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By R. W. Smith, R. W. M. Lai, J. Leja

J. Leja (Professor, Dept. of Mineral Engineering, U.B.C. Vancouver, Canada) — I would like to offer some comments on the behavior of contact angle with time, treated in this paper. The authors should be congratulated for a clear exposition of these uncommon departures in the correlation between flotation and contact angle, in systems of importance to industrial practice. Some nine years ago Professor J. H. Schulman (presently at Columbia University, New York) and I reported on a similar study conducted at the Ernest Oppenheimer Laboratory, Cambridge, England.' The systems used by us had, how- ever, no direct practical application at that time, as mercury in solutions of xanthates was tested with a variety of alkyl-aryl polyoxyethylene frothers which were then new to flotation practice. Further, the paper dealt with findings contrary to the then widely held belief that the contact angle established in collector-solution is unaffected by the addition of a frother. Correlation with flotation, or lack thereof, was not sought, though we did suggest that in many cases the selectivity of frothers might be influenced by the dynamic contact angles. We also stated (on p. 243,

Jan 1, 1968

Executive Committee. Louis D. HUNTOON, Chairman. ARTHUR S. DWIGHT, Vice- Chairman. E. MALTBY SHIPP, Treasurer. GEORGE F. KUNZ, HOMAS T. READ, Secretary. Woolworth Building, New York, N. Y. Meeting, May 2,1913. The Annual Meeting of the New York Section was held at the Engineering Societies Building, Friday evening. May 1913, at 8 p.m. Dr: Kunz presided. The Annual Report of the Secretary-Treasurer was read and accepted. Mr. Colvocoresses offered the following amendments to the By-Laws: ARTICLE II: First paragraph amended to read as follows: "The officers of this Section shall be. a Chairman, Vice-Chairman, Secretary, and Treasurer." In the second paragraph the word "four " to be changed to " five." ARTICLE V : The following paragraph to be inserted: ' The funds of this Section shall be received by the Treasurer, and shall be paid out only by check signed by the Treasurer, and in case of his absence or inability, the Chairman, Vice-Chairman, or the Secretary may act for the Treasurer." On motion duly seconded the amendments were adopted as read. The Nominating Committee, appointed by the Chairman, recommended the following men for officers : Chairman., Louis D. Huntoon ; Vice-Chair-man, Arthur S. Dwight; Secretary, Thomas T. Read, and Treasurer, E. Maltby Shipp. There being no other nominations, Mr. Rand moved that the Secretary be authorized to cast the vote for the members in favor of the men nominated. Motion carried. In reply to the circulars mailed regarding the summer outing the Secretary reported that 89 members approved and 9 did not approve of such an outing. The Chairman introduced Dr. M. Belowsky, of the University of Berlin, who addressed the meeting in German. Following Dr. Belowsky, the speaker of the evening, A. H. Fay; of the Bureau of Mines, discussed Metal Mine. Accidents.

Jan 6, 1913

By Herbert Haas

The following notes describe a laboratory for metallurgical chemistry and technical analysis which I built late in 1903, while engaged, as constructing engineer, in erecting a pyrite smelter at the Afterthought mine, Ingot, Shasta county, California. This design partly supplements the paper of Mr. C. H. White, which was presented at the Atlantic City Meeting of the Institute in February, 1904.' The work of a chemist at a busy smelting-plant differs radically from the work of a student, who takes all possible care to have his analysis exact within hundredths of a per cent., and has plenty of time to devote to the operation. The works-chemist, having the shortest time in which to make his determinations, should have a laboratory arranged as conveniently as possible to save time in carrying out his work. By a conveniently-arranged laboratory, I do not mean an elaborately furnished one; but rooms suitably fitted up and supplied with the necessary apparatus to do the work expected from the chemist within the requirements of technical analyses. It is not uncommon at large smelters to have the night ae-sayer prepare 30 or more samples for titration, in time for the

