Valance \Val"ance\, n. [Perhaps fr. OF. avalant descending, hanging down, p. pr. of avaler to go down, let down, descent (cf. Avalanche); but probably from the town of Valence in France.]

1. Hanging drapery for a bed, couch, window, or the like, especially that which hangs around a bedstead, from the bed to the floor. [Written also valence.]

Valance of Venice gold in needlework. --Shak.

2. The drooping edging of the lid of a trunk. which covers the joint when the lid is closed.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Valence \Va"lence\, n. [From L. valens, -entis, p. pr. of valere to have power, to be strong. See Valiant.]

(Chem.) The degree of combining power of an atom (or radical) as shown by the number of atoms of hydrogen (or of other monads, as chlorine, sodium, etc.) with which it will combine, or for which it can be substituted, or with which it can be compared; thus, an atom of hydrogen is a monad, and has a valence of one; the atoms of oxygen, nitrogen, and carbon are respectively dyads, triads, and tetrads, and have a valence respectively of two, three, and four.

Note: The valence of certain elements varies in different compounds. Valence in degree may extend as high as seven or eight, as in the cases of iodine and osmium respectively. The doctrine of valence has been of fundamental importance in distinguishing the equivalence from the atomic weight, and is an essential factor in explaining the chemical structures of compounds.

Source: Webster's Revised Unabridged Dictionary (1913)