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By W. M. Hirthe, E. H. Greener, D. R. McCann

It has been proposed1'2 that, at low temperatures, point defects are a strengthening factor in inter-metallic compounds whereas, at high temperatures, the deformation is diffusion-controlled and, therefore, an increase in the concentration of point defects tends to soften or increase the plasticity of a compound. More recent investigations, including those of Bloem and Kroger' on PbS, Kramers and smith4 on TiO, and Nadeau5 on LiF, have extended this concept to ionic crystals. Rutile (TiO2) is a tetragonal transition metal oxide which has a defect structure over at least the compositional range. The defect in near-stoichiometric rutile is either an oxygen ion vacancys or a titanium ion interstitial.' This investigation does not contribute to resolving the defect question but either defect would satisfy the results obtained. Six specimens having the same orientation, see Fig., 1, utilized in an independent investigation1' were cut with a diamond saw from a single-crystal boule purchased from the Linde Co. Three specimens were annealed in air at 1200°C for 4 hr and slowly cooled to room temperature in a period of 12 hr. The remaining specimens were reduced in a vacuum of l0 mm Hg at 1200°C for 4 hr and cooled at the same rate in vacuum. The reduced specimens were weighed before and after reduction and, assuming the weight loss to be oxygen, the corresponding oxygen-to-metal ratio is 1.998. All specimens were chemically polished and etched utilizing the techniques described by Hirthe, Adsit, and Brittain." The specimens were embedded in acrylic resin and mounted on a leveling vise in a Kentron micro-hardness tester. A 200-g load was applied to a Knoop indenter with a descent time of 18 sec and a dwell time of 20 sec. Eight indentations were made on a near (171) surface, approximately 3 deg from the (lii) plane, for each orientation of the major axis of the indenter relative to the crystal structure. The dependence of microhardness on orienta-

Jan 1, 1963

By Guy N. Bjorge

HOMESTAKE'S mining methods today are of necessity controlled to a considerable extent by that which has been done in the past. This may be shown by the fact that our two main operating shafts now, the B. & M. and Ellison, were begun in 1878 and 1896 respectively, so that-the loca-tions of shafts, locations of all the drifts on the upper levels, and a great deal of sloping was done before any of us now connected with the mine had anything to do- with it. Anything that I may say is not to be construed as criticism of those who have gone before for it would be a sad commentary indeed on us if we had not learned something from their experience. The levels down to the 1100 in the Homestake mine are spaced at 100-ft. intervals, and below that at 150-ft. intervals. The general plan of develop-

