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By Burnham E. Field

The chemical industry is constantly looking for new materials which either are more resistant to corrosion than those now available or have improved physical properties to meet the requirements of higher temperatures and greater pressures. Attack by acids is one of the more important forms of corrosion and in the last few years the development of acid-resistant alloys has been quite rapid. Perhaps the most notable example is that of nitric acid, the problem of which has largely been solved by the chromium-iron and chromium-iron-nickel alloys. Sulfuric acid may be handled in lead, iron, or the iron-silicon alloys, depending on conditions. As to hydrochloric acid, no metal or alloy can be called entirely satisfactory for handling this acid under plant conditions.' The results of our investigations on the resistance of the nickel-molybdenum alloys to hydrochloric acid have been confirmed by those of Guertler, Rohn, Schulz, Jenge, and others12 but thus far only one such alloy has approached commercial production in Germany; this contains approximately 15 per cent. chromium and 7 per cent. molybdenum with the remainder chiefly nickel. Dr. S. W. Parr, as far back as 1914, developed a complex alloy known as "illium," with a nickel base and containing some molybdenum. 3 Dr. Parr was primarily interested in an alloy for lining bomb calorimeters, and while illium does show good resistance to acid it is too expensive for general use. Two United States

Jan 1, 1929

By William Hamilton Merritt

Since 1880 the occurrence of gold-ore has been known in the Lake of the Woods district. In 1879 the writer examined a so-called silver-location in the lake. More recent developments have extended, south and east, to the Rainy lake and along the Seine river, which flows from the northeast into the Rainy lake. The gold occurs in quartz-veins in the Huronian series. These Huronian rocks occur in belts in the Laurentian; the latter being the predominant formation in the eastern part of Ontario.

Jan 1, 1897

By F. J. Fayers, J. W. Sheldon

A theoretical discussion is presented of the behavior of the interface between two fluids of different physical properties when displacement is occurring along a thin tilted bed. An approximate equation of motion is deduced for the motion of the interface, suitable boundary conditions are derived and the conditions necessary for the approximation to be valid are determined. Steady-state behavior and the circumstances under which a steady-state interface can develop are discussed. Finite-difference solutions of the equation of motion for two characteristic water-drive problems are presenled. The theory of displacement in a thin bed may be regarded as being the porous-medium-equivalent of the classical "shallow-water wave" theory of hydrodynamics. INTRODUCTION The solution of moving interface problems are important in predicting the behavior of oil reservoirs under various conditions of production. Kidder4,5 has obtained analytic solutions for the fingering problem and for another particular case of the motion of the interface between two immiscible fluids of unequal density in a porous medium. In the present analysis, we analyze the problem of the motion of an interface along a slightly dipping bed whose length is long compared with its thickness. The requirement of a thin bed is necessary in order to give a simple differential equation for the motion. The two fluids are of unequal density and mobility. In the derivation of the equation of motion, it is assumed that the lighter fluid is being injected at constant rate at the high end of the porous layer, while heavy fluid is produced at the low end of the layer. The analysis applies equally well, however, to the reverse procedure in which the heavier fluid is injected at the low end of the tilted layer. It will be shown that the behavior of the system is critically dependent on which fluid has the higher mobility and that the interface can in certain circumstances achieve a simple progressive steady-state shape. The fluids may be considered to be immiscible or miscible. It is assumed, however, that the thickness of the interface region is negligible in comparison with other dimensions of the system, and that the strength of the saturation or concentration discontinuity remains constant during the motion. In conjunction with Buckley-Leverett theory and areal sweep-out calculations, the tilted interface problem is one of the fundamental problems of reservoir engineering; it defines the very important underpassing and overpassing phenomena associated with water-drives, gas-drives and secondary recovery operations. The tilted interface problem has been dealt with previously by Dietz.2 In the present paper, we endeavor to derive the pertinent mathematical results more rigorously, and in doing so we obtain modifications in both the differential equation and boundary conditions for those given by Dietz. We also attempt to show the connection between these results and some of the recent work on the stability of interfaces. Finally, we attempt to demonstrate the practical importance of the thin bed theory by showing the difference in behavior of two characteristic waterflood problems. In the favorable mobility case recovery is improved by increasing production rate, while in the unfavorable case undercutting or overcutting is minimized by reducing the displacement rate. PROPERTIES OF THE EQUATION OF MOTION Fig. 1 illustrates a porous layer of constant thickness H and tilt 8 with Fluid 1 of mobility ?l and density pl below Fluid 2 of mobility ?2 and density p2. The fluids are incompressible and flowing with volumetric flux q along the layer. Both the slope a of the interface with respect to the bed and the curvature of the interface are assumed to be small. What is meant by "small" is indicated in the derivation given in Appendix A of an approximate equation of motion for the interface. Other symbols are defined in the "Nomen-

