Studies on Silicic Acid Gels. IV. The Effect of the Hydrogen-ion Concentration upon the Time of Set.

Studies of Silicic Acid Gels. IX. The Effect of a Change of pH upon the Time of Set of Some Acid Gels.

“…The influence of sol concentration on the flocculation values of pure ferric oxide and chromium hydroxide hydrosols has been previously reported (3, 5). With these pure sols the flocculation values decreased for monovalent ions, remained constant for divalent ions, and decreased for trivalent and tetravalent ions as the sols were diluted.…”

“…The technique employed has been reported several times in this Journal (5,2). A solution of sodium silicate equivalent to 1.26 N sodium hydroxide was obtained by dilution of "E" brand sodium silicate, prepared by the Philadelphia Quartz Company.…”

“…A recent study of the time of set of silicic acid gels, prepared from solutions of sodium silicate and acetic acid in this laboratory (5), has shown that, for mixtures of acid reaction, the time of set is proportional to the hydrogen-ion concentration. A report by Hurd, Frederick, and Haynes (2) showed a similar result when hydrochloric, nitric, or sulfuric acid was used.…”

Studies on Silicic Acid Gels. VI. Influence of Temperature and Acid upon the Time of Set.

“…In any study of the setting of silicic acid gels, the factors of temperature and hydrogen-ion concentration play a very important part. The latter has been discussed, among others, by Prasad and Hattiangadi (4) and Hurd, Raymond, and Miller (3). As the latter have pointed out, the time of set is proportional to the concentration of hydrogen ions for concentra- tions of the latter from 10-4 to 10~8.…”

Studies on Silicic Acid Gels. VII. The Effect of the Soda-Silica Ratio upon the Time of Set

“…The silicates used in this study have been described previously by Hurd, Raymond, and Miller (7). The time of set was determined always in 80-cc.…”