508 Prof. Marianini on the Currents produced by the 



Saline water being substituted for the spring water, a devia- 

 tion of five degrees was obtained. 



In order the better to assure myself of the insulation, I 

 twisted round the tube a band of lead covered with silk ; I 

 repeated the experiments several times, and the results were 

 always such as to lead to a conclusion that it was not neces- 

 sary that the electricity should pass through a metal to cause 

 the Leyden-electrical induction ; it being sufficient that it 

 should pass through some conductor, in order that the passage 

 might be accomplished with sufficient celerity. 



XXI. I connected the liquid contained in the tube which 

 was used in the experiments above described, with the ends 

 of the re-electrometric wire, and I then discharged the Leyden 

 jar upon the extremities of the band which surrounded the 

 tube itself. The needle deviated almost a degree. I renewed 

 the experiment ; but on repeating the same discharge in the 

 same direction six times, I found the needle deviated four de- 

 grees. Hence we see that it is not necessary that the actuated 

 conductor should be metallic, in order that the Leyden-elec- 

 trical induction should take place. 



From the experiments of this and the preceding paragraph, 

 it may be deduced, that the induction would take place if 

 neither the actuating nor the actuated conductor were metal- 

 lic ; which, I believe, I have also verified by apposite experi- 

 ments. 



XXII. Having interrupted the actuating wire in another 

 place, I connected one end of it with the external coating of a 

 Leyden jar not charged, and the other with the internal*. I 

 afterwards discharged a jar equal to that in power upon the 

 wire itself. The induction took place, and the charge was 

 divided between the two jars, which proves that it is not ne- 

 cessary that the identical fluid of one coating should pass to 

 the other, to produce the phsenomena of Leyden-electrical 

 induction. 



XXIII. Also the simple sparks drawn from the prime con- 

 ductor may produce currents by actuation. Whilst one of the 

 wires described in § XV. was connected with the re-electro- 

 metric coil, I let pass some sparks upon one extremity of the 

 other, keeping the other extremity in communication with the 

 ground ; and I observed some movement in the magnetized 

 needle at every spark that appeared. 



Once, with fifteen sparks directed upon the actuating wire, 

 a magnetization in the iron of the re-electromeler was obtained 

 with the induced currents, which caused the needle to deviate 

 three degrees. 



[* Armatura externa in the original) but obviously in error.— Edit.] 



