202 BONES. 



ammonia (hartshorn), the dissolved phosphate of 

 lime falls to the bottom as a white powder. 



3. If a bone is heated for some hours in a crucible, 

 which is well covered with a piece of tile, it assumes 

 a black color, and is changed into hone-coal (bone- 

 black, ivory-black). As the air, in this case, has no 

 access to the bone, only an imperfect combustion, or a 

 charring of the gelatine, ensues, and the carbon (coal) 

 remains behind, mixed with the bone-earth, which is 

 not volatilized by the fire. In two ounces of bone- 

 black so prepared, only half to three quarters of a 

 drachm of coal is obtained ; but this, on account of 

 its minute state of subdivision, possesses such a 

 strongly purifying and bleaching power, as to be 

 employed in sugar refineries for the purpose of de- 

 priving brown sugar of its color. This coal, after 

 having performed service as a means of purifying 

 sugar, is used also as a manure, under the name of 

 sugar refuse, 



4. In the preceding experiment the constituents 

 of the gelatine are converted by the heat into gases, 

 which are distinguished by a very disagreeable odor, 

 and escape. To observe this more plainly, fill the 

 bowl of a common clay tobacco-pipe three quarters 

 full of chipped bone, close the remaining space with 

 stifly-kneaded clay, and place the bowl with its con- 

 tents in glowing coals. The vapors escaping from 

 the extremity of the pipe-stem may be ignited, for 

 they contain illuminating-gas ; they possess, more- 

 over, a pungent odor, and quickly turn a strip of red 



