A portable altar consists of a solid piece of natural stone which must be sufficiently hard to resist every fracture. It must be consecrated by bishop or other person having faculties to do so. By virtue of Facultates Extraordinariae C., 6., the bishops of the United States may delegate a priest. It is inserted in, or placed on, the table of the altar, about two inches from the front edge, and in such a manner that, by its slight elevation above the table, the celebrant can trace its outlines with his hand and thus recognize its location beneath the altar-cloths. In general it should be large enough to hold the Sacred Host and the greater part of the base of the chalice (Cong. Sac. Rit., 20 March, 1846) If the altar is intended for the celebration of Masses at which Holy Communion is distributed, it should be large enough to hold the ciborium also. Five Greek crosses are engraved on it, one near each corner and one in the centre, to indicate the place on which the unctions are made at the consecration. If the cross in the centre should be wanting, the unction must not be omitted, but the omission of this unction would not invalidate the consecration (Cong. Sac. Rit., 2 May, 1892). The table and supports on which the portable altar rests may be constructed of any suitable material, wood or stone, provided they have the proper dimensions. For the portable altar the Greeks generally use the antimensium, a consecrated altar-cloth of silk or linen, after the manner of our corporals. When a church is consecrated, a piece of cloth large enough to form several antimensia is placed on the altar. It is consecrated by the bishop pouring wine and holy chrism on it and stiffening it with a mixture consisting of relics pounded up with wax or fragrant gum. It is afterwards divided into pieces about sixteen inches square, and after the Holy Eucharist has been celebrated on them for seven days these pieces are distributed as occasion requires (Neale, Holy Eastern Church, I, 187).