Irritant
in pharmacy, that which produces irritation or excitement of any muscle, nerve, or other organ or part of the body. A pure irritant is a poison producing inflammation without corrosive action on the tissues. IRTISH (er'tish), a river of Siberia, the chief affluent of the Obi, rises at the E. end of the Altai Mountains, passes through Lake Saisan, breaks through the Altai in the W. at the bottom of a savage gorge, and flows N. W. across the IRVING steppes of Western Siberia to join the Obi, from the left, at Samarow. At that point it has a width of 2,000 yards; its total length is 1,620 miles; the area of its basin, 647,000 square miles. The important towns of Se Semipalatinsk, Omsk, and Tobolsk stand on its banks. From April to November it is navigable from its mouth as far as Lake Saisan; during the rest of the year traffic is carried on by means of sledges. Its current is gradually shifting E. Its best known tributaries are the Buchtarma and Om from the right, and the Tobol and Ishim from the left.
IRUS (I'rus), a beggar of Ithaca and lover of Penelope, killed by Ulysses by a blow with his fist.