Butterley Company, Ripley, Derbyshire, SK 399 517
The Butterley Company was established in 1790. Puddling ceased in Britain in 1976 (although possibly much earlier on this site).
A dense tapped? slag presumably produced during balling, i.e. consolidating a bloom of iron in a puddling furnace. Is this the same as cinder tap? The company provided the iron for the construction of many major buildings in Britain, such as St Pancras railway station.