IRON MANUFACTURE. 545 
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This is based on a number of analyses made of the ashes of the 
Hocking Valley coals, both by Prof. Wormley and the present chemist 
of the Survey. The composition is quite similar to that of the silicious 
matter of the limestone, consisting essentially of a mixture of alumina 
and silica in the proportion of 3 to 5. In regard to the amount of this 
ash introduced into the furnace in smelting with raw coal it is about as 
follows: Assuming the consumption to be 3 tons of coal to the ton of 
iron, and taking the average of a number of analyses of the coal already 
given, we find the percentage of ash to be 4.5; three times this represents 
the amount on the iron made, and taking the consumption of ore per ton 
of iron as 2.1 tons, the coal ash amounts to 6.4 per cent. of the ore used. 
The importance of this coal ash, however, as a slag forming element, is 
greater than the mere amount of silicious matter that it introduces, 
owing to its containing so large a percentage of alumina, the effect being 
to increase very decidedly the amount of this element in the slag. 
Assuming the foregoing statements, two points of interest appear ; 
first, what kind of slag is produced ; and second, what role do the coal 
ashes play in its formation. | 
Most of the furnaces at present use but a portion of native ore ; 
however, the following record, where mill cinder is the only addition, 
will be taken as a basis for calculation. The figures represent three 
weeks’ run of a raw coal furnace: 
Charges. Tons. 
pall Perret ners sccta scar aice tance cencaevenaearstnscsseleeiesesesersesressieess' 1024 
IN ENVICTONG: cree scscuccnisattGessasccstreddsecesccec eters Lgdadsecsesasdscsescesicesetenees 434 
Mill cinder .......... A Ah ot GG AUC GSOCORCROASCR Coo DORE COD EATE GOCE EEC REC MEET eer 243 
EIT ESE ONO Seecy er see ee cecelttticedne os os due dtolotecmees REM atecs toe heat cn canee sedeae sae A427 
Iron produced seeececenceeebeseecesenseceessnnesssessesaaseeseeesceersceeeeseesconsneess 323 
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IMG Gaye vere JHOTP WHANE) {HOTA OIE WRIA G000600c11000000 1600, GbOdHCO COSOOC ONE OHACOOUGOECOEGD 15 
