104 THE INVISIBLE WORLD 



made, and on a small scale at that, only wild mi- 

 crobes from the air are used. But in manufac- 

 tories, where large quantities are made, the tanks 

 are arranged with pipes at the bottom. When the 

 vinegar is complete, it is drawn off through these 

 pipes, leaving the scum in the tanks. As the tanks 

 are filled with new liquor, this scum, or network 

 of the microbes used, rises to the surface, ready 

 to convert to vinegar the new liquor. Thus the 

 same colony, or colonies, of microbes, or their de- 

 scendants, are carried from batch to batch, from 

 year to year. This, long continued, must result in 

 culture, and furnish better workers. 



No doubt, too, a vinegar yeast may yet be made. 

 In its dry form kept in the home, by its use every 

 family may make its own vinegar as easily as its 

 own bread. 



