ZISCA. 



177 



soluble oxalate of ammonia is formed. It is then 

 to be filtered, and the oxalate washed, until no iron 

 can be detected in the water that passes. The 

 earthy oxalate is, when dry, of an opaline colour. 

 After being well washed, it is to be decomposed 

 by heat in a platina crucible. Thus obtained, the 

 zirconia is perfectly pure, but is npt affected by 

 acids. It must be reacted on by potash as before, 

 and then washed until the alkali is removed. After- 

 wards dissolve it in muriatic acid, and precipitate 

 by ammonia. The hydrate thrown down, when 

 well washed, is easily soluble in acids. It is inso- 

 luble in water and the pure alkalies, but the alka- 

 line carbonates dissolve it. Heated with the blow- 

 pipe, it does not melt, but emits a yellowish phos- 

 phoric light. Heated in a crucible of charcoal, 

 bedded in charcoal powder, placed in a stone cru- 

 cible, and exposed to a good forge for some hours, 

 it undergoes a hasty fusion, which unites its parti- 

 cles into a gray opaque mass, resembling porcelain. 

 In this state, it is sufficiently hard to strike fire 

 with steel, and scratch glass. Specific gravity 4-3. 

 Potassium, when brought into contact with zirconia 

 ignited to whiteness, is converted into potash, and 

 dark particles of zirconium, the metallic base of 

 the earth, make their appearance. They are as 

 black as charcoal, and, at a temperature slightly 

 elevated, burn with great intensity. It combines 

 with sulphur, and forms a sulphuret of zirconium. 



ZIRKNITZ, OR CZIRKNITZ; a remarkable 

 lake of the Austrian states, in Carniola, twenty- 

 three miles south-west of Laybach. It is situated 

 amidst lofty mountains and frightful precipices, 

 containing vast subterranean caverns, which com- 

 municate with each other by openings, in general 

 small. The lake is six miles in length, and three 

 in breadth, and presents a curious phenomenon. 

 The bottom remains dry for about four months, 

 is cultivated, and made to produce a crop of 

 millet and hay. At the end of that time, the 

 water rises with great impetuosity, and fills the 

 lake in the short space of twenty-four hours. This 

 singular phenomenon is owing to its having two 

 subterranean outlets, by which the water is dis- 

 charged, and through which it again rises. 



ZISCA, OR ZIZKA (pronounced Shishka}. John 

 Zisca, of Trocnow, the formidable general of the 

 Hussites, was descended from a noble Bohemian fa- 

 mily, and was born about 1360, onafarm belonging 

 to his parents, at Trocnow, in the present circle of 

 Budweis, in the open air, under an oak. He lost 

 his right eye in his boyhood, but did not, as some 

 have supposed, derive the name of Zisca from that 

 circumstance. This was the name of his family, 

 and does not signify one-eyed. He went as a page 

 to the court of Wenceslaus VI., king of Bohemia, 

 where he subsequently became a chamberlain. He 

 displayed great talents from early youth, but, at 

 the same time, a gloomy and solitary disposition. 

 His first military service was in the band of volun- 

 teers who went from Bohemia and Hungary to 

 assist the Teutonic knights against the Poles. He 

 took part in the battle of Tanneburg, on July 15, 

 1410, in which the knights suffered a great defeat. 

 Zisca then fought in the Hungarian service against 

 the Turks, and afterwards with the English against 

 the French, at the battle of Agincourt (1415). 

 After his return, he remained at the court of king 

 Wenceslaus, and shared in the indignation of a great 

 part of the Bohemian nation, at the fate of the two 

 reformers, Huss (q. v.), and Jerome of Prague. A 

 monk having dishonoured his sister, who was a 



nun, and abandoned her, Zisca became bent on ven- 

 geance. Wenceslaus himself one day told him, 

 that, if he knew any means of taking revenge for 

 the disgrace inflicted on the Bohemians at Con- 

 stance, he had his consent to use them. Zisca now 

 left the court, tried the disposition of the people, 

 and soon returned to Prague. Nicholas of Hussy- 

 necz had already placed himself at the head of the 

 insurgents, and Wenceslaus called on the citizens 

 of Prague to give up their arms : but Zisca led 

 them armed into the castle (April 15, 1418), and 

 he said to the king, " With these weapons will we 

 fight for thee ;" and the citizens retained their arms. 

 Zisca was considered, from this time, the head of 

 the Hussites. On the occasion of a procession 

 (July 30, 1419), the priest of the Hussites was hit 

 by a stone. They immediately stormed the town- 

 house, at the instigation of Zisca, and threw thir- 

 teen of the city council out of the window on the 

 pikes of the people. King Wenceslaus died of fear 

 in consequence of this affair. His brother and suc- 

 cessor, the emperor Sigismond, delayed undertak- 

 ing the government of Bohemia, and Zisca gained 

 time to make his preparations : yet he was at first 

 obliged to retreat from Prague to Pilsen. Sigis- 

 mond now began to execute the adherents of the 

 new doctrine, and the Hussites, under Zisca, swore 

 never to acknowledge him as king of Bohemia. 

 They erected fortresses, and Zisca caused a town 

 to be built on mount Tabor, from which the Huss- 

 ites are sometimes called Taborites. He fortified 

 the new city in a way which reflected honour on 

 his skill. He is also said to have invented the bul- 

 wark of wagons, by which he protected his infantry 

 against the enemy, as he was destitute of cavalry. 

 In a short time, he disciplined his ill-armed and 

 licentious horde. A few successful engagements 

 procured him better arms, and horses for mounting 

 a part of his men. His enterprises were undertaken 

 from vengeance, religious hatred, and love of plun- 

 der. He committed many cruelties, partly in order 

 to make himself feared, partly because he was 

 obliged to yield to the wild passions of his fanati- 

 cal followers. In order to defend Prague againsf, 

 Sigismond, who was approaching with a large army, 

 he repaired thither, and intrenched himself on the 

 hill of Wittkow. Here, July 14, 1420, he repelled 

 repeatedly the assaults of 30,000 men with 4000 ; 

 and the place is still called Zisca's hill. From want 

 of money, the emperor effected little during this 

 campaign. In 1421, Zisca took the castle of Prague, 

 and there got possession of the first four cannons, 

 which, since the invention of gunpowder, had found 

 their way to Bohemia. From this time, cannons 

 and guns (though the latter could be procured at 

 first only by noblemen) became common among the 

 Hussites and their enemies. Zisca continued his 

 system of plundering in Bohemia, took several for. 

 tresses, generally by assault, and treated the con- 

 quered cruelly. After the death of Nicholas of 

 Hussynectz, in 1421, all the Hussites acknow- 

 ledged him as their leader and chief; but he caused 

 the crown of Bohemia to be offered to the king of 

 Poland. By incredibly quick marches he every- 

 where anticipated the enemy. During the siege of 

 the castle of Raby, an arrow deprived him of his 

 only remaining eye. He now had himself carried 

 about with his army on a car, so that he could be 

 seen by his men, whom he arranged for battle by 

 means of the descriptions which were given to him 

 of the country. He had a legion called the invin- 

 cible brethren, with which he generally decided the 



