356 PHYSIOLOGICAL CHEMISTRY 



BONE ASH. 



Add dilute nitric acid, stir thoroughly and after the major portion of the ash has been 

 brought into solution add a little distilled water and filter. 



Residue I. Filtrate I. 



(discard) Add ammonium hydroxide to 



alkaline reaction and filter. 

 I 



Test for: 



1. Iron. 



2. Phosphates. 



V. ADIPOSE TISSUE 



Adipose tissue consists almost entirely of a mixture of fats. For 

 discussion and experiments see chapter on Fats, page 179. 



VI. TEETH 



TEETH are composed of enamel, dentine and cement. The cement 

 and dentine possess practically the same chemical composition as bone. 

 The enamel is the product of an epithelial tissue. It is the hardest 

 substance in the body and contains the smallest amount of water 

 (3-10 per cent) l According to Bertz 2 the enamel and dentine of human 

 teeth have the following percentage composition: 



Dentine Enamel 



38.18 CaO 50.22 



1.51 MgO 0.73 



30.24 P 2 O 5 40.69 



29.15 Organic substance 6.82 



It will be seen that calcium phosphate is the predominant constituent 

 of each. 



In dental caries there may be a pronounced loss of inorganic matter 

 and a corresponding gain in water and organic substance. These 

 analyses by Klihns 1 illustrate this change in percentage composition 

 Sound Teeth Dental Caries 



