SUBSTITUTION OF CHLORINE FOR HYDROGEN. 721 



compound may preserve its leading chemical characters, al- 

 though its hydrogen be exchanged for chlorine. Chemists were 

 not prepared for the admission of this equivalency of chlorine 

 and hydrogen from anything observed in inorganic compounds. 

 The two elements seemed, indeed, to be strongly contrasted, 

 chlorine typifying the electro-negative or salt-radical class of 

 elements, and hydrogen belonging, incontestably, to the electro- 

 positive or basyle class with the metals, although not occupying 

 a high place in that class. One equivalent of chlorine being 

 also isomorphous with two equivalents of manganese, to which 

 latter element hydrogen appeared to be related, as a member of 

 the magnesian family, the isomorphous relation to be looked for 

 was one of chlorine with two of hydrogen, and not with one of 

 hydrogen as in oxamethane and chloroxamethane lately com- 

 mented upon. 



But it is to be remembered that no body is absolutely 

 chlorous (electro-negative), or zincous (electro-positive), but 

 only relatively so to certain other bodies. Hence although 

 zincous to chlorine, hydrogen is chlorous to carbon, or hydro- 

 gen is the chlorous constituent of the organic compounds 

 in question. Even among inorganic compounds, we have in- 

 stances of hydrogen discharging the same function, as in the 

 class of phosphuretted hydrogen and arsenietted hydrogen, 

 where 3 atoms of hydrogen are chlorous, and may be 

 replaced by oxygen, chlorine, etc. (In ammonia, on the con- 

 trary, nitrogen appears to be the negative, and hydrogen the 

 positive constituent.) In this way that universal dualism in 

 the constitution of a compound, or distribution of its elements 

 into two opposed classes, conducing to binary combination, 

 which has never ceased to be a recognised doctrine of chemical 

 science, in some form or other, with reference to inorganic com- 

 pounds, is extended also to organic compounds. Such a doctrine 

 which might always have been maintained on abstract grounds 

 appears now to be inevitable from the observed substitutions 

 of chlorine for hydrogen. Hydrogen then being viewed 

 as a chlorous element in such compounds as carburetted 

 hydrogen and olefiant gas, while carbon is the basyle or zincous 

 element, the former element may therefore be replaced by other 

 bodies higher than itself in the scale of salt-radicals, such as 

 chlorine, without any essential derangement of the constitution 



