ALTENBURG ALUM. 



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When this was changeri into a church ceremony, the 

 nltar yet remained a table, placed in the choir of the 

 church, used for the distribution of the Lord's sup- 

 per, and for various other purposes. Altars of 

 mason-work were, probably, first used among Chris- 

 tians in the reign of Constantine the Great. The 

 regulation of placing them always towards the east 

 originated with.Sextus II. Since the time of Gre- 

 gory VI., Roman Catholic churches frequently con- 

 tain several altars. The high altar, the most im- 

 portant, is in the chancel of the church, somewhat 

 elevated ; the other smaller ones are near the pil- 

 lars, or the side walls, or in the chapel. In the 

 larger Protestant churches, also, there is usually a 

 great and small altar. 



^ ALTENBURG; a Saxon duchy, which is divided 

 into two parts by the principality of Gera. At pre- 

 sent, it belongs to the houses of Gotha and Saal- 

 feld. The division belonging to the former house 

 contains about 525 square miles, with 109,557 inha- 

 bitants, famous for their attention to agriculture and 

 to the breeding of cattle. It is one of the most 

 beautiful and best cultivated parts of Germany. The 

 division of Saalfeld contains about 212 square miles, 

 with 30,500 inhabitants (according to some, about 

 170 square miles and 21,400 inhabitants); lias four 

 cities, one market-town, and 100 villages. Each 

 line possesses full sovereignty. The city of A., well 

 built on the Pleisse, contains 1279 houses, 10,100 

 inhabitants, and, till 1308, was a free city of the 

 empire. 



ALTER, Francis Charles, a German Jesuit and 

 laborious scholastic critic, was Greek teacher at 

 Vienna, where he died in 1804. He was author of 

 no less tlian 250 volumes of dissertations, one of the 

 principal of which is " Novum Testamentum ad 

 codicem Vindobonensem Grace expressum," 2 vols. 

 8vo. 



ALTER EGO (Latin; the other I); a law term, 

 used particularly in the official style of the kingdom 

 of the Two Sicilies, by which the king gives to a 

 substitute, appointed to manage the aflairs of the 

 kingdom, the full exercise ot royal power. This 

 happened in Naples after the insurrection of Monte- 

 forte, where the present king, when crown-prince, 

 July 6, 1820, was appointed by his father vicar- 

 general of the kingdom. In France, the phrase 

 used to express this is lieutenant-general du royaume. 



ALTITUDE denotes the perpendicular height of the 

 vertex of any plane, or solid body, above the line or 

 plane of its base ; thus the altitude of a triangle is 

 measured by a perpendicular let fall from any one of 

 its angles upon the base, or upon the base produced ; 

 therefore the same triangle may have different alti- 

 tudes, accordingly as we assume one side or another 

 for its base. Again, the altitude of a cone or pyra- 

 mid, whether right or oblique, is measured by a 

 perpendicular let fall from the vertex to the plane 

 of its base. Similar remarks apply to other solids. 

 In astronomy, altitudes are measured or estimated 

 by the angles subtended between the object and the 

 plane of the horizon ; and this altitude may be either 

 true or apparent. The apparent altitude is that 

 which is obtained immediately from observation ; 

 and the true altitude that which results from cor- 

 recting the apparent altitude, by making allowance 

 for parallax, refraction, &c. The altitude of a ter- 

 restrial object is the height of its vertex above some 

 horizontal plane assumed as a base. The altitude 

 of mountains is measured, generally, from the level 

 of the ocean ; that is, the altitude of a mountain is 

 the difference between the mean terrestrial radius, 

 and the distance of the vertex of the mountain from 

 the centre of the. earth. If the altitude of a moun- 

 tain is given without "any explanation, the altitude 



above the ocean is always understood. This altitude 

 can be measured trigonometrically, by barometrical 

 observations, or by actually measuring the nearest 

 distance between the level at the base and that al 

 the vertex of an object ; and, if very great accuracy 

 is not required, by optical reflection, uy the length 

 of shadows, by moveable staves, the geometrical 

 square, &c. ; and, generally, by any method in 

 which the calculation depends upon the similarity of 

 plane rectilinear triangles. 



ALTO, or ALTO TENOKE. Alto is the term ap- 

 plied to tliat part of the great vocal scale which lies 

 between the mezzo soprano and the tenor, and which 

 is assigned to the highest natural adult male voice. 

 In scores it always signifies the counter-tenor part. 



ALTONA ; the largest city of Denmark, after Co- 

 penhagen, in the duchy of Holstein ; 53 54' 25" N. 

 lat. ; 9 55' E. Ion. ; two miles from Hamburg on 

 the Elbe. The city contains upwards of 23,000 in- 

 habitants ; among whom are 2400 German and Por- 

 tuguese Jews, under the direction of a rabbin. The 

 remainder are Lutherans, Calvinists, Catholics, and 

 Anabaptists. The number of houses is about 2230. 

 There are also 520 habitable cellars. The city is 

 built on the side of a steep hill, which gives it the 

 appearance of an amphitheatre, when viewed from 

 the side of the Elbe. The commerce of A., both 

 inland and foreign, is considerable. The Danish 

 government has conferred many privileges on the 

 city. Here is a board of commerce, a mint, an ex- 

 change, a royal bank, and, since 1739, a royal school. 

 In 1713, A. was almost totally burned by the Swe- 

 dish general Steenbock. It has been since beauti- 

 fully rebuilt. 



ALTRANSTADT ; a town in Saxony, famous for the 

 treaty concluded between Charles XII., king of 

 Sweden, and Augustus, elector of Saxony, Sept. 

 24, 1706, by which the latter resigned the crown of 

 Poland. After the defeat of Charles, at Pultawa, 

 Augustus, Aug. 8, 1709, declared the peace of Al- 

 transtadt void, because his commissioners, von Imhof 

 and Pfingsten, had exceeded their powers in signing 

 the conditions. The former was condemned to be 

 imprisoned for life, the latter to be put to death. 

 Augustus, at the invitation of some Polish nobles, 

 returned to Poland, took possession of the throne, 

 and renewed his alliance with the czar. 



ALUM, artificial. Common alum is a triple salt, 

 consisting of sulphuric acid, alumine, potash, and 

 water, or of sulphate of alumine and sulphate of 

 potash, united together, with a certain quantity of 

 water of crystallization. It crystallizes in regular 

 octahedrons, which are generally truncated on their 

 edges and solid angles. Alum may also be formed 

 by substituting either soda, ammonia, or magnesia 

 for the potash, without at all altering its crystalline 

 form or its taste. It dissolves in five parts of water, 

 at 60, and the solution reddens vegetable blues, 

 indicating the excess of acid which this salt contains. 

 Exposed to heat, it undergoes a watery fusion, and 

 becomes light and spongy, in which condition it 

 possesses slightly corrosive properties, and is used as 

 i caustic, under the name of almnen cxsiccatum. 

 The simplest process by which alum is prepared is, 

 perhaps, that adopted at the Solfatara near Naples, 

 which is covered with a white clayey soil, through 

 which sulphureous vapours are constantly emitted. 

 This soil is always hot, and nothing more is requisite 

 than to immerse it into cisterns, and subject the 

 earthy matter to lixiviation ; after which, the saline 

 solution is evaporated by means of the subterra- 

 nean heat, and placed in a situation to cool, when 

 the alum is deposited in crystals. As nothing is 

 added during the process, it is obvious that the alum 

 must exist ready formed in the soil. From the pre- 



