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Start The Science of the ‘Gin and Tonic’
28 September 2018

The Science of the ‘Gin and Tonic’

Estimated reading time Time 4 to read

The authentic gin and tonic has a refreshing scientific history behind it, the recipe of which would consist of one part carbonated water invented by Joseph Priestley, another part tonic water developed by Jacob Schweppe, the bark of the quinine tree of Peru, and a generous serving of gin. We review the history of each of these parts that, once combined, launched the gin and tonic as a remedy against malaria in the English colonies. However, modern science questions its effectiveness nowadays.

Gin and tonic was born as a remedy against malaria. Credit: Toni Cuenca

Today we know Joseph Priestley (13 March 1733 – 6 February 1804) as the discoverer of oxygen, but before that achievement he had already earned the highest distinction awarded by the Royal Society—the Copley medal—for having discovered a procedure for making sparkling water. In the eighteenth century, with the development of modern chemistry and chemical analysis, a new generation of chemists and pharmacists began to prepare and market bottled mineral waters for therapeutic purposes. Thus arose the debate over the superiority of either the new bottled remedies or the traditional water treatments offered by health spas.

Proponents of this manufactured “spring water” argued that, thanks to chemistry, the composition of a mineral spring could be determined, reproduced and even improved in order to optimise its healing attributes and eliminate possible toxic or harmful substances. In addition, the bottled mineral waters were much more accessible and affordable. For their part, the defenders of traditional treatments argued that the beneficial effects were intimately linked to the spring from which they emerged, and they used as their main and incontestable argument the effervescence of the waters of some springs, the so-called “mineral spirit,” an essence that the artificial waters did not possess and that even the water collected from the spring lost in a short time. This prompted Joseph Priestley to reproduce in his laboratory the “bubbling spirit” of the medicinal springs.

Sparkling water for scurvy

In 1767, in an article entitled Impregnating Water with Fixed Air, Priestley described the procedure he had conceived of and the device he designed to put it into practice: to simplify, it consisted of dripping sulphuric acid onto calcium carbonate to generate carbon dioxide (CO2), which was directed though a column of water in agitation, which induced effervescence. All this effort resulted in “extremely pleasant sparkling water,” in his own words.

Apparatus used by Priestley’s for making soda water. Source:

Priestley never showed any interest in giving a commercial application to his method, but he was interested in solving a big problem for the British navy: scurvy. Aware of recent research that seemed to show that CO2 stopped food from rotting, Priestley intuited that drinking carbonated water could cure and prevent disease. His theory convinced the Royal Navy, which agreed to bring his device on board to produce sparkling water for the crew of Captain Cook’s second expedition to the Pacific. The result was not the desired one, but this initiative marked the beginning of a long friendship between British explorers and carbonated water.

From watchmaker to tonic manufacterer

The person who made the most of Priestley’s achievement was Jacob Schweppe, a young Swiss-based watchmaker who sensed the possibilities offered by carbonated water. He patented a new method to produce it and, in 1783, abandoned his watch business to start marketing it under the name of Schweppes. But Schweppe was not the only fizzy water entrepreneur around. Those years saw many soda manufacturers go into business with products sold as medicinal remedies or tonics, an effect that they reinforced by adding extracts of plants and trees with healing properties: anise, wormwood, mint… This also gave them a unique and characteristic flavour, a factor to help consumers decide on one or the other.

Advertisement of Schweppes’ waters, published 1883. Credit: Schweppes

At the beginning of the seventeenth century, the Spanish conquerors in Peru learned about the great medicinal properties of the bark of the cinchona tree, which was used by indigenous peoples. In 1817, the French chemists Pelletier and Caventou were able to extract and isolate the active ingredient, known as quinine. Its effectiveness in alleviating the symptoms of malaria was such that its use as a preventive medicine soon became institutionalised among Europeans in distant lands, including the British soldiers and administrators who were living in India.

The drink of the British soldiers

But quinine was very bitter, so the British soldiers got used to drinking it mixed with sparkling water—then very popular in England—and sugar, in a combination that made it much more pleasant. And that idea did not go unnoticed by English businessmen. Erasmus Bond was the first to launch a commercial tonic in 1858, which combined the three previous ingredients (bubbles, quinine and sugar); but it was Schweppes that blew its competitors out of the (carbonated) water thanks to its “Indian Quinine Tonic,” launched in 1870, which was specifically targeted at the growing market of overseas Brits.

Bark of the cinchona tree. Credit: gokalpiscan

At this point, it was inevitable that some British soldiers would try to brighten up the invigorating drink (and their harsh days) with a dash (or two) of gin. The combination was so successful and so popular that Winston Churchill himself did not hesitate to proclaim: “gin and tonic has saved more Englishmen’s lives, and minds, than all the doctors in the Empire.”

Churchill’s affirmation is somewhat outdated today because the daily consumption of tonic water—the modern version has a concentration of quinine of about 58 milligrams per litre— neither combats nor prevents malaria, as researchers from the Institute of Tropical Medicine in Hamburg confirmed experimentally in 2004. As explained by those responsible for the study: “Considerable quantities of tonic water may, for a short period of time, lead to quinine plasma levels at the lower limit of therapeutic efficacy and may, in fact, cause transitory suppression of parasites (Plasmodium falciparum, which causes the disease). However, continuous levels that are appropriate for malaria prophylaxis cannot be maintained with even large amounts of tonic.”


Miguel Barral


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