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By H. M. Howe

The chief purpose of this note is to call attention to the triaxial diagram as a convenient means of illustrating the properties of slags, and by this example of its use to commend it to those inclined to graphical studies having other possible applications. Explanation.—In the common or di-axial diagram, the properties corresponding to any point are determined by its perpendicular distance from each of two axes. For example, in an ordinary stress-strain diagram the properties of a given point in the curve are, first, a stress cd so many pounds per square inch, because its perpendicular distance from the horizontal axis of the diagram corresponds by the vertical scale to that stress; and second, a strain or elongation of so many per cent., because its perpendicular distance from the vertical axis corresponds by the horizontal scale to that elongation. It happens that, as a matter of convenience, we habitually place these two axes at right angles to each other; so that our measurenieilts happen to be made not only at right-angles to

Jan 1, 1899

This discussion of the paper of Chester W. Washburne should have been printed following the remarks of H. A. Wheeler, in Bulletin No. 100, April, 1915, pp. 835 and 836, but was inadvertently omitted. ROSWELL H. JOHNSON:-There is one reason why the hydrostatic interpretation of gas pressure is not wholly acceptable. As we go clown in the sands we seem to get excesses of gas. Particularly in this field it becomes excessive in quantity relative to the amount of water in the sand. If this holds in other fields as well it must mean that there has been an ascension of water, because these sedimentaries when laid down, were filled with connate water. If we do get an ascension of connate water, produced by some such phenomena as its expansion by heat or by the formation of new gas by pressure upon organic materials at great depth, we can hardly expect the pressure to be controlled merely hydrostatically. * In reply to Mr. Wheeler's inquiry as to gas wells with pressure higher than hydrostatic pressure, I would cite the original wells given by Orton on which he based the hydrostatic theory. He used in his calculation a head of 600 ft. above tide, assuming the outcrop of the Manitoulin Islands to be in Lake Superior, whereas the Trenton does not outcrop at Lake Superior. The Manitoulin Islands are in Lake Huron, the level of which is 580 ft. above tide. No allowance is made for the lower density of the fresher water near the outcrop, the weight taken for the whole column being the water of high density found at the wells.

Jan 5, 1915

By M. B. Holt

At this time, when electricity in its various applications is attract- ing so much interest, and with such good reason, it has been suggested to me that, as the Aspen Mining and Smelting Company, of Aspen, Pitkin county, Colorado, was the first mining company in America to employ electrical power for hoisting, a record of what has been accomplished by this company would be of interest. Early in the year 1888 the question of power for the development of the ore-horizon lying below the level of the tunnel through which the property is worked, became one of importance. The conditions under which it was proposed to use power were as follows (See Fig. 1): The company's mines lie upon the northwestern slope of a mountain, the ascent of which is at an angle of 28' from the horizon. The ore, consisting of argentiferous galena and other silver-bearing mineral, is found at or near the plane of contact of a superincumbent mass of blue limestone, with an underlying bed of dolomite. This contact plane dips north 30° west, at an angle of 60' with the horizon. A tunnel 1000 feet in length, driven south into the mountain near

Jan 1, 1892

By Richard Borg

The partial molal free energy of Cd in each of the four intermediate phases, Cd3 Cu, Cd8 Cu5, Cd3Cu4, and CdCu2 is determined using the Knudsen vapor pressure technique. Measurements are made also within the two-phase regions, and thus the variation in FCd is now known across the entire phase diagram. The absolute values are all less the 2.0 kcal and increase regularly with increasing Cd concentration. The small absolute value of the free energy precludes the possibility of obtaining highly accurate values; nevertheless, the results are compatible with those previously reported for the liquid phase. Additional results are reported concerning the lattice parameters of the 6, E, and b phases. THE elements Cu and Cd combine to form four intermediate phases which are designated* and E and which include respectively the following inter metallic compounds: CdCu2, Cd3Cu4, Cd3 Cu5, and Cd3 Cu. The extent of each phase with respect to temperature and composition is shown in Fig. 1 which is the equilibrium diagram drawn according to Hansen.1 All four phases are brittle, and most probably are true intermetallic compounds. Only the crystal structure of the 6 phase has been thoroughly investigated.2,3 The structure is cubic and isotypic with y brass. The structure of Cd3 Cu has not been previously reported, It is hexagonal with a = 8.11 and c = 8.76 0.02Å and the structure is presently being determined.* The compounds Cd3 Cu4 and CdCu, have been each previously the subject of a single investigation. Cd3Cu, is presumed to be cubic4 with the space group Fd3m, whereas CdCu2 is hexagonal2 with the C14-type structure. Cu2 Cd is found by X-ray analysis to be hexagonat with lattice parameters a = 5.00A and c = 16.17Å. The material appears to be pure Cu2Cd as all reflections could be indexed on the basis of the single hexagonal structure. These values disagree with those of Kripyakevich and coworkers5 who report a = 4.96Å and c = 7.98Å. Their investi-

