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By T. Sterry Hunt

THERE are about sixty bodies which chemists call elements ; the simplest forms of matter which they have been able to extract from the rocky crust of our earth, its waters, and its atmosphere. These substances are distributed in very unequal quantities, and in very different manners. As regards the frequency of these elements in nature, neglecting for the present those which constitute air and water, and confining ourselves to the solid matters of the earth's crust, there are a few which are exceedingly abundant, making up nine-tenths, if not ninety-five hundredths, of the rocks so far as known to us. The elements of which silica, alumina, lime, magnesia, potash, and soda are oxides, are very common, and occur almost everywhere. There are others which are much rarer, being found in comparatively small quantities. Many of these rarer elements are, however, of great importance in the economy of nature. Such are the common metals and other substances used in the arts, which occur in nature in quantities relatively very minute, but which have been collected by various agencies, and thus made available for the wants of man. It is chiefly of the well-known metals, iron, copper, silver, and gold, that I propose to speak to-night; but there are two other elements not classed among the metals, which I shall notice for the reason that their history is extremely important, and will, moreover, enable us to comprehend more clearly some points in that of the metals themselves. I speak of phosphorus and iodine. You all know the essential part which the former of these, com- * An address before the Polytechnic Association of the American Institute, during the meeting of the American Institute of Mining Engineers in New York. Printed in this volume by request of many members.

Jan 1, 1873

By Thomas T., Read

IT will be recalled that when educational instruction for the mineral industry began at Freiberg, at the beginning of the eighteenth century, the original aim was to organize and systematize the procedures previously followed by young men in gaining -familiarity with the technology then in use. There must have been many other ideas current, even then, as to just what a young man needed to learn in order to become capable of assuming 'responsibility for the supervision and direction of such technical work. The problem in Europe was decidedly different .from that in nineteenth-century America, because some of the European mines were actually owned and operated by the governing authority and the others were supervised, regulated, and taxed by it. The American problem was the e5cient performance of technical operations; the European one was regulatory supervision. It was natural, therefore, that in the development of educational processes in Europe stress was laid on those factors which conserved and protected the interests of the state. The study of mineralogy and geology, leading to correct judgments as to the workability and value of mineral deposits; assaying, which gave the means of quantitative measurements, as did surveying; chemistry, which furnished a better basis of understanding for assaying, mineralogy, and geology; and physics and mathematics, which are the bases for the understanding and efficient use of mechanical appliances, became the core of systematic instruction, for the mineral industry. It was early recognized that men could learn more than was already known about all of these subjects and education took on that dichotomy which still characterizes it; the teaching of established knowledge to the unlearned, and that of extending of the bounds of knowledge, now loosely termed research, which after two and a half centuries of work still shows

Jan 1, 1941

By G. T. Jackson

The Alaska Gastineau Mining Co.'s mine is located at Perseverance, about 4 mi. east of Juheau, Alaska. Its property consists of a group of claims, the lode system traversing these claims for a distance of 11,000 ft. (3352 m.). It is shown in Fig. 1. The ore deposits occur in what is known as the Juneau gold belt. This gold belt can be traced for about 50 mi. northwest of Juneau and 40 mi. southeast. It consists of a single band, several hundred feet wide, in which stringers and veins of quartz, carrying gold, occur in a slate formation near its contact with some altered volcanic rock known as greenstone. The Perseverance orebody consists of stringer lodes, having a strike northwest and southeast, dipping about 60° to the northeast. These

Jan 1, 1920

By Open-Hearth Steel

We have a very high-powered organization up here this morning, headed by Kenneth C. McCutcheon, general superintendent of the Ashland Division of the American Rolling Mill Company, and L. A. Lambing, superintendent of the open-hearth and Bessemer departments of Jones & Laughlin Steel .corporation of Aliquippa, Pa., representing the open-hearth men. Also, we have P. F. Dolan, assistant general manager of the Maryland plant of Bethlehem Steel Company, of Sparrows Point, and Harry E. McDonnell, superintendent of blast furnaces of Weirton Steel Company of Weirton, W. Va., representing the blast-furnace section.

