FLUORINE. 77 



Boracic acid is rarely found native, but is gener- 

 ally procured from the salt called borax. 



Borax is boracic acid united to soda, or a borate 

 of soda. This is the tincal brought from Asia puri- 

 fied. It is found at the bottom of certain lakes in 

 Thibet, and in China. The boracic acid has been 

 decomposed but lately, when it yielded to the ap- 

 plication of galvanic electricity by Sir H. Davy. 

 Borax is in the form of a powder of an olive colour. 

 It is combustible. 



Borax is much used as a flux in soldering metals, 

 and also for such stones as cannot be brought into 

 fusion by alkalies. 



FLUORINE. 



This name has been given, provisionally, to the 

 supposed base of the fluoric acid, which is ima- 

 gined to consist of fluorine and hydrogen. 



Thejluoric acid has hitherto resisted all the en- 

 deavours that have been made to decompose it 

 completely; and its real nature, therefore, con- 

 tinues uncertain. According to the present no- 

 menclature, it is now sometimes called hydro- 

 fluoric acid. 



Fluoric acid is obtained by adding sulphuric 

 acid to some pounded pure fluor spar, and ap- 

 plying heat. 



Fluor spar is that mineral well known by the 

 name of Derbyshire spar, because very abundant 

 in that county. It is employed for making vases 

 and other ornamental works. It consists of fluoric 

 acid and lime, or, perhaps, calcium, the metal of 

 lime, and is hence called also fluat of lime. The 

 sulphuric acid, having a stronger attraction for lime 



