ACETYLENE GAS
This gas has a peculiar odour of geranium. It is a product of the incomplete combustion of hydrocarbons, and is formed when lamps or gas jets are burned with insufficient air, e.g. a Bunsen burner which has “lighted back,” also from the use of oil stoves, and gas cooking and heating apparatus. It is used for illumination, and formed by the action of water on calcium carbide. It forms a highly explosive mixture with air. It is not a potent poison. Continued exposure to it causes anæmia, malnutrition, and nervous symptoms. On animals it produces narcosis. It does not combine with hæmoglobin, but acts as an indifferent gas.
NITROGEN MONOXIDE,
NITROUS OXIDE
This is known as laughing gas; it has a sweetish taste and smell. When breathed in small quantities it produces tingling sensations and induces laughter, hence its name. When breathed for anæsthetic purposes the skin becomes livid, the blood pressure raised, and unconsciousness follows. It acts first upon the higher nerve centres, then upon the spinal cord, medulla, and heart. If pushed too far it causes death by asphyxia. In ordinary use for anæsthesia, the latter is rapidly produced, and recovery follows quickly when the administration is stopped. It has peculiar effects upon certain people, who may not only show the symptoms of hilarity, but, in some cases, become extremely violent.