Quick question,

 

Am I right in thinking that if both the probes of a voltmeter were immersed in one beaker of salt solution, the voltmeter would show small fluctuating readings of potential due to the movement of the ions in the solution? Or does it not work like that?

Yes, but the variations would be very small

 

I think it's this

 

http://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise

but, from my point of view it's half past two in the morning.