and ponderous as to give the most presumable indication 
of the secretion of metallic oxyde : this is afterwards ve- 
rified by fusing the mass with a mixture of dried chalk 
and charcoal, a globule of metal will be obtained, which 
evinces the richness of the scoria ; this, having lost its 
colouring principle (the metal), becomes clear and trans- 
parent. The results from these ores by fusion afford va- 
rious products, and lead to different conclusions : 1 shall 
mention several of them. 
The Cumberland iron ore, when introduced into a cru- 
cible without any additional mixture, fuses easily, and 
forms an opaque scoria, internally of a black colour, but 
towards the surface covered with fine shades of brown i 
this arises from a partial oxygenation of the semi-revived 
metal while cooling, and is often injured by a fresh com- 
bination of oxygen.* If the crucible remains sound, and 
the melted mass is kept in a state of extreme division for 
an hour, a considerable quantity of metal will be found 
precipitated, but so highly oxygenated as to shiver to 
pieces if exposed to air before it is entirely cooled. If, when 
the crucible is taken from the furnace, it be slightly incli- 
ned to one side, and the vitrified fluid entirely removed 
from the surface of the metal, a violent deflagration will 
immediately ensue, the ejected globules will be thrown 
three feet upwards from the mouth of the crucible : if the 
quantity of metal does not exceed 500 grains, it will total- 
ly disappear, except a rough dark-blue oxyde in the bot- 
tom of the crucible, not above i-4th of the original weight. 
The metal thus oxy dated* will be found in small spherules 
of a blackish colour, and spongy around the spot occupi- 
ed by the crucible. 
This curious appearance is in fact a combustion of iron 
by oxygen gas, furnished by the decomposition of atmos- 
pheric air : it is an operation which the accurate observer 
* By being exposed to the atmosphere. T. 
