>Sodium bisulphite (not sulphite) was and I think still is the major
>constituent in a commonly used WC cleaner.
This is of course sodium bisulphate - totally irrelevant to the thread.
As an ex-chemistry teacher this is a mistake I have corrected numerious
times in student work!
However the info on sodium metabisulphite is correct. It comes from my
local chemist shop with no hazard information on the label. It is more
stable than the bisulphite and seems to keep indefinitely. I don't think
any of these compounds is particularly hazardous (except possibly for
asthma sufferers.)
When I was a chemist I never had to buy sodium sulphite for photographic
use. Just used to take the bottle we had in stock, carry out a test for
sulphate (always positive once you have opened the bottle) and condemn it.
Peter
petermarshall@cix.compulink.co.uk