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By David Sinclair

THE dimensions and shapes of mine structures may at present be determined by (1) field experience, (2) structural calculations, and (3) barodynamic tests.§ None of these, however, provide information as to the stresses, their direction and distribution in a mine structure. For the design of pillars, the placing of openings relative to working places such as gangways, haulage levels, etc., this information is desirable. Photoelastic methods provide this and, while relatively new, their appli-cation in all engineering fields is assuming increasing importance. This paper, therefore, will present the method with a few applications to mining, and with sufficient reference for further study by the reader. PART I THE PHOTOELASTIC METHOD The photoelastic method of stress measurement determines the stress distribution in a two-dimensional model by optical means. It makes use of the fact that when a piece of isotropic transparent material, such as glass, celluloid, or Bakelite, is stressed and viewed in polarized** light a picture is seen which indicates by its color bands of light, or fringes, the magnitude of the stresses, their direction and their distribution.

Jan 1, 1940

By E. C. Burke, W. R. Hibbard

Plastic deformation in magnesium single crystals was studied by tensile tests at room temperature utilizing an improved preparation and testing technique. Consistent critical resolved shear stress values for basal slip were obtained. The advent of pyramidal slip at room temperature was rationalized upon the basis of grip constraints. A bend-twinning hypothesis was advanced as an explanation of mechanical twinning which occurs as a complex stress-relief mechanism. INVESTIGATIONS of the plastic deformation of magnesium have been limited to the determination of the fundamental kinetics which may be summarized as follows: 1—Twinning on the {102).l 2— Slip on the (001) plane in the [loo] direction at room temperature.' 3—Slip on the {101) or {102) plane in the [loo] direction above 225°C." 4—Critical resolved shear stresses for basal slip in tension at room temperature of 83 g per sq mm with a variation from 57 to 127 g per sq mm." Bakarian' studied the compression of thin wafers of magnesium single crystals and classified the components of the deformation mechanisms as follows: 1—The Basal field: (001) at an angle of less than 20" to the compression surface. Fracture along {101} or slip on (001) followed by {101} fracture. 2—The prism field: (001) at an angle greater than 60" to the compression surface. Twinning on the {102) generally occurring during the early stages of loading, basal slip in the areas of original orientation and (001) slip within twins. 3—The central field: (001) at angles greater than 20" but less than 60" to the compression surface. Slip on the (001). 4—The critical resolved shearing stress for {101} slip above 225°C was 400 g per sq mm. Observations of mechanical twins in hexagonal close-packed metals have been summarized by numerous investigatorsb-' emphasizing a lateral or rotational atomic adjustment, in addition to the pure twinning shear, and the importance of reorienting the basal plane to a position more favorable for continued slip, rather than the resulting small dimensional changes. Criterion for the operative twinning planes has not been clearly established. Schmid and Boas hurmised that an energy condition related to the atom movements is the determining factor. MillerQ bserved that twinning stresses in zinc crystals decreased as the amount of prior deformation increased. Preparation of Specimens Magnesium single crystals % in. in diam x 8 in. long were grown from the melt under an argon atmosphere in a gradient furnace similar to that described by Jillson." Magnesium containing 0.018

Jan 1, 1953

By Nathaniel Arbiter

There is a history in all men's lives, Figuring the nature of the times deceas'd, The which observ'd, a man may prophesy, With a near aim, of the main chance of things. W. Shakespeare, Henry IV; Part 2 Introduction This nation's first century embraced two stages of the Industrial Revolution. During one, what had been a colonial agricultural economy began to industrialize; water power, then steam after 1794, were the energy sources; coal and iron were the essential ingredients. The second stage started after 1850; aided by rich and diverse mineral resources, the country began its transition from the Iron Age to the Age of Metals. Early civilizations had been built on stone, and fairly high levels were sustained on iron. But the spectacular advances in the past century in communication, in construction, in transportation by sea, rail, land and air, and in much that characterizes modern civilization have depended increasingly on the use of the complete metallic and nonmetallic resources of the earth's crust. Thus it was appropriate to define the Industrial Revolution as “the period during which man's relationship to natural resources became utterly changed”, 1 with minerals playing a major and indispensable role. But we are now becoming aware that the relationship of man to natural resources must change again. On every hand the dangers inherent in the contamination of land, sea and air by the wastes of civilization are becoming apparent. And from the growing realization that mineral wealth is finite must eventually come other far reaching changes in mineral use and distribution. For on the scale of centuries we cannot continue to exploit mineral resources even at present rates, let alone at expanded rates, without eventual depletion of the more abundant resources, and early exhaustion of the less abundant. In the past our problems were relatively easily met by the development of new and improved machinery and processes. But the future will

