USE OF BACTERIA IN THE ARTS. 



53 



power of growth. The production of the acid is 

 wholly dependent upon the growth of the bacteria, 

 and the secret of the successful vinegar manu- 

 facture is the skilful manipulation of these bac- 



FlG. 18. Bacillus acettcum, the bacterium which is the common 

 cause of the vinegar fermentation. 



teria so as to keep them in the purest condition 

 and to give them the best opportunity for growth. 

 One method of vinegar manufacture which is 

 quite rapid is carried on in a slightly different 

 manner. A tall cylindrical chamber is filled with 

 wood shavings, and a weak solution of alcohol is 

 allowed to trickle slowly through it. The liquid 

 after passing over the shavings comes out after a 

 number of hours well charged with acetic acid. 

 This process at first sight appears to be a purely 

 chemical one, and reminds us of the oxidation 

 which occurs when alcohol is allowed to pass 

 over a platinum sponge. It has been claimed, 

 indeed, that this is a chemical oxidation in which 

 bacteria play no part. But this appears to be an 



