Volta's Pistol
   Volta's Pistol developed from the  Eudiometer, a device developed by Alessandro Volta in 1776-77 to study the "goodness" or oxygen content of air. 

   Volta himself suggested the construction of an inflammable air gun in which a spark fired a mixture of hydrogen and oxygen. By the middle of the 19th century the scientific instrument had turned into a piece of lecture demonstration apparatus. The loud bangs produced by these demonstrations as the cork stopper blew out of the end could awaken even the dullest students.

   The pistol at the left is in the apparatus collection of Edinburgh University, and was probably used by Lord Kelvin in his demonstration lectures.

   At the right is a Volta's pistol from Transylvania University.

   The electric cannon at the left is in the collection at St. Patrick's College in Maynooth, Ireland. In his catalogue of the collection, Dr. Charles Mollan suggests that it was bought in the era 1826-1864. 

   Two wires pass through the glass walls at the rear of the cannon to supply the spark to the hydrogen-air mixture. 

   The apparatus above might really be called Volta's Cannon, while the devices at the right look more like hand-held pistols. One of them even has the cork which holds in the oxy-hydrogen mixture preparatory to being set off by a spark from a Leiden jar.

   The upper piece of apparatus is at Glasgow University, and the lower one is from Miami University in Oxford, Ohio.


   If the devices above are Cannons and Pistols, then the two little pieces of apparatus below are Volta's Mortars, designed to pop the cork. Both of these are from Middlebury College. The one at the left has ivory insulation around the firing electrode. The one at the right, with its green paint and gold stripes, closely resembles the mortar shown in the 1854 catalogue of Chamberlain and Ritchie. 
   Another form of this apparatus is the Powder Bomb in which a spark is used to set off a charge of gunpowder.

REFERENCE: Thomas B. Greenslade, Jr., Volta's Pistol", Rittenhouse, 1, 55-57 (1987)

Return to Static Electricity Home Page | Return to Home Page