Modern people often assume that individuals who lived during the Renaissance and Medieval periods were less intelligent than individuals living today. After all, they believed in all sorts of things that science has shown to be false or even ridiculous. Furthermore, some of these beliefs seem to defy the conventional notion of common sense and as a result it is unclear how they ever came about. What we know about evolution, though, tells us that we couldn't have evolved that much over even the last several thousand years. The ancients were just as smart as we are, but they did have a vastly more limited knowledge base in the physical sciences.
In the modern age we have solved the age-old problem of manufacturing gold from other elements. The trick is to use nuclear processes that alter the structure of atoms, and it can be done in nuclear reactors or particle accelerators. It turns out that making gold from lead, as the folklore suggests alchemists did, is not the way to go. Instead, you want to synthesize it from Mercury. As Mercury appears prominently in alchemical writings, I did some research to see if it might actually have been possible for ancient alchemists to have hit upon something similar to the modern method hundreds or even thousands of years ago. My academic background is in psychology rather than physics, so if I'm making some key error here feel free to let me know - but some of the evidence suggests that they might have been able to actually accomplish the synthesis of gold.
The ancients had no particle accelerators or nuclear reactors so some lower-technology method must have been employed. The only real option that a low-technology society would have is the exposure of base material to a highly radioactive element. Uranium wouldn't work because it doesn't give off a high enough level of radiation to come anywhere close to the energy requirements, and elements like plutonium do not occur in nature. A possible viable candidate, though, is radium. It is highly radioactive and can be found in small amounts in pitchblende, an ore that is found in central Europe. While the ancients had no mass spectrometry, radium is obviously different than the surrounding ore. It glows like the magical stones of ancient legends and also gives off heat.
Mercury is the only viable base material. It can be transformed into gold following this equation:
"Mercury 198 + 6.8MeV gamma ray -> 1 neutron + Mercury 197 (half-life 2.7 days -> Gold 197)"
Approximately 10% of naturally occuring mercury is of isotope 198, so it is plentiful enough to be useful. The decay of one atom of radium 226 releases 4.871 MeV of energy, so at least two would have to decay for each transformed atom of Mercury.
So here's the idea. Alchemy talks about the red tincture, the white tincture, and the Philosopher's Stone. We also know that lead was used in the process and at least some alchemists probably did believe that it was the lead which transformed.
The Red Tincture - cinnebar, the ore from which Mercury is produced.
The White Tincture - radium, which in its pure form is white.
The Philosopher's Stone - a smelted piece of radium. Radium's melting point is 1292 degrees Farenheit, well within the temperature range of even a bronze age forge.
The process might work something like this:
* Extract radium from pitchblende. This is the transformation from Nigredo to Albedo. Pitchblende ore is black and the extracted radium is white. The extracted radium is the alchemical "salt" due to its white appearance.
* Using a forge, melt the radium into some sort of mold to create a "stone."
* Extract the mercury from cinnebar. Cinnebar ore is red (Rubedo) and it during the extraction process it separates into Mercury and sulfur, which is yellow (Citrinitas). These are the alchemical sulphur and mercury - by this model the terms are literal.
* Place the liquid mercury into a lead vessel. Lead might have been arrived at simply because it offers some shielding from radioactivity. Needless to say, the entire process outlined here would be very dangerous to perform without modern safety equipment.
* Drop the radium "stone" into the mercury.
* Seal up the vessel and allow the mixture to "incubate" for a period of time. 40 days was commonly recommended, probably enough time for most of the mercury-198 isotope to transform.
* Open the vessel and remove the stone and mercury. The synthesized gold molecules would be deposited at the bottom of the vessel, which may have given rise to the idea that the lead was being transformed.
The stone would be reusable, so once you had accomplished (1) and (2) you wouldn't need to repeat the process. It's half-life would be about 1600 years so a stone could even be passed down from master to student over the course of centuries. You would need more mercury, though, to make more gold.
Whether or not this would work depends on two things. First off, the modern method of extracting radium from pitchblende uses electricity. Is there a lower-technology method that could have been applied in order to extract a small amount of the element? Second of all, would the radium actually produce enough concentrated decay energy to facilitate the transformation? One other issue is that to my knowledge we have never actually found one of these radium stones, which argues against the ancients ever coming up with this technology. However, they may have been regarded as so valuable and secret that they were never just left lying around. It might be interesting to sweep European alchemical labs with a detector and see if any buried sources of radiation can be found.
If I were a graduate student in physics and could get my hands on the materials, I would love to try it out. It could never have been developed to any practical level because the amounts of gold produced are tiny, and to this day it is cheaper to buy gold than it is to make it. Nevertheless, it intrigues me that this process does seem to match more features of the old accounts than you would expect due to chance alone, and the idea that the ancients could have managed a physical transformation is compelling and it would be interesting to know whether or not it is really possible.
Are there any physicists out there who might care to disabuse me of my ignorance? Fire away - I am by no means an expert and would love to hear why it can't work from someone who knows more about radioactive materials than I do.
Also try this free pdf e-books:
Reynold Nicholson - The Mystics Of IslamBaron Tschoudy - Alchemical Catechism
Herbert Stanley Redgrove - Alchemy Ancient And Modern