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By J. M. Roberts, D. M. Barnett

The activation energy required to break a pinned dislocation line away from its condensed atmosphere of impurity atoms is calculated as a .function of applied stress, without neglecting line tension. Reasows are presented for not assuming the effect of line tension to be negligible when considering the problem of freeing a small segment of dislocation from an impurity atmosphere. The dislocation is considered to he pinned at each atomic size along its length and the pinning points are assumzed immobile. The development is a refinement of the origznal cottrell-bilby1 theory. The solution is compared to recent approximations developed by cottrell3 and Haasen5 in which line tension con- IN 1949 Cottrell and bilby1 considered the problem of determining the force required to pull a dislocation away from its condensed atmosphere of impurity atoms. They also examined the effect of thermal fluctuations on this force. The dislocation line was pictured as bowing out in a triangular loop under the action of an applied stress, and the activation energy necessary to free the dislocation from its atmosphere was calculated as a function of stress, line energy, and dislocation-solute atom interaction. siderations were neglected. A qualitative explanation of the yielding process in terms of the activation of Frank-Read sources is presented, but the lack of a realistic solution to the dynamic dislocation problem involved prevents an extension of the model at present. A self-consistent correlation between the present calculations and experimental data for delay time associated with yielding and the temperature dependence of the upper yield stress was made. Favorable agreement was noted. It is concluded that extension of the original Cottrell-~ilby' theory which includes line tension effects can just as well describe the yielding process as other approximations3,5 which neglect line tension. Cottrell and Bilby found the form of the activation energy vs stress curves to be almost independent of the line energy and the interaction energy (i.e., these parameters only affected the activation energy U by a scale factor). A check of the theory was accomplished by comparison with the experimental data of McAdam and Mebs2 for the lower yield stress as a function of temperature. cottrell,3 in 1957, attempted to obtain a simple closed-form solution for the activation energy as a function of stress by linearizing the quartic equation relating displacement of the dislocation line and applied stress. It was argued that since the contribution to the line energy/atomic plane of a dislocation is made by the long-range stress field of the dislocation through a term of the type (Gb3/2p)ln A/ro, where

Jan 1, 1963

By Claudio Guarnaschelli

Alteration of the electronic distribution of mineral surfaces by light irradiation has been used to modify the adsorption characteristics of flotation reagents. Energy of a few electron volts is suficient to cause the necessary transitions that either enhance or retard the adsorption phenomenon. The adsorption characteristics of potassium ethyl xanthate on galena and marmatite are presented as functions of the energy of illumination, type of semiconductor, and surface oxidation. In dilute solutions, the adsorption differences are readily detected by controlled kinetic measurements. The correlation between the electronic distribution and the adsorption and desorption phenomena at the solid surface is gaining more attention and acceptance. These interrelations have found a practical application in mineral processing since all of the sulfide minerals display semiconducting properties. By varying the ratio of free electron to electron vacancies, the separation of ilmenite from rutilel and zircon from pyrochlore" has been executed successfully. Plaksin et al.' indicate three possible ways of utilizing the semiconductor properties of a mineral. The first one involves the control of the oxidation-reduction potential of the liquid phase, the second one consists of allowing selected additives to diffuse through the mineral surface, while the third one entails a change in the adsorption and chemical activity of minerals by irradiating their surface. The aim of the present work is to consider the effect of irradiation on the adsorption-desorption characteristics of natural minerals. Since the effect of irradiation is to change the electronic distribution at the surface:

