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By M. Metzger, J. C. Bilello

Microyielding in 99.999 pct Cu occuwed in two distinct parabolic microstages and was substantially indeoendent of grain size at the relatiz~ely large grain sizes stzcdied. The strain recouered on unloading was a significant fraction of the forward strain and was initially higher in a copper-coated single crystal than in poly crystals. Results were interpreted in terms of cooperative yielding and short-range dislocation motion activated otter a range of stresses, and a formalism was given for the first microstage. It was suggested that models involving long-range dislocation motion are more appropriate for impure or alloyed fcc metals. THERE are still many unanswered questions concerning the degree and origin of the grain size dependence of plastic properties. In the microstrain region, a theory of the stress-strain curve proposed by Brown and Lukens,' based on an exhaustion hardening model in which the grain boundaries limit the amount of slip per source, accounted for the variation with grain size of microyielding in iron, zinc, and copper.' This theory assumes N dislocation sources per unit volume whose activation stress varies only with grain orientation. Dislocations pile-up against grain boundaries until the back stress deactivates the source, which leads to a relationship between the axial stress and the strain in the microstrain region given by: where G is the shear modulus, D the grain diameter, a the flow stress, and a, is the stress required to activate a source in the most favorably oriented grain.3 If this or other grain-boundary pile-up models are correct, then the reverse strain on unloading would be much larger for a polycrystalline specimen than for a single crystal. Also, the microplasticity would become insensitive to grain size if this could be made larger than the mean dislocation glide path for a single crystal in the microregion. These questions are examined in the present work on polycrys-talline copper and a single crystal coated to provide a synthetic polycrystal. EXPERIMENTAL PROCEDURE Tensile specimens 3 mm sq were prepared from 99.999 pct Cu after a sequence of rolling and vacuum annealing treatments similar to those recommended by Cook and Richards4-6 to minimize preferred orientation. Grain size variation from 0.05 to 0.38 mm was obtained by a final anneal at temperatures from 310" to 700°C. Dislocation etching7 revealed pits on those few grains within 3 deg of (111). For all grain sizes dislocation densities could be estimated as -107 cm per cu cm with no prominent subboundaries. The single crystals, of the same cross section, were grown by the Bridgman technique with axes 8 deg from [Oll] and one face 2 deg from (111). An anneal at 1050°C produced dislocation densities of 2 x 106 cm per cu cm and subboundaries -1 mm apart in these single crystals. A Pb-Sn-Ag creep resistant solder was used to mount the specimens, with a 19 mm effective gage length, into aligned sleeve grips fitted to receive the strain gages. All specimens were chemically polished and rinsed8 to remove surface films just prior to testing. The synthetic polycrystal was made by electroplating a single crystal with 1 µ of polycrystalline copper from a cyanide bath. Mechanical testing was carried out on an Instron machine using two matched LVDT tranducers to measure specimen displacement, the temperature and the measuring circuit being sufficiently stable to yield a strain sensitivity of 5 x 107. At the crosshead speeds employed, plastic strain rates were, above strains of 10¯4, about 10¯5 per sec for polycrystalline specimens and 10-4 per sec for the single crystals. Plastic strain rates were an order of magnitude lower at strains near l0- '. A few checks at strain rates tenfold higher were made for reassurance that the initial yielding of polycrystalline copper was not strongly strain-rate dependent. Test procedures followed the general framework outlined by Roberts and Brown.9,10 An alignment preload of 8 g per sq mm for polycrystals, and 2 to 4 g per sq mm for single crystals, was used for all tests. These gave no detectable permanent strain within the sensitivity of the present experiments; although at these stress levels, small permanent strains are detectable in copper with methods of higher sensitivity.11 12 stress and strain data are reported in terms of axial components. RESULTS General. The initial yielding is shown in the stress vs strain data of Fig. 1. For polycrystals, cycle lc, the loading line bent over gradually without a well-defined proportional limit, and almost all of the plastic prestrain appeared as permanent strain at the end of the cycle. The unloading curve was accurately linear over most of its length with a distinct break indicating the onset of a significant nonelastic reverse strain at the stress o u, indicated by the arrows. The yielding in subsequent cycles, Id and le, had the same general character. The single crystal behavior, shown to a different scale at the right of Fig. 1, was different in that initially the nonlinear reverse strain was unexpectedly much greater than for polycrystals. It should be noted that these soft crystals had a small elastic

Jan 1, 1970

By ALEC CROWELL

This brief summary of oil and gas developments in Alabama, Florida and Georgia has been made possible through the courtesy of Stewart J. Lloyd, Assistant State Geologist of Alabama; Herman Gunter, Director, Florida Geological Survey, and Garland Peyton, Director, Georgia Department of Mines, Mining and Geology.

