From "Aunt Babette's Cook Book, Foreign and Domestic Receipts for the Household" by Aunt Babette, published by Bloch Publishing and Printing Company, Chicago, c. 1889
A brass kettle, if kept perfectly clean, is best for boiling sugar in for confectionery. Dissolve two pounds of white sugar in one pint of water and place this in the kettle over a slow fire for a quarter of an hour. Pour into it a small quantity of gelatin and gum arabic dissolved together. Skim off at once all the impurities that rise to the surface. If you allow the syrup to boil a few moments longer you will have what is called "Rock Candy."
To make other candies, bring the syrup very carefully to such a degree of heat that the "threads" which drop from the spoon when raised into cold air will snap like glass. When this desired stage is reached, add a teaspoonful of vinegar or cream of tartar to prevent granulation, and pour it into pans. To make stick candies, pull and roll into shape with buttered hands.