85 
on the Cohesion of Fluids. 
we may infer that the mutual attraction of the particles of 
mercury being unity, that of mercury for gold will be .1 or 
more, that of silver about .94, of tin .90, of lead .81, of bis- 
muth .72, of zinc .21, of copper .10, of antimony .08, of iron 
.07, and of cobalt .0004. The attraction of glass for mercury 
will be about one-sixth of the mutual attraction of the particles 
of mercury: but when the contact is perfect, it appears to be 
considerably greater. 
Although the whole of this reasoning on the attraction of 
solids is to be considered rather as an approximation than as a 
strict demonstration, yet we are amply justified in concluding, 
that all the phenomena of capillary action may be accurately 
explained and mathematically demonstrated from the general 
law of the equable tension of the surface of a fluid, together 
with the consideration of the angle of contact appropriate to 
every combination of a fluid with a solid. Some anomalies, 
noticed by Musschenbroek and others, respecting in particular 
the effects of tubes of considerable lengths, have not been 
considered : but there is great reason to suppose that either 
the want of uniformity in the bore, or some similar inaccuracy, 
has been the cause of these irregularities, which have by no 
means been sufficiently confirmed to afford an objection to any 
theory. The principle, which has been laid down respecting 
the contractile powers of the common surface of a solid and a 
fluid, is confirmed by an observation which I have made on 
the small drops of oil which form themselves on water. There 
is no doubt but that this cohesion is in some measure inde- 
pendent of the chemical affinities of the substances concerned : 
tallow when solid has a very evident attraction for the water 
