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By J. A. Scott, F. R. Hensel

The paper deals with the investigation of two types of coreless induction furnaces, one of 60 cycles, the other of 5000 cycles. Nickel was used as test material and the absorption of oxygen by molten nickel was chosen for determining the influence of the frequency on the metallurgical characteristics of the furnaces. Dr. Herty's aluminum method, slightly modified, was found suitable for determining the nickel oxide content in nickel. Also an electrolytic method for determining alumina in nickel was worked out. The solubility-temperature relations for nickel oxide in molten nickel were determined approximately. It was found that the solubility of nickel oxide increases with the temperature. Comparative tests on the rate of oxygen absorption made in a 60 and a 5000-cycle furnace showed that the absorption of nickel oxide in nickel is an increasing function of turbulence, time and temperature. The rate of oxygen pickup in the 60-cycle furnace is about three times as great as in the 5000-cycle furnace. In the 60-cycle furnace the maximum oxygen content of the melt comes close to the saturation limit. Melting under an oxygen-free atmosphere prevents oxidation in both types of furnaces. DISCUSSION (Iloward Scott presiding) H. Scott, East Pittsburgh, Pa.—When Professor Desch was in Pittsburgh recently he mentioned that the induction furnace has practically replaced the crucible furnace in Sheffield except for the carbon tool steels. Dr. Hensel is to be congratulated on the development of analytical methods for determining inclusions and for getting two different methods to agree. F. R. Hesnsel—Recently the purification of molten metals with hydrogen or other suitable gases has become an important issue and a number of patents have been taken out covering gaseous treatments of molten metals. In this connection I wish to call

Jan 1, 1933

By E. I. Larsen, F. R. Hensel

According to statements by Guertler1 Smith and Hamilton were the first to study the copper-titanium alloys, but owing to the presence of large amounts of impurities their data are inconclusive. M. A. Hunter and I. W. Bacon later investigated the electrical conductivity and the temperature coefficients at room temperature. The present writers reported their results2 in November, 1930. Recently Kroll published data on copper-titanium alloys3 which agree closely with those obtained by the authors. Material Tested The titanium used was in the form of square sintered rods, the analysis of which runs as follows: titanium, 95.4 per cent; silicon, 0.7; iron,l.8; aluminum, 1.4; copper, 0.1; manganese, 0.05. The ingots were prepared in a high-frequency induction furnace in air atmosphere. Their analyses are given in Table 1. Up to 5 per cent titanium the alloys could be forged. Above that amount they were red short and broke up easily. Owing to their rapid absorption of nitrogen and oxygen from the air, the alloys with the higher amounts of titanium tend to form surface films which greatly increase the casting difficulties, especially when small masses of metal are handled. It was, however, possible to prepare sound ingots up to 25 per cent titanium. Thermal and X-ray Investigation The cooling curves of some of the alloys are plotted in Fig. 1, and R tentative diagram constructed from these data is given in Fig. 2. From this it is evident that the solid solubility of copper for titanium is approxi-mately 4 to 5 weight per cent titanium at 878" C., which is the eutectic temperature. The melting point of copper is lowered gradually by adding

