43 S Dr. ingen-housz on the Influence of the 
of Dr. hales and Mr. boyle, will add ftrength to my aflertion, 
viz. that vegetables really throw out air in the fun-fhine. 
O j 
If all what 1 have laid hitherto fhould not be thought fuffi- 
cient to take away the prejudice which Dr. Priestley’s fifth 
volume, and Mr. cavallo’s book on Air, may have produced in 
the mind of feme philofophers, I fhould advife them to be pre- 
fent, at leaft once, at the mold beautiful ficene which they will 
behold, when a leaf of an agave Americana , cut in two or three 
pieces, is immerfed in a glafs hell or jar full of pump-water, 
inverted and expofed to the fun in a very fair dav in the middle 
of the fummer, when this plant is in its full vigour ; and when 
they fhall have feen thofe beautiful and continual ftreams of 
j 
air, which rulh from feveral parts of this vegetable, princi- 
pally from the white internal fubftance of it, I will be an- 
fwerable for their laying afide all farther doubt about the truth 
of my doctrine. 
After having now demonftrated, as I think, in the cleared: 
manner, that vegetables diffufe through our atmofphere, in 
the fun-fhine, a continual Ihower of this beneficial, this truly 
vital air; and that plants immerfed in water, far from robbing 
it of all air, impregnate it fully with a better and more fa- 
lubrious air; let us not pafs fo wonderful, and hitherto not 
even Jo much as fufpedted, an operation of nature, without ad- 
miring the deligns of that infinite wifdom, who has employed 
fuch hidden, fuch wonderful, and at the fame time fuch bene- 
ficial means to preferve from deftrudlion the living beings which 
inhabit our earth ; and let us confider, whether it would not 
be worth while to attempt drawing fomc benefit from this new 
difeovery, by making ufe of velfels of water, in which lbme 
leaves of vegetables have been expofed in the fun-fhine ; by 
placing fuch veflels in our rooms; by ftirring the water; by 
2 fprinkling 
