"Keith G" wrote in message
...

"Ian Iveson" wrote


You could always heat them up and hold them at an angle of 71 deg pointing
North and then hit them smartly wiv a hammer - it would make them very
slightly 'magnetic'....

Worked with Miller and some Lucas dynamos, sometimes, reputedly :-)

It must take a while for the heat to escape. How do they know when it's done?

How do they avoid cracking the glass or the metal, or weakening the joints
between dissimilar materials?

There seems to be common in the claims something about relieving "internal
stresses", whatever that means. It may be plausible...I forget if I ever knew
anything about metal at low temperatures...presumably crystals can be
unformed by making them either very big or very small.

Perhaps it is the equivalent of work hardening, where discontinuities are
squeezed out of crystal boundaries?

Perhaps that then effects the way that perveance-enhancing constituents of
the cathode alloy migrate to the surface?


I'm not qualified to comment, but I will say that, in general, I *believe* the
opposite - the appropriate application of heat allows change in solid objects,
the application of extreme cold prevents it.....


http://www.frozensolid.co.uk/science.htm

for example.

Like other forms of cold working, it drives out the dislocations from the
structure. Seems also to encourage the formation of carbide in iron, and who
knows what other structural changes in other metals and alloys, similar to those
caused by pressure perhaps.

cheers, Ian