This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
Liquorice enters into various beverages, such as sarsaparilla, root beer, etc. It is prepared for commercial purposes in southern Europe, in the United States and England. The only part of the liquorice plant that is valuable is the root, which in suitable soil will grow to the length of six or eight feet. These roots, properly cleaned, cut in pieces about a foot long, and tied up in bundles, may be seen in any drug store.
For the purpose of preparing carbonated beverages, a solution of stick or powdered liquorice extract in water should never be used, but the fluid extract of liquorice, as per appended Formula, which yields a pure product.
It is prepared from liquorice extract or liquorice root as follows: Liquorice extract, powdered, one pound; distilled water, four pints. Macerate the liquorice with two pints of the water for twelve hours, strain and press; again macerate the pressed liquorice with the remainder of the water for six hours, strain and press. Mix the strained liquors. Add one pint of alcohol, and filter after twelve hours. It yields a clear solution with water. The extract is of a brown color, and of a sweet taste. For commercial purposes it may be concentrated by evaporating the liquid before adding the alcohol, to any desired strength, then adding a fourth of the volume of alcohol, and filtering after standing; or even it may be evaporated to consistency, when it represents the pure solid extract of liquorice. However, for home use, the fluid extract prepared after the above Formula is quite convenient, and whether made of extract or root, about equal in strength, considering the abnormal adulterations of the ordinary liquorice extract, which will yield only from twenty to twenty-five per cent, of pure solid extract or in solution.