摘要:

AbstractThe mechanisms of viscous flow and of electrolytic conduction in liquids have been examined to show the significance of the activation energy which is evaluated from the temperature coefficients of viscosity and electrical resistivity. It is shown that the high numerical values characteristic of silicate glasses arise from the ionic character of the liquid, the small coordination number (4) for silicon, and the high electric charge on the ions (Si, 4; 0,2; etc.). Below the softening range, a glass is not necessarily stabilized (i.e., in equilibrium with respect to molecular association or dissociation processes) and its properties depend on its history, mechanical, thermal, etc. In stabilized glasses, the activation energies for viscosity and electric resistivity rise continually with falling temperatures, showing no maximum, in contrast to the views of Preston and Seddon.The oxygen, to silicon ratio has a dominating rôle in the structure of silicate crystals, as shown by W. L. Bragg. Similar concepts are applied to glass, and it is shown that the Preston‐Seddon proposal of definite compounds in soda‐silica glasses may be replaced by an alternate explanation.The quantity, β, in the equation, η=arβ, which relates viscosity to resistivity, has a value of 4 to 6 for certain soda‐containing glasses. The suggestion is made that viscous shear requires the breaking of four to six times as many sodium‐oxygen bonds as does electrical conduction.Finally, an internal energy‐temperature curve, based on specific‐heat data for fused silica, has been constructed. The curve shows a. steady rise with increasing temperature. It is typical of

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19418.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractNine commercial glasses were electrodialyzed, and the results were compared with those obtained by the American Ceramic Society No. 1 powder method. Data showing the rates at which bases were released have been included.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19419.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractThe fiber method developed by Schwalbe, Badger, and Silverman for comparing the tensile strengths of glasses was used to compare the tensile strengths of sheet‐iron ground‐coat enamel glasses whose feldspar, borax, and quartz contents varied within workable limits. For purposes of comparison, this method uses that value of the unit stress at failure which exists in a fiber whose fractured surface shows a smooth portion constituting 1% of the total cross‐section. For the enamels tested, these values of tensile strength ranged from 30.0 to 32.7 kg. per sq. mm. (42,000 to 46,000 lb. per sq. in.). An increase in quartz or feldspar tended to raise the tensile strength slightly, while an increase in borax tended to lower it slightly, although the total variation was small. From these data, it was concluded that insofar as the enamel strength was concerned mechanical failures of the enamel, such as chipping, fishscaling, or crazing, could not be aided by variations of the feldspar, borax, and quartz contents of sheet‐iron ground‐coat enamel glasses within workab

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19420.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractA Kentucky ball clay and a Georgia kaolin were resolved into seven practically monodisperse fractions, ranging from 0.2 to 20.0 microns in mean size. The distribution of sizes and the physical characteristics of the fractions were determined to place the fractions on a comparable basis. Plasticity, drying shrinkage, and dry strength measurements were made on the fractions. There was no definite relationship between drying shrinkage and particle size, but, in general, the drying shrinkage increased with decreasing particle size. The drying shrinkage measurements, however, afforded a means for computing the thickness of water films at the maximum plasticity developed. This computed thickness was between 90 and 160 Angstrom units at maximum plasticity. The dry strength increased up to a certain limit in direct relation with increased area of surface or decreased particle size. The optimum plasticity value, taken as the product of yield and strain, increased with increasing surface area according to the relation.LogS = AP + B.WhereS= surface available per 100 g. clay.P= plasticity.AandB= constants.The constant,B, is equal to 180 × 104for the kaolinite used in this investigation. This means that there must be more than 180 × 104square centimeters of total surface per 100 grams of clay on the basis of platelike particles before the material will exhibit plasticity. This surface represents a monodisperse system of particles approximately 2 microns in diameter; systems containing particles more than 2 microns in diameter exhibit the Osborne‐Reynolds close‐packing e

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19421.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractA method for the direct determination of sodium oxide in feldspars is described. Data derived from an investigation conducted to determine the optimum conditions for the accurate estimation of this alkali metal by the prescribed procedure are tabulated and the results are discussed. The application of the method to the analysis of other related silicates is mentioned briefly.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19422.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractThe potentiometric titration of 8‐hydrOxyquinoline and the metallic inner complexes,i.e., magnesium oxyquinolate, is described, using direct titration with a standard bromate solution of the hydrochloric acid solution of the hydroxyquinoline or its derivatives with particular reference to magnesium oxyquinolate. Potentiometric procedures for direct determination have been developed using the electrode system, platinum‐nickel. This procedure involves the use of the monometallic, platinum‐platinum electrode pair and the electron beam sectrometer as the recording instrument, which has a distinct advantage of speed and equal accuracy over previous electrometric titrations. A series of experimental analyses has been carried out both on the hydroxyquinoline and its magnesium salt. The procedure is well adapted to routine plant control analyses, and a separation of calcium prior to the determination of magnesium is not req

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19423.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractThe fundamental properties of nepheline syenite, such as thermal expansion and fusion characteristics, are given. Test specimens of twelve bodies, comprising various flux combinations of nepheline syenites and potash feldspars with talc, whiting, magnesium carbonate, and pyrophyllite, were fired to seven different cones. The firing linear shrinkage curves of combinations of nepheline syenite with the. various materials are somewhat similar to such combinations with potash feldspar except that the syenite combinations are active at lower temperatures. That the sintering ranges of nepheline syenites are longer than those of potash feldspar is explained thermochemically.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19424.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractBy introducing nepheline syenite in sanitary porcelain in reduced amounts to replace potash feldspar,alonger vitrification range is afforded which results in less warpage.Ware fluxed with nepheline syenite has a steel‐like ring, the pitch being higher than the regular ware. An electrical machine for producing pure tones was used to classify the various pitches. An oscillograph was used to determine decrement or tone decay. Nepheline syenite, ground to near pottery‐grade fineness, was air‐separated into coarse, medium, and fine divisions. When used in a porcelain body, the fine division afforded a longer vitrification range, lower warpage, and increased mechanical strength. The sound properties of these bodies are classified. Photomicrographs of body structures are inc

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19425.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractThe expansion of chrome ore‐magnesite mixtures is attributed to the solid solution of magnesia in the spinel component of the ore. This conclusion is substantiated by measurements of the density, index of refraction, and lattice width, before and after exposure to magnesi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19426.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY

摘要:

AbstractThe results of using lithium carbonate to replace the more soluble alkalis and their frits in glazes fired between cones 07 and 05 are discussed. Owing to its unusual fluxing properties, the use of from 9 to 12% lithium carbonate permits a marked increase in the amounts of alumina, calcium, and silica which may be used, resulting in a more stable glaze, with sufficient alkalinity to produce vivid copper blues and other typically alkaline colors.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1939.tb19427.x

出版商:Blackwell Publishing Ltd    

年代:1939

数据来源: WILEY