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By W. A. Gibson, Zay Jeffries

It has been known for a number of years that certain aluminum alloys could be hardened by quenching from a temperature of about 500' C. Immediately after quenching the total increase in hardness is not marked, but the hardness increases gradually so that after about 4 days, it has reached a maximum. The actual increase in hardness probably continues for weeks or even months, but in order to detect the differences after 4 days, it is necessary to make tests at rather long intervals. So far as is known to the authors, Alfred Wilm was the first to discover these properties in aluminum alloys.' The aluminum-copper alloys are amenable to this treatment and the addition of magnesium makes the heat-treatment effect more pronounced. Until recently heat treatment of aluminum alloys has been confined to the worked alloys in the form of sheet or extruded products. The alloy that has been most used in this connection is known commercially as duralumin and has about the following composition: copper not exceeding, 6 per cent.; magnesium not exceeding, 2 per cent.; manganese not exceeding, 1 per cent.; commercial aluminum,2 balance. A typically good alloy in this range consists of: copper, 4 per cent.; magnesium, 0.5 per cent.; manganese, 1 per cent.; commercial aluminum, balance. This alloy can be rolled into sheets or extruded; and in this condition it can be heated in the ordinary furnace atmosphere to a temperature near 500° C. and quenched in water. After about 4 days it will have the following physical properties: tensile strength 55,000 to 60,000 1b. per sq. in. (3866 to 4218 kg. per sq. cm.); elongation in 2 in., 15 to 20 per cent. No harmful effects of the furnace gases or even the air, if the heating is effected in an electric furnace in an air atmospherc.

Jan 1, 1921

By D. J. Jr. McAdam

Fort the past five years, an investigation of the endurance properties of metals has been in progress at the U. S. Naval Engineering Experiment Station, Annapolis, Md. As a result of the investigations at this Station1-5 and other laboratories6-11 "endurance limits" of practically all kinds of carbon and alloy steels have been determined and have been correlated with other physical properties, especially with tensile strength. About a year and a half ago, the investigation at the Naval Experiment Station was shifted to non-ferrous metals. As a result, several papers discussing the endurance properties of numerous non-ferrous metals and alloys, especially the alloys of nickel and of copper12-16 have been published. In these papers, stress-cycle graphs illustrate. the endurance properties of each individual metal and alloy, and other graphs illustrate the effect of cold working, heat treatment, and chemical composition on endurance and other physical properties. Endurance tests of non-ferrous metals were made by the machines used in the endurance tests of ferrous metals. 1-4 The specimen for the rotating-cantilever tests, which has been described, 1,2,13 has a conical surface, with taper so adjusted that the stress is nearly uniform over a length of about 1 ½ in. Alternating torsion tests were made with the machine of the inertia types17 and usually by an accelerated-fatigue method.12 As the rotating-cantilever endurance limits of metals are about twice the alternating-torsion endurance limits, the former values are more generally useful in correlating the endurance properties of nonferrous metals. In several recent papers by the writer13-16 correlation of the endurance properties of a number of non-ferrous metals has been discussed.

Jan 10, 1925

By L. C. Graton

INTRODUCTION CLEAR recognition by Lindgren1 of the important control exerted by physical conditions on the formation of ores laid the foundation for that long-sought attainment, a classification? of mineral deposits based consistently on origin. In probably no other portion of the realm of mineral deposition has the importance of physical influences been so manifest or the validity of Lindgren's genetic classification been so well proved as in that extremely important family of ore deposits which are now universally classed as hydrothermal and generally regarded as of magmatic derivation. While many varieties of deposits, some of them possessing great scientific interest and economic importance, fall outside the limits of this hydrothermal group, inclusion within it of most of the veins and a vast number of the replacement deposits of the world gives to this grand genetic class at once a dominating importance and a powerful scientific appeal. Nowhere are these vein and replacement deposits of hydro- thermal lineage more generously distributed, more extensively exploited or more thoroughly known than in the Cordilleran province of the United States. One of the respects in which these hydrothermal deposits command the interest of both geologists and mine operators is in their relation to depth: the great vertical range through which many of them have already been developed, the disappointing failure of others at relatively shallow levels, and the noteworthy downward changes in character and tenor exhibited by still others. In this hydrothermal category (if the Rand be granted place here) are included the ores of all the very deep mines of the world, ranging from 5,000 to nearly 8,000 ft., as well as of many other mines undoubtedly destined in time to attain corresponding depths.

