"Roland Perry" wrote in message
...
In message , at 18:30:37 on Mon, 18 Jul 2016,
tim... remarked:
It's every much the same sort of thing: banning a commodity because it's
harmful/unethical or whatever.

There is a mile of difference between unethical and harmful, especially
when in normal use the item isn't harmful at all, it's only harmful if
it's abused.

Ivory hunting is harmful to elephants.

I was referring to the mercury instrument (I thought that was bleeding
obvious)

tim

In message , at 10:25:58 on Tue, 19 Jul
2016, tim... remarked:

It's every much the same sort of thing: banning a commodity because
it's harmful/unethical or whatever.

There is a mile of difference between unethical and harmful,
especially when in normal use the item isn't harmful at all, it's
only harmful if it's abused.

Ivory hunting is harmful to elephants.

I was referring to the mercury instrument (I thought that was bleeding
obvious)

The problem with mercury is that even if not "abused" (whatever that
means) it has a tendency to get split, and when it does the tiny
droplets run everywhere and are very difficult to clean up.
--
Roland Perry

"Roland Perry" wrote in message
...
In message , at 10:25:58 on Tue, 19 Jul 2016,
tim... remarked:

It's every much the same sort of thing: banning a commodity because
it's harmful/unethical or whatever.

There is a mile of difference between unethical and harmful, especially
when in normal use the item isn't harmful at all, it's only harmful if
it's abused.

Ivory hunting is harmful to elephants.

I was referring to the mercury instrument (I thought that was bleeding
obvious)

The problem with mercury is that even if not "abused" (whatever that
means) it has a tendency to get split, and when it does the tiny droplets
run everywhere and are very difficult to clean up.

thermometers are sealed units

(I have no idea about barometers, but assume likewise)

tim

In article ,
"tim..." wrote:

thermometers are sealed units

(I have no idea about barometers, but assume likewise)

There may be sealed versions but the point about a mercury barometer is
that it's influenced by atmospheric pressure and the most basic version
is an open dish with a long tube immersed in it. I'd guess old versions
are most likely to have mercury open to the atmosphere.

Sam

--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

"Sam Wilson" wrote in message
...
In article ,
"tim..." wrote:

thermometers are sealed units

(I have no idea about barometers, but assume likewise)

There may be sealed versions but the point about a mercury barometer is
that it's influenced by atmospheric pressure and the most basic version

oh yes

how silly of me :-(

tim

tim... wrote:

"Roland Perry" wrote in message
...
In message , at 10:25:58 on Tue, 19 Jul 2016,
tim... remarked:

It's every much the same sort of thing: banning a commodity because
it's harmful/unethical or whatever.

There is a mile of difference between unethical and harmful, especially
when in normal use the item isn't harmful at all, it's only harmful if
it's abused.

Ivory hunting is harmful to elephants.

I was referring to the mercury instrument (I thought that was bleeding
obvious)

The problem with mercury is that even if not "abused" (whatever that
means) it has a tendency to get split, and when it does the tiny droplets
run everywhere and are very difficult to clean up.

thermometers are sealed units

(I have no idea about barometers, but assume likewise)

Barometers measure atmospheric pressure, so they have to be open to the
atmosphere to do this.

--
Jeremy Double

tim... wrote:

"Roland Perry" wrote in message
...


The problem with mercury is that even if not "abused" (whatever that
means) it has a tendency to get split, and when it does the tiny droplets
run everywhere and are very difficult to clean up.

thermometers are sealed units

Until they get broken, like the one in my dad's greenhouse which I used to
push the droplets around the wooden shelf with a long nail.


(I have no idea about barometers, but assume likewise)



The mercury column needs to be open to air pressure, but I guess there
could be a sliding piston arrangement of some kind to achieve it. My dad
has a large mercury-column barometer, which IIRC claims to be
spillage-proof even if turned upside down accidentally during transport, so
there must be a seal of some kind.


Anna Noyd-Dryver

On 19/07/2016 11:02, Roland Perry wrote:
In message , at 10:25:58 on Tue, 19 Jul
2016, tim... remarked:

It's every much the same sort of thing: banning a commodity because
it's harmful/unethical or whatever.

There is a mile of difference between unethical and harmful,
especially when in normal use the item isn't harmful at all, it's
only harmful if it's abused.

Ivory hunting is harmful to elephants.

I was referring to the mercury instrument (I thought that was bleeding
obvious)

The problem with mercury is that even if not "abused" (whatever that
means) it has a tendency to get split, and when it does the tiny
droplets run everywhere and are very difficult to clean up.

I can remember playing with blobs of mercury when I was a kid, great fun
chasing them round the table....

Colin