204 COLOURING MATTERS IN WINE. 



and more colour. Every solution of tannic acid, par- 

 ticularly when combined with other organic substances, 

 acquires colour when exposed to the air. It is there- 

 fore eventually resolved into a sediment, apothema, a 

 brown matter, which possesses some properties in 

 common with the above-mentioned apothema, of ex- 

 tractive matter. If the solution contain but little 

 tannic acid, the colour called yellow may become dark 

 yellow, or actually brown, if much, much darker. The 

 dark colour of mahogany is derived from the apothema 

 produced from the tannic acid contained in the wood. 

 Precisely the same observations may be made with re- 

 spect to our wild chestnuts, which are covered with a 

 perfectly white skin, so long as the seed is protected 

 by the husk, but when this bursts, become dark brown 

 in the space of a few hours. "Without maintaining that 

 the yellow colour of Muscadel, Champagne, and even of 

 Teneriffe and Madeira, is to be entirely ascribed to the 

 alteration thus undergone by tannic acid, it is true 

 that the yellow hue is in great part to be attributed 

 to this and the extractive matter before mentioned. 

 Eor in these yellow or dark-coloured wines, the darker 

 the colour originally was, the more intense is the 

 colour given on the addition of a salt of iron. 

 This reaction holds so true in general with respect 

 to all liqueur wines, that the less the colour produced 

 in any wine by the addition of chloride of iron, the 

 lighter its colour originally was. 



Pure Ehine wine is generally considered to be ex- 



