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By E. Klar, A. B. Michael

Differences in the electrical conductivities of copper powder sintered under reducing, selectively oxidizing, and neutral atmospheres are related to impurities in solution or as precipitated oxides. The precipitation of impurities as oxides during sintering in nitrogen is proposed for maximizing the conductivity of sintered copper. Conductivity equations for two-phase systems are summarized. Selected equations are applied to porous sintered copper and composite structures. A recent review of the influence of impurities on the electrical conductivity of copper by Gregory et al.1 emphasized that an impurity in solid solution has a much more pronounced effect on reducing the electrical conductivity than when present partly or wholly as a second phase. When impurities in solid solution can be precipitated as oxides, the copper is purified with respect to these elements and the conductivity is increased. Cast and wrought copper, therefore, frequently contain an intentional residual oxygen concentration to oxidize and precipitate impurities less noble than copper. Copper powders generally also contain impurities which can contribute to a reduction in the electrical conductivity of the sintered material. The most deleterious impurities commonly found in commercial copper powders which markedly decrease the electrical conductivity when in solid solution but which can be precipitated as oxides include iron, tin, antimony, arsenic, cobalt, and nickel. In addition to impurities, porosity in sintered copper also contributes to a reduction in the electrical conductivity. The work reported herein discusses the influence of impurities, sintering atmospheres, and porosity on the electrical conductivity of sintered copper. These are important factors for controlling the electrical conductivity of materials such as sintered copper electrical contacts. Several publications on the electrical conductivity of sintered copper and composite materials with random pores or obstacles have incorrectly considered the conductivity to be proportional to the volume fraction of conducting material. However, analyses and equations have been proposed, the earliest of which is perhaps Lord Raleigh's of 1892,' which more accurately describe the conductivity of two-phase systems. These equations which in many cases allow one to closely estimate the electrical conductivity of porous sintered materials and two-phase composites will be reviewed and related to the measured electrical conductivity of sintered copper, copper-graphite. and Ag-W composites. INFLUENCE OF IMPURITIES AND OXIDIZING, REDUCING, AND NEUTRAL ATMOSPHERES Zone-Melted and Leveled Copper. The electrical conductivities of an electrolytic copper and a lower-purity compacting grade of copper powder after consecutive treatments in reducing or selectively oxidizing atmospheres are compared in Fig. 1. The powder and drillings from the electrolytic copper ingot were melted and solidified in a graphite crucible under hydrogen. The vertical zone leveling technique of multiple passes in opposite directions was used to obtain a uniform distribution of impurities. The electrical conductivity was measured on machined specimens 3 by 0.10 in. diam of the zone-leveled material and after the same specimens were consecutively treated as follows: 1) heating in hydrogen at 1600°F for 3 hr; 2) heating in air in a sealed tube so that 0.04 pct 0 was introduced; heating was started at 1000°F for 1 hr and continued at 1800°F for 8 hr; the stepwise diffusion treatment was used to avoid loss of copper due to evaporation of copper oxide at higher temperatures; and 3) final heating in hydrogen at 1600°F for 3 hr. A L&N Kelvin Bridge, type 4306, and a test fixture with knife edges 2 in. apart were used to measure the room-temperature conductivity with an estimated accuracy of ±0.5 pct. In all cases the conductivity of the electrolytic copper was approximately 100 pct of IACS. The conductivity of the impure copper was 80 pct of IACS both in the cast state and after heating in hydrogen. However, after the heating in air, the conductivity of the impure material was 100 pct IACS. After again heating in hydrogen, the electrical conductivity decreased to 60 pct of IACS. This decrease is attributed both to the dissolution of impurities and observed intergranular cracks due to the phenomenon of hydrogen embrittle-ment in copper. These data show that the electrical conductivity of commercial copper as represented by a compacting type powder can be increased significantly by the precipitation of impurities as oxides through heat treatment in an oxidizing atmosphere. Sintered Copper Powder. A commercial compacting type of copper powder pressed to various densities was sintered either in nitrogen, dissociated ammonia, or dissociated ammonia followed by a selectively oxidizing atmosphere of air in sealed Vycor tubes so that 0.06 pct O was added to the material. The electrical conductivity was measured perpendicular to the pressing direction on as-sintered specimens of approximately 3 by 0.25 by 0.15 in. The fully dense material was obtained by zone melting and leveling

