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PRIESTLEY

1733-1804

DURING the reign of George II. and six years before the war with Spain, Joseph Priestley was born on 13th March 1733, at Fieldhead, a hamlet near Leeds. He was destined to be a remarkable man in more ways than one, whose work will live as long as time endures, and whose moral character was above reproach.

Priestley's father was a cloth dresser, and his mother a farmer's daughter. The mother dying when Priestley was seven years old, the home, managed by his father's sister, became the meeting-place of numerous dissenting ministers, who helped to mould the character of the boy, for in after life his work became divided between science on the one hand, and theology, metaphysics, and politics on the other. During his schooldays and subsequently he acquired a knowledge of Latin, Greek, Hebrew, Syriac, Chaldean, Arabic, French, Italian, and Dutch; also logic, metaphysics, mathematics, and natural philosophy. Although not blessed with the best of health, he was always of a cheerful temperament, so much so that he

alt-portrait of Joseph Priestley, appears circa 1800

Statue of Joseph Priestley in Birmingham, circa 1910s

Joseph Priestley and his statue in Birmingham

even looked upon ill-health as an advantage rather than the reverse, because with health he says he might have been fond of sports, and occupied his time in other ways than in studies. Anybody reading Priestley's memoirs will see that he was no believer in the old adage "mens sana in corpore sano."

In the year 1752, or when he was nineteen, he went to the Dissenting Academy at Daventry, and at this institution developed the power of free discussion on most subjects, especially theology: and as Priestley tells us in his Autobiography, he was generally on "the heterodox side of almost every question."

After three years at the Academy, namely, in 1755, Priestley became a Calvinistic minister at Needham Market in Suffolk; but whether it was due to his heterodoxy or to his stuttering, the congregation left him, and he was obliged to seek fresh pastures. Too great to be fettered by rules, too original to condescend to imitation, he consulted his own inspiration only, and, like other workers, had to pay dearly for living apart from the general weal of mankind. After other vicissitudes, he removed in 1761, one year after the succession of George III. to the throne of his ancestors, to Warrington, having been appointed tutor of languages in a dissenting academy. Here he gave instruction in Latin, Greek, Hebrew, French, and Italian, and lectured on logic, on elocution, on the theory of language and universal grammar, on oratory and criticism, on history and general policy, on civil law, and on anatomy. A goodly number of subjects, but Priestley was a most versatile man, as the catalogue of his 108 books published in 1794 bears witness. During his six years' residence at Warrington, he married the daughter of Isaac Wilkinson, an ironmaster of Wrexham, and the union proved a happy one. In 1766 he became acquainted with Benjamin Franklin[1] (who lived in Craven Street, Strand, London). The acquaintance ripened into friendship. Franklin encouraged Priestley in his philosophical pursuits, and no doubt this was the origin of his electrical researches, which were subsequently published in his History of Electricity. This work greatly enhanced his fame, and gained for him an F.R.S., and the degree of LL.D. of Edinburgh University.

In 1767 Priestley left Warrington for Leeds, having been appointed minister of Millhill Chapel. In the Yorkshire town he commenced his chemical investigations, at the same time freely expressing his opinions on theology and metaphysics. Living near a brewery, he made experiments on the "fixed air" (carbon dioxide) of Black, and this led to investigations with "airs," or, as we should say, with gases. Priestley's chemical work was essentially in the domain of pneumatic chemistry. In 1772 he published a work on the method of impregnating water with fixed air—hence the birth of the mineral water industry. In the same year he presented a paper to the Royal Society entitled "Observations on Different Kinds of Air," which secured for him the Copley medal.

Having published a method of preventing scurvy, a proposition was made to Priestley that he should accompany Captain Cook in his second voyage to the South Seas. It was accepted, but not confirmed by the Board of Longitude. On the Board were many clergymen, and no doubt they were against Priestley's "religious principles."

In 1772 Priestley was appointed librarian to Lord Shelburne (afterwards Marquis of Lansdowne) at a salary of £250 a year, a house, and an annuity for life. He remained in the service of his lordship for seven years, living sometimes at Calne, and sometimes in London; and during this time he travelled in Germany and Holland, and in 1774 visited Paris, where he made the acquaintance of Lavoisier and other French savants. Why Priestley severed his connection with Lord Shelburne will never be exactly known, but his lordship treated him with the greatest kindness and consideration.