Jan 1, 1933

By A. M. Kivari

OPERATIONS at the cement plant of the Permanente Corporation, in the hills about 45 miles south of San Francisco and 12 miles west of San Jose, are interesting to the members because of the adoption of modern hydrometallurgical methods for handling and beneficiating raw materials Closed-circuit grinding, classification, hydroseparation, flotation, agitation, and thickening are familiar terms at this cement plant These methods make it possible to process refractory limestone into suitable materials for the manufacture of modern cements Construction of the plant, haying originally a design capacity of 7000 bbl of cement per clay, was started in June 1939, and the first clinker was ground on the following Christmas Day At present the capacity is about 12,000 bbl of finished cement per 24 hr , most of the production being low-heat cement † About 3130 tons of limestone, 620 tons of clay and 100 tons of gypsum are required daily for this output Occasionally iron oxide is added to the clay to obtain the desired composition This, together with the gypsum, is purchased from outside sources Up to the present time, the corporation has produced low-heat, normal, moderate¬ heat, moderate-sulphate-resisting, high-early-strength, oil-well, modified-oil-well, and plastic cements Most of the present production is for Shasta Dam, near Redding, Calif , the told demand being 5,800,000 bbl of cement Following are sonic of the cement requirements of the Shasta D [im] specifications [ ] The average specific surface in the bin s sampled shill be not less Ulan 1800 sq cm per gram and no individual sample less thin 1600 sq centimeters Compressive strength The average compressive strength in pounds per square inch of three mortar cubes composed of one part cement and 2 75 parts fine testing sand, by weight, shall be equal to or greater thin the following

Jan 1, 1941

By Z. T. Bieniawski

The importance of understanding the phenomena associated with rock fracture has long been fully appreciated in rock mechanics. This is clearly apparent from the special attention paid to rock fracture in the comprehensive papers published within the past four years.l-5 These papers present a picture of how the knowledge of brittle fracture of rock was gradually enriched and also show that what was often taken for granted three or four years ago is no longer considered as valid today. The Griffith hypothesis,6 thought in the past to predict the strength of rock, is now known to be applicable to fracture initiation only. The knowledge of a failure criterion for fracture initiation is not sufficient, however, as after fracture initiation the rock is still a useful material even possessing increasing load-bearing ability. The importance of the fracture propagation process, subsequent to fracture initiation, is thus obvious. Yet, relatively little attention has so far been paid to brittle fracture propagation in rock. As it is now realized that understanding of this process is a prerequisite for practical rock mechanics applications, studies of propagation of brittle fracture in rock constitute an important aspect of rock mechanics research. It has been pointed out 4 that it is essential that the failure mechanism is fully understood before a failure criterion is postulated. Many failure criteria have been propounded in the past on the basis of theoretical reasoning alone and could not be verified by experimental evidence. Recently, a hypothesis for the mechanism of brittle fracture of rock was propounded, 4 describing the events taking place in the rock from the initial application of gradually increased load to complete disintegration of the material.

Jan 1, 1972

By W. O. Hotchkiss

Rock exposures are usually a very small part of the surface area in any mining district and the prospector and geologist must base their deductions as to the area, extent, and structure of various formations upon exposures that seldom form 5 per cent. of the area studied. Most often, outcrops form less than 1 per cent. of an area, so that exploration for mineralized contacts or mineral-bearing formations necessitates drilling, test pitting or tunneling, shaft sinking, and other underground work. In these days of high costs any method that will give definite facts regarding rock? obscured by soil or other material should be used to the greatest possible extent. In the early days of the Lake Superior iron districts, mines were located in the few places where ore was present in outcrops. Later, larger orebodies have been found, in depressions, obscured by soil and other foreign material. Mineralized rocks are oftentimes more weathered, softer, and more easily eroded than unmineralized rocks. It is quite natural, therefore, to expect that such orebodies (particularly where large enough to influence erosion in former physiographic conditions) should lie in depressions and be obscured by later debris. It is not difficult to believe that the history of the development of Lake Superior iron mining may be duplicated in other mining districts, that even larger orebodies than those first mined may be found in areas where the rock exposures, which led to original discoveries, are few or lacking. The chief properties of rocks that can manifest themselves through an obscuring cover are magnetism, electrical effects, radio-activity, gravity, and sound transmission. All of these have been used, to a small extent, to tell us a few things about what lies below the surface that we could not otherwise determine, but none has been used so long and so widely as

