A few years ago, cartoonist Randall Munroe, author of the endlessly insightful animated series XKCD, published a book called What If? Which collected a series of silly questions which were then answered by Fermi estimates, cliched line drawings and weird aspects. Contrary to popular belief, “what if” is the fundamental question of science that makes it possible for us to finally arrive at answers to the second question: “why?”. Among the advocates of the “what-if” school of exploration are Humphry Davy, a chemist considered by many to be the greatest scientist of his time—a great esteem in a crowded field.
Davy came from then remote Cornwall. His father died when Humphrey was very young, forcing the family to sell their small land. His mother set up a small hat-making business and made sure her children were educated. Humphrey was a rather exceptional kid, reading confidently at the age of five, showing real promise in grammar school and cruising the coast in search of good fishing spots. Along the way, he built up an exceptional knowledge of both the fish species and the geological features of the area. His interest prompted him to conduct chemical experiments in his room. He was later trained as a local surgeon with the goal of becoming a doctor. The looseness of these arrangements led him to be largely self-taught; He read widely but gradually focused on chemistry, his readings including William Nicholson’s Dictionary and Antoine Lavoisier’s Elementary Thesis. Some of his biographers have concluded that his unusual blending of reading also left a deep loopholes In learning it would limit his progress later.
His enthusiasm for chemistry spread and in 1798 his friend Davis Gilbert recommended him to physician Thomas Bedus. Beddoes recently set up a compressed air institute in Clifton in Bristol where he hoped to use “aerobic fluids” to treat disease. The increasing number of gases being discovered seemed to indicate that there was a large part of the investigation for which a chemist was needed. Davy began making gases and testing their effects. It has conclusively shown, in contrast to a previous suggestion, that nitrous oxide does not cause disease. Then he went on to display his indisputable effects on animals and humans. However, the term laughing gas did not appear until a decade later. For Beddoes, these results were a victory.
In 1800, when talk of Alessandro Volta’s pile producing electricity spread, and almost immediately followed by William Nicholson and Anthony Carlisle’s report on the electrolysis of water, Davy began experimenting with electrical experiments himself using a pile he had Bedo in his laboratory. This led to a series of papers that further spread Davy’s reputation. Davy won’t be in Bristol for long. Count Rumford, the American scientist and businessman who founded the Royal Institution (RI), invited Davy to London. He was unaffected. Davy struck him as a kind of rustic yoke, unsuitable for the elegant community of London. But one public lecture, in which Davy spoke with exceptional force and clarity, was enough to change Rumford’s opinion. Davy was offered a position at RI where his brilliant lectures, full of explanations of his discoveries, began to attract large audiences. It is sometimes said that it was Davy’s lectures that forced the authorities to make Albemarle the first one-way street in the city to accommodate traffic. In fact, this was already the case for several years as Rumford and his colleagues were not slack as speakers. But Davey cemented the reputation of Rotary International among the young and fashionable. Unusually, women began attending lectures that had previously been seen as “masculine”.
In the basement of the building, Davy continued his experiments, ordering larger arrays of metal plates to experiment with. It was soon found that different metals had different electrical resistances that also depended on the dimensions of the wire. A platinum wire can be heated until it glows – the observation that defined a pre-incandescent light bulb. Carbon also conducted electricity, an observation that laid the foundation for the later Bunsen and Leclanchy cells. As he used ever more powerful batteries, he began shredding the material, reducing many of the alkaline and alkaline earth salts to their metals. But it can also get sparks that jump between adjacent electrodes. To his surprise, the separation of two carbon electrodes attached to large battery electrodes resulted in a bright white glowing “arc” of blinding intensity in the space between them.
With a battery of 2,000 metal plates connected to a coal rod, a bright spark was produced, more than half the volume of coal ignited to white, and by pulling the points together, a continuous discharge occurred through the hot air, in an area of at least four inches, resulting in an arc Bright ascending of light, broad, and conical in the middle’.
It was the original arc light – it later became the most intense practical light source in common use.
Davy’s electrical experiments opened up vast areas of chemistry, physics, and technology, culminating in the 1980s with the discovery of fullerenes and carbon nanotubes. I don’t know about you, but I suspect he would have loved XKCD.
Thanks to Frank James from UCLA and RI for sharing some of his encyclopedic knowledge