I bought a pH meter which is aimed at gardeners ...
http://www.amazon.co.uk/Gardman-Soil...7222580&sr=8-3

I thought I could also use it on liquids ... but I have serious doubt it
is reading acidity correctly.
Is there a simple way of testing ?

In water it read 7 .. (so OK there) ... I tried in in a bottle of white
vinegar with is rated at 5% acidity it reads pH 6

Is there a simple home way of testing calibration ?