18 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY’ 
and J would venture boldly to put forward the view that the 
association between (1) and (8), and between all three when 
an angle of contact is formed at all, is an absolute one, and 
therefore that whenever K,, exceeds K,, (K_ signifying 
the inter-attractions of two large slabs of matter within 
range across a surface) the strains and molecular spacing 
and orientations in the liquid surface-stratum are such as to 
give rise to an expansility ; and conversely whenever there is 
a negative tension that K,, exceeds K,,. 
It should perhaps be pointed out that if this view 
is correct, it would follow that the negative tension of 
liquid under the influence of solid must often be con- 
siderable since 1+ must equal — Tiuiaair cos 0 (A bemg 
the angle of contact). Thus taking Quincke’s value 25°5° 
for 0 at a glass-water-air meeting-point* and assuming that 
the air film condensed on the glass exerts neither upward 
pull nor downward thrust, if Twaterain equals + 81 dynes, 
T water lass) WOuld equal — 73 dynes, the bracket round the 
word (glass) indicating that the tension concerned is not 
the whole Tyaterciass but only that of the water stratum in 
contact with glass, a “ part-tension’’ as it may perhaps 
conveniently be termed. The angle of contact is assumed to 
be measured between the water-air surface, just beyond range 
of the solid, and the water-glass interface—within range alike 
of solid, water, and air both the tensions and the ‘ angle 
of contact’ would presumably vary in complex fashion from 
point to point, which variations however would in no way affect 
the validity of the conclusion as stated. 
In cases where K,, sufficiently exceeds K,,, we should 
expect that T,,s, would be actually more strongly negative 
than Thiquiaair 1S positive, and consequently that there 
would then be no possibility of equilibrium at a point 
on the surface of the solid, and therefore no angle of 
* Modifications of @ by gravity are eliminated by measuring it only when 
the slope of the solid is such that the water-air surface is horizontal. 
