1853.] OF THE ROYAL INSTITUTION. 241 
by doubling the atomic weight of water as by halving that of 
hydrated nitric acid; but either way it is clear that hydrated 
nitric acid cannot contain water. 
Such was the position of the question, when an English chemist 
proved that the formation of ether from alcohol (which was con- 
sidered chemically as the hydrate of ether,) does not consist in a 
separation of two already formed compounds, but in a substitution 
of hydrogen by the organic radical ethyl. A similar fact M. Gerhardt 
has proved respecting a great number of organic acids, by pre- 
paring bodies which stand to them in the same relation as ether 
does to alcohol. 
The researches of M. Cahours had led to the discovery of a 
series of bodies necessary for Gerhardt’s process. These were 
obtained by the action of pentachloride of phosphorus on 
various hydrated organic acids, and consisted of chlorine combined 
with the oxygenized radical of the acid. Thus from benzoic 
acid was prepared the chloride of benzoil, C, H, O Cl, and the 
corresponding bodies, from cuminic, cinnamic, and various other 
acids. Gerhardt has since made by the same process the body 
C, H, O Cl, which is the chloride of the radical of acetic acid, 
called othyl. Now, on bringing any one of these chlorides in 
contact with the potassium-salt of the corresponding acid, the 
chemical force of combination between chlorine and potassium 
induced the decomposition. 
These results can be most simply stated in the form adopted 
by M. Gerhardt the discoverer, which consists in comparing the 
composition of these bodies with that of water, from which they are 
formed by the substitution of one or both atoms of hydrogen by 
organic radicals. 
Thus water being represented by the formula 0, acetic acid is 
formed from it by the action of chloride of othylC, H, O Cl, 
which forms © ah: +H Cl i.e. hydrated acetic acid and 
hydrochloric acid. If a second atom of chloride of othyl is made 
to act upon this acetic acid, or better upon the acetate of potash 
Ps z he O, we get, besides chloride of potassium, a compound 
o, Hu, O 
,'H, O 
sidered as water having both its atoms of hydrogen replaced by 
the radical othyl, C, H, O. This compound is the anhydrous 
acetic acid which might be called the acetate of othyl, inasmuch 
as that radical has, in the formation of the compound, taken the 
place of the basic potassium in the acetate of potash. 
In like manner, the anhydrous benzoic acid et Bs . O was made 
q 5 
S 
O which when compared to the original type, may be con- 