Jan 1, 1969

By Burt A. Waite

The new OSM regulations for ground water monitoring of underground coal mines have been the source of many concerns for the mining industry. Because the regulations were initially written at the federal level, but are being administered at the state level, considerable confusion still exists within the industry as to what is really required. Based on submission and/or approval of more than 30 monitoring plans for existing mines in Pennsylvania, West Virginia, and Ohio, three basic sections are necessary. They are: 1. background data on the hydrogeologic setting of the mine, 2. the monitoring plan itself, and 3. mining procedures to minimize adverse effects on ground water. Like all of the OSM requirements, ground water monitoring will be a new burden the coal industry must bear, but with proper planning and communication with the regulatory authorities it need not be as bad as originally feared.

Jan 1, 1983

By S. A. Allison, N. P. Finkelstein

After a brief consideration of the properties of zinc sulfide minerals, their flotation characteristics, and their reactions with thiol collectors, the literature on the activation of the minerals by cupric ion, their deactivation by cyanide, and their depression is reviewed in detail. The distinction between deactivation and depression is stressed. The contradictions in the published results and theories are discussed and attempts are made to resolve them. It is concluded that, whereas all aspects of the subject require further investigation, the study of depression is most likely to yield benefits in practice.

Jan 1, 1976

By Frederic Lahee

THE total production of crude oil in Texas during 1924 was said to be 133,613,985 bbl. as compared with 125,991,628 bbl. in 1923.1 Subtracting from these figures the yield of the Gulf Coast fields, there remains, for the other part. of Texas, a yield of 106,272,573 bbl. in 1924, as compared with 101,931,595 bbl. in 1923. This represents an increased, production of over 4,250,000 bbl. for all of Texas outside of the Gulf Coast or Salt Dome fields. Within this same region, in 1924, there were 3624 completions, of which 2352 were oil or oil and gas wells, 7 were gassers, and 1265 were dry holes. Thus, nearly 35 per cent. of the completions were dry holes. In 1923, there were 4134 completions, with 2853 oil or oil and gas wells, 2 gas wells, and 1279, or 31 per cent. of the total, dry holes. Outside of the Gulf Coast region, six major pools were discovered and developed in 1924.; two pools, previously discovered, were extended far beyond their limits at the end of 1923, and many smaller pools were opened. The major pools were the Big Lake field, in Reagan Co., the New Richland field, in Navarro Co., the Harmel, Carey, and Ragle pools, in south Archer County, and the Wortham field, in Freestone and Limestone Counties. Fields that were notably extended were the Panhandle producing area and the Luling field. Many wildcat wells have been drilled; most -of these were failures, but several opened .pools and several have had sufficiently favorable results to. lead to further drilling. The activity of the operators in searching for new production was very intense during 1924, and indications point to as feverish a campaign during the coming year. This will be stimulated by rising prices for crude oil. There are good reasons for believing that new pools will be discovered along the Mexia fault zone, in Archer, Young, Baylor, and Throckmorton Counties, in the great central region of Texas where we now have the Mitchell County and Reagan County pools, and very likely in the eastern Red River Counties including Cooke and Grayson. On the other hand, with the opening of the year, there is no new big pool in sight. An outstanding feature of the production end of the business is the increasing reliance placed on geological work and geological recommendations. Not in five or six years has there been such a demand for first-class geologists.

Jan 3, 1925

By J. S. Diller

In 1827, chromite was discovered near Baltimore by Isaac Tyson, Jr., who initiated the mining of chrome ore an:! later (1845) .the manufacture of chromium compounds in this country. From 1828 to about 1860 the United States, supplanting Russia, supplied chromite for most of the world. Chrome deposits were found also in California, and the Tyson Company shipped ore to Philadelphia by way of Cape Horn. In 1848, J. Lawrence Smith, an American in the employ of the Porte, discovered large bodies of chromite in Asia Minor. They were developed in 1865 and became the chief source of the world's supply for a number of years. The discovery of the large high-grade bodies in New Caledonia, and later in Rhodesia, with other foreign sources, gives at present an abundant supply for all demands. For a number of years before the great war, the United States produced only a few hundred tons of chromite annually, for local use, but during the war the demand for domestic ore resulted in a production of more than 82,000 long tons of crude ore in 1918, and it was demonstrated that the United States has reserve deposits equal to a war demand of several years' duration. Now that the war is over, the country is conserving its domestic supplies by employing higher-grade but cheaper ore from foreign countries. ChromiUm-bearing Minerals Oxides: Chromite-—chromic iron ore................ FeO.Cr2O3 Picotite—chromic iron ore................. (MgFe)O.(Al,Cr) Chromates: Crocoite—lead chromate................... PbCrO4 Phoenicochroite—basic lead ohromite........ 3PbO.2CrO3 Vauquelinite—phospho-chromate of lead..... 2(PbCu)CrOd.(PbCu)3P2O8 Sulfates: Redingtonite—hydrous chromium sulfate.... Knoxvillitel—hydrous basic sulfate of chromium.............................. Daubreelite-—iron-chromium sulfide (known in meteorites only)...................... FeS.Cr2S3

