Explanatory notes
… (lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, … heading will not therefore, for example, cover a mixture of europium and samarium nitrates with the oxalates nor a … are used in nuclear reactors for the absorption of slow neutrons. This heading excludes : (a) Natural compounds …