22 Life and Health 



animal matter than in more advanced life, and are there- 

 fore more liable to bend than to break ; while in old age 

 they contain a greater percentage of mineral matter, and 

 are more easily broken. 



Experiment 8. To show the mineral matter in bone. Put a large 

 soup bone on a hot, clear fire, and let it remain there until it is at a 

 red heat. At first it becomes black from the libera- 

 tion of the carbon of its organic matter, but at last 

 it turns white. Let it cool. The animal matter has 

 been burnt out, leaving the mineral, or earthy part, 

 a white, brittle substance of exactly the same shape. 



Experiment 9. To show the animal matter in 

 bone. Add one-fourth of a cupful of muriatic acid 

 to a quart of water, and place the mixture in a wide- 

 mouthed bottle or glass fruit jar. Scrape and clean 

 FIG. ii. a chicken's leg bone, part of a sheep's rib, or any 



The Fibula tied other small slender bone. Soak the bone in the acid 

 into a Knot mixture for a few days, adding a little more acid 

 after the Min- f rO m time to time as the effervescence seems to 

 eral Matter has have cease d T h e mineral matter is slowly dis- 

 been dissolved solved and th bo although retaining its original 

 by Acid. . .... 



form, loses its rigidity and becomes pliable, and so 



soft as to be readily cut. If the experiment be carefully performed, 

 a long, thin bone may even be tied into a knot. 



33. Physical Properties of Bone. A bone is not the 

 same in its structure in all parts. If we take a leg bone 

 of a sheep, or a large end of beef shin bone, and saw it 

 lengthwise in halves, we see two distinct structures. There 

 is a compact tissue which seems hard and solid as stone 

 forming the outside shell, and a honeycombed lighter 

 tissue inside having the appearance of a beautiful trellis- 

 work of thin bony plates. This spongy, or cancellous tissue 

 occurs in the interior of bones, and chiefly at the joint 

 ends. Not only is the cancellous tissue strong and light, 

 but it has another advantage, that of breaking shocks. 



