The Collaborative International Dictionary of English v.0.48:

Excamb \Ex*camb"\, Excambie \Ex*cam"bie\, v. t. [LL. excambiare,
   excambire; L. ex out + cambire. See Change, and cf.
   Exchange.] (Scots Law)
   To exchange; -- used with reference to transfers of land.
   Excambion