Jan 1, 1934

By Ming-Kao Yen

A considerable amount of work has been reported in the literature in regard to the texture and earing behavior of copper strip. The rolling texture of copper has been confirmed as (110) [112] and (112) [111], which yields ears of a drawn cup at the position 45" from the rolling direction.1-3 The recrystallization texture has been established as the cubic or (100) [001] texture, where the earing positions are at 0" and 90" to the rolling direction.4-8 It has also been reported that in the development of cubically aligned grains of copper strips, the percentage of this cubic texture increased with an increase of final reduction and final annealing temperature.8,9 A comprehensive study on H.C. copper (British commercial copper of high-conductivity quality = Cu 99.95 pct, O2 0.03 pct, Ag 0.003 pct, Fe 0.005 pct and Pb < 0.001 pct) was made by Cook and Richards.6 They concluded that the recrystallization textures could be described as one or more of the following textures: (1) a single texture (100) 10011, (2) a twin texture (110) [112] and (3) a random orientation, depending upon the previous history of the specimen concerned. The effect of various alloying additions in copper was reported by Dahl and Pawlek.10 They found that certain alloying additions, such as 5 pct Zn, 1 pct Sn, 4 pct Al, 0.5 pct Be, 0.5 pct Cd, or 0.05 pct P suppressed the formation of cubic texture. Brick, Martin and Angierll reported that the cold rolled textures due to various additions fitted a rather simple pattern. However, the recrystallization textures were subject to very considerable variations. In the discussion of this paper, Baldwin stated that deoxidized copper containing 0.02 pct P gave a complicated recrystallization texture at lower temperature. When this copper was annealed at high temperature, a single texture appeared which was described as (110) [ill] but. according to a pri- vate communication from Baldwin, this orientation reported was in error and should have been reported as (110)[112]. He also reported that the earing positions of drawn cups were at 60" to the rolling direction.12 Recently, Howald, in his discussion on the paper by Hibbard and Yen,13 reported that the rolling texture of phosphorus deoxidized copper, containing from 0.006 to 0.020 pct phosphorus, was of the pure copper type. When these coppers were annealed at lower temperatures, they exhibited a random orientation, and when they were annealed at higher temperatures they had a mixed (111)[110] and (100)[001] texture, depending on the severity of the final reduction and annealing temperature. However, the specific influence of phosphorus and other impurities on the recrystallization textures and the deep drawing properties of copper strip has not been thoroughly reported. Therefore, an attempt has been made in the present work to determine the rolling and recrystallization textures and also the earing behavior of five types of commercial copper and thereby to evaluate the effect of phosphorus and some other significant impurities on the development of texture for cold reductions of about 87 to 89 pct. Materials Used The five types of copper employed in the present investigation were two phosphorus deoxidized coppers of different phosphorus content (0.007 and 0.013 pct P), an oxygen-free copper (OFHC), an electrolytic tough-pitch copper, and a fire-refined tough-pitch copper. These materials were subjected to a thorough spectroscopic and chemical analysis. The designations and the chemical compositions were as shown in Table 1. The coppers, FA1, FA2 and FA3. were hot-forged from 3-in. billets into a ½ X 6-in. plate and cold rolled to the ready-to-finish gauge indicated below. FA4 and FA5 were hot rolled and scalped to ready-to-finish gauge. The grain size of all the materials in the ready-to-finish condition was about 0.030 to 0.045 mm. Table 2 shows the last stage of the production schedule for each copper strip used. Experimental Procedure ANNEALING, GRAIN SIZE AND HARDNESS DETERMINATIONS Specimens of each type of copper were finally annealed in air for periods of one hour at temperatures ranging from 300 to 1600°F and were subsequently cooled in air. The average grain diameter of the annealed specimen was estimated by comparing with a standard grain size chart. Hardness was determined on the Rockwell 15 T scale. CUPPING TESTS Cups were made in a blanking and drawing set, in which blanks of 2-in. diam were drawn to a cup of 1.25-in. diam with an average depth of about 0.75 in. The clearance between the punch and die was about 0.032 in. The ears of the cup were measured with a special fixture which read the height of ears to one-thousandth of an inch on every ten-degree interval along the circumference of the cup. POLE FIGURES The usual transmission diffraction method with unfiltered copper radiation was employed to determine the pole-figures of the specimens cold-rolled or annealed at 900°F. All the pole-figures were derived from the positions of intensity maxima on 111 diffraction rings of the X ray photo-grams taken at 10 rotation of a

Jan 1, 1950

By Henry G. Granger

NOTHING in this paper is to be understood as even suggesting a moment&apos;s suspension of the splendid work now going forward on the Isthmus of Panama, except so far as it is related to the proposed locks. All the work already done, and all material purchased or ordered, would be available for the plan herein proposed. The situation and the problem concerned may be summarized as. follows : The scheme of a lock-canal through the Isthmus of Panama was adopted, as is well known, on two principal grounds-namely, the greater expense of a sea-level canal, and the longer time required for its construction. Of these, the latter is believed to have been the more influential. But further developments have diminished the weight of both, so that a reconsideration of the question is warranted. It is the purpose of this paper to advocate such a reconsideration-emphasizing the importance of certain objections to the lock-canal not mentioned or not duly appreciated in the report of those members of the International Board of Consulting Engineers who favored this form; showing the nature and bearing of the new facts developed; and, finally, proposing a combination of well-known methods and apparatus, which would, in my judgment, effect the construction of a sea-level canal in less time, and perhaps at no greater cost, than will be required for the remaining work on the lock-canal. I. OBJECTIONS TO A LOCK-CANAL. 1. Earthquakes. Two centuries ago Panama is said to have been destroyed by an earthquake. In 1882 a rather violent earthquake was felt at the southern end of the Isthmus. In 1898 I felt a slight shock near the present border-line of Colombia. In 1900 I felt three shocks at Quibdo, the head of navigation of the

