1081 



TONQUIN BEAN. 



TOTIPALMES. 



1032 



tion of taste is altogether unknown, nor has even a probable hypo- 

 thesis been formed. The beat examples of merely sapid substances 

 are the various alkaline and metallic salts, and the inodorous bitters. 

 By experiments with these the sense of taste is found to be subject 

 to many of the same rules as the other senses, and to be especially 

 analogous to that of smell. [SiiELL.] A certain force of application 

 of the stimulus heightens the perception of it. Men instinctively 

 press the tongue against the roof of the mouth and ' smack ' it, to 

 obtain a clear sense of taste, as they inspire quickly in the act of 

 smelling. Contrast of tastes also commonly makes that which is last 

 perceived more obvious, as the eye passing from one colour to another, 

 or the nose from one odour to another, perceives each in succession 

 the more acutely; and there are subjective sensations of taste, as 

 there are of sight and hearing. Such are those produced by the con- 

 tact of two different metals with each other and with the tongue, and 

 those which are perceived in various diseases ; but the circumstances 

 on which they depend are as yet unknown. 



TOXQUIN or TONGA BKAN. [COUMABOUXA.] 



TONSILS. The Tonsils are two complex glands, one of which lies 

 on each side of the fauces, between the arches of the soft palate. 

 They are of an elongated oval form, and each is composed of a 

 number of smaller glands aggregated together in one mass, and usually 

 opening,by several orifices on the surface of the mucous membrane. 

 They form a continuous layer with a great number of similar glands, 

 which are contained in the substance of the palate, in the root of the 

 tongue, and in the space between the tongue and the epiglottis ; and 

 with these the tonsils form a complete ring of glandular tissue 

 around the aperture leading from the mouth to the pharynx. The 

 nature of the fluid secreted by them is not certainly known. It bears 

 a general resemblance to saliva, and probably serves chiefly to lubricate 

 the food for its passage from the mouth to the stomach. 



TOON-WOOD. [CEDHELA.] 



TOPAZ, a Mineral. It occurs massive, in imbedded and rounded 

 crystals. Primary form a right rhombic prism. Cleavage easy, 

 parallel to the base of the primary form, more difficult in the 

 direction of its lateral faces. Structure lamellar at right angles to the 

 axis of the prism. Fracture uneven, rightly conchoidal. Hardness : 

 scratches quartz. Electricity : positive by friction ; those crystals 

 which possess different faces of crystallisation at opposite ends acquire 

 different kinds of electricity at the two extremities when heated. 

 Colour white, yellow, bluish, and greenish. Lustre vitreous, trans- 

 parent, translucent. Specific gravity 3-499. Fragments exposed to 

 heat emit a blue, green, or yellowish phosphoric light. By the blow- 

 pipe on charcoal it does not fuse, but with borax it melts into a 

 transparent glass. Topazes occur generally in primitive rocks, and in 

 many parts of the world, as Cornwall, Scotland, Saxony, Siberia, 

 Brazil, Ac. 



The following analyses have been given of this mineral : (1) Saxon 

 topaz by Klaproth ; (2) Brazilian topaz by Klaproth ; (3) Saxon topaz 

 by Berzelius ; (4) Brazilian topaz by Berzelius : 



(1) (2) (3) (4) 



Silica .... 35 44-5 34-24 34-01 



Alumina . . . . 59 47'5 57'45 58'38 



Fluoric Acid . . 5 7-0 775 7-79 



Oxide of Iron . . . 0'5 



99 99-5 99-44 100'18 



The ancient Topa-um was found on an island in the Red Sea, which 

 was often surrounded with fog, and therefore difficult to find. It 

 wag hence named from ' topazo,' to seek. This name, like most of 

 the mineralogical terms of the ancients, was applied to several distinct 

 species. Pliny describes a statue of Arsinoe, wife of Ptolemy Phil- 

 adelphus, four cubits high, which was made of topazion, or topaz, but 

 evidently not the topaz of the present day, nor chrysolite, which has 

 been supposed to be the ancient topaz. It has been conjectured 

 that it waa a jasper or agate ; others have imagined it to be prase, or 



Topaz is employed in jewellery, and for this purpose its cc^ur is 

 often altered by heat. The variety from Brazil assumes a pinker red 

 hue, no nearly resembling the Balas ruby, that it can only be distin- 

 guished by the facility with which it becomes electric by friction. 

 The finest crystals for the lapidary are brought from Minas Novas, in 

 Brazil. From their peculiar limpidity, topaz-pebbles are sometimes 

 denominated Oouttes d'Eau. When cut with facets and set in rings, 

 they are readily mistaken, if viewed by daylight, for diamonds. The 

 coarse varieties of topaz may be employed as a substitute for emery 

 in grinding and polishing hard substances. 



Topaz is cut on a leaden wheel, and is polished on a copper wheel 

 with rotten stone. It is usually cut in the form of the brilliant or 

 table, and is set either with gold foil or ' or a jour.' The white and 

 rose-red are most esteemed. 



1 1 'ana, Manual of Mineralogy.) 



TOPA20LITE. [GARNET.] 



TORDY'LIUM (TopM\u>v of Dioscoiides), a genus of Plants 

 belonging to tho natural order l/mbetiifcra. The calyx consists of 

 ;"> awl-shaped teeth ; the petals obcordatc, with an indexed lobe, the 

 outer ones radiant. The fruit has a thick wrinkled margin ; the peri- 

 carps with very slender ribs ; the 3 dorsal ribs at equal distances, the 



2 lateral ones contiguous to the thickened margin or covered by it. 

