From Eric Kvaalen
You say that the grape juice in the 170-year-old champagne found in the Baltic Sea had not turned to acetic acid probably because of the cool temperatures and dark environment (25 April, p 20).
The reason the champagne had not turned to vinegar was that there was not enough oxygen. Every gram of acetic acid requires about half a gram of oxygen.
Les Essarts-le-Roi, France
