271 
Quantity of Carbon in carbonic Acid. 
These slips were put into small crucibles, and completely 
covered with dry sand. Heat was very gradually applied at 
first, until the volatile parts were dissipated ; they were then 
kept about 40 minutes in a white heat. On being collected 
and weighed, while still warm, the charcoal from each was as 
follows : 
Fir, 
54,5 grs. equal to 18,17 
Lignum Vitae, 
138 
- 
Box 
81 
- 
20,25 
Beech 
75 
- 
15 
Oak 
43 >5 
- 
i7>4° 
Mahogany 
3L5 
- 
1575 
These being exposed to the air during one week, increased in 
weight thus : 
Fir, - - 13 per cent 
Lignum Vitae, 9,6 
Box 14 
Beech - 16,3 
Oak -- - 1 6,5 
Mahogany 18 
Certain quantities being confined in common air increased very 
little in weight, and all in the same proportion ; we are there- 
fore much inclined to think that this increase is owing to an 
absorption of water from the air; and we repeatedly found 
that the greatest increase of weight took place in the first hour 
or two after exposure, and arrived at its maximum in less than 
24 hours, as the following experiment, selected from several 
others, will prove. 
40 grains of charcoal from willow wood, which had been put 
into a bottle with a ground glass stopper immediately after they 
N n 2 
