The Invention of Air: A Story of Science, Faith, Revolution, and the Birth of America
by Steven Johnson
Reviewed by Seymour Mauskopf
Steven Johnson's latest book, The Invention of Air, focuses on the life and career of Joseph Priestley. Its provocative title encapsulates its themes: "The Invention of Air" is a kind of double entendre, referring both to Priestley's work in pneumatic chemistry and -- more grandiosely -- to the genesis of our oxygenated terrestrial atmosphere, beginning with the emergence roughly two billion years ago of the first organism capable of photosynthesis. The subtitle, A Story of Science, Faith, Revolution, and the Birth of America, delineates Johnson's two principal biographical themes: first, Priestley as the embodiment of the Enlightenment ideal of the interrelation of scientific practice, religious belief and political action; and second, Priestley as a significant influence on some of the most important early American leaders, particularly Benjamin Franklin, John Adams and Thomas Jefferson.
The biography is structured around Priestley's participation in three different social networks. The first was a social milieu extremely important to Enlightenment culture, the urban coffeehouse club -- in this case, the Club of Honest Whigs, a biweekly London gathering presided over by long-standing London resident Benjamin Franklin. Priestley, a teacher at the Warrington Academy in Yorkshire, was interested in the exciting science of electricity and wanted to write a popular history of the field, so in 1765 he went to the club to meet Franklin. The personal association with Franklin lasted until the latter was compelled to return to the Colonies in 1775. Priestley's association with the Honest Whigs persisted much longer. It was in these years and this context that he did his most significant scientific work -- particularly on the composition of air.
The second network was the Lunar Society of Birmingham, where the Priestley family moved in 1780. Birmingham was in the Midlands, a region that was rapidly developing into the industrial heartland of England. Hence the "Lunaticks" included some of the new leaders of industry, such as John Wilkinson (Priestley's brother-in-law), Josiah Wedgwood, Matthew Boulton and James Watt. Other local intellectuals -- Erasmus Darwin, for example -- were also members. Both Priestley and Franklin had been previously associated with the Lunar Society, but in the 1780s Priestley became a core member. He had new kinds of interactions here: Some of the industrialists supplied him with experimental apparatus, and Priestley in turn functioned as a protoscientific consultant to them.
More particularly, in Birmingham in the 1780s Priestley had what Johnson terms the second of two "streaks" in his career. The first had involved his scientific activities in the decade from 1765 to 1775, climaxing in his work in the chemistry of gases. The second streak brought into prominence the two other activities that make up Johnson's Enlightenment ideal: religion and politics.
Like Priestley's London coffeehouse associates, the Lunaticks favored religious and political radicalism, and in this environment Priestley began to publish prolifically. He was profoundly religious but was at odds with the established Church of England: He was one of the founders of Unitarianism and a Unitarian minister. He published many religious tracts and sermons. In 1782, in An History of the Corruptions of Christianity, he attempted nothing less than to purge Christianity of its superstition (including belief in the Trinity and the divinity of Christ) and idolatry, through the cleansing agent of scientific rationalism. The work provoked outrage in England (although, Johnson argues, it had a profound effect on Thomas Jefferson).
After 1789, hostility toward Priestley was further aggravated by his vocal support of the French Revolution. On July 14, 1791, a "church and king" mob, inflamed by the holding of a commemorative Bastille Day dinner in Birmingham, destroyed his house and laboratory.
In the spring of 1794 Priestly emigrated with his family to the United States, where he initially received a hero's welcome. He settled in the woods just outside the small town of Northumberland in central Pennsylvania. His interactions in America during the final decade of his life constitute the third social network. Although physically isolated for the most part, Priestley did participate in general discussions via correspondence, publications and occasional forays to Philadelphia. Johnson pays particular attention to Priestley's interactions with Jefferson and Adams regarding religion and politics (Priestley opposed the Alien and Sedition Acts of 1798, and there was pressure on Adams to deport him). In many respects, this part of the book was the most novel to me. I had had no idea that Priestley was more than a spent force in America, much less that he was simultaneously an object of admiration and a bone of controversy to Jefferson and Adams.
Readers of American Scientist will no doubt be most interested in Johnson's account of Priestley's discoveries in chemistry, for which he is most famous. Johnson focuses on two related ones, both dealing with the salubrity of the air. The first experiment, carried out in 1771, relates to the ability of plants (mainly sprigs of mint) to rejuvenate air -- that is, to enable air that has lost the ability to support respiration and combustion to regain it. The second discovery, made three years later, was the production of a type of uncommonly rejuvenated air (in the above sense), which Priestly called dephlogisticated air -- a term later superseded by Antoine-Laurent Lavoisier's name for it, oxygen.
Interestingly, Johnson chooses to focus on the first discovery, seeing it as the precursor to modern ecological theories. He devotes an entire chapter to modern investigations and theories about the genesis of our oxygenated atmosphere, tracing the intellectual origin of this science back to Priestley's "sprig of mint" experiments. Curiously, though, he ignores Priestley's own theological views on the providential use of plants to restore the atmosphere and maintain the balance of nature.
In his account of Priestley's second and more famous discovery of oxygen, Johnson explicitly refers to another book on Priestley, Joe Jackson's World on Fire: A Heretic, an Aristocrat, and the Race to Discover Oxygen (2005). Unfortunately, Johnson's telling suffers from the same limitation as Jackson's -- namely, retrospective negative evaluation of Priestley's phlogistic interpretation of his discovery, implying that somehow Priestley should have known better. Historians of science have long ago moved away from this kind of progressivist judgment of earlier scientific theory and practice. In my opinion, it spoils Johnson's treatment.
In his account of what enabled Priestley's discovery of various gases, most notably oxygen, Johnson invokes technological history and the deployment of new tools such as the air pump. However, he omits the most important one, the pneumatic trough (and its inventor, Stephen Hales), even though it is featured prominently in "Priestley's Tools," the illustration at the start of chapter 2.
Nevertheless, this is a well-written and engaging book on Priestley and his times. In general terms, it is not original; the interactions of theology, politics and science in Priestley's life and work have often been recounted. Johnson's focus on Priestley's experiments with sprigs of mint in 1771 and his account of Priestley's interactions with Jefferson and Adams are more novel and provide interesting sidelights on Priestley's rich and fascinating life.
Seymour Mauskopf is a professor in the Department of History at Duke University. His research interests include the history of chemistry and allied sciences in the 18th and 19th centuries (Crystals and Compounds ); the history of chemical technology, focusing on munitions and explosives; and the history of parapsychology and marginal science (The Elusive Science: Origins of Experimental Psychical Research, with Michael R. McVaugh ).