MSN.com - 3/13/13, MSN UK News

Following criticism that the smoke looked unusually dark and distinct compared with that seen before, a spokesman has admitted that it is not made simply of incinerated ballot papers.

Instead, the smoke is a mixture of chemicals made by adding cartridges containing potassium perchlorate, anthracene (a component of coal tar), and sulphur to the burning ballots.The Rev. Federico Lombardi added that the white smoke signalling a pope has been elected will be produced by potassium chlorate, lactose and chloroform resin.