58 POPULAR LECTURES AND ADDRESSES. 



of a wine-glass, when the glass, having been 

 partially filled with wine, has been shaken so as 

 to wet the inside above the general, level of the 

 surface of the liquid ; for, to explain these motions, 

 it is only necessary further to bring under con- 

 sideration, that the thin film adhering to the 

 inside of the glass must very quickly become 

 more watery than the rest on account of the 

 evaporation of the alcohol contained in it being 

 more rapid than the evaporation of the water. On 

 this matter, the author exhibited to the Section 

 a very decisive experiment. He showed that in a 

 vial partly filled with wine, no motion of the kind 

 described occurs as long as the vial is kept corked. 

 On his removing the cork, however, and withdraw- 

 ing by a tube the air saturated with vapour of the 

 wine, so that it was replaced by fresh air capable 

 of producing evaporation, a liquid film was instantly 

 seen as a horizontal ring creeping up the interior 

 of the vial, with viscid-looking pendent streams 

 descending from it like a fringe from a curtain. 

 He gave another striking illustration by pouring 

 water on a flat silver tray, previously carefully 

 cleaned from any film which could hinder the 

 water from thoroughly wetting the surface. The 

 water was about one-tenth of an inch deep. Then, 

 on a little alcohol being laid down in the middle of 

 the tray, the water immediately rushed away from 

 the middle, leaving a deep hollow there, which laid 

 the tray bare of all liquid, except an exceedingly 



