That, probably, would be carrying the speculation too far; I should rather think that water and caloric unite their efforts to dissolve a body, and that the difficulty or facility of effecting this, depend both on the degree of attraction of aggregation to be overcome, and on the arrangement of the particles which are more or less disposed to be divided and penetrated by the solvent. EMILY. But have not all liquids the same solvent power as water? MRS. B. The solvent power of other liquids varies according to their nature, and that of the substances submitted to their action. Most of these solvents, indeed, differ essentially from water, as they do not merely separate the integrant particles of the bodies which they dissolve, but attack their constituent principles by the power of chemical attraction, thus producing a true decomposition. These more complicated operations we must consider in another place, and confine our attention at present to the solutions by water and caloric. CAROLINE. But there are a variety of substances which, when dissolved in water, make it thick and muddy, and destroy its transparency. MRS. B. In this case it is not a solution, but simply a mixture. I shall show you the difference between a solution and a mixture, by putting some common salt into one glass of water, and some powder of chalk into another; both these substances are white, but their effect on the water will be very different. CAROLINE. Very different indeed! The salt entirely disappears and leaves the water transparent, whilst the chalk changes it into an opaque liquid like milk. EMILY. And would lumps of chalk and salt produce similar effects on water? MRS. B. Yes, but not so rapidly; salt is, indeed, soon melted though in a lump; but chalk, which does not mix so readily with water, would require a much greater length of time; I therefore preferred showing you the experiment with both substances reduced to powder, which does not in any respect alter their nature, but facilitates the operation merely by presenting a greater quantity of surface to the water. I must not forget to mention a very curious circumstance respecting solutions, which is, that a fluid is not nearly so much increased in bulk by holding a body in solution, as it would by mere mixture with the body. CAROLINE. That seems impossible; for two bodies cannot exist together in the same space. MRS. B. Two bodies may, by condensation, occupy less space when in union than when separate, and this I can show you by an easy experiment. This phial, which contains some salt, I shall fill with water, pouring it in quickly, so as not to dissolve much of the salt; and when it is quite full I cork it. --If I now shake the phial till the salt is dissolved, you will observe that it is no longer full. CAROLINE. I shall try to add a little more salt. --But now, you see, Mrs. B., the water runs over. MRS. B.