for many years, and in March, 1882, the material for a gas-making cupola furnace was purchased. A few weeks later it was decided to make the attempt to bnrn the gas under the steam-

Jan 1, 1884

By W. M. Robertson

The rate of crack Propagation thvough a solid meta1 in the presence of a liquid metal has been calculated. The crack is assumed to propagate by solution of the solid in the liquid under the influence of an applied stress, with volume diffusion of the dissolved solute through the liquid controlling the propagation. The calculated velocities can be tens of centimeters per second or higher. THE embrittlement of normally ductile solid metals by liquid metals has been the subject of extensive study, as summarized in the book by Rostoker, McCaughey, and arkuus.' In experimental studies of liquid-metal embrittlement it is usually concluded that the observed crack-propagation rates are too high to be accounted for by diffusion processes. Diffusion is considered to be an unimportant factor and various other mechanisms are invoked to account for the experimental observations. The similarities of liquid-metal embrittlement to stress-corrosion cracking, to hydrogen embrittlement of steel, and to low-temperature embrittlement of bcc metals are frequently used as analogies for these mechanisms.1"3 The present paper assesses how rapidly a crack could propagate by a mechanism of volume diffusion through the liquid metal. We assume that the crack propagates by solution of the solid in the liquid at the crack tip under the influence of the applied stress and diffusion of the dissolved solute away from the crack tip. The model uses only macroscopic thermodynamic, kinetic, and elastic concepts. The calculations indicate that this dissolution-diffusion mechanism can give high crack velocities. In some previous treatments4'' of crack propagation in a liquid-metal environment the fundamental step has been the breaking of atomic bonds at the crack tip. The liquid greatly decreases the energy necessary to break these bonds. The present model assumes the crack is filled with liquid metal; the presence of the liquid is essential because diffusion through the liquid is assumed to control the rate of propagation. With proper modification this model could also apply to stress corrosion in a liquid environment. THEORY Consider a crack in a homogeneous elastic continuum, ignoring all the structural details of the solid. This neglects a host of metallurgical details which can be significant in the problem of liquid-metal embrittlement;' but this simple assumption is a useful approach in evaluating the role of diffusion through the liquid. The stress distribution around the crack tip establishes a gradient in the chemical potential at the tip, which causes a diffusion flux through the liquid away from the tip. The solid-liquid interfacial tension works against crack propagation, since propagation requires creation of interfacial area. From these two considerations we derive the diffusion flux, which then yields an expression for the velocity of the crack tip. The concentration of the solute in the liquid, C, is equal to the equilibrium concentration in the presence of an unstressed, flat surface, Co, plus the excess concentration due to the stress, AC(a), plus the excess concentration due to capillarity, AC(y): We calculate AC(o) and AC(y) and then obtain the diffusion flux. Consider (Fig. 1) a long flat crack of length 2L, thickness 2r, and tip radius r, where r remains constant as the crack propagates in the positive x direction. There is no stress ay in the y direction across the flat surfaces of the crack. The magnitude of the stress at the crack tip due to the applied stress, a,, is given by the relation6 ^=^[l-2^] 12] which, for long narrow cracks, becomes The stress increases the chemical potential in proportion to the strain energy.? The excess chemical potential due to the stress, Ap(a), is given by where 52 is the atomic volume of the solid and E the Young's modulus. Inserting Eq. [3] gives Now consider the crack to be filled with a liquid metal. The excess solubility due to stress, hC(a), is given by the excess chemical potential due to capillarity, Ap(y), is given by8 where y is the solid-liquid interfacial energy, and v1 and YZ are the two principal radii of curvature of any surface point. At the crack tip, r1 = -r and vz = m, so TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME

Jan 1, 1967

Masjid-i-Su1aiman.—There have been no new developments in the Masjid-i-Sulaiman field during the year. Drilling, deepcning and acidizing operations for maintenance of production havc continued normally. Reservoir conditions have been unchanged, the rate of fall of dome prcssure remaining very low—at about 0.4 lb. per sq. in. per million tons net production. Drilling on the Lali structure northwest of Masjid-i-Sulaiman has continued but oil has not been encountered in commercial quantities. Haft Kel.—The progressive drilling program extending the production capacity of the Haft Kel field was completed carly in the year and the field is now on a routine maintenance basis. Drilling has continued on the white-oil springs structurc northwest of Haft Kel. Naft-i-Shah.—No developments of interest have occurred in Naft-i-Shah field. Offtake is for local markets only. A further large produeer was completed during the year. Gach Saran.—By the end of 1939, work on plant and pipe lines to put, the field on a production basis was approaching completion. Two substantial producers were also drilled in the initial production area. Pazanun and Agha Jari.—No further drilling was carried out on the Pazanun structure during the year, gas only having been obtained to depths exceeding 8000 ft. On the adjacent Agha Jari structure, however, a second satisfactory oil producer was completed.

Jan 1, 1940