These are the pharmacological agent which when administered externally , bring loss of all five modalities of sensation with reversible loss of consciousness. Light Sound Taste Temperature/ Pressure 5. Smell Diethyl Ether : Physical Properties : Colourless ,volatile liq. With pungent odour. Boil at 350 C , vapor irritant. Exposed in air , moisture or light , it get convert to ether peroxide and acetic aldehyde , which is irritant in nature Highly explosive. Stored in umber colour glass bottle covered with black paper. 10-15 % in inspired air is sufficient for induction of anaesthesia which can be maintained but 4-5 % concentration. Pharmacological Action Only a major portion of ether is oxidized in the body and is eliminated through the lungs . The miscibility of drug with body fluid requires large amount of drug for induction of anesthesia and induction is slow. Ether irritate the respiratory track and enhance the mucosal secretion. Drug may causes laryngospasm ,Ether is also known to increase heart rate, blood pressure and blood sugar. It also causes peripheral vasodilation . Ether depresses myocardial contractility. Advt / Therapeutic effect : Safest agent in wide margine , also unexperienced hand. 90 mg/100 ml blood Indused anaesthesia 190 mg/100 ml bloodCauses respiratory Track Not only safe anaesthetics but good analgesic also. It does not interfere with uterine contractility. Does not have any effect on liver , kidney , and heat. No special or complicated apparatus if required. Eeconomical agent .