This report is continued from the last report in which a metallic powder or reducing salt has been added to glass batches containing iron oxide and melted.
(a) Glass melted by adding aluminium powder to a base glass batch in such proportions as 0.1, 0.5, 1.0%.
(b) Glass melted by adding aluminium powder to a base glass batch in which 1% of lime has been replaced by iron oxide, in such proportions as 0.1, 0.5, and 1.0%.
The transmission curves of these glasses have been measured. The shortest wave length that transmits them is in general reduced as the amount of aluminium powder added is increased, and the colour of the glass becomes greyish, accordingly a total transmission becomes smaller.
(c) Glass melted by adding to a base glass batch some stannous chloride in such proportions as 1, 4 and 8%.
(d) Glass melted by adding stannous chloride to a bese glass in which 1% of lime has been replaced by iron oxide, in such proportions as 1, 2, 4, 6 and 8%.
The transmission curves of these glasses have been measured. It has been found that the limit of wave length that transmits these glasses tends to shift toward short wave length as the amount of stannous chloride added increases, while the wave length that shows a maximum transmission tends to shift toward the blue in spectrum. These transmission curves intersect somewhere between 480 and 520.
As a result of this study it is found that the color of the glasses will be yellowish as the amount of zinc, magnesium added is increased. This seems to be that it must have reduced to colloidal iron rather than ferrous oxide. Aluminium turns to greyish while stannous chloride becomes bluish which is the color presented by ferrous oxide. In either case the amount of ferrous oxide is increased and that of ferric oxide is reduced in the glass.