"213 
and apricots, may be preserved in close bottles, 
filled with air deprived of oxygen, for from twenty 
days to a month ; and pears and apples about three 
months, when they will afterward ripen perfectly 
by exposure to air. 
I have already mentioned, that some plants pro- 
duce oxygene in pure water. Dr. Ingenhousz found 
this to be the case with species of the conferva?. I 
have tried the leaves of many plants, particularly 
those that produce volatile oils. When such leaves 
are exposed in water saturated with oxygene gas, 
oxygene is given off in the solar light ; but the 
quantity is very small and always limited ; nor have 
I been able to ascertain, with certainty, whether 
the vegetative powers of the leaf were concerned 
in the operation, though it seems probable. I ob- 
tained a considerable quantity of oxygene in an 
experiment made fifteen years ago, in which vine 
leaves were exposed to pure water ; but on repeat- 
ing the trial often since, the quantities have always 
been very much smaller. I am ignorant whether 
this difference is owing to the peculiar state of the 
leaves, or to some conferva? which might have ad- 
hered to the vessel, or to other sources of fallacy. 
The most important and most common products 
of vegetables, mucilage, starch, sugar, and woody 
fibre, are composed of water, or the elements of 
^ater in their due proportion, and charcoal ; and 
these, or some of them, exist in all plants ; and the 
decomposition of carbonic acid, and the combin- 
ation of water in vegetable structures, are processes 
which must occur almost universally. 
When glutinous and albuminous substances exist 
p 3 
