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By William P. Blake

This camp is just now startled by the alarming suggestion that unless there shall speedily be an appreciation in the value of silver, and a decrease in the cost of salt, it will be prudent business policy to close the Alice mines and mills until the conditions of production are more favorable. Such an event would be a great blow to the prosperity of Butte. It would throw some hundreds of men out of employment, and it might lead to the adoption of the same policy by other companies, which, like the Alice, have not been able to pay dividends to their shareholders for a long time. The question arises, and becomes emphatic: If, under the present adverse conditions, the mines and mills cannot be made to pay a proper profit, why should they continue to be worked ? The owners mentally ask: Shall we go on exhausting our mines, pouring out a stream of silver for the maintenance of the community, and the support of the rail ways, or shall we husband our reserves, withdraw the miners from our slopes, and wait for more favorable conditions ? This is the impending question, and all concerned dread to meet and answer it. Let us briefly review the situation and forecast, if possible, what the solution of' the problem will be. It must be understood that the discussion does not include, or refer to, the immense copper-producing interests of the camp, which may or may not be upon a very much more satisfactory basis. It will be confined chiefly to the operations of the Alice company, sta tistics of which are at hand, without involving the other silver com panies in the conclusions beyond those inevitable from well-known facts, patent to all. There are at present in Butte and in its vicinity in the principal mills an aggregate of 290 stamps dropping upon silver-ores: Alice,...........80 stamps. Moulton,. .........40 " Lexington,...50 " Silver Bow,.........30 " Blue Bird,..........90 " The Alice mills at present, with their 80 stamps, devour, in round numbers, from 100 to 120 tons a day. The actual amount

Jan 1, 1888

By Edward F. Winter, C. E. Ruoff

A silicon solid-state array image scanner is described. This paper deals with structural and performance properties of the array which basically consists of PIN photo and gating diodes, and low capacitance isolation diodes. Each chip of the array is composed of an 8 by 9 matrix of photo detector cells; each cell contains one each of the three diode types mentioned. This x-y matrix is read a column at a time with an access delay of approximately 100 nsec per column. It is designed to detect the presence or absence of illumination within 10-mil diam image spots located on a 15- by 15-mil grid. Radiant power level of an illuminated spot is low; of interest is the range around I uw with a of 8400g Structural improvements to the original array which will result THE purpose of this paper is to describe the results of a solid state scanner exploratory development activity. The scanner is intended to sense the presence or absence of low-level illumination falling upon a matrix of 10-mil wide squares arranged on a 15- by 15-mil x-y grid pattern. The light of interest has a wavelength of 8400, characteristic of radiation emitted from a GaAs lasing diode. This wavelength matches well the spectral absorption of silicon,' thus the well-developed silicon processing technology can be applied to fabricating large integrated arrays of PIN photocells to sense the radiation. The illumination state of the cells of the array is read, one column at a time, by addressing a drive line of the particular column in question and examining the state of those sense lines which are orthogonal to the drive Lines of in greater sensitivity at various wavelengths, both above and below 8400Å, and in greater speed are presented. These include variations in diffusion depth, resistivity of N and P regions, isolation techniques, and packaging. Trade-offs between access speed, cycle frequency, and sensitivity are discussed. A packaging approach to achieving an array composed of several chips is described. Requirements on this package are: 1) maintenance of 15- by 15-mil pitch of the light sensitive cell position, therefore positional accuracy of mounted 8 by 9 cell photo detector chips; 2) maintenance of inherent high array speed even though signal levels are low through high density close proximity mounting of monolithic sense amplifier circuitry. the array. One bank of N sense amplifiers is required, where N is the number of photodiode cells in each column of the array. CELL AND CHI" STRUCTURE A photograph of a single monolithic cell is shown in Fig. 1. Each cell is composed of three junctions, an isolation junction, a logic or blocking diode junction, and a photodiode junction; all of these junctions are connected electrically by a common N region. An electrical schematic of four cells of the array is shown in Fig. 2 with the associated driver and sense amplifier circuits in block diagram form. Note the common cathode configuration of the three diodes of each cell. Fig. 3, a diagram of the cell vertical struc ture, illustrates how the electrical configuration of

