An additional explanation for the second gas effect: a concentrating effect.
D000769:Anesthesia, Inhalation; D000777:Anesthetics / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D003521:Cyclopropanes / Q000008:administration & dosage / Q000378:metabolism; D004285:Dogs; D005030:Ethylenes / Q000008:administration & dosage / Q000378:metabolism; D006221:Halothane / Q000008:administration & dosage / Q000378:metabolism; D008168:Lung / Q000502:physiology; D009609:Nitrous Oxide / Q000008:administration & dosage / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000032:analysis / Q000378:metabolism*; D012119:Respiration
D000777:Anesthetics; D003521:Cyclopropanes; D005030:Ethylenes; D009609:Nitrous Oxide; D006221:Halothane