190 



THE DEPOSITION OF SMOKE AND DUST. 



from one electrode of the electrical machine (the other elec- 

 trode being put to earth) to a volume of smoke as it issues 

 from a small model furnace, the smoke is simply forced 

 again down the flue, while the effect produced by presenting 

 a collection of points is to condense the smoke. 



If smoke bo confined within a bell jar, the effect of an 

 electrical discharge upon it can be the better observed as 

 the smoko is in a state of perfect equilibrium, and the result 

 of any stress sot up in its midst is at onco apparent. 



If an electrical discharge bo made to take place within 

 the bell jar, the confined smoke becomes greatly agitated, 

 finally disappearing, leaving a thin white film covering 

 the whole of the interior of the jar and the electrodes. A 

 precisely similar eii'eot is observed if the discharge be made 

 upon smoke in motion, for which, experiment the smoke 

 may be generated in a temporary furnace connected by 

 means of a short flue to a glass compartment in which the 

 electrodes are placed. The smoko may be generated by 

 placing liquor ammonias in doso proximity to burning sul- 

 phur or by burning 7-inc filings. 



As to the utility of the remarkable property which an 

 electrostatic discharge possesses over a smoke and dust- 

 laden atmosphere, it is perhaps too early to speak ; but it 

 has been applied on a largo scale at some lead works in 

 this country, and has met with some degree of success. 



It has hitherto been the custom at some works to lead 

 the fumo through miles of flue, in order to arrest and de- 

 posit the fine particles of sulphide of lead of which it is 

 mainly composed, and it has been thought by some that 

 could an electric discharge be brought to bear upon the 

 fume, the deposition would be effected in a less expensive 

 and at the same time more expeditious manner. 



Various devices have been hitherto adopted to arrest the 