Jan 1, 1971

By Harold Roast

THE object of this investigation was to compare the arsenical antimony-lead alloy with some of the regular bearing-metal alloys. With this end in view, the following tests were made: 1. Chemical analyses to show the composition. 2. Thermal analyses. 3. Macroscopic examination of fractures. 4. Microscopic examination. 5. Tensile tests. 6. Crushing tests. 7. Scleroscope tests. 8. Brinell tests, at temperatures from 80° to 400° F. Tests 3 to 8 were conducted on both sand-cast and chill-cast specimens. For the purposes of this paper the alloys have been numbered from 1 to 6; their composition is as follows: LEAD, ANTIMONY, TIN, COPPER, ARSENIC, NUMBER PER CENT. PER CENT. PER CENT. PER CENT. PER CENT. 1 82.64 12.95 4.40 0.01 none 2 27.54 9.94 59.87 2.65 none 3 77.65 20.75 none 0.13 1.47 4 82.95 16.85 none 0.20 none 5 83.78 15.35 none 0.05 0.82 6 0.15 7.87 84.13 7.85 none The analysis, in the case of the antimony, was made by solution in sulfuric acid and titrated with permanganate. For tin, the ferric-chloride method was used; for copper, the alkaline separations, and the thiocyanate methods; for arsenic, volatilization of arsenic and titration with iodine. The lead, with the exception of alloy 6, was taken by difference.

Jan 2, 1922

By W. B. Finkeldey, C. H. Mathewson, C. S. Trewin

This paper was prepared upon request as a contribution to a symposium covering the manufacture, properties, and uses of the important non-ferraus metals. In approaching a subject as broad as this, there is a natural desire to build up a comprehensive and finished production which shall constitute a dependable source of information on all questions properly belonging to this branch of metal technology. There are, however, a number of circumstances, apart from the mere routine of labor and thought involved, which operate rather effectively against the possibility of completing such .an ambitious program at the present time. First of all, as far as any public record of results is concerned, the commercial rolling, drawing, and forming of zinc with relation to changes of structure and properties—and this we consider to constitute the clement~ of metal technology—might as well be an unpractised art. We have never seen a published photomicrograph showing the structural characteristics of either hard or soft sheet or strip, although the structure of castings has been frequently described, and other coarse-grained structures resulting from hard-hammering and annealing have been reproduced. Thus, an author in this field must proceed to his task without much assistance from the literature, and the outcome can represent only a personal estimate of principles, facts, or findings, and not a summary or survey of progress in the entire field as determined by varied experience, practice, and settled opinion.

Jan 1, 1921

By G. Thodos, R. B. Grieves

A method has been developed for the accurate calculation of the cricondentberm and cricondenbar temperatures of multicomponent hydrocarbon mixtures of known composition. The mixtures may contain any number of components including paraffins and isoparaffins, olefins, acetylenes, naphthenes and aromatics. This approach is based upon the mole fraction of the low-boiling component in the mixture and graphically presents the ratios of the cricondentherm and cricondenbar temperatures to the pseudocritical temperature as {unctions of a boiling-point parameter. The only requirements are the critical temperature, normal boiling point and the approximate vapor pressure behavior of each component. For mixtures of more than two constituents a stepwise calculation procedure is necessary where the pseudocritical temperature is based upon the critical temperature of the pure low-boiling component and upon the actual cricondentherm or cricondenbar temperature of the mixture of all the remaining higher-boiling components. From an analysis of 22 binary systems (123 compositionsl, the average deviation of calculated cricondentherm temperatures from reported values is 0.87 per cent, based on degrees Rankine; and for 10 multicomponent mixtures containing from three to six components, the average deviation is 0.98 per cent. From an analysis of 18 binary systems (104 compositions) the average deviation of calculated cricondenbar temperatures from reported values is 0. 79 per cent; and for 15 multicomponent mixtures, 1.47 per cent. Equations, derived from the graphical relationships, are presented which enable rapid calculations for both binary and multicomponent systems. INTRODUCTION With the increasing tendency towards the use of high pressure processes, the need for an accurate method of calculation of the properties of a multicomponent hydrocarbon mixture in the critical region is becoming more essential. Critical region phase relations are also significant in gas condensate reservoirs, for which a knowledge of the fluid phase boundaries and regions of retrograde condensation make it possible to evaluate optimum operating conditions. The possibility of liquefaction in the underground structure may be established, and information on the feasibility of the use of repressurizing may be determined. A typical phase diagram for a multicomponent hydrocarbon mixture is presented as Fig. 1. This figure also shows the regions of retrograde behavior encountered by following lines AB and AC. If accurate methods of calculating the temperatures and pressures at the critical, cricondentherm (maximum temperature) and cricondenbar (maximum pressure) points of multicomponent hydrocarbon mixtures of known composition were available, it would be possible to estimate closely the entire phase diagram of any mixture. Several methods have been presented in the literature for the estimation of the critical temperatures and pressures of multicomponent mixtures containing all types of hydrocarbons and including the fixed gases.4-8,21 Considering the cricondentherm and cricondenbar points, the work is more limited. Etter and Kay5 have developed rather complex equations for

