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.
Take of ginger, bruised, eight ounces; alcohol, two pints; macerate for twenty-four hours, in well-stoppered bottle; then transfer to a filter or decant the liquid, and pack the moistened ginger in a cylindrical percolator, and gradually pour the liquid upon it, and add more alcohol until two pints of filtered liquor are obtained.
In consequence of the mucilaginous matter contained in ginger, alcohol of 95° should be properly preferred. The extract or tincture made with diluted alcohol, or .proof spirit, is apt to be turbid.
This appears in commerce; the fluid extract of ginger being evaporated in vacuo (page 490) to consistency, and is therefore highly concentrated, so that one ounce may flavor fifteen gallons of syrup. Whether this solid extract of ginger is soluble without causing turbidity depends on the mode of its preparation. For commercial purposes, the consistent extract is a convenience, saving the expense of package and freight. For home-use the fluid-extracts or tinctures are naturally preferable.
A regular fluid extract or tincture of ginger is not soluble or miscible with water. The resin and volatile oil, on which the pungency and aroma of ginger depend, can only be made partially to dissolve in water. Numerous formulae, based on various investigations, have been published from time to time, of which we append those which deserve attention, or are of practical value. We refer to the works of B. S. Proctor, 1859; J. L. A. Creuse, 1873; of J. C. Thresh, 1878 and 1879; and Carl Riebe, 1884.
Soluble essence of ginger: six fluid draahms tincture of ginger, six fluid ounces of water, two grains alum, ten minims (drops) of solution of potassa. Mix; let stand and filter. This essence mixes with water clear, but is deficient in aroma.
Fluid extract of ginger, one pint; water, owo pints; carbonate magnesia, two ounces. Mix; shake frequently during twenty-four hours, filter, evaporate to one half pint, and add alcohol, one-half pint.
(Presented to the British Pharmaceutical Conference). To tincture of ginger, one part, add slaked lime, until it ceases to lose color; filter; add proof spirit through the filter to make two parts; to this add dilute sulphuric acid, until the yellow color suddenly disappears; after twenty-four hours; filter; dilute to four parts with water. To this add powdered! pumice or silica, and filter at zero C. This process is intended to render the resin much more soluble than the oil joy combination with an alkali.
(Read Before The Michigan Pharmaceutical As-Sociation). A sufficient quantity of filter paper, in small pieces, placed in a wide-month bottle, is saturated with fluid extract of ginger, and then exposed to a temperature below 140 degrees Fahrenheit, until the alcohol is evaporated. Add water, shake repeatedly and macerate (to soak or steep) twenty-four hours; transfer to a strainer, and drain off the liquid. Transfer the pulp to a percolator, in the bottom of which is a layer of fine purified sand; pour on the strained liquid, and after this has passed through the pulp and sand, add a sufficient quantity of water to make the desired measure. Then dissolve the sugar in the percolate to form a syrup.
Another process still, and one followed by some manufacturers of bottlers* supplies, is simply to saponify the resins in the usual way by means of a strong alkali, which cannot find our approval.
None of these are exactly satisfactory; some attempt too much; some are deficient in aroma; some, if still hot, are open also to the objection of a soapy, chemical taste and smell. So we may correctly conclude that, owing to the peculiar constituents of ginger, no preparations from it could be made which would mix readily with aqueous menstrua and still accurately represent the drug. We must also carefully take into consideration the following facts: if the extract or tincture of ginger, to be rendered soluble, is treated with an alkaline, and not most carefully prepared, the action of the fruit-acid used to acidulate the beverage, in coming in contact with the alkali (which has absorbed a considerable amount of the resinous portion of the ginger) causes a slight ebullition, turbidity and flakiness.