Sacha wrote:
[...]

You get the citric or tartaric acid from a chemist who might have to order
it for you. The one I got it from is one who knows us and the person I
spoke to there this morning said she'd ordered it in because it's
elderflower time and she knew several people would want it. Each packet
contains 50g. However, I've heard of people having trouble finding it in
the past because of the illegal potential, so it's worth making sure your
local chemist will obtain it for you.
[...]

I can't imagine any chemist refusing to sell it in these little packets
just because of the risk of abuse; but I can sympathise if they don't
reckon they can sell enough to make it economic. I think big towns
still have home-brew shops -- there's one in Cheltenham, for example,
and a market stall in Carmarthen. The bloke in the Chelt shop told me
how the market for these things had shrunk over the past ten-twenty
years since the height of the home booze craze: even his wholesaler of
citric acid and such was buying a fraction of what he used to.

--
Mike.