Colorado Geological Survey, Boulder, Colo. R D George, State Geologist. The following publications of the Survey may be obtained as long as the supply lasts, at the indicated price. Bulletin 3, Geology and ore deposits of the Alma district (1910), 25 cents, 4, Geology and ore deposits of the Monarch and Tomichi districts, Chaffee and Gunnison counties (1912), can be had together with 5, pt 1, Geology of the Rabbit Ears region and pt. 2, Permian or " Permo-Carbonif erous " of the Eastern Foothills of the Rocky Mountains in Colorado, for 50 cents; 7, Bibliography of Colorado geology and mining literature (1914), 25 cents, 8, The clays of eastern Colorado (1915), 25 cents, 9, Geology and ore deposits of Bonanza district (1915), 25 cents, 10, Geology and ore deposits of Gold Brick district (1916), 25 cents, 13, Geology and ore deposits of the Platoro-Summitville district (1917), 25 cents; 14, Molybdenum deposits of Colorado (1919), 25 cents; 15, Manganese deposits of Colorado (1919), 25 cents (14 and 15 in one volume, 35 cents); 17, Twin Lakes district (1921), 25 cents. Bulletin 18, Fluorspar deposits of Colorado (1920), 25 cents, 21, The geology of the Ward region, Boulder County (1921), 50 cents, 22, Mineral deposits of the Western Slope (1921), 25 cents, 24, Some anticlines of western Colorado (1924), 50 cents; 27 (in three parts) pt 3, Geology of parts of Las Animas, Otero and

Jan 1, 1933

By J. M. Karpinski

The need for standard test methods in the minerals beneficiation industry is growing with the increasing complexity of our processes and the more stringent requirements imposed on the quality and uniformity of our products. Although solutions of our problems have never been easy, they will become increasingly difficult to achieve unless we can develop a reliable and reproducible set of test methods. Historically speaking, our need was greatest for methods of chemical analysis. As these methods developed, they improved our ability to determine the grade of ore and measure the effect of our beneficiation attempts. The entire concept of grade and recovery is only as old as chemical analysis. Then came physical measurements. Each new concept in minerals beneficiation was related to certain properties and required corresponding test methods: specific density for jigging, magnetic susceptibility for magnetic separation, and tumbler strength for pellets. And associated with each process was the need for size determination. Size measurement is probably the first physical test ever conceived, and yet we are still improving on it. Dry sieving was quite acceptable for direct-shipping ores, but we had to go to wet sieving to control pelletizing and flotation. Subsieve analyzers have extended our routine measurements to the subsieve sizes, hut not below a few microns. As we all know, the solution of slimes- beneficiation and pollution-abatement problems is hampered by the lack of reliable and reproducible test methods in the fine-particle size range.

Jan 1, 1971

The resolution drafted by J. W. Richards, J. V. N. Dorr, and Allen H. Rogers on the death of J. E. Johnson, Jr., and adopted by the Board of Directors, is as follows: "The Boards of Directors of the American Institute of Mining and Metallurgical Engineers wishes to place on record its great personal loss in the sudden death of Mr. J. E. Johnson, Jr., our fellow Director of the activities of the Institute, a member our Executive Committee, Chairman of the Institute's Committee on Admissions, and Vice-chairman of its Iron and Steel Committee. "A mere recital of these positions of trust and responsibility, which he filled with conscientious efficiency and marked ability, shows how greatly the Institute has lost by his death. No one else of the Institute's officers could have been so illy spared. We, his colleagues, take up his tasks with a sense of our inability to discharge them as well as he, and this with a doubled sense of our loss. "Others have written and spoken of the blow which his death has been to the furtherance of the metallurgy of iron and steel. His pre-eminence in this line is one of the facts of which the Institute is justly proud. Here his personality, originality, courageousness in advocating new principles, clearness of writing and forcible presentation of facts, are irreplaceable. His two great treatises on the blast furnace are his literary and scientific memorial.