Jan 1, 1920

By George H. K. Schenck, Peter G. Donald

There is an accelerating acceptance of change by management of cement companies. Diversity of response is noticeable in efforts across the country to reverse the downward trend in profits that brought margins in 1966 to the lowest point in 20 years. New concepts are emerging among managers as they seek to increase the efficiency in use of the basic corporate resources of men, capital and technology. The shift towards computerized control of cement manufacturing is making new gains as is diversification of cement companies into allied fields such as production and sale of natural and light- weight aggregates, crushed stone and concrete products. Increased interest in special products such as white cement and further moves overseas are also significant. Perhaps the most dramatic event of recent years occurred in Washington at hearings before the Federal Trade Commission where cement producers split on whether there should be FTC guidelines that would prevent ownership of ready-mixed concrete producers by cement companies.

Jan 4, 1967

With the exception of the mentions of coal in Illinois in the period 1660-1680, already referred to, the first coal found in the United States was in the James River, Virginia, field. In 1699 a large tract of .land above the present city of Richmond was allotted for a settlement of French Huguenots by the colonial, government, near the present Manakin, about fourteen miles above Richmond. They soon found coal, tradition says it was uncovered by a hunter pulling out a small tree in a. steel) bank near a stream, and Colonel William Byrd, F.R.S., the most prominent man of his day in the colony, wrote to the Colonial Council of Virginia, May 10 and 11, 1701: "The 10th of May, last., I with Coll. Randolph, Capt. Epes, Capt. Webb, &c., went up to the new settlements of ye French Refugees at ye Manaken Town.... We went tip to ye Cole, w'ch is not above a mile and a half from their settlement on the great upper Creeke, w'ch, riseing very high in great Raines hath washed away the Banks that the Coal lyes bare, otherwise it's very deep in the Earth, the land being very high, and near the surface is plenty of Slate.", Some of the Frenchmen were evidently familiar with the use of coal, as on May 22, 1702, "David Menestrier a black smith and one of ye french Refugees Inhabiting at Luciana Petitioning his Excellency that he may have leave to use ye coal mines lately discovered there for his forge his Excellency by and with ye advice of ye Council loth hereby give Leave to ye said David Menestrier to take what coales he shall want. out of ye said Coal mine for ye use of his forge according to ye Prayer of ye said Petition."2 There was some uncertainty about the grant of these lands to the Huguenots which caused the request for leave to use this coal, as a Virginia patent in its usual form allowed the owner to mine all minerals excepting gold and silver, which were subject to royalties for the Crown. After the visit to the coal above mentioned, "Wm. Byrd, understanding the land had not been granted to the French, took out a patent for 344 acres, including the same, (the coal) which patent was dated October 20, 1704".3

Jan 1, 1942

By Walter E. Mingramm

THE construction of rescue-apparatus on the principle of furnishing the wearer with air from a tank containing it under high pressure was given up by inventors about 20 years ago. Such an apparatus must supply continuously, for not less than two hours, nearly 50 liters of pure air at atmospheric pressure per minute, or a total of 6,000 liters (210 cu. ft.); and a cylinder containing this amount of air, under 2,000 lb. pressure, would weigh 180 lb. or more. Although apparatus has been recently constructed utilizing liquified air, no experiments have been made to determine the regularity with which the air is generated, nor has its chemical composition been determined. Moreover, the chief objection to such an apparatus is the' difficulty and cost of keeping on hand a large quantity of liquified air. The system of furnishing the wearer of a breathing-apparatus with air which has given the best results, and has found employment in all the devices now in practical use, is that in which the air contained in the human lungs at the beginning of the work is regenerated by the apparatus. By means of chemicals, such as caustic potash and caustic soda, the carbonic acid gas, CO., exhaled is absorbed, and the oxygen that has been consumed is replaced from a tank containing this gas under high pressure. The pressure of the oxygen (which is 1,875 lb. in the two cylinders at the beginning of the work) is automatically reduced to 75 lb., and is sufficient to keep the air inside of the apparatus in constant circulation, and to force it to pass through the chemicals provided for the absorption of the CO, gas. In the attempt to construct an apparatus which would (1) furnish the wearer with a sufficient supply of air; (2) replace the amount of oxygen used up by the lungs during the time of

