Wilkinson, an ironmaster in Wales, by whom he had several children. His literary career may be said to have commenced here, and having once begun to publish, his appeals to the press were incessant and on almost every subject. The universality and originality of his pursuits may be judged from his delivering at Warrington a course of lectures on anatomy, while his published works during the next seven or eight years comprise:--'The Theory of Language and Universal Grammar,' 1762; 'On Oratory and Criticism,' 1777; 'On History and General Policy,' 1788; 'On the Laws and Constitution of England,' 1772; 'On Education,' 1765; 'Chart of Biography,' 1765; 'Chart of History,' 1769. During the same period appeared, in 1767, his work entitled, 'A History of Electricity,' &c., which was so well received that it went through five editions. This was followed in 1772 by a 'History of Vision.' In 1767, on account of a dispute with the Warrington trustees, Priestly removed to Leeds, where he became minister of the Mill-Hill Chapel, and wrote many controversial books and pamphlets. In after times he wrote--'Letters to a Philosophical Institution;' 'An Answer to Gibbon;' 'Disquisitions on Matter and Spirit;' 'Corruptions of Christianity;' 'Early Opinions on Christ;' 'Familiar Letters to the Inhabitants of Birmingham;' 'Two different Histories of the Christian Church;' 'On Education;' 'Comparison of Heathen and Christian Philosophy;' 'Doctrine of Necessity;' 'On the Roman Catholic Claims;' 'On the French Revolution;' 'On the American War;' besides twenty volumes of tracts in favour of Dissenters and their Rights. His general works fill twenty-five volumes, of which only five or six are on scientific subjects; his publications being in all 141, of which only seventeen are scientific. When residing at Leeds Priestly's house immediately adjoined a brewery, which led him to make experiments upon the fixed air copiously produced during the process of fermentation. These experiments resulted in his discovering the important fact that atmospheric air, after having been corrupted by the respiration of animals, and by the burning of inflammable bodies, is restored to salubrity by the vegetation of plants; and that, if the air is exposed to a mixture of sulphur and iron-filings, its bulk is diminished between a fourth and a fifth, and the residue is both lighter than common air and unfit to support life; this residue he termed 'phlogistic air,' afterwards called azotic or nitrogen gas.[53] For these experiments the Copley medal was awarded to him in 1773 by the Royal Society. The following year to this, from experiments with nimium or red lead, Priestly made his great and important discovery of oxygen gas. This was followed by his discovering the gases of muriatic, sulphuric, and fluoric acids, ammonial gas and nitrous oxide gas. He also discovered the combination which nitrous gas forms suddenly with oxygen; diminishing the volume of both in proportion to