Jan 1, 1932

By Charles R. Keyes, D. F. Riddell

For a period of several years, and in a large number of oases, the Metallurgical Laboratories of the New Mexico School of Mines were employed in umpire work. During this time many important local problems mere solved. Against the results of careful chemical analyses of ores, assay-returns mere often checked. In many cases the assay-methods of mine and custom-smelter were compared, and both often found faulty for the ore concerned. A wide range of ores was covered. Many of the chemical analyses and assays were made by Dr. F. C. Lincoln, Professor of Metallurgy, now of the Montana State School of Mines. A varied series of instructive assays was prepared by Prof. R. B. Brinsmade, now of the West Virginia State University. Single assays and given series of tests were undertaken by H. T. Goodjohn, now chief chemist to the Cia. Metalurgica de Torreon, Coahuila, Mexico; by H. J. Hub-bard, now superintendent of the Butters Divisadero Mines, Jocoro, San Salvador, C. A.; by E. D. Morton, now superintendent of the Arizona & Nevada Copper Mining Co., at Lunning, Nev.; and by A. W. Edelen, now superintendent of the Angangueo Unit of the American Smelting & Refining Co., in Michoacan, Mexico. A critical comparison of assay-methods that were found to be followed in the case of certain gouge-ores mined in the Mimbres range in New Mexico, and about which there had been much controversy, was made by D. F. Riddell, then Acting Professor of Assaying, and now superintendent of the Providentia Mines Co. of Parral, in Chihuahua, Mexico. To him is due the credit of much that is contained in the following notes, which he has generously permitted to be used in advance of the publication of the complete results.

Jan 1, 1912

By Richard W. Lodge

Several methods, both wet and dry, for the assay of zinc-box residues from the cyanide process, have been described in recent years, and each of them has been claimed to be superior to all others. In the year 1901, a paper, entitled "Assay of Zincy Precipitates," was published ill the School of Mines Quarterly to the purport that the scorification method for the assay of zinc-box residues was absolutely unreliable. In order to shed light on this matter, the following experiments were undertaken by Messrs. C.B. Hollis and F. D. Kehew, undergraduate students at the Massachusetts Institute of Technology. The zine-box residues used were obtained through the courtesy of Mr. H. R. Batcheller. The samples were very rich and varied greatly in the fineness of their condition. SCORIFICATION-ASSAYS. In the preliminary tests, the charge, which was weighed on a chemical balance, consisted of 0.1 Assay Ton of residues mixed with from 30 to 35 grammes of test-lead and placed in a 3-in. scorifier, over this an additional quantity of test-lead (from 30 to. 35 grammes) was placed for a cover, and borax-glass, varying in quantity from 3 to 15 grammes, was sprinkled over the top of each charge of the various assays for a cover. The charges were scarified in a muffle-furnace heated to the ordinary temperature which is used in scorification; in some cases the door of the muffle was left open, while in others it remained closed. Generally, the charges spit badly, especially in the assays that were made with door of the muffle left open, or in those in which the door was opened too quickly. The results of the preliminary assays showed: 1. That in order to obtain approxi-

Jan 1, 1904

By G. W. Bain

The Canadian magnesite deposits are situated in Grenville township, about 8 miles from Calumet station, on the Canadian Pacific Railway, but the poor transportation facilities have hindered their development. Magnesite was discovered in the boulders near White Rock Lake by Rev. W. P. Boshart in 1900. Observing that the material of these boulders was more glistening and whiter in color than Grenville limestone, he sent a specimen to the Department of Mines, Ottawa. An analysis showed this to be almost pure carbonate of magnesia and of commercial value if present in sufficient quantities. That summer, Boshart and McAllister found numerous outcrops, both of boulders and of bed rock, that gave promise of being magnesite of a commercial grade, and decided that this mineral deposit, if developed, would rival that at Veitsch, Austria. So they procured options on most of the land on which they knew the magnesite occurred. But the transportation difficulties were too great for the deposits to be mined at the prices offered for the product. In 1907, T. J. Waters organized the Canadian Magnesite Co. and opened a quarry on the north half of lot 18, range IX, and later on lot 15, range IX, of the same township. A lirnestone kiln was erected and the calcined rock was hauled to Calumet. In 1914, the North American Magensite Co, took over the quarries and shipped both crude and calcined magnesite until January, 1923. During 1915, S. Melkman organized the Scottish Canadian Magnesite Co. and opened a quarry on lot 15, ranges X and XI, Grenville township. A light, narrow-gage railway connects this quarry with the C. P. R. at Magnesite station. but shipments are made only during the summer months. Numerous other quarries have contributed to the output of the district but the greater part has come from the open pits of the

Jan 1, 1923

By G. W. Bain

The Canadian magnesite deposits are situated in Grenville township, about 8 miles from Calumet station, on the Canadian Pacific Railway, but the poor transportation facilities have hindered their development. Magnesite was discovered in the boulders near White Rock Lake by Rev. W. P. Boshart in 1900. Observing that the material of these boulders was more glistening and whiter in color than Grenville limestone, he sent a specimen to the Department of Mines, Ottawa. An analysis showed this to be almost pure carbonate of magnesia and of commercial value if present in sufficient quantities. That summer, Boshart and McAllister found numerous outcrops, both of boulders and of bed rock, that gave promise of being magnesite of a commercial grade, and decided that this mineral deposit, if developed, would rival that at Veitsch, Austria. So they procured options on most of the land on which they knew the magnesite occurred. But the transportation difficulties were too great for the deposits to be mined at the prices offered for the product. In 1907, T. J. Waters organized the Canadian Magnesite Co. and opened a quarry on the north half of lot 18, range IX, and later on lot 15, range IX, of the same township. A lirnestone kiln was erected and the calcined rock was hauled to Calumet. In 1914, the North American Magensite Co, took over the quarries and shipped both crude and calcined magnesite until January, 1923. During 1915, S. Melkman organized the Scottish Canadian Magnesite Co. and opened a quarry on lot 15, ranges X and XI, Grenville township. A light, narrow-gage railway connects this quarry with the C. P. R. at Magnesite station. but shipments are made only during the summer months. Numerous other quarries have contributed to the output of the district but the greater part has come from the open pits of the

Jan 1, 1923

By M. L. Requa

This paper is abstracted from the report of the Appraisement Committee of the Independent Oil Producers' Agency, of which the writer was Chairman. The other members of the committee were M. V. McQuigg and R. S. Haseltine. To Thomas Cox, engineer in charge of the investigation, and to his efficient staff of assistants, is due the credit for the detail work necessary in carrying out the plan of the Committee. It treats only of the valuation of the lands, wells, and piping, without going into details of equipment and other features. It was recognized, early in the operation, that the value of oil lands was the value of oil to be extracted, and marketed, less the costs attendant thereon. Referring this back to the costs in cents per barrel, it became obvious that surface improvements, absolutely necessary in the production of oil, from wells then drilled; had no separate and independent value aside from the value of the land, but that any excess equipment, not necessary for the production of oil from present wells, such as drilling tools, well casing, etc., should be given a present condition value. In valuing the properties of the Independent Oil Producers' Agency, the Committee has considered the following facts: 1. That from each property there will ultimately be. produced a certain total quantity of oil. 2. That in the production of that oil a certain total quantity of money will be expended. 3. That a certain total amount of money will be received from the oil. 4. That the total net receipts will be the total gross receipts less the cost of development and production. 5. That the present value of the net receipts must be such an amount that when invested by a purchaser it will be returned with 8 per cent. interest additional during the life of the property.

Jan 2, 1918

By V. R. Garfias, H. J. Hawley

FoR a number of years the senior author has been interested in the various geologic and engineering problems involved in the development of the petroliferous districts of northeastern Mexico, having in a previous paper* endeavored to present a summarized statement of the information relating to the geology and soil resources of this region. Of the many interesting geologic phenomena, perhaps those which have been the object of most speculation relate to the igneous intrusions which, in places, have a controlling influence on the accumulation of oil in commercial quantibies, a relationship which has been tentatively explained by various observers with as many interestingly different views. The authors of the present paper aim to record, in the course of a general discussion of the various viewpoints, some additional data, and present further tentative conclusions with a view to rounding out an up-to-date summary of the subject. The greater part of the area in question lies in the State of Vera Cruz, only a northwest fraction being in the State of San Luis Potosi. Vera Cruz is bounded on the north by the State of Tamaulipas, the northernmost of the Mexican States along the Gulf. The topography of the States of Tamaulipas and Vera Cruz and of Texas and Louisiana to the north, is controlled by the Gulf coastal plain which in northern Vera Cruz has an average width of about, 60 miles, the transitional topography between that of the rugged Banks of the Sierra and the lowlands of the coast being made up of a series of terraces and irregular hills and valleys. Geology and StRucture The greater part of the mainland of Mexico is made up of Tertiary and later effusive rocks and of sedimentaries of Cretaceous age. The igneous rocks form a belt from 150 to 300 miles wide, spurs of which shirt