Jan 7, 1908

By Allen L. Hatch

A survey of all phases of the world's lead and zinc production in 1968 from ore through to refined metal was conducted by sending questionnaires to individual companies and the results of this survey are tabulated at the end of the paper. The paper goes on to review changes in the geographical distribution of the world's lead and zinc mine and metal production and in the trading patterns of raw materials, present and future utilization of metal production capacity, developments in metal smelting and refining processes and the growing importance of marketing, product development and research in the 1950's and 1960's.

Jan 1, 1970

By P. BOURY

THIS account of a contrivance which has been found serviceable in practice may be of interest to engineers, and' especially to those engaged in hydraulic mining. In that process, one feature which seems at first sight to possess little significance, is highly important in its effects, namely, the regular supply of water to the " giants." The chief condition of this regularity is an even flow in the pipe-line from the penstock to the nozzle. This, of course, requires that the penstock be kept full. Any considerable surplus of water, overflowing at the penstock, is a simple waste, unless it be otherwise utilized in the sluices. At all events, it does not affect the delivery of the nozzles. But a deficiency at the penstock may admit air into the pipe; and this may produce hydraulic recoil, injuring the line by incessant vibrations, giving rise to leaks, and even to blow-outs, and (when a partial vacuum exists at the time of the fracture the collapse of the pipe. An accident of this sort in our main pipe-line, occasioned partly by a settling of the ground and partly by the presence of air in the pipe, led to the employment of the device here described. The line referred to is made of 30-in. pipe, successively reduced to 18 and 15 in. in diameter, for the supply of two giants. By reason of the causes above mentioned, the 30-in. pipe burst more than 1,400 ft. from the penstock, and, despite the air-valve, the 30-in. pipe was collapsed to such a degree that one length of it, next to the penstock, was squeezed together and positively swallowed by the main pipe, through which it traveled for 750 ft., piercing through a short elbow on the way. This remarkable result was undoubtedly the effect of the vacuum suddenly produced when the pipe burst.

Sep 1, 1906

By A. C. Fieldner

DURING 1939, 286 by-product coke ovens were completed and put into operation. These included 140 Witputte ovens for the Carnegie-Illinois Steel Corp., at Gary, Ind.; 61 Koppers-Becker ovens for the Ford Motor Co., at River Rouge, Mich.; 65 Semet-Sotvay ovens for the Great Lakes Steel Corp., Zug Island, River Rouge, Mich.; and 20 Curran-Knowtes ovens for the Midwest-Radiant Corp. plant at Mitlstadt, Ill. The Millstadt plant is unique in carbonizing a washed coat containing 3.50 per cent sulphur. The gas contains approximately 2500 grains sulphur per 100 cu. ft.; this is successfully removed with sodium carbonate solution by the Seaboard liquid purification process. The coke is intended primarily for use as a smokeless domestic fuel in the city of St. Louis.

