The Invention of Air

by Steven Johnson

  Reading the letter now, it is easy to be impressed by the pyrotechnics of Franklin’s style, and by his bleak view toward his own species. But the most moving words come near the end of the letter, as he settles his pen, following the outburst:

  But to be serious, my dear old Friend, I love you as much as ever, and I love all the honest Souls that meet at the London Coffeehouse. I only wonder how it happen’d that they and my other Friends in England, came to be such good Creatures in the midst of so perverse a Generation. I long to see them and you once more, and I labour for Peace with more earnestness, that I may again be happy in your sweet Society.

  There is lacerating honesty in Franklin’s attack on the “very badly constructed” species of man, but what is perhaps most striking in this letter is the emotional honesty in these fond words for the Honest Whigs. When you look at Franklin through the lens of his friendship with Priestley and the coffeehouse society—if you take those closing lines literally—one overwhelming thought confronts you: Franklin was, at heart, a Londoner. He made his name in Philadelphia several times over, and was revered and seduced by Paris, but there is every reason to believe that had King George been a little less aggressive with his tax policy, Franklin would have spent the last forty years of his life in London. He “labours for peace with more earnestness” so that he can return, at long last, to the sweet society of the London Coffee House. No doubt he is exaggerating his adopted-homesickness for the benefit of his old friend, but you have to willfully misread the passage to avoid the conclusion that one of Franklin’s key grievances against King George was that he forced him to board that ship for Philadelphia in 1775, and leave behind the “honest souls” in the shadow of St. Paul’s.

  FRANKLIN MAY HAVE BEEN at the front lines, but Priestley’s ideas were bound up in the American Revolution as well, in his dual capacity as scientist and political theorist. In his musings on his discovery of dephlogisticated air, he had written of its potential military uses, speculating that the new chemical techniques that he had developed might well be employed to improve the explosive power of gunpowder, or make its manufacture more efficient. He shared many of these ideas with a former Portuguese monk he had befriended named John Hyacinth Magellan. Magellan, a descendant of the famous navigator, turned out to be a spy for the French, who sent back to Paris extensive missives on the nascent scientific-industrial complex in Britain, with Priestley’s research playing a starring role. Priestley himself may have shared some of his speculations with Lavoisier during their famous dinner in Paris in late 1774. As it happened, Lavoisier had just been appointed head of Louis XVI’s state-subsidized Régie Royale des Poudres et Saltpêtres (the Royal Gunpowder and Saltpeter Administration), dedicated exclusively to increasing France’s supply of powder. The cutting-edge ideas about combustion that Priestley and Magellan had put in his head—along with his estimable skills as a chemist—made him a brilliant choice to revitalize France’s gunpowder production. By 1777, Lavoisier had increased the annual production of saltpeter to 2 million pounds, and significantly increased its explosive yield. By the early 1780s, France’s saltpeter was widely considered to be the highest-quality powder in the world, propelling canonballs 50 percent farther than the British powder did.

  All that stored energy—created this time by the human-driven processes of industrial chemistry, and not the carbon cycle—would eventually flow across the Atlantic, to the aid of the struggling Continental army. One of the primary reasons Franklin was so preoccupied with matters of war was the simple fact that his country didn’t have enough energy on its side. At the beginning of the conflict, all thirteen colonies had between them only 80,000 pounds of gunpowder, a supply that wouldn’t have lasted half a year of fighting. “Oh, that we had plenty of powder; I would then hope to see something done here for the honour of America,” Nathaniel Greene wrote as he contemplated the British stronghold of Boston from his camp at Prospect Hill, north of the city, in the summer of 1775. By December of that year, Washington announced: “Our want of powder is inconceivable. A daily waste and no supply administers a gloomy prospect.” Supporters of the revolutionary cause in the colonies were given a crash course in the production of gunpowder, but their concoctions were generally of poor quality, and in any event the amount of powder generated was paltry compared to the immense needs of the army.

