402 
MR. R. W. FOX ON THE ELECTRO-MAGNETIC PROPERTIES 
considerable energy, so as even to cause the needle to revolve with some velo- 
city. 
In connection with the electricity of veins, I deemed it desirable to ascer- 
tain the relative power of conducting galvanic electricity possessed by many 
of the metalliferous minerals ; and it appeared to be in about the following 
order, viz. 
Conductors . 
Copper nickel, 
C Purple copper, 
< Yellow sulphuret of ditto, 
(^Vitreous ditto, 
Sulphuret of iron. 
Arsenical pyrites, 
Sulphuret of lead. 
Arsenical cobalt, 
Crystallized black oxide of manganese, 
Tennantite, 
Fahlerz. 
lery imperfect conductors. 
Sulphuret of molybdenum, 
Sulphuret of tin, or rather bell-metal ore. 
Non-conductors. 
Sulphuret of silver. 
Ditto of mercury, 
Ditto of antimony, 
Ditto of bismuth, 
Cupriferous ditto, 
Realgar, 
Sulphuret of manganese, 
Ditto of zinc, 
Mineral combinations of metals with oxygen, and with acids. 
