Chiropodists, until fairly recently used silver nitrate pencils to cure corns.
They called it lunar caustic.
But then I had a retired GP on a course recently who told me in his early days
in practice it was not unusual for him to prescribe mercury for internal use !
The point is that one tries one's hardest to underline to students that they
should treat all chemicals with respect. Even water, which is a chemical, can be
toxic, as we have seen from the deaths arising from dropping 'E' s.
Terry King