56 POPULAR LECTURES AND ADDRESSES. 



APPENDIX A. 



ON CERTAIN CURIOUS MOTIONS OBSERVABLE ON 

 THE SURFACES OF WINE AND OTHER ALCO- 

 HOLIC LIQUORS. 



\_A paper by Professor James Thomson, read before Section A 

 of the British Association at the Glasgow Meeting of 

 1855 : Brit. Assoc. Report for 1855, Part II. pp. 16, 17.] 



THE phenomena of capillary attraction in 

 liquids are accounted for, according to the 

 generally received theory of Dr. Young, by the 

 existence of forces equivalent to a tension of the 

 surface of the liquid, uniform in all directions, 

 and independent of the form of the surface. The 

 tensile force is not the same in different liquids. 

 Thus it is found to be much less in alcohol than in 

 water. This fact affords an explanation of several 

 very curious motions observable, under various 

 circumstances, at the surfaces of alcoholic liquors. 

 One part of these phenomena is, that if, in the 

 middle of the surface of a glass of water, a small 

 quantity of alcohol, or strong spirituous liquor, be 



