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.
The fluid extract of the powdered coca-leaf is prepared as follows: Of coca-leaves powdered, one pound; diluted alcohol sufficient to make one pint of extract. Moisten the powder with six ounces of the diluted alcohol, pack into the percolator; then add enough diluted alcohol to saturate the powder and leave a stratum above it. When the liquid begins to drop from the percolator close the lower orifice, then cover the percolator tightly and macerate for forty-eight hours. Then allow the percolation to proceed, gradually adding diluted alcohol, until the coca is exhausted and sixteen fluid ounces of extract are obtained. This extract is of a deep-brown or olive-brown color, and has the astringent, bitter and slightly aromatic taste of the leaves, and is miscible with water. Its effectiveness is very modified. This extract and the commercial extracts of coca are more for pharmaceutical use, where a dose from one to four fluid drachms is dispensed. To impart to a carbonated beverage the desired effects of cocaine - and but for this reason it is employed and not for giving any aroma - it is much too weak, except when from one to four pints of the extract to one gallon of syrup are employed, which makes it more expensive and troublesome.
Formulas directing one or more ounces of extract to be added to one gallon of syrup are misleading, as this proportion would have no effect whatsoever. When not alone the name "coca" for new beverages, but principally the effects of the alkaline cocaine, axe desired, the tincture of-cocaine or essence of coca prepared after the appended formulas offer all that can be desired.