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 two plates of a single 
element of Daniell’s. I have tested that the spirit lamp 
gives no idio-electric effect amounting 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 he 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 
c\f the difference of potentials produced by a single cell. I 
h#ive 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 always been found negative, except tioo 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 he electrically attracted down to the Leyden 
phial, but forces them to rise. These, on cooling, become. 
( 
