( ) 
Mr. Hales^ from the Confideration of this, and fome 
of his oVn Experiments, concluded, that there mud 
be Air not only in an elaftick, but in a fix’d State, in 
Vegetables and other Subftances, and therefore that the 
Air-Pump wou’d not be fufficient to get all the Air 
out of Bodies: For which reafon he contriv'd ways of 
getting the Air out of feveral Subftances by Fire 
^diftillingthem,') and by Fermentation, and made ufe 
of a very ingenious, but fimple and certain Method, 
of meafuring the Quantity of Air generated from(or ab- 
fofb‘d by) the feveral kinds of Bodies upon which he 
made Experiments. The Defcription of his Hydro- 
ftatical Gages , and the Manner of making his Experi- 
ments, I cannot give better, or fhorter, than in his own 
Words. QSee Page 1 5- 7.) 
“ In order to make an Eflimate of the Quantity of 
“ Aiir which arofe from any Body by Diftillation or 
“ Fufion, I firft put the Matter which I intended to 
“ diftil, into a fmall Retort r (^Figure 4 J and then at 
'a cemented faft to it the Glafs-Veffel^i h, which was 
“ very capacious at h, with a Hole in the bottom. I 
“ bound a Bladder over the Cement, which was made 
“ of Tobacco-pipe-Clay and Bean-flower, well mixed 
“ with fome Hair, tying over all four (mail Sticks, 
“ which fervM as Splinters to ftrengthen the Joynt ; 
fometimes, inflead of the Glafs-Veffel ah,\ made 
“ ufe of a large Bolt-head, which had a round Hole 
“ cut, with a red-hot Iron-ring, at the bottom of it ; 
“ through which Hole was put one Leg of an inverted 
“ Syphon, which reached up as far as z Matters being 
“ thus prepared, holding the Retort uppermoft, I 
“ immerfed the Bolt-head into a large Veffel of Water, 
“ to the top of the Bolt-head,* as the Water ruflied 
“ in at the bottom of the Bolt-head, the Air was 
“ driven out through the Syphon : When the Bolt- 
head 
