The condensing electroscope is an ordinary gold-leaf electroscope with an addition: the top is made into an electrophorus. The electrophorus was invented in 1782 by Alessandro Volta (who also invented the electrochemical battery). By putting the static electricity into a capacitor, the charge transfer from the object being tested was much more complete. Then, by removing half of the capacitor (seen lower left in this image) the voltage would soar and the leaves would diverge much more strongly.

The two metal uprights inside the glass jar shield the gold leaf, from any static electricity that might exist on the glass jar, from rubbing during handling.

The condensing electroscope was the only device available in the early 19th century that could react to the electricity given off by a voltaic pile. This showed that the new Voltaic electricity was the same as the old static electricity.

The picture below is excerpted from "Volta Before the First Consul" (a colored engraving by Ducollet, after Més, n.d.). It shows Volta demonstrating, before Napoleon and his court, the "animal electricity" of Galvani, and the Voltaic Pile. The instruments on the table include a condensing electroscope, and the demonstration is clearly designed to show that Galvani's electricity is related to the static electricity of the eighteenth century.

Museum Hours: Tuesday - Saturday 10 to 5
Thursdays 10 am to  8pm 
Closed Major Holidays
Library Hours: Monday - Friday 9 to 4:30

Admission: $7 Adults; $5 Students & Seniors; Children 3 and under are FREE!

© The Bakken Updated: April 6, 2007