205 



to the earth by a difference amounting to several times the 

 difference of potentials (or electro motive force) between two 

 wires of one metal connected with the tw^o plates of a single 

 element of Daniell's. I have tested that the spirit lamp 

 ofives no idio-electric effect amountini]^ to so much as the 

 effect of a single cell. The electric effect observed is there- 

 fore not due to thermal or chemical action in the flame. It 

 cannot be due to contact electrifications of metallic or other 

 bodies in conductive communication with the walls, floor, or 

 ceiling, because the potentials of such must always fall short 

 of the difference of potentials produced by a single cell. I 

 have taken care to distinguish the observed natural effect 

 from anything that can be produced by electrical operations 

 for lecture or laboratory purposes. Thus I observe generally 

 in the morning before any electrical operations have been 

 performed, and find ordinarily results quite similar to those 

 observed on the Monday mornings when the electrical 

 machine has not been turned since the previous Friday. 

 The effect, when there has been no artificial disturbance, 

 has ahvays been found negative, except two or three times^ 

 since the middle of November ; but trustworthy observations 

 have not been made on more than a quarter of the number 

 of days. 



A few turns of the electrical machine, with a spirit 

 lamp on its prime conductor, or a slightly charged Leyden 

 phial, with its inside coating positive put in connection with 

 an insulated spirit lamp, is enough to reverse the common 

 negative indication. Another very striking way in which 

 this may be done is to put a negatively charged Leyden 

 phial below an uninsulated flame (a common gas burner, 

 for instance). The flame, becoming positively electrified by 

 induction, keeps throwing off, by the dynamic power of its 

 burning, portions of its own gaseous matter, and does not 

 allow them to be electrically attracted down to the Leyden 

 phial, but forces them to rise. These, on cooling, become. 



