Further exposure would by degrees eliminate the aqueous portion by evaporation, and the progress of decomposition would tend to free the gases in the other constituents, and thus still further to diminish the mass. But no experiments, instituted by physicists, can compare, in time at least, with the instances presented to us in the vases of the catacombs. There, traces on the glass still show clearly to what level the blood, or at least the clot, originally reached; and we see what has remained after a lapse of sixteen hundred years--a crust of dry reddish powder adhering to and coating the sides and bottom of the vessel. Boldetti, however, mentions three instances in which such ampullæ were found in the catacombs containing a residuum of the blood still thick and slightly liquid. And, if we are not mistaken, something similar may be seen in some other vials preserved here and there, and held to contain a portion of the blood of certain martyrs. The early Christians of Italy gave up the old Roman custom of incremation, or burning the bodies of the dead, and adopted instead the Eastern rite of sepulture. In some instances, at least, they seem to have used spices and ointments, as the Jews and Eastern nations generally did; and some of them might even have had a knowledge of the antiseptic preparations used by the Egyptians. They never prepared the dead as mummies, but they may at times have put some antiseptic ingredient into the blood, tending by its chemical action somehow to retard the escape of the water and the decomposition of the mass. If this were really done or not, we believe modern science cannot decide; and the historical evidence is not clear.