J06B 



sÜlcales e.g. with glass in pulverous state instead of with phosphorus, 

 the same action may be attained with greater security. The silicates 

 may be applied in the same way as the phosphorus. 



Several kinds of glass can be used e.g. Bohemian glass, Jena, 

 Thuringian-, lead-glass etc. In table I the analyses of some of the 

 kinds of glass that were used are given. 



TABLE 1. 



B. Closer investigations. 



What is the explanation of the action of these silicates? In order 

 to learn something about this the reaction between II' and glass 

 in the glow-lamp was investigated. The first experiment that suggested 

 itself was the following: Take a tungsten lauip with a thick wire 

 and cover it not with glass powder, but with a glass capillary. In 

 this way we have to do with much greater quantities of reacting 

 substances than in the case of the lamp "sprayed" with glass powder. 



As a precaution we burn the lamp for the first time under a low voltage, while 

 the evacuated lamp was still connected with the pump. This should be done very 

 carefully. The wire had to be exactly horizontal, in order that an eventual drip- 

 ping down of the molten glass might be avoided When by means of the electric 

 current the wire was kept at a temperature of about 600°, all gases absorbed in 

 the glass capillary could be removed in this way. 



This process was continued until a high vacuum was kept constant during a 

 long time. Only then the lamp was separated from the pump. 



When high tension is applied to this lamp, while the wires are 

 horizontal (see above), the glass begins so to say to boil and 



