485 



<^ii^^:^^^^ 



Fig. 344. 



Fig. 'MX 



Fig. 346. 



Fig. 28. T\pes of (.eissler tiiljcs. Iilltd witli gas at low picssuic. Fhey 

 luminesce in \arioiis colors when cleciiit iinicni from an inllnence machine 

 or inductit)ii coil is passed through the lubes. From O. Lehman Die Elek- 

 Irische Lirlilcis( hciinni^j^cii odcr /•'.iilhi(liiii;^(ii (Halle a. .S., 1898). 



