NIS'SEN, Heinrich (1839—). A German
archæologist. He was burn at Habersleben, stud-
ied at Kiel and Berlin, and became professor of
ancient history at Marburg (1869), Göttingen
(1877), Strassburg (1879), and Bonn (1884).
Nissen especially devoted himself to the critical
study of early Roman history. He wrote
Kritische Untersuchungen über die Quellen der
vierten und fünften Dekade des Livius (1863), Das
Templum (1869), Pompejanische Studien (1877),
Italische Landeskunde (1883), and "Griechische
und römische Metrologie" (1887) in Iwan Müller's
Handbuch der klassischen Altertumswissenschaft.
NI'SUS (Lat, from Gk. N(<ros, xVisos). (l)ln Greek mythology-, a King of ilegai-a. and son I of King Pandion of Athens. His datighter I Scylla fell in love with Minos, King of Crete, I when the latter, on his expedition against the i Athenians, besieged Megara, and betrayed the j city to him. She slew her father by cutting off I a purple lock of hair, on the preservation of which his life depended, but Minos punished her treachery by dragging her after his ship and drowning her. She was changed into the bird called Ciris, in which form she was constantly pursued by Xisus, transformed into a sea-eagle. The legend is treated by Vergil in the Ciris, and by Ovid, Met., viii. 145. (2) A companion of -Eneas and friend of Euryalus, with whom he was slain in the war against Turnus. NIT'HABD (c.795-843). A Prankish histo- rian, son of Bertha, daughter of Charles the Great. He was a warrior and a statesman and Bided with Charles the Bald in the qtiarrels be- tween the sons of Louis the Pious. Nithard fought in the great three days' fight at Fontenoy in 841, and was killed two years after in a bat- tle with the Northmen near AngoulOnie. His Latin history deals with the dissensions of the sons of Louis the Pious ; it is valuable, but strongly partisan, and is remarkable as one of the few documents of the Middle Ages written 1)V a lavman. The work is edited bv Pertz (Han- over, 2'd ed.. 1870). Consult: Patz, Dr Vita et Fide Xitluirdi (Halle, 1865), and ^Meyer von Knonau, Ucbcr Xitkai'ds vier BUcher Geschichten (Leipzig, 1880).
NITHSDALE, nich'd&l, William Maxwell, Earl of (1676-1744). A Scotch Jacobite, the Willie of 'Kenmure's up and awa'.' He partici- pated in the Jacobite rising of 1715. He was captured after Preston, and was rescued from the Tower by his wife, who took his place in prison while he escaped in her clothes. He made his way to Rome, where he joined the Pretender. The Countess of Nithsdale wrote the story of his escape published in the first voliune of the Transactions of the Societies of Antiquaries of Scotland.
NITO'CKIS. A Queen of Eg>-pt (Nitaqert. or Nitaqrit ) , the last ruler of the Sixth IJynasty. She w'as sister of Menthuophis, whom she succeeded, and whose murder she avenged by drowniing all she suspected of connection with the plot, after having called them together for a feast. The third in size of the great pyramids was enlarged by Xitocris. and there she was buried, .bout her beauty legends grew up ; the Greeks called her Rhodopis, translating the Egyptian e])ithet, red-cheeked; they argued she must have been a Greek, made her a courtesan, and told how the King married her, having
fallen in love with her lost slipper — the earliest form of the legend of Cinderella. Another legend in the Middle Ages makes her a beautiful spirit who haunts the pyramid and drives men mad for the love of her.
NITRATE OF SODA. See Manures and Manuring.
NITRATES. See Nitric Acid.
NITRE. See Saltpetre.
NITRIC ACID (from Neo-Lat. nitnim, nitre, natron, Lat. nitrum, from Gk. virpov, nitroiiy Xlrpop, liiron, natron, of Semitic origin, cf. Heb. iieter, ]uitron, from nular, to loose), HNO3. A powerfully acid compound of hydrogen, nitrogen, and oxygen. Geber, in his De Inventione Veri- tatis, described a method of preparing the acid by heating potassium nitrate with alum and cop- per sulphate, and tJlauber was probably the first to prepare it by the action of free sulphuric acid upon saltpetre (the acid was long known as 'spiritiis nitri fumaiis Glauberi') . In 166!)Mayow described nitric acid as containing two com- ponents, one from the air and one from the earth. In 1776 Lavoisier demonstrated that one of its constituents was oxygen, and in 1785 Cavendish showed the composition of the acid by synthesiz- ing it from oxygen and nitrogen in the presence of water. However, the true composition of its molecule was not recognized until long after- wards, when chemists had realized that acids in general were compounds necessarily containing' hydrogen. (See Chemistry.) Nitric acid does not occur in a free state in nature, but after thunder storms traces of it are found in rain water, and according to Boussingault, amounts of nitric acid up to 0.66 nig. to the liter have been found in the rain falling on the Alps. It occurs largely, however, combined in the form of alkaline nitrates, in Chile and elsewhere, the formation of the nitrates being supposed to originate in the putrefaction of nitrogenous or- ganic matters: the latter are assumed to be con- verted into ammonia, and this to be oxidized in presence of the hydroxide of potassium, sodium, or calcium, into the corresp<mding nitrate. Nitric acid may be made by the action of strong sul- phuric acid on the nitrate of sodium or potas- sium, the former being generally employed on a commercial scale on account of its cheapness. Cast iron retorts are charged with about 670 pounds of dry sodium nitrate, about 530 pounds of strong sulphuric acid are added, and heat is applied. The volatile nitric acid, on forming, passes into a series of large bottles provided with inlet and outlet tubes ('Woulff's bottles') and containing small amounts of water. Nitric acid is, however, not the only product, a certain amount of peroxide of nitrogen being fm-med at the same time. Some of this dissolves in the nitric acid, imparting to it a more or less intense red coloration. Another portion of the peroxide is caused to come into contact with moist air. in a tower attached to the last of the large bot- tles, and thus this portion of the peroxide is converted into nitric acid. Sodium sulphate re- mains as a by-product of the process in the east- iron retorts. The acid jiroduct generally contains about 55 per cent, of nitric acid, the rest being water and small amounts of chlorine, iodic acid, oxide of iron, sulphuric acid, sodium sulphate, and peroxide of nitrogen, the non-volatile of
