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By J. H. Frye, J. W. Caum, R. M. Treco

IT has been suggested that: "Insofar as the hardening due to a solute depends upon the increase of lattice parameter produced by it, it is reasonable to suppose that this hardening might be related to the resistance which the pure solvent would offer to increase in its parameter."' It was further suggested that this hypothesis might be examined by comparing the hardnesses of analogous silver and copper alloys, since the stress necessary to produce a given lattice expansion is quite different in the two metals. Suitable data2,3,4 are now available on these alloys, and we shall proceed to an examination of the hypothesis quoted above. Hardness, Lattice Parameter and Ionic Overlap Increase in ultimate Meyer hardness has been plotted against increase in lattice parameter in Figs. I and 2. It is believed that most of the values are accurate within the limits indicated by the rectangles. These data are also presented in Table I. Ultimate Meyer hardness, P u, is defined by the equation: where L = load, D = diametei of an impression having the same diameter as the testing ball, which in this case is 4 mm. Increase in lattice parameter is defined as the difference between the lattice parameter of the solid solution and that of the pure solvent. The curves in Figs. I and 2 are based on equal solute concentration and an equal degree of plastic deformation pro duced by the testing ball. Hardnesses are corrected to a constant grain size for copper and silver alloys, respectively, and these two grain sizes are approximately equal. Furthermore, all solutes are from the same period of the B subgroup of the periodic table as their solvent. The question arises as to whether Or not lattice parameter is the only factor controlling the hardness of these alloys. There

Jan 1, 1943

By J. H. Frye, R. M. Treco, J. W. Caum

IT has been suggested that: "Insofar as the hardening due to a solute depends upon the increase of lattice parameter produced by it, it is reasonable to suppose that this hardening might be related to the resistance which the pure solvent would offer to increase in its parameter."' It was further suggested that this hypothesis might be examined by comparing the hardnesses of analogous silver and copper alloys, since the stress necessary to produce a given lattice expansion is quite different in the two metals. Suitable data2,3,4 are now available on these alloys, and we shall proceed to an examination of the hypothesis quoted above. Hardness, Lattice Parameter and Ionic Overlap Increase in ultimate Meyer hardness has been plotted against increase in lattice parameter in Figs. I and 2. It is believed that most of the values are accurate within the limits indicated by the rectangles. These data are also presented in Table I. Ultimate Meyer hardness, P u, is defined by the equation: where L = load, D = diametei of an impression having the same diameter as the testing ball, which in this case is 4 mm. Increase in lattice parameter is defined as the difference between the lattice parameter of the solid solution and that of the pure solvent. The curves in Figs. I and 2 are based on equal solute concentration and an equal degree of plastic deformation pro duced by the testing ball. Hardnesses are corrected to a constant grain size for copper and silver alloys, respectively, and these two grain sizes are approximately equal. Furthermore, all solutes are from the same period of the B subgroup of the periodic table as their solvent. The question arises as to whether Or not lattice parameter is the only factor controlling the hardness of these alloys. There

Jan 1, 1943

By FRANK FIRRISTONE

Ix the summer of 1842 my father, William Firmstone, was engaged by Charles Jackson, Jr., of Boston, to examine the conditions in the Lehigh valley as a site for blast-furnaces using anthracite for fuel. In consequence of his report, he was further engaged by Mr. Jackson to build a furnace for him and his partners on the Lehigh canal, 2 miles above the mouth of the river at Easton. Work was begun in the fall of 1842, and the first furnace blown-in in 1844. The history of the works, therefore, from 1844 to 1887, when my own connection with them ceased, covers only four years less than the whole period of the rise, culmination, and commencement of the decline in the smelting of iron with anthracite in America, the beginning of which, in a commercial sense, may be put in 1839.' Although this paper, as the title indicates, is concerned almost exclusively with the furnaces at Glendon, still what was done there was more or less influenced by current opinion in the dis¬trict, and even reflects, to some extent, the changes in opinion and practice with mineral fuel the world over. No. 1 Furnace was built of red brick, on four piers, had three tuyeres and fore-hearth and tymp, as was universal with furnaces using mineral fuel until the introduction of Liirmann's cinder-tuyere. The dimensions and profile are shown in Figs. 1 and 2. The first hearth (Fig. 1) was of sandstone; all after were of fire-brick (Fig. 2). The profile was no doubt derived directly from Gibbons's furnace,2 for it appears from W. Firmstone's note-books that in October, 1840, he visited ." Gibbons' new furnaces building at Corbyn Hall," and I have an old drawing,\

