Age of Invention: When Alchemy Works

Often, the alchemists were onto something.

I’ve spent a lot of time recently researching innovations of the late sixteenth century, many of which involved alchemy.

Alchemy today has a bad reputation, and for good reason. You cannot transmute base metal into gold (unless you have a modern particle accelerator). You certainly won’t transmute base metal into gold in a laboratory because of a particular conjunction of the planets, or because you happened to be especially pure of heart that day.

But what is so striking about the alchemists is that they took experiments and observations very seriously. Even if they were entirely wrong as to why, their alchemical demonstrations often really did work.

Take Richard Eden, who in the 1560s described having created “a hundred silver trees an inch high, so perfectly formed with trunks, stalks, and leaves”. Achieving the growth of such a silver forest - often called Diana’s trees - was meant to be a crucial step towards the Philosopher’s Stone. And as surprising as it may seem, it is very real. You can achieve it by precipitating nitrate of silver with mercury. The silver appears to “grow”, with crystals shooting out in every direction. With a little help it could easily resemble a tree, with intricate and unpredictable little crystalline stalks and leaves.

Such an experiment might nowadays be considered a party trick. But at the time it would have been empirical confirmation that the alchemical manuals written by the ancients, such as the so-called ancient Egyptian priest Hermes Trismegistus, were correct. It would also have been empirical confirmation of alchemical theory, that metals “grew” beneath the earth. After all, metals seemed to stretch out veins through the earth like the roots of the tree. While such a process in nature might be very slow, the alchemist’s skill was in merely speeding things up, to make “nature ripe by art”.

What about transmutation? Once again, there was an empirical basis for it. Many governments took it seriously, banning transmutation into gold without a license, for fear that the coinage would be affected. In fact, the English court in the 1570s put considerable money into a transmutation effort that has been proven to work, at least on a small scale. This was the project of William Medley, who on Parys Mountain, in Anglesey, appeared to transmute iron into copper. His investors sent the assay master of the royal mint, William Humfrey, to observe the process, who declared it “beyond the reason of all”: it resulted in a greater weight of metal than it started with. Yet, ultimately, after test after test, Humfrey had to admit that it really did work. He allowed experiment to trump theory. What was really happening? The key was in the Parys Mountain water, which flowed through copper ores underground, thus making it rich in copper sulphates. When Medley used the water to boil scrap iron, the copper thus seemed to form from the iron itself.

Unfortunately for Medley, he appears to have failed to perform the process at any scale. He was also secretive, at first resisting Humfrey’s visits, which caused much delay. A rival alchemist spread malicious rumours about him, and his delays put him in the bad books of one of his investors, the Earl of Warwick, who had him imprisoned for debt. Indeed, this was a common ending for alchemists, who on the whole were far too secretive for their own good. One of the key alchemical texts, mistakenly attributed to Aristotle, was even called the Secreta Secretorum. It opened them to criticism and hampered the development of their science.

But I think the lesson is this: our ancestors were not stupid. In fact, they were perfectly willing, long before the period we often think of as the Scientific Revolution, to take observation and experiment seriously. They were even willing to allow observation to trump the theories of the ancients. But those who studied the art were too few, too far between, and perhaps simply too unwilling to share their experiences with one another.