It is about the size of a thick wash-rag, and the puddler carries it in the hand that clasps the rabble rod where it is too hot for bare flesh to endure.
The melted iron contains carbon, sulphur and phosphorus, and to get rid of them, especially the sulphur and phosphorus, is the object of all this heat and toil.

For it is the sulphur and phosphorus that make the iron brittle.

And brittle iron might as well not be iron at all; it might better be clay.

For a good brick wall is stronger than a wall of brittle iron.

Yet nature will not give us pure iron.