Did it once in a school physics lesson! long Soda Glass tube sealed one end over Bunsen burner, and filled with mercury, thumb over end and inverted in a bowl of mercury - all with bare hands.
Can you imagine the modern health and safety police allowing that! OK we had many imprecations about keeping the tube straight and not breaking it, but the mercury wasn't a concern !
Nowadays I very much doubt if the little darlings are allowed naked flames and hot glass never mind baths of Hg !!!!