Tron-Stones ufed at the Bla/t- Furnace. 377 
ftone yield of torrefied ftone 45 per cent. its produce will be 
162tb. or 4olb. more than the former. “As there exifts no 
greater proportion of carbon in the furnace, it is evident 
that the exifting quantity, being diftributed over nearly — 
1-3d of more metal, muft therefore be in more {paring quan- 
tity in the whole, and the value of the metal confequently 
reduced. 
3. The weight of oxygen contained in iron-ftones is the 
next obje&t of ferious confideration. I have already fhewn, 
from experiment, that our iron-ftones naturally contain from 
9 to 14 per cent. of oxygen, which remains after torrefaction 5 
it, has alfo been fhewn, that this quantity of hurtful mixture 
may eafily be doubled by over-roafting or under-roafting the 
ftone; and that the bad effects entailed are in the ratio of its 
combination with the iron. From a review of the faéts ad- 
duced on this fubject in various parts of my papers, its agéncy ° 
and effects will eafily be credited by men of feience ; its pro- 
perty of conftituting the acidifying bafe of all the acids rea- 
dily explains the unalienable confequence of its prefence with 
acidifiable bafes. The effects are ftill more pernicious when 
the oxygen is furnifhed by the decompofition of water in 
raw iron-ftone; the hydrogen in this cafe fet free, alfo feizes 
a portion of the carbon; and thefe abftractions, united to that 
produced by the native portion of oxygen in the ftone, form 
an aggregate which frequently reduces the value of iron 40 
per cent. So long as the principles of feience are overlooked 
in the manipulations of the foundry and forge, the exiftence 
of fuch agents will be treated as chimeras of the philofopher 
and chemift, and the effeéts hourly produced: by them in- 
duftrioufly attributed to caufes which in point of unity or 
confiftency will not bear the flizhteft touch of inveltiga- 
tion. 
Vou. V. 3C XY A new 
