CAUSSIN, Nicholas, surnamed the Just, a French Jesuit, born at Troyes in Champagne, in 1583. He taught rhetoric in several of the colleges of the order, and as a preacher gained great reputation. This procured him the preferment to the office of confessor to Louis XIII.; but he discharged his duties too faithfully for Cardinal Richelieu, who procured his dismissal. He was exiled for some time, but afterwards returned, and died in the Jesuits' convent at Paris in 1651. The most popular of his works, which are numerous, is that entitled La Cour Sainte, 5 vols. 12mo.

CAUSTICS (καυστικός from καίνος, savour, to burn), certain substances which when applied to the skin corrode and destroy its texture. Of these there are the common stronger caustic, the common milder caustic, the antimonial caustic, and the lunar caustic or fused nitrate of silver. See Cauterity.

Caustic Curve, in the higher geometry, a curve formed by the concourse or coincidence of the rays of light reflected from some other curve. See Optics.

CAUTERY, in Surgery, a burning or searing, as of morbid flesh, by the application of caustic medicines, or by a hot iron. The first is termed potential cautery, the latter actual cautery.

CAUTIONER, in Scots Law, one who becomes bound for another to the performance of any deed or obligation.