Jan 7, 1919

THE Institute assembled on Tuesday evening, in the building of the University of Pennsylvania. In the absence of President Thomas, Vice-President Raymond occupied the chair. The Institute was welcomed in an eloquent and thoughtful address by Prof. J. P. Lesley, to which Mr. Raymond responded. Invitations were announced from the proprietors of Sellers' Tool Works, Whitney's Car-wheel Works, the Baldwin Locomotive Works, Lewis & Brothers' White Lead Works, the Southwark Foundry, Harrison's Boiler Factory, the University of Pennsylvania, and the Academy of Natural Sciences. The following gentlemen, being duly recommended by the Council as members and associates, were unanimously elected : Alexander, John S., . . . . . Philadelphia, Pa. Biddle, E. R., . New Pork. Britton, J.. Blodget, . . . . . Philadelphia, Pa. Brooks, Maj. T. B., . . . . . Marquette, Mich. Brown, D. P., . Pottsville, Pa. Canfield, Edw., . . . . . . Dover, N. J. Cogswell, W. B., . .Franklin IronW'ks, N. Y. Cornwall, Prof. H. B., . .New York. Edwards, Daniel, . . . . . . Danville, Pa. Estabrook, Juhn D., . . . . . Philadelphia, Pa. Firmstone, William, . . . . . Easton, Pa. Fritz, John, . . . . . . . Bethlehem, Pa. Gignoux, Charles, . . . . . . New Pork. Grant, E. M., . . . . . . . Tuskegee, Ala. Humphreys, A. W., . New York. Ingham, W. A,, . . . . . . Philadelphia, Pa. Keyes, W. S., . . . . . . Eureka, Nev. Kimball, Dr. J. P., . New Pork. Law, Charles, . Pittston, Pa. Neilson, W. O., . . . . . . Philadelphia, Pa. Newberry, Prof. J. S., . . . . . New York. Pearse, John B., . .Steel Works P. O., Pa. Ricketts, P. De P., . . . . . New Pork. Scranton, Col. Charles, . . . . . Ox ford, N. J. Sontag, Hugo, . . . . . . Cologne, Prussia. Steele, Thomas C., . .Summit, Pa. Wharton, Joseph, . . . . . . Philadelphia, Pa.

By Charles Fairhust

Although the term 'rock mechanics' started to become popular about the time of the First U.S. Rook Mechanics Symposium in 1956, study of the mechanical behavior of rock certainly pre-dates this event. Bucky, Phillips, Von Karman, Fayol, Galileo...the list of significant contributors can be traced back over centuries, - not surprising for the oldest structural material used by man. Started with a strong mining orientation by the Colorado School of Mines, University of Minnesota, and Pennsylvania State University, joined soon after by Missouri School of Mines and the University of Texas, the Annual U.S. Symposium on Bock Mechanics has evolved into the main U.S. form for discussion of all aspects of rock mechanics, basic and applied - tectonophysics to comminution; near-surf ace foundations to deep mine support design. Although dominantly a U.S. event the annual symposium has benefitted from regular and important contributions from abroad. It would be presumptuous to attempt a comprehensive statement of significant developments over the 25-year history of the U.S. Bock Mechanics Symposium. This anniversary address will attempt instead to present a personal view of developments that appear to be of broad general significance and that may indicate directions for the future. Among the developments to be discussed in the address arc the following: - Energy Basis of Book Fracture Early rock mechanics investigators often overlooked the important distinction between a failure initiation stress and structural collapse. Although essentially synonymous in the