Jan 1, 1909

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 S. C. Sircar, B. K. Dhindaw

KINETICS and mechanism of sulfation reactions have been studied extensively. Qualitative and quantitative data are reported for the kinetics and mechanism of sulfation reaction of copper oxide pellets;&apos;&apos;2 yet it remains a controversial Subject. The mechanism and kinetics of the sulfation of zinc oxide powder (B.D.H. analar quality) were studied by gravimetric technique. A spring of high-carbon steel wire with accuracy well within 0.2 mg was used for measuring weight change. The sample was taken in a Pyrex glass bucket, hanging freely inside a Pyrex glass tube reactor, with a gold wire attached to the spring, the reactor being surrounded by a movable furnace (double wound type) with a temperature control within *5"C. Flow of oxygen, 60 cu cm per min, and sulfur dioxide, 45 cu cm per min, were measured through calibrated flowmeters and the mixture dried over PZ05 before entering the reactor. The experimental results are presented in Figs. 1 and 2. The plot of weight change of zinc oxide, giving the amount of zinc sulfate formed, was found to be linear over the temperature range of 500" to 700° C and up to a conversion of approximately 60 pct, as beyond it they divert from linearity.&apos; The rate of sulfation was found to be affected by total flow rate of gases at a fixed ratio of SO2/O2, up to 60 cu cm per min, and was found to be linearly dependent on quantity of total powdered sample taken. The plot of rate of sulfation of zinc oxide, 70 mg, with varying amounts of vanadium pentoxide, at a constant ratio of gases as mentioned above, and at a constant temperature of 625"C, was also found to be linear as seen in Fig. 2. Extrapolation to zero V2O5 addition gives the same rate of sulfation, as in case of pure zinc oxide, 70 mg. Vz05 was prepared by heating ammonium vanadate at 600°C for 15 min in a muffle furnace. The available literature points out that the theory of sulfation that has received the maximum support postulates the following mechanism for sulfation of ZnS: 2ZnS + 30, = 2Zn0 + 2SOZ; the ZnO formed acts as a catalyst for the reaction, 2 S02 + O2 = 2S03. This SO3 reacts with ZnO to give zinc sulfate. It is suggested here that the above widely supported mechanism is operative in the sulfation reaction and that the rate-controlling step in the sulfation reaction of ZnO is the formation of SO3 from SO, and 0,. The authors are carrying on further work in this line, and the details will be published later. The authors wish to acknowledge the facilities provided and the help extended by Prof. P. R. Dhar, Head, Department of Metallurgical Engineering, and the permission granted to publish this note by the Director, I. I. T., Kharagpur.

Jan 1, 1969

By John M. Lovejoy

NATURAL resources become a source of wealth as they are exploited and made available to the people in usable form. Experience has taught us that Nature does not readily give up her treasures, but the ingenuity of man in the field of techologic progress is required to find and efficiently exploit these resources. History has also demonstrated that with advancing technologic knowledge the. world has become progressively richer in its resources. Those that could not be commercially exploited are now being turned to beneficial use. Through expanding technology and the use of substitutes and synthetics, availability of the world&apos;s sources of natural wealth is today many times that of a hundred or a thousand years ago. And so it is with petroleum. Technology is also the great multiplier of our petroleum resources. Through improvements in the art of finding, drilling, and producing, our ability to meet rapidly increasing demands over the last quarter century has been maintained. On the other hand, had our

