642 EXPERIMENTAL INVESTIGATION OF THE 
tin, antimony, lead, zinc, bismuth, and mercury ; 
and also some of their alloys and salts. In none 
of these metals, when in a state of purity, have I 
been able to discover the slightest trace of mag- 
netic action, though in several specimens of some 
of them, as they appear in a commercial state, 
magnetic action is strongly developed. 
18. A bar of bismuth, for instance, cast from a 
mass fused in an earthenware crucible, was found 
to be highly magnetic, and, for a while, was con- 
sidered as a good specimen of the magnetic action 
of that metal; but on examining another bar cast 
from the remaining portion in the crucible, and 
finding it still more powerfully magnetic than the 
former, a suspicion was aroused that either their 
crystalline structures were different to each other 
or that the metal was not pure. The experi- 
mental inquiries which this suspicion occasioned, 
led to the detection of localities in the two bars 
in which the magnetic actions were more power- 
ful than in other parts of them, which gave rise 
to the determination of sweating one of the bars 
at a low heat, and running out of the crucible the 
most easily fused portions, before the rest became 
fluid, which is an excellent process for freeing 
