The precipitation of silica by tannin

The precipitation of silica by tannin from chloride solution has been examined. Precipitation was never complete, the maximum being 96 % from a solution 0.075 N in ammonia.Separations of zirconium and tin from silica in acid chloride solution and of tin from acid oxalate solution were shown to be clean only if the initial acidity was higher than 0.4 N. Separations of titanium from silica in both acid chloride and acid oxalate solution were never clean, as titanium, required a very low acidity before precipitation was complete.