[quote=“Bleach”]
Oh…nasty…
By the way - what exactly is rock salt? Is that NaCl?
[/quote]
This is the common name for the mineral “halite”. Its chemical formula is NaCl. You might know this substance as table salt. and… Actually, rock salt is not K2SO4; it is NaCl.
http://www.soest.hawaii.edu/GG/ASK/rocksalt.html
I guess it’s just big grains of salt like the kind you use while making ice cream.