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Jan 1, 1933

By K. Tangri, M. Chaturvedi

The addition of 0.5 wt pct Cu to Zr-2.5 Cb alloy increases the as -quenched hardness of the hexagonal martensitic a' phase, produced by water-quenching bccß-Zr phase, by about 35 pct. This strengthening has been attributed to the solid -solution hardening of the matrix. On aging ternary martensite, a' phase reverts to equilibrium a and Zr2Cu and ß-Cb precipitate out, mainly at the twin and grain boundaries, causing a secondary hardening of the matrix. COLD-worked Zircaloy-2 pressure tubes have been in use in power reactors for a considerable period of time. The search for a better material led to the development of Zr-2.5 wt pct Cb alloy which in the quench-aged condition develops 50 pct more strength than that of cold-worked Zircaloy-2, however, its corrosion resistance in water and steam in the temperature range of 316" to 400°C, in absence of neutron flux, is inferior to that of zircaloy-2.' Work carried out by Ells et al.1 and Dalgaard2 has shown that the corrosion properties of Zr-2.5 wt pct Cb alloy can be considerably improved by the ternary addition of 0.5 wt pct Cu. This paper is concerned with the effect of 0.5 wt pct Cu on the formation of martensitic a and its aging characteristics in a Zr-2.5 wt pct Cb alloy. MATERIALS AND EXPERIMENTAL TECHNIQUES Zr-2.5 Cb-0.5 Cu (referred to as the ternary alloy) and Zr-2.5 Cb (referred to as the binary alloy) alloys, supplied by the Chalk River Nuclear Laboratories of the AECL were used. The detailed chemical analysis is given in Table I. Cold rolling and swagging with frequent intermediate anneal of 1000°C were used for the initial fabrication of the alloys. All the heat treatments were carried out after the specimens were wrapped in zirconium foils and encapsulated in silica tubes under a vacuum of 5 x 10-6 mm of Hg. For optical metallography and hardness measurements specimens were mechanically and then chemically polished in a 45 pct HNOj, 45 pct HzO, and 10 pct HF solution. Hardness was measured on a Vickers hardness tester using a 10-kg load. For each specimen at least fifteen indentations were made in order to obtain a representative value. The phase identification and structural analysis were carried out using X-rays and electron diffraction techniques. Wires of 1.5 mm diam reduced to 0.12 mm diam by chemical etching were used for making Debye-Scherrer powder patterns using Cu Ka radiation in a 114.6 mm diam camera. Carbon extraction replicas were prepared by etching the specimens, after depositing a layer of carbon on the metallographic specimen, in one part HF and thirty parts ethyl alcohol. Thin films were prepared by electropolishing heat-treated 3/4 by 1/2 by 0.005 in. thick strips using a modified Bollman-Window technique. The 10 pct perchloric acid-90 pct methyl alcohol bath was kept at -50°C and polishing was done at 5 to 10 V. The thinned specimens were washed in ethyl alcohol at -30º to -40°C and dried between filter papers. Replicas and thin films were examined in a Phillips 300 G electron microscope. For resistivity measurements thin strip specimens 0.02 by 0.3 by 10.0 cm long were used. The potential leads were spot welded to the specimens in order to maintain a fixed length for the initial and the final resistivity measurements. The resistivity was measured by a Kelvin bridge in a temperature controlled room. The temperature was maintained at 72º ±1°F and the accuracy of the resistivity measurements was 0.03 µa-cm. RESULTS As-Quenched Structures. In order to produce a homogeneous matrix to study the precipitation reaction the solution-treatments of both the alloys were carried out in the -field region. From the Zr-Cb phase diagram due to Lundin and cox3 ß/a + ß phase boundary for Zr-2.5 wt pct Cb alloy is 820°C. Ells et al.1 have reported this boundary for Zr-2.5 Cb alloy containing 1100 ppm 0 to be at 920°C. Also, the addition of 0.5 wt pct Cu reduces this temperature by 50°C. Therefore, the solution-treatments were carried out at 1000°C to ensure that the alloys were in ß-phase region. The soaking time was 1 hr and the specimens were water-quenched. The as-quenched hardness of the binary alloy was 245 Vpn whereas, that of the ternary alloy was 330 Vpn. The X-ray diffraction studies indicated that the as-quenched structure of both the alloys consists of martensitic hexagonal phase a', with a c/a ratio of 1.591, and some retained ß-Zr. The presence of a' phase was further confirmed by thin film electron microscopy. Electron micrographs of typical ß-quenched structures of the ternary and the binary alloys are shown in Figs. 1 and 2, respectively. Fig. 3 shows the diffraction pattern from an area similar to that shown in Fig. 1. Although, the as-quenched hardness of the ternary alloy is about 35 pct greater than that of the binary alloy, the structure of both the alloys seems to be the same. The matrix of both alloys is heavily twinned and shows very few dislocations. Furthermore, there is no evidence of any precipitation taking place in either of the two specimens during quenching from the solution-treatment temperature. Aging Behavior of Martensitic a'. The aging kinetics of the ternary alloy were followed by resistivity and hardness measurements. The as-quenched values

