Donald Qualls at silent1@ix.netcom.com wrote

You buy it locally:
$8-$10 / gal. from a chemicals supplier, usually 5 gal minimum.  Also
available from graphic arts and some industrial supply firms.
- or -
$25-$30 / gal. from a photo store

It is expected to freeze: melting point is 62F.

No, not him -- he can't managed to develop film in coffee and use the
orange juice as stop bath, with the result that his film turns black
while he's looking at it (though I found it interesting that it was
cleared, as if fixed, rather than milky as unfixed film should be);
instead, he used the OJ as developer (and what did he alkalize either
one with, we don't know) and pulled the film into the light without even
a stop bath.

Sad to say, though there have been dozens of fixers over the past 170 or
so years, only the thiosulfates have ever gone anywhere.  Salt water or
sea water has been said to fix, but it doesn't.  Sodium sulfite does,
but has very low capacity and is extremely slow even in saturated
solution -- as in, soak your film for days and change solution several
times trying for a good fix.  Most of the other potential fixers are
also fogging agents (not that big a deal, as long as you avoid developer
carry over) or bleaches (very bad, if you're losing image while you
remove the undeveloped halide), or both.  Even thiosulfate can bleach,
weakly, in an acidic solution.  No, sodium thiosulfate isn't
particularly toxic -- it's the specific antidote for prussic acid, aka
cyanide, though it has to be administered almost instantly (another
strike against MacGyver -- by the time he got Pete Thornton the fixer
from the mini-lab, which should have contained toxic levels of dissolved
silver, it was too late to save a real cyanide victim, even if he wasn't
quite dead yet).

The problem with fixers is only partly that the halogens grip metal ions
very tightly; fixing requires both a chemical that can solubilize silver
ions, *and* one that can keep the halogen ions from reforming insoluble
halides with the silver.  Chloride, Bromide, and Iodide will all replace
nitrate -- not because they're more reactive than the nitrate ion, but
because their compound is insoluble, so any tiny bit that forms
immediately drops out of the reaction as an insoluble solid.  The
thiosulfates provide sodium or ammonium ions to keep the chloride happy
and in solution while the thiosulfate complexes the silver in a form
that doesn't just re-react with the chloride in solution -- and that
trick is one tha few chemicals can manage.

The places to look would be in the thio- family, because of the affinity
between silver and sulfur, but most of them are also fogging agents --
thiourea, for instance (these days called carbamide), and thiocyanates,
are both strong foggants.  There may be other thio- chemicals, however,
that could complex silver and resolubilize it from a halide crystal --
perhaps a thionitrate or thiophosphate, if such things aren't just the
fevered dreams of a non-chemist.  None of those, however, are likely to
appear on grocery aisles as common household materials.

Hmm.  Maybe garlic juice, with its high concentration of allyl sulfide?
It's probably a foggant, but might it be a fixer?  And if so, could any
of us stand to use it immediately after half an hour in the same room
with Caffenol?