PHILADELPHIA -- It's not exactly a seminar at Hogwarts.
But Harry Potter devotees would still feel right at home with the scholars gathering this week to discuss the philosopher's stone, arsenic and the finer points of transmuting lead to gold.
"I have a few flasks heating back in Baltimore as we speak," says Larry Principe, a Johns Hopkins professor of chemistry and history whose academic specialty might be dubbed experimental alchemy.
Welcome to the first major conference on alchemy in nearly 20 years. Long written off as fraud and deranged mystics, alchemy and its practitioners are increasingly becoming the focus of serious scholarship.
One reason: Many early scientific luminaries -- including physicist Sir Isaac Newton and Robert Boyle, the father of modern chemistry -- turn out to have been closet alchemists. Newton alone spent more than 30 years working on what one historian called his "dark addiction."
"Newton was not the first of the Age of Reason. He was the last of the magicians," British economist John Maynard Keynes famously said in 1946.
Another reason for the resurgence of interest is that some historians now believe 17th-century alchemists might have played a larger role in jump-starting the scientific revolution than they previously thought.
"Once you get past the weird terminology, you realize they were in the forefront of the experimental method," says Bill Newman, a historian of science at Indiana University who studies Newton and other, lesser-known alchemists. "These guys had a huge unrecognized impact."
They also discovered stuff. Among the innovations attributed to early alchemists, for example, are the distillery and Meissen porcelain, the first version of the ceramic produced outside China.
Others were busy concocting perfumes, pigments and primitive pharmaceuticals.
Still, it's not hard to see how even serious alchemists earned their reputations as nut jobs.
"Alchemists were, frankly, preoccupied with urine," says Neil Gussman of the Chemical Heritage Foundation. The organization was the host of the three-day alchemy conference and houses one of the world's largest collections of ancient alchemic tomes and art in its headquarters near Independence Hall.
Occasionally, the alchemists' eccentric pursuit paid off. Consider phosphorus. Prized for its glow-in-the-dark properties, the element was discovered in 1669 by amateur German alchemist Henning Brand, who isolated it by laboriously distilling urine until only powdery white crystals remained.
"You wouldn't have wanted to be his neighbor," says Gussman.
Despite these contributions, alchemy was long considered unfit for serious scholarly study. One prominent 20th-century historian even warned that academics who dared study it risked becoming "tinctured with the same type of lunacy they set out to describe."
"Some people were afraid to touch it," says Bruce Moran, a University of Nevada historian and author of Distilling Knowledge: Alchemy, Chemistry and the Scientific Revolution.
The last time alchemy scholars gathered, back in the Netherlands in 1989, some feared the field was dying. Today, "alchemy is going mainstream," says Brown University historian Tara Nummedal, who at 34 is one of a new generation of academics interested in the field.
Nummedal's interest was piqued by Newton: "When I learned that the father of modern science was an alchemist, I thought: How can that be?"
Nummedal has plenty of company. Newton, who invented calculus, described the laws of gravity and helped explained the behavior of light, color and planetary motion, has long been an enigma -- and occasionally an embarrassment -- to science scholars.
"We cannot understand how a mind of such power ... could stoop to be even the copyist of the most contemptible alchemical poetry," biographer David Brewster wrote in 1855.
"Nobody really understands why Newton is doing these experiments," says Indiana University's Newman. "He wasn't just dabbling. This was a serious undertaking on his part."
But figuring out what Newton and other alchemists were up to has turned out to be a formidable task because many early alchemical texts are written in Latin. They're also peppered with arcane code phrases that scholars call decknamen.
"They're pseudonyms for substances," says Newman, who is working on a National Science Foundation-funded effort to decode the decknamen in Newton's alchemical writings.
In his notes, Newton, for example, refers to the "Green Lion" and the "menstrual blood of the sordid whore." Despite its sensational overtones, Newman believes the "blood" Newton referred to was antimony, a toxic, silvery metal widely employed in alchemical recipes.
But decoding musty alchemical tomes is just the first step. "It's very, very difficult to figure out what Newton was doing in the lab unless you try it," says Newman. "You really have to learn to think like an alchemist."