148 



Professor Beck's Researches on Wines 



results, it is necessary to make comparative experiments with 

 pure wine. — See Berzelius's Traite de Chimie. 



Specific Gravity of Wine. — It has long been known, that the 

 specific gravity of wine gives us no information, as it does in 

 the case of distilled liquors, of the proportion of alcohol which 

 it contains. Direct experiments on this point have been made 

 by Brisson and Brande. I also accurately determined the den- 

 sity of several varieties of wine, and other fermented liquors. 

 The following are some of the results : — 



Madeira, mean of three kinds, . . . 0.98659 



Secrial Madeira, ...... 0.98606 



London Particular, . . . . . . 0,98860 



Port, mean of two kinds, . . . . 0.98203 



Sauterne, . . . . . . . 0.99511 



Claret, mean of two kinds, . . . . 0.99490 



American Wine, . . . . . . 1.00702 



Cider, mean of two kinds, * . . . 1.03400 



Metheglin, ....... 1.08984 



Alcohol in Wine. — It has been a subject of some controversy 



whether alcohol exists, ready formed, in wine, or whether it is 



generated by the heat employed in the process of distillation. 



The latter opinion was supported by Fabroni (Ann. de Chim. 



xxx. 220.) ; but its fallacy has been completely exhibited, by 



the able investigations of Mr Brande and Gay Lussac. 



The following statements seem to be conclusive as to the ex- 

 es 



istence of ready formed alcohol in wine. 



1. Alcohol can be obtained from wine by distillation, in va- 

 ctw, at the temperature of 60° F., which precludes the idea 

 that it is formed by the action of heat upon the elements exist- 

 ing in the fermented liquor. 



% When a portion of wine is partly distilled off, and the dis- 

 tilled liquor is afterwards added to the residuum in the retort, 

 the specific gravity of the mixture is precisely the same as that 

 of the wine previous to distillation. Alcohol being much lighter 

 than wine, if it were formed during the process of distillation, 

 would have the effect of reducing the specific gravity, when add- 

 ed to the residuum, which is never the case. 



3. When the colouring and extractive matters in the wine are 

 precipitated by the subacetate of lead, the pure alcohol may be 



