BONES AND BONE MANURES 127 



110. Examination of Bones and Bone Compounds. 



(a) Bones. — Two whole bones are weighed separately. 

 One is then placed in the muffle and ignited for an 

 hour at bright red heat ; when cold the residue is 

 weighed. This gives the proportion of water and 

 organic matter present. The residue is bone ash, and 

 will be required for (</). The second bone is immersed 

 for a day or two in dilute hydrochloric acid. The 

 mineral matter is dissolved out and leaves behind a 

 soft flexible ^\qq,& oi ossein. A portion of the solution 

 is evaporated with nitric acid in order to destroy all 

 organic matter, the residue taken up with dilute nitric 

 acid and tested for phosphoric acid with ammonium 

 molybdate. 



The ossein obtained from the second bone is 

 washed free from acid, dried in the oven, and weighed. 

 To a small portion is applied the xanthoproteic reaction 

 (see 9, b, p. 15), and another portion is heated with 

 soda-lime in order to show the presence of nitrogen. 

 The main bulk of the ossein is now boiled with distilled 

 water for some minutes, and then left in a beaker 

 covered with a clock-glass on the water-bath for a few 

 hours. On allowing to cool, the solution will set to a 

 jelly, owing to the formation of gelatine produced from 

 the bone collagen by the action of the water. The 

 gelatine will give a precipitate with tannic acid solution. 

 {b) Bone Meal and Steamed Bone Flour. — About 5 

 grams each of bone meal and steamed bone flour are 

 treated with dilute hydrochloric acid and the amount of 

 residual organic matter in each case noted. The fine- 

 ness of grinding of the samples should also be observed, 

 as on this largely depends the availability of the 

 manures. 



{c) Vitriolised Bones.— Sixty grams of bone meal 



