1 河東カオリン, 川俣長石, 四條畷珪石及磁器素地上1種を約100℃おきに600-1300℃で2時間加熱し, 100℃, 常壓, 20%鹽酸に對する溶解度の變化を求め, 別にカオリン-長石-珪石系に屬する24種の配合物をSK19まで燒成し, ガラス質を生成せる15種に就て耐酸度を測定し, 各結果の相關關係を考察した。
2 カオリン加熱物の耐酸性は其熱化學微構造熱膨脹等の加熱效果と一致せる關係を示す。
長石及珪石は加熱に依て著しい耐酸性の變化を示さない。
1000℃までは磁器素地土の溶解曲線はカオリン, 長石及珪石の平均値に近く, 加熱效果と溶解度との關係はカオリンのやうに明瞭でない。
1100-1200℃まで加熱すれば, カオリン, 長石, 珪石及磁器素地土の溶解度には殆ど差異を見ない。
3 長石に珪石を溶解せしむる時, 珪石の増加は耐火度の上昇を來すが, 耐酸性には殆ど變化がない。
4 長石にカオリンを溶解せしむれば, 耐火度耐酸性共著しく増加する。
5 長石に珪石及カオリンを同時に溶解せしむる時, カオリンの増加は著しく耐酸性を増す, 珪石の増加も幾分有利なやうに思はれる。
終りに本研究は財團法人手島工業教育資金團の補助に依つた。爰に甚深の感謝を捧ぐる次第である。

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The authors, continuing the previous studies (This Journal, 1934, 42, 339, 471; 1935, 43, 55, 133, 263) on the fine refractory and electric insulating material “steatite”, reported the results of further comparative studies. In the following, the main points of the present communication are briefly abstracted from the original Japanese paper.
(1) Several steatite specimens were stored for 3 months, after burning, in the air of the laboratory. All samples were seen expanded, especially the samples burned from talc only or with small addition of boric acid considerably expanded. The authors assumed that this expansion was owing to the moisture and carbon dioxide in the air.
(2) To ascertain this expansion, 4 sorts of samples were put on to the hydrothermal treatment by heating in the autoclave of superheated steam of 10 atmospheric pressures and ca. 180°C for 3 hours. The samples No. 3 (talc only) and No. 4 (talc with 3% boric acid) disintegrated considerably, No. 2 (talc with 0.6% magnesium chloride) expanded, but No. 1 (talc with 3% alumina) was seen completely stable and in constant dimensions. So that, the reason of expansion was, as assumed above, clearly owing to the combination of water with the free silica of cristoballite form in the heat decomposed talc molecule, which is produced by calcining or burning talc (H₂Mg₃ Si₄O₁₂ or 3MgSiO₃·H₂SiO₃) to anhydrous matter Mg₃Si₄O₁₁ or 3MgSiO₃·SiO₂. This combination of water molecule with silica in the calcined talc and returning to talc molecule was accelerated by the hydrothermal treatment of superheated steam under high pressure, as above treated.
(3) The modified spalling test or quick cooling test was applied to the steatite specimens of various burning conditions obtained in the foregoing experiments. The spalling test was modified by one of the present authors (S. Nagai) and carried on, as follows: the small cylindrical test pieces (dia. 2cm and height 2cm) were heated at 800, 1000, 1200 or 1300C for 30 minutes and quickly dropped in the water. The compressive strength and other physical properties were compared with those before this heat treatment, and the decrease of strength were principally discussed. The second modified test was also carried on, as follows: the test pieces applied to the repetitions of the heating at 800 or 1000°C for 30 minutes and then dropping quickly into water 2 or 3 times until to the complete disintegration of the test pieces, and the decrease of strength was principally compared. In the following tables are compared the results of these spalling or heat treatment tests, by using several steatite samples from talc, “Shuganseki”, etc.
As seen from these results, the modified spalling test is suitably applicable to compare the resistibility of steatite to the quenching. The quenching temperature must be selected, (1) 1000°C or 12000°C for the test of comparing the decrease of strength over 50% by one quenching and (2) 800°C for repeated spalling test.
(4) The authors will report in their next communication several further results of studies, (1) the special steatite obtained by mixing small quantity of alumina, zinc oxide, chrome oxide, etc., (2) expansion tests of various steatite specimens, (3) electric properties, etc.

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1. There is no correct method of the surface temperature measurement yet, as it is very difficult.
2. Author propose of two new “Elongation Method” and “Surface Temperature Scale Method”, both contrived by himself.

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衞生器に用ふる標準色のサムプルを造るために6種の着色琺瑯の組成と製法とが記載されてゐる。これ等の琺瑯は亦錐6番の標準熔化衞生器 (こゝに熔化としたのは原文のVitrivus chinaをかく譯したのである。Vitrivus chinaは日本で瀬戸物といふやうに熔化支那物即ち磁器のことを意味するのであらう。譯者が見た實物は磁器素地を熔化又は磁化するまで無釉で締燒し, 後硬質陶器の如く低温度で釉燒した米國式の二度燒磁器である。以下ビトリアスチヤイナとも書く, -譯者註) の製造にも用ひらる。

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