Sep 1, 1909

By Charles H. Foreman

IN JUNE 1921, the Sullivan &lining Co., owned jointly by the Bunker Hill and Sullivan Mining & Concentrating Co. and the Hecla Mining Co, started work on the development of the Star Mine. The development work contemplated called for a crosscut from the Hecla workings on the 2000 level to the Star ledge. The length of crosscut necessary to encounter the Star ledge was approximately 8900 ft. from the Hecla shaft. By using workings formerly made by the Hecla Mining Co., only about 8100 ft. of actual crosscutting was necessary. This crosscut has a direction of S 20° W and would have a tendency to crosscut any ledges in the intervening ground.

Jan 1, 1924

By John S. Alexander

DURING the past few years the block coal of Indiana has been talked about and written upon to such an extent, that almost every one at all interested in such subjects, has been made acquainted with the area and geographical position of the field, the quality and peculiar properties of the coal, the thickness of the veins, the manner of mining, etc. The writer, therefore, taking for granted that, to those present all this is familiar ground, desires more especially to call attention to the position this coal takes in the market, and at those points of consumption where it is brought in direct competition with rival fuels. Chicago, thus far, has been the chief consumer of Indiana block coal, the distance from the mines at Brazil, via Terre Haute and the

By K. Tangri, B. Swaroop

Simultaneous measurements of lattice (elastic) strain by X-ray line shift method and total strain with an electrical strain gage have been carried out on polycrystalli,ne nickel with the help of a specially designed tensometer attachment for the X-ray dif-fractometer. During the initial stages of deformation, the rate of increase in lattice strain closely follows the total strain until the plastic strain sets in. From then onwards, the two strains deviate from each other and with further increase in afiplied stress the rate of increase of lattice strain eventually decreases. Depending upon the mode of unloading, both compressive and tensile strains have been observed in nickel deformed up to 0.29 pct strain. These results have been explained on the basis of the effects of clustering of dislocations and also the production and behavior of point defects during loading and unloading, respectively. POLYCRYSTALS deformed plastically in a uniaxial tension test show residual lattice strains (hereafter referred to as RLS), which broaden the X-ray line profiles and shift their peak positions.''4 It is known that uniform straining of a crystal lattice (macrostrain) produced movement of ddfraction line peaks, whereas nonuniform straining (microstrain) causes line broadening.= Though the nature and origin of RLS in deformed metals is not yet clearly understood, these are believed to be due to the presence of some form of a locked-up stress system. Several possible detailed interpretations6'" of the stress system have been proposed by various workers and common to all these interpretations is the assumption that different parts of the aggregate have different tensile yield stresses; e.g., that a part A yields under a lower applied stress than a part B. Therefore, during the deformation process, the elastic strain in A will be less than that in B, and, after completion of deformation, B will tend to contract further than A but will be prevented from doing so by the restraining influence of A. Thus, when equilibrium is reached, A will be in compression while B is in tension. Although there is general agreement on the correctness of this argument, controversy still exists as to the exact nature of the parts A and B in a deformed metal. In an alternative approach to the creation of parts A and B, many other investigators have assumed that the RLS observed in unloaded specimens are in some way connected with the lack of proportionality between lattice strain and applied stress in the region above the yield stress." cullity13 has prepared a schematic summary of the results of previous workers, mainly Smith and Wood,2'11 which suggests that, above the elastic limit, the lattice strain may increase less rapidly with respect to strain, or may even decrease with increase in applied stress. If the applied stress is then decreased, the lattice strain would decrease along a line parallel to the loading line in the elastic region and thus produce a compressive residual lattice strain after unloading. At equilibrium, to balance these compressive stresses? there would have to be regions under tensile stress which may well be the grain boundaries or the substructure walls formed during deformation. The present investigation was undertaken to gain a better understanding of the nature and origin of RLS and also to experimentally verify the salient features of this hypothesis. EXPERIMENTAL Stress and strain determinations were made with a specially constructed tensometer attachment for the X-ray diffractometer, Fig. 1: which permits the following measurements simultaneously on a sheet specimen under uniaxial tension at various stress levels during loading and unloading: a) lattice strains, E=. in a direction perpendicular to the direction of pulling (x direction) from shifts in X-ray line peak positions; b) the total strain, ex, in the direction of pulling. with the help of an electrical strain gage affixed to the back of the specimen directly below the area irradiated by X-rays: and c) the applied stress, with the help of a load cell which consisted of a calibrated stainless-steel sample of dimensions identical to those of the specimen under investigation, and to which it was coupled. Because of its high stacking fault energy.I4 nickel

