These are medicines which, through their cohesive affinity, absorb certain acid, irritant, and poisonous substances which may happen to be present in the alimentary canal; and so hold them attached that they are incapable of exercising their injurious influence on the mucous membrane, and perhaps are rendered incapable of being taken into the system, or at least are taken up with greater difficulty. The only substance belonging to this class which I shall notice is charcoal.