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subject I shall discuss in the next Lecture, as it 
follows naturally another series of facts relating to 
the effects of lime in the soil. 
It is evident from the analysis of woody fibre by 
MM.GayLussac and Thenard, (which shows that 
it consists principally of the elements of water and 
carbon, the carbon being in larger quantities than 
in the other vegetable compounds,) that any pro- 
cess which tends to abstract carbonaceous matter 
from it must bring it nearer in composition to the 
soluble principles ; and this is done in fermentation 
by the absorption of oxygene and production of 
carbonic acid ; and a similar effect, it will be 
shown, is produced by lime. 
Wood-ashes imperfectly formed, that is, wood- 
ashes containing much charcoal, are said to have 
been used with success as a manure. A part of 
their effects may be owing to the slow and gradual 
consumption of the charcoal, which seems capable, 
under other circumstances than those of actual 
combustion, of absorbing oxygene so as to become 
carbonic acid. 
In April, 1803, I inclosed some well burnt char- 
coal in a tube half filled with pure water, and half 
with common air; the tube was hermetically sealed. 
I opened the tube under pure water in the spring 
of 1804, at a time when the atmospheric tempera- 
ture and pressure were nearly the same as at the 
commencement of the experiment. Some water 
rushed in ; and on expelling a little air by heat 
from the tube, and analysing it, it was found to 
contain only seven per cent, of oxygene. The 
water in the tube, when mixed with lime-water, 
s 2 
