﻿762 



Dr. E. B. Ludlam on the Action of 



through a filter of purified asbestos in a Jena-glass tube which 

 could be rendered absolutely free from moisture by heating 

 in the blowpipe to a bright red heat. 



Diagram of Connexions. 



f Bfi/SSS W/RE GAUZE 

 BRASS TUB£ 



QUARTZ TU3E 



The gas then passed into the brass illuminating vessel, of 

 which the walls, in the later experiments, were gold-plated. 

 It was led in front of a window of crystalline quartz, \ mm. 

 thick, and thence into a cylindrical condenser of the type 

 described by Becker *. The illumination vessel and the 

 outer cylinder of the condenser were earthed, the axial rod 

 of the condenser was connected by protected wires to the two 

 quadrants of an electrometer, whose sensitiveness was 

 arranged so that one volt gave a deflexion of 300 mm. on the 

 scale. The electrometer case and the metal box in which it 

 was placed were connected w T ith one pole of a high-potential 

 battery whose other pole was earthed. The small battery 

 used for charging the needle, and the high-potential battery, 

 were also both enclosed in earthed metal boxes to prevent 

 possible disturbances arising from the sparking in the 

 neighbourhood. 



In the earlier experiments the condenser was made entirely 

 of brass, the insulating parts being of special glass, but later 

 brass which had been gold plated was used, and in the con- 

 cluding experiments both the cylinder and inner rod were of 

 carbon, insulated by means of fused quartz. 



From the condenser the gas passed into a gas meter of 



* Zeitschr.fiir Instmmentenkunde, vol. xxix. p. 258 (1909). 



