178 FLUORIC ACID AND ITS COMPOUNDS. 



succeeded once in obtaining a complete con- 

 densation by mixing three volumes of the acid 

 gas with four volumes of the alkaline gas ; but 

 a repetition of the experiment did not succeed. 



SECT. III. 



OF THE ATOMIC WEIGHT OF FLUOBORIC ACID. 



MESSRS. Gay-Lussac and Thenard discovered 

 another compound gas, one of the ingredients of 

 which is fluoric acid, and the other boracic acid. 

 It has been generally distinguished by the name 

 ofjluoboric acid. They procured it by exposing 

 a mixture of fluor spar and anhydrous boracic 

 acid to a strong heat. The gas came over in 

 abundance, and was collected over mercury. 

 Dr. Davy, to whom we are indebted for an ex- 

 cellent set of experiments on this gas, procured 

 it by mixing together one part of anhydrous bo- 

 racic acid and two parts of fluor spar in a retort, 

 and pouring twelve parts of sulphuric acid on 

 the powder. When the heat of a lamp is ap- 

 plied, the gas comes over, and it must be re- 

 ceived over mercury. I prepared the gas by 

 Dr. Davy's method, not having been provided 

 with an apparatus similar to that employed by 

 the French chemists ; but I found the process 



