Mr Rowell on the Electricity of Steam. 349 



boiler ; but it fully agrees with the hypothesis that the pheno- 

 menon is caused by the expansion and contraction of the par- 

 ticles of steam. 



All the experiments on the subject shew, that the steam 

 within the boiler is not electrified, and that the electrical 

 development takes place on its escape from the mouth of 

 the tube. At this point, there is an enormous expansion of 

 the steam ; and it then takes up its portion of electricity, 

 according to its expanded surface, in the same proportion as 

 the electrical state of the boiler, or rather the issue tube. If 

 the boiler or tube be insulated, they will be rendered nega- 

 tive ; the steam at this point is so also ; but, as it begins im- 

 mediately to condense, it is, at a short distance, neutral; 

 and, on a further condensation, and consequent diminution of 

 surface, the steam becomes positively electrified. 



The cause of the increase, through friction, of the electri- 

 city of steam, is probably from its bringing a greater quantity 

 of the steam in contact with the issue tube ; thus enabling a 

 greater portion of the steam to take up its coating of electri- 

 city than could be the case if escaping from a round smooth 

 aperture ; as, in that case, owing to the non-conducting powers 

 of high pressure steam, only the exterior particles of the 

 column of steam could take their full coating of electricity. 



The presence of water in the tube may increase the elec- 

 trical development, by rendering the connecting and issue tube 

 a better conductor of electricity from the boiler to the mouth 

 of the issue tube. 



The necessity for the issue tube being a good conductor of 

 electricity is shewn by the experiments of Dr Faraday, who 

 says, " A metal, glass, or box-wood tube, well soaked in distil- 

 led water, being used for the steam issue, the boiler was ren- 

 dered well negative, and the steam highly positive ; but if a 

 quill or an ivory tube be used, the boiler received scarcely any 

 change^ and the stream of steam is also in a neutral state.'' 



This must be owing to the difi^erence in the conducting 

 power of the various tubes, and not to the difference in the 

 friction they occasion, as metal, wood when well soaked in 

 water, and glass, from its becoming damp from the steam, are 

 good conductors, and would supply the escaping steam with 

 electricity ; but quill and ivory being non-conductors, and hav- 



