214 AGEICTJLTUEAIi AND INDUSTRIAL BACTERIOLOGY 



any considerable proportion of the acetic acid into carbon 

 dioxide and water, thus weakening the vinegar. For this 

 purpose casks or barrels may be partly filled with cider or 

 wine (preferably not more than one-half to two-thirds full 

 at the most), placed upon their sides and an opening left 

 for ingress of air. This opening should be closed with a 

 layer of cheesecloth or gauze to prevent insects from gain- 

 ing access. The process may be considerably hastened by 

 adding some good vinegar or some "mother of vinegar," 

 or best of all a- culture of the most suitable acetic bacteria. 



Washings from honey extractors and improperly ripened 

 honey may be manufactured into vinegar of very fair 

 quality by the same process. 



Many housewives in recent years have manufactured 

 vinegar in small quantities in the home by making use of 

 what have come to be known popularly as "vinegar bees." 

 These consist of dried, brownish, gelatinous lumps, varying 

 from the size of a pinhead to a bean. "When examined 

 microscopically they are found to consist of a gelatinous 

 mass of bacteria with many yeasts. When dropped into a 

 solution of sugar, the yeasts at first multiply rapidly and 

 bring about alcoholic fermentation. The bacteria soon 

 begin to develop, produce the characteristic acetic film, and 

 transform the alcoholic solution into vinegar. Homemade 

 vinegar of this type is often prepared by the use of fruit 

 juices, syrups that have been used in preserving fruits, 

 from molasses, or even from cane sugar or honey. Some 

 samples of vinegar of fair quality are prepared in this way, 

 though usually the vinegar is not as good as that secured 

 by the fermentation of cider. In most instances the acid 

 content is relatively low, rarely reaching 4 or 5 per cent. 

 It should not be used, therefore, for preservation of food 

 materials requiring a high percentage of acid. 



Commercial Manufacture of Vinegar. — The best commer- 

 cial vinegars are manufactured from cider and wine. 



