The Clarification and Limpidity of White Wines. 739 



fining, even filtration, which gave the wine a maximum of limpidity, 

 and the bottling being carried out under the most irreproachable 

 conditions. This difiiculty is extremely costly for producers of these 

 high-priced wines, but they cannot, however, always foresee it. 

 Luckily, it is fairly uncommon. To a certain extent it can be ascer- 

 tained if the presence of dextrin is not overabundant in the wine 

 about to be bottled. To a small qnantity of the wine in a test tube 

 add half the volume of strong spirit, which is well shaken up with the 

 orifice closed with the hand. The mixture becomes always opalescent, 

 but it is not this appearance that has to be considered. What has to 

 be observed is the formation of a thread-like precipitate, which, when 

 not very abundant, has the appearance of pieces of spider's web in 

 suspension in the liquid. If this precipitate is produced there is the 

 certain proof of the presence of dextrin, and the evident indication 

 that the time of bottling must be retarded. Until now the influence 

 of time alone is the only known means of obtaining this spontaneous 

 precipitation, and it is evident that it would be useful to have an artificial 

 method with more rapidity in obtaining the desired result. In our 

 opinion it is in an appropriate filtration that the solution of the 

 problem must be looked for. It is also by a proper filtration, as we 

 will see further on, that the clarification of mucilaginous wines full of 

 microbes is to be obtained. 



Wines that Ferment. 



White wines may be divided into two classes — dry and sweet. 

 According to the wines and to the seasons, the small quantity of 

 sugar remaining in the dry wines, when the yeasts lose their activity 

 through a falling temperature, can be sufiicient to give rise in the 

 spring or summer to a secondary fermentation in the wine already 

 clarified by several finings. This second fermentation naturally makes 

 the wine cloudy, but if the yeasts which cause it are not accompanied 

 by too many germs of disease it is soon over. This end is hastened 

 by frequent rackings, and the final clarification of the wine is facilitated 

 by sulphuring at this moment. For sweetish wines, such as Sauternes, 

 where the first fermentation leaves often important quantities of sugar, 

 the second fermentation, and consequently the clarification of the wine, 

 would be interminable if we had to wait for its natural ending. There 

 are yeasts of which the fermenting activity is very weak but the 

 alcohol producing power very high. Thus it is not uncommon to find 

 wines containing 27:75 per cent, proof spirit (we have seen them at 

 30 per cent.) which still contain sugar and still ferment. There is no 

 advantage in allowing this fermentation to continue ; firstly, because 

 the wine does not clear, and secondly, because the excessive alcoholic 

 strength diminishes the quality of the wine rather than increases it, 

 since it is necessary to preserve the sweet, creamy flavour that is charac- 

 tei'istic of Sauterne. To arrive at this result numerous rackings and 

 sulphurings are employed. On account of the sulphur the wine becomes 

 an unfavourable medium for the yeasts, which, losing at first their 

 vitality, fall into the lees and are eliminated by rackings. At the end 

 of one year, or perhaps two, not only do these sweet wines no longer 



