Discussion The fluoroplatinate of cerium was the only one which could not be isolated. This was to be expected, since tetravalent cerium was produced by the action of fluorine. The addition of water to the cerium product resulted in the immediate but gradually complete hydrolysis of the salt. The addition of oxalic acid to a fresh solution of the cerium fluoroplatinate precipitated all of the cerium at once, leaving the fluoroplatinate ion in ...