1819.] and on some other Subjects of Chemical Theory. 295 
analogy, similar to that in which it holds dissolved the vegetable 
acids, which are admitted to be ternary compounds of carbon, 
hydrogen, and oxygen. The opposite view applies only to that 
ortion of water considered as essential to the body in an insu- 
lated state, and in which it is combined in a definite proportion, 
observing in its relations, or the relations of its elements, equi- 
valent proportions to other bodies. 
In the last place, considering this opinion in relation to the 
two opposite views which have been maintained with regard to 
the constitution of oxymuriatic and muriatic acids, while it has 
all the evidence in its favour from which the existence of water 
in muriatic acid gas is inferred, and all the analogies by which 
this is confirmed ; it has the support which the doctrine of the 
undecompounded nature of chlorine derives from the relations 
of sulphur, iodine, and cyanogen; and from the induction that 
hydrogen, as weil as oxygen, communicates acidity. It avoids, 
at the same time, the improbability which attends that doctrine, 
in its leading principle, that muriatic acid contains no combined 
water, though other powerful acids are held to contain it,and though 
it affords water by the very same processes by which they yield 
it; and in the still greater violation of analogy (the most extra- 
ordinary perhaps ever admitted in chemical reasoning), involved 
in the conclusion that the compounds which this acid forms 
with salifiable bases, though the same in all generic properties 
with those formed by other acids, are not of similar constitution, 
and are not even of a saline nature. It unites the advantages, 
therefore, of both doctrines, and connects, under one system, 
facts which are otherwise insulated, and partial generalisations, 
which, instead of having any relation, seem opposed to each 
other. 
The same general view, I have still to add, may be further 
extended. Alkalinity, as well as acidity, is the result appa- 
rently of the action of oxygen; the fixed alkalies, the earths, and 
the metallic oxides, which all contain it.as a common element, 
forming a series in which it is difficult to draw any well defined 
line of distinction. Ammonia alone remains an exception: it 
contains no oxygen, and yet possesses in a very marked degree 
all the alkaline properties—an anomaly so great, as to have led 
almost every chemist to infer that oxygen must exist as an 
element in one or other of its constituent principles; and as 
nitrogen is the one apparently least elementary, it has been 
supposed to be a compound containing oxygen. The result 
may be accounted for, however, on a very different principle. 
As hydrogen, in some cases, gives rise, as well as oxygen does, 
to acidity, so it may, in other cases, give rise to alkalinity. 
Under this point of view, ammonia is a compound of which 
nitrogen is the base, deriving its alkaline power from hydrogen ; 
it stands, therefore, in the same relation to the other alkalies that 
sulphuretted hydrogen does to the acids. And thus the whole 
