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By R. E. Hudrlik, G. W. Preckshot

The diffusion coefficients of silver from solid silver in molten lead were measured to within ± 0.8 pet in a columnar type diffusion cell ower, the temperature range of 326° to 530°C. Fick's law describes the process up to 530°C where the laminar mechanism appareltly breaks down. These is negligible resistance at the interface as shown by mathematical analyses. The diffusion coefficients are found concentration independent. IT would seem that diffusion in liquid metals would be free of such effects as molecular structure, dissociation. polarization. and compound formation. This view was taken by Gorman and preckshot in their study of diffusion of copper from solid copper into molten lead. They reported diffusion coefficients which were independent of the concentration over the range of 478° to 750°C. They found that the Stokes-Einstein equation with constant radius of the diffusing specie represented the diffusion data better than Eyring's rate theory equation and Sheibel's correlation. The radius of diffusion was found to be that of the doubly charged copper. There appeared to be no resistance across the solid-liquid boundary. In the present work the diffusion coefficients for silver in liquid lead were measured over a range of temperatures of 350° to 505°C. The solubility of silver in lead over the range of 303° to 630°C was also obtained. These results are compared with calculated or correlated values or with data in the literature. EXPERIMENTAL Procedure—The experimental equipment techniques and procedures were those reported in detail by Gorman and preckshot9 and will not be repeated here. Measured values of WT, Co, A. L were obtained for various diffusion times and the diffusion coefficient was computed for the case of no resistance at the interface9, 11 by: WT/CoAL = 1- 8/p2 n=1 1/(2n - 1)2 exp[-(2n - 1)2p2 Dt/4L2] [1] or where there was resistance at the interface by: WT = 1- ?n=1 2h2/ap2L [sxp [-Dan2t]/[(h2 + an2) L + h] The roots an are those of the transcendental equation3 tan (an L) = Iz/cun. The diffusion coefficient is that defined by Hartley and Crank.7 The total silver in the lead cylinder and equilibrium slug was determined by a cupellation technique' with proper correction for losses. Analysis of known samples showed that this method is surprisingly accurate. The amount of silver in the lead adhering to the silver cylinder was obtained in the same fashion as shown by Gorman and preckshot.9 The small errors involved in this determination are not critical since the silver in this adhering lead layer is only 3 to 15 pet of the total diffused. Materials—Electrolytic silver containing 99.9+ pet Ag obtained from General Refineries of Minneapolis, Minn. was used for all but runs 7 and 8. For the balance of the runs this silver was reduced with hydrogen at 1100°C and its oxygen content was found to be about 0.017 pet. For the runs. 7 and 8, phosphorous-reduced silver of the same purity was obtained from Handy and Harman Co. of Chicago, Ill. The densities of the phosphorus-reduced silver and the hydrogen-reduced electrolytic silver were 10.484 and 10.487 g per cm3, respectively. These values agree with those reported for pure silver. Silver which was reduced at 900 C had an average density of 9.998 g per cm3, indicating porosity. This silver was used for a number of runs which were not tabulated in Table I. These are indicated by crosses on Fig. 2. The 99.999 pet Pb was obtained from the National Lead Co. Research Laboratory of Brooklyn, New York. DISCUSSION OF RESULTS The diffusion and solubility results are reported in Table I for eleven runs using either phosphorus-reduced electrolytic silver or hydrogen-reduced silver at 1100° C. The solubility data shown in Fig. 1 show the excellent agreement with that reported by Heycock and Neville.8 The data of Friedrichs5 apparently are in error. The experimental solubility data of this work are reported to 0.3 pet. The experimental diffusion coefficients computed from Eq. [1] are reported within 1.2 pet of the mean and are plotted in Fig. 2. These are expressed within +0.8 pet of the experimental values over the entire temperature range by: D= 8.26 x 10 -5 e-1925/RT . [3] There appears to be little difference due to the

