40 
Dr. Eajon on Cryjlallization, 
in crude antimony, clearly fhew, that this fub* 
fiance, during its formation, has been a£led upon 
by fome caufe, either the fame, or feme other, 
very analogous to that, by which the precious 
(tones, bafaltes, &c. are made to cryftallize. * 
The fame thing is true with refped to bifmuth; 
and even pure fdver, during its paflage from a 
fluid to a folid flate, difeovers a tendency to form 
on its furface a number of Arise, which no doubt 
proceed from a difpofition of the metal to cryflal- 
lize, or arrange its particles in a particular order. 
The expanflon of water, during its freezing, 
is now univerfally allowed to be occafioned by 
the cryflallization of its parts. And, to me, it 
feems probable, that the expanflon of bifmuth 
and iron, in fimilar circumflances, proceeds from 
the fame caufe. -j- 
Lead ore, when tolerably pure, is generally 
found in mafles of a cubic form ; though, fome- 
times, in fhape of prifms. Perhaps this variety is 
* I obferved at Warrington (where copper ore is fmelted) 
the drofs and flux which fwim on the top of the metal 
ip the furnace in a liquid flate, are call into moulds in 
ihape of a double cube; thefe mafles, when cold, very 
much refemble Java or volcanic matter, and, when broken, 
evidently Ihew a cryftalline appearance in many parts, 
efpecially about the corners. 
f Figures call from melted iron are always very /harp, 
becaufe that metal expands as it cools, by which means the 
whole dye or mould is completely filled. 
owing 
