Abstract: A new type of glass, for example for use as a TL-envelope glass which as regards phosphor poisoning and Hg penetration has better properties than the present TL-envelope glasses. Phosphor poisoning occurs in particular upon fusing electrodes and bending and severing and bridging, respectively, during the manufacture of SL and PL lamps. Phosphor poisoning is controlled by incorporating little or no Na.sub.2 O in the glass. In order to nevertheless reach good processing properties, a combination of Li.sub.2 O and K.sub.2 O is used in the glass. The addition of only Li.sub.2 O or only K.sub.2 O does not result in a suitable glass. Hg penetration is controlled by the presence of a large quantity of alkaline earth metal oxides in the glass. The glass according to the invention has a good light transmission. A lamp comprising a lamp envelope of a glass according to the invention shows only a small luminous decline during operation of the lamp.

Abstract: A new type of glass, for example for use as a TL-envelope glass which as regards phosphor poisoning and Hg penetration has better properties than the present TL-envelope glasses. Phosphor poisoning occurs in particular upon fusing electrodes and bending and severing and bridging, respectively, during the manufacture of SL and PL lamps.Phosphor poisoning is controlled by incorporating little or no Na.sub.2 O in the glass. In order to nevertheless reach good processing properties, a combination of Li.sub.2 O and K.sub.2 O is used in the glass. The addition of only Li.sub.2 O or only K.sub.2 O does not result in a suitable glass.Hg penetration is controlled by the presence of a large quantity of alkaline earth metal oxides in the glass.The glass according to the invention has a good light transmission. A lamp comprising a lamp envelope of a glass according to the invention shows only a small luminous decline during operation of the lamp.

Abstract: A quartz glass lamp vessel 1 or 21 is used in many types of lamps. Sometimes it is expedient to absorb a certain portion of the emission spectrum. In accordance with the prior art this is possible by including rare earth metal oxides in the quartz glass.The solubility of rare earth metal oxides in quartz glass is, however, limited.According to the invention, quartz glass is used which contains an alkali metal oxide and optionally, an alkaline earth metal oxide, in addition to a rare earth metal oxide. The alkali metal oxide increases the solubility of the rare earth metal oxide, so that rare earth metal oxides can be used in larger concentrations. This results in glasses which have a higher degree of absorption, from which lamp vessels can be produced.

Abstract: Doped quartz glass is produced by fusing a mixture of quartz powder with a concentrate. The concentrate consists of quartz powder and the oxides of alkaline earth metals and/or alkali metals (dopants). By adding a small quantity of dopants, a doped quartz glass can be obtained having a viscosity behavior corresponding to that of Vycor glass. Still softer glasses can be obtained by the addition of some more dopants.