Reconstructing Alchemical Experiments

In this week’s issue of C&EN, I wrote a profile of Larry Principe, a professor of organic chemistry and the history of science at Johns Hopkins University. Principe studies alchemy with the goal of understanding the evolution of modern-day chemistry.

Alchemists sometimes depicted their experiments with coded images like this one. Credit: Chemical Heritage Foundation

But he doesn’t just study alchemy. He also carries out his own alchemical experiments to get a handle on the thought processes of those experimentalists who tried to make gold from cheaper materials. One school of alchemists that Principe got particularly interested in is a group who focused on making gold by starting with mercury.

Back in the 16th and 17th centuries in Europe, Principe says, “there was a lot of disagreement about what material to start with—what you actually go to your apothecary and get 20 lb of to start trying to” transmute base metals and chemicals into gold. Some alchemists thought copper sulfate or potassium nitrate would work. Others—those that Principe calls the mercurialists—focused on mercury, hoping to use the liquid metal to make the philosopher’s stone.

For those who have lived under a rock for the past decade and haven’t read any of the “Harry Potter” books, or even heard of them really, the philosopher’s stone is a substance thought to be able to convert base metals into gold. And, as mentioned in the first book of the “Harry Potter” series, the philosopher’s stone was also thought to be a universal medicine capable of prolonging life.

To make the philosopher’s stone, Principe says, the mercurialists believed that “you needed to awaken a seed that’s within gold to cause it to grow—just like when a farmer takes seeds and puts them in the ground and waters them, he gets more seeds back in the harvest.” This group of alchemists therefore used a lot of agricultural metaphors and imagery in their writings and drawings.

One of these alchemists, a Harvard-educated man named George Starkey, wrote a number of public works on the subject under the pen name Eirenaeus Philalethes as well as some private letters—most famously to “father of modern chemistry” Robert Boyle.

The tree that Principe made out of philosophical mercury and a seed of gold. Credit: Larry Principe

Putting together some of these public and private writings, Principe came up with a reasonable idea of what Starkey was doing in the lab. “The idea was that you take common mercury, and you turn it into ‘philosophical mercury’ by distilling it from various mixtures of metals,” Principe says. “Somehow this makes it a fit liquid for nurturing the seed of gold.”

Principe undertook the laborious process of grinding mercury with various substances, heating it, boiling it, and distilling it seven times. After a month of work, he says, he got something that should have been, according to Starkey, philosophical mercury. He then mixed it with a small bit of gold, put it in a small sealed flask with a long neck, and heated it.

But here was the tricky part: Starkey didn’t have thermometers back in the day, so it was difficult for Principe to gauge what temperature the alchemist had used. The Johns Hopkins professor fiddled with temperature settings for three weeks until he came into the lab one morning and realized he must have found the correct, albeit narrow, range.

There in the flask was a beautiful treelike structure of mercury and gold. “It surprised the heck out of me,” Principe says. “I didn’t expect anything quite like that.” But once he saw the result, Principe says, it is easy to understand why Starkey thought he was on the right path toward the philosopher’s stone: He had succeeded in making the seed of gold sprout. And it’s also easy to understand why he, and then Boyle, continued to practice alchemy after successfully producing the small, crystalline structure.

“When you’re working for months and months on a process, and you just can’t get anything close to the results that are described” by the alchemists, Principe says, “and then you finally make the right change and it works beautifully,” it is so satisfying. “And you realize that at that moment, you are looking at the same phenomenon that your author writing in 1600 saw himself. For me, that is such a powerful thing—it explains so much more.”

The story of the tree was originally published here:

Lawrence M. Principe, “Apparatus and Reproducibility in Alchemy,” pp. 55-74 in Instruments and Experimentation in the History of Chemistry, eds. Frederic L. Holmes and Trevor Levere, (Cambridge, MA: MIT Press, 2000).

Author: Lauren Wolf

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  1. I admire Prof. Principe for his efforts in duplicating the alchemist’s trade. I do hope he is not planning to follow the alchemists’ isolation of phosphorus by boiling off several liters of human urine!

  2. @Ash – But that’s how all the early discoveries were made! Wasn’t insulin isolated from several ground-up pancreas glands? And cortisone from a bunch of adrenals?

    Chemistry 100 years ago was a sport where you had to know the local butcher on a first-name basis.

  3. Actually, less than 100 years ago, SeeArrOh. When I was in college, I presented my undergrad research at a symposium with the other local colleges. My project was a combo of enzyme kinetics and crystallography of said enzyme (I collaborated with Novartis, where my undergrad adviser had worked until the early 90s). I remember there was another young lady at the symposium, from the College of St. Elizabeth (just up the road from Drew, where I went) who ALSO had an enzyme kinetics project. But she didn’t get anywhere near as far as I did because she was obtaining cow parts (don’t remember if it was liver, spleen, or what) from a butcher in Newark, NJ, then isolating whatever enzyme it was she was studying. I remember thanking my lucky stars I didn’t have to do that (My enzyme came frozen in little eppendorfs.)

  4. Well, not only the butcher. Near the end of XX century, I worked for my thesis in a lab where everyone was dealing with biomimetic coordination compounds of mostly copper, iron, manganese. I was not personally involved in such operations, but my copper-lover colleagues had to insulate the bluish metalloproteins of the outer cuticle of zucchini. When it was the goos season, incredible amounts of zucchini came into the lab, to be carefully peeled with sharp knives, removing as less cuticle as possible, to get only the good one. And then, let’s go with extraction and dialysis… Eventually, someone decided that an adapted potato peeling machine could be a good investment!