New York AGRICULTURAL EXPERIMENT STATION. 159 
of acidity in wine is caused by special bacteria, especially Micro- 
cocus malolacticus, which converts malice acid into lactic acid and 
a very small amount of volatile acids, while other acids such as 
lactic and acetic are not attached. In alcoholic solutions, a pro- 
duction of acetic acid may take place. When malic acid and 
sugar are present, an increase in acidity takes place, more acid 
being produced than last. Yeast acts comparatively slightly on 
malic acid. Acetic acid bacteria may also decompose malic acid. 
CONDITIONS AFFECTING MALIC ACID IN CIDER VINEGAR. 
The presence of malic acid or its salts in cider vinegar is a 
question of importance in relation to determining its purity and 
to this phase we will give attention later. 
(1) Effect of fermentation upon malic acid added to apple 
juice.—In order to study farther the disappearance of malic acid 
in apple juice, some special experiments (22, 23, 24, 28) were 
prepared. To some apple juice, containing 0.41 per ct. of 
malic acid, we added enough artificial malic acid to bring the 
amount to 1.02 per ct. Bottles of this apple juice containing 
malic acid were kept at different temperatures along with bottles 
of the same apple juice containing only malic acid normally 
present. In experiment 28 the apple juice had been sterilized 
and yeast added. In the following table we present the results 
of these experiments, carried on at 55°, 70° and 85° F.: 
TaBLE X VI.—Errect of FERMENTATION UPON Matic Acip ADDED 
To APPLE JUICE. 
PERCENTAGE OF Maric Acip In APPLE JUICE AND VINEGAR KEPT aT 
a 55° F. ADS 85° F. 55° F. (Sterilized) 
AGE. 
Malic Malic Malic Malic 
Normal. acid Normal. acid | Normal.| acid. Normal. acid — 
added. added. added. added. 
Months. Exp. 17./Exp. 22./Exp. 20./Exp. 23.|Exp. 21./Exp. 24./Exp. 25.| Exp. 28 
Al 02 0 cs 41 1.02 4 
Blveshisacursiscre 0.4 16 41 1.02 0. 2 0.41 1.02 
Ges teno og soog 0.20 0.69 0.08 -46 0.10 0.54 0.47 0.63 
Gr rrssiaicitrecan ae 0.16 0.61 0.03 0.36 0.10 0.54 0.44 0.39 
nidocoeu 6am pc 0.16 0.49 0.01 0.32 0.05 0.46 0.41 0.31 
by Setedoond Boe 0.13 0.30 0.01 0.28 0.01 0.38 0.40 0.28 
Niet gake aya ase ss 0.21 0.01 0.27 0.01 0.38 0.26 0.30 
OH odes onan aor 0.00 0.00 0.00 0.21 0.00 0.35 0.17 0.21 
