OXYGEN AND NITROGEN.

141

CAROLINE.

The water within the receiver has now risen alittle above its level in the bason. What is thereason of this ?

MRS. B.

With a little reflection, I dare say, you wouldhave explained it yourself. The water rises inconsequence of the oxygen gas within it havingbeen destroyed, or rather decomposed, by thecombustion of the taper; and the water did notrise immediately, because the heat of the taper,whilst burning, produced a dilatation ot the airin the vessel, which counteracted this effect.

Another means of decomposing the atmosphereis the oxygenation of certain metals. This pro-cess is very analogous to combustion ; it is, in-deed, only a more general term to express thecombination of a body with oxygen.

CAROLINE.

In what respect, then, does it differ from com-bustion ?

MRS. B.

The combination of oxygen in combustion isalways accompanied by a disengagement of lightand heat; whilst this circumstance is not a neces-sary consequence of simple oxygenation.