258 ANALYSIS OF HUMAN BONES. 



phate of ammonia resulting from the precipitation of phos- 

 phate of magnesia b}' volatile alkali. On evaporating to 

 dryness, and slightly calcining the residuum, this earth is 

 obtained of a black colour, and iu a floccnlent form ; but 

 ,by calcination at a red heat it assumes all its characteristics. 

 We suspected at first, that the silex and alumine might 

 have been taken up by the phosphoric acid from the stone 

 vessels we used : but we have since satisfied ourselves, by 

 several decisive experiments, that they actually existed in 

 the bones. 



" Though we have already given an account of the succes- 

 sive operations necessary for obtaining the different substances 

 juiit mentioned, in the Anncksdu Museum (THistoire naturelle 

 for September, 1908, we shall repeat them here, to form a 

 complete whole, and as a guide to those who would go 

 through the same examination. 



M'iibod of" 1. Let the bones, calcined and powdered, be decomposed 



iirtayajs. j^^, an equal quantity of sulphuric acid. 



2. Dilute the first mixture with twelve parts of distilled 

 water; pour the whole on a piece of cloth, leave t^he sul- 

 phate of lime to drain, and wring it out strongly. 



3. Filter the liquor through paper, and precipitate it by 

 ammonia; filter it a second time, wash the precipitate, and 

 set tlie liquor aside. 



4. While the precipitate is still wet, treat it with sulphuric 

 acid, taking care that the acid is a little in excess: filter 

 afresh, wash the yjrecipitate, and add the liquor to the for- 

 mer : No. 3. Repeat this operation, till the precipitate 

 formed by the ammonia dissolves entirely in the sulphuric 

 acid ; wliich will show, that it no longer contains any sen- 

 sible quantity of lime. 



By this series of operations the whole of the lime in the 

 bones will be converted into sulphate of lime, which, being 

 but little soluble, will be separated from the liquor; in 

 which will be found the phosphoric acid, with the sulphates 

 of magnesia, iron, manganese, and alumine, 



5. Theee substances, being separated from the sulphuric 

 acid by ammonia, are to be treated with caustic potash, 

 which will attract the sulphuric and phosphoric acids, evolve 

 the ammonia, and dissolve the alumine. 



j^'fi.'.Prccipitate the alnmine from the alkaline solution by 



meani. 



