544 HAYDUKS HAYES cathedral in Cincinnati. His literary efforts are confined chiefly to his "Lectures on Paint- ing and Design" (2 vols. 8vo, 1844-'6), which are bold and clear expositions of the principles of art as he understood them. He also wrote the article on painting in the " Encyclopaedia Britannica," and induced the government to purchase the Elgin marbles. HAYDPKS, a class of Hungarians who were originally shepherds (Hung. hajdu and from whom patriotic militia organizations subse- quently received the name. The gallantry of the Hayduks was signally rewarded by Bocs- kay, prince of Transylvania and the protector of the rights of the Protestants, who endowed them, Dec. 12, 1605, with privileges of no- bility, and assigned to them a district known as the Hayduk towns (ffajdu-vdrosoty ; and they have retained most of those privileges, excepting immunity from taxation, which was withdrawn by the emperor Charles VI. at the beginning of the 18th century. The district is enclosed within the county of Szabolcs, E. of theTheiss, and comprised in 1870 an aggre- gate population of 59,715, almost all Magyars and Protestants. Besides the capital, Boszor- meny (pop. 19,208), it contains the towns of Dorog (8,216), Hadhaz (7,024), Nanas (13,198), and Szoboszlo (12,269). Menials of Hungarian officials and magnates having been called hay- duks, the name was adopted at German courts for ponderous lacqueys, though these are gen- erally Germans or Swiss, and not Hungarians. HAYEL, or Hail, a city of Arabia, in Nedjed, capital of the sultanate of Shomer, situated in a plain between the mountain ranges Jebel Adja and Jebel Solma, lat. 27 44' N., Ion. 42 42' E., 240 m. N. E. of Medina; pop. in 1862, about 22,000. The walls, which are 20 ft. high, with bastioned towers and folding gates, surround an area capable of containing a popu- lation of 300,000, if its houses were closely packed as in European cities ; but there are many large gardens, open spaces, and planta- tions within their circuit. The palace of the sultan with its pleasure grounds occupies near- ly a tenth of the city. It is surrounded by a wall 30 ft. high, with semicircular bastions along its front, and a gateway flanked by high square towers. From the palace itself rises a massive oval tower 70 ft. high. The streets of the city are irregular, and most of the houses, which are generally of brick with flat roofs, are built about central courtyards. The surrounding plain is studded with houses and gardens, the country seats of wealthy citizens or of members of the ruling family. Hayel is the centre of a thriving commerce. HAYES, Angnstns Allen, an American chemist, born in Windsor, Vt., Feb. 28, 1806. He grad- uated 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 col- lege about the same time conferred upon him an honorary degree of M. D. Since 1828 he has resided in Boston or its vicinity, and has devoted his time to chemical investigations, filling also successively the posts of director of an extensive manufactory of colors and chemical products at Koxbury, of consulting chemist or director of some of the most im- portant dyeing, bleaching, gas, iron, and cop- per-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 appli- cation of the oxides of iron in refining pig iron in the puddling furnace, so as to produce with- out loss a pure malleable iron ; and still earlier, the refining of copper was, under his direction, rendered a much shorter and more certain op- eration, 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 decomposi- tion 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 alde- hyde and acetous and acetic acids ; on the for- mation, 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 water?, 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 ves- sels, 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
