Application of Leo J. Novak and Joseph T. Tyree

MARTIN, Judge.

This is an appeal from a decision of the Board of Appeals of the U. S. Patent Office affirming the examiner’s rejection of claims 10, 11 and 12, all of the claims of appellants’ application, Serial No. 638,-889, filed December 3, 1956, for a patent on “Thickening and Gelling Agents.”

The following claims are representative:

“10. A thickening and gelling composition for aqueous media and which is stable in acid solutions of a carboxymethyl ether of a readily water-soluble, high molecular weight dextran, said dextran ether containing an average of from a minimum of about 0.8 to 1.5…