  What ultimately turned the tide were two interrelated developments, the first predicated on Priestley and Lavoisier’s chemical revolution, and the second on Ben Franklin’s skills as a diplomat. Lavoisier’s innovations in gunpowder production gave the French a stockpile of top-quality powder. During his secret mission to France in late 1776-77, Franklin helped negotiate a pact that brought more than 200 tons of high-grade French gunpowder to the muskets of the Continental army. By 1779, more than 800 tons had been imported. That tremendous influx of stored energy changed the balance of power between the struggling colonial army and the redcoats. “By Yorktown,” Joe Jackson writes, “British soldiers complained that they could not get close enough to shoot colonials before they themselves were blasted from their garters.” From his laboratory in Paris, Lavoisier mused on the role of his saltpeter in the American Revolution: “It can truthfully be said that it is to those supplies that North America owes its freedom.” It was typical of Lavoisier’s self-important style to attribute the American victory to his own saltpeter, and no doubt he exaggerated matters in phrasing it that way. But it is impossible to imagine that freedom being won on 40 tons of mediocre powder.

  Priestley had a hand in the ideas behind the colonial struggle as well. He had published his initial work of political theory, Essay on the First Principle of Government, in 1768, which expanded on Lockean liberal ideals and made some early and influential gestures toward the concept of separating church and state, though it was not nearly as widely read as his scientific publications. At Franklin’s urging, Priestley published in 1774 an address to “Protestant Dissenters of All Denominations” that specifically focused on the “American Affairs.” The pamphlet took a strong stand against “forg[ing] chains for America,” and advised its readers to vote against all members standing for election who supported the existing policies toward the colonies “to the imminent hazard of our most valuable commerce, and of that national strength, security, and felicity which depend upon UNION and on LIBERTY.” By the time Franklin set sail for Philadelphia, Priestley and Richard Price had become the most well-known British supporters of the American cause, in part provoking Samuel Johnson’s famous attack on the colonial uprising, Taxation No Tyranny. Johnson was said to have remarked, “Ah, Priestley. An evil man, Sir. His work unsettles everything.” (He was right about the second bit.) If there was a fifth column rising in support of the Americans among the intellectuals of Georgian England, its epicenter was at the London Coffee House. When Priestley wrote back after Franklin’s first emotional tribute to the Honest Whigs in 1776, he thanked his old friend for his “kind remembrance” of the club, and sent a message of political solidarity: “Our zeal in the good cause is not abated.”

  Despite that zeal, Priestley’s political worldview was still in a germinal state during the 1770s. His output of political pamphlets came to an abrupt halt in 1774, and would not start up again until the next decades. (He would ultimately write much more about the French Revolution than about the American.) This unusual reticence may have been partly attributable to sensitivities of having Lord Shelburne as a patron; while Shelburne had left the Cabinet largely because of his opposition to the king’s taxation policies, he was still very much attached to the Court and Parliament, with some ambition of returning to some official office in the future. For Shelburne to have been seen as funding a vocal supporter of the colonies would have raised eyebrows. And so Priestley kept most of his explicit support for the uprising in America to the word-of-mouth networks emanating from the London Coffee House.

  Priestley was less successful at subduing his religious views. In 1774, he had assisted his friend t
he Reverend Theophilus Lindsey in founding the first official Unitarian denomination, which openly denied the divinity of Jesus Christ and the existence of the Trinity. He published several materialist philosophical tracts during his tenure with Shelburne that questioned the notion of the soul, most markedly Disquisitions Related to Matter and Spirit, in 1777. These were, of course, political acts as much as they were theological ones, since the Test and Corporation Acts prohibited any dissenters from the thirty-nine articles of the Church of England from holding political office. (It was legally considered an act of high treason for a British native to say mass.) When George III lifted some of these restrictions against Catholics, while retaining them for other dissenters, Priestley appealed for a Royal audience to make the case for expanding the scope of reform, working through William Eden and Lord North. The king sent North a curt response that records his antipathy toward Priestley: “If Doctor Priestley applies to my librarian, he will have permission to see the library as other men of science have had: but I cannot think the Doctor’s character as a politician or divine deserves my appearing at all.”

