WINE AND THE ART OF WINE TASTING. 31 



fectly colorless, it may be rendered so by the use of animal charcoal, 

 properly prepared, that is to say, in such a way as to prevent its dimin- 

 ishing the acidity of the wine. If this precaution is not taken, the wine, 

 oh account of its diminished acidity, will quickly turn yellowish on 

 account of the formation of ferric compounds, which, under these condi- 

 tions, takes place with great readiness. 



STRAW-COLORED (Paglierino, It.; Couleur de paille, Fr.). Of the color 

 of straw, but somewhat pale. 



AMBER, YELLOW (Giallo, It.; Jaune, Fr.). Is said of wines which have 

 a deeper straw color.* 



GOLDEN, GOLDEN- YELLOW (Giallo dorato, Aurato, Dorato, It.; Dore, 

 Fr.). This epithet sufficiently explains itself. 



" Egli e il vero oro polabile" wrote Redi of the wine of Trebbiano. 



GREENISH (Verdognolo, Verdiccio, It.; Verddtre, Fr.). When a wine 

 has a slight greenish tint, resembling somewhat the green of grass. 

 This color is characteristic of certain varieties of grapes; for example, 

 the Verdea or Bergo. 



Regarding the wine of this variety, it is said that the Verdea of Tus- 

 cany is not so called on account of its green taste, but because of its 

 greenish tint. 



Frederick the Great, of Prussia, had a great predilection for the wine 

 of Verdea. 



This greenish color is also characteristic of the wines of Reno, and in 

 general of wines made from somewhat acid grapes. 



PINKISH- YELLOW, OR PINKISH STRAW-COLOR ( Paglierino rossastro, Giallo 

 rossastro, It.; Faille roussdtre, Fr.). Sometimes a wine, in addition to 



*This yellow color may be natural and proper to the wine, or it may be a color which 

 it has acquired from several causes, among which are some that have very grievous 

 effects on the wine, and may be considered properly as maladies. 



The wines most generally subject to this disease of becoming yellow are those poor 

 in alcohol, tartar, tartaric acid, and tannin, and which on the other hand are rich in 

 malic acid. 



I have already alluded to one of these causes above, namely, the presence of iron 

 compounds. Some colorless wines, which are rather poor in acid, become, when placed 

 in contact with the air, yellow or yellowish brown, in consequence of the formation of 

 complex compounds, ferric, humic, etc. 



The commonest causes of the yelkwing of wines can be traced to the conditions under 

 which the vintage has taken place; if, for instance, the season has been cold and rainy, 

 and the grapes have been gathered after the vines have in great part been denuded of 

 their foliage, if the bunches contain decayed, soft, insipid grapes poor in acid and sugar, 

 a wine of poor keeping qualities is obtained, and one very likely to become yellow, 

 unless art comes to the aid of nature. 



Robinet, who has made special investigations with regard to the causes of this dete- 

 rioration of white wines, distinguishes between that due to a fermentation caused by a 

 mycoderm, and those due to chemical action, and among the latter he mentions some 

 which give rise to the formation of malic ether, which reacts on the sugar. I should, 

 however, remark here that after stating his belief in the formation of the malic ether, 

 he declares that he has been unable to find the rational equation of the reaction, or 

 definite proof of its existence, but bases his belief in the formation of the malic ether 

 on the taste and pronounced odor of cider which the wine acquires an odor which is 

 characteristic of the above substance. 



Robinet also makes the important observation that during his researches he had 

 noticed the disappearance of the glycerine from wines which were becoming yellow. 

 This disappearance of the glycerine would lead one to believe that the reactions which 

 take place are much more complicated than supposed by Robinet, especially in consid- 

 eration of the fact that the glycerine is subject to transformations, like the other 

 ingredients of wine. 



Instead of trying to cure or ameliorate this defect in wines, it should be prevented, 

 which can be done by the addition of alcohol and acids. 



The secondary fermentation which causes this disease is due ? still according to Rob- 

 inet, to a particular mycoderm, which can be seen distinctly with a magnifying power 

 of nine hundred diameters. This mycoderm is extremely small, and of an oolong 

 shape; it is ^ ff m.m. in length, and ^^ m.m. in width. 