The publication of Priestley's Disquisitions relating to Matter and Spirit in 1777 brought him much odium theologicum, because it was a powerful exposition of materialism. Critics denounced him as an atheist, as an infidel, and other epithets were hurled at him from all parts of the country. It is probable that this denunciation was the cause of Priestley leaving the service of Lord Shelburne. His lordship, however, punctually paid the annuity of £150 a year which he had promised.

After leaving Lord Shelburne in 1779, Priestley visited London, but ultimately settled in Birmingham, having been appointed Unitarian minister to the Old Meeting Chapel (no longer in existence—New Street Station is on the site of Priestley's chapel). At this time he was friendly with Watt, Wedgwood, Boulton, Darwin, the Galtons, and others. Mrs Schimmelpenninck (née Galton) described Priestley as "a man of admirable simplicity, gentleness, and kindness of heart, united with great acuteness of intellect."

He resigned his charge in 1791, when his friends raised a sum annually for him, in order that he might be able to prosecute his investigations without the necessity of teaching. During this period, although he published a vast amount of chemical work, he could not leave theology, metaphysics, and politics alone. Sympathizing with the Americans in the War of Independence, and afterwards with the French in the Revolution, and his writings and speeches against the Established Church, brought him into controversy with the clergy of Birmingham. The controversy was bitter and long. Priestley was regarded as a dangerous character, an enemy to Church and State, and even Burke (1729-97) spoke against him in the House of Commons. Such was the feeling against dissenters—"fomenters of sedition"; but that is far from being the end of the story. The storming of the Bastille was almost as much applauded in London as in Paris, but the burning, the plundering, the executions in the name of justice, by which the politest nation in the world seemed to be degrading itself by acts which would disgrace a horde of savages, soon alienated most Englishmen. The times were troublous ones, still the city of Paris maintained its round of gaiety undisturbed; for "Paris is a volcano with two craters, one of passion and one of pleasure." On the still fresh ruins of the grim Bastille, now demolished for ever, Frenchmen danced with glee. It was one way of showing that the ancient rêgime had for ever disappeared. The Revolution was accomplished amid song and dance—the "Marseillaise" and the "Carmagnole." In this country party passion ran high. Burke published his Reflections on the Revolution in France, in which he denounced in eloquent and impressive language the terrible doings in France. This book called forth many rejoinders, of which Tom Paine's Rights of Man, and Mackintosh's Vindiciæ Gallicæ are the most remarkable. We can see the reason why Burke spoke against Priestley; his opinions were considered heretical and violent. Priestley had written with great fierceness against the episcopacy and ecclesiastical governments generally, and regarded all civil establishments of Christianity, and all connections between Church and State, as abuses and barriers to the propagation of truth. Consequently, he and his friends rejoiced at the advent of the French Revolution; when abuses of every description would be swept away, and the beginning of happy days for the human race. Priestley was at loggerheads with the Birmingham clergy on account of his opinions on theological matters, and with laymen he made enemies owing to his contemptuous allusions to King George III. and the royal family.

About this time Priestley was elected one of the eight foreign associates of the Académie des Sciences de Paris (the blue ribbon of science), and was, therefore, brought into correspondence with many savants who supported the Revolution in its early stages, and this fact only helped to add fuel to the fire that was even then smouldering.

Priestley was sorely hurt by the publication of Burke's book, and replied by publishing his Letters to Mr Burke, in which he maintained that the old aristocratic system, embracing both civil and ecclesiastical matters, was beginning to totter at its foundation—due to the salutary effect of the French Revolution. This exasperated the men of Birmingham, who were loyal to Church and King. They became furious, and all sorts of terms of vituperation were hurled at Priestley: he was " chaos in miniature, not worth God's notice." A verse to the national anthem is well worth quoting here:—

Gunpowder Priestley would
Deluge the throne with blood,
And lay the great and good
Low in the dust.

Thursday, 14th July 1791, the second anniversary of the taking of the Bastille, was celebrated by eighty of Priestley's friends in Birmingham by a dinner at an hotel in Temple Row, and in spite of the plainest symptoms of an intended riot. "Church and King," "Down with Dissenters," were heard everywhere. These cries exasperated the mob to such an extent that they smashed the windows of the hotel, and burnt the chapels and houses of the dissenters. The full hatred of the mob was directed against Priestley, who, with his wife and family, narrowly escaped with their lives, leaving his valuable library, philosophical instruments, furniture, and the manuscripts of works which had cost him years of labour a prey to the flames.