Jan 1, 1971

By Clarence E. Sims

An effort has been made to give both a comprehensive and simplified picture of the origin, modes of formation, and characteristics of nonmetallic inclusions in steel. Exogenous inclusions, those formed by mechanical entrainment or heterogeneous reaction, have their principal source in ladle refractories. Mechanical emulsion is not considered a likely mechanism. Endogenous inclusions, resulting from homogeneous reactions, are formed mainly during cooling and freezing. They are principally oxides and sulfides but include some nitrides and carbides. Deoxidation affects both the quantity and character of such oxide inclusions and significantly affects the size and shape of sulfides. The importance of inclusions is largely in their effect on mechanical properties. It is fitting and proper that we should honor the memory of those technical giants who have left such a rich heritage to our profession. Today, according to annual custom, we pay tribute to such a man. To have been chosen to play a part in this observance prompts in me an inordinate pride while I am humble before the responsibilities of my task. The ranks are growing thin of those who had the good fortune to come under the personal influence of Professor Howe, but the number who continue to benefit from his legacy of technical wisdom con-stantly increases. I am among the latter. One has only to read his works to appreciate his unusual ability to take data and observations from many sources and give them a clear and comprehensive

Jan 1, 1960

By Herbert Clark Hoover, Lou Henry Hoover

PREVIOUSLY I have dealt with the methods of separating silver from copper. There now remains the portion which treats of solidified juices ; and whereas they might be considered as alien to things metallic, nevertheless, the reasons why they should not be separated from it I have explained in the second book. Solidified juices are either prepared from waters in which nature or art has infused them, or they are produced from the liquid juices themselves, or from stony minerals. Sagacious people, at first observing the waters of some lakes to be naturally full of juices which thickened on being dried up by the heat of the sun and thus became solidified juices, drew such waters into other places, or diverted them into low-lying places adjoining hills, so that the heat of the sun should likewise cause them to condense. Subsequently, because they observed that in this wise the solidified juices could be made only in summer, and then not in all countries, but only in hot and temperate regions in which it seldom rains in summer, they boiled them in vessels over a fire until they began to thicken. In this manner, at all times of the year, in all regions, even the coldest, solidified juices could be obtained from solutions of such juices, whether made by nature or by art. Afterward, when they saw juices drip from some roasted stones, they cooked these in pots in order to obtain solidified juices in this wise also. It is worth the trouble to learn the pro- portions and the methods by which these are made. I will therefore began with salt, which is made from water either salty by nature, or by the labour of man, or else from a solution of salt, or from lye, likewise salty. Water which is salty by nature, is condensed and converted into salt in salt-pits by the heat of the sun, or else by the heat of a fire in pans or pts or trenches. That which is made salty by art, is also condensed by fire and changed into salt. There should be as many salt-pits dug as the circumstance of the place permits, but there should not be more made than can be used, although we ought to make as much salt as we can sell. The depth of salt-pits should be moderate, and the bottom should be level, so that all the water is evaporated from the salt by the heat of the sun. The salt-pits should first be encrusted with salt, so that they may not suck up the water. The method of pouring or leading sea-water into salt-pits is very old, and is still in use in many places. The method is not less old, but less common, to pour well-water into salt-pits, as was done in Babylon, for which Pliny is the authority, and in Cappadocia, where they used not only well-water, but also spring-water. In all hot countries salt-water and lake-water are conducted, poured or carried into salt-pits, and, being dried by the heat of the sun, are converted into

