Copper(II) sulfate
strixvanallen on Jan. 5, 2015
Before you ask: yes, throwing copper compounds in the sink is not environmentally correct, but chemists do it anyway. We are bad people.
The cloud he is talking about is in an old strip. Good hunt. XD
strixvanallen at 12:29PM, Feb. 10, 2015
Everyone did this at some point. xD
Peipei at 3:46PM, Jan. 5, 2015
Lol! Typical Laxed chemist! xD