446 Notice of some Recent 



experiments which go to prove this position. Having 

 placed an electrometer upon an isolated horizontal con- 

 ductor, he found by a mean of 3 trials, that after having 

 electrified the conductor with positive electricity, the 

 electrometer took 10 minutes and 2 seconds to descend 

 from 20° to 10°. With negative electricity, the electro- 

 meter only required 4 minutes and 30 seconds to pass over 

 the same number of degrees, under precisely the same cir- 

 cumstances. He infers, that the force generally less which 

 negative electricity furnished by a machine possesses, com- 

 pared to that of the positive electricity which the same 

 machine furnishes, does not depend alone on the less ad- 

 vantageous disposition of the conductors destined to collect 

 the first electricity, but also on the more ready loss which 

 it sustains."*^ 



Electric spark obtained from the Torpedo. — The attempts 

 which Dr. Davy made to obtain a spark from the torpedo 

 were not attended with success {Records, vol. i. 306.) M. 

 Matteucci has, however, been fortunately successful in his 

 trials. He employed for this purpose an apparatus perfectly 

 similar to that employed by Mr. Faraday for obtaining a spark 

 by means of a single voltaic pair. The principle object of 

 this arrangement is to prevent the electricities from being 

 neutralized directly by the medium of the conducting body 

 which developes them, and of forcing them to unite ex- 

 teriorly across the thin layer of air where the spark is pro- 

 duced. Matteucci has also succeeded in magnetizing steel 

 needles in the same manner."^ In a letter from Matteucci, 

 read by Donne before the Institute, we learn that an elec- 

 trical discharge may be obtained from the torpedo, although 

 the skin of the organ be removed, and, even when portions 

 of the substance of the electrical apparatus have been cut 

 away. When the torpedo does not discharge electricity, 

 it is impossible to obtain, even in the interior of the organ, 

 the least trace of electricity in any point whatever, either 

 with the galvanometer or condenser. The intensity of the 

 shock is reduced by diminishing the number of nervous 

 filaments which go to the organ. In the act of discharging, 

 the electrical current always passes from the back to the 

 belly. Three grains of muriate of morphin introduced 



* JJibliotheque Universelle, June, 1836. 



