A metric lick is expressed in moles of substance removed from
the surface per square centimeters of tongue surface in contact
with the surface. Associated with any measurement made in licks
is a saliva index, which indicates how many moles of saliva were
transferred, on average, to the surface.  Figures on how many
metric licks are in one swipe of the tongue on different
surfaces are appreciated. I may generate them myself when I have
a chance (it's midnight, and I don't want to go around licking
things right now) - s_alanet