\ 6 4 Analyfes of the Air. 
hydroftatical gages, in the following man- 
ner, viz. 
In order to make an eftimate of the quan- 
tity of Air which arofe from any body by 
diftillation or fufion, I firft put the matter 
which I intended to diftil into the fmali 
retort r (Fig. 33.) and then at a cemented 
faft to it the glafs veflel a b, which was very 
capacious at b , with a hole in the bottom. 
I bound bladder over the cement which was 
made of tobacto-pipe clay and bean flower, 
well mixed with fome hair, tying over all 
four fmali flicks, which ferved as fplinters 
to ftrengthen the joint 3 fometimes, inftead 
of the glafs veflel a b, I made ufe of a large 
bolthead, which had a round hole cut, with 
a red hot iron ring at the bottom of it 3 
through which hole was put one leg of an 
inverted fyphon, which reached up as far 
as z. Matters being thus prepared, holding 
the retort uppermoft, I immerfcd the bolt- 
head into a large veflel of water, to a the 
top of the bolthead 5 as the water rufhed in 
at the bottom of the bolthead, the Air was 
driven out through the fyphon : When the 
bolthead was full of water to then I clofed 
the outward orifice of the fyphon with the 
end of my finger, and at the fame time drew 
the 
