Augustus Allen Hayes, an American chemist, born in Windsor, Vt., Feb. 28, 1806. He graduated at the military academy in Norwich, Vt., in 1823, and then began the study of chemistry as a profession. In 1825 a laborious research undertaken by him, for the purpose of more accurately determining the proximate composition of various American medicinal plants, was rewarded, among other results, by the discovery of the organic alkaloid sangui-naria, a compound remarkable for the brilliant colors of its salts, although itself colorless, or nearly so. In 1827, while assistant professor of chemistry in the New Hampshire medical college, he investigated the compounds of chromium; and his paper on this subject was highly praised by Berzelius. Dartmouth college about the same time conferred upon him an honorary degree of M. D. Since 1828 ho has resided in Boston or its vicinity, and has devotod his time to chemical investigations, filling also successively the posts of director of an extensive manufactory of colors and chemical products at Roxbury, of consulting chemist or director of some of the most important dyeing, bleaching, gas, iron, and copper-smelting establishments in New England, and of state assayer of Massachusetts. His contributions to science have been numerous and valuable, and may be found chiefly in the " Proceedings " of the American academy and of the Boston society of natural history, in the "American Journal of Science," and in the "Annual of Scientific Discovery." In 1837 he conducted an elaborate investigation upon the economical generation of steam and the relative value of fuels, which in 1838 led to a novel arrangement of steam boilers.

To Dr. Hayes belongs also the credit of the application of the oxides of iron in refining pig iron in the puddling furnace, so as to produce without loss a pure malleable iron; and still earlier, the refining of copper was, under his direction, rendered a much shorter and more certain operation, by the introduction of the scales of oxide of copper produced in refining. Among his other important original researches are those in relation to the chemical decomposition of alcohol by chlorine and the formation of chloroform; upon the action of alcohol on the human system, and the demonstration of its invariable oxidation in the system into aldehyde and acetous and acetic acids; on the formation, composition, and specific differences of the varieties of guano; on the existence of a deposit of native iron on the west coast of Africa; and a memoir on the difference in the chemical constitution and action of sea waters, on and below the surface, on soundings, and at the entrances of rivers. This last research forms part of an investigation undertaken under a commission from the United States navy department to examine and report on the subject of copper and copper sheathing as applied in the construction of national vessels, and his report embodies a vast amount of scientific and commercial information.

In 1859-'60, while considering the question of supply of water to the city of Charlestown, he found, as his earlier analysis indicated, that the deep water of Mystic pond was far less pure than the surface water. The question of diffusion under a flowing surface came up for study, with the responsibility of accepting or rejecting the source of supply. He had proved that a copper strip or wire, passing vertically through two masses of water of slightly unlike composition, would become polarized, and exhibit electrolytic action. This mode of testing the exact limits of the impure water was applied under his direction, and it was shown that a compound affording sulphur when decomposed could be detected by its action on the strip to form a black sulphide, and the limits of the existence of this compound were read on the surface of the strip of copper, or silvered copper. A large number of observations on this and other masses of water have proved the high practical value of the application, and demonstrated the presence of a stream of naturally pure water, nearly 20 ft. deep, flowing over impure water without contamination. After the outbreak of the civil war, Dr. Hayes called public attention to the uncertainty of the foreign supply of saltpetre, and the necessity of domestic production.

His efforts resulted in the manufacture of the supply for the navy from caustic potash and nitrate of soda, by a novel process, the product being of great purity. After spending two years in Europe, to restore his impaired health, studying various phenomena of chemical geology, he returned to the United States, and for the last few years has withdrawn from active life.