POWDER DISPERSIBILITY 345 Table VI Results of Evaluation o[ Dispersion State and Sedimentation Volume o[ Powder Samples Evaluation Point Sedimentation Sample of Disperion State Volume (cc) -- Carbon black 1 8.5 Iron oxide (A) 5 17.0 Iron oxide (B) 1 2.7 Iron oxide (C) 1 7.0 Iron oxide (D) 1 3.8 Iron oxide (E) 1 3.2 Titanium dioxide (A) 1 4.2 Titanium dioxide (B) 1 4.2 Titanium dioxide (C) 5 4.0 Colloidal kaolin 8 1.2 Mica 3 4.0 Talc (A) 5 1.5 Talc (B) 4 I. 3 Zinc oxide (A) 2 11.2 Zinc oxide (B) 2 11.9 Zinc oxide (C) 2 13.0 Calcium carbonate 3 3.8 Lake Red C 7 2.6 Permanent Orange 4 6.4 Zinc laurate 1 ... the investigation made by Zettlemoyer et al. (3) on the correlations of S•2, Smo, and Smo/S•2 to the silica content of titanium dioxide of the rutile type. As can be seen from this table, the ratio Smo/SN•of titanium dioxide becomes larger than 1.0 with the increase of silica con- tent. On the other hand, water vapor adsorption is different from ni- trogen gas adsorption it is a physical adsorption accompanied in some cases by a chemical adsorption. For these reasons, the ratio Smo/S• sometimes exceeds the theoretical limit of 1.0. Samples having Smo/SN2 larger than about 1.0 are titanium dioxide (A), titanium dioxide (B), titanium dioxide (C), iron oxide (A), iron oxide (B), iron oxide (E), colloidal kaolin, mica, and calcium carbonate. Those having SmO/SN, from 0.5 to 1.0 are iron oxide (C), iron oxide (D), talc (A), talc (B), zinc oxide (A), zinc oxide (B), zinc oxide (C), and zinc laurate. Those having Smo/SN• smaller than 0.5 are carbon black. Lake Red C, and Permanent Orange.

346 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Correlation of Various Factors to Dispersion State and Sedimentation Volume Correlations between the dispersion state and final sedimentation volume, on the one hand, and the ratio Smo/SN2, mean particle size, specific gravity, and •'-potential of the powder, on the other hand, were studied. Correlation coefficients are given in Table X. Table VII Absorption Water Volume and Degree of Wetting Degree of Wetting Water Powder Water Absorption • • Mean Sample (cc/g) Water Powder Value Carbon black 6.9 2 2-3 2 Iron oxide (A) 4.2 3 3-4 3 Iron oxide (B) 0.6 5 4-5 5 Iron oxide (C) 1.3 4 4-5 4 Iron oxide (D) 1.0 4 4-5 4 Iron oxide (E) 0.6 4 3 4 Titanium dioxide (A) 0.8 5 5 5 Titanium dioxide (B) 0.9 4 4 4 Titanium dioxide (C) 1.4 5 4-5 5 Colloidal kaolin 0.7 5 4-5 5 Mica 1.6 4 4 4 Talc (A) 1.1 1 2-3 2 Talc (B) 1.0 1 1-2 1 Zinc oxide (A) 1.9 4 3-4 4 Zinc oxide (B) 1.9 4 2-3 3 Zinc oxide (C) 1.9 4 3-4 4 Calcimn carbonate 1.6 3 5 4 Lake Red C ... 1 1 1 Permanent Orange ... 1 1 1 Zinc laurate ... 1 1 1 Table VIII Results of Analysis of Titanium Dioxide (A) and Titanium Dioxide (C) Titanium Dioxide (A) Titanium Dioxide (C) Rutile Type TiO,, 94.7% A12Oo 1.69 % SiO2 1.11 • ZnO 1.02% Ti20:• 0.3% Anatase Type TiO2 99% Ti•O• 0.27%