Jan 1, 1970

Edward Keller, Baltimore, Md. (communication to the Secretary): When, at the New Pork meeting, February, 1899, Mr. Douglas gave an abstract of his highly interesting paper on the Copper Queen mine, he invited the members of the Institute, in his usual progressive spirit, to make a full scientific investigation of the region of that mine during the prospective excursion to Bisbee, Arizona. I volunteered to examine some of the metallurgical processes and products of the works, and obtained from Mr. Douglas a valuable series of samples. Upon the issue of his paper, however, I found that he had already a considerable volume of analyses of those products, and that little was left for me to do in that respect, except to duplicate his results, the importance of which work would not have been commensurate to the time and labor involved. I selected, therefore, only some points which he had not made entirely clear, or concerning which I was skeptical. The details of most of my work will appear in a future paper. From Mr. Douglas's figures I have calculated the values for the elimination of impurities in the so-called Leghorn converter, introduced by him at the Copper Queen works, and have found them to be as follows: Percentage of Elimination of Impurities in Pour Blows of a Converter. No of ' Selenium Sulph'r Iron. Zinc. I Nickel. Lead. Antimony Arsenic. and Blow- ! Tellurium .. 1.......... 99.4 99.6 88.0 92.6 94.4 81.6 83.8 40.3 2.......... 99.0 99.6 98.1 92.5 96.8 71.9 76.6 38.1 3.......... 98.8 99.5 93.5 91.4 96.3 63.8 80.6 25.3 4.......... 99.8 99.5 95.8 95.8 97.5 65.3 76.9 36.3 Average 99.2 99.6 93.8 93.1 . 96.2 70.6 ! 79.5 35.0

Jan 1, 1900

By A. Manganwidjoyo, W. A. Wiebenga

The aim of this paper is to disclose some of the correlations between rock parameters, hidden in Wuerker's "Annotated Tables of Strength and Elastic Properties of Rocks," 1956. The empirical relations concern dry rocks of varying porosity. Curves and equations interrelating the specific gravity, compressive strength, bar velocity, and Poisson's ratio are presented. In 1956 Wuerker published his "Annotated Tables of Strength and Elastic Properties of Rock", in which various physical properties of rocks determined by different authorities, are tabulated systematically. The tables are primarily intended for use by mining-, quarrying- and ore-dressing engineers. Since the list of measured parameters for each type of rock includes properties such as — grain size, specific gravity, porosity, compressive strength, static elastic cons:ants (moduli of elasticity, rigidity, specific damping capacity and longitudinal bar velocity) the tables are also of considerable interest to the practical geophysicist. Correlations between rock parameters may enable geophysicists, geologists and civil engineers to transiate measurements from one parameter to another. Even if these translations are of limited accuracy, or valid only within certain specified ranges, they often serve a useful parpose. The aim of this paper is to disclose some of the correlations between rock parameters concealed in wuerker's Tables. Throughout this paper the following symbols and units are used unless otherwise stated: Sg is Specific gravity, the ratio of the density of a specimen to the density of water at 4°C. P is Porosity, in %, the ratio of the volume of voids in a specimen to its total volume. CS is Compressive strength in 1000 p.s.i., the stress under which a specimen will fracture when undergoing a standard compression test. V is Bar Velocity in kilo-feet/sec, the velocity of longitudinal seismic waves measured in a slender bar type specimen. Vc is Bulk or Constraint Velocity in kilo-feet/ sec, the velocity of longitudinal seismic waves measured in a very large specimen.+is Reciprocai bar velocity in millisecs/ft (1 millisec = 10-3 sec). cis Poisson's ratio, the ratio of the lateral to longitudinal strain of a body under longitudinal stress. CORRELATIONS Specific Gravity (Sg) vs. Porosity (P) Figure 1 is a diagram illustrating the relatiooship between specific gravity and porosity for approuirr~ately 70 samples of dry rocks. A curve fitted by estimation to this data yields the empirical formula: Sg =-0.0268P + 2.67 * 0.2 (1) Considering unit volume of a porogs specimen then

