impressive and conciliatory, the victorious revolt against scientific dogmatism then in progress. Hence his unrivalled popularity and privileged position, which even the most rancorous felt compelled to respect. No stranger of note visited England without seeking an interview, which he regarded it as an obligation of Christian charity to grant. Three successive kings of England conversed familiarly with him, and he was considered to have inherited, nay outshone, the fame of the great Verulam. 'The excellent Mr. Boyle,' Hughes wrote in the 'Spectator' (No. 554),' was the person who seems to have been designed by nature to succeed to the labours and inquiries of that extraordinary genius. By innumerable experiments he, in a great measure, filled up those plans and outlines of science which his predecessor had sketched out.' Addison styled him (No. 531) 'an honour to his country, and a more diligent as well as successful inquirer into the works of nature than any other one nation has ever produced.' 'To him,' Boerhaave wrote, 'we owe the secrets of fire, air, water, animals, vegetables, fossils; so that from his works may be deduced the whole system of natural knowledge ' (Methodus discendi Artem Medicam, p. 152).
It must be admitted that Boyle's achievements are scarcely commensurate to praises of which these are but a sample. His name is identified with no great discovery; he pursued no subject far beyond the merely illustrative stage; his performance supplied a general introduction to modern science rather than entered into the body of the work. But such an introduction was indispensable, and was admirably executed. It implied an 'advance all along the line.' Subjects of inquiry were suggested, stripped of manifold obscurities, and set in approximately true mutual relations. Above all, the fruitfulness of the experimental method was vividly exhibited, and its use rendered easy and familiar. Boyle was the true precursor of the modern chemist. Besides clearing away a jungle of perplexed notions, he collected a number of highly suggestive facts and observations. He was the first to distinguish definitely a mixture from a compound; with him originated the definition of an 'element' as a hitherto undecomposed constituent of a compound; he introduced the use of vegetable colour-tests of acidity and alkalinity. From a bare hint as to the method of preparing phosphorus (discovered by Brandt in 1669) he arrived at it independently, communicated it 14 Oct. 1680 in a sealed packet to the Royal Society, and published it for the first time in 1682 (Works iv. 37). In a tract printed the same year he accurately described the qualities of the new substance under the title of the 'Icy Noctiluca.' He, moreover, actually prepared hydrogen, and collected it in a receiver placed over water, but failed to .distinguish it from what he called 'air generated de novo' (ibid. i. 35).
In physics, besides the great merit of having rendered the air-pump available for experiment and discovered the law of gaseous elasticity, he invented a compressed-air pump, and directed the construction of the first hermetically sealed thermometers made in England. He sought to measure the expansive force of freezing water, first used freezing mixtures, observed the effects of atmospheric pressure on ebullition, added considerably to the store of facts collected about electricity and magnetism, determined the specific gravities and refractive powers of various substances, and made a notable attempt to weigh light. He further ascertained the unvarying high temperature of human blood, and performed a variety of curious experiments on respiration. He aimed at being the disciple only of nature. Down to 1657 he purposely refrained from 'seriously or orderly' reading the works of Gassendi, Descartes, or 'so much as Sir F. Bacon's "Novum Organum," in order not to be possessed with any theory or principles till he had found what things themselves should induce him to think' (ibid. 194). And, although he professed a special reverence for Descartes, as the true author of the 'tenets of mechanical philosophy' (ibid. iv. 521), we find, nine years later, that he had not yet carried out his intention of thoroughly studying his writings (ibid. ii. 458). Yet he was no true Cartesian; the whole course of his scientific efforts bore the broad Baconian stamp; nor was the general voice widely in error which declared him to have (at least in part) executed what Verulam designed.
The style of his writings, which had the character rather of occasional essays than of systematic treatises, is free from rhetorical affectations; it is lucid, fluent, but intolerably prolix, its not rare felicities of phrase being, as it were, smothered in verbosity. He endeavoured to remedy this defect by processes of compulsory concentration. Boulton's first epitome of his writings appeared in 1699-1700 (London, 3 vols. 8vo); a second, of his theological works, in 1715 (3 vols. 8vo); and Dr. Peter Shaw's abridgment of. his philosophical works in 1725 (3 vols. 8vo). The first complete edition of his writings was published by Birch in 1744 in five folio volumes (2nd edition in 6 vols. 4to, London, 1772). It included his posthumous remains