Jan 1, 1940

By W. C. PAGE

ALL mine ore here must be concentrated before shipment, which involves selective flotation. Three products are made: lead, zinc, and pyrite concentrates. The equipment and practice are so well outlined in the accompanying flow sheet that only a few amplifying remarks are necessary. After crushing at the mine to approximately 4 in., the ore is carried by aerial tram about 4 1/2, mi. to the mill. From 1800 to 2000 metric tons per day, excluding Sundays, is thus transported. At the mill, the buckets are hand-tipped into the bins. After crushing to pass a ¼ -in. square opening, the ore may be stored in reserve crushed-ore bins or ball-mill feed bins as desired. Total bin capacity at the mill is about 4000 metric tons. The concentrator is arranged in three independent grinding sections, each fed from its own storage bin. Grinding operations follow standard practice, with ball mills in single-stage closed circuit with classifiers, the overflow from which is delivered to the lead circuit rougher flotation machines,

Jan 1, 1936

MRS. SIDNEY J. JENNINGS, President, MRS. ARTHUR S.. DWIGHT, First Vice-President, MRS. KARL EILERS, Second Vice-President, MRS. H. W. HARDINGE, Third Vice-President, MRS. BRADLEY STOUGHTON, Recording Secretary, MRS. AXEL 0. IHLSENG, Corresponding Secretary, MRS. ARTHUR S. DWIGHT, Acting Treasurer. Welfare Committee MRS. C. C. BURGER, Chairman, Sub-Committees Americanization Belgian Relief MRS. LEVI HOLBROOK, Chairman, MRS. HENRY H: KNOX, Chairman, Emergency MRS. HERMAN A. PROSSER, Chairman. Since the annual meeting held in February, 1917, when the Woman's Auxiliary to the A. I. M. E., was formed, the work of organization, which of necessity must be slow, has steadily gone forward. Under the Chairmanship of Mrs. C. C. Burger of the Welfare Committee, three active sub-committees have been formed: that of Americanization; under Mrs. Levi Holbrook, who is eminently fitted for such a position, by her active and valuable work in a number of the fine patriotic societies of our country; the Belgian Relief Committee, under Mrs. Henry H. Knox, which has clone phenomenal work in the three months of its existence, and whose report is later given in detail; and the Emergency Committee under Mrs. Herman A. Prosser, which has a fund already established, and is. in close touch with Major Arthur S. Dwight, ready to act when necessity arises. The officers of the Auxiliary feel more than gratified at the response so far received, and in a later issue will print extracts from letters, if permission can be gotten from the writers, showing the interest and enthusiasm that have beer aroused by the formation of a Woman's Auxiliary. Answers have even come from far Korea "the hermit nation," from Australia, from South America, showing what a bond of sympathy and, helpfulness is in process of growth. It is our sad duty to announce the death of our Treasurer, Mrs. George D. Baryon, who, from the very inception of our plan to organize, was an inspiring and valuable co-worker. Her place will be difficult to fill. Mrs. Arthur S. Dwight is Acting Treasurer at present. The Auxiliary wishes to express its heartiest thanks to Mr. Stoughton, the genial and efficient Secretary of the A. I. M. E., for his cooperation and valuable suggestions in the difficult work of organizing. He has indeed been "a guide, philosopher and friend." SUSANNE M. IHLSENG (MRS. AXEL 0.), Corresponding Secretary.

