106 
STRUCTURE OF WOOD, &C. 
Manner of 
the experi- 
ments ior 
ascertaining 
the heat fro 
charcoal, 
very dry : and as the persons alluded to have neglected to 
determine the quantities of absolutely dry wood burned by 
them, much uncertainty prevails in the results of all their 
n experiments. 
Another source of uncertainty lies in the great quantity of 
heat suffered to escape with the smoke and other products of 
the combustion. 
As the calorimeter used in my Experiments, has been describ- 
ed in a memoir which I had the honour to present to the cla-is 
on the 24th of February, IS, 12 , it is unnecessary here to 
resume that subject •' suffice it to explain, in a few words, the 
various precautions I adopted in burning wood under the 
calorimeter. 
I picked out the woods intended for the experiments, from a 
joiner’s workshop, and they all appeared to be quite dry ; I bad 
them formed into small boards, six inches in length, and half an 
inch thick ; from these boards T had some shavings planed off, 
about 1 -lOth of a line thick, half an inch broad, and 6 inches in 
length. 
When these shavings were sufficiently dry, they were burn- 
ed, one by one, under the mouth of the calorimeter ; and I took 
care to hold them, by means of a small pair of nippers, so as to 
make them burn with a brisk flame, and without the least 
smoke, or smell, or calculable residuum in ashes. 
The following is the method I pursued in making these 
experiments. 
The calorimeter, filled with water at a temperature of about 
5 ° of Fahrenheit’s thermometer, lower than that of the apart- 
ment in which the experiments were made, was placed upon its 
stand at the height of about 13 inches above the table on which 
the apparatus was laid. 
The extremity of the calorimeter, containing the opening, 
which I call its mouth, projects about 4 inches beyond the edge 
of the stand, so as easily to admit the point of the flame from 
the small piece of burning wood 3 and the height of the stand is 
so adjusted, that the operator may rest both his elbows on the 
table, while his hands sustain the fragment of wood to be burned. 
Near the calorimeter stands a small lamp, by which the pieces 
of wood, or rather shavings, may,without loss of time, be set on 
fire, and burned in succession : and care is taken to have always 