Jan 1, 1950

By Desio S. Oddone, Mark C. Malamphy, Irnack C. Do Amaral

Most igneous rocks, and particularly those of the basic type, contain relatively high percentages of magnetite and other iron oxides, which give them moderately high magnetic susceptibilities and make them responsible for an important percentage of the magnetic anomalies observed during the course of geophysical surveys by the magnetic method. The irregular form and high susceptibility of the igneous rocks make them readily polarizable and the position and strength of the magnetic poles formed are not always explicable by theoretical calculations of anomalies due to certain assumed forms in the normal magnetic field of the area under study. During the last four years our field work has permitted us to make detailed observations of anomalies due to igneous rocks in all the states of south Brazil. The form and position of the igneous rock at some places were fairly accurately known, which made it possible to calculate theoretical anomalies and compare them with the observed data. Some of the data we obtained have been published and additional cases are now awaiting publication. In this paper, we will present a few specific cases where the geology is moderately well known and which we believe to be of considerable value as representing typical magnetic anomalies in the south magnetic hemisphere, where the inclination of the magnetic field is very low. Although the vertical intensity is negative in the Southern Hemisphere, we have adopted the convention of plotting increase in intensity (negative) as a positive anomaly; i.e., above the x axis. This convention facilitates comparison with anomalies in the north.

Jan 1, 1940

By Irnack C. Do Amaral, Mark C. Malamphy, Desio S. Oddone

Most igneous rocks, and particularly those of the basic type, contain relatively high percentages of magnetite and other iron oxides, which give them moderately high magnetic susceptibilities and make them responsible for an important percentage of the magnetic anomalies observed during the course of geophysical surveys by the magnetic method. The irregular form and high susceptibility of the igneous rocks make them readily polarizable and the position and strength of the magnetic poles formed are not always explicable by theoretical calculations of anomalies due to certain assumed forms in the normal magnetic field of the area under study. During the last four years our field work has permitted us to make detailed observations of anomalies due to igneous rocks in all the states of south Brazil. The form and position of the igneous rock at some places were fairly accurately known, which made it possible to calculate theoretical anomalies and compare them with the observed data. Some of the data we obtained have been published and additional cases are now awaiting publication. In this paper, we will present a few specific cases where the geology is moderately well known and which we believe to be of considerable value as representing typical magnetic anomalies in the south magnetic hemisphere, where the inclination of the magnetic field is very low. Although the vertical intensity is negative in the Southern Hemisphere, we have adopted the convention of plotting increase in intensity (negative) as a positive anomaly; i.e., above the x axis. This convention facilitates comparison with anomalies in the north.

Jan 1, 1940

By James Hance

INTRODUCTION SEVERAL years ago the writer was connected with the Mint and Assay Service of the Federal Government as Assistant Assayer at the-Salt Lake Assay Office. At that time cyanide bars formed approximately half of the bullion purchased by that office. Disagreement in valuation between the producer and the office was not infrequent and to a lesser extent between the Assay Office and the Mint, this latter issue being soon obviated, however, by adopting uniform methods of sampling the bars. A nice problem seemed to offer itself for research and the writer began a series of experiments which were soon terminated, however, by his going into other work, and which he regrets have not since been completed. The results attained may suggest lines of approach to this problem and are, therefore, offered in this article. Frederick P. Dewey, Assayer of the Mint Service, U. S. Treasury, has had abundant opportunity to study this phase of metallurgy, and has published several articles relative thereto.1 In the last article cited Dewey quotes analyses of cyanide bullion similar in content to that with which the writer worked, and which show some of the variations met with. In the discussion of these papers,2 comparison has been made in terms of copper bullion, but to the writer this seems of questionable value. Copper bullion may resemble silver bullion, but its similarity to, gold bullion with little or no silver content is another thing. The freezing-point diagram of Roozeboom, reproduced on page 881 of the discussion cited, is for the gold-silver series as stated. The original problem under discussion, however, is not this alloy but gold with base metals other than copper. As for the statement that the corners are the worst places or

