222 COLOTJHING MATTERS IK WINE. 



of chlorine is likewise a first oxidation, and further 

 oxidation of the newly-formed brown substance may 

 be occasioned by the addition of more chlorine. The 

 same holds good of tannic acid ; chlorine and alkalies 

 make it brown. Faure's conclusion, drawn from this 

 reaction, is however incorrect; he has viewed the 

 two distinct operations of chlorine upon the pure 

 colouring matter, as a proof of the presence of two 

 bodies. 



The alteration in colour undergone by the colouring 

 matter of wine, under the operation of some salts, is 

 very remarkable. I have taken the concentrated alco- 

 holic tartaric acid solution, in order to see if it would 

 fall with the precipitate, which is occasionally formed 

 by some tartaric acid salts. 



It remains dissolved in a solution of nitrate of 

 silver, and becomes of a deeper red ; sublimate makes 

 it rather paler ; subnitrate of mercury does not alter it 

 at all ; chloride of tin makes it darker red and slightly 

 violet; nitrate of lead brighter red. "With the ex- 

 ception of those obtained by sublimate the pre- 

 cipitates of tartaric acid salts are white ; the colour- 

 ing matter is not precipitated with them, but remains 

 in the liquid under the influence of the stronger acids ; 

 alum produces no change in it. 



It comports itself very differently with acetate of 

 alumina, and with acetate and phosphate of soda, a 

 little excess of acetic acid being present in all ; these 

 give it a violet hue very much resembling the colour 



