Names from a long time ago. Chemists may call it ammonium chloride, but if you go to a hardware store, it's still Sal Ammoniac ("Salt of Ammon", in the plumbing section), same as it was around the turn of the millennium (not that one, the one before). And even the chemist isn't escaping this history, because the modern name "ammonium" itself comes from Ammoniac, which comes from the fact that the substance was discovered in white crystals that formed on the roof from the burning of camel dung in the Temple of Zeus/Jupiter Ammon in Egypt (or so says the internet).
Today it's used to rub soldering irons on to clean the tips.
Source: Hardware Store
Contributor: Theodore Gray
Acquired: 5 August, 2002
Text Updated: 11 August, 2007