166 ACIDIFIABLE COMBUSTIBLES. 



of crystallized borax contain 4 grains of soda, 

 and 9 grains of water. The 6 grains wanting 

 to complete the whole weight, must represent 

 the boracic acid in the salt. The reader will 

 observe that the. original weight of the ingre- 

 dients put into the crucible (abstracting the 

 water) was 19 '5, consisting of 



10 grains anhydrous borax 

 9*5 grains fluor spar 



19-5 



The boracic acid of the borax, and the fluoric 

 acid of the fluor spar, had been driven off to- 

 gether, and these acids had been replaced by 

 sulphuric acid. Now, 9*5 fluor spar are com- 

 posed of 



7-0 lime 



2-5 fluoric acid 



7 of lime require 10 of sulphuric acid for satu- 

 ration. So that the sulphate of lime in the 

 residue amounts to 17 grains. The remaining 

 9 grains are sulphate of soda, composed of 



4 soda 



5 sulphuric acid 



9 



But the original weight of anhydrous borax was 

 10, and it obviously contained 6 grains of bora- 



