Selenium Black Glass

A black glass was made by melting a soda-lime-silica glass under a reducing atmosphere with the addition of 0.6% of selenium and 0.1% of cobalt carbonate, CoCO3. The light absorption of a specimen about 0.01 inch thick in the range of 400 to 750mu was superior to that of commercial black glass. The maximum transmission was 27% at 750mu. The use of nickel and iron oxides is less effective than cobalt oxide for obtaining selenium black glass.