Jan 1, 1944

By J. M. Clark

(Wilkes-Barre Meeting, June, 1911.) For some years past, those interested in the development of the increasingly important mining industry of Canada, have urged the adoption by the Dominion Parliament of a federal mining-law, which would have the force and stability of statutory enactment. At present, placer-mining in the Yukon Territory, is governed by the Yukon Placer Mining Act. All other mining under federal jurisdiction is governed by &apos;Orders in Council and Ministerial Regulations. In the earlier stages of development, it is perhaps a matter of necessity that these important matters should be so dealt with; but it is now felt that the time has come when mining-rights in the extensive regions under federal control should be put on a permanent basis, -and that any changes required from time to time should be made only after full and open discussion in Parliament. A short sketch will suffice to indicate how vast and varied the interests affected really are. When the Dominion of Canada was constituted by the Imperial Statute known as the British North America Act of 1867 (which came into force by proclamation on July 1 of that year), it comprised only the present Provinces of Ontario, Quebec, Nova Scotia, and New Brunswick; but provision was made for the inclusion of Newfoundland, Prince Edward Island, British Columbia, Rupert&apos;s Land, and the North West Territories. Subsequently Rupert&apos;s Land and the North West Territories were acquired, the &apos;Crown Colonies of British Columbia and * SECRETARY&apos;S NOTE.-Mr. Clark, an eminent Canadian lawyer, and joint author of the treatise on "The Law of Mines in Canada," has been requested by the Do¬minion Government to prepare a Federal mining-law, and presents this paper, by invitation of the Council, in order to obtain, if possible, useful suggestions from members of the Institute.-R. W. R.

Apr 1, 1911

By R. S. Handy

DOES hand-sorting of mill feed pay? The fact that the practice is so general would seem to indicate that there must be good reasons for following it; yet, to my mind, the advantage in many cases is doubtful enough to invite a thorough discussion of the subject, in an effort to determine under what conditions hand-sorting does pay. A typical sorting plant in the Coeur d&apos;Alene district handles about 800 tons of mine-run ore per day. The material is run over a grizzly with about 4-in. opening; the oversize is crushed to about 4-in. size and joins the undersize, and the whole product is washed and screened on trommels with about 1 ½ -in. openings. The oversize from these trommels is spread on a belt and the waste and first-class ore are sorted out by hand, the residue being further crushed, and passes, together with the trommel undersize, into the mill feed bins. About 50 tons of shipping ore and 150 tons of waste are sorted out per day, leaving about 600 tons of mill feed. To sort out this material requires 20 ore sorters and five bosses and repairmen. The normal cost of hand-sorting is about 16 c. per ton of run-of-mine ore, or 65 c. per ton of material sorted out. I believe that straight crushing and milling of the run-of-mine ore, in this case, is not only cheaper, but is metallurgically moree canonical and efficient than hand-sorting followed by milling of the residue. At one of the Bunker Hill rock-houses, 1250 tons of run-of-mine ore are reduced to pass 30-mm., or about 1 ¼ -in. opening in six hours, requiring five men. The equipment and the power consumed are not greatly different from that required in a sorting plant of the same capacity, and the normal cost of thus preparing the feed for milling is under 3 c. per ton of mine product. The relative cheapness of this method as against hand-sorting is thus clearly established, the saving being about 13 c. per ton. If there is any virtue in hand-sorting, then, it must lie in the metallurgical results achieved.

