Platinum Capsules Research Articles

Melting Relations of Brown-Hornblende Mylonite from St. Paul's Rocks under Water-Saturated and Water-Undersaturated Conditions to 30 Kilobars

Crystalline brown-hornblende mylonite, with a composition similar to some basanites and nephelin-ites, was crushed and reacted with excess water and with no water added (about 2% water present) in sealed platinum capsules in a piston-cylinder apparatus from 10-30 kb. The solidus with excess water, and liquidus curves for excess water and for 2% water, are presented, together with stability limits (within 50°C brackets) in the melting intervals for amphibole, plagioclase, clinopyroxene, garnet, olivine, rutile, nepheline, and zoisite. With increasing water content and consequent decreasing liquidus temperature on the water-undersaturated liquidus surface, the number of liquidus and near-liquidus minerals increases, the field of olivine extends to higher pressures, and garnet becomes stabilized at pressures above 20 kb. Orthopyroxene was not found. Amphibole is stable at the liquidus between 10 and 21 kb with excess water at 1,075°C, and between 10 and 16 kb with 2% water at 1,175°C. These results combined with previous interpretations are consistent with the following tentative petrogenetic history for St. Paul's Rocks. A water-undersaturated olivine-basanite magma rose from a depth of about 100 km at a temperature of 1,200-1,300°C, and differentiated until it reached a depth somewhere between 45-70 km, where the magma had reached the composition of brown-hornblende mylonite. At a temperature between 1,050°C and 1,000°C amphibole was the dominant mineral being precipitated. Exsolution of water from the magma became fixed in the mantle peridotite as amphibole, and locally may have caused incipient melting of the peridotite. This process may have initiated upward movement of the heterogeneous assemblage of peridotite and largely crystallized basanite magma, which rose as a near-solid diapiric intrusion with temperature possibly remaining as high as 1,000°C up to 7 km deep, where intense mylonitization began during the final ascent and shallow emplacement.

Glass formation in the system CaO-Al2O3-CaF2

The formation of glass in the system CaO-Al2O3-CaF2 has been investigated in sealed platinum capsules having about one atmosphere pressure of AlF3 vapour. Transparent colourless glass could be obtained in the low-fluoride moderate-alumina region of the system (Al2O3 35 to 60%, CaF2 0 to 20%). With the concentration of CaF2 exceeding 20% considerable amount of quench crystals of CaF2 appeared in the glass. Moderate-alumina low-lime melts containing more than 35% CaF2 occur in an immiscibility zone. At the low-fluoride periphery of the liquid immiscibility zone a small zone of metastable liquid immiscibility has been found. The results of electron microscopic and infra-red spectroscopic studies of a few selected glasses have been analysed in combination with the molar refractivity data to reflect upon the co-ordination characteristics of aluminium in these glasses.

Water-saturated and undersaturated melting relations of a granite to 35 kilobars

Biotite granite from the Sierra Nevada batholith was reacted, with known water contents in sealed platinum capsules, in a piston-cylinder apparatus between 10 and 35 kb. With the liquid just over-saturated with respect to water, temperatures for solidus and liquidus (quartz/coesite-out curve), respectively, are: 2 kb, 680°C, 715°C; 10 kb, 620°C, 725°C; 25 kb, 655°C, 800°C; 35 kb, 700°C, 850°C. The temperature interval is 35°C at 2 kb, 105°C at 10 kb, and 150°C at 35 kb, indicating that granite departs from a eutectic composition at depths greater than about 40–50 km. We conclude that crystal-liquid equilibria are not likely to yield primary rhyolite or granite magmas by partial fusion of oceanic crust in subduction zones. The solubility of water in granite liquids, in wt%, is 22.5 ± 2.5 at 25 kb and 810°C and 27 ± 2.5 at 35 kb and 850°C. These results indicate that a miscibility gap persists between water-saturated silicate magmas and aqueous vapor phase at least to pressures corresponding to 100 km depth in the mantle. The formation of kyanite near the liquidus of water over-saturated granite indicates that the aqueous vapor phase is enriched in alkalis and possibly silica, relative to the condensed phases.

