There is no exact legal definition of the difference between new and old whisky. A definition, however, is employed in the "Bottled In Bond" Act, where it is provided that distilled spirits may be bottled in bond, under the supervision of the United States officials, provided they are at least four years old. This provision of the law may be reasonably construed to mark the line between new and old whisky. It is, to be sure, an arbitrary limit fixed by the Legislature, but it also has a reasonable basis, since after four years of storage there is such a great improvement in the liquor itself as to warrant the transposal from the new to the matured class.

It is true that distilled spirits will improve in wood for a much longer period than four years. They are left sometimes in wood for 8, 12, 16, and even 20 years, and in many cases improvement is noticed throughout the whole time. The cost of the liquor which has been stored so long a time, and during which storage has lost a large portion of its volume, is so great that distilled liquors are kept only over these great lengths of time to supply the wants of connoisseurs who have sufficient income to warrant the purchase of such expensive liquors.