The solubility limits of lanthanum, praseodymium, neodymium,
samarium, gadolinium, dysprosium, europium, ytterbium, lutetium,
and yttrium hydroxides in various concentrations of sea water have
been determined by tyndallometric and pH measurements. By a
simple graphical method the solubility and hydrolysis constants
have been evaluated from the solubility limits represented in the
general precipitation diagrams, in which the ordinate is pH and
the abscissa is the logarithm of the metal concentration. The precipitation pH values (4.70 to 5.49) and the values of the solubility
products (log Kso = - 28.4 to - 26.2) obtained for the rare earths
in various concentrations of sea water, indicate that \u27lanthanides
in the acid range in sea water, at lanthanide salt concentrations
greater than 10- 4 M, form compounds other than rare earth
hydroxides
