Thorium Nitrate: Monazite Sand Opened with Sulphuric Acid, through Phosphate, Oxalate and Sulphate (Roscoe 1913)

How gas-mantle makers got thorium out of monazite sand, in outline: open the sand with hot sulphuric acid, catch thorium phosphate first with magnesia, turn it to oxalate to leave the phosphate behind, part it from cerium with soda, clean it as the sulphate, and finish as the nitrate. Result: thorium nitrate holding 48-49 % ThO2 on ignition. Source: Roscoe and Schorlemmer, A Treatise on Chemistry vol. 2 (1913), p. 832 (a general outline; the works process was secret). Not given: amounts, temperatures, times. Thorium is radioactive. Picture drawn by Youblob.