THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE, 



[FIFTH SERIES.] / FEB 12 I 89 / 



FEBRUAR Y 1897. 



£=s^->* 



XIII. The Spectra of Argon. 

 By John Trowbridge and Theodore William Richards*. 



IT is well known that argon possesses at least two marked 

 spectra — one ; termed the red, which is chiefly charac- 

 terized by red lines ; and another called the blue, which, as 

 its name signifies, is strongly marked by blue lines. 



In studying these spectra by means of a high-tension accu- 

 mulator, we have been led to observe carefully the electrical 

 conditions for producing them. It is obvious that a battery 

 of a large number of cells is the most suitable source for the 

 study of the discharges of electricity through gases. Espe- 

 cially is this true of a storage battery ; for the readiness with 

 which it can be charged by a dynamo, the constancy of the 

 electromotive force (about 2*1 volts per cell), the ease with 

 which it can be coupled for quantity or tension, and the 

 steadiness of the discharge afforded by it make such a battery 

 far superior to an induction-coil or to an electrical machine. 



With an induction-coil the discharge is not unidirectional, 

 and is affected by the necessary irregularities of the break. 

 These irregularities make themselves felt in a marked degree 

 when a condenser is used in the secondary circuit. The elec- 

 trical machine gives an intermittent current, and has a varying 

 capacity. The advantages of a battery for the study of the 

 discharge of electricity through gases have been pointed out 

 by Be La Rue and M tiller and by Hittorf f. These investi- 



* Communicated by the Authors. 



t Ann. der Phys. und Chem, (N. F.) vol. vii. 1S79 ; p. 553. 



Phil. Mag. S. 5. Vol. 43. No, 261. Feb. 1897. H 



