Rube sides of kettle with part of the butter. Put sugar, syrup, water and salt into kettle and cook to hard ball stage, 260 degrees. (Use candy thermometer, temperature is important). For a dry taffy, increase heat 2 degrees, for a chewy taffy, decrease heat 2 degrees. Add butter and vanilla when the taffy reaches temperature. Pour out taffy onto a cold buttered cookie sheet. Pull the taffy with the ends of your fingers, which have been buttered slightly. Pull and fold, but do not squeeze. Pull and fold and pull and fold until taffy reaches taffy like state. You can use different extracts other than vanilla for other flavors.