This section is from the book "The Manufacture Of Liquors, Wines, And Cordials, Without The Aid Of Distillation", by Pierre Lacour. Also available from Amazon: Manufacture of Liquors, Wines, and Cordials, Without the Aid of Distillation.
Are used for clarifying liquids. They consist of bodies or matter that is either lighter or heavier than the fluid. The whole process of fining is mechanical, for when the article used for fining is lighter than the fluid, it floats on the surface, and acts on the principle of the attraction of particles, and these particles subside. On the other hand, when the finings are heavier than the liquid, they fall to the bottom, and carry down with them the heavier impurities. These two points are illustrated in the use of eggs, milk, flour, isinglass, etc, which are lighter than water; and in the latter instance in the use of alum, potash, etc, which are heavier than water.
When flour is used for finings, it is made into a smooth paste before adding.
Liquors are sometimes prepared, on a small scale, for domestic use, by digesting from one to two pints of wheat flour, in five gallons of spirit, for a few days, agitating it daily, and then straining for use. This quantity is usually added to twenty gallons of spirit. The body and taste of liquor containing flour is equal to that given by honey.
Is used in the manufacture of wines and brandies. It is formed by digesting sugar in a solution of acetic acid; and some manufacturers digest or saturate any given quantity of the sugar to the consistence of paste. With water acidulated with sulphuric acid to the strength of common vinegar, the fluid is after digesting for two weeks, evaporated by solar or artificial heat.
This sugar is used for giving a sweetish, acidulous taste to wines, and a vinous taste to brandy. But the same ends can be obtained by the assistance of sugar and acid, without farther preparation.
Is a yellow coloring resinous substance. This gum is soluble in water, forming a yellow opaque emulsion. It is dissolved by alcohol, and a golden yellow tincture results, which is rendered opaque by the addition of water.
So intense is the color of this resin that one part communicates a perceptible yellowness to ten thousand of water.
Is intensely bitter, without being nauseous, and the bitter principle is extracted by water and alcohol. Gentian enters largely into the composition of the different formulas for bitters. See Bitters.
The specific gravity of liquids affords one of the best tests for their purity. The instrument cop monly used for this purpose is Baume's hydrometer. This consists of a glass bulb loaded at one end, and drawn out at the other into a tube on which the scale is marked. That used for alcohol is graduated by loading it until it sinks to the foot of the stem (which is marked zero), in a solution of one part of common salt in nine parts of water. It is then put into water, and the place to which it sinks is marked 10° of the scale, which is constructed from these data.