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By Claude H. P. Lupis, John F. Elliott

IN the recent past, extensive use has been made of the interaction coefficient in treating the thermody-namic behavior of components in solutions at dilute concentrations. The development of this concept by wagner1 and chipman2,3 is sufficiently well-known so that its elucidation here is not necessary. The present discussion is focused on the relationship between E and e. The usual forms of the coefficients are:

Jan 1, 1965

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.' Steamboat Springs is situated near the eastern base of the escarpment of the Sierra Nevada, six miles distant from the Comstock lode.

Jan 1, 1906

STANDING COMMITTEES Executive CHARLES F. RAND, Chairman. JAMES F. KEMP, JOSEPH W. RICHARDS, ALBERT R. LEDOUX, BENJAMIN B. THAYER. Membership BENJAMIN B. THAYER, Chairman. KARL EILERS, JOHN H. JANEWAY, Jr., JOHN D. IRVING, HERMAN A. PROSSER. Finance EDWARD L. YOUNG, Chairman. KARL EILERS, JAMES GAYLEY. Library JAMES F. KEMP, Chairman.1 JOHN HAYS HAMMOND,3 E. GYBBON SPILSBURY,2 ALEX. C. HUMPHREYS,4 BRADLEY STOUGHTON.

Jan 1, 1914

YEAR OF ELECTION 1913. FRANK DAWSON ADAMS Montreal, Canada. 1921. WILLIAM CUTHBERT BLACKETT Sacriston, Durham, England. 1923.. GELASIO CAETANI Rome, Italy. 1920. HENRY STURGIS DRINKER Merion Station, Pa. 1921. FERDINAND FocH Paris, France. 1922. FEDERICO GIOLITTI Torino, Italy. 1906. SIR ROBERT A. HADFIELD London, England. 1921. FRANK WILLIAM HARBORD London, England. 1917. HERBERT HoovER Washington, D. C. 1905. HENRI LECHATELIER Paris, France. 1921. C. McDERMID London, England. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1909. ALEXANDRE POURCEL Paris, France. 1911. ROBERT H. RICHARDS Cambridge, Mass. 1891. DR. ING. H. C. EMIL SCHROEDTER Mehlem a Rhein, Germany. HONORARY MEMBERS (Deceased)

Jan 1, 1928

By A. D. Rovig, T. J. Fisher

By converting its autogenous mills to steel ball mills at the C. E. Weed concentrator in Butte, Mont., The Anaconda Co. has achieved substantial increases in through- put tonnage, plus better recoveries as a result of the finer feed size to subsequent flotation operations. If steel grinding is so superior to autogenous grinding, why wasn't it chosen in the first place? Briefly, here's why:

Jan 10, 1975

By Secretary

The two papers by Mr. C. M. Rolker, " Notes on Certain IronOre Deposits in Colorado," and "Notes on the Leadville OreDeposits," printed at pages 266 and 273 of this volume, were put to press (owing to the author's absence from the country) without final revision by him. The following corrections are thus made necessary: On page 272, line 13 should read, "respectively 12 and 4 feet" (instead of 12 and 14). On the same page, line 6 from the bottom should read, " the remaining 360 feet" (instead of 320). On page 284, lines 23 and 21 should read, " 111 some places, the dolomite sand roof has remained thicker; and in isolated parts of the bed no replacement has occurred."

Jan 1, 1886

Jan 1, 1948

At a meeting of the Board of Directors, held Jan. 21, 1916, the following resolution was adopted: Resolved, that this Board has learned with indignation and sorrow of the unprovoked and brutal murder of 18 American citizens on January 10, in the State of Chihuahua, Mexico, and laments especially the death of Messrs. C. R. Watson, C. A. Pringle, H. C. Hase, and W. J. Wallace, who were members of the American Institute of Mining Engineers. As these men and their companies were engaged, in the lawful prosecution of their work, we trust that nothing will be allowed to prevent or delay appropriate action by our Government concerning the outrage by which they lost their lives;

Jan 3, 1916

Geological Survey topographic mapping parties started initial operations in the 1953 Alaskan mapping program. One area to be covered is 17,000 sq miles in the Kantishna River, Melozitna, Tanana Fairbanks, Healy and Mt. McKinley section. The other area to be covered is the Kenai, Tyonek, Blying Sound and Seldovia areas. Average starting salary earned in 1952 by Columbia University School of Engineering graduates was $4000 yearly. This year's graduates can expect to start at about $4300, according to a survey taken by Columbia. Figures cover only those with Bachelor degrees. Graduates with a Master's started at an average of $500 per year more.

Jan 7, 1953

By Richard A. Boulay

The effects of capital, operating and debt cost variations on project performance criteria are examined using a theoretical model and an actual case history. On an after-tax basis, financial measurements are found to be most sensitive to operating cost changes, somewhat sensitive to reasonable changes in capital costs and relatively insensitive to interest rate fluctuations.

