THE PERISSAD LAW. BY MAJORW. H. LIVERMORE, U. S. A. G E N E R A L OUTLINE.
T h e Perissad Law may be briefly explained as follows : If t h e atomic weights of all chemical elements are arranged in a single ascending series, the law of increase is apparently irregular ; b u t almost all of these weights may be so arranged in two parallel series, that each scriea will show a regular law of increase a s far as the atomic weights have been determined, and in almost, every instance all of one series fall into those groups of classification of Mendeleyeff that indicate an even quantivalence, and almost all of the others into those indicating an uneven quantivalence. This realizes a prediction made by J l r .
