STRUCTURE OF WOOD,, &C. 
90 
Hence we may conclude, that a cubic inch of this old wood Quantities of 
was composed of moisture aud 
Ligneous parts . . . . . 0‘39/94 cubic inch. 
Water. 0’0718S 
Air 053020 
volatilematttr 
in wood. 
1-00000 
We may also conclude from these results, that the wood of 
the centre of a large oaken post, though kept for ages out of the 
reach of the rain, can never contain, in our climate, less than 
10 per cent, of its weight in water ; and that a cubic inch of 
such wood contains more than half a cubic inch of air. 
Th e yearly medium temperature at Paris is about 54 F. : 
now as we have just seen that the habitual state of dryness in 
woods at the temperature of 52° F. is such as to give about 
11 per cent, of water for 100 parts of wood ; we must not be 
surprised at finding 10 per cent, of water in the interior of a 
large beam, after it had been sheltered from the rain during 
150 years. 
To ascertain whether the property of wood to attract mois~ 
ture from the atmosphere was augmented or diminished by the 
beginning of carbonisation, I made the following experiments. 
Fourteen grammes of ash shavings, after being highly dried 
on a marble slab over a chafing dish, were exposed to the air, 
in the month of February, in a large room, whose temperature 
was about 20® F. and in 15 hours they had gained 1 '65 
grammes in weight. 
Fourteen grammes of the same sort of shavings having been 
first scorched in the stove till they had assumed a brown co.lour, 
were at the same time dried over the chafing-dish, and exposed 
w ith the others to the cold air, for the same length of time ; but 
they gained in weight only 1 -01 grammes, while those which 
had not been scorched, as already stated, had gained 1(35 grs. 
Fourteen grammes of the shavings of lime-wood, in then- 
natural state, and 14 grammes of the same kind of shavings, 
after they had been violently scorched in the stove, were dried 
(together over the chafing-dish, and then exposed in the open 
-air, at the temperature of 40® F. for 15 hours. The shavings 
; H 2 in 
