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.
Mix the glycerine with some of the diluted alcohol, moisten the powdered bark with six ounces of the mixture and pack in percolator. Pour on the rest of the mixture to leave a liquid stratum above the bark. Macerate for forty-eight hours. Keep percolator covered. Then proceed to percolate and add enough alcohol until sixteen fluid ounces of extract, or the desired quantity of tincture, is obtained. This extract is of red-brown color.