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What makes the conclave smoke black or white?

Black smoke rose from the chimney on the roof of the Sistine Chapel on Wednesday.

ALDRIN XHEMAJ/EPA

Black smoke rose from the chimney on the roof of the Sistine Chapel on Wednesday.

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VATICAN CITY (AP) — The Vatican is revealing what the smoke signals emerging from the Sistine Chapel chimney are made of, after the stir caused by how much more distinct the black smoke in this conclave has been compared to the past.

The Vatican spokesman the Rev. Federico Lombardi said the black smoke that came Tuesday and Wednesday — indicating a pope had not been elected — was made by adding cartridges containing potassium perchlorate, anthracene (a component of coal tar), and sulfur to the burned ballots.

The Vatican is burning the flares following confusion in past conclaves about smoke color. Lombardi said that neither the chapel frescoes nor the cardinals inside suffered from the smoke.

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