Jan 7, 1917

Time as a Factor in the Making and Treating of Steel. By John Johnston. (Howe Lecture) (T.P. 1478) Influence of Chromium and Molybdenum on Structure, Hardness and Decarburization of 0.35 Per Cent Carbon Steel. By R. F. Miller and R. F. Campbell. (T.P. 1345) Mechanical Properties of Iron-manganese Alloys. By F, M. Walters, Jr., I. R. Kramer and B. M. Loring. (T.P. 1369) The Instability of Low-expansion Iron-nickel-cobalt Alloys. By I. R. Kramer and F. M. Walters, Jr. (T.P. 1370) The S-curve of a Chromium-nickel Steel. By B. M. Loring. (T.P. 1383) A Magnetic Determination of the A3 Transformation Point in Iron. By B. A. Rogers and K. 0. Stamm. (T.P. 1388) Rapid Tension Tests Using Two-load Method. By A. V. de Forest, C. W. MacGregor and A. R. Anderson. (T.P. 1393) Effects of Scrap in the Blast-furnace Burden. By C. L. T. Edwards. (T.P. 1270) Temperature Gradients through Composite Carbon Columns and their Application to Blastfurnace Linings. By F. J. Vosburgh and M. R. HatFIeld. (T.P. 1363) Correlations of Some Coke Properties with Blast-furnace Operation. By H. W. Johnson. (T.P. 1402) The Technical Cohesive Strength and Yield Strength of Metals. By D. J. McAdam, Jr. (T.P. 1414) Effects of Eight Complex Deoxidizers on Some 0.40 Per Cent Carbon Forging Steels. By George F. Comstock. (T.P. 1417) Significance of the Bessemer End Point. By H. T. Bowman. (T.P. 1428) Structural Diagrams of Nickel Irons and Steels. By J. T. EasE and N. B. Pilling. (T.P. 1432) Carbides in Low-chromium Steel. By Walter Crafts and C. M. OFFenhauer. (T.P. 1436) Hardenability Calculated from Chemical Composition. By M. A. Grossmann. (T.P. 1437) Recrystallization of Silicon Ferrite in Terms of Rate of Nucleation and Rate of Growth. By J. K. Stanley and R. F. Mehl. (T.P. 1438) The Solubility of Carbon as Graphite in Gamma Iron. By R. W. Gurry. (T.P. 1440) An Evaluation of the Factors Affecting Iron Oxide in the Open-hearth Bath. By J. E. Gould and H. J. Hand. (T.P. 1442) Precision in Creep Testing. By J. A. Fellows, Earnshaw Cook and Howard S. Avery. (T.P. 1443) Lattice Relationships in the Decomposition of Austenite to Pearlite, Bainite and Martensite. By G. V. Smith and R. F. Mehl. (T.P. 1459) Rate of Nucleation and Rate of Growth of Pearlite. By F. C. Hull, R. A. Colton and R. F. Mehl. (T.P. 1460) Weight Change as a Criterion of Extent of Decarburization or Carburization. By R. W. Gurry. (T.P. 1470) Observations in the Making and Use of Sulphite-treated Steels. By E. L, Ramsey and L. G. Graper. (T.P. 1476) Diffusion in Metal Accompanied by Phase Change. By L. S. Darken. (T.P. 1479) Engineering Properties of Heat-resistant Alloys. By Howard S. Avery, Earnshaw Cook and J. A. Fellows. (T.P. 1480) Distribution of Manganese and of Sulphur between Slag and Metal in the Open-hearth Furnace. By L. S. Darken and B. M. Larsen. (T.P. 1481)

