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 well-known article belongs to the preservatives too, and has indeed a great preserving facility. Substances preserved therein keep any length of time, but it does not check fermentation, except when applied in large quantities. It is obtained from fat and fixed oils, a syrupy liquid, specific gravity 1.250, containing 92 and one-half per cent, of absolute glycerine. It is transparent, colorless, inodorous, very sweet and somewhat warm to the taste, soluble in all proportions in water and alcohol. Water, mucilage, dextrine, glucose, and perhaps cane-sugar syrup, are sometimes used as adulterants. The first is detected by the specific gravity of the sample, the others by the brown color produced on mixing the sample with twice its bulk of concentrated sulphuric acid. In the bottlers' laboratory it is very useful. It has also great extracting facilities, and we employ it therefore in some instances as menstruum, preserving the beverages by the other means of preservation.