FERMENT OILS. 365 



aldehyde the alcoliol was obtained l)y dehydrogenatioii ^Yith sodium 

 amalgam. The alcohol, when properly dried, boils at 115^ C. It 

 is considerably lighter than water, in which it is very sparingly 

 solultle. 



The odorous compound Isobutylbenzene is mentioned in series 

 i., p. 240, and the Methyl-isobutylbenzene (a musk substitute) at 

 p. 8 of the same. They will be referred to in this volume. 



The substances in wine to which its taste and bouquet are due 

 are generated dvrinfj the ferine at at ion of the juice of such grapes 

 as contain a certain quantity of tartaric acid ; they are not found 

 in wines free from all acid, or which contain a different organic 

 acid, such as acetic acid. 



The wines of hot climates possess no odour : wines grown in 

 France possess it in a marked degree, but in the wines from the 

 Ehine districts the perfume is most intense. The kinds of grapes 

 on the Ehine, which ripen \'ery late and scarcely ever completely, 

 such as the Eiessling and Orleans, have the strongest perfume or 

 bouquet, and contain proportionately, a larger quantity of tartaric 

 acid. The wines from the earlier grapes, such as the Eulander 

 and others, contain a large proportion of alcohol, and are similar 

 to Spanish wines in their flavour, but they possess no bouquet. 



The grapes grown at the Cape of Good Hope from Eiesslings, 

 transplanted from the Eliine, produce an excellent wine, but it 

 does not possess the aroma peculiar to Ehenish wine. 



It is evident from these facts, that the acid of wines, and their 

 characteristic perfumes, have some connection, for they are always 

 found together, and it can scarcely be doubted that the presence 

 of the former exercises a certain intluence in the formation of the 

 latter. This influence is very plainly observed in the fermentation 

 of liquids destitute of tartaric acid, and particularly of those 

 which are nearly neutral or are alkaline, such as the mash of 

 potatoes or corn. 



The juice of grapes grown in different climates differs not only 

 in its proportion of free acid, but also in respect of the quantity of 

 sugar dissolved in it. The quantity of nitrogenised matter in the 

 juice seems to be the same in wdiatever part the grapes may grow ; 

 at least, no difference has been observed in the amount of yeast 

 formed during fermentation in the south of Prance and on the 

 Ehine. 



