“When wine is heated, there is first an escape of an inflammable vapor that burns with a bluish flame. A person needs only to have seen once this preparation of hot wine to recall that curious flame flickering over the boiling liquid and darting up little blue tongues. Now, this inflammable vapor comes from alcohol, a fluid substance that gives to wine its peculiar properties and is hence sometimes called spirits of wine. There are, then, in wine two distinct liquids, one easily reducible to vapor and called alcohol, the other slower to vaporize and recognizable as water. This does not mean that the wine has been watered: the water in question is not there as the result of fraud; it belongs naturally to the wine and comes from grapes just as alcohol does. Wine is therefore a natural mixture of a small proportion of alcohol with a great quantity of water. In our ordinary wines the proportion of alcohol for each hundred quarts of liquid varies from nine to fourteen quarts. “Wine is made from the juice of grapes. This juice, as it is pressed out of the sweet grapes, has none of the taste or smell peculiar to wine, for it does not yet contain any alcohol; but it does have an agreeably sweet taste, the same taste that makes grapes so desirable a fruit for the table. This pleasant flavor is due to a sort of sugar present in the grapes. Examine carefully a handful of raisins such as you buy at the grocer’s: you will detect on their surface, certain tiny white grains that crunch under the teeth and have a sweet savor. Those grains are little particles of sugar that have collected on the outside of the grapes during the process of drying. Grapes, then, must contain sugar. “Well now, this sugar is exactly what causes the formation of alcohol. What is sugar in the fresh juice of grapes is alcohol in the same juice after it has fermented and turned to wine. Let us consider briefly how this change comes about.