Jan 1, 1970

By Stuart H. Ingram

The term lightweight aggregate implies material which may be substituted for the usual rock, sand and gravel commonly used as the major part of concrete, but distinguished by being much lighter in weight. Background The art of making and using concrete is old and well developed. Research and experience have pretty well determined the qualities necessary in its constituents, and time has tested theories and applications. Elaborate specifications and tests have been devised and generally adopted governing all phases of concrete work, from selection of material, through engineering design and down to mixing and placing. Standard practices have become routine to executives and laborers, and operations have been simplified and costs lowered. Though many lightweight aggregates meet the basic specifications necessary for usefulness, their physical qualities are so different that they fiequently will not pass standard tests, and some of them cannot be mixed and placed with the usual formulas for water and slump. As a rule their use produces a concrete with a lower modulus of elasticity which requires design change, and being produced in much smaller quantities than ordinary aggregate, production costs are higher. This latter works in a vicious circle to restrict their use and maintain prices that are not competitive, except as against each other. Increased Demand In spite of such handicaps consumption has grown steadily for the past two decades and is apparently growing even faster today. It is evident that lightweight concrete must have better qualities, and be sufficiently better to Overcome the higher cost and the other difficulties and disadvantages pertinent to the use of a new and different material in an old industry. Hence the study of its main ingredient should be of interest to all engineers. Our group has a double interest in the subject since most of the materials which have been used as sources of lightweight aggregate are either mined, Or are by-products of mining operations. We are directly interested in their production as well as their use, and since available supplies of materials suitable are limited, the increasing use, and rising demand, make the discovery of new Or or the development of processes to adapt other natural materials to this use, a promising field; and one in which our profession should take an active part. Recent Development Descriptions of ancient work contain references to the use of spalls of tuffs Or pumice in concrete masonry, but it is only since the nineteen twenties that serious attempts have been made to produce and market lightweight aggregates. A period of rapid advance in theory and practice in cements, mortars and con-

Jan 1, 1948

By Stuart H. Ingram

The term lightweight aggregate implies material which may be substituted for the usual rock, sand and gravel commonly used as the major part of concrete, but distinguished by being much lighter in weight. Background The art of making and using concrete is old and well developed. Research and experience have pretty well determined the qualities necessary in its constituents, and time has tested theories and applications. Elaborate specifications and tests have been devised and generally adopted governing all phases of concrete work, from selection of material, through engineering design and down to mixing and placing. Standard practices have become routine to executives and laborers, and operations have been simplified and costs lowered. Though many lightweight aggregates meet the basic specifications necessary for usefulness, their physical qualities are so different that they fiequently will not pass standard tests, and some of them cannot be mixed and placed with the usual formulas for water and slump. As a rule their use produces a concrete with a lower modulus of elasticity which requires design change, and being produced in much smaller quantities than ordinary aggregate, production costs are higher. This latter works in a vicious circle to restrict their use and maintain prices that are not competitive, except as against each other. Increased Demand In spite of such handicaps consumption has grown steadily for the past two decades and is apparently growing even faster today. It is evident that lightweight concrete must have better qualities, and be sufficiently better to Overcome the higher cost and the other difficulties and disadvantages pertinent to the use of a new and different material in an old industry. Hence the study of its main ingredient should be of interest to all engineers. Our group has a double interest in the subject since most of the materials which have been used as sources of lightweight aggregate are either mined, Or are by-products of mining operations. We are directly interested in their production as well as their use, and since available supplies of materials suitable are limited, the increasing use, and rising demand, make the discovery of new Or or the development of processes to adapt other natural materials to this use, a promising field; and one in which our profession should take an active part. Recent Development Descriptions of ancient work contain references to the use of spalls of tuffs Or pumice in concrete masonry, but it is only since the nineteen twenties that serious attempts have been made to produce and market lightweight aggregates. A period of rapid advance in theory and practice in cements, mortars and con-

