POWDER DISPERSIBILITY Table I Powder Samples Used No. Sample Remarks 337 1 Carbon black Channel type 2 Iron oxide (A) a-FeO OH, ochre 3 Iron oxide (B) Fe•O4, black 4 Iron oxide (C) a-Fe2Oa, red 5 Iron oxide (D) •-Fe20•, dark red 6 Iron oxide (E) (Fe•O:s), brown 7 Titanium dioxide (A) Rutile type 8 Titanium dioxide (B) Rutile type 9 Titanium dioxide (C) Anatase type 10 Colloidal kaolin ... 11 Mica .. ß 12 Tale (A) Manchurian 13 Tale (B) Manchurian 14 Zinc oxide (A) ... 15 Zinc oxide (B) ... 16 Zinc oxide (C) ... 17 Calcium carbonate Precipitated 18 Lake Red C Ba salt 19 Permanent Orange ... 20 Zinc laurate . ß. Table II Influence of Temperature and Ti•ne of Preliminary Treatment on S•.., and Smo of Titanium Dioxide (A) Sm, (Il12/g) Temperature Time (hours) (øC) I 2 a 6 25 9.2 9.0 9.3 9.5 100 10.1 10.2 10.0 10.0 200 11.0 10.7 11.0 11.3 10 11.6 Sn2o (tn2/g) Time (hours) Temperature (oc) i 2 3 5 lO 25 lO.1 lO.1 11.8 lO.3 11.7 lOO 15.1 15.3 16.3 16.1 15.4 200 16.7 16.2 16.9 16.7 16.4 was measured at -196øC volumetrically and Sn=o at 25øC gravimetrically.

338 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table IIi SN2, Smo, and Smo/SN•of Powder Samples Sample Carbon black Iron oxide (A) Iron oxide (B) Iron oxide (C) Iron oxide (D) Iron oxide (E) Titanium dioxide (A) Titanium dioxide (B) Titanium dioxide (C) Colloidal kaolin Mica Talc (A) Talc (B) Zinc oxide (A) Zinc oxide (B) Zinc oxide (C) Calcium carbonate Lake Red C Permanent Orange Zinc laurate 215.8 25.3 16.3 12.6 10.3 2.3 10.1 11.2 8.9 11.3 86 74 4 1 48 44 36 32 67.0 9.8 3.6 97.7 25.1 19.2 9.0 7.2 2.5 15.1 13.3 9.0 17.0 12.0 4.9 2.3 4.5 3.0 2.0 4.3 18.6 0.9 2.8 0 45 0 99 1 18 0 71 0 70 1 o9 1 5o 1:19 1.01 1.5o 1.40 O. 66 O. 56 O. 94 0.68 O. 56 1.34 O. 28 O. 09 O. 78 Measurements of Ss2 and SH2o were repeated three times and the mean values are shown. vapor supposedly takes place only on the hydrophilic part of the powder surface. Therefore, the ratio of specific surface area of adsorption of water vapor to that of nitrogen may be used to estimate the hydro- philicity of the powder (2). In this experiment, we used the improved version of Sibata's surface area measuring apparatus. ©* SN• was measured volumetrically and Smo, õravimetrically. Before measurement, the sample was deaerated at 100 ø + 5 øC and 10 -4 mm of Hg for 1 hour to remove water and gases adsorbed on the sample. However, Lake Red C, Permanent Orange, zinc laurate, iron oxide, etc., were deaerated at room temperature (25 øC) for 11• hours, since these were susceptible to discoloration, de- formation of grain, and change in surface state if treated at around 100 øC. An experiment was carried out using titanium dioxide (A) to check the influence of temperature and time of preliminary treatment in a high vacuum at 10 -4 mm of Hõ on SN, and Smo. Table II shows the results of this experiment. * Sibata Chemical App. Mfg. Co., Ltd., 3-1-25, Ikenohata, Daito-Ku, Tokyo, Japan.