See Achicolum.

Fornix, (from the Arabic term forn,) is part of the corpus callosum in the brain, and called from a distant resemblance that it hath to the arches of vaults. Seecerebrum and Lyra. Fortis, Aqua, is a name which artists have given to the nitrous acid, from its dissolving power. Niirum. It is also called Elephas. Fossa, (from fodio, to dig). A ditch. In ana-tomy it is synonymous with fossa navicularis. Fossa navjcularis. See Auricula. Fossa magna. The interior cavity of the pudendum muliebre, obvious on a separation of the labia. Fossa pituitaria. See Sella turcica. Fossilis Sal. See Gemmae sal. Fossilus. A name of the tibia, and of the fibula. Fotus, or Fomentatio, (from foveo, to c/ie-risk,) embroche. Thermasma, chiliasma. To foment, is to cherish with heat, to bathe with warm liquors; though dry powders, parched barley, or oats in bags, liquids in a bladder, or in a sponge, applied warm to the diseased parts, are also named fomentations. They are usually, however, fluids externally applied, as warm as the patient can bear them, in the following manner: two flannel cloths are dipped in the heated liquor, one of which is wrung as dry as the necessary speed will admit, then immediately applied to the part affected: it lies on until the heat begins to lessen, and the other is in readiness to apply when the first is removed. This alternate application is continued fifteen or twenty minutes, and repeated two or three times a day. If there is a wound, it is usually defended by a piece of thin cloth.

Every intention of relaxation and soothing by fomentations may be answered by warm water alone; but when discutients or antiseptics are required, the suitable ingredients must be added. Fomentations of warm water are not, however, employed as relaxants only. They are applied with advantage to contracted limbs, to indolent abscesses, foul ulcers, and sometimes to bruises. In these instances the stimulating power of the heat is useful to excite the action of the torpid vessels. See Balneum.

The common fomentation is a decoction of camomile flowers, in the proportion of an ounce to a quart, and it is often preferred to the decoctum pro fomento of the London College. Fornix 3816 . Abrotani exsiccati; absin-thii maritimi exsiccati, camaemeli exsiccati, singulorum, p. i. foliorum lauri exsiccatorum, p. ij. aquae distil-latae m. lb 6. paulisper coque et cola. The preference is given to the former, on accouut of its being less complicated, and that little benefit is derived from the numerous ingredients.

The degree of heat should never exceed that of producing a pleasing sensation, except when employed as a stimulus: great heat produces effects very opposite to that usually intended by the use of fomentations. Fotus anodynus. See Anodynum. Fovea, (a fovea, for fodio, to dig). In anatomy it is the sinus of the pudendum muliebre. In the bath rooms it is a sudatory for receiving one or both the legs, in order to sweating.