The chemical state of uranium in sea-water was sought from stability constants. It was estimated that uranium in sea-water existed as U(VI) and that the distribution of the chemical species in standard sea-water was: UO₂(CO₃)^4-₃ 97.9%, UO₂(OH)^-₃ 1.73%, UO₂(CO₃)^2-₂ 0.4%.
The cation-exchange ability of titanic acid was demonstrated from the fact that the pH value of NaCl solution shifted toward the acidic side by the addition of titanic acid. But, despite this cation-exchange ability, it is thought that the form in which titanic acid adsorbed uranium is probably UO₂(CO₃)^4-₃, because it was found to adsorb HCO^-₃ in quantities proportional to uranium. From the results of the present and previous studies, it is presumed that uranium is adsorbed by fhe coordinate bond.