Direktthermometrische bestimmung von thorium und lanthan in gläsern

A rapid method is described for the determination of thorium and lanthanum in non-silicate glasses. It is suitable for routine use in a works laboratory. The samples are dissolved in nitric acid. The thorium content is calculated from the measured heat of precipitation of thorium iodate, and the lanthanum content by difference from the heat of precipitation of both thorium and lanthanum oxalates together. The apparatus is calibrated by using standard solutions of the two metal ions. The standard deviations for the middle of the range (around 250 mg of the oxides) were 3·1 mg for ThO₂ and 1·7 mg for La₂O₃. An analysis takes about 1·5 hr.