238 Royal Society. 



contains a metal less electro-positive than the hydrocarbon radical, 

 I should expect that the hydrocarbon radical would be eliminated 

 by the action of sodium. Kakodyle, for instance, should give methyle 

 and arsenide of sodium. 



C,H3| ^' + Na/ -Na/^^ + C,H3 



A case in point is afforded by the reaction of the alkali-metals 

 with ammonia. 



2.H}N+|}=2.H}N+g} 

 Of the same kind is the reaction of zinc-ethyle upon ammonia*. 



To develope the hypothesis still further : just as the positive side 

 admits of displacement by a more electro-positive radical, so should 

 the negative side admit of displacement by a more electro-negative 

 body. 



The ordinary reactions of zinc-ethyle may be looked upon as illus- 

 trating this proposition, and can be written so as to exhibit a double 

 displacement. 



+ - +- +- + - 

 Zn, C,H,-fII=ZnH-C,H,I 



+ -+-+-+- 

 also ZnC,H. + 00=ZnO + C,H50 



Inspection will show in all these cases, that an electro-positive 

 radical displaces a less electro-positive radical ; and an electro-nega- 

 tive radical displaces a less electro-negative one. 



In accordance with the theory would be the displacement in 

 sodium-ethyle of the ethyle by mercury, or by copper, &c., plati- 

 num, &c. 



Na,C,H, , Cn_NaCn , C.H, 

 Na C,H, + Cn-NaCn'^'C,H, 



Also a like displacement by arsenic or by nitrogen would be ac- 

 cording to theory. 



Pushing the hypothesis to its furthest limits, I should say that 

 sodium-ethyle is only in equilibrium with bodies whose respective 

 electrical sides lie either both of them within, or both of them with- 

 out the space lying between the electro-positive sodium and the 

 electro-negative ethyle. 



'* SeeFrankIand'8paper,Trans.KoyalSoc.I857« 



