PRIESTLEY, Joseph, scientist, born in Field-head, near Leeds, Yorkshire, England, 24 March, 1733; died in Northumberland, Pennsylvania, 6 February, 1804. He was the eldest son of a cloth-dresser, and his mother dying when the boy was six years old, he was adopted by his aunt, Mrs. Keighley. The youth was sent to a free gram-mar-school, and at the age of sixteen had made considerable progress in the ancient languages. He had determined to become a clergyman, and in 1752-'5 he was at the dissenting academy at Daventry, in Northamptonshire, where he wrote some of his earliest tracts On attempting to enter the ministry he was rejected on account of his views on original sin, the atonement, and eternal damnation, which he maintained openly. In 1755 he became an assistant in an obscure meeting-house at Needham market in Suffolk, but he failed to become popular. Three years later he went to Nantwich, in Cheshire, where he taught twelve hours a day. At this time he wrote his first book, "Rudiments of English Grammar" (London, 1761), and his "Course of Lectures on the Theory of Language and Universal Grammar" (Warrington, 1762). In 1761 he removed to Warrington, in Lancashire, where the dissenters had established an academy, and for six years he was tutor there in the languages and belles-lettres. He preached continually during his residence in that place, and was ordained there. During one of his visits to London he met Benjamin Franklin, and through his assistance undertook the preparation of his "History and Present State of Electricity, with Original Experiments" (London, 1767). He received the degree of LL. D. from the University of Edinburgh, and was elected to the Royal society in 1766. In 1767 he removed to Leeds, where he was given charge of the Mill Hill chapel. He devoted himself closely to the study of theology, and began his investigations on gases, also publishing a fragmentary work on the "History and Present State of Discoveries relating to Vision, Light, and Colors" (2 vols., London, 1772). In 1769 he came into conflict with Sir William Blackstone, author of the "Commentaries," pointing out inaccurate statements of historical facts in his work. Blackstone promised to cancel the offensive paragraphs in the future editions of his work, and the controversy came to an amicable conclusion. From 1773 till 1780 he was librarian or literary companion to the Earl of Shelburne, with whom he travelled on the continent, and spent some time in Paris; on his return he had much leisure for scientific research, and was active in prosecuting his experiments. During these years he made his great discoveries in chemistry, and renewed his investigations on gases. Priestley was unacquainted with chemistry ; he had no apparatus, and knew nothing of chemical experimenting, but these adverse conditions may have been serviceable as he entered upon a new field where apparatus had to be invented, and the arrangements that he devised for the manipulation of gases are unsurpassed in simplicity and have been used ever since. The first of these discoveries was that of nitric oxide in 1772, the properties of which he ascertained and applied to the analysis of air. In 1774, by heating the red oxide of mercury, he made his discovery of oxygen, to which he gave the name of dephlogiscated air. He also showed its power of supporting combustion better, and animal life longer, than the same volume of common air. By means of mercury which he used with the pneumatic trough to collect, gases that are soluble in water, he further made known hydrochloric acid and ammonia in 1774, and sulphur dioxide and silicon tetrafluoride in 1775, and introduced easy methods for their preparation, describing with exactness the most remarkable properties of each. He likewise pointed out the existence of carburetted hydrogen gas. Priestley discovered nitrous oxide in 1776, and, after he came to the United States, carbon monoxide in 1779. To him we owe the knowledge of the fact that an acid is formed when electric sparks are made to pass for some time through a given bulk of common air, which afterward led to Cavendish's discovery of the composition of nitric acid. These facts are described in his "Experiments and Observation Relating to Natural Philosophy, with a Continuation of the Observations on Air" (3 vols., London, 1779-'86). Meanwhile he wrote numerous theological works, and it has been said of Priestley that "he was fond of controversy, yet he never sought it, and if he participated in it, it was generally because it was thrust upon him, and he became the defendant