EMILY.
I see them perfectly; but I wonder that they have sufficient power to force themselves through the water.
CAROLINE.
They must rise, you know, from their specific levity.
MRS. B.
You are right, Caroline; but vapour has not in all liquids (when brought to the degree of vaporization) the power of overcoming the pressure of the less heated surface. Metals, for instance, mercury excepted, evaporate only from the surface; therefore no vapour will ascend from them till the degree of heat which is necessary to form it has reached the surface; that is to say, till the whole of the liquid is brought to a state of ebullition.
EMILY.
I have observed that steam, immediately issuing from the spout of a teakettle, is less visible than at a further distance from it; yet it must be more dense when it first evaporates, than when it begins to diffuse itself in the air.
MRS. B.
When the steam is first formed, it is so perfectly dissolved by caloric, as to be invisible. In order however to understand this, it will be necessary for me to enter into some explanation respecting the nature of SOLUTION. Solution takes place whenever a body is melted in a fluid. In this operation the body is reduced to such a minute state of division by the fluid, as to become invisible in it, and to partake of its fluidity; but in common solutions this happens without any decomposition, the body being only divided into its integrant particles by the fluid in which it is melted.