Sense and Science: The Vatican's secret smoke recipe

In Italian, it’s fumata nera (black smoke) and fumata bianca (white smoke), a system to inform the world whether or not the Roman Catholic church has a new pope.

 

I wondered if there was some secret Vatican formula for producing the smoke, which is sent up the chimney on top of the Sistine Chapel, where the cardinals’ conclaves are held. The whole world waited for the smoke: two episodes of black smoke disappointing everyone, and then, finally, white smoke on March 13.

 

It did take some time to track down the formula, with some websites, like the National Geographic’s, saying that the formula was unknown.  In the end, I found the formula on the American Broadcasting Corporation's site, with the best scientific explanation of the process to be found on the British Broadcasting Corporation (BBC) website.  

 

After more browsing, I realized that the source of ABC was the Vatican itself, through the latter's website, news.va.  So it looks like the Vatican has indeed entered the Internet age, and is also shedding its mystery and its secrets.  

 

 The Vatican website explains that, until 2005, the smoke was produced with a simple process: wet straw produced white smoke, and pine resin or pitch produced black smoke.  But the process was not reliable: the smoke sometimes looked gray, neither black nor white.

 

So in 2005, the Vatican changed the formula: I’m imagining priests looking like medieval alchemists trying different chemicals, which are controlled through an electronic panel.  The black smoke is now produced through a mixture of potassium perchlorate, anthracene and sulphur, while the white smoke is a mixture of potassium chlorate, lactose and rosin.

 

In broad terms, the chemical principles are simple.  Organic materials are used to produce the black smoke: sulphur, which is also used in gunpowder and fireworks, combined with anthracene —which is derived from coal tar— and potassium perchlorate.  The BBC says that the Vatican formula is very similar to a smoke bomb.  Fortunately, the smoke goes out through the chimney or else the cardinals would be in trouble.

 

The white smoke, on the other hand, uses potassium chlorate and lactose (sugar) to provide oxygen for the combustion, but the white color comes mainly from the pine resin, also known as rosin. I looked up pictures of pine resin and it looks very much like the incense blocks sold in Quiapo which, if you want to try, also produces white smoke —and aromatic, at that.  

 

But the Quiapo incense is not from pine, though.  Called kamanyang, the incense is made from the resin of the storax tree, Liquidambar orientalis.  

 

If there are adventurous chemistry teachers who want to try to demonstrate the two kinds of smoke, you could do as well with the old formula for white smoke by using wet straw, or get some kamanyang from Quiapo.  To produce the black smoke, you can use any high-carbon substance.  Ask the students what else produces black smoke, and they might remember burning rubber tires.

 

The Vatican now uses Twitter and social media, and there was even an official Pope app for tablets which updated people on the conclave.  Despite these modern forms of communication, the Sistine Chapel’s chimney remained the center of attention, an age-old ritual still revered.  I am certain the chimneys will be used again to announce a new pope, maybe even with new chemical formulas. — TJD, GMA News

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Michael L. Tan is a veterinarian and a medical anthropologist.  He is currently dean of the College of Social Sciences and Philosophy at the University of the Philippines in Diliman, Quezon City, and Clinical Professor at the College of Medicine at UP Manila.  He also writes the opinion-editorial column "Pinoy Kasi" for the Philippine Daily Inquirer. He has been involved in numerous research projects on a range of issues from HIV/AIDS prevention to the culture of impunity. In 2012, he was elected to the National Academy of Science and Technology, the Philippines' highest science advisory body.