Take a pound of castile, or any other nice old soap; scrape it in small pieces, and put it on the fire with a little water-- stir it till it becomes a smooth paste, pour it into a powl, and when cold, add some lavender water, or essence of any kind-- beat it with a silver spoon until well mixed, thicken it with corn meal, and keep it in small pots closely covered-- for the admission of air will soon make the soap hard."
Here is something you could try with any old, discolored, or small pieces of hard soap you have lying around but don't want to throw away. Be careful when melting it over heat, and don't be sparing with the water-- remember most liquid soaps are at least 50%-75% water. The "essence" to add can be any essential oil that is safe to use on skin. Lavender is a favorite, but you could also try lemon, cinnamon, or anything else you like. Corn meal is easily obtained from the grocery store, and fortunately we now have screw-on containers and the like that will more easily prevent evaporation than anything available to the 1838 author.
Source: The Virginia Housewife by Mary Randolph, 1838