Jan 1, 1970

By Walter E. Lewis

Myriad problems face all of us in the next decade. Vietnam, poverty, and pollution are perhaps the most pres- sing. A lesser one but still vital to us as a Nation is the slow hut apparently relentless extinction of the mining, metallurgical. geological and petroleum engineer. Are we doomed to take our place in the crossword puzzle with the moa. to be defined like it as an "extinct bird"? Or can we reverse the trend perhaps, in the next decade? The plain fact is we are an endangered species, and must resign ourselves to virtual extinction in the 1970's unless the trend is reversed. Probably, many of us have felt the problem will solve itself if left in the in-basket long enough, believing, that the trend will reverse solely on the basis of demand for these disciplines. This approach has not worked up to now, it gives no promise of working in the future, and furthermore, the problem has been in the in-basket much too long. The point is simply this: What can each of us do as an individual, or as part of a company, a State agency, a Federal agency, a university, or an organization such as AIME?

Jan 1, 1970

By M. C. Flemings, F. R. Mollard

Conditions necessary for plane front growth of two-piwse solids from a single-phase melt are discussed. Alloys consideved are those from a simple binary system containing a eutectic, but are not, in general, of eutectic cornposition. It is concluded that: 1) plane front solzdification is favored by low growth rate, steep thermal gradient, and essential absence of convection; and 2) for steady-state solidification, the structure should resemble that of directionally solidified eutectics (lamellar, rodlike). Factors affecting THERE are many materials, including metals, available today with strengths in excess of 10' psi when in whisker or fiber form. The challenge facing those interested in practical application of such materials has been, and remains, the economic production and incorporation of the whiskers or fibers into useful engineering composites. solute redistribution along the growth direction are described quantitatively, by numerical solution of the diffusion equation. Effects of variations in growtlz rate on average composition of the solidifying composite are significant. For alloys not too close to a single-phase region, the initial transient at constant gvowth velocity is the order of D/R where D is diffusion coefficient in the liquid and R is interface velocity. Composites consisting of the reinforcing phase within a metallic matrix have excited particular interest in recent years because of their potential for high strength at elevated temperature and for resistance to brittle fracture. Techniques employed to incorporate the whiskers or fibers in the metallic phase have included 1) liquid metal infiltration, 2) solid or liquid phase sintering, and 3) direct growth of composites from the melt, of rodlike or lamellar morphology, by directional solidification of eutectic alloys. Two recent books"2 have reviewed the status of this growing field. Concerning the last method, growth of eutectics, it has been shown that the reinforcing phase (e.g., rods)

Jan 1, 1968

By W. R. Atkins

The Negaunee mine is at the east end of the Marquette Range, in the city of Negaunee, on the Upper Peninsula of Michigan. Iron ore was first discovered on this property in 1883 by diamond drilling. A shaft was sunk soon afterward. and the mine has been worked continuously ever since. The total shipments from 1887 to Jan. I, 1945, were 20,417,587 long tons. The mine was taken over by the present operators, The Cleveland-Cliffs Iron Co., in 1903. During the past four years, 1941 to 1944 inclusive, the property has produced an average of nearly a million tons a year, and has employed more than 400 men. Geology The ore body at the Negaunee mine lies in a large syncline dipping about 15° to the west, the ore coming to ledge at the east end of the trough. The ore occurs in the Negaunee formation of the middle Huronian age, which consists of ferruginous cherts and slates through which intrusions of diorite have occurred. Although these intrusions of diorite have an important bearing on the formation of ore on the range, they are not important in this ore body. Some faulting has taken place along the diorite intrusions, or dikes as they are called locally, and also other faults are known to exist across the formation. These faults do not complicate either mining or development of the ore body. The footwall consists of jasper underlain with Siamo slate; the hanging wall is jasper and ferruginous chert. Fig. I shows a typical cross section of the ore body. The ore body is quite regular, about 120 ft. thick in the middle of the syncline and thinning out toward both sides of the fold. Its width ranges from 400 to 800 ft., the average being about 600 ft. The footwall is uniform in dip and strike, but irregular lenses of ore often extend 50 to 75 ft. up into the overlying jasper capping. Method of Mining Ore in the Negaunee mine has been mined by top slicing almost exclusively since 1903 This method of mining has been employed because it is especially adapted to the size and shape of the Negaunee ore body, and to the soft, sticky nature of the ore as well as the generally soft, broken jasper capping. Development The ore body has been developed from six different levels with intervals varying between loo and 125 ft. On the average, the dip causes a horizontal offset of 350 ft. per level, and under these circumstances it has been necessary to carry on considerable development in rock to make available the ore lying along the north and east footwalls. This is not as disadvantageous as might be supposed, because of reduced pressure and the accompanying saving in maintenance costs. The development of the

