98 WRITINGS OF JAMES SMITHSON. 



The mean of the six analyses quoted by M. Haiiy, in tlae 

 second edition of his Mineralogy, is 



Silica - - - 36.0 



Alumina - - - 52.3 



Fluoric acid - - 9.7 



98.0 



Deducting the oxygen from the metals, we have 



Silicium . . - 18.0 



Aluminium . . - 27.7 



Fluorine ' - - - 62.3 



98.0 

 Kryolite. 



It has been observed to diminish in fusibility during 

 fusion,* and it was in every respect probable, from what had 

 been seen with the foregoing bodies, that it would bo de- 

 composed in the fire. After being kept some time melted, 

 it afforded an alkaline solution, which, by exposure to the 

 air, became carbonate of soda, effloresced, effervesced with 

 nitric acid, and produced crystals of nitrate of soda. 



Fused on the platiua plate at the mouth of the tube ; a 

 copious deposit of silex collected in the tube ; and the bit 

 of logwood paper became very yellow. 



Kryolite heated in sulphuric acid on glass destroyed its 

 polish. 



1. Those experiments render it highly probable that flu- 

 orine will be expelled from every compound of it by the 

 agency of fire ; and consequently that we are now in pos- 

 session of a general method of discovering its presence in 

 bodies. In cases where a matter is infusible, and parts with 

 it with great difliculty, as in that of topaz, it may be required 

 to reduce it to fine powder, or to act upon it by some ad- 



* Haiiy's Mineralogy. 



