COMMENTARY. Our author’s account of the _Caries_ or _Rot_ of wood is taken from Dioscorides, who recommends it in the same cases as Carbo ligni is now applied, namely, to ulcers, but more especially spreading ulcers. (i, 143.) It is the Lignorum marcor of the Arabians, who recommend it in the same cases as the Greeks. See Avicenna (ii, 2, 617); Serapion (c. 48.) Σάπων, Sapo, _Soap_, is possessed of detergent powers. * * * * * COMMENTARY. The first author, we believe, who makes mention of _Soap_ is Pliny. He calls it an invention of the Gauls. It is made, he says, of suet and ashes. (H. N. xxviii, 51.) Aretæus likewise calls it a Gallic composition, prepared from soda, and used for cleansing clothes. He recommends it as an application to the skin in elephantiasis. (De Curat. Morb. Chron. ii, 13.) Serapion praises it as an application to abscesses. The only Greek authority which he quotes under this head is Paulus. (De Simpl. 368.) See also Avicenna (ii, 2, 650); Rhases (Cont. l. ult. i, 609, ii, 628); and Ebn Baithar (ii, 119.) One of Baithar’s Arabian authorities commends soap in leprosy and scabies; also in favus and the cutaneous diseases of the scalp. Ebn Baithar further gives a very curious account of the process of dyeing the beard by means of a mixture of soap and sandyx. This was a very ancient use of soap, and is frequently alluded to by the classical authors. (Ovid. Ars. Amand. iii, 163.) This subject is treated of very ingeniously by Beckmann in his ‘History of Inventions.’ The author, however, is mistaken in supposing that there is no mention of soap in the works of Galen, with the exception of that work ‘De Simplicibus,’ universally admitted to be spurious, whereas Galen frequently makes mention of it in works about the authenticity of which there has never been any question. As for example, (Meth. Med. viii); (De Comp. med. sec. loc. T. ii, 225.) In the latter passage he makes distinct mention of Gallic soap. Σαρκοκόλλα, Sarcocolla, is the tear of a Persian tree, being emplastic and desiccative without pungency, and therefore it agglutinates wounds. * * * * *