The Collaborative International Dictionary of English v.0.48:

matrass \ma*trass"\, n. [F. matras; perh. so called from its
   long narrow neck; cf. OF. matras large arrow, L. materis,
   mataris, matara, a Celtic javelin, pike; of Celtic origin.]
   (Chem.)
   A round-bottomed glass flask having a long neck; a bolthead.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bolthead \Bolt"head`\, n.
   1. (Chem.) A long, straight-necked, glass vessel for chemical
      distillations; -- called also a matrass or receiver.
      [1913 Webster]

   2. The head of a bolt.
      [1913 Webster]