Jan 2, 1916

EUGENE WESLEY SHAW,* Washington, D. C. (written discussion ?).-Studies of the probable future production of oil wells and fields-particularly those in the nature of the recent work by Lewis and Beal, having the object of increasing the percentage of recovery-rank, in both practical and theoretic value, very high, if indeed they do not outrank all other petroleum investigations except structural surveys. Even such surveys, although saving untold millions that might have been spent in prospecting unpromising territory, may have less ultimate value than generally supposed, for it may perhaps be argued that much if not most of the condemned territory will sooner or later be tested-some is already productive-and the most that can be rightly claimed is the recovery of cream first; also that the consumption of the richest portions first cannot be extenuated, as it might with some resources, on the ground that if the best is not taken now it will deteriorate.

Jan 5, 1918

By E. B. Spice

Although much may be learned about the economics of cold weather operations by studying successful mining ventures in southern and central Canada, it is the purpose of this article to extend the study by considering only permafrost areas. Geographically this means most of the country north of the 60th parallel. In this area, at the present time, only five Canadian companies are carrying on routine and successful mining operations on a year-round basis. However, there have been some score of unsuccessful ventures, and a number of properties in the development stage show promise of being producers. Problems of cold weather are worthy of study. It may be pointed out that successful mines in this area face problems of isolation and costly transportation as well as cold weather. To reach valid conclusions, consider the development of a mythical mineral deposit located on the 65th parallel in the heart of the barren lands; problems of isolation and transportation will be ignored.

Jul 1, 1956

By R. L. Sandefur

Professor Kim's excellent review article1 on ultimate pit planning contains a statement of the apparently widely held but incorrect belief that "kriging provides information on the confidence limits around the estimate which no other extension technique is capable of supplying." If a geostatistical approach is valid, there are several good reasons for using kriging but uniquely provided confidence limits is not among them. If kriging is possible, then confidence limits can be calculated for any other linear estimate. Kriging is the procedure which finds the weighing coefficients which minimize the estimation variance [ ] is the variance of blocks like the one being estimated. wi is the covariance of the estimated block and the i-th sample. oij is the covariance of the i-th sample and the j-th sample. Ai is the weighing coefficient for the i-th sample. N is the number of samples. The formula for estimation variance can also be used to calculate confidence limits on blocks estimated by any linear combination of sample grades including: 1) Polygons a. Hole nearest block centroid is assigned weight 1. All other holes are assigned weight 0. b. Polygonal area weighing. The samples are assigned weights directly proportional to their polygonal areas of influence within the block. The weights sum to 1. 2) Inverse distance weighing. The samples are assigned weights directly proportional to the reciprocal of their distance to some power from the block centriod. The weights sum to 1. Often only holes nearer than a certain distance and/or the nearest hole in each octant is considered. If there is an antisotropy to the ore body, an elliptical transformation often gives more accurate results. The most popular inverse distance weighing function is inverse squared distances (IDS). 3) Simple average. All samples within a certain distance are assigned the same weights which sum to 1. As an example of the applicability of the above formula to any linear estimate an internal verification on copper grade of 665 blast holes on the 1040 bench at Utah's Island Copper mine is presented. Internal verification is simple and applicable to non-linear estimates as well. Any sample (drill hole, bulk, trench, or chip) is dropped out, the value of the dropped sample estimated and compared with the actual value. If this is done for all samples, a measure of confidence limits is obtained. Internal verification is used in Cominco's MEPS system4 and in the BLUEPACK system.5 Comparison of block values against estimates697 is not dissimilar to internal verification. Results of the internal verification are presented below:

Jan 1, 1980

By Johann F. Kerl

Autogenous batch grinding tests were performed in laboratory-scale tumbling mills with magnetite, limestone, and sandstone pebbles. The influence of pebble size, feed size, mill speed and loading, and grinding time on the fineness of grinding was investigated. Comparisons were made with the results from ball mill grinding experiments.