By J. Leja, A. Pomianowski

This paper deals with equimolar solutions of xanthate and alkyl trimethyl ammonium bromide adsorption on copper, nickel and sphalerite powders. After an exposition of the experimental methods used and the results obtained, a thorough discussion leads to the conclusion that some molecular association between xanthates and CnTAB's does take place in the bulk of the solution as well as at the air/liquid interface. A spectrophotometric study of xanthate solutions alone and their mixtures with equimolar amounts of alkyl trimethyl ammonium bromide (CnTAB) has established the additivity of ultraviolet spectra (190 to 400 mµ) for potassium ethyl xanthate (KEtX) and C12TAB. No obvious effect of C12TAB addition on the decomposition rate of KEtX was observed, the half life of which was established as 29±3 days at 22°C and pH ~ 6. In mixed solutions of longer xanthate homologues (e.g. hexyl and nonyl) and equimolar CnTAB, colloidal precipitates are gradually formed which contain primarily the corresponding xanthate molecules. The kinetics of collector abstraction by copper, nickel and sphalerite powders were studied in 10-5 to 10"3 M solutions of KEtX alone and in equimolar mixtures of KEtX and CI2TAB. Presence of C12TAB caused a two to three fold increase in the amounts of xanthate (equivalent to many monolayers) abstracted by copper and nickel powders (and in their rates of abstraction) but had no effect on the abstraction of xanthate by unactivated sphalerite (equivalent to less than a monolayer). The adsorption of C12TAB itself from the mixed solutions was very low, at most one monolayer only, and was not influenced by the nature of the solid powder used. A change in the rates of abstraction, observed with copper powder, was interpreted as a completion of a multilayer coating (completely enveloping the grains of powder) following which the rate of reaction between solution and substrate becomes controlled by diffusion through this coating. Work of Buckenham and Schulmanl on molecular associations between different collectors has shown unusual synergistic effects in flotation of individual minerals using mixtures of xanthates and alkyl trimethyl ammonium bromides. The objectives of the present work were: 1) to determine whether these molecular associations between the two types of collectors (indicated by strong surface tension lowering in Buckenham and Schulman's work) take place at the air/liquid interface only or in the bulk of solution as well 2) to establish whether different solids adsorb any species from the mixture of these amphipatic molecules preferentially or as molecular complexes 3) to establish whether there are any differences in the kinetics of adsorption. Metallic copper and sphalerite powder were chosen as adsorbents since they represent two extremes since copper readily adsorbs multilayers of xanthate (and is easily floated with ethyl xanthate) while unactivated sphalerite does not appreciably adsorb xanthate but is known to be readily floated by the amine type collectors. Metallic nickel was included because the infrared spectroscopic work2 on xanthate

