CAPILLAR Y A TTR ACTION. 5 1 



"tears" begin to form at .once. I first incline 

 and rotate the bottle so as to wet its inner surface 

 with the liquid, and then, leaving it quite still, I 

 remove the stopper, and withdraw by means of 

 this paper tube the mixture of air and alcoholic 

 vapour from the bottle and allow fresh air to take 

 its place. In this way I promote the evaporation 

 of alcohol from all liquid surfaces within the 

 bottle, and where the liquid is in the form of a 

 thin film it very speedily loses a great part of its 

 alcohol. Hence the surface tension of the thin 

 film of liquid on the interior wall of the bottle 

 comes to have a greater and greater value than 

 the surface-tension of the mass of liquid in the 

 bottom, and where these two liquid surfaces having 

 different surface-tensions come together, we have 

 the phenomena of " tears." There as I hasten 

 the evaporation, you see a horizontal ring of 

 liquid being formed and creeping up the side 

 of the bottle : afterwards we find the liquid so 

 raised collecting into drops which slip down 



the side and give a fringe-like appearance to 



E 2 



