PALLA PALLAS. 



399 



till the arrival of the French minister Aclet, who was [ 

 himself a man of science, and who afforded Palisot J 

 the means of prosecuting inquiries into the natural [ 

 history of America. He was employed to arrange 

 Peale's collection, and made scientific tours to the 

 Appalachian mountains and the country beyond. At 

 length, he received the news of his name being erased 

 from the list of emigrants, and returned to his native 

 country, taking with him the rich collection of natural 

 curiosities which he had formed. In 1806, he was 

 admitted into the institute in the room of Adanson ; 

 and he became a member of other learned societies. 

 He died January 21, 1820. Among his principal 

 works are Flore d'Oware et de Benin (Paris, 1804 

 21, 2 vols., folio); Jnscctes recueillis en Afrique et 

 en Amerique (1805 21, folio) ; Essai d'une nouoelle 

 Agrostographie, ou Nouveaux Genres des Graminees 

 (1812, 4to and 8vo) ; all which are illustrated by 

 engravings. 



PALLA ; a long garment of the Roman women, 

 which hung down to the feet, and was worn over the 

 other dress. When long enough; they threw part of 

 it over the left shoulder, and held it fast under the 

 arm. At funerals it was black. Tragic actors also 

 wore the palla. 



PALLADIO, ANDREA; one of the greatest classi- 

 cal architects of modern Italy, whose works of art 

 and writings alike contributed to improve the taste of 

 the age in which lie lived, and direct the genius of 

 posterity. He was born at Vicenza, in the Venetian 

 territory, in 1518, and, after having studied under 

 Trissino, he went to Rome, where he acquired a ma- 

 turity of skill and science from an examination of the 

 productions of ancient and modern art which that 

 capital afforded. Returning to his native country, 

 he established his fame by his designs for many noble 

 edifices both there and in other parts of Italy, which 

 have afforded models for some beautiful structures in 

 England, as well as other parts of Europe. Palladio 

 belongs to the masters who, in the sixteenth cen- 

 tury, by the study of the works of Roman architec- 

 ture, created a new era in architecture. Among 

 many splendid works executed from his designs and 

 under his direction, the theatre degli Olimpici, in his 

 native place, is the most brilliant proof of his talents. 

 Venice also owes to him many of her finest buildings. 

 The villa built by lord Burlington at Cheswick (but 

 since enlarged by James Wyatt) was from a design 

 of Palladio, as was also a bridge at Wilton, the seat 

 of the earl of Pembroke, in Wiltshire. The majestic 

 simplicity of antiquity was always present to his 

 mind, and Algarotti called him the Raphael of archi- 

 tects. But this great architect is best known in the 

 present age on account of his published works, espe- 

 cially his Treatise on Architecture, in four books, 

 which first appeared in a folio volume, at Venice, in 

 1570, and has been many times reprinted. The best 

 edition is that of Vicenza, 1776 83, 4 vols. It has 

 also been translated into French and English. James 

 Leoni, an Italian architect, published Palladio's 

 Architecture in English, with the notes and remarks 

 of Inigo Jones, and engravings by Picart (London, 

 1742, 2 vols., folio) ; and some of the designs of this 

 architect were published by lord Burlington in 1730. 

 Palladio was likewise the author of an Italian work 

 on the antiquities of Rome (Venice, 1594, and Rome, 

 1599, 8vo), and of Illustrations of the Commentaries 

 of Caesar. He died at Vicenza, in 1580. Chapuy 

 and Anted. Beugnot have published Palladio's 

 (Euvres Completes, with plates and notes, at Paris 

 1827 seq., in 20 numbers, folio. See Remanza's 

 Lives of Venetian Architects and Sculptors. 



PALLADIUM; a wooden image of Minerva 

 (Pa //*), 'wliich is said to have fallen from heaven, 

 and to have been found by Ilus, who placed it in a 



temple in his new city (Ilium). It was believed by 

 the Trojans, that their city would be invincible so 

 long as it contained the Palladium. Ulysses and 

 Diomedes, to remove this impediment to the capture 

 of the city, are said to have carried it off". The Ro- 

 mans, however, pretended that it was brought to 

 Italy by ^Eneas, and preserved in the temple of 

 Vesta, at Rome. It was considered so holy, that 

 even the pontifex maximus did not dare to look upon 

 it. Other cities, however, claimed to have posses- 

 sion of it. The term palladium has figuratively ac- 

 quired the sense of bulwark, protection, sanctuary. 



PALLADIUM ; the name of a metal discovered 

 by doctor Wollaston, associated with platina ore, 

 among whose grains it exists alloyed with indium 

 and osmium, in grains still more minute than those 

 of the platina. The process of separating it from 

 the substances with which it occurs, is too long to be 

 detailed here, and must be sought in the larger che- 

 mical treatises. When pure, it is of a grayish white 

 colour, and is scarcely distinguishable from platina. 

 It is ductile and very malleable ; in hardness, superior 

 to wrought iron, and possessed of a specific gravity 

 of 11 '8. It is a less perfect conductor of caloric 

 than most metals, and less expansible, though in this 

 it exceeds platina. On exposure to a strong heat, its 

 surface undergoes a tarnish, and becomes blue. Its 

 melting point is higher that that of gold ; but if 

 touched, while hot, with a small piece of sulphur, 

 it runs like zinc. The sulphuret thus formed 

 is whiter than the metal itself, and extremely 

 brittle. Nitric acid soon acquires a fine red colour 

 from palladium, but the quantity which it dissolves 

 is small. Sulphuric and muriatic acid act in a 

 similar manner. Nitro-muriatic acid, however, dis- 

 solves it rapidly, and assumes a deep red colour. Al- 

 kalies and earths throw down a precipitate from its 

 solutions, generally of a fine orange colour. Alkalies 

 act on palladium even in the metallic state ; the 

 contact of air, however, promotes their action. A 

 neutralized solution of palladium is precipitated of a 

 dark orange or brown, by a recent muriate of tin ; 

 but if it be in such proportions as to remain trans- 

 parent, it is changed to a beautiful emerald-green. 

 Green sulphate of iron precipitates palladium in a 

 metallic state. Sulphureted hydrogen produces a 

 dark-brown precipitate ; prussiate of potash, an 

 olive-coloured bne ; and prussiate of mercury, a yel- 

 lowish-white. As the last does not precipitate pla- 

 tina, it is a good test of palladium. This precipitate 

 is from a neutral solution in nitric acid, and detonates 

 at about 500 Fahr., in a manner similar to gun- 

 powder. All the metals, except gold, silver, and 

 platina, precipitate it in the metallic state. 



PALLAS, PETER SIMON, imperial Russian coun- 

 sellor, celebrated for his travels, particularly in that 

 empire, and for his numerous observations and dis- 

 coveries made there, born at Berlin, 1741, was the 

 son of a physician, and chose the study of medicine, 

 with the purpose of devoting himself only to the 

 natural sciences, particularly to natural history. For 

 this object, Holland then offered the largest collec- 

 tions and the best instructors. He therefore went to 

 Leyden, and published there, in 1760, his disserta- 

 tions on the Entozoa. He afforded important aii 1 to 

 Volkmann, who was arranging the splendid collection 

 of natural curiosities in the Hague, belonging to the 

 stadtholder, and became so skilful in the art of ar- 

 ranging and describing collections of natural history, 

 that, after he had visited Britain, he was employed 

 in superintending the arrangement of cabinets in 

 this department, and was thus enabled to publish his 

 Elenchus ZoopAytorum (still a classical work on 

 zoophytes) and his Miscellanea Zoologica (1760). 

 ! He then returned to Berlin, and began to publish 



