Dr. W. Odling on the Doctrine of Equivalents. 39 



• H H Water. 



CI CI Hypochlorous anhydride. 

 H CI O Hypochlorous acid. 

 K CI O Hypochlorite of potash. 

 K H O Hydrate of potash. 

 K K Oxide of potash. 

 H^ S Sulphydric acid. 

 H^ S^ Bisulphide of hydrogeu. 

 Fe^S Sulphide of iron. 

 Fe* S^ Bisulphide of iron. 



CF S Sulphide of chlorine (chloride of sulphur). 

 CF S^ Bisulphide of chlorine (dichloridc of sulphur). 

 C^H^Cl Chlor-ethyle. 

 C^H^H Hydr-ethyle. 

 C^H^Zn Zinc-ethyle. 

 CF Sb Chloro-stibamine. 

 H^ Sb Stibamine. 

 Ag^Sb Stibio-silver. 

 That we are not acquainted with a very great number of such 

 instances of replacement^ appears to arise from the circumstance 

 that, in few hydrogenized bodies, can the hydrogen be replaced 

 with equal facility by chlorine and by potassium. As a general 

 rule, we find that the facility of replacement by potassium is 

 directly, by chlorine inversely, as the degree of oxidation of 

 the compound under examination, and consequently that the 

 same body does not always afford both chlorine and metal 

 derivatives. Chlorine and potassium are two elements possessing 

 in the highest degree those opposite properties which we de- 

 nominate chlorous and basylous respectively. They are, how- 

 ever, connected by a great number of intermediate links, and 

 constitute, as it were, the extremities of a very long chain. 

 From the antagonism in properties possessed by chlorous and 

 basylous elements, we find that the correspondence in properties 

 between chlorous and basylous derivatives of the same hydro- 

 genized body is confined within narrow limits; it is, however, 

 manifested in the phainomcna of double decomposition, thus* : — 

 C7H«02 + HKO = C7H5KO^ + H20 

 C7n«02 + HC10 = C7H5C10- + H20. 

 The chloro-bcnzoicacidproducedis not uniform in composition. 

 In the instances of equivalent substitution hitherto adduced, 

 the replacement has been effected by interchange of atom for 

 atom. But we frequently find that the atoms of different 

 elements have difi'crcnt representative values; and moreover, 

 * A very excellent illustration of this relation has recently been aftbrded 

 by llofmuun, thus : — 



;^Et Zn + V CP = ;5Zn CI + P Et' 

 .•5Et Ik + PH-;'=;JlIf; Br-(- P Et\ 



