and the Method of making Wines, 337 



of the swelling up of the mass; it increases and decreases like 

 it, as will be proved by the experiments which I shall subjoin 

 to this article. 



The heat is not always equal throughout the whole mass 5 

 it is often more intense towards the middle, especially when 

 the fermentation is not sufficiently tumultuous to mix and 

 confound by violent movements all the parts of the mass : in 

 that case the vintage is trod again ; it is agitated from the 

 circumference to the centre, and an equal temperature is 

 established in every point. 



We may admit as incontestable truths : 1st, That, at an 

 equal tem}]u2rature, the greater the mass of the vintage the 

 greater will be the effervescence, movement, and heat, 2d, 

 That the effervescence, the movement, and heat, are greater 

 in vintage where the juice of the grapes is accompanied with 

 the pellicles, stones, stalks, &c. than in must separated from 

 all these matters, 3d, That fermentation can produce from 

 59 to 95 degrees of heat : at least, I have seen it in activity 

 between these two extremes. 



2d, Disengagement of Gas, — ^The carbonic acid gas dis- 

 engaged from the vintage, and its effects hurtful to respira- 

 tion, have been known since fermentation itself was known. 

 This gas escapes in bubbles from every point of the vintage, 

 rises in a mass, and bursts at the surface. It displaces the 

 atmospheric air which rests on the vintage, occupies every 

 where the vacant parts of the vat, and flows over the edges, 

 precipitating itself in the lowest places on account of its gra- 

 vity. It is to the formation of this gas, which takes a por- 

 tion of oxygen and carbon from the constituent principles of 

 the must, that we shall in future refer the changes which 

 take place in fermentation. 



This gas, retained in the liquor by all the means that can 

 be opposed to its evaporation, contributes to preserve the 

 aroma and a portion of alcohol which exhales along with it. 

 The antients were acquainted with these means, and they 

 carefully distinguished the product of a free from that of a 

 close fermentation ; that is to say, the fermentation effected 

 jn open and that effected in close vessels. Brisk wines are 

 indebted for that quality to their having been shut up in the 



Vol. IX. U u bottles 