Jan 1, 1905

PROF RICHARD ÅKERMAN Stockholm, Sweden DR. FRANK DAWSON ADAMS Montreal, Canada PROF RICHARD BECK Friberg, Germany ANDREW CARNEGIR New York, N.Y. DR. JAMES DOUGLAS New York, N.Y. PROF HATON DE LA GOUPILLIERE Paris, France SIR ROBERT A. HADFEILD London, England PROF HANS HOFFER Leoben, Austria JAMES FURMAN HOEFER Leoben, England PROF HENRI LOUIS LE CHATELIER Paris France

Jan 1, 1917

By H. W. Mead, C. E. Birchenall

SELF-DIFFUSION of iron in austenite is a process which may play a significant role in some of the practically important reactions which occur in solid irons and steels. It also provides a system in which the interaction of vacancies on substitutional sites and atoms in interstitial positions may be investigated. For both purposes, accurate values of the diffusivities are required. Two sets of previous measurements exist, each containing features which require checking. In the course of an investigation to determine the rate of diffusion of iron in certain steels, Garwick and Rosenqvist' measured the self-diffusion coefficient of iron in a 0.10 pct* C steel and obtained a dicated that while at lower temperatures D increased with increasing carbon content, at the higher temperatures it first increased and then decreased. At the same time the activation energy decreased linearly from a value of 69,000 cal per g-atom for pure iron to 33,000 cal per g-atom at 1.06 pct C. This rapid decrease in activation energy implies that iron at higher temperatures within the austenite range would diffuse more slowly in high carbon steels than in steels of lower carbon content. Experimental Procedure The radioactive iron used in this work was obtained from Oak Ridge National Laboratory. The unit consisted of about 1 microcurie each of Fe7 and Fe It was allowed to decay for two years. At the end of this time most of the Fe with a half-life of 46.3 days, had decayed, while most of the original Fe(half-life 2.91 years) still remained. The iron as chloride was extracted into an ether layer, using the method of Ashley and M~rray. After evaporation of the ether the iron chloride was dissolved in 250 ml of aqueous solution containing 2.4 gpl Fe. The compositions of the steels used are listed in Table I. Disks of ¾ in. diam and about ¼ in. thick were machined from these steels for use in diffusion couples. The disks were surface ground on both sides to ensure parallel opposite faces. One face of each disk was polished through 000 emery paper. Half of the prepared disks were plated with radioactive iron. For this, 1 ml of the radioactive iron

Jan 1, 1957

By Waldemar Lindgren

THE important investigations of Dr. G. F. Becker at Steamboat Springs, Nev., in 1885, aided by the analytical work of W. H. Melville, established the fact that sulphides were being deposited at the surface by hot ascending waters.1 Steamboat Springs is situated near the eastern base of the escarpment of the Sierra Nevada, six miles distant from the Comstock lode. In a region of former volcanic activity, hot springs with a temperature of about 80° C. break forth through a fissure in granodiorite, and at the base of a basaltic bluff the waters have deposited a large amount of siliceous and calcareous sinter, some of which is colored red by antimony sulphide. The sinter from one of the springs was analyzed by Mr. Melville,2 and his results, re-calculated to grams per kilogram, showed [ ] The relative quantities of antimonious and arsenious sulphides are not given in the above analysis, but I believe that the former greatly predominated. The water of one of the springs was also analyzed by Melville and the re-calculation of this analysis to salts that were possibly present is given in Table I.