Jan 1, 1948

By David B. Reger

Widespread wildcatting for new supplies of natural gas and the beginning of importation from the southwest characterized the petroleum industry of West Virginia during 1944. Within the state, drilling for oil did not increase but. more gas wells were completed than in any previous year since 1937. Out of 40 wildcats drilled there were 25 gas discoveries and 15 dry holes. No commercial oil was found in the 40 wells. The proved limits of several oil pools were slightly extended by marginal drilling, resulting in 1300 acres of new oil territory, although no distinctly new pools were found. At least four new gas pools were assuredly discovered and various successful wildcats indicate future pools or wide extensions. The new proved gas territory, in definite new pools and definite extensions, is about 34,000 acres. A considerable net decline of proved oil has occarred and probably a slight decline of proved gas reserves. The account of operations, as gathered from trade journals and other reporting services, shows that 918 new wells were drilled, resulting in 71 oil wells with 613 bbl. of daily new production; 577 gas wells with 305,372,000 cu. ft. of daily open flow, and 142 dry holes. Also, 107 old wells were drilled to deeper sands, with 22 bbl. and 12,327,000 cu. ft. of added production. On the new wells the oil average was 8.6 bbl. per well per day, and the gas average was 529,241 CU. ft. per well per day. On new wells the ratio of dry holes to completions was 15.47 per cent. On deeper drilling the ratio of failures was 19.63 per cent. Production of oil for the year was estimated by the Oil Weekly as 3,069,000 bbl., as compared with 3,349,000 bbl. in 1943. Production of natural gas for the year is estimated by the author as 200,000, 000,000 cu. ft., as compared with the U. S. Bureau of Mines final figures of 223,789,000,000 cu. ft.t in 1943.

Jan 1, 1945

By G. S. Rice, Clark H. H.

When mines in the interior coal fields of the United States began the practice of blasting the coal without undercutting, or what is known as…

Jan 1, 1915

By H. E. Williams

In view of the frequent occurrence of petroleum in other parts of the world, it seems odd that so large an area as is contained within the borders of Brazil should be without this product. This apparent deficiency may be due, however, to our ignorance of the regions in which it may exist. In some places, indications point to the probable existence of petroleum in ages gone by; and while the presence of petroleum pools may be problematic, in several regions conditions not unfavorable to their occurrence exist. Yet, Brazil has enormous oil resources in the rich oil-shales in different parts of the country. Many of these shales are very rich and only suitable processes for the extraction of the oil are lacking. At the present time, only a few small experimental plants are producing oil by distillation from these shales. These plants have been the subject of recent investigations by the Geological and Mineralogical Survey, a preliminary report of which is in the hands of the printer. The only regions where studies have not been made are the upper Amazon, the Acre, the Rio Negro, and the Peruvian frontier, which really seems to be the most promising field for explorations of any in the country. In the vast plateau region of the interior north of the 20th parallel of latitude, granites, gneiss, mica schists, and very old metamorphosed sedimentaries predominate. Later, sedimentaries occupy a minor position and, where found in the interior, represent a thin veneering resting on the older rocks. At several places near the coast they have a greater development and contain considerable beds of oil-shale and may, .in some cases, offer conditions favorable for the occurrence of oil. Such deposits are found in the Permian rocks of central and southern Maran-hao; in the Tertiary and Cretaceous beds along the coast of Alagsas Sergipe, Bahia, and perhaps farther south in Espirito Santo; and in the Parahyba embayment north of Cape Frio and in the interior Tertiary basin of eastern Sao Paulo.

