New York AGRICULTURAL EXPERIMENT STATION. 161 
TABLE XVIII.—Errect or STERILIZATION UPON DECREASE OF 
Mauic AcIp. 
PERCENTAGE OF Maxic Acip IN APPLE JUICE AND VINEGAR KEPT AT 
AGE. 55° FB. 70° F. 85° F. 
Normal. Sterilized. Normal. Sterilized. Normal. Sterilized. 
Months. Exp. 17. Exp. 25 Exp. 20 Exp. 26. Exp. 21 Exp. 27 
MINES «, patersresc-< 0.41 0.5 0.51 0. 
Roreyete aieraiete eres’ 0.20 0.47 0.08 0.44 0.10 0.46 
Gales ciereea ones 0.16 0.44 0.03 0.39 0.10 0.45 
SJ slaliee telenavaet cts 0.16 0.41 0.01 0.29 0.05 0.43 
DUA rcnamcrse das 0.13 0.40 0.01 0.27 0.01 0.438 
BSD a sickens « —_— 0.26 0.01 0.23 0.01 0.38 
miatslalarevevevsiereie 0.00 0.17 0.00 0.32 0.00 0.35 
THE RELATION OF MALIC ACID TO THE IDENTIFICA- 
TION OF PURE CIDER VINEGAR. 
A common test for the identification of cider vinegar has been 
the formation of a white precipitate on addition of lead acetate. 
The formation of the precipitate is based upon the assumed 
presence of malic acid or malates in the sample tested. It is 
supposed that any vinegar made from apple juice contains malic 
acid, and that absence of malic acid, as indicated by no pre- 
cipitate with lead acetate, is regarded as a proof that the vinegar 
is from sources other than apples. This test has recently been 
fully discussed by Leach and Lythgoe,’ together with some 
modifications. 
In all of the vinegars made by us, we were able to get a white 
precipitate with lead acetate, even when no malic acid or malates 
was present. We are making a more detailed study of the rela- 
tion of malic acid and malates to cider vinegar. 
THE SOLIDS OF APPLE JUICE AND CIDER VINEGAR. 
The methods employed by us in determining the amount of 
solids was to heat about five grams of liquid on about 20 grams of 
pure quartz sand in a steam bath for six to eight hours. The re- 
sults are given in part in the following table. For full details, see 
the appendix: 
1 Am. Chem. Soc. 26:378 (1904). 
11 