Jan 1, 1961

A dinner was given to Ambrose Swasey by the United Engineering Society, at the Engineers' Club, on November 14. Those present -included -twenty-one presidents and past presidents of the Founder Societies. Charles F. Rand, President of United Engineering Society, presided. President Robert S. Woodward, of the Carnegie Institution of Washington, and Dr. Robert W. Hunt, of Chicago, made addresses to which Mr. Swasey responded. Dr. Michael I. Pupin, Chairman of Engineering Foundation, made the closing address. The evening was marked by the high character of the addresses, inspiration for grave duties lying before the engineering profession, and by the spirit of good fellowship. Among the seventy-two persons present were the following members of the Institute: E. E. Bartlett, William N. Best, J. Parke, Channing, C. R. Corning, F. C. Cottrell, J. V. Davies, J. V. N. Dorr, H. S. Drinker, Karl Eilers, H. M. Howe, A. C. Humphreys, Robert W. Hunt, Wm.. B. Jackson, D. S. Jacobus, J. H. Janeway, J. E. Johnson, Jr., John Johnston, George F. Kunz, Edwin Ludlow, Philip N. Moore, Fred'k. H. Newell; Wm. H. Nichols, H. Hobart Porter, Charles F. Rand, R. M. Raymond, .Jesse M. Smith, E. Gybbon Spilsbury, Bradley Stoughton, . Joseph Struthers, Benj. B. Thayer, Wm. H. Wiley, S. T. Wellman.

Jan 1, 1919

By Edward Gridley

At the meeting of the Institute, held at Roanoke, Va., in June, 1883, I gave some facts in relation to charcoal pig iron of unusual strength, made from our carbonate ore taken from the mine at Amenia, N. Y. My object in again bringing the subject to the attention of the Institute, is to obtain, if possible, the solution of a prohlem in connection therewith. Our furnace is of the old type, stone stack 32 feet high by 9 feet 2 inches at top of bosh; bosh about 67O pitch; stone hearth; three tuyeres of 31/4-inch opening; fuel, a mixture of hard and soft coal; blast about & to # pound pressure, and heated to 400' to 600° Fahr. by iron pipe oven on top of stack. The analysis of the roasted carbonate ore, as before given to the Institute, is as follows:

Jan 1, 1884

THE sessions of the Institute were opened on Tuesday evening, October 26th, at Garrett's Hall, by Mr. Charles A. Otis, Chairman of the Local Committee of Arrangements, who welcomed the Institute to Cleveland, and introduced Col. Charles Whittlesey, who ad¬dressed the Institute briefly on the coal deposits of Ohio. Col. Whittlesey described the situation and character of the coal-beds of the State, and gave a short history of the use of raw coal in the manufacture of pig-iron, and spoke of the excellent quality of metal produced. The aid that a body of scientific miners and metal¬lurgists were capable of giving in the development of coal and other mineral resources was dwelt upon, and the hope expressed that the visit of the Institute to Cleveland might be profitable as, well to its members as to the citizens of the State. The President, Mr. A. L. Holley, responded to the welcome of Mr. Otis and of Col. Whittlesey, and read an introductory address on Some Pressing Needs in the Iron and Steel Manufacture. The following members and associates, duly proposed and indorsed by the Council, were then elected MEMBERS. Alfred S. Bertolet, - Youngstown, Ohio. Henry Binnse, - Chicago, Ill. John Birkinbine, - Philadelphia. Andrew A. Blair, - Watertown Arsenal, Mass. Ogden Bolton, - Canton, Ohio. Lloyd Booth, - Youngstown, Ohio. E. Borda, - Philadelphia. N. P. Bowler, - Cleveland, Ohio. Alexander E. Brown, - Cleveland, Ohio. C. F. Brush, - Cleveland, Ohio. S. M. Carpenter, - Cleveland, Ohio. James Cartwright, - Youngstown, Ohio. Henry Chisbolm, - Cleveland, Ohio. Wilson B. Chisbolm, - Newburgh, Ohio. W. H. Clarke, - Millertown, Pa. James E. Clayton, - Ore Knob, N. C.