Jan 1, 1921

By S. Shapiro, G. Krauss

RECENT investigations1 3 of the products of marten-sitic transformation in Fe-Ni and Fe-Ni-C alloys have made use of light microscopy to describe mar-tensitic fine structure. The application of conventional metallographic techniques to this problem was possible because of the similarity of distributions of parallel striations developed by etching polished surfaces to distributions of transformation twins which are positively identified in thin films by transmission electron microscopy. The surface striations frequently are not well-defined, and could also be due to, for example, rows of etch pits which are not resolved by the light microscope. This note describes the etching effects revealed by examination of surface replicas of mar-tensite in the electron microscope. The application of a replica technique both extends the observations of fine structure made with the light microscope and allows the results of conventional metallography to be used with more confidence. Samples of an Fe-33 wt pct Ni alloy were used for this study because of the detailed knowledge of the fine structure of martensite which has been developed'-4 for alloys of about this composition. Samples transformed to martensite at -120°C, and transformed samples heated to 340°C to effect a small amount of reversal of martensite to austenite, were examined. Surfaces were first prepared for replication by elec-tropolishing in a chromium oxide-acetic acid electrolyte at a current density of 0.1 amp per sq cm and a temperature of 15°C or a perchloric acid-acetic acid electrolyte at a current density of approximately 2 amps per sq cm and a temperature of 15°C. The polished surfaces were then etched for 4 to 7 sec by immersion in a solution of equal parts HC1, HNO,, and H20. Application of the etchant for this period of time produced discrete attack of certain features without loss of resolution due to overlapping of areas most susceptible to etching. The etched surfaces were replicated by 1) preshadowing with Pt-Pd alloy at an angle of 20 to 30 deg, 2) depositing a thin carbon film, and 3) stripping the film and shadowing material by immersion in a 5 pct nital solution. Two types of etching effects were observed by examination of the surface replicas in the electron microscope: l) continuous striations centered at the bottom of long grooves or the tops of pyramidal elevations on the sample surface, and 2) high densities of fine etch pits. Examples of both types of features are shown in Figs. 1 to 4. The striations are in each case continuous and have the same characteristic configurations as do transformation twins in martensite. Fig. 1 shows that the density of grooves decreases toward the edge of a martensite plate and Fig. 2 shows a region where the striations are of varying length. Similar examples of transformation twin arrangements determined by transmission electron microscopy of thinned foils of martensite have been shown in the literature,'~ and, based on these similarities, the striations and their associated grooves or mounds are considered to be evidence for the presence of transformation twins. The transf~rmation twins in martensite are on the order of l00 A thick, much too fine for resolution by the light microscope. It appears that orientation-dependent etching of the matrix martensite about the twins results in grooves or surface elevations which

Jan 1, 1967

By J. G. Savins

Certain types of macromolecules added to water and salt solutions flowing in turbulent motion can reduce the pressure gradient. Alternatively, the volumetric capacity of a pipe for these fluids is increased by the presence of these materials. Examples presented show that the drag reduction can become significant. Thus, the presence of 0.28 per cent of a gum derivative in a solution of sodium chloride flowing at 200 gal/min in a 1.89-in. pipe yields a pressure drop which is 0.44 of the single-phase drop measured under the same conditions of turbulent flow; the addition of 0.1 per cent of a vinyl derivative to a I-in. water line yields a throughput capacity which is 1.78 of the single-phase capacity at the same pressure drop. It is further shown that these phenomena are distinctly different from previous observations with other classes of non-Newtonian systems. There a simple lowering of friction factors below the levels predicted from the resistance laws for Newtonian fluids is associated with a suppression of turbulent motion. A rational physical explanation for drag reduction is advanced. Briefly, the proposed mechanism is a storage by the molecular elastic elements of the macromolecules in solution of the kinetic energy of the turbulent motion. INTRODUCTION This study was inspired by a recent review of some paradoxical drag reduction phenomena in turbulent pipe f1ow.I Under very moderate conditions of turbulent flow, the pressure gradient necessary to pump solutions containing certain specific kinds of polymers, fibers and metallic soaps may become appreciably lower than that required* to pump the solvent, i.e., water or a low-viscosity hydrocarbon, under identical flow rates in the same conduit. As shown by our review, this phenomenon of drag reduction in turbulent duct flow was first noted during the second world war, apparently arising in connection with the development of flame warfare weapons. Since that time several papers illustrating this phenomenon have appeared: Toms, Oldroyd,3 Agoston et al., Bundrant and Matthews, Robertson and Mason,6 Ousterhout and Hall,7 Daily and Bugliarello~ Lummus, Anderson, and Fox. 9 That there are practical applications for techniques which increase discharge or decrease the pressure necessary to transport a liquid through a pipeline is illustrated in the patents which have issued which take advantage of this peculiar phenomenon, e.g., Mysels,l0 Dever, Harbour, and Seifert.11 One also finds fragmentary evidence of this effect in the data pertaining to a few of the polymeric solutions studied by Shaver12 and Dodge.13 However, these investigators were concerned with the development of friction factor vs Reynolds number correlations for a variety of non-Newtonian solutions and suspensions, rather than in a study of drag reduction-. A similar kind of drag reduction effect has been observed in gases. Sproull, for example, reports that adding dust to air flowing in turbulent motion through a pipe results in a lowering of the pressure gradient at identical flow rates. There are also military applications for reducing the drag on hydrodynamic vehicles. For example, the possibility of injecting a rheologically complex fluid into the boundary layers of bodies to reduce the skin friction has been investigated by Fabulal5 and Granville.16 Along somewhat different lines are the drag reduction studies of Kramer.17118 He has shown that skin friction can be reduced by covering the surface of a vehicle with a flexible skin. The effect is apparently due to the boundary layer being stabilized by the presence of the skin. Drag reduction by means of coexisting gas and liquid boundary layers, e.g., film boiling and continuous gas injection, has been proposed by Bradfield, Barkdoll, and Byrne,19 Cess and Sparrow,20'21 Sparrow, Jonsson, and Eckert.22 Here the skin friction occurs between a vapor and a surface rather than between a liquid and a surface. There are several references in the literature to friction-factor correlations for non-Newtonian solutions and suspensions: Shaver and Merri11,23 Dodge and Metzner, Clapp,25 and Thomas.26