Jan 1, 1984

February 20th, 1872. THE Institute assembled on Tuesday evening, in the building of the University of Pennsylvania. In the absence of President Thomas, Vice-President Raymond occupied the chair. The Institute was welcomed in an eloquent and thoughtful address by Prof. J. P. Lesley, to which Mr. Raymond responded. Invitations were announced from the proprietors of Sellers' Tool Works, Whitney's Car-wheel Works, the Baldwin Locomotive Works, Lewis & Brothers' White Lead Works, the Southwark Foundry, Harrison's Boiler Factory, the University of Pennsylvania, and the Academy of Natural Sciences. The following gentlemen, being duly recommended by the Council as members and associates, were unanimously elected Alexander, John S., - Philadelphia, Pa. Biddle, E. R., - New York. Britton, J.. Blodget, - Philadelphia, Pa. Brooks, Maj. T. B., - Marquette, Mich. Brown, D. P., - Pottsville, Pa. Canfield, Edw., - Dover, N. J. Cogswell, W. B., - Franklin IronW'ks, N.Y. Cornwall, Prof. H. B., - New York. Edwards, Daniel, - Danville, Pa. Estabrook, John D., - Philadelphia, Pa. Firmstone, William, - Easton, Pa. Fritz, John, - Bethlehem, Pa. Gignoux, Charles, - New York. Grant, E. M., - Tuskegee, Ala. Humphreys, A. W., - New York. Ingham, W. A., - Philadelphia, Pa. Keyes, W. S., - Eureka, Nev. Kimball, Dr. J. P., - New York. Law, Charles, - Pittston, Pa. Neilson, W. G., - Philadelphia, Pa. Newberry, Prof. J. S., - New York. Pearse, John B, - Steel Works P. O., Pa. Ricketts, P. De P., - New York. Scranton, Col. Charles, - Oxford, N. J. Sontag, Hugo, - Cologne, Prussia. Steele, Thomas C. - Summit, Pa. Wharton, Joseph, - Philadelphia, Pa.

Jan 1, 1873

WHOEVER has occasion to judge tin in its whiteness from the testimony of his eyes alone would surely believe it to be purest silver, or something that comes very near to it in nature. This is even more so when, on handling, it is found to be harder than lead, to which it can be said to have a greater and closer resemblance. But whoever has actual experience with tin knows that none of the other metals is less similar to it than silver. For silver mixes with every metal, as does gold; and they unite together, and the others do likewise; and except for their color they change their natures but little. But this metal tin, wherever it is found, acts like a powerful poison which envenoms and corrupts the others; and it does this not only with large quantities but also with every small amount; indeed just the trace remaining where it has been melted is enough to embrittle silver and gold as well as iron and copper. The greater the quantity of it in these, the greater are its effects. Speculators of natural causes say that this fact arises from its great wateriness, which is very subtle and poorly decocted and almost like that of quicksilver. This wateriness, then, by means of its subtlety which joins itself with metals, imposes itself into that unctuous and viscous material which renders them flexible, and thus deprives them of their toughness

Jan 1, 1942

Geologist or Mining Engineer who has had sufficient experience to make examination of a large area and who can report upon economic value of any minerals found. Work will extend over a period of 2 or more years. Location, India. R-1660. Assistant Superintendent of malleable and gray iron foundry, young man. Must have thorough molding experience, especially on squeezers, knowledge of mixture control and operation of air furnaces, cupolas, and annealing ovens college graduate preferred. R-1727. Engineer thoroughly familiar with distilling, evaporating and drying machinery. Capable of taking charge of entire evaporator department, including engineering and selling. New Jersey. R-155C. Experimental Draftsman familiar with small automatic mechanisms, principally those produced in large quantities by punch-press methods, such as adding machines or typewriters. New York City. R-1566. Patent Draftsman.-At least 2 years' experience on perspective rend-ering of small automatic machinery. New York City. R-1570. Designer.-Familiar with hydraulic work and capable of going ahead with detail and design work without supervision. Pennsylvania. R-1575. Superintendent or Foreman. Knowledge of ceramics, clay products, electric porcelain, tile, factory materials, etc. New York State. Good salary to right man. R-1578. Designer. Experienced in designing mining machinery, including electric hoists. Canada (Quebec). R-1589. Construction and Operating Superintendent. Executive and thor-oughly experienced in the zinc melting industry. Will have charge of construction of plant and its operation. Salary $6000 to start; increase to $8000 later. India. R-1593.

