The Collaborative International Dictionary of English v.0.48:

Sandiver \San"di*ver\, n. [Perh. fr. OF. sa["i]n grease, fat +
   de of + verre glass (cf. Saim), or fr. F. sel de verre
   sandiver.]
   A whitish substance which is cast up, as a scum, from the
   materials of glass in fusion, and, floating on the top, is
   skimmed off; -- called also glass gall. [Formerly written
   also sandever.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sandever \San"de*ver\, n.
   See Sandiver. [Obs.]
   [1913 Webster]