248 Ohservaltons on Vermentation. 



This addition is particularly necessary when the ferment- 

 ina; principle is in excess in the must, as happens in cold 

 countries and moist soils, where they make only weak sour 

 v/ine, very suscepiilile oF decomposition on account of the 

 superabundance of the fermentable principle. On the con- 

 trary, this principle is sometimes prejudicial by its deficiency 

 in the juice of some extremely sweet scrapes. It is then 

 proper to employ the methods proposed, above, when there 

 is an excess of sugar. 



On tlie Progress of the Vinoii.s Fcrmevtntlon. 



After bavins; treaited of the various causes which influence 

 the vinous fermentation, M. Chaptal shortly traces the pro- 

 gress of this operation. He speaks of the intestuie motion 

 which gives rise to the formation of the crust called ckapeait 

 de la vendii^e; he makes mention of the heat and the dis-, 

 engagement of carbonic acid gas, which are constantly ob- 

 servable, and he points out the results of the operation. I 

 shall say a word or two on the most remarkable of these. 



1. Of the Disevgagement of Carbonic Acid Gas. 



The production of carbonic acid gas during the vinous 

 fermentation, is caused by the reaction of the elements of 

 the SLisiar already altered by the ferment, and in which there 

 is a subtraction of carbon and oxygen. The gas first pro- 

 duced is dissolved in the fluid; but as the formation of it 

 fi^oes on, an effervescence takes place from the disengage- 

 ment of the gas, which soon spreads into the atmosphere, 

 and mephitizes it, if the precautions pointed out by M. 

 Chaptal are not employed. 



If while the wine is yet fermenting it is inclosed in well 

 slopped bottles, the carbonic acid gas is dissolved in the 

 wine until this is saturated ; ihen the fermentation is stop- 

 ped by the pressure of the a;as, which remains free in the 

 emi)ty space of the l)oLiie, and the wine thus managed be- 

 comes very brisk and sparkling. This is the method prac- 

 tised m Champagne, where they pour off the wine several 

 times, to separate the sediment which is thrown down. In 

 Lanoucdoc, they render the very sweet white wines spark- 

 ling^ by putting some grains of corn into the bottles. These 

 <rralns, doubtless, supply a ferment, which excitmg a fresh 

 fermentation occasions a disengagement of carbonic acid 

 gas. 



But, as M. Chaptal remarks, it is not to the presence of 

 carbonic acid gas only that sparkling wines owe their ex- 

 cellent qualities ; they are also indebted for them to the 



aroma 



