302 History of Luminescence 



E. Becquerel (1861) and particularly by A. Morren (1861-1869) 

 that the effect was most marked with mixtures of gases and that 

 oxygen played an important part in the phenomenon. In his book 

 (1867: 1: 196) , E. Becquerel closed his discussion by writing: " Thus 

 this persistent temporary luminescence, that is to say this phospho- 

 rescence which is produced by oxygen or by its mixture or by its 

 combination with other bodies, is as curious as the luminous effect 

 given by the slow combustion of phosphorus." It was these obser- 

 vations which called attention to the afterglow of gases,^^ a field 

 that has played so important a part in theories of light emission. 



One of the most quoted cases Avas described by E. P. Lewis (1900) , 

 who noticed that nitrogen gas under a few millimeters pressure 

 could be " stimulated " by the electric discharge to emit a bright 

 yellow glow which continued for some time after the discharge 

 ceased. The phenomenon was further studied by Lord Rayleigh 

 (R. J. Strutt) in a series of papers beginning in 1911, who called 

 the gas " active nitrogen." The conditions for the phenomenon and 

 the spectral emission received much attention in the early twentieth 

 century. Additional knowledge of the afterglow will be found in 

 Chapter XIII on chemiluminescence. 



ELECTRODELESS DISCHARGES 



Later research led to a great variety of " vacuum tubes " for vari- 

 ous studies, including glass vessels without electrodes. Although 

 Hauksbee (1706) used electrodeless glass vessels for light effects, 

 J. J. Thomson (1891) described a special electrodeless vessel giving 

 a bright luminescence in the form of a ring when placed in a sole- 

 noid through which rapid alternating currents were passing. In 

 1893 H. Ebert and E. Wiedemann and others®^ investigated lumi- 

 nous phenomena in " electrodeless " tubes containing gas at low 

 pressure under the influence of rapidly changing electric fields be- 

 tween condenser plates. They also enclosed luminescent substances 

 in the tubes and observed the brilliant blue of Balmain's paint 

 (CaS) , the bright red of burnt magnesia, the intense blue of aescu- 

 lin, the green of anthracene, etc. In describing the method of 

 electrical excitation, H, Ebert (1894) particularly emphasized the 



Pogg. Ann. der Physik 110: 123-124, 1860, who described one of Geissler's tubes with 

 this property. 



*' Later work was carried out by E. Sarasin (1869) , A. de la Rive (1870) , E. Warburg 

 (1884) , J. J. Thomson (1891) , C. Kirn (1894) , G. Seguey (1895) , and H. F. Newall 

 (1896) . 



'* Light from electrodeless discharge tubes was also described by J. P. Gassiot (1858) , 

 J. Plucker (1862), Alvergniat (1871), E. C. Remington (1893), and O. Lehraann 

 (1892) . 



