The authors continued the previous studies reported already by one of the present author (S. Nagai and K. Fukai, This Journal, 1934, 42, 339, 471; 1935, 43, 55, and S. Nagai and G. Inoue, This Journal, 1935, 43, 133, 263, 343, 412) on the fine ceramics for electric insulating material “Steatite”, and reported here the results of further executed comparative results. The main points of the present communication are briefly abstracted from the original Japanese paper, as following:(1) Raw materials were further collected (This Journal, 1934, 42, 340; 1935, 43, 133), i.e., (a) 13 talc samples in Japan Proper, Korea, Manchoukuo and Shantung Peninsula of North China, (b) 8 serpentine samples in Japan Proper and Korea, and (c) 1 Shuganseki sample of bowenite or meerschaum type from Manchoukuo, and these samples were tested on their chemical compositions. The results are shown in the following table 1.Table 1 Chemical Composition of Raw MaterialsFrom these results, it was seen that all samples obtained in Japan Proper are impure, containing large amounts of alumina, iron oxide or lime, and talc samples (J)-(K) obtained from Korea, Manchoukuo and North China are suitable for the use to the present study.(2) Powder of Manchurian talc (J), or (M)-(Q) was mixed with various oxide as ZnO, Al2O3, PbO, BaO, Cr2O3 or TiO2 in amount of 5, 10 or 15%, moulded to plate (Length: 60mm, Breadth: 30mm and Thickness: 5-6mm) or cylinder (Diameter: 20mm and Hight: 25-30mm) in dry powder press by the pressure 300, 500 or 700kg/cm2, burned at 1350°, 1400° or 1450°C for several hours, and then tested comparatively for many physical propperties, e. g., (1) Burning shrinkage and weight-decrease, (2) Bending or compressive strength, (3) Porosity, (4) water absoption, (5) Specific gravity, (6) Thermal expansion and linear expansion coefficient, (7) Stability to boiling water or superheated steam under pressure of 10 atm, (8) Spalling test by quick cooling, etc. From these results, the considerable result was cbtained by adding 5% Al2O3, folloved by 10-15% ZnO, 5% BaO, 5% PbO, etc., and the addition of 5% TiO2 or Cr2O3 did not give good result.