Jan 1, 1965

By J. B. Fisken

(Butte Meeting, August, 1913.) BEFORE touching upon the immediate subject of this paper a few facts of a historical nature as to the general application of electricity to mining might be of interest. As to what was actually the first application of electricity to mining, opinions will no doubt always differ. My experience does not go back far enough, nor are the records to which I have had access of any value as covering this point. Sydney F. Walker, a man whose pioneer experience in the application of electricity to mining purposes dates back as far as 1876, ,gave an interesting resume of the subject in an address before the South Wales branch of the Association of Mining Electrical Engineers at its 1.913 session, and, unless his statements are shown to be wrong, they should be accepted as facts. According to Mr. Walker, the ignition of charges of blasting powder was the first operation in mining to be accomplished with the aid of electricity. Very frequently this energy was furnished by a static machine and occasionally by a magneto generator. Later, this was followed by the application of electricity to bell signals, and we are told that this application was looked upon skeptically and regarded as an expensive experiment by the mining managers of those early days. At the Paris Exposition of 1878, there was exhibited an electric lamp, which suggested future possibilities to the mining engineers of those days. The first successful application of electric lighting to underground excavations that I have been able to find any record of is that of M. Blavier. In the year 1879' he installed two Serrin lamps and successfully illuminated one of the large underground chambers in the Angers slate quarries. Another early application of electricity to the lighting of mines is that in the large chambers in the salt mines of Maros-Ujvár, in Hungary; these have been regularly and successfully lighted elec-

Jan 6, 1913

By David Cole

AT the time flotation appeared upon the metallurgical horizon in Arizona, the writer, under the direction of Dr. Ricketts, was engaged in remodeling and enlarging the No. 6 Concentration Plant of the Arizona Copper Co. at Morenci, and the work had been in progress nearly a year before the Inspiration experiments with flotation had disclosed the revolution in concentration that was at that timè impending. The simplified flowsheet worked out for the remodeling of the Morenci plant had been based upon the removal of the freed metal in a minimum number of stages by treatment upon tables equipped with Butchart riffles, the latter being adapted to accomplish both classification of feed and removal of the metal at one operation, substantially as described in my previous paper.1 The scheme of treatment for the slime was based upon the well-known fact that after copper sulphides, such as chalcocite and chalcopyrite, etc., are reduced to a certain extremely fine state of comminution they are definitely beyond the reach of separation upon any of the concentrating devices then known. By using drag-belt classifiers (which served as conveyors as well as separators), the overflow would be of the usual "slimes" class. Experiment had shown that when these drag-belt overflows were, properly diluted (that is, to about 5 to 7 per cent. solids in the feed under treatment) . the very fine sand, and especially the very fine but still granular sulphide particle's, would, if given a short distance to fall, quickly settle out in prime condition to yield an excellent recovery on vanners; a further valuable feature would be that the very fine non-separable final overflow tonnage might be discharged direct to tailing, thus conserving space requirements so as to permit within the old building, without embarrass-ment, the increase of capacity required.

