In August 1657, the members of the Accademia del Cimento tested the behavior of a bladder placed in a bell-jar in which a vacuum had been formed. The experiment was a direct application of Torricelli's well-known experiment of 1644.

The members of the Academy sealed the bell-jar placed at the end of the barometer tube with a lid, to which they attached what they described as an "almost totally deflated" lamb's bladder. They shut the lower end of the barometer apparatus with a membrane and poured the mercury through the funnel into the tube until it was completely filled. Lastly, they closed the upper end of the lid with another membrane. They immersed the barometer tube in the mercury-filled vat and removed the seal placed on the lower end. They observed that, at the same time as the mercury's partial descent into the vat, the mercury "magically" began to swell. This was due to the fact that, in the vacuum created by the falling mercury, the small amount of air inside the deflated bladder expanded as it was no longer offset by the ambient air pressure.

The experimenters also produced the reverse proof of the basis for this explanation. When the upper end of the lid was reopened, the air re-entered the bell. The bladder instantly collapsed and the mercury remaining in the tube fell immediately into the vat below.