Jan 1, 1964

By J. Spreadborough, D. LaW. King, E. Anderson

Tmzsile tests were performed on Armco iron samples, at various ternpe.ralures and strain rates, ocer a wide range of grain sizes. Analysis of the data suggests that the plot of the lower yield stress, against d-1/2,where 2d is the acerage grain diameter, is not linear (as is often assumed) but is concave toward the d. axis over the range of d-from 7 to 53 . The different values of the parameters obtained by other workers can be explained, in part at least, by the observed curvature. This curvalure is shown to be consistent with a model of yielding based on dislocation pile-ups; however, the values of obtained by fitting our data to this model differ appreciably from the values generally reported. The equation proposed by Cottrell, viz.: is a plausible empirical fit to the experimental results. The purpose of this paper is to comment on the validity of the widely used linear relationship first proposed by all' and Petch and coworkers2"4 between ay, the lower yield stress, and 2d, the average grain diameter, for bcc metals, viz.: Many workers, see Refs. 2 to 7 and Table 11, have fitted this equation to their experimental results and have obtained acceptable fits over the relatively narrow range of grain sizes used by most of them. Indeed, in some cases, so few data points were available that any more sophisticated fit would have been irrational. In most of the interpretations,'-' oi is thought to be a measure of the friction stress accompanying dislocation movement, and ky was originally inter- preted as a measure of the dislocation locking but is now believed by Cottrell" to be a function of the dislocation creation rate. In the "unpinning" theories, k, is equated to where od is the unpinning stress and 1 is the average distance from the boundary of the grain where yielding is taking place to the nearest dislocation source in an unyielded grain. Other considerations (see, for example, Refs. 11 and 12) lead to equations with a similar form to [I] where different meanings may be attributed to the parameters. While there are doubts as to the physical significance of the parameters i and k, they continue to be used by many workers; interpretations of the variations in the behavior of ferrite materials following certain treatments, e.g., aging,'3 neutron irradiation,14 have been given frequently in terms of these parameters. Some theories of the mechanical behavior of bcc metals are based on this relationship. We have investigated experimentally the oy - d-'lZ relationship for Armco iron over a wider range of grain sizes and with more data points than those given in published results. The analysis of our data suggests that the oy—d-'" relationship is not linear but is in fact concave towards the d-'I2 axis. RESULTS AND DISCUSSION The experimental work was carried out on 3-mm-diam Armco iron rods which were prepared by wire drawing from 5-mm-diam rods. By annealing in vacuum at temperatures between 7000 and 1200°C for various times, grain sizes from 7 to 20,000 grains per sq mm were obtained, the grains in all cases being regularly shaped. Grain sizes were measured by lineal interceptand by area methods; only specimens with Amax/A values of 3 to 6 were used in the Petch-Hall plots (where A is the average area of a grain and Amax is the area of the largest grain observed). For all the specimens used, the number of grains in a cross section exceeded 50, which should be adequate to avoid grain size effects.'= Tensile tests were performed at 296", 219, and 17l°K, using

Jan 1, 1969

By B. E. Thompson, H. B. Fuqua

For a very brief description of the North Texas area, and the general geological features with which it is associated, the reader is referred to the opening paragraph of last year's summary1. A more complete discussion of the structure of the area, together with other interesting data concerning it, has been published recently by the Bureau of Economic Geology at the University of Texas2. It has been impossible for the authors to isolate the statistics for production for each of the many small pools of this district, as such statistics are not kept by operators except by counties or arbitrary divisions of counties. The total number of wells drilled in Archer, Wichita and Clay counties also has been subject to some estimate, as many of the shallower holes are not reported. While both routine development in proven or semiproven areas and exploratory drilling during 1935 showed an increase over the year 1934, the discovery of new producing areas of importance did not show improvement over that period. Several extremely local productive spots within semiproven areas were found in Archer, Cooke and Wilbarger counties; and extensions to older producing areas were developed in Archer, Baylor, Cooke, Montague, Wichita and Wilbarger counties. In Archer County, the Grace and Woods No. 1 Archer County (Fee), 4 miles northwest of Archer City, in the Thomas Glass survey, encountered a sand from 2836 to 2845 ft. of Pennsylvanian (lower Canyon) age, which showed an initial yield of 75 bbl. daily. While its production is of negligible importance, it is given special mention in this review because of the fact that it is producing from a new and deeper horizon than has been previously exploited in the county. Little deep development occurred in the district during the year. The Walter Gant No. 2 C. M. Worsham in J. M. Swisher survey, about 14 miles east of Henrietta, in Clay County, was abandoned at 5127 ft. in

Jan 1, 1936

By H. B. Fuqua, B. E. Thompson

For a very brief description of the North Texas area, and the general geological features with which it is associated, the reader is referred to the opening paragraph of last year's summary1. A more complete discussion of the structure of the area, together with other interesting data concerning it, has been published recently by the Bureau of Economic Geology at the University of Texas2. It has been impossible for the authors to isolate the statistics for production for each of the many small pools of this district, as such statistics are not kept by operators except by counties or arbitrary divisions of counties. The total number of wells drilled in Archer, Wichita and Clay counties also has been subject to some estimate, as many of the shallower holes are not reported. While both routine development in proven or semiproven areas and exploratory drilling during 1935 showed an increase over the year 1934, the discovery of new producing areas of importance did not show improvement over that period. Several extremely local productive spots within semiproven areas were found in Archer, Cooke and Wilbarger counties; and extensions to older producing areas were developed in Archer, Baylor, Cooke, Montague, Wichita and Wilbarger counties. In Archer County, the Grace and Woods No. 1 Archer County (Fee), 4 miles northwest of Archer City, in the Thomas Glass survey, encountered a sand from 2836 to 2845 ft. of Pennsylvanian (lower Canyon) age, which showed an initial yield of 75 bbl. daily. While its production is of negligible importance, it is given special mention in this review because of the fact that it is producing from a new and deeper horizon than has been previously exploited in the county. Little deep development occurred in the district during the year. The Walter Gant No. 2 C. M. Worsham in J. M. Swisher survey, about 14 miles east of Henrietta, in Clay County, was abandoned at 5127 ft. in

