Bacchus in Vacuo
   This pneumatic demonstration is in the Smithsonian Collection, and came from Middlebury College in Vermont. It originally cost $5.00.

   "Bacchus in Vacuo is an image mounted on a small brass barrel, which has a partition in the middle dividing it into two parts, one of which is open to the pressure of the atmosphere, while the other is closed, containing a quantity of water and air. A glass tube communicat- ing with the water in the closed end, passes up into the mouth, and down the neck of the image into the open end of the barrel. A small sheet rubber bag is concealed under the dress and contains a small portion of air which expands as the air around is rarefied". From the 1844 Catalogue of Pneumatic Instruments, published by N.B. and D. Chamberlain. 

   The cut from the catalogue at the right shows how the apparatus is placed under the bell jar of the vacuum pump.

   In later years the demonstration became debased and took the form of the diagram at the left, from a 1907 high school textbook by Carhart and Chute. It was still called the Bacchus Experiment, but all traces of the figure have disappeared. 

   Carhart and Chute wrote: "Select two bottles; fit to one of them a perforated stopper. Connect the two by a bent tube reaching nearly to the bottom of each. Fill the stoppered one nearly full of water and place them under a bell-jar on the air-pump table. Exhaust the air. Explain why the water flows out of the stoppered bottle and then flows back on admitting air into the bell-jar."

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