m 
Iron o 
The advantages that charcoal possesses, beyond those 
of pit- coal, for the manufacturing of crude iron, are deriv- 
ed from the purity of its component parts, and the supe- 
rior quantity of unalloyed carbon it affords to the iron. 
This principle is presented to the metal free from the com- 
bination of clay, lime, sand, and sulphur ; with which 
pit-coal frequently abounds. A determinate quantity of 
charcoal by measure, will smelt and convey principle to 
three times the quantity of iron that can be done by the 
same measure of pit-coal coaks. Its greatest and most 
useful property, however, seems to be developed in the 
refinery fire, and similar bar-iron operations ; where it! 
manifests in the most evident manner its superiority over 
pit-coal, by shortening the tedious processes of the forge, 
diminishing the \ waste, and affording a much superior 
quality of iron for all the purposes of sub sequent manu- 
facture. Thus far Mushet. 
Wood in charring loses somewhat of its bulk : by 
means of the heat applied, the acid moisture is distilled 
away, together with some part of the resinous and carbo- 
nic principle of the wood, but the w T oody fibres consisting 
chiefly of carbon or pure charcoal remain, and the vascu- 
lar part now emptied of the fluid contents, form the pores 
of the charcoal. Of these Dr. Hook counted 150 in the 
eighteenth part of an inch in length ; hence he concludes 
that in an inch square of charcoal there are 5,724,000 
pores. 
As there are great variations in the weight of wood, 1st. 
as to the kinds, 2dly. as to the time when it was cut, 
3dly. as to the length of time it has been exposed to the 
atmosphere, 4thiy. as to the part of the tree from which it 
is cut, no certainty can be obtained as to the proportion of 
charcoal by weight obtained from various wx>ods : I 
think the charcoal according as it is well or ill burnt, va- 
ries from a third to a fifth of the weight of the dry wood 
from whence it was made. 
