circulation (n.)

mid-15c., in alchemy, "process of changing something from one element into another," from Middle French circulation or directly from Latin circulationem (nominative circulatio), noun of action from past participle stem of circulare "to form a circle," from circulus "small ring" (see circle (n.)).

Of blood, "act of moving so that it returns and begins again," first by William Harvey, 1620s. Meaning "act or state of being distributed" is from 1680s; that of "extent to which a thing circulates" (of periodical publications) is from 1847.