Several persons were arrested for this disgraceful riot, and three were executed.

The riots may be looked at from two standpoints: either as a struggle to preserve the privileges of the Church of England, or as a rebellion of an excited contingent of the population enraged by the party spirit of the times. Meetings had been organised which were declared by some to be dangerous to the peace of the country. The spirit of democracy had spread in England, and those in favour of the French Revolution entertained the idea of over-turning the Constitution of the Empire. Inflammatory pamphlets had been issued and circulated in Great Britain in favour of upholding the doctrine of the Revolution.

Priestley's New and Old Meeting Houses were burnt to the ground. News of this was conveyed to Priestley at Fair Hill, who thought it so improbable that he should be molested that he hardly credited the story. He was at last prevailed upon to leave the house, but having no apprehension with regard to his property, neither collected any of his manuscripts nor took anything with him. Detachments of the rioters now proceeded to Priestley's residence; they attacked the building with great violence, destroying pictures, furniture, etc., including a valuable library. It was hoped the laboratory would escape the attention of the crowd, as it was situated at some distance from the house, but this was not so; it was broken into, much valuable apparatus being ruined, and the building destroyed.

On the following morning various parties of the rebels entered the town and paraded the streets armed with bludgeons, vociferating "Church and King," words which the peaceful inhabitants chalked on the doors and shutters of their houses to aid security. The Earl of Aylesford, who had done his best to quell the disturbance, went to the ruins of Priestley's house and addressed the mob. He brought them into the town and tried to persuade them to disperse, but both his efforts and those of the magistrates were useless to stop the revolt.

During the day several residences were attacked and burnt, and in consequence additional constables were sworn in; but these were of little avail against the large numbers of the disturbers of the peace. The spirit of rebellion continued to spread, much to the terror and distress of the whole town. While the work of destruction was going on, cries such as "Long live the King and the Constitution in Church and State," "Down with all abettors of the French Revolution," could be continually heard. The devastation went on until Sunday afternoon, when information was received that troops were approaching Birmingham. About ten o'clock three troops of the 15th Regiment of Dragoons from Nottingham, attended by magistrates, entered the town and halted at the Swan Inn. The arrival of the military reassured the inhabitants and eventually restored order.

In the meantime Priestley, on leaving his home at Fair Hill, only went to neighbouring houses a little distance, but hearing that the rioters were advancing, went to Heath Forge, five miles from Dudley. Here he considered he was safe, but news reached him that he was pursued; in consequence he proceeded to Kidderminster; here, again, he proved to be too near his enemies, so Worcester was his next halting-place, and from thence he proceeded to London, which he reached on 18th July 1791.

To the man of science the destruction of his library was the greatest grief. The manuscripts which he most deplored were the following:—

1. Diaries from 1752.
2. Several commonplace books containing notes.
3. Register of philosophical experiments and hints for new ones.
4. Sermons, prayers, etc.
5. Notes and a paraphrase on the whole of the New Testament excepting Revelation.
6. A new translation of the Psalms.
7. Memoirs of his own life, to be published after his death.
8. Illustration of Hartley's doctrine of Association of Ideas, and further observations on the human mind.

Concerning the Priestley riots Gillray[2]produced an etching in which Priestley was grossly lampooned. The sympathy of Priestley and his friends for the French Revolutionists became their greatest crime in the eyes of their enemies, and the dinner on 14th July was ostensibly made the occasion of the anti-Jacobin outbreak. "By far the greatest crime of all which Dr Priestley and the 'Socinians' had committed," says Mr Dent, "was that of sympathizing with the lovers of freedom who had just succeeded in overturning the throne of Louis XVI. in France. This sympathy Gillray, the caricaturist, turned to account in a bitterly hostile and infamously libellous print, representing the leading Jacobins of the day drinking 'a Birmingham toast' proposed by Dr Priestley. 'The—Head here!' i.e. in a Communion salver, which he holds aloft, himself drinking the toast from a chalice. The Jacobins are represented as early welcoming this toast. Sheridan pouring out a fresh glass of sherry, of which he has already emptied several bottles, is made to say, 'I'll pledge you that toast.' … Sir Cecil Wray, frugally drinking small beer, exclaims, 'O heavens! why, I would empty a Chelsea pensioners small-beer barrel in such a cause.' Fox, as chairman, with punch-bowl before him, cries, 'My soul and body, both upon the toast.' Horne Tooke, who sits next him, drinking gin, says, 'I have not drunk so glorious a toast since I was parson of Brentford'; while in the corner opposite Dr Priestley, his co-religionist and bosom friend Dr Theophilus Lindsey cries 'Amen! Amen!' as he drinks the toast in brandy. In the background are several cadaverous-looking pietists, supposed to represent Dr Priestley's congregation. The print is exceedingly vigorous in design and execution, but as full of venom as an etching from Gillray's needle could possibly be."

