Chemical Science. 109 



Chester, I mentioned having observed that pure silver, when 

 melted, and while in a fluid state, had the property of uniting 

 with a small proportion of oxygen, not only from the atmosphere, 

 but also from other bodies which gave it out at a suitable degree 

 of heat, as some of the nitrates for instance ; and that the oxy- 

 gen thus absorbed remains united with the silver only so long as 

 it continues in a fluid state, or while fluid, until some substance 

 be applied, having a more powerful attraction for the oxygen. 

 In proof of this, I now sen.1, for your inspection, a few specimens 

 of silver that has been in the difFerent states, and which carry 

 the external marks : and also a bottle of the gas collected from 

 silver, which had been exposed to the influence of the atmosphere 

 by cupellation. 



If silver in large quantities, after having been exposed in a 

 melted state to a current of oxygen gas or atmospheric air, be 

 allowed gradually to cool, the surface first becomes fixed or 

 solid ; this soon bursts, ebullition ensues, and an elastic vapour 

 in considerable quantity escapes, driving before it a portion of 

 the internal fluid metal, which, becoming solid as it is brouo-ht 

 to the surface, produces the protuberances as shewn by the ac- 

 companying specimen. No. 1. This ebullition continues from 

 J to 1 an hour or more, according 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 proportionably 

 minute, and are spread more equally over the whole surface, as 

 will be seen in specimen No. 2. 



No. 3 shews the arrangement of crystallization, which the 

 silver assumes when the gas is separated from it, during the time 

 of its becoming solid. 



I have before observed, that substances having a potyerful 

 affinity for oxygen, will take it from the silver, even while in a 

 fluid state. Thus, if charcoal be spread, for a lew niomcntti 

 only, on the surface of silver tiiatlms absorbed oxygen, the whole 



