112 MR. E. SCHUNCK ON THE ACTION OF 



together with particles of ferment carried up by them, a 

 thick scum on the surface of the liquid, resembling the froth 

 OD the surface of fermenting beer. As far as the evolution of 

 gas, however, was concerned, the action did not seem to be 

 quite as energetic as what would have been produced by the 

 action of ordinary yeast on sugar. During this stage of the 

 fermentation, a slight vinous odour might be perceived near 

 the surface of the liquor. After a few days the liquid began 

 to acquire a decided acid reaction, which was first indicated 

 by the colour of the ferment changing from purple to brown. 

 Very soon litmus paper began to be strongly reddened by it. 

 After some time the disengagement of gas ceased, and the 

 particles of ferment all sank to the bottom, leaving a clear, 

 yellowish supernatant liquid. The latter, however, on stand- 

 ing exposed to the atmosphere, seemed constantly to acquire 

 more and more acid properties; and after several weeks' expo- 

 sure, it was generally found to have a strongly acid taste and 

 smell like that of sour beer. I have generally allowed the 

 mixture to stand for several months, usually from summer to 

 winter, as I imagined that long standing promoted the for- 

 mation of one of the acid products, whose properties I shall 

 presently describe. Nevertheless, during this lapse of time 

 little or no mould was formed on the surface of the liquor, 

 no decidedly putrid smell was emitted, nor did the mass ever 

 seem to be particularly attractive to insects, or to breed 

 worms or larvae, at least none that were visible to the 

 naked eye. 



Now the products of this process of fermentation are of 

 three kinds: gaseous, liquid, and solid. I shall describe them 

 in the order mentioned. For the purpose of examining the 

 gaseous products, 2 lbs. of cane sugar were dissolved in 

 water, and the usual quantities of ferment and lime water 

 were added. After two days the mixture was found to be in 

 a state of active fermentation. A portion of it was then in- 

 troduced into a capacious bottle, leaving a small space at the 