Jan 9, 1916

By H. Rush Spedden, Arvid Thunaes

Pilot plant test work in 1942 and 1943 showed that by a combination of deslim-ing, fine-size classification, and Sullivan deck concentration it is possible to recover heavy minerals such as cassiterite at least as fine as 10 microns in size. This appreciable improvement in gravity concentration practice has been substantiated by several full-sized plants. IN the past, mills treating ores of tin and tungsten by gravity concentration have recovered very little mineral finer than 325 mesh, although some form of slime concentration has been generally attempted by the use of buddies or round tables. This paper describes a series of pilot plant tests made in 1942 and 1943 in which the use of the Sullivan deck was investigated for the recovery of an appreciable amount of the fine values formerly lost. The investigation was initiated by the U. S. Government in an effort to increase the wartime production of tin. Bolivian milling practice at that time included jigging of the coarse sizes, tabling of the intermediate sizes on conventional shaking tables, and the use of buddies or round tables on the finest sizes. Flotation of the pyrite was employed at different stages of the treatment, depending upon the quantity present and the preference of the operator. Usually good recoveries and the bulk of the production were made in the jigging and tabling operations provided that these sections were not overloaded. Buddies and round tables were used for a small additional recovery if it could be shown that they could pay for their high cost of operation. Extensive test work established that by a combination of desliming, classification, and Sullivan deck treatment, cassiterite as fine as 10 microns (1500 mesh) could be recovered when proper conditions were maintained. This test work has been verified by several full-scale installations. The method is generally applicable to the preconcentra-tion of large tonnages of low-grade ores or tailings for the recovery of a small amount of a valuable heavy mineral. The Sullivan deck (or now the Denver Buckman tilting concentrator), which is the essential part of the method, was devised originally for the recovery of tin from tailings of the Sullivan concentrator, Kimberly, B. C. Since the material treated contained only 0.05 pct Sn, it was impractical to attempt to recover cassiterite finer than 500 mesh.*

Jan 1, 1951

By H. Rush Spedden, Arvid Thunaes

Pilot plant test work in 1942 and 1943 showed that by a combination of deslim-ing, fine-size classification, and Sullivan deck concentration it is possible to recover heavy minerals such as cassiterite at least as fine as 10 microns in size. This appreciable improvement in gravity concentration practice has been substantiated by several full-sized plants. IN the past, mills treating ores of tin and tungsten by gravity concentration have recovered very little mineral finer than 325 mesh, although some form of slime concentration has been generally attempted by the use of buddies or round tables. This paper describes a series of pilot plant tests made in 1942 and 1943 in which the use of the Sullivan deck was investigated for the recovery of an appreciable amount of the fine values formerly lost. The investigation was initiated by the U. S. Government in an effort to increase the wartime production of tin. Bolivian milling practice at that time included jigging of the coarse sizes, tabling of the intermediate sizes on conventional shaking tables, and the use of buddies or round tables on the finest sizes. Flotation of the pyrite was employed at different stages of the treatment, depending upon the quantity present and the preference of the operator. Usually good recoveries and the bulk of the production were made in the jigging and tabling operations provided that these sections were not overloaded. Buddies and round tables were used for a small additional recovery if it could be shown that they could pay for their high cost of operation. Extensive test work established that by a combination of desliming, classification, and Sullivan deck treatment, cassiterite as fine as 10 microns (1500 mesh) could be recovered when proper conditions were maintained. This test work has been verified by several full-scale installations. The method is generally applicable to the preconcentra-tion of large tonnages of low-grade ores or tailings for the recovery of a small amount of a valuable heavy mineral. The Sullivan deck (or now the Denver Buckman tilting concentrator), which is the essential part of the method, was devised originally for the recovery of tin from tailings of the Sullivan concentrator, Kimberly, B. C. Since the material treated contained only 0.05 pct Sn, it was impractical to attempt to recover cassiterite finer than 500 mesh.*

