Cook together in a copper pan (or a pan not lined with tin) until the mixture reaches th 'ball'stage. (To test the stage of the cooking by finger, dip the thumb and index finger into cold water, then into the mixture, bringing the 2 fingers together and dipping them again into water. This should be done quickly to avoid burning. The mixture forms a small ball that can be rolled with the tip of the fingers) Pour this cooked sugar onto an oiled marble slab, keeping it at an even thickness of 2/3 in., using 4 oiled rulers to make a framework. Let cool and cut.

Source : The Art of French Cooking Posted by: Rina de Jong