It was decreed that putting mercury metal in the hands of the great
unwashed
( the public) was not a good thing:-)

I expect there's more mercury in the amalgam for a molar's filling than in
the capilliary tube of a max/min thermometer. Restrictions might be OK for
mercury barometers and some thermometers.

Pretty nasty stuff .-so use blue or red dyed alcohol as an alternative.

But the alcohol ones are useless! Hg's nasty perhaps but not highly
reactive.

I'm colour prejudiced in this, I want silver!!

It's about time the EU banned apple pips which contain arsenic and what
about rhubarb leaves full of oxalic acid then there's more dozens of garden
plants which are really nasty!

I also went down the same road. My next solution was to by a "spring" type
that works like a clock, there are 2 pointers which get moved clockwise
for max temp anticlockwise for min temp. There is a movable arm with which
these arms are "zeroed" whenever required. It works well and was cheap,
however I have doubt to its accuracy, as I am recording temperatures in
excess of 50 degC in my mini greenhouse. So electronic here I come.
However I am unable to source any locally (North Staffordshire) so I will
have to bite the bullet and pay postage.

Thanks for the last informative input. Why not check its accuracy with a
standard thermometer?

Thanks to all who answered.

Geoff