g2 - TLUORIC ACID. 



four parts. The first part will relate to the silicated fluoric 

 acid gas, and to the subsilicated fluoric acid - f the second to the 

 combinations of these acids, and of pure fluoric acid with am- 

 monia j the third to fluoboracic acid j and the fourth to its 

 ammoniacal salts. 



Sect. 1. On silicated fluoric acid Gas, and subsilicated fluoric 



Acid. 



Fluoric acid The facts which have already been published by MM. Gay 



gat requires Lussac and Thenard and others, appear to me to be sufficient 

 either silex oi* . _ ... , . t . . . 



boracic acid to to P r ove that pure fluoric acid has not yet been obtained in 



admit of that the gaseous state, and that silex, or boracic acid, is requisite 



that it may assume this form. Were more evidences neces- 



Common fl. a. sary . j could advance many in point. One circumstance only 

 £, is saturated. * . ' r . * 



I shall mention, proving that common fluoric acid gas is per- 

 fectly saturated with silex. I have preserved this gas, made 

 by heating, in a glass retort, a mixture of fluor spar and sul- 

 phuric acid, for several weeks over mercury in a glass receiver 

 uncoated with wax, without observing the slightest erosion t« 

 be produced.* 

 It is best obtain- This gas, with great propriety, has lately been called silicated 



ed by heating fl aor j c .Before I proceed to its analysis, I shall notice what 



fluor spar, * * ' 



finely powder- method I have found the best tor obtaining it. I have, for 



ed glass, and a cons jd C rable time, long before MM. Gay Lussac and 



together. Thenard's work was published, added to the mixture of fluor 



spar and sulphuric acid, a quantity of finely pounded glass, and 



have thus procm^d the gas with the greatest facility. The 



advantages of this addition are considerable. The retort is 



saved,, which otherwise, in less than one operation, would be 



destroyed j and a much larger quantity of gas is procured 



from the same materials, and with less trouble and less heat ; 



the action indeed at first is so powerful, that gas begins to 



come over before the application of heat is made, and a very 



gentle one only is required to continue its production. 



* The sides of the receiver indeed became obscure ; but this was not 

 from erosion, but from deposition, as appeared Crom the transparency 

 and polish of the glass being readily restored by slight friction. What 

 the deposition was, I am ignorant of. After several weeks it was so 

 Rifling, as to give only a slight degree of opacity to the receiver. 



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