Syrup boiled from sugar for candies must hang from the end of a spoon to form a thick drop, and long silk-like threads hang from it, when exposed to the air. The syrup is then 238 degrees Fahrenheit, and when a drop is tried in cold water, the water will remain clear and the syrup will form a soft ball and will just keep its shape. Boil a few moments longer, and try in cold water, and if the syrup becomes brittle, and it forms a hard ball, it is at 248 degrees Fahrenheit.
When the syrup begins to discolor it is at 310 degrees, while at 350 degrees it is caramel or burned sugar. The syrup should only be stirred until the sugar is dissolved; if stirred while hot, it will grain or sugar.