28 VINEGAR, CIDER, AND FRUIT-WINES. 



By exposing ripe wine or the last-mentioned fluid at the ordi- 

 nary temperature of a room, and best in a plate covered by a 

 glass plate resting upon small wooden blocks to prevent the access- 

 of dust, the formation of a thin veil-like coating upon the surface, 

 which shortly covers the entire surface, will, in a few days, be 

 observed. The wine soon shows the characteristic odor and taste 

 of acetic acid, and in a few days assumes a somewhat darker 

 color and deposits a slight, brownish sediment consisting of decayed 

 vinegar ferment. In 14 to 21 days the fluid is entirely converted 

 into vinegar, i. c., it contains no more alcohol, but instead the 

 corresponding quantity of acetic acid. 



By exposing the vinegar thus obtained for a longer time to the 

 air, a thick white skin of mold may happen to form on the surface, 

 and, on chemically examining the fluid, the content of acetic acid 

 will be found steadily to decrease, the mold which is able to convert 

 the alcohol into water and carbonic acid possessing also the power 

 of forming the same products from acetic acid. 



The above-described process of the destruction of the wine and 

 its conversion into vinegar by a veil-like coating of the vinegar 

 ferment occurs most frequently ; a thick spume, the so-called 

 'mother of vinegar, may, however, also happen to form upon the 

 surface, a phenomenon to which we will refer later on. 



On examining under the microscope a drop taken from the 

 surface of the wine when the veil of vinegar ferment commences 

 to form, a picture like that shown in Fig. 2 presents itself. In 

 a somewhat more advanced stage the formations resembling 

 chains and strings of beads appear more frequently, and when 

 finally the development of the ferment is in full progress, it 

 appears as an aggregation of numerous single cells mixed with 

 double cells and many other cells strung together like beads. 

 The field of vision of the microscope is then completely filled 

 with a large number of colorless globules, which are present 

 either singly or in combination of twos, the formations resem- 

 bling chains or strings of beads occurring but seldom. In many 

 of the separately-occurring formations oval forms generally 

 slightly contracted in the centre are observed ; this contraction 

 indicates the place where the splitting of one cell into two new 

 cells takes place. By strongly shaking the fluid before viewing 



