I believe I do. Sublimation appears to consist in destroying, by means of heat, the attraction of aggregation of the particles of a solid body, which are thus volatilised; and as soon as they lose the caloric which produced that effect, they are deposited in the form of a fine powder. CAROLINE. It seems to me to be somewhat similar to the transformation of water into vapour, which returns to its liquid state when deprived of caloric. EMILY. There is this difference, however, that the sulphur does not return to its former state, since, instead of lumps, it changes to a fine powder. MRS. B. Chemically speaking, it is exactly the same substance, whether in the form of lump or powder. For if this powder be melted again by heat, it will, in cooling, be restored to the same solid state in which it was before its sublimation. CAROLINE. But if there be no real change, produced by the sublimation of the sulphur, what is the use of that operation? MRS. B. It divides the sulphur into very minute parts, and thus disposes it to enter more readily into combination with other bodies. It is used also as a means of purification. CAROLINE. Sublimation appears to me like the beginning of combustion, for the completion of which one circumstance only is wanting, the absorption of oxygen. MRS. B. But that circumstance is every thing. No essential alteration is produced in sulphur by sublimation; whilst in combustion it combines with the oxygen, and forms a new compound totally different in every respect from sulphur in its pure state. --We shall now _burn_ some sulphur, and you will see how very different the result will be. For this purpose I put a small quantity of flowers of sulphur into this cup, and place it in a dish, into which I have poured a little water: I now set fire to the sulphur with the point of this hot wire; for its combustion will not begin unless its temperature be considerably raised. --You see that it burns with a faint blueish flame; and as I invert over it this receiver, white fumes arise from the sulphur, and fill the vessel. --You will soon perceive that the water is rising within the receiver, a little above its level in the plate. --Well, Emily, can you account for this? EMILY. I suppose that the sulphur has absorbed the oxygen from the atmospherical air within the receiver, and that we shall find some oxygenated sulphur in the cup. As for the white smoke, I am quite at a loss to guess what it may be. MRS. B.