BORON. 163 



of boracic acid. This number comes near 3, 

 which we have seen to be the true atomic weight 

 of boracic acid; and serves still farther to 

 show that the experiments from which I de- 

 duced 2*75 to be its atomic weight, were in- 

 accurate. 



5. Boracic acid, as it is usually obtained from 

 borax by precipitation, is in white opaque scales, 

 containing a considerable quantity of water. 

 Sir H. Davy, Berzelius, and myself, endeavoured 

 to determine the quantity of water present in 

 these scales. The experiment is attended with 

 a good deal of difficulty. I varied my method 

 after I became aware that my first experiments 

 were wrong, and endeavoured to prevent any 

 volatilization of boracic acid, by mixing the 

 hydrous acid with a considerable quantity of 

 protoxide of lead. But I still found the loss of 

 weight to amount to 44 per cent. The follow- 

 ing are the results of Davy, Berzelius, and my- 

 self. The hydrate is composed of 



Real acid 57 . . 56 . .56 

 Water 43 . . 44 . .44 



I am satisfied that Davy came nearest the truth, 

 though I have not been able to discover the 

 cause of my own failure. If the hydrous acid 

 contain two atoms of water united to one atom 

 of acid, its constituents should be 



L2 



