14 | Stridturee on Mr. Collier's 
ftones; in common £ to 4 or 5 is ufed, and where Camber- 
Jand or Lancafhire ore is fmelted in contact with wood- 
charcoal, ',th wili abundantly fafiice. 
From Mr. Collier’s defcription, a perfon seipmaliae in the 
mode of conducting blaft furnaces would be apt to con- 
ceive that the furnace was firft charged, and then kindled to 
effect reduction: this of courfe conveys an idea that fre- 
quent filling and kindling are neceffary. The furnace is 
firft fufficiently heated with coal cinder alone ;° the charging 
then commences, and continues hourly for a great length 
of time—two, three, and four years: inflances have been 
of a furnace continuing to finelt, without much interrup- 
tion, for nine years. 
The mention of bellows is a proof how deficient Mr. Collier’s 
information has been refpecting the prefent general ftate of 
machinery attached to iron works. Excepting a very few 
charcoal furnaces, all the blaft furnaces in Britain are fup- 
plied with air from caft-iron cylinders of various dimenfions, 
conftructed on various plans. The compreffion of air from 
thefe is greater than could poflibly be obtained by means of 
bellows, more fit for combutlion, and capable of fupporting 
a column of mercury of fix inches, which is,equal to 6,784 
feet of water. By fuch a heavy compreffion of air, 1500 to 
1800 cubical feet will pafs through the difcharging pipe into 
the furnace in one minute, when its diameter does not ex- 
ceed 23 or 3 inches at moft. 
Mr. Collier writes with more information on the manu-. 
faturing of bar iron. Still however he does, not diftinguifh, 
with iE Genk accuracy, between the various procetles. The 
feeond method he defcribes is only followed out where bar 
iron is manufactured with charred wood: the efveéts produced 
by the ufe of wood-charcoal are fo material, that they un- 
doubtedly merited to be mentioned, and particularly diftin- 
guifhed from thofe of charred or raw pit-coal. 
One of the principal operations, well known by the name 
of the Puddling Procefs, is very flightly noticed,. and in a 
. manner 
