The Factory Production of Some Special Glasses for Discharge Lamps

JSGT 1939 V23 T281-T291

The compositions of glasses suitable on the one hand for low-pressure and on the other for high-pressure mercury vapour lamps are set out and comments are made on the conditions to be observed in their preparation commercially. Low iron oxide content is essential, especially in the hard glasses for high-pressure lamps, in order to ensure high transmission of UV light. Some experiments are recorded, showing that in the case of certain borosilicate glasses the addition of 0·5% sodium chloride to the batch resulted in an appreciable reduction in iron oxide content. Experiments are also recorded on a series of glasses of stated composition containing cobalt, nickel, copper or iron oxide or their mixtures designed to transmit UV light efficiently within certain wavelength limits and as little as possible visible light. The importance of wall thickness of the lamp bulb in this connection is referred to and the methods adopted for controlling the transmission are described.

P. Staton