30 VINEGAR, CIDER, AND FRUIT-WINES. 



can exuberantly grow only upon the surface of the nourishing 

 fluids. By filling a bottle about four-fifths with wine, and after 

 allowing the vinegar ferment to develop, closing the mouth of the 

 bottle with the hand and submerging the neck of the bottle in 

 water, the fluid will be seen to rise for some time in the bottle 

 and then remain stationary. A determination of the content 

 of acetic acid immediately before the commencement of this ex- 

 periment, and a few days after, shows but a slight increase of 

 acetic acid, because after the. ferment has consumed the free oxygen 

 present in the bottle, the essential condition for its further develop- 

 ment is wanting, and it must cease its activity without, however, 

 perishing. It may here be remarked that the vinegar ferment, 

 like the majority of bacteria, possesses an extraordinary vitality ; 

 under unfavorable conditions it passes into a kind of quiescent 

 state, during which no perceptible increase of cells takes place. 

 It may remain in this state for a long time without suffering 

 destruction, and recommences augmentation and propagation in a 

 normal manner as soon as the conditions required for its nourish- 

 ment are again presented. 



The great rapidity of the augmentation of the vinegar bacteria 

 can be shown by an experiment of some importance to the prac- 

 tice. Pour into a shallow vat of about three feet in diameter a 

 fluid suitable for the nourishment of bacteria, and divide upon 

 the surface by means of a thin glass rod small drops of wine, upon 

 which the frequently mentioned veil has been formed. In a few 

 hours the entire surface of the fluid in the vat will be covered 

 with vinegar bacteria, spreading concentrically from the points 

 where the drops of wine have been distributed. From this it will 

 be seen that the cultivation of the ferment for the purpose of 

 manufacturing vinegar offers no difficulties, provided all con- 

 ditions required for the propagation of this organism be observed. 



B. Now*wkmy conditions of the vinegar ferment. 



.Through many observations and experiments made in practice 

 the conditions most favorable for the development of the vinegar 

 ferment, and for converting in the shortest time the largest quan- 

 tity of alcohol into acetic acid have been determined. These con- 



