The chemical knowledge of Egyptian metallurgists and jewellers, he holds, was early transmitted to the artisans of Rome, and was preserved throughout the dark ages in the workshops of Italy and France until about the 13th century, when it was mingled with the theories of the Greek alchemists which reached the West by way of the Arabs.
Coins of foreign mints are generally submitted to examination by a committee of eminent chemists and metallurgists whose report is published in the official journals.
The reason why at this level the walls must form an upright instead of an inverted cone, why the furnace must widen downward instead of narrowing, is, according to some metallurgists, that this shape is needed in order that, in spite of the pastiness of the slag in this formative period of incipient fusion, this layer may descend freely as the lower part of the column is gradually eaten away.
The height of the furnace is rarely as great as roo ft., and in the belief of many metallurgists it should not be much more than 80 ft.
Many metallurgists were sceptical on theoretical grounds about his results, and only became convinced when they saw that his process was really able to convert melted cast iron into malleable iron in a perfectly fluid state.
They were still hunters, but had domesticated animals; they were fairly skilful metallurgists, casting bronze in moulds of stone and clay; they were also agriculturists, cultivating beans, the vine, wheat and flax.