THE MANUFACTURE OF VINEGAR. 459 



DISEASES. 



The most troublesome pest of vinegar factories is a minute nema- 

 tode, the Anguillula aceti or vinegar eel. It often develops around the 

 edges of the surface of the liquid in vinegar barrels and in the acetify- 

 ing columns and, if neglected, may cause putrefaction and spoiling of 

 the vinegar. Frequent and thorough cleaning of all apparatus, pasteuriza- 

 tion of liquids and light sulphuring of empty casks will prevent its devel- 

 opment. 



Microscopic mites are sometimes troublesome in neglected factories. 

 They can be reduced by the methods recommended for vinegar eels 

 and their entrance into the barrels or acetifying columns prevented by 

 painting a ring of turpentine or some viscid substance around each air 

 hole. 



Vinegar flies (Drosophylla cellaris) are often troublesome, but can be 

 excluded by proper screening of buildings and barrels. 



Bacteria other than acetic may develop in vinegar and some of them 

 may depreciate its quality. These have been little studied but the most 

 harmful seem to be anaerobic forms which develop in the lower parts of 

 the liquid protected from oxygen by the screening film of the acetic 

 bacteria. They produce butyric acid and putrid odors and, if neglected, 

 may completely spoil the vinegar. Sulphuring, fining, and pasteurization 

 are the remedies. 



Darkening or persistent cloudiness may be caused by oxidase as in 

 wine and cider and is controlled in the same way. A similar defect may 

 be caused by the tannic extractive matters of new casks or contact with 

 iron. Aeration followed by fining will remove the cause of the trouble. 



