BORON. 159 



1. It will be proved in the 15th chapter of Specific 

 this treatise, that the weight of an atom of fluo- fluo 



ric acid is 1 -25. Fluoboric acid gas may be ob- ac 

 tained by mixing together anhydrous boracic 

 acid and pulverized fluor spar, and exposing the 

 mixture to a red heat, in an iron tube or sim- 

 ply, by heating in a retort (as was first discovered 

 by Dr. John Davy), a mixture of 1 part boracic 

 acid, 2 parts fluor spar, and 12 parts sulphuric 

 acid. I collected a quantity of this gas, and 

 took its specific gravity two different times, and 

 obtained each time the very same result - 9 name- 

 ly 2-3709. 



On causing the gas under examination to be 

 absorbed by water, I observed that there was a 

 slight deposite of silica, indicating a mixture of 

 fluosilicic gas. By weighing this silica, I deter- 

 mined the volume of fluosilicic gas, and on de- 

 ducting it, the specific gravity of the fluoboric 

 acid gas was 2*38833. A careful examination 

 of the water containing the fluoboric acid gas, 

 enabled me to detect in it the presence of a 

 small quantity of sulphuric acid ; it was present 

 to the amount of 0*8 grain in the hundred cubic 

 inches of the gas. This being also deducted, the 

 specific gravity of pure fluoboric acid gas be- 

 came 2-3622.* 



* Dr. Davy found the specific gravity of this gas 2-3709. This is 

 the very specific gravity which I got and a little above the truth, owing, 

 doubtless, to a little fluosilicic or sulphuric acid, or both. 



