The production of American wine has experienced a noteworthy increase during the past twenty-five years. While, in 1860, less than two millions of gallons of native wine were consumed in the United States, in the year 1884 the quantity used exceeded seventeen millions of gallons.[87] Aside from the general distinction of red and white, wines are classified by their characteristic properties, as dry, sweet, and cordial. In dry wines, such as those of the Gironde and Rhenish districts, considerable free acid, and but little or no sugar are contained, whereas in sweet wines (Madeira, port, etc.) a certain proportion of the sugar remains undecomposed. Cordial wines are distinguished by their sweetness and comparatively heavy body. The nature of wines is materially affected by the proportion of glucose and acids contained in the original must, as well as by the environments of their manufacture, such as climate and temperature. From a chemical point of view, the most important constituents of wine are the primary products of fermentation--alcohol, succinic acid, and glycerine, but its market value is far more dependent upon the flavour and bouquet, which are chiefly due to the formation of secondary products, usually included under the name “oenanthic ether,” and consisting of the ethers of caproic, caprylic, and other organic acids. The following table exhibits the constituents of some of the best known varieties of wine, according to results obtained by different authorities:--