Jan 1, 1961

By R. W. Nash, A. E. Schwaneke, V. R. Miller

The Bureau of Mines developed a detector for controlling sorting devices to separate the copper-bearing fragments from the barren portion of Michigan native copper and western prophyry copper ores. A successful sorter could be used to preconcentrate the ore and eliminate costly hoisting or hauling of waste. An induction balance unit was developed and used in sorting tests on crushed sized - 2.5 + 1.3-cm (- 1 + 112- in.) ores from the Kingston (0.9% Cu) and Centennial (1.6% Cu) mines of Upper Michigan. Concentrates of 4.0% and 7.5% Cu, respectively, were obtained at recoveries of 85 and 80% of the copper in the feed. Eighty percent of the sorted ore was rejected as tailing. Sorting larger fragments improved the separation efficiency. Tests on - 10+ 5-cm (- 4 +2-in.) sized Kingston (1.6% Cu) and Centennial (2.1 % Cu) ore samples yielded concentrates of 4.3 and 4.5% Cu, respectively, with corresponding recoveries of 92 and 91 %. A bout 60% of the sorted ore was discarded as tailing. Porphyry copper sulfide ores also responded to electronic sorting but at a lower separation efficiency. Sorting response was affected by the degree of segregation.

Jan 1, 1979

By John Shelton

ONE of the heaviest burdens uselessly cast by our mineral land laws upon the holder of the title conveyed by a patent from the United States is due to the provision excepting known veins from land patented as placer. In many instances the expense of defending such titles from the assaults of the owners of lode locations made upon the theory that the veins so located were known to exist at the date of the placer application for patent has exceeded many times the value of the land in question. Neither the lapse of time, however long after the issuance of the patent nor repeated adjudications by the courts serve to quiet such titles or to prevent them from being questioned. In the passage of laws providing for the acquisition of title to the mineral lands of the United States, Congress provided that the title to known veins should not pass from the United States by a patent based upon a placer location. As construed by the courts, the law (Sec. 2333 R.S.U.S.) provides that the applicant for a patent upon a placer claim may, if any vein of sufficient value to justify the expenditure of money in its development is known by him to exist within the boundaries thereof, include in his patent application an application for patent upon the vein as a lode claim; and failure to do so is to be deemed a conclusive declaration that the applicant makes no claim to the vein nor to an area of surface ground extending for 25 ft. (7.6 m.) on each side of its middle or center. As to such vein and, such area of enclosing surface ground under the circumstances stated, the title remains in, the United States notwithstanding the issuance of a patent that purports to convey the entire surface of a described area and everything beneath it, excepting only the segments of veins the apices of which lie outside of such area. Such known veins with such area of enclosing surface ground are, of course, at any time, so long as they remain unlocated, subject to location and appropriation in the same manner as other veins upon the public domain. The history of the operation of this law in one district will serve to illustrate its effect generally throughout the mining regions of the United States. In the Butte district, the mineral that first attracted the atten-

