‘Tron-Stones ufed at the Blaft-Furnace. 37% 
of caft iron. As carbonic acid contains, as has already been 
noticed, 72 parts of oxygen in 100, then we have for the 
quantity of oxygen gas 100: 72 :: 62300°41 : 44856°29 
grains oxygen gas; and as, at the ordinary temperature and 
preffure of the atmofphere, a cubic foot of oxygen gas weighs 
591 grains, we find 44856'29 divided by 591 = 75°89 cubic 
feet of oxygen gas neceflary to form the acidifying principle 
of 81:86 cubic feet of carbonic acid gas; and that the fame 
quantity of oxygen gas is neceflary to the production of one 
pound of carbonated crude iron. This leads us to the fol- 
lowing ftatement for the quantity of atmofpheric air ufed 
during the fame operation; firft premifing that the confti- 
. tuent parts of atmofpheric air are nearly 73 of azote and 
27 of oxygen gas; of atmofpheric air then neceflary, we 
have 27: 100:: 75°89 : 281 cubic feet. 
I fhall now proceed from mere calculation to matter of 
fact, and attempt to prove the correétnefs of the former by 
the approximation of the latter to its refults. Let a blaft- 
furnace be fuppofed to produce.202 tons of pig-iron per week, 
= 45360 averdupoife pounds; this, divided by days, hours, 
-*minutes, and feconds, gives per day 6480 pounds, per hour 
270, per minute 44 ]b., and perfecond 525 grains. 
From this it is evident that 1b. of caft iron is produced 
in 13 13, feconds: experience has fhewn that a blaft-furnace, 
_ producing, in any of the above periods, the refpeétive quan- 
tity of metal, requires a difcharge of air per minute nearly 
equal to 1350 cubic feet; this, divided by 4,5 lb., the quan- 
tity produced per minute gives, for 1 1b. iron, 300 cubie 
feet. The quantity, by calculation, we have feen to be 281 
cubic feet—difference 19: a fum no. way confiderable when 
we refleét upon the inequality of the movements of a blowing 
machine, and when it is recollected that fome allowance 
ought alfo to be made for what air may pafs through the 
furnace undecompofed, or may be loft at the place of en- 
trance. 
From this coincidence of theory with practice, we cannot 
help admiring the rigorous principles on which the Lavoi- 
ferian fyftem is founded ; nor are we lefs pleafed to find, that, 
fmall as the operations of the chemift may be, yet they are a 
3B2°- jutt 
