Castor oil as a lubricant is in extensive use in some countries. In Australia, which imported 769,362 gal in 1898, its chief use is officially stated to be as lamp oil, and the decline in imports in 1902 to less than 500,-059 gal. is attributed to the substitution of petroleum for the castor oil. It may also be noted that in the Cape of Good Hope, where it is probably largely used for the same purpose, 307,728 gal. were imported in 1902. To a limited extent thisoil is used in the United States. As is well known, the mechanical function of lubricating oils is to form a coating or cushion between rotary surfaces, thus keeping them free from contact and preventing loss of power through friction. To this purpose castor oil, being heavy bodied, viscuous and non-drying, is in most cases well adapted. It is the heaviest of fatty oils, having a density of 0.96 and is particularly adapted to the oiling of fast-moving machinery because the heatgenerated keeps it in a liquid state.