Jan 1, 1946

By Jerry A. Selvaggi, Richard B. Jacob

The High Gradient Magnetic Separator (HGMS), also known as the High Gradient Magnetic Filter (HGMF), is an effective device utilized in magnetic separation. This method of separation is gaining popularity in the separation of submicron material containing feebly magnetics. The most common use of this type of separator is in the removal of iron stained particles to improve the brightness of kaolin clay. Potential areas for use of this magnet include: (1) desulfurization of coal (2) the clean-up of mill effluent (3) removal of fine particulate matter from municipal and indus¬trial waste (4) desulfurization of oil Design, operation, and applications of this separator are further dis¬cussed in papers by R. R. Oder (1975), and R. R. Oder and B. I. Horst (1975). This device is a system composed of an iron enclosure of high per¬mability material housing a set of electrical coils, a canister en¬closing a magnetic matrix (stainless steel wool), an electric power supply and a hydraulic system to maintain specified operating tempera¬ture conditions. See Figure 1.

Jan 1, 1984

By C. R. Barrett, N. N. Singh Deo

The high-temperature steady-state creep behavior of a series of dilute copper-silicon alloys was studied to determine the effect of stacking fault energy on the creep-rate. The steady-state creep rate is, when taken at equivalent diffusivities decreases with decreasing stacking fault energy. The stress and temperature dependencies of is suggest that creep is a difusion controlled dislocation climb process. Electron microscopy studies of the creep substructure revealed: 1) the subgrain size is not a function of the stacking fault energy in these alloys, 2) the dislocation density not attributed to the subgrain walls seems to be higher during primary creep and decreases to a lower steady value during steady-state creep, and 3) the dislocation density during steady-state creep decreases with decreasing stacking fault energy. In the past few years numerous investigators have studied the influence of stacking fault energy on high-temperature creep strength. Most of these investigators have confined their attentions to studying the relationship between steady-state creep rate, is, and stacking fault energy, ?, when samples are tested under conditions of comparable stress and temperature. For the case of fcc metals, it was initially shown by Barrett and Sherbyl and since confirmed by many others2"4 that is decreases with decreasing ?, often following an empirical relation of the form i ?m where m is a constant about equal to 3. The application of theory to explain this observation has not been entirely successful. One of the main difficulties has been the almost complete lack of structural information (dislocation density, subgrain size, and so forth) for samples with different stacking fault energies, tested under high-temperature creep conditions. weertman5 has attempted to explain the stacking fault energy dependence of is on the basis of a dislocation climb mechanism. Assuming that both the rate of dislocation core diffusion and the ease of athermal jog formation decreases as ? decreases Weertman has argued that the rate of dislocation climb and hence the creep rate should also decrease as ? decreases. One questionable aspect of Weertman's analysis is the assumption that core diffusion down extended dislocations is slower than core diffusion down unextended dislocations. The only experimental work done in this area, by Birnbaum et al.6 on nickel and Ni-60 Co, has shown the core diffusivity to increase with decreasing ?. Theories of steady-state creep based on the diffusive motion of jogged screw dislocations often seem unable to predict even the qualitative nature of the es- relationship. Assuming that Weertman is correct in his assumption that the dislocation jog density decreases with decreasing ? then the jogged screw theories predict an increasing dislocation velocity with lower ?. It is usually assumed that the increase in dislocation velocity implies a corresponding increase in creep rate. However, two other factors must be considered before such a statement can be made. That is, we must know how both the mobile dislocation density and the effective stress (the difference between applied stress and internal stress) vary with ?. Significant changes in either one of these factors could outweigh any change in dislocation velocity accompanying a change in ?. And with the slower rates of recovery expected in low stacking fault energy materials it seems likely to expect both mobile dislocation density and effective stress to be dependent on ?. Sherby and Burke7 have suggested that stacking fault energy influences the creep rate in an indirect way. These authors cite evidence that the steady-state subgrain size generated during high-temperature creep is a function of ? decreasing with decreasing ?. Assuming the creep rate to be proportional to the area swept out by each expanding dislocation loop and that subgrain boundaries are good barriers to dislocations, then the creep rate should be proportional to subgrain area, hence increasing as ? increases. A critical evaluation of any of the above theories requires more quantitative information concerning the dislocation substructure generated during high-temperature creep. Accordingly this investigation was undertaken with an aim of studying the influence of stacking fault energy on tbe steady-state creep characteristics of a series of dilute copper-silicon alloys. Special emphasis was placed on studying the strain dependence of both the dislocation configuration and density. MATERIALS AND PROCEDURE Dilute copper-silicon alloys of the compositions shown in Table I were tested in tension at constant stress. The relative stacking fault energy of these alloys has been determined and is shown in Table 11. An Andrade-Chalmers lever arm was used to maintain constant stress and testing was carried out in a water

