| 摘要 |
<p>579,832. Optical glass. CHANCE BROS, Ltd., BASTICK, R. E., HAMPTON, W. M., and WANG, T-H. Nov. 11, 1943, No. 18792. [Class 56] Optical glass comprises the following essential constituents within the range of proportions specified namely : Silica (Si02) - - - 10-25 per cent Barium Oxide (BaO) - 15-35 " " Boron Oxide (B2O2)- - 10-30 " " Lanthanum oxide (La203) 8-20 " " Thorium oxide (ThO2) -. 3-15 " ." Zinc oxide (ZnO) - - 2- 8 "<SB> " the amounts of lanthanum and thorium oxides together being not more than 35 per cent of the total glass composition. - Five examples are given. Lead oxide and other-alkaline earth oxides may be added provided that the total of the oxides of lead, zinc and the alkaline earth metals does not exceed 45 per cent of the glass composition. Oxides of zirconium, aluminium, and beryllium may be added to prevent crystallisation.</p> |
