

ELECTRO-CHEMICAL PRINCIPLES. 155 



which, in fact, is simply juxta-position, and is destroyed when 



the surfaces are separated, and each appears again in possession 



of its original electric state. When heterogeneous atoms com- Heterogene- 

 ,.,., , ..., i.- • ous particles 



bine (whether the combination do consist simply in juxta-posi- seem to una j 



tion, or, which is more difficult to comprehend, in a partial or by a discharge 



a. i \ f t* i. « i ot electricity 



total penetration) they appear to adjust or dispose themselves so with prtK j U c' 



as to touch with the opposite poles ; of which the electricities tion of heat, 

 produce a discharge which causes the phenomenon of elevation 

 of temperature, almost constantly apparent at the time of any- 

 chemical combination, and the particles remain combined 

 until their discharged poles are, by some means or other, re- 

 stored to their former electric state. 



As we know, from fact and experience, that bodies of the The affinity 

 same electro-chemical class (that is to say, bodies in which we ^^^ |{|? rC 

 conceive that the same pole predominates) can combine, it tensity of the 

 appears, that the force of affinity depends rather on the in- ^""haifu oa 

 tensity of the general polarity, than of the specific unipolarity ; the 'excess ia 

 and from this reason it may be, that sulphur has more affinity one P ole be " 

 with oxigen, than gold or platina has, although sulphur has the other, 

 same unipolarity as oxigen, and those metals have an opposite 

 unipolarity to that of oxigen. 



It is clear, th3t when two bodies, in which the same pole When bodies, 

 predominates, combine together, the new particle must possess g^m "predomi. 

 their unipolar force concentrated in one of ks poles, and must, nating pole, 

 consequently, have electro-chemical properties more intense 5 gj*™^ 1 " che-* 

 and this is a good reason why sulphur and oxigen produce the mical property 

 strongest acid. On the contrary, when particles possessing an °o„, 1 d wilVbe 

 opposite polarity unite, the polarity of one of the particles more intense ; 

 most frequently predominates j for example, in potash, and in and vlce versa - 

 most of the metallic oxides, the predominating pole of the 

 metal also predominates in the compound. In some instances, 

 the product is a neutral compound, in which neither of the 

 poles predominate, such as the superoxides : in other instances, 

 the pole of the metal predominates in one degree of oxidation, 

 and that of the oxigen in another. 



The combination of polarized atoms requires a motion to Polarized 



turn the opposite poles to each other -, and to this circumstance J u ^\* otac j, 



is owing the facility with which combination takes place when other in order 



one of the two bodies is in the liquid state, or where both are l ° con V I * ie - 



1 his will oe 



in that state ; and the extreme difficulty, or Ifcarly impossibility, -a»ily done if 



M2 of 



