392 PRINCIPLES OF CHEMISTRY 



breathed it acts as a strong poison, because it is absorbed by the 

 blood ; 30 this explains the action of charcoal fumes, the products of 

 the incomplete combustion of charcoal and other carbonaceous fuels. 

 Owing to its faculty of combining with oxygen, carbonic oxide acts as a 

 powerful reducing agent, taking up the oxygen from many compounds 

 at a red heat, and being itself transformed into carbonic anhydride. 

 The reducing action of carbonic oxide, however, is (like that of 

 hydrogen, Chapter II.) naturally confined to those oxides which easily 

 part with their oxygen as, for instance, copper oxide whilst the 

 oxides of magnesium or potassium are not reduced. Metallic iron itself 

 is capable of reducing carbonic anhydride into carbonic oxide, just as 

 it liberates the hydrogen from water. Copper, which does not de- 

 compose water, does not decompose carbonic oxide. If a platinum 

 wire heated to 300, or spongy platinum at the ordinary tempera- 

 ture, be plunged into a mixture of carbonic oxide and oxygen, or of 

 hydrogen and oxygen, the mixture explodes. These reactions remind 

 one exceedingly of those which are peculiar to hydrogen. The follow- 

 ing important distinction, however, exists between them, namely : the 

 molecule of hydrogen is composed of H 2 , a group of elements divisible 

 into two like parts, whilst, as the molecule of carbonic oxide, CO, 

 contains unlike atoms of carbon and oxygen, in none of its reactions 

 of combination can it give two molecules of matter containing its 

 elements. This is particularly noticeable in the action of chlorine on 

 hydrogen and on carbonic oxide respectively ; with the former chlorine 

 forms hydrogen chloride, and with the latter it produces the so-called 

 carbonyl chloride, COC1 2 ; that is to say, the molecule of hydrogen, H 2 > 

 under the action of chlorine divides, forming two molecules of hydro- 

 chloric acid, whilst the molecule of carbonic oxide entirely enters 

 into the molecule of carbonyl chloride. This characterises the so- 

 called diatomic or bivalent reactions of radicles or residues. H is a 

 monatomic residue or radicle, like K, 01, and others, whilst carbonic 

 oxide, CO, is an indivisible (without decomposition) bivalent radicle, 

 equivalent to H 2 and not to H, and therefore combining with X 2 and 



carbonic oxide gives carbonic anhydride and hydrogen, but hydrogen with oxygen givea 

 hydrogen peroxide (Chapter VII. p. 805), which with carbonic oxide forms carbonic 

 anhydride and water. The water, therefore, is renewed, and again serves the same 

 purpose. But it may be that here it is necessary to acknowledge a simple contact 

 influence. 



50 Carbonic oxide is a very quick poison, because it is absorbed by the blood in the 

 same way as oxygen. In addition to this, the spectrum of the absorption of the blood 

 changes so that by the help of blood it is easy to detect the slightest traces of carbonic 

 oxide in the air. M. A. Kapoustin found that linseed oil (and therefore oil paints) are 

 capable of giving off carbonic oxide while drying (absorbing oxygen). 



