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On the Proportions of Coals and Iron-Stones. 367 
precedent, unlefs ‘borrowed from thofe works where exactly 
the fame quality of coal is ufed. This analyfis alfo lays open 
part of the fource from whence originates the widely dif- 
ferent quantities of metal produced per week at various’ blaft- 
furnaces, and the great mpedprapersang of ore ufed to different 
coals. 
_ Experience has fhewn that the three qualities of coal jut 
mentioned, will {melt and give carbonation to the following 
proportions of the fame {pecies of torrefied iron-fione :— 
» 21212 \b. of clod-coal cokes will fmelt - - _ 130]b, 
r1i2]b. of fplint-coal cokes will fmelt —- -.. 1051b. 
112 lb. mixed foft and hard coal cokes will fmelt . 84]b. 
Let the iron-ftene be fuppofed in the blaft-furnace to yield 
40 per cent. then we find that the 1-20th of a ton of the re-— 
fpective qualities of cokes will fmelt and carbonate the fol- 
lowing proportions of iron, viz.—1121b. clod-cval cokes, 
130 1b. iron-ftone, at 40. per cent. = 52 1b. iron; 1121b. of 
fplint-coal cokes, 105 1b. of the ftone = 42 1b. of iron;, and 
112!b. foft and hard coal cokes, 84]b. of the iron-flone — 
= 33 & lb, of iron.» We then have for the quantity of metal 
produced by one ton of each quality of cokes : 
speGledscoall; 52 . X20 = 1040lb. 
fol %o .<1 Splint ditto. 42); X,20 =  84olb. 
os «> Mixed ditto, 68 B2er%Z04=,, 702 1b. 
This furnifhes a datum whereby we eafily obtain the quan- 
tity of the, various’ cokes neceffary, to produce 1.ton of car- 
bonated.crude iron bycommon proportion: for if 1c401b.— 
of metal are produced by 1 ton, or 22401b. of clod-eoal 
cokes, the quantity of the fame cokes requifite for the pro- 
duGtion of 1 ton; or 2240 lb. of metal, will be: rc. 9.14 
e 80. 4824°6lb. =2 3.08 
Splint-coal cokes) $402.2240 :3,2240: 5973°3lb. = 2 1g Ig 
. Mixed ditto 902462240 332240: 7147°51b. = 3.53.39 
» If to the quantity of cokes neceflary to manufacture 1 ton 
of crude ivon, we'add the quantity of volatile, matter driven 
off in the procefs of charring, which may be thus eftimated 
upon the ayerage of each quality.; oa 
5 
Clod,coal 2.07 37 |-per c. produce in cokes $ @ 62%. per ¢. 
Splint coal + — 50 £08 0% 's 
Mixed coal 3 — 62,5 ———— 3 39% 
Then, 
