One of the methods, which is innocent, consists in adding to the weakened liquor, first, a portion of alum dissolved in water, and then a solution of sub-carbonate of potash. The whole is stirred together, and left undisturbed for twenty-four hours. The precipitated alumine thus produced from the alum, by virtue of the sub-carbonate of potash, acts as a strainer upon the milky liquor, and carries down with it the finely divided oily matter which produced the blue colour of the diluted liquor. Roach, or Roman alum, is also employed, without any other addition, for clarifying spiritous liquors.
"A tun of fine gin 252 gallons "Water 36 ----- "Which added together make 288 gallons
"The _doctor is now put_ on, and it is further reduced with water 19 ----- "Which gives Total 307 gallons of gin.
"This done, let 1 lb. of alum be just covered with water, and dissolved by boiling; rummage the whole well together, and pour in the alum, and the whole will be fine in a few hours."
"_To prepare and sweeten British Gin._[100]
"Get from your distiller an empty puncheon or cask, which will contain about 133 gallons. Then take a cask of clear rectified spirits, 120 gallons, of the usual strength as rectifiers sell their goods at, put the 120 gallons of spirits into your empty cask.
"Then take a quarter of an ounce of oil of vitriol, half an ounce of oil of almonds, a quarter of an ounce of oil of turpentine, one ounce of oil of juniper berries, half a pint of spirit of wine, and half a pound of lump sugar. Beat or rub the above in a mortar. When well rubbed together, have ready prepared half a gallon of lime water, one gallon of rose water; mix the whole in either a pail, or cask, with a stick, till every particle shall be dissolved; then add to the foregoing, twenty-five pounds of sugar dissolved in about nine gallons of rain or Thames water, or water that has been boiled, mix the whole well together, and stir them carefully with a stick in the 133 gallons cask.
"To _force down_ the same, take and boil eight ounces of alum in three quarts of water, for three quarters of an hour; take it from the fire, and dissolve by degrees six or seven ounces of salt of tartar. When the same is milk-warm pour it into your gin, and stir it well together, as before, for five minutes, the same as you would a butt of beer newly fined. Let your cask stand as you mean to draw it. At every time you purpose to sweeten again, that cask must be well washed out; and take great care never to shake your cask all the while it is drawing."