Jan 1, 1949

By C. N. Schuette

The material presented in this paper has been gathered by the writer during a long and varied experience on matters pertaining to the quicksilver industry. During the past 18 years he has visited practically all of the quicksilver mines of the United States and has had occasion to review the literature on quicksilver mining the world over. In a previous publication1 the conclusion was expressed "that the greatest opportunity for increasing the economy in quicksilver production lies in giving more attention to the geology of the deposits ... " The present paper is a contribution toward that end. Due to a lack of correlation of the observed facts, a great deal of confusion exists in the views of various writers concerning the mode of occurrence of quicksilver ores. This paper attempts to show that certain common factors underlie the formation of all quicksilver orebodies. It attempts to present a framework on which to marshall the observed facts and thus make clear the interrelation of various observations which at first sight appear to be contradictory. The material presented is fragmentary in many respects and it is hoped that readers familiar with the deposits mentioned may supply the deficiency. The reader is asked to refer to the publications cited for maps and additional information on the individual orebodies, as this review, in covering so much territory, must necessarily confine itself to a bare outline of the facts concerning each occurrence. The writer hopes that this paper will elicit comment and criticism from the many competent men interested in the quicksilver industry and to all of them he would express his indebtedness for the many courtesies that they have extended to him at various times in the past. Theory op Primary Concentration The mode of occurrence of any given orebody presents an individual problem to the miner engaged in exploiting it. No two orebodies are exactly alike in their geological relationships, therefore an understanding, in detail, of the geology is necessary if the orebody is to be exploited in the most economic manner.

