ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1949.tb18962.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractA study of the color of minerals revealed that cobalt blue, the most common blue colorant in glasses, glazes, ceramic pigments, and synthetic minerals, seems to be almost completely absent in the mineral kingdom. This observation led to an investigation of the conditions under which the CoO4groups form and to the composition of natural cobalt minerals. It was found that minerals containing Co2+ions surrounded by oxygen must have formed generally at low temperature and that the cobalt was removed from the magma when the crystallization of silicates, aluminosilicates, and aluminates began. To explain this phenomenon, the distribution of heavy‐metal ions in silicate melts containing anions of different size was examined by means of model experiments.It could be demonstrated that these anions are statistically distributed around the heavy‐metal ions as long as the thermal energy is high and the interionic distances are large. With decreasing temperatures the statistical distribution changes into one that is governed by two energy terms, one resulting from the Coulomb forces, the other from the mutual polarization of the ions.On the basis of Fajans' theory of the deformation of ions it was possible to explain the formation of sulfidic ores from the original magma and the striking of glasses of the CdS t

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1949.tb18963.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractA study was made of the effect of systematic variations in the alkali‐cation concentration and size on the permeability of alkali‐silica glasses to helium at 300°C. Permeability determinations were made on fused silica, Pyrex‐brand chemical glass, Na2O‐SiO2glasses containing 20, 25, and 30 mol % Na2O, a K2O‐SiO2glass containing 30 mol % K2O, and a Li2O‐Na2O‐SiO2glass containing 5 mol % Li2O and 25 mol % Na2O.Additions of Na2O to SiO2glass produced a rapid decrease in the permeability of the glass. The permeability was found to decrease exponentially over the range 0 to 30 mol % Na2O. The substitution, atom for atom, of potassium for sodium increased the permeability of the glass, whereas lithium in combination with sodium decreased the permeability as compared with the soda glass. This was attributed primarily to the difference in the polarizing power of these cations that affected the ionic radius of the surrounding oxygens and resulted in a change in the packing density of the ions in the glass.A comparative packing index was calculated for the glasses based on the percentage of the absolute volume of glass contributed by the constituent elements. For the Na2O‐SiO2glasses, increase in packing index (indicating a more closely packed structure) was accompanied by a decrease in permeability. It is suggested that (1) the comparative packing index is a potentially valuable index of permeability only for glasses containing the same atoms, (2) new atoms introduce a new polarizing factor in the glass, and (3) the packing index ceases to be comparative for

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1949.tb18964.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractA rapid and sensitive method for the quantitative determination of the crystalline constituents in kaolin‐flint‐feldspar blends has been developed with the Geiger‐counter X‐ray spectrometer. Two variations of this method were the use of (1) a powdered sample with a reference‐material addition and (2) a polished normal body surface. The powdered‐sample technique with a reference‐material addition showed the greater accuracy and consistency of results. The polished‐surface technique was slightly less accurate, but the preparation and nature of the test specimen make it very adaptable to control methods. With this technique the complete preparation and testing of the fired surface can be carried out in approximately 10 minutes. Standardization curves for the X‐ray spectrometer technique were used to obtain quantitative information concerning the crystalline constituents in the following blends: (1) kaolin‐flint, (2) kaolin‐feldspar, (3) flint‐feldspar, and (4) kaolin‐flint‐feldspar, as well as with additions of 1.2 and 2.8% lime and magnesia, and direct substitution of nepheline syenite for feldspar. Pressed 1 1/2‐in. pellets of each body were subjected to 3‐ and 12‐hour soaking periods at 1200° and 1400°C. Quartz, mullite, cristobalite, and wollastonite were identified as the crystalline constituents in the kaolin, flint, and feldspar blends studied. Quantitative X‐ray information concerning the reduction of the free‐quartz content, formation of cristobalite and mullite, and the amount of the total crystalline content was used to determine the effects of variations in composition and

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1949.tb18965.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractA method of testing and evaluating clays suitable for the production of lightweight aggregate is presented. The procedures to be used with both the laboratory furnace and the pilot‐plant rotary kiln are outlined, and the determinations and tests necessary for relative comparisons of the products are describe

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1949.tb18966.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractJust as the properties of titania enamels are influenced by the clay used as the suspending agent in slip preparation, so it was thought that the salts used as electrolytes might also have effects of a similar nature. Six salts, KCl, K2CO3, NaAlO2, NaNO2, MgCO3, and KNO3, more or less commonly used as electrolytes for setting up titania enamels, were employed singly and in combinations of two and three in the preparation of 25 slips made from a standard frit. The clay content was 4%, and the milling conditions were constant. Slips, therefore, that varied in electrolyte content only were sprayed on ground‐coated steel plates, which were then fired uniformly. The set of the slips was determined by means of the Irwin slump test and the Brookfield viscometer. The reflectance, color value, finish, and acid resistance of the enamels were found by standard methods. The results showed that electrolytes have much more effect on enamel properties than has commonly been supposed and that, in the preparation of enamels, not only the quality of the frit but the properties of the components of the mill addition, clay and electrolyte alike, merit careful consideration in order to achieve the best possible result

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1949.tb18967.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY