IN CAPILLARY GLASS TUBES. 267 



liquids and solids. When mercury is poured 

 on a marble or wooden table, it collects in large 

 globules, for the same reason that water aggre- 

 gates into large drops when poured upon dry 

 silk, a duck's feathers, and other non-conduct- 

 ing bodies or for the same reason that when 

 plates of glass are smeared with tallow they do 

 not attract water unless previously wetted. 



On the Connexion between Gravity and the 

 Molecular Forces of Nature. 



IT has been said that the attraction of atoms is 

 not like that of gravitation, inversely as the 

 squares of the distance. This assertion is not 

 only refuted by all analogy, but by the well 

 established fact that the elevation and force with 

 which liquids rise in capillary tubes, cceteris pari- 

 bus, is inversely as their diameters. The prin- 

 cipal difference between the attraction of atoms 

 and that of masses is, that the former acts at 

 exceedingly small distances, corresponding with 

 the minuteness of atoms ; while the power of 

 masses extends to comparatively great distances. 

 The aggregate force of cohesion with which a 

 mass of granite is held together, other things being 

 equal, is proportional to the number of its ulti- 

 mate particles. The force of gravity with which 

 it presses upon the earth is in the same ratio. 