Jan 1, 1913

By A. Gemperle

Electron diffraction and transmission electron microscopy on foils at room temperature were used to investigate the ordering of Fe-Si alloys containing 10 to 23 at. pct Si. A certain degree of DO3 order was found in all alloys. With the exception of the lowest silicon concentration for which the antiphase domains could not be clearly resolved, the alloys have a domain structure of two-domain type with boundaries having 1/4a01<111> displacement vectors for less than 12.3 at. pct Si and with boundaries having 1/2 a0<100> displacement vectors for more than 12.3 at. pct Si. The alloys with 12.3 at. pct Si have a domain structure consisting of fine domains with 1/2a&apos;o<100> boundaries within much larger domains with 1/4a&apos;o<111> boundaries. The development of these structures can be explained by transition of the alloy from the disordered state into the B2-type order and then into the D03-type order by the mechanism proposed previously for the FeSAl alloys. The existence of the B2 structure in the lower part of the investigated concentration range reported in some articles can be explained by fine domains with 1/2a&apos;o<100> boundaries formed by several disordered planes within large domains with 1/4a&apos;o<111> boundaries. The ordered structure predicted by the theory —with practically no domain boundaries —is found in the alloys having 12.3 at. pct Si where it develops in the B2 structure region. ORDERING in Fe-Si alloys was first studied by phragmenl who found that beginning with 13 at. pct Si the DO3 (Fe3Si) superlattice reflections appear in the diffraction patterns. The equilibrium diagrams constructed later by corson2 and Haughton3 from various measurements proposed the existence of a homogeneous solid solution (a phase) in the range from 0 to 25 at. pct Si. Jette and Greiner4 and Farquhar et al.5 measured the relation between lattice parameter and composition and they considered the break in the curve at 9 to 10 at. pct Si to be caused by the ordered solution a"(Fe3Si). Glaser and Ivanick6 Determined critical ordering temperatures of the alloys containing from 10.9 to 27.9 at. pct Si from the measurement of the electric resistivity of quenched samples. In all cases the critical temperature was lower than the melting point and it was highest for 25 at. pct Si. Lihl and Ebel7 measured the lattice parameter curves at various temperatures up to 1000°C. The region between two breaks on these curves, corresponding to 10 to 12.5 at. pct Si at room temperature, was considered by them to be two-phase (a + a"). They concluded by extrapolation of the measured values that a" in the alloy having 25 at. pct Si is stable up to the melting point. Davies8 studied superlattice reflections in the X-ray diffraction patterns of an alloy containing 8.7 at. pct Si. He found the B2 structure and short-range order in the slowly cooled samples and the DO3 A. GEMPERLE is Research Scientist, Institute of PhysicS, Czechoslovak Academy of Sciences, Prague, Czechoslovakia. __Manuscript submitted January 2, 1968. IMD structure in the quenched and annealed samples. This investigation first reports the presence of the B2 structure, phase a&apos;: in Fe-Si alloys. Meinhardt and krisement9,10 also found its existence in Fe-Si alloys by neutron diffraction. No order was detected by them in the alloy containing 8 at. pct Si. The onset of B2 order was observed at a composition of 9.2 at. pct Si. They found almost perfect B2-type order with partial DO3-type order at room temperature in the 10 to 12.5 at. pct Si range and almost perfect DO3-type order in the 12.5 to 25 at. pct Si range. They established the critical temperatures Tc of both the structures through measurement at higher temperatures. The critical temperature for the B2 structure was found to be always higher than the critical temperature for the DO3 structure of the same alloy. They extrapolated the curves of the critical temperatures and concluded that the alloys with more than 17 at. pct Si have the B2 structure up to the melting point and the alloys with more than 23 at. pct Si have the DO3 structure up to the melting point. The results of Meinhardt and krisement9,10 were confirmed by Dokken&apos;s measurement" of the temperature dependence of the electrical resistivity in the 10.8 to 15 at. pct Si range. On the other hand chessin12 detected by X-ray diffraction a considerably lower degree of order in the 12.7 at. pct Si alloy. ANTIPHASE DOMAIN STRUCTURE IN ALLOYS WITH B2- AND DO$-TYPE ORDER The ordered structures B2 and DO3 can be described in terms of a subdivision of the bcc lattice into four fcc sublattices with a parameter double that of the bcc lattice. Following Marcinkowski13 we will label them I. 11, 111, IV. The B2 structure in the AB alloy is formed by placing A atoms on sublattices I and II and B atoms on sublattices III and IV. In a non-stoichiometric perfectly ordered alloy having concentration (A) > (B), A atoms occupy sublattices I and 11. and A and B atoms distributed at random occupy sublattices III and IV. The DO3 structure in an A3B alloy is formed by placing A atoms on sublattices I, 11, and 111, and B atoms on sublattice IV. In a nonstoichiometric, perfectly ordered alloy having concentration (A)/3 > (B), A atoms occupy sublattices I, 11, and 111, and A and B atoms distributed at random occupy sublattice IV. As further shown in Ref. 13, two types of domains are possible in the B2 superlattice and the antiphase domain structure has associated with it boundaries with displacement vectors 1/4 a&apos;o<ll1> only. Four types of domains are possible in the DO3 superlattice and the antiphase domain structure has associated with it boundaries with displacement vectors 1/4a&apos;o<111> and 1/2a&apos;o<l00>. Bethe14 suggested on the basis of theoretical considerations that in a structure with two sublattices at low temperatures only one domain should be present in the whole crystal at equilibrium. Similarly Bragg15 concluded that at low temperatures the domain struc-

