Bulletin . azes. B2O3 and ALOg then function the same in high silicaglazes but function oppositely in low silica glazes. In Chart 2, the glazes are located by the molecular ratiosof silica to alumina on the abscissa and by the total oxygen ratioson the ordinate. The molecular ratio of silica to alumina isindependent of the total oxygen ratio, but the total oxygen ratiois partly dependent upon the silica-alumina ratio. Therefore,in plotting glaze groups similar to Chart 2, the evidence pre-sented is influenced by one dependent and one independentvariable. This must be borne in mind in drawing c
Bulletin . azes. B2O3 and ALOg then function the same in high silicaglazes but function oppositely in low silica glazes. In Chart 2, the glazes are located by the molecular ratiosof silica to alumina on the abscissa and by the total oxygen ratioson the ordinate. The molecular ratio of silica to alumina isindependent of the total oxygen ratio, but the total oxygen ratiois partly dependent upon the silica-alumina ratio. Therefore,in plotting glaze groups similar to Chart 2, the evidence pre-sented is influenced by one dependent and one independentvariable. This must be borne in mind in drawing conclusions,otherwise they may be misleading. The underfired mattes occur at i, crazed mattes at 2, soundmattes at 3, semi-mattes at 4, crazed brights at 5, sound brightsat 6, and glazes which are crazed and devitrified at 7. The lineA B is the high gloss axis. Opalescence and the Function of B2O3 in the Glaze, Trans. A. C. S., Vol. 12, to 137. INFLUENCES OF SILICA AND ALUMINA ON PORCELAIN GLAZES. 2 I. NKvciCi^S^^ V~^~~V^ CK tr; r\j cvi s M <3 2 2 IXFLUENCES OF SILICA AND ALUMINA OX PORCELAIX GLAZES. The chart shows graphically that the matte glazes fall withinnarrow limits and that the bright glazes occur within wide the following table is given the ratio limits within which thedifferent kinds occur: Si02 : AI0O3 0. R. 0 •9- -I . 0 .6- -I I •4- -I . I ?9- -2 I 4- -4- 2 I- -4- 4 •5- -7- 1. Underfired matte glazes (at cone 11). . 2. Crazed matte glazes (at cone 11) 3. Sound glazes (at cone 11) 4. Semi-matte glazes (at cone 11) 5. Crazed bright glazes (at cone 11) 6. Sound bright glazes (at cone 11) 7. Crazed devitrified glazes (at cone 11)... 1. /- The trials show that the best bright glazes are found be-tween oxygen ratios of and and silica-alumina ratios of7 and The best mattes occur between O. of and silica-alumina ratios of and The high fire matteglazes given b
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