Jan 1, 1923

By W. O. Hotchkiss

Rock exposures are usually a very small part of the surface area in any mining district and the prospector and geologist must base their deductions as to the area, extent, and structure of various formations upon exposures that seldom form 5 per cent. of the area studied. Most often, outcrops form less than 1 per cent. of an area, so that exploration for mineralized contacts or mineral-bearing formations necessitates drilling, test pitting or tunneling, shaft sinking, and other underground work. In these days of high costs any method that will give definite facts regarding rock? obscured by soil or other material should be used to the greatest possible extent. In the early days of the Lake Superior iron districts, mines were located in the few places where ore was present in outcrops. Later, larger orebodies have been found, in depressions, obscured by soil and other foreign material. Mineralized rocks are oftentimes more weathered, softer, and more easily eroded than unmineralized rocks. It is quite natural, therefore, to expect that such orebodies (particularly where large enough to influence erosion in former physiographic conditions) should lie in depressions and be obscured by later debris. It is not difficult to believe that the history of the development of Lake Superior iron mining may be duplicated in other mining districts, that even larger orebodies than those first mined may be found in areas where the rock exposures, which led to original discoveries, are few or lacking. The chief properties of rocks that can manifest themselves through an obscuring cover are magnetism, electrical effects, radio-activity, gravity, and sound transmission. All of these have been used, to a small extent, to tell us a few things about what lies below the surface that we could not otherwise determine, but none has been used so long and so widely as

Jan 1, 1923

By Harrison Souder

THE object of this paper is to bring to. the notice of engineers a safety detonating fuse by the use of which misfires in blasting may be eliminated and safety in blasting operations promoted. This new detonator is a French invention and is known as Cordeau detonant or detonating fuse and is sold under the name of Cordeau-Bickford. It consists of a lead tube 5 to 6 mm. in diameter, filled with trinitro-toluene. While applicable to all classes of mining it will appeal especially to those who have to do with deep-hole blasting in open-cut clines or quarries, or any operations where a large number of holes are to be shot at one time. Since the introduction of the deep-hole blasting in the Cornwall iron mines, much trouble has been experienced from misfires and many experiments were made to determine the best and safest method of blasting. Before the introduction of the detonating fuse it was found that to insure the best results, two or more high-power electric exploders, not less than No. 6, with specially insulated conductors, should be placed in each hole; the holes wired in parallel, and for a large number of holes the current to be supplied by a live wire to the bus or lead wires at about the middle of the bench. The voltage in general use is 110 to 220, but as our material is a magnetic iron ore and the holes are generally damp, we found it advisable to reduce this to about 30 volts to prevent short circuits. A No. 7 or No. 8 special insulated detonator was adopted. But with the best of care and attention to the minutest detail, we were not able to eliminate occasional misfires and the consequent ever present danger of accidents.

Jan 10, 1914

By James H. Hance

Several years ago the writer was connected with the Mint and Assay Service of the Federal Government as Assistant Assayer at the Salt Lake Assay Office. At that time cyanide bars formed approximately half of the bullion purchased by that office. Disagreement in valuat,ion between the producer and the office was not infrequent and to a lesser extent between the Assay Office and the Mint, this latter issue being soon obviated, however, by adopting uniform methods of sampling the bars. A nice problem seemed to offer itself for research and the writer began a series of experiments which were soon terminated, however, by his going into other work, and which he regrets have not since been completed. The results attained may suggest lines of approach to this problem and are, therefore, offered in this article. Frederic P. Dewey, Assayer of the Mint Scrvice, U. 5. Treasury, has had abundant opportunity to study this phase of metallurgy, and has published several articles relative thereto.1 In the last article cited Dewey quotes analyses of cyanide bullion similar in content to that with which the writer worked, and which show some of the variations met with. In the discussion of these papers,2 comparison has been made in terms of copper bullion, but to the writer this seems of questionable value. Copper bullion may resemble silver bullion, but its similarity to gold bullion with little or no silver content is another thing. The freezing-point diagram of Roozeboom, reproduced on page 881 of the discussion cited, is for the gold-silver series as stated. The original problem under discussion, however, is not this alloy but gold with base metals other than copper. As for the statement that the corners are the worst places or

