396 Miscellanies. 
an iron cap—which cap must be removed at each successive empty- 
ing and filling of the pit—some tubes leading from the top of the 
ground to the bottom of the pit served as vents. From the nature 
of this construction, it is evident that the size must necessarily be lim- 
ited to a very few cords of wood—say five or six at most.—This 
size might-answer very well for the extraction of pyroligneous acid, 
to which purpose M. de la Chabeaussiére applied his kiln—or for a 
blacksmith who consumes but a-small quantity of coals; but would 
be no more than a plaything in works where the daily consumption 
is from one thousand to fifteen hundred bushels or more. 
It occurred to me that, by 
building kilns above ground, 
so that all the vents could be 
come at with facility, and [j= 
arching the top over in the AMI) jin ha 
form of a dome, leaving one if 
or more openings in the side 
for the admission of wood 
and the. extraction of coals, 
{which are closed during the 
operation of charring,) they it a 
might be constructed of al Simm ithe 
most any size that might be = 
esirable. The result of the 
experiment justified my most 
sanguine expectations. A 
kiln of thirty feet diameter, 
and nine feet high to the 
spring of the arch, and which ) 
holds fifty cords of wood, has 
been several times filled and 
charred, and has uniformly 
yielded from fifty five to sixty 
bushels of coals to the cord,* 
of a quality, far, very far su- 
_ perior to coals made in the ordinary way. From the manner of 
- making these coals, they must bé entirely free from stones and dirt, 
====—=s=9=—===== 
I 
Ve phi 
* Colliers, in the woods, usually compute the yield of coals atthe rate of one hun- 
: to two and a half cords of wood, or forty bushels te the cord—but I be- 
18 a general average, one hundred bushels to three cords of wood, would 