Jan 1, 1918

COLUMBIA SECTION Holds four sessions during year. Annual meeting in September or October. S. S. FOWLER, Chairman, J. C. HAAS, Vice-Chairman, LYNDON K. ARMSTRONG, Secretary-Treasurer, 720 Peyton Bldg., Spokane, Wash. W. H. LINNEY, J. F. MCCARTHY. A special meeting of the officers of the Columbia Section was held in Spokane, Wash., Jan. 10, 1918, for the purpose of organizing and nominating members to the principal committees of the Section. Present: J. C. Haas, Vice-chairman; W. H. Linney, Past Chairman; and L. K. Armstrong, Secretary. J. F. McCarthy, Wallace, Idaho, was appointed fifth member of the Executive Committee. The following were appointed to the Membership Committee: R. M. Betts; for Oregon; W. J. Hall, for Idaho; J. M. Porter, for Washington. A member for British Columbia will be appointed later. The following were appointed to the Committee on Papers: Prof. F. A. Thomson, Moscow, Idaho; Prof. L. 0. Howard, Pullman, Wash.; H. S. Lee, Rye Valley, Ore. A fourth member, representing British Columbia, is to be appointed later. The following members were appointed representatives on the Executive Committee of the Spokane Engineering and Technical Association: J. C. Haas, W. H. Linney, F. A. Ross, L. K. Armstrong. The Treasurer reported a deficit, resulting from the participation of the Section at the Northwest Mining Convention in 1916. It was recommended that the Institute be petitioned to make good this deficit, in addition to the usual annual allowance. The members of the committee who were present expressed their desire to be of greater service in the present war, and discussed at some length the possible means of carrying out their desires. It was later decided to reopen the subject at a subsequent meeting of the Section, or to present it to the Executive Committee of the Spokane Engineering and Technical Association for discussion and cooperative action. L. K. ARMSTRONG, Secretary.

Jan 3, 1918

By William H. Emmons

Discussion of the paper of William H. Emmons, presented at the Canal Zone meeting, November, 1910, and printed in Bulletin No. 46, October, 1910, pp. 767 to S37. CHARLES R,. KEYES, Des Moines, Ia. (communication to the Secretary*) :-It is not in a spirit of criticism that I offer a supplemental suggestion or two on the subjects covered by this valuable and highly instructive memoir. There are two points which, in my opinion, should have received greater emphasis in Mr. Emmons's excellent paper. One is the fundamental role played by the chlorides under certain conditions in ore-formation. The other is the possible establishment of geographic relationships among the four phenomena of (1) excessive chloridic content of mine-waters; (2) the abundance of chloridic compounds of the precious metals ; (3) the presence of. manganese oxides; and (4) the diminishing importance, in ore-genesis, of the metallic sulphates. Although Mr. Emmons's notes refer to gold alone, it may be pertinently asked whether the same principles do not hold good for silver and copper also, since these metals form, together with gold, a distinct and well-known chemical group. That the reactions involved apply equally well to the other two metals mentioned, is shown by a number of recent observations and discussions. Chloridic ores of silver are, as I have lately endeavored to show, mainly worked in. arid or desert regions only ; and the great deposits of disseminated copper-ores are similarly characteristic of such regions, in which both classes doubtless owe their formation to the abundance of saline materials derived from desert dusts, and to the .plentiful and almost universal presence of manganese oxide. Under these climatic conditions, silver is somewhat more abundantly deposited than copper and gold, because its chloride is so much * Received Nov. 11, 1910.

