CARBON′IC OXIDE

CO. Syn. Protoxide of carbon , Carbon monoxide , Ga′seo us oxide of carbon ; Oxy′dum carbon′icum , L. A gaseous compound of carbon and oxygen, containing le oxygen than is contained in carbonic acid. Prep. 1. From carbonic acid gas pa ed over fragments of charcoal, heated to redne in a tube of porcelain or iron. 2. From crystallised oxalic acid, gently heated with 5 or 6 times its weight of strong sulphuric acid in a gla retort. 3. From ferrocyanide of pota ium in fine powder, and 8 or 10 times its weight of concentrated sulphuric acid, heated together in a gla retort. Obs. All the proce es except the last give a mixture of carbonic acid and oxide. It is therefore nece ary to pa the gas through a caustic alkaline solution or milk of lime to deprive it of carbonic acid. It may then be pa ed over dried chloride of calcium, to deprive it of moisture. It may be collected either over mercury or water, as the latter absorbs very little of this gas. Prop. Carbonic oxide is colourle , inodorous, neutral, inflammable, and irrespirable. It is extremely poisonous, 1% mixed with air being combustion of charcoal in close rooms are now attributed to this gas. The antidotes, ., are the same as for poisoning from inhaling carbonic acid.