Because the heat of the taper, whilst burning, produced a dilatation of the air in the vessel, which at first counteracted this effect.
Another means of decomposing the atmosphere is the oxygenation of certain metals. This process is very analogous to combustion; it is, indeed, only a more general term to express the combination of a body with oxygen.
CAROLINE.
In what respect, then, does it differ from combustion?
MRS. B.
The combination of oxygen in combustion is always accompanied by a disengagement of light and heat; whilst this circumstance is not a necessary consequence of simple oxygenation.
CAROLINE.
But how can a body absorb oxygen without the combination of the two electricities which produce caloric?
MRS. B.
Oxygen does not always present itself in a gaseous state; it is a constituent part of a vast number of bodies, both solid and liquid, in which it exists in a much denser state than in the atmosphere; and from these bodies it may be obtained without much disengagement of caloric. It may likewise, in some cases, be absorbed from the atmosphere without any sensible production of light and heat; for, if the process be slow, the caloric is disengaged in such small quantities, and so gradually, that it is not capable of producing either light or heat. In this case the absorption of oxygen is called oxygenation or oxydation, instead of combustion, as the production of sensible light and heat is essential to the latter.