Bearing of this investigation on existence of connection between
molecular structure and molecular energy
Further illustrations of this connection
Illustrations of existence of relations between greater or less
molecular energy and
(1) the actual valencies of the atoms in the molecules con-
sidered
(2) the distribution of reactions between the atoms in the
molecules.
General considerations regarding relations illustrated in pars. 87
and 88.
Application of these considerations to prevalent views on valency
Apparent exceptions to that explanation of isomerism which is
based on the theory of valency
Properties of liquid and solid compounds are to some extent con-
ditioned by mutual molecular actions
Physical isomerism
Work of Lehmann on this subject
Criticism of Lehmann's division of physical isomerides into phy-
sical metamerides and polymerides
Summary of section iv.
Appendix to section iv.
Lossen's criticism of the various meanings assigned to term
valency:
'Are the carbon bonds of equal value?'