Jan 1, 1970

By Zay Jeffries

AN acute current shortage of copper, with the prospect that conditions may become worse, indicated by Office of Production Management information. Present estimates of copper requirement for defense indicate that nearly all the available metal will be required in the future for this purpose. Severe dislocations are, expected, but the objective is to distribute the copper available for civilian use in such a manner as to minimize these dislocations. The advisory committee on metals and minerals has been asked for a suggestions which may be helpful in meeting this situation.\

Jan 1, 1941

By William F. Boericke

CONSIDERABLE waste of oil and grease in lubricating motors and other machinery results from the use of bearings that are not totally enclosed. There is also the likelihood of damage to the bearing through the accidental introduction of grit or dust both in the oiling process and after, unless the cover is entirely dustproof. With the ordinary sleeve bearing that is only partly enclosed, it is generally easier for a careless attendant to cause trouble through neglect than with the ball bearing type, which from its design, must be totally enclosed to give effective service, and needs a minimum of attention. At one of the large mining companies which has taken a leading part in reducing unit costs and pioneering new developments in mining machinery, ball bearings have been gradually supplanting the conventional type of sleeve bearings on many of their motors, centrifugal pumps, and other machines in the mines. This innovation is not recent, as substitution of ball bearings on mine motors was first tried out by this company in 1909. Since then an increasing number of such bearings have been put in. They are now favored because of increased operating efficiency and reduction in lubrication costs.

Jan 1, 1926

By W. A. Ver Wiebe

Spurred on by the very high demands for new crude supplies resulting from World War 11, the oil men of Kansas strained every effort in 1943 to find as many new pools as possible. In all, 1761 test wells were drilled, ,of which 895 were successful in finding new oil supplies and 32 in finding new gas supplies. The total number of wildcat wells drilled in Kansas was 577, including the so-called "extension wildcats," which are located less than 2 miles from production. As a result of the very determined effort to find new oil reserves, 49 of the wildcat test wells found new oil pools in western Kansas and 7 found new oil pools in eastern Kansas. There were 289 rank wildcat tests, and among these 28 were successful ventures. They are responsible for 26 of the new oil pools recorded for the year and 2 of the new gas pools recorded. The ratio of dry holes to producing wells among such rank wildcats is thus approximately 10 to I (289 dry and 28 good). This compares with a ratio of II: I in 1942 and 6:1 in 1941; the same in 1940 and 5:Iin 1939. With nearly all wells flowing to their maximum economic capacity, the total production for Kansas during 1943 reached a new high; that is, 107,700,000 bbl., compared with 97,000,000 during the previous year. Similarly, the amount of gas sold during 1943 made a new high point on the production curve. The total amount was 122 billion cubic feet, compared with about 98 1/2 billion cubic feet for the year previous. As usual, the large Hugoton field of south- western Kansas accounted for approximately half of the total gas production. Highlights of the Year Despite the fact that 56 new pools were found in Kansas during 1943, it must be admitted that the future reserves of the state have not been increased greatly. Most of the new pools seem to be of minor value, although it is admittedly impossible to gauge the future production of any pool in Kansas with any exactitude. Judging by the later performance of some of the pools found in 1942 and in 1941, less than five of the new pools are likely to make any great contribution to the state's future oil reserves. Taking up the counties of Kansas in alphabetical order, the following statements summarize the highlights of the year. In Graham County, the Morel pool was extended to the southeast and this pool now promises to become one of the important pools of western Kansas. Several of the older wells have already contributed more than I000,000 bbl. of oil, and such a figure is considered very satisfactory in Kansas. In McPherson County, important new reserves were found by persistent drilling in township 17 S., R. I. W., the most northeastern township of the county. Many new wells in older pools and discovery wells in new pools make this region look promising. The Lindsborg pool, which had a sensational revival during 1942, was also extended in a number of directions and has now become a rather large producing area with a fairly high future potential capacity.

