Complex sentence: Cerate is an unctuous preparation for external application, of a consistency intermediate between that of an ointment and a plaster, so that it can be spread upon cloth without the use of heat, but does not melt when applied to the skin.
Split into simpler sentences: Cerate is an unctuous preparation for external application, of a consistency intermediate between that of an ointment and a plaster. It can be spread upon cloth without the use of heat, but does not melt when applied to the skin.