Jan 1, 1931

By A. English, M. J. Greaves

This paper is a discussion of pelletizing systems developed over the last 15 to 20 years for the agglomeration of fine iron ore concentrates. Five different pelletizing systems are now in commercial use in the U.S., and for the purposes of comparison, estimated operating costs and capital costs for the construction of four of them are included. Capacities of existing commercial plants are examined, together with the anticipated capabilities of plants presently being built or projected. In just 21 years, the art of pelletizing iron ore concentrates has reached maturity with mastery of the separation of finely divided concentrates from low-grade iron ores and their agglomeration into pellets containing about 65% iron. This accomplishment has firmly established an improved feed for the blast furnace, with resulting benefits in faster reduction of burdens and greater economy of operation. The present production capacity of pelletizing facilities in the U.S. is about 20 million tons annually, and it is expected to double by 1970. The rapid expansion of pelletizing in the U. S. has been closely observed in European countries, notably in Sweden and Germany, where pioneer agglomerating techniques were developed early in this century. PELLETIZING PLANTS AND PROCESSES Twelve commercial pelletizing plants are presently in operation in the U. S. and Canada. An equal number are in various stages of engineering and construction, and many others are being considered. The pelletizing systems currently employed include shaft furnaces, horizontal grates using three different airflow arrangements, and grate kilns. The capacity of pelletizing operations in North America is shown in Table I. All of these plants are integrated with the mine, the ore-crushing facilities and the concentrating plant and are equipped with storage and loading-out facilities for the product. Normally, a pelletizing plant is composed of a shuttle conveyor above the receiving bins; balling equipment; a heat-hardening system including the necessary auxiliaries such as furnaces, burners and controls, ducts, fans, meters and instrumentation; fines recovery equipment; and product handling equipment. Also included are the necessary auxiliaries and utilities such as boilers or power plant; oil unloading and storage facilities; coal unloading storage, grinding and distribution facilities; and bentonite or other additive storage and distribution equipment. Shaft Furnaces: Vertical shaft furnaces used in this country are limited to the treatment of natural magnetite concentrates containing minor quantities of residual fluxing elements. Fig. 1 shows a perspective view of the shaft furnace with balling, feeding and pellet-handling equipment. An elevation of a shaft furnace is shown in Fig. 2. A commercial shaft furnace unit is about 45 ft in height with a 6 x 14-ft rectangular cross section and has a nominal production rate of approximately 50 gross tons of pellets per hour. The upper portion of the furnace shaft is constructed of fire brick as protection from the high process temperatures involved. The lower portion of the shaft is lined with abrasion-resistant brick to withstand erosion from the fired pellets. Rectangular-shaped, refractory-lined and insulated combustion chambers are situated on each side of the shaft furnace. Oil or gas is burned to produce high temperature gases which are forced into the furnace through ports located near the top of the combustion chambers. The shaft furnaces operate at a pressure of approximately 6 psi. Pellets are fed into the top of the furnace by a pantographic feeder designed to produce the desired pellet stockline. The furnace is kept filled at all times and pellets are fed and discharged from the furnace at the same rate. In early development, 10 to 12 lb of solid fuel was incorporated in the pellets. However, the main source of process heat is now derived from the combustion chamber gases. In some instances no solid fuel is used. The pellet movement in the shaft furnace is counter-current to the flow of gases. Ambient air is introduced through louvers at the lower end of the furnace, at about 6 psi, cooling the fired pellets and supplementing the heat of the high temperature gases from the combustion chamber ports. The zone of maximum temperature, located above the ports of the combus-

Jan 1, 1963

By Daniel J. Martin, James L. Martin

The dendritic pattern of steels shown by deep etching is used extensively as a guide in the inspection and control of the great majority of steels used in ordnance construction and for many applications in industry. The value of macroexamination lies in the fact that it enables a qualified observer to make deductions concerning the general quality of relatively large pieces of metal. Not the least of these general characteristics is the nature and extent of the dendritic segregation in the steel, either in the cast condition or after mechanical or thermal treatments. Previous Work Detailed methods for macroetching were outlined by Yatsevitchl and have been standardized by the American Society for Testing Materials. A comprehensive study of the occurrence, origin, and the chemical and crystalline nature of the dendritic structure was given by Keshiam2 The marked persistence of dendritic segregation in nickel steels is fully recognized and has been discussed by Sauveur and Reed3 and by others. Very little, however, has been written on the effect of the various elements on the macrostructure of steels, and the purpose of this report is to submit evidence concerning the influence of chromium, nickel and molybdenum on the macrostructure of some 4 by 4-in. ingots cast and treated under closely controlled conditions. Methods and Results The ingots to be described were made in a 60-lb. high-frequency induction furnace at the Watertown Arsenal. Heats were made from a single lot of materials; were molten for the same length of time; tapped at approximately the same temperature into a standard mold preheated in each case to 150º ± 10º C.; and stripped and buried in ashes after 10 min. in the mold. Transverse disks were taken from the same location in