Jan 11, 1919

By W. R. Ingalls

THE MAJOR use of spelter has always been for the coating of iron and steel products, the process of coating being known as "galvanizing" and the products themselves as "galvanized," except for a couple of years during the war, when the consumption for brass making became superior, in the United States at least, owing to military demands. Since 1919, however, the consumption of spelter for galvanizing has regained the premier position, but not with such a long lead over brass making as previous to the war. The last development is ascribable to two main reasons, viz., an increased demand for brass in new industries, especially automobile manufacturing; and a diminished use of spelter per unit of iron and steel galvanized. MAJOR IMPORTANCE OF SUBJECT The last mentioned matter has already been the subject of some discussion and of some literature. The galvanizers have been charged with deliberately thinning their zinc coatings, with the consequence of producing inferior goods and thereby jeopardizing the whole galvanizing business. Zinc producers have been concerned about this, out of consideration of both the less use of zinc per unit of iron and steel and the fear that, the number of units produced may be curtailed. It has been argued, among other things, that the present policy of American galvanizers would impair their ability to compete in foreign markets with British galvanizers, who have been represented as making a superior product.

Jan 7, 1923

By W. A. Vine

WHEN a hole is made in a stressed solid, such as rock pierced by mine openings, equilibrium of the solid is destroyed. To re-establish that equilibrium the stress condition in the rock surrounding the opening becomes rearranged. This rearrangement may or may not develop local stresses in the vicinity of the opening which exceed the elastic strength of the rock. Since stability of the opening depends, therefore, on the strength of the naturally occurring rock surrounding the opening, this rock is an engineering material of construction, and all rock affected by the associated opening or system of open- ings may be considered a structure. The term invert is chosen to describe the formation of the structure —built from the inside, as it were, and a consequence of mining rather than an entity built for a purpose. By definition, an invert structure is formed when openings are made underground and is composed of that material on the solid side of a rock-air interface wherein the stress condition is affected by the associated opening or system of openings. The shape of an invert structure is never clearly defined; the skin of the structure may be mapped, and even described, but the boundary of the structure within the solid rock mass must be arbitrarily set. The name geomechanics is proposed to describe a branch of scientific knowledge which will encompass principles and working hypotheses for behavior and design of invert structures. It is foreseen that study

Jan 1, 1956

By W. W. Tyler, A. C. Wilson, L. B. Nesbitt

INVESTIGATIONS of thermal conductivity and impact strength of the titanium alloy RC-130-B and 316 stainless steel were undertaken because of interest in strong, nonmagnetic, commercially available alloys of low thermal conductivity for use in low temperature experiments. Measurements of electrical resistivity and thermoelectric power were also made for some of the samples studied. The titanium alloy designated as RC-130-B is manufactured by Rem Cru Titanium Inc. It contains 0.14 pct C, 3.99 pct Al, and 4.7 pct Mn. A general discussion of properties of the two phase Ti-4Mn- 4A1 alloys is given by Finlay and Vordahl.' The alloy is machinable and has a yield strength greater than 130,000 lb per sq in. at 0.2 pct offset. The 316 stainless steel sample used for both conductivity and impact strength measurements was obtained from the Allegheny-Ludlum Steel Corp. and is designated as Allegheny metal 18-8M, Type 316, Grade 316. The sample had received 25 pct minimum final cold reduction and had a Brine11 hardness rating of 255. Several impact tests were made on a sample of 316 stainless which had not received the 25 pct cold reduction. Also several data points are reported giving thermal conductivity and electrical resistivity for a sample of 304 stainless steel taken from stock. Figs. 1 and 2 give thermal conductivity and electrical resistivity data for the titanium alloy and for

Jan 1, 1954

By C. E. Birchenall, H. M. Schadel

Vapor pressure of silver over silver-gold alloys has been measured over a range of temperatures for four compositions. Orifice effusion has been compared with electromotive force measurement as a means for determining thermodynamic activities in these solid metallic alloys. Correlated activity coefficients are given for silver-gold alloys for the temperature range 200' to 1000°C. SOUND development of a technique for the measurement of some property of matter requires a comparison with other recognized procedures which have been used to measure the same property. Such a check is especially useful if the assumptions on which the applications stand are basically different for the two methods. Agreement in the results tends to confirm both sets of assumptions. The electromotive force method for determining thermodynamic activities depends upon the reversibility of the electrode processes and a knowledge of the valence states involved. The orifice effusion technique of determining vapor pressures requires that certain mean free path conditions be met, that the state of association of the vapor be known, and that efficient collection of vapors be maintained. Thus the requirements are quite different in nature. Although procedures often exist by which the fulfillment of these conditions may be tested internally, agreement of thermodynamic activities for a single system obtained by both methods constitutes a more severe test of the assumptions. The binary alloy system silver-gold is excellent for this purpose for several series of emf measure-

