14 
The connection between contorting and cleaving force is 
not quite clear. It would seem tliat when a certain freedom 
of extension is allowed even the most intractable substances 
yield and change their form. But if the compressed mass be 
wedged up so tightly that change of figure is impossible, the 
individual particles seem to revolve upon their axes, and 
arrange themselves as coins would do, with their principal 
planes transverse to the line of pressure. If the conditions 
exclude even such change as this, the indestructible force 
may develope itself in other ways still less intelligible to 
us, and reappear as heat, chemical action, or segregation. 
Into these inquiries we need not now enter. Our W of 
limestone is explained — that is, brought into an intelligible 
relation with other observed phenomena. 
It would be interesting, though hardly profitable, to 
pursue this subject yet further into the field of molecular 
philosophy. Many attempts have been made to resolve 
various physical states into combinations of certain hypo^ 
thetical atomic forces. These speculations are sure to recur, 
and molecular or atomic theory wiU some day be the basis 
of all physical science, JSTewton, as he says, strongly sus- 
pected that all the phenomena of cohesion and aggregation, 
aU the phenomena of chemistry and physiology, resulted 
from the agency of forces varying with the distance of the 
particles. Boscovitch endeavoured to establish a general 
theory of cohesion upon the properties of unextended atoms 
endowed with powers of attraction and repulsion varying, not 
only in degree but in kind, with the distance, and to such 
elementary forces he expected ultimately to reduce the 
peculiar manifestations of chemical and vital change. In 
our day Sir William Thomson, expanding a suggestion made 
by Helmholz, has sought to show that aU material phenomena 
may be due to motions created in an incompressible, friction- 
less, universal fluid — that the ultimate analysis of matter 
will hereafter give not particles, but vortices. As yet these 
