Yes, it was first introduced by George Wakefield - although I thought
in the fifties. I didn't know he had patented it.
No, I haven't tried it - was hoping to get some more details so I could
get students to play around with the formula rather than using it
straight out of the pack - it is also a little expensive for student use
at around nine dollars a litre pack.
petermarshall@cix.compulink.co.uk