[Rockingham]

"Mercaptan" also refers to a class of naturally occurring sulphur containing compounds that often have to be removed from petroleum. They are usually described as having a rotting smell, especially rotten eggs. A noxious discharge from a refinery or other petroleum facility could be due to natural mercaptans. Sewers and swamps can also release such smells due to natural decomposition.

[Frank_Discussion]

I didn't know that. Thanks for the info.

[capitan_refugio]

Methyl mercaptan is a natural byproduct of the digestion of asparagus and similar vegetables ;^)