ANNALS 
OF 
PHILOSOPHY. 
JANUARY, 1819. 
ARTICLE I, 
Observations on new Combinations of Oxygen and Acids. 
By M. Thenard.* 
I OBTAINED these new combinations by treating the peroxide 
of barium with acids. Most of them are very remarkable, and 
deserving the attention of chemists. 
The first that I observed is the combination of nitric acid and 
oxygen. When the peroxide of barium, prepared by saturating 
barytes with oxygen, is moistened, it falls to powder without 
much increase of temperature. If in this state it be mixed with 
- seven or eight times its weight of water, and dilute nitric acid be 
ually poured upon it, it dissolves gradually by agitation with- 
out the evolution of any gas. The solution is neutral, or has no 
action on turnsol or turmeric. When we add to this solution 
the requisite quantity of sulphuric acid, a copious precipitate of 
pate of barytes falls, and the filtered liquor is‘merely water 
holding in solution oxygenized nitric acid. 
This acid is liquid and colourless, it reddens strongly turnsol, 
and resembles in almost all its properties nitric acid. 
When heated, it immediately begins to discharge oxygen ; but 
its decomposition is never complete unless it be kept boiling for 
-some time. It follows from this, that it would be difficult to con- 
centrate it by heat without altering it. The only method which 
succeeded with me was to place it in a capsule under the receiver 
of an air-pump along with another capsule full of lime, to exhaust 
* Translated from the Ann, de Chim. et Phys, viii. 306. (July, 1818.) 
Vou. XIII. N° I. A 