Jan 1, 1941

By Paul L. Horrer

Costly damage by severe wave attack to many engineering structures has illustrated the need for a consideration of the nature of wave action in plans for offshore drilling operations. Using wave data it is possible to answer questions pertaining to engineering problems such as platform elevation, structure orientation, and expected wave forces. For locations where wave records are not available a technique can be used to obtain information about wave characteristics from past meteorological data and near shore submarine topography. Forces exerted on structures by waves may be divided into four parts. A completed study is given in which frequencies of various wave heights and maximum frictional drag forces are computed for a typical offshore drilling site. INTRODUCTION Waves of tremendous proportions accompanying hurricane winds crash against breakwaters and other offshore structures causing untold damages. Wave forces exerted on structures at these times are enormous, as shown by past records of incidents where massive portions of breakwaters have been broken off and moved by waves. On other similar occasions, whole structure; have been unloosed and smashed or floated away. These incidents, which seem almost incredible, serve to illustrate the great amount of energy contained in large waves, and to show that this energy results in powerful forces destructive to offshore installation~ which are not designed sufficiently strong to withstand wave attack. In the past the expected frequencies of waves having various characteristic.% have rarely been considered in the design of structure affected by wave action. As a result, many structures have failed to accomplish the purpose for which they were designed or have collapsed under wave attack. Others have been constructed to withstand greater wave energy than is ever encountered, with resulting waste of material and construction time. In this study an analysis is made of the frequencies of waves having different characteristics which affect the plans for offshore drilling installations. After such an analysis the erection of these structures can proceed with less risk involved and with more efficiency and economy. ENGINEERING ASPECTS In the offshore drilling program wave forces play an extremely important part in design and construction of drilling rigs in shallow water. The design of a platform or other structure from which drilling equipment is operated is critical, becauze any damage to the platform may endanger personnel and result in complete loss of equipment. Since a platform built too close to the water would be battered by breakers, and one built unnecessarily high would involve undue expense, it is necessary to know the most desirable elevation at which the platform should be erected. This is only one of many questions about structural planning which can be answered using existing technique for determining wave characteristics. The purpose of efficient design for the portions of many types of offshore structures which are acted upon by wave forces is the same as that of all designs which deal with frictional forces of a fluid on a solid. For these structures the problem is comparable to that encountered by undersea craft moving through water, except that in the case of a fixed structure the force is produced by the water moving past the model. For off shore sructures which are extremely rigid the frictional forces may be nearly negligible compared with the impact or shock forces imparted by breaking waves. In all case; the better design is that which offers the least resistance to the opposing forces. From a consideration of wave forces, each drilling structure varies in efficiency depending upon the type and amount of superstructure in contact with the waves. For example, round piling and bracing offer less resistance to wave forces than do I-shaped ones. All network superstructure such as cross bracing should be kept to a minimum and at as low an elevation as possible, so that it will not expecience the pressure exerted at the tops of breaking waves. Models of proposed structures can be tested in wave tanks and in the field to ascertain the efficiency of specific designs. Past experience in beach and shoreline engineering has shown that, although changes in the topography of the bottom very near shore do not seem to be occurring, the natural forces involved may be in a delicate balance such that a static state exists. Interruptions of any of these natural forces by erecting offshore structures are likely to cause undesirable effects. Changes in beach profile result partly from sediment being brought into suspension by the orbital motion of waves and partly from the transport of sediment by longshore currents. With the erection of an offshore structure and consequent change in the combined effects of these two forces, unfavorable deposition upon, or erosion of, the bottom at the site may occur. Therefore, combination wave and current studies are essential for the solution of problems involved in the design of most marine structures. TECHNIQUE FOR OBTAINING WAVE INFORMATION In determining the probable effect of wave action on an offshore drilling structure, it is first necessary to know the usual frequencies of certain wave types for the given location. A technique has been developed which provides a means for obtaining information about wave characteristics in the

