C 234 ] 
the conjectures of Dr. Franklin, made many years 
ago, and exprefled in the following extra# from the 
laft edition of his Letters, p. 346. 
“ I have been inclined to think that the fluid fire , 
“ as well as the fluid air , is attracted by plants in 
“ their growth, and becomes confolidated with the 
“ other materials of which they are formed, and 
s ‘ makes a great part of their fubftance ; that, when 
“ they come to be digefted, and to fufter in the 
4 ‘ veflels a kind of fermentation, part of the fire, as 
sc well as part of the air, recovers its fluid aCtive ftate 
“ again, and diffufes itfelf in the body, digefting and 
“ feparating it j that the fire fo reproduced, by di- 
** geftion and feparation, continually leaving the 
4t body, its place is fupplied by frefh quantities, 
“ arifing from the continual feparation ; that what- 
“ ever quickens the motion of the fluids in an ani- 
“ mal quickens the feparation, and re-produces 
“ more of the fire, as exercife ; that all the fire 
“ emitted by wood, and other combuftibles, when 
burning, exifted in them before, in a folid ftate, 
u being only difeovered when feparating ; that fome 
tc foflils, as fulphur, fea-coal, &c. contain a great 
“ deal of folid fire ; and that, in fhort, what efcapes 
<c and is diffipated in the burning of bodies, befides . 
water and earth, is generally the air, and fire, 
s< that before made parts of the folid.” 
IX. 
Of Air procured by means of spirit op salt,. 
Being very much ftruck with the refult of an ex- 
periment of the Hon. Mr. Cavendifh, related Phil. 
Trank 
