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ISOS'CELES, uroa-xtKvif, equal-legged; 

 froTdifo!, equal, and <TI}.O; , a leg. An 

 isosceles trian- 

 gle is one 

 which has two 

 equal sides ; 

 such is the tri- 

 angle ABC. 

 The angles at 

 the base of such 

 a triangle are 

 equal, and 

 the legs be pro- - 7 

 duced, the an- / 

 gles under the 

 base are also equal. 



ISOTH'ERAL, from iiroi, equal, and 

 Bte<>{> summer. Having the same sum- 

 mer temperature. Isotheral lines are those 

 drawn on a map through places having 

 the same summer temperature. 



ISOTHER'MAL, from iirot, equal, and 

 t, heat. Having equal temperature. 



Isothermal lines are those drawn on a map 

 through places having the same annual 

 mean temperature. Isothermal zones. To 

 avoid the confusion arising from the mul- 

 tiplicity of isothermal lines, geographers 

 have grouped them into zones or bands. 

 Thus the northern hemisphere is divided 

 into six isothermal zones by Humboldt. 



ISOTON'IC, from tiros, equal, and rave?, 

 tone. Having equal tones. In music, the 

 isotonic system consists of intervals in 

 which each concord is alike tempered, 

 and in which there are twelve equal 

 semitones. 



ISTH'MIAN GAMES, one of the four great 

 national festivals of Greece, so called 

 from being celebrated on the Isthmus of 

 Corinth. 



IS'SDANT, an epithet in heraldry for any 

 beast issuing out of the bottom line of 

 any chief or fess. 



Is'suz, Fr. issue, Ital. uscto, a door. A 

 term extensively applied both as a sub- 

 stantive and verb. Thus bankers issue 

 paper-money, and regulate the amount 

 of their issue* by the circumstances of 

 trade. A cause issues to the court, and 

 finally issues in demurrer. Profits of land 

 or other property, the legitimate off- 

 spring of parents, the point of matter 

 depending in suit, &c., are all issues in 

 legal phraseology. Surgical issues are 

 little ulcers made designedly in various 

 parts of the body, and kept open by the 

 patient for some specific object. 



ITAL'ICS, letters or characters first used 

 In Italy, and which stand inclined, as 

 those in which this clause is printed. They 

 are often used, by way of distinction from 

 Roman letter, to mark emphasis, antithe- 

 sis, &c. To italicite, is to write or print in 

 Itailc chartctcrs. 



ITAL'IC SCHOOL or Pitit-osopHT. Tbe 

 Pythagorean and Eleatic systems. 



ITE. In chemistry, acids whose names 

 terminate in out, produce salts different 

 from those whose names end in ic ; and to 

 indicate that a saline compound is formed 

 by an acid ending ous, the termination ite 

 is used ; whereas ate is used when the acid 

 terminates withic. Thus the sulphites are 

 formed by sulphurous acids with bases, 

 and the sulphates by the sulphuric acid 

 with the same bases. See ACID. 



ITIHAS'AS. The two great heroic poems 

 of the Hindoos, the Ramayana and Maha 

 Sharata : they are of great antiquity. 



I'TIS. This termination, added to the 

 Greek name of an organ, implies inflam- 

 mation of that organ; thus, gastritis, in- 

 flammation of the stomach. 



IT'TNERITE. A rare mineral, which oc- 

 curs massive, and in rhombic dodeca- 

 hedrons, of a gray or bluish tint. It 

 consists principally of silica, alumina, 

 soda, and hydrosulphuret. 



I'VA, a genus of plants. Syngenesi 

 Poly, necessaria. The I- frutescens affords 

 the Mexican quinquina, much celebrated 

 in its native country as a febrifuge. This 

 is a shrubby plant, but all the other spe- 

 cies are annuals. Warm parts of America. 



I'VORT, Fr. ivoire. The name given to 

 the tusks of the elephant and the walrus, 

 and to the horn of the narwhal. It is an 

 intermediate substance between bone and 

 horn, containing about twenty- four per 

 cent of gelatine. The hardest, toughest, 

 and most translucent ivory is reckoned 

 the best. It is readily distinguished from 

 bone by its peculiar rhombohedral net- 

 work, shown when, the ivory is cut trans- 

 versely. 



I'VORT BLACK, an animal charcoal, pre- 

 pared by the calcination of ivory dust, 

 used as the basis of the finer black pig- 

 ments, ink for copperplate printing, &c. 



IVY-GEM, a resinous juice which exudes 

 from the stem of the ivy-tree, Hedera he- 

 lix, in warm climates. It is imported 

 from the East Indies, in compact reddish- 

 brown masses. 



IX'ODES, the name given by Latreille to 

 a sub-genus of acari found in thickets, and 

 fastening on dogs, oxen, horses, and other 

 quadrupeds, from which they can only be 

 detached by tearing out the part to which 

 they adhere by their suckers, which they 

 bury completely in the flesh. They are 

 vernacularly named ticks, and are exceed- 

 ingly plentiful in warm and dry seasons. 



J. 



J. A letter added to the English alpha- 

 bet in modern days, and ranked as the 

 tenth, being written in words where I. 

 was formerly used, and before 



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