1048 



than had ever been fonnd. Photographs of discharges through 

 flowing ammonia-gas confirmed the spectral part of the investigation 

 of this system. For a more detailed discussion of the obtained results 

 in connexion with the well-known theoretical considerations of J. 

 Franck and G. Hertz and J. Stark we must refer to our dissertation. 

 Some points, both photographic and spectral, will be further dis- 

 cussed in a later paper of the author. 



The author gladly accepts this occasion to express his gratitude 

 to Dr. G. L. F. Philips who kindly enabled him to make this 

 investigation and also his great indebtedness to Prof. W. Reinders 

 and Prof. L. H. Siertsema for their helpful interest in the work 

 and the preparation of the writer's dissertation, from which this 

 short paper is extracted. 



Eindhoven. Laboratory of the N. V. 



. PIdlips's Incandescent-lamp- factory. 



