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.
This is prepared by dissolving the oil of ginger in alcohol. It is but slowly soluble in the latter, and requires repeated agitation by shaking to completely dissolve.
The essence of ginger has an agreeable ginger aroma, but beverages prepared or flavored only by this preparation appear deficient in aroma, und hold nothing of the other salient principles of the ginger root in solution. Besides, the oil of ginger is difficult to be cut, dissolves only in very limited quantities in reduced spirits, and yields therefore a weak flavoring essence, which has to be made especially weak for the purpose of manufacturing carbonated beverages, in order to make it miscible with water. One ounce of the ginger oil can be dissolved in sixteen ounces of alcohol by agitation. However, this is too strong and too concentrated a solution for practical purposes; it is economical to prepare only weak solutions.
We append this Formula, as follows: Take ginger oil, one-half ounce; alcohol 95°, sixteen ounces; mix and agitate.
We append another Formula: Take of ginger oil, two drachms; cut thoroughly with sugar and pumice. Then add by degrees a mixture of eight ounces of water and eight ounces of alcohol. Agitate thoroughly, filter and clarify.