[ 39 ] 



II. Note on the Electrical Relations of certain Metals and Metalliferous Minerals. 

 By R. W. Fox. Communicated by Davies Gilbert, Esq. F.R.S. 



Received and read January 15th, 1835. 



I HAVE ascertained that the crystallized grey oxide of manganese holds a much 

 higher place in the electro-negative scale than any other body with which I have com- 

 pared it, when immersed in various acids, and alkaline solutions ; and the other metals 

 and minerals which I have examined, appear to rank after it in the following order : 

 Manganese. 



1 



These five hold nearly the same place, varying in their mu- 

 tual relations according to the time of their remaining im- 

 ^mersed, and the nature of the liquid. 



The same may in some degree be said of the three other 

 bodies included in the larger bracket. 



Rhodium. 



Loadstone. 



Platina. )> 



Arsenical pyrites. | 



Plumbago. J 



Iron pyrites. 



Arsenical cobalt. 



Copper pyrites. 



Purple copper. 



Galena. 



Standard gold. 



Copper nickel. 



Vitreous copper. 



Silver. 



Copper. 



Pan brass. 



Sheet iron. 



I have also compared the action of different metalliferous combinations in various 

 diluted acids, &c. on the needle of the galvanometer, and some of the results are given 

 in the following Table, in which cases sea-water, and also muriatic acid diluted with 

 thirty-two parts of water, were employed. The figures show the angles of deflection 

 observed when the needle became stationary, which may serve to give some idea of 

 the relative effect of the combinations in question on the needle ; but I find that the 

 results are often considerably modified by the bodies being exposed for a longer or 

 shorter time to the action of the acids, &c. ; indeed this is so remarkable in the case 

 of copper with zinc, that the needle often moves back much more than ten degrees 

 from its maximum angle of deflection in one or two minutes after immersion; 

 whereas in the case of iron with zinc, for example, the immediate retrograde motion 