Jan 4, 1918

By J. G. Early, F. V. Lenel, G. S. Ansell

The isothermal shrinkage rates of copper-powder compacts were determined in the temperature range from 760o to 1060oC. The rates for compacts fabricated from a pure spherical copper powder were compared, on the one hand, with those fabricated from a spherical powder containing a dispersion of aluminum oxide in the copper matrix and, on the other hand, with those fabricated from a pure copper powder having irregularly shaped particles. The irregular copper-powder compacts shrank much faster than the spherical copper-powder compacts and these, in turn, shrank faster than dispersion -strengthened copper -powder compacts. The experiments were run under a small external load. By varying this load, the stress dependence of the isothermal shrinkage rate could be measured for compacts from spherical-copper powders. This stress dependence was found to be approximately proportional to the 4th (dispersion-strengthened alloys) or 4.5th (pure metals) power of the stress. It is concluded that the material-trans port mechanism is due to dislocation climb rather than to Herring-Naharro creep. In this investigation the isothermal shrinkage rates of compacts made of copper powder with an average particle size of 70 g in the temperature range from 780o to 1060°C were studied. The aim of the investigation was to determine the mechanism of material transport responsible for the shrinkage of these compacts. Since the phenomenon observed in this investigation was shrinkage of compacts at high temperatures, it will be necessary to consider all the material-transport mechanisms possible in sintering. It is unlikely that evaporation and condensation, surface diffusion, or even volume diffusion of vacancies, in which surfaces of small radius of curvature are vacancy sources and those of larger radius of curvature vacancy sinks, will materially contribute to a sintering process involving shrinkage, i.e., one in which the centers of adjacent particles move towards each other. The two principal mechanisms which were considered were the so-called Nabarro-Herring mechanism and a plastic deformation mechanism by dislocation movement. Both of these mechanisms were originally conceived to explain creep, i.e., the plastic deformation of metals at elevated temperatures under a constant applied stress. The shrinking of metal-powder compacts which was studied in this investigation can be readily treated as a creep process. This means that the shrinkage rates observed are considered as creep rates under the influence of an applied stress. It is true that the stresses in sintering experiments are generally not constant but decrease continually with time, but, by considering creep rates or shrinkage rates over a relatively short time interval, the small changes in stress during this time interval can generally be neglected. Nabarro-Herring microcreep is a high-temperature deformation mechanism which is caused by a diffusional flow of vacancies from boundaries under a tensile stress towards those under a compres-sive stress. Herring1 has shown that in this type of microcreep the strain rate e is proportional to the applied stress and follows an equation of the form ma, aexp(-Q/RT) [l| where <j is applied stress, Q is the activation energy for self-diffusion, R is the gas constant, and T is the absolute temperature This type of creep can explain the shrinkage of a porous compact. The surface of the pores are subjected to the tensile stress of surface tension, while the grain boundaries are under a compressive stress also due to surface tension. Vacancies diffuse from the pore surface through the lattice to the grain boundaries, where they are eliminated. In order to maintain vacancy equilibrium at the pore surface the vacancies leaving the region of the pore surface are replenished from the volume of the pore, which means that the pores shrink.

Jan 1, 1964

By P. H. Dudley

A Discussion of the Paper of Prof. Howe. (Bi-Monthly Bulletin, No. 14, March, 1907, pp. 169 to 274.) P. H. DUDLEY, New York, N. Y. (communication to the Secretary*) :-The characteristics of Prof. Howe&apos;s metallurgical papers are, that he is able, from the mass of confusing evidence on the subject, to make an analysis and present hypothetical and essential principles in concrete form for consideration and discussion. I can appreciate, from the practical side of the subject, the arduous labor of collecting and investigating the data that is essential to prepare the paper. Much of the data necessarily came from material of preceding years. of manufacture in which there was allowed time for chemical reactions of the recarburizer, and for the elimination of the oxidation-products before teeming the ingots. This condition gave a favorable tinge-element to free the metal from slag- and other impurities, but, in allowing the. ingot to cool before charging in the furnace, the time-element entered as a detrimental factor in the development of the pipe or shrinkage-cavities, which gave an ingot-structure deficient in soundness. The interpretations from such material must be made with due allowances for the methods of manufacture, and must be given proper weight, as general facts, in subsequent arguments. The difficulties under which investigators labor are not easily surmounted in differentiating between reliable and unreliable data incident to variables of methods of manufacture, chemical composition of the alloys of steel, mediocre practice and that of the highest state of the art. Modern practice and large outputs in Bessemer steel have reversed the effects of the time-element-by cutting short the chemical reactions of the recarburizer and the elimination of