Jan 1, 1939

By James L. Martin, Daniel J. Martin

The dendritic pattern of steels shown by deep etching is used extensively as a guide in the inspection and control of the great majority of steels used in ordnance construction and for many applications in industry. The value of macroexamination lies in the fact that it enables a qualified observer to make deductions concerning the general quality of relatively large pieces of metal. Not the least of these general characteristics is the nature and extent of the dendritic segregation in the steel, either in the cast condition or after mechanical or thermal treatments. Previous Work Detailed methods for macroetching were outlined by Yatsevitchl and have been standardized by the American Society for Testing Materials. A comprehensive study of the occurrence, origin, and the chemical and crystalline nature of the dendritic structure was given by Keshiam2 The marked persistence of dendritic segregation in nickel steels is fully recognized and has been discussed by Sauveur and Reed3 and by others. Very little, however, has been written on the effect of the various elements on the macrostructure of steels, and the purpose of this report is to submit evidence concerning the influence of chromium, nickel and molybdenum on the macrostructure of some 4 by 4-in. ingots cast and treated under closely controlled conditions. Methods and Results The ingots to be described were made in a 60-lb. high-frequency induction furnace at the Watertown Arsenal. Heats were made from a single lot of materials; were molten for the same length of time; tapped at approximately the same temperature into a standard mold preheated in each case to 150º ± 10º C.; and stripped and buried in ashes after 10 min. in the mold. Transverse disks were taken from the same location in

Jan 1, 1939

By F. M. Hamilton, R. G. Fleck

As the result of extensive small laboratory experiments, the metallurgical results of sintering iron ore from the Benson mines at Star Lake, N. Y. were clearly defined. But the practical operation had not been proved; so, the sintering strand, which went into operation at the mines in 1952, was designed to minimize the risk involved. It was built by the Dwight-Lloyd Div. of McDowell Co. Inc.

Sep 1, 1956

By C. Feng, I. R. Kramer

A study was conducted to determine the influence of the surface on the yield point of fcc metals and high-purity iron. For the high-purity fcc metals, the yield Point produced by restraining a specimen may be eliminated by removing a sufficient amount of the layer. A yield point similar to that in fcc metals was found when iron specimens were pre-strained after a prior deformation. This yield point is not due to an aging effect but is associated with the surface layer. The yield points in age-hardenable aluminum alloy and those connected with "work softening" are not affected by a surface-removal treatment and are, therefore, caused by bulk-type dislocation reactions. The yield point which appears in previously strained fcc metals has been the subject of numerous studies. Several theories have been advanced to explain this "unloading-reloading" yield point. Cottrell and stokes,' from their study on the effect of temperature on plastic properties of high-purity aluminum, considered that it was the result of an avalanche "breakdown" of Lomer-Cottrell sessile dislocations. Haasen and Kelly2 extended this concept of dislocation-dislocation interaction to account for the yield point when unloading and reloading was carried out at the same temperature. On the other hand, strain aging was found to be responsible for the yield point in A1-Mg alloy by Westwood and Broom,3 and in aluminum alloys containing various amounts of alloying elements by Smallman, Williamson, and Ardley.4 In these cases, the yield point is considered to be associated with the locking of dislocations by impurity atoms. Birn-baum and filer5,6 and Takamura and muira7 reported that, when a high-purity copper specimen was prestrained, then held at a lower stress, and finally reloaded at the prestrain temperature, a larger yield point was observed. Such an increase was attributed to the locking of dislocations by point defects. In addition, Bolling8 suggested that both mechanisms, i.e., dislocation-dislocation interaction and strain aging, are responsible for the yield phenomenon, at least in a brass. Thus, there appears to be experimental evidence for both the strain aging and dislocation-dislocation interaction theories to explain the yield point in the fcc metals and alloys. In a previous article,9 one of the authors observed that, if sufficient amounts of metal were electrolti-cally removed after deformation of a high-purity aluminum single crystal, the yield point did not appear upon reloading. Continued pursuit in this area revealed that the effect of the surface on the yield-point phenomenon is not limited to one metal but affects a variety of metals of different lattice structures. Nor is the effect limited to the yield points produced by simple unloading-reloading at constant temperature; the surface exerts an important role on the yield point even when the temperature is changed at some stage during the test. It is the intent of the present article to give additional information regarding the effect of the surface on the yield-point phenomenon and to show the association between the yield point in both fcc and bcc metals and the existence of a heavy concentration of dislocation in the region near the surface of a deformed specimen.10 EXPERIMENTAL Materials. The single crystals used in this study had a nominal cross section of 0.125 by 0.125 in. and a 3-in. gage length and were prepared by a modified Bridgman technique. The initial purity for the metals was 99.997, 99.999, and 99.999 pct for aluminum, copper, and gold, respectively. Bar stock of these same materials was used in the preparation of the polycrystalline specimens of aluminum and copper. The iron specimens were machined from rods of "ferrovac", reported to have a purity of 99.98 pct. In addition, a precipitation-hardening aluminum alloy, containing 1.5 pct Cu, 2.5 pct Mg, and 5.5 pct Zn, was used. The polycrystalline specimens of iron, copper, and the aluminum alloy had a diameter of 0.17 in. and a gage length of 2 in. while the high-purity aluminum specimen had a nominal rec-