Jan 1, 1916

By William C. Brice

Minnesota is involved in planning controversies related to taconite and potential copper-nickel mining. Mine facility planning includes the Reserve dining on-land tailings disposal issue and the potential for a new copper-nickel mining district. Both provide a unique opportunity for innovative planning in the attempt to be responsive to public and private interests. Concerns that emanate as a result of mineral resource activities include environmental protection, land use competition, land exchanges, highway and utility extensions, and legal constraints on public or private lands. The purpose of this newly-developed planning approach is to anticipate such issues and provide a rational information base for dealing with them. The result will be a framework plan for guiding public planning, and an impact assessment for reviewing the implications of industrial project proposals. The approach uses a computer-stored resource inventory of natural and cultural information. Geographic data is mapped and entered into a computer storage and retrieval system. This enables systematic analysis of mineral resources along with environmental and land use considerations. Computer mapping describes the relationship of each activity and allows identification of potential conflicts; it also shows geographical extent in the form of statistical compilations. Resource data is being collected and compiled using a standard metric grid (Universal Transverse Mercator). Individual cells are 100 m. squares and represent areas of about 2.5 acres. The study area contains about 145,000 cells. Data inventories are being compiled in 25 natural and cultural resource categories. Geologic variables include Bedrock Geology, Taconite Reserves and Potential Resources, Depth to the Duluth Complex Contact and two soil inventories. Topographic and hydrologic variables include elevation, slope, slope orientation, surface hydrology, and watersheds. There are also 6 biological data variables and 7 land use inventories.

Jan 1, 1977

By N. V. Melnikov, L. N. Marchenko

The latest theoretical and experimental study of physical processes initiated by explosions in solid media have made it possible to obtain a deeper insight into the mechanism of the energy transfer to ambient rock from char es of explosives interspersed with various air gaps. As shown in (17, high explosive action causes excessive fragmentation of medium in the vicinity of the charge, while expansion of the process into the massif is negligible. A theoretical outline of a more rational application of explosion energy was given with a view of obtaining more uniform fragmentation of rock convenient for loading and transportation. The proposed idea proven by experimental study consisted of the possibility of explosion control based on redistribution of explosion energy. Practical realization of the above idea was proposed (1) involving charges with air gaps for rock fragmentation. Since the Rolla Symposium on Mining Research (USA, 1961) (2), borehole charges with air gaps have become common practice. This method of rock blasting is applied in open cast and underground mines working the hardest and viscous, hard, medium hard and soft rocks (ore, quartzites, granites, 1 imes tones, sandstones, coals, etc.) as well as at enterprises for extraction of building materials and raw chemical minerals of any strength. Application of charges with air gaps results in an increase of the degree and uniformity of fragmentation (up to 94 percent of the blasted rock mass consists of fragments not exceeding 400 mm), the average fragment size decreases by 1.5-2 times and the amount of lumps is reduced by 2-10 times (in some cases there are no lumps at all ). Besides, the amount of operation for filling boreholes with tamping material is reduced, the specific consumption of explosives

Jan 1, 1971

By David W. Brunton

Mine-drainage and the ever-increasing demand for water on the plains have within the past few years necessitated the driving of a great number of adits and tunnels, including many of considerable size and great length. In most instances, existing conditions have called for extreme rapidity of execution; and this necessity, coupled with the high altitudes at which most of the work has been carried on, excessive freight-rates, and difficulty of access, has involved many complex and interesting problems. One of the most rapidly executed undertakings of this class is the Laramie tunnel, recently completed for the Laramie-Poudre Reservoirs & Irrigation Co. This tunnel is driven through Green ridge, a spur of the Continental Divide, which separates the Laramie river from the Cache-la-Poudre in Laramie county, Colo. Green ridge is extremely persistent, and further northward in Wyoming is known as Sherman hill, the highest point on the Union Pacific railway. At the point where the tunnel is driven, two opposing bends bring these streams within 2.5 miles of each other, with a difference in elevation of 500 ft. The rock exposed on the banks of the two rivers does not differ materially in hardness; and, without a geological study of the conditions involved, it would appear that the difference in the depth of erosion of the two streams is due principally to the greater volume of water at this point in the Cache-la-Poudre, which has a drainage-area above the tunnel-portal of 110 sq. miles, as against 30 sq. miles of natural drainage for the Laramie. To increase the water-supply at the tunnel, however, this latter amount has been augmented by two side collection-canals, which bring the available drainage-area up to 84 square miles. The nearest railroad shipping-point to the eastern portal is

