42 VINOUS FERMENTATION. 



the ferment to ad upon it? I think, that the firft portions of 



acid are owing to a combination of the carbon, of the terment. 



Ferment pro- and the oxigen of the fugar, and that tiie ferment gives rife 



^'a^font'^^takhi *^ Termentalion by abftrafting from the fugar a portion of this 



from the fugar principle. To render this idea more clear, I fuppofe a par- 



a portion of its ^j^j^ q^- fugar to be formed of eight parts of oxigen, four of 



carbon, and one of hidrogen, which is not very remote from 



the truth, according to the experiments of Lavoifier: one of 



thefe eight parts of oxigen will unite with a fourth of a part 



of the carbon of ferment, and then, the equilibrium between 



the principles of the fugar being difturbed, they will combine 



in a different manner, fo as to form carbonic acid and alcohol. 



Ferment has a The ferment has in fad a ftrong attradion for oxigen ; as is 



ftrong attratnon ppQ^gj ^y \i^ decompofing air with the greatefl facility; when 

 for oxigen, as '^ •' , , . f , , , , "^ . ,.^ 



is proved by its acetous and carbonic acids are produced, and the azot is clil- 

 decompofingair. gj^g3gg(^^ jf p^j-e air be employed inftead of common air, 

 the readion is ftill more fpeedy. I have introduced 15 gram- 

 • nies of ferment into a vefTel filled with a litre of pure air; I 

 opened it over quicklilver; a fifth of its bulk was abforbed; 

 the ferment was grown four, all the oxigen gas had evidently 

 difappeared, and was converted into carbonic acid : the tem- 

 perature was 15°. 

 What becomes From what has been faid we fee what becomes of the, car- 

 of the principles j^q^ ^f jj^g ferment, and we fliall learn what may become of its 

 other principles, if we recoiled the quantity of produds re- 

 fulting from a given quantity of matter fubjeded to fermen- 

 tation, and comparing the nature of the one with the other. 



From fixty grammes of ferment, and three hundred gram- 

 mes of fugar we obtained, carbonic acid 95 grammes; pure 

 alcohol 171.5; extradive matter, flightly acid, and contain- 

 ingnoazot, 12; refiduum of the ferment 40. There40grara- 

 mes flill contained 25 of ferment, fo that 35 only had been 

 employed for the decompofition of the fugar; and thefe 35 

 Leaves a peculiar were reduced to 15 of a white fubftance* infoluble in water, 

 fubftancc. incapable 



Y A • f ij * The yeaft depofited by a fermenting juice is feldom pure : in 



pure, contain- general it contains more or lefs of this peculiar white fubftancc, 

 ing more or lefs which is fometimes fo abundant, that the fediment confifts of it al- 

 f^Jft'^ P^^"'*'*'^ moft entirely. It is the mixture of thefe two fubltances, thut con- 

 with which it ftitutes In great part the Ices of different wines. All thefe effefts 

 forms the chief depend on the relative proportions of the ferment and the fugar j if 

 part of wine- ^^^^^ ^^ jj^jl^ ^^^^^ ^^ j^^^y^ ferment, the yeaft will be pure j if 

 '"'• on 