  THERE ARE TWO basic ways to look at Priestley’s years at Leeds and Calne in the 1770s: either taking a contemporaneous approach, viewing his achievements in the context of their time; or, alternatively, taking the hindsight view, from the perspective afforded by our knowledge of all the events that were to come. The first view is simpler, despite all the intricacies of the tale: it’s the story of a great scientist hitting his stride. The hindsight view presents a different picture: the multiple trails of Priestley’s intellectual life converging for the first time, dominated by the science, to be sure, but increasingly integrated with religious and political values. In the next decade, the three paths would combine to form a mighty highway, one that would ultimately drive Priestley all the way to the New World.

  We cannot fully understand Priestley—or the wider context of social change during that period, particularly among his compatriots across the pond—without appreciating the convergence of these three intellectual paths. Scientific innovation tends to be imagined as something that exists outside the public sphere of politics, or the sacred space of faith. (Recall that Kuhn barely mentions either in The Structure of Scientific Revolutions.) But for Priestley, these three domains were not separate compartments, but rather a kind of continuum, with new developments in each domain reinforcing and intensifying the others. When Lindsey opened his Unitarian Church, Priestley defended the move against critics who claimed it would undermine the existing religious authorities by invoking the very same principles that governed his scientific research: expose as many ideas as possible to as many minds as possible, and the system will ultimately gravitate toward truth and consensus. “[The] only method of attaining to a truly valuable agreement,” he wrote, “is to promote the most perfect freedom of thinking and acting . . . in order that every point of difference may have an opportunity of being fully canvassed, not doubting but that . . . Truth will prevail, and that then a rational, firm, and truly valuable union will take place.”

  The critique of the soul launched during the Calne years deliberately followed the same approach that Priestley had taken in his experiments with air in the Leeds laboratory. Just as Priestley had demystified what had conventionally been called the “spirit” of mephitic air, or fermenting liquids, so would he demystify the “spirit” of human existence. These were not metaphors, strictly speaking, but elements of a connected system: the materialism that helped him isolate pure air could just as readily be applied to the theological question of the soul. The presence of a higher power in all of this wasn’t somehow miraculously hovering over the human body; it lay instead in that steady widening of understanding that materialist science made possible. The progressive movement of Enlightenment science stood as the great embodiment of God’s work on Earth—to Priestley a much more sensible embodiment of the divine than a man crucified almost two thousand years before. And that movement had too much force not to wipe away the political and theocratic relics that had been carried over from earlier, less sophisticated ages.

  Priestley’s introduction to Observations on Air, penned in 1774, made the connections explicit: “This rapid process of knowledge,” he wrote, “. . . will, I doubt not, be the means, under God, of extirpating all error and prejudice, and of putting an end to all undue and usurped authority in the business of religion, as well as of science.” To our modern ears, this is a perfectly acceptable premise, though it was daring in its day: that the ascendancy of scientific thinking would challenge the explanatory models of religion. But Priestley then goes on to make an even bolder suggestion, linking the march of scientific progress to political change, and making it clear that his own native country would not be immune: “The English hierarchy (if there be anything unsound in its constitution) has equal reason to tremble at an air pump, or an electrical machine.”

  Part of what makes the hindsight view so intriguing is that we have no figure in the current intellectual landscape, in the United States at least, who fits Priestley’s mold in any convincing way. Here was a man at the very front lines of scientific achievement who was simultaneously a practicing minister and theologian—and who was, by the end of the 1770s, well on his way to becoming one of the most politically charged figures of his time. He was an empiricist driven by a deep and abiding belief in God, who was simultaneously a revolutionary of the first order. In today’s culture, a Venn diagram of science, politics, and faith would show no overlap, particularly if we’re talking about individuals who hold radical views in all three disciplines. There are plenty of politicians with strongly religious beliefs, and plenty of clergymen who have active and influential political careers. But the vast majority of that group is conservative in its values, in the most general sense of the word: they are attempting to conserve and protect some kind of traditional order. And the scientist-politicians—Al Gore notwithstanding—are as rare as the scientist-priests.

