“…That simple air-oxidation of a titanous solution is not dependable is shown by McNabb and Skolnik (7). Their results corroborate the experience of Margaret D. Foster of this laboratory, who found that in a solution containing titanous salt equivalent to 0.04 gram of titanium dioxide less than three fourths of the titanium was reoxidized to the quadrivalent state after 10 hours of aeration; a solution containing 0.09 gram of titanium dioxide was less than nine-tenths converted in the same time.…”