LIQUID ELEMENTS OF THE VOLTAIC CIRCLE. 221 



The positive metal which is exposed to the exciting fluid 

 always acts in one way, displacing the basyle and combining 

 with the salt-radical of that body ; in the manner the zinc has 

 been seen to liberate hydrogen and combine with chlorine, when 

 hydrochloric acid is the exciting fluid. The positive metal is 

 thus substituted for a similar basyle in a pre-existing saline 

 compound. That metal may dissolve in another manner, by 

 uniting directly, for instance, with free chlorine or iodine in 

 solution, but then no polarization follows. A chain of particles 

 of chlorine may extend from the zinc to the associated negative 

 metal, but they are not polarized, as a chain of hydrochloric acid 

 particles would be in the same circumstances. The particles of 

 these free elements appear to be incapable of that polar condi- 

 tion, having chlorous affinity on one side and zincous on the 

 other, of which both the solid and liquid constituents of the 

 voltaic circle must be susceptible. Judging from the unifor- 

 mity in composition of exciting liquids, their susceptibility of 

 polarization depends on their consisting of an atom of basyle 

 and an atom of salt-radical, which may become respectively the 

 locus of zincous and chlorous polarity. Or as chlorine belongs 

 to the salt-radicals and zinc to the basyles, and each may be 

 taken to represent its class, the exciting bodies may be said to 

 be capable of having a chlorous and zincous pole, because they 

 consist of a chlorous and zincous element. Such particles may 

 be looked upon as in a state of tension when forming a part of 

 a polar chain, each about to divide into its chlorous and zin- 

 cous atoms. Mr. Faraday has established that all exciting 

 liquids are binary compounds of single equivalents of salt- 

 radical and basyle, or pro to- compounds^ such as hydrochloric 

 acid itself, proto- chloride of tin, &c. Other saline bodies which 

 are per- compounds, such as bichloride of tin, are not exciting or 

 polarizable, because, as it may be supposed, they are not natu- 

 ally resolvable into a chlorous and zincous atom, but into a 

 chlorous atom and another salt ; the bichloride of tin, for 

 instance into chlorine and proto-chloride of tin. For such 

 saline bodies may all be ternary compounds and consist of a 

 binary compound united with an additional quantity of salt- 

 radical. Certain protocompounds, also, which are deficient in 

 the saline character, are not polarizable, such as chloride of 

 sulphur, protochloride of phosphorus and protochloride of 

 carbon. These bodies do not contain a proper basyle. 



