184 VINEGAR, CIDER, AND FRUIT-WIXES. 



transmitting ferment to the fluid to be fermented has for a long 

 time been in use in the fabrication of beer and of alcohol. In the 

 brewery the wort, and, in the distillery, the mash, is brought into 

 fermentation by " setting" it with yeast, L e., alcohol ferment is 

 intentionally added. The "setting of wine" with vinegar fer- 

 ment is the only correct method for the preparation of vinegar 

 from wine. 



Before entering upon a description of this process it will be 

 necessary to discuss a few undesirable phenomena which may ap- 

 pear in the conversion of wine into vinegar. A thick white skin 

 having the appearance of a ruffle may frequently form upon the 

 surface of the wine set for acetification, the wine in this case becom- 

 ing constantly poorer in alcohol, but not sour. Sometimes the pre- 

 viously steady increase in the content of acid in the wine to be aceti- 

 fied suddenly ceases and a very rapid decrease in the content of aeid 

 takes place, the development of the white skin upon the surface 

 being also in this case observed. 



The formation of this white coating upon the surface is due to 

 the development of mold ferment whose cells in a short time 

 augment to such an extent as to form a thick membranous layer, 

 the folds being formed by the superposition of the cells. The 

 mold ferment has the property of converting alcohol as well as 

 acetic acid into carbonic acid and water, and consequently if it 

 settles upon wine the latter becomes poorer in alcohol, and if upon 

 wine containing already a certain quantity of acetic acid the 

 latter is also decomposed. The mold ferment requires, however, 

 considerable quantities of nitrogenous combinations for its vigor- 

 ous development, and, therefore, readily settles upon young wine 

 which contains a large quantity of albuminous bodies in solution. 

 This fact explains the reason why young wine is seldom attacked 

 by acetous generation, but it readily becomes moldy, and, conse- 

 quently, cannot be recommended as material for the fabrication of 

 vinegar except the albuminous substances be first separated by 

 heating the wine to 140 F., which is best effected by means of 

 the apparatus shown in Fig. 39, p. 149. 



Another serious annoyance in the fabrication of wine-vinegar 

 is the appearance of vinegar eels, which, if not checked in time, 

 may lead to the interruption of the entire process. These ani- 



