C LEAKING OF WLN T E. 97 



which will be thereby increased. Albumen, mixed 

 with tartaric acid, dissolved in water, cannot be pre- 

 cipitated, either by boiling or by alcohol, for the tartaric 

 acid holds the albumen in solution. From this we 

 learn that albumen, when used in the clearing of 

 wine, is not rendered insoluble by the alcohol in the 

 wine, but by the formation of tannate of albumen. 



The precipitate of tannate of albumen thus ob- 

 tained, is, however, soluble in water, with excess of 

 tartaric acid. How far the discolouration of wine may 

 be carried by means of albumen, depends on the quan- 

 tity of tartaric acid, tannic acid, and alcohol present 

 in the wine. Vergnette Lamotte* prefers isinglass 

 to albumen, and recommends it as better adapted to 

 the purpose. Isinglass cannot, however, be com- 

 pletely precipitated in weak spirit. It is, there- 

 fore, also chiefly useful because it forms a precipitate 

 with tannic acid. 



If but little tannic acid be contained in the wine, 

 the precipitate obtained by means of isinglass will be 

 inconsiderable, and but a small quantity of colouring 

 matter will be withdrawn from the wine. So that the 

 use of isinglass will only render the colour of wines con- 

 taining much tannic acid lighter. To render it useful 

 as an application to other wines we must first, as we 

 have seen, add a little extract of nut-galls to the 

 wine, which at once imparts the power to isinglass of 



* Dingler's Polyt. Journ. Ed. Ill, s. 147. 



H 



