Excerpts from the Preface: Milk fat has always been highly valued as a food, and much attention has been given to its conservation. The usual methods of conserving it have been by the production and storage of butter or of the fat from which the other milk constituents have been removed. The problems of its conservation for any great period of time are principally those related to bacterial growth and enzyme action and to spontaneous chemical reactions with the oxygen of the atmosphere. Butter oil and milk oil are the terms applied in the United States to the milk fat which remains after the curd and water have been removed from butter. Terms used in other countries are: Australia, dehydrated butter; Egypt, samna or samn; England, clarified butter; France, beurre fondu; Germany, Butteröl, Butterschmalz, Flössbutter, geschmolzene Butter, gesottene Butter, Kuhschmalz, Rindschmalz, Schmalz, Schmelzbutter; India, ghee or ghi; Iran, roghan; Switzerland, eingesottene Butter. This bibliography includes material on the preparation, properties, keeping quality, and uses of pure milk fat; the manufacture, preservation, and storage of butter oil; and the conservation of shipping space in shipping it to the Tropics and other places. In the preparation of the annotations, the same terms have been used in referring to butter oil as were used by the author in the work cited.