Jan 1, 1942

Time as a Factor in the Making and Treating of Steel. By John Johnston. (Howe Lecture) (T.P. 1478) Influence of Chromium and Molybdenum on Structure, Hardness and Decarburization of 0.35 Per Cent Carbon Steel. By R. F. Miller and R. F. Campbell. (T.P. 1345) Mechanical Properties of Iron-manganese Alloys. By F, M. Walters, Jr., I. R. Kramer and B. M. Loring. (T.P. 1369) The Instability of Low-expansion Iron-nickel-cobalt Alloys. By I. R. Kramer and F. M. Walters, Jr. (T.P. 1370) The S-curve of a Chromium-nickel Steel. By B. M. Loring. (T.P. 1383) A Magnetic Determination of the A3 Transformation Point in Iron. By B. A. Rogers and K. 0. Stamm. (T.P. 1388) Rapid Tension Tests Using Two-load Method. By A. V. de Forest, C. W. MacGregor and A. R. Anderson. (T.P. 1393) Effects of Scrap in the Blast-furnace Burden. By C. L. T. Edwards. (T.P. 1270) Temperature Gradients through Composite Carbon Columns and their Application to Blastfurnace Linings. By F. J. Vosburgh and M. R. HatFIeld. (T.P. 1363) Correlations of Some Coke Properties with Blast-furnace Operation. By H. W. Johnson. (T.P. 1402) The Technical Cohesive Strength and Yield Strength of Metals. By D. J. McAdam, Jr. (T.P. 1414) Effects of Eight Complex Deoxidizers on Some 0.40 Per Cent Carbon Forging Steels. By George F. Comstock. (T.P. 1417) Significance of the Bessemer End Point. By H. T. Bowman. (T.P. 1428) Structural Diagrams of Nickel Irons and Steels. By J. T. EasE and N. B. Pilling. (T.P. 1432) Carbides in Low-chromium Steel. By Walter Crafts and C. M. OFFenhauer. (T.P. 1436) Hardenability Calculated from Chemical Composition. By M. A. Grossmann. (T.P. 1437) Recrystallization of Silicon Ferrite in Terms of Rate of Nucleation and Rate of Growth. By J. K. Stanley and R. F. Mehl. (T.P. 1438) The Solubility of Carbon as Graphite in Gamma Iron. By R. W. Gurry. (T.P. 1440) An Evaluation of the Factors Affecting Iron Oxide in the Open-hearth Bath. By J. E. Gould and H. J. Hand. (T.P. 1442) Precision in Creep Testing. By J. A. Fellows, Earnshaw Cook and Howard S. Avery. (T.P. 1443) Lattice Relationships in the Decomposition of Austenite to Pearlite, Bainite and Martensite. By G. V. Smith and R. F. Mehl. (T.P. 1459) Rate of Nucleation and Rate of Growth of Pearlite. By F. C. Hull, R. A. Colton and R. F. Mehl. (T.P. 1460) Weight Change as a Criterion of Extent of Decarburization or Carburization. By R. W. Gurry. (T.P. 1470) Observations in the Making and Use of Sulphite-treated Steels. By E. L, Ramsey and L. G. Graper. (T.P. 1476) Diffusion in Metal Accompanied by Phase Change. By L. S. Darken. (T.P. 1479) Engineering Properties of Heat-resistant Alloys. By Howard S. Avery, Earnshaw Cook and J. A. Fellows. (T.P. 1480) Distribution of Manganese and of Sulphur between Slag and Metal in the Open-hearth Furnace. By L. S. Darken and B. M. Larsen. (T.P. 1481)

Jan 1, 1942

By A. F. Taggart

THE following notes represent significant excerpts from a mass of records of experimental work done in the ore-dressing laboratory at the Columbia School of Mines during the years 1926 to 1928-inclusive. CLASSIFICATION OF EXPERIMENTAL WORK The experiments performed may be grouped for purposes of description under the following general -headings: I. Collecting agents. a. A method for quantifying collecting effect. b. Coating with undissolved collecting agents (oils) c. Action of dissolved collecting agents. II. Frothing agents. a. A method for quantifying frothing effect. b. Relation between frothing effect and chemical composition. III. Inorganic reagents. a. Methods of studying the effects of these reagents. b. Effect on slime dispersion. c. Effect on sulfides. SUMMARY OF THE ORIGINS OF PRESENT-DAY FLOTATION PRACTICE The first practicable, foolproof method of froth flotation was described in U. S. patent 835120, issued in 1906 to Sulman, Picard and Ballot, and in the equivalent patents in other countries. A number of less simple methods of producing the same result had been described previously in patent publications and otherwise.1 The reagents specified in all of these early patents were "oils" and, in addition, some inorganic substance, usually an acid. The quantities of reagents recommended and added were enormous when' compared with those used today.

