PHOSPHATE OF LIME. 



75 



Fig. 1. 



but is intimately united with the animal matter of the tissues, like 

 a coloring matter in colored glass, so as to present a more or less 

 homogeneous appearance. It can, however, be readily dissolved 

 out by maceration in dilute muriatic acid, leaving behind the 

 animal substance, which still retains the original form of the bone 

 or cartilage. It is not, therefore, united with the animal matter so 

 as to lose its identity and form a new chemical substance, as where 

 an acid combines with an alkali to form a salt, but in the same 

 manner as salt unites with water in a saline solution, both sub- 

 stances retaining their original character and composition, but so 

 intimately associated that they cannot be separated by mechanical 

 means. 



In the blood, phosphate of lime is in a liquid form, notwithstand- 

 ing its insolubility in water and in alkaline fluids, being held in 

 solution by the albuminous matters of the circulating fluid. In the 

 urine, it is retained in solution by the bi-phosphate of soda. 



In all the solid tissues it is useful by giving to them their proper 

 consistence and solidity. For example, in the ena- 

 mel of the teeth, the hardest tissue of the body, it 

 predominates very much over the animal matter, 

 and is present in greater abundance there than in 

 any other part of the frame. In the dentine, a 

 softer tissue, it is in somewhat smaller quantity, 

 and in the bones smaller still ; though in the bones 

 it continues to form more than one-half the entire 

 mass of the osseous substance. The importance of 

 phosphate of lime, in communicating to bones their 

 natural stiffness and consistency, may be readily 

 shown by the alteration which they suffer from its 

 removal. If a long bone be macerated in dilute 

 muriatic acid, the earthy salt, as already mentioned, 

 is entirely dissolved out, after which the bone loses 

 its rigidity, and may be bent or twisted in any di- 

 rection without breaking. (Fig. 1.) 



Whenever the nutrition of the bone during life 

 is interfered with from any pathological cause, so 

 that its phosphate of lirne becomes deficient in 

 amount, a softening of the osseous tissue is the 

 consequence, by which the bones yield to external 

 pressure, and become more or less distorted. (Osteo-malakia.) 



After forming, for a time, a part of the tissues and fluids, the 



FIBULA TIED iir 

 A K^OT, after ma- 

 ceration in a dilate 

 acid. (From a speci- 

 men in the museum 

 of the Coll. of Physi- 

 cians and Surgeons.) 