 Tho species are herbs, with pinnate leaves and ovate leaflets deeply 

 toothed. The flowers are white. 



T. maximum, Great Hart-Wort, has a scabrous or hispid stem, 

 pinnate leaves, and lanceolate leaflets deeply notched and clothed 

 with fine bristly haira. It is a native of England. 



T. ojficinale, Officinal Hart- Wort, has a branched furrowed stem, 

 clothed with soft deftexed haira ; the leavea are pinnate, rough, and 

 hairy ; the leaflets ovate, cut, and crenate. The 2 outer petals aro 

 radiant, each with 2 very unequal lobes, which are sometimes 

 reddish. It is the 2eVcXi of Hippocrates (' Viet. Acut.,' 387) and of 

 Theoprastus (' Hist. Plant.,' 9, 18) ; the Seseli of Pliny (25, 8). 



TORENIA, a small genus of Plants of the natural family of Scro~ 

 pkulariacece, found in India, the tropical parts of Australia, and in 

 South America. T. Asiatica, a species found in almost every part of 

 India, is described by Rheede as having the juice of its leaves employed 

 as a cure for gonorrhoea on the coast of Malabar. 



TORILIS, a genus of Plants belonging to the natural order Umbel- 

 liferce. The calyx has 5 teeth; the petals are obovate, ernarginate, 

 the outer ones radiant and bifid ; the fruit slightly and laterally com- 

 pressed ; the carpel with bristly primary ridges, the secondary hidden 

 by the numerous prickles which occupy the interstices ; the flowers 

 white, those in the disc of the umbellules male and sterile. 



T. anthriscus has bipinuate leaves, the leaflets ovate, lanceolate, 

 inciso-serrate ; the umbels on long peduncles, the leaves of the invo- 

 lucre awl-shaped, the fruit covered with bristles ; the flowers are small, 

 reddish or white. It is a native of Europe and the Caucasus, and is 

 plentiful in Britain. 



T. infesta has an erect much-branched stem, the leaves bipinnate, 

 the leaflets deeply cut, ovate, lanceolate. The fruit is deuaely prickly, 

 the flowers small and reddish. It is found on fields and waste places 

 in Europe and Great Britain. 



T. nodosa has nearly sessile dense umbels, the outer carpels with 

 hooked bristles, the inner often covered with dense whitish shining 

 granulations ; the lower leaves are bipinuate, the upper ones pinnate ; 

 the leaflets deeply, narrowly, and uniformly pinnated. It is a native of 

 Europe and the Levant, and is plentiful in Britain. 



TORMENTILLA. [POTENTILLA.] 



TORPEDINID/E, the Torpedoes, a family of Fishes belonging to 

 the order Plagiostomi, and the aub-order Raiince. [RAIID.B.] 



Torpedo, the principal genus, was founded by Dumeril upon the 

 Raia Torpedo of Linnaeus, and some other species, distinguished by 

 their having the tail short and moderately thick, and the disc of the 

 body nearly circular, the anterior margin being formed by two pro- 

 duced portions from the head, which, inclining sideways, join the 

 pectorals : the space between the head, the pectoral fins, and the 

 biunchiic is occupied by small vertical hexagonal tubes, which are 

 filled with mucous matter, and largely provided with nerves from the 

 eighth pair. The situation of these honeycomb-like cells, which con- 

 stitute the electrical apparatus, is indicated on the upper surface by a 

 alight convexity on each side of the head. [ELECTRICITY OF OBQANIO 

 BEINGS.] 



Cuvier and Riaso consider that several species have been confounded 

 under a common name, and the latter of these authors has charac- 

 terised four species of Torpedo in his ' Histoire Naturelle de 1'Europe 

 Mcridionale.' They are 



1. Torpedo Narke, which he describes as being yellowish-red above, 

 and having five ocellated spots. 



2. Torpedo unimaculata. This species has the body above fulvous, 

 spotted with whitish spots, and one oblong ocellated spot in the middle 

 of the back. The tail is more elongated and slender. It is said to 

 have the electrical apparatus scarcely visible, and to give but very 

 slight shocks. 



3. Torpedo marmorata. Body flesh-coloured, and having brown 

 spots and sinuous markings, producing a marbled appearance : tail 

 thick, above rounded. 



4. Torpedo Qalvani. Body fulvous, immaculate, but margined with 

 black. 



Fleming refers the British Torpedo to the third of these species 

 Torpedo marmorata. 



TORPEDO. [TOBPEDINID.E.] 



TORS. By the natural weathering of rocks exposed to atmospheric 

 vicissitudes, the perishable parts are removed and the more resisting 

 portions remain. In rocks which manifest peculiar arrangements of 

 joints or natural divisions, the blocks and masses defined by their 

 intersections often appear in cubical, subcolumnar, and other charac- 

 teristic shapes. To masses more or less characteristic in figure, left 

 by the decay of surrounding parts in prominent situations, the name 

 of 'Tor' is applied in the granitic tracts of Devon and Cornwall. 



TORSK. [BBOSIMUS.] 



TORTOISES. [CHELOSHA.] 



TORTRIX, a genus of Serpents. [Boiox ; OPHIDIA.] 



TORULA. [MOULDINESS.] 



TOTANUS. [SCOLOPACIDA] 



TOTIPALMES, Cuvier's name for a group of Birds whose hind toe 

 is united together with the others in a continuous membrane. The 

 Pelicans, the Cormorants, the Frigate Birds, the Boobies, the Anhingas, 

 and the Tropic Birds belong to this group. 



