340 Literary and Philosophical Society. 



and voltaic electricity to one standard of measurement, 

 and again, when introducing my theory of electro- 

 chemical decomposition, that the chemical decomposing 

 action of a current is constant for a constant quantity of 

 electricity, notwithstanding the greatest variation in its 

 sources, in its intensity, in the size of the electrodes used, 

 in the nature of the conductors (or non-conductors, 307) 

 through which it passes, or in other circumstances.' 



' 705. I endeavoured upon this law to construct an 

 instrument which should measure out the electricity passing 

 through it, and which, being interposed in the course of the 

 current used, should serve at pleasure either as a com- 

 parative standard of effect or as a positive measure of the 

 subtle agent.' 



706. . . . ' Water therefore, acidulated by sulphuric 

 acid, is the substance I shall generally refer to, although 

 it may become expedient in peculiar cases or forms of 

 experiment to use other bodies.' In 843 it is said, ' I 

 expect to find in some salts, as the acetate of mercury 

 and zinc, solutions favourable for this use.' 



In 866, speaking of the decomposition of water, he 

 says, ' For an equivalent of zinc oxidised an equivalent of 

 water must be decomposed.' 



' 918. All the facts show us that that power com- 

 monly called chemical affinity can be communicated to a 

 distance through the metals and certain forms of carbon ; 

 that the electric current is only another form of the forces 

 of chemical affinity ; that its power is in proportion to the 

 chemical affinities producing it ; that when it is deficient 

 in force it may be helped by calling in chemical aid, the 

 want in the former being made up by an equivalent of the 

 latter ; that, in other words, " the forces termed cJtemical 

 affinity and electricity are one and the same." ' 



