New YorK AGRICULTURAL EXPERIMENT STATION. 137 
is desired. A further shortening of time may be realized by 
adding yeast to the apple juice, using one compressed yeast 
cake for five gallons of juice. (5) Management of acetic fermen- 
tation. When alcoholic fermentation is complete, draw off clear 
portion of liquid, rinse barrel, replace the clear liquid, add 2 
to 4 quarts of good vinegar containing some “ mother ” and keep 
at a temperature of 65° F. to 75° F. (6) Care of cider vinegar. 
When the acetic acid amounts to 4.5 per ct. of acetic acid 
or more, then fill the barrels as full as possible and cork tightly. 
INTRODUCTION. 
Some years ago our attention was called to the fact that cider 
vinegar made by farmers was found frequently to fall below the 
legal standard of the State, viz., 4.5 per ct. of acetic acid and 
2 per ct. of cider vinegar solids. It was commonly claimed 
that these vinegars were made from pure apple juice. The desire 
was expressed that a study should be made to ascertain why the 
ider vinegar made by farmers so frequently falls below the 
legal standard. The work described in this bulletin was under- 
taken primarily to throw some light on this question. Our 
original plan was to ascertain what results could be secured in 
making vinegar from pure apple juice under those conditions 
commonly employed by farmers. No attempt was made to study 
the rapid process of making vinegar by the use of so-called 
generators, since their use is greatly limited in ordinary farm 
practice. 
The investigation was extended to the consideration of addi- 
tional points of interest, such as (1) the composition of fresh 
apple juice obtained from different kinds of apples; (2) the 
changes in composition that the constituents of apple juice 
undergo (a) during alcoholic fermentation and (b) during acetic 
fermentation; (8) the conditions affecting these changes; (4) 
the destruction of vinegar on long standing. Somewhat similar 
work has been done at the experiment stations of Pennsylvania 
and Virginia and by the Bureau of Chemistry of the United States 
Department of Agriculture. 
Up to July, 1901, Dr. J. A. LeClerc, formerly assistant chemist 
here, now of the Division of Chemistry, United States Depart- 