Jun 1, 1911

The following is an incomplete list of members and guests who called at Institute headquarters during the period July 10, 1919, to Aug. 10, 1919. Howard C. Arnold, Washington, Pa. J. S. Lane, New York City, N. Y. L. M. Banks, Denver, Colo. H. W. Lawrie, Washington, D. C. George S. Blair, Pittsburgh, Pa. J. L. McAllen, Latouche, Alaska. Richard H. Catlett, Newark, N. J. David F. McFarland, Urbana, Ill. George L. Clark, Council Bluffs, Iowa. James F. Magee, Lancaster, Pa. Capt. Frederick S. Cook, Portland, Ore. A. G. McGregor, Warren, Ariz. John J. Croston, Atlanta, Ga. Emory M. Marshall, Santa Fe, N. M. Thomas Davis, Seattle, Wash. Benjamin L. Miller, Bethlehem, Pa. J. C. Dick, Salt Lake Cite, Utah. 2d Lieut. C. 0. Noble, U. S. Army. Chris. G. Dobson, Vancouver, B. C. Irving Perrine, Hutchinson, Kans. H. S. Emlaw, Grand Rapids, Mich. Fred S. Porter, Seattle, Washington. F. A. Fahrenwald, Cleveland, Ohio. Capt. H. R. Robbins, Peking, China Lieut. James L. Head, St. Louis, Mo. Joseph P. Ruth, Jr., Denver, Colo. A. A. Holland, Napanu, Canada. William A. Simkins, San Francisco, Calif. W. E. Hopper, Washington, D. C. T .V. Smirnoff, Siberia. Harry Hotchkin, Chicago, Ill. Harrison Souder, Cornwall, Pa. L. L. Hutchison, Tulsa., Okla. F. J. Sur, Denver, Colo. Paul S. King, Wilmington, Del. Harry Wolf, Denver, Colo. George K. Anderson, Jr., lies accepted a position as manager for Wight & Co., producers of air-cooled blast-furnace slag, at Longdale, Va. J. M. Armstrong, with the Caribbean Petroleum Co., has been transferred from Philadelphia to Maracaibo, Venezuela. Fred Sherman Baker, who has been with the Oriental Consolidated Mining Co., at Unsankinko, Chosen, Korea, is now at Columbia City, Ind. Ray J. Barber has removed from Roxbury, Mass., to New York City, and is now consulting engineer for the Roxbury Cold Mines, Inc.

Jan 9, 1919

By Richard P. Rothwell

Though coal has been mined in this country for more than a century, no systematic effort was ever successfully made to ascertain the total amount produced. The production of the Cumberland Basin, Md., and the shipments from the anthracite fields of Pennsylvania, have been placed upon record, thanks to the intelligence and foresight of Mr. C. Slack in the former case, and to the late Mr. B. Bannan in the latter. For some of the years between 1822 and 1842, the production of the Richmond Basin was reported by Mr. R. C. Taylor, but since that date till the author undertook this work it was impossible to obtain any statement of the production of this field. A few of the newer fields, such as that of Mt. Diablo, Cal., have been fully reported, and a few of the newer States have also had this service performed by some intelligent private individuals; but no statistics of coal production have ever been collected either by the State or General Government, if we except the returns for the years 1869—70 of the census report. During the year 1875, by great exertions, I succeeded in obtaining, and July 3d, 1875, gave in the Engineering and Mining Journal what, " though not an accurate statement of our coal production," was " by far the most full and reliable that had ever been published." Though that report showed the production of bituminous coal to be 23,630,094 gross tons, or about six million tons more than had ever before been reported, it was in reality two and a half million tons below the actual output. The more full returns I obtained for 1875 gave many figures for 1874

