IV.] f^ATS — BONE. 31 



(k.) 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. 



BONE. 



2. (A.) Organic Basis of Bone. 



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

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

 dissolved out, and the bone, although retaining its original form, 

 loses its rigidity, and becomes pliable, 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. 



{!>.) Wash the decalcified bone thoroughly with water, in which it is in- 

 soluble ; place it in a solution of sodium carbonate and wash again. Boil it 

 in water, and from it gelatin will be obtained. Neutralise with sodium 

 carbonate. The solution gelatinises. Test the solution for gelatin (Lesson 

 II. 1). 



(c. ) Decalcify a small portion of a dry bone with picric acid. 



(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 hydrochloric 

 acid, observing that bubbles of gas (COg) are given off, indicating 

 the presence of a carbonate; dilute the solution, add excess of 

 ammonia = a white precipitate of phosphate of lime and phosphate 

 of magnesia. 



(<".) Filter, and to the filtrate add ammonium oxalate = a white 

 precipitate of oxalate of lime, showing that there is lime present, 

 but not as a phosphate. 



('/.) To the solution of mineral matters 2 (A.) {a.) add acetate 

 of soda until there is free acetic acid present, recognised by the 

 smell ; then add ammonium oxalate = a copious white precipitate 

 of lime salts. 



(e.) Use solution of mineral matters obtained in 2 (A.) (a.) Render a part 

 alkaline with NH4H0 = copious precipitate, redissolve this in acetic acid, 

 wliich dissolves all except a small flocculent residue of phosphate of iron 

 (perhaps in part derived from the blood of bone). Filter ; use a small part to 

 test for phosphoric acid and the rest for calcium and magnesium (Filtrate A.). 



(i.) The undissolved flocculent precipitate is waslied and dissolved in a few 

 cc. dilute HCl. and the presence of iroji oxide proved by adding ferrocyanide of 

 potassium ( = blue), and that of phosplwfic acui by molybdate of ammonium 

 (see " Urine"). 



