The refreshing tale of gin-and-tonic (well, half of it…)

Just the tonic, by Kim Walker and Mark Nesbitt 2019. Royal Botanic Gardens Kew.

What is: carbonated water, citric acid, sodium citrate, natural quinine, and aspartame? That is the declared list of ingredients in a can of Schweppes’ tonic water (slimline variety). Arguably, that listing is ‘just the tonic’, which is also the title of a book by Kim Walker and Mark Nesbitt. But, by most measures of worthiness, water and a small bunch of other chemicals doesn’t really appear substantial enough to justify a whole book – even a relatively slim one of approx. 140 pages of main text. But that view would be quite wrong – as Walker and Nesbitt so admirably and effectively show in their charming – and refreshingly slimline – book.

True, Just the tonic does look at the main ingredients within tonic water (which, to dispel any doubt, are the carbonated water and the quinine), but the authors do so much more than merely repeat them in their fascinating tome. Importantly, they provide what can probably best be called the ‘social history of tonic water’ – which immediately takes us far beyond just the ingredients of this fizzy drink. And their musings lead naturally – and inevitably – to one of the greatest pairings in the world of food and drink, the gin and tonic, which takes tonic water to the next level. But, we are getting a little ahead of ourselves – keen as we no doubt are to get to the alcofreshing* reward of a nicely iced-and-sliced G&T. So, back to the book…

Although the section about tonic water specifically is quite short (it’s amongst the 12 pages of Chapter 5 that also deal with tonic wines, aperitifs and digestifs), the book’s great strength is the much-more-numerous other pages that provide the proper context for appreciating tonic water’s significance – such as the 48 pages on quinine and malaria, and the 14 pages devoted to soda water… Why? What is the relevance of this? In Just the tonic, many different strands are skilfully woven together so that the whole is very much more than the sum of its parts.

Strand 1: The main flavouring in tonic water is quinine, an alkaloid originally extracted from the bark of a tree of the genus Cinchona native to South America. Historically, quinine has proven very effective as both a preventative and cure for malaria (Jane Achan et al. Malaria Journal 2011,10:144, and was also used in treating other fevers (DJH Dickson, Edinb Med Surg J. 1823 Oct 1; 19(77): 571–573; MK Davies and A Hollman, Heart, 88(2): 118–118, 2002; doi:10.1136/heart.88.2.118). This background, and tonic-promoting property of quinine, led to its widespread medicinal use. However, quinine is bitter and attempts to mask this with other ingredients – such as alcohol – inspired the creation of more pleasant-tasting drinkable ‘tonics’.

Strand 2: Development of fizzy carbonated water by “free-thinking English chemist and maverick theologian” Joseph Priestley in the last third of the 18th century. This concoction gradually became better known as soda water, an effervescent drink that was promoted for its own health-giving properties. The pairing of quinine with soda water – and substitution of citric for sulphuric acid – by Schweppes around 1870 gave the world Indian Tonic Water.

Strand 3: The short history of gin is also told by Walker and Nesbitt, who reveal that the first known reference to gin and tonic as a bar cocktail is in 1865, and this drink gave its name to a geographical region, the ‘gin and tonic degrees of latitude’, such as India during the British Raj.

Strand 4: “Ice is also an essential ingredient … [in] gin and tonic”**, so the authors duly oblige with an abridged history of ice by way of ice houses, shipped ice, and the development of the domestic fridge…

I’m greatly summarising the book, which also gives fascinating insights into the cinchona plants (and their removal – usually illegally – from South America to establish plantations in India and SE Asia by the British and Dutch colonial powers, respectively), and the impact of malaria which threatened to curb the colonialism and empire-building of the European powers in the 18th and 19th centuries. Indeed, so important was this alkaloid to this imperialist expansion it’s been claimed by Daniel Headrick that quinine was one of the ‘tools of Empire’. As with George van Driem’s The tale of tea, another plant-derived material – this time quinine packaged as tonic water (with or without gin) – has been used to great effect to tell an amazing tale of plants-and-people interactions. And not only that…

Just the tonic is beautifully illustrated throughout – one has to make special mention of the end papers which are exquisite drawings of microscopical observations of cinchona bark by Walter Hood Fitch. The text is readable, engaging, informative, and entertaining – and the book could probably be read in a single sitting (which is as much a tribute to its readability as its length). The use of ‘boxes’ and short sections all help to maintain variety in the text and further facilitate its ease of reading. From maintaining a narrative – and reading – flow point of view, there are no in-text references (nor foot-notes). But, from a pedagogic point of view, there is an extensive list of Further Reading, organised by the book’s 7 main academic chapters and including scientific articles and books.

Just the tonic is a charming book, and with commendable modesty the authors predict that the history of gin and tonic will be more refined as more resources come on-line. And it’s an important story, so the more we find out the better will be our modern-day appreciation of this long-established association of humanity and quinine. I urge you to read – and savour! – Just the tonic. But be warned, having now had your thirst for more G&T information thoroughly whetted by Walker and Nesbitt’s book, you’ll have to wait until autumn 2020 for The botany of gin by Chris Thorogood and Simon Hiscock to read more on this topic***.


This is a wonderful book, and a great resource to add to the blossoming literature on plants-and-people. It’s not only me who thinks this highly of the book: Just the tonic has been awarded the ‘debut drink book’ award in Fortnum & Mason eighth annual food and drink awards. Now, if only there was a suitable drink we could use to celebrate this achievement…

* A new word(?) that combines alcoholic and refreshing. And, talking of new words, my only remaining question having read Just the tonic is what does ‘adveefashionable’ (on p. 78) mean?

** As is a slice of lemon; and, yes, Walker and Nesbitt have something to say about that as well…

*** But, if that’s too long to wait, look here and here for more tonic-related items.