METHODS OF OBTAINING GAZHOl’S OXID OF CARBON. 25 ()
zeous oxid of carbon. Those oxids which retain their oxigenmost obstinately yield most of the latter, and those which partwith it readily afford most carbonic acid gas. The latter comesover chiefly at the beginning and the former towards the end ofthe process.
Inferences. ..From these various facts there can no longerremain any doubt but that the carbonic acid, under certain ele-vations of temperature, may be decomposed by any fixed sub-stance having a considerable affinity with oxigen, and that withregard to the metals, those succeed the best which have thegreatest attraction for acids or oxigen, as is the case with zinc.Upon the whole we may conclude that there are but two distinctcombinations of carbon and oxigen capable of assuming andmaintaining the form of gas. For although the gazeous oxid ofcarbon may be obtained in a great variety of ways, by directcomposition, as well as during the decomposition of the carbonicacid, yet when pure, it is exactly the same substance, having thesame specific gravity, requiring the same portion of oxigen tosaturate it, and producing the same quantity of carbonic acid, asMr. Cruikshank* has sufficiently proved experimentally to whatthe different results of impure gases are owing.
One hundred cubic inches of gazeous oxid of carbon, obtainedfrom iron filings and carbonate of lime or barytes, previously ig-nited, according to Mr. Cruikshank weigh 30 grains. They re-quire 40 cubic inches (13*6 grains) of oxigen for saturation,and form Q2 cubic inches (43.2 grains) of carbonic acid, and nowater is produced. Hence the 100 cubic inches of gazeous oxidof carbon consist of 21 + oxigen 8.6 carbon.
One hundred cubic inches of the same gas obtained from char-coal and metallic oxids, weigh 30 grains. They require 44 cubicinches (15 grains) of oxigen for saturation, and yield /6 cubicinches (3 5.5 grains) of carbonic acid, and afford (on account ofthe hidrogen contained in the charcoal) about 8 grains of water
R 2
Nicholson’s Journal, Sep. i8oi, p. aio.