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So…after all those decades of physics and chemistry, can science transmute base substances into gold? —Bill Johnson
Don’t you think you’re being a little unappreciative here, Bill? Decades of physics and chemistry have given us space stations and electronic intelligence, conquered disease and extended lives, and enabled us to download gigabytes of pornography at reasonable cost. And you’re still after gold?
I suppose that’s not surprising. Gold has been the most prominent symbol and source of material wealth since the dawn of history. Even in this age of wonders many simple souls don’t trust collateralized mortgage obligations and would just as soon have an ingot, preferably if they can whip it up in the basement with crucibles and a Bunsen burner.
The dream of medieval alchemists was transmuting base metals into gold using the elusive philosopher’s stone, but since atomic theory was unknown little progress was made. With the advent of the nuclear age, though, literally converting one element into another became possible.
Initial attempts didn’t get you gold. Rather, you started in the classic case with uranium and got various forms of iodine, cesium, strontium, xenon, barium, and whatnot plus enough released energy to vaporize the neighborhood—a useful result in narrow circumstances but a bother to the kitchen scientist.
Nonetheless, nuclear physics offered possibilities. In 1941 researchers transformed a few atoms of mercury into gold by bombarding them with fast neutrons. The drawbacks: first, the gold was radioactive, and second, no small matter from an investment standpoint, one gold isotope had a half-life of 78 hours, one 65 hours, and a third 48 minutes, after which they decayed into something less bankable.
In 1981 researchers at Lawrence Berkeley Laboratory reported they’d smashed carbon and neon atoms into bismuth atoms and created trace amounts of gold. Fast-decaying, radioactive gold. Swell.
What we needed was a method of producing stable gold. I did what every modern researcher does when at an impasse. I consulted Wikipedia. An uncited assertion in the “Synthesis of precious metals” entry provided a lead. After a heroic effort involving my sending Una out to dig through the journals, I offer the following tentative method:
- First, get some mercury. The kind we want is Hg-196, a naturally occurring isotope with 80 protons and 116 neutrons in its nucleus. The 80 protons are what make it mercury. Gold, meanwhile, has 79 protons—you see where I’m going with this. Finding sufficient Hg-196 could take some doing, though, as only 0.15 percent of mercury is in this form.
- Slam a slow neutron into it. The journals said the desired type of neutron had an energy level in the thermal range. This to me suggested you could just heat up a can of neutrons on the stove and drop in some mercury. However, I suspected subtleties were being overlooked. I set this matter aside for further study.
- The slow neutron is captured by the nucleus of the Hg-196. This turns it into Hg-197, with 80 protons and 117 neutrons. Hg-197 is unstable. In 64.14 hours, give or take, electron capture occurs. This means the Hg-197 grabs an electron from a low-hanging shell, combines it with a proton to make a neutron, and kicks out a neutrino.
- Discard the neutrino.
- The Hg-197 has now turned into something with 79 protons and 118 neutrons. Do you know what this? I’ll tell you. It’s Au-197, the only stable isotope of gold.
- Repeat five zillion times, until you have enough gold to make an ingot. Success! However, if you didn’t do so earlier, you must now separate the stable gold deriving from Hg-196 from the unwanted crud deriving from the rest of the mercury, which I remind you constitutes 99.85 percent of what’s out there and a good chunk of which I’ll bet is now radioactive. So it could be a long afternoon.
I’ve also learned that if one wants slow neutrons one can’t merely drop by the neutron remedial reading class. Ideally one wants a nuclear reactor.
You’re thinking: too much for me. I’m going back to traditional methods of gold extraction involving exploitation of Third World workers. I remind you of David Hahn, the Detroit-area Boy Scout who built a model breeder reactor in his mom’s potting shed using radioactive materials scavenged from smoke detectors and clocks.
Despite numerous obstacles, did David get discouraged? No. Judging from photos, he got radiation poisoning. Maybe you should reconsider how badly you want to do this, Bill. But at least you know it can be done.
Have something you need to get straight? Take it up with Cecil at straightdope.com.