738 Agricultural Journal of Victoria. 



always easy in practice, and often necessitates a multitude of 

 operations. First of all the acidity of the wine must be increased 

 if necessary, by an addition of tartaric acid, followed by tborougli 

 aeration, and a heavy sulphuring. The activity of the microbes will 

 thus be paralysed, and by the help of a heavy fining the elimination 

 of the greater portion of the microbian cloud will be obtained, 

 which will eventually disappear completely under the action of 

 subsequent rackings. If these means are insufficient, recourse must 

 be taken, as soon as possible to filtration or, better still pasteurisa- 

 tion, but it is necessary to only have recourse to pasteurisation after 

 having used the other methods so, as far as possible to introduce 

 into the apparatus a wine cleansed from the greater quantity of its 

 impurities. 



EoPY Wines. 



In addition to the preceding microbian cloud, the wine is some- 

 times ropy or greasy, and the difficulty of clarification is much 

 greater. Ropy white wines are common in some districts, and the 

 microbian origin which Pasteur discovered is now known. However, 

 this is not the only known origin, as certain varieties of yeast have 

 been discovered which can contribute to produce this special appear- 

 ance of the wine. But whether it is produced by microbes or yeasts 

 , it is easy to correct it. By aerating and beating up the wine the 

 oily consistence disappears ; an addition of tannin prevents its 

 reappearance and facilitates the clarification by fining. This is not 

 the case when the rope is due to a totally different cause to the 

 preceding one, when it is derived from the grey rot of the grape. 

 Dextrin, which is the mucilaginous product introduced into the wine 

 by the Botrytis cmerea is refractory to a separation by the preceding 

 method, and consequently makes clarification extremely difficult. The 

 addition of tannin is useless. Aeration, if not always useless, can 

 only be practised after the wine has been sulphured to prevent its 

 breaking. As for pasteurisation it cannot be considered, for it would 

 rather retard the separation of dextrin. 



Natural separation becomes almost complete at the end of a more 

 or less protracted period, for it is still in relation with the action of 

 coagulation. It is slower with white wines than with red wines, 

 probably because the latter precipitate more abundantly as they 

 mature. Sauternes, which always contain this dextrin, should never 

 be bottled until it is completely eliminated, or else with the coagula- 

 tion continuing the wine may lose its initial limpidity, and a cloud is 

 formed which congeals into small lumps not adherent to the glass. 

 This floating deposit, which is somewhat difficult to separate, has 

 none of the characteristics of the deposits due to the micro-organisms 

 found ordinarily in wines. It can be found in wines of the finest 

 quality which received every possible care, that is to say after three 

 or four years in wood, the use of the most approved methods of 



Note. — Some red and white wines made from American grapes and even certain 

 European varieties in the South of France are sometimes ropy, because they contain 

 an abundance ot pectic matters which act like dextrin. 



