>  Do you somehow think mercury is dangerous? 

As with a lot of other material it is the more complex chemical compunds of
it that are dangerous.  For mercury, lead, cadmium, etc, sometimes very
poisonous.  I believe that the chemicals in our own stomach (like HCl) can
make something nasty with mercury)

I have for long not seen any mercury thermometer sold here in Sweden,
instead the chemists recieves them for destruction at no charge.  Also,
light tubes are strongly recommended to return for mercury collect.

Similarly, mercury batteries and lead and cadmium accumulators can be
returned to the seller for destruction, and they have no leagal right to
charge you for that!  (In Sweden)

IMHO, mercury and cadmium batteries should be forbidden, as there is
already better technologies available (Lithium and NiMH).  If the
production of them increases they would not only be technically better and
less poisonous, but also be the cheapest technologies.

(OK they are still poisionous, but much less)

...
Just for fun, I once made a joystick consisting of two ring-form plastic
tubes half-filled with mercury, 90� to each other, both standing, and three
electrodes each: bottom, and sides.  By just holding the stick in the air
(or anywhere) and tiliting it, you controlled the game.

(This was before i read about mercury and its nasty compunds in chemistry
class...)

After a couple of week i noticed a black-grey substance covering the inside
of the rings.  The plastic I used alow oxygen to diffuse, and also the
plastic material might have released some complex additives.

I guess the switches observed in theese shoes are made of plastic, and the
dull grey something is some mercury compound (probably nasty)
...

I just dont understand why they would use a mercury switch in theese shoes
anyway?

I have produced simple vibration detectors using just a cheap piezo disc
pumping charge to a transistor�s base at each mechanic cycle. (and diode
and resistor for protection)

Much cheaper, both the sensor, required electronics, and manufacture, and
no quiscent current whatever direction of sensor.

/Morgan
        Morgan Olsson                   ph  +46(0)414 70741
        MORGANS REGLERTEKNIK            fax +46(0)414 70331
        H�LLEK�S           (in A-Z letters: "HALLEKAS")
        SE-277 35 KIVIK, SWEDEN               mrt@iname.com
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