ATMOSPHERICAL AIR. 15 



proceis of vegetation ; or the phlogiflicated part alone of 

 the atmofphei-e may have had that origin, and the de- 

 phlogifticated part have come from vegetation. 



I once thought that a very fmall quantity of any of the 

 acids enabled water to yield more air than it would do 

 without them, and while 1 ufed only fmall bulbs, I con- 

 tinued to think fo ; but when I ufed the larger veflels 

 above mentioned, 1 could not perceive any fenfible 

 difference in the refults in confequence of this cir- 

 cumftance. 



The quantity of air extricated from diftilled water 

 before the produdlion becomes equable is about one for- 

 tieth of its bulk. 



Wifhing to leave nothing undone that I was capable 

 of doing with refpe£l to this courle of experiments, I 

 have, fmce the publication of the tradt above mentioned, 

 endeavoured to convert the whole of a fmall quantity of 

 water into air, but it has been without effedt. Having 

 provided barometer tubes with bulbs connected with 

 them, from one inch to three inches in diameter, I firft 

 put into them a fmall quantity of water, and then filling 

 them with mercury, left them fome time with the orifices 

 of the tubes upwards, in order to give the water an 

 opportunity to rife to the top. I then inverted them, 

 when after fome time a very fmall quantity of water 

 would be vifible on the furface of the mercury in the tube, 

 and the vapour arifing from it in vacuo would, of courfe, 

 be diffufed through the whole of the bulb above it. 

 After this, inclining the veflel, and making it lean over 

 a fire, that fmall quantity of water was wholly converted 

 into vapour, fo as to caufe the mercury to defcend, and 

 leave both the whole of the bulb, and part of the tube, 

 filled with hot vapour, and in this ftate 1 kept it feveral 

 hours. After this 1 always found a quantity of air pro- 

 duced, and this I threw out, by inverting the veird. 



Then 



