94 
Iron . 
various ; but char of hard wood, such as oak, birch, ash, 
See. See. was always preferred to that made from pine, 
holly, sallow, Sec. Sec. At the small remaining number 
of charcoal furnaces now in this country, the oak has still 
the undoubted preference. Its firmness and continuity 
enable it in the blast-furnace to support and convey prin- 
ciple to the iron contained in a larger portion of ore, than 
charcoal made from softer wood. The same properties 
also enable it for a time to sustain a heavier pressure of air 
from the discharging pipe : this facilitates the reduction 
of the whole, and greatly augments the weekly produce 
in iron. The mode of preparing charcoal of wood for 
the blast-furnace, though extremely simple, is yet capa- 
ble of being greatly misunderstood, so as to occasion a 
considerable waste of wood in the process. The follow- 
ing is the detail of an operation which I have seen success- 
fully tried, and which was productive of excellent char- 
coal. It is the same I believe as is followed at the two 
charcoal furnaces in Argyleshire. 
First of all, a plot of ground is raised a little higher than 
the surrounding surface : this is made slightly convex. 
The burner commences by placing in the centre a circle 
of sticks, transversely inclining, and crossing each other 
near their tops. Around these are built successive cir- 
cles of wood of various sizes, from 1 to 10 inches diame- 
ter ; but care is always taken to place those of similar di- 
ameters in the same circle. A round of beams, of the 
largest nature, is immediately followed by one so much 
smaller as to fill up the interstices between the larger di- 
ameters, that no more air may be admitted than is neces- 
sary to excite gradual combustion. These are again 
followed by pieces of an increasing diameter. This mode 
of ranging the large and small sizes is continued till such 
time as the pile is deemed sufficiently large. The total 
width may then measure from 20 to 30 feet. The last 
