I've bought CaC recently for chemistry experiment / demonstration purposes.
It has quite a foul odor even before you react it with water and the gas
produced upon reaction with water has a strong garlic odor - somewhat less
so after you burn it. From what I've read, pure acetylene is odorless and
the garlic odor is from substituted phosphines (PH2X where X is some other
group - probably containing sulfur). Unfortunately these impurities are
rather poisonous so I've had to limit the demos (if done indoors) to only a
couple of grams of impure CaC at a time.

It does make a very bright yet sooty flame.
--=20
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