Jan 1, 1972

By Alexander B. Morris

Studies such as the investigations into the solubility of gases in crude oil under various conditions, which have been carried on during the past three or four years, are very interesting from an academic point of view, but this consideration alone is hardly sufficient to warrant the large contributions from the industry necessary to maintain them. Some definite benefit to the industry as a whole should be forthcoming. The purpose of this paper is to direct the attention of company engineers, and company executives, to some of the ways in which the information gained from these studies can be made directly profitable. This work has two principal economic aspects. One affects the investment budget, and through it the financial requirements of the companies. The other affects operations, and through this course is reflected in current earnings. It will be shown that, as a direct result of the investigations into gas solubility, undertaken in the recent past by various investigators, it is now possible: 1. To determine more accurately the amount of reservoir oil originally present. 2. To obtain closer control on operating conditions, to effect more economical recovery. 3. To predict earlier and more dependably when and how much surface lifting equipment will be needed. 4. To reduce, or entirely avoid the very large investment in gasoline recovery equipment now frequently found necessary. 5. To control the gravity of the pipe-line oil so as to secure the greatest possible revenue from the products of the well. 6. To effect the recovery of a large amount of gasoline now wasted while the practicability of a gasoline recovery system is being decided. 7. To plan operations, by comparison with the history of old properties operated without this new information, so as to avoid the mistakes of ignorance made in the past. These points will be discussed in the following pages, though not necessarily in the order stated. There is so much overlapping of the points themselves, and of the data from which they have been drawn as conclusions, that to treat them in any particular order would require

Jan 1, 1935

By M. L. Requa

EVERY forward step in civilization brings with it an increase in population and increasing demand for raw materials. Modern civilization, because of its industrial development, depends more and more for its well-being on ample supplies of raw materials; the higher the type of that civilization, the greater its dependence. No fact is more obvious than that the raw materials should be put to use with greatest prudence and efficiency. National life is not a matter of a decade or a century. Conservation is no longer a matter for political discussion; it is a vital element in the future welfare of all nations. Unfortunately, to the minds of many, conservation means the locking up of natural resources, their arbitrary withdrawal, bringing about, in short, a condition of industrial stagnation. This has occurred in past centuries through misdirected governmental effort. Two eminent engineers have variously defined conservation as follows:

Jan 1, 1925

[A Aamodt, H. C., A55 C Sales, Great Lakes Carbon Corp., 18 E. 48th St., New York, N.Y. Aamot, Olav Crone, M29 2126 M4, Galveston, Texas Aaronson, Hubert I., M47 E Prin Res Engr, Ford Motor Co., Met. Dept., Sci. Lab., Engrg. Staff, P. O. Box 2053, Dearborn, Mich. Aase, Glenn D., M54 D Prin Engr, Air Pollution Control Dist., 1480 Mission St., San Francisco 3, Calif. Abbett, W. A., Jr., M56 8629 Beverly St., Duluth 8, Minn. Abbey, Robert G., M56 138 Dartmouth Rd., Bala Cynwyd, Pa. Abbott, A. G., Jr., J52 E Test, Dev Engr, Chrysler Corp. Missile Div., P. O. Box 2628, Detroit 31, Mich. Abbott, Mark L., A58 Rep, General Refractories Co., 208 S. LaSalle St., Chicago, Ill. Abbott, W. K., J58 E Dev Met, Int'l Nickel Co., Inc., 67 Wall St., New York 5, N.Y.]