Jan 1, 1929

By CHARLES DORRANGE

INTRODUCTION. CULM is a general term used in the anthracite regions for many years to denote a mixture of coal, bony coal and impurities which is sent to the refuse-banks. Thus, 35 years ago culm contained the pea and buckwheat sizes of anthracite; but to-day, and as mentioned in this paper, culm is used specifically to denote the material which passes through the smallest screen in the anthracite-breaker. The smallest size of commercial anthracite is known as No. 3 buckwheat, barley, or bird's-eye coal, and is ordinarily made through a round-punched plate having openings 3/16 in. in diameter, and over a round-punched plate with opening 3/32 in. or 1/16 in. in diameter. Thus culm will consist of coal, bony coal, slate, gravel, iron pyrite, etc., ranging in size from ? 3/32 in. down to dust. Other local terms for culm are " slush," " silt," and " dirt." The first experiments towards the utilization of anthracite culm by briquetting, and the first briquetting-work done in this country, were in 1872 at Port Richmond Piers, Philadelphia, Pa., by E. F., Loiseau.1 Clay was used as a binder and the finished briquette was water-proofed with shellac, etc. Excessive cost was given as the reason for discontinuing work at this plant. The Delaware k Hudson Co., in 1876, built a plant at Rondout, N. Y., which operated until 1880. Gas-tar was used as a binder, and anthracite screenings were briquetted for engine fuel. Excessive cost, poor results in firing, and the tendency of the fuel to cut the boiler-flues were given as the reasons for discontinuing the manufacture. The next plant was built by E. F. Loiseau about 1878, at Nesquehoning, Pa., near the No. 1 or Nesquehoning colliery

Sep 1, 1911

By James E. York

THE honor so fairly earned and so incompletely and tardily paid to Henry Cort, the inventor of the puddling-furnace and the, rolling-mill, has been fully set forth by Mr. Charles H. Morgan,1 and needs no further emphasis here. In view of the importance of the rolling-mill in the treatment of iron and steel, the paucity of information concerning it is surprising. With the exception of a hook, written about 35 years ago, by Peter Bitter von Tunner, an Honorary Member of this Institute, and of desultory articles on simple sections, which have appeared in technical journals, I know of no pub¬lication attempting to treat this subject, although volumes have been written on the scientific theory and technical manipulations involved in other branches of the iron- and steel-industry. This strange anomaly may be due to the fact that roll-turning cannot be called a scientific business. It does not ordinarily come within the range of an educated engineer; yet it cannot be performed by an ordinary mechanic. It demands some of the qualifications of an engineer, in designing, and those of a mechanic, in execution. The men who have followed this trade have controlled the training of their successors. In many cases the technical knowledge required bas been handed down from father to son, and there has been a motive of private interest to prevent its public dissemination. Moreover, the statement of the various principles involved in the process would require, besides manual experience, a degree of scientific knowledge which roll-turners do not usually possess; and, finally, any book on the subject, in order to possess real, practical value, would have to be so fully illustrated as to make it very costly to publish. Regarding my own experience, I may say that I served a six-

May 1, 1906

J. L. CHRISTIE, Chairman T. S. FULLER, Past-chairman W. M. PEIRCE, Vice-chairman W. A. SCHEUCH, Vice-chairman E. M. WISE, Secretary International Nickel Co., Bayonne, N. J. W. M. CORSE, Treasurer Executive Committee H. A. BEDWORTH G. O. HIERS D. K. CRAMPTON R. H. LEACH E. H. DIX, JR. R. F. MEHL J. A. GANN J. WALTER SCOTT' JEROME STRAUSS Finance Committee T. S. FULLER, Chairman W. M. CORSE H. S. RAWDON C. H. MATHEWSON SAM TOUR

