463 
We may assume that it is only the pure lead which 
possesses this tendency to crystallize, and that the silver or 
copper found in every sample of the crystals is really only 
contained in the fluid alloy, entangled, so to speak, amongst the 
crystals. This will be readily granted on consideration of the 
imperfect separation of the solid and fluid particles obtained 
by simple draining in a perforated ladle. 
Pursuing the operation in this manner, we obtain on the 
one hand, crystals increasing in purity and freedom from 
foreign metals ; on the other, lead increasing in richness of 
silver and (as will be shewn,) of copper. 
The fracture and other physical qualities of such kinds of 
lead present marked differences. As the crystals are purer, 
they are darker in appearance ; those from the rich pot being 
sometimes of a silvery whiteness. 
Annexed is a tabular view of a series of analysis which 
will at once shew that a similar law regulates the separation 
of copper as of silver from lead ; that is to say : — there is an 
alloy of copper and lead which remains fluid at a temperature 
at which crystals of pure lead are formed. Iron, it will be 
seen, cannot be removed by this method, but is chiefly 
separated by oxidation, and subsequent skimming the surface 
of melted metal : — 
In 100 Parts. 
Eich Pot. 
Silver. 
Copper. 
Iron. 
1 Before Crystallizing 
.0108 ... 
... .0344 ... 
... .0312 
.0052 ... 
... .0152 ... 
... .0086 
3 Fluid Lead — 85 parts... 
.0140 ... 
... .0476 ... 
... .0122 
Second Pot. 
.0052 ... 
... .0154 ... 
5 Crystals — 95 parts 
.0020 ... 
... .0066 ... 
... .0118 
6 Fluid Lead— 25 parts ... 
.0126 ... 
... .0286 ... 
... .0146 
Third Pot. 
.0020 ... 
... .0102 ... 
... .0118 
.0010 ... 
... .0038 ... 
... .0198 
9 Fluid Lead — 25 parts ... 
.0100 ... 
... .0240 ... 
... .0082 
Fourth Pot. 
.0014 ... 
... .0054 ... 
... .0112 
