ELECTRIC JAR CHARGED BY STEAM. 163 



cock, Fig. 59, instead of the sensation of scalding 

 heat, rather a cooling breeze was felt. The heat 

 of the steam at 300 Fahr. disappears so instanta- 

 neously, that a thermometer held in it indicates 

 only 120 ; showing that 180 of the heat has van- 

 ished. The question occurred, " What becomes 

 of all the heat of this discharged steam ? " This 

 led tq a course of experiments. Forked pointed 

 wires were arranged on a metallic rod, as at A, 

 Fig. 59, and the other end of the metallic rod 

 was then inserted through the cover of the elec- 

 tric jar B. This apparatus was held in front of the 

 condensing steam from a boiler, with seventy-five 

 pounds pressure to the inch. The coated glass-jar 

 received and retained the electric excitation trans- 

 mitted from the steam discharged into the open 

 air. A cold day was selected for more sudden con- 

 densation of the steam. On holding the pointed 

 wires in front of the jet of steam, the jar was 

 speedily charged, and transmitted a shock with a 

 bright spark, when touched by the finger. The 

 shocks were not only felt through the arms of 

 the experimenter, but also through the knees an.d 

 feet of the bystanders on the brick hearth in front 

 of the boilers. 1 



This experiment showed the general diffusion 

 of the electric excitation through the adjacent air. 

 The workmen amused themselves in taking shocks, 



1 An account of the experiment was published in Allen's " Philosophy 

 of Mechanics," p. 38, in 1851. 



