| http://www.w3.org/ns/prov#value | - eight ZnO 20-25 MO 25-40 B 0 25-45 K 0 6.7-13.4 Na O 3.3-6.7 where MO is a substance selected from the group consisting of BaO', SrO and mixtures thereof, and wherein the ratio of K O/Na O is approximately 2/ 1, the ratio of MO/ZnO is between about 1.25/1 and about 2/ 1, and the ratio R/B O is between about 1/1 to about 2.4/ 1, UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,00
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