1. (Energy of adhesion in vacuum)
Therefore, in vacuum is always negative.
Note: are all positive quantities. has units of energy per unit area.
If
A lesser value of would mean that is more positive. This implies that the surface would be more wettable.
2. (Energy of adhesion in the presence of an intervening fluid)
(Energy of adhesion in vacuum)
are all positive quantities. 
has units of energy per unit area.
would mean that 
is more positive. This implies that the surface would be more wettable.
(Energy of adhesion in the presence of an intervening fluid)
