GENERAL PRINCIPLES OF DEFINITE ELECTROLYTIC ACTION. Ill 



present themselves at this, the opening of a new view of electro-chemical action ; not 

 being held up as obstructions to those who may be engaged in rendering that view 

 more and more perfect, but laid aside for a while, in hopes that their perfect and 

 consistent explanation will finally appear. 



822. The doctrine o^ definite electro-chemical action just laid down, and, I believe, 

 established, leads to some new views of the relations and classifications of bodies asso- 

 ciated with or subject to this action. Some of these I shall proceed to consider. 



823. In the first place, compound bodies may be separated into two great classes, 

 namely, those which are decomposable by the electric current, and those which are 

 not. Of the latter, some are conductors, others non-conductors, of voltaic electricity*. 

 The former do not depend for their decomposability, upon the nature of their elements 

 only ; for, of the same two elements, bodies may be formed, of which one shall belong 

 to one class and another to the other class ; but probably on the proportions also 

 (697.)- It is further remarkable, that with very few, if any, exceptions (414. 691.), 

 these decomposable bodies are exactly those governed by the remarkable law of con- 

 duction I have before described (394.) ; for that law does not extend to the many 

 compound fusible substances that are excluded from this class. I propose to call 

 bodies of this, the decomposable class. Electrolytes (664.). 



824. Then, again, the substances into which these divide, under the influence of the 

 electric current, form an exceedingly important general class. They are combining 

 bodies ; are directly associated with the fundamental parts of the doctrine of chemical 

 affinity ; and have each a definite proportion, in which they are always evolved during 

 electrolytic action. I have proposed to call these bodies generally ions, or particu- 

 larly anions and cations, according as they appear at the anode or cathode (665.) ; 

 and the numbers representing the proportions in which they are evolved electro- 

 chemical equivalents. Thus hydrogen, oxygen, chlorine, iodine, lead, tin, are ions ; 

 the three former are anions, the two metals are cations, and 1, 8, 36, 125, 104, 58, are 

 their electro-chemical equivalents nearly. 



825. A summary of certain points already ascertained respecting electrolytes, ions, 

 and electro-chemical equivalents, may be given in the following general form of pro- 

 positions, without, I hope, including any serious error. 



826. i. A single ion, i. e. one not in combination with another, will have no ten- 

 dency to pass to either of the electrodes, and will be perfectly indifferent to the pass- 

 ing current, unless it be itself a compound of more elementary irnis, and so subject 

 to actual decomposition. Upon this fact is founded much of the proof adduced in 

 favour of the new theory of electro-chemical decomposition, which I put forth in a 

 former series of these Researches (518. &c.). 



827. ii. If one ion be combined in right proportions (697.) with another strongly 



* I mean here by voltaic electricity, merely electricity from a most abundant source, but having very small 

 intensity. 