Melting of Gabbro (Quartz Eclogite) with Excess Water to 35 Kilobars, with Geological Applications

Crystalline, fine-grained, high-alumina olivine tholeiite with excess water was reacted in sealed platinum capsules in piston-cylinder apparatus between 10 and 35 kbar pressure. Runs were planned to determine the curve for the beginning of melting, but combining these with published results at lower pressures permitted delineation of the major features of the phase diagram through the melting interval. Amphibolite melts below 10 kbar; quartz eclogite melts above 25 kbar; between them is a melting interval dominated by the breakdown of amphibole and formation of garnet and jadeitic pyroxene. The results introduce two features for geological applications. The solidus changes slope at about 13.5 kbar; the amphibole maximum-stability curve changes slope in the interval 12.5-15 kbar to such an extent that the amphibole stability field is more restricted at high pressures than anticipated from previous studies. With free water, eclogite is Stable only at depths greater than about 70 km, and amphibolite is Stable in the deep crust. Amphibolite crust thickened in the depth range 40-60 km with aqueous pore fluid melts, forming a liquid enriched in silica and albitic plagioclase; this is a potential source of water-undersaturated liquids for batholiths. The upper boundary of the mantle low-velocity zone could be the boundary between rocks with interstitial amphibole and those with interstitial hydrous silicate liquid. In oceanic crust forming the upper part of a subducted lithosphere slab, it appears that most hydrous minerals dehydrate or melt before they reach 100 km depth. If so, dehydration of subducted oceanic crust does not supply water for andesitic magmatism beyond the arc-trench gap, nor contribute to the chemical variations recorded in andesites across arc complexes (K_2O, K/Rb).

The phase equilibrium diagram of the system CaO-Al2O3-CaF2

The phase equilibria of the system CaO-Al2O3-CaF2 have been studied by quenching in sealed platinum capsules followed by microscopic and X-ray examination of quenched products. The established phase diagram contains five ternary eutectics, two ternary peritectics and two invariant points of four-phase monotectic transformations. The system Al2O3-CaF2 has been established to be the stable diagonal of the reversible reciprocal system Al2O3 + 3CaF2 = 3CaO + 2AlF3. In the high-fluoride region a wide zone of liquid immiscibility has been found. The system also shows such rarely noticed but theoretically possible phenomena as the transformation of peritecticals into eutecticals and occurrence of three different primary fields under single continuous zone of liquid immiscibility.

The join calcium monoaluminate-calcium fluoride

The system CaO-Al2O3-CaF2 is important in cement and slag technology and in metallurgy. A section of this system, the pseudo-binary join CaO·Al2O3-CaF2, has been studied and the phase diagram established. This join is of particular interest since CaO·Al2O3 is one of the main constituents of high alumina cement. Quenching in sealed platinum capsules followed by microscopic and X-ray examination was the principal method used. The only compound on the join is 3CaO·3Al2O3·CaF2 which melts congruently at 1507±1.5° C and forms one eutectic with CaO·Al2O3 at 11% CaF2 and 1498±5° C and another with CaF2 at 97.5% CaF2 and 1405±10° C. There is a wide zone of liquid immiscibility. The m.p. of CaF2 was determined to be 1422±1° C. Attempts to use high temperature microscopy to study this system are described.

Melting Reactions in the System NaAlSi3O8-KAlSi3O8-SiO2-H2O to 20 Kilobars Compared with Results for Other Feldspar-Quartz-H2O and H2O Systems

Synthetic feldspar with composition was crystallized from gel and a portion mixed with 10 wt percent natural quartz. These starting materials were reacted with excess water in sealed platinum capsules, using half-inch-diameter piston-cylinder apparatus. Univariant melting curves were located between 10 and 20 kbar pressure for the systems . Points on the reaction curves are:. (2) . (3) A reaction common to both systems, . These three reaction curves meet at an invariant point at 16.8 kbar and 605° C. Reactions (1) and (2) represent the curves for the beginning of melting of granite and syenite, respectively. A review of previous results provides our best estimates for melting curves from 1 to 20 kbar (or higher) in these systems and additional systems . Curves for the beginning of melting of major rock types in the presence of excess water have recently been extended to mantle pressures, and the influence of feldspar and quartz in granite, tonalite, syenite, and gabbro melting is evident to about 15 kbar, from comparison of the rock- curves with the feldspar-quartz- curves. The melting pattern changes above the pressure where plagioclase feldspar breaks down, and the slope (dP/dT) of the melting curves then becomes positive and roughly parallel with curves for dry systems. Data for excess-water systems are almost complete; these will provide guides for the study of water-deficient systems in the vapor-absent region, which is more relevant for problems of magma genesis and magma evolution.

