The Science of the Papal Enclave

Science? In the Papal Enclave? Blashphemy! But indeed, it's true. The different colors of smoke produced to signify whether a pope has been elected or not (black for not, white for pope) can be explained purely by using science.

As Chris Mocella, co-author of Chemistry of Pyrotechnics, said in this National Geographic article, there are two ways to make smoke: combustion and vaporization. Either could be responsible for the classic white smoke.

So what is the Vatican's methodology? Probably "metallic zinc dust with elemental sulfur, generating zinc sulfide gas that is a thick off-white cloud of smoke when generated." The black smoke is probably the product of a high carbon combustion (wood) in a low oxygen environment.