'Old' Metabisulphite

[The Mighty Badger]

During yesterdays brewday I came across an old, opened pack of sodium metabisulphitem from my kit days; it was probably opened / last used 5 years ago. It had gone rather brick like but I chipped some off, crushed it and tried to dissolve it in water. Didn't seem to dissolve very quickly but I did get a whiff of the usual smell.

I assume this stuff doesn't 'go off' as such, but can it degrade etc? Would it still be good to use or should I just bin it?

[The Mighty Badger]

That's kind of what I thought, but as I wasn't too sure I thought I'd better ask the question.
Thanks

[boingy]

If it has that smell (and make you cough, lol) then it is still OK