The preparation and properties of rutile-type transition metal oxyfluorides

Rutile-type transition metal oxyfluorides have been prepared by various solid state reactions at 900–1300°C and 100 to 65,000 atm in sealed platinum capsules. The products include: TiOF, VOF, FeOF, the solid solutions Ti 2O 4− x F x and V 2O 4− x F x , and several mixed transition metal oxyfluorides of the type MM′O 3F. Single crystals suitable for physical measurements were obtained for TiOF, VOF, and FeOF. The oxyfluoride products, characterized by X-ray crystallographic techniques, were all found to have the rutile-type structure. The electrical and magnetic properties of these materials were determined.

Melting of Granite with Excess Water to 30 Kilobars Pressure

A chemically analyzed biotite granite from the Dinkey Lakes, Sierra Nevada Batholith, consists of 34.8 per cent quartz, 31.5 per cent plagioclase, 29 per cent orthoclase, and 4.7 per cent mafic minerals (mainlybiotite). The crushed rock, sealed with 25-35 wt. per cent H2O in platinum capsules, was reacted in piston-cylinder apparatus. The curve for the beginning of melting passed through 620° ± 5° C. at 10 kb. and 605° ± 5° C. at 15.3 kb. At about 17 kb., the plagioclase broke down to yield jadeite and quartz, and the solidus curve then began to increase in temperature with increasing pressure, reaching 670° C. at 27 kb. At higher pressures, quartz was transformed to coesite, and the melting curve continued to rise. In subsolidus runs at 20 kb., the original orthoclase and biotite were completely dissolved in the aqueous vapor phase. These experimental results, along with similar results in the SiO2-excess portion of the system NaAlSiO4-SiO2-H2O, provide no support for the theoretical predictions that solid-liquid-vapor melting curves should pass through a temperature minimum at 10 kb. or less. The water-saturated melting curve for the granite provides physical limits for the generation of silicate magmas within the crust and mantle.

High-temperature, condensed-phase equilibria in the system Ti-W-O

By using the sealed capsule technique, the system Ti-W-O has been studied at high temperature. Along the TiO 2-WO 3 join, no compound was found and a binary eutectic exists at 1233°C and 64 mole % WO 3. In the ternary system, six crystalline phases, α-Ti, β-Ti, TiO, Ti 2O 3, Ti 3O 5 and TiO 2 were found stable at 1400°C in the titanium-oxygen system and all of them form equilibrium assemblages with tungsten. Also at 1400°C, a complete series of solid solutions formed along the join TiO 2-WO 2 and the formation of liquid in the oxygen-rich compositions did not develop beyond this join. At 1700°C, reactions between metallic titanium and the platinum capsules which were used became significant and destroyed the sealed systems. Equilibrium data could not be collected in the region W-TiO-Ti. No attempt has been made to determine the actual pressure and the partial pressure of oxygen necessary to produce equilibrium relations in this system. Generalizations which are governed by the phase rule are stated.

Dense form of germanate orthoclase (KAlGe3O8)

Orthoclase (KAlSi3O8) is one of the most abundant minerals that contain potassium as a main constituent element. No natural polymorph of this mineral with denser structure has been found, nor has one been made in laboratory [Boyd, l964]. In the present study a new dense form of germanate orthoclase (KAlGe3O8) was synthesized during a preliminary study on the determination of solid solubility of germanate leucite (KAlGe2O6) in germania (GeO2). Proper proportions of solutions of KOH and Al(NO3)3 and powder of GeO2 were carefully mixed, evaporated, and fired at 600°C to decompose Al(NO3)3 into Al2O3. An X-ray powder diffraction of the product revealed that a mixture of GeO2 and amorphous material had been made. The starting material prepared in this way was charged in a platinum capsule and heated and hydrostatically compressed for 1 hour at 980°C and 25 kb in a piston-cylinder type apparatus.

