l 56 Mr. Faraday on the mutual action of sulphuric acid 
gave a yellowish deliquescent salt, decomposed by heat, 
burning in the air, and entirely volatile. 
3. Analysis of the acid and salts. 
When solution of the pure acid was subjected to the voltaic 
battery, oxygen and hydrogen gases were evolved in their 
pure state : no solid matter separated, but the solution 
became of a deep yellow colour at the positive pole, occa- 
sioned by the evolution of free sulphuric acid, which re-acted 
upon the hydro-carbon. A solution of the barytic salts gave 
similar results. 
The analytical experiments upon the composition of this 
acid and its salts were made principally with the compound 
of baryta. This was found to be very constant in composi- 
tion, could be obtained anhydrous at moderate temperatures, 
and yet sustained a high temperature before it suffered any 
change. 
A portion of the pure salt was prepared and dried for 
some hours on the sand bath, at a temperature about 212 0 . 
Known weights were then heated in a platinum crucible to 
dissipate and burn off the combustible matter ; and the 
residuum being moistened with sulphuric acid to decompose 
any sulphuret of barium formed, was heated to convert it 
into a pure sulphate of baryta. The results obtained were 
very constant, and amounted to 41.714 of sulphate of baryta 
per cent, of salt used, equivalent to 27.57 baryta per cent. 
Other portions of the salt were decomposed by being 
heated in a flask with strong nitro-muriatic acid, so as to 
liberate the sulphuric acid from the carbon and hydrogen 
present, and yet retain it in the state of acid. Muriate of 
