Thorium Arsenates

Thorium hydrogen arsenate,Th(HAsO₄)₂.6H₂O, is precipitated in a crystalline form when a 40 per cent, solution of arsenic acid is added to a boiling solution of thorium nitrate containing 2 per cent, of thoria. Thorium dihydrogen arsenate, Th(H₂AsO₄)₄.4H₂O, is obtained as a crystalline precipitate when a solution of thorium nitrate containing 5 per cent, of thoria is treated with a 50 per cent, solution of arsenic acid.