546 
CHEMISTRY: W, D. HARKINS 
degree per gram molecule. On turning to molecular compounds such 
as ammonia and carbon dioxide it is found that the entropy of fusion 
is 9.3 for the former and 8.9 for the latter, while for benzene the value 
is 8.3. Corresponding to Walden's rule a large number of organic com- 
pounds have entropies of fusion between 12 and 14 calories per degree, 
while many of the substances with smaller entropies of fusion possess 
other properties characteristic of associated liquids when they are in 
the liquid state. As might be expected substances with very complex 
formulae give high values, the increase with molecular complexity being 
very distinct. Thus with stearic acid (C1H36O2) the value rises to 40, 
while the acid with two carbon atoms has an entropy of only 9.5, with 
nine carbon atoms of 10.5, while in the case of the 12 carbon atom acid 
the value rises to 27. 
It is thus to be seen that the entropy is a very important function in 
a study of the transfer of molecules from one region to another, and 
that in general the price which a molecule has to pay in terms of energy 
in order to undergo any certain change, increases with the temperature or 
the molecules pay in proportion to their wealth with respect to energy. 
There is also an increase in this energy price whenever the complexity of 
the molecules increases sufficiently. The price in terms of entropy i s 
much more constant than the price in terms of energy, and in this sense 
there is an analogy to the action of a Carnot engine. 
It is beheved that the point of view presented in abstract in this 
short paper will greatly change the present attitude in regard to the 
determination of molecular association in Hquids, and it is possible that 
it may be of importance in a study of the general subject of the partition 
of energy, as well as in changes of kinetic into potential energy.^^ 
The complete paper of which this is a part will be presented to the 
Journal of the American Chemical Society by Mr. L. E. Roberts and 
the writer, for publication in a later issue. 
1/. Amer. Chem. Soc, Easton, Pa., 38, 1916, (1452). 
2 Ibid., 41, 1919, (970-92). Proceedings, May, 1919. 
3 Physic. Rev., July, 1919. 
4 Leipzig, Ann. Physik, 27, 1886, (452). 
6 London^ Phil. Trans. Roy. Soc, 184A, 1893, (647), Zs. Physik. Chem., Leipsig, 12, 1893, 
(647). 
«/. Amer. Chem. Soc, 37, 1915, (975). 
7 Zs. Elektrochem., 14, 1908, (715). 
8 Crompton, /. Chem. Soc, 67, 1895, (315-327). T. W. Richards, /. Franklin Institute, 
1902. 
^Wayling, Phil. Mag., 37, 1919, (495). 
^° Since this paper was submitted I have received a copy of a paper presented to the 
Society Frangaise de Physique by M. J. Duclaux on June 6, 1919. He believes that there 
are quantities of energy of magnitude 6.6 X 10"^^ ergs. 
