Aqua vitae

I’ve been pondering some of the alchemical recipes in The Chemistry of Alchemy. (I’m halfway through the book now; my previous mention of this book is posted here.) I learned that cinnabar (mercury sulfide) was known as dragon’s blood (picture below from Wikipedia.) I did not know that another source of dragon’s blood is tree sap (resin) and apparently has healing or antibacterial properties. Scientists have even analyzed the flavonoids from the plant Dracaena Cambodiana. Hopefully no one actually tried to eat cinnabar as the compound would be toxic when ingested. I also learned that the famous Paracelsus helped advance alchemy via a medical slant, but his healing strategy generally took advantage of the placebo effect – diluting the active compound so it won’t do any further damage as many of the chemical treatments could be toxic.

John of Rupescissa is a name I was unfamiliar with. He lived in the 14^th century and apparently said or wrote: “The quintessence: it is the human heaven.” Rupescissa, thought that each substance had its quintessence, or its ultimate and purest form”. Aqua vitae is aptly named: the water of life! When distilled to purity, aqua vitae is a clear liquid that can support fire, i.e., it is a  “water that burns”! Aqua vitae turns out to be high-proof ethanol, discovered by the alchemists looking for the essence of wine. Multiple distillations led to the separation of ethanol, clear like water, with the aroma of alcohol (where I’m assuming this aroma was interpreted in a positive light). Aqua vitae also had healing properties – not surprising as alcohol can act as an antiseptic, and Rupescissa eagerly promoted this new product – the “pure spirit of wine”.

Since each chapter in The Chemistry of Alchemy is accompanied by a practical demonstration, the authors chose to make “Burning Waters”. Their preamble to the actual process is very amusing. “First, an additional safety instruction: do not try this demonstration with ethanol because if you do, you could end up in jail, and jail is not a safe place to be.” (They had previously discussed how much time Rupescissa spent in prison under the rather nasty conditions of that era.) “Seriously, distilling grain alcohol – or any alcohol that comes from fermented food substance – is illegal by federal law. You don’t have to check the regulations in your state. Illegal. Guaranteed. And dangerous. Don’t drink anything made in these demonstrations, and certainly don’t drink anything run through this still… the type of alcohol we will be distilling is not the same as the alcohol in highballs and is in itself a poison.” (They use rubbing alcohol or 2-propanol.)

One of my favorite demonstrations is “The Parting of Gold”. The authors tell us how to make the combination of mineral acids (HCl, H₂SO₄, HNO₃) needed to dissolve gold and separate it from other metals. I should have brought this up when I introduced acids and bases in class, but I hadn’t got to this demo yet. Anyway, one starts by making sulfuric acid known as oil of vitriol, in this case by placing a rock consisting of iron(II) sulfate and heating it up like crazy. It took a lot of work to get just a few milliliters of the acid so they continued the rest with commercial sulfuric acid (which one can easily get from aquarium pH-lowering solution). The next step is to drip the sulfuric acid into common table salt (NaCl) and collect the gas (HCl) formed. Hydrochloric acid was called “spirit of salt” by the alchemists. When sulfuric acid is dripped onto saltpeter (potassium nitrate or KNO₃), this forms nitric acid also known as aqua fortis (or “strong water”). When the three acids are present together in a solution, the mixture is known as aqua regia (“royal water”) because it can dissolve gold. (I really should learn more Latin!)

The authors recommend using 14-karat gold wire as the starting material from a jewelry-supply outlet so that the sample is free of lead and nickel. Copper is present, and the experiment involves an intermediate step separating out a beautiful blue copper solution before finally leading to the gold solution. If I ever get to teach a class on alchemy, this gold separation experiment might be on the list of things that are interesting and not too unsafe. Several of the other demonstrations, while I think they are fascinating, are a tad on the scary side for me as a theoretical chemist. I can do lab experiments (and I do teach General Chemistry lab), but I’m not particularly interested in heating up different ores on a skillet to high temperatures. I could however do the Tree of Diana, Invisible Ink, or the “Stone that moves on its own”. Feel free to check out that the book if you’re interested.