...It can be quite hard to get the tartaric acid or citric acid because,
apparently, both can be used to cut cocaine or to make bombs.

I just asked at our local chemist - they had citric out on the shelf and the
assistant kindly got the pharmacist who explained that citric was a good
substitute for tartaric in recipes such as elderflower cordial. Am about to
make my first batch
(I did just search for citric acid on the net and found several recipes of
explosives so will be careful what I put into my cordial )

--
Hayley
(gardening on well drained, alkaline clay in Somerset)