. 213. PHYSICAL PROPERTIES OF MINERALS. 813 



the Unctuons and Meagre toiich are used for distinguishing 

 certain friable minerals; and the Phosphorescence produced by 

 heat, is also employed in those minerals in which the natural- 

 historical properties properly so called are not observable. 

 It would be superfluous to dwell any longer upon these 

 subjects ; the more so since every Treatise on Mineralogy 

 may be consulted for all their particulars. 



