The possible sources from which alcohol can be obtained areh very numerous, since any substance containing either sugar or starch may be used for the purpose. Moreover, not only sugar and starch, but wood and other cellulose-containing materials are also in use as sources of alcohol, and synthetic alcohol from hydrocarbons is emerging out of the purely experimental stage and becoming, or promising soon to become, a regular commercial product.

Sugar and starch, however, are foodstuffs, and they, or the substances containing them, may for this reason sometimes and in some places be too expensive for use in making alcohol. Thus comparatively little wheat is employed for the purpose anywhere. Potatoes are very largely used on the Continent for making alcohol, but in this country scarcely at all. They command here a higher price for ordinary consumption than the distiller will pay. Be finds maize and molasses more economical, in spite of the fact that they are not indigenous products, whilst potatoes are so. Moreover, many of the substances which contain starches and sugars do not contain a sufficient proportion to make it profitable, in normal circumstances, to use them in spirit manufacture.

Hence, in spite of the great number of articles from which it is possible to obtain alcohol, the materials actually employed to any large extent are comparatively few. They may be grouped into the following classes: -

(a) Starch-containing materials.

(b) Sugar-containing materials.

(c) Cellulosic substances.

(d) Synthetic materials.

A tabular botanical summary of the first two classes will be found at the end of this section (p. 22).