Date   : Tue, 27 Oct 2009 03:20:29 +0000
From   : afra@... (Phill Harvey-Smith)
Subject: Chemical "hot water bottle". [ot]

Rick Murray wrote:
> Hi!
> 
> My first YouTube video, and it is a serious question.
>    http://www.youtube.com/watch?v=quR3rH99apc
> 
> BTW, it is also deaf-friendly. Or for those that don't understand my 
> speaking. :-)
> The audio is a bit naff, sorry. It was all recorded with a digital camera.

Video if fine, had no problems at all following it.

As for how it works :-

http://en.wikipedia.org/wiki/Sodium_acetate

And scroll down to the bit about heating pads.

Cheers.

Phill.