rather than the assailant." In 1780 he took up his residence in Birmingham, where he had charge of an independent congregation. Ills collection of apparatus had increased, and his income was now so good that he could prosecute his researches with freedom. In 17!)0 he enraged the people by his "Familiar Letters to the Inhabitants of Birmingham" (Birmingham, 1790), and these were soon followed by "Letters to Rt. Iton. E. Burke, occasioned by his Reflections on the Revolution in France" (1791). He now became the recognized champion of liberal thought, which made him the subject of severe condemnation at home. This feeling culminated on 14 July, 1791, the anniversary of the French revolution, in a riot in Birmingham, during which his meetinghouse and his dwelling-house were burned, and his library and apparatus were destroyed, and many manuscripts, the fruits of years of industry, perished in the flames. Priestley escaped to London. When the popular excitement had somewhat ceased in Birmingham he sought compensation in tile courts for the destruction of his property, and presented a claim for £3,628, but, during a trial of nine years, it was cut down to £2,502. He sailed from London on 7 April, 1794, and on 4 June landed in New York, where he was received by delegations from scientific societies and invited to give a course of lectures on experimental philosophy, for which a hundred subscriptions at $10 each were soon obtained. But he refused, and proceeded at once to Philadelphia, where he received a complimentary address from the American philosophical society. He was offered the professorship of chemistry in the University of Pennsylvania with a good salary, but declined the appointment, preferring to choose his own occupations in retirement. His sons had previously settled in Northumberland, Pennsylvania, whither he followed, making his home in the midst of a garden overlooking one of the finest views of the Susquehanna. A laboratory was built for him, which was finished in 1797, and he was able to arrange his books and renew his experiments with every possible facility. Thomas Jefferson consulted him in regard to the founding of the University of Virginia, and he was offered the presidency of the University of North Carolina. In the spring of 1796 he delivered a series of "Discourses relating to the Evidences of Revealed Religion" (Philadelphia, 1796), which were attended by crowded audiences, including many members of congress and the executive of-fleers of the government, and in 1797 he delivered second series, which were less favorably received. The first of these, when published, was dedicated to John Adams, who was then his hearer and admirer, but later, when Adams (q. v.) became president, Priestley opposed the administration, and it was intimated that the "alien law" was directed against him. His time was chiefly spent in literary work, and he wrote the continuation of his "General History of the Christian Church to the Fall of the Western Empire" (4 vols., Northumberland, 1802-'3), which he dedicated to Thomas Jefferson" also "Answer to Mr. Paine's Age of Reason" (1795) ; "Comparison of the Institutions of Moses with those of the Hindoos and other Nations" (1799)" "Notes on all the Books of Scripture" (1803)' and "The Doctrines of Heathen Philosophy compared with those of Revelation" (1804). There are many memoirs of his life, of which the most important are John Corry's "Life of J. Priestley" (Birmingham, 1805) and "Memoirs of Dr. Joseph Priestley to the Year 1795. written by himself" with a Continuation to the Time of his Decease, by his Son, Joseph Priest, lee" (2 vols., London, 1806-'7). His "Theological and Miscellaneous Works" (excluding the scientific) were collected by John T. Rutt and published in twenty-six volumes (Hackney, 1817-'32). His old congregation in Birmingham erected a monument to his memory in their place of worship after his death, and a marble statue was placed in 1.860 in the corridor of the museum at Oxford. The centennial of the discovery of oxygen was celebrated on 1 August, 1874, by the unveiling of a statue to his memory in Birmingham, an ad-press in Paris, and in this country by a gathering of chemists at his grave in Northumberland, Pennsylvania, where appropriate exercises were held, including addresses by T. Sterry Hunt, Benjamin Silliman, and other scientists. Dr. H. Carrington Bolton, who delivered an address on Priestley before the New York genealogical and biographical society in April, 1888, has in preparation "The Scientific Correspondence of the Reverend Joseph Priestley."