Jan 1, 1876

The sessions of the Institute were opened on Tuesday evening, October 26th, at Garrett's Hall, by Mr. Charles A. Otis, Chairman of the Local Committee of Arrangements, who welcomed the Institute to Cleveland, and introduced Col. Charles Whittlesey, who addressed the Institute briefly on the coal deposits of Ohio. Col. Whittlesey described the situation and character of the coalbeds of the State, and gave a short history of the use of raw coal in the manufacture of pig-iron, and spoke of the excellent quality of metal produced. The aid that a body of scientific miners and metallurgists were capable of giving in the development of coal and other mineral resources was dwelt upon, and the hope expressed that the visit of the Institute to Cleveland might be profitable as well to its members as to the citizens of the State. The President, Mr. A. L. Holley, responded to the welcome of Mr. Otis and of Col. Whittlesey, and read an introductory address on Some Pressing Needs in the Iron and Steel Manufacture. The following members and associates, duly proposed and indorsed by the Council, were then elected MEMBERS. Alfred S. Bertolet,.. .. . Youngstown, Ohio. Henry Binnse,. Chicago, Ill. John Birkinbine,.. .. . Philadelphia. Andrew A. Blair,. .. .. Watertown Arsenal, Mass. Ogden Bolton,. .. .. Canton, Ohio. Lloyd Booth,..Youngstown, Ohio. E. Borda,..Philadelphia. N. P. Bowler,.. .. . Cleveland, Ohio. Alexander E. Brown,.... Cleveland, Ohio. C. F. Brush,.. .. .Cleveland, Ohio. S. M. Carpenter,.. .. . Cleveland, Ohio. James Cartwright,.. .. . Youngstown, Ohio. Henry Chisholm,.. .. . Cleveland, Ohio. Wilson B. Chisholm,.. .. . Newburgh, Ohio. W. H. Clarke,.. .. . Millertown, Pa. James E. Clayton,. .. .. Ore Knob, N..C.

By E. R. Gilbert, D. E. Munson

Creep of copper under 75 to 1.50 kg per sq cm stresses at temperatures near the melting point was found to he a complex reaction controlled by three mechanisms acting in parallel. In order of appearance with decreasing temperature, the auerage activation energies, Qc , are 168, 79, and 24 kcal per mole. Stress dependence of the minimum creep rate was found to he an exponential for the two high-Qc processes and a power law for the low-Qc, process. Transition of control occurs from one mechanism to another. The relative transition temperature depends upon the applied stress, and the range oiler which the transition occurs depends upon the difference in the activation energies of the mechanisms. The creep behavior at high temperature is explained by the climb of dislocations through thermally or mechanically formed jogs, CREEP in pure fcc metals at temperatures in excess of one half the absolute melting point is normally controlled by dislocation c1imb.1,2 A climb model which seems applicable, according to an extensive analysis of data,3 was derived by Weert-man.4 This model assumes jog-saturated dislocations and predicts an activation energy, Qc, nearly equal to that for self-diffusion, USd. Although the requirement of jog saturation is restrictive, agreement between theory and experiment seems adequate. Many other theoretical treatments, including an early model by Mott,5 include detailed consideration of jog formation as an initial requirement for climb. These models predict activation energies for creep which differ from those of self-diffusion. Seeger6,7 postulates an observed activation energy related to the stacking-fault energy. Thus, Usd <Qc<5Usd + Uj where Uj is the jog-formation energy. Seeger incorporated qualitatively the influence of the relative numbers of thermal and athermal jogs. Expanding this concept, Shoeck8 explicitly states a function based on formation mode and relative numbers of vacancies: e r ci exp {-uf/k T} exp {-Um/k T} [ 1 ] where Uf and Um are energies of vacancy formation and migration, respectively. The concentration of jogs, Cj, depends upon the manner of jog production. For intersection jogs, Cj is not sensitive E. R. GILBERT, Junior Member AIME, formerly with De- to temperature; for thermal jogs, Cj is proportional to exp {—Uj /k T}. Schoeck regards each mode as a distinct mechanism; therefore, the mechanisms may act together.299 The diversity predicted by theory, surprisingly, has not been substantiated by experimental results. A significant investigation must include the extremes in stacking-fault energy. Extensive creep studies of aluminum10 and nickel,11,12 high stacking-fault energy metals, have been made. Comparable studies on a low stacking-fault energy metal, such as copper, have not. It is the purpose of this paper to report the results of an investigation of the creep of copper under conditions which favor thermal jogs. EXPERIMENTAL Cylindrical compression creep specimens (0.240 in. in diameter by 0.400 in. long) were machined from cold-drawn rods of electrolytic tough-pitch copper containing 0.0007 Mg, 0.002 Fe, 0.001 Ni, 0.0005 Ag, Cd < 0.005, and Pb < 0.005 wt pct impurities. Undetected spectrographically was a nominal 0.04 wt pct 0, which occurs as a Cu2O constituent distributed discontinuously at grain boundaries. Vacuum annealing at 900°C for 15 min produced a stable 0.03-mm average grain diameter. Testing was carried out using apparatus similar to that described by sherby,13 modified by enclosing platens and a push rod in a vacuum cylinder. Normally this arrangement resulted in pressures less than 10 Only a slight surface tarnish, less than 0.0005 in. in thickness, occurred during the test. The applied stress, corrected for atmospheric pressure, was maintained within 2 pct of the desired true stress by the addition of lead shot at fixed strain increments. Creep strain was measured with dial gages as a relative displacement of the upper and lower platens; accuracy of measurement was 0.0001 in. Two creep-test methods were used, the differential or cyclic temperature14 and the isothermal, to obtain creep data at stress levels of 150, 100, and 75 kg per sq cm over the temperature range of 620° to 1032°C. Minimum creep rates were used from both test methods; this was considered proper because comparable temperature tests or cycling to the same temperature gave the same creep rate, within experimental error. The cold vacuum test chamber, with the unstressed specimen in place, was heated to temperature by placing a preheated furnace over the chamber. Temperature equilibrium was attained within 30 min. For the cyclic tests, the stress was removed during the 5 to 10 min necessary to effect the temperature change and re-