Jan 1, 1962

By R. E. Cech

Particles -3 to 30 µ diam of a 29.5 pet Ni, 70.5 pet Fe alloy after being melted and solidified while falling through a hydrogen atmosphere were found to contain a distortion-free body-centered-cubic phase. In most particles, the amount of body-centered-cubic phase approaches or equals 100 pet. It was shown by a series of experiments that this phase forms directly from the liquid. It is pointed out that a mechanism previously suggested in recent papers on the theory of the liquid-solid transformation can account for the solidification of body-centered-cubic phase in a temperature range where face-centered-cubic is the stable phase. IN the course of an operation to produce powders for a study of the martensitic transformation in Fe-Ni alloys, an unexpected phenomenon was observed. Powders of a 29.5 pet Ni alloy, which has a subzero M, temperature, were found to contain considerable amounts of a body-centered-cubic phase at room temperature. The experiments to be described were designed to elucidate the mode of formation of this unexpected phase. Experiments and Discussion An alloy containing 29.5 wt pet Ni, balance iron, was vacuum melted from high purity electrolytic iron and carbonyl nickel shot and solidified in the crucible. The metal was converted to oxide, ground to 100 pet <37µ, pressed to a cake, and homogenized 20 hr at 1350°C. To insure homogeneity the grinding, pressing, and homogenizing heat treatment was repeated a second time. The oxide was then ground to 100 pct <37µ and hydrogen reduced at 500°C. The reduced powder was given a spheroidizing treatment to produce spherical cast particles. The treatment consisted of dispersing the particles in hydrogen and allowing them to drop through a vertical hydrogen furnace set to a temperature higher than the liquidus of the alloy. This operation, commonly known as shotting, has been described more fully elsewhere.&apos; The powder produced by this method was found to contain approximately equal parts of body-centered-cubic and face-centered-cubic phases. A magnetic separation technique, previously described,&apos; was applied, and it was found that particles were either completely face-centered-cubic or nearly completely body-centered-cubic. The microstruc-

Jan 1, 1957

By C. Hays, R. E. Swift, E. G. Kendall

Investigations of the Zr-Pt system, by metallography, incipient melting, and X-ray diffraction, determined the phase relationshifis from 0 to 50 at. pct Pt. Phase fields in the Pt-~ich region were outlined, and three intermetallics (ZrPt, Zr2Pt, and ZrPtd were located. A eutectic between Zr and Zr2Pt, and a eutectoid veaction between Zr and a Zr + Zr2Pt, were established. The maximum solubility of Pt in P Zr was approximately 13.5 wt pct, as opposed to less than 1 wt pct solubility in a Zr. EARLIER work on the Zr-Pt system was limited to an X-ray study on the intermetallic compound, ZrPt3, by H. J. Wallbaum,1 It was reported that ZrPt3 existed at 86.52 wt pct Pt, and had a hexagonal structure, isomorphous with TiNi3. Wallbaum&apos;s data revealed the following structural particulars: a = 5.633A, c = 9.21A, and c/a = 1.635A. Other studies allied to Zr-Pt alloys concerned only 1) Pt-rich alloys (0.05 to 5.0 pct Zr) for corrosion resistance,2 2) a Zr-base alloy with 5 pct Pt and 0.124 pct C for oxidation resistance,3 and 3) electroclad-ding of Zr with Pt for in-pile corrosion resistance of Zr to uranyl sulphate. 4 Metallographic, incipient melting, and X-ray diffraction techniques were applied to accurately resolve the phase relationships in the 0 to 50 at. pct (68.2 wt pct) Pt region, and to outline the phase fields in the Pt-rich area. Three intermediate phases: Zr2Pt, ZrPt, and ZrPt3, were also established by the same methods. PROCEDURE Melting stock for this program was of the highest purity obtainable. The Zr was iodide crystal bar with a low hafnium content of about 0.05 wt pct (Westinghouse "Grade 3"). The as-received Zr was treated to remove the surface film of corrosion product that resulted from a standard autoclave grade designation test. Next, the bars were processed to yield material suitable for arc melting and free of contaminants. Sheet platinum metal (Baker and Co. "Grade 2") was used for alloying additions. This material con-

