amphigen

from The Collaborative International Dictionary of English v.0.48

Amphigen \Am"phi*gen\, n. [Gr. 'amfi` + -gen: cf. F.
   amphig[`e]ne.] (Chem.)
   An element that in combination produces amphid salt; --
   applied by Berzelius to oxygen, sulphur, selenium, and
   tellurium. [R.]
   [1913 Webster]