NBC News reports:
Of all the many sights and sounds etched onto the memory of anyone who’s been alive long enough to witness a conclave, the white smoke billowing from the Sistine Chapel chimney and the ringing of the church’s bells signifying the appointment of a new pope are perhaps the most famous.
With the second result of each pair of votes — there are two morning votes and two afternoon votes on each full day of the conclave — the temporary chimney installed last week by the Vatican’s fire department will emit black smoke if the vote is inconclusive or white smoke if electors have come to a decision.
According to the Vatican press office, the black smoke is made by a cartridge holding a mixture of potassium perchlorate, anthracene and sulphur. The white smoke is created by a mixture of potassium chlorate, lactose and a pine resin also known as Greek pitch. The smoke travels up almost 100 feet of steel and copper tubes to the chimney and the world beyond.
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