ACETIC ACID BACTERIA. 93 



In 1837-38 the view was also expressed by Turpin and 

 Kiitzing that the acetic acid fermentation is caused by a 

 micro-organism, which Kiitzing described and delineated 

 under the name of Ulvina aceti. Starting from this, Pasteur, 

 first in his treatise of 1864 and subsequently in his work, 

 Etudes sur le vinaigre, in 1868, furnished experimental proof 

 of the correctness of this view. He sowed a trace of the film 

 on a mixture of wine and wine vinegar, and thus obtained a 

 stronger development of acetic acid than was possible by 

 allowing the liquid to undergo spontaneous fermentation, 

 and on this he based a process for manufacturing vinegar. 

 He assumed that the acetic fermentation was caused by a 

 single species of micro-organism, which he called Mycoderma 

 aceti. His method consists in giving a large surface to the 

 liquid employed two parts of bright wine to one of wine- 

 vinegar and then sowing on the surface of the mixture a 

 young film consisting of " mother of vinegar." When the 

 temperature, the composition of the liquid, and all other 

 conditions are favourable, the formation of acetic acid will 

 proceed more quickly than in the older Orleans process. It 

 is claimed that the installation is cheaper and the loss of 

 alcohol scarcely greater than in the latter process. As early as 

 1879, E. C. Hansen discovered that at least two distinct species 

 are concealed under the name of Mycoderma aceti, which 

 now go by the names of Bacterium aceti and Bad. Pasteuri- 

 anum ; and now a whole series of species are distinguished. 

 To obtain the best results in this branch of industry, it is 

 again necessary to start with an absolutely pure culture of 

 a methodically selected species. The old Orleans process 

 still prevails in France. In this method the wine which is 

 to be converted into vinegar is placed in casks, half-filled, at 

 about 20 C., to which air has moderately free access. The 

 formation of acetic acid, as in Pasteur's process, takes place 

 in consequence of the liquid being gradually covered with a 

 film consisting of " mother of vinegar." In other countries 

 the " quick vinegar process " is employed, in which " the 

 goods " (diluted spirit mixed with vinegar) come into intimate 

 contact with air. To allow free access of air, the liquid is 

 broken up into small drops and distributed over a large surface 