Jan 8, 1919

Jan 1, 1943

Jan 1, 1943

By ANDREW CARNEGIE

Although the noble building provided in New York City by Mr. Carnegie for the United Engineering Society has been pushed to about half-completion, the ceremony of laying its corner-stone was not performed until Tuesday afternoon, May 8, 1906. The stone lies just back of the southeast corner of the building, on the north side-of West 39th Street. Among those present were Mr. and Mrs. Carnegie, Miss Whitfield, the sister of Mrs. Carnegie, Ralph W. Pope, Secretary of the Institute of Electrical Engineers, Frederick R. Hutton, Secretary of the. Society of Mechanical Engineers, Rossiter W. Raymond, Secretary of the Institute of Mining Engineers, Charles H. Haswell, the first Chief Engineer of the United States Navy (1836-1851), now in his ninety-seventh year, John Fritz, of the Bethlehem Steel Company, William H. Fletcher, President of the Engineers' Club, E. E. Olcott, President of United Engineering Society, and other interested friends. After an inspection of the interior of the building, the group formed about the corner-stone, which had been draped with the American flag. The exercises were opened by Mr. Olcott, who appropriately welcomed Mr. Carnegie, and briefly expressed the essential value of the building, saying, in part " The societies to be housed underneath this roof have as their aim the pre¬serving and putting in tangible form of the records of scientific accomplishments so as to avoid the repetition of mistakes. The possibility of finding the records of these results all at one center, so near the great Public Library of our city, will be an inestimable advantage to all professions. It is an occasion of no ordinary moment, therefore, when we can welcome Mr. Carnegie and have him lay for us the corner-stone of this great building which his liberality has provided." Mr. Carnegie responded in happy vein, thanking the committee for their greeting, and expressing his pleasure. in being able to do what he had done to further so worthy a cause. Among other things, he said

May 1, 1906

By Harry W. Brown

This paper presents results of static capillary pressure measprements made both by the restored-state and by the mercury-injection methods, and of dynamic capillary pressure measurements made by the Hassler technique. The results indicate a variation from sample to sample of the factor used to convert capillary pressure obtained by mercury injection to those applicable to a water-gas system. Static capillary pressures measured by the restored-state method were found to be in close agreement with dynamic capillary pressures, indicating that data obtained from static measurements may be utilized with confidenre in the solution of dynamic problems of fluid flow. Experimental data are presented on the use of "J-curves" for the correlation of capillary pressure-saturation relations for a number of cores from a particular geologic formation. It is shown that the correlation was improved in some cases by reqtricting it to rertain lithologic classifications. INTRODUCTION The Meaning and Importance of Capillary Pressure The coexistence of two or more immiscible fluids within the voids of a porous medium, such as reservoir rock, gives rise to capillary forces. Because of the interfacial tension existing at the boundary between two immiscible fluids in a pore space, the interface is curved, and there is a pressure difference across the interface. This pressure difference is termed the capillary pressure. The magnitude of the capillary pressure between two immiscible fluids which together fill a porous medium depends upon several factors: the textural properties of the medium, the wettability of the medium, the interfacial tension between the fluids, the respective saturations of the fluids, and the manner in which these saturations are attained. For a given pair of immiscible fluids in a particular sample of reservoir rock, the capillary pressure is a unique function of the fluid saturation, provided that the saturation of the fluid which wets the rock has previously been decreased unidirectionally from an initially complete saturation. Similarly, for a given pair of fluids at a particular saturation which has been achieved by a

