Abstract :
A purification technique developed at the U.S. National Bureau of Standards may produce the purest materials ever obtained. The technique appears to have most of the desirable features of conventional purification procedures but avoids the disadvantages associated with each. Impurity is reduced by a factor as great as 104 in each stage of operation, and since it is believed that any number of stages may be employed with the same degree of improvement and no recontamination, the process may be able to produce absolutely perfect crystals.
