1911 Encyclopædia Britannica/Carbonic Acid

CARBONIC ACID, in chemistry, properly H₂CO₃, the acid assumed to be formed when carbon dioxide is dissolved in water; its salts are termed carbonates. The name is also given to the neutral carbon dioxide from its power of forming salts with oxides, and on account of the acid nature of its solution; and, although not systematic, this use is very common.