A SPECTROPHOTOMBTRIC L'DY OF FLUORESCENCE. 



23 



sharp! the white J orite. The broadening of the band 



upon this side may result in a sligh hifting of the fluorescence. It has 

 already been shown by 1 . Knoblauch- that fluorescent 



substances such I naphtha n-roth have the position of the fluo- 



trum shifted by dis them in different liquids; and that 



theshift 1 Is with that of th< (sorption band previously described 



by Kundt. 3 



This sub ' typical of his second class, 



the characterise which an cence spectrum independent of 



the wave-length of th< 1 an absorption band beginning 



.it th.it point in th< rum at wh first trace- of fluorescence shows 





W 



fin hor se chestnut). 



Curv. I 



trn when li^ht. 



1 111 thick. 





itsib and extending ird the viole so that there is no overlapping of 



the baud oi' the 1 xciting light with tin- uor< jcence spectrum. 



Our measurements of the fluoi of aesculin were made upon a 



solution consisting of water in whiebfreshly broken twigs of the horse- 

 chestnut tree had been immersed. W n freshly prepared this shows the 

 well-known fluorescence characterise ulin, but the solution loses 



its activity upon standing. We w< ble to procure pure aesculin, but 



the results. -., far .i- the form and a position of the fluorescence curve 

 are concerned, would probably la- the ime had measurements been made 

 upon the solution of the chemically pr>ared substance. The fluorescence 

 curve, Fig. 21, is of the usual form ad its position with reference to the 



vr. Wic<l Ann . j8, p. 201. 

 oblaucb, Wied. Ann . s4. p. 193. 



Kundt. Wied. Ann.. 4, p. 34, 1878. 

 I.ommel, PoggendorfT's Ann., 143, p. 38. 



