Vegetable Kingdom on the Anim Jr eat ion.. 43- 
the metallic fluid 111 the tube, to al 1 ' t ;e air within the tube 
to expand by the heat of the fun without eleaping. After this 
apparatus had flood during a few hours, in a bright fun- Shine, 
I cooled the whole to the fame degree it poflefled when it was 
expoled to the fun. This was done by plunging the whole in 
a tub filled with water, whofe degree of heat was reflored to 
the fame degree it had before. I found the quantity of air 
within the tube remarkably increafed, and fo far dephlogifti- 
cated that a flame burned in it with an increafed brieht- 
nels, and that one meafure of it joined to one meafure of 
nitrous air occupied 0.64 ; whereas the fame air, before it 
was fhut up with tire csreus was of inch a degree of 
goodnefs, that one meafure of it with one of nitrous occu- 
pied 1.06. Though this experiment may fully (hew that 
plants throw out air in the fun-fhine, yet if another plant, 
which does not by nature yield fo much air as the cercus com- 
monly does, is fhut up in a fimilar tube, and expofed to tiie fun, 
the fame effect will not always be obtained. The reafon of it 
is, that plants abforb a good quantity of common air as their 
nourishment at the lame time that they throw out dephlogifti- 
cated air. This fact, therefore, if confidered by itfelf, will not be 
looked upon as equally demonstrative with the above mentioned 
ones. I he refult of this experiment may depend on the more or 
lei's vigour of the vegetable employed, on the more or lels bright-* 
nels of the lun’s light, on the more or lefs heat the vesre- 
table receives, &c. A cereus being a plant of hot climates may 
bear more heat than an European plant. All thefe circum- 
stances, as well as many others, may make the ifl'ue of this, 
experiment Sometimes ambiguous ; but the fa£t, as 1 have re- 
lated it, joined to the above mentioned analogous experiments 
of 
