226 BONES. 



the residue left thereon in some warm situation, to 

 dry, and when completely dried, rub off and weigh 

 the dry mass. The loss of weight will declare how 

 much lime and water were present in the bone-dust. 

 A good and dry specimen will lose by this treatment 

 one drachm at the most. 



Should the powder, after the vinegar has been 

 poured oiF, begin again to effervesce when fresh vin- 

 egar is added, it must then be made warm and 

 treated for the second time with a fresh quantity of 

 vinegar. Any admixture of earth, sand, etc. will- be 

 easiJy perceived by the eye in the residue (in the 

 event of its being necessary after a previous wash- 

 ing). In order to be assured of the presence of lime 

 in the decanted vinegar, it is simply necessary to 

 add thereto some sulphuric acid, whereby gypsum 

 or sulphate of lime is formed, which from its great 

 difficulty of solution falls as a white sediment to the 

 bottom. 



3. Test by Combustion. If half an ounce of bone- 

 dust in an iron spoon is suffered to stand over red- 

 hot coals until all the gelatine is burned away, and 

 the residue has again become white, the quantity of 

 the latter is learned by the loss of weight. Good 

 and dry bone-dust loses by this treatment full one 

 fourth of its weight ; that is, from half an ounce, at 

 least a drachm. When lime or other earthy sub- 

 stances are intermixed, less of course will disappear. 

 This test is, however, by no means so well adapted 

 for powdered bones as for bird-manure (pp. 193, 194), 



