a term in the Roman surgery, about the meaning of which physicians and commentators are greatly divided; some taking it for the needle, and others for the thread.

ACICULÆ, the small spikes or prickles of the hedgehog, echinus marinus, &c.

ACIDS, substances which give a sour, sharp, or tart taste. Among the chemists, the acid salts are distinguished into the nitrous, vitriolic, muriatic, and vegetable. See Chemistry, title, Of acids.

Acids, in the materia medica, are such medicines as possess an acid quality; such as vinegar, spirit of vitriol, &c. These being powerful antiseptics, are effectual good in all putrid and malignant diseases, and, by their cooling virtue, are no less efficacious in feverish and inflammatory cases.