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 twenty to twenty-five in summer. To render this experiment more complete, we may introduce a small thermometer into the phial A, containing the ether, which will descend considerably during the evaporation.

The only effect produced in this experiment is, the taking away the weight of the atmosphere, which, in its ordinary state, presses on the surface of the ether; and the effects resulting from this removal evidently prove, that, in the ordinary temperature of the earth, ether would always exist in an aëriform state, but for the pressure of the atmosphere, and that the passing of the ether from the liquid to the aëriform state is accompanied by a considerable lessening of heat; because, during the evaporation, a part of the caloric, which was besore in a free state, or at least in equilibrio in the surrounding bodies, combines with the ether, and causes it to assume the aëriform state.

The same experiment succeeds with all evaporable ﬂuids, such as alkohol, water, and even mercury; with this difference, that the atmosphere formed in the receiver by alkohol only supports