Jan 1, 1949

By Paul L. Horrer

Costly damage by severe wave attack to many engineering structures has illustrated the need for a consideration of the nature of wave action in plans for offshore drilling operations. Using wave data it is possible to answer questions pertaining to engineering problems such as platform elevation, structure orientation, and expected wave forces. For locations where wave records are not available a technique can be used to obtain information about wave characteristics from past meteorological data and near shore submarine topography. Forces exerted on structures by waves may be divided into four parts. A completed study is given in which frequencies of various wave heights and maximum frictional drag forces are computed for a typical offshore drilling site. INTRODUCTION Waves of tremendous proportions accompanying hurricane winds crash against breakwaters and other offshore structures causing untold damages. Wave forces exerted on structures at these times are enormous, as shown by past records of incidents where massive portions of breakwaters have been broken off and moved by waves. On other similar occasions, whole structure; have been unloosed and smashed or floated away. These incidents, which seem almost incredible, serve to illustrate the great amount of energy contained in large waves, and to show that this energy results in powerful forces destructive to offshore installation~ which are not designed sufficiently strong to withstand wave attack. In the past the expected frequencies of waves having various characteristic.% have rarely been considered in the design of structure affected by wave action. As a result, many structures have failed to accomplish the purpose for which they were designed or have collapsed under wave attack. Others have been constructed to withstand greater wave energy than is ever encountered, with resulting waste of material and construction time. In this study an analysis is made of the frequencies of waves having different characteristics which affect the plans for offshore drilling installations. After such an analysis the erection of these structures can proceed with less risk involved and with more efficiency and economy. ENGINEERING ASPECTS In the offshore drilling program wave forces play an extremely important part in design and construction of drilling rigs in shallow water. The design of a platform or other structure from which drilling equipment is operated is critical, becauze any damage to the platform may endanger personnel and result in complete loss of equipment. Since a platform built too close to the water would be battered by breakers, and one built unnecessarily high would involve undue expense, it is necessary to know the most desirable elevation at which the platform should be erected. This is only one of many questions about structural planning which can be answered using existing technique for determining wave characteristics. The purpose of efficient design for the portions of many types of offshore structures which are acted upon by wave forces is the same as that of all designs which deal with frictional forces of a fluid on a solid. For these structures the problem is comparable to that encountered by undersea craft moving through water, except that in the case of a fixed structure the force is produced by the water moving past the model. For off shore sructures which are extremely rigid the frictional forces may be nearly negligible compared with the impact or shock forces imparted by breaking waves. In all case; the better design is that which offers the least resistance to the opposing forces. From a consideration of wave forces, each drilling structure varies in efficiency depending upon the type and amount of superstructure in contact with the waves. For example, round piling and bracing offer less resistance to wave forces than do I-shaped ones. All network superstructure such as cross bracing should be kept to a minimum and at as low an elevation as possible, so that it will not expecience the pressure exerted at the tops of breaking waves. Models of proposed structures can be tested in wave tanks and in the field to ascertain the efficiency of specific designs. Past experience in beach and shoreline engineering has shown that, although changes in the topography of the bottom very near shore do not seem to be occurring, the natural forces involved may be in a delicate balance such that a static state exists. Interruptions of any of these natural forces by erecting offshore structures are likely to cause undesirable effects. Changes in beach profile result partly from sediment being brought into suspension by the orbital motion of waves and partly from the transport of sediment by longshore currents. With the erection of an offshore structure and consequent change in the combined effects of these two forces, unfavorable deposition upon, or erosion of, the bottom at the site may occur. Therefore, combination wave and current studies are essential for the solution of problems involved in the design of most marine structures. TECHNIQUE FOR OBTAINING WAVE INFORMATION In determining the probable effect of wave action on an offshore drilling structure, it is first necessary to know the usual frequencies of certain wave types for the given location. A technique has been developed which provides a means for obtaining information about wave characteristics in the

Jan 1, 1949

By Alvinus Brown Wood

THE ancient copper-mines of Lake Superior, having been destroyed or covered by-modern mining-dumps, are not accessible to the present inhabitants of that region, and, since no more are likely to be found, some account of those already discovered, from one who has seen them, may be acceptable to the Institute. Early in May, 1855, 1 took a party of men to open an ancient pit on the Quincy mine-location. Mr. C. C. Douglas was the Agent.," as mine-managers were then called on Lake Superior. The Quincy Co. had previously done work on a fissure-vein, several hundred feet west of the Amygdaloid lode (afterwards called the Pewabic lode), on which was the ancient pit herein described. It was at this pit that the Quincy' main shaft was subsequently stink. The ancient pit showed an apparent depth of about 4 ft., but when cleaned out it was shown to be 14 ft. deep, having been filled up by the sliding-in of material composed largely of broken rock, taken out in sinking the ancient shaft, and left near its mouth. Midway of the shaft, and below water-level, was found a scaffolding, of white-birch poles,- which had been used as a landing, to assist in removing the excavated rock. The shaft was 7 ft. in diameter. The excavation had been done by first building fires in order to disintegrate the rock, as was proved by the abundance of charcoal found; then breaking the softened rock with hammers of diorite, such as is found in the greenstone range on Keweenaw point. These hammers had about. the size of large paving-stones. Only broken ones were found, the whole ones having been doubtless carried away for other work, such as could be traced on the lode for a hundred feet or more to the south. At the place where this shaft was stink, barrel-copper (i.e.,

Mar 1, 1906

By AIME AIME

SCANDINAVIAN countries seem somehow to furnish an amount of talent and leadership far be- yond their population and among them Sweden is possibly at the top. The United States has many eminent citizens born in the latter, country or who are of Swedish descent and the engineers may claim their full share. In fact, the number is so large that a flourishing Swedish-American Engineering Society has been formed, including a number of A. I. M. E. members. Dr. Waldemar Lindgren is more scientist than engineer, though his work in economic geology has contributed directly to the development of many mines, and he is the valued- adviser of a number of our larger companies. Probably he, himself, values most highly the contributions he has been able to make to scientific theories of the occurrence and genesis of ore deposits. His fellow scientists have placed upon these the high mark of approval by electing him to the National Academy of Sciences, and Princeton University in 1916 recognized his position by conferring on him the degree of Doctor of Science.

