Formerly castle-soap. [from Castile, a province of Spain, in which the soap was originally made.]
A fine hard soap made with olive-oil and soda. There are two kinds, the white and the mottled. Called also Spanish soap.
1616. B. Jonson, Devil an Ass, V. iii. Foam at the mouth, A little castle-soap Will do ’t to rub your lips.
1641. French, Distill. (1651), v. 153. You may make candles of Castle-sope.
1710. Lond. Gaz., No. 4674/7. Castile marbled Soap.
1712. Addison, Spect., No. 458, ¶ 1. A word or two upon the present Duties on Castle-soap.
1766. Entick, London, IV. 86, note. White soap in hard cakes, called Castile soap.
1866. Mrs. Riddell, Race for W., xxix. Like Castile soap … generally mottled.