Jan 1, 1936

By J. C. Smock

The magnetic and polaric properties of magnetite, or magnetic iron ore: are fundamental facts in magnetism. The disturbing erect of this mineral upon the magnettic needle in land surveying must have been very early observed. The difficulties arising from this source are still almost insurmountable in making accurate surveys in districts where this ore occurs to any extent, either as a rock

By C. A. Stetefeldt

Steam-dRied sulphides, obtained in the lixiviation-process, are now almost exclusively sold to smelters, the old methods of melting (after roasting) in crucibles, or cupelling with lead at the mill, having

Jan 1, 1892

By James A. Barr

Ferrophosphorus, an alloy of phosphorus and iron or perhaps a physical mixture of definite compounds of iron and phosphorus, has become of increasing importance as the use of the basic open hearth has extended. Commercial ferrophosphorus is a porous, brittle metal of crystalline structure and often with a bluish metallic luster. A typical analysis is as follows: Per Cent. Phosphorus......................................... 18.0 to 22.0 Iron............................................... 80.0 76.0 Oxygen............................................ 0.2 Sulfur............................................. 0.3 Silicon............................................. 0.1 Carbon............................................ 0.1 Manganese......................................... 0.2 This alloy was first made in an electric furnace, as it was thought that the high heat of the electric arc together with the reductive effect of carbon was necessary. About 1898, J. J. Gray, Jr., was producing a high-phosphorus pig iron in his furnace at Rockdale, Tenn., by using high-phosphorus, local iron ores. As these high-phosphorus ores were difficult to obtain, he conceived the idea of increasing the phosphorus content of the pig iron by the addition of phosphate rock to the furnace burden. When the phosphorus content of the pig was kept low and only small amounts of phosphate rock were added to the burden, no particular troubles were encountered, but when he increased the amount of phosphate rock to produce an 18 per cent. alloy, his furnace troubles rapidly multiplied. After many failures and freeze-ups, he was partly successful in making short campaigns on 18 to 20 per cent. "ferro." At first, when the furnace got in bad shape on ferro, he would switch to a regular pig-iron burden until the furnace was brought around sufficiently to start on ferro again. About this time, Mr. Gray applied for and obtained his first patent. As he grew more skilled in the furnace operations, he was enabled to extend the furnace campaigns and produce ferrophosphorus continuously for the life of the furnace lining. These improvements were made the subject of another patent issued in 1916.

Jan 1, 1925

By Gary E. McIntosh

This paper will discuss a US Bureau of Mines project designed to assess and predict the impacts which surface coal mining will have on the regional shallow groundwater system in the Powder River Basin. The primary objective will be met through the accomplishment of the following: (1) The design and establishment of a regional network for monitoring shallow groundwater systems in the basin; (2) monitoring the direction and rate of flow, water quality, and aquifer characteristics of the shallow groundwater systems; and (3) development of a regional groundwater simulation model, with appurtenant subroutines to determine local effects.

Jan 4, 1979

By John B. Miles

The present period of depression in the iron industry, with the resultant close approximation of the cost of production to the selling-price of pig-iron, should make the discussion of this subject at this time not only interesting but profitable. It is possible that it may result in the collection of data, which when added to those set forth in this paper will clearly indicate the influence of the rate of driving a blast-furnace upon its fuel-economy. The question is not whether an excessive rate of driving (meaning a rate definitely in excess of the average rate in the United States) results in an increase in the fuel-consumption, but rather whether a rate considerably less than the average does not result in a marked decrease in the fuel-consumption. The commercial and metallurgical sides of this problem must be kept separate. With a large margin between the cost of production and the selling-price of pig-iron, and a plant already in operation, it is frequently profitable to sacrifice a couple of hundred pounds of fuel per ton of pig-iron in order to secure the greater gross profits resulting from a larger tonnage. When this margin decreases with a plant in operation, or when the determination of the size of a new furnace intended for a certain production confronts the management, a clear understanding of the effect of the rate of driving upon fuel-economy becomes necessary. If it be granted that slow driving leads to low fuel-consumption, it should be borne in mind in the design of a new plant for the production of a certain tonnage that the adoption of an economical rate of driving increases only the size of the furnace proper, whereas, due to the decrease in quantity of blast required on account of the decrease in fuel burned, the stoves, the blowing-engines, the boilers and the piping may be de-

