436 Dr, iNGEN-riousz on the Influence of the 
If it was the water, and not the plant, which yielded the 
dephlogifhcated air, the quantity of air obtained would bear, 
m general, a proportion to the quantity of the water employed-; 
but this is by no means the cafe. The quantity of air bears a 
proportion to the bulk of the vegetable much more than to the 
quantity ot the water. This is very eafily to be obferved with 
iome ot the above mentioned American plants. It ought to be 
always obferved, that if too many leaves are crowded together, 
they thade one another too much ; and therefore, in this cafe, 
the quantity ot air obtained w T ill be proportionably lefs, and its 
quality worfe. 
Again : it the dephlogifhcated air, obtained from plants in 
water, was air difengaged from the water, it would follow, 
that a plant limit up in a tranfparent glals veffel without any 
watei would yield no air at all, nor increafe the quantity of 
air lhut up with the vegetable. The following experiment, I 
think, will be lufficient to convince any one that this is far 
tioin being the cale. I placed in a glafs tube, hermetically 
teakd at one end, a piece of an American plant, called cereus ; 
i!ie extremity of this piece, where it was cut from the plant, 
WJS ^ghtly lqueezed in a fmall glals veffel, in which only as 
much water was kept as feemed to be required to keep the 
cereus i n f-hl vigour. I fmeared the vegetable, and the orifice of 
the g'ia^ vcfiel ah around with foft wax, fo that all communica- 
tion between tne air within the tube and the water within the 
Jmall veliel was cut ofr. I placed this tube inverted in a vefifel 
hlleci with quickfilver, keeping a column of lome inches of 
rkana gives fuch a prodigious quantity of 
i often got from one Angle leaf abov 
JM ' quality. The anHus triangularis , 
owners give no I c f s 3 j r , 
dephlogiflicated air, that, in a fair day, 
e 150 cubic inches of this air, of the 
cereus , fe/npervivum arbor urn , and many 
3 
the 
