With everybody waiting on a puff of white smoke to eminate from the chimney of the Sistine Chapel, the engineer in me is curious about the mechanics.
I know in modern times that a special additive to the ballots is added to make the white smoke, but I wonder about the origin of this custom. Was there a time when the white smoke was not something that was manually introduced- akin to the Coptic Pope being chosen by a blindfolded boy?
Or, if in fact this always had been an engineered thing, when and why did the custom begin? More importantly, has it always been the same thing added to make white smoke? Who figured out the mechanics of it all?

