A little research showed that the right way to do this is using a conical flask and a Magnetic Stirrer and Stirring Bar.
Problem solved 
...and then I saw the price of those things...bloody hell! I love the internet because you can find out how to build anything and I got a simple set of instructions on how to build a stirrer. This is where I got mine
http://www.instructables.com/id/How-to- ... c-Stirrer/
These are the components...
The 12V PC Cooling fan and Controller and 10 Rare Earth Magnets (silver things just on the right of the fan body) all came via sourcingmap.com and cost US$19 incl free postage.
The job box and 12V power supply came from an electrical wholesaler near me for 22 Euro.
I glued 4 of the Rare Earth Magnets inside a lid off a plastic tub in two pairs with opposite polarities facing out on either side. The lid was exactly the same diameter as the centre of the fan and would be glued to the fan later.
Next I cut a hole in the lid of the job box just 4mm larger than the outer diameter of the lid containing the magnets and then fitted the fan on the inside of the lid.
The fan controller is just a potentiometer designed to fit into a slot at the back of a PC but I drilled a hole in the box lid beside the fan and stuck the knob of the potentiometer through.
Next I glued the plastic lid - with the magnets inside - onto the hub of the fan and added a little decoration and....Voilla
a home made Magnetic Stirrer 
Does it work? Yes indeedey
Including the Conical Flask and Magnetic Stirrer Bar I've ordered on Amazon the whole thing cost me 65 Euros (about GBP56)
I'm very happy with the result and if anyone fancies making one I'll happily provide detailed instructions but it's very simple to do
AM
Statistics: Posted by Almanac — Sat Aug 24, 2013 4:39 pm
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