The Collaborative International Dictionary of English v.0.48:

Emmantle \Em*man"tle\, v. t. [Pref. em- (L. in) + mantle: cf. F.
   emmanteler. Cf. Inmantle.]
   To cover over with, or as with, a mantle; to put about as a
   protection. [Obs.] --Holland.
   [1913 Webster]