Jan 1, 1965

By Thomas F. Donnelly

The Province of San Cristobal is situated on the south side of the island of Santo Domingo about 25 miles west of Santo Domingo city, the capital of the republic. The copper mineraliza,tion is found about 8 miles north of the town of San Cristobal,. in the section known as Bucaro Hill; in San Francisco Hill; on the Nigua River; and on the Jaina River. The district is reached by automobile from Santo Domingo city over an excellent road for 25 miles to San Cristobal, and then, by horseback 6 or 8 miles up the Nigua River to what is locally known as "Camp

Jan 1, 1916

Jan 1, 1900

By Ellis Clark

These mines were discovered by George W. Lufkin in August, 1878, and mere worked almost continuously until August, 1893, a period of fifteen years. The ore-deposits in this locality lie close to the surface, and it is strange that the Spaniards, passing and repassing for nearly three centuries, did not discover them, particularly as they are marked in several places by large outcrops of black flint and iron, which would lead even a casual observer in a mineral country to suspect the proximity of ore. The mines are situated about six miles from the old Santa Fé trail, and fifteen miles from the Rio Grande. The geology is such that a skilled geologist passing over the ground would probably suspect, from the peculiar arrangement of the formations, the occurrence of ore. The formations in the district, eruptive and sedimentary, are nine in number; and of these eight are to be found within one thousand feet of the Grande workings. Topography. The topography of the Lake Valley district shows its dependence on the surface and underground geology, in a degree more marked

Jan 1, 1895

Jan 1, 1967

By Bruno Nordberg

HOISTING is one of the earliest endeavors of man with machinery, for hoisting was probably used by the early Egyptians. Treadmills were used for general hoisting until early in the nineteenth century and it was a short step only to attach a Watt steam engine to the rope drum of a hoist. One of the earliest steam hoists was built for a coal mine at Frisne, near Valenciennes, France. It was a remarkable piece of engineering created by James Watt in 1811, using a wooden drum on a vertical shaft. This followed the crude hoist by Holtzhausen in 1803, which used a drum of wood on a horizontal shaft.1 In this country there were examples of crude mine hoists, which have been developed into the efficient machines in use today. African and Australian mines show examples of both extremes, and have an array of fine hoisting equipment exemplified in those built by British manufacturers. The influence of both English and American engineering in hoisting is interestingly evident in Canada. The information available to the writer does not reveal this to be true of South Africa, although American-built hoists have been furnished. Mining camps develop their own style of equipment, adapted to local conditions. For instance, the Butte mining district adheres to the straight drum with friction clutches, because of the great number of levels from which hoisting is done or to which men and material are lowered and the necessity for hoisting or lowering unbalanced. The north Michi-gan copper country uses both straight and cylindroconical drums and hoists continually in balance, so that the drums are not clutched to the main driving shaft. The Joplin mining district, Missouri, has its own peculiar small hoists. Other individual mines or localities in which a number of mines have been developed show individualisticc types of hoists, depending upon their particular problems. In each instance, however, the particular problem must be carefully analyzed, as conditions are seldom so near the same that a number of identical hoists can be used to advantage.