Jan 5, 1908

By H. Y. Yancey, B. M. Bird

During the past four years the experimental work in coal washing carried on by the U. S. Bureau of Mines and the University of Washington has been devoted mainly to the development of special methods for the tabling of fine sizes of coals that are difficult to wash. One important outgrowth of this investigation has been the application of hindered-settling classification to coal tabling. Although used for many years in ore dressing, the term "classification" as used here may be new to many readers. It may be defined as the separation obtained when a bed of particles is held in a uniform state of suspension in an upward current of water, either continuous or pulsating, just sufficiently strong to keep the bed in a mobile condition. A common example of this type of separation is a jig in which there is no suction stroke. When the hindered-settling classifier is used with the coal-washing table, the fine-size raw coal, instead of being fed direct to tables, as is the prevailing practice, is first fed to the classifier and grouped, according to the rate of settling against the upward current of water, into perhaps six separate products. After dewatering, each of these except the sixth, a refuse product, is elevated to a seperate feed bin arid washed on a separate table. This paper gives a brief discussion of the basis for the use of hindered-settling classification of a table feed; a description of the experimental work; a comparison of the results obtained with and without classification; and a discussion of the application of the classifier in commercial coal washing. Basis for Use oF Hindered-settling Classification of Table Feed Although theoretical reasoning might be used to justify treating a table feed by hindered-settling classification,l the simplest method of demonstrating the need of such a step before tabling is to show the

Jan 1, 1930

By AIME AIME

A LUSTY baby of the Institute, the Coal Division, showed that it had acquired a full set of teeth and was capable of man&apos;s work at the Division meeting at Fairmont, W. Va., on March 26 and 27. At this second of a series of field meetings, the first of which was held in Pittsburgh last fall, the industry in the East was represented from top to bottom and good humor and enthusiasm were the predominant notes. West Virginians are always good hosts and this meeting would have proved the statement to any inclined to doubt it. The spacious auditorium of the Fairmont Hotel was arranged for the technical sessions, the hotel being headquarters for the meeting. About a hundred and twenty-five representatives were registered and in attendance when Thomas G. Fear, chairman, opened the morning session at 10 o&apos;clock Mr. Fear first introduced Howard Eavenson, vice-chairman of the morning program, who, as chairman of the Coal Division, had labored long and cheerfully to make the meeting successful. Mr. Eavenson talked briefly on what the organization was doing, pointing out that these field meetings were designed to bring the members into closer touch with the parent Institute and give the younger engineers in the field a better opportunity to participate in the work the Institute is doing. He congratulated the various committees for their work in promoting the meeting.

Jan 1, 1931

The Library of the above-named Societies is open from 9 A.M. to 10 P. M. except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The tine spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 10, 1917

C. N. FEnner, New York City (communication to the Secretary) : A possible explanation of some of the&apos; phenomena of amalgamation cited by Mr. Bayliss and others has occurred to me. We know that if, to a quantity of mercury, gold and silver are added until a putty-like paste is formed, and if this mass is spread on a flat surface and pressure is applied, a more fluid portion of the mercury will be squeezed out from the rest, carrying gold and silver with it. The proportion of gold to silver will depend, I think, upon various causes and conditions—the relative chemical affinity which gold and silver have for mercury; the amount of pressure used; the presence of other metals:

Jan 1, 1898

By Henry Fay

LAWRENCE ADDICKS, New York, N. Y., (communication to the Secretary *).-There are two points regarding gun erosion on which I want to say a few words: The first is about the analogy to hardening of wire by drawing and the second the possible role played by thermal conductivity of the metal. The ductile metals do not necessarily become brittle when cold-worked as it is possible to draw copper from 3. in. in diameter soft rod down to the finest hair wire without annealing. This results, as stated in the paper, informing a hardened core with a very hard skin. The electrical conductivity is depressed some 3 per cent. and the tensile strength nearly tripled. A soft copper wire 0.08 in. in diameter and 6 in. long may be twisted 150 or more turns before the wire will snap under torsion. A hard-drawn wire will break after perhaps a dozen twists, the skin breaking down at one spot. Just wiping the wire with a cloth clamp with dilute nitric acid has a remarkable effect in increasing the number of twists without appreciably lowering the tensile strength, showing the skin to be very thin. On the other hand, pickling the rod, from which the wire is to be drawn, in dilute nitric acid also greatly increases the number of twists which can be applied to the resulting wire. This indicates that the copper oxide scale produced when the wire bar is rolled hot is more or less rolled into the rod and may have much to do with the skin effect. We also know that if the conditions of drawing are not correct, the heat of deformation in the die may produce quite an annealing effect. The application of this analogy to what occurs in a gun to produce the effects noted offers some difficulty. The second point is that as the temperature of the surface of the gun bore has undoubtedly a great deal to do with the amount of erosion, one natural remedy would be to conduct the heat away fast enough to keep this temperature within desired limits. This brings up the question of the thermal conductivity of the metal of which the gun is made. We know that the conductivity of pure metals is greatly altered by alloying and that the alloy is usually, though not always, lower in conductivity than the metal before alloying. This is interesting when it is considered that the high-nickel and manganese-steel alloys show greater erosion as stated. Would it not be instructive to study the question from the point of view of heat conducted away from the eroded surface?

