Metallic mercury is used in schools and research laboratories, in medi
cal and scientific departments, in dental surgeries and as a cathode i
n the electrolysis of brine.(1,2) In ophthalmic theatres it is used in
weights which are placed over the eye after a local anaesthetic injec
tion is administered. It is volatile and therefore spilt droplets can
pose a hazard to health, especially in a confined space.