of Sea Water, tie, 53 
bubbles occafioning confiderable agitation j and 
returns into the air vefTel through the com¬ 
munication (CC.) That portion of fixed air, 
which is incapable of abforption by lime water, 
&c. being fpecifically lighter than the reft, 
will efcape through the orifice (at O) as the fixed 
air is fupplied by the effervescing mixture, but 
the pure fixed air, thus returned into the air 
veflfel, is again inhaled by the bellows, and blown 
into the lime water. The air and water veflels, 
in the model I have had made, are of tin, con¬ 
taining about four gallons a-piece. The orifices 
(at T, t , B, b,) are made air-tight, with per¬ 
forated corks. The tubes (P, p and t) run 
down the fides of the air veflels. The tube (b) 
which is a corftinuation of the bellows pipe, runs 
down the middle of the water veflel. This pipe 
might be immerfed twelve or thirteen inches into 
the body of the water, as I have found, that a pair 
of common bellows, will force air through water, 
to this depth, with moderate exertion. 
In my model, the bellows, contrary to my 
direction, are of a large fize, and there was diffi¬ 
culty in working them, as might be expected, 
when all the orifices are fhut. To obviate this 
inconvenience, I tied a bladder, full of fixed air, 
upon the orifice (at O) and opening into the air, 
veflel. By this device, the bellows work with 
as much eafe as in the open air; and the bladder 
fills and empties exactly like the lungs in refpira- 
E 3 ti°n, 
