Over the past ten years, there has been considerable interest and expenditure on the recovery of ionium (thorium-230) from certain residues accumulated from the World War II uranium process at St. Louis, Missouri. Most of these efforts were reported in the classified literature. However, an unclassified report was issued recently by the Mallinckrodt Chemical Works on the plant design for ionium recovery. A review of the earlier efforts shows that consideration of ionium recovery was limited to the St. Louis residues. At that time the development of a substantial U. S. uranium ore milling industry had not yet been achieved.