Jan 1, 1965

By B. G. Klugh

(New York Meeting, February, 1913.) THE present paper represents a preliminary investigation of the ultimate structure of iron-bearing materials which have been subjected to heat treatment for the purpose of agglormer-ating the fines, or for chemical changes, or for both. Primarily, the object of this inquiry was to determine the relation of the microstructure of each of these materials-to its specific susceptibility to the action in the blast-furnace. It is hoped that this small contribution will serve as a nucleus to a line of research that will throw some light upon the debated questions involved in blast-roasting. Thus far the investigation has been conducted along lines of analogy of known principles, rather than through the applica-tion of any well-defined system of microscopic petrography. This is obviously due to the fact that we are dealing with materials which are the artificial products of a new art, rather than with the natural materials from which the essence of the pure science has been evolved. In the limited tune allowed for this research, it has been conducted upon those materials the chemical content of which allows of their use commercially in the blast-furnace.

Jan 5, 1913

By AIME AIME

BECAUSE of its unequalled skill, your country in- creased its production until, in 1913, it produced 40 per cent. of the world&apos;s consumption of coal, iron ore, and cast iron; 45 per cent. of the steel; and 60 per cent. of the copper. Your industrial effort, in a general manner and your mining effort in particular, has been tremendous. In the general economy of the world, you occupy an incomparable position of power and action. All your curves of production, mineralogical, metallurgical, financial, commercial, have taken terrific trigonometrical tangents and you will easily under- stand the sorry position of your competitors. I must, therefore, pay a tribute of homage arid admiration to you all who, each in his sphere, have been the artisans of such prosperity and my earnest wish is that you continue in this way.

Jan 1, 1920

By AIME AIME

THE revised program for the San Francisco meeting, with assignment of the various papers to the several sessions is now available and is printed below : MONDAY, OCT. 7 . General Meeting, 11-12 A.M. Chairmen: Frederick W. Bradley and E. A. Hersam. Opening of the session by the Chairman of the San Francisco Section-E. A. Heraam. Address of welcome by the President of the Institute- Frederick W. Bradley. Address: The Mining problems of the West--Charles W. Merrill.

Jan 1, 1929

By H. W. Hardinge

DISREGARDING for the present the economic side of a new device, let us turn to that feature of the conical pebble-mill which is of interest from a scientific point of view, and consider the device as a puzzle in which the theories of the cylindrical type of mill have been increased. Many articles have been written on the theory of the tube-mill, and explanations have been made which do not explain.; but these have evolved suggestions of practice which have resulted in changes in the tube as to length, diameter, feed, discharge, speed of rotation, rotation on hollow trunnions, rotation on rings, and changes in the operation as to quantity and size of pebbles, charge of load above or below the axis, crushing by causing the larger pieces of the material of the charge to act as grinders, etc. The practical worker in crushing is first interested in the endeavor to reach an economic means of accomplishing a desired end; but the improvements in crushing-practice have been largely left to the manufacturer of machinery, who, as a rule, has little, if any, knowledge of the specific requirements-such as sizing for concentration without pulverizing the metals, instead of pulverizing the rock or gangue; the metals being the more friable, while the rock is tough and not so easily disintegrated. A reversal of this practice is the aim of sliming direct for cyanidation. In the ordinary cylindrical mill, having a diameter of 4 or 5 ft. and a length of from 15 to 27 ft., it has been found that the maximum size of the particles of the charge must not exceed 1 mm. (about 25 mesh), some of which, upon entering the mill, is immediately reduced to a slime. The work upon the individual particle having been finished, it should be passed out of the mill; but, instead of this, the finely comminuted material