Jan 1, 1944

By W. A. Ver Wiebe

Spurred on by the very high demands for new crude supplies resulting from World War 11, the oil men of Kansas strained every effort in 1943 to find as many new pools as possible. In all, 1761 test wells were drilled, ,of which 895 were successful in finding new oil supplies and 32 in finding new gas supplies. The total number of wildcat wells drilled in Kansas was 577, including the so-called "extension wildcats," which are located less than 2 miles from production. As a result of the very determined effort to find new oil reserves, 49 of the wildcat test wells found new oil pools in western Kansas and 7 found new oil pools in eastern Kansas. There were 289 rank wildcat tests, and among these 28 were successful ventures. They are responsible for 26 of the new oil pools recorded for the year and 2 of the new gas pools recorded. The ratio of dry holes to producing wells among such rank wildcats is thus approximately 10 to I (289 dry and 28 good). This compares with a ratio of II: I in 1942 and 6:1 in 1941; the same in 1940 and 5:Iin 1939. With nearly all wells flowing to their maximum economic capacity, the total production for Kansas during 1943 reached a new high; that is, 107,700,000 bbl., compared with 97,000,000 during the previous year. Similarly, the amount of gas sold during 1943 made a new high point on the production curve. The total amount was 122 billion cubic feet, compared with about 98 1/2 billion cubic feet for the year previous. As usual, the large Hugoton field of south- western Kansas accounted for approximately half of the total gas production. Highlights of the Year Despite the fact that 56 new pools were found in Kansas during 1943, it must be admitted that the future reserves of the state have not been increased greatly. Most of the new pools seem to be of minor value, although it is admittedly impossible to gauge the future production of any pool in Kansas with any exactitude. Judging by the later performance of some of the pools found in 1942 and in 1941, less than five of the new pools are likely to make any great contribution to the state's future oil reserves. Taking up the counties of Kansas in alphabetical order, the following statements summarize the highlights of the year. In Graham County, the Morel pool was extended to the southeast and this pool now promises to become one of the important pools of western Kansas. Several of the older wells have already contributed more than I000,000 bbl. of oil, and such a figure is considered very satisfactory in Kansas. In McPherson County, important new reserves were found by persistent drilling in township 17 S., R. I. W., the most northeastern township of the county. Many new wells in older pools and discovery wells in new pools make this region look promising. The Lindsborg pool, which had a sensational revival during 1942, was also extended in a number of directions and has now become a rather large producing area with a fairly high future potential capacity.

Jan 1, 1944

By S. F., French

IN reviewing the design of the ore haulage system for the Morenci project, the reader should bear in mind that the railroad and its equpiment cannot be considered as an independent railroad provided only for the purpose of transporting ore from one point to another, but as an integral part of the operation which begins at the electric shovels loading ore at the mine, and ends where the ore, after having been crushed in the primary crushing plant, is deposited in the bins at the secondary crushing plant. Obviously then, the problem consisted of designing a system that would function to the best possible advantage in complete co-ordination with the other units.

