>06 P^renck National Institute, 



ments and their own, appertain to causes which cannot in* 

 fluence the consequences to w hich they have led. 



To conclude: — On tliher hypothesis, the discovery of 

 Mr. Davy has produced an extremely active re- agent in 

 chemistry, and which must produce, on other bodies, effects 

 hitherto unknown. 



This new discovery gave rise, therefore, to very different 

 experiments, but which led to the s^me end: some had 

 for their objects to ascertain the action of the pile on the 

 other alkalis, on the earths, and generally on all the simple 

 non-metallic substances which we might suppose to be 

 oxides, like potash and soda. The object of the other? 

 was to decompose, by means of the new metals, substances 

 oxygenized, or supposed to be such, and particularly the 

 boracic, fluoric, and muriatic acids. 



We informed the public last year, that Messrs. Gay 

 Lussac and Thenard had succeeded in effecting the de- 

 composition of the first of these acids, and had ascertained 

 its radical. Since that time their inquiries have been di- 

 rected to the fluoric acid. 



They began by studying the physical and chemical pro- 

 perties of this acid more precisely than had been done by 

 any one else. The afiinity of water for this gas is extreme: 

 as soon as it is mixed with other gases which contain some 

 portions of this liquid, abundance of vapours is formed : 

 nevertheless, this gas cannot coijimunicate its expansive 

 force to water ; it cannot be dissolved nor gazify the 

 smallest quantity, and in its aeriform state it is absolutely 

 dry: but it is impossible to obtain this acid pure; it al« 

 ways retains some portions of those bodies with which it 

 has been in contact ; and in the labours which Messrs. 

 Gay Lussac and Thenard have undertaken on the subject 

 of this acid by means of potassiuiT? they made use of si- 

 liceous fluoric gas in preference, as not containing any 

 foreign body susceptible of being decomposed and obscuring 

 the results of the experiments. In the reciprocal action of 

 these two substances, there is a great absorption of fluoric 

 icid, very little hydrogen gas extricated, and a transforma- 

 tiori of the metal int® a solid matter the colour of which 

 i^ reddish browt). 



^Jessrs. Gay Lussac and Thenard regard this new com- 

 binatioa as a compound of potash, of silex, and of the ra- 

 dical of the fluoric acid; but they have not been able to 

 obtain this last substance in a separate state. '* It appears," 

 say they, (after several experiments which we cannot give 

 Jjere,) '' that when thjs radical is combined with potash 



only. 



