Mucilages are viscid, somewhat tenacious, and generally adhesive liquids, prepared with water as a solvent. As represented by the preparations of the U. S. P. they ate usually solutions of gums, or closely related bodies. The official mucilages gradually decompose and become acid, thinner, and offensive in smell. Such changes may often be checked or entirely prevented by glycerin, alum, or creosote. The majority of the mucilages should be prepared only as wanted.