3o6 ACETIC FERMENTATION 



the employment of selected pure culture ferments is not yet regarded as a funda- 

 mental rule, everything being still left to the mercy of chance. 



As every re ider will be aware, there are two different methods of making 

 vinegar. In one of them wine forms the raw material, this method being 

 known as the Origins j.roc.'ss, from having long been extensively carried on in 

 that locality. There (as elsewhere) the work is still performed in the same 

 manner as it was centuries ago, as follows: A number of oaken casks, each of a 

 capacity of some 55 gallons, are arranged in rows in a chamber maintained at a 

 constant temperature of 1 8 to 22 0. In the upper part of the front end (head) 

 of each cask a circular aperture (a few cm. in width) is provided, through which 

 the cask can be filled or emptied, and which is generally kept closed, whilst near 

 it is a very small hole (vent) always left open for the admission of air. In 

 normal work each cask is about half full. Before setting a new cask in work, 

 it is scalded out several times with steam or hot water, in order to extract the 

 sap from the wood, and is then "soured" by impregnating it with good, boiling- 

 hot vinegar. About i hi. (22 galls.) of good clear vinegar and 2 1. (0.44 gall.) 

 of wine are then placed in the cask, another 3 1. of wine being added at the end 

 of eight days, 4 to 5 1. more after the lapse of another week, and so on until the 

 cask contains about 180-200 1. (40-44 galls.). Then, for the first time, vinegar 

 is drawn from the cask, and in such quantity that about 22 galls, are left 

 behind in the vessel. From that time the cask (" mother ") is in continuous 

 use, 10 litres (2.2 galls.) of vinegar being withdrawn every week and replaced 

 by an equal quantity of wine. The " mother" casks may remain in work during 

 six or eight years without interruption, but at the end of this period they will 

 contain such a considerable accumulation of deposited yeast, tartar and mother 

 of vinegar, as to necessitate their being emptied and cleansed. A skin, known 

 as vinegar-flowers or mother of vinegar, and composed of acetic acid bacteria, 

 develops on the surface of the liquid, and the manner and luxuriance of its 

 growth enables the operator to judge the progress of the fermentation. How- 

 ever, at the outset the growth proceeds very slowly, since the wine employed 

 mostly contains but very few of these bacteria. Consequently an opportunity 

 is afforded for the development of rapid-growing injurious organisms, chiefly 

 certain budding fungi, which consume the acetic acid. The aerobic " vinegar 

 eels " also make their appearance. To obviate this source of loss, PASTEUR (XV.), 

 in 1862, proposed that, instead of waiting until the acetic acid bacteria in the 

 wine had increased sufficiently to form a protective skin of " vinegar-flowers," 

 the necessary ferment should be cultivated in small vessels, the skin thus 

 obtained being then carefully transferred in pieces of sufficient size, by the aid 

 of a wooden spatula, on to the surface of the wine to be soured, which was 

 placed in shallow open vats. This process was adopted by Breton-Lorion of 

 Orleans, in particular, and would be suitable for general application if the 

 presence of not more than one species of acetic ferment could be thereby ensured. 

 This, however, is not the case, and it is purely a matter of chance whether the 

 skin prepared by cultivation beforehand is composed of beneficial or injurious 

 organisms. According to circumstances, there may be present several very 

 different species with divergent properties, faculties, conditions of vitality and 

 metabolic products. By reason of this uncertainty alone, the Pasteur method is 

 liable to produce very irregular results, and may, on occasion, actually give rise 

 to losses; and, as a matter of fact, it is just on this account that the method has 

 been abandoned both in France and Germany, where it was introduced by 

 E. WURM (I.). Up to the present it does not appear that any one has attempted 

 to work with really pure cultures. 



In the second method actually employed for making vinegar, spirit is used 

 instead of wine. This method has been evolved from that originally prescribed 



