Three bars of mild steel, tied cold, at the Steel Company of Scotland's Works, Glasgow, manufactured by Siemens' process, 1885, communicated by J. Riley

Three bars of mild steel tied cold at the Steel Company of Scotland's works, Glasgow, 1885.They were maufactured by the Siemens' process. The knot shows the great ductility of mild steel manufactured by the open hearth process.This now obsolete process used a dish shaped hearth where cold pig iron and steel scrap were charged and then melted by preheated gases with flame temperatures up to 1750 degrees C. These temperatures were produced by regeneration as the gases were first passed through preheated bricks.The heat in the bricks was maintained by periodic reversal of the entry and exit gases.