Jan 1, 1913

By William E. Hubbard

The production of the Texas Panhandle1 up to Jan. 1, 1932, was slightly under 179,000,000 bbl., 90 per cent of which came from Hutchin-son and Gray counties. About 21,500,000 bbl. were produced during 1931. This was about 35 per cent less than the 1930 production and the smallest annual production since the first boom started seven years ago. The present daily production is slightly under 55,000 bbl., which is the production permitted under statewide curtailment. The assumed potential for the purpose of curtailment is 108,708 bbl. and the actual capacity of the wells is probably in the neighborhood of 75,000 barrels. The total initial production of the oil wells completed in 1931 was 40,714 bbl. from 117 wells or 347 bbl. per well as compared to a 511-bbl. average from the 304 oil wells drilled during the preceding year. Gray County led with 71 completions and a total initial production of 29,209 barrels. Completions Two hundred wells were completed in the Panhandle in 1931, as against 526 in 1930. Of the year's completions, 117 were oil wells, 77 produced gas, and but six were dry holes. Of the 3197 wells drilled in the Panhandle to date, 2944 have produced oil, gas, or both, making the ratio of dry holes to producers about 1:11.7. Ignoring the 64 dry holes drilled in nonproductive counties the ratio becomes 190:2944 or 1:15.5, which is somewhat more favorable than that obtained at the end of 1930. Of the oil wells completed 374 have been plugged. Although it is but five years since the peak of drilling operations more than one-fifth of the oil wells in Hutchinson County have been plugged. The percentage of total wells plugged to total completed oil wells, by counties,

Jan 1, 1932

By E. P. Mathewson

In a discussion of a paper on The Basic Process as Applied to Copper Smelting, by Percy C. Gilchrist, read before the Society of Chemical Industry, London, Jan. 5, 1891,' Prof. W. C. Roberts-Austen asked Mr. Gilchrist whether he thought that the substitution of a basic lining for acid lining in the Manhks process would afford anything like the service which it had been shown to render in the metallurgy of iron. Claude Vautin stated that he had experimented for over two years. with basic linings for Bessemer converters for copper mattes at Cobar, but had given up the attempt on the score of cost. Mr. Gilchrist in his reply stated that he did not believe in applying any system of Bessemerizing to copper. About the time of the presentation of the paper mentioned,Hermann Keller, Superintendent of the Parrot smelter, in Butte, was experimenting on a large scale with converters lined with magnesite brick. He gave up the idea on account of the cost of linings and because no particular advantage was observed. My belief is that his tuyeres and converters were too small. A short time afterward similar experiments were tried at the Great Falls plant of the Boston & Montana Co., and at the Old Works of the Anaconda Copper Mining Co. in Anaconda. These were abandoned on the score of cost and the lack of advantages. The same cause of failure, in my opinion, holds here. The Anaconda Copper Mining Co., however, adopted the magnesite brick lining for its tilting casting machines. Fig. 1 is a view of the first tilting furnace casting copper. It was made from an old Brueckner roasting cylinder. Fig. 2 shows an elevation and vertical and horizontal longitudinal sections of the second tilting furnace, built in 1897.

