370 Miscellaneous Intelligence . 
powerfully; but if the lamp be touched with’a negative pole or 
coating, no divergence, or only a very slight one, will take place. 
The following table will illustrate the difference of effect when the 
lamp was postive and negative. ‘The first column is the number of 
inches between the lamp and the screen above. 
Lamp positive. ‘ Lamp negative. 
1 inch The leaves opened to their full The leaves opened 
extent (14 lines) in 1” and dis- — the 14 lines in 345” 
charged themselves against the 
side every second. 
ost Ditto in 14" 345” 
3 5 (0:98 540” 
4» as leaves diverged one 
line in 150° and only 
diverged 24 lines on 
the whole. 
5", rset 1 line in 210” total 
divergence 14 lines. 
Gigs 39. ah! 1 line in 240” total 
divergeace 1 line. 
A similar, but inverted table would represent the progress of 
the electrometer attached to the lamp, the screen being similarly 
electrified. 
There exists, therefore, incontestibly a reciprocity of conducting 
and insulating actions ; the lamp conducts and transmits the positive 
effect tothe screen, but not the negative ; on the contrary, the screen 
transmits the negative effect to the lamp, but not the positive. This 
singular property is found to exist in all the combinations of this 
kind which can be imagined. ‘Thus, for example, if a Leyden jar is 
moderately charged positive by its ball, and this applied to the 
insulated aphlogistic lamp, a smaller Leyden jar, with its ball held 
about four or six inches trom the incandescent platina, will become 
very sensibly charged; but if the ball of the first be electrized ne- 
gatively, there will be no charge given to the second, on iepeating 
the experiment. By disposing successively a number of electro- 
meters, each with its aphlogistic lamp, so as to establish a communi- 
cation from one to the other, a very paradoxical system is obtained, 
representing a species of pile which is rapidly traversed by positive 
electricity from right to left, but not at all in the opposite direction, 
whilst with negative electricity the inverse directions are equally 
distinct: though as the author has not succeeded in increasing the 
effect by the successive groups, it has perhaps more analogy with the 
tourmaline. Electro-magnetic phenomena were not known at the 
time when M. Erman discovered the reciprocity of insulating and 
conducting action, and he has not as yet published the result of 
his ultimate researches on the electro-magnetic effects of incandescent 
platina, 
