TEETH. 



A Danilh pliyficiaii, named H.ngeriip, maintains in cer- 

 tain tlicfes that otic may licar with the teeth. 



As to animals, there are fome lilhcj whicli have teeth on 

 their tongues, as trouts ; others have them at the bottom of 

 the gull>-t, .IS the cod-li(h ; fome, as the great fea-dog or 

 (hark, called canis carcharias, iiave throe, four, or five rows 

 of teeth on tlie fame jaw ; tlic crocodile three, and thofe all 

 incifors ; vipers have two large crooked canine teeth, which 

 «re moveable, .md ordinarily lie flat, only being raifed when 

 they would bite ; and the rana pifcatrix, fea-frog, or fea- 

 devil, has whole rows of the like moveable teeth. The toad 

 and cuttle-filh have no teeth, and yet they can bite. See 

 ylnatomy of FisH. 



Teeth, Chemical Analyfis of. The teeth clofely re- 

 femble bone in their compolition.. The bodies conlifl of a 

 cartilaginous bafis, united with phofphate of lime, and fmall 

 proportions of other earthy falts. The enamel differs fo far 

 only from the bodies, that it contains no cartilaginous matter, 

 bnt confifts entirely of earthy fubftances. The teeth have 

 been often examined, and with various refults, according to 

 the ftate of chemical knowledge at the period of examina- 

 tion. We do not think it neceflary to give an account of 

 all that has been faid on the fubjeft, but fhall confine our 

 attention principally to the lateft and mod perfeft analyfes. 

 We (hall begin with the analyfis of Mr. Pepys : he found 

 the enamel of teeth compofed of 



Phofphate of lime - 

 Carbonate of lime - 

 Lofs and water 



78 



6 



16 



The bodies of the teeth, according to the fame chemift, 

 confift. of the following proportions. 



A much more complete analyfis, however, of the enamel 

 of teeth has lately been made by Berzelius. He gives the 

 following table of his refults, compared with the compofition 

 of the .bones of the fame animals. 



Tiius confirming a difcovery made many years before by 

 Morichini, an Italian chemift, namely, that the enamel of 

 teeth contains fluoric acid ; a circumftance which had been 

 called in quellion by later inquirers. 



FoJJile ivory and bone have been found by Fourcroy and 

 Vauquelin to retain proportions of animal matter, varying 

 from 45 to 15 per cent. ; a curious fatil, and highly illuftra- 

 tive of the powers of intimate mixture, or rather perhaps 

 cliemical union, in preventing the deftruftion of organic 

 fubftances. 



Tketh, jlrtificial, are thofe fet in lieu of natural ones, 

 whicli are wanting. See Teeth, Difeafes of. 



Teeth, Mark of, in the Manege. See M.-VRK and Eye 

 of a Bean. See alfo Teeth, infra. 



Teeth of Fijl^. See Anatomy of Fish. 



Teeth, in Rural Economy, little bones fixed in the jaws, 

 which ferve not only to reduce the food and nourifliment, 

 but lliew the age in fome animals. The horfe has forty- 

 teeth, including the tufhes, which are thus diftinguiftied. 

 Twenty-four are called grinders, being placed at the bottom 

 of the mouth, beyond the bars, twelve on each fide of the 

 channel, ^'^z. fix above, and fix on each fide. Thefe teeth 

 continue, and do not give place to new teeth in their 

 room, fo that they are of no ufe in diftinguiftiing a 

 horfe's age ; and they are fubjeft to wolves teeth. In re- 

 gard to the other fixteen, twelve of them are called in their 

 infancy milk or foal teeth, and the remaining four go by the 

 name of tujlxs. The twelve foal teeth are (hort, fmall, and 

 white, and are feated on the fore -part of the mouth, fix 

 above, and fix below : and thefe change and call, to give 

 place to others ; which, in procefs of time, become long, 

 large, and yellovvifh. 



Thefe new teeth are diftinguiftied by different names given 

 them, according to their putting forth ; and it is the manner 

 of their coming forth that gives the knowledge of the firft 

 years of a horfe's age. 



Of thefe twelve, four are caUed nippers, four middling 

 teeth, and four go by the name of corner teeth. The four 

 nippers are feated on the fore -part of the mouth, two above, 

 and two below. When a horfe iias put forth thefe, he is 

 concluded to be from two and a half to three years old. 



The middling teeth are placed near the nippers or ga- 

 therers, one above, and one below, on each fide of the jaws. 

 They come out and appear between three and a half and 

 four years. 



The corner teeth are placed ftill more forward in the 

 mouth, one above, and one below, on each fide of the jaws. 



They begin to ftioot between the fourth and the fifth 

 year, and are got above the gum at five years ; and when 

 furmounting the gum at that age, they become hollow, and 

 mark commonly till feven or eight years. By marking is 

 meant, that in the hoDow or cavity of the corner teeth a 

 little black fpeck is formed, which, from its refemblance, 

 is called the h\iA or eye of a bean, or the mark. But when 

 the horfe pafles fix, the cavity begins to fill, and the black 

 mark difappears by degrees ; yet this diminution of the 

 cavity and the mark continues from fix to feven and a half. 

 However, at eight years, the cavity is filled up, and the 

 black mark gone ; and the tooth is then full, and even as if 

 it had been ftiaved. It is then faid, that the horfe has raized, 

 which happens a little before the eighth year ; and after that, 

 the horfe does not mark ; fo that the fureft knowledge of 

 his age is then formed from his turtles. 



The turtles are placed beyond the corner teeth, upon the 

 bars, two on each fide below, without being preceded by 

 any foal teeth. The two under turtles cut fometimes at 

 three years, fometimes at three and a half, fometimes at 



four; 



