MAGNETIC CHARACTERS OF METALS, &c. 651 
piece of pure silver, were fused in an earthenware 
crucible, and run out upon a sheet of copper. 
The copper in this alloy was about one to five of 
silver, which is more than twice the proportion of 
that in the standard coinage. On subjecting this 
mass to the torsion magneto-scope, it was found 
to be more highly magnetic than the old half- 
crown of William and Mary (29.) 
33. This singular result has cost me much 
thought and a great deal of trouble. The crucible 
employed was quite clean, having never been used 
before ; and its contents during the time it was 
in the fire were the silver and copper, and a 
mixture of pulverized charcoal and common salt. 
Similar pieces of charcoal and slices of the same 
quality of salt have been tested, but no magnetic 
action could be detected in either. Whence, 
then, this almost unexpected magnetism in the 
metallic alloy ? Fragments of a broken crucible 
similar to that used were found to be slightly 
magnetic, probably from a portion of iron in the 
clay of which it was formed: but the magnetic 
action in the fragment of the crucible was not 
nearly so great as that displayed by the alloy. 
Moreover, the pure portion of the silver that 
entered the alloy had previously been fused in a 
