204 
FREDERICK BARRY 
from experience, and in none of its implications at variance with the 
results of experiment — which enables man to correlate the great com- 
plexity of all measurable phenomena as interdependent changes, of 
one general and definite character within a single vast mechanism. 
We know, concerning energy, that within the limits set by the 
possible accuracy of our measurements, it suffers no diminution with 
the passage of time; that its disappearance in one form is coincident 
with its appearance in another. We are able to formulate exactly 
its dimensions: that is, its magnitude in terms of the fundamental 
concepts of mass, and of geometrical space and time. We know, 
further — thanks to the invaluable labors of Carnot and Clausius — 
that its possible transformation is limited in a significant way: that 
while all of the energy forms familiar to us may be converted com- 
pletely into heat, heat energy itself can be only partially transformed. 
It results that within any isolated system, as time goes on, though 
no energy disappears, an increasing portion of it becomes unavialable, 
in the form of uniformly distributed heat. We are thus compelled 
in studying the energy changes which accompany any natural process 
to distinguish between that part of the heat energy released or ab- 
sorbed which may be transformed directly or indirectly into work, 
and that which may not ; to introduce into our scheme two additional 
conceptions, those of free energy and bound energy. 
Our knowledge of energy thus summarized is expressed in two laws, 
which are fundamental: the law of the conservation of energy, and the 
law of the limited transformation of energy. These are commonly 
known, respectively, as the first and second laws of thermodynamics. 
Both have been quantitatively formulated in terms of free and bound 
energies; and these formulations will soon claim our attention (i). 
Both thermodynamical laws, because of their very generality, 
are characterized by one limitation : they apply to phenomenal changes 
in the gross, and are insufficient to describe in any satisfactory way, 
the details of a natural process. The need thus indicated has, however, 
been almost completely satisfied by the elaborate conceptual scheme 
which during the last century has been developed — simultaneously 
with the theory of energetics, and consistently with the growth of 
chemical knowledge — out of Dalton's first scientific application of the 
atomistic conception of matter. In the modern kinetic-molecular 
theory, already worked out in great perfection of detail, the physical 
scientist has a means of supplementing and extending the implications 
i 
