@chai2,
Cola? Luxury!
My mum used to rub carbolic soap in a bowl of water to make it go all bubbly. The more vigorosity applied, the bubblier the water.
She then mixed in some soot from the chimney to make it look like Cola, and made us drink it out in the road so all our neighbours would think that we'd been to America.
Tasted a bit like soap though, for some reason.