Numbers 19:3

And ye shall give her unto Eleazar the priest, that he may bring her forth without the camp, and one shall slay her before his face:

Ye shall give her unto Eleazar. He was the second or deputy high priest, and he was selected for this duty because the execution of it entailed temporary defilement, from which the acting high priest was to be preserved with the greatest care. It was led "forth without the camp," in accordance with the law regarding victims laden with the sins of the people, and thus typical of Christ (Hebrews 13:12; also Leviticus 24:14). The priest was to sprinkle the blood "seven times" before-literally, toward or near-the tabernacle; a description which seems to imply either that he carried portion of the blood in a basin to the door of the tabernacle (Leviticus 4:17), or that in the act of sprinkling he turned his face toward the sacred edifice, being disqualified through the defiling influence of this operation from approaching close to it. By this attitude he indicated that he was presenting an expiatory sacrifice, for the acceptance of which he hoped in the grace of God, by looking to the mercy-seat.

Every part of it was consumed by fire, except the blood used in sprinkling; and the ingredients mixed with the ashes were the same as those employed in the sprinkling of lepers (see the notes at Leviticus 14:4) 'The place at which the red heifer was burnt to ashes, in later times, was situated at the east terminus of the double-arched causeway that spanned the Kedron, reaching from Moriah to Olivet, in front of the gate Shushan. It was vaulted below for fear of pollution, like the southeast corner of the temple and the notable places in the city, for raising "clean persons" (Barclay's 'City of the Great King,' p. 63). The purifying liquid was a water of separation - i:e., of "sanctification" for the people of Israel.