Jan 1, 1909

R. W. Raymond, New York City: In connection with the subject of multiple tuyeres, my attention has been drawn to the practicability of gaining, without the multiplication of tuyeres, the advantages which that measure is intended to secure ; and learning that this had been attempted in the invention of the Gaines radial-discharge or fan-shaped tuyere, I wrote to Messrs. Gustafson Brothers, of Sequachee, Tenn., who manufacture that tugere, for information concerning the invention itself and its performance in practice. To their courtesy I am indebted for most of the facts given below. I present these statements without expressing any personal opinion on the subject (having no personal knowledge of it), for the purpose of bringing this device to the notice of members, and calling forth both criticism and testimony concerning it. Admitting that definite advantages are to be secured by the multiplication of tuyeres, we must still confess that this change involves considerable expense in the increased number of blastpipes, tuyeres, coolers, connections, and pipes for water-circulation. There is, moreover, a serious question involved in the weakening of the furnace-wall by extra perforations. This consideration applies with special force to furnaces already built without reference to such an increase of tuyere-openings. Ledebur, in his Handbuch der Eisenhüttenkunde, says on this point (I translate from the edition of 1893, page 365): "A limit to increase in the number of tuyeres is given, in any case, by the circumstance that the perforation of the wall weakens it; in other words, that there must be left between the tuyeres a mass of masonry sufficient to carry the parts above. In most cases an appropriate number may be secured by giving to the furnace as many openings as there are meters in its circumference at the tuyerelevel. For instance, for a hearth-diameter of 2.5 meters, i.e., a circumference of 7.7 meters, seven or eight openings might be made, of which, however, one would

Jan 1, 1899

By Richard H. Rein, John Chipman

The activity of SiO2, in the entire liquid system SiO2-CaO-Mg0-A12O3 at 1600°C is calculated from the distribution of silicon between these slags and Fe-Si-C alloys saturated with either graphite or silicon carbide, the activity coefficient of silicon in these alloys, and the requisite thermodynamic data. The activities of the other components in the ternary systems SiO2-CaO-A12O3, SiO2-MgO-CaO, SiO2-MgO -A12O3 are computed from these data by the IrON blast-furnace slags can be regarded as consisting of the four major oxide components, SO2, CaO, MgO, and A12O3 along with minor proportions of other oxides and of sulfur. The purpose of this study is to measure the activity of silica in the liquid solutions of these four oxides at iron-making Gibbs-Duhem equation with the aid of the known free energies of several of the interoxide compounds and the accepted phase diagrams. Based on these activities, new data are Presented for the free energy of formation of a number of the interoxide compounds. The free energy of mixing the liquid metasilicates of CaO and MgO shows slight positive deviations from the ideal. temperatures and to obtain activities of the other components by application of the Gibbs-Duhem equation and the properties of several interoxide compounds. Recent investigations on the activity of silica in the SiO2-CaO-A12O3 system1-3 and recogntion of a serious error in older data for the free energy of formation of SiO2 (Ref. 4) have succeeded in bringing a fair degree of concordance into the results of different investigators. In the present study, the activity of silica is obtained from the silicon-distribution experiments described in a previous paper,' the revised activity coefficient of silicon

Jan 1, 1965

By W. B. Devereux

The special mriditions under which gold occurs in the Potsdam formation of the Black Hills prew~lt features worthy of a more systematic pesentation than they have heretofore received. The notes

Jan 1, 1882

By William M. Bowron

An interesting calculation was made at the Chattanooga Meeting of 1885 as to the cost of making a ton of pig-iron in the Chatta-

Jan 1, 1889

By AIME AIME

PROBABLY no man has been of greater service to the Institute and has kept more in the background than Henry Krumb. A Vice-President continuously) for the last eleven years, apparently neither his picture nor a biographical sketch ever have adorned these pages and were he forewarned in the present instance he would order us to "forget it." He is a Columbia School of Mines man, Class of '98. He worked underground at Rossland, B. C. for a time, then for a year and a half a. chief engineer of the famous Camp Bird at Ouray, Colo. For three wars he was examining engineer for the Guggenheims and since 1901 has been an independent consulting engineer with experience throughout the Americas.

