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Re: mercury :-(

On Mon, 3 Jun 2002, John S. Denker wrote:

And there's no need. Most things that formerly were done
with mercury can be done these days in other ways, just as
nicely or even better:
-- mercury switch --> reed switch + magnet
or optical switch + interrupter
-- Hg diffusion pump --> silicone diffusion pump
or turbopump or ion pump
-- various explosive compounds --> other explosive compounds

In the past, people have repeated the Faraday Disk demonstration by using
electric heaters and Bismuth or Indium solder (Rose Metal, Wood's metal,
etc.) If you need a pool of liquid conductor, and if electrolytes aren't
conductive enough, then molten tin/lead can be used.

Unfortunately this alloy is fairly expensive, but a university lab might
be able to make up a batch. Also, beware of some of the low temperature
solder recipes which contain Cadmium.

http://www.belmontmetals.com/products/low-melting.cfm

I have a data sheet from Belmont Metals. It shows an alloy that melts at
136F (hot water), which is 49% bismuth, 21% indium, 18% lead, and 12% tin.

The lowest temperature fusible alloy I've seen mentioned will supposedly
melt at 30C (86F), but I don't know what it contains. That stuff would
be liquid during a hot day! I bet it's full of cadmium though.

Here are some alloy recipes:

Rocket Web Library: alloys
http://arocket.mid-south.net/library/Structures/Metalwork/alloys.html


Here's a place to buy small amounts of "Field's Metal" 144F alloy:

https://host2.4ua.com/scitoys/cgi-bin/shop.exe?page=store.html

Note that bismuth can be had from "environmental green" shotgun shells
which use bismuth pellets rather than lead.


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