Jan 1, 1969

The Reconstruction and Research Division of the United States Council of National Defense has, up to date, prepared two reviews on the above subjects: one covers foreign countries and the other covers the activities in the States. These reviews contain information appearing in various Governmental and public periodicals. While the information on foreign countries is necessarily incomplete and fragmentary, its summation is perhaps the most complete work of this kind so far accomplished. The information from the states consists mainly of bills and ordinances introduced in the state legislature, municipal councils, legislature committee reports, programs suggested by governors, and other state and local officials and local organizations It is realized that a good deal of this information will be useful to engineers studying conditions in the various states, and especially to those who want an insight into the general condition in all the states. For instance, the reconstruction problem in each state involving highway, reclamation, buildings, etc., are covered in detail.

Jan 8, 1919

By Spencer Cragoe

I have read with much interest the elaborate and able paper of Messrs. Granger and Treville on the Mining Districts of Colombia, presented at the Atlantic City Meeting (ante, p. 33). Going into detail, however, as the paper does—and particularly with reference to the department of Antioquia, I am somewhat surprised that the property of the Frontino and Bolivia Company, probably one of the richest and most extensive in Colombia, should come off with such scant notice. The entire property embraces an area of some 28 square miles, and is situated at a distance of about 2 leagues from Remedios—after Medellin probably the most important town of the Department—and lying in approximately &apos;7° N. latitude. The neighborhood of Remedios has been long celebrated for its production of the precious metal. Alluvial gold in large quantities has been obtained from the vicinity for upwards of two centuries; and even to-day a large proportion of the population finds a comfortable livelihood, during the dry season, in washing the sands of various rivers, notably the Rio Porce; while the amount of gold, in the form of nuggets, brought almost daily to Remedios and other points, from streams in the immediate neighborhood, is astonishing. These nuggets vary much in size. The majority, of course, are small, but larger ones are by no means scarce. I have been considerably surprised at the amount and value of the trade thus transacted between natives and merchants of the various towns. The property owned by the Frontino and Bolivia Company has been, I believe, for the larger part of the present century,

Jan 1, 1899

By A. D. Hodges

In 1874 my attention was called to what seemed to me an interesting and new nickel and cobalt combination found in Ludwig and Carter&apos;s copper mine, near Mason Valley, Esmeralda County, Nevada. With the assistance of Mr. A. Hebberling I made several partial analyses of the mineral or minerals. I also communicated with my friend, Professor H. B. Cornwall, of the John C. Green School of Science, College of New Jersey, who analyzed a couple of specimens which I forwarded to him. The copper ore occurs in the mine principally as carbonate and to a certain extent as silicate, the latter generally in connection with clay seams or bands. In some places, together with the copper silicate and clay, generally interstratified with them, there occurred a compact shining black mineral (a) containing nickel and cobalt. Occasionally, in cavities, in connection with (a) was found a black substance (b), either massive and in this case very similar to (a) but with driller lustre, or forming an incrustation with rough and botryoidal surface and radial-fibrous structure, or granular and earthy. A few specimens were found having on the surface very fragile black needles (c) sometimes 1/2-inch long, interspersed with needles of malachite. The mineral (a) seemed, according to the analyses, to be of nearly constant composition, and was considered by Professor Cornwall to be a chrysocolla containing nickel and cobalt—a new occurrence to

