Hasok Chang is Hans Rausing Professor of History and Philosophy of Science at the University of Cambridge, and the current British Academy Wolfson Research Professor. A past President of the British Society for this History of Science, Hasok is the author of Is Water H 2 O? Evidence, Realism and Pluralism (Springer, 2012), and Inventing Temperature: Measurement and Scientific Progress (Oxford University Press, 2014, joint winner of the 2006 Lakatos Award). This article is a modified version of H. Chang, “Making and Unmaking Gold: Confessions of an Anti-Alchemist”, Whole Terrain, vol. 20 (Heresy), 2013, pp. 21-24. We thank the Whole Terrain team at Antioch University for permission to reproduce the article. Please visit the Whole Terrain website, and follow/like Whole Terrain on Twitter and Facebook.

Alchemy, Science and Heresy



The alchemists of old dreamed of making gold out of base metals. From the viewpoint of later scientific chemistry, the whole idea of transmuting one element into another was absurd. Alchemy taken as chemistry seemed so outrageous as to prompt Carl Jung to argue that it was not chemistry at all, but a set of symbolic expressions erupting from the collective unconscious.

But today’s heresy can be tomorrow’s common sense in science. Physics in the twentieth century has clearly demonstrated that one chemical element can be transmuted into another. This happens in radioactive decay, and also in particle accelerators (once colorfully called “atom-smashers”). The atomic bomb, a by-product of research into such processes of transmutation, soon removed any doubts about their reality. Was this a revival of alchemy?

Most scientists were not keen to have modern nuclear physics associated with the sooty reputation of alchemy, though some took pleasure in the rhetorical shock-effect of drawing a link between the two. It was duly pointed out that nuclear reactions were nothing at all like the processes employed by the alchemists. Yet there is a humbling lesson in all this.

The 19th-century scientists had so confidently dismissed alchemy on the basis of what we now think is a false belief. They reasoned that alchemy was futile because each chemical element consisted of a distinct kind of atom and every atom was indestructible and immutable; therefore, there could be no transmutation from one kind of atom to another. Later scientific advances showed that atoms had internal structures, and that they were made up of other particles. Ironically, modern atomic physics made nonsense of the very word “atom,” which means “indivisible”, more literally “uncuttable” (a-tom, “tom” as in “appendectomy” or “microtome”).

Some of the greatest scientific advances originated as heresies. We have the familiar story of Galileo facing the traditional doctrine that the earth was stationary and at the center of the universe. Similar obstacles to progress have also existed, though in more benign forms, within science itself. Alchemy provides a good case in point. In the late 19th century it was scientifically unimaginable that an atom might break up, because then it would become a different kind of atom, and that would be alchemy. This is why the great Dmitri Mendeleev, creator of the periodic table of elements, refused to accept that the electron was a sub-atomic particle as J. J. Thomson argued. He feared that Thomson’s conception would invite alchemy back into science. One can sympathize with Mendeleev, but if his stance had prevailed, modern physics could not have flourished in the way it did.

Un-making Gold

Alchemy was always much more than chrysopoeia (the art of gold-making). Many alchemists sought health as much as wealth: even the glitter of precious metals was nothing compared to the promise of eternal life. This was the case particularly in Chinese alchemy, but in European alchemy, too, there was a strong medical component seeking the “elixir of life.” Sometimes the gold and the elixir were identified with each other. In that context began the quest for “potable gold,” which was expected to do medical wonders. Ironically, according to today’s medical wisdom gold is poisonous if ingested.

Medieval alchemists did know how to dissolve gold, using aqua regia (“royal water”), a mixture of muriatic acid (hydrochloric acid in modern terms, HCl) and aqua fortis (“strong water”, nitric acid, HNO 3 ). Aqua fortis, itself a creation of alchemists, is remarkable in its ability to dissolve copper and silver readily. Mixing it with muriatic acid results in a wondrous effect: although both acids are colorless, their mixture takes on a red color and starts bubbling; in that active state this mixture can dissolve gold. But of course this was of no medical use, as drinking aqua regia would kill you before the gold dissolved in it would have a chance to exert its alleged beneficial effects. This liquid gold was not potable.

It was quite by accident that I came to make some potable gold two years ago, several centuries too late for the alchemists. I was investigating the history of the invention of the battery by Alessandro Volta in 1800. Volta’s battery was a “pile” of cells stacked high, each cell consisting of two pieces of different metals and a wet layer soaked in brine (an aqueous solution of various salts, mostly common salt, which is sodium chloride, NaCl). Volta’s contemporaries never reached a consensus on exactly what role the salt water was playing in the generation of electricity. Trying to learn for myself the electrical properties of salt water, I passed some electricity through it by inserting electrodes connected to two household AA batteries into a flask of salt water. I was using a gold wire as the electrode on the plus side, because electrodes made of other metals are known to oxidize or corrode. To my great surprise, as soon as the batteries were connected, I saw the gold wire dissolve into a yellow streak flowing down. When I showed this reaction to my colleague Jenny Rampling, a historian of alchemy, she dubbed me an “anti-alchemist,” an un-maker of gold.

