Stearic acid is a usually a most common chemical, used in process industries , and it is quite expensive too. So it is not a difficult task for a a chemical engineer to prepare stearic acid locally at a very cheap cost. Just buy a natural soap bar ( try to get the most cheapest among all), this reaction will only work with the natural soap bar, so try to do the reaction on a little piece of soap initially. Dissolve the natural soap bar in hot water completely. Add food vinegar (but the food vinegar is needed in higher volume, so you can add any...