Jan 7, 1908

By Christopher G. Atwater

The object of this paper is to describe and discuss the progress that has been made, up to the present date, in the development of the modern by-product coke-oven. There are few members of the Institute who have not heard more or less of the by-product oven-installation, and there are many whose acquaintance with it is intimate and practical. Since the general opinion on the subject has hardly become crystallized as yet, it is hoped that this paper will at least furnish matter for discussion. In order to obtain an idea of the present status of the industry in the principal iron-producing countries, the following table has been prepared : Table Showing Proportion of Coke Made in By-Product Ovens in Various Countries. United Kingdom (1898, Mr. George Beilby). Short Tons. Per Cent. Coal coked in by-product ovens,. .. 1,400,000 7.9 Coal coked in blast-furnaces with by-product recovery,.......2,240,000 12.7 Coal coked in non-by-product ovens,. . 14,000,000 79.4

Jan 1, 1903

By James F. Kemp

Discussion of the paper of D. Foster Hewett, Bulletin To. 27, March, 1909, pp. 291 to 310. JAMES F. KEMP, New York, N. Y.:-Mr. Hewett&apos;s paper is one of exceptional interest, because it not only adds an important contribution regarding one of the rarer, valuable elements, but also because it introduces compounds hitherto unknown and in associations no less novel. While we have occasionally dis¬covered and recorded asphaltite in metalliferous deposits, for example in the Joplin and Granby districts, we have not seen a metallic ore in a deposit essentially asphaltite. The source and method of introduction afford a subject well worth serious reflection. Vanadium was first discovered and recognized as a distinct element in the slags obtained in smelting the titaniferous magnetites at Taberg, Sweden. For a long time, therefore, we looked upon the titaniferous magnetites as its hone. Analyses proved, years ago, that it was present in the ores of this type in New Jersey and in the Adirondacks. It was quite rarely determined, but when looked for it was, I think, invariably found, although the Amount seldom exceeded 0.5 per cent. of V,05., In just what combination it exists in the titaniferous ores is uncertain. One might imagine V2O3 replacing some of the Fe2O3 of magnetite; or, since in the lead series vanadates and phosphates are closely akin, one might wonder if a lime-vanadate could take the place of apatite. Yet no lime-vanadate has been found in nature, and apatite itself is usually rare in the titaniferous ores. When percentage-curves are plotted for a series of analyses of the ores, the line of vanadic oxide shows a curious sympathetic behavior with the line of chromic oxide;&apos; but the data are somewhat limited, and no compound has sug¬gested itself which throws light on the matter. Dr. W. F. Hillebrand has discussed the occurrence and dis-

Oct 1, 1909

John A. Church, New York City: It requires some courage to appear as a critic of a theory which is not only the fashion among American geologists but is usually presented by them in terms which imply that any other views are an exhibition of ignorance. Still, I am obliged to say that the theory of lateral secretion as it is stated in this and other writings of Mr. Emmons and other geologists has not added much to our real knowledge or clearness of view. In the earlier and less developed stages of the theory, when it was used as Sandberger used it, to show that certain veins were probably derived from the rocks in which they lie, or which are adjacent, it was valuable in pointing us to an immediate source of ore-deposition. When we are driven to assume the existence of undiscoverable rocks at an unknown but certainly a considerable distance and in an unknown direction from the vein, I do not see that we have improved upon the despised " unknown source in depth " with which our ignorance has been covered so long. The new theory may suffer from adolescence, and these points map be cleared up by further study, but I speak of it as it is. Differentiation in a magma, by which a metal is concentrated in one member of a series of outflows, may explain why certain ores have favored a given locality with their presence; but it is not a necessary precedent to ore-formation. Concentration in the source of supply cannot be a requirement, for the forces that have been able to take up four or five tons of gold from an extensive body of rock must be able to collect four or five thousand tons of lead, copper or nickel from a proportionately more extended body of rock. That is to say, concentration is no more essential for these metals than it is for gold. In fact, differentiation, as it is now explained, is not an advance upon old ideas, but a retreat from them. It was noticed long ago that violent eruptive phenomena, however long continued, died away in solfataras; and when a vein came to be looked upon as an extinct solfatara the inference was ready that veins are eruptive in the sense that the solfataric waters collected the metals from the unerupted residue of the magma and carried them to the veins. The early views carried differentiation further than the modern school.