Jan 1, 1961

By D. I. Bardos, A. M. Bardos, Paul A. Beck

The approximate effective silicon radii in ternary Laves phase alloys with transition elements and silicon were found to range between 1.16 and 1.21A, i.e., considerably smaller than the atomic radius calculated for elemental silicon. The atomic radii were found to increase with the size of the transition element atoms in the structure. It has been noted by Aronsson1 that silicon in solid solution in iron, cobalt, and nickel has an effective CN 12 atomic radius of approximately 1.20Å, a value very much smaller than the CN 12 radius of 1.34Å derived from the interatomic distances in elemental silicon.7 The unusually short metal-silicon interatomic distances in transition element monosilicides and disilicides have been also pointed out by various investigators.1 A similar tendency was observed by Nevitt in Cr3O type silicides.2 Recent work on Laves phases in ternary systems of silicon with transition elements4"8 suggested that extensive Laves phase fields may occur in such systems.8 It has been pointed out by Laves7 that the MgCu2 and MgZn2 type structures lend themselves particularly well for the determination of the effective radii of the component atoms. In these AB2 phases the B atoms are arranged in close packed straight lines, and their distances are related in a simple manner to the lattice parameters.8 The present work was undertaken in order to find out whether or not the B transition element in such AB2 Laves phases can be replaced to an appreciable extent by silicon. In cases where extensive substitution proves to be possible, the "average atomic radius for the B site" at various silicon contents was to be determined, and the effective atomic radius of silicon calculated by extrapolation to complete replacement of the B component by silicon. The following ternary systems were studied: Ti-Mn-Si, Ti-Fe-Si, V-Co-Si, V-Ni-Si, Nb-Fe-Si, Nb-Co-Si, Ta-Fe-Si, Ta-Co-Si, and Mo-Fe-Si. In all of these alloy systems, the Laves phase solid solutions were found to extend over a considerable range of silicon content. As previously reported,4"8 in the V-Co-Si, V-Ni-Si, and Mo-Fe-Si ternary systems Laves phases do occur, even though there are no corresponding binary Laves phases. In stabilizing the Laves phase, silicon acts as if it were decreasing the effective electron concentration of the alloy.8 A more detailed study of the boundaries of the Laves phases in the V-Co-Si and V-Ni-Si systems has been made and will be published elsewhere. In both cases, the elongated Laves phase fields extend parallel to the B-Si side of the composition triangle, clearly showing that silicon is substituting for cobalt, respectively, nickel over a wide range of compositions. The binary Laves phases NbCo2 and TaCo2 have the cubic MgCu2-type structure. It was found that, in both ternary systems with silicon, again the MgZn2-type hexagonal Laves phase is stabilized and that this phase extends to high-silicon contents. In each ternary system at least three Laves phase alloys of the composition A(B1_xSix)2 were used, x here denoting the fractional substitution of the B-transition element atoms by silicon. The alloys, listed in Table I, were prepared by arc melting in argon. Each specimen was water quenched after a homogenizing anneal of 3 days at 110(FC, except for the Mo-Fe-Si alloys, which were annealed at 1200°C. Metallographic examination showed that most of the homogenized alloys consisted of a single phase, although some had minor amounts of a second phase, as shown in Table I. X-ray diffraction patterns were prepared using an asymmetrical focusing camera of large resolution and Fe Ka radiation. The patterns were indexed, and the lattice parameters of the hexagonal Laves phases were determined from the available diffraction lines of highest indices: (213), (205), and (313). The lat-

Jan 1, 1963

By H. I. Aaronson, H. A. Domian, A. D. Brailsford

A current study of the growth kinetics of k (hcp) plates in a Cu-Si (fcc)' has generated a requirement for data 02 the chemical interdiffusion coefficient in a (termed D,) as a function of temperature at the composition of the a/a + k pJase boundary. Rhines and Mehl 2 have determined D, as a function of composition at lower silicon contents by making Matano analyses of concentration-penetration curves. However, the accelerating increase in B, which they demonstrated as the phase boundary composition is approached at constant temperature and the rapidly diminishing accuracy of this analysis as the limiting compositions of a diffusion couple are approached (the silicon-rich component of their couples contained appreciably less silicon than is permitted by the solubility limit) indicate that the required information cannot be safely obtained by extrapolation of their data. Although the quite different method employed in this study is not exact, it will be shown that the approximations made are not serious ones, particularly from the viewpoint of the prgcipal application anticipated for these data. D, was determined from the migration kinetics of the a :k boundaries formed in sandwich-type diffusion couples produced by welding a block of high-purity copper to opposite sides of a cube (* in. on edge) of homogenized high-purity Cu-5.82 wt pct Si alloy. The alloy is pure k in the temperature range employed. The surfaces of the couple components which were normal to the diffusion direction were machined accurately flat and parallel, lightly polished, and carefully cleaned. Welding was then accomplished by means of the vacuum-encapsulated pressure jig technique previously employed.3 Welding was always conducted at the intended diffusion temperature; thus the welding anneal also served as the first diffusion anneal. Subsequent diffusion anneals were performed in evacuated Vycor capsules. Following the welding anneal, one of the surfaces parallel to the diffusion direction was machined, ground, and polished flat; additional material was removed from this surface after each diffusion anneal in order to avoid any effects of composition changes. After etching,4 the average distance between a : k boundaries was measured by means of a traveling microscope with an accuracy (per measurement) of better than 1 p. Satisfactory results were obtained at four temperatures in the range 775° to 655°C; attempts to obtain data at two lower temperatures were unsuccessful, evidently as the result of the interference of surface contamination during the welding process.

