I forgot to label the bag and now it's been 6 months and I can't remember which chemical it is. They are both fine white powders. I know the fixer smells pretty strong so I suppose I could put some in water and see if I can smell it. Any better ideas?
You could try a clearing test. Once you've mixed your mystery powder with water place a small amount in a graduate or glass and then snip a bit of the leader off of a roll of film. If it clears in the solution, then you have fixer. If the film remains opaque then it is probably something else. Your smell test would work as well, btw. Good luck.