Jan 1, 1894

The notion prevails that writing is a knack, that the skilful use of the pen is a gift of nature. This is an error. Dogberry may be responsible for it; he said: "To be a well-informed man is the gift of fortune, but to write and read comes by nature". Because Dogberry said it, we may be sure that Shakespeare thought otherwise. Ability of any sort may be partly innate, but my own observation and experience lead me to conclude that most of the easy writers have become so by constant practice. As I recall the names of men successful with the pen, I remember that most of them have written a great deal and have taken particular pains to improve their style. The suggestion that proficiency in the difficult art is a happy accident provokes a sardonic smile. The larger part of the great writing in our literature is the result of persistent effort. An easy fluency has been the undoing of many; their flamboyant and fantastic scribbling has proved as perishable as froth. This criticism applies to technical writing also; in order that a technical description or discussion may hold the interest of the reader, at least long enough to cause him to read it to the end, the writing must be done carefully and systematically; otherwise it will fail in its purpose of conveying information. Clearness is absolutely essential. "It is not enough to use language that may be understood; it is necessary to use language that must be understood."* The purpose of writing, at least of that which is meant to be read by others, is not only to express ideas but to communicate them. Lack of perspicuity may prove as bad as

Jan 1, 1931

By B. B. Zavoico

During 1936 the Russian oil industry made very satisfactory progress and, while not all difficulties of organization have been ironed out, the country is now assured of a supply of petroleum products in sufficient quantities and of quality demanded by modern motor equipment. The year 1937 promises to better by a wide margin the good showing of 1936. The statistics given in this paper for the first time take into consideration the varying gravities of crude oils of the several Russian oil fields instead of using a flat conversion factor of 7 bbl. per metric ton. It was found from the detailed study that the generally used average conversion factor should be increased from 7 to 7.25 bbl. per metric ton, the figure varying, of course, with the gravity of oil in the individual fields. Crude-oil production during 1936 is estimated at 201,500,000 bbl. as compared with 182,970,000 bbl. produced in 1935, an increase of 9.4 per cent. The greatest increase was again recorded in the Baku district, which increased its production by 10.9 per cent, from 141,257,000 bbl. in 1935 to 158,300,000 in 1936. Grozny district maintained its production at a level of about 23,000,000 bbl., but its old fields continued to decline and production was sustained by the development of newer fields. A great advance was made in drilling speeds and the total footage in 1936 reached 6,694,200 ft. as compared with 4,926,600 ft. drilled in 1935, an increase of 26.4 per cent. In older deep fields, producers were being completed at over 8000 ft.—a great depth for Russian drillers but two years ago. Several major discoveries were made in 1936. Northeast Caucasus.—Izberbash, east from Grozny and on the Caspian Sea, was the outstanding discovery, the initial production of the discovery well being around 3000 bbl. per day from about 5000 ft. The importance of the field is due to the large area of the structure, half of which, however, is under the sea, and also to its strategic location on the shores of the Caspian and near a trunk pipe line to the Grozny refining center. An active development program is being pursued in Izberbash and its 1937 production quota is set at 7,500,000 bbl. Achi-Su field, near Izberbash, also discovered during 1936, while not as prolific as Izberbash, is thought to cover a very large area and the small

