When limonite is dehydrated and deoxidized in the presence of carbonic acid, it may give rise to chalybite.
The iron oxide of which the ores of iron consist would be so easily deoxidized and thus brought to the metallic state by the carbon, i.e.
Moreover, the coals which deoxidized the iron would inevitably carburize some lumps of it, here so far as to turn it into the brittle and relatively useless cast iron, there only far enough to convert it into steel, strong and very useful even in its unhardened state.
The oxide ores of copper would be deoxidized by the savage's wood fire even more easily than those of iron, and the resulting copper would be recognized more easily than iron, because it would be likely to melt and run together into a mass conspicuous by its bright colour and its very great malleableness.
These two things are done simultaneously by heating and melting the ore in contact with coke, charcoal or anthracite, in the iron blast furnace, from which issue intermittently two molten streams, the iron now deoxidized and incidentally carburized by the fuel with which it has been in contact, and the mineral matter, now called " slag."