Jan 1, 1951

By Harry W. Brown

This paper presents results of static capillary pressure measprements made both by the restored-state and by the mercury-injection methods, and of dynamic capillary pressure measurements made by the Hassler technique. The results indicate a variation from sample to sample of the factor used to convert capillary pressure obtained by mercury injection to those applicable to a water-gas system. Static capillary pressures measured by the restored-state method were found to be in close agreement with dynamic capillary pressures, indicating that data obtained from static measurements may be utilized with confidenre in the solution of dynamic problems of fluid flow. Experimental data are presented on the use of "J-curves" for the correlation of capillary pressure-saturation relations for a number of cores from a particular geologic formation. It is shown that the correlation was improved in some cases by reqtricting it to rertain lithologic classifications. INTRODUCTION The Meaning and Importance of Capillary Pressure The coexistence of two or more immiscible fluids within the voids of a porous medium, such as reservoir rock, gives rise to capillary forces. Because of the interfacial tension existing at the boundary between two immiscible fluids in a pore space, the interface is curved, and there is a pressure difference across the interface. This pressure difference is termed the capillary pressure. The magnitude of the capillary pressure between two immiscible fluids which together fill a porous medium depends upon several factors: the textural properties of the medium, the wettability of the medium, the interfacial tension between the fluids, the respective saturations of the fluids, and the manner in which these saturations are attained. For a given pair of immiscible fluids in a particular sample of reservoir rock, the capillary pressure is a unique function of the fluid saturation, provided that the saturation of the fluid which wets the rock has previously been decreased unidirectionally from an initially complete saturation. Similarly, for a given pair of fluids at a particular saturation which has been achieved by a

Jan 1, 1951

By C. E. Ells, A. Sawatzky

The effect of neutron irradiation on tensile properties of the Zr-2.5 wt pet Nb-0.5 wt pet Cu alloy has been evaluated for integrated neutron fluxes up to 3 x 1020 n per sq cm (E > 1 Mev). Specimen temperature during irradiation was normally 300°C. The material was studied both in annealed and in quenched and aged conditions. When the alloy (fab-ricatedfrom sponge zirconium) is quenched from a temperature =40°C below the a + ß/ß transformation and aged 6 hr at 535oC, neutron irradiation up to the maximum studied has little effect 071 reduction in area, although there is a drop in uniform elongation and the yield strength is increased by = 25 pct. Conversely, irradiation of the alloy in an annealed condition can result in much greater changes in properties, with yield-strength increases of up to 200 pet. The dose dependence of irradiation hardening obeys the saturation equntion proposed by Makin and Minter to explain hardening in copper and nickel: Act = C[1 - exp(-Døt)/1/2 A rnodel is proposed to explain the effect of niobium content and metallurgical condition on irradiatiotz behavior. THE Zr-Nb alloys form a class of material susceptible to marked strengthening by quench and age heat treatment. With niobium concentrations as low as 2.5 wt pet, strengths can be developed which are double those of annealed zircaloy-2.1 Since the neutron-capture cross section of the Zr-2.5 wt pet Nb alloy is nearly identical to that of Zircaloy-2, significant gains in power-reactor neutron economy could be obtained by replacing stressed in-reactor components of Zircaloy-2 with the heat-treated Zr-Nb alloy. When the solution heat-treatment temperature is in the high (a + ß) phase, then the tensile properties of the quenched (and aged at 500°C) material have been shown to be relatively insensitive to neutron irradiation.1-3 Addition of small quantities of copper to the binary Zr-2.5 wt pet Nb alloy gives a useful reduction to the corrosion rate in air and carbon di- oxide,&apos; and a ternary alloy of composition Zr-2.5 wt pet Nb-0.5 wt pet Cu was chosen for one component in the Douglas Point Reactor. This application utilizes both the corrosion resistance to a moist air-carbon dioxide environment and the strength developed by a quench and age heat treatment. By suitable choice of solution heat treatment and aging temperatures, tensile properties of the ternary alloy can be made nearly identical to those considered as optimum for the binary alloy. One effect of the copper addition, however, is to give marked changes in the aging kinetics of the alloy.&apos; For this reason, it appeared that neutron irradiation might promote overaging in the ternary alloy, particularly at the elevated service temperature (=300°C). This paper describes the effect of neutron irradiation on the tensile behavior of the Zr-2.5 wt pet Nb-0.5 wt pet Cu alloy in several metallurgical conditions pertinent to its use as a reactor material. The metallurgical conditions included those for which aging occurs in the unirradiated material, and fully annealed conditions for which a higher degree of thermal stability could be expected. 1) EXPERIMENTAL Two batches of alloy were used, both made from sponge zirconium. The fabricator&apos;s analysis of principle constituents showed no significant difference between the two batches, Table I. The rod material was rolled to 1.5 in. diam, and then swaged to final sizes of 0.5 to 0.375 in. diam at nominal temperatures of 785" and 625°C for the AM and AS batches, respectively. Subsequent hydrogen analyses at CRNL confirmed that the hydrogen concentration of the as-received rod was indeed <20 ppm. However, it was found that the (a + ß)/ß transus for the AM material was approximately 25°C lower than that of the AS material, indicating rather more difference in oxygen concentration than given in Table I. Except for a small difference in yield-point behavior, the tensile prop-