Jan 1, 1962

By C. O. Burgess, A. B. Kinzel

Although vanadium is an important constituent of almost every brand of high-speed steel manufactured today, little is known as to its role in this series of alloys. The now standard 18 per cent tungsten and 4 per cent chromium constituents were the result of developments and improvements before 1903. In that year, vanadium was added to the steel by Dr. J. A. Mathews. This proved to be an outstanding contribution, so that the standard high-speed steel of today is generally referred to as the 18-4-1 type—18 per cent W, 4 per cent Cr and 1 per cent V. Various modifications have been attempted since then, but with the exception of the introduction of cobalt, no striking improvements have occurred. Vanadium has been increased to 2 per cent in many of the common brands, and at least one brand contains 5 per cent V in addition to the usual tungsten and chromium. The carbon has been gradually increased so that it is not uncommon to find 0.80 per cent in the standard grade, although the carbon in the 5 per cent vanadium steel mentioned above is approximately 1 per cent, and even 1.2 per cent has been made experimentally. The role of vanadium has never been well understood, and although vanadium has been increased to 2.5 and even 5 per cent in certain high speed steels, it has not been generally established that the higher vanadium contents result in superior cutting properties. However, in all of the investigations, of which the writers are aware, the interrelation of the vanadium and carbon contents was not considered as a prime factor. The carbon content was held at 1.2 per cent or less—generally at the usual 0.65 to 0.75 per cent. Theoretical Aspects Although the role of vanadium is not understood, there are theoretical considerations which indicate definite reasons for the improved cutting effciency due to vanadium. Refinement of the secondary grain is one distinct possibility. The well-known action of vanadium in limiting grain size might well be expected to operate in high-speed steels, and even though its action were not evident in the parent austenite grain.

Jan 1, 1932

By Byron W. Cheever

While engaged in experimenting with the usual methods for estimating phosphorus in iron and steel, it occurred to me that potassium chlorate might be used to oxidize the carbon, and thus avoid the tedious and vexatious evaporations necessary for successfully carrying out the usual methods. After many trials, the following plan was adopted : Take, for analysis, of Bessemer or other low-carbon steels, from 3 to 5 grammes; of crucible steel, 10 grammes; of pig-iron, 1 to 5 grammes, according to the percentage of phosphorus supposed to be present. Of iron, high in phosphorus (1 per cent.), take 1 gramme. Place in a No. 4 evaporating dish the amount of iron or steel decided upon, cover with a funnel which will just fit inside the dish, and then add gradually HNO3, (1.20 specific gravity), using 12 C.C. of acid for each gramme of steel or iron taken. (A larger quantity of acid will be required for small samples.) When the full amount of acid has been added, and the violent action has ceased, place the evaporating dish on a sand-bath, add 10 C.C. HNO3, (1.40 specific gravity), and boil till the bulk of the solution is reduced about onehalf. Then add 10 C.C. HNO3, (1.40 specific gravity), continue the boiling, and add from time to time, during the next 15 minutes, small portions of pulverized KCIO3, till about 2 grammes have been added. (If the solution shows signs of going dry, more strong acid must be added.) This will precipitate the manganese, with some iron. Sometimes it happens that the manganese does not come down readily, and more KCIO3, or further concentration, or both, will be required. The process is not complete till the manganese is precipitated, which may be known by the appearance of a dark, mirror-like deposit on the dish, at the edge of the solution. Boil the solution 5 minutes after the last addition of KCIO3, and then add cautiously (to prevent sudden explosions) 5 C.C. strong HCl. This will dissolve the precipitated manganese and iron. Continue the boiling till the chlorine is all expelled, adding from

