In the early literature, especially that relating to the prairies, there are numerous brief references to the extraction of oil or grease from bones by boiling. For instance, W. R. Gerard in his article on pemmican in Bulletin 30 of the Bureau of American Ethnology says: “Sweet pemmican is a superior kind of pemmican in which the fat used is obtained from marrow by boiling broken bones in water.” Wissler in his paper on the Material Culture of trte Blackfoot Indians says: “Marrow fat was obtained by boiling cracked bones and skimming the floating fat from the top of the kettle with a dipper made of horn.” A still earlier reference to the same process is found in Schoolcraft's History, Condition and Prospects of the Indian Tribes (Vol. 4, p. 107) in which he says: “The men break bones, which are boiled in water to extract the marrow to be used for frying and for other culinary purposes. The oil is then poured into the bladder of the animal, which contains when filled about twelve pounds, being the yield of the marrow bones of two buffaloes.”