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 METAPHYSICS When arsenic and antimony are present, the reactions become much more complicated and complete roasting more difficult. Gold, mer- cury, and silver may be reduced to metal by roasting, owing to their feeble affinity for oxy- gen at high temperatures. Some sulphides are difficult to roast, owing to their fusibility (sulphides of lead, bismuth, antimony, &c.). Chloridizing roasting has for its object the conversion of silver in ore or matte into the condition of chloride, in which form it may be dissolved, or directly treated with metallic iron to separate the silver, as mentioned above. The chlorination of silver is effected by the addition of common salt to the charge to be roasted, which is decomposed by the sulphuric acid generated by the oxidation of the sulphur with the liberation of hydrochloric acid. The methods employed are in general the same as those used in oxidizing roasting. The revolv- ing cylinder (Bruckner's) and the showering furnace (Stetefeldt's, on the principle of Ger- stenhofer) are largely used, and are found to give good results. In many smelting opera- tions, especially where ores of complex compo- sition are used, an alloy of several metals is fre- quently produced. Thus the furnace or work lead from many ores contains copper, antimo- ny, silver, gold, and other metals. The separa- tion of the metals from each other is based on their relative oxidability, on the solvent action of metals and metallic oxides on each other, on difference in fusing point, on crystallization, and on solubility in acids. Examples of these methods will be found in the accounts of the different metals. It will suffice here to men- tion briefly the separation of lead from silver by the oxidation of the former, and the re- moval of copper and other metals at the same time, by the solvent action of litharge on their oxides (cupellation) ; the separation of silver from copper by alloying the latter with lead, and subsequently removing the lead with the silver by heat (liquation) ; the removal of sil- ver from lead by zinc (Parkes's process) and by crystallization (Pattinson's process) ; and the separation of silver from gold by acids. Metals occur in the arts either cast as ingots or in finished forms, or wrought by hammering, rolling, and drawing into sheets, rails, wire, &c. These mechanical processes are intimate- ly connected with and dependent upon the physical properties of the different metals and on their purity. See " Elements of Metallur- gy," by J. Arthur Phillips (London, 1874). METAPHYSICS. See PHILOSOPHY. METASTASIO, Pietro Antonio Domcniro Bonaven- tnra, an Italian poet, born in Rome, Jan. 3, 1698, died in Vienna, April 12, 1782. He is said to have excelled in improvising verses at the age of 10. Gravina, an eminent jurist and scholar, adopted him as a son. changing his name of Trapassi to that of Metastasio (from the Gr. /zerdcrrao-^, change or transfer), and preparing him for the profession of the law, but without discouraging his studies in classical METASTASIO 427 and dramatic literature, in which he advanced so rapidly that at 14 he wrote a tragedy, Oim- tino, after the Greek model. He accompanied his patron to Naples, where his talents gained him many friends. While continuing the study of jurisprudence, he took holy orders, whence he was sometimes called Abbate. Gravina bequeathed him in 1718 a considerable fortune ; but the young poet squandered most of it within two years, and again applied himself to the study of the law. Soon returning to his favorite pursuit, he produced an epithalamium and the drama Endimione. Under the patron- age of the viceroy of Naples he wrote Oli orti esperidi and Angelica, the latter after Ariosto. The part of Venus in the former play was per- formed by Maria Bulgarini, or La Romanina, who was at that time the leading Neapolitan prima donna, and whose appreciation of Me- tastasio's genius laid the foundation of a most intimate relation, the poet writing under her inspiration his Didone ablandonata (1724), which was set to music by Sardi and other composers, and established Metastasio's fame. He accompanied the signora to Rome, where his Semiramide (set to music by Meyerbeer in 1819), Ezio, Alessandro neW India, Catone in Utica, and Artaserse were performed in rapid succession. In 1729 he went to Vienna, where he succeeded Zeno as imperial laureate. In 1733 appeared his Olimpiade ; and one of his most celebrated lyrical dramas, La clemenza di Tito, was performed in 1734, and was again set to music in 1790 by Mozart. The death of the emperor Charles VI. in 1740, and the out- break of war, led to the closing of the theatre in which he had been employed, and he now devoted himself to literary pursuits, chiefly to translations and annotations of Greek writers. In 1744 appeared his plays of Antigone and Ipermnestra. After the return of peace he wrote II re pastore (1751), which was enacted by the ladies of the imperial family. His last operatic play, II Ruggiero, was produced at Milan on occasion of the marriage of the arch- duke Ferdinand (1771). His last occupation was the superintendence of the magnificent Paris edition of his works. Metastasio was among the first to recognize the genius of Mozart, and to express his admiration of a comic opera which the composer, then only 12 years old, had set to music in 1768. His best known oratorios are La morte d^Abele, Isacco, and La passione ; and his most popular cantatas are La liberta, La primavera, and La partenza. A catalogue raisonne of his compositions is given by Dr. Burney. The best editions of his works are those in 12 vols. (Paris, 1780-'82), and 20 vols. (Mantua, 1816-'20). See Burney, " Memoirs of the Abbate Metastasio," with translations of his principal letters (3 vols. 8vo, London, 1796). The best Italian sketch of his literary career is by Mauro Boni in his edi- tion of Metastasio's works (Padua, 1811). His "Dramas and Poems" were translated into English by J. Hoole (3 vols., London, 1800).