256 Proceedings of the Royal Society of Edinburgh. [Sess. 
and the two atoms of the oxygen of the sether (now in presence of each other) being 
in different (perhaps different electric) conditions, mutually loosen their former 
affinities and reunite themselves to the (electrically?) different atoms of oxygen of 
these respective combinates. 
The same principle may naturally be expected to display itself with regard to 
acids and bases. The oxygen of an acid unites itself to the (electrically ? ) different 
oxygen of water. The oxygen of a base on the same principle has an affinity for the 
electrically different oxygen of water. 
It will be observed — 
1. That the oxygen of the water of an acid can only be expelled by that of a 
base and vice versa. 
2. It is to be remarked that it is not the metal of a base which exchanges places 
with the hydrogen of the hydrate of an acid ; for if that were the case, the affinity 
of the oxygen of the metal, and also of the acid, would be greater for the oxygen of the 
water than the affinity of the hydrogen for that same oxygen. But this is not so. 
The very opposite is the truth. If one atom of hydrogen be withdrawn from the 
hydrate of an acid or from the hydrate of an oxide , it is universally accompanied by 
an atom of oxygen. It is evident, then, that the affinity between the positive and 
negative atoms of oxygen is less than that which attaches these atoms to the element 
with which they form a primary combinate. 
A consequence of this truth is, that it is impossible to double the equivalent of 
oxygen, if the chemical equivalents are to be understood as not being in direct 
contradiction to any chemical truth or essential feature in the properties of an 
element. Carbon differs entirely in this respect from oxygen. 
There is no reaction found where it is known that C 2 is divided into two parts. 
It is only consequent therefore to write, with Gerhard t, C 2 simply as C, it being then 
understood that the equivalent of carbon is (12) twelve. 
This value of the atom will be adopted in the following part of this paper. 
Sulphur, selenium, etc., being bodies displaying properties similar, not to carbon, 
but to oxygen, it will be necessary to retain the equivalent value that has generally 
been assigned to them. 
I have now shown how ordinary alcohol, C 2 H 6 0 2 common sether, and the hydro- 
carbide, C 2 H 6 , belong to the type nCM 4 . The phenomena which necessitate this 
view of the constitution of these bodies have a like consequence in regard to the 
other alcohols, glycols, acids, and sethers of this series. 
p--0 -OH 
: ••• H 2 
Propyle alcohol is (V..qq 2 > where it w r ill be seen that the atom of carbon 
C ■ H 3 
situated between the two others, on account of being chemically united to these, is 
reduced to the combining power of two for hydrogen, oxygen, etc. One combining 
power is given up to the carbon upon the one side, and a second to the carbon upon 
the other. 
It will be observed also that the primary combinates ought in rigour to be them- 
selves enumerated in an inverse order. The type nCM 4 becomes then in reality the 