Jan 1, 1885

By Bernard Kopelman

The particle size of tungsten metal powder used to make tungsten wire for use in radio tubes and incandescent lamps must be closely controlled if the highly desirable feature of nonsagging is to be achieved. Our knowledge of factors affecting the particle size of tungsten powder has been limited by lack of any extensive literature on the subject. There are no publications in the English language discussing this problem in any but the most general terms. In this paper the published experimental information on this subject is reviewed. Based on the published data and some experimental data obtained by the author, a general theory of factors affecting the particle size of tungsten metal powder obtained by reduction of the oxides in hydrogen is offered. The various forms of the tungsten oxides and tungsten metal used in the experiments described were those prepared by commercial processes, so that the experimental results obtained on a laboratory scale would be more directly applicable to actual commercial reduction conditions. The effects of time of reduction, temperature. and concentration of water vapor in the hydrogen were observed by counting microscopically the particle distribution obtained. Such a method is very time-consuming, but the data obtained by this method are more reliable and more fundamental than those obtained by any of the several instruments available for measurement of particle size. Review of the Literature Until the year 1912, tungsten powder was prepared commercially by reducing tungstic oxide in the presence of carbon or one of its compounds (such as glycerin or ethylene glycol), usually by firing the mixture in a closed fire-clay crucible. The resultant powder contained about 95 per cent tungsten.&apos; When reduction of tungsten oxides by H² was introduced Commercially,²,³ several investigators became concerned with the equilibria between tungsten metal and its several oxides in an atmosphere of hydrogen and water vapor.4-l3 While these many investigations were in fair agreement on the equilibria WO³ + H2 = WO2 + H2O and WO2 + 2H2 = W + 2H2O there arose considerable controversy as to the chemical composition of the oxide between WO³ and WO², because of very poor agreement on the equilibrium constant of this intermediate oxide reduction reaction. The controversy on this intermediate oxide has been in progress for more than 100 years. Thus Malguti,14 in 1835, decided it was WO2.56 In 1857, Riche15 proposed the formula W³O8. Usler,16 in 1865, confirmed the existence of WsO8 and further proposed W1O1l. In 1897, Desil7 agreed upon W²O8 but also found W5O14.

Jan 1, 1947

By Bernard Kopelman

The particle size of tungsten metal powder used to make tungsten wire for use in radio tubes and incandescent lamps must be closely controlled if the highly desirable feature of nonsagging is to be achieved. Our knowledge of factors affecting the particle size of tungsten powder has been limited by lack of any extensive literature on the subject. There are no publications in the English language discussing this problem in any but the most general terms. In this paper the published experimental information on this subject is reviewed. Based on the published data and some experimental data obtained by the author, a general theory of factors affecting the particle size of tungsten metal powder obtained by reduction of the oxides in hydrogen is offered. The various forms of the tungsten oxides and tungsten metal used in the experiments described were those prepared by commercial processes, so that the experimental results obtained on a laboratory scale would be more directly applicable to actual commercial reduction conditions. The effects of time of reduction, temperature. and concentration of water vapor in the hydrogen were observed by counting microscopically the particle distribution obtained. Such a method is very time-consuming, but the data obtained by this method are more reliable and more fundamental than those obtained by any of the several instruments available for measurement of particle size. Review of the Literature Until the year 1912, tungsten powder was prepared commercially by reducing tungstic oxide in the presence of carbon or one of its compounds (such as glycerin or ethylene glycol), usually by firing the mixture in a closed fire-clay crucible. The resultant powder contained about 95 per cent tungsten.&apos; When reduction of tungsten oxides by H² was introduced Commercially,²,³ several investigators became concerned with the equilibria between tungsten metal and its several oxides in an atmosphere of hydrogen and water vapor.4-l3 While these many investigations were in fair agreement on the equilibria WO³ + H2 = WO2 + H2O and WO2 + 2H2 = W + 2H2O there arose considerable controversy as to the chemical composition of the oxide between WO³ and WO², because of very poor agreement on the equilibrium constant of this intermediate oxide reduction reaction. The controversy on this intermediate oxide has been in progress for more than 100 years. Thus Malguti,14 in 1835, decided it was WO2.56 In 1857, Riche15 proposed the formula W³O8. Usler,16 in 1865, confirmed the existence of WsO8 and further proposed W1O1l. In 1897, Desil7 agreed upon W²O8 but also found W5O14.