By James Norman, Oliver C. Ralston

DIATOMACEOUS earth occurs in deposits widely distributed throughout the nation. The chief producing areas are in the Western States, where many high-grade deposits are known. Eastern deposits of diatomite are unsatisfactory for many purposes either because of impurity or because of the extremely fine particle size. Eastern users of diatomite, on the whole, must pay for transportation of the material from the west coast. The freight rate is necessarily high because of the great bulk of the diatomite. A satisfactory process of purifying the diatomaceous earths of Maryland and Virginia, which are unsuited for wide use only because of impurities, should be of value to eastern users. In the past, benefication of diatomite by wet processes has been limited to classification or sedimentation for the removal of sand from diatoms. Calcination with salt is used to produce a white diatomite when iron is present in the impurities, and small amounts of clay are rendered inactive in the process. No treatment has been developed whereby a large proportion of clay can be removed from a low-grade diatomaceous earth to give a diatomite of very high purity. In August 1937 the Federal Bureau of Mines, in cooperation with Dr. R. C. Williams, of Baltimore, undertook the problem of purifying low-grade Maryland diatomite by Froth flotation. Work was done at the Eastern Experiment Station, College Park. Unless otherwise stated, the crude diatomite used was from the Patuxent River deposits near Dunkirk. This material, consisting of roughly one-third each or clay, quartz sand and diatoms, was representative of the usual low-grade marine diatomite found in the Coastal Plain Miocene beds of Maryland and Virginia and sporadically in other Atlantic coast states. As received, it contained 50 to 60 per cent moisture and probably had been wet since its formation.

Jan 1, 1942

By Oliver C. Ralston, James Norman

DIATOMACEOUS earth occurs in deposits widely distributed throughout the nation. The chief producing areas are in the Western States, where many high-grade deposits are known. Eastern deposits of diatomite are unsatisfactory for many purposes either because of impurity or because of the extremely fine particle size. Eastern users of diatomite, on the whole, must pay for transportation of the material from the west coast. The freight rate is necessarily high because of the great bulk of the diatomite. A satisfactory process of purifying the diatomaceous earths of Maryland and Virginia, which are unsuited for wide use only because of impurities, should be of value to eastern users. In the past, benefication of diatomite by wet processes has been limited to classification or sedimentation for the removal of sand from diatoms. Calcination with salt is used to produce a white diatomite when iron is present in the impurities, and small amounts of clay are rendered inactive in the process. No treatment has been developed whereby a large proportion of clay can be removed from a low-grade diatomaceous earth to give a diatomite of very high purity. In August 1937 the Federal Bureau of Mines, in cooperation with Dr. R. C. Williams, of Baltimore, undertook the problem of purifying low-grade Maryland diatomite by Froth flotation. Work was done at the Eastern Experiment Station, College Park. Unless otherwise stated, the crude diatomite used was from the Patuxent River deposits near Dunkirk. This material, consisting of roughly one-third each or clay, quartz sand and diatoms, was representative of the usual low-grade marine diatomite found in the Coastal Plain Miocene beds of Maryland and Virginia and sporadically in other Atlantic coast states. As received, it contained 50 to 60 per cent moisture and probably had been wet since its formation.

Jan 1, 1942

An Outline Classification of Mining Systems for Ore and Coal. See COAL Progress at the Homestake Mine. By Guy N. BJORGE. (Min. & Met., June, 247. 4400 words.) Homestake's mining methods today are controlled to a con¬siderable extent by that which has been done in the past. The two main operating shafts were begun m 1878 and 1896 respectively, so that the location of shafts, loca¬tions of all the drifts on the upper levels, and a great deal of stoping was done before any of those now connected with the mine had anything to do with it In this paper is described the general plan of development. A table shows percentage of total production mined by the different methods in recent years. Average daily produc¬tion for several years now has been about 3850 tons milled. With the present schedule of 6-day operation of the mine, that means about 4450 tons a day mined This ore is treated at three plants, with respective capacities of 2000, 1200 and 600 tons The principal novelty in milling is at the largest mill where the stamps are used as crushers only, and where in the last two years a notable increase has occurred in the size of screens used A unit has been added to cyanide plant No 3 The construc¬tion of a new shaft is described, as is also the hoist building The company operates its own lumber and timber department It has a well equipped hospital Housing at Lead is an individual matter. Rejuvenating the Golden Chariot Property in Idaho. By R. S. MCCLELLAN (Min. & Met, November, 443. 2300 words) An effort to rejuvenate the Golden Chariot group of properties near Silver City is now being carried on by the John Hays

