Dr. Schafhaeutl's Remarks on the Electricity of Steam. 449 



species in this class of animals, 'are shown by him to depend 

 both upon climate and upon soil, the structure of the country 

 (or geological conditions) having quite as much share in such 

 varied distribution, as the greatest diversity of temperature. 

 The Association has to thank the author for valuable tables, 

 which show both the distribution of the pulmoniferous mol- 

 lusca in our islands, and their relations to those of Europe 

 generally. 



[To be continued.] 



LXV. Remarks on the Electricity of Steam. By Dr. 

 CHARLES SCHAFHAEUTL*. 



HPHE discovery of a large quantity of free electricity in a 

 -*- jet of steam f is decidedly of great interest, but the cir- 

 cumstances under which this electricity is developed, are still 

 involved in such great mystery, that I cannot omit to call 

 the early attention of the experimenter to some points which 

 appear to me of primary importance. 



Is the electricity in the jet of steam developed by the simple 

 evaporation of water in the boiler, by the expansion of high- 

 pressure steam in the air, or by the condensation of the steam, 

 that is in its transition from the gaseous state to that in which 

 it begins to become visible? 



It would of course be easy to decide the first question by 

 cementing a glass tube containing a metallic wire into the 

 boiler, the inner portion of which being of course in contact 

 with the steam in the chamber, and precautions being taken 

 to prevent the escape of steam either into the cylinder or the 

 open air. 



If I recollect right, during the process of evaporation, the 

 evaporated part has been generally found to be negative elec- 

 tric in respect to the remaining liquid; during condensation 

 the reverse takes place. According to Mr. Armstrong's ac- 

 count, the electricity of the jet was positive, and seems there- 

 fore to correspond with the electricity developed by the pro- 

 cess of the condensation of steam. If we ascribe the elec- 

 tricity contained in the jet of steam simply to the evapo- 

 ration of the water in the boiler, the opposite electric state 

 of the boiler seems difficult to be explained by the laws of 

 common electricity, because there appears to me to be no 

 reason why the steam in contact with the inside of the iron 

 sheets of the boiler should not discharge its electricity the 



* Communicated by the Author. f See our last Number, pp. 370, 375. 

 Phil. Mag. S. 3. Vol. 17- No. 112. Dec. 1840. 2G 