Seeing this etching, reminds one of many of the venomous, satirical, and revolting paintings of Antoine Wiertz in the Musée Wiertz in the Rue Vautier, Brussels (e.g. "Napoléon dans l'Enfer," "L'Enfant Brule," "L'Inhumation Précipitée," etc.).

The reference to "The—Head" arises from the fact that in the centre of the table at that ever-memorable dinner of 14th July 1791, was a painting of the King, and on both sides a marble obelisk, the one representing French liberty breaking the fetters of despotism, and the other English liberty in its present enjoyment.

Such were the feelings against Priestley by his own countrymen, and as Carlyle says in his French Revolution—"did not iron Birmingham, shouting 'Church and King'—itself knew not why—burst out into rage, drunkenness and fire, and your Priestleys and the like dining there on the Bastille day get the maddest singeing—scandalous to consider!" The French, more tolerant, naturalized Priestley and other foreign friends of humanity; and in September 1792 he was elected a member of the Assemblée Nationale by the Orne Department in Normandy. He wisely declined the honour, as the guillotine was no respecter of persons—not even "the friends of humanity."

Priestley came to London, and although elected minister of a congregation at Hackney, he felt the insecurity of his position. He was boycotted by his scientific friends, by tradespeople, and his own servants feared to live under the same roof. Finally, he emigrated to the United States of America, where he landed in 1794. He settled at Northumberland, a quiet town on the banks of the Susquehanna in Pennsylvania; and with all his suffering and injustice, he left his native land "without resentment or ill-will," knowing too well that the time would come when Englishmen would do him justice. He died on 6th February 1804, and lies buried near his new home.

If Priestley could have seen that his friend Lavoisier and Bailly (the astronomer) would be sent to the guillotine, he would have modified his views of the liberty, fraternity, and humanity of the French Revolutionists. Priestley received £2000 to atone for mob violence—the Birmingham revolution of three days; for poor Lavoisier and Bailly the only compensation is the sorrow of all intellectual men and women.

In the end, Priestley's political and theological heterodoxy helped to make England what it is. He was scorned in England, honoured in France, and found peace in America. Posthumous honours have been instituted to his memory. A statue at Birmingham, representing him in the act of decomposing red precipitate, was erected in front of the Town Hall; another at Leeds; a chemical scholarship bearing his name is awarded by the Birmingham University; and a beautiful fresco on the walls of the Birmingham Town Hall represents him entering a coach in order to place himself and family out of reach of the infuriated mob, egged on to do their nefarious work of destruction by political and religious foes.

Some idea may be formed of the vastness of Priestley's work by mentioning the titles of some of his books: Observations on Air; The First Principles of Civil Government; Disquisitions relating to Matter and Spirit; On Oratory and Criticism; On the History and Present State of Discoveries Relating to Vision, Light, and Colours; The General History of the Christian Church; the Doctrine of Philosophical Necessity; The Harmony of the Evangelists in Greek; The Rudiments of English Grammar; Experiments on Different Kinds of Air; An Introduction to the Theory and Practice of Perspective; A History of Electricity; The Doctrine of Phlogiston Established (one of his last publications), etc.

With all his faults, sympathies with American and French Revolutionists, heterodoxy, prejudices against antiphlogistians, he was a manly man, devoid of mean acts (which cannot be said of many of his foes), a great worker, brilliant experimentalist, a learned writer, a kind and genial friend, and a great controversialist in the domains of theology, metaphysics, politics, and natural philosophy. He was the father of pneumatic chemistry, but more anon. He never could free himself of the false doctrine of phlogiston; but in the words of Voltaire: "oublions les rêves des grandes hommes et souvenons nous des vérités qu'ils nous ont enseignées."

