When you buy a biography of a scientist, you expect it to describe the science that justifies the book in the first place ¨C right??Be careful: if the biographer is an academic you may get less science than you hope for or, in extreme cases, almost none at all.?And it will be your fault.

I look for a biography of a scientist to tell me about their personality, their work and the context in which it was carried out. Rosalind Franklin: The Dark Lady of DNA?(Harper Collins, 2002) by professional biographer Brenda Maddox, is an outstanding exemplar. But where the author is an academic, the situation may be quite different. Here are three contrasting examples and the scores that I have given them in my own self-made metric of Description of science.

Pure Intelligence (University of Chicago Press, 2015) is the late Melvyn Usselman¡¯s account of the life of largely forgotten chemist and entrepreneur William Wollaston (1766 - 1828).?Wollaston discovered the elements palladium and rhodium, as well as developing a commercial process for the purification of platinum. Usselman gives the full technical details of his subject¡¯s work. Indeed, so absorbed was he by them that, with colleagues, he reproduced some of Wollaston¡¯s key experiments in his own lab. For me and probably for anyone else interested in Wollaston¡¯s work, this is what I am looking for in an informative, well-balanced book.?Score for Description of science: 95/100 (nobody gets 100).

The Experimental Self: Humphry Davy and the Making of a Man of Science (University of Chicago Press, 2016) is Jan Golinski¡¯s study of the inventor of the miner¡¯s safety lamp and discoverer of sodium and six other chemical elements, who lived from 1778 to 1829. His book gives roughly equal weight to six aspects of Davy¡¯s life, one of which is ¡®the discoverer.¡¯ Others include the dandy, the enthusiast and the traveller.? Score for Description of science: 45/100.

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Making Marie Curie: Intellectual Property and Celebrity Culture in an Age of Information. (University of Chicago Press, 2015) is by Eva Hemmungs Wirt¨¦n. Curie¡¯s most important discoveries, made in 1898, were the radioactive elements radium and polonium (named for her native Poland). Wirt¨¦n argues that the story of these scientific advances is ¡°too well known to need repeating¡± and so tells us instead about a wide range of Curie¡¯s other activities, including her affair with Paul Langevin and her attitude to patents and patenting.?Score for Description of science: 5/100 (nobody gets 0).

I write this not to criticise Golinski, Wirt¨¦n or indeed any other author.?Golinski is very clear that his is not a comprehensive biography of Davy. He is equally upfront that his first interest is in Davy¡¯s personality and personal development. Wirt¨¦n¡¯s subtitle shows very directly where her interest lies, which is certainly not in Curie¡¯s science. And it is desirable, indeed essential, that other aspects of a career?that has been as well documented as Marie Curie¡¯s, are fully explored.

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There is a very simple reason why academics are able to pick and choose the aspects of their subject¡¯s life or work that they focus on ¨C money. Professional biographers?such as Maddox depend on book sales for their income. They will normally look to appeal to as wide a readership as possible, and where their subject is a scientist, this must mean that the science takes centre stage.?The academic biographer is luckier.?Their income, while probably not massive, is at least steady and assured. They will normally expect to make only a little extra from book sales.?Their best hope, financially, is that a well-received book generates a promotion.

So as a potential buyer, you have been warned. The author¡¯s academic credentials may be impeccable, but beware.?Your prospective purchase may, or may not, contain science.

Richard Joyner is?emeritus professor of chemistry at?Nottingham Trent University.