MANUFACTURE OF IRON. 
43 
he had considered as without value, and which he intended to have removed from his pre¬ 
mises at some expense, had been found to be worth more than $3,000, for the iron which it 
contained. 
I have already observed, that the nature and proportion of the flux most proper to be 
employed in any given case, cannot be positively 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 expe¬ 
riments. 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. Alumina is the 
least fusible, and it should not much exceed the proportion of 0.15. Magnesia is much more 
fusible, and it may attain the proportion of 0.25 without inconvenience.- But when other 
metallic compounds form part of the ore, as manganese, titanium, 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 proportions 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 combustible almost exclusively employed at present, no doubt 
possesses great advantages ; but the want of 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 smelter’s 
operations. In those cases, by no means unfrequent, where the proprietors of iron works 
have also under their control the manufacture of charcoal intended for their use, it would be 
greatly to their advantage to introduce some of those improvements which have been adopted 
in England and France, and the value of which experience has fully confirmed. 
Although charcoal is perhaps the best fuel for the iron furnace, it is well known that causes 
are gradually, though constantly, operating to diminish the supply, and of course to increase 
its price. In some cases this already begins to act as a damper upon the manufacture in 
question. The same difficulty was experienced in England at a very early period, when it 
was fortunately ascertained that the bituminous coal, which abounds in that country, when 
converted into coke, might be substituted in the place of charcoal. And it is to this discovery 
that England is chiefly indebted for the commanding position which she now occupies as a 
manufacturing nation. In this country, various attempts have been made to substitute anthra¬ 
cite for charcoal, in iron smelting; which at length, by the employment of the hot blast, have 
been crowned with complete success. This great improvement in the manufacture of iron, 
however, will be of more value in those States where anthracite is found, than in our own; 
but it cannot fail, even here, to be highly beneficial.t 
* Traite des Essais par la Voir Seche, II. 339. 
t I have just received a small work, entitled “ Notes on the use of Anthracite in the Manufacture of Iron," by Prof. Walter R. 
Johnson ; to which I would refer those who are interested in this subject. 
