Chevreul's scientific work covered a wide range, but he is best known for the classical researches he carried out on animal fats, published in 1823 ("Recherches sur les corps gras d'origine animale"). These enabled him to elucidate the true nature of soap; he was also able to discover the composition of stearin, a white substance found in the solid parts of most animal and vegetable fats, and olein, the liquid part of any fat, and to isolate stearic and oleic acids, the names of which he invented. This work led to important improvements in the processes of candle-manufacture.