WINE-MAKING 225 



the same, finally, as that produced by burning coal. 

 The alcohol remains in the liquid, which thus grad- 

 ually loses its original sweet taste and acquires in- 

 stead a vinous flavor. The gas, on the contrary, 

 works its way to the surface, agitating the mass 

 with a sort of tumultuous movement like that of 

 boiling water, and is dissipated in the atmosphere. 



"Let us bear in mind that carbonic acid gas is as 

 invisible as the air itself, that it has no odor, no 

 color, and finally that it kills quickly if inhaled in 

 any considerable quantity. That explains the dan- 

 ger lurking in a wine-vat during fermentation, or 

 even in a wine-cellar that lacks sufficient ventilation 

 to carry off the perilous gas. No one should enter 

 such places without holding before one a lighted taper 

 at the end of a long stick. While the taper continues 

 to burn in the usual manner, one can proceed with- 

 out fear : there is no carbonic acid gas present. But 

 if the flame becomes dim, gets smaller and smaller, 

 and finally goes out altogether, one must beat a 

 hasty retreat, for the extinction of the taper is a 

 sure sign of the presence of carbonic acid gas, and 

 further advance would mean exposing oneself to im- 

 minent death. 



"But to return to the subject of wine-making, 

 we were saying that the sugar which imparts its 

 sweet taste to the must (that is, the unfermented 

 grape- juice) changes its nature and divides into 

 two parts : alcohol, which remains in the liquid and 

 turns it to wine, and carbonic acid gas, which is dis- 

 sipated in the atmosphere. When this process is 



