“White wine is made from white grapes, which have skins with no coloring matter; but it can very well be made from dark grapes, colored though they are. The secret consists simply in this: the crushed grapes are pressed before fermentation begins. In this way the juice is separated from the skins, and, these latter being removed, the wine will be white even with dark grapes. In short, the coloring matter in grapes which gives its hue to red wine is contained solely in the skins; and furthermore it is insoluble in water, but easily soluble in alcohol. Hence it is only after fermentation has made some progress that the liquid becomes colored by the dissolving of the coloring matter through the agency of the alcohol that has been generated. Accordingly, if the skins are removed before the juice ferments and generates alcohol, the wine remains white, since it no longer contains any coloring matter to dissolve. “Some wines force out the corks from their bottles and are covered with foam on being poured into glasses. These are foamy wines, and to produce them the bottling must be done before fermentation is finished. The carbonic acid gas then continues to form, but as it finds no way of escape since the bottle is tightly corked, it dissolves in the liquid and accumulates there, though all the while endeavoring to free itself; and that is what makes the cork pop with a sharp report when the string that holds it down is cut; that is what causes the wine to rush foaming out of the bottle; and, finally, that is what gives the bead to a glass of wine and makes a slight crackling sound as the bubbles burst on the surface. “Foamy wine has a pungent but agreeable taste owing to the carbonic acid it contains. We drink, dispersed through the liquid, the same gas as would kill us if freely inhaled; but it has no terrors except when thus inhaled. Mixed with our drinks, it imparts to them a slightly tart flavor, harmless and even salubrious, since it aids digestion. There is carbonic acid gas in nearly all water that we drink, and it is in fact by reason of this gas that water is able to hold in solution the small proportion of stony matter that contributes toward the formation of our bones. It is to this gas, finally, that effervescent lemonade, cider, beer, and Seltzer water owe their pungency and their foam.” CHAPTER XLV THE STAG-BEETLE