Jan 1, 1942

By H. C. Babbitt

The Effect of Arsenic.—A question involving the temperature of precipitation of ammonium phospho-molybdate, which was brought to my attention some time ago, led to the following experiment :*

Jan 1, 1893

By AIME AIME

IN ORDER to carry on its work most effectively, the Committee on Industrial Organization (now known as the Committee on Industrial Relations) consists, of .a number of sub-committees, each composed of a chairman and members who are especially fitted to carry out the work designated by its title. With only one or two exceptions, all of these committees made reports at the New York meeting of the Institute, in February of this year, abstracts of which follow.

Jan 1, 1920

By L. C. WYMAN

THIS paper discusses what mining reports should contain when presented to the California State Corporation Department, to accompany applications for the sale of stock to the general public, but the principles involved apply to mine financing everywhere. Such reports should 'be as clear and concise as possible, endeavoring to tell the truth in as few words as necessary. Should the engineer be aware that his report is to be used in connection with the sale of stock to the general public, he should consider the public as his client as well as the person who actually employs him. It is always required that the engineer be favorably known and of recognized standing. The following points should be given careful attention : 1. A legal description and location of the property. 2. Transportation conditions, and how they may be expected to affect the operating costs. 3. A brief history of the property, its production record as to tonnage, grade, and character of the ore should be given. Should the property have suspended operations for any reason, this should be given. Any details of former operating costs should be given, especially as to how any improvement could be made, due to better methods which might be employed.' 4. The main geological features and whether they are such as to lead the engineer to believe that the mine may possibly 'be exhausted or the ore of such grade as to be no longer profitable. If he considers them favorable, he should give his reasons for the belief that further development work may produce profitable results. A map showing these features should be submitted, and it is not necessary that such map be highly colored or contain any more than the essential matters. 5. Other mines in the district, or those with similar

Jan 1, 1929

By F. W. Bradley

GOLD is a large subject. One could talk about its geological or mineralogical occurrences, prospect- i11.g for it, mining of .it, its metallurgy or its marketing; but I have decided to limit my discussion to gold as a business-that is, to its production and marketing. In the production of gold, it is necessary to consider the many possible sources, the quantities available, the capital and operating costs and the chances of price-breaking competition. So in the following remarks I shall endeavour to point out that though gold is found in every formation constituting the earth's crust, though it is possible to-find it free in great concentrated placer deposits on the surface, though there are still large unprospected areas of both the surface and the crust, though it may be possible to produce it by the cheapest labor on earth, and by processes not as yet developed, it still has an unlimited market at a definite price. There is no reasonable fear of disturbance by the finding of bountiful deposits, or by cheapening the cost of production due to devaluation, or by the development of any easy processes for direct, or for by product, production.

Jan 1, 1932

By Albert Sauveur

IT is not without some hesitation, and even misgiving, that I venture into a discussion of the now classical Roberts-Austen Roozeboom diagram, lest I too fail, like so many other writers, in giving a satisfactory and logical explanation of these interesting curves. Roozeboom's original diagram is reproduced in Fig. 1. The generally accepted meaning of the various curves has been so often described before this Institute that it will suffice to recall it briefly before passing to my own interpretation of the changes involved.

