THE ABSORPTION SPECTRA OF SOLUTIONS. 



The question as to whether the fluorescence of a gas or liquid influences 

 its conductivity has in general been answered in the negative. Nichols and 

 Merritt 1 reported that the conductivity of an alcoholic solution of eosin was 

 increased when the solution was caused to fluoresce. Carmichel 2 and Regner 3 

 found no such effect, while Hodge 4 and Goldman 5 have shown that the effect 

 found by Nichols and Merritt was due to an electromotive force produced 

 by the light at the electrodes of the cell. Howe 6 finds that if the fluorescence 

 of anthracene increases the conductivity, the increase is too small to measure. 

 Wood could detect no increase in the conductivity of sodium vapor when it 

 was caused to fluoresce. 



On the other hand, Nichols and Merritt 7 believe that in the case of the 

 fluorescence of solutions of fluorescein, the emission center may be the ion, 

 although they have examined the effect of change of concentration upon the 

 absorption spectrum of eosin and find very little effect. The absorption curve 

 is steep towards the red, and gradual towards the violet. The fluorescent 

 curve slopes in the opposite manner. Their work indicates that the molecules 

 and ions seem to behave in much the same way in absorption phenomena. 

 The same writers* have investigated the problem as to whether the fluorescence 

 excited per unit of absorbed energy is constant for all wave-lengths. Confin- 

 ing the range of absorption to that of a single band, they conclude that the 

 light near the red side of the band is more effective in producing fluorescence 

 than that lying on the violet side; and the change in specific exciting power 

 in passing along the band is continuous, without any indication of anything 

 selective in the neighborhood of the region of maximum absorption. 



THE CARRIERS OF CANAL-RAY SPECTRA. 



A large number of investigations have been made on the spectra produced 

 by canal rays. In the earlier work Stark was of the opinion that the renewal 

 of energy to a vibrating atom took place at the moment of collision between 

 the radiating atom and some other moving part; and the smaller the mass of 

 the particle collided with, the more efficient it would be in exciting vibrations 

 inside the atom, since the velocity of the small particle is greater and the time 

 occupied by a collision would be shorter. Continuous radiation of energy by 

 an atom moving with a comparatively small velocity would only be made 



'Phys. Rev., 19,296 (1904). 



2 Jour, de Phys. ; 4, 873 (1905). 



3 Phys. Zeit., 4,862 (1903). 



4 Ibid., 28, 25 (1908). 



5 Ann. d. Phys., 27, 332 (1908). 



6 Phys. Rev., 30, 453 (1910). 



7 Ibid., 31, 376 (1910). 



8 Ibid., 381 (1910). 



