Many lamp oils today are comprised of materials known as paraffin or kerosene. Animal fats are no longer used as fuels. However, because lamp oils made by different manufacturers tend to have slightly different mixtures of chemicals, it's impossible to describe them with only one chemical formula.
Although whale blubbers and processed animal fats were once the norm in manufactured lamp oils, changes in law over the last hundred years have required companies to explore other, non-animal-related sources of their oils. Today, kerosene and parrafin, which are made by mixing various long-chain hydrocarbons, dominate the industry due to their low cost of manufacture, cleanliness of burning and minimal adverse effects to consumers.