Jan 1, 1934

By R. Lee-Aston

HALLOWAY mine of Tennessee Copper Co. at Copperhill, Tenn., has been under development for several years. It has two shafts, the A shaft, 1336 ft deep from the surface to the 16 level, and the B shaft, lying 500 ft to the southeast and extending 1385 ft deep from the 10 level down to the 24 level. A section through the two shafts, Fig. 1, shows the development work entailed by the proposal and the area involved. The Problem: For operational reasons it was necessary to extend the B shaft from the 10 level to surface, and the pilot hole and raising method was chosen. This method had been used to extend the Company's Boyd manshaft from the 10 to the 14 level in 1954, but no satisfactory hole surveying method had been employed. In that instance, when the hole was located it was found to be about 8 ft from its calculated position. The success of this shaft extension method lies in the ability to keep the pilot hole within the proposed shaft diameter for nearly the entire length. The approximate 670 ft of extension distance in one hole was thought to be excessive because of deflection encountered locally in other core drilling. Since a connection between the two shafts, intermediate between the surface and the 10 level, would be required at some future date, the pilot hole drilling was done in two sections. This intermediate level was fixed at the 6 level and distances became 470 ft from surface to the 6 level and 230 ft from the 6 to the 10 level. A rock pentice of 25 ft was left temporarily in place just above the 10 level.

Jan 3, 1958

By E. W. Murbach

The oxidation of uranium carbide by oxygen at various pressures, and by air, has been investigated at temperatures up to 600°C. Arc-melted and cast uranium carbide displays oxidation behavior that appears to be dependent on its treatment after melting. ccReactive" uranium carbide, which results from exposure of freshly melted material to laboratory air, ignites in oxygen at about 275° to 350°C depending on pressure, and in air at about 350°C. The product of the initial oxidation appears to be UO2+.. Continued heating produces U30,. The initial oxidation rate is poportional, roughly, to the square root of the oxygen pressure. The activation energy determined for the initial oxidation reaction is 7.1 kcal, from 400° to 600°C in 10 mm of oxygen. AN investigation of low-decontamination methods for reprocessing uranium carbide reactor fuels is being carried out at Atomics International. One of the reprocessing cycles includes oxidation of the fuel at relatively low temperature (300° to 500°C) and reaction of the product oxide with carbon at elevated temperatures (above 1500°C) to produce uranium carbide. A number of small-scale experiments have been carried out in which uranium carbide was oxidized in air and oxygen at various pressures to measure reaction rates and to obtain other information concerning the oxidation process. In initial experiments with arc-melted UC, ignition was observed at about 275°C in oxygen or 350°C in air. However, similar experiments by Neymark' at 426°C in air showed no ignition. It was soon determined that the difference in oxidation behavior was due to the treatment of the UC following arc-melting. Neymark's experiments were carried out with freshly melted UC while those reported in the

Jan 1, 1963

CONTENTS PAGE SOUTHWARD, GLENN B.-Coal Mining by the V System. Discussed by Glenn B. Southward, Howard N. Eavenson, Edward B. Raiguel, Thomas de Venny, J.. J. Rutledge, Graham Bright 1 ARMS, RAY W.-Dry Cleaning of Coal. Discussed by Ray W. Arms, S. A. Taylor, Howard N. Eavenson, W. R. Crane, F. F. Jorgenson, G. R. Delamater. 6 EAVENSON, HOWARD N.-Data About Labor Employed in Various Bituminous Coal Mines. Discussed by Howard N. Eavenson, George H. Ashley, E. A. Holbrook, S. A. Taylor, R. V. Norris 14 Coal Mining by the V System Discussion of the paper of GLENN B. SOUTHWARD presented at the New York Meeting, February, 1924, and issued as Paper No. 1300-C, with MINING AND METALLURGY, February, 1924. MEMBER.-How do you pay your men for loading? GLENN B. SOUTHWARD.-Everything is on time basis. MEMBER.-How many men do you have loading across one of the diagonal faces? GLENN B. SOUTHWARD.-From four to five, depending on the length of the face. Our loaders are so arranged that each will give about twenty-five tons per loader a day. MEMBER.-How much timber do you use? GLENN B. SOUTHWARD.-A little more than will be used in room-and-pillar work, but not a great deal more. We have not attempted to recover much of our timber. MEMBER.-IS the mine union or non-union? GLENN B. SOUTHWARD.-Non-union. HOWARD N. EAVENSON, Pittsburgh, Pa.-I went .through that mine some weeks ago, and think that the author has been very conservative in his statements about the amount of loadings, etc. EDWARD B. RAIGUEL, Huntington, W. Va. (written discussion).¬Page 7 shows 60 men employed in day and night shifts, inside the mine, producing 750 tons per day. Let us reduce these figures to a man-hour basis, for comparison with Mr. Eavenson's figures on West Virginia mines, as follows:

Jan 6, 1924

By Robert T. Ault

The nature of fracture in unnotched tensile and notched tensile sheet and round specimens and V -notched and precracked Charpy-type sheet specimens of both wrought stress -relieved and re-crystallized molybdenum was investigated over the temperature range of -78° to 300°C. The sharp rise in fracture stress, for unnotched tensile samples, as the temperature is increased above the brittleness transition temperature (Tb), is found to be a result of an increase in flow stress due to plastic constraint and an increased strain rate which results from the onset of necking at Tb . Quasi-brittle fracture in notched tensile samples is found to occur when the tensile stress at the elastic-plastic interface, beneath the root of the notch, reaches a maximum critical value, which is independent of test temperature over the range from —78° to 25°C, but dependent on microstructure. In the temperature range between 150° and 300°C, unnotched tensile and notched tensile samples alike are found to fracture by a ductile fibrous tearing process which is discontinuous in nature, as a result of the competition between the processes of tearing, through continued plastic flow, and local work hardening. Results from the V-notched and fatigue-cracked Charpy-type impact tests demonstrate that crack initiation is the governing factor in the low-temperature (-78° to 25°C) fracture process for molybdenum. In recent years, there has been considerable interest, and a commensurate number of investigations, concerning the duc tile-to-brittle transition in refractory metals. There has not developed, however, a satisfactory explanation for the uniaxial tensile fracture-stress transition which accompanies the well-known ductility transition. This matter therefore warranted investigation. In a similar manner, the increased importance of notched tensile strength values in evaluating materials and in design criteria requires a better understanding of the factors which control the fracture behavior of notched tensile samples. In a previous investigation1 of the nature of initial yielding and fracture in notched sheet molybdenum at room temperature, it was suggested that plastic constraint was the controlling factor in governing the fracture behavior of notched samples. The final portion of this investigation was concerned with the fracture toughness of molybdenum. Of particular interest was the comparison of effective surface energies for fracture in V-notched samples with fatigue-cracked, Charpy-type samples in order to ascertain the relative importance of the initiation and propagation phases of the fracture process. MATERIALS AND TEST PROCEDURE Sheet tensile, notched tensile, and V-notched Charpy specimens were prepared from 50-mil, stress-relieved molybdenum sheet.* Half of these specimens were vacuum-annealed for 1 hr at 1200°C and 7.5 x l0-5 Torr and furnace-cooled to produce a relatively uniform grain size of 0.30 mm diameter. Round notched and unnotched tensile specimens were prepared from warm-rolled and swaged 5/8-in.-diam bar.* These specimens were vacuum-annealed for 1 hr at 1350°C and 5 x lom5 Torr and furnace-cooled to produce a grain diameter of 0.11 mm. Material analyses in ppm were: C N O H Sheet 290 10 4 1 Bar 50 30 30 2 The unnotched tensile sheet specimens had a 1/4-in. gage width and a 1-in. gage length. The unnotched tensile round specimens had a 9/32-in. gage diameter and a 1-1/4-in. gage length. The sheet and round notch tensile specimens are shown in Fig. 1. All of the notched tensile specimens tested were tandem-notched in order to study the location and mode of fracture initiation. The tandem-notched specimens were carefully machined so that the largest variation in notch depth on a single specimen was 0.001 in. Thus, when fracture occurs, the extent of plastic deformation that exists in the un-fractured notch section is that which exists just prior to fracture. All of the tandem-notched sheet specimens were electrolytic ally polished and chemically etched prior to testing. The V-notched Charpy-type specimens machined from the 50-mil sheet material had the standard dimensions of 2.125 in. long, 0.394 in. deep, and a 0.010-in. root radius. The unnotched tensile and notched tensile tests were conducted over the temperature range of -78° to 300°C, in a 10,000-lb Instron Universal Testing Machine, at a constant crosshead speed of 0.020 in. per min. The V-notched Charpy-type