Jan 1, 1935

By James Norman

DIATOMACEOUS earth occurs in deposits widely distributed throughout the nation. The chief producing areas are in the Western States, where many high-grade deposits are known. Eastern deposits of diatomite are unsatisfactory for many purposes either because of impurity or because of the extremely fine particle size. Eastern users of diatomite, on the whole, must pay for transportation of the material from the west coast. The freight rate is necessarily high because of the great bulk of the diatomite. A satisfactory process of purifying the diatomaceous earths of Maryland and Virginia, which are unsuited for wide use only because of impurities, should be of value to eastern users. In the past, benefication of diatomite by wet processes has been limited to classification or sedimentation for the removal of sand from diatoms. Calcination with salt is used to produce a white diatomite when iron is present in the impurities, and small amounts of clay are rendered inactive in the process. No treatment has been developed whereby a large proportion of clay can be removed from a low-grade diatomaceous earth to give a diatomite of very high purity. In August 1937 the Federal Bureau of Mines, in cooperation with Dr. R. C. Williams, of Baltimore, undertook the problem of purifying low-grade Maryland diatomite by froth flotation. Work was done at the Eastern Experiment Station, College Park. Unless otherwise stated, the crude diatomite used was from the Patuxent River deposits near Dunkirk. This material, consisting of roughly one-third each of clay, quartz sand and diatoms, was representative of the usual low-grade marine diatomite found in the Coastal Plain Miocene beds of Maryland and Virginia and sporadically in other Atlantic coast states. As received, it contained 50 to 60 per cent moisture and probably had been wet since its formation.

Jan 1, 1940

By Hans M. Ewoldsen

The generation and evaluation of solutions to body force problems is of extreme interest to the geotechnical profession, as all natural stress states must necessarily include some contribution from the weight of the material. In this chapter the elastic solution for the stress field around a circular, horizontal tunnel at an arbitrary depth beneath the surface of a half-space is reexamined. The influences of body force, initial stress, and free surface proximity are examined and related to in-situ cases. The solution as presented deals only with an isotropically elastic medium; this medium is further considered only in a half-space configuration. It is readily apparent that these restrictions impose severe limitations if analogies are attempted with in-situ cases where geologic discontinuities, inhomogeneities, and irregular boundaries exist. The question might be raised as to the propriety of geotechnically oriented researchers even considering such idealized conditions. There is, however, much to be gained from study of such solutions. The lack of geologic discontinuities and inhomogeneities allows the investigator to separate and leisurely examine such parameters as are included in the solution, without worry of interrelationships of a host of other parameters. Further, elastic solutions have had extensive usage prior to the development of such techniques as the finite-element solution. It is interesting to compare body force solutions with the external field solutions which in the past have been used for design purposes. Finally, the exact solution may be used to verify the accuracy of the finite-element type of solution. The mathematical solution on which this chapter is based was originally developed by R. D. Mindlin.l Because of the complexity and length of the solution, no attempt was made to determine the resultant stress fields until the advent of the present-day high-speed digital computer. How-

