Sandever

from 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]