Jan 1, 1885

By G. C. Waterman, W. E. Hawes

Mr. Grieves&apos; paper on "Shaft Sinking Today --A Boring Business Tomorrow" in the Dec. 1981 issue of MINING ENGINEERING is an excellent description of recent improvements in speed and costs of shaft sinking. However, shaft boring techniques are not a recent development. In 1935-36, the Idaho Maryland Co. (gold), Grass Valley, CA, bored the vertical 1.5-m-diam Idaho No. 2 ventilation and supply shaft to a depth of 346 m. The equipment was designed and perfected by Branner Newsome and was, I believe, described in "Transactions." Pickands Mather later bored a 1.8-m-diam shaft to a depth of about 305 m using Newsome&apos;s design. The Idaho No. 2 shaft cut through hard gabbro, diabase dikes, soft serpentine, very incompetent ankeritized serpentine and a strong fault zone. The completed shaft did not require timber support; the fault zone was cemented. Equipment consisted of a rotating 1.5-m or 3-m core barrel with a slotted bottom which cut a 76-mm kerf. The cutting agent was chilled steel shot introduced into the slot as needed. The driving mechanism and core barrel were lowered into the shaft, the former secured to the wall and the inshaft "engineer" operated the motors which controlled core barrel rpm and advance. After an advance of 1.5-3 m the equipment was lifted out of the shaft, a half(?) stick of powder cut off the drilled core, and it was hoisted to the surface with a cable attached to an eye bolt at the tope of the core. A "shift" consisted of three men: hoistman, equipment operator (down the shaft), and a surface laborer. Advance was variable as equipment and techniques were perfected. Near the end of the job advance was, as I remember, 1.5-3 m per shift. Costs were, as I recall, about $115/m. Up to 4 m cores were lifted out in one piece and swung to the dump by a stiff leg derrick. The Newsome equipment was relatively inexpensive to build and operate and his method should be (more than?) competetive with the methods described by Grieves.

Jan 1, 1983

By Robert C. Mackenzie

EXAMINATION by the differential thermal analysis technique of a large number of samples of soil and other clays from various parts of the world has demonstrated that the occurrence of cold-precipitated hydrated ferric oxide (the identification of which in soil clays has previously been reported5) is not confined to any limited locality; e.g., it has been found in varying amounts in clays from Britain, France, South Africa, and Mexico. The conditions necessary for its formation have not yet been elucidated in spite of the number of samples examined, and, since this mineral is so easily prepared in the laboratory, it has been considered that a study of its constitu¬tion and of the conditions under which it could be prepared might. lead to a better understanding of the factors involved. These experiments form the subject of this short paper, and while they do not supply a definite answer to the mode of formation of this mineral in nature, they may, it is hoped, add something to our knowledge in this direction. EXPERIMENTAL WORK Materials Employed The a-Fe2O3.H2O (goethite) and B-Fe2O3.H2O (Weiser and Milligan") were obtained from the Department of Geology, University of Aberdeen, and Rothamsted Experimental Station, respectively. The beta material had been prepared by the method described by Fernelius.1 y-Fe2O3.H2O (lepidocrocite) was prepared at the Macaulay Institute for Soil Research by the method of van Schuylenborgh.6 The method employed for preparation of the cold-precipitated hydrated ferric oxide* was as follows: 1: 1 NH4OH was added (moderately fast with rapid stirring) to a solution of 5 grams FeC13.6H2O in 250 ml distilled water at room temperature (ca. 15°C) until red litmus turned blue, and then 2 to 3 drops in excess. The resultant precipitate was filtered off on a Buchner funnel and washed free from Cl- with distilled water. Previous experiments having shown that drying over P2O5 at room temperature or drying at 105°C in the oven did not significantly affect the thermogram,5 samples were nor-

