You don't want to measure lye-you want to use the whole container. If your container is not this size, then scale the recipe up or down accordingly. Leftover lye is a serious disposal problem. What I find I have to do is reserve it, because they normally don't keep the fat after they've cut up their cow. The recipe will work equally well with other animal fats to produce a similar result.
Coconut oil yields a softer, quick-lathering soap.
Unfortunately, these oils are sensitive to air and light, and soap made from cooking oils will spoil in a few weeks unless it is refrigerated. Volatile fragrance oils, also called essential oils, are highly concentrated scent ingredients. The amount that you should use depends on how fragrant you want the soap to be. Let this mixture sit for a few weeks, stir- ring it every day, then heat in a double boiler for 10 minutes, then cool and strain the oil. The soap works just fine with no fragrance at all, and many people prefer it that way.