| 摘要 |
<p>1. A reduced coloured glass, having a conventional silico-soda-calcia matrix, that is containing principal constituents 68 to 74% of SiO2 , 0 to 5% of Al2 O3 , 6 to 15% of CaO, 0 to 6% of MgO, 11 to 15% of Na2 O and 0 to 5% of K2 O, which comprises as colouring agents iron, chromium and optionally cobalt and, owing to reducing conditions used in manufacture, sulphides in sufficient quantities to cause strong absorption of ultra-violet radiation typical of sulphide chromophore complexes of iron and alkali metals in reduced glasses called "sulphide amber", characterised in that it contains said colouring elements in the following quantities by weight : 0.18 to 0.40% of iron measured as Fe2 O3 0.08 to 0.20% of chromium measured as Cr2 O3 0.01 to 0.04% of sulphides expressed as S, and 0 to 0.015% of cobalt expressed as CoO, and in that it has, at 5 mm thickness and for illuminant C a dominant wavelength from 565 to 578 nm.</p> |
