This fondant is used for the base of a great variety of candies:
Put the sugar and water into the kettle and place over a hot fire. Stir with a spoon or paddle until the sugar is dissolved. Then wipe down the sides of the kettle with a damp cloth, and see that every granule of sugar is removed from the sides of the kettle, if any are permitted to remain they will make the fondant grainy. When the syrup begins to boil, place the thermometer in and add the vinegar. The kettle must not be moved while the syrup is boiling, and it must never be stirred after it begins to boil. The bulb of the thermometer must be entirely covered, hence the necessity of selecting a kettle in which the syrup will be deep enough to permit the bulb of the thermometer being submerged. If a black scum forms on the surface, wait until it collects in one spot, and then gently remove it with a spoon, being careful not to disturb the syrup.
While the syrup is cooking wipe the marble slab off well with a damp cloth rinsed out of cold water, but do not afterwards dry the slab. Always have the slab in some convenient place so that it is not necessary to carry the syrup a great distance. If a platter is substituted for the slab, it must be made very cold, and should be allowed to set in a cold place. Never move the candy while it is cooling before it is cold enough to work.
When the thermometer registers exactly 240°, lift the kettle from the fire, exercising care not to shake the syrup. Pour it on the slab by holding the kettle down close, beginning at one side and drawing the kettle towards the other side as the syrup is being poured. Do not scrape the last from the kettle, and do not allow the kettle to drain too much. The drippings are likely to sugar, and will make the entire batch grainy.
Allow the syrup to cool until it feels only slightly warm, not cold, to the back of the hand, then remove the bars if the slab is used, and begin to work it with the scraper or broad knife by lifting it from the sides to the center. Keep working it rapidly, and it will soon become smooth and creamy; then a little later it will turn into a solid lump of sugar, and you will find when working a portion between the fingers that it becomes soft and will be perfectly smooth.
If wanted for immediate use, cover it with a damp cloth for about forty minutes, when it can be worked into a very soft, pliable mass. If wanted for future use, it should be put into an earthen jar and covered with a damp cloth. In this way the fondant may be kept for six months or longer without deteriorating. The cloth must be kept damp, and should be rinsed out of cold water two or three times each week. The cloth must not touch the fondant.
This fondant will be a little better if it stands for two or three days before using. Make up a batch of this fondant, keep it on hand, and it can be converted into any one of many different varieties of candy in a few minutes, or it may be used for icing. If a batch of the fondant should be spoiled in making, it can be broken up and used instead of other sugar in one of the fudge recipes.
Warm some of the prepared fondant in the double boiler, then beat into it water, milk, cream, or the white of an egg, until it is thin enough to spread. Do not make the fondant too hot, or when spread on the cake it will become too hard to cut nicely or before spreading the icing on the cake, add some broken nut meats or add chocolate to the plain fondant icing.