Jan 1, 1931

By Gerald Sherman

MINE fires are always dangerous and are frequently accompanied by loss of life during the period of confusion which is apt to follow their discovery. In metal mines, fires may result from the accidental ignition of some combustible material, or they may be of spontaneous origin resulting from the rapid decomposition of sulphide. They occur frequently enough to demonstrate the need of some special equipment and a general plan for controlling them, in addition to measures for their prevention. Nearly all the large copper mines have had fires, and the methods of fighting them have been well described in recent papers, notably-by C. L. Berrien,1 R.. E. Tally,2 and others in discussion. The Copper Queen mine has many shafts, which are connected by underground workings. The deeper parts are ventilated by fans, but in the shallower portions natural ventilation through numerous connecting raises or shafts is sufficient. There have been several fires in the past few years, of which all are extinguished but one, and that is under control. These notes cover particularly the preparations that are being made-to check a new fire, partially or temporarily, and to facilitate the escape of workmen in the interval before a definite plan of fighting it can be established. A fire may occur in a shaft or station, or in some working father away. In case of fire in an upcast shaft, the gas would escape to the surface and the immediate result would probably not be dangerous to workmen, as they could escape by other shafts. In a downcast shaft, however, the gas would be distributed very rapidly throughout a large portion of the mine, and men might easily be trapped and asphyxiated. A fire in mine workings, drift, raise, or stope, would be dangerous in a degree, but the draft there is likely to be less strong than in a shaft and probably a smaller area would be invaded by the fire gases.

Jan 1, 1918

By Albert F. J. Bordeaux

(Cleveland Meeting, October, 1912.) THE immediate vicinity of the sea-shore, affording special facility for the exportation of ores, makes it possible to work certain mines in the Vladivostok district, which, in more remote places of Siberia, would remain unproductive. Outside of the city of Vladivostok the population is small and the country is very little prospected. Additional discoveries of valuable deposits like the large body of calamine which has recently been opened in the neighborhood of earlier worked lead-silver ores, in the Tetiuhe valley, are still in the field of possibilities. For many years gold alone was produced, in part from the coastal rivers and in part from a quartz-vein on Askold island near Vladivostok. But the production is diminishing, and prospectors are looking for other rivers in the interior, such as the tributaries of the Ussuri. These rivers are now more accessible than formerly, due to the slow but gradual development, of colonization by the Russian peasants. The few natives of the country, called Orodjones, are of the Chinese race. They resemble the North American Indian and are hardy fur-hunters. They have given some attention to placers and have already shown good specimens of gold-dust from the rivers Iman, Bikin, Noto, etc. Coal-mining was begun in the Vladivostok region more than 20 years ago, but in a somewhat irregular way. The industry is not as yet important and the best coal-seams are badly prospected, or ire even neglected. Copper, lead, and iron exist in several places. The amounts give some encouragement to the anticipation that the discoveries will give rise to important metallurgical works. I here present a review of the various deposits, based upon such safe information as is in hand, when I have not drawn upon my personal observations. Fig. 1 is a snap of Eastern Siberia, showing the mineral deposits.

Oct 1, 1912

By E. T. Dumble

In the Bosquejo Geoldgico de Mexico, published in 1897 by the Secretaria de Fomento as Nos. 4, 5 and 6 of the Boletin del Institute Geologico de Mexico, the Director, Jose C. Aguilera, after a detailed account of the geological observations made by himself and his assistants on their several trips through the various districts of the Republic, gives in Part 2 a synopsis of the geology of Mexico, describing . al1 the formations recognized, the rocks comprised in them, their geographical distribution, disturbances, principal eruptions and economic features, as explanatory of the Geological Map of Mexico. In Part 3 Prof. Ordonez describes many of the interesting eruptive rocks of Mexico." This work brings together in a very satisfactory way about all of the published results of geological investigations in Mexico; and although the determinations of the authors with reference to some of the sedimentary deposits are very different from those of other writers, they seem to be based upon good paleontological grounds in each instance. From the map and the text of this paper it appears that the condition of knowledge in regard to the geology of the State of Sonora, at the time of its publication, was about as follows: The western portion of the State, lying between the coast line of the Gulf of California and the foot-hills of the Sierra Madre mountains, is largely Quaternary, interrupted by areas of Azoic rocks and of later eruptives, with two or three limited exposures of limestones of the Cretaceous; while the eastern or

