170 dnalyjis of the Air. 



they drew the Air briskly out of the glafs 

 z z a a thro' the fyphon ; the other leg of 

 which fyphon I immediately drew from under 

 the glafs veflel, marking the height of the 

 water z z. 



When the materials on the pedeftal ge- 

 nerated Air, then the water would fubfide 

 from z z to a a, which fpace z z a a was 

 equal to the quantity of Air generated : But 

 when the materials deftroyed any part of the 

 Air's elafticity, then the water would rife 

 from a a (the height that I in that cafe at 

 firft fucked it to) \.ozz y and the fpace a a z z 

 was equal to the quantity of air, whofe elafti- 

 city was deftroyed. 



Ifometimes fired the materials on the pe- 

 deflal by means of a burning glafs, viz. fuch 

 as phofphorus and brown paper dipped in 

 water, ftrongly impregnated with nitre, and 

 then dried. 



Sometimes I lighted the candle, or large 

 matches of brimftone, before I whelmed the 

 glafs z z a a over them ; in which cafe I 

 inftantly drew up the water to a a y which 

 by the expanfion of the heated Air would 

 at firft fubfide a little, but then immediately 

 turned to a rifing ftate ; notwithftanding the 

 flame continued to heat and rarefy the Air 



for 