Jan 1, 1939

By W. C. Phalen

Introduction............................... 100 Production and Exportation of Phosphate Rock.............. 101 Methods of Conservation........................ 101 Introductory Note........................ 101 Mechanical Methods of Conservation............... 103 Grades of Brown Phosphate Rock............... 106 Preparation of Phosphate Rock for Market, with Phases of Conservation Involved..................... 106 Removal of Overburden.................... 106 Methods of Mining...................... 107 Reworking Deposits..................• 107 Working "Cutters"................... 109 Washing and Drying..................... 111 Conservation of Fines .................... 113 Chemical Methods of Conserving Phosphate Rook.......... 113 Application in the West.................... 113 Chemistry of Process.................... 114 Substitutes for Phosphate Rock..................... 115 Natural Substitutes........................ 115 Phosphatic Limestone..................... 115 Apatite, Nelsonite and Other Minerals Containing Phosphate ... 116 . Apatite in Virginia................... 117 Guano........................... 118 Greensand (Marls)...................... 118 New Jersey....................... 118 Kentucky........................ 119 . Tennessee........................ 120 Alabama........................ 120 Excrement.......................... 120 Bones............................ 121 Artificial Substitutes....................... 121 Basic Slag......................... 121 Phosphate Rock Reserves....................... 122 Florida............... 122 .

Jan 1, 1918

By H. H. Stout

In the early fall of 1925, the writer was conducting, in the Ledoux and Co. laboratory, New York, experiments directed toward ascertaining the effect on its impurity content when cathode copper was subjected to a current of various gases at an elevated temperature below the melting point. The apparatus consisted of a vertical I-in. dia. silica tube about 12 in. long, heated on the outside. The cathodes were broken to pass 3/8-in. mesh, and a current of various different gases was passed up through a 4-in. long column of these loose cathode particles in the vertical tube furnace. Temperature was maintained to 1500º to 1600ºF. and the gas treatments lasted from 3 to 6 hr. The writer observed that whenever reducing gas (H2 or CO) was used, these cathode particles stuck together at points of contact with each other. The cohesion was so marked and tenacious that an examination was made of the fractured surfaces, when cathode particles were broken from the cluster. Crystal growth was always found to have taken place across the surfaces where separate particles were in contact, but only after all oxides, sulphates, etc., had been completely removed. The idea of a possible new process was then conceived and was disclosed to A. M. Smoot (V. P. Ledoux and Co.) with intent to obtain his views. The first conception as given Smoot was "to gas-clean broken cathodes, put them in an extrusion press, solidify and extrude them at around 1500ºF." Smoot's reaction, after a few moments considera- tion, was, "It looks perfectly all right to me.'' The writer and his assistants, W. H. Osborn and H. H. Stout, Jr., after conferring as to ways and means, decided to go ahead with preliminary laboratory experiments, which, it was thought, would move the new process from the possible to the probable. This program followed a course indicated by three basic considerations: 1. Since brittle cathodes were often unintentionally produced, it seemed probable that the laws controlling this type of deposition could be ascertained. 2. We had already proved the gas-cleaning feature. 3. There remained to prove: whether a sound, homogeneous metal billet could be produced with crystal growth established over the entire surface of each individual particle in the billet; and, if so, what would be the physical properties? Osborn arranged with Columbia University for conducting experiments in its research laboratory to prove or disprove the third item; Columbia assigned C. A. Phillipi, Jr. to assist in the project. A press with a cylinder 2 in. high and of I-in. dia. was used. It was surrouilded and heated by a resistance coil 01 Nichrome wire. Broken tough cathodes were used. Experimental Procedure The first run took place March 18, 1926. The resistance wire gave out when temperature of 1000ºF. was obtained. Pressure was immediately applied: perceptible ram movement stopped when 39,000 lb. per sq. in. on the copper was reached, with a maxi-

Jan 1, 1941

Map

Jan 1, 1960