ANHYDROUS SULPHURIC AND SULPHUROUS ACID.S, MY 



The substance contains more sulphuric acid when it is not analysed 

 immediately after preparation, and after it has given forth some sul- 

 phurous acid ; less sulphuric acid, on the contrary, when this was the 

 case, and it therefore contained some free sulphurous acid. 



The result of these four experiments carefully conducted, according 

 as the substance was of newer or older preparation, was as follows : 



Weight of sulphate Percentage of 



of baryta obtained. sulphuric acid. 



'M22gr 72-90 



1-945 70-00 



2-554. 68-91 



5-021 67-68. 



The compound does not contain, therefore, as I suspected before the 

 experiment, sulphuric and sulphurous acids in the same proportions as 

 in the anhydrous hyposulphuric acid (S + S), but 2 eq. of sulphuric 

 acid to 1 eq. of sulphurous acid (2 S + S) which in 100 parts may be 

 stated as follows : 



Sulphuric acid 71*42 



Sulphurous acid 28-58 



100-00 



As the sulphurous is the least strong acid in the combination, and 

 may therefore be considered of the two as the base, according to this 

 view the compound may be considered as a neutral sulphate salt, in 

 which the sulphuric acid contains three times as much oxygen as the 

 base. 



