He puddled his own soul till the metal was pure, and that's how he got the Iron Will that was strong enough to save a nation.
My purpose in slackening my heat as soon as the pig-iron was melted was to oxidize the phosphorus and sulphur ahead of the carbon.

Just as alcohol vaporizes at a lower heat than water, so sulphur and phosphorus oxidize at a lower heat than carbon.

When this reaction begins I see light flames breaking through the lake of molten slag in my furnace.
Probably from such a sight as this the old-time artists got their pictures of Hell.

The flames are caused by the burning of carbon monoxide from the oxidation of carbon.

The slag is basic and takes the sulphur and phosphorus into combination, thus ending its combination with the iron.