CARBONATE OF LIME. 43 



appropriately considered immediately after the phosphate of 

 lime, because it is the salt next in importance in the consti- 

 tution of the bones and teeth. In these structures it exists 

 intimately combined with the organic matter, under the same 

 conditions as the phosphates, and has analogous functions. 

 In the fluids it exists in small quantity, and is held in solu- 

 tion by virtue of free carbonic acid and the chloride of po- 

 tassium. 



The carbonate of lime is the only example of an inor- 

 ganic proximate principle existing uncombined, and in a 

 crystalline form, in the body. In the internal ear it is found 

 in this form, and has a function connected with audition. 



According to Robin and Yerdeil, it is possible that in 

 chemical analyses a certain quantity may come from a 

 decomposition by calcination of those salts of lime which 

 contain a combustible acid. 1 These authors give a table 

 of the quantity of this substance in various of the solids 

 and fluids of the body, from which we make the following 

 selections : 



Table of Quantity of Carbonate of Lime. 



Parts per 1,000. 



In Bone, Human (Berzelius). 113-00 



" " " (Marchand).. 102-00 



" " " ' (Lassaigne) 76'00 



" Teeth of Infant one day old ) / . . . 140-00 



" Teeth of Adult ( Lassaigne ! . . . 100-00 



" Teeth of Old Man, eighty-one years ) ( . . . 10-00 



" Urine of Horse (Boussingault) 10-82 



Origin and Discharge of Carbonate of Lime. Carbonate 

 of lime is introduced into the body with our food, held in so- 

 lution in water by the carbonic acid, which is always present 

 in small quantity. It is also formed in the body, particularly 

 in the herbivora, by a decomposition of the tartrates, ma- 



1 Op. tit., vol. ii., p. 247. 



