BACTERIA. 59 



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. The installation is claimed to be cheaper, 

 and the loss of alcohol not greater at all events not to any 

 appreciable extent than in the last-named process. Yet, as 

 far as the author has been able to learn, PASTEUR'S process is 

 never employed. The uncertain results obtained may have 

 been due to the fact that the composition of the nutritive 

 liquid varies, and, especially, that the bacterial culture was not a 

 pure culture, and might, therefore, also contain varieties of 

 bacteria which possessed different properties, required different 

 conditions for their growth, and, consequently, would give 

 different products in varying quantities. This will hold good 

 even in those cases in which the composite culture consists 

 only of varieties which can produce vinegar. As early as 

 1879 HANSEN discovered that at least two distinct species are 

 hidden under the name of Mycoderma aceti, which now go 

 by the names of Bacterium aceti and Bad. Pasteurianum ; and 

 now a whole series of species are distinguished. To obtain the 

 best results in this branch of industry it is likewise 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 30 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 German " quick 

 vinegar process " is employed, in which the growth of bacteria, 

 suspended in diluted spirit mixed with vinegar, is accelerated 

 by coming into intimate contact with the air. This is brought 

 about by allowing free access of air, by dividing the liquid 

 into small drops, and distributing these over a large surface 

 (beechwood shavings). The nature of the micro-organisms 

 taking part in this manufacturing process has not yet been 

 investigated. The use of pure-cultivated and methodically 

 selected cultures is likely to be adopted before long. 