Jan 1, 1951

By Archiblad MacMartin

The Kunigin-Marien-Hiitte is the only works in Germany where the Bessemer process is carried on by the direct method. The Besserner plant there, is arranged after the true English type, and the only resemblance to the Swedish mode of 'procedure is the dispensing with the use of spiegeleisen at the end of the "blow." In a new department of the establishment, started within three years, each of the converters is turned by means of a very neat and compact reversible engine, the steel shaft of which is an endless screw, which turns against the oblique cogs of a large wheel attached to the shaft of the vessel. An advantage which this arrangement possesses over the ordinary English hydraulic arrangement, is the fact that the endless screw suffices to turn the vessel, in either direction, any number of complete revolutions; while even the latest American improvements, so clearly explained to us by Mr. Holley at the opening session of this meeting, do not secure even one complete revolution without changing the angle of inclination of the hydraulic piston. In the endless screw arrangement, there being no limit to the working of the motor in either direction (no return-stroke necessary), the vessel can always, unless outside reasons demand the contrary, be turned around to any desired position by the shortest cut, whether backwards or forwards. Also, the diameter of the cogwheel attached to the vessel can be made sufficiently great to avoid all unevenness of motion. In the old department the motive-power still continues to be hydraulic. If reports be true, the new department produces spiegelized steel, for the manufacture of all-steel rails. But the old department is still, as from the beginning, devoted to the production by the direct method of steel for steel-headed rails. The most remarkable fact connected with this direct steel is the ease with which it welds to the iron 'of the rail-packets, although no borax or other fluxing agent is used to facilitate the welding. It is very rarely that an exception occurs, and an ingot or a charge is discarded by the rail-mill. The mixture of pig-iron used for the production of this steel is melted in cupolas of very interesting construction (not to be de-

By Waldemar Lindgren

I. INTRODUCTION AT the time of the discovery of America the old world had a scant supply-of the precious metals. Both the northern and the southern part of the new continent proved wonderfully rich in gold and silver and its treasures were eagerly looted; though the looting has lasted four centuries, the nines of its mountain chains are far from being exhausted. Even the later discoveries in Australasia and eastern Siberia could not rob the Western Hemisphere of its position as the greatest gold and silver producing region of the world, though finally the developments in a narrow and circumscribed area in South Africa wrested from the Americas their supremacy in the production of gold. Nevertheless the history of the two parts of the great western continent has been strikingly different. At first the Spaniards extracted vast treasures of silver from Mexico, Peru, and Bolivia, while Colombia and some placer deposits in Peru yielded a smaller quantity of gold. A couple of centuries later, a stream of gold began to flow from Brazil, the silver production from the countries mentioned above continuing strong in the meanwhile. Later on, the yield of South America diminished, but to offset this there began a wonderful series of discoveries in North America. The gold fields of California astonished the world; and when the cream of these had been skimmed off there began a no less amazing development of the Central Cordilleran gold and silver districts, which soon wade the United States the greatest producer of the precious metals. Aided by ever improving technique, extensive exploration, and a system of railroads, the yield was maintained and increased. Still later followed the discoveries of the gold fields of the arctic region and silenced those who had maintained that the zenith in gold production had passed. Recently the province of Ontario in eastern Canada

Jan 4, 1916

By J. L. Gregg

A study of copper-base and silver-base alloys was made with the object of finding, if possible, useful alloys subject to dispersion hardening. These studies led to the discovery of several alloys showing considerable dispersion hardening, the most important of which, the alloys of copper with iron, nickel, cobalt and chromium silicides, have since been very ably reported by M. G. Corson.l This paper is offered as a few notes covering alloys other than those described by Corson and some further data on the silicide alloys. Copper Alloys For the purpose of making a rapid survey of copper alloys that might show useful dispersion-hardening phenomena, various alloys were prepared containing 3 per cent. of additional elements added in such proportion that possible compounds could be formed without an excess of either added element. These alloys in the form of rolled or forged pieces were quenched in water from a temperature of 871" C. (1800" F.) and subsequently aged at various lower temperatures for l-hr. periods. The comparison of the Rockwell hardness of the quenched alloys with the maximum hardness of the alloys after aging was used as a measure of the dispersion hardening. Table 1 shows the Rockwell "E" hardness 1/8-in. ball, 100-kg. load) of the quenched alloys, together with the maximum hardness resulting from aging. The reheating temperature given in this table is the aging temperature at which maximum hardness resulted from a l-hr. sojourn. From this table it may be observed that only the silicide alloys showed significant dispersion hardening. Of these, the only one not described by Corson is the Cu-Be-Si alloy. This alloy contained 1.35 per cent. beryllium and 1.78 per cent. silicon, which is approximately equivalent to 3 per cent. Be2Si. It had a yellow color and scaled much less than the other silicide alloys upon heating. It could be worked easily either hot or cold but hardened very rapidly on cold working. The annealed alloy upon drawing from a diameter

Jan 1, 1929