TRON MANUFACTURE. 539 
matter, owing to the large amount of gas and volatile matter expelled 
from the coal, which loses thus 30 to 40 per cent. of its weight. It is 
well to observe, however, that while the gas is thus increased in heating 
power and value as a fuel, it is not largely increased in volume. To 
illustrate this, suppose a pound of average Brier Hill coal burned in 
the blast furnace, it would lose about 40 per cent. at the top of the fur- 
nace, representing tar, gas and water. ‘The 60 per cent. coke left, 
which alone acts as fuel, will equal probably 56 per cent. carbon. 
This 0.56 pound of carbon will require 3.23 pounds, or about 44 cubic 
feet of air for its combustion at the tuyeres to carbonic oxide, and no 
matter how much carbon it may take up from ore and limestone, will 
represent at least 53 cubic feet of gas at the throat, assuming each 
volume of oxygen to make two volumes of carbonic oxide. 
vy Three determinations made recently on samples of very dry burning 
coals, showed an average «f about 3.7 cubic feet gas of to the pound; this 
is higher than the Brier Hill coal would yield, as the coals examined 
contained more volatile matter ; even assuming the gas produced to be 
4 cubic feet, the point is clear that ,the volume of the gas from a fur- 
nace using raw coal will not be more than one-twelfth greater than if 
the furnace was using the coke the coal used would produce; a fact 
which should settle, once for all, the question of different lines for coal 
furnaces, because of the large volume of gas! 
The 53 cubic feet of gas considered above as furnished by the 
burning of the coke from 1 pound of coal, supposing it to do its full 
work in the furnace (supposed to be using 3.2 tons of coal to make 1 
ton of iron) in the way of reduction, would have at the throat of the 
furnace about the following composition by weight: 
IN EROGTEME rake. loceenest eee seeete ee: ecete cacwets sects ontie cee scadtorses set eesscapeeese es 63.0 
WAT OMI CTO KAG Cees sere ee ete Toes te oan tate On Seen shee Sede EY aE a eee OMI 
WanlbomiCqaC Perret ces eer ca clneecninc einicord oa cldeeistle se sn ce Neue eho bac aNee ows 9.3 
100.0 
Its calorific power would be 665., or one hundred cubic feet of such 
gas would heat nearly 50. pounds of water from zero to boiling, assum- 
ing the mean specific gravity of the gases at 1.02. Adding now to the 
above gas the volatile matters from the coal (3.7 cubie feet having a 
specific gravity of about 0.6), the composition by weight would be nearly 
as follows: 
