This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
The addition of 154 grains of bismuth subnitrate to 22 gallons of cider prevents, or materially retards, the hardening of the beverage on exposure to air; moreover, the bismuth salt renders alcoholic fermentation more complete.
Calcium sulphite (sulphite of lime) is largely used to prevent fermentation in cider. About 1/8 to 1/4 of an ounce of the sulphite is required for 1 gallon of cider. It should first be dissolved in a
small quantity of cider, then added to the bulk, and the whole agitated until thoroughly mixed. The barrel should then be bunged and allowed to stand for several days, until the action of the sulphite is exerted. It will preserve the sweetness of cider perfectly, but care should be taken not to add too much, as that would impart a slight sulphurous taste.
To 25 gallons of soft water add 2 pounds of tartaric acid, 25 or 30 pounds of sugar, and a pint of yeast; put in a warm place, and let ferment for 15 days, then add the flavoring matter to suit taste. The various fruit ethers are for sale at any wholesale drug house.