CHAP. V.] BONE. 101 



Bichat found that clavicles, which had been exposed for ten years 

 to the wind and rain at the cemetery of Clamart, presented, under 

 the action of acid, an abundant cartilaginous parenchyma. In an 

 old Koman frontal bone, dug up from Pompeii, Dr. Davy found 

 35-5 animal parts, and 64*5 earthy; and in a tooth of the mammoth, 

 30-5 animal, and 69*5 earthy. 



The animal part of bone consists of cartilage, with vessels, medul- 

 lary membrane, and fat. The cartilage is readily convertible into 

 gelatine, according to Berzelius, after three hours' boiling; and, when 

 this has been removed, there remain only four grains out of 100, 

 which may be considered to have been composed of blood-vessels. 



The earthy part of bone consists of phosphate and carbonate of 

 lime, with a small quantity of phosphate and carbonate of magnesia. 

 The phosphate of lime forms the principal portion of the earthy 

 part: in 100 parts of bone Berzelius found 51*04 of this salt. It 

 was discovered by Gahn, and the discovery announced by Scheele, 

 that bone-earth consisted of " phosphoric acid and lime." Accord- 

 ing to Berzelius, the phosphate consists of eight atoms of lime and 

 three atoms of phosphoric acid; but Mitscherlich regards it as 

 composed of three atoms of lime with one of phosphoric acid 

 (a tribasic salt) . It may be formed artificially by dropping chloride 

 of calcium into a solution of phosphate of soda. It appears as a 

 gelatinous precipitate, which does not crystallize, and is readily 

 soluble in acids. 



The existence of fluoride of calcium in bone was announced 

 many years ago by Berzelius ; but the observations of our friend, 

 Dr. G. O. Rees, throw considerable doubt upon this assertion. 

 Dr. Rees attributes the action of the supposed fluoric acid upon glass 

 to phosphoric acid in combination with water, which, if heated on 

 glass of inferior quality until it volatilizes, will act upon it with 

 considerable energy. The proportion of carbonate of lime to the 

 phosphate is small. According to Berzelius, there are 11*30 parts 

 in 100 of bone. 



We subjoin the following process, by which the qualitative 

 analysis of bone may be readily effected : 



In order to insulate the animal matter, digest the bone for some 

 days in muriatic acid diluted with about thrice its bulk of water; 

 the earthy constituents will thus be gradually removed, leaving a 

 semi-transparent cartilaginous tissue behind. 



The earthy matters are best examined by treating a portion of 

 burnt bone with nitric acid, diluted with from four to six times 

 its bulk of water ; brisk effervescence ensues, proving the presence 



