46 Researches on Wines and other Fermented Liquors. 
formed by the action of heat upon the elements existing in the fer- 
mented liquor. 
2. When a portion of wine is partly distilled off, and the distilled 
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 ef- 
fect of reducing the specific gravity, when added to the residuum, 
which is never the case. 
3. When the coloring and extractive matters in the wine, are 
precipitated by the subacetate of lead, the pure alcohol may be sep- 
arated by the subsequent addition of dry subcarbonate of potassa, in 
the same manner as from whiskey, gin and brandy. 
The first of the above statements, has been shown to be true, by 
Gay Lussac, (Ann. de Chim. \xxxvi, 175.) The correctness of 
the second, was demonstrated by Mr. Brande, upon a suggestion, 
contained in a notice, of his first paper published in the Edinburgh 
Review. I confirmed the results of Mr. Brande’s experiments on 
this point, in the case of three kinds of area viz. Madeira, Torres 
Vedras and Claret. 
The last, however, is the most conclusive of all the proofs in fa- 
vor of this view of the constitution of wine, as by the process here 
referred to, the alcohol may be separated from wine without the in- 
tervention of heat. We are indebted to Mr. Brande, for having first 
pointed out a mode of effecting this object, (Philosophical Trans- 
actions for 1813.) ‘This consists, in adding to the wine a solution 
of subacetate of lead, filtering the liquor and then adding to the fil- 
tered liquor, dry subcarbonate of potassa. The metallic oxide, as 
he says, forms a dense precipitate with the acid and coloring ex- 
tractive matter of the wine; by filtration, a colorless fluid is obtain- 
ed, from which, the alcohol may be separated, as above mentioned. 
Mr. Brande also states, that the acetate of lead and subnitrate of tin, 
produce the desired effect of separating the coloring and acid mat- 
ters, in the greater number of instances; and to these, I may add, 
the protomuriate of tin, and the protonitrate of mercury, which I 
found to answer, in most cases. 
Observing the effect of adding the subcarbonate of potassa to 
wine, viz. that of causing effervescence and the forming of a floccu- 
lent precipitate, I was led to infer, that the compound thus formed, 
interfered with the separation of the alcohol. 'To determine wheth- 
