Adventures of Superman - S4 Ep 9 "Dagger Island"

Lois Lane is chloroformed while focused on talking with Clark Kent over the phone. The bad guy approaches her slowly from behind and clearly soaks a cloth. The bad guy then chloroforms Lois Lane, leaving her slumped over the desk. He then releases poison gas in an attempt to kill her.
Luckily Superman arrives just in time to save her. Some good sleepy dialogue follows.