18 CHEMICAL PHYSIOLOGY. 



(d.) Shake up olive oil with a solution of albumin in a 

 test-tube = an emulsion. Examine it microscopically. 



(e.) Heat in a porcelain capsule for an hour or more some 

 lard mixed with plumbic oxide and a little water. The 

 fat is split up, yielding glycerin and a lead soap. 



(f.) Heat some lard and caustic soda solution in a capsule 

 to form a soap ; decompose the latter by heating it with 

 dilute sulphuric acid, and observe the liberated fatty acids 

 floating on the top. 



BONE. 

 14. A. Organic Basis of Bone. 



(a.) To Decalcify Bone. Place a small thin dry bone in 

 dilute hydrochloric acid (1 : 8) for a few days. Its mineral 

 matter will be gradually dissolved out, when the bone, although 

 retaining its original form, loses its rigidity, and becomes 

 pliable, elastic, and so soft as to be capable of being cut with 

 a knife. What remains is the organic matrix or ossein. Keep 

 the solution obtained. 



(b.) Wash the decalcified bone thoroughly with water, in 

 which it is insoluble. Boil it for a long time, and from it 

 gelatin will be obtained. Test the solution for gelatin 

 (Lesson I., 12). 



B. Mineral Matter in Bone. 



(a.) Examine a piece of bone which has been incinerated 

 in a clear fire. At first the bone becomes black from the 

 carbon of its organic matter, but ultimately it becomes 

 white. What remains is calcined bone, having the form of 

 the original bone, but now it is quite brittle. Powder some 

 of the white bone-ash. 



(b.) Dissolve a little of the powdered bone-ash in hydro- 

 chloric acid, observing that bubbles of gas (CO 2 ) are given 

 off, indicating the presence of a carbonate ; dilute the solu- 

 tion, add excess of ammonia = a white precipitate of phos- 

 phate of lime and phosphate of magnesia. 



