IN a former letter to NATURE (January 20, p. 79) we announced the discovery of a new element with atomic number 72, for which the name hafnium was proposed. Evidence was given that this element is ...

IN a previous letter (NATURE, March 10, p. 322) we have shown that the optical spectrum of the new element hafnium, of atomic number 72, which was discovered a short time ago by Coster and Hevesy ...