396 CARBONIC OXIDE. 



troversy respecting it was for some time maintained, but its true na- 

 ture was soon pointed out, by the late Mr. Cruickshanks, of Wool- 

 wich, England ;* Clement and Desormesf completed the demon- 

 stration, and the refutation of the ideas of the associated Dutch 

 chemists and others, who took it for a variety of carburetted hydro- 

 gen gas-t 



2. PREPARATION. All the processes mentioned below, are in- 

 structive. They all shew, (that under (g) excepted,) the formation of 

 an oxide of carbon, either by the combination of 1 equivalent of oxy- 

 gen with 1 of carbon, or by the removal of 1 equivalent of oxygen 

 from carbonic acid, leaving 1 of carbon and 1 of oxygen in combina- 

 tion. To the former belong the processes (a) (e), and (/.) to the 

 latter (6), (c), and (d) ; (g) is peculiar. 



(a.) Heat white oxide of zinc with J of charcoal powder or iron 

 filings; 



(6.) Or iron filings with an equal weight of chalk, previously heat- 

 ed moderately red. 



(c.) Or dry carbonate of lime or of baryta^ with } charcoal pow- 

 der, previously ignited; or heat the same carbonates with J or J of 

 dry iron filings or metallic zinc. 



(d.) Bypassing carbonic acid over charcoal or iron filings, ignited 

 in an earthen or perhaps iron tube.|| 



(e.) Heat equal parts of the scales of iron with dried charcoal 

 powder. 



(jf.) Manganese, after ceasing to give oxygen by heat alone, mix- 

 ed with an equal weight of charcoal, previously ignited. IF 



(g.) Still another process has been introduced, by mixing salt of 

 sorrel 1 part (bin-oxalate of potash) with 5 or 6 of sulphuric acid, 

 and heating the mixture to ebullition in a retort ; decomposition of 

 the oxalic acid ensues, and carbonic acid and carbonic oxide are 

 evolved in equal measures ; the former is easily absorbed by a caustic 

 alkali or by lime water, and leaves the latter pure. The sulphuric 

 acid is not decomposed ; it remains limpid, and operates by uniting 



* Nich. Jour. 4to, Vol. V. t Ann. de Chim. Vol. XXXIX. 



t Ann. de Chim. XXXIX, 26, and XLIII. 



The dry carbonate of baryta and dry iron filings give the purest gas, and nearly 

 free from carbonic acid. The process with oxide of zinc and iron filings, is one ol* 

 the best, and affords abundance of gas which is easily purified by washing it with 

 caustic alkali or lime water. 



|| See Nich. Jour. Vol. II, p. 116, for BarueFs apparatus. 



IT Any carbonate, that will sustain ignition, without decomposition, will give car- 

 bonic oxide, if heated with half its weight of iron filings or charcoal ; iron is of 

 course, oxidized by the oxygen withdrawn from the carbonic acid which undergoes 

 decomposition, giving up just half its oxygen; and charcoal is turned into carbonic 

 oxide by the same process. The carbonates of strontia, soda, potassa and lithia, 

 utay be employed in addition to those that have been named, and the oxide of lead 

 aad copper may be used with charcoal, as well as the oxide of zinc or iron. 