Jan 1, 1947

By Charles E. Wait

In the analysis of a set of interesting furnace-products belonging to the metallurgical cabinet of the School of Mines, I placed in the hands of one of my students a sample of litharge which gave the results quoted below. The collection of specimens from which this was taken, represents the products obtained in the blast-furnace treatment of argentiferous lead ores, also samples from the zinc process, and those from the cupellation of the enriched lead. The sample, when received, was marked "bismuth litharge," and was that obtained during the last stages of cupellation. It gave upon analysis the following : Per cent. Lead,.......85.36 Antimony,.......06 Bismuth ,........20 Copper,.....49 Iron,...... 69 Zinc,......18 Nickel,.....01 Silver,....2.94 Lime,.....36 Magnesia,....03 Silica,.....12 Sulphuric anhydride,. .32 Carbonic anhydride,. 1.25 Water,.....24 Oxygen,..,.7.80 99.95 At present I wish merely to call attention to the large percetage of silver present (equal to 857 ounces Troy per ton of 2000 pounds avoirdupois), and also to note two or three determinations that I have recently made, with a view to ascertain, if possible, the condition in which this silver exists. If I mistake not, it is usually assumed that silver exists in litharge in the metallic state; and it is, indeed, in the analyses of litharge, rarely expressed otherwise. This method of reporting the silver is, no doubt, due to the accepted statements that the oxides of silver are reduced to the metallic state at a temperature of 300&apos; C. or less. The following experiments lead me to believe that silver exists in litharge, not entirely in the metallic state :

Jan 1, 1887

By B. I. Routh

A STUDY of the effects of temperature on the gel strength of drilling muds is a natural outgrowth of the present era of deep drilling. The control of the gel solids&apos; is now considered important because it affects the wall-building qualities; the suspension of weighting material; the removal and release of sand, cuttings, and gas; and the control of cav-ing formations. With regard to the effect of temperature on gel strengths Herrick2 states: "Temperature variation within ordinary limits does not have much effect on yield points." Lewis, Squires and Thompson3 investi-gated one clay and found no marked change with temperature in either yield point or mobility. Reed4 found that potassium bentonite showed a great increase of gelation with increase in temperature and qualitatively there occurred a marked increase in viscosity upon heating. The apparatus used in these experiments consisted of a Stormer viscosimeter, Marsh funnel viscosimeter, rectangular and cylindrical shearometers, Mudwate hydrometer, and other minor laboratory equip-ment. The various methods of measuring viscosity and gel strength have been extensively described by Evans and Reid.5

Jan 1, 1938

W. P. PUTNAM,. Detroit, Mich.-There is one company that is heating these tubes in an upright position by passing electrical energy directly through the tube itself. The lower connection is attached to an indicator, which shows the point at which the steel passes through the critical range At that point the clamps are released and the tube is dropped into a well of oil. This method simplifies the heat treatment of tubes in long lengths. H. J. FRENCH.-I am not entirely familiar with. the method outlined, but it appears to have one serious disadvantage; that is, the length of tubing that is directly connected with the electrical contacts is wasted and must be cut off due to either heavy oxidation or burning. That is a serious difficulty, if true in all cases, and cannot be overcome, inas-much as it is very difficult to draw long tubes of thin wall. Having once obtained a lot of tubes, to cut, say 14 ft. in length, there is often little excess metal available to discard. Am I correct concerning the burning or heavy oxidation of the metal where it comes in contact with the tube.