Jan 1, 1937

By A. T. English

X-ray dif action techniques were used to investigate ordering and domain coalescence for the B2 (CsC1) superlattice in this alloy. Essentially complete disorder is obtainable by drastic quenching. isothertmal ordering occurs very rapidly at temperatures between 565° and 680°C, only a few seconds being required for development of substantial long-range order. A very fine antiphase dormain structure, found in samples annealed for short times, undergoes coalescence with further annealing. Domain "size" is found proportional to (t)1/2 . This Yate law can be derived by adapting the formalism of Hillert&apos;s analysis 01- metallurgical grain growth. For this Purpose the material is descvibed in terms of a "Swiss-cheese " structure, consisting of two multiply connected, mutually intertwined domain volumes. The observed activation enevgy for coalescence, 70 kcal per g-atom, agrees with an estit~lated value ,for volume diffusion in disordered rrzaterial. It is suggesled that the experimental value vejlects the substantially disordered environment of mobile vacancies located in the moving antiphase domain boundary. The alloy Fe-Co-2V is bcc below about 900&apos;C and orders into a B2 (CsC1) superlattice below about 730c It has important applications in magnetic components, including many requiring extensive cold rolling.* example, Marcinkowski and Brown6 observed a re1atively small as-quenched domain size of about 250Å in B2 Fe3A1. Since there appear to be no published data on domain coalescence in B2 alloys, this process was studied in detail. MATERIALS AND EXPERIMENTAL TECHNIQUES A commercial high-purity alloy, nominally 49 Fe-49Co-2V, was obtained from the Arnold Engineering Co. in the form of cold-rolled sheet 0.004 in. thick. Samples were annealed for 1 hr at 800°C in dry H2 to produce disorder and quenched into iced brine. They were then annealed in a nitrate-nitrite salt bath for various times at temperatures between 525° and 625°C. Estimates of the LRO parameter S and the APD size D were made using established X-ray diffraction techniques. Superlattice peaks are best observed using CoKa radiation, for which the value of (fFe-fCo) is maximized. Peak-to-background intensity ratio was improved by filtering CoKß from the incident beam to eliminate sample fluorescence, and by using a pulse-height analyzer. The LRO parameter S was computed from the ratio of integrated intensities I 100/I 200- Owing presumably to systematic errors associated with the presence of crystallographic texture and X-ray extinction, only rough agreement was obtained between experimental and theoretical (absolute) intensity ratios. For this reason certain experimental refinements (e.g., use of balanced filters) were considered superfluous and were omitted. Emphasis was placed on maximizing intensity in order to reduce the time taken to accurately determine the contour of the very small (loo), peak. This was done by point counting 105 counts at appropriate intervals. Background intensity averaged about 1200 cps.

Jan 1, 1967

By Frederic Carter

THERE have been many attempts to prove that platinum was known to the ancients, but since no traces of the metal have been found in the relics of early times, it must be concluded that it had not been known to them. As far as records go, it was actually first discovered in the 16th century in a Spanish mine on the Pinto River in South America; from which source it received its name of Platina del Pinto (little silver from the Pinto). It was more or less of a rarity and was a subject of interest to a few chemists only, until the year 1822 when the metal was first discovered in Russia. In 1819 there had been noticed in the washings of the gold sands of the southern part of the Ural Mountains, grains of a heavy white substance, but it was not until three years later that this substance was found to contain platinum. While at first the amounts of platinum brought from the Urals had been meager, prospecting soon disclosed rich deposits extending over a considerable area, and nuggets from 10 to 20. lb. were by no means rare. This discovery assured to chemists an ample supply of platinum for their crucibles, etc. The ore is now found in various parts of the world but the richest deposits are still found in the Ural Mountains. The platinum of commerce is obtained entirely from alluvial deposits at depths varying from 6 to 40 ft. The sand and gravel of former river beds are subjected to a series of screenings and washings to effect the separation of the ore. Actually, probably all gold-bearing gravel beds of the world contain platinum, and it is more than likely that large quantities of platinum ore have been thrown away with the black sand washings from gold placer deposits. This is especially true of the alluvial deposits of the Pacific Coast in California and Oregon. Platinum ore is usually found in the form of rounded or, flattened grains of "sand," and occasionally in irregular lumps of the size of peas. Large nuggets are very rare. The ore has a metallic luster and is distinguished by its steel gray color, but shows light gray streak when rubbed on a hard white surface; it has a high specific gravity, 16 to 19; is infusible in the hottest blast furnaces, and insoluble in any single acid. Platinum ore is a complex body consisting of the metal in combination with varying proportions of the other members of the platinum group; iridium,

Jan 1, 1928

By Hans Lundberg

N OT so long ago, the discovery of an orebody took place only by accident. At the present time mineral deposits, even though concealed, may be revealed by their physical or geophysical characteristics, considered in connection with geological studies. Geophysical methods are based on sound, scientific principles and in no sense partake of the mysteries of "divining-rod " methods. Geophysical methods are divided into two main groups: Group I: Methods where fields of force surrounding mineral deposits are investigated (magnetic, gravitometric, electric) ; Group I1 : Methods where fields of force are applied (produced) and anomalies caused in these fields by mineral deposits are recorded (electric, seismic). By methods belonging to Group I, the investigation of the fields of force may be brought to an astonishing degree of accuracy by means of highly sensitive and delicate apparatus (torsion and magnetic balances) ; at least, in simple cases these methods have proved to be of great value.

