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FKEE CAL0K1C.

EM LEY.

1 admire this theory extremely*; but allow meto ask you one more question relative to it. Yousaid that when water was heated over the fire, theparticles at the bottom of the vessel ascended asgoon as heated,, in consequence of their specificlevity : why does not the same effect continuewhen the water boils, and is converted into steam ?and why does the steam rise from the surface, in-stead of the bottom of the liquid ?

MRS. B;

The steam or vapour does ascend from the bot-tom, though it seems to arise from the surface ofthe liquid. We shall boil some water in thisFlorence flask; (Plate IV. Fig. 5.) you willthen see, through the glass, that the vapour risesin bubbles from the bottom. We shall make itboil by means of a lamp, which is more conve-nient for this purpose than the chimney fire-

EMILY.

I see some small bubbles ascend, and a great

* This theory of the non-conducting power of fluids, notwith-standing all its plausibility, has been found, by a variety of sub-sequent experiments, to have been carried by Count Rumford rather too far; and it is now generally admitted that fluids arenot entirely destitute of conductihility, though they propagateheat chiefly by motion, in the manner just explained, and possessthe conducting power but in a very imperfect degree.