646 The Philippine Journal of Science 1921 
sistent theory of the mechanism of reactions. The difficulty was 
the ancient one of putting ‘new wine in old bottles.” 
There has been a strong tendency iin the last two decades to 
refer everything unexplainable to “tautomerism,” which has been 
used as a convenient hypothesis allowing one to manufacture as 
many structures as he desires for a compound. The result has 
‘naturally been a mass of confusion, from which there was only 
one way of escape, namely, the one clearly indicated half a cen- 
tury ago by Kekulé’ himself, when he emphasized the fact that 
his formulas were nothing but rational formulas, and that true 
constitutional formulas could be obtained only through physical 
research. Although physicists cannot yet tell us the exact pro- 
portions or the exact forces in atoms, they can tell us much. It 
seems that the time is now at hand when the Kekulé affinity 
units may be, with due respect for what they have accomplished, 
laid on the shelf and replaced by more definite conceptions. 
RECENT CONCEPTIONS OF CHEMICAL AFFINITY 
Ever since the discovery of electrons it has been apparent 
that they are connected intimately with atomic union. A 
certain form of union between atoms (the salt-forming union) 
was easily explained as due to the transfer of an electron from 
one atom to another. While such an interpretation proved very 
valuable to inorganic chemists in dealing with this type of union, 
it was found to be no advance over the older form, A-—B*, in 
dealing with the type of union predominant in organic chemistry, 
which may be called the direct union. No satisfactory electronic 
conception of the direct union had been proposed until Lewis * ad- 
vanced his hypothesis of the “cubical atom,” which was later 
developed and made more definite by Langmuir ® as the “octet - 
theory of valence.” 
THEORY OF REACTION MECHANISM OF THE DIRECT BOND 
On the basis of Langmuir’s octet theory of valence it seems 
possible to revise the older theories of reaction mechanism into 
a much more tangible and consistent form. For the sake of defi- 
niteness, and because physicists disagree concerning force laws 
at small distances, it is necessary to put in the form of definitions 
"Kekulé, F. A., Ann. d. Chem. 106 (1858) 147. 
* Lewis, G. N., Journ. Am. Chem. Soc. 38 (1916) 762. 
* Langmuir, I., Journ. Am. Chem. Soc. 41 (1919) 868, 1548; 42 (1820) 
274. For the notation and nomenclature used cf. Perkins, G. A., Philip. 
Journ. Sci. 19 (1921) 1. 
