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.
For this we submit the following formula: Take fresh lemon-peel, sliced thinly, or better grated, four ounces (the pulpous part adherent to the peel being cut off previously); diluted alcohol, twenty ounces; macerate for ten days in a closed vessel, with occasional agitation; strain, press and filler; then add sufficient diluted alcohol to make one pint. This tincture may be used for flavoring mixtures which want to be improved by a touch of lemon flavor.
The safest way to prevent "lemon soda" from turning milky is to use the "soluble essence". It is sometimes recommended to carefully filter the compound syrup; but this is too troublesome. A carefully prepared water-soluble essence is of better practical use.
This is very seldom employed in preparing syrups, and should only then be used when the syrup is prepared by the cold process. We append a direction for its preparation: Triturate one drop of the oil, with sugar, and agitate with one pint of water, which will be imparted with the pure odor of lemon. Filter. For lemon water on a larger scale, prepare like rose and orange-flower water (see special directions).