Jan 12, 1919

By E. J. Schmitz

This section was obtained last year during an examination of the iron-ore resources of the Rich Patch Mountain region and along Craig&apos;s creek valley. The geological members below the Oriskany and Lower Helderberg are exposed along the gap in a beautiful arch, while the higher formations appear in a more or less disturbed state on both sides of this arch, and are partly covered by dèbris. I have thought it of interest to the Institute to reproduce the drawing of this section at the gap which I made in my note-book at the time of my examination; those parts of the section, which lie at both sides of the arch, are only approximated. I give also a number of notes and measurements, referring to the Clinton formation and especially to the characteristics of the fossiliferous ore-seam opened in the various tunnels along the arch (see section). I. In Tunnel C: For the first 110 to 120 feet to second shute, we find the ore only here and there in small deposits, and interchanging with, or changing into, either a very siliceous limestone or a sandstone. About 10 feet beyond shute we have : Sandstone roof. Clay-slate, 211/2 inches Brown lean ore, 1 inch. Sandy clay, 3 to 31/4 inches. 1. Dark .brown ore, 3 inches. 2. Fossil-ore, changing into sandstone or very siliceous limestone, 2 inches. 3. Brown lean ore, 6 inches. Clay and slate below, 1 foot. 194 feet from entrance : Sandstone roof. Clay-slate, 4 inches. Clay 15 inches. Fossil-ore, 63 to 7 inches. Clay and ore, If inches. Lean brown ore, 2 inchea. Clay to bottom, 2 feet.

Jan 1, 1896

By A. Karim, T. G. Langdon, C. Y. Cheng, J. E. Dorn

The effect of changes in temperature and stress on the creep behavior of Fe-4 pct Si was investigated over the temperature range from 650° to 1175K Over the temperature range of 799° to 110l°K, the shear strain rate, ?&apos;, obeys the relationship: where K is a constant, 7 the applied shear stress, G the shear modulus, g the free activation energy for diflusion, R the gas constant, and T the absolute temperature. The results strongly suggest that the creep in this alloy is controlled by a dislocation climb mechanism. In a recent investigation, Ishida, Cheng, and Dorn1 observed that the apparent activation energy for creep of a! Fe from 480" to 775°K corresponded to that for self-diffusion. Over the magnetic transformation range (775" to 1045"K), the apparent activation energy for creep increased steeply with increasing temperature in agreement with the known decrease in the free activation energy for self-diffusion. Passing through the Curie temperature, the apparent activation energy decreased abruptly following which it then increased mildly as the temperature further increased. Inasmuch as the apparent activation energy for creep of a! Fe below the Curie transformation range of temperatures appeared to decrease with increasing values of the stress, the data were analyzed in terms of a model based on the nonconservative motion of jogged screw dislocations. But since the observed creep rate was much higher than that which could be accounted for on the basis of usual models, the authors found it necessary to assume that pipe diffusion became significant over the lower temperature range. Furthermore, the abnormally high activation energy for creep above the Curie temperature was attributed to grain boundary migration which became prevalent in this temperature range. It was thought that a number of the interesting issues that arose in the creep of a Fe might be resolved by investigating the creep of Fe-4 pct Si alloy: This alloy has about the same Curie range and therefore should give creep results that closely parallel those for a Fe and in this way provide comparable data for analysis of creep mechanisms. Furthermore, it can be annealed at higher temperatures which could provide some stabilization against grain boundary migration. In addition, it might serve to illustrate the possible effects of short-range ordering on creep.

Jan 1, 1969

By H. Foster Bain

In the preparation of this series of books it was considered particularly appropriate to include this work. Gunther was one of the younger men who was associated with Colonel Mudd in the finding and development of ore deposits. Supported by Mudd, Gunther undertook a systematic survey of the sources of copper of ancient Europe. This survey resulted in the rediscovery of the deposits now worked by the Cyprus Mines Corporation for which Gunther was, until shortly before his death, the resident manager. In finding and developing these mines, Gunther applied the methods and data embodied in this book and proved their usefulness. It is believed that other young engineers may profit similarly. In presenting a new edition, the form and substance of this work have been preserved and no changes have been made in any direct statement of the original author. Individual illustrations, paragraphs and mine descriptions appearing in the first edition have been omitted in order to permit introduction of new material. The latter has been chosen so as to present a somewhat more balanced picture of the mining industry as it now exists. The new material relates largely to the so-called porphyry coppers, to mines in Canada, Rhodesia, Alaska, and a number in the United States that have become important since the book was first written. The new material was prepared by Mr. Russell C. Fleming, using the best that had been published and items of which he had personal knowledge or had obtained by correspondence with men familiar with the deposit described. Whenever possible the description used has been submitted to the original author for correction. In a number of instances

