T A L 



[426] 



TAP 



separate, and their extremities fuse 

 into a white enamel. Its consti- 

 tuents are principally silex and 

 magnesia, with small quantities of 

 potash, alumine, oxide of iron, and 

 water. Talc and chlorite are nearly 

 allied, and pass, by insensible gra- 

 dations, into each other. Talc is 

 sometimes used as a substitute for 

 glass, and windows are formed of 

 its Iamina3, which are sometimes 

 obtained of the size of twelve inches 

 square. There are two varieties of 

 talc, namely, fibrous talc and in- 

 durated talc. 



TA'LCTTE. The nacrite of Brongniart ; 

 talc granuleux of Hatly ; erdiger 

 talc of Werner. A rare min- 

 eral, occurring in coats or reniform 

 masses, composed of very minute 

 shining spangles or scales. "When 

 rubbed between the fingers, it 

 leaves a pearly gloss. 

 TALCOCA'LCTTE. A name proposed, by 

 Dr. Boase, to be given to a genus 

 of rocks. Talcocalcite is a com- 

 pound of granular felspar and talc : 

 its species all effervesce with dilute 

 muriatic acid. The genus is divided 

 into four species, namely, compact, 

 schistose, lamellar, and silicious : 

 these all possess, more or less, a 

 silky texture. 



TALC-SCHIST. A genus of minerals in 

 the classification of Dr. Boase, and 

 thus described by him : "A basis 

 of granular felspar, intermixed 

 with, and laminated by, talc." It 

 is a glossy slate, having the pecu- 

 liar saponaceous feel of magnesian 

 minerals. Dr. Boase enumerates 

 four species : T. foliated ; T. lamel- 

 lar; T. crenulated; T. schistose. 

 Talc-schist is intimately connected 

 with euphotide and serpentine, by 

 the change of diallage into talc. 

 TA'LTJS. (talus, Lat. talus, Fr. incli- 

 nation que Von donne d la surface 

 laterale et exterieure d'un mur, de 

 telle sorte que de haut en las il aille 

 toujours en s 1 epaississent. 11 se dit 

 aussi d'une terrasse sans rnurs, lors- 



que ses faces laterales elargissent dc 

 Jiaut en las.} 



1. A sloping heap. "When, from 

 disintegration, the fragments of a 

 face of rock accumulate at its base 

 and form a sloping heap, the heap 

 is called a talus. 



2. In anatomy, a name sometimes 

 given to one of the bones of the 

 tarsus, the astragalus. 



TA'NTALITE. Called also Columbite. 

 The ore of tantalum or columbium. 

 When recently broken, tantalite is 

 of a dark bluish-gray, or nearly 

 iron-black colour. It occurs in 

 octohedral crystals, and in small 

 masses. Its specific gravity is 

 from 5-9 to 7-9 It consists of 

 oxide of columbium 80, oxide of 

 iron 12, oxide of manganese 8. 

 TA'NTALTJM. A metal extracted from 

 tantalite; it appears to be the same 

 substance as columbium, and iden- 

 tical with it. It is one of the 

 simple or elementary bodies. 

 TA'PIK. A genus of mammalia, be- 

 longing to the family Pachyder- 

 mata Ordinaria. The nose of the 

 tapir may be compared to a small 

 fleshy proboscis, the snout being 

 lengthened and moveable. There 

 are several species of this genus 

 still surviving, but they are all 

 natives of tropical climates. The 

 general appearance of the tapir is 

 that of a pig, but some of the spe- 

 cies are as large as the ass. The 

 fore feet have four toes each, all of 

 equal size ; the hind feet have only 

 three each. The skin is of a dark 

 colour, nearly black, with but few 

 hairs. 



Fossil tapirs are found in differ- 

 ent parts of Europe. They appear 

 to have far exceeded in size any of 

 the living species. They belonged 

 to the same era as the fossil ele- 

 phants and mastodons ; lived with 

 them, and were destroyed by the 

 same catastrophe ; their bones be- 

 ing found in the same strata. 

 TAP-BOOT. In botany, the main root 



