of Fermeyilation, or of Distillation. 209 



temperatures, from the lowest adequate degree to the highest that 

 the operation would permit. Were the alcohol a product, and not 

 an educt, he conceived that in these trials the quantity obtained 

 \vould vary with the temperature : but since the quantities were 

 equal, he conceived the converse proposition to be true. 



It appears to me, if we suppose the decomposition of the wine 

 to take place at the lowest degree which Mr. Brande tried, that 

 the quantity of spirit produced should be the same at any higher 

 temperature *. 



With regard to this question, there seems to have been a 

 strange confusion in the opinions of Fabroni. He tells us that 

 14* (64) is sufficient to distil off, and consequently to form the 

 spirit ; yet he considers that spirit does not exist ready formed 

 in fermented liquors. In the brewing of common ale, the wort 

 is mixed with yeast at 55": the temperature rises to 70, often 

 higher. Wash receives the yeast at 60 ; the heat rises to 90, 

 and frequently to 1 00^. In the wine countries, must is set to 

 ferment at 68°, and a much higher temperature succeeds. In 

 all these cases the heat is much above that at which Fabroni 

 considers alcohol to be produced ; so that it is not clear how 

 he infers alcohol to be only a product of distillation. The fol- 

 lowing passage extracted from his own writings seems to throw 

 no light on the subject : for my own part, I do not fully com- 

 prehend its meaning : " la chaleiir necessaire a cet effet ne doit 

 pas etre considerable ; car il s'en forme par iachaleurde la fer- 

 mentation, aune chaleur de distillation de 14 degres." 



It has been supposed by many, that during the fermentation 

 of liquors the evolved carbonic acid carries off with it some 

 vapour of alcohol. If this were the case, I thought it sufficient 

 proof that alcohol must be formed during fermentation. To 

 ascertain it, I set a vessel of wash to ferm.ent, and contrived the 

 apparatus so that the carbonic acid was forced to pass through 

 some ounces of water under tolerable pressure. The process 

 continued for six days, and the gas which passed through the 

 water was in considerable quantity. This water when distilled, 

 and the product also several times distilled, manifested no signs 

 of containing alcohol : so that, if any were produced, it was so 

 minute as to escape detection, 



I was the more surprised at this result, as Chaptal had satisfied 

 himself that alcohol is carried off from fermented liquors. He 

 exposed water to the gas arising from a fermenting tun : he then 

 .set it by for a month ; and at the end of that time fourld it con- 



* Since the above was written, Mr. Brande has himself stated this very 

 objection, ami has instituted new experiments on the subject, wliich shall 

 be adverted to in proper place. 



Vol. 44. No. 197. Sf-^^ 1814, O tained 