Jan 3, 1917

By C. K. Leith

THE outstanding fact of the mineral world today, at home and abroad, is the surplus of current production, and particularly of capacity for production, over current requirements. This is not by Any means a new condition, but never before has it loomed up in such&apos; menacing form. - Those of us who have devoted most of our professional efforts to the discovery and development of &apos;new mineral supplies now suddenly find ourselves with the job apparently accomplished, waiting for some one else to find an outlet for excess mineral production before we can further. The management of the industry is in much the same boat. The psjrcho16gy of the industry has been so grooved in the direction of acquisition of, minerals that at the present moment the mineral industry confronts the new problem of surplus in more or less of a daze.

Jan 1, 1931

By G. R. Speich, S. A. Kulin

R. C. Shnay (Dept. of Mines and Technical Surveys, Ottawa, Ont., Canada)-—The authors are to be congratulated on an interesting and informative paper. However, several questions arise when the isothermal formation of martensite .is considered in relation to the formation of bainite at temperatures near the M, point. The reactions in an alloy and in a plain carbon steel would appear to be comparable; and in the course of a recent investigation of the austenite-bainite transformation in a plain carbon steel,Ia the writer has obtained data at temperatures above and below the M, point. These data are in some respects similar to those of the authors and a comparison would seem justified. The steel used in this investigation had the nominal composition: C, 0.80 pct; Mn, 0.20; and Si, 0.20. The course of the transformation was followed by the use of a magnetic balance. The magnetic moment of the specimen as determined by this instrument is directly proportional to the percentage of the total volume of the specimen which has transformed to bainite. ~lf specimens were austenitized at 1850°F for 4 hr, quenched to the transformation temperature, and quickly transferred to the magnetic balance. Readings were taken at regular intervals until the transformation had stopped. A typical transformation curve is shown in Fig. 9. The preliminary curve preceding the S-shaped curve was found at all temperatures above the M, to around 600°F. Both the extent of this preliminary curve and the time interval between it and the S-shaped curve were found to decrease with increasing temperature as was suggested by Davenport and Bain.14 Therefore,

Jan 1, 1953

By Arthur Notman

THE raw material men in all industries, and copper is no exception, are accustomed to think of them- selves as the whole show, and not without justice, for if there were no copper mines the world would have no copper. Nevertheless, many different things costing money and resulting in profits must be done to their product before it is ready for the world&apos;s use. In other words, they are making the frequent mistake of Chinking in terms of partial costs. Nobody really uses electrolytic copper. Possibly that is why nobody seems willing to pay anything for it. The manufacturers, being canny, do not buy any more electrolytic than they feel that they can work up and sell profitably, although they like to make the raw material men Chink that they will take all that can be produced. This is a state of affairs that has aroused my sympathy and curiosity, and has induced me to study the financial history of the copper wire and brass industry of the country or such portion of it as publishes any records readily available to the curious minded. About 60 per cent of the electrolytic copper used in this country is drawn into wire and consumed by the electrical industries. The remaining 40 per cent is

Jan 1, 1926

By AIME AIME

I am happy to welcome you to the twenty-third conference of the National Open-Hearth Committee, and our joint conference with the Blast Furnace Committee, of the American Institute of Mining and Metallurgical Engineers. It is appropriate that, for our fifteenth year anniversary, we should meet in the hotel and the city where this Open-Hearth Committee was inaugurated in 1925. At that first meeting, only a handful of men from a number of steel companies met to discuss ways and means to start a movement to improve the practical and metallurgical technique of open-hearth operations among independent manufacturers, as the United States Steel Corporation had carried on for many years.

Jan 1, 1940