Jan 1, 1940

By Charles A. Chase

This paper, descriptive of a single mine, is presented in the belief that it may furnish useful suggestions to mine-managers encountering similar problems; and it includes the details which will enable them to estimate the value of the methods employed—especially where these depart from common practice. Tt should be added, however, that this mine is not typical of the San Juan district, but differs markedly from neighboring mines in physical conditions and metallurgical requirements. The Liberty Bell mine is situated in San Miguel county, Colo., on the west front of the San Juan mountains, 2 miles north of Telluride. The vein was discovered in 1876 by Wm. L. Cornett, who, with subsequeilt locators, took up claims along the apex. A few hundred feet of development-work was accomplished, and a few? tons of ore were smelted or milled; but profitable working proved impossible under existing

Jan 1, 1912

By Jed H. Mosgrove

One of the most interesting of all the subjects required of persons studying the different facets of coal mining is coal mine gases. Some mine gases have been a real problem since the very beginning of underground mining, and in the early days there was insufficient knowledge to cope with them. The history of mining shows that until about the last 50 years, much work was done primarily by the hand methods which are primitive by today's standards. Miners had to contend with gases without the aid of enclosed lighting, permissible mine machinery, sophisticated testing devices, and high-pressure ventilating fans. In early days the miners were not educated about the different mine gases nor did they have the technical equipment to determine the actual composition of the deadly atmospheres they encountered. They simply applied a descriptive term to each gas or mixture of gases depending on its, effect on a person or the surrounding atmosphere. The gases or mixtures of gases were then referred to as "damps," a term which was probably derived from the German word "damps," meaning vapors or gases. The more common damps encountered were : Blackdamp A condition of the atmosphere in which a miner's light would be extinguished and in which breathing would be difficult, sometimes even resulting in suffocation. An atmosphere deficient in oxygen which could contain a combination of any of the mine gases. Firedamp A flammable mixture of methane and air which would either burn or explode when ignited. White Damp A mixture of gases containing carbon monoxide, most often found in mines during fires or after explosions.

Jan 1, 1981

By A. F. Lucas

Belle Isle, located in the low sea marshes near Atchafalaya Bay, is the southeasternmost of the famous Five Salt Islands of Louisiana. Rising about 80 ft. (24 m.) above the level of the surrounding marsh and being some 800 acres (323 ha.) in extent, it constitutes a striking landmark on the low Gulf coast, and since the eighteenth century, when it played an important part in the operation of the buccaneers, it has been intermittently frequented by man. In 1897, the writer discovered the great mass of salt that underlies the island and shortly afterward published a brief account of the geology of Belle Isle and the neighboring salt islands.' In that paper he described principally the salt, but pointed out also the occurrence of petroleum and of sulphur in the strata above the salt. Since that time the island has been extensively explored by the drill, and the developments up to 1908 have been described by Veatch2 and Harris13 and Knapp.4 The writer's early conclusions as to the probable presence of sulphur in considerable quantity have been confirmed by the later drilling, some of the wells having found quantities of gas containing hydrogen sulphide and a number of sulphur-bearing strata as well. Under the stimulus of the present keen demand for sulphur for war purposes, a syndicate of New York capitalists was recently formed to explore the sulphur resources of the island in more detail. Under the writer's direction, six wells were drilled for this syndicate during the winter of 1916-17: The present paper presents briefly the results of this work and sums up the present knowledge of the geology of this highly interesting locality.

Jan 1, 1918

By F. R. Hensel

Up to the present time few attempts have been made to produce hard nonmagnetic materials by heat treatment of austenitic steels. The usual result has been to cause them to pass into the martensitic stage, thus destroying to a great extent the typical austenitic properties, since this involves a transition of a portion of the iron from a face-centered to a body-centered type of atomic arrangement. High-strength nonmagnetic materials such as might be provided by properly hardening austenite are required in the electrical industry for different machine parts. In Europe nonmagnetic retainer rings for restraining the end-turns of the rotor windings in turbo-alternators have been developed as a special application of high-strength austenite. In testing1 a 28,000-kva. three-phase Siemens turbo generator running at 3000 r.p.m. at full load current, the losses in the short-circuit test were 450 kw. for the magnetic ring and 286 kw. for the nonmagnetic, and the difference should be attributable to the magnetic ring. The differences in temperatures during the same test are given in Table 1 and these show the advantage of a nonmagnetic over a magnetic retainer ring.

Jan 1, 1931