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 the manufacture of carbonated beverages the fluid extract of ginger may be prepared according to the following directions: Take one pound of bruised ginger, moisten it with a few ounces of alcohol of 95 per cent, and pack firmly into the percolator; then add enough alcohol of the same strength to saturate the powder and leave a stratum above it. When the liquid begins to drop from the percolator close the lower orifice, and, having closely covered the percolator, macerate for forty-eight hours. Then allow the percolation to proceed, gradually adding more alcohol, until the ginger is exhausted and sixteen fluid ounces of extract are obtained. Re-percolate.
This process does away with the evaporation of a part of the extract, as directed by the United States Pharmacopoeia, and thus modifies the operation. But we propose to follow the process of re-percolation regularly, as already explicitly explained on page 484. Ginger is readily exhausted by alcohol; the brownish-red fluid extract is six or three times respectively stronger than the tinctures of ginger hereafter directed, and has the same sensible properties, but in a higher degree.