M. Pouillet 071 the Electricity of Elastic Fluids. 53 



a very small spirit of wine lamp upon a common electroscope, 

 and at 5 or 6 feet above it, a stick of electrified rosin, or a 

 plate of glass, or any other body very feebly charged, at the in- 

 stant we behold a very great divergence in the plates; notwith- 

 standing the same body with the same electric charge would 

 give no sign of divergence if it was presented to the electroscope 

 without flame, and even at the distance of an inch. This ap- 

 paratus I have found very useful in discovering the smallest 

 trace of electricity, and it has made me understand all the ac- 

 cidents of which I have spoken. When we turn the plate of an 

 electrifying machine, the air of the room is electrified, and 

 the flame which ascends in that air, is charged at the instant 

 with electricity of the same name, and conveyed to the condenser. 

 A pile in action electrifies the air like a machine, and the flame of 

 the electroscope affords a proof of it ; a fire of charcoal, or even a 

 lighted candle, produces carbonic acid electrified positively; and 

 the flame of the electroscope betrays again the presence of this 

 electricity. In short, the atmospheric air is always electrified, 

 and if it penetrates into a room by an open window, and is re- 

 newed, I am certain that it can preserve its electrified condi- 

 tion for a sufficiently long time to cause great disturbance in 

 the inquiries which are making upon very weak quantities of 

 electricity. But there are means of excluding all these causes 

 of error, and it must be allowed that in all that follows they 

 have had no sort of influence upon the results. 



We now return to the combustion of hydrogen. The gas 

 flows out by a tube of glass ; the flame is vertical, presenting a 

 breadth of 4 or 5 lines upon a length of about 5 inches; the elec- 

 tricity is conducted to the condenser no longer by a plate of 

 brass, but by a platina wire, whose end is coiled into a spiral. 

 The spire is always vertical; but sometimes the circumvolutions 

 are of a diameter large enough to envelope the flame without 

 touching it, and sometimes they are small enough for the whole 

 spire to be completely enveloped in the interior of the flame. 



When we approach the flame from the exterior outline of 

 the spire, and keep it 10 millimetres distant, we obtain signs 

 of vitreous electricity. These signs become more and more 

 intense in proportion as the distance diminishes. But when 

 the flame touches the spire, the electrical signs become weak 



