The Encyclopedia Americana (1920)/Elective Affinity

ELECTIVE AFFINITY, a term formerly used in chemistry, in connection with the supposed fact that when a given chemical substance is mixed with two or more others with which it is capable of combining, it will exhibit a preferential affinity for one of them, and combine with that to the exclusion of the others. This view of chemical action is now known to be incorrect. See Equilibrium, Chemical.