Nov 1, 1906

By N. Mungan

Formation damage, i.e.. reduclion in permeability, has been generally attribuled to clay minerals which expand or disperse upon contact with water that is less saline than the connate water. Luboratory, studies show that penneahility reduction can also occur in formalions containing only nonexpandable clays such as illite or kaolinite, and can be caused also by changes in pH. Furthermore, pH changes can damage even formations that are essentially free of clays. It is suggested that permeability reduction is due to the small passages being blocked by particles, which may be dispersed clays, cemenlion material or other fine parricles. These particles are dislodged by dispersion of clays due to changes in salinity or by dissolution of calcareous cement by acids, or of silicaceous cement by alkaline solutions. In working with reservoir cores, it was found that extracted cores damaged more easily and extensively than nonextracted cores. The extent of damage depended also on tenlperatltre. INTRODUCTION Permeability is an important property of porous media and has been the subject of many studies by engineers and geologists. Many of these studies are conccrned with formation damage, i.e., reduction in permeability, resulting from exposure of oil-producing formations to water substantially less saline than the connate water. This effect causes understandable concern since during drilling, completion and production phases formations are often exposed to fresh water. The damage resulting from contact with relatively fresh water has been attributed to expansion and dispersion oF clay minerals. During laboratory investigation of the use of NaOH as a wettability reversal agent to increase oil recovery from oil-wet reservoirs, several cores used in the displacement studies suffered loss in permeability. Despite the traditional usage of NaOH for conditioning aqueous mud systems, the role of the caustic filtrate in wellbore damage seems to have been overlooked. Browning2 as recently reported on the effects of NaOH in dispersing clay minerals but he was concerned only with complications that may arise in drilling massive shale beds. The following study was made to examine the role of pH and salinity changes in core damage. Where cores from reservoirs were used, tests were performed with extracted and nonextracted cores both at room and reser- voir temperatures, since it was felt that the test environment and core condition may affect the results. Because of its limited coverage and exploratory nature, this study is not intended to provide answers to field formation damage problems. It is hoped that it will encourage research into new aspects of the permeability reduction problems, particularly those allied to new recovery and production processes. PROCEDURE In all permeability tests, fluids were pumped through the cores at a constant volumetric rate. Only deaerated fluids and reagent grade chemicals were used. The fluids were passed through two ultrafine filters before injection to remove any entrained particles. The cores, with the exception of the unconsolidated cores, were mounted in Hassler holders. Water was used to transmit pressure to the sleeve. The inlet endpiece had two entry ports which permitted scavenging one fluid with another to avoid any mixing in the small holdup volume. The cores were flushed with CO2 gas, evacuated for 5 to 6 hours and saturated with the first liquid at a pressure of 1,000 psi for 24 hours to eliminate any free gas from the cores. Pressure differences up to 20 psi were measured by transducers, calibrated in inches of water and continuously recorded. For greater pressure drops, gauges were used. All reservoir cores were cleaned with a light refined mineral oil, then with heptane, and finally dried with CO2. Compatibility tests showed that no precipitates formed when mineral oil and the crudes were mixed. Some cores were extracted in Dean-Stark-type solvent extractors using xylene and trichloroethane and dried in a vacuum oven at 450F. Each test consisted of a sequence of water, test solution, and again water flow. RESULTS AND DISCUSSION STUDIES IN BEREA CORES Salinity Contrast Berea cores 2-in. in diameter and 12-in. long were cut from sandstone quarried in Cleveland, Ohio. The clay minerals were identified by X-ray diffraction to be chlorite, kaolinite, illite and incerlayered illite. Flow of fresh water or 30,000 ppm brinc does not cause any permeability reduction (Fig. 1). However, after injection of brine the core is readily damaged by fresh water. Damage starts almost instantly as the fresh water injection is begun, and at a cumulative injection of 1.2 PV fresh water, the permeability has dropped from 190 to 0.9 md. Upon continued injection, the effluent contains clay minerals dislodged from the core. The final core per-

Jan 1, 1966

By S. J. Swainson

PHOSPHATE ROCK is a low- priced commodity. This fact has influenced the choice of mining and beneficiating methods to a greater degree, perhaps, than in most other low-grade mining operations. The fact that many yards of everburden and matrix must be stripped and mined per ton of salable "rock" produced and sold has necessitated he development of relatively simple btneficiating plants having high capacity and low capital and operating costs. The law of diminishing returns must always be reckoned with in phosphate mining and washing, and often recovery must be sacrificed in favor of costs in order to achieve the highest over-all economic efficiency. The phosphate-bearing formation, known as "matrix," is composed of (1) phosphate pebbles, which are somewhat rounded in shape and which vary in size from 1-in, to micron sizes, (2) rounded quartz grains usually smaller than 10 mesh, and (3) clay, of varying "stiffness," which is the binder of the matrix. The phosphate pebbles vary in hardness. Their color, which varies from white to black, is not a reliable indicator of the Bone Phosphate of Lime (B.P.L.) content of the

Jan 1, 1944

[NORTH AMERICA UNITED STATES ALABAMA America.-Dyar, 0. C. Anniston.-Klugh, B. 0. Ashland.-Pallister, H. D. Auburn.-*Poor, R. S. Bessemer.-Creveling, J. 0. Lindstrom, W. A. McKenzie, W. 0. Mitchell, F. R. Birmingham.-Abbott, C. E. Aldrich, T. H., Jr. Armstrong, 0. R. Beard, A. H. Benjamin, F. S. Blackburn, E. 0. Blair, A. J. Blair, 0. S. Blair. H. W.]