Jan 1, 1952

By W. F. Holbrook

In a previous paper1 a method for the measurement of the comparative desulphurizing power of slags was described and data were presented covering the range of likely slags containing up to 10 per cent MgO. In the present work the range is extended to include slags containing up to 20 per cent MgO, and the effect of temperature on 5 per cent and 15 per cent MgO slags over the range 1475&apos; to 1525&apos; C. is included. The method used was that described in the previous paper except that some of the temperature measurements were made with a noble-metal thermocouple instead of a tungsten-graphite thermocouple. Twelve-gram charges of 0.8 per cent sulphur-metal and 5-gram charges of slag were subjected to heating for 30 min. at a prescribed temperature. The charges were analyzed for sulphur content. For purposes of comparison, desulphurizing power is defined as the ratio of the percentage of sulphur found in the slag to that found in the metal. Six slag and metal charges were made coincidentally in 5/8in. holes in a section of an electrode graphite rod. One slag and metal charge was used as a control by means of which adjustment in the desulphurization value could be made for small variations in temperature and other factors. For convenient presentation of the data, the slags are arranged in groups in each of which one of the four main slag components is constant. Thus, the 15 per cent MgO slags are presented separately from those containing 20 per cent MgO. Slags with Magnesium Oxide Constant 15 Per cent Mg0.—The data on slags containing 15 per cent MgO cover a composition range of 24 to 50 per cent SiO2, 5 to 27 per cent A1203 and 24 to 53 per cent CaO. Variation in composition has been in steps of 2 per cent over much of the area. Because the change in desulphurization power is generally gradual with gradual change in composition, certain sections have been covered in steps of 4 per cent and even

Jan 1, 1938

By W. F. Holbrook

In a previous paper1 a method for the measurement of the comparative desulphurizing power of slags was described and data were presented covering the range of likely slags containing up to 10 per cent MgO. In the present work the range is extended to include slags containing up to 20 per cent MgO, and the effect of temperature on 5 per cent and 15 per cent MgO slags over the range 1475&apos; to 1525&apos; C. is included. The method used was that described in the previous paper except that some of the temperature measurements were made with a noble-metal thermocouple instead of a tungsten-graphite thermocouple. Twelve-gram charges of 0.8 per cent sulphur-metal and 5-gram charges of slag were subjected to heating for 30 min. at a prescribed temperature. The charges were analyzed for sulphur content. For purposes of comparison, desulphurizing power is defined as the ratio of the percentage of sulphur found in the slag to that found in the metal. Six slag and metal charges were made coincidentally in 5/8in. holes in a section of an electrode graphite rod. One slag and metal charge was used as a control by means of which adjustment in the desulphurization value could be made for small variations in temperature and other factors. For convenient presentation of the data, the slags are arranged in groups in each of which one of the four main slag components is constant. Thus, the 15 per cent MgO slags are presented separately from those containing 20 per cent MgO. Slags with Magnesium Oxide Constant 15 Per cent Mg0.—The data on slags containing 15 per cent MgO cover a composition range of 24 to 50 per cent SiO2, 5 to 27 per cent A1203 and 24 to 53 per cent CaO. Variation in composition has been in steps of 2 per cent over much of the area. Because the change in desulphurization power is generally gradual with gradual change in composition, certain sections have been covered in steps of 4 per cent and even