Jan 1, 1965

A GREAT and incomparable speculation is whether the discovery of A compounding the powder used for guns came to its first inventor from the demons or by chance. With this invention he certainly far surpassed all men of every age from the creation of the world up to that day when it was announced by him-men so very learned, indeed like angels and of divine intellect, powerful in every knowledge and power. These had not only revived-arts and sciences and discovered new ones with their intellects, but they had information about all natural

Jan 1, 1942

By Haydn H. Murray

Although alumina constitutes about 15% of the earth&apos;s crust, it is expensive to separate and purify for the production of aluminum with the exception of the alumina in bauxite. The United States has a variety of nonbazurite resources that could substitute for bauxite, including high alumina clays, alunite, dawsonite in oil shale, anorthosite, and nepheline venite. Each of these resources is discussed from the standpoint of geology, geography, processing, and potential recovery. Potential byproducts include alica from clays, potash and sulfuric acid from alunite, soda ash from dawsonite, and soda ash and potash from anorthosite and nepheline syenite.

Jan 1, 1983

By E. M. Wise

IT is known qualitatively that the recrystallization behavior of platinum is dependent upon the amount and particularly the nature of impurities present, the amount of prior cold-work and the annealing time and temperature, but published data are limited. A study of the effects of cold-work and annealing temperature on the hardness of a sample of very pure platinum was undertaken to supply part of this information. CONCLUSIONS 1. The platinum used in the experiments had a probable platinum content of 99.99+ per cent, and had the following mechanical properties in the completely softened condition: Vickers hardness number, 39.4; ultimate tensile strength, 19,340 lb. per sq. in.; proportional limit, very low; elongation, 37.5 per cent in 2 inches. 2. The effect of cold-rolling on the hardness is shown in Fig. 1. The hardness increases rapidly up to 10 to 15 per cent reduction and more slowly up to about 75 per cent reduction, beyond which it increases more rapidly. 3. The recrystallization temperatures for a 15-min. anneal, after cold-rolling 19, 39.5, 50.8, 66, 80.5 and 89.5 per cent reduction in thickness, are approximately 765°, 700°, 635°, 600°, 545° and 425°C., respectively. 4. The recrystallized grain size of this platinum is a function of the percentage of cold reduction, being larger the lower the percentage of cold-work. 5. Little or no grain growth resulted from subjecting recrystallized samples to higher temperatures or annealing for longer times.

Jan 1, 1940

Here are the details . . . . . of how a $2.5 million research gamble, now backed by five years of intensive development in cooperation with the Chemical Construction Corp. resulted in a hydrometollurgical process that yields pure metal powders from sulphide concentrate - a process that offers potential savings of $2.5 million a year.

Jan 6, 1953

LIST OF THE MEETINGS OF THE INSTITUTE AND THEIR LOCALITIES FROM ITS ORGANIZATION Transactions Number Place Date Vol Page 1 Wilkes-Barre, Pa May, ?71 1 3 2 Bethlehem, Pa August, ?71 1 10 3 Troy, N Y November, ?71 1 13 4 Philadelphia, Pa February, ?72 1 17 5 New York, N Y May, ?72 1 20 6 Pittsburg, Pa October, ?72 1 25 7 Boston, Mass February, ?73 1 28 8 Philadelphia, Pa May, ?73 2 3 9 Easton, Pa October, ?73 2 7 10 New York, N Y February, ?74 211 11 St Louis, Mo May, ?74 3 3 12 Hazleton, Pa October, ?74 3 8 13 New Haven, Conn February, ?75 3 15 14 Dover, N J May, ?75 4 3 15 Cleveland, 0 October, ?75 4 9 16 Washington, D C February, ?76 4 18 17 Philadelphia, Pat June, ?76, 5 3 18 Philadelphia, Pa October, ?76 5 9 19 New York, N Y February, ?77 5 27 20 Wilkes-Barre, Pa May, ?77 6 3 21 Amenia, N Y October, ?77 6 10 22 Philadelphia, Pa. May, ?78 6 18