Jan 1, 1954

By E. J. Quinn, M. F. Fogler

In a recent paper, Rawdon and Mutchlerl gave some exceptionally interesting results on the Brinell and scratch hardness of severely cold-worked metals. In their work, they found that, on continued cold rolling, the metal hardened up to a particular point and then reversed and became softer; this was true for both Brinell and scratch hardness values. The generally reported behavior2 of metals, with respect to Brinell tests on cold-worked material, is that the metals harden up to a certain point and then, on further cold rolling, no change in Brinell hardness occurs. Jeffries and Archer3 state that there is little difference between the scratch hardness of annealed and cold-worked metals; the work of Faust and Tammann4 also indicated no difference between the hardness of annealed and cold-worked copper. Rawdon and Mutchler found, when they plotted the reduction ratio (initial thickness divided by thickness after rolling) against the hardness value for the cold-rolled material, that the hardness number increased up to a reduction ratio of about 3 and then decreased and became even smaller than that for the annealed metal. This behavior was reported for both scratch and Brinell hardness; Figs. 1 and 2 show their results for Brinell hardness on the metals for which they published data. This is an exceptionally interesting phenomenon, if it occurs under all conditions of rolling, and would have an important bearing on the practice of cold

Jan 1, 1925

By L. L. Wyman

PREVIOUS studies1 by the writer dealing with the embrittlement of copper have been concerned with the behavior of various pure and deoxidized coppers when exposed to an oxidation-reduction cycle, and the consequent evaluation of these materials on the basis of their resist-ance to this action. No attention was devoted to the variations in pene-tration of embrittlement with time, when these copper materials are exposed to a strong reducing gas, such as hydrogen, nor to the variations in oxygen penetration, with time and temperature, into the "pure" coppers. The cause of the embrittlement is the reduction of the oxygen in the copper by the hot reducing gas, so that a consideration of time, tempera-ture, the occurrence of hydrogen and oxygen must be given. For the purpose of differentiating some of "the involved factors, the present work may be divided into two separate series of experiments. The first of these deals with the oxidation of purified coppers under various conditions and then the subjection of these to a standard hydrogen treatment. The second series concerns the reduction, under different conditions, of tough-pitch coppers of several oxygen contents. The resulting data will give the rates of oxidation, and of reduction, for the materials involved. The first series of experiments will reveal how rapidly copper may become oxidized, while the second series will indicate how rapidly embrittlement will penetrate into an oxygen-containing copper when it is exposed to hydrogen at different temperatures.

Jan 1, 1933

By F. F. Sharpless

ON Saturday evening, Sept. 9, a small party of Institute members, their wives and friends, left New York to attend the Fall Meeting of the Institute at San Francisco. In this party there were: President and Mrs. Arthur S. Dwight; Mr. and Mrs. George D. Barron; Mr. and Mrs. H. J. Stehli; N. S. Spencer and Miss Spencer; the Secretary and Mrs. F. F. Sharpless. They were joined at Chicago by E. F. Eurich, and by Mr. and Mrs. R. L. Baldwin and daughter. Our party was met at Chicago by Mr. and Mrs. L. V. Rice, Mr. and Mrs. A. D. Terrell and W. F. Boericke, who constituted themselves an impromptu entertainment committee and proceeded to carry out a delightful little program. We were taken to the Lake Shore drive, where a stiff wind off the lake refreshed us after a sultry day on the train, and on our return to the city saw Chicago illuminated with all its brilliance of electricity. We were entertained at dinner at the Drake Hotel. In spite of being two hours late getting into Omaha, we were right on the dot at Denver on Tuesday morn-ing. Horace F. Lunt came to the hotel soon after breakfast, and told us that a trip to the mountains had been planned. Having learned the number in the party, he began to gather up his automobiles for a 10 o'clock start.

Jan 10, 1922