EPOCH OF DAVY AND FAKADAY. 303 



which :s naturally associated with the elements of the grain of water, 

 endowing them with their mutual affinity. 



Many of the subordinate facts and laws which were brought tc 

 light by these researches, clearly point to generalizations, not included 

 in that which we have had to consider, and not yet discovered : such 

 laws do not properly belong to our main plan, which is to make our 

 way up to the generalizations. But there is one which so evidently 

 promises to have an important bearing on future chemical theories, 

 that I will briefly mention it. The class of bodies which are capable 

 of electrical decomposition is limited by a very remarkable law : they 

 are such binary compounds only as consist of single proportionals of 

 their elementary principles. It does not belong to us here to speculate 

 on the possible import of this curious law ; which, if not fully esta- 

 blished, Faraday has rendered, at least, highly probable : 42 but it is 

 impossible not to see how closely it connects the Atomic with the 

 Electro-chemical Theory ; and in the connexion of these two great 

 members of Chemistry, is involved the prospect of its reaching wider 

 generalizations, and principles more profound than we have yet caught 

 sight of. 



As another example of this connexion, I will, finally, notice that 

 Faraday has employed his discoveries in order to decide, in some 

 doubtful cases, what is the true chemical equivalent ; 43 " I have such 

 conviction," he says, " that the power which governs electro-decom- 

 position and ordinary chemical attractions is the same ; and such con- 

 fidence in the overruling influence of those natural laws which render 

 the former definite, as to feel no hesitation in believing that the latter 

 must submit to them too. Such being the case, I can have no doubt 

 that, assuming hydrogen as 1, and dismissing small fractions for the 

 simplicity of expression, the equivalent number or atomic weight of 

 oxygen is 8, of chlorine 36, of bromine 78*4, of lead 103'5, of tin 59, 

 &c. ; notwithstanding that a very high authority doubles several of 

 these numbers." 



Sect. 4. Reception of the Electro-chemical Theory. 



THE epoch of establishment of the electro-chemical theory, like other 

 great scientific epochs, must have its sequel, the period of its reception 

 and confirmation, application and extension. In that period we 



42 Art. 697. 43 851. 