High temperature phase equilibria in the systems Sm 2O 3WO 3 and Sm 2O 3WWO 3

Using the sealed capsule technique, the system SmWO has been studied at high temperatures with emphasis on the formation and stability of ternary phases. The equilibrium relations in the region Sm 2O 3WWO 3 at 1700°C and along the join Sm 2O 3WO 3 were determined in detail. Three ternary phases were found to be stable at high temperatures. They are 3Sm 2O 3·WO 3, and 7Sm 2O 4·4WO 3 with melting points of 2240 and 2190°C, respectively, and Sm 2O 3·WO 3, which melts incongruently at 1690°C. Two low temperature phases, Sm 2O 3·2WO 3 and Sm 2O 3·3WO 3, were also formed in the system, and melt at 1245 and 1155°C, respectively. The reaction between the platinum capsule and metallic samarium, which destroys the sealed system, prevented the collection of reliable phase data for the SmSm 2O 3W compositional range of the system. Experiments on alloying tungsten and samarium in hydrogen also failed to produce significant data for the WSm join due to the loss of samarium at high temperatures. No attempt has been made to determine the actual pressure and the partial pressure of oxygen necessary to maintain the condensed phase equilibrium relations shown. Generalities governed by thermodynamics and the phase rule are stated.

Phase Equilibrium Diagram CaO-CaF2-2CaO.SiO2

Differential thermal analysis and quenching experiments were used to establish the ternary phase diagram CaO-CaF2-2CaO.SiO2. Hermetically-closed platinum capsules were used to prevent fluorine loss in the form of HF, SiF4, and CaF2 by reaction of the CaF2 with water vapor or SiO2, or by evaporation. The melting point of pure CaF2 was 1419°± 1°C. There is one binary eutectic in the system CaO-CaF2 and there are two ternary eutectics in the system CaO-CaF2-2CaO.SiO2. The results of the present study were combined with literature data to construct the phase diagram CaO-CaF2-SiO2.

Phase Relations in the System Boron Oxide–Silica

The suggested phase diagrams for the system B2O3‐SiO2 as drawn from the findings of previous investigators are presented. These diagrams show the wide controversy regarding this system. The principal difficulties in obtaining reliable equilibrium data are the volatilization of B2O3, the hydration of B2O3‐rich glasses, and the great viscosity of B2OrSiOz melts. In this investigation firings were made in sealed platinum capsules. Where necessary, they were opened and studied under xylene to eliminate hydration. Phases were identified by optical and X‐ray methods. The liquidus was obtained by determination of the temperatures at which the stable phases of SiO2 completely dissolved in the borosilicate melts. The criteria used for equilibrium are discussed.

Hydrothermal Crystallization of Yttrium‐Iron Garnet on a Seed

Yttrium‐iron garnet has been shown to be the stable solid phase, congruently saturating, and not subject to reduction in 50 wt% NaOH between 350° and 425°C at pressures from 200 to 1350 atm. Substantial diffusivity of hydrogen through platinum and gold has been shown to lead to the formation of Fe3O4 in garnet syntheses attempted in platinum or gold capsules where water was the pressure‐transmitting fluid. Yttrium‐iron garnet has been grown on a seed crystal under the following conditions: crystallization temperature, 370°C; dissolving temperature, 420°C; pressure, 200 atm; and solvent, 50 wt% NaOH. The rate of crystallization was 0.08 mm per day in the (111) direction.

Calorimetric Assembly for the Measurement of Heats of Fusion of Inorganic Compounds

The apparatus consists of a calorimeter of basically simple design, above which is a movable, vertical furnace for heating the specimen contained in a hermetically sealed platinum capsule. A complete series of measurements may thus be carried out on one sample. The capsule is dropped directly into a metal dry-chamber in the calorimeter in contact with a stirred liquid for measurement of heat content changes. A recommended procedure, based on experiments in pairs is described; one of each pair being a calibration drop, the other the specimen drop. The computation of heat content changes from the temperature changes observed is described. The limits of error of this and other calorimetric assemblies are critically discussed. Data to illustrate the results for the LiCl–KCl eutectic mixture (mp 354.1°C) and the reproducibility of the measurements are given. The calorimetric assembly is capable of measurements of heats of fusion of inorganic compounds to an accuracy of ±2%.

Emergency measures and precautions in radium accidents.

