CAPILLARY ATTRACTION. 257 



contact of heterogeneous substances, the laws 

 and nature of which change are, and perhaps for 

 ever, will remain unknown to us." (Edinburgh 

 Philosophical Journal, vol. viii. 253.) 



Sir H. Davy maintained, " that water is com- 

 bined with rocks, earths, salts, wood, muscular 

 fibre, &c. by chemical attraction ; but that it 

 combines with glass, porcelain, &c. by cohesive 

 attraction." This is contrary to his own, and the 

 general view of chemical attraction, which is de- 

 fined as " the force that unites different ele- 

 ments, and as the antagonist of cohesion," which 

 is supposed to unite homogeneous elements. But 

 there is as much difference between water, and 

 glass or porcelain, as between water and salts, 

 rocks, wood, or muscular fibres. 



There is no end to the ambiguities and con- 

 tradictions that have resulted from regarding 

 cohesion and capillary attraction, as referable to 

 a different cause from what produces chemical 

 affinity. I have already proved that the par- 

 ticles of water and other compound bodies, are 

 held together by the same agent which causes 

 the cohesion of gold, or any other homogeneous 

 body. The same power that unites the atoms of 

 quartz, feldspar, and mica, and holds them to- 

 gether in the form of granite or gneiss, main- 

 tains the cohesion of liquids. This principle has 

 been recognized by Laplace, in a supplement 

 to the 10th Book of the Mechanique Celeste, 



