52 Mr. Henry on the Prejervatkn 
i 
ufed at fea. It is capable, however, of being 
applied to fo many ufeful purpofes, that, I trull, 
the Society will think the communication of this 
valuable improvement well worthy of their at¬ 
tention. 
Defcription of an Apparatus to mix Air with Liquids. 
In the figure, plate i. an effervefcing veflel is 
reprefented (at E) in which fixed air is detached 
from a mixture of calcareous earth, and vitriolic 
acid, conveyed through the tubes (T /) into the 
air veflel (A). The fixed air, being of greater 
fpecific gravity, will fall to the bottom, and 
expel the common air at the top through the 
orifice (at O). It may be known when the veflel 
is full of fixed air, by fuelling; or extinguifhing 
a candle at this orifice; or by .computing the 
quantity of vitriolic acid and calcareous earth 
that will generate a certain quantity of air. A 
pair of common bellows (at B) with a pipe, a few 
inches longer than ufual and bent, is placed with 
the vent fo as to receive the air pipe (P), and 
the bellows pipe at ( b ) is inferted into the top 
of the water veflel (W). The bellows being 
worked, the fixed air riles, from the bottom of the 
air veflel, through the pipe (P P) into the vacuum 
within the bellows, and is impelled, with force, 
through the bellows pipe ( b ) into the body of 
the water veflel, filled with lime water, or any 
other kind of liquid. The air, which is noc 
abforbed by the liquid, rifes to the furface in 
bubbles 
