If a "Washita stone has got very hard on the surface and will not sharpen, first face down the stone well by sprinkling sharp sand and water on a thick piece of glass, a smooth flagstone or slab of slate, or an iron plate, and rubbing the hard surface on the sand until a new face has been obtained. Dry sand on a piece of board or a sheet of emery paper will answer the purpose, but wet sand makes the best job. Boiling the stone in soda water will soften it to some extent. The proper oil should be used, so as not to let the stone get hard. Vaseline or half lard oil and half paraffin are suitable. Many oil-stoues are hardened through absorbing the linseed oil used with the white-lead when fixed in the case or for sharpening. The stone should be cemented in the case with glue and red-lead, and the oil should always be wiped off after being used.