Jan 1, 1946

The editorial expenses for the preparation of the manuscript of the second edition, as for the first, were provided by grants of the Engineering Foundation and the Open Hearth Steel Committee of the Iron and Steel Division, AIME ; the Seeley W. Mudd Memorial Fund again sponsored the publication of this volume. The companies and research or educational institutions with which the authors, reviewers, and editors are connected also contributed much to the writing and editing of this book through their generous donations of time and travel and office expenses. And finally, the authors and others have given countless hours of their own time with no recompense but the satisfaction of a job well done. In order to give credit to the companies or educational institutions which made it possible for the members of the Editorial Board to devote considerable time to the revision of this book, the names of these members and their affiliations are recorded here as follows W. O. Philbrook, Carnegie Institute of Technology M. B. Bever, Massachusetts Institute of Technology H. B. Emerick, Jones and Laughlin Steel Corporation B. M. Larsen, United States Steel Company A number of individuals suggested desirable changes in the book before rewriting was started. Almost all manuscripts were gone over critically by reviewers, and the resulting criticisms led to the correction of errors and omissions and greatly contributed to the accuracy and completeness of the text. Other people have supplied additional data or illustrations or assisted in other ways. While some of these contributors must remain anonymous because they are not known to the Editors, the cooperation of the following individuals is gratefully acknowledged: R. D. Allen, Republic Steel Corporation, Chicago Isadore Amdur, Massachusetts Institute of Technology Mary Baeyertz, Armour Research Foundation S. P. Bahmer, Republic Steel Corporation, Massillon E. C. Bain and Associates, United States Steel Company, Pittsburgh C. W. Briggs, Steel Founders' Society of America H. W. Briske, Wisconsin Steel Works

Jan 1, 1951

By A. E. Seaton

In this paper it will be my endeavor to trace the development of the marine engine and its appurtenances, and the general progress that has taken place in marine engineering generally during the past fifteen years, rather with the object of attributing much of it to the successful efforts of the makers of iron and steel, thereby rendering my thanks to them for the valuable service they have contributed to my profession, than to recount what has been achieved by the skill, ability and perseverance of my colleagues in shipbuilding and engineering. The engineer has been at all times dependent on the ironmaster, and on more than one occasion his progress has been barred by the inability of the latter to overcome some obstacle to success in his manufacture. But on the other hand, it is equally true that the ironmaster has often been ahead of the engineer, and has been prepared, long beforehand, to supply that which would make a success for the marine engineer if he would avail himself of it.

Jan 1, 1891

By Louis D. Huntoon

SHORTLY after publication of the article in the July, 1924, issue Of MINING AND METALLURGY, entitled "Canada as a Gold Producer," requests were received to determine the ownership of production. Advices have also been received that considerable discussion has taken place on the same questions both in Canada and Great Britain. The author is indebted to R. H. Coates, Dominion Statistician, and George C. Bateman, Secretary, Ontario Mining Association, for the following figures and takes this opportunity of expressing his appreciation. There have been no statistics compiled as to ownership of production. Statistics were compiled as of Dec. 31, 1921 relative to the distribution of stocks, bonds and "other securi¬ties" in industrials, agriculture excepted, throughout the Dominion, and "distribution of ownership of securities issued by mining companies incorporated and operating in Ontario" for the same year. Stock registration does not necessarily represent actual ownership' as large blocks may be endorsed and not transferred; neither does registration actually represent production. When the charts are studied individually and collectively one cannot help but be impressed with the fact .that in the mineral industry of Ontario and the Dominion at large, Canadian registration predominates, the United States registration is about half that of Canada, and Great Britain is about half that of the United States. When the nickel-copper industry is excepted the British registration falls to a very low percentage. Since Dec. 31, 1921, British capital has commenced to flow into mining enterprises in Ontario and it has been already rewarded by the discovery of valuable ore deposits.

Jan 1, 1925