Jan 1, 1964

Jan 1, 1923

Jan 1, 1923

By H. E. Brauer

PART I INTRODUCTION Among the zinc base alloys used for casting in metal moulds, particularly die casting, those alloys containing aluminum usually together with copper, are probably the most widely used. The reason lies in their desirable mechanical properties and the fluidity and absence of hot shortness which facilitate casting. Objection to the use of these alloys may bee raised on account of the rather frequent instances of failure of a type variously described as disintegration, exfoliation and intercrystalline corrosion. In all cases which have come to our knowledge where the conditions of service were known, failure has occurred upon exposure to moisture and heat varying from a hot moist atmosphere to high pressure steam. Moreover, the alloys described in all such cases contain impurities or alloying metals which the present authors have found to have enormous accelerating effects on intercrystalline oxidation in zinc-aluminum alloys. Thus Williams1 experimented with an alloy containing a large percentage of tin exposed in Cuba. Bauer2 reports failure of a boiler plug containing over 1 per cent. of impurities, doubtless lead for the most part, and Rawdon's3 examinations were made on an alloy containing 0.4 per cent. lead also exposed to the Tropics. No thorough investigation of the nature and cause of this type of failure has been made heretofore, so far as the authors are aware, although Rawdon correctly classified it as internal oxidation. We have, therefore, carried out this investigation in order to determine the exact nature of this phenomenon and the effect of other metals present as impurities or intentional additions in accelerating or-retarding it. In the appendix we include a considerable amount of data which may be valuable in selecting an alloy combining good physical properties with high resistance to oxidation.

Jan 8, 1922

By John Hays Hammond

Discussion of the paper of John Hays Hammond, presented at the Chattanooga meeting, October, 1908, and published in Bi.-Monthly Bulletin., No. 24, November, 1908, pp. 1171 to 117S. PROF. HENRY Louis, Newcastle-upon-Tyne, En j. (communication to the Secretary'`) :-I welcome Mr. Hammond's paper as an. attempt to give definiteness to the best modern professional practice. Such a codification of our professional ethics is urgently needed, seeing how widely the views of mining engineers differ on some of the point-,. raised, for example, I have no hesitation it) performing a class of work, as to which Mr. Hammond seems to entertain some doubts, and, on the other hand, I strongly condemn a practice which he appears to recommend. I have not the least hesitation in making reports for vendors of mining properties, and am constantly doing so; . the best justification for this practice may be found in the fact that such reports have been repeatedly accepted by buyers as giving a correct representation of the facts of the case, which is all that should be demanded from any report. On the other hand, Mr. Hammond advocates that mitring engineers should take payment for their reports tin shares of a company to be floated upon the basis of such reports. I hold that this is ethically wrong, as even the most honest of men is liable to be unconsciously biased under these conditions. Indeed, I go much further, and maintain that a mining engineer who re¬ports or advises upon mining properties should never hold any-mining shares at all, or be himself interested in any mine,' and this has been my consistent practice for many years. A man who holds shares in a mine, and is called upon to report upon a neighboring property or a similar mine, can never be wholly unbiased, and even if lie could be, he would always lay himself open to the suspicion that he was giving a favorable report so as to-enhance the value of the property in which he himself is interested, or an unfavorable report so as to stifle competi-

Jun 1, 1909