Jan 1, 1914

By C. M. Weld

The southeastern coast of China, from Ning-Po to .Macao, represents an element in the continental mass of Asia which has at practically all times in the remote past exhibited a tendency to rise rather than to subside.' This strip of land, 1,000 or more miles long by perhaps 150 miles wide at its widest part, has in fact stood above sea level since at least early Cambrian times, while the great basins to the north and west were receiving their massive accumulations of Sinian (Cambro-Ordovician), Carboniferous, and later deposits. We find, .therefore, a coastal fringe of metamorphic and igneous rocks bordering the huge expanses of sedimentary rocks which occupy the interior. Hong-Kong is situated toward the southwestern extremity of this fringe. Hong-Kong is an island of approximately 30 sq. miles, on the north shore of which is situated the city of Victoria, with its 325,000 inhabitants. This island was ceded to Great Britain in 1842. In 1560 the peninsula of Kowloon (about 5 sq. miles), being that part of the mainland lying directly across from the city of Victoria, was added to Hong Kong. Thirty-eight years later, in 1898, a stretch of territory, including the mainland behind Kowloon and. numerous adjacent islands, was leased to Great Britain for 99 years. This last addition is known as the "New Territory of Hong-Kong" and comprises 376 sq. miles in area. A map of Hong-Kong, Kowloon, and the "New Territory" is shown in Fig. 1. My studies of this total area of over 400 sq. miles were devoted primarily to an investigation of the mineral resources. Systematic mapping of the immensely complex exposures of rocks was not possible in the time at my disposal. However, observations in, this. direction warrant a few generalizations.

Jan 2, 1914

By C. A. Mitke

During September, 1911, the fire area in the Lowell mine continually increased and gases resulting from the fire came through the upcast shaft. These gases contained such a large percentage of sulphur dioxide that the men were unable to go up and down on cages, and, within a comparatively short time, repairs in the shaft mere found to be necessary. Since the fire was in sulphide ores and extended into certain timbered sections, the gases contained varying amounts of SO2, CO2, and perhaps, at times, CO. The temperature in the shaft was generally about 97", and the relative humidity from 97 to 99.5 per cent. The corrosive action of the fumes became apparent when the cables had to be changed more often than usual, the heads of lag screws in the guides of the shaft disappeared, and the cages needed frequent repairs. It also became necessary to repair two compartments of the shaft by putting in 150 ft. of new guides between the 600 and 800 levels and lag screws in nearly all the old guides from the surface to the 800 level. 2. Ordinary Methods of Testing Helmets which were Unsatisfactory. These conditions required all work to be done by men wearing oxygen helmets. The Draeger type was tried, and was used until all repairs were completed. At first the helmets were tested for air circulation and air tightness and the injector mas tested by water gauge according to the methods recommended by the Draeger Oxygen Apparatus Co. Six arrangements, covering these different tests, are illustrated in the catalogue and circulars of the company. After the above tests had been made on the oxygen apparatus, the men still complained about leaky helmets. Small quantities of gas entered the helmets and could not be detected by these methods. The

Jan 1, 1914

By Damon H. McFadden

5.1-1. Geographic and Geologic Factors. Surface mines are located where the coal seam can be economically uncovered and where the product can be utilized competitively with other fuels. The planning and designing of a pit may follow various procedures. The sequence for consideration of the influential factors as considered here may not be complete for every pit, nor will it be necessary to be completely used in each design. It is suggested as a check and outline for the engineering approach. Controlling conditions for the layout should be listed and considered with the facilities and equipment for the exploitation. After these items, as listed below, have been discussed and the feasibility agreed upon, then the actual planning and design of the pit can be done. GEOGRAPHIC FEATURES. The location of the coal area sets the climatic stage. The rainfall, the temperature extremes, and the general weather conditions all affect the design of the pit. Overburden soil when wet may not be stackable and may be impossible to move by standard procedures. The coal seam itself may be so soft that it must not be traveled on when wet, as the losses may be the difference between a profitable venture and an unsuccessful one. Some equipment will work well on dry soil only, just as a dredge works only in the wet. The conditions must be checked and analyzed. Some equipment cannot handle frozen soil (wheel excavators), so temperature extremes must be noted. The extreme weather conditions may also govern the expected working days and therefore the ultimate production. The altitude (atmospheric pressure) may affect the equipment, and this should be checked. All of these conditions should be noted on the preliminary map of the area. GEOLOGIC FACTORS. The geologic and surface conditions of the coal field dictate the type of pit generally feasible. Rough terrain, rolling terrain,

