Lead poisoning in both its acute and chronic forms has been recognised since the 
second century BCE. Lead colic, anaemia, renal tubulopathies and motor 
neuropathies are well recognised. This paper sketches the early history and 
remembers the important contribution of Henry Burton, who described the gums to 
be bordered by a narrow leaden-blue line, about the one-twentieth part of an 
inch in width, whilst the substance of the gum apparently retained its ordinary 
colour and condition. The sign though inconstant, is still a valuable clinical 
clue.