Jan 1, 1938

By Albert F. Schneider

The peculiar conditions under which lead and silver ores are now smelted in Salt Lake Valley, Utah, render it advantageous to make slags that are siliceous and carry a high percentage of lime. The ores treated come from Utah, Idaho, Montana, and Nevada; nine-tenths coming from Utah. These ores are siliceous, and contain but little fluxing material; the iron present scarcely sufficing for the sulphur and arsenic. Formerly ores high in iron were furnished from Cottonwood Canons, but this supply is meagre. The ores from Idaho, Montana, and Nevada are high grade galenas, more or less impure. They generally require a large amount of iron for the sulphur, arsenic, and antimony. In the winter and spring of 1880—&apos;81, we were treating at the Germania Works principally Bingham Canon lead ores and silver ores from Tintic. The former contained 15 to 30 per cent. silica, and only 4 to 5 per cent. iron (generally as iron pyrites); they ranged high in lead and low in silver, and carried more or less alumina; the lead was present chiefly as carbonate. The silver ores from Tintic contained sulphides, and ran as high as 80 per cent. silica. We had been running on a slag approximating 40 per cent. FeO, 20 per cent. CaO, 10 per cent. other bases, and 30 per cent. SiO2, which had heretofore been very satisfactory; but with the class of ores then coming in it was of the utmost advantage to use less iron and more lime, especially as the iron ore (50-55 per cent. iron and 5-7 per cent. silica) cost four times as much as the limestone (50-55 per cent. lime, 3-5 per cent. silica). The large amount of alumina in the slag influenced them for the worse; the addition of lime to the charge helped them, and after many experiments regarding the proportion of FeO, CaO, and SiO2, a slag approximating 35 per cent. FeO, 25 per cent. CaO, 5 per cent. other bases, and 35 per cent. SiO2 seemed to answer

Jan 1, 1883

By J. Ostachowicz, B. Holynska, M. Lankosz

The paper presents an analyzer and the method for the continuous determination of weight percentage of ore grains with diameter smaller than 75 µm in mineral slurries. The method is based upon the measurement of characteristic x-rays of copper excited by primary radiation of two different energies 16.5 keV and 60 keV from Pu238 and Am241 sources respectively. Additionally the backscattered primary radiation is measured in order to correct the variations of the solids content in the slurry. Since the particle size distribution of slurry can be described by the Rosin-Rammler formula, some calculations have been carried out in order to evaluate the influence of distribution parameters upon the results of the measurements of weight percentage U75 of particles smaller than 75 µm. The influence of solids content and of the copper concentration variation on the results has been also evaluated.1 It resulted from the calculations that the ratio rl/rz, where rl and r2 are the relative intensities of copper characteristic x-rays excited with 16.5 keV and 60 keV photons respectively does not depend on the copper content within the range 1 % to 4% of copper and is slightly dependent on the solids weight fraction and its chemical composition. The change of the dispersion parameter of the Rosin- Rammler distribution from 0.5 to 0.9 results in a change of value of U75 of approximately 3.0%. The results of calculations have been confirmed by the results of laboratory experiments. Therefore, a prototype of industrial analyzer for continuous determination of weight percentage of particles smaller than 75 µm has been designed and made. Its schematic drawing is shown in [Fig. 1]. Slurry is flowing down through steel flow-cell of the length equal to approx. 2 m. In the center, two XRF measuring heads (1) and (2) are located. Each of the heads comprises a rigid waterproof cover (3) with the mylar window (4), in which a proportional counter of resolution 15% for 6.4 keV is mounted with a preamplifier (5). The low- energy isotope source (6) is centrally located above the detector

Jan 1, 1980

By E. M. Norris

In the summer of 1917 it was decided to fireproof the main Tramway hoisting shaft of the Anaconda Copper Mining Co. at Butte, Mont. The shaft has three hoisting compartments and one pump compartment; it is timbered with 12 by 12-in. (30.5 by 30.5-cm.) fir timber, and is 2475 ft. (754 m.) deep. Subsidence and displacement of the surrounding country rock had produced exceedingly heavy ground, and had carried the shaft out of line, in several places, by as much as 2 ft. (0.6 m.) displacement. Constant repairing and realigning of the timbers had been necessary in order to maintain clearance for the cages. The most feasible method of fireproofing, therefore, seemed to be to cover the timbers with a coat of concrete applied with the cement gun. The cement gun, which is operated by compressed air at ordinary mine pressures, feeds a mixture of sand and cement through a hose to a nozzle having a water connection. The mortar in fluid form is thus sprayed upon the prepared surface in thin layers, which can be built up to any desired thickness. The cement gun can be set up at any convenient point; satisfactory results have been obtained with the nozzle a distance of 500 ft. (152 m.) from the gun. The shaft was thoroughly overhauled and the timbers put in the best possible state of repair. Between the 1000 and the 1400 levels, much loose ground lay against the shaft timbers on the north side; this was breast-boarded back and a 30-in. (76-cm.) reinforced-concrete retaining wall was erected, leaving a space of 12 in. (30.5 cm.) outside the shaft timbers to allow for future movements of the ground. For convenience in handling men and materials, it was arranged to concrete the auxiliary hoisting-cage compartment and the pump compartment first, using the cages of the main hoist to serve the cementing crews. The auxiliary cage was then available while the remainder of the shaft was being concreted. A tight partition of 2-in. (5.08-cm.) plank was erected between the auxiliary and the adjoining hoisting compartments, for better protection of men riding on the cages. The application of concrete made this

