FABRICATION OF VINEGAR. 139 



Vinegar-Flies. 



Though, as far as known, the animals known as vinegar-flies 

 create no disturbance in the regular working of the factory, they 

 deserve mention because they appear wherever a fluid passes into 

 acetous fermentation. In wine cellars, not kept thoroughly clean, 

 these insects are frequently found on the bung-holes of the wine- 

 barrels, and in factories in which the manufacture of wine vinegar 

 is carried on according to the old system, they often occur in great 

 swarms. 



The vinegar-fly (Drosophila funebris, Meig) is at the utmost 

 0.11 inch long; it is especially distinguished by large red eyes 

 sitting on both sides of the head and meeting in front. The 

 thorax and legs are red, the abdomen which is provided with six 

 rings, is black, with yellow stripes. The wings are longer than the 

 body. The larva is white, has twelve rings, on the mouth two 

 black hook-like structures, and on the back part of the body four 

 warts two of which are yellow. In eight days the larva is trans- 

 formed into a yellow chrysalis. 



The collection of these flies in large masses can be readily pre- 

 vented by keeping the factory thoroughly clean and being espe- 

 cially careful not to spill any fluid. 



CHAPTER XIV. 



METHOD OF THE FABRICATION OF VINEGAR IN APPARATUS 

 OF SPECIAL CONSTRUCTION. 



To overcome the frequent disturbances in the working of a 

 factory not provided with suitable heating and ventilating ar- 

 rangements, several kinds of apparatus and methods have been 

 proposed. Most of these inventions were protected by patent, 

 but the relinquishment of the latter in a short time is the best 

 proof of their non-success in practice. A few of them are here 

 described, not because they are considered an essential pro- 

 gress in the fabrication of vinegar, but simply as illustrations of 



