SULPHURIC ACID FOR WATER. 383 
abstracts it, the more quickly must the newly 
formed compound be enabled to deposit itself in 
the liquid on the floors; for, if the compound 
when newly formed had only a minimum of water, 
it would be a diffused crystalline body, appear- 
ing like a fog; but if it had an opportunity of 
speedily acquiring more water, it (the fog-like 
body) would collect into small drops, and descend, 
like small rain, with greater speed. And, it is re- 
quisite that this compound should get deposited as 
quickly as possible into the liquid on the floors ; 
because it is not till it has become thereby diluted, 
that it emits its supply of nitrous gas for the con- 
tinuance of the process. 
Some manufacturers of sulphuric acid state 
that they are able to make more acid from a given 
weight of sulphur, in a given time, in summer 
than in winter ; but they are not able satisfactorily 
to account for the difference. I have had the 
means of fully satisfying myself that such is really 
the fact; nor is it, indeed, any other than what 
strict attention to theory would lead us to antici- 
pate. Let us only consider, that in winter the 
temperature of the external atmosphere, to which 
the chambers are exposed, is frequently at 32°, 
and not seldom below that, and that in summer it 
