ADH 



ADHESION BETWEEN LIQUIDS AND SOLID BODIES. 205 



As a consequence of their mobility, liquids manifest 

 strongly the force of adhesion, for they come into close 

 contact with solids, whatever the form of the latter 

 bodies. A hand dipped into water and withdrawn, is 

 covered with adhering drops. A drop of water placed 

 between two adhesion-plates causes them to adhere 

 much more firmly. The degree of adhesion between a 

 solid and a liquid body cannot, however, be immediately 

 deduced from the more or less moistened state of a solid 

 which has been immersed in a liquid, for the state of 

 the surface of the body is of considerable influence ; 

 thus water will adhere only in a slight degree to a body 

 which has a greasy or dusty surface. 



If lycopodium (the fine powdery seed of several species 

 of the Lycopodium) be scattered over a board or a table, 

 by means of a wide -necked bottle with a piece of 

 muslin gauze tied over the mouth, drops of water which 

 are let fall upon the surface so covered will not spread 

 out upon it, as is usually the case, but will roll along the 

 surface in the form of globules. If the surface of the 

 water in a basin be covered with a layer (not too thin) of 

 the same powder, the hand may be immersed to some 

 depth into the water without being wet. It would, 

 however, be incorrect to conclude from these facts that 

 there is no adhesion between the water and the fine 

 i resinous granules of the lycopodium ; the powder in 

 these experiments merely hinders the contact between 

 the water and the table or hand respectively, and thus 

 prevents the manifestation of adhesion ; if the globules 

 of water are examined, they will be found covered with 

 the powder. 



There are, however, cases in which no adhesion is 



