272 Remarkable Facts observed in 
had been exposed to the influence of the at- 
mosphere by cupellation. 
If silver in large quantities, after having 
been exposed in a melted state toa current of 
oxygen gas or atmospheric air, be allowed 
gradually to cool, the surface first becomes 
fixed or solid ; this soon bursts, ebullition en- 
sues, and an elastic vapour in considerable 
quantity escapes, driving before it a portion . 
of the internal fluid metal, which becoming 
solid as it is brought to the surface, produces 
the protuberances as shown by the accompa- 
nying specimen, No. 1. This ebullition con- 
tinues from 2 to an hour or more, accord- 
ing to the quantity of silver, and the rapidity 
with which it is cooled. 
If, instead of cooling gradually, it be made 
to assume the solid state suddenly by pouring 
it into water, still the same phenomena occur ; 
an ebullition takes place, and oxygen gas is 
evolved ; but as the silver is so much divided’ 
and passes so suddenly from the fluid to a 
solid state, the protuberances are proportion- 
ably minute, and are spread more equally 
over the whole surface, as will be seen in spe- 
cimen No. 2. 
No. 3, shews the arrangement of erystalli- 
zation, which the silver assumes when the 
gas is separated from it, during the time of 
its becoming solid. 
