32 
effect of the percussion is then vastly greater than the initial 
energy ; but this is because the blow has disturbed the un- 
stable equilibrium of the molecules of the chemical mixture, 
and the proper effect of the initial cause, though it remains 
unaltered, is quite lost in the incidental effects. In this case 
also, what we may consider as potential energies are sud- 
denly changed into the kinetic energies of elastic gases. 
Another well-known case of a small initial cause resulting, 
from a similar reason, in effects far beyond those properly due 
to it, is seen in the spread of fire. A lighted match falls 
on a curtain, and a whole city is burned to the ground. This 
instance is sufficient to prove that in the case, not only of 
those substances (such as explosive mixtures) the chemical 
stability of which is very small, but of those also the chemical 
stability of which is considerable, the complete results of the 
initial cause often consists of two totally different kinds of 
effects ; — first, of the effects proper, which are equivalent to 
the cause; and, secondly, of effects due to energies trans- 
formed or set free from their potential form, which bear no 
definable proportion to the original cause. 
23. Such instances are sufficient to prove how much am- 
biguity there is in this subject, and how necessary it would be, 
in any Science of causation in Nature, to distinguish between 
the sequences of cause and effects when the latter are nothing 
more than a continuity of the transformed cause, and are exactly 
equivalent to it ; and when the effects are those which result 
from the transformation of potential into kinetic energies. 
The transformation of itself does not necessarily imply any 
expenditure of energy to produce it ; but, whether this be the 
case or not, it is evident that, as there is no determinable 
relation between the initial cause and the ultimate result, the 
effects of causation in Nature, so far as sequences of this sort 
occur, are absolutely incalculable ; and that, however the 
whole system of animate and inanimate existences may be 
limited by the law of the conservation of energy, it is, neverthe- 
less, unscientific and indeed absurd to regard the universe as 
a piece of mechanism, the consecutive order of which could be 
determined as a problem in dynamics. 
24. For it must be observed that into terrestrial pheno- 
mena (at least) this kind of indeterminate causation enters very 
largely, because the physical changes amongst these pheno- 
mena are in a great measure due to the changes of chemical 
combinations which are acted on by the various energies of 
heat, electricity, magnetism, actinism, and such like. The 
question of chemical equilibrium and the comparative stability 
of chemical combinations has attracted some attention in recent 
