On Madame Gervais' X^iu; Mclhvd af Fermcnlaiion. 37 



chancres of the external temperature can have no effect upon 

 the tennenting gyle; and if" it has been rn-CHEo at a proper 

 heat, (which is between sixty-five and eighty*,) will proceed 

 through its different stages, as well during the hottest days ol" 

 summer, as in the selected months of autumn and s})ring. 



With respect to motion, we are indebted to Monsieur Ga\- 

 Lussac, an able French chemist, for a beautiful and important 

 experiment, proving that must, possessed of all the requisites 

 to produce a good fermentation, will not begin to ferment un- 

 less excited by a foreign agent. He placed the must in a close 

 vessel, from which the atmospheric air had been exhausted, 

 where it remained several days widiout giving any signs of 

 fermentation, from which he concluded some power was 

 wanting to break the union of its constituent princi})les ; he 

 tlierefore introduced a small quantity of oxygen, which imme- 

 diately caused the must to ferment, evidently proving the ne- 

 cessity of a small portion of atmospheric air (which contains 

 oxygen), to allow the fermentation to connnence. But it at 

 the same time proves, that, after performing that office, this 

 great enemy to all fermented liquors may be dispensed with, 

 without impeding the process ; as the small quajitity of oxy- 

 gen, introduced by Monsieur Gay-Lussac, was soon absorbed 

 by the carbon to form carbonic acid gas, and he found no oc- 

 casion for any further supply. 



This discovery is of the greatest importance, since it en- 

 ables us, widiout the least detriment or inconvenience to tlie 

 process, to exclude the oxygen of the atmosjiheric air, which, 

 by constantly supplying the'gyle with the principle diat causes 

 and promotes acidity, casts on it from the first tliat roughness 

 and disairreeable flavour which spoil most of our common be- 

 verages. 



Here again die new apparatus jiroves of great benefit ; for 

 as soon as carbonic aciil gas is evolved from the fcrnienting 

 gyle, the atmospheric air, being lighter, is driven out Irom the 

 upper part of the working-tiui ; and as no air is permitted to 

 enter afterwards, all the subsc<iuent carbonic acid gas emitted 

 diminishes die (|uaiitity of oxygen contained in the gyle, by 

 the oxygen uniting wiili the carbon as fast as it disunites irom 

 tlie saccliarine matter during its decomposition, and thereby 

 secures a souutlness and peculiar mildness not to be procured 

 by any other mode. 



The necessary conditions for a complete decomposition of 

 the saccharine matter haviiig been stated, it remains to notice 

 those required for a good production of alcoliol. 



* Fcnncntatiop. will take place from f<>rty-ci;^lu to one Iiumlred aul 

 thiriv-fii:ht de^;i-fc:% 



1 he 



