244 
ON THE OXIDES OF SULPHUR. 
acid, S + S, and of which many of the properties confound it 
with its analogous oxy-sulphuric acid, S-fO. 
M. Persoz succeeded in isolating the sulpho-sulphuric acid, 
by decomposing the sulpho-sulphate of lead by sulphuretted 
hydrogen. He filtered the liquor, and evaporated in vacuo, 
or on a stove in flat bottomed capsules, and thus obtained an 
acid, colorless, very dense, and decomposable by heat into 
sulphurous acid and sulphur. The sulpho-sulphuric acid 
decomposes in the cold the carbonates of soda, potassa, lime, 
magnesia and lead, it unites directly with bases, and form 
salts, which are to the oxy-sulphates as the seleniates are to 
the sulphates, or arseniates are to the phosphates. 
In contact with simple bodies, or compounds which have a 
direct action on sulphur or on sulphurous acid, the sulpho- 
sulphuric acid is always destroyed. Either in the cold or 
with the aid of an elevated temperature, it decomposes the 
salts formed with acids or bases of easy reduction. We can 
easily designate its properties and those of the sulpho-sul- 
phates, and forsee the phenomena to which it should give rise, 
by considering its analogy with the oxy-sulphuric acid and 
the properties of its elements, sulphurous acid and sulphur. 
Journ de Pharm. 
