Thorium nitrate is more readily extracted by dibutyl butyl phosphonate (DBP) than by tri- n-butyl phosphate (TBP). It is extracted as a tri-solvete and the reaction may be represented by the equation Th( NO 3) 3++3 NO 3′+3 DBP= Th( NO 3) 4·3 DBP The distribution of thorium to the organic phase is approximately halved when nitrobenzene is substituted for kerosene as a solvent for the reagent, but in either case the reaction is represented by the equation given.