Jan 1, 1920

By W. F. Holbrook

IN a previous paper1 a method for the measurement of the comparative desulphurizing power of slags was described and data were presented covering the range of likely slags containing up to 10 per cent MgO In the present work the range is extended to include slags containing up to 20 per cent MgO, and the effect of temperature on 5 per cent and 15 pen cent MgO slags over the range 1475° to 1525° C is included The method used was that described in the previous paper except that some of the temperature measurements were made with a noble-metal thermocouple instead of a tungsten-graphite thermocouple Twelve-gram charges of 0 8 per cent sulphur-metal and 5-gram charge-, of slag were subjected to heating for 30 nun at a prescribed temperature The charges were analyzed for sulphur content For purposes of comparison, desulphurizing power is defined as the ratio of the percentage of sulphur found in the slag to that found in the metal Six slag and metal charges were made coincidentally in 5/8-in holes in a section of an electrode graphite rod One slag and metal charge was used as a control by means of which adjustment in the desulphurization value could be made for small variations in temperature and other factors For convenient presentation of the data, the slags are arranged in groups in each of which one of the four main slag components is constant Thus, the 15 per cent MgO slags are presented separately from those containing 20 per cent MgO SLAGS WITH MAGNESIUM OXIDE CONSTANT 15 Per cent MgO -The data on slags containing 15 per cent MgO cover a composition range of 24 to 50 per cent SI02, 5 to 27 per cent A1203 and 24 to 53 per cent CaO Variation in composition has been in steps of 2 per cent over much of the area Because the change in desulphurization power is generally gradual with gradual change in composition, certain sections have been covered m steps of 4I per cent and even

Jan 1, 1938

By Joseph C. Buchen

In principle, productiorl of salt from sea water is a simple operation. The sun and wind cause evaporation of sea water trapped in ponds, and what is left is principally salt. Commercial production, however, requires consideration of many factors. First is a high consistent annual rate of evaporation, as well as large areas of suitable low-lying ground close to economical shipping facilities. The south end of San Francisco Bay has these requisites. Large ponds are built, by using clamshell dredges to build up levees to a height of approximately 3 ft. on ground usually lower than sea level, so that the water may be taken in through tide gates without pumping. Ponds are divided into extremely large concentrating ponds and smeller crystallizing ponds. Approximately ten times more area is required for concentrating than for crystallizing. The concentrating ponds are irregular in shape and size but the crystallizing ponds are rectangular and fairly regular in size, to aid in harvesting. The ocean water is taken into the first of a series of concentrating ponds and gradually moved forward from pond to pond as it increase:: in density, reaehing the crystallizing area as a saturated brine. This brine is pumped into the crystallizer at the beginning of the net evaporating season, usually in May, and further evaporation causes its sodium chloride content to deposit on the bottoms of the ponds. The brine must be drawn off and a fresh supply added from time to time to prevent other undesirable salts from depositing with the sodium chloride. Harvesting usually begins near the end of August and now is accomplished almost entirely by mechanical means. After harvesting, the salt is stored in large sbockpiles until required for shipping or refining. The greatest amount is used for industrial purposes and is shipped without any processing other than screening, but all salt for domestic use produced by the Leslie Salt Co. is refined by the racuum process, giving a produet consistently testing over 09.9 per cent sodium chloride.

