[ a72 } 
SE CTION XVIM. 
Experiments foewing that the pureft 
“ dephlogifiicated air, and the great 
off quantity, is yielded by Sull-grown 
= leaves. 
of pump-water ‘the’ extremity of 
branch of a vine containing leaves 
of different ages, from the full+ 
grown to thofe which begin only | 
to unfold themfelves; The bub- 
bles appeared the firft in the old 
leaves ; and they broke owt gras 
_ dually upon the next_in age; fo 
that they appeared the lateft upon 
_ the new-formed leaves. The fame 
= proportion takes place alfo in the 
2 = fize of the bubbles, as well as in 
