ABSTRACT
Dr Boltwood has not been able to separate the parent of radium from actinium by the reagent employed by me, viz. ammonium sulphide, but has found the use of sodium thiosulphate effective. As a matter of fact, author did not use the ordinary laboratory solution of ammonium sulphide, but added ammonia to the actinium solution, and then saturated it with sulphuretted hydrogen. The continual discovery of new products in very awkward positions in the radioactive series has made any simple permanent system of nomenclature impossible. Besides uranium and thorium, twenty-four distinct radio-active substances are now known to exist in radio-active minerals. The name uranium A, suggested by Mr Campbell, in itself innocuous, is open to the objection that in the case of radium, thorium, and actinium the suffix A is applied to the first product of the disintegration of the respective emanations, while no such emanation has been observed in the initial series of changes of uranium.