Through further experiments I learned that this gold-dissolving reaction happens only in a narrow window of applied voltage, roughly between 2.2 and 3 volts. Below 2.2 volts nothing happens. Beyond 3 volts, the gold electrode does not dissolve, but chlorine gas is produced. It was serendipitous that in my initial experiment I used two standard AA batteries (which together give 3 volts): our local electronics shop only stocked double battery-holders, though I went there looking for single ones.

I have shown this experiment to dozens of professional chemists and chemistry students. There hasn’t been a single person not surprised to see gold dissolved in salt water with the help of mere 3 volts of electricity. The kinds of things I was looking into, arising from my work in the history of science, are quite far from cutting-edge issues in today’s chemistry. It was surprising to me that none of the chemists I spoke to had ever conducted this experiment before — but then again, why would they? Perhaps I have a heretical sense of what scientists ought to be attending to.

I have a lot more work to do. As yet I don’t know the exact identity of that yellow streak that comes off the gold electrode. It must be some sort of gold chloride, but an exact analysis will need to be performed. I also don’t know why the reaction happens only in a narrow range of voltages applied. I am not a chemist, and my chemist colleagues at the Universities of London, Cambridge and elsewhere have not had ready answers to all of my questions. But I hope they will continue to help me in my research.

Fritz Haber and the Quest for Oceanic Gold

Fritz Haber, a Jewish German chemist of the early 20th century, had a different dream involving gold: to rescue the German economy from its ruin following the First World War, by extracting gold from seawater. Haber had won the 1918 Nobel Prize in chemistry for his pioneering work on the Haber-Bosch process for the synthesis of ammonia, a key ingredient in the manufacture of chemical explosives and fertilizers, both crucial for Germany under the wartime blockade. There was an outcry against the decision to award the Nobel Prize to Haber, who was widely considered a war criminal; aside from making ammonia, he had also busied himself spearheading the German chemical warfare initiative. Haber personally directed the first major deployment of chemical weapons in human history, unleashing chlorine gas on unsuspecting Allied troops in Ypres in Belgium in April 1915. After the war Haber was heretically unrepentant about his work, scientific and military; he was only serving his country, and chemical weapons in his view were not intrinsically more terrible than the “conventional” weapons that blew people’s bodies apart and gave survivors nasty septic wounds.

Haber was determined to serve his country again after the war, to the best of his ability. The Swedish physical chemist Svante Arrhenius had estimated that there was eight million tons of gold dissolved in the oceans of the world. If Haber could find an economical process for extracting this gold, would that not throw a lifeline to the postwar German economy suffering through hyperinflation and vindictive reparations demanded by the Allied powers? It may sound crazy to believe that there is gold in the sea, but Haber respected Arrhenius, another Nobel Prize winner still renowned for his contribution to the chemistry of ions and also to our understanding of the greenhouse effect and climate change. All the fantastical medieval schemes of filling the state coffers with alchemical gold paled in comparison to the promise of Haber’s project for Weimar Germany.

Evading strict Allied supervision of German research activity, Haber and his team made journeys to far corners of the world and secretly analyzed samples of seawater. They did find gold, but at concentrations far lower than Arrhenius’s estimate, dashing the hopes of an economical gold-extraction process. Haber could not save Germany. And Germany, in the end, did not want him. There was no place under Nazi rule for a Jewish patriot. Haber left Germany in 1933, and died on his way to Palestine.

What if Haber’s dream could have come to pass, even just a little bit? What if helping the German economy would have reduced some of the frustrations feeding into the rising popularity of fascism? Asking “What if” can be an irresponsible thing to do for a historian, and “counterfactual history” is something of a heretical enterprise. But this all depends on why one does history. Sometimes we have to establish the facts, for the record. Sometimes we want to explain and understand why the past was the way it was. And sometimes we need to learn that things could have been otherwise, that today’s status quo resulted from some contingency in the past. This frees our minds from regarding today’s injustices and dysfunctions as flowing from some eternal principles or necessities, and teaches us to regard our present blessings as precious gifts from fragile past circumstances and actions.

Heresy and Science in History

Gold, salt, water — three of the substances that humans value most. Put the three together: gold in salt water is an emblem of some of the most intense human hopes, desires and fears, all mingled together. I imagine my little test tube of golden salt water diffusing into the ocean. From my peculiar vantage point, it makes perfect sense that there would be gold in the sea, though I do not know the exact processes through which it got there. Potable gold always was staring the alchemists in their faces, unrecognized. It will not give us eternal life, or save a nation, but it does serve as a reminder of the gaps that still exist in seemingly infallible and already perfected realms of science.

Ultimately, “science” is just another name for humanity’s humble engagement with nature, in which nature has surprised us time and again, forcing us to redefine repeatedly what is orthodoxy and what is heresy. The history of science shows that the line separating the two has shifted and blurred and sharpened over and over again. It is time that we learned to discard the very notion of heresy. We will, naturally, continue to have our well-considered views, and treat deviations from them with caution and even suspicion. We will continue to defend our core values, and to manage with difficulty any disagreements and conflicts we have with each other about those values. But the idea of heresy embodies a degree of closed-mindedness that shuts off many roads we may travel to find the precious gifts from nature that we need to gather in order to sustain and improve ourselves.

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