WOLLASTON, WILLIAM HYDE, M.D., a distinguished physicist, was the second son of the rev. Francis Wollaston, of Chiselhurst, in Kent, and was born Aug. 6, 1766. After the usual preliminary education, lie was entered of Caius college, Cambridge, where he studied for the medical profession, and took the degree of M.D. in 1793, in which year, also, he was elected a fellow of the royal socie•y. After practicing as a physician at Bury St. Edmunds, he removed to London; but being beaten by Dr. Pem berton in a competition for the post of physician to St. George's hospital, he determined thenceforth never to write a prescription, " were it for his own father," but to devote himself wholly to scientific investigation. This sudden resolution proved ultimately most beneficial, leading him rapidly to wealth and fame; for unlike many eminent investigators of nature's laws and phenomena, Wollaston combined "the genius of the philosopher with the skill of the artist," and succeeded in making industrial application of several of his important discoveries. His researches were prosecuted over a wide field, but were pre-eminently fruitful in the sciences of chemistry and optics. To the facts of the former science he added the discovery of new compounds connected with the production of gouty and urinary concretions, such as phosphate of lime, ammonio magnesian phosphate (a mixture of these two forming the "fusible " calculus), oxalate of lime, and cystic oxide; also the discovery in the ore of platinum of two new metals, palladium (1804) and rhodium (1805). By his ingenious discovery of a mode for mak
ing platinum malleable, lie is said to have gained £30,000, and his mode of hardening steel, and some other discoveries of a practically useful nature, were also very lucrative. His contributions to optics were the celebrated " goniometer " (q.v.), a most valuable gift to mineralogists; an apparatus for ascertaining the refractive power of solid bodies; the "camera lucida " (q.v.); the discovery of invisible rays outside the violet baud of the spectrum; and an immensity of valuable and interesting observations on single and double refraction. He did much to establish the theory of definite proportions. To other sciences his contributions were also of importance, for he was the first to demon strate the identity of galvanism and common electricity, and explain the cause of the difference in the phenomena exhibited by each, etc. Wollaston was elected secretary of the royal society, Nov. 80, 1806. He died of effusion of blood on the brain on Dec. 22 of the same year. His most important memoirs, 38 in number, will be found in the Philosophical Transactions