504 CHEMISTRY OF ALCOHOLIC FERMENTATION. 



readily with alcohol, in the nascent state, to form esters, than is 

 the case with acids already formed. 



325. Alcohols and Esters (Bouquet Principles) as Vola- 

 tile By-products of Alcoholic Fermentation. Other 

 By-products. 



Whereas, in the preceding paragraphs, we have dealt with the 

 volatile products belonging to the aliphatic series and containing 

 relatively large amounts of oxygen and little hydrogen such as 

 the volatile acids and the aldehydes, with the general formulae, 

 C B H 8M O g and C M 'H 8B we will now proceed to treat of bodies with 

 the formula C n H 8W + 20, the first of which series is methyl alcohol, 

 CH 3 .OH. This is often formed during bacterial fermentation, 

 but may also occur through the decomposition of intermediate 

 products (glucosides) in alcoholic fermentation by yeast. This 

 circumstance will be referred to later on (see p. 510, vol. ii.). 



The second member of the series, namely, ethyl alcohol, one 

 of the chief products of fermentation, has been dealt with in 

 322. 



The higher alcohols are abundantly represented in cognac, and 

 in the fusel oils discovered by SCHEELE (II.) in 1785. They 

 occur in the free state, and also as esters in combination with 

 fatty acids. 



Primary propyl alcohol, CH 3 .CH 2 .CH 2 .OH, was obtained by 

 CHANCEL (I.) from the fusel oil of grape-husk spirit, and also by 

 FITTIG (I.). According to K. WINDISCH (III. and IX.), KRUIS 

 and RAYMAN (II.) and ORDONNEAU (I.) it occurs constantly in 

 crude potato and corn spirit, cherry brandy and cognac. 



Secondary, or isopropyl alcohol, CH 3 .CH(OH).CH 3 , is said to 

 have been obtained by BERTHELOT (VIII.), and was found in 

 crude potato spirit by RABUTEAU (II.). 



Normal butyl alcohol, CH 8 .(OH,) r OH,.(OH) > is formed, 

 according to Frrz (XIII.) and EMMERLING (VII.), in the fermen- 

 tation of glycerine (a constant by-product of alcoholic fermentation) 

 by fission fungi. It was isolated from crude potato spirit by 

 RABUTEAU (II.), from crude corn spirit by EMMERLING (VII.), and 

 from cognac by ORDONNEAU (II.). According to this last worker, 

 it is probably a normal product of fermentation by wine yeasts, 

 whereas beer yeast, which furnishes other secondary products, 

 produces isobutyl alcohol, (CH 3 ) 2 .CH.CH 2 .CH 2 (OH). This last 

 substance had already been obtained by WURTZ (I.) from the 

 crude spirits furnished by beetroot, potatoes, and grain ; it was 

 also found by PIERRE and PUCHOT (I.), K. WINDISCH (III. and 

 IV.), RABUTEAU (II.) and by KRUIS and RAYMAN (II.). 



Primary pentyl or amyl alcohol, CH 3 .(CH 2 ) 3 .CH 2 (OH), seems, 

 according to WYSCHNEGRADSKY (I.), to occur along with the 

 isomeric amyl alcohols in fusel oil. 



