256 LACTIC ACID BACTERIA IN DISTILLING, ETC. 



this refreshing beverage, has yet been made. Possibly Saccharo- 

 bacillus pastorianus is concerned therein ; at present, however, 

 nothing definite can be stated on this point. 



A considerable amount of acidity is produced in the Belgian 

 beers known as Lambic, Faro, and Mars, beverages prepared by 

 spontaneous fermentation without any addition of yeast. The 

 boiled and re-cooled wort is placed in barrels which are only partly 

 filled, the empty internal space communicating with the external 

 air by a small aperture. Sufficient yeast-cells to set up fermenta- 

 tion are left adhering to the walls of the casks from the previous 

 fermentation, so that after a lapse of twenty-four hours an evolu- 

 tion of gas is already noticeable. In addition to alcoholic fermen- 

 tation, lactic, and subsequently also acetic, fermentation sets in. 

 L. v. D. HULLE and H. VAN LAER (I.) published in 1891 the 

 results of a chemical investigation of this matter. The more 

 important of these are tabulated below : 



The beverage is consumed after a storage period of three to 

 five years, and, in its matured condition, is known as "gueuse 

 Iambic" The acidity then amounts to about i per cent., and is 



masked by an 

 addition of sugar 

 immediately be- 

 fore drinking. 



A spontaneous 

 lactic fermenta- 

 tion also occurs 

 in the case of 

 ginger - beer (to 

 which reference 

 has already been 

 made in 64). 



The cells of Saccharomyces pyriformis are surrounded by the The preparation 

 cells of Bacterium vermiforme, the membranes of which Q f ^is foaming 

 are very much thickened and swollen. Magn. 680. (After . 



H. M. Ward.) acid beverage, 



which is largely 



consumed in England in the summer-time, is a very simple matter. 

 To a 10-20 per cent, solution of sugar are added a few pieces of 

 ginger and a couple of granules of the ginger-beer plant, the whole 



FIG. 52. Section through Ginger-beer plant. 



