In racking there is a withdrawal of the wine from the sediment which it casts down, and which is known as the lees. It is an important operation because irremediable damage is caused to wine by allowing it to remain in contact with the dregs. A knowledge of their composition is of great value, since it serves to explain their injurious influence. The lees deposited from vinous fermentation consist of mineral salts, tartaric acid, and organic matters. Of these the 'organic substances are the most to be dreaded, and for this reason, that they are very prone to rapid decomposition. They consist of yeast-cells, cells of other micro-organisms, of DEBRIS and minute particles of grape stalks and skins, and of other bodies, all readily liable to decompose. All these various materials, therefore, are continually a source of peril, for the slightest thing may start action in them, which spreads throughout the wine and simply ruins it. By removing it from such undesirable company all these risks are avoided, and the best possible qualities of the wine are afforded the opportunity to develop. In the performance of racking definite changes take place in the vine, which are assuredly important. For it must be remembered that the nearly fermented young wines contain an excess of carbonic acid gas; and this is rightly regarded as possessing great preservative properties, in that it prevents the dangerously spreading growth of the little micro-organisms and germs present in all new wine. In the course of racking, however, a certain amount of the carbonic acid gas must be lost, and fresh oxygen is absorbed from the atmosphere. The oxygen is invaluable from the fact that it exerts a powerful chemical influence upon the wine; as a consequence fermentation is slightly renewed if there be any grape sugar remaining. At the same time the colour of the wine is also modified, and any rawness or harshness in its taste quality is enormously increased by the development of those delicate and subtle ethers which have so much to do with the flavour and bouquet of all wines. The operation of racking, consequently, is one of great importance, as it requires to be repeated from time to time. A copious deposit of lees generally takes place after the first racking, and a second one should speedily follow. During the first year young wines are often racked off as many as three times, but with the older wines once a year, at the beginning of spring, may be sufficient. But it is precisely in matters of this kind that judgment and experience are so much needed.