The Collaborative International Dictionary of English v.0.48:
Admix \Ad*mix"\, v. t. [Pref. ad- + mix: cf. L. admixtus, p. p. of admiscere. See Mix.] To mingle with something else; to mix. [R.] [1913 Webster]WordNet (r) 3.0 (2006):
admix v 1: mix or blend; "Hyaline casts were admixed with neutrophils"