210 COLOURING MATTERS IX WINE. 



phuretted hydrogen conducted through it, a brown 

 substance may be extracted from the sulphide of lead, 

 by means of alcohol and tartaric acid. A tincture of 

 the original colour of the wine is thus obtained, and 

 the sulphide of lead contains nothing more. 



If this tincture be evaporated upon a water-bath, 

 and the residue treated with water, the whole is not 

 dissolved (a), but a portion remains undissolved, 

 which, however, is easily soluble in diluted ammonia, 

 to which it imparts a brown colour. Both, are, there- 

 fore, apothema, but both want the reaction of the 

 apothema of tannic acid ; for by gelatine and sul- 

 phuric acid, no precipitate can be obtained from it. 

 However, the progress of decomposition entirely de- 

 stroys all tannic acid reaction in apothema of tannic 

 acid. When it is first formed a precipitate may be 

 obtained by the addition of gelatine and acid ; but 

 after further decomposition it loses this reaction, and 

 the apothema of tannic acid becomes exactly like apo- 

 thema which has been produced in a different manner. 



The brown substance (a), which is soluble in am- 

 monia, but not in water, was re-precipitated by means 

 of sulphuric acid. The above-mentioned experiments 

 sufficiently prove that no peculiar colouring matter is 

 contained in the above-mentioned liqueur wines, 

 which are both distinguished by equal intensity of 

 colour. In considering the extractive matter of wine 

 we shall enter upon certain details which belong to 

 this subject; at present we will only observe, that 