Jan 1, 1968

By George J. Young

The recurrence of mine-fires in Nevada during the past decade is not only a matter of interest, but also one of considerable concern to engineers and mine-managers. The more important fires may be enumerated as follows: Forman Shaft fire, Gold Hill, April 21, 1903; shaft-house, machinery, and shaft destroyed; loss estimated at $50,000; cause unknown. Union Shaft fire, Virginia City, July 14, 1904; shaft-house, machinery,and shaft in part destroyed; loss estimated at $100,-000; cause of fire stated as the careless throwing of a match in the rope-house. Sutro Tunnel fire, Virginia City, Jan. 27, 1909; 700 ft. of tunnel-timbering destroyed, and direct damage of $10,000; cause " probably electric wires." Belcher Shaft fire, Gold Hill, Aug. 9, 1910; shaft-house destroyed, machinery ruined, and upper part of shaft damaged; damage, $25,000; no cause given. Belmont Mine fire, Tonopah, Feb. 23, 1911; fire started ill winze; 17 men killed. Giroux Mine fire, Kimberly, Aug. 23, 1911; fire originated in shaft-station from unknown cause; 7 men killed, and $34,-521 damage caused. (Note 1.—On June 11, 1912, some time after the present paper was written, a fire broke out in the pump-room on the 2475 station of the Ward shaft, Virginia City. This fire was caused by the short-circuiting and exploding of the starting-switch on No. 5 pump. The oil in the switch was scattered about and set fire to the timbers and lagging of the pump-room. The pump-man in charge notified the surface, and the electric current was shut off. A hose was then turned on the fire, but the dense smoke drove the attendant out. Inspection by the electrician and the shaft-foreman, equipped with oxygen-

Jan 1, 1913

By Foster Bain

THE outstanding characteristic of the last hundred years has been the world-wide rise in the standard of living. Man's dominion over nature is increasing with an accelerating pace and more and more the forces and materials of this world are being made to serve man's necessities and his convenience. We demand both quantities and varieties of goods that were beyond the dreams, to say nothing of the reach, of our fore-fathers, and our possession of them has become so much a matter of course that they excite no remark. Literally, thousands of young folks have required an explanation of a recent popular song, "Thanks for the Buggy Ride," for the reason that their own experience does not extend back into the pre-flivver age. This transition from the use of vehicles made mainly of wood and drawn by animal power, to metal made cars propelled by mineral fuels is all but complete and the memory even of older conditions is already fading. This is symbolic of what is happening all around us. In a recent book, Dr. Frank J. Goodenough, president of Johns Hopkins University, referred to Chinese civilization as a ?vegetable" civilization meaning thereby that the Chinese depend mainly upon the plant world for food, clothing and other necessities and luxuries. Our own people did the same hardly more than a hundred years ago. In 1820, this country produced and used only 5 lb. of pig iron per capita, but a quick and enormous change was wrought in the hundred, years that followed, and in 1920 the amount was 119 times as much, or 597 lb. It has since increased even beyond this and touched a peak of 809 lb. in 1923. In that year our output was more than twice that of 1903 and nine times that of 1883. This increase in production

Jan 10, 1926

By William L. Fink, Dana W. Smith

Approximately two years ago the authors obtained data that indicated that initial precipitation could not be detected by change of lattice parameter in the aluminum-rich aluminum-magnesium alloys. Some of these data were first published in a brief note in Mining and Metallurgy'. Cast specimens were used at that time and they showed initial precipitation relatively sooner than sheet material of the same composition. For this reason a more thorough investigation has been carried out using a homogenized aluminum-magnesium sheet corltairling approximately 10 per cent magnesium. Materials.—The aluminum used in the preparation of the aluminum-magnesium alloy was of high purity, containing less than 0.01 per cent each of iron, silicon and copper. The magnesium was high-purity sublimed magnesium. Preparation of Alloy.—Approximately 4 kg. of the aluminunl was melted in a plumbago crucible in an electric furnace and the magnesium was added. The melt was thoroughly stirred with a graphite rod and fluxed with chlorine gas before casting. The alloy was cast in the form of a sheet ingot in a cold iron tilting mold (approximately 200 by 165 by 40 mm.) and into small chill-cast slabs for chemical analysis (75 by 40 by 5 mm.). The chemical analyses were made upon drillings from the analysis slabs. The analytical methods were those described in "Chemical Analysis of Aluminum," published by the Aluminum Company of America. The composition of the alloy was found to be: magnesium 10.30, silicon 0.013, iron 0.008 and copper 0.005 per cent. In order to insure homogeneity the alloy was given two intermediate anneals at 430' C. for a total time of 36 hr. The ingot was hot-rolled

Jan 1, 1937