192 
• oso 
*= 61050 grains of carbonic acid, which gives =* 
82,85 cub. feet for 1 lb. and 82,85 x 2240 = 185,584 cub.' 
20881 
feet for 1 ton. For the mixed coal or 2,983 = 710 x 
100 =*= 71000 grains carbonic acid ; that is, —222 = 93 3 
761 
cubical feet'for 1 lb. and 93,3 x 2240 = 208,992 cubical 
feet for 1 ton. By the same calculation we may attain a 
pretty accurate notion of the quantity of atmospheric air ne- 
cessary to produce 1 lb. or 1 ton of cast iron ; an average of ! 
the three varieties of coal will be sufficiently accurate for 
this purpose ; thus 
14392 + 17094 -f 20881 
— — — 0 ■ = 174554 or 
2,4935 lb. of carbon are consumed upon the average of 
each pound of pig iron : this is found to produce of car- 
174 554; 
bonic acid gas - = 62*341 x 100 =» 62*30041 J 
* 28 
grains ; which again divided by 761, the grains in one t 
cubic foot, gives 81*86 cubic feet for the gas discharged t 
in manufacturing one pound of cast iron. As carbonic ( 
acid contains, as has already been noticed, 72 parts of 
oxygen in 100, then we have for the quantity of oxygen 1 
gas 100 : 72 : : 62300*41 : 44856*29 grains oxygen gas; 
and as, at the ordinary temperature and pressure of the at* 
mosphere, a cubic foot of oxygen gas weighs 591 grains, 
we find 44856*29 divided by 591 = 75*89 cubic feet 
of oxygen gas necessary to form the acidifying principle .1 
of 81*86 cubic feet of carbonic acid gas ; and that the r 
same quantity of oxygen gas is necessary to the produc- 
tion of one pound of carbonated crude iron. This leads 
us to the following statement for the quantity of atmosphe- 
ric air used during the same operation ; first premising 
that the constituent parts of atmospheric air are nearly 73 
of azote and 27 of oxygen gas ; of atmospheric air then 
necessary, we have 27 ; 100 » : 75*89 ; 281 cubic feet# 