Jan 1, 1923

LIST OF THE MEETINGS OF THE INSTITUTE AND THEIR LOCALITIES FROM ITS ORGANIZATION Transactions Number Place Date Vol Page 1 Wilkes-Barre, Pa May, ?71 1 3 2 Bethlehem, Pa August, ?71 1 10 3 Troy, N Y November, ?71 1 13 4 Philadelphia, Pa February, ?72 1 17 5 New York, N Y May, ?72 1 20 6 Pittsburg, Pa October, ?72 1 25 7 Boston, Mass February, ?73 1 28 8 Philadelphia, Pa May, ?73 2 3 9 Easton, Pa October, ?73 2 7 10 New York, N Y February, ?74 211 11 St Louis, Mo May, ?74 3 3 12 Hazleton, Pa October, ?74 3 8 13 New Haven, Conn February, ?75 3 15 14 Dover, N J May, ?75 4 3 15 Cleveland, 0 October, ?75 4 9 16 Washington, D C February, ?76 4 18 17 Philadelphia, Pat June, ?76, 5 3 18 Philadelphia, Pa October, ?76 5 9 19 New York, N Y February, ?77 5 27 20 Wilkes-Barre, Pa May, ?77 6 3 21 Amenia, N Y October, ?77 6 10 22 Philadelphia, Pa. May, ?78 6 18 23 Chattanooga, Tenn May ?78 7 3

Jan 1, 1923

By H. J. Levinstein, W. H. Robinson

A method of chemically polishing silver for metal-lographic examination has been developed. The samples are prepared by polishing on 0, 2/0, and 3/0 paper. They are then polished on 600 micro-cut paper, followed by a final mechanical polish on a cloth containing 5µ diamond paste. The samples are then chemically polished in a solution of 100 cc of saturated chromic acid and 5 cc of a 5 pct HC1 solution. The chemical polishing is performed by swabbing with a cotton ball saturated with the solution. During the chemical polishing, the sample is rinsed frequently in running water. Polishing in this manner for 5 min is sufficient to remove the strained material from the previous polishing operations. The amount of material removed is approximately 4µ/min. The surface obtained is flat and free of pits. Fig. 1 is an interference micrograph of a silver surface polished by this technique. If the solution employed is of improper HC1 content, an interference color film will form on the sample. This film can be removed either by swabbing with a cotton ball saturated with ortho-

Jan 1, 1962

By M. G. F. Söhnlein

In a Bolivian tin concentrator an appliance was needed to furnish a suitable product for fine jigging from a pulp of the following composition: Mesh Per Cent. + 20 8.0 40 36.5 + 60 9.0 + 80 10.5 + loo 5.5 4-150 1 4.5 -150 25.0 99.0 Loss 1.0 In the jigging process, particles of cassiterite as small as 0.1 mm. can be recovered, provided they are not present in excess, that is if the material treated on the jigs contains sufficient coarser sands to keep the interstices between the grains open. Removing the fine material from the pulp by screening, to prepare the jig feed, is impractical, because that means the use of an 80-mesh screen or finer, and is not as effective as hydraulic classification. A screen would eliminate mineral grains from the feed which can be recovered by jigging, and in addition would throw more gangue and low-grade middling on to the jig. Formerly a one-spigot Richards vortex classifier had been used to accomplish this separation, but the tangential openings through which the hydraulic water enters became clogged by fine vegetal matter with which the water was contaminated, and which it was impossible to remove from the water. Consequently the work of the classifier was imperfect and a good deal of slime was sent to the jig. When designing the plant referred to in this paper it was decided to use a hydraulic classifier as shown in Fig. 1. The essential features had been copied from the Anaconda classifier.&apos; This remodeled classifier consists of a truncated pyramidal wooden hopper A with an attachment of cast iron

Jan 1, 1917