382 RELATIVE ATTRACTIONS OF 
Now, the only state of the water with which 
the greater bulk of the mixed gases in the cham- 
bers has the opportunity of coming quickly into 
contact, is the vaporous state; and when it is 
considered how little the weight of aqueous va- 
pour is which is capable of existing in a given 
space, at ordinary atmospheric temperatures, we 
need not be surprised at the slowness of the pro- 
cess of the manufacture of the acid in question. 
At the commencement of the manufacture of 
the acid, the floors of the chambers are covered 
either with water or dilute acid; and therefrom 
arises, into the aerial space, aqueous vapour, as 
in other ordinary instances of spontaneous evapo- 
ration. Supposing the large quantity of mixed 
sulphurous and nitrous acid gases to seize with 
avidity upon the whole of the vapour, and make 
the aerial space anhydrous; this anhydrous space 
would acquire more vapour from the liquid on the 
floors, and thereby be the means of transferring 
more water to the newly formed compound, which 
must be slowly descending, like a fog, towards the 
liquid on the floors. It is obvious that the 
greater the amount of vapour existing in the 
chambers previously to the commencement of the 
process, and the more quickly the space can be 
replenished with vapour as the action of the gases 
