[ 95 ] 



XVIII. 0?i the Circumstances under 'which Steam developes Po- 

 sitive Electricity. By Dr. Charles Schafhaeutl*. 



TN a conversation with Mr. Bradley of the Adelaide Gallery, 

 *■ he informed me that steam issuing under a pressure of 

 about 40 atmospheres, from the boilers of Mr. Perkins's 

 steam-gun, was able only slightly to move the gold leaves of a 

 voltaic condenser. On my expressing an opinion that the 

 electricity of the issuing steam had some relation to tlie form- 

 ation of the deposit or incrustation in the boiler, he invited 

 me to make some experiments at the Adelaide Gallery, in 

 order, if possible, to elucidate this point. 



As Mr. Perkins's boiler is constructed so as to prevent 

 any incrustation forming, I selected for my experiments a 

 common Marcet boiler, consisting of a globular iron vessel 

 about 5 inches diameter, in the vertical axis of which is 

 inserted a mercuiial gauge, and at an angle of 45 degrees 

 from it, a thermometer on one side, and on the other side a 

 jet, with a stop-cock. The lower part of the boiler was of 

 course occupied by quicksilver, on the top of which distilled 

 water was poured to the height of 1^ inch. In the direction 

 of the jet a glass bell was suspended of 9 inches diameter 

 and 5 inches in depth, so that the distance of the top of the 

 bell from the orifice of the jet was about 9 inches. A bundle 

 of copper wire was then attached at one end to the disc of a 

 voltaic condenser, and the other end was spread out and in- 

 serted in the glass bell. The water in the boiler was then 

 brought to a state of ebullition, and when the mercurial 

 column had risen to 31 inches, the stop-cock of the jet was 

 opened, the issuing steam condensed in the glass bell in great 

 quantities, and the gold leaves of the voltaic condenser after 

 the first few seconds separated instantaneously to their full 

 extent, even under a pressure of 23 inches. This was like- 

 wise the case when the condensing plate was removed from 

 the electroscope, and the gold leaves were always found posi- 

 tive electrified. 



The steam under the same pressure directed against the 

 copper wires without the bell was found to exhibit no trace 

 of electricity. 



The distilled water, which had assumed a red colour from 

 the hydrate of oxide of iron derived from the inside of the 

 boiler, was nov/ ciianged for a saturated solution of common 

 salt, which occupied a space of about three (|uartersof an inch 

 on the top of the quicksilver ; the other part of the experiment 



• Communicated by the Author, wliosc former communications on the 

 subject will be found in vol. xvii. p. 44'J, and in our last Number, pres. 

 vol. p. 14. 



