CARBONIC ACID IN THE ATMOSPHERE. I] 
is soon diffused and becomes almost insensible 
in the great mass of aerial fluid. 
There are no experiments tending to shew 
whether the quantity of Carbonic acid gas in 
the atmosphere is upon the increase or decrease. 
From the above facts it is obvious that large 
additions are made to it every day; but some 
are of opinion that this gas is decomposed in 
the process of vegetation, in which the carbon 
enters the vegetable, and the oxygen is restored 
to the atmosphere. If this should be the case, 
which has not been satisfactorily proved, there 
may be a kind of equalization established be- 
tween the animal generation and destruction of 
this gas. Mr. Dalton has made a calculation 
(see memoirs vol. 2nd. p. 41, second series) to 
shew that the quantity of acid gas at present 
found in the atmosphere may be no more than 
the natural produce of 6000 years, and that the 
supposed decomposition of it may not be neces- 
sary. 
Under these circumstances it is evidently ex- 
pedient that the quantity of acid gas now in the 
atmosphere, should be as accurately ascertained 
as is practicable. 
