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Pyrex glass formula patent No. 1,304,623 - Page 4 Home  > Insulators  > Patents  > Page 4

1,304,623: 4 of 4

5. A glass containing not under 76 per cent. silica and also containing boric oxid, the boric oxid comprising not less than 60 per cent. of ingredients other than silica.     6. A glass having the stability better than 0.002 grams per 100 sq. cm. and a hardness no greater than 900° C. and containing not under 76 per cent. silica and also containing boric oxid, the boric oxid comprising not less than 60 per cent. of ingredients other than silica.     7. A glass containing between 76 and 90 per cent. silica; between 6 and 14 per cent. boric oxid, and also containing sodium oxid and alumina.     8. A glass containing silica, boric oxid and alkali, the boric oxid and alkali forming not less than 6 per cent. of the glass, the glass having linear co-efficient of expansion less than .0000036.     9. A glass containing silica, boric oxid and alkali, the boric oxid and alkali forming not less than 6 per cent. of the glass, and the boric oxid being to the alkali in the ratio of at least two to one, the glass having a linear co-efficient of expansion of less than .0000036.     10. A glass containing silica, boric oxid and alkali without oxids of the second group of the periodic system, or the reducible oxids of lead or antimony, the boric oxid and alkali forming not less than 6 per cent. of the glass, the glass having linear co-efficient of expansion of less than .000004.     11. A transparent glass containing over 70 per cent. silica, and having a linear co-efficient of expansion of less than .0000036 and a hardness not greater than 800° C.     12. A transparent glass containing more than 79 per cent. silica and having a linear co-efficient of expansion less than .000004, and a hardness not greater than 850° C.     13. A glass having a hardness not greater than 850° C.; a co-efficient of thermal endurance (F/3) greater than six, and stability of 0.002 g. or better per 100 sq. cm.     14. A glass having a hardness not greater than 850° C., a linear co-efficient of expansion of less than .0000036, and thermal co-efficient of endurance (F/3) greater than six.     15. A glass having linear expansivity less than 0.000004, stability better than 0.002 grams per 100 sq. cm. and hardness not greater than 850° C.

16. A glass containing silica and boric oxid and having a linear expansivity less than 0.000004 and stability better than 0.002 grams per 100 sq. cm.     17. A glass having hardness not greater than 820° C. and linear expansivity less than .0000036.     18. A glass having a hardness not greater than 820° C., a linear expansivity less than 0.000004, and a stability better than 0.002 grams dissolved matter per 100 sq. cm.     19. A glass containing at least 76 per cent. silica and containing at least one other acid oxid and a basic oxid, the molecular ratio of the acid oxid contents except such as are due to silica to the basic oxid contents being at least two to one.     20. A glass containing at least 76 per cent. silica and containing at least one other acid oxid and a basic oxid, the percentage ratio of the acid oxid contents except such as are due to silica to the basic oxid contents being at least two to one.     21. A glass containing silica and not more than two other acidic oxids, one of which may be alumina and only one basic oxid; the molecular ratio of the acidic oxid contents, except such as are due to silica and alumina, to the basic oxid contents being at least two to one.     22. A glass containing at least two acidic constituents and only one basic constituent, and having linear expansivity less than 0.000004.     23. A glass containing silica and not more than two other acidic constituents and only one basic oxid constituent, and having linear expansivity less than .000004.     24. A glass containing between 76 per cent. and 85 per cent. silica, over 9% of another acid oxid, and over 3% of a basic oxid.     25. A glass containing over 76 per cent. silica and having linear expansivity less than 0.000004 and hardness not greater than 820° C.     In testimony whereof we have signed our names. EUGENE C. SULLIVAN. WILLIAM C. TAYLOR.