Jan 1, 1932

With the signing of the armistice on Nov. 11, the direction of the main concentration of effort of the United States was changed. In order to win the war, all industrial efforts had to be organized and centralized. With the war won and peace in sight, this centralization of effort stopped and the full play of individual initiative was allowed to resume its sway in the community. During this period of reversal of direction of effort, there was a natural loss of momentum and the United States, as well as the rest of the world, is in for a period of readjustment. The immense progress that was made in one direction under the stress of the necessities of war, which focused the energies of a nation in one direction, is an outstanding example of what can be accomplished if a community with many varying interests can be united on one objective which it desires to attain. The realization that the fusing of many interests into one stream of effort is difficult should not prevent us from taking the long view ahead that is necessary in order to be able to measure the progress made. If we don&apos;t have a mountain peak to guide us, we are very likely to run in circles in the plain without reaching the goal to which we strive. The most efficient development of natural resources is an ideal that, from a material point of view, appeals to the engineer. This ideal includes giving of opportunities to everyone to take a share in the development of these resources.. It also contemplates rewarding foresight

Jan 4, 1919

By Leslie F. Tedsen, Alan E. Flanigan, John E. Dorn

IT is necessary occasionally to use aluminum-alloy sheet where moderately elevated temperatures are encountered. Considerable attention has been directed toward determining the influence of "artificial aging" on the room-temperature properties of the precipitation-hardenable alloys, as testified by numerous company reports and by references 1 to 4. Investigations on the properties at elevated temperatures are few, however,5-7 and have not always covered the range of times and temperatures of greatest interest. The present investigation was instituted to overcome this deficiency. The work was done for the Office of Production Research and Development of the War Production Board, under the supervision of the War Metallurgy Committee, as a part of the "restricted" Project NRC-548. It has been released for publication by the Office of Production Research and Development. As is well known, the high-strength aluminum alloys achieve their remarkable properties as a result of precipitation-hardening. In production they are subjected to a solution heat-treatment followed by quenching, to retain the supersaturated solid solution. The solution treatment is followed by "aging" (precipitation-hardening) either at room temperature or at a suitable elevated temperature. A considerable increase in tensile and compressive yield stresses results from precipitation at room temperature ("natural aging"). Through the elevated-temperature process ("artificial aging") it is possible to obtain values of yield stress considerably higher than those attainable by natural aging. The increase in yield stress is accompanied by a smaller gain in ultimate tensile stress and by a decrease in elongation. During [TABLE I.-Sources of Materials Used in the Testing Program MATERIAL ORIGIN AND TREATMENT 24S-T Alclad.... From Lockheed stock. 24S-RT Alclad... Direct from mill. 24S-T80 Alclad.. 24S-O Alclad from Lockheed stock, solution-heat-treated (925°F., water quench) and aged at 375°F. for t0 t % hour. 24S-T8I Alclad.. 24S-T Alclad from Lockheed stock, plant stretched up t0 I per cent and aged t0 ± % hr. at 375°F. 24S-T86 Alclad.. 24S-RT Alclad from Lockheed stock aged 534 ± 34 hr. at 375°F. 6IS-W (bare).... From Lockheed stock. 6IS-T (bare) 6IS-W (bare) from Lockheed stock aged 8 hr. at 350°F. XB7SS-T Alclad. From Lockheed stock.] the first stages of artificial aging the yield stress increases steadily until it reaches a maximum value. In this condition the material is said to be "fully aged." Further exposure results in "overaging," attended by a steady decrease in yield stress. In the production of the artificially aged materials, temperatures and times are selected to achieve full aging. The following important characteristics are associated with the process: I. The higher the temperature, the more rapidly is the fully aged condition attained.

Jan 1, 1945