1. 1R. C. Benner, and H. N. Baumann , "Refractory Material," U. S. Pat. 2,118,143, May 24, 1938 ;" Ceram. Abs., 17 [8 ] 1938 (1938 ).
2. 2J. W. Mellor , Comprehensive Treatise of Inorganic and Theoretical Chemistry, Vol. V , p.102 . Longmans, Green & Co., London, 1924, x + 1004 pp.; Ceram. Abs., 4 [2] 47 (1925).
3. THE SYSTEM Na2O-B2O3I Preparation of Crystalline B2O3and Some of Its Physical Properties