  If an echo of the intellectual chord Priestley managed to strike—political thinker, believer, scientist, radical—still somehow resonates in the American context, it is because most of those notes were played, in a slightly different configuration, by the great polymath intellectual of the revolutionary generation, Thomas Jefferson. That the two men were in such harmony was no accident, as Jefferson himself borrowed some of his dominant notes from Priestley’s score. But that is getting ahead of our story.

  BY 1779, PRIESTLEY’S controversial views had created an uncomfortable tension between himself and Lord Shelburne, who would return to public office several years later, serving as prime minister for nine months, starting in 1782. (He would negotiate the close of the Revolutionary War with Benjamin Franklin during that tenure.) When his patron suggested that he had plans to relocate Priestley to Ireland, Priestley took the proposal as indication that he had worn out his welcome. The exact details of the break remain something of a mystery. It may have been a case of Shelburne anticipating his return to public office and recognizing the potential dangers of having a radical Unitarian on his payroll as his son’s tutor. Shelburne was said to blame the whole affair on Priestley’s ill health. (He suffered a debilitating attack of gallstones during this period.) It may have been some kind of strange failure of communication between the two men, as the whole separation played out without any direct dismissal from Shelburne. But the most plausible interpretation comes from Priestley’s biographer Robert Schofield: Shelburne had married his second wife, Louisa Fitzpatrick, in July of 1779. The daughter of the Earl of Upper Ossory, she quickly established herself as an eminent political hostess, and apparently found the Priestleys distasteful, as much for their middle-class sensibility as for Joseph’s radical views. Tellingly, Shelburne attempted a rapprochement with Priestley some years later, and while the dates are not exact, it seems probable that the olive branch arrived after the death of Lady Shelburne in 1789.

  The cause continues to be a matter of debate, but the effect is a matte
r of fact: after extensive consultation with friends, Joseph and Mary Priestley packed up the vials and air pumps and electrical machines (along with their three children) and moved to Birmingham. Priestley was giving up Berkeley Square and Calne for the heart of coal country.

  Shelburne had left Priestley with an annual allowance of £150 to continue his work in Birmingham, but his financial situation was greatly compromised by the break with Shelburne. For some time, Priestley imagined that he would have to return to private tutoring to cover his family’s expenses. But the threat to Priestley’s valuable leisure time was quickly defused. This time around, it would not be a landed aristocrat who saw the value in supporting Priestley’s work—it would be an extended group of wealthy individuals, almost all of whom had made their fortunes in the nascent Industrial Revolution. For the rest of his tenure in England, Priestley would live indirectly off the stored energy of the Carboniferous era.

  The first great break for the Priestleys came when Mary’s brother, the successful ironmaster John Wilkinson, secured a comfortable home for the family at Fair Hill, on the outskirts of Birmingham. The house had four main bedrooms and servants’ quarters, and ample grounds for the children to explore. The upstairs floor had a long, narrow room that Priestley used as a library, though it doubled as a kind of eighteenth-century media room: Priestley would entertain children with magic lantern shows there, and harmless shocks from his electrical machine. The only flaw with Fair Hill was that it didn’t include a suitable space that could be converted into a laboratory, but Priestley quickly turned that liability into a strength by constructing a separate building for his experiments, custom-tailored to his idiosyncratic needs. This was a fitting beginning to his sojourn in the Midlands, since his new coterie of industrial magnates was soon to provide him with a host of new tools designed according to his exact specifications. The Priestleys moved to Fair Hill in September of 1780, and by the end of November, the new laboratory had been completed. Priestley wrote the potter Josiah Wedgwood to report that he was ready “to do more business in a philosophical way than ever.”