Jan 1, 1925

By E. R. Morgan, J. C. Shyne, V. F. Zackay

NITROGEN used as an alloying element in steel has received increased attention in recent years. Its merit as an austenite stabilizer and hot strengthener has long been recojinized, particularly by European investigators.&apos; Recent work&apos; indicates that nitrogen contents of 1/2 pet or more allow the addition of several percent of ferrite-forming hot strengtheners, such as molybdenum, without subsequent austenite decomposition at elevated temperatures. The room temperature properties of such alloys are characterized by high yield and tensile strengths with excellent ductility, even after cold working, as shown in Tables I and 11. The 1350°F creep-rupture properties of Cr-Mn-Mo-N steels are comparable to those of commercial alloys such as Timken&apos;s 16-25-6, containing 16 pct Cr, 25 pct Ni, and 6 pct Mo, as shown in Table 111. Cr-Mn steel containing 1/2 pet N must be made under pressure if ingot gassing is to be avoided. However, there are difficulties attendant to this practice. Pressure melting restricts the ingot size, and the equipment required is costlier and more complicated than comparable air melting facilities. An effort was made, therefore, to determine more economical methods of adding nitrogen. The pressures generated in centrifugal casting usually range from 5 to 10 atm and are sufficient to prevent the gassing of high nitrogen Cr-Mn steels. A centrifugal casting was made of an alloy containing 16 pct Cr, 18 pct Mn, 2 pct Mo, and 0.73 pct N. A risk, 8 in. diam and 11/2 in. thick, was cast at 1000 rpm. It has been calculated that a pressure of 9 atm was developed at the periphery of the disk at this speed. Metallographic inspection of specimens taken from the disk revealed no gas holes or other defects. The elevated temperature properties of radial and circumferential specimens taken from this casting are given in Table IV. The creep-rupture life of this cast nickel-free austenitic steel was equivalent to that of the wrought Cr-Mn-Mo-N steels. Although centrifugal casting appears to lend itself to the manufacture of high nitrogen austenitic steels, its applicability is limited to relatively small sizes. A process applicable to the production of large ingots of high nitrogen steels is suggested by low carbon rimming steel practice. Gas holes formed during ingot solidification are not detrimental so long as they weld shut during hot rolling. An economic advantage of gassing ingots is the increased ingot-to-slab yield, especially if the ingots are mechanically capped. Also, it is probable that higher nitrogen levels can be achieved with mechanically capped ingots than with hot-topped ingots. A series of gassy heats was made under both atmospheric and higher pressures, as indicated in Table V. Several of the air melted ingots were mechanically capped by chilling the molten ingot tops with a steel plate. The ingots were allowed to freeze in steel molds without hot-tops unless otherwise indicated. A comparison of Table 111 with Table V shows no significant difference in the creep-rupture properties of the gassy and the nongassy ingots after hot work- ing nor between the gassy ingots produced under different conditions. References 1 F. Rapatz: Application of Stainless and Heat Resisting Steels Alloyed with Nitrogen. Sinhl and Eisen ( 1941) 61, pp. 1073-1078. &apos;V. I?. Zackay, J. F. Carlson, and P. L. Jackson: High Nitrogen Austenltlc Cr-Mn Steels. Trans. ASM 119551 48, PP. 509-523.

Jan 1, 1957

The Geological Society of America, 419 West 117th St., New York, N. Y. Charles-P. Berkey, Secretary. The only official publication of the Society is the Bulletin. It contains the Proceedings of the annual meeting of the Society, as well as the Proceedings of the affiliated societies?the Mineralogical Society of America, and the Paleontological Society?and of Section E of the American Association for the Advancement of

Jan 1, 1933