Jan 1, 1969

(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 Sept. 10 to Oct. 10, 1915: George H. Blakemore, Sydney, N. S. W. W. B. A. Dingwall, San Antonio, Tex.. H. Haege, Sydney, N. S. W. R. H. Jeffrey, London, England. C. A. Filteau, New York, N. Y. H. S. Emlaw, Spring Lake, Mich. Myron R. Walker, Cerro de Pasco, Peru. Y. T. Woo,' Tientsin, China. William R. Grunow, Morenci, Ariz. A. L. DeDeken, LouVain, Belgium. E. DeGolyer, Norman, Okla. K. P. Swensen, Tokyo, Japan. William W. Elmer, Tuttletown, Cal. Charles Enzian, Wilkes-Barre, Pa. Huntington Adams, Iquique, Chile. C. F. Schnepp, Cobalt, Ont., Canada. W. Ray Cox, for several years Mineral Inspector of the General Land Office at Portland, Ore., has been appointed Professor of Mining and Metallurgy in the School of Mines, Oregon Agricultural College, Corvallis, Ore.

Jan 11, 1915

By Zay Jeffries

A. G. WORTHING, Nela Park, Cleveland, Ohio (communication to the Secretary*).-The paper by Mr. Jeffries is very interesting. He is to be commended for his pioneer work in the study of equilibrium systems at the very high temperatures which one obtains with tungsten and molybdenum. There is one statement, however, to which I must take exception. On page 1227, a statement is made which would seem to indicate that the Nela Research Laboratory joined Dr. Langmuir in the recommendation of 3,300°C. as the most probable melting point of tungsten. This is not the case. In. the paper referred to by Mr. Jeffries, I have given 3,630°K. or 3,357°C. as the melting-point temperature for tungsten. Confirming observations by other workers in our laboratory justify the belief that this latter value is correct to within a small part of the discrepancy between the two values quoted.

Jan 12, 1916

By A. H. Kline, E. B. Zimmer, Zay Jeffries

It is well known that many properties of a given metal vary with the size of grain or cell. For most industrial purposes, where high ultimate strength and high elastic limit are desired, the manufacturer tries to produce a fine-grained structure. For some purposes, for example in transformer iron, a coarse-grained structure is desirable. The terms fine-grained and coarse-grained are used only in a relative sense. For example, a fine-grained cast copper might have grains 100 times larger than coarse-grained high-speed steel. Similarly, a finegrained steel rail might have grains or cells 100 times larger than coarsegrained wire, which was made of steel from the same heat. In some metals, the change in grain size is more appreciable khan the changes in any of the properties determined by the tensile test. Furthermore, in metals which have been annealed or subjected to high temperatures, grain size may prove to be a better indication of the life of the metal in use than the tensile test. One of the authors was able to supplant the tensile test with grain-size determinations in the control of metal for a specific use, the latter determination being more indicative of the life of the metal part than the tensile test. A grain-size determination with a tensile stest is, of course, more valuable than either singly. At present there is a decided dearth of data on actual grain-size determinations in metals, and consequently a corresponding lack of ability to interpret the determinations after they are made. It would be desirable to have correlation made between grain size and properties of metals, comparing thousands of determinations. In this way, grain-size determinations might be interpreted in much the same manner that tensile tests are now. Several Methods of Measuring Grain Size One of the chief reasons why more grain-size measurements have not been made is the excessive work involved in making a determination.

Jan 1, 1916