“Thus where, by the confusion of liquids or commixture of solids, the subject produced is of a character different from that of either of its component parts, it is called a tertium quid.” John Trayner, Trayner’s Latin Maxims 598 (4th ed. 1894).
tertium quid
tertium quid (t[schwa]r-shee-[schwa]m kwid). [Latin] Scots law. A third thing that has qualities distinct from the prior two components.