A piece of wrought iron, or mild steel or copper, if torn asunder shows long lustrous fibres, resembling a bundle of threads in appearance.
Ingot metal or mild steel was sometimes treacherous when first introduced, and accidents occurred, the causes of which were obscure.
The reinforcement mostly consists of mild steel and sometimes of wrought iron: steel, however, is stronger and generally cheaper, so that in English practice it holds the field.
For ductile iron or mild steel it may be taken as 1.5.
Wrought iron and mild steel may be made to show a short and crystalline fracture by a sudden application of stress, while if drawn asunder slowly they develop the silky, fibrous appearance.