Jan 1, 1900

By A. E. Outerbridge

I had the honor to present to the American Institute of Mining Engineers at the Pittsburg meeting, February, 1896, a paper having the foregoing title, in which I said : " It has generally been accepted as a fact that cast-iron, under the influence of repeated shocks, becomes brittle, and will finally break under a blow which otherwise it would have withstood. It will probably surprise metallurgists, therefore, to learn that experiment disproves the supposed fact, and establishes exactly its opposite. " The result of about a thousand tests of bars of cast-iron of all grades, from the softest foundry mixtures to the strongest car-wheel metal, enables me to assert with confidence that, within limits, cast-iron is materially strengthened by subjection to repeated shocks or blows." Three tables were appended showing increase of strength

Jan 1, 1905

By Rollin E. Hook, Attwell M. Adair

The yield and fracture behavior of recrystallized chromiztm have been studied in order to gain an understanding of the recrystallization embrittlement-rheotropic recovery phenomenon. The duc tile-brittle tensile transition temperature of recrystallized chromium was found to vary from 225 ° to -80°C as the ratio of specimen diameter/mean planar grain size decreased. The applicability of this observation to other bcc metals is briefly discussed. Brittle fracture in recrystallized chromium was found to be initiated predominately from intercrystalline rupture nuclei. Single crystals exhibit a high degree of ductility at 23 "C. The experimental data indicate that grain boundaries play a significant part in the yield and fracture behavim. Pres training significantly reduces the transition temperature, and high temperature aging does not result in re-embrittle-ment until complete recovery or re crystallization occurs. SEVERAL theories have been used to explain the recrystallization embrittlement-rheotropic recovery phenomenon in chromium. Wain, Henderson, and ohnstone' propose a Cottrell dislocation locking mechanism due to nitrogen, and Weaver and Gross and weaver 3 propose a strain-induced precipitation mechanism involving a chromium nitride precipitate. The researches of many investigators seem to leave little doubt that brittleness in chromium is promoted by interstitial impurities. Smith and seybolt4 have shown that the ductile-brittle transition temperature is lowered as the interstitial content is reduced. weaver3 provides evidence for a 150°C reduction in the tensile transition temperature as the nitrogen content is reduced from 20 to 5 ppm. Maykuth and affee' have suggested that the amount and orientation of grain boundary impurities may be responsible for the brittle nature of recrystallized chromium. This suggestion was based on their findings that wrought iodide chromium possessing a fiberous grain structure is ductile in tension at room temperature while a recrystallized grain structure is completely brittle. Previous investigations have not studied this phenomenon sufficiently to determine its cause. Perhaps this has been largely due to previous experimental findings that brittle fracture observed in chromium has been almost entirely transgranular.' In addition McNeil and imb,' who investigated coarse-grained as-cast chromium, describe the point of initiation of fracture as cleavage, close to the (100) plane, near or at grain bound-daries, or at included particles or voids. However, Hook, Adair, and ipsitt found that fracture in coarse-grained recrystallized chromium is initiated by intergranular rupture and then propagates nearly entirely by cleavage. This result, together with their finding that room temperature ductility in bending is observed for single crystals and coarse-grained polycrystalline specimens for which the number of grains through the specimen diameter is small, suggests that grain boundaries may play an important role in the brittle behavior of chromium. The recrystallization embrittlement problem can be resolved into two questions. These are, whether the controlling mechanism is predominately one of crack initiation or crack propagation, and whether brittle fracture is initiated predominately by slip or twin induced intergranular rupture or by cleavage. The following research was designed to study the role of grain boundaries on the brittle fracture of chromium in an effort to resolve these questions. EXPERIMENTAL PROCEDURES, RESULTS, AND DISCUSSION General Procedure. All tensile specimens (except 0.04 in. diam wires) were prepared from 1/4 in. diam swaged rod fabricated from one ingot. Details of fabrication are given elewhere. The results of impurity analysis for the swaged rod and for the

Jan 1, 1963