No. 161.] 
49 
That the proper adjustment of the flux to the nature of the ore, is 
a subject not yet sufficiently attended to by our iron smelters, I think 
is evident from an examination of the scorios of many of our fur- 
naces. Small globules or buttons of nearly pure iron, or of the 
metal slightly oxidated, are sometimes found in the hard and glassy 
compound, and by treating this refuse with additional portions of 
flux, a large proportion of metallic iron is obtained. The conduc- 
tor of a furnace in Dutchess county, observed to me that a heap of 
this slag, which he had considered as without value, and which 
he intended to have removed from his premises at some expense, 
he had recently found to be worth more than $3,000 for the iron 
which it contained. 
It has already been stated that the nature and proportion of the 
flux most proper to be employed in any given case, cannot be posi- 
tively determined without an analysis of the ore. Berthier gives 
some general directions on this subject, which it may be useful to 
introduce in this place; and especially so, as his statements are the 
result of an extensive series of experiments. According to this 
chemist, the proportion of flux to the ore necessary to ensure the 
requisite degree of fusibility, should be such as that the compound 
may contain from 45 to 60 per cent of silica, 20 to 35 per cent of 
lime, and 12 to 25 per cent of other earths. The nature of the 
latter has a great influence upon the fusibility of the scoria. Alu- 
mina is the least fusible, and it should not much exceed the pro- 
portion of 0.15. Magnesia is much more fusible, and it may at- 
tain the proportion of 0.25 without inconvenience. But when 
other metallic compounds form part of the ore, as manganese, ti- 
tanium, phosphate of iron and of lime, the arseniates of iron, iron 
pyrites, galena, blende and chromium, the proportion of fluxing 
materials must be determined by their nature and by the propor- 
tions in which they exist in the ore.* 
In regard to fuel, and its mode of employment, there is also 
room for improvement in our manufactories. Charcoal, the com- 
bustible almost exclusively employed at present, no doubt possesses 
great advantages, but the want ol due attention to the process of 
carbonization, renders this substance of very variable purity. — 
This not only increases the expense, but causes a variation in the 
degree of heat quite unfavourable to the success of the iron smelt- 
* Traits des Essais par la Voie Seche II. 339. 
[Assem. No. 161.] 7 
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