New York AGRICULTURAL EXPERIMENT STATION. 155 
While these few results are not at all conclusive, they suggest 
that at low temperatures the clear liquids form acid more quickly, 
while at higher temperatures there is little practical difference. 
In no case did any of these vinegars show signs of deterioration 
during the 44 months of the experiment. In these particular 
cases, the sediment did not appear to carry forms of living 
organisms that prevented the ultimate formation of acid in good 
quantities. 
LOSS OF ACETIC ACID IN VINEGAR ON STANDING. 
Reference has been made to the fact that cider vinegar occa- 
sionally suffers deterioration on standing a long time and loses 
more or less completely its sourness. Some cases have been 
brought to our attention by farmers in which all acetic acid had 
disappeared and the liquid was no longer vinegar. This condi- 
tion is well illustrated in the experiments numbered 17, 18, 22, 
30, 31, 32, 33, 34 and 35. In the set of experiments started in 
1900, including those numbered 30 to 35, all lost their acid and 
in most cases completely, while in some the reaction was actually 
alkaline. 
This disappearance of acetic acid in vinegar is due to forms of 
fermentation that decompose the acetic acid, changing it into 
other substances, largely water and carbon dioxide. Several dif- 
ferent organisms are known that decompose dilute acetic acid. 
Among these Pasteur showed that the acetic acid bacteria them- 
selves, after changing alcohol into acetic acid, attack the acetic 
acid found and destroy it, especially when there is a free access 
of air to the liquid. Browne® made a study of a sample of deteri- 
orated vinegar and found the injurious organism to be Bacterium 
cylinum, which, while an acetic-acid-forming bacterium, was 
different in this case from the bacteria that had produced the 
acetic acid. 
Bertrand’ attributes the inoculation of Bacterium xylinum to 
the small vinegar flies that are so common in places where fer- 
mentation of fruit juices is taking place. 
In our work it was noticed in most cases, where the vinegar 
had lost its acid, that the “ mother” was black and the liquid 
itself abnormally dark in color. In experiments 17, 18 and 22, 
6Annual Report of the Pennsylvania State College for 1901-1902, p. 156. 
7Comptes Rendus, 122: 900, 