Jan 1, 1938

By Joseph C. Buchen

In principle, productiorl of salt from sea water is a simple operation. The sun and wind cause evaporation of sea water trapped in ponds, and what is left is principally salt. Commercial production, however, requires consideration of many factors. First is a high consistent annual rate of evaporation, as well as large areas of suitable low-lying ground close to economical shipping facilities. The south end of San Francisco Bay has these requisites. Large ponds are built, by using clamshell dredges to build up levees to a height of approximately 3 ft. on ground usually lower than sea level, so that the water may be taken in through tide gates without pumping. Ponds are divided into extremely large concentrating ponds and smeller crystallizing ponds. Approximately ten times more area is required for concentrating than for crystallizing. The concentrating ponds are irregular in shape and size but the crystallizing ponds are rectangular and fairly regular in size, to aid in harvesting. The ocean water is taken into the first of a series of concentrating ponds and gradually moved forward from pond to pond as it increase:: in density, reaehing the crystallizing area as a saturated brine. This brine is pumped into the crystallizer at the beginning of the net evaporating season, usually in May, and further evaporation causes its sodium chloride content to deposit on the bottoms of the ponds. The brine must be drawn off and a fresh supply added from time to time to prevent other undesirable salts from depositing with the sodium chloride. Harvesting usually begins near the end of August and now is accomplished almost entirely by mechanical means. After harvesting, the salt is stored in large sbockpiles until required for shipping or refining. The greatest amount is used for industrial purposes and is shipped without any processing other than screening, but all salt for domestic use produced by the Leslie Salt Co. is refined by the racuum process, giving a produet consistently testing over 09.9 per cent sodium chloride.

Jan 1, 1938

By William Fink

MANY investigators have attempted to determine the true nature of the internal changes taking place during aging. Merica, Waltenberg and Scott1 were the first to propose a theory of age-hardening. They attributed the age-hardening of duralumin to the precipitation of minute particles of the compound CuA12. Later Zay Jeffries and R. S. Archer2 augmented the above theory by suggesting that the small CuA12 particles acted as "keys" causing "slip interference." Many other investi-gators3 have devoted much time to the mechanism of age-hardening, some corroborating the "precipitation" and "slip interference" theory, others coming to different conclusions because of effects that to them seemed unexplainable by the early theories; e.g., the increase of electrical resistance upon aging, the fact that no change in lattice parameter could be detected during the early stages of aging even at elevated tempera-tures, and the fact that the density did not change as would be predicted. In 1932, Merica revised4 his earlier precipitation theory to take care of these presumably anomalous effects. This revised theory, the "knot" theory, assumes that substantial age-hardening occurs before actual precipitation of solute as discrete particles. The assumed mechanism is one of diffusion of solute atones into groups forming distorted regions which act as "hard" spots and cause slip interference. These "knots" are assumed to have approximately the same lattice arrangement as the solvent.

Jan 1, 1936

By E. M. Wise

MANY of the platinum metal alloys are hot-forged in the early stages of reduction from ingot and substantial quantities of platinum alloys are commercially employed at very high temperatures in ammonia oxidation units, orifices for forming glass rods and fibers and as cathodes in long-life thermionic amplifiers. They are used also for electrical heating resistors, safety blowout disks, thermocouples and crucibles. The tensile prop-erties at elevated temperatures are important in many of these situations but data on the subject are limited. Creep data also are important, but will not be covered at this time. SCOPE AND CONCLUSIONS Tensile tests were carried out at room temperature and elevated temperatures up to 1100° C. on previously well annealed samples of platinum, palladium and several of their important alloys with composi-tions shown in Table 1. The results are presented graphically in Figs. 1 to 4. The tensile strengths of platinum and the platinum-base alloys (with the exception of the 10 per cent rhodium-platinum alloy) at 1100° C. are from 16.6 to 18.8 per cent of the strengths of the same alloys (well annealed) at room temperature. The strength ratio of the 10 per cent rhodium-platinum alloy is 22.3 per cent, which is appreciably higher than that of the other materials tested.

Jan 1, 1938