The truths which Priestley contributed to chemistry have now to be described; but, before doing so, it may be remarked en passant that he lived in a great age, an age remarkable for great names, which recall to the mind great ideas: Swift, Voltaire, Rousseau, Johnson, Hume, Goldsmith, Gibbon, Goethe, Schiller, Burns Chatterton, Franklin, Mirabeau, Pitt, Talleyrand, Napoleon, Nelson, Washington, and a host of others more or less great lived in the same age as Priestley; and what pictures these names conjure to the thinking reader!

Although many of his works will perish as time rolls on, his chemical discoveries will remain for ever.

Joseph Priestley's name will live as the discoverer of oxygen. It is curious that Priestley himself was so wedded to the doctrine of Stahl—the phlogistic theory—which supposed the existence of a subtle principle, phlogiston, that he did not appreciate the vast importance of his own discovery, and his attitude led Cuvier when pronouncing his éloge (at the time of his death) before the Académie des Sciences, to describe him as "le père de la chimie modèrne qui ne voulait pas reconnaitre sa fille."

On 1st August 1774 Priestley discovered oxygen (dephlogisticated air) from red precipitate (mercuric oxide), which gave chemists a new gas of wonderful properties, only to involve chemical processes into great confusion and deeper mystery. The fire air (oxygen) of Scheele, recorded in his Chemische Abhandlung von der Luft und dem Feuer, brought some light into the chemistry of air; but their discoveries were enveloped in darkness—the jargon of the phlogistic doctrine—according to which metals lose something (phlogiston) when calcinated (dephlogisticated). The true explanation of combustion (oxidation) and deoxidation was left for Lavoisier to interpret. Priestley was the workman, Lavoisier the philosopher. The discovery placed in the latter's hand became perfect and in harmony with the universal laws of nature; and a revolution in chemistry was accomplished exactly corresponding to that effected by Copernicus in astronomy nearly four hundred years ago.

Priestley seemed "to look on all 'airs' (gases) as easily changeable one into the other," a kind of transmutation. During his lifetime he examined the burning of candles, the respiration of animals upon air, the action of living plants on the air, and invented the pneumatic trough (and used both water and mercury therein). He prepared nitrous air (nitric oxide) dephlogisticated nitrous air (nitrous oxide of the dentist), and carbon monoxide. He used mercury in many of his pneumatic researches, collected alkaline air (ammonia gas), vitriolic air (SO2 gas), marine acid air (HCl gas), and fluor acid air (SiF4). In 1772 he proved that common air was a mixture. By burning charcoal in it he obtained fixed air (CO2), which on absorption left a residual (phlogisticated) air incapable of supporting either respiration or combustion. Again, Priestley could not see the importance of his discovery, namely, that air is a mixture of gases.

In 1774 Priestley discovered ammonia gas too, which he gave the name of alkaline air; and proved that mixed gases do not separate on standing, but remain uniformly distributed throughout the mass (diffusion of gases).

By passing electric sparks through ammonia gas, he observed that an inflammable gas was formed; and that phlogisticated air (the mephitic air of Rutherford and the nitrogen of Chaptal and later chemists) was evolved on heating ammonia with the calx of lead (lead oxide, PbO). Although a brilliant experimentalist, "with rare quickness and perceptive powers," Priestley had not the genius of the philosopher; "he passed too rapidly from subject to subject even to notice the great truths which lay under the surface"; he left for others to interpret the results of his discoveries. The phlogistic doctrine was always in the way of this remarkable man; he never could free himself of its encumbrances, its wordy phraseology, and its false theory. He was blinded by Stahl's doctrine even to the end of his days. He only "looked at the results of his experiments through the fogs of his prejudices"; but his discoveries proved in the hands of Lavoisier the deathblow to phlogistic ideas. The conflict with error was ended and truth prevailed. His work represents the death of an old science and the birth of a new one. Such was the life of Joseph Priestley, and "le monde comme il va!"


  1. Born 1706; died 1790.
  2. James Gillray (1757-1815) went mad in 1811 chiefly through intemperance, and only had a few subsequent intervals of sanity.