The escape of radium salts from sealed containers has, in several instances, resulted in expenditure of from $50,000 to $100,000 by the institutions where such accidents occurred. These figures may seem exceedingly high. They include, however, the costs of decontamination, medical care, legal advice, lost production time, and replacement of equipment that could not be decontaminated. In some instances such an accident has resulted in serious contamination of the exposed persons because of the absorption, inhalation, or ingestion of radium salts. On July 24, 1951, a platinum capsule containing 50 mg. of radium sulfate became opened at an industrial plant in Cincinnati. Within a few hours after the accident had been discovered, radium sulfate was spread rather widely throughout the plant. Several persons inhaled some of the radium at the time of the accident. A careful survey of the medical literature showed no readily available source of information as to

Emission of slow neutrons by a radium-beryllium source.

KNOWLEDGE of the emission of slow neutrons by sources is essential wherever effective slow-neutron cross-sections much exceed fast-neutron cross-sections. The investigation of the Szilard–Chalmers effect on manganese and arsenic with fast neutrons is an example1–4. We have now measured the emission of slow neutrons, in three energy channels (resonance bands of dysprosium, indium, iodine), by a ‘natural source’ of the common type. The source consisted of 300 mgm. radium as the chloride, mixed with an excess of beryllium metal (2–3 gm., but exact amount unknown), and was contained in a platinum capsule of 0.025 cm. wall thickness. Total neutron emission was of the order of 3 × 106 sec.−1, that is, equivalent to that of about 200 mC. radon–beryllium5.

Application of radium in carcinoma of uterine cervix: A standard combination for convenience and uniformity

T HE surgeon orders radium for carwall thickness of 0.5 mm., the loss by cinema of the cervix through the absorption amounts to about ?Jo of the hospital offrce, simply designating dose which the capsule contains; when the “ Standard Combination.” This includes : capsule wall is I mm. thick, the loss is (a) Two, I mm. wall thickness, platinum +fo and when it is 2 mm. thick, the loss capsules each 25 m.c. W.D. (Working Dose, or actually emitted dose) for intrauterine use. These are supplied, placed in tandem in a thin rubber sac with cord attached. An introducing forceps accompanies this. (b) Two, 2 mm. wall thickness, platinum capsules each 25 m.c. W.D. (Working Dose, or actually emitted dose) for vaginal use. A piece of ametallic rubber tubing, 3 mm. wal1 thickness and 8 inches long, together with a dumb-bell joint for fashioning amounts to about 46.

Leidenfrost' Phenomenon

A FEW days ago I was examining the “rosette” formed by a spheroid of water in a hot platinum capsule, and noticed that the outline was not a continuous curve, as is generally represented in books, but was “beaded” with re-entering angles as shown by the continuous, lines in figures 3, 6, 9, while the curve of each bead could be distinctly traced within the drop, forming a “fluted” outline, shown by the dotted lines in the same figures. It was at once manifest that both the “beaded” and “fluted” figures were produced by the superposition of the retinal images of the drop in two extreme conditions of vibration; that, in the case represented by 3, the drop was really vibrating like a bell which is sounding its first harmonic above its fundamental note, and therefore possesses six ventral segments, the extreme forms assumed being represented 1 and 2 respectively, and that 6 and 9 represent the appearance of the drop when vibrating like a bell which is sounding its second and third harmonic respectively. To verify this a spheroid of about five-eighths of an inch in diameter was produced; and as soon as the beaded decagon, 9, was steadily maintained, the room was darkened, and the spheroid illuminated by sparks from Holtz's machine. Immediately the curvilinear pentagons 7 and 8 were apparent, and frequently the vibrations continued perfectly steady for several seconds. When the drop had diminished in size the mode of vibration changed, and the crosses represented by 4 and 5 appeared when the sparks passed; on opening the shutters the beaded octagon 6 appeared almost perfectly steady in the capsule. The figures 1, 2, and 3 were obtained in the same manner, and with a larger spheroid twelve and sixteen beads were obtained, presenting respectively curvilinear hexagons and octagons when illuminated by the sparks. In one case a small spheroid presented a very large number of beads in its outline; but on examining it with sparks it was found to be produced by the crosses 4 and 5 rotating very rapidly about a vertical axis. Two or three particles of carbon introduced into a spheroid remained for a long time close to the surface of one “ventral segment”, like lycopodium powder on a Chladni's plate, and when they escaped from it were ensnared by the next segment. The figures observed when the spheroids were illuminated by sparks were fully as exorbitant as those shown at 1; 2, 4, 5, 7, and 8.