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 DALTON of Virginia. Transferred to the array of the Potomac, he followed it through the campaign of 1864, having charge of all the wounded, and establishing and moving the hospitals as circumstances required. The number of pa- tients thus under his charge from May, 1864, to March, 1865, was more than 100,000. From the latter date he was medical director of the 9th army corps until the close of the war, when " for faithful and meritorious services " he received the rank of colonel of volunteers by brevet. From March, 1866, to January, 1869, he was sanitary superintendent of the New York board of health. He visited Cal- ifornia three years later, for the improve- ment of his health, and died there. His pub- lished works are : a treatise on " The Disorder known as Bronzed Skin, or Disease of the Su- pra-Renal Capsules " (" New York Journal of Medicine," May, I860); " Reports of the Sani- tary Superintendent of the Metropolitan Board of Health " for 1866, 1867, and 1868; and an article on " The Metropolitan Board of Health " ("North American Review," April, 1868). DALTOff, John, an English chemist, author of the atomic theory, and of that of the constitu- tion of mixed gases, born at Eaglesfield, near Cockermouth, in Cumberland, Sept. 5, 1766, died in Manchester, July 27, 1844. With his parents, he belonged to the society of Friends. He received his first instruction at the school of his native village, and in 1781 became usher in a school at Kendal, where he remained till 1793, when he was appointed professor of mathematics and natural philosophy in the New college at Manchester, which was re- moved to York in 1799. He continued his lessons in private schools for years, occasionally giving lectures on the physical and experimen- tal sciences in neighboring towns and cities. In 1788 he began a series of important mete- orological observations, and in 1793 published his first separate work, entitled "Meteorolo- gical Observations and Essays." This was one of his favorite pursuits, and he continued to collect and record meteorological observations until his death. In 1794 he gave an account of a singular defect in his own vision which rendered him incapable of distinguishing cer- tain colors; green, red, purple, and blue, all appearing alike to him. He supposed this pe- culiarity to be due to the color of the retina or of the fluids of the eye; but after his death no abnormal coloration was discovered on dis- section. This defect of vision, which is not very uncommon, has sometimes been called Daltonism since the publication of his paper. (See COLOR-BLINDNESS.) He wrote numerous articles for the "Gentleman's and Lady's Diary," the "Memoirs of the Manchester So- ciety," "Nicholson's Journal," the "Philo- sophical Magazine," and the " Transactions of the Royal Society of London." In 1801 he published " Elements of English Grammar." In 1802 he wrote six dissertations for the "Memoirs of the Manchester Society," in one of which he unfolded his celebrated theory of the " Constitution of Mixed Gases." The lead- ing feature of this theory is that gases which do not form new chemical compounds act on each other as a vacuum, diffusing themselves among each other by their own elasticity. The greater part of Dalton's experiments were made to ascertain the influence of heat in the pro- duction of physical and chemical phenomena ; and much of the progress of modern science in this department is due to his researches. Other subjects treated in these papers were "The Force of Vapor of Water and other Fluids at Different Temperatures in the Torri- cellian Vacuum, and other Atmospheric Press- ure," and "The Theory of Evaporation and the Expansion of Gases by Heat." These writings display profound reasoning based on accurate observations, and have rendered great service to pneumatic chemistry and modern investiga- tions on the specific gravity of gases. His celebrity, however, rests mainly on his atomic theory, which he began to work out in 1803, and explained in lectures in 1804. This the- ory was fully propounded in his "New Sys- tem of Chemical Philosophy," the first vol- ume of which appeared in 1807, and the second in 1810, followed by a third in 1827. (See ATOMIC THEORY.) In his papers on subjects connected with meteorology, he has left valu- able remarks on evaporation, rain, the aurora borealis, winds, and dew. His observations on the latter contain the principles of Dr. Wells's theory of dew, and of Daniell's hygrometer. In 1821 he was elected fellow of the royal so- ciety, and in 1826 received a gold medal from that society for discoveries in science. In 1822 he visited France, where he was received with much distinction. In the reign of William IV. the English government gave him a pension of 150 a year, which was subsequently in- creased to 300. DALTON, John Call, an American physiologist, born at Chelmsford, Mass., Feb. 2, 1825. He graduated in arts at Harvard college in 1844, and in medicine in 1847. He first attracted attention as an original physiological writer by an essay on the corpus luteum, which received the annual prize offered by the American medi- cal association in 1851, and he was appointed professor of physiology in the medical depart- ment of the university of Buffalo, where he in- augurated in this country the teaching of phy- siology with illustrations by vivisection. He re- signed this professorship in 1854, and occupied the chair of physiology in the Vermont medi- cal college from 1854 to 1857, and in the Long Island College hospital from 1859 to 1861. In 1854-'5 he gave a course of lectures on physi- ology in the college of physicians and surgeons in New York, in place of Prof, Alonzo Clark. In 1855 he was appointed to that chair, which he has since filled. His contributions to the literature of physiology have been numerous since 1851. He has published several impor tant articles in the "American Journal of the