50 POPULAR LECTURES AND ADDRESSES. 



the incline first in isolated drops, afterwards 

 joining together and forming narrow continuous 

 streams. 



These and other well-known phenomena, in- 

 cluding that interesting one, "tears of strong 

 wine," were described and explained in a paper 

 " On Certain Curious Motions Observable on the 

 Surfaces of Wine and other Alcoholic Liquors," 

 by my brother, Professor James Thomson, read 

 before Section A of the British Association at 

 the Glasgow meeting of 1855.* 



I find that a solution containing about 25 per 

 cent, of alcohol shows the "tears" readily and 

 well, but that they cannot at all be produced if 

 the percentage of alcohol is considerably smaller 

 or considerably greater than 25. In two of those 

 bottles the coloured solution contains respectively 

 one per cent, and 90 per cent, of alcohol, and in 

 them you see it is impossible to produce the 

 "tears"; but when I take this third bottle, in 

 which the coloured liquid contains 25 per cent, of 

 alcohol, and operate upon it, you see there the 



* See Appendix A to the present Lecture, p. 57 below. 