Jan 1, 1972

By Lawrence Addicks

(San Francisco Meeting, September, 1915) THROUGH the courtesy of Dr. James Douglas I am permitted to give, a summary of some of the results obtained in leaching slimes tailings in a series of experiments conducted under my direction at Douglas, Ariz.. during the past year. While the test run for which the data are given deals with a particular case, much of the work is general in its application and may therefore be of interest. This work was done upon the ores of the Burro Mountain Copper Co. A description of the geology of the district will be-found in the paper by R. E. Somers published in the May, 1915, Bulletin of the Institute. The mineral is pyrite and chalcocite very finely disseminated throughout the gangue and a characteristic of all the ores is the large amount of alumina present. A representative analysis of the particular ore under consideration would be about as follows: Cu, per cent 2.35 S, percent 3.0 Ag, ounces per ton 0.05 CaO, per cent 0.5 Au None K202, per cent 4.0 Fe, per cent 1.5 SiO2, per cent 70.0 A120,, per cent 13.0 The leaching of the ore direct was early dismissed from consideration for the following reasons: 1. The ore would have to be quite finely crushed to liberate the mineral for leaching; concentrating after crushing would cost but a few cents a ton; and a higher total recovery would result from leaching tailings rather than ore. 2. Rough concentration would yield a suitable material for roasting to make sulphur dioxide or sulphuric acid in connection with the leaching scheme. 3. Such a program put the question of cost vs. recovery on a basis where flotation and discarding of tailings were directly comparable.

Jan 8, 1915

By Thomas D. West

The fact that iron expands when heated, until fusion takes place, and that molten iron is consequently less dense than solid iron of the same grade, is now universally admitted. It was proved by the extensive experiments of Mr. Thomas Wrightson, reported in the Jownal of the Iron and Steel Institute (1890, No. 1, p. 72, and 1891, No. 1, pp. 75, log), and, in a manner, is illustrated in heavy founding by the shrinkage 'of the molten metal, which must be " fed " in order to obtain solid castings. This decrease in volume requiring " feeding" while the metal is still liquid I call " shrinkage," applying the term " contraction" to the decrease in volume which takes place after solidification, while the iron is cooling to atmospheric temperature. The light-work founder, not having the opportunity to make heavy castings, in which shrinkage can be observed, is apt to confound the two; but they are in fact distinct, and are separated by an act of expanion, which takes place at the moment of solidification. The fact of this expansion was first practically demonstrated by Mr. John R. Whitney, of Philadelphia, Pa., whose experiments are recorded in the National Car and Locomotive Builder of May, 1889. Experiments recently made by the writer indicate that there is a constant relation between this expansion and the preceding shrinkage and forcibly demonstrate the necessity of " feeding " a casting to make its interior solid. This is a matter with which all makers and users of castings have experienced difficulty. The founder being heretofore unable to define correctly the principles involving the urgent necessity of " feeding " has failed to impress the moulder with its importance in making sound castings.

Jan 1, 1897

By L. Adler

A relatively simple and effective technique is proposed to deal with the failure of geologic masses containing weakness planes. This technique, termed irextended" rupture envelope, provides a means to clearly distinguish rock and soil from fractured rock and, on a theoretical level, considers a matrix-inclusion system. It may also constitute the link between Mohr's and Griffith's failure theories. Included in the article are five sample problems concerning site location, structural design, strengthening the plane of weakness, changing the magnitudes of major and minor principal stresses and changing the orientations of major and minor principal stresses. Engineers trying to solve design problems in rock and soil mechanics have often assumed an iso-tropic and homogeneous medium. For naturally occurring geologic masses this assumption has always been viewed with regret. The following analysis which deals with the effects of plane anisotropy on failure presents a solution to this. The planes of weakness are joints, faults, bedding planes, fracture and cleavage (natural and induced), foliation and schistosity. The physical properties of these weakness planes include an undulating surface, frictional resistance, discontinuous extent, filling material, tightness and presence of water to cause a hydrostatic pore pressure. All of these properties relating to failure can be summarized in Mohr's rupture envelope for the plane of weakness. This, along with the geometrical orientation, strike and dip, of the plane of weakness produces what is termed an irextended" rupture envelope. MOHR'S STRESS CIRCLE AND RUPTURE ENVELOPE The significant features of these concepts are listed below.' 1) A point on the u - r coordinate plane represents the normal and tangential stress components on a reference area in the material. This area can have any orientation. (Fig. la)

Jan 1, 1963