Jan 1, 1985

By Lawrence Adler

Any design of a mine roof in bedded deposits which ignores differential deflections at the supports can quickly lead to dangerous overstressing. As illustrated by the typical case presented on page 1029, if one support deflects only 0.1 in. more than its neighbor, stresses 50 pct higher than anticipated will result. Previous studies1-3 have assumed that the mine roof acts like a beam clamped at both ends, with no deflection or slope4 at the supports (Fig. 1). Essentially this assumes:5,6 [BA = OD = 0 and dA = dB = 0.]

Jan 10, 1959

By John W. Stevenson

In gassy coal mines, abandoned worked-out areas are natural reservoirs that may contain air- methane mixtures. The quantity of such mixtures is continuously increasing or decreasing as atmospheric pressure falls or rises. This is in accordance with Boyle's Gas Law, which states that the volume of a perfect gas varies inversely with the absolute pressure. In large, open gob areas without a bleeder ventilation system, atmospheric pressure is a static force acting in all directions. Changes in atmospheric pressure may occur rapidly or slowly, but any change will result in a change in the quantity of gob air-methane mixtures.

Jan 6, 1968

COMMITTEES. Precious and Base Metals. Charles W. Goodale, Chairman.. L. D. Ricketts, Vice-Chairman Darsie C. Bard, Secretary, Montana State School of Mines, Butte, Mont. Leonard S. Austin, Thomas J. Grier, Willet G. Miller, David W. Brunton, Hennen Jennings, Albert F. Schneider, Theodore B. Comstock, Edmund B. Kirby, George C. Stone, Stanley A. Easton, Charles W. Merrill, Benjamin B. Thayer. Samuel S. Fowler,

Jan 11, 1913

By L. S. Panyity

The Cleveland (0.) gas pool described by Frank R. Van Horn,' is the northern extremity of the great "Clinton" sand gas development in Ohio. Numerous gas pools have been developed in this formation, which are now more or less connected, link by link, forming an almost continuous gas pool, starting at Cleveland, and running thence southward through Cuyahoga, Medina, Wayne, Ashland, Richland, Knox, Licking,

Jan 1, 1918

Jan 1, 1951

By James Douglas

As the operation of light railroads is important to the mining industry, the following statistics of the Arizona Southeastern Railroad may be of interest. When the traffic of the Bisbee copper-mines reached 20,000 tons per year the necessity of better transportation than that afforded by eighteen- and twenty-horse and mule teams became imperative on the score of both cheapness and convenience. Before deciding on the construction of a railroad, the Copper Queen Company made a thorough experiment in transportation

Jan 1, 1899

DAVID THOMAS 1871 R. W. RAYMOND 1872-1874 A. L. HOLLEY 1875 ABRAM S. HEWITT 1876 T. STERRY HUNT 1877 ECKLEY B. COXE 1878-1879 WILLIAM P. SHINN 1880 WILLIAM METCALF 1881 RICHARD P. ROTHWELL 1852 ROBERT W. HUNT 1883 JAMES C. BAYLES 1884-1855 ROBERT H. RICHARDS 1886 THOMAS EGLESTON 1887 WILLIAM B. POTTER 1888 RICHARD PEARCE 1889 ABRAM S. HEWITT 1890 JOHN BIRKINBINE 1891-1892 H. D4. HOWE 1893 JOHN FRITZ 1894 J. D. WEEKS 1895 E. O. SPILSBURY 1896 THOMAS M. DROWN 1897 CHARLES KIRCHHOFF 1898

Jan 1, 1942

By Calvin Pierson, R. S. Dean, E. P. Barrett

Wrought iron and steel have been prepared from limonite, hematite, and magnetite ores by gaseous reduction, compacting and squeezing the resulting product at high temperature and finally melting the wrought iron so formed. The structure, analyses, mechanical and magnetic properties of the products are given. It is found that the structure of iron ores is best studied by subjecting them to gaseous reduction and using metallographic technique on the resulting sponge iron. In this way the cell structure of iron ore is clearly shown. The wrought iron made by heating compacted sponge iron to 1450" C., and forging, shows a cell structure inherited from the ore. This cell structure is further preserved in melting and casting the wrought iron. The probable relation of the properties of the materials to this inherited cell structure is discussed.

Jan 1, 1935

The Board of Directors has authorized the following offers of sets of back volumes of the Transactions, at considerably reduced prices, to Members, Libraries, and Scientific Societies Per Set. I. Five volumes, bound in half-morocco, from No. 36 (1906) to No. 40 (1910), . $20 II. Ten volumes, bound in half-morocco, from No. 31 (1902) to No. 40 (1910), including Mexican Volume, 35 III. Twenty volumes, bound in half-morocco, from No. 21 (1893) to No. 40 (1910), 50

Jan 4, 1913

By P. H. Dudley

IN giving a brief account of the experiments in progress to inquire into some of the facts in regard to "railway resistances," recently commenced upon the Lake Shore and Michigan Southern Railway, with the dynagraph (which is essentially an